Motor sampling current bias error compensation method, motor control method and system

Abstract

The application relates to the motor technical field and discloses a motor sampling current bias error compensation method, a motor control method and a system. The sampling current bias error compensation method comprises the following steps: a control system of a permanent magnet synchronous motor is configured as an open loop state in advance; a first current bias error of the permanent magnet synchronous motor is obtained, wherein the first current bias error at least comprises current bias errors of phase A and phase C; current measurement values of the permanent magnet synchronous motor are obtained under a closed loop state of the control system; the current measurement values of the permanent magnet synchronous motor are compensated by using the first current bias error, so that compensated current measurement values of the permanent magnet synchronous motor are obtained; and the compensated current measurement values of the permanent magnet synchronous motor are compensated by using a pre-designed PI type regulator. α axis and β axis α axis and β axis α axis and β axis α axis and β axis The application can realize high-precision compensation of sampling current bias errors of the permanent magnet synchronous motor at a low cost, and further improve the control precision of the permanent magnet synchronous motor.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of motor control, and in particular to a motor sampling current bias error compensation method, a motor control method and a system. BACKGROUND

[0002] Steer-by-wire (SBW) system is an advanced steering technology. SBW system completely cancels the mechanical coupling between the steering wheel and the steering wheel in the traditional steering system, and completely completes the closed-loop control of "human-machine interface-domain controller-steering execution motor" through electrical signals, thereby giving unprecedented freedom to vehicle layout, driving style customization, passive safety and functional safety.

[0003] SBW system has the following advantages: (1) higher design freedom: the steering wheel and steering execution mechanism can be flexibly arranged to adapt to different vehicle requirements (such as autonomous driving vehicles, skateboard chassis, etc.); (2) better driving experience: dynamically adjusting the steering ratio and road feel feedback to improve the comfort of operation; (3) enhanced safety: supporting redundant design to avoid steering failure caused by mechanical failure.

[0004] However, the core of SBW system relies on high-precision motor control, and the current sampling precision directly affects the torque output of the steering motor and the stability of the system. Current bias error compensation is a necessary link in permanent magnet synchronous motor (PMSM) control, and its main purpose is to reduce the torque fluctuation of the motor within an electrical angle period and thus reduce the speed fluctuation of the motor in motor control, thereby improving the smoothness of control. For example, in a new energy steer-by-wire system, the granular feeling of the driver when slowly turning the steering wheel is reduced. In a numerical control machine tool, the servo system rotates more smoothly and the stroke control is more precise.

[0005] In a steer-by-wire system, the motor current sampling link directly determines the torque control accuracy, the silence level and the road feel transparency, and is one of the key control factors of the steer-by-wire system. For example, the motor sampling current error appears as a certain direct current bias in the d-q axis current in the low-speed, light-load and steady-state working conditions of the steering motor, thereby introducing a bias torque. After amplification by the reducer, a certain additional force is generated at the steering wheel end, causing problems such as zero drift, stickiness and high-frequency jitter. It is usually necessary to compensate for the error of the motor sampling current to ensure the control accuracy of the motor.

[0006] The prior art has carried out extensive research on the compensation design of the sampling current of the motor. For example, the Chinese patent application with publication number CN114268261A inputs the q-axis feedback current into a preset DC bias error extraction module, obtains a DC bias error, and compensates the output signal of the resolver using the DC bias error. This technical solution only considers the DC bias error and cannot compensate for the proportional error. The Chinese patent application with publication number CN118889913A establishes a model between the scaling error and the reference current on the basis of the Chinese patent application with publication number CN114268261A, and compensates for the bias error and the proportional error in the closed-loop control through the model.

[0007] The error compensation method for the sampling current of the steer-by-wire motor also generally follows the above patent application. In the closed-loop control, a low-pass filter or a lead-lag compensator is used to compensate for the current measurement error to minimize the fluctuation of the hand torque on the steering wheel caused by the fluctuation of the motor output current, which is perceived by the user. Therefore, the existing current measurement error compensation method cannot solve the problem of the sampling current bias error of the motor from the root cause.

[0008] The disclosure of the above background art is only used to assist in understanding the inventive concept and technical solutions of the present application, and does not necessarily belong to the prior art of the present application, nor does it necessarily provide technical teaching. In the absence of explicit evidence that the above-mentioned content has been disclosed before the filing date of the present application, the above-mentioned background art should not be used to evaluate the novelty and inventiveness of the present application. SUMMARY

[0009] The purpose of the present application is to provide a motor sampling current bias error compensation method, a motor control method and a system. The present application can eliminate the inherent sampling current bias error of the system, achieve high-precision compensation of the sampling current bias error of the permanent magnet synchronous motor at a lower cost, and further improve the control accuracy of the permanent magnet synchronous motor.

[0010] To achieve the above-mentioned purpose, the technical solutions adopted by the present application are as follows:

[0011] A motor sampling current bias error compensation method, comprising the following steps:

[0012] The control system of the permanent magnet synchronous motor (hereinafter referred to as the motor) is configured to be in an open-loop state in advance, and a first current bias error of the permanent magnet synchronous motor is obtained, wherein the first current bias error at least includes the current bias error of phase A i Aoffset and the current bias error of phase C i Coffset ;

[0013] In the closed-loop state of the control system, the current measurement values of the permanent magnet synchronous motor are obtained α and the current measurement values of the β axis are compensated by the first current bias error to obtain the compensated current measurement values of the α axis β ; α i αmeasure and β the current measurement values of the i βmeasure ;

[0014] the current measurement values of the α axis i αmeasure and β the current measurement values of the i βmeasure are error-compensated by a pre-designed PI-type regulator.

[0015] Further, any one of the technical solutions or a combination of the multiple technical solutions described above, the current measurement values of the α axis i αmeasure and β the current measurement values of the i βmeasure are error-compensated by a pre-designed PI-type regulator in the following manner:

[0016] ;

[0017] wherein, i αmeasure is the current measurement value of the α axis, i βmeasure is the current measurement value of the β axis, is the estimated current value of the α axis, is the estimated current value of the β axis, is the estimated current bias error value of the α axis, is the estimated current bias error value of the β axis, is the estimated resistance of the motor, K p is a proportional gain, K i is an integral gain, S is a complex variable.

[0018] Further, any one of the technical solutions or a combination of the multiple technical solutions described above,​ and The relationship between them is expressed as follows:

[0019]

[0020] wherein, is α the voltage estimation value of the axis, is β the voltage estimation value of the axis, is α the feedback flux linkage value of the axis, is β the feedback flux linkage value of the axis, is the estimated inductance of the motor, is the estimated resistance of the motor.

[0021] Further, any one of the above technical solutions or a combination of multiple technical solutions, the proportional gain K p and the integral gain K i are selected as follows:

[0022] ;

[0023] wherein, is the estimated inductance of the motor, is the estimated resistance of the motor, ωc is the bandwidth of the PI type regulator.

[0024] Further, any one of the above technical solutions or a combination of multiple technical solutions, in the open loop state of the control system, based on double resistance sampling, the first current bias error of the permanent magnet synchronous motor is obtained by the following formula:

[0025] ;

[0026] wherein, i Ameasure is the A-phase current measurement value in the open loop state, i Cmeasure is the C-phase current measurement value in the open loop state, i Aoffset is the current bias error of the A-phase in the open loop state, i Coffset is the current bias error of the C-phase in the open loop state.

[0027] Further, any one of the above technical solutions or a combination of multiple technical solutions, in the closed loop state of the control system, based on double resistance sampling, the A-phase and C-phase current measurement values are compensated to obtain the compensated A-phase and C-phase current measurement values iAmeasure and i Cmeasure : i Ameasure = i A_measure - i Aoffset , i Ameasure = i A_measure - i Aoffset wherein, i A_measure is the current measurement value of phase A before compensation, i C_measure is the current measurement value of phase C before compensation;

[0028] determining the current measurement value of phase A after compensation according to the current measurement value of phase A after compensation i Ameasure and i Cmeasure determining the current measurement value of phase C after compensation according to the current measurement value of phase C after compensation α αmeasure and i βmeasure . β i

[0029] Further, any one of the technical solutions or the combination of the multiple technical solutions described above further includes the following steps:

[0030] pre-acquiring and storing the first current bias error;

[0031] In the closed-loop control process, the first current bias error is acquired in real time, and the current measurement value is compensated by using the first current bias error to obtain the current measurement value after compensation.

[0032] Further, any one of the technical solutions or the combination of the multiple technical solutions described above, acquiring the first current bias error of the permanent magnet synchronous motor, includes the following steps:

[0033] configuring the control system of the permanent magnet synchronous motor to be in an open-loop state, and collecting the current measurement value of the permanent magnet synchronous motor;

[0034] filtering the current measurement value collected in real time to obtain a current filtered value;

[0035] taking the average value of the current filtered value in a preset time period after the control system is configured to be in the open-loop state as the first current bias error.

[0036] ​​Further, any one of the above technical solutions or a combination of multiple technical solutions, the current of the control system adopts double-resistance sampling based on the control system of the permanent magnet synchronous motor is configured to an open loop state, and then A-phase current measurement values and C-phase current measurement values are collected;

[0037] The A-phase current measurement values and the C-phase current measurement values collected in real time are subjected to filtering processing to obtain current filtered values of the A-phase and current filtered values of the C-phase;

[0038] The current filtered values of the A-phase in a preset time period after the control system is configured to the open loop state are taken as current bias errors of the A-phase i Aoffset ;

[0039] The current filtered values of the C-phase in a preset time period after the control system is configured to the open loop state are taken as current bias errors of the C-phase i Coffset .

[0040] Further, any one of the above technical solutions or a combination of multiple technical solutions, the permanent magnet synchronous motor is configured to a steer-by-wire motor; and / or,

[0041] The preset time period is 1.5s to 2s after the control system is configured to the open loop state.

[0042] According to another aspect of the present application, the present application provides a control method of a permanent magnet synchronous motor, which controls the working state of the permanent magnet synchronous motor based on the motor sampling current bias error compensation method according to any one of the above technical solutions or a combination of multiple technical solutions.

[0043] According to another aspect of the present application, the present application provides a permanent magnet synchronous motor control system, which controls the working state of the permanent magnet synchronous motor based on the control method of the permanent magnet synchronous motor according to any one of the above technical solutions or a combination of multiple technical solutions.

[0044] The technical solutions provided by the present application have the following beneficial effects:

[0045] a. The present application obtains the first current bias error of the motor by rough calibration of the control system of the permanent magnet synchronous motor in the open loop state. In the closed loop control of the control system, the first current bias error is used to compensate the current measurement values of the motor sampled in real time, and then the PI type regulator designed in advance is used to further compensate the compensated current measurement values, thereby improving the compensation accuracy of the sampling current bias error of the motor and improving the control accuracy of the motor;

[0046] b. The motor sampling current bias error compensation method provided by the application adopts a PI type regulator to regulate the sampling current bias error of the closed-loop control of the permanent magnet synchronous motor, the PI type regulator does not occupy hardware resources, has low cost, and has strong adjustability and is convenient for platform transplantation;

[0047] c. The motor sampling current bias error compensation method provided by the application is based on two-phase resistance sampling, can not only realize high-precision compensation of the sampling current bias error of the permanent magnet synchronous motor at low cost, and is especially suitable for improving the control performance of the steer-by-wire system and the steering system of special vehicles such as unmanned vehicles, reducing motor noise and improving the road feel feedback of the driver;

[0048] d. The application can improve the precision of determining the fixed bias error of the sampling current of the system by determining the first current bias error according to the current filter value in the preset time period after the control system is set to an open-loop state. BRIEF DESCRIPTION OF DRAWINGS

[0049] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0050] Figure 1 The module principle diagram of the control system of the permanent magnet synchronous motor provided for an exemplary embodiment of the present application;

[0051] Figure 2 The flowchart of the motor sampling current bias error compensation method provided for an exemplary embodiment of the present application;

[0052] Figure 3 The principle diagram of the PI filter type current measurement bias error compensation controller provided for an exemplary embodiment of the present application;

[0053] Figure 4 The sampling current bias error compensation flowchart for the open-loop mode of the steer-by-wire motor provided for an exemplary embodiment of the present application;

[0054] Figure 5 The simulink model schematic diagram of the PI filter type current bias error compensation regulator provided for an exemplary embodiment of the present application;

[0055] Figure 6 The A-phase current comparison diagram of the steer-by-wire motor before and after compensation provided for an exemplary embodiment of the present application;

[0056] Figure 7 A comparison chart of B-phase current of the steer-by-wire motor before and after compensation is provided for an exemplary embodiment of the present application;

[0057] Figure 8 A comparison chart of C-phase current of the steer-by-wire motor before and after compensation is provided for an exemplary embodiment of the present application;

[0058] Figure 9 A schematic diagram of the electrical angle and torque ripple of the steer-by-wire motor before compensation is provided for an exemplary embodiment of the present application;

[0059] Figure 10 A schematic diagram of the electrical angle and torque ripple of the steer-by-wire motor after compensation is provided for an exemplary embodiment of the present application. DETAILED DESCRIPTION

[0060] In order to make the technical personnel in the art better understand the present application scheme, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should be within the scope of protection of the present application.

[0061] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, device, product or equipment including a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or equipment.

[0062] As shown in Figure 1 In FOC control, the outer ring is the angle ring / speed ring, and the innermost ring is the current ring. Among them, the current ring is the most important part of the whole closed-loop control, which affects the stability and responsiveness of the whole motor system. The performance of the current loop is not only related to the algorithm used, but also closely related to the basic current sampling accuracy and angle sampling accuracy. With the development of technology, some application scenarios of permanent magnet synchronous motor PMSM use positionless control. In this use scenario, the accuracy of current sampling is crucial.

[0063] The current sampling of the mainstream motor is divided into high-end sampling and low-end sampling. The high-end sampling is to place the current sensor directly on the three-phase bridge arm, and the software does not need to reconstruct the current, but directly collects the phase current. The advantage of high-end sampling is that the method is simple, but the cost is high.

[0064] Low-end sampling is the preferred solution for most motor control, which is generally divided into single-resistor sampling, double-resistor sampling and three-resistor sampling. Single-resistor sampling, also known as bus current sampling, is easily affected by the switch state of the inverter, and in some duty cycle states, the effective value cannot be sampled, so at least 2 times of sampling in a cycle is required for current reconstruction. The advantage of low-end sampling is low cost, but the algorithm implementation is complex.

[0065] The principle of double-resistor sampling and three-resistor sampling is the same, which is to place a sampling resistor on the lower bridge arm and sample at the moment when the lower tube is turned on. And double-resistor sampling has lower cost and simpler algorithm implementation than three-resistor sampling, and double-resistor sampling follows the principle that the sum of three-phase currents is 0.

[0066] Taking double-resistor sampling as an example, in the ADC hardware amplifier device with an output voltage range of 0~5v, there is a zero current bias error phenomenon. Under normal circumstances, the output voltage of 2.5V corresponds to 0 current, greater than 2.5V corresponds to positive phase current, and less than 2.5V corresponds to negative phase current. The output of the ADC hardware amplifier device corresponds to 2 12 bit ADC value, i.e. 0~4096 bit numbers, 2048 is the 0 current value, but due to hardware layout, thermal drift, etc. Zero current cannot be ideal 2048, there is a bias error, which causes the converted phase current to not fluctuate around 0 but have an initial value, resulting in d / q current always having a first harmonic. If you try to suppress it in the current loop with harmonic compensation, only the feedback current will disappear, but the actual sampling will always exist, affecting the accuracy of motor control and the performance of the motor.

[0067] Based on the above shortcomings, the present application provides a motor sampling current bias error compensation method, as shown in Figure 1 and Figure 2 , the method comprises the following steps:

[0068] Pre-configuring the control system of the permanent magnet synchronous motor to be in an open loop state, obtaining the first current bias error of the permanent magnet synchronous motor, the first current bias error at least including the current bias error of phase A i Aoffset and the current bias error of phase C i Coffset ;

[0069] In the closed loop state of the control system, obtaining the α axis andβ the current measurement value of the axis, and the first current bias error is used to compensate the current measurement value of the axis to obtain a compensated current measurement value of the axis α the current measurement value of the axis, and the first current bias error is used to compensate the current measurement value of the axis to obtain a compensated current measurement value of the axis β the current measurement value of the axis, and the first current bias error is used to compensate the current measurement value of the axis to obtain a compensated current measurement value of the axis α the current measurement value of the axis, and the first current bias error is used to compensate the current measurement value of the axis to obtain a compensated current measurement value of the axis i αmeasure and β the current measurement value of the axis, and the first current bias error is used to compensate the current measurement value of the axis to obtain a compensated current measurement value of the axis i βmeasure ;

[0070] the current measurement value of the axis, and the first current bias error is used to compensate the current measurement value of the axis to obtain a compensated current measurement value of the axis α the current measurement value of the axis, and the first current bias error is used to compensate the current measurement value of the axis to obtain a compensated current measurement value of the axis i αmeasure and β the current measurement value of the axis, and the first current bias error is used to compensate the current measurement value of the axis to obtain a compensated current measurement value of the axis i βmeasure perform error compensation.

[0071] In this embodiment, first, rough calibration is performed in the open-loop state of the PMSM control system, and the A, C phase current measurement values of the motor control system i Ameasure , i Cmeasure , the A, C phase current bias errors i Aoffset , i Coffset , and the A, C phase current actual values i Aactual , i Cactual satisfy the following formula: .

[0072] The A / C two-phase current measurement values i Ameasure , i Cmeasure , in the case where the command D / Q voltage is 0, i Aactual and i Cactual are 0, but the current bias errors i Aoffset , i Coffset actually exist, so the first current bias error in the open-loop state can be obtained based on the current measurement values, as shown in the following formula.

[0073] ;

[0074] wherein, i Ameasure is the A phase current measurement value in the open-loop state, i CmeasureThe current measurement value of phase C in open loop state, i Aoffset The current bias error of phase A in open loop state, i Coffset The current bias error of phase C in open loop state.

[0075] In one embodiment of the present application, the current measurement value of the system in open loop state i Ameasure , i Cmeasure is filtered to obtain a smooth current value. The current value is assigned as a storage value to i Aoffset , i Coffset to remove the current bias error introduced by the system sampling. The first current bias error obtained in open loop state is a fixed value, which can be used to compensate the sampling error fixedly existing in the system, and cannot compensate the error in each speed range.

[0076] In the present embodiment, further in the closed loop control of the output current of the motor, the compensation algorithm is used to compensate the α / β axis current in the rotating coordinate system to make the three-phase current smooth, and the closed loop control principle of the PMSM control system is as follows.

[0077] If there is a current measurement deviation, there will be an offset value in the obtained A / C current, which is converted into α / β axis current measurement value, and the conversion formula of the three-phase current to α axis, β axis current is as follows:

[0078]

[0079] wherein, i α is the α axis current, i β is the β axis current, i A , i B , i C is the three-phase current, i A + i B + i C = 0.

[0080] In the closed-loop control, based on the first current bias error obtained in the open-loop process i Aoffset 、 i Coffset In the closed-loop state of the motor control system, based on double-resistance sampling, the A-phase and C-phase current measurement values are compensated by the following formula to obtain the compensated A-phase and C-phase current measurement values i Ameasure and i Cmeasure : i Ameasure = i A_measure - i Aoffset , i Ameasure = i A_measure - i Aoffset , wherein i A_measure is the A-phase current measurement value before compensation, i C_measure is the C-phase current measurement value before compensation, that is, the A-phase and C-phase current measurement values of the permanent magnet synchronous motor collected in real time in the closed-loop control process. According to the compensated A-phase and C-phase current measurement values i Ameasure and i Cmeasure , the compensated α axial current measurement value i αmeasure and β axial current measurement value i βmeasure are determined. The existing current bias error compensation method of the motor is usually to directly compensate the collected current measurement value. The present application compensates the real-time collected current measurement value first, and further compensates the compensated current measurement value, which not only eliminates the inherent current sampling error of the system, but also improves the accuracy of the subsequent closed-loop compensation. It should be noted that the measurement values in the closed-loop control refer to the measurement values after eliminating the inherent sampling error of the system.

[0081] Based on the above conversion formula of the three-phase current to the α axial current, β axial current, the expression of the α axial current and the β axial current obtained by the compensated A-phase and C-phase current measurement values is as follows:

[0082] ;

[0083] wherein,i αmeasure 、 i βmeasure is α the current measurement value of the axis and β the current measurement value of the axis, i Ameasure 、 i Bmeasure and i Cmeasure is the compensated current measurement value of the A, B, C phase.

[0084] Further, the following relationship exists between the compensated current measurement value and the actual current value of the A phase and the C phase in the closed loop state:

[0085] ;

[0086] wherein, i αmeasure 、 i βmeasure is α the current measurement value of the axis and β the current measurement value of the axis (obtained based on the compensated current measurement value of the A, C phase), i α_actual and i β_actual is α the actual current value of the axis and β the actual current value of the axis, i αoffset and i βoffset is α the current bias error value of the axis and β the current bias error value of the axis, i A_offset is the A phase current bias error in the closed loop state, i C_offset is the A phase current bias error in the closed loop state, i A_offset and i C_offset is configured as the second current bias error.

[0087] The AC quantity is converted to the d / q axis current quantity, and the conversion relationship is as follows:

[0088]

[0089] wherein, i dmeasure 、 i qmeasure is d the current measurement value of the axis and q the current measurement value of the axis, i d_actual andi q_actual is d the actual current value of the shaft, q i d_offset and i q_offset is d the current offset error value of the shaft, q k is d the current offset error amplitude value of the shaft, q r is the current offset error phase value, and ω is the electrical angular velocity of the permanent magnet synchronous motor, t denotes time. It can be clearly seen that there is always a first-order harmonic current in an electrical angle on the current.

[0090] In the current control of the automobile steering motor, for the first-order harmonic current caused by the sampling offset error, the prior art is to use multiple zero-current acquisition for filtering. This compensation method has a high requirement for chip resources, and there is still a certain fluctuation in the actual closed-loop control, which can still be perceived by the driver. In view of this deficiency, the present application proposes to obtain the fixed sampling current offset error of the control system, i.e. the first current offset error, in advance in the open-loop state; in the closed-loop control, the first current offset error is used to compensate the real-time sampled current value to obtain the compensated current measurement value. The compensated current measurement value is further compensated.

[0091] As Figure 3 shown, the present application designs a PI filter type current measurement offset error compensation controller (hereinafter referred to as PI type regulator) to reduce the torque ripple of the permanent magnet synchronous motor.

[0092] ;

[0093] wherein, i αmeasure is α the current measurement value of the shaft, i βmeasure is β the current measurement value of the shaft, is α the estimated current value of the shaft, is β the estimated current value of the shaft, is α the estimated current offset error value of the shaft, is β the estimated current offset error value of the shaft, K p is a proportional gain, K i ​​​is an integral gain, is an estimated resistance of the motor, S is a complex variable.

[0094] and there is the following relationship:

[0095]

[0096] wherein, is α an estimated voltage of the shaft, is β an estimated voltage of the shaft, is α an estimated current of the shaft, is β an estimated current of the shaft, is α a feedback flux linkage value of the shaft, is β a feedback flux linkage value of the shaft, is an estimated inductance of the motor, is an estimated resistance of the motor, S is a complex variable.

[0097] a proportional gain K p and an integral gain K i are selected as follows:

[0098] ;

[0099] wherein, is an estimated inductance of the motor, is an estimated resistance of the motor, ωc is a bandwidth of the PI type regulator, which can be calibrated according to an actual system.

[0100] Based on the above open-loop coarse calibration, the closed-loop first compensation current measurement value, and then the PI filter type current bias error compensation regulator is used to compensate the sampling current bias error of the permanent magnet synchronous motor, which can better eliminate the sampling current bias error of the motor and improve the control precision of the permanent magnet synchronous motor. In addition, the PI type regulator is used for the closed-loop control of the permanent magnet synchronous motor, compared with the commonly used PID controller in the prior art, the PI type regulator proposed in the application does not occupy hardware resources, has low cost, and has strong adjustability, and is also convenient for platform transplantation.

[0101] The core goal of the method is to improve the accuracy of current sampling. The application of the method to the sampling current bias error compensation of the steer-by-wire motor can realize the control performance optimization of the electric power steering (EPS), steer-by-wire (SBW) system and special vehicle steering system such as unmanned vehicle, reduce the motor noise and improve the road feel feedback of the driver at a low cost.

[0102] In addition, the method proposed in the application is not only suitable for the traditional automobile industry, but also has wide application potential in the fields of unmanned driving, engineering machinery and special equipment, and the core value lies in improving the safety, comfort and reliability of the steering system through high-precision current control. It can also be applied to the control system of the rudder of unmanned aerial vehicles or electric aircraft, the field of high-precision servo motor driving, the field of robot joint control, etc.

[0103] In one embodiment of the application, a control method of a permanent magnet synchronous motor is provided, which controls the working state of the permanent magnet synchronous motor based on the motor sampling current bias error compensation method according to any one of the above embodiments.

[0104] The control system of the permanent magnet synchronous motor is configured to an open loop state in advance, and the current measurement value of the permanent magnet synchronous motor is collected. The real-time collected current measurement value is filtered to obtain a current filtered value. Preferably, the average value of the current filtered value in a preset time period after the control system is configured to the open loop state is taken as the first current bias error. The preset time period is preferably 1.5s to 2s after the control system is configured to the open loop state.

[0105] In the closed loop control process, the first current bias error is obtained in real time, and the current measurement value is compensated by using the first current bias error to obtain a compensated current measurement value. In the closed loop control process, the compensated current measurement value is further compensated based on a PI type regulator, and is applied to the closed loop control of the motor.

[0106] Taking a steer-by-wire motor as an example, first, the host computer sends a current error compensation command 1 to the ECU controller through a bus such as can / ethercat, and the ECU controller switches the control system of the steer-by-wire motor to an open loop mode, that is, only SVPWM space vector modulation is performed, the commands of Vd and Vq are 0, and the angle is the actual collection of the sensor.

[0107] The collected three-phase current ADC value is filtered to obtain a relatively smooth direct current. It is written into the Dflash of the chip, and then powered off. Then the ECU controller is powered on, and the bias current ADC value stored in the NVM is brought into the actual closed loop control. In one specific embodiment, see Figure 4, first send 1003, 2701, 2702, enable flag, start timing, at the same time the motor control system switches to open loop mode; start filtering three-phase current at 80ms, actual offset value = 2048-filtered ADC value; in order to smooth the data, take the data with small fluctuations in the middle, write the offset value of three-phase current into the chip Dflash area within 1.5s and 2s, and the offset ADC value of three-phase current needs to be limited (±30), then the controller is powered off and stored, and the enable position is 0.

[0108] The control system of the steer-by-wire motor is switched to a closed loop mode, and a PI filter type current bias error compensation regulator is added in the calculation of the three-phase current to D / Q axis current, and a simulink model is built as shown in Figure 5 .

[0109] The input of the simulink model is the d / q axis command voltage value, the motor electrical angle, the motor electrical angular velocity, the alpha / beta axis current, and the proportional gain K p , the integral gain K i , and the verification is performed. Referring to Figure 6 to Figure 8 , the three-phase current of the steer-by-wire motor before and after compensation is reduced from about ±1A to about 0.2A, which verifies that the design is feasible.

[0110] Referring to Figure 9 and Figure 10 , Figure 9 and Figure 10 , the fine lines in Figure 9 and Figure 10 represent the motor electrical angle, Figure 9 and Figure 10 , and the thick lines in Figure 9 and Figure 10 represent the current fluctuation of the torque ripple. As can be seen from the comparison of Figure 9 and Figure 10 , the motor electrical angle and torque ripple of the steer-by-wire motor after compensation are obviously improved compared with those before compensation, and the jitter of the motor electrical angle and torque ripple is significantly improved, so that the control of the motor is more stable and smooth.

[0111] In an embodiment of the present application, a permanent magnet synchronous motor control system is provided, which controls the working state of the permanent magnet synchronous motor based on the control method of the permanent magnet synchronous motor as described above.

[0112] It should be noted that the control method of the permanent magnet synchronous motor, the permanent magnet synchronous motor control system embodiment and the motor sampling current bias error compensation method embodiment belong to the same inventive concept, and the entire contents of the motor sampling current bias error compensation method embodiment are incorporated into the control method of the permanent magnet synchronous motor and the permanent magnet synchronous motor control system embodiment by reference.

[0113] It is to be noted that, as used in this document, the term "indicia" is intended to encompass any type of data, information, or other content, whether in the form of text, graphics, images, video, audio, or otherwise. It is to be further noted that, as used in this document, the terms "coupled" and "connected," along with derivatives thereof, can be used to mean one or more of the following: in electrical communication with; physically contacting with; in long-distance communication with; and / or not in direct contact with. It is to be further noted that, as used in this document, the terms "include" and "comprise," along with derivatives thereof, can be used to indicate inclusion of one or more elements or steps; these terms are not intended to, nor do they, imply that any or all functionality can be included with any or all elements or steps; and / or any such elements or steps are each independently repeatable both logically and temporally. In addition, the term "exemplary" is intended to refer to a non-limiting example, embodiment, or aspect. Moreover, the term "in response to" is intended to mean that a particular action is performed in response to one or more events or conditions, but not necessarily directly or immediately in response to the one or more events or conditions.

[0114] The foregoing is merely illustrative of the principles of this application and various modifications can be made by those skilled in the art, without departing from the scope of the application. Accordingly, the above description is not intended to limit the scope of the application.

Claims

1. A method for motor sampling current bias error compensation, characterized in that, The method comprises the following steps: The control system of the permanent magnet synchronous motor is configured as an open loop state in advance, and a first current bias error of the permanent magnet synchronous motor is obtained, the first current bias error at least including current bias errors of phase A, phase B and phase C i Aoffset and phase C i Coffset ; In a closed loop state of the control system, the current measurement values of the permanent magnet synchronous motor are obtained α and the first current bias error is used to compensate the current measurement values of the β and the first current bias error is used to compensate the current measurement values of the α and the first current bias error is used to compensate the current measurement values of the β and the first current bias error is used to compensate the current measurement values of the α and the first current bias error is used to compensate the current measurement values of the i αmeasure and the first current bias error is used to compensate the current measurement values of the β and the first current bias error is used to compensate the current measurement values of the i βmeasure ; The current measurement values of the axes are used to control the current of the axes by means of a pre-designed PI-type regulator α The current measurement values of the axes are used to control the current of the axes by means of a pre-designed PI-type regulator i αmeasure The current measurement values of the axes are used to control the current of the axes by means of a pre-designed PI-type regulator β The current measurement values of the axes are used to control the current of the axes by means of a pre-designed PI-type regulator i βmeasure The current measurement values of the The pre-designed PI type regulator is utilized in the following way to α current measurement of the shaft i αmeasure and β current measurement of the shaft i βmeasure error compensation is performed: ； wherein i αmeasure is α a current measurement of the shaft, i βmeasure is β a current measurement of the shaft, is α an estimated current value of the shaft, is β an estimated current value of the shaft, is α an estimated current bias error value of the shaft, is β an estimated current bias error value of the shaft, is an estimated resistance of the motor, K p is a proportional gain, K i is an integral gain, S is a complex variable; proportional gain K p integral gain K i are chosen as follows: ; where, Lestis an estimated inductance of the motor, Restis an estimated resistance of the motor, ωc Bwis a bandwidth of the PI-type regulator.

2. The motor sampling current bias error compensation method of claim 1, wherein, and The relationship between the variables A, B, and C is expressed as follows: ； wherein is α a voltage estimate of the axis, is β a voltage estimate of the axis, is α a feedback flux linkage value of the axis, is β a feedback flux linkage value of the axis, is an estimated inductance of the motor, is an estimated resistance of the motor.

3. The motor sampling current bias error compensation method of claim 1, wherein, In the open loop state of the control system, the first current bias error of the permanent magnet synchronous motor is obtained based on double resistance sampling through the following formula: ； wherein, i Ameasure Ia is a measured value of the A-phase current in the open-loop state, i Cmeasure Ic is a measured value of the C-phase current in the open-loop state, i Aoffset Ea is a current bias error of the A-phase in the open-loop state, i Coffset Ec is a current bias error of the C-phase in the open-loop state.

4. The motor sampling current bias error compensation method of claim 3, wherein, In the closed-loop state of the control system, based on double-resistance sampling, the A-phase and C-phase current measurement values are compensated by the following formula to obtain compensated A-phase and C-phase current measurement values i Ameasure and i Cmeasure : i Ameasure = i A_measure - i Aoffset , i Ameasure = i A_measure - i Aoffset wherein, i A_measure is the current measurement value of the A phase before compensation, i C_measure is the current measurement value of the C phase before compensation; According to the compensated A, C phase current measurement values i Ameasure and i Cmeasure determining the compensated α current measurement values of the axes i αmeasure and β current measurement values of the axes i βmeasure .

5. The motor sampling current bias error compensation method of claim 1, wherein, The method further comprises the following steps: The first current bias error is obtained and stored in advance; In the closed loop control process, the first current bias error is obtained in real time, and the current measurement value is compensated by using the first current bias error to obtain a compensated current measurement value.

6. The motor sampling current bias error compensation method of claim 1, wherein, The first current bias error of the permanent magnet synchronous motor is obtained, comprising the following steps: The control system of the permanent magnet synchronous motor is configured to be in an open loop state, and a current measurement value of the permanent magnet synchronous motor is collected; The current measurement value is filtered to obtain a current filtered value; The average value of the current filtered value in a preset time period after the control system is configured to be in the open loop state is taken as the first current bias error.

7. The motor sampling current bias error compensation method of claim 6, wherein, The current of the control system is sampled based on double resistance, and the A-phase current measurement value and the C-phase current measurement value are collected after the control system of the permanent magnet synchronous motor is configured to be in the open loop state; The A-phase current measurement value and the C-phase current measurement value collected in real time are filtered to obtain the A-phase current filtered value and the C-phase current filtered value; the control system is configured to filter the current of the A phase in a preset time period after the control system is configured in the open loop state as the current bias error of the A phase i Aoffset ; The control system is configured to filter the current of the C phase in a preset time period after the control system is configured in the open loop state as the current bias error of the C phase i Coffset .

8. The motor sampling current bias error compensation method of claim 6, wherein, The permanent magnet synchronous motor is configured as a steer-by-wire motor; and / or, The preset time period is 1.5s to 2s after the control system is configured to be in the open loop state.

9. A control method of a permanent magnet synchronous motor, characterized by, The working state of the permanent magnet synchronous motor is controlled based on the motor sampling current bias error compensation method according to any one of claims 1-8.

10. A permanent magnet synchronous motor control system, characterized by, The working state of the permanent magnet synchronous motor is controlled based on the control method of the permanent magnet synchronous motor according to claim 9.

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