Method for controlling motor

Abstract

The present disclosure relates to a method (100) of controlling an electric machine, comprising the step of determining (101) current errors of the d-axis and q-axis of the electric machine. Further, the method (100) includes the step (102) of providing a current error to a current controller of the electric machine, where the current controller is a field-oriented control (FOC) current controller. Furthermore, the method (100) comprises a step (103) of determining PI parameters for the d-axis and the q-axis in a current controller. The PI parameter comprises a proportional gain value and an integral gain value. Further, the method (100) comprises controlling (104) the electric machine to adjust the current based on the PI parameter.

Description

Technical Field

[0001] This disclosure relates to a control method for an electric motor and a current controller for the electric motor. Background Technology

[0002] In electric motors, rapid and precise current control is crucial for maintaining the required torque and speed under varying load conditions. By ensuring instantaneous torque response, electric vehicles (EVs) can provide smooth acceleration and deceleration, enhancing the driving experience and safety. This precise control also plays a vital role in optimizing energy efficiency and extending vehicle range by reducing unnecessary power loss. Overall, the ability to quickly and accurately regulate current is key to maximizing the performance, safety, and range of electric vehicles.

[0003] Currently, several methods exist for effectively implementing current control. However, these methods are impractical in real-world applications. One example is deadbeat predictive current control (DPCC). This method predicts the current within a single sample, using the next current as a reference, thus achieving convergence within that sample. While DPCC performs as expected in terms of characteristics, its practical implementation presents challenges. Implementing DPCC in motor current controllers is cumbersome, partly because it imposes an excessive computational burden on the controller.

[0004] Therefore, an improved method is needed to control the current of electric vehicle motors more effectively. Summary of the Invention

[0005] Therefore, the object of this disclosure is to provide a method for controlling a motor to at least improve some of the aforementioned disadvantages. Furthermore, this disclosure provides a current controller.

[0006] This disclosure is based, at least in part, on the insight that the method provided herein is more efficient than conventional methods used in known current controllers. The method disclosed herein can advantageously provide fast response and accuracy in motor current control without unduly impacting the computational load of the current controller, and can also provide improved dynamic characteristics to known current controllers.

[0007] This disclosure relates to a method for controlling a motor, the steps of which include determining a current error of the motor, the current error being based on the difference between a reference current and a measured current of the motor. The reference current may be a current setpoint / point obtained from a controller, a parameter table, or a direct input. The reference current may be a DC current, a d-axis current, or a q-axis current. The measured current may be an actual current (measured, e.g., by a sensor device) or based on, for example, an actual measured current flowing through the stator windings of the motor. The measured current may be a DC current converted from AC current. The current error may be the difference between the measured current and the reference current. The method steps also include providing the current error to a current controller of the motor. The current controller may be configured to determine (possibly including selecting / applying / receiving) PI parameters to adjust current control. The current controller may include a proportional-integral model, i.e., a PI model, which uses the PI parameters to regulate the current. The input to the current controller is adjusted through this PI model to reach the level of the reference current as quickly as possible. More specifically, the current controller may be configured to iteratively reduce or eliminate the current error using a current feedback loop and the PI parameters. This current control method ensures that the current controller adjusts the input current to the same value as the reference current within an extremely short response time, for example, at a response level of microseconds (μs) to milliseconds (ms). This method and current controller thus improve the efficiency and dynamic characteristics of motor current control. Furthermore, the method includes determining the PI parameters for the current controller, including the proportional gain value K. p and integral gain value K i Furthermore, the method steps also include controlling the motor using the PI parameters and current error via the current controller.

[0008] Advantageously, this method enables current control to operate with a fast dynamic response while maintaining computational efficiency. This reduces the hardware cost of using this method and current controller to control the motor.

[0009] The PI parameters can be determined based on the inductance-resistance characteristics of the motor windings. If this method is used for a permanent magnet synchronous motor (PMSM), the windings can be the stator windings.

[0010] One advantage of determining the PI parameters based on the inductance-resistance characteristics of the winding is that it simplifies the method for optimizing the PI gain expression and improves its accuracy. This method can reduce the real-time computational load on the processor executing the method, while allowing for efficient parameter control.

[0011] In some respects, K p The value can be determined based on a function, in which K... p The value may depend on the motor winding resistance R, the motor winding inductance / stator inductance L, and the sampling parameter P.cs and tuning parameter K c .

[0012] In some respects, K i The value can be determined based on a function, in which K... p The value depends on R and P. cs K c .

[0013] Particularly advantageous is if K is determined based on the above functional relationship. p and K i If the value is K, then c P cs R and L can be used to determine K p And Ki, thus making it simpler and more efficient to derive the PI parameter (because the general parameter can be used for K). p It can also be used for Ki).

[0014] K c It can be a predetermined constant. Therefore, K c It can be adjusted / determined once and then kept constant in all operating states of the current controller. Therefore, the computational burden on the current controller will be further reduced because K... c It may be a constant that is preset and remains unchanged / static / fixed for all operating states of the current controller. K c It can be any suitable constant, such as an integer.

[0015] In some respects, the K p The value can be based on the function f(P) CS (L, R), and

[0016] ,

[0017] In some respects, the K p The value can be determined according to the following equation:

[0018]

[0019] Furthermore, in some respects, the K i The value can be based on the function f(P) CS (R)

[0020] in .

[0021] Furthermore, in some respects, the K i The value can be determined according to the following equation:

[0022] .

[0023] Therefore, K p and K i The value can be determined based on the function described above, for example by manipulating or transforming the function expression, or by explicitly using the equation.

[0024] Advantageously, these functions use a small number of readily available parameters. For example, R and L can be derived from hardware parameters or measured by sensor devices. Furthermore, Kc can be preset / fixed / pre-tuned. This provides a fast, efficient, and flexible approach.

[0025] Sampling parameter P cs It can be based on the switching frequency of the inverter of the motor. or sampling time T s Therefore, based on the switching frequency... At that time, the sampling parameter can be the crossover angular frequency. Switching frequency The relationship with the crossover angular frequency can be expressed as: , where n is an integer, preferably 10. The crossover frequency may be approximately 1 / 10 of the switching frequency.

[0026] Advantageously, this allows the current controller to provide stable control across all speed, torque, and frequency ranges. Therefore, even if the switching frequency changes, the PI parameters will follow these changes because they depend on the inverter's switching frequency.

[0027] Crossover angular frequency It can also be expressed as a preset fraction of the inverter's switching frequency, where the fraction is based on the assumption that the maximum crossover frequency is... Approximately the switching frequency 1 / 10. The inverter switching frequency can be changed according to the selection of those skilled in the art. For example, the switching frequency can be between 2kHz and 100kHz.

[0028] In some respects, the method may include using a current controller, utilizing PI parameters, K... p K i and current error I e Determine the voltage setpoint U set Thus, the motor is controlled, and the voltage setpoint U set It can be derived based on the following expression:

[0029] .

[0030] Among them, U set It is the voltage setpoint, I e This represents the current error, where s is a Laplace complex variable. U setIt can also be derived based on a combination of a preset feedforward voltage value and the above expression. Feedforward voltage is often used to improve the output dynamics of current controllers.

[0031] The voltage setpoint can be used as a control signal, that is, to determine the applied voltage value to control the motor operation, such as operating the motor to make the actual current value reach the reference current value.

[0032] The control process can be achieved by using an inverter to control the voltage output to the motor. The voltage setpoint can be based on the DC voltage value input to the inverter, which is then converted to AC voltage to control the motor.

[0033] An inverter may contain suitable modules and components for implementation according to any of the methods disclosed herein.

[0034] Furthermore, the current controller in this paper can be a current controller employing a field-oriented control (FOC) method. The current error can be either the d-axis current error or the q-axis current error of the motor. This FOC current controller can include PI models for the d-axis current and q-axis current, respectively. Additionally, the K values ​​for both the d-axis and q-axis can be determined simultaneously. p and K i Thus, K is derived. pd K pq K id K iq The PI parameters for the d-axis and q-axis may differ, depending on the specific inductor resistance characteristics; for example, the R and L values ​​for the d-axis and q-axis may differ.

[0035] Furthermore, the current controller in this paper can be a single-parameter tuned FOC current controller. The single parameter can be K. c。 A single-parameter tuned FOC current controller can perform more convenient and efficient current control.

[0036] This disclosure also relates to a current controller for a motor, wherein the current controller is configured to determine a current error of the motor, the current error being based on the difference between a reference current and a measured current of the motor. Further, the current controller is configured to determine a set of PI parameters for adjusting the voltage output of the current controller. Therefore, the current controller is configured to determine the PI parameters, the PI parameters including a proportional gain value K. p And the integral gain value Ki. The current can be obtained using PI parameters through a PI model. Furthermore, the current controller is configured to provide its output based on the PI parameters and the current error, the output of which may be a voltage setpoint derived therefrom to obtain the voltage for controlling the motor.

[0037] The current error can be either the d-axis current error or the q-axis current error of the motor. The FOC current controller can include separate PI models for the d-axis current and the q-axis current. Furthermore, the K values ​​for both the d-axis and q-axis can be determined simultaneously. p and K i Thus, K is derived. pd、 K pq、 K id、 K iq The PI parameters for the d-axis and q-axis may be different, depending on the different inductor resistance characteristics; for example, the R and L values ​​for the d-axis and q-axis may be different.

[0038] Current controllers can provide at least similar advantages to the methods disclosed herein. To avoid excessive repetition, their advantages will not be elaborated further.

[0039] This disclosure also relates to a motor control system including a current controller according to any aspect herein. The motor control system may further include an inverter and a pair of conversion modules enabling the current controller to use values ​​from a rotating reference frame. The conversion modules may refer to modules well known to those skilled in the art, such as Clark / Parker conversion modules, etc.

[0040] A current controller can provide an output signal, such as a DC voltage setpoint for the rotor of a DC motor, a DC-DC converter, or an electrically excited synchronous motor. Alternatively, the voltage setpoint can be a D / Q voltage value converted to AC voltage to control the motor. When an FOC current controller is involved, it can provide d-axis and q-axis voltage setpoints. The voltage setpoint can be provided by an inverter to output a three-phase AC voltage for controlling motors, such as permanent magnet synchronous motors or other types of AC motors. The current controller can utilize the PI parameters to regulate the rectified or converted current to charge the power supply.

[0041] An inverter may include suitable modules and components for operation in accordance with the methods disclosed in any aspect of this document.

[0042] Furthermore, this disclosure relates to a motor control system (also referred to as an electric drive system), including a current controller and / or inverter in any aspect thereof. In some aspects, the current controller may be implemented as a software module within the motor control system, for example, stored on a storage medium within the inverter. The current controller may be implemented in a separate control device that can be connected to the inverter. The inverter may be a device connected between the battery pack and the motor of an electric vehicle. The inverter may be configured to control the speed and torque of the motor. The inverter may include controllable switches and control components for converting, for example, direct current (DC) to alternating current (AC). Attached Figure Description

[0043] To further clarify and describe these features and advantages of the technical solutions disclosed herein in more detail, the following details various specific embodiments will be described in detail with reference to the following drawings, wherein:

[0044] Figure 1 A schematic diagram of a motor control system according to certain aspects of this disclosure;

[0045] Figure 2 A schematic diagram of a current controller according to certain aspects of this disclosure; and

[0046] Figure 3 This is a flowchart illustrating a method for controlling a motor according to certain aspects of this disclosure. Detailed Implementation

[0047] In the following detailed description, some embodiments of the present disclosure will be described. However, it should be understood that, unless otherwise specifically described, features of different embodiments are interchangeable between embodiments and can be combined in different ways. Although numerous specific details are set forth in the following description to provide a more thorough understanding of the present disclosure, it will be apparent to those skilled in the art that such practices may be carried out without these specific details. In other instances, well-known structures or functions have not been described in detail so as not to obscure the content of this disclosure.

[0048] It should also be understood that the terminology used herein is for the purpose of describing specific aspects only and is not intended to be limiting. It should be noted that the terms “a,” “an,” “this,” and “said,” as used in the specification and appended claims, are intended to indicate the presence of one or more elements, unless the context explicitly specifies otherwise. Thus, for example, in some contexts, a reference to “a unit” or “unit” may refer to multiple units, etc. Furthermore, words such as “with,” “comprising,” and “including” do not exclude other elements or steps. It should be emphasized that the term “comprising / including” is used in this specification to specify the presence of a specified feature, integer, step, or component. It does not exclude the presence or addition of one or more other features, integers, steps, components, or groups thereof. The term “and / or” should also be interpreted as “both,” and each should be used as an alternative. More specifically, the phrase “one or more” of a group of elements (such as “one or more of A, B, and C” or “at least one of A, B, and C”) should be interpreted as a conjunction or disjunctive logic. In other words, it can refer to all elements, one element, or a combination of two or more elements of a group of elements. For example, the phrase "A, B and C" can be interpreted as A or B or C, A and B and C, A and B, B and C, or A and C.

[0049] It will also be understood that although the terms first, second, etc., may be used herein to describe various elements or features, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element, without departing from the scope of the embodiments. The first element and the second element are both elements, but they are not the same element.

[0050] The term “electric vehicle” as used in this article may refer to a fully electric vehicle, also known as an electric car, a plug-in hybrid electric vehicle, also known as a plug-in hybrid electric vehicle, or a hybrid electric vehicle, also known as a hybrid electric vehicle, where a hybrid electric vehicle refers to a vehicle that uses multiple propulsion sources, one of which is an electric drive system.

[0051] The term "electric motor" refers to an electromechanical power conversion machine, such as an electric motor or generator. The type of electric motor or generator can be any type commonly known to those skilled in the art.

[0052] The term DC as used in this article can refer to direct current, and the term AC can refer to alternating current.

[0053] The terms “d-axis” and “q-axis” or “dq value” used in this disclosure generally refer to the direct axis and the orthogonal axis, and are commonly used terms in motor control technology, such as field-oriented control (FOC).

[0054] From a geometric perspective, the d-axis and q-axis can be viewed as a two-dimensional representation of the magnetic flux contributed by three independent sinusoidal phasors of a three-phase motor. The d-axis is the axis that generates flux. The q-axis, or orthogonal axis, is the axis that generates torque. The d-axis and q-axis are perpendicular to each other. Therefore, the q-axis is 90 degrees out of phase with the d-axis. Simply put, the d-axis is the dominant direction of magnetic flux in the rotor, while the q-axis is the dominant direction of torque generation.

[0055] Therefore, the current in the motor can be converted to a dq reference frame, which allows the current controller to manipulate and control the torque and flux separately.

[0056] The term "switching frequency" can refer to the rate at which power electronic switches (such as transistors) in an inverter turn on and off.

[0057] The term "sampling time" can refer to the time interval between continuous measurements of current and / or updates to the corresponding control signals. The sampling time can, in some respects, be chosen to be the same as the switching cycle (the reciprocal of the switching frequency).

[0058] The term "motor winding resistance" can specify the resistance of the conductive material used in the stator and / or rotor windings. Motor winding resistance may be generalized for both the d-axis and q-axis of the stator or rotor.

[0059] The term "motor winding inductance" can refer to the inductance of the windings in the motor stator and / or rotor. The motor winding inductances for the d-axis and q-axis may differ. Therefore, in this method, L can be predetermined / calculated. d (d-axis inductance) and L q (q-axis inductance).

[0060] The term "inductance-resistance characteristics" can refer to the electrical characteristics of windings (such as stator windings), such as the inherent resistivity of the winding material and the inductance of the motor windings (e.g., the inductance within each individual winding and / or the inductance between different windings or phases).

[0061] Figure 1 A motor control system 400 is illustrated. The motor control system 400 includes a current controller 200, a frequency converter 245, and a motor 250. In some respects, the current controller 200 may be a software module within the inverter 245, while the inverter 245 and the motor 250 are hardware components well known to those skilled in the art. Figure 1 The current controller 200 illustrated is a field-oriented current controller configured to determine respective current errors for the d-axis and q-axis of the motor 250, based on the difference between a reference current and the measured current of the motor. The term "determine current error" can refer to the current controller 200 being provided with / directly receiving the current error, such as a value from another module or unit, or the current controller 200 calculating and determining the current error. The reference current can be a direct current (DC). The reference current can be a current input from a power source (e.g., a battery). The reference current can be provided as a d-axis reference current and a q-axis reference current. The measured current represents the actual current measured by appropriate means connected to the motor or inverter. The measured current can be input to the current controller or to a unit for comparison with the reference current to derive the current error. The measured current can be an AC current converted to DC by a Clark / Parker converter, such as the AC current driving the motor. The measured current can include both d-axis and q-axis currents. The d-axis reference current is compared with the measured d-axis current to determine the d-axis current error, and the q-axis reference current is compared with the measured q-axis current to determine the q-axis current error. Therefore, the d-axis and q-axis current errors are provided to the current controller. As is well known to those skilled in the art, in another exemplary current controller, the DC voltage for a motor (e.g., a DC motor) can be controlled by adjusting the DC current using PI parameters and the current error based on the described method.

[0062] In addition, Figure 1In this embodiment, the current controller 200 is configured to determine a set of PI parameters for regulating / controlling the current. The current controller may include a PI model for regulating the current using the PI parameters. Further, the current controller 200 is configured to determine the PI parameters for the d-axis and the q-axis, the PI parameters including respective proportional gain values ​​K in the d-axis and q-axis. p and integral gain value K i Furthermore, the current controller 200 is configured to control the motor using the PI parameters and the current error. The current controller is configured to provide an output for each of the d-axis and q-axis currents, respectively. The output of the current controller 200 can be provided as an input to the motor 250, applying current / voltage to the motor 250 to generate torque as required. The term "provide output" can indicate that the current controller 200 provides / transmits an output after the step of adjusting the current using the PI parameters. The output can be a parameter-based control signal. Thus, the current controller 200 can be a feedback current controller that operably controls the current of the motor 250 continuously through its output. The current controller 200 can be an FOC current controller with a feedback loop, operating by providing a PI (proportional-integral) model and the current error to the current controller 200.

[0063] Typically, the current controller 200 can operate based on the following expression to provide an output signal. :

[0064]

[0065] For control signals, such as the output voltage at time t, The current error at time t is... This represents the integral of the error from time 0 to time t. t can be the current time. It can also be derived by combining the preset feedforward voltage value with the above expression (a).

[0066] Accordingly, control signals can be provided to inverter 245 to control motor 250.

[0067] Expression (a) can be simplified to: It is well known to those skilled in the art.

[0068] thus, This can be represented as the voltage setpoint input to the inverter used to control the motor. (e.g., control signals).

[0069] The following will elaborate further. Figure 1The operating procedure of one aspect of the current control system 400 is illustrated. For example... Figure 1 As shown, the reference / desired current value of motor 250, represented by the dq value, can be provided to current controller 200 as indicated by arrow s1. The desired current data can be determined based on, for example, user input, throttle input, or vehicle drive input.

[0070] The current controller 200 can further, as indicated by arrow s1', receive measured current in the form of dq values ​​from the motor 250 and / or the inverter. The measured d-axis and q-axis currents can be obtained through Clarke / Parker transformation. Based on these, the current controller 200 can provide a control signal to the inverter (hardware) 245 using PI parameters and current error. The control signal can be a voltage value expressed as d and q values. The control signal can be adjusted before being input to the motor 250 as a control value. Therefore, the control signal can be adjusted from a rotating reference frame (i.e., with dq values) to a three-phase reference frame, for example, through a reverse Clarke / Parker transformation, such as... Figure 1 As shown in s2, this allows the control signal to be represented as the ABC current / voltage components corresponding to each phase of the three-phase motor. The advantage of configuring the current controller 200 to output the control signal with dq values ​​(including q and d values) is that it enables the current controller 200 to operate more efficiently during calculations.

[0071] In addition, such as Figure 1 As shown in s3, the control signal can be provided to the inverter 245, which can be configured to control the switches therein to operate in a certain mode, so that the motor 250 can run according to the reference input.

[0072] As shown in the figure, arrows s4 and s4' indicate that control system 400 is a feedback control system because motor 250 and / or related components can include sensor devices and other monitoring circuitry to measure the current three-phase current and the current rotor angular position of the motor. These values ​​are then provided as feedback dq values ​​to current controller 200, which can then repeat steps s1-s3 iteratively to minimize current errors within a shorter response period. The feedback model can improve the operating efficiency and robustness of the control system. Figure 1 As shown, the three-phase current can be measured as three-phase components (ABC), and then converted to a rotating reference frame before being received by the current controller 200 to obtain the d-axis and q-axis values.

[0073] The module responsible for converting dq values ​​to three-phase values, and which converts three-phase values ​​to dq values, can be called a conversion module, such as a Clark / Parker converter. Accordingly, system 400 may include a first conversion module m1, such as a reverse Clark / Parker converter module, to ensure that the motor receives current / voltage values ​​that can be used to adjust the current / voltage for each corresponding phase, and a second conversion module m2, such as a Clark / Parker converter module, to ensure that the current controller 200 receives current values ​​of dq, and includes at least one d-axis value and at least one q-axis value of the motor 250. The first conversion module m1 may also include a pulse width modulator (PWM) or any other modulation module, or the PWM may be a separate module providing output to the inverter.

[0074] Figure 1 The diagram further illustrates the connection of the current controller 200 to the inverter 245 of the motor 250. Accordingly, the motor 250 can directly receive control signals from the inverter 245. Figure 1 Inverter 245 may include other circuitry, such as diodes, transistors, and other switching / controlling elements. Accordingly, inverter 245 may be configured to convert direct current (DC) to alternating current (AC) based on control signals from current controller 200, and to supply motor 250 with AC power corresponding to the control signals for each phase. As is well known to those skilled in the art, inverter 245 may include other modules / units, such as transistors (IGBT / MOSFET), diodes, and gate drivers. Furthermore, it should be noted that system 400 may be connected to a power source, such as a battery pack (which may be directly connected to inverter 245), to provide DC voltage (volts) to motor control system 400, allowing system 400 to use the current controller 200 to control motor 250 (and inverter 245) using PI parameters.

[0075] Figure 2 A current controller 200 is illustrated according to certain aspects of this disclosure, wherein the current controller 200 is an FOC controller. The term "FOC controller" can refer to a current controller that converts (e.g., stator) current into a dq value.

[0076] Figure 2The current controller 200 may include control circuitry 210 and one or more storage devices 220. Control circuitry 210 may include, for example, one or more central processing units (CPUs), graphics processing units (GPUs) dedicated to performing calculations, and / or other processing devices. Control circuitry 210 may also include input / output interfaces (not shown), for example, for receiving data from sensor devices and outputting control signals. Storage device 220 may include any form of volatile or non-volatile computer-readable memory, including but not limited to persistent memory, solid-state memory, remotely mounted memory, magnetic media, optical media, random access memory (RAM), read-only memory (ROM), mass storage media (e.g., hard disks), removable storage media (e.g., flash drives, optical discs (CDs), or digital video disks (DVDs)), and / or any other volatile or non-volatile, non-transient device-readable and / or computer-executable memory for storing information, data, and / or instructions that may be used by each associated module 221-223. Each storage device 220 can store any suitable instructions, data, or information, including computer programs, software, application programs (including one or more logics, rules, codes, tables, etc.), and / or other instructions that can be executed and utilized by, for example, control circuitry 210. Specifically, the storage device may include a first determining module 221, a second determining module 222, and an output module 223. Storage device 220 can store any instructions and / or programs that can be executed according to the method of this disclosure. Instructions can be executed by control circuitry 210. For example, the first determining module 221 may include instructions for determining motor current error. Further, the second determining module 222 may include instructions / programs for determining PI parameters, and the output module 223 may include instructions for outputting control signals to adjust the current error. Therefore, control circuitry 210 can utilize different modules 221-223 to output control signals to adjust the current error. In some embodiments, storage device 280 can be considered integrated into the control circuitry. It should be noted that the current controller 200 (and / or one or more of the conversion modules m1, m2) may, in some respects, be a (software) module / component located within the inverter 245, i.e., within the control circuitry of the inverter 245. The inverter 245 may be inverter hardware / device, which may include a power module, a gate driver (which can control the transistor switches of the power module to output three-phase voltages), and control circuitry.

[0077] Figure 3The diagram illustrates a flowchart of a method 100 for controlling a motor. The method 100 includes step 101 determining a motor current error, the current error being based on the difference between a reference current and a measured current of the motor. Further, the method 100 includes step 102 providing the current error to a current controller of the motor. Additionally, the method 100 includes step 103 determining PI parameters of the current controller, the PI parameters including a proportional gain value K. p and integral gain value K i Furthermore, method 100 includes step 104, controlling the motor using the PI parameters and current error via the current controller.

[0078] K p The value can be determined based on a function, where K p The value depends on the motor winding resistance R, the motor winding inductance L, and the sampling parameter P. cs and tuning parameter K c .

[0079] Furthermore, K i The value can be determined based on a function, where K i The value depends on the motor winding resistance R and the sampling parameter P. cs and tuning parameter K c Preferably, K c This is a preset constant. Therefore, K c It can be a preset value that optimizes the application of all motor states.

[0080] More specifically, K p The expression can be represented as follows:

[0081]

[0082] For formula (1) Using the power series in formula (2) below, we can simplify (1):

[0083]

[0084] Choosing n=1 and n=2, we can expand the terms and obtain the following results:

[0085]

[0086]

[0087] Inserting simplification into equation (1) will produce:

[0088]

[0089]

[0090] In equation (1), K p The actual solution is compared with equations (4) and (5), and simplification can be achieved by introducing... This brings the solution closer to the real solution. This reduces the complexity of adding more power series terms and makes the solution of the equation closer to the solution described in equation (1).

[0091] Therefore, K p The values ​​on Ki can be represented as follows:

[0092]

[0093]

[0094]

[0095] G c This represents the transfer function. It should be noted that the control steps can be specified using, for example... Figure 1 The inverter 245 in the motor controls the voltage output to the motor. Method 100 can be executed iteratively and continuously.

Claims

1. A method (100) for controlling a motor, comprising: - Determine (101), motor current error, I e The current error is based on the difference between the motor's reference current and the measured current; - Provide the current error (102) to the current controller of the motor; - For this current controller, determine (103) the proportional-integral (PI) parameters, which include the proportional gain value K. p and integral gain value K i ; - The motor (104) is controlled by the current controller using the PI parameters and the current error.

2. The method (100) according to claim 1, characterized in that, The PI parameter is determined based on the inductance and resistance characteristics of the motor windings.

3. The method (100) according to any one of the preceding claims, wherein, K p The value is determined by a function, where K p The value depends on: - Motor winding resistance, R; - Motor winding inductance, L; - Sampling parameters, P cs ;and - Adjust parameter K c .

4. The method (100) according to any one of the preceding claims, wherein, K i The value is determined based on a function, where K i The value depends on: - Motor winding resistance, R; -Sampling parameters, P CS ;and - Adjust parameter K c .

5. The method (100) according to any one of claims 4 and 5, wherein, K c This is a preset constant.

6. The method (100) according to claim 4, characterized in that, The K p The value is determined based on a function:

7. The method (100) according to claim 5, characterized in that, The K i The value is determined based on a function: .

8. The method (100) according to any one of claims 4-7, characterized in that, The sampling parameter P cs It is derived based on the sampling time or switching frequency of the inverter of the motor.

9. The method (100) according to claim 8, characterized in that, The sampling parameters are based on the switching frequency. It is concluded that the switching frequency is the crossover angular frequency. Preferably, the crossover angular frequency , denoted as a predetermined fraction of the switching frequency of the inverter, wherein the fraction is based on the assumption that the maximum crossover frequency is . At switching frequency About 1 / 10 of the way.

10. The method (100) according to any one of the preceding claims, characterized in that, The motor is controlled by the current controller using PI parameters and current error, including determining the voltage setpoint U by the current controller. set It is based on the expression: , Among them, U set For the voltage setpoint, I e Let be the current error, and s be a Laplace complex variable.

11. The method (100) according to any one of the preceding claims, characterized in that, The current error refers to the d-axis current error or q-axis current error of the motor.

12. A current controller (200) for a motor, said current controller (200) being configured to: - Determine the current error of the motor, which is based on the difference between the reference current and the measured current of the motor; - Determine the PI parameters, including the proportional gain value K. p and integral gain value K i , - The current controller utilizes the PI parameters and current error to provide an output for controlling the motor.

13. The current controller (200) according to claim 12 is a field-oriented control current controller, wherein, The current error is either the d-axis current error or the q-axis current error.

14. The current controller (200) according to claim 12 or 13, characterized in that, The PI parameter is determined based on the inductance and resistance characteristics of the motor windings.

15. A motor control system (400) comprising the current controller (200) as described in claims 12-14.

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