DESC:CONTROLLER FOR POWER TRAIN OF ELECTRIC VEHICLE
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims priority from Indian Provisional Patent Application No. 202321020837 filed on 24/03/2024, the entirety of which is incorporated herein by a reference.
TECHNICAL FIELD
The present disclosure generally relates to motor control in electric vehicles. Particularly, the present disclosure relates to a control system for controlling a powertrain of an electric vehicle. Furthermore, the present disclosure relates to a method of controlling a powertrain of an electric vehicle.
BACKGROUND
Recently, there has been a rapid development in electric vehicles because of their ability to resolve pollution-related problems and serve as a clean mode of transportation. Generally, electric vehicles include a power pack, and/or combination of electric cells for storing electricity required for the propulsion of the vehicles. The electrical power stored in the power pack of the electric vehicle is supplied to the traction motor and various other electrical components for the operation of the electric vehicle.
For the traction motor, a wide operating speed range above the base speed (e.g., a high-speed cruise) is often required. Therefore, it is required for the electrical propulsion systems i.e., electric motor drives to operate efficiently both below the base speed and above the base speed and meet the required torque demands. In order to achieve the above, various control strategies are used to control the motor drive which in turn controls the traction motor.
Typically, various torque control strategies are used in motor drives for computing motor current. However, available torque control strategies are incapable of controlling the motor to keep the motor operation stable. The existing torque control strategies compromises on stability of the operation while providing sudden acceleration or deceleration. In the existing motor control, due to the sudden change in speed or torque (due to various reasons) causes the problem of destabilization or loss of control of the operation of motor.
Therefore, there exists a need for a mechanism that overcomes the one or more problems associated with the existing motor controls as set forth above.
SUMMARY
An object of the present disclosure is to provide a control system for controlling a powertrain of an electric vehicle.
Another object of the present disclosure is to provide a method of controlling a powertrain of an electric vehicle.
In accordance with the first aspect of the present disclosure, there is provided a control system for controlling a powertrain of an electric vehicle. The control system comprises a control unit. The control unit is configured to execute a control loop, and execute an error loop, along with the control loop to maintain control of a motor in field weakening region of operation, when a control error is greater than a threshold.
The control system is advantageous in terms of providing precise control of the motor. The control system of the present disclosure is advantageous in terms of preventing the motor from operating in unstable region and beneficially, keep the motor operation in the field weakening region during any control error. Beneficially, the control system prevents the motor from reaching a speed higher than safe limits. Beneficially, the control system maintains a controlled current for required torque. Beneficially, the control system provides speed control for limiting the speed of the motor in safe limits. Beneficially, the control system provides acceleration and deceleration control for enhanced drive mode experience and smooth operation of the motor. Beneficially, the control system of the present disclosure is advantageous in terms of providing a smooth and safe operation of the motor.
In accordance with the second aspect of the present disclosure, there is provided a method of controlling a powertrain of an electric vehicle. the method comprises executing a control loop, and executing an error loop, along with the control loop to maintain control of a motor in field weakening region of operation, when a control error is greater than a threshold.
Additional aspects, advantages, features, and objects of the present disclosure would be made apparent from the drawings and the detailed description of the illustrative embodiments constructed in conjunction with the appended claims that follow.
It will be appreciated that features of the present disclosure are susceptible to being combined in various combinations without departing from the scope of the present disclosure as defined by the appended claims.
BRIEF DESCRIPTION OF DRAWINGS
The summary above, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the present disclosure is not limited to specific methods and instrumentalities disclosed herein. Moreover, those in the art will understand that the drawings are not to scale. Wherever possible, like elements have been indicated by identical numbers.
Embodiments of the present disclosure will now be described, by way of example only, with reference to the following diagrams wherein:
Figure 1 illustrates a block diagram of a control system for controlling a powertrain of an electric vehicle, in accordance with an aspect of the present disclosure.
Figure 2 illustrates a flow chart a method of controlling a powertrain of an electric vehicle, in accordance with another aspect of the present disclosure.
In the accompanying drawings, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the non-underlined number to the item. When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing.
DETAILED DESCRIPTION
The following detailed description illustrates embodiments of the present disclosure and ways in which they can be implemented. Although some modes of carrying out the present disclosure have been disclosed, those skilled in the art would recognize that other embodiments for carrying out or practicing the present disclosure are also possible.
The description set forth below in connection with the appended drawings is intended as a description of certain embodiments of a control system for controlling a powertrain of an electric vehicle and is not intended to represent the only forms that may be developed or utilized. The description sets forth the various structures and/or functions in connection with the illustrated embodiments; however, it is to be understood that the disclosed embodiments are merely exemplary of the disclosure that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.
While the disclosure is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the drawings and will be described in detail below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure.
The terms “comprise”, “comprises”, “comprising”, “include(s)”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a setup, or system that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or system. In other words, one or more elements in a system or apparatus preceded by “comprises... a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or apparatus.
In the following detailed description of the embodiments of the disclosure, reference is made to the accompanying drawings which are shown by way of illustration-specific embodiments in which the disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present disclosure. The following description is, therefore, not to be taken in a limiting sense.
The present disclosure will be described herein below with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail since they would obscure the description with unnecessary detail.
As used herein, the terms “electric vehicle”, “EV”, and “EVs” are used interchangeably and refer to any vehicle having stored electrical energy, including the vehicle capable of being charged from an external electrical power source. This may include vehicles having batteries that are exclusively charged from an external power source, as well as hybrid vehicles which may include batteries capable of being at least partially recharged via an external power source. Additionally, it is to be understood that the ‘electric vehicle’ as used herein includes electric two-wheelers, electric three-wheelers, electric four-wheelers, electric pickup trucks, electric trucks, and so forth.
As used herein, the terms “power pack” “battery pack”, “battery”, and “power source” are used interchangeably and refer to multiple individual battery cells connected to provide a higher combined voltage or capacity than a single battery. The power pack is designed to store electrical energy and supply it as needed to various devices or systems. Power pack, as referred herein may be used for various purposes such as power electric vehicles and other energy storage applications. Furthermore, the power pack may include additional circuitry, such as a battery management system (BMS), to ensure the safe and efficient charging and discharging of the battery cells. The power pack comprises a plurality of cell arrays which in turn comprises a plurality of battery cells.
As used herein, the terms “traction inverter”, “converter” and “inverter” are used interchangeably and refer to an electronic device that converts DC power to AC power as used in the electric vehicle motor. The power converter can change the speed at which the motor rotates by adjusting the frequency of the alternating current.
As used herein, the terms “motor control system” and “motor drive” are used interchangeably and refer to control electronics configured to harness and control the electrical energy sent to the motor. The drive feeds electric current into the motor in varying amounts and at varying frequencies, thereby indirectly controlling the motor’s speed and torque.
As used herein, the terms “throttle”, “throttle valve”, and “throttle command” are used interchangeably and refer to a vehicle control input, facilitating the integration of features such as cruise control, traction control, stability control, and precrash systems and others that require torque management.
As used herein, the terms “field-weakening command” and “field-weakening current” are used interchangeably and refer to a value of current used for weakening the field of the motor to limit the magnitude of back emf in the motor.
As used herein, the term “control unit” refers to a computing unit of the electric vehicle that controls and coordinates the operation of the vehicle's various subsystems, including the power converter, electric motor, charging system, and braking system. The control unit is responsible for optimizing the vehicle's performance, efficiency, and safety. The control unit may comprise a microprocessor.
As used herein, the terms “microcontroller”, “microprocessor” and “processor” are used interchangeably and refer to a computational element that is operable to respond to and process instructions that drive the system. Optionally, the microprocessor may be a micro-controller, a complex instruction set computing (CISC) microprocessor, a reduced instruction set (RISC) microprocessor, a very long instruction word (VLIW) microprocessor, or any other type of processing unit. Furthermore, the term “microprocessor” may refer to one or more individual processors, processing devices, and various elements associated with a processing device that may be shared by other processing devices. Furthermore, the microprocessor may be designed to handle real-time tasks with high performance and low power consumption. Furthermore, the microprocessor may comprise custom and/or proprietary processors.
As used herein, the term “control loop” refers to a feedback loop constantly monitoring the motor's output and adjusting its input to ensure it aligns with a desired set point.
As used herein, the term “error loop” refers to additional safety feedback loop deployed along with the control loop to stabilize the motor operation.
As used herein, the term “control error” refers to instances when the motor’s output is beyond the control thresholds of the control loop.
As used herein, the term “communicably coupled” refers to a communicational connection between the various components of the system. The communicational connection between the various components of the system enables the exchange of data between two or more components of the system.
Figure 1, in accordance with an embodiment, describes a control system 100 for controlling a powertrain of an electric vehicle. The control system 100 comprises a control unit 102. The control unit 102 is configured to execute a control loop, and execute an error loop, along with the control loop to maintain control of a motor 104 in field weakening region of operation, when a control error is greater than a threshold.
The control system 100 is advantageous in terms of providing precise control of the motor 104. The control system 100 of the present disclosure is advantageous in terms of preventing the motor 104 from operating in unstable region and beneficially, keep the motor operation in the field weakening region during any control error. Beneficially, the control system 100 prevents the motor 104 from reaching a speed higher than safe limits. Beneficially, the control system 100 maintains a controlled current for required torque. Beneficially, the control system 100 provides speed control for limiting the speed of the motor 104 in safe limits. Beneficially, the control system 100 provides acceleration and deceleration control for enhanced drive mode experience and smooth operation of the motor 104. Beneficially, the control system 100 of the present disclosure is advantageous in terms of providing a smooth and safe operation of the motor 104.
In an embodiment, the control unit 102 is configured to operate a traction inverter 106 to maintain control of the motor 104 of the powertrain. Beneficially, the control unit 102 is communicably coupled to the traction inverter 106 to control the operation of the motor 104. It is to be understood that the traction inverter 106 may operate at variable frequencies to control the operation of the motor 104, based on the instructions received from the control unit 102.
In an embodiment, the control loop comprises a direct axis control reference current and a quadrature axis control reference current. Beneficially, the direct axis control reference current enables flux control in the motor 104. Furthermore beneficially, the quadrature axis control reference current enables torque control in the motor 104.
In an embodiment, the error loop comprises a direct axis error reference current. Beneficially, the direct axis error reference current enables flux control in the motor 104, when the control error occurs.
In an embodiment, the error loop is added to the control loop, when the control error is greater than the threshold to maintain control of the motor 104. Beneficially, the error loop enables stable control of the motor 104 when there may be possibility of loss of control due to the control error being greater than a threshold which is beyond the control of the control loop.
In an embodiment, the direct axis error reference current of the error loop is added to the direct axis control reference current, when the control error is greater than the threshold to maintain control of the motor 104. Beneficially, the error loop enables stable flux control of the motor 104 (ensuring the operation of the motor 104 in field weakening region) when there may be possibility of loss of control due to the control error being greater than a threshold which is beyond the control of the control loop.
In an embodiment, the control error is determined by the control unit 102 based on at least one of: a motor speed and a fault condition. Beneficially, the determination of the control error by the control unit 102 enable activation of the error loop.
In an embodiment, the error loop is normalized with a ramp rate before execution by the control unit 102 for maintaining smooth transition of operation of the motor 104. Beneficially, the normalization of the error loop with ramp rate enables smooth along with stable operation of the motor 104. It is be understood that the normalization of the error with ramp rate prevent any jerk or sudden change in operation of the motor 104.
In an embodiment, the threshold of the at least one of: the motor speed and the fault condition is dependent on characteristics of the motor 104. Beneficially, the motor speed and fault conditions (such as overcurrent, overvoltage and/or overtemperature) may be dependent on the physical characteristics of the motor 104. Beneficially, the threshold of the at least one of: the motor speed and the fault condition may be defined according to the motor utilized in the powertrain of the electric vehicle.
In an embodiment, the control system 100 comprises the control unit 102. The control unit 102 is configured to execute the control loop, and execute the error loop, along with the control loop to maintain control of the motor 104 in field weakening region of operation, when the control error is greater than the threshold. Furthermore, the control unit 102 is configured to operate a traction inverter 106 to maintain control of the motor 104 of the powertrain. Furthermore, the control loop comprises a direct axis control reference current and quadrature axis control reference current. Furthermore, the error loop comprises a direct axis error reference current. Furthermore, the error loop is added to the control loop, when the control error is greater than the threshold to maintain control of the motor 104. Furthermore, the direct axis error reference current of the error loop is added to the direct axis control reference current, when the control error is greater than the threshold to maintain control of the motor 104. Furthermore, the control error is determined by the control unit 102 based on at least one of: a motor speed and a fault condition. Furthermore, the error loop is normalized with a ramp rate before execution by the control unit 102 for maintaining smooth transition of operation of the motor 104. Furthermore, the threshold of the at least one of: the motor speed and the fault condition is dependent on characteristics of the motor 104.
Figure 2, describes a method 200 of controlling a powertrain of an electric vehicle. The method 200 starts at step 202 and finishes at step 204. At step 202, the method 200 comprises executing a control loop. At step 204, the method 200 comprises executing an error loop, along with the control loop to maintain control of a motor 104 in field weakening region of operation, when a control error is greater than a threshold.
In an embodiment, the method 200 comprises operating a traction inverter 106 to maintain control of the motor 104 of the powertrain.
In an embodiment, the control loop comprises a direct axis control reference current and a quadrature axis control reference current.
In an embodiment, the error loop comprises a direct axis error reference current.
In an embodiment, the method 200 comprises adding the error loop to the control loop, when the control error is greater than the threshold to maintain control of the motor 104.
In an embodiment, the method 200 comprises adding the direct axis error reference current of the error loop to the direct axis control reference current, when the control error is greater than the threshold to maintain control of the motor 104.
In an embodiment, the method 200 comprises determining the control error by the control unit 102 based on at least one of: a motor speed and a fault condition.
In an embodiment, the method 200 comprises normalizing the error loop with a ramp rate before execution by the control unit 102 for maintaining smooth transition of operation of the motor 104.
In an embodiment, the threshold of the at least one of: the motor speed and the fault condition is dependent on characteristics of the motor 104.
It would be appreciated that all the explanations and embodiments of the system 100 also apply mutatis-mutandis to the method 200.
In the description of the present invention, it is also to be noted that, unless otherwise explicitly specified or limited, the terms “disposed”, “mounted,” and “connected” are to be construed broadly, and may for example be fixedly connected, detachably connected, or integrally connected, either mechanically or electrically. They may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Modifications to embodiments and combinations of different embodiments of the present disclosure described in the foregoing are possible without departing from the scope of the present disclosure as defined by the accompanying claims. Expressions such as “including”, “comprising”, “incorporating”, “have”, and “is” used to describe and claim the present disclosure are intended to be construed in a non-exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural where appropriate.
Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the present disclosure, the drawings, and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.
,CLAIMS:WE CLAIM:
1. A control system (100) for controlling a powertrain of an electric vehicle, wherein the control system (100) comprises a control unit (102) configured to:
- execute a control loop; and
- execute an error loop, along with the control loop to maintain control of a motor (104) in field weakening region of operation, when a control error is greater than a threshold.
2. The control system (100) as claimed in claim 1, wherein the control unit (102) is configured to operate a traction inverter (106) to maintain control of the motor (104) of the powertrain.
3. The control system (100) as claimed in claim 1, wherein the control loop comprises a direct axis control reference current and a quadrature axis control reference current.
4. The control system (100) as claimed in claim 1, wherein the error loop comprises a direct axis error reference current.
5. The control system (100) as claimed in claim 1, wherein the error loop is added to the control loop, when the control error is greater than the threshold to maintain control of the motor (104).
6. The control system (100) as claimed in claim 5, wherein the direct axis error reference current of the error loop is added to the direct axis control reference current, when the control error is greater than the threshold to maintain control of the motor (104).
7. The control system (100) as claimed in claim 1, wherein the control error is determined by the control unit (102) based on at least one of: a motor speed and a fault condition.
8. The control system (100) as claimed in claim 1, wherein the error loop is normalized with a ramp rate before execution by the control unit (102) for maintaining smooth transition of operation of the motor (104).
9. The control system (100) as claimed in claim 1, wherein the threshold of the at least one of: the motor speed and the fault condition is dependent on characteristics of the motor (104).
10. A method (200) of controlling a powertrain of an electric vehicle, wherein the method (200) comprises:
- executing a control loop; and
- executing an error loop, along with the control loop to maintain control of a motor (104) in field weakening region of operation, when a control error is greater than a threshold.