Claims:We claim:
1. A motor control unit (MCU) (300) of an electric vehicle for increasing time of motor lock operation, the traction motor control unit (MCU) (300) comprising:
a motor lock detection unit (310) configured to detect a motor lock condition when acceleration actuation amount is greater than zero and vehicle speed is zero;
a temperature of winding, rotor position, and torque determining unit (312) configured to:
determine temperature (Tpu, Tpv, Tpw) of each winding (u, v, w) of a three-phase traction motor (103) by temperature sensors coupled with the each winding (u,v,w);
determine rotor position based on inputs received from a rotor position sensor;
determine a torque applied by the motor;
generate a series of motor lock in and lock out map based on the determined torque; and
a coolant flow control unit (314) configured to regulate the coolant flow when difference of temperature between threshold temperature (To) and determined temperature (Tp) of locked phase is greater than a pre-stored calibrated temperature (Tc) and current coolant flow is less than permissible limit (P1) to decrease the determined temperature of the locked phase.

2. The motor control unit (MCU) (300) as claimed in claim 1, wherein the motor control unit (MCU) (300) comprises a motor locked phase control unit (316) configured to change locked phase of the three-phase motor (103) to next phase as per the generated motor lock in and lock out map when:
difference of temperature between threshold temperature (To) and determined temperature (Tp) of locked phase is less than a pre-stored calibrated temperature (Tc) and determined temperature (Tpu, Tpv, Tpw) of at least one of the winding (u, v, w) of the three-phase traction motor (103) is less than a pre-stored second calibrated temperature (Tc1).

3. The motor control unit (MCU) (300) as claimed in claim 1, wherein the motor control unit (MCU) (300) comprises an automatic brake actuation control unit (318) is configured to:
display a timer on instrument panel to apply brake within a predefined time span when the current coolant flow is equal to or greater than a permissible coolant flow limit (P1); and
apply automatic brake when no manual brake is applied and the timer on the instrument panel is equal to zero.

4. The motor control unit (MCU) (300) as claimed in claim 2, wherein the motor control unit (MCU) (300) comprises an automatic brake actuation control unit (318) is configured to:
display a timer on instrument panel to apply brake within a predefined time span when determined temperature (Tpu, Tpv, Tpw) of each winding (u, v, w) of the three-phase traction motor (103) is greater than or equal to a pre-stored second calibrated temperature (Tc1), and
apply automatic brake when no manual brake is applied and the timer on the instrument panel is equal to zero.

5. The motor control unit (MCU) (300) as claimed in claim 1, wherein the coolant flow control unit (314) is coupled with a vehicle control unit (VCU) (105) to receive the current coolant flow and give coolant flow input (205) to regulate the coolant flow to cool the windings of the three phase motor (103).

6. The traction motor control unit (MCU) (300) as claimed in claim 1, wherein the series of motor lock in and lock out map is generated based on the temperature of the other two phases and rotor position.

7. A method (400) for increasing time of motor lock operation of a three-phase traction motor (103) during driving on an upward slope, the method (400) comprising:
detecting (402), by a motor lock detection unit (310), a motor lock condition when acceleration actuation amount is greater than zero and vehicle speed is zero;
determining (404), by a temperature of winding, rotor position, and torque determining unit (312), temperature (Tpu, Tpv, Tpw) of each winding (u, v, w) of a three-phase traction motor (103) by temperature sensors coupled with the each winding (u,v,w), a rotor position based on inputs received from a rotor position sensor, and a torque applied by the motor based on the percentage press of accelerator pedal, and coolant temperature and coolant flow from a vehicle control unit (VCU) (105);
generating a series of motor lock in and lock out map based on the determined torque,
regulating (410), by a coolant flow control unit (314), the coolant flow when difference of temperature between threshold temperature (To) and determined temperature (Tp) of locked phase is greater than a pre-stored calibrated temperature (Tc) and current coolant flow is less than permissible limit (P1) to decrease the determined temperature of the locked phase.

8. The method (400) as claimed in claim 7, wherein the method comprises:
changing (414), by a motor locked phase control unit (316), locked phase of the three-phase motor (103) to next phase as per the generated motor lock in and lock out map when:
difference of temperature between threshold temperature (To) and determined temperature (Tp) of locked phase is less than a pre-stored calibrated temperature (Tc) and determined temperature (Tpu, Tpv, Tpw) of at least one of the winding (u, v, w) of the three-phase traction motor (103) is less than a pre-stored second calibrated temperature (Tc1).

9. The method (400) as claimed in claim 7, wherein the method comprises:
displaying (416) a timer on instrument panel instructing to apply brake within a predefined time span when the current coolant flow is greater than or equal to permissible coolant flow limit (P1); and
applying (424), by an automatic brake control unit (318), automatic brake when no manual brake is applied and the timer on the instrument panel is equal to zero.

10. The method (400) as claimed in claim 8, wherein the method comprises:
displaying (416) a timer on instrument panel instructing to apply brake within a predefined time span when determined temperature (Tpu, Tpv, Tpw) of each winding (u, v, w) of the three-phase traction motor (103) is greater than or equal to a pre-stored second calibrated temperature (Tc1), and
applying (424), by an automatic brake control unit (318), automatic brake when no manual brake is applied and the timer on the instrument panel is equal to zero.

11. The method (400) as claimed in claim 7, wherein the regulating (410) comprises receiving the current coolant flow from a vehicle control unit (VCU) 105 and giving coolant flow input (205) to regulate the coolant flow to cool the windings of the three phase motor (103).
12. The method (400) as claimed in claim 7, wherein the series of motor lock in and lock out map is generated based on the temperature of the other two phases and rotor position.

, Description:MOTOR CONTROL UNIT FOR ENHANCING USER CONVENIENCE IN AN ELECTRIC VEHICLE
TECHNICAL FIELD
[0001] The present disclosure relates, in general, motor control unit (MCU) of an electric vehicle.
[0002] In particular, the present disclosure relates to a motor control unit and a method for enhancing user experience while driving an electric vehicle on an up-hill or upward slope. The present disclosure discloses increasing time of motor lock operation without any additional component.
BACKGROUND
[0003] Background description includes information that may be useful in understanding the present subject matter.
[0004] The electric vehicles have drive motor which generates a traction force to move the wheels of the vehicle. The drive motor receives the AC current from an inverter that converts direct current (DC) coming from a battery pack to the AC current to drive the motor. The drive motor is generally a three-phase alternating-current motor. During uphill movement or upward slope movement on traffic condition, the driver keeps the vehicle stationary or stopped by applying accelerator and continuously supplying maximum constant current to only one phase of the coils of the three phase motor to keep the rotor in locked position. The present condition of vehicle where maximum constant current is being supplied to only one phase to lock the rotor position is referred as motor lock condition. Continuous supply of constant current to one phase might overheat the locked phase coil which may damage the coil. Hence, motor lock control logic is designed in such a way that after reaching temperature limit of the coil, the vehicle comes out of the motor lock condition leading to backward movement of the vehicle on a slope.
[0005] To overcome the present technical problem of overheating of locked phase coils and to avoid backward movement of the vehicle, the existing solution given in US8676469B2 discloses a vehicle drive motor control system which is capable of, when a vehicle drive motor is in a locked state as a result of actuating an accelerator, making the vehicle slowly move backward (or providing other stimulus to the driver) by decreasing the maximum drive torque value. This may effectively cause the driver to make the switch from actuation of the accelerator to actuation of the brake.
[0006] In the existing solution, the drive torque is decreased to allow slow backward movement of the vehicle to indicate or to make the driver to apply brake.
[0007] The existing solution doesn’t increase the motor lock time and doesn’t hint the driver to apply brake by slow backward movement. In case the driver does not pay attention to backward movement of vehicle, the vehicle keeps moving in backward direction with slow speed which is again dangerous in bumper-to-bumper movement of the vehicles.
[0008] Other existing system or technology also doesn’t provide solution to technical problem of coil overheating and backward movement of the vehicle.
[0009] Therefore, there is a need to provide a system and a method for increasing the motor lock operation time and to avoid overheating of the coils of the drive motor during uphill or upward slope movement of the vehicle and also to intimate the driver about the limit of the motor lock operating duration.
OBJECTS OF THE DISCLOSURE
[0010] Some of the objects of the present disclosure, which at least one embodiment herein satisfy, are listed herein below.
[0011] A general object of the present disclosure is to provide a method and a system for increasing time of motor lock during an upward slope or uphill drive.
[0012] An object of the present disclosure is to provide a method and a system to decrease temperature of the motor coils during the motor lock condition by regulating the motor coolant flow.
[0013] Another object of the present subject matter is to provide a system and a method to restrict backward movement of the vehicle during upward slope or uphill drive.
[0014] Another object of the present subject matter is to provide a system and a method to indicate driver to apply brake when the motor lock condition is over.
[0015] These and other objects and advantages of the present disclosure will be apparent to those skilled in the art after a consideration of the following detailed description taken in conjunction with the accompanying drawings in which a preferred form of the present invention is illustrated.
SUMMARY
[0016] This summary is provided to introduce concepts related to a method and a system to increase time of motor lock condition or operation during upward slope of uphill drive. The concepts are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.
[0017] The present disclosure relates to a motor control unit (MCU) of an electric vehicle for increasing time of motor lock operation during upward slope or uphill drive of the vehicle. The motor control unit (MCU) comprising a motor lock detection unit configured to detect a motor lock condition when acceleration actuation amount is greater than zero and vehicle speed is zero, and a temperature of winding, rotor position, and torque determining unit configured to determine temperature (Tpu, Tpv, Tpw) of each winding (u, v, w) of a three-phase traction motor by temperature sensors coupled with the each winding (u,v,w), determine rotor position based on inputs received from a rotor position sensor, determine torque applied by the motor and generate a series of motor lock in and lock out map based on the determined torque. Further, the MCU comprises a coolant flow control unit that is configured to regulate the coolant flow when difference of temperature between threshold temperature (To) and determined temperature (Tp) of locked phase is greater than a pre-stored calibrated temperature (Tc) and current coolant flow is less than permissible limit (P1) to control the determined temperature of the locked phase.
[0018] In an embodiment, the motor control unit (MCU) comprises a motor locked phase control unit which is configured to change the locked phase of the three-phase motor to next phase as per the generated motor lock in and lock out map when: difference of temperature between threshold temperature (To) and determined temperature (Tp) of locked phase is less than a pre-stored calibrated temperature (Tc) and determined temperature (Tpu, Tpv, Tpw) of at least one of the winding (u, v, w) of the three-phase traction motor (103) is less than a pre-stored second calibrated temperature (Tc1).
[0019] In an embodiment, the motor control unit (MCU) comprises an automatic brake actuation control unit is configured to display a timer on instrument panel to apply brake within a predefined time span when the current coolant flow is equal to or greater than a permissible coolant flow limit (P1) and apply automatic brake when no manual brake is applied and the timer on the instrument panel is equal to zero.
[0020] In an embodiment, the motor control unit (MCU) comprises an automatic brake actuation control unit which is configured to display a timer on instrument panel to apply brake within a predefined time span when determined temperature (Tpu, Tpv, Tpw) of each winding (u, v, w) of the three-phase traction motor (103) is greater than or equal to a pre-stored second calibrated temperature (Tc1), and apply automatic brake when no manual brake is applied and the timer on the instrument panel is equal to zero.
[0021] In an aspect, the coolant flow control unit is coupled with a vehicle control unit (VCU) to receive the current coolant flow and give coolant flow input to regulate the coolant flow to cool the windings of the three phase motor.
[0022] In an aspect, the series of motor lock in and lock out map is generated based on the temperature of the other two phases and rotor position.
[0023] In another embodiment, the present subject matter discloses a method for increasing time of motor lock operation of a three-phase traction motor during driving on an upward slope. The method comprising detecting, by a motor lock detection unit, to detect a motor lock condition when acceleration actuation amount is greater than zero and vehicle speed is zero. Further, the method comprises determining, by a temperature of winding, rotor position, and torque determining unit, temperature (Tpu, Tpv, Tpw) of each winding (u, v, w) of a three-phase traction motor by temperature sensors coupled with the each winding (u,v,w), a rotor position based on inputs received from a rotor position sensor, and a torque applied by the motor based on the percentage press of accelerator pedal and coolant temperature and coolant flow from a vehicle control unit (VCU). The method further comprises a step of generating a series of motor lock in and lock out map based on the temperature of the other two phases and rotor position. Regulating, by a coolant flow control unit, regulate the coolant flow when difference of temperature between threshold temperature (To) and determined temperature (Tp) of locked phase is greater than a pre-stored calibrated temperature (Tc) and current coolant flow is less than permissible limit (P1) to control the determined temperature of the locked phase.
[0024] In an embodiment, the method comprises changing, by a motor locked phase control unit, lock phase of the three-phase motor to next phase as per the generated motor lock in and lock out map when: difference of temperature between threshold temperature (To) and determined temperature (Tp) of locked phase is less than a pre-stored calibrated temperature (Tc) and determined temperature (Tpu, Tpv, Tpw) of at least one of the windings (u, v, w) of the three-phase traction motor is less than a pre-stored second calibrated temperature (Tc1).

[0025] In an aspect, the method comprises displaying a timer on instrument panel instructing to apply brake within a predefined time span when the current coolant flow is greater than permissible coolant flow limit (P1), and applying, by an automatic brake control unit, automatic brake when no manual brake is applied and the timer on the instrument panel is equal to zero.
[0026] In an aspect, the method comprises displaying a timer on instrument panel instructing to apply brake within a predefined time span when determined temperature (Tpu, Tpv, Tpw) of each winding (u, v, w) of the three-phase traction motor (103) is greater than or equal to a pre-stored second calibrated temperature (Tc1), and applying, by an automatic brake control unit, automatic brake when no manual brake is applied and the timer on the instrument panel is equal to zero.
[0027] In an aspect, the method includes receiving the current coolant flow from a vehicle control unit (VCU) and to give coolant flow input to regulate the coolant flow to cool the windings of the three phase motor.
[0028] In an aspect, the method includes generating the series of motor lock in and lock out map based on the temperature of the other two phases and rotor position.
[0029] Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which numerals represent like components.
[0030] It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined to form a further embodiment of the disclosure.
[0031] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate exemplary embodiments and, together with the description, serve to explain the disclosed principles. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system and/or methods in accordance with embodiments of the present subject matter are now described, by way of example only, and with reference to the accompanying figures, in which:
[0033] Fig. 1 illustrates block diagram of electrical vehicle as known;
[0034] Fig. 2 illustrates a block diagram of motor control unit receiving inputs for processing and giving output to increase time of motor lock operation, in accordance with an embodiment of the present disclosure;
[0035] Fig. 3 illustrates block diagram of motor control unit (MCU) in the electrical vehicle, in accordance with an embodiment of the present disclosure;
[0036] Fig. 4 illustrates method for decreasing temperature of motor coils during motor lock condition to increase time for motor lock operation and changing phase of motor lock, in accordance with an embodiment of the present disclosure.
[0037] It should be appreciated by those skilled in the art that any block diagrams herein represent conceptual views of illustrative systems embodying the principles of the present subject matter. Similarly, it will be appreciated that any flow charts, flow diagrams, state transition diagrams, pseudo code, and the like represent various processes which may be substantially represented in a computer-readable medium and executed by a computer or processor, whether or not such computer or processor is explicitly shown.
DETAILED DESCRIPTION
[0038] The detailed description of various exemplary embodiments of the disclosure is described herein with reference to the accompanying drawings. It should be noted that the embodiments are described herein in such details as to clearly communicate the disclosure. However, the amount of details provided herein is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the present disclosure as defined by the appended claims.
[0039] It is also to be understood that various arrangements may be devised that, although not explicitly described or shown herein, embody the principles of the present disclosure. Moreover, all statements herein reciting principles, aspects, and embodiments of the present disclosure, as well as specific examples, are intended to encompass equivalents thereof.
[0040] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises”, “comprising”, “includes” and/or “including,” when used herein, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof.
[0041] It should also be noted that in some alternative implementations, the functions/acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may, in fact, be executed concurrently or may sometimes be executed in the reverse order, depending upon the functionality/acts involved.
[0042] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that terms, e.g., those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
Definitions:
[0043] Motor Lock in and Motor Lock out map: The lock in lock out map informs the motor to shift the next available phase for motor locking based on the temperature of the other two phases and the rotor position, once the temperature threshold of already existing locked phase is about to be reached.
[0044] Vehicle Control Unit (VCU): VCU is a controller which controls functionality of the electrical vehicle. The functionalities include functioning of brake pedal, accelerator pedal, coolant flow control, air conditioner control, and other electrical appliances of the electrical vehicle. The VCU is communicatively coupled preferably over CAN bus communication with Motor control unit (MCU) and other components of the electrical vehicle.
[0045] Motor Control Unit (MCU): MCU is a controller which is coupled with an electric motor and inverter to control functionality of the electric motor. Based on the requirements, the MCU takes voltage from the battery and supplies the converted voltage to the motor for traction of the vehicle. The MCU receives all inputs corresponding to the motor. The MCU can be provided inside the inverter and can be referred as Inverter Motor Control Unit.
[0046] Battery Management System (BMS): BMS is a controller which is coupled with the battery pack to determine health, state of charge, and all other functions associated with the battery. The battery pack is coupled with the MCU to supply high voltage DC voltage which is converted into AC voltage for running of the generally three phase motor.
[0047] Calibrated Temperature:
Calibrated Temperature (Tc): This temperature is used to command the motor lock operation to continue either by regulating the coolant flow or by changing the phase.
T0-Tp where
1. T0 = Threshold temperature of per phase winding of locked phase
2. Tp = per phase actual temperature of locked phase.
For example, if T0= 100 and Tp= 20, so it will compare with ‘calibrated temperature’ which is 30 (for example), T0-Tp is greater than calibrated temperature, therefore by increasing the flow of coolant would keep the temperature of locked phase within the workable range for some duration.
Now, if Tp=80 so T0-Tp =100-80=20 and at this point of time it is not recommended to increase the coolant flow to control the temperature of locked phase, instead, change of the phase of motor is required.
Calibrated Temperature_1 (Tc1): This temperature is used to check threshold of winding temperature for all phases.
[0048] For example, per phase winding temperature is Tpu= 60=locked phase, Tpv=40 and Tpw=30 so it will compare with ‘calibrated temperature_1’ which is 50 (for example), Tpv & Tpw is less than calibrated temperature_1, so the phase of motor is changes based on the rotor position.
[0049] All controllers and control units are coupled with each other via CAN bus communication path.
[0050] The present subject matter discloses a method and a system to increase time of motor lock operation by regulating coolant flow to control temperature of the motor coils as well as by changing phase of motor operation on an upward slope or uphill drive of the electrical vehicle. In the present subject matter, a motor lock in-lock out drive map is prepared to change the operating phase of motor based on the temperature of the other two phases and the rotor position. Further, stator winding temperature of all phases is sensed and accordingly the coolant flow is regulated. For limiting conditions of temperature and coolant flow, there is an intimation to driver with a timer on display of instrument panel prompting the driver to apply brakes failing which automatic brakes will be applied by the system to avoid or restrict backward movement of the vehicle.
[0051] FIG. 1 illustrates block diagram of the electric vehicle 100. The electric vehicle 100 comprises a drive motor 103 which is connected with a transmission system 101 that is connected to wheels 102. The drive motor 103 is connected to a battery pack 109 via an inverter. The inverter receives DC voltage current from the battery pack 109 and converts the same into AC voltage current to operate the drive motor 103 which is three phase electric motor. Upon receiving the AC voltage current, the drive motor 103 generates a drive torque for traction of the vehicle, therefore, the drive motor 103 can be referred as traction motor.
[0052] The three-phase drive motor 103 includes coils U, V and W of U, V and W phases. The inverter comprises a Motor Control Unit 104 to control the operations of the drive motor 103 based on inputs, such as acceleration actuation, brake actuation.
[0053] The motor control unit (MCU) 104 is coupled with a vehicle control unit (VCU) 105 to receive inputs from the driver and give instructions to the MCU 104 to control and operate the drive motor 103. As shown in fig. 1, the VCU 105 is coupled with the coolant control unit 106 of the vehicle, a brake control unit 107, and an acceleration control unit 108. The coolant control unit 106 controls flow of coolant in the drive motor 103 to dissipate the heat. The coolant control unit 106 also detects temperature of the coolant. The brake control unit 107 is coupled with brake pedal to detect brake actuation amount applied by the user. The acceleration control unit 108 is coupled with accelerator pedal of the vehicle to determine actuation amount of the acceleration based on the accelerator pedal press condition.
[0054] The MCU 104 is coupled with a rotor position sensor to detect position of the rotor with respect to stator of the motor and to determine angular speed of the rotor. The rotor position is sensed from a resolver or rotor position sensor present in the motor. The MCU 104 is coupled with a drive torque detection means to detect driving torque of the motor. The required torque is determined by the VCU 105 based on the percentage press of accelerator pedal and send the required torque signal to the inverter.
[0055] Each coil of the three phase motor has a temperature sensor which detects current temperature of each of the coil of the three phase motor. Each sensor is coupled with the MCU 104 to detect real time temperature of the respective coils U, V, and W inside the motor.
[0056] As shown in the fig. 1, the VCU 105 determine real time values of acceleration actuation amount, brake actuation amount, coolant flow speed and vehicle speed. The VCU 105 coupled with the MCU 104 via CAN bus path to communicate all real time values for further processing and to control operations of the drive motor 103.
[0057] Referring to Fig. 1, the battery pack 109 is coupled with a charger to convert the AC voltage into DC voltage to charge the battery pack 109. The battery pack 109 is coupled with a battery management system 110 which constantly check State of Health (SoH), State of Charge (SoC), and Depth of Discharge (DoD) of the battery pack 109.
[0058] Referring to fig. 2, to decrease temperature of the locked phase coil of the three phase drive motor 103 and to change locked phase of the three phase drive motor 103, the MCU 300 (104 is referred in Fig. 1) receives acceleration actuation amount from the acceleration control unit 201 (i.e., 108 of Fig. 1), speed of vehicle from speed determining unit 202, coolant flow and coolant temperature from coolant flow control unit 203 (i.e., 106 of Fig. 1), and brake actuation amount from the brake control unit 204 (i.e., 107 of fig 1). Upon receiving the inputs from the VCU 105, the MCU 300 process the inputs to generate coolant flow input 205, change of phase of motor input 206, and automatic brake actuation input 207, to decrease the temperature of the coils of the locked phase of three phase drive motor 103 to increase the time of motor lock operation, and to change locked phase of motor to increase the time of motor lock operation. At the end when it is not possible to maintain or continue the motor lock operation, the MCU 300 prompt the driver to apply the brake and in case the driver don’t apply brake in a predefined time span, for example, 30 seconds, the MCU 300 sends signal to apply the automatic brake to avoid backward movement of the vehicle when there is no motor lock condition.
[0059] Fig. 3 illustrates components or processing units of the MCU 300, in accordance with some embodiments of the present disclosure. The MCU 300 can work as a central system to communicate with a plurality of electronic components and other controllers as shown in fig. 1. Present specification does not provide detailed explanation about the VCU 105, BMS 110, brake control unit 107, acceleration control unit 108, and coolant control unit 106, traction system and structure of the AC current three-phase drive motor as a person skilled in the art would know about the functioning and the components of these units. The MCU 300 can be positioned inside the inverter to control the drive motor 103. The MCU 300 includes a processor(s) 302, an interface(s) 304, and a memory 306.
[0060] The processor(s) 302 may be implemented as one or more microprocessors, microcomputers, microcontrollers, digital signal processors, logic circuitries, and/or any devices that manipulate data based on operational instructions. The MCU 300 can be provided as a micro-controller to operate the drive motor 103 to achieve the objectives.
[0061] Among other capabilities, the one or more processor(s) 302 are configured to fetch and execute instructions and one or more routines stored in the memory 306. The memory 306 may store one or more readable instructions or routines or maps which may be fetched and executed to increase time for motor lock operating during uphill or upward slope driving. The memory 306 may include any non-transitory storage device including, for example, volatile memory such as RAM, or non-volatile memory such as EPROM, flash memory, and the like.
[0062] The interface(s) 304 may include a variety of interfaces, for example, interfaces for data input and output devices referred to as I/O devices, storage devices, and the like. The interface(s) 304 may facilitate communication of the MCU 300 with various other controllers, such as VCU 105, BMS 110, the battery pack 109 and motor 103. The interface(s) 304 may also provide a communication pathway for one or more components of the MCU 300. Examples of such components include, but are not limited to, processing unit(s) 308 and data 320. The MCU 300 and other components are coupled with the each other via CAN bus or any other existing communication line in the vehicles.
[0063] The processing unit(s) 308 may be implemented as a combination of hardware and programming (for example, programmable instructions) to implement one or more functionalities of the processing unit(s) 308. In examples described herein, such combinations of hardware and programming may be implemented in several different ways. For example, the programming for the processing unit(s) 308 may be processor-executable instructions stored on a non-transitory machine-readable storage medium and the hardware for the processing unit(s) 308 may include a processing resource (for example, one or more processors), to execute such instructions. In the present examples, the machine-readable storage medium may store instructions that, when executed by the processing resource, implement the processing unit(s) 308. In such examples, the MCU 300 may include the machine-readable storage medium storing the instructions and the processing resource to execute the instructions or the machine-readable storage medium may be separate but accessible to the MCU 300 and the processing resource. In other examples, the processing unit(s) 308 may be implemented as electronic circuitry to perform the functions and to control the drive motor 103 and brake control unit 107 as per present subject matter.
[0064] In an aspect, the processing unit(s) 308 may include motor lock detection unit 310, a temperature of winding, rotor position, and torque determining unit 312 which is coupled with the drive motor 103, a coolant flow control unit 314 to control flow of coolant, a motor lock phase control unit 316 to change the locked phase of the drive motor 103, and an automatic brake actuation control unit 318. The processing unit(s) 308 may include other unit(s) which may implement functionalities that supplement applications or functions performed by the MCU 300 or the processing unit(s) 308. As shown in fig. 3, the automatic brake actuation control unit 318 can be provided as part of the VCU 105 which receives the inputs from the MCU 300.
[0065] Further, the data 320 may include data that is either stored or generated as a result of functionalities implemented by any of the components of the processing unit(s) 308. In some aspects, the data 320 may be stored in the memory 306 in the form of various data structures. Additionally, the data 320 can be organized using data models, such as relational or hierarchical data models. The data 320 may store data, including temporary data and temporary files, generated by the processing unit(s) 308 for performing the various functions of the MCU 300. In the present subject matter, the data 320 may store the series of motor lock in and lock out map.
[0066] In the present subject matter, the data 320 or the memory 306 may store series of motor lock in and lock out map, drive torque map. The maps may be stored in the form of tables or lookup tables having values for each instant corresponding to the parameters. The stored predefined maps provide real-time assistance in computation to the units of the processing unit(s) 308 to increase the time of motor lock condition.
[0067] The MCU 300 is coupled with the VCU 105 and the BMS 110 in bi-communication mode. The MCU 300 is also coupled with accelerator pedal and brake pedal to receive driver instructions in the form of acceleration actuation amount, and brake actuation amount. Referring to fig. 2 and 3 together for better understanding of flow of information and working of the present subject matter, the MCU 300 coupled with the drive motor 103 and the VCU 105 to increase the time of motor lock operation during uphill or upward slope driving of the vehicle.
[0068] In operation, when driver holds the vehicle stopped on an uphill or upward slope road by actuating the accelerator pedal where speed of the vehicle is zero and the brake pedal is not actuated, the drive motor enters a motor locked state. The motor lock detection unit 310 is configured to detect the motor lock condition when the acceleration actuation amount is greater than zero ‘0’ and speed of the vehicle is zero ‘0’. The motor lock detection unit 310 receives actuated acceleration amount from the acceleration control unit 108 via the VCU 105 and vehicle speed from the VCU 105.
[0069] Once the motor lock condition is detected, the temperature of winding, rotor position, and torque determining unit 312 is configured to determine temperature (Tpu, Tpv, Tpw) of each winding (u, v, w) of the three-phase traction motor 103 by temperature sensors coupled with the each winding (u,v,w). The temperature of winding, rotor position, and torque determining unit 312 further determines rotor position based on inputs received from the rotor position sensor placed in the drive motor 103. The rotor position is sensed from the resolver or rotor position sensor present in the motor. The temperature of winding, rotor position, and torque determining unit 312 determine a torque applied by the drive motor 103 based on the percentage press of accelerator pedal based on which the VCU 105 calculates the required torque and send this signal to the inverter. Based on the determined torque, the temperature of winding, rotor position, and torque determining unit 312 generates a series of motor lock in and lock out map and stores the same either in data 320 or in the memory 306 based on the initial instructions.
[0070] The coolant flow control unit 314 receives coolant flow regulation input from the VCU 105. The VCU 105 calculates the difference between threshold temperature (To) and determined temperature (Tp) of locked phase. The coolant flow control unit 314 is configured to regulate the coolant flow when difference of temperature (To-Tp) between threshold temperature (To) and determined temperature (Tp) of locked phase is greater than a pre-stored calibrated temperature (Tc) and current coolant flow is less than permissible limit (P1) to decrease the determined temperature (Tp) of the locked phase. With the dissipation of heat from the drive motor 103, the time of motor lock condition increases.
[0071] The motor lock phase control unit 316 is configured to change locked phase of the three-phase motor 103 to next phase as per the generated motor lock in and lock out map. The motor lock phase control unit 316 changes the locked phase when difference (To – Tp) of temperature between threshold temperature (To) and determined temperature (Tp) of locked phase is less than the pre-stored calibrated temperature (Tc) and determined temperature (Tpu, Tpv, Tpw) of at least one of winding (u, v, w) of the three-phase traction motor 103 is less than a pre-stored second calibrated temperature (Tc1). The motor lock phase control unit 316 changes the locked phase to next phase as per the series of motor lock in and motor lock out. With the change of locked phase, the duration of motor lock condition increases.
[0072] The automatic brake actuation control unit 318 is configured to display a timer on instrument panel to instruct or inform the driver to apply brake within a predefined time span when the determined current coolant flow is equal to or greater than the permissible coolant flow limit (P1). When the driver applies the brake manually, the timer stops and vehicle remain in stationary condition on the uphill or upward slope path or road with actuation of brake pedal. However, when the driver ignores the indication to apply brake, the automatic brake actuation control unit 318 applies automatic brake when the timer on the instrument panel is equal to zero which indicates that the driver did not apply the manual brake. In order to avoid backward movement of the vehicle, the present MCU 300 provides a signal to apply automatic brakes even in the absence of actuation of brake pedal by the driver. The timer can be calibrated based on limiting temperature. Therefore, the present subject matter provides complete protection to the motor and the vehicle.
[0073] The automatic brake actuation control unit 318 is configured to display a timer on instrument panel to instruct or inform the driver to apply brake within a predefined time span when determined temperature (Tpu, Tpv, Tpw) of each winding (u, v, w) of the three-phase traction motor (103) is greater than or equal to a pre-stored second calibrated temperature (Tc1). When the driver applies the brake manually, the timer stops and vehicle remain in stationary condition on the uphill or upward slope path or road with actuation of brake pedal. However, when the driver ignores the indication to apply brake, the automatic brake actuation control unit 318 applies automatic brake when the timer on the instrument panel is equal to zero which indicates that the driver did not apply the manual brakes. In order to avoid backward movement of the vehicle, the present MCU 300 provides signal to apply automatic brakes even in the absence of actuation of brake pedal by the driver. The timer can be calibrated based on limiting temperature. Therefore, the present subject matter provides complete protection to the motor and the vehicle.
[0074] The coolant flow control unit 314 is coupled with the vehicle control unit (VCU) 105 to receive the current coolant flow and give coolant flow input 205 to regulate the coolant flow to cool the windings of the three phase motor 103.
[0075] In an embodiment, the series of motor lock in and lock out map is generated based on the temperature of the other two phases and rotor position. The lock in-lock out map informs the motor to shift the next available phase for motor locking based on the temperature of the other two phases and the rotor position, once the temperature threshold of already existing locked phase is about to be reached.
[0076] Exemplary illustration and working of the present subject matter:
[0077] In the present example, hypothetical values are considered to explain the working and flow of the present subject matter.
[0078] The calibrated temperature is pre-stored in the MCU 300. In the present subject matter, two calibrated temperatures, such as pre-stored first calibrated temperature Tc and a pre-stored second calibrated temperature Tc1 is stored either in the memory 306 or in the data 320. The calibrated temperature corresponds to command the motor lock operation to continue either by regulating the coolant flow or by changing the phase.
[0079] T0-Tp where T0 = Threshold temperature of a per phase winding of locked phase, Tp= per phase actual temperature of locked phase.
[0080] For an example, assume T0= 100o C and Tp= 20o C so it will compare with ‘calibrated temperature’ which is 30 (for example), T0-Tp is greater than calibrated temperature, therefore by increasing the flow of coolant would keep the temperature of locked phase within the workable range for some duration. Therefore, by increasing the coolant flow, temperature of the locked phase coil of the drive motor can be decreased so that time of motor lock condition is also increased.
[0081] In another scenario, assume Tp=80o C so T0-Tp =100-80=20o C and at this point of time it is not recommended to increase the coolant flow to control the temperature of locked phase or current coolant flow is equal to permissible coolant flow and therefore, the MCU 300 changes the locked phase of the drive motor 103.
[0082] In another scenario, where the pre-stored second calibrated temperature corresponds to check threshold of winding temperature for all phases.
[0083] Let say Per phase winding temperature is Tpu= 60=locked phase, Tpv=40 and Tpw=30, the MCU 300 compares with ‘pre-stored second calibrated temperature Tc1’ which is for example say 50o C, hence, Tpv and Tpw is less than calibrated temperature_1, so that MCU 300 changes the locked phase and it will be done based on the rotor position.
[0084] FIG. 4 illustrates a method 400 to increase time of motor lock operation by regulating the coolant flow as well as by changing the motor locked phase. The order in which the method 400 is described is not intended to be construed as a limitation, and any number of the described method blocks can be combined in any appropriate order to carry out the method 400 or an alternative method. Additionally, individual blocks may be deleted from the method 400 without departing from the scope of the subject matter described herein.
[0085] At step 402, the method 400 includes detecting, by a motor lock detection unit 310, a motor lock condition when acceleration actuation amount is greater than zero and vehicle speed is zero.
[0086] At step 404, the method 400 includes determining, by a temperature of winding, rotor position, and torque determining unit 312, temperature (Tpu, Tpv, Tpw) of each winding (u, v, w) of a three-phase traction motor 103 by temperature sensors coupled with the each winding (u,v,w), a rotor position based on inputs received from a rotor position sensor..
[0087] The step 404 includes generating a series of motor lock in and lock out map or cycle based on the determined torque.
[0088] At step 406, the method 400 includes calculating the difference of temperature between threshold temperature (To) and determined temperature (Tp) of locked phase of the drive motor 103 and compare the same with the pre-stored first calibrated temperature (Tc). When the difference of temperature (To-Tp) is greater than the pre-stored first calibrated temperature (Tc), the method proceeds to step 408. When the difference of temperature (To-Tp) is less than the pre-stored first calibrated temperature (Tc), the method proceeds to step 412.
[0089] At step 408, the method 400 includes comparing the current coolant flow with the pre-stored permissible limit (P1) of the coolant flow. When the current coolant flow is less than the pre-stored permissible limit (P1) of the coolant flow, the method proceeds to step 410. When the current coolant flow is greater than or equal to the pre-stored permissible limit (P1) of the coolant flow, the method proceeds to step 416.
[0090] At step 410, the method 400 includes regulating, by the coolant flow control unit 314, regulate the coolant flow when difference of temperature between threshold temperature (To) and determined temperature (Tp) of locked phase is greater than a pre-stored calibrated temperature (Tc) and current coolant flow is less than permissible limit (P1) to decrease the determined temperature of the locked phase.
[0091] At step 412, the method includes comparing the determined temperature (Tpu, Tpv, Tpw) of each winding (u, v, w) of the three-phase traction motor 103 to a pre-stored second calibrated temperature (Tc1). When the determined temperature (Tpu, Tpv, Tpw) of each winding (u, v, w) is greater than or equal to the pre-stored second calibrated temperature (Tc1), the method proceeds to step 416. When the determined temperature (Tpu, Tpv, Tpw) of at least one of the winding (u, v, w) is less than the pre-stored second calibrated temperature (Tc1), the method proceeds to step 414.
[0092] At step 414, the method 400 changes the locked phase of the three-phase motor 103 to next phase as per the generated motor lock in and lock out map.
[0093] At step 416, the method 400 includes displaying a timer on instrument panel instructing or indicating driver to apply brake within a predefined time span.
[0094] At step 418, the method 400 includes determining whether driver has manually applied the brake. When the driver applies the manual brake, the method proceeds to step 420 to stop the timer and keep the vehicle stationary by actuation of the brake pedal.
[0095] At step 422, the method 400 includes determine whether timer is equal to zero or not.
[0096] At step 424, the method 400 includes applying, by the automatic brake control unit 318, automatic brake to hold the vehicle stationary when the timer on the instrument panel is equal to zero.
[0097] The method 400 includes regulating the coolant flow where the coolant flow control unit 314 receives the current coolant flow from a vehicle control unit (VCU) 105 and gives coolant flow input 205 to regulate the coolant flow to cool the windings of the three phase motor 103.
[0098] Technical advantages:
[0099] With the implementation of the present subject matter, the time of motor lock operation increases by regulating the coolant flow as well as changing the phase of the motor operation on the uphill or upward slope.
[00100] With the implementation of the present subject matter, the automatic brakes are applied even when the driver ignores the indication or warning on the instrument panel to apply brake to keep the vehicle stationary and avoid moving the vehicle in backward direction.
[00101] The above description does not provide specific details of the manufacture or design of the various components. Those of skill in the art are familiar with such details, and unless departures from those techniques are set out, techniques, known, related art or later developed designs and materials should be employed. Those in the art can choose suitable manufacturing and design details.
[00102] It should be understood, however, that all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. Unless specifically stated otherwise, as apparent from the discussion herein, it is appreciated that throughout the description, discussions utilizing terms such as “receiving,” or “setting,” or “transmitting,” or the like, refer to the action and processes of an electronic control unit, or similar electronic device, that manipulates and transforms data represented as physical (electronic) quantities within the control unit’s registers and memories into other data similarly represented as physical quantities within the control unit memories or registers or other such information storage, transmission or display devices.
[00103] Further, the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. It will be appreciated that several of the above-disclosed and other features and functions, or alternatives thereof, may be combined into other systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may subsequently be made by those skilled in the art without departing from the scope of the present disclosure as encompassed by the following claims.
[00104] It will be appreciated that variants of the above-disclosed and other features and functions, or alternatives thereof, may be combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.
[00105] The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants and others.