DESC:METHOD AND SYSTEM FOR CONTROLLING MOTOR DRIVE
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims priority from Indian Provisional Patent Application No. 202221055798 filed on 28/09/2022, the entirety of which is incorporated herein by a reference.
TECHNICAL FIELD
The present disclosure generally relates to motor drive control. Particularly, the present disclosure relates to a method of controlling a power converter of a motor drive of an electric vehicle and a system for controlling a power converter of a motor drive 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 inefficient as a result of which the motor drives are not able to fulfil speed requirements and fail to control the acceleration and deceleration rate of the motor. The existing speed control in motor drives fails to fulfil torque demand and control acceleration or deceleration rate. Moreover, existing control strategies are unable to provide instantaneous torque commands with speed loops due to their slow response. Thus, the existing speed control strategies are not suitable for high-performance vehicle applications.
Therefore, there exists a need for a mechanism that overcomes the one or more problems associated with the existing motor drive controls as set forth above.
SUMMARY
An object of the present disclosure is to provide a method of controlling a power converter of a motor drive of an electric vehicle.
Another object of the present disclosure is to provide a system for controlling a power converter of a motor drive of an electric vehicle.
In accordance with the first aspect of the present disclosure, there is provided a method of controlling a power converter of a motor drive of an electric vehicle, the method comprising:
- generating a first component of reference current using a torque value;
- generating a second component of reference current using a speed value;
- generating a third component of reference current using an acceleration value;
- generating a reference current value based on the first component of reference current, the second component of reference current, and the third component of reference current; and
- generating a current demand based on the generated reference current value and feeding the generated current demand to a controller for controlling the power converter.
The present disclosure provides a method of controlling a power converter of a motor drive of an electric vehicle. The method, as disclosed in the present disclosure, is advantageous in terms of providing precise control for the power converter to control the operation of a power converter-fed motor both below and above the base speed. For achieving the control, the reference current value is to be generated by taking into account the torque, acceleration, and speed requirements. The required torque is anticipated by throttle command as provided by a rider and the obtained throttle command is used to generate the corresponding current command using a tuning block. The required speed is anticipated using throttle command and clutch engagement/disengagement. The required acceleration is anticipated based on the driving mode in which the rider is riding the vehicle. Beneficially, by considering the required acceleration, the weight aspect of the rider is taken into account for calculating the required reference current value and thus current demand. Hence, the method by considering torque, speed, and acceleration requirements, as well as considering the weight aspect, accurately determines the magnitude of current demand. The power converter of the motor drive is controlled, to meet the current demand.
In accordance with the second aspect of the present disclosure, there is provided a system for controlling a power converter of a motor drive of an electric vehicle, wherein the system comprises a tuning block configured to:
- generate a first component of reference current using a torque value;
- generate a second component of reference current using a speed value;
- generate a third component of reference current using an acceleration value;
- generate a reference current value based on the first component of reference current, the second component of reference current, and the third component of reference current; and
- generate a current demand based on the generated reference current value and feed the generated current demand to a controller for controlling the power converter.
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 flow chart of a method of controlling a power converter of a motor drive of an electric vehicle, in accordance with an aspect of the present disclosure.
Figure 2 illustrates a block diagram of a system for controlling a power converter of a motor drive 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 method of controlling a power converter of a motor drive 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 “power converter”, “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 drive” and “drive” are used interchangeably and refer to a motor along with 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 “reference current” and “base current” are used interchangeably and refer to a value of current which when compared with actual current generates a control command. In an ideal condition, actual current and reference current have equal values.
As used herein, the terms “reference current value” or “final reference current” are used interchangeably and refer to the sum of all the components of reference current i.e., first component, second component, and third component calculated based on torque, speed, and acceleration respectively.
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 “cruise mode” is used to refer to a driving mode that allows a rider to maintain a set speed without using the accelerator. This driving mode has a specified range of acceleration as defined by the manufacturer of the vehicle.
As used herein, the term “braking mode” is used to refer to a driving mode in which the rider uses the braking mechanism of the vehicle to stop the vehicle or reduce the speed of the vehicle. This driving mode has a specified range of acceleration as defined by the manufacturer of the vehicle.
As used herein, the term “acceleration mode” is used to refer to a driving mode in which the rider uses the accelerator mechanism of the vehicle to speed up the vehicle. This driving mode has a specified range of acceleration as defined by the manufacturer of the vehicle.
As used herein, the term “controller” 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 “PI controller” refers to the proportional-integral controller that combines proportional and integral control action. The PI controller provides a response to the current error between the setpoint and the actual value. The integral term provides a response to the accumulated error over time. The combination of these two terms allows the PI controller to both reduce the error quickly and eliminate steady-state error.
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 method 100 of controlling a power converter of a motor drive of an electric vehicle. The method 100 starts at step 102 and completes at step 110. At step 102, the method 100 comprises generating a first component of reference current using a torque value. At step 104, the method 100 comprises generating a second component of reference current using a speed value. At step 106, the method 100 comprises generating a third component of reference current using an acceleration value. At step 108, the method 100 comprises generating a reference current value based on the first component of reference current, the second component of reference current, and the third component of reference current. At step 110, the method 100 comprises generating a current demand based on the generated reference current value and feeding the generated current demand to a controller for controlling the power converter.
The method 100 is advantageous in terms of providing precise control for the power converter to control the operation of a power converter-fed motor both below and above the base speed. For achieving the control, the reference current value is to be generated by taking into account the torque, acceleration, and speed requirements. The required torque is anticipated by throttle command as provided by a rider and the obtained throttle command is used to generate the corresponding current command using a tuning block. The required speed is anticipated using throttle command and clutch engagement/disengagement. The required acceleration is anticipated based on the driving mode in which the rider is riding the vehicle. Beneficially, by considering the required acceleration, the weight aspect of the rider is taken into account for calculating the required reference current value and thus current demand. Hence, the method 100, by considering torque, speed, and acceleration requirements, as well as considering the weight aspect, accurately determines the magnitude of current demand. The power converter of the motor drive is controlled, to meet the current demand. Beneficially, the method 100 prevents the motor from reaching a speed higher than safe limits. Beneficially, the method 100 maintains a controlled current for required torque. Beneficially, the method 100 provides direct control from the throttle for speed and torque control of the motor. Beneficially, the method 100 provides speed control for limiting the speed of the motor in safe limits. Beneficially, the method 100 provides torque control for enhanced rider experience. Beneficially, the method 100 provides acceleration and deceleration control for enhanced drive mode experience and smooth operation of the motor.
In an embodiment, the method 100 comprises calculating the torque value based on a throttle position of the vehicle. Beneficially, the torque value is determined based on the angle at which the throttle is positioned. In a specific embodiment, a relationship between the torque value and the throttle position may be linear. In an alternative specific embodiment, the relationship between the torque value and the throttle position may be non-linear.
In an embodiment, the method 100 comprises calculating the speed value based on a difference between a motor speed and a desired vehicle speed. Beneficially, a closed-loop control is utilized to calculate the speed value based on a difference between a motor speed and a desired vehicle speed. It is to be understood that the closed-loop control monitors the speed of the vehicle and compares it to the desired speed. The closed-loop control then adjusts the speed of the motor to bring the vehicle speed in line with the desired speed.
In an embodiment, the method 100 comprises calculating the acceleration value based on a difference between a motor acceleration and a desired acceleration. Beneficially, the acceleration value determines how quickly the vehicle is accelerating, based on the speed of the electric motor and the desired acceleration. It is to be understood that the closed-loop control monitors the acceleration of the vehicle and compares it to the desired acceleration. The closed-loop control then adjusts the speed of the motor to bring the vehicle acceleration in line with the desired acceleration.
In an embodiment, the method 100 comprises determining the desired acceleration based on at least one drive mode of the electric vehicle. Beneficially, the desired acceleration is utilized to determine how quickly the vehicle should accelerate based on the selected drive mode.
In an embodiment, the at least one drive mode comprises a cruise mode, a braking mode, and an acceleration mode. Beneficially, the control of the motor is optimized based on whether the electric vehicle is in the cruise mode, the braking mode, or in the acceleration mode.
In an embodiment, the method 100 comprises limiting a maximum value and a minimum value of the current demand based on operational thresholds of the power controller. Beneficially, limiting the maximum value and the minimum value of the current demand protects the motor from operating at speeds that may damage the motor.
In an embodiment, the method 100 comprises training a tuning block for generating the first component of reference current using the torque value, the second component of reference current using the speed value, and the third component of reference current using the acceleration value. Beneficially, the tuning block is trained to generate accurate and error-free values of components of reference current.
In an embodiment, the tuning block is a PI controller with a negative feedback loop. Beneficially, the PI controller with a negative feedback loop uses proportional and integral control action to reduce the error between a desired value and an actual value. Furthermore, the negative feedback loop ensures that the controller always works to reduce the error, rather than amplify it.
In an embodiment, the method 100 comprises generating the first component of reference current using the torque value, generating the second component of reference current using the speed value, generating the third component of reference current using the acceleration value, generating the reference current value based on the first component of reference current, the second component of reference current, and the third component of reference current, and generating the current demand based on the generated reference current value and feeding the generated current demand to the controller for controlling the power converter. Furthermore, the method 100 comprises calculating the torque value based on the throttle position of the vehicle. Furthermore, the method 100 comprises calculating the speed value based on the difference between the motor speed and the desired vehicle speed. Furthermore, the method 100 comprises calculating the acceleration value based on the difference between the motor acceleration and the desired acceleration. Furthermore, the method 100 comprises determining the desired acceleration based on the at least one drive mode of the electric vehicle. Furthermore, the at least one drive mode comprises the cruise mode, the braking mode, and the acceleration mode. Furthermore, the method 100 comprises limiting the maximum value and the minimum value of the current demand based on the operational thresholds of the power controller. Furthermore, the method 100 comprises training the tuning block for generating the first component of reference current using the torque value, the second component of reference current using the speed value, and the third component of reference current using the acceleration value. Furthermore, the tuning block is the PI controller with the negative feedback loop.
Figure 2, describes a system 200 for controlling a power converter of a motor drive of an electric vehicle The system 200 comprises a tuning block 202 configured to generate a first component of reference current using a torque value, generate a second component of reference current using a speed value, generate a third component of reference current using an acceleration value, generate a reference current value based on the first component of reference current, the second component of reference current, and the third component of reference current, and generate a current demand based on the generated reference current value and feed the generated current demand to a controller for controlling the power converter.
In an embodiment, the tuning block 202 is a PI controller with a negative feedback loop.
It would be appreciated that all the explanations and embodiments of the method 100 also apply mutatis-mutandis to the system 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 method (100) of controlling a power converter of a motor drive of an electric vehicle, the method (100) comprising:
- generating a first component of reference current using a torque value;
- generating a second component of reference current using a speed value;
- generating a third component of reference current using an acceleration value;
- generating a reference current value based on the first component of reference current, the second component of reference current, and the third component of reference current; and
- generating a current demand based on the generated reference current value and feeding the generated current demand to a controller for controlling the power converter.
2. The method (100) as claimed in claim 1, wherein the method (100) comprises calculating the torque value based on a throttle position of the vehicle.
3. The method (100) as claimed in claim 1, wherein the method (100) comprises calculating the speed value based on a difference between a motor speed and a desired vehicle speed.
4. The method (100) as claimed in claim 1, wherein the method (100) comprises calculating the acceleration value based on a difference between a motor acceleration and a desired acceleration.
5. The method (100) as claimed in claim 4, wherein the method (100) comprises determining the desired acceleration based on at least one drive mode of the electric vehicle.
6. The method (100) as claimed in claim 5, wherein the at least one drive mode comprises a cruise mode, a braking mode, and an acceleration mode.
7. The method (100) as claimed in claim 1, wherein the method (100) comprises limiting a maximum value and a minimum value of the current demand based on operational thresholds of the power controller.
8. The method (100) as claimed in claim 1, wherein the method (100) comprises training a tuning block for generating:
- the first component of reference current using the torque value;
- the second component of reference current using the speed value; and
- the third component of reference current using the acceleration value.
9. The method (100) as claimed in claim 8, wherein the tuning block is a PI controller with a negative feedback loop.
10. A system (200) for controlling a power converter of a motor drive of an electric vehicle, wherein the system (200) comprises a tuning block (202) configured to:
- generate a first component of reference current using a torque value;
- generate a second component of reference current using a speed value;
- generate a third component of reference current using an acceleration value;
- generate a reference current value based on the first component of reference current, the second component of reference current, and the third component of reference current; and
- generate a current demand based on the generated reference current value and feed the generated current demand to a controller for controlling the power converter.