Claims:1. A motor control system (100) for an electric vehicle comprising:
a plurality of sensors (110) configured to sense a corresponding plurality of real-time operational parameters associated with a motor (105) of the electric vehicle;
an electric vehicle control subsystem (120) operatively coupled to the plurality of sensors (110), wherein the electric vehicle control subsystem (120) is configured to:
receive each of a plurality of sensed values corresponding to each of a plurality of real-time sensed operational parameters;
compare each of a plurality of sensed values with each of a plurality of predetermined threshold limits corresponding to a plurality of predetermined operational parameters stored in an operational parameter database;
generate an error signal based on a difference determined from comparison of the plurality of received real-time operational parameters with the plurality of predetermined operational parameters;
convert a generated error signal into a variable duty ratio or frequency pulse width modulation (PWM) signal by performing a calibration activity based on a predefined requirement; and
control performance of the motor to drive the electric vehicle based on duty ratio/frequency values obtained upon conversion of the generated error signal.
2. The system (100) as claimed in claim 1, wherein the plurality of sensors (110) comprises a hall sensor (111), current sensor (113), a temperature sensor (112), a weight sensor, a traction sensor, a radar sensor, an altitude sensor, a fire sensor, a pressure sensor, an accelerometer and a gyro sensor.
3. The system (100) as claimed in claim 1, wherein the plurality of real-time sensed operational parameters comprises at least one of speed, current, temperature, voltage, load, friction, relative speed, elevation, fire in the electric vehicle, pressure, acceleration or a combination thereof.
4. The system (100) as claimed in claim 1, wherein the motor (105) comprises a brushless direct current (BLDC) motor.
5. The system (100) as claimed in claim 1, wherein the generated error signal comprises at least one of error in speed response, error in torque response, error in regenerative braking response, error in current response, error in temperature response or a combination thereof.
6. The system (100) as claimed in claim 1, wherein the calibration activity for conversion of the generated error signal into a variable duty ratio/frequency pulse width modulation (PWM) signal comprises calibration of least two parameters of a PID controller.
7. The system as claimed in claim 6, wherein the at least two parameters comprises proportional gain (Kp) and integral gain (Ki).
8. A method (300) comprising:
sensing, by a plurality of sensors, a corresponding plurality of real-time operational parameters associated with a motor of the electric vehicle (310);
receiving, by an electric vehicle control subsystem, each of a plurality of sensed values corresponding to each of a plurality of real-time sensed operational parameters (320);
comparing, by the electric vehicle control subsystem, each of a plurality of sensed values with each of a plurality of predetermined threshold limits corresponding to a plurality of predetermined operational parameters stored in an operational parameter database (330);
generating, by the electric vehicle control subsystem, an error signal based on a difference determined from comparison of the plurality of received real-time operational parameters with the plurality of predetermined operational parameters (340);
converting, by the electric vehicle control subsystem, a generated error signal into variable duty ratio or frequency pulse width modulation (PWM) signal by performing a calibration activity based on a predefined requirement (350); and
controlling, by the electric vehicle control subsystem, performance of the motor to drive the electric vehicle based on duty ratio/frequency values obtained upon conversion of the generated error signal (360).
9. The method as claimed in claim 8, wherein sensing the corresponding plurality of real-time operational parameters associated with the motor of the electric vehicle comprises sensing the corresponding plurality of real-time operational parameters comprising speed, current, temperature, voltage, load, friction, relative speed, elevation, fire in the electric vehicle, pressure, acceleration or a combination thereof.
10. The method as claimed in claim 8, wherein generating the error signal based on the difference determined from the comparison of the plurality of received real-time operational parameters with the plurality of predetermined operational parameters comprises generating the error signal comprising at least one of error in speed response, error in torque response, error in regenerative braking response, error in current response, error in temperature response or a combination thereof.
Dated this 06th day of March 2020
Signature

Vidya Bhaskar Singh Nandiyal
Patent Agent (IN/PA-2912)
Agent for the Applicant
, Description:BACKGROUND
[0001] Embodiments of the present disclosure relate to electrically operated vehicle, and more particularly, to a motor control system for electric vehicles and a method to operate the same.
[0002] An electric vehicle (EV) is one that operates on an electric motor, instead of an internal-combustion engine that generates power by burning a mix of fuel and gases. A power system of the electric vehicle includes two components such as the electric motor that provides the power and a controller that controls the application of this power to the electric motor. The performance of the electric motor depends on many factors like voltage, current, speed, temperature etc. As a result, the electronic motor controller is essential which controls different aspects of the electric motor to ensure the right current and voltage is applied across the electric motor. Various motor control systems are available which controls one or more parameters of the electric motor for driving the electric vehicles.
[0003] Conventionally, the motor control systems available in market for controlling the electric motor of the electric vehicle includes electronic controllers which includes an automatic means for starting/stopping the motor, choosing forward/reverse rotation, selecting and controlling the speed, modifying or limiting the torque, and shielding against faults and overloads based on manual input. However, such electronic controllers requires manual intervention which leads to wastage of time and effort. Also, such electronic controllers are unable to modify one or more parameters based on one or more requirements in real-time for performance improvement. Moreover, the conventional electronic controllers are able to upgrade the performance of the electric vehicle by changing one or more physical components which also make the process more expensive.
[0004] Hence, there is a need for an improved motor control system for electric vehicles and a method to operate the same in order to address the aforementioned issues.

BRIEF DESCRIPTION
[0005] In accordance with an embodiment of the present disclosure a motor control system for an electric vehicle is disclosed. The system includes a plurality of sensors configured to sense a corresponding plurality of real-time operational parameters associated with a motor of the electric vehicle. The system also includes an electric vehicle control subsystem operatively coupled to the plurality of sensors. The electric vehicle control subsystem is configured to receive each of a plurality of sensed values corresponding to each of a plurality of real-time sensed operational parameters. The electric vehicle control subsystem is also configured to compare each of a plurality of sensed values with each of a plurality of predetermined threshold limits corresponding to a plurality of predetermined operational parameters stored in an operational parameter database. The electric vehicle control subsystem is also configured to generate an error signal based on a difference determined from comparison of the plurality of received real-time operational parameters with the plurality of predetermined operational parameters. The electric vehicle control subsystem is also configured to convert a generated error signal into variable duty ratio/frequency pulse width modulation (PWM) signal by performing a calibration activity based on a predefined requirement. The electric vehicle control subsystem is also configured to control performance of the motor to drive the electric vehicle based on duty ratio/frequency values obtained upon conversion of the generated error signal.
[0006] In accordance with another embodiment of the present disclosure, a method for operation of a motor control system of an electric vehicle is disclosed. The method includes sensing, by a plurality of sensors, a corresponding plurality of real-time operational parameters associated with a motor of the electric vehicle. The method also includes receiving, by an electric vehicle control subsystem, each of a plurality of sensed values corresponding to each of a plurality of real-time sensed operational parameters. The method also includes comparing, by the electric vehicle control subsystem, each of a plurality of sensed values with each of a plurality of predetermined threshold limits corresponding to a plurality of predetermined operational parameters stored in an operational parameter database. The method also includes generating, by the electric vehicle control subsystem, an error signal based on a difference determined from comparison of the plurality of received real-time operational parameters with the plurality of predetermined operational parameters. The method also includes converting, by the electric vehicle control subsystem, a generated error signal into variable duty ratio/frequency pulse width modulation (PWM) signal by performing a calibration activity based on a predefined requirement. The method also includes controlling, by the electric vehicle control subsystem, performance of the motor to drive the electric vehicle based on duty ratio/frequency values obtained upon conversion of the generated error signal.
[0007] To further clarify the advantages and features of the present disclosure, a more particular description of the disclosure will follow by reference to specific embodiments thereof, which are illustrated in the appended figures. It is to be appreciated that these figures depict only typical embodiments of the disclosure and are therefore not to be considered limiting in scope. The disclosure will be described and explained with additional specificity and detail with the appended figures.
BRIEF DESCRIPTION OF THE DRAWINGS
The disclosure will be described and explained with additional specificity and detail with the accompanying figures in which:
[0008] FIG. 1 is a block diagram of a motor control system for an electric vehicle in accordance with an embodiment of the present disclosure;
[0009] FIG. 2 illustrates a block diagram for depicting an operation of an exemplary control system in BLDC motor driver for an electric vehicle of FIG.1 in accordance with an embodiment of the present disclosure;
[0010] FIG. 3 illustrates a circuit diagram representation of a motor control system for an electric vehicle of FIG. 1 in accordance with an embodiment of the present disclosure;
[0011] FIG. 4 is a flow chart representing the steps involved in a method of operation of a motor control system for an electric vehicle of FIG. 1 in accordance with the embodiment of the present disclosure.
[0012] Further, those skilled in the art will appreciate that elements in the figures are illustrated for simplicity and may not have necessarily been drawn to scale. Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the figures by conventional symbols, and the figures may show only those specific details that are pertinent to understanding the embodiments of the present disclosure so as not to obscure the figures with details that will be readily apparent to those skilled in the art having the benefit of the description herein.
DETAILED DESCRIPTION
[0013] For the purpose of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiment illustrated in the figures and specific language will be used to describe them. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended. Such alterations and further modifications in the illustrated system, and such further applications of the principles of the disclosure as would normally occur to those skilled in the art are to be construed as being within the scope of the present disclosure.
[0014] The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such a process or method. Similarly, one or more devices or sub-systems or elements or structures or components preceded by "comprises... a" does not, without more constraints, preclude the existence of other devices, sub-systems, elements, structures, components, additional devices, additional sub-systems, additional elements, additional structures or additional components. Appearances of the phrase "in an embodiment", "in another embodiment" and similar language throughout this specification may, but not necessarily do, all refer to the same embodiment.
[0015] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this disclosure belongs. The system, methods, and examples provided herein are only illustrative and not intended to be limiting.
[0016] In the following specification and the claims, reference will be made to a number of terms, which shall be defined to have the following meanings. The singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise.
[0017] Embodiments of the present disclosure relate to a motor control system for an electric vehicle and a method to operate the same. The system includes a plurality of sensors configured to sense a corresponding plurality of real-time operational parameters associated with a motor of the electric vehicle. The system also includes an electric vehicle control subsystem operatively coupled to the plurality of sensors. The electric vehicle control subsystem is configured to receive each of a plurality of sensed values corresponding to each of a plurality of real-time sensed operational parameters. The electric vehicle control subsystem is also configured to compare each of a plurality of sensed values with each of a plurality of predetermined threshold limits corresponding to a plurality of predetermined operational parameters stored in an operational parameter database. The electric vehicle control subsystem is also configured to generate an error signal based on a difference determined from comparison of the plurality of received real-time operational parameters with the plurality of predetermined operational parameters. The electric vehicle control subsystem is also configured to convert a generated error signal into variable duty ratio/frequency pulse width modulation (PWM) signal by performing a calibration activity based on a predefined requirement. The electric vehicle control subsystem is also configured to control performance of the motor to drive the electric vehicle based on the duty ratio/frequency values obtained upon conversion of the generated error signal.
[0018] FIG. 1 is a block diagram of a motor control system (100) for an electric vehicle (not shown in FIG. 1) in accordance with an embodiment of the present disclosure. The system (100) includes multiple sensors (110) configured to sense corresponding multiple real-time operational parameters associated with a motor (105) of the electric vehicle. In one embodiment, the multiple sensors (110) may include, but not limited to, a hall sensor, current sensor, a temperature sensor, a weight sensor, a traction sensor, a radar sensor, an altitude sensor, a fire sensor, a pressure sensor, an accelerometer and a gyro sensor. In some embodiment, the multiple real-time sensed operational parameters may include, but not limited to, at least one of speed, current, temperature, voltage, load, friction, relative speed, elevation, fire in the electric vehicle, pressure, acceleration or a combination thereof. As used herein, the term ‘multiple operational parameters’ is defined as multiple of actual parameters which is determined by the multiple sensors in real-time during operation of the vehicle. In one embodiment, the motor (105) may include but not limited to a brushless direct current (BLDC) motor.
[0019] The system (100) also includes an electric vehicle control subsystem (120) operatively coupled to the multiple sensors (110). The electric vehicle control subsystem (120) receives each of multiple sensed values corresponding to each of multiple real-time sensed operational parameters. The electric vehicle control subsystem (120) is also configured to compare each of multiple sensed values with each of a multiple predetermined threshold limits corresponding to multiple predetermined operational parameters stored in an operational parameter database. As used herein, the term ‘predetermined operational parameters’ is defined as a multiple of reference values or predetermined throttle values which are determined based on a user requirement by using a hand throttle, pot and the like. The multiple sensed values corresponding to each of the multiple real-time sensed operational parameters are mapped with the multiple predetermined threshold limits corresponding to the multiple predetermined operational parameters.
[0020] In one embodiment, the operational parameter database may store the plurality of reference values or the plurality of predetermined threshold limits corresponding to the plurality of predetermined operational parameters. In some embodiment, the operational parameter database may be hosted/stored but not limited to, on a remote server or in a local storage device. In such embodiment, the remote server may include a cloud server. In another embodiment, the operational parameter database may be hosted on a local server. In one embodiment, the electric vehicle control subsystem (120) may include a proportional integral derivative (PID) controller.
[0021] The electric vehicle control subsystem (120) is also configured to generate an error signal based on a difference determined from comparison of the multiple received real-time operational parameters with the multiple predetermined operational parameters. In one embodiment, the generated error signal may include at least one of error in speed response, error in torque response, error in regenerative braking response, error in current response, error in temperature response or a combination thereof.
[0022] The electric vehicle control subsystem (120) also converts a generated error signal into variable duty ratio/frequency pulse width modulation (PWM) signal by performing a calibration activity based on a predefined requirement. In one embodiment, the calibration activity for the conversion of the generated error signal into variable duty ratio/frequency pulse width modulation (PWM) signal may include calibration of least two parameters of the PID controller (121) which is shown later in details in FIG. 2, wherein the at least two parameters comprises proportional gain (Kp) and integral gain (Ki). The electric vehicle control subsystem (120) is also configured to control performance of the motor (105) to drive the electric vehicle based on duty ratio/frequency values of the PWM signal obtained upon conversion of the generated error signal. The variable duty ratio/frequency PWM signal obtained upon the conversion of the generated error signal is given as input to one or more switches of metal–oxide–semiconductor field-effect transistor (MOSFET) driver (122) shown later in FIG. 2, which in turn controls the speed and current of the BLDC motor (105).
[0023] FIG. 2 illustrates a block diagram for depicting an operation of a motor control system (100) of FIG. 1 for an electric vehicle in accordance with an embodiment of the present disclosure. The system (100) controls the BLDC motor (105) used in the electric vehicle. The BLDC motor (105) is substantially similar to a motor (105) of FIG.1.The BLDC motor (105) of the electric vehicle starts the operation when a load voltage (107) is applied to the BLDC motor (105). A polarity of the load voltage (107) is switched by a BLDC controller circuit such as, but not limited to, a H-bridge Inverter circuit (108) (later shown in FIG. 3). The BLDC motor (105) attains a corresponding speed upon application of the load voltage (107). Here, the speed of the BLDC motor (105) is determined by using a speed sensor or a hall sensor (111). Also, the speed of the motor (105) may be varied by using either a hand throttle, pot or any speed adjusting device which determines the voltage corresponding to the required speed. Throttle values (123) are mapped into speed reference value (124) upon variation of the speed value using the hand throttle. Here, the speed reference value (124) is known as a predetermined threshold limit of the speed of the BLDC motor (105) which is determined based on user requirement. Again, the speed of the BLDC motor (105) which is determined by the speed sensor or the hall sensor (111) in real-time is known as actual speed (126). The speed of the BLDC motor (105) is calculated by using a below-mentioned equation (1) as follows:
Speed of the BLDC Motor (N) = (120 f) / P ………. (1)
Where, N= speed of the BLDC motor in rpm,
F=Switching Frequency in Hz
P= Number of poles.
[0024] Now, the actual speed of the BLDC motor (105) is compared with the speed reference value (124). Upon comparison, a difference in speed value is generated which leads to generation of error signal (127). Such generated error signal (127) is further transmitted to a proportional integral derivative (PID) controller block (121) which is controlled by a microcontroller (117) (later shown in FIG. 3), wherein the generated error signal is tuned or calibrated. After calibration activity, the generated error signal in the PID block (121) is converted into variable duty ratio pulse width modulation (PWM) signal (128). The calibration activity for the conversion of the generated error signal into variable duty ratio pulse width modulation (PWM) signal (128) includes calibration of least two parameters of the PID controller (121), wherein the at least two parameters includes proportional gain (Kp) (129) and integral gain (Ki) (130). Here, at least two parameters Kp (129) and the Ki (130) are tuned or calibrated based on requirement. Calculation of the Kp in a discrete domain is shown below in equation (2) as follows:
Kp * e = (Kp * e) in discrete domain …… (2)
Similarly, calculation of the Ki is shown below in equation (3) as follows:
???? / ?? ?t0 e ???? = 1 / ?? Sn0 K?? * e?? * t ….……. (3)
Where, t = PID loop execution time interval
Where, en = error in nth time interval, and T = Overall process time interval
[0025] Later, the variable duty ratio PWM signal (128) is provided as an input to one or more switches of MOSFET driver (122) which in turn controls the speed of the BLDC motor (105). Also, the temperature and the current of the BLDC motor (105) in real-time are also sensed by a temperature sensor (112) and a current sensor (113) respectively. Such real-time temperature sensed value (131) and current sensed value (132) are compared with the predetermined threshold limit of the temperature and the current respectively. The real-time sensed value of the current (132) from the current sensor (113) is compared with the current predetermined limit set (136), wherein if the actual or the real-time sensed current value (132) is greater than the predetermined threshold limit of the current (135), then the frequency of PWM signal is drastically varied based on the error signal, to tame the current value within the limit (current chopping). If the current value is way beyond the predefined maximum limit set (136), the duty ratio value (128) of the PWM signal is set to zero to shut down the BLDC motor (105). The above-mentioned current regulator involves a PID controller (139) where at least two parameters Kp and the Ki are tuned accordingly to minimize the generated error signal and hence generates suitable output voltage value. Again, the current limiting control uses PID operation where at least two parameters Kp and the Ki are tuned accordingly to minimize the generated error signal in order to control the frequency of chopping. Further, the frequency value (137) of the PWM signal is used to drive the BLDC motor (105) via a MOSFET driver (122).
[0026] Similarly, the real-time sensed value of the temperature from the temperature sensor (112) is compared with the predetermined threshold temperature limit set (133), wherein if the actual or the real-time sensed temperature value (131) is greater than the predetermined threshold limit of the temperature (133), then based on the error signal, the desired output voltage signal (134) from the PID controller (138) is fed to an external system which can include but not limited to a cooling fan to increase its speed or to increase the flow rate of the coolant in case of fluid cooled motors by controlling one or more valves or can be converted into duty ratio to lower the speed of the motor accordingly. In case of undesirable temperature variations, such as when the temperature is beyond a predefined maximum limit set (136), the BLDC motor (105) is completely shut down by setting the duty ratio value of the PWM signal (128) to zero. The above-mentioned temperature regulator involves PID controller (138) where at least two parameters Kp and the Ki are tuned accordingly to minimize the generated error signal and hence generates suitable output voltage value.
[0027] FIG. 3 illustrates a circuit diagram representation of a motor control system (100 in FIG. 1) for an electric vehicle in accordance with an embodiment of the present disclosure. The linking of various components and flow of signals for operation of the motor control system (100) for the electric vehicle has been explained above in FIG. 2.
[0028] FIG. 4 is a flow chart representing the steps involved in a method (300) of operation a motor control system for an electric vehicle of FIG. 1 in accordance with the embodiment of the present disclosure. The method (300) includes sensing, by multiple sensors, corresponding multiple real-time operational parameters associated with a motor of the electric vehicle in step 310. In one embodiment, sensing the multiple real-time operational parameters associated with the motor of the electric vehicle may include, but not limited to, sensing the multiple real-time operational parameters using a hall sensor, current sensor, a temperature sensor, a weight sensor, a traction sensor, a radar sensor, an altitude sensor, a fire sensor, a pressure sensor, an accelerometer and a gyro sensor.
[0029] The method (300) also includes receiving, by an electric vehicle control subsystem, each of multiple sensed values corresponding to each of multiple real-time sensed operational parameters in step 320. In some embodiment, receiving the each of the multiple sensed values corresponding to the each of the multiple sensed real-time sensed operational parameters may include but not limited to, receiving each of the multiple sensed values corresponding to at least one of one of speed, current, temperature, voltage, load, friction, relative speed, elevation, fire in the electric vehicle, pressure, acceleration or a combination thereof.
[0030] The method (300) also includes comparing, by the electric vehicle control subsystem, each of multiple sensed values with each of multiple predetermined threshold limits corresponding to multiple predetermined operational parameters stored in an operational parameter database in step 330. In one embodiment, comparing the each of the multiple sensed values with the each of the multiple predetermined threshold limits may include comparing a multiple of sensed actual values with each of a multiple of reference parameters stored in the operational parameter database.
[0031] The method (300) also includes generating, by the electric vehicle control subsystem, an error signal based on a difference determined from comparison of the multiple received real-time operational parameters with the multiple predetermined operational parameters in step 340. In one embodiment, generating the error signal based on the difference determined may include generating the error signal which may include at least one of error in speed response, error in torque response, error in regenerative braking response, error in current response, error in temperature response or a combination thereof.
[0032] The method (300) also includes converting, by the electric vehicle control subsystem, a generated error signal into variable duty ratio/frequency pulse width modulation (PWM) signal by performing a calibration activity based on a predefined requirement in step 350. In one embodiment, performing the calibration activity for conversion of the generated error signal into variable duty ratio/frequency pulse width modulation (PWM) signal may include performing a calibration of least two parameters of the PID controller, wherein the at least two parameters includes proportional gain (Kp) and integral gain (Ki).
[0033] The method (300) also includes controlling, by the electric vehicle control subsystem, performance of the motor to drive the electric vehicle based on duty ratio/frequency values obtained upon conversion of the generated error signal in step 360. In one embodiment, controlling the performance of the motor to drive the electric vehicle based on the duty ratio/frequency values obtained upon the conversion of the generated error signal may include controlling the speed and current of the motor by sending converted variable duty ratio /frequency PWM signal as an input to one or more switches of metal–oxide–semiconductor field-effect transistor (MOSFET) driver which in turn controls the speed and current of the motor.
[0034] Various embodiments of the present disclosure relate to a motor control system of the electric vehicle which helps in improvement of performance of the electric vehicle based on actual requirements by enabling the motor to supply more power for including more kilometres per battery charge. As a result, the efficiency of the vehicle performance increases and further improves overall user experience.
[0035] Moreover, the present disclosed system helps in upgrading the electric vehicle’s performance through a set of machine-generated instructions without changing the physical components of the electric vehicle.
[0036] Furthermore, the present disclosed system includes real-time intervention on operation of the electric vehicle for bringing additional safety and thus improves safety of the user, reliability and life of the vehicle and its components.
[0037] In addition to, the present disclosed system is less expensive with less components counts and thus easy to use for operation and maintenance of the electric vehicle.
[0038] It will be understood by those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the disclosure and are not intended to be restrictive thereof.
[0039] While specific language has been used to describe the disclosure, any limitations arising on account of the same are not intended. As would be apparent to a person skilled in the art, various working modifications may be made to the method in order to implement the inventive concept as taught herein.
[0040] The figures and the foregoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, the order of processes described herein may be changed and are not limited to the manner described herein. Moreover, the actions of any flow diagram need not be implemented in the order shown; nor do all of the acts need to be necessarily performed. Also, those acts that are not dependent on other acts may be performed in parallel with the other acts. The scope of embodiments is by no means limited by these specific examples.