Motor parameter on-line observation and control device, motor controller and electric drive system

Abstract

The invention relates to an on-line observation and control device for motor parameters. The on-line observation and control device comprises an input module; the controller is used for outputting corresponding control voltage to the motor according to the dq-axis current control value provided by the input module; the first acquisition module is used for acquiring the motor rotating speed; the second acquisition module is used for acquiring phase current; the current conversion module is used for converting the phase current acquired by the second acquisition module into a dq-axis current actual value of the motor, and the controller is configured to adjust a control voltage output to the motor based on the dq-axis current actual value; the lookup table is used for determining dq-axis inductance according to the dq-axis current control value; the observer is used for estimating at least one working parameter of the motor according to the rotating speed of the motor, the dq-axis inductance and the actual dq-axis current value; and the output module is used for outputting an observation result of the observer. The invention also relates to a motor controller comprising the device and an electric drive system comprising the motor controller.

Description

Technical Field

[0001] The present invention relates to the field of motor control, and more specifically, to an online observation and control device for motor parameters, including a motor controller of the device, and an electric drive system including the motor controller. Background Art

[0002] Permanent magnet synchronous motor (PMSM) is widely used in vehicle (especially electric vehicle) electric drive system due to its advantages of high efficiency, high power density, fast response speed and wide speed regulation range. The rotor flux of permanent magnet synchronous motor depends on the magnetic material of permanent magnet, and the performance of magnetic material has a great influence on the performance of vehicle electric drive system.

[0003] When a permanent magnet synchronous motor runs under high temperature conditions for a long time, the rotor flux of the motor will decrease or even demagnetize. Rotor demagnetization will lead to a decrease in the motor output torque, posing a threat to the driving safety of the vehicle. Therefore, in the process of controlling the motor, it is hoped that the change of the rotor flux can be observed so as to take remedial measures when the flux decreases abnormally, so as to accurately control the motor output torque.

[0004] In addition, since the motor parameters will change with the change of the motor operating state, it is hoped that accurate motor parameters can be obtained in real time when controlling the motor torque. Summary of the invention

[0005] In view of this, according to a first aspect of the present invention, an online observation and control device for motor parameters is proposed, the device comprising:

[0006] An input module is used to provide a dq axis current control value i of the motor. d_control ,i q_control ;

[0007] The controller is configured to control the dq axis current according to the dq axis current control value i provided by the input module. d_control ,i q_control Outputting corresponding control voltage to the motor to drive the motor to rotate;

[0008] A first acquisition module, wherein the first acquisition module is used to acquire the motor speed;

[0009] A second acquisition module, the second acquisition module is used to acquire the phase current of the motor;

[0010] A current conversion module, the current conversion module is used to convert the phase current obtained by the second acquisition module into the actual value i of the dq axis current of the motor d_real ,i q_real The controller is configured to be based on the actual value i of the dq axis currentd_real ,i q_real Adjust the control voltage output to the motor;

[0011] A lookup table is used to control the dq axis current according to the dq axis current control value i d_control ,i q_control Determine the dq axis inductance L of the motor d ,L q ;

[0012] The observer is configured to calculate the motor speed obtained by the first acquisition module and the dq axis inductance L determined by the lookup table. d ,L q And the actual value of the dq axis current i d_real ,i q_real estimating at least one operating parameter of the electric machine; and

[0013] An output module is used to output the observation result of the observer.

[0014] According to an optional embodiment, the at least one operating parameter includes an estimated value u of the dq axis voltage of the motor d_est ,u q_est , and the observer is further configured to consider the estimated value u of the dq axis voltage of the motor in the process of estimating the at least one operating parameter d_est ,u q_est and dq axis voltage control value u d_real ,u q_real The difference Δu between them.

[0015] According to an optional embodiment, the dq axis voltage control value u d_real ,u q_real The controller controls the dq axis current according to the value i d_control ,i q_control To provide, the device further comprises:

[0016] A voltage compensation module is configured to control the dq axis voltage value u according to the dq axis voltage control value u d_real ,u q_real and determining a voltage gain from the bus voltage and phase current of the motor, and compensating for voltage attenuation in the motor based on the voltage gain; and / or

[0017] A comparator is used to calculate the dq axis voltage control value u d_real ,u q_real and the estimated value of dq axis voltage u d_est ,u q_est The difference between Δu,

[0018] The observer is further configured to perform iterative calculation according to the difference Δu to determine the model parameters of the observer.

[0019] According to an optional embodiment, the at least one operating parameter includes the rotor flux ψ of the motor f , and the controller is further configured to calculate the rotor flux ψ based on the rotor flux ψ estimated by the observer. f To estimate the rotor temperature.

[0020] According to an optional embodiment, the dq axis current control value i of the motor d_control ,i q_control By changing the rotor flux ψ f Determined by looking up the table as input.

[0021] According to an optional embodiment, the at least one operating parameter includes a stator resistance R of the motor, and the controller is further configured to infer the stator temperature based on the stator resistance R.

[0022] According to an optional embodiment, the device further comprises a memory, wherein the controller is further configured to save the at least one operating parameter to the memory when the motor is powered off, and record the total power-off time of the motor.

[0023] The controller is further configured to read the working parameters and the total power-off time of the motor in the last working cycle from the memory when the motor is powered on again, and calculate the initial input of the observer based on the reading result.

[0024] According to an optional embodiment, the observer comprises a recursive least squares observer.

[0025] According to a second aspect of the present invention, there is further provided a motor controller, the motor controller comprising the online observation and control device for motor parameters as described above.

[0026] According to a third aspect of the present invention, there is further provided an electric drive system, the electric drive system comprising:

[0027] Motor; and

[0028] A motor controller as described above.

[0029] The online observation and control device according to the present invention can observe the rotor flux and stator resistance of the motor in real time, and further monitor the working state of the rotor and the working temperature of the stator, and in particular can observe the abnormal reduction of the rotor flux, so that remedial measures can be taken when the abnormal reduction of the rotor flux occurs, so as to accurately control the output torque of the motor. The device does not require a complex temperature model and a large amount of data calibration, saving computing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] By incorporating the accompanying drawings and Figure 1 With reference to the specific embodiments used to illustrate certain principles of the present invention, other features and advantages of the method of the present invention will become clear or be described in more detail.

[0031] Figure 1 A schematic structural diagram of an online observation and control device for motor parameters according to an exemplary embodiment of the present invention is shown.

[0032] Figure 2 The flowchart of the work flow for determining the rotor flux and the stator resistance by using the online observation and control device according to the present invention is shown.

[0033] Figure 3 A flow chart showing a process for determining an initial value of an online observation and control device according to the present invention is shown. DETAILED DESCRIPTION

[0034] The online observation and control device of the motor parameters according to the present invention will be described below with reference to the accompanying drawings and by way of example. In the following description, many specific details are set forth so that those skilled in the art can more fully understand the present invention. However, it is obvious to those skilled in the art that the present invention may not be implemented with some of these specific details. On the contrary, it is contemplated that the present invention may be implemented with any combination of the following features and elements, regardless of whether they relate to different embodiments. Therefore, the following aspects, features, embodiments and advantages are for illustrative purposes only and should not be regarded as elements or limitations of the claims.

[0035] In the normal operating range of the motor, the rotor temperature is the main factor affecting the rotor flux. The current method mainly estimates the current rotor temperature based on the rotor temperature model, and then calculates the rotor flux based on the temperature coefficient of the magnetic material. In vehicle applications, the flux estimation accuracy of this method is completely dependent on the temperature characteristics of the magnetic material and the accuracy of the rotor temperature model, and it is impossible to detect whether the rotor flux has an abnormal decrease.

[0036] In order to solve the above-mentioned defects in the existing flux estimation method, the present invention proposes a new online observation and control device for motor parameters, which can monitor the changes of rotor flux in real time without omitting the complex rotor temperature estimation model, and can judge the abnormal reduction of rotor flux. In other words, the device can realize real-time observation and protection of rotor flux.

[0037] Figure 1 FIG. 1 is a schematic diagram showing a structure of an online observation and control device for motor parameters according to an exemplary embodiment of the present invention. Figure 1To describe the specific structure and control process of the online observation and control device.

[0038] The device may firstly include an input module and a controller, wherein the input module is used to provide a dq axis current control value i of the motor. d_control ,i q_control When the vehicle is just powered on, the dq axis current control value can be determined based on the initial flux linkage table stored in the motor controller.

[0039] The dq axis current control value i d_control ,i q_control The input module can further provide the controller with the dq axis current control value i d_control ,i q_control After the voltage compensation operation and the voltage variation operation, a corresponding control voltage (which may be in the form of a three-phase voltage for driving the three-phase winding of the motor) is output to the motor to drive the motor to rotate.

[0040] In addition, the device may also include a first acquisition module for acquiring the motor speed and a second acquisition module for acquiring the motor phase current. The phase current acquired by the second acquisition module can be converted into dq axis current via the current conversion module, and the dq axis current can be used as the actual value i of the dq axis current of the motor. d_real ,i q_real is fed back to the controller to achieve closed-loop control of the motor current. That is, the controller can be based on the actual value of the dq axis current i fed back. d_real ,i q_real Adjusts the control voltage output to the motor.

[0041] The online observation and control device according to the present invention is also special in that it includes a lookup table, an observer, and an output module for outputting the observation result of the observer. The dq axis current control value i provided by the input module is d_control ,i q_control Substituting this as input into the lookup table, the motor’s dq-axis inductance L can be determined d ,L q The observer can be based on the motor speed obtained by the first acquisition module and the dq axis inductance L determined by the lookup table. d ,L q And the actual value of dq axis current i d_real ,i q_real At least one operating parameter of the electric machine is estimated.

[0042] The operating parameters may include, for example, the estimated value u of the dq axis voltage of the motor d_est ,u q_est , and in the process of estimating at least one operating parameter, the observer may consider the estimated value u of the dq axis voltage of the motor d_est,u q_est and dq axis voltage control value u d_real ,u q_real The difference Δu between them.

[0043] Here, the dq axis voltage control value u d_real ,u q_real The controller can be controlled by the dq axis current control value i provided by the input module d_control ,i q_control To provide, the dq axis voltage control value u q_real ,u q_real It can be further converted into the three-phase voltage of the motor through a voltage gain nonlinear compensation module and a voltage conversion module.

[0044] Here, it can be understood that in the motor inverter, the voltage attenuation of the motor may be caused by the switch tube voltage drop, dead time, overmodulation and other reasons. If the attenuation is not compensated and corrected in time, it will further lead to the control deviation of the motor. For this reason, a voltage compensation module is also provided in the device of the present invention, which is used to control the motor voltage according to the dq axis voltage control value u d_real ,u q_real The bus voltage and phase current of the motor determine a voltage gain, which can be a nonlinear compensation value. Based on the compensation value, the voltage attenuation in the motor can be compensated to ensure that the dq axis voltage output by the current control loop is consistent with the voltage actually output by the motor inverter, thereby ensuring the accuracy of motor control.

[0045] In addition, the device may also include a comparator, which is used to calculate the dq axis voltage control value u d_real ,u q_real and the estimated value of dq axis voltage u d_est ,u q_est The difference Δu between them can be fed back to the observer, and the observer can perform iterative calculation based on the difference Δu to determine the model parameters of the observer.

[0046] The operating parameters determined by the observer may also include the rotor flux ψ of the motor f and stator resistance R. The controller can be based on the rotor flux ψ estimated by the observer f Estimate the rotor temperature, which can be used for current table lookup rotor temperature monitoring to determine whether the rotor is overheated. In addition, the rotor flux ψ f The observation results can also be used as the input of the dq axis current lookup table, that is, the dq axis current control value i of the motor d_control ,i q_control By changing the rotor flux ψ fAdditionally, the input of the dq axis current table lookup may also include parameters such as motor torque, voltage / speed, etc.

[0047] The operating parameters determined by the observer may further include a stator resistance R of the motor, and the controller may determine the stator temperature based on the stator resistance R.

[0048] As an example, the observer may be a recursive least squares (RLS) observer, with the stator resistance R and the rotor flux ψ f Taking the observation target as an example, the operation process of the RLS observer can be expressed by the following equation:

[0049]

[0050] In the above equation, d(n) is the actual observed value in the electric drive system, where u d * (n),u q * (n) is the dq axis voltage output by the motor current control closed loop, Ld, Lq are the motor current

[0051] ^

[0052] The sense can be determined based on the dq axis current according to a pre-calibrated lookup table. w(n) is the observation target, that is, the target parameter to be observed, including the stator resistance R and the rotor flux ψ f u(n) is the input required for the least squares method, including the motor electrical angular velocity ω e (n), dq axis current i d (n),i q (n), etc., where the motor electrical angular velocity ω e (n) can be calculated based on the motor speed.

[0053] The calculation process of the least squares method with forgetting factor (where λ is the forgetting factor coefficient) can be expressed as:

[0054]

[0055]

[0056]

[0057] P(n)=λ -1 P(n-1)-λ -1 (n)k(n)u T (n)P(n-1)

[0058] According to the above process formula, the stator resistance R and rotor flux ψ can be obtained f, as the observation result of the observer. For the rotor flux ψ f The observation result can be used as a criterion for judging whether the rotor is overheated; in addition, the stator resistance R can be used as an estimation standard for the stator temperature.

[0059] Figure 2 The flowchart of determining the rotor flux and stator resistance by using the online observation and control device according to the present invention is shown. When the vehicle is powered on, in order to ensure that the RLS observer can have an appropriate initial value when the motor just enters the torque control mode, during the period of entering the torque control mode, the dq current initial value needs to be given so that the RLS observer can obtain the initial values ​​of the rotor flux and stator resistance.

[0060] During the subsequent operation of the motor, the stator resistance and rotor flux can be observed in real time with the help of the RLS observer. The stator temperature can be further determined based on the stator resistance and the temperature coefficient of the copper wire. For the rotor flux, once it deviates from the normal range, a warning signal can be issued. Preferably, the warning signal can also be de-interference processed. For example, if the warning signal continues for more than a predetermined time, it is determined that the flux has indeed undergone an abnormal change.

[0061] If the flux observation result output by the observer is within the normal range, it can be used as the input of the dq axis current lookup table to determine the dq axis current of the motor together with the motor torque and voltage / speed. The dq axis current determined by the lookup table can be used as the current control value i provided to the controller. d_control ,i q_control .

[0062] In order to improve the observation speed when power is just turned on, the observed motor parameters (stator resistance and rotor flux, etc.) can be automatically written into the memory (for example, non-volatile memory NVM) during the power-off process of the motor, and the power-off time can be recorded. After powering on again, the initial values ​​of the stator resistance and rotor flux at power-on can be estimated based on the power-off time and the data stored in NVM. Figure 3 The process is shown in detail.

[0063] The online observation and control device according to the present invention can observe the rotor flux and stator resistance of the motor in real time, and further monitor the working state of the rotor and the working temperature of the stator, and in particular can observe the abnormal reduction of the rotor flux, so that remedial measures can be taken when the abnormal reduction of the rotor flux occurs, so as to accurately control the output torque of the motor. The device does not require a complex temperature model and a large amount of data calibration, saving computing costs.

[0064] In this article, the "dq axis" of the motor refers to the direct axis and quadrature axis of the motor, where the direct axis is also called the d axis, which is aligned with the direction of the motor rotor magnetic field; and the quadrature axis is also called the q axis, which is perpendicular to the direction of the motor rotor magnetic field. Therefore, it can be understood by those skilled in the art that the term "dq axis current (or inductance)" refers to the d axis current (or inductance) and the q axis current (or inductance). For example, the "dq axis current control value i d_control ,i q_control "Including the direct axis current control value i d_control and the quadrature axis current control value i q_control , and "dq axis voltage control value u d_real ,u q_real "Including the voltage control value u of the direct axis d_real and the voltage control value u of the quadrature axis q_real .

[0065] Those skilled in the art will appreciate that the various steps of the method according to the present invention are not limited to being implemented in the order listed above. In addition, in the present invention, the terms "comprise" and "include" indicate that in addition to the steps directly and clearly stated in the specification and claims, the technical solution of the present application does not exclude the situation of having other steps that are not directly or clearly stated.

[0066] Although the present invention has been disclosed as above with preferred embodiments, the present invention is not limited thereto. Any changes and modifications made by any person skilled in the art without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention, and therefore the protection scope of the present invention should be subject to the scope defined by the claims.

Claims

1. An online observation and control device for motor parameters, characterized in that: The device includes: An input module is used to provide a dq axis current control value i of the motor. d_control ,i q_control ; The controller is configured to control the dq axis current according to the dq axis current control value i provided by the input module. d_control ,i q_control Outputting corresponding control voltage to the motor to drive the motor to rotate; A first acquisition module, wherein the first acquisition module is used to acquire the motor speed; A second acquisition module, the second acquisition module is used to acquire the phase current of the motor; A current conversion module, the current conversion module is used to convert the phase current obtained by the second acquisition module into the actual value i of the dq axis current of the motor d_real ,i q_real The controller is configured to be based on the actual value i of the dq axis current d_real ,i q_real Adjust the control voltage output to the motor; A lookup table is used to control the dq axis current according to the dq axis current control value i d_control ,i q_control Determine the dq axis inductance L of the motor d , L q ; The observer is configured to calculate the motor speed obtained by the first acquisition module and the dq axis inductance L determined by the lookup table. d , L q And the actual value of the dq axis current i d_real ,i q_real estimating at least one operating parameter of the electric machine; and An output module is used to output the observation result of the observer.

2. The online observation and control device for motor parameters according to claim 1, characterized in that: The at least one operating parameter includes an estimated value u of the dq axis voltage of the motor dest ,u qest , and the observer is further configured to consider the estimated value u of the dq axis voltage of the motor in the process of estimating the at least one operating parameter d_est ,u q_est and dq axis voltage control value u d_real ,u q_real The difference Δu between them.

3. The online observation and control device for motor parameters according to claim 2, characterized in that: The dq axis voltage control value u d_real ,u q_real The controller controls the dq axis current according to the value i d_control ,i q_control To provide, the device further comprises: A voltage compensation module is configured to control the dq axis voltage value u according to the dq axis voltage control value u d_real ,u q_real and determining a voltage gain from the bus voltage and phase current of the motor, and compensating for voltage attenuation in the motor based on the voltage gain; and / or A comparator is used to calculate the dq axis voltage control value u d_real ,u q_real and the estimated value of dq axis voltage u d_est ,u q_est The difference between Δu, The observer is further configured to perform iterative calculation according to the difference Δu to determine the model parameters of the observer.

4. The online observation and control device for motor parameters according to any one of claims 1 to 3, characterized in that: The at least one operating parameter includes the rotor flux ψ of the motor f , and the controller is further configured to calculate the rotor flux ψ based on the rotor flux ψ estimated by the observer. f Estimate the rotor temperature.

5. The online observation and control device for motor parameters according to claim 4, characterized in that: The motor's dq axis current control value i d_control ,i q_control By changing the rotor flux ψ f Determined by looking up the table as input.

6. The online observation and control device for motor parameters according to any one of claims 1 to 3, characterized in that: The at least one operating parameter includes a stator resistance R of the motor, and the controller is further configured to infer a stator temperature based on the stator resistance R.

7. The online observation and control device for motor parameters according to any one of claims 1 to 3, characterized in that: The device further comprises a memory, wherein the controller is further configured to save the at least one operating parameter in the memory when the motor is powered off, and record the total power-off time of the motor, The controller is further configured to read the working parameters and the total power-off time of the motor in the last working cycle from the memory when the motor is powered on again, and calculate the initial input of the observer based on the reading result.

8. The online observation and control device for motor parameters according to any one of claims 1 to 3, characterized in that: The observer includes a recursive least squares observer.

9. A motor controller, characterized in that: The motor controller comprises an online observation and control device for motor parameters according to any one of claims 1 to 8.

10. An electric drive system, characterized in that: The electric drive system comprises a motor and a motor controller according to claim 9.

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