阅读说明：本技术 极性判断方法、判断装置和电机控制系统 (Polarity judgment method, polarity judgment device and motor control system ) 是由 陈辉 秦向南 付俊永 于 2020-06-23 设计创作，主要内容包括：本发明提出了一种极性判断方法、判断装置和电机控制系统。其中,极性判断方法包括：向电机的估算直轴注入至多两组脉冲信号,至多两组脉冲信号中的每组脉冲信号均包括正脉冲信号和负脉冲信号；获取估算直轴的正向反馈电流峰值和负向反馈电流峰值；将正向反馈电流峰值的绝对值和负向反馈电流峰值的绝对值进行比较；根据比较结果确定电机的转子极性。通过本发明的技术方案,在不增加现有控制器系统成本的前提下,可以准确地实现永磁同步电机小容值母线电容控制器的高频注入极性判断,精度较高,方法简单易实现。(The invention provides a polarity judgment method, a polarity judgment device and a motor control system. The polarity judgment method comprises the following steps: injecting at most two groups of pulse signals into an estimated direct axis of the motor, wherein each group of pulse signals in the at most two groups of pulse signals comprises a positive pulse signal and a negative pulse signal; acquiring a positive feedback current peak value and a negative feedback current peak value of the estimated straight axis; comparing the absolute value of the positive feedback current peak value with the absolute value of the negative feedback current peak value; and determining the rotor polarity of the motor according to the comparison result. According to the technical scheme, on the premise that the system cost of the existing controller is not increased, the high-frequency injection polarity judgment of the permanent magnet synchronous motor small-capacitance-value bus capacitor controller can be accurately realized, the precision is high, and the method is simple and easy to realize.)

1. A polarity judging method for determining a polarity of a rotor of an electric motor, the polarity judging method comprising

Injecting at most two groups of pulse signals into an estimated direct axis of the motor, wherein each group of pulse signals in the at most two groups of pulse signals comprises a positive pulse signal and a negative pulse signal;

acquiring a positive feedback current peak value and a negative feedback current peak value of the estimated straight axis;

comparing the absolute value of the positive feedback current peak value with the absolute value of the negative feedback current peak value;

and determining the rotor polarity of the motor according to the comparison result.

2. The polarity judging method according to claim 1,

each group of pulse signals in at most two groups of pulse signals are pulse voltages, the absolute value of the product of the amplitude of the positive pulse voltage and the injection time in each group of pulse voltages is equal to the absolute value of the product of the amplitude of the negative pulse voltage and the injection time, and the forward feedback current of the estimated direct axis is restored to zero at the moment of starting to inject the negative pulse voltage.

3. The polarity judging method according to claim 2, wherein the at most two sets of pulse signals include a first set of pulse voltages and a second set of pulse voltages, and the step of injecting the at most two sets of pulse signals into the estimated direct axis of the motor specifically includes:

detecting a bus voltage during the injecting of the first set of pulse voltages, comparing the bus voltage to a threshold voltage threshold;

stopping injecting the current pulse voltage and recording the duration of the current pulse voltage based on the condition that the bus voltage is less than or equal to the critical voltage threshold, wherein the current pulse voltage comprises a positive pulse voltage and/or a negative pulse voltage in the first group of pulse voltages;

and updating the injection time of the second group of pulse voltages according to the duration of the positive pulse voltage and/or the negative pulse voltage in the first group of pulse voltages, and injecting the updated second group of pulse voltages after the injection of the first group of pulse voltages is finished.

4. The polarity judging method according to claim 3, wherein the step of updating the injection time of the second group of pulse voltages specifically comprises:

based on U_pAnd T_pcIs equal to U_nAnd T_ncThe injection time of the second set of pulse voltages need not be updated;

based on U_pAnd T_pcIs greater than U_nAnd T_ncThe injection time T of the positive pulse voltage in the second group of pulse voltages_pIs equal to U_nAnd T_ncIs divided by U_pInjection time T of negative pulse voltage_nIs equal to T_nc；

Based on U_pAnd T_pcIs less than U_nAnd T_ncThe injection time T of the positive pulse voltage in the second group of pulse voltages_pIs equal to T_pcInjection time T of negative pulse voltage_nIs equal to U_pAnd T_pcIs divided by U_n；

Wherein, U_pIs the amplitude, T, of a positive pulse voltage in the first set of pulse voltages_pcIs the duration of a positive pulse voltage, U, of the first set of pulse voltages_nIs the amplitude, T, of the negative pulse voltage in the first set of pulse voltages_ncIs the duration of the negative pulse voltage in the first set of pulse voltages.

5. The polarity judging method according to claim 3,

and the critical voltage threshold is the bus voltage corresponding to the moment when the slope of the feedback current of the estimated direct axis starts to decrease.

6. The polarity judging method according to any one of claims 1 to 5, wherein the step of determining the polarity of the rotor of the motor according to the comparison result specifically comprises:

the estimated direct axis is a real direct axis based on the condition that the absolute value of the positive feedback current peak value is smaller than the absolute value of the negative feedback current peak value;

and based on the condition that the absolute value of the positive feedback current peak value is greater than or equal to the absolute value of the negative feedback current peak value, the direction of the real straight axis is opposite to that of the estimated straight axis.

7. A polarity judging device for determining a polarity of a rotor of an electric motor, comprising:

a memory storing a computer program;

a processor implementing the polarity determination method as claimed in any one of claims 1 to 6 when executing the computer program.

8. A motor control system, comprising:

a memory storing a computer program;

a processor implementing the polarity determination method as claimed in any one of claims 1 to 6 when executing the computer program.

9. The motor control system of claim 8, further comprising: and the bus capacitance control device is used for injecting at most two groups of pulse signals into the estimated direct axis of the motor.

10. The motor control system of claim 9, wherein the bus capacitance control device employs a bus capacitance having a capacitance range of: greater than 0 and less than or equal to 10 uF.

11. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, implements the polarity determination method according to any one of claims 1 to 6.

Technical Field

The invention relates to the technical field of motors, in particular to a polarity judgment method, a polarity judgment device, a motor control system and a computer readable storage medium.

Background

The motor low-speed position-free control method based on high-frequency injection has wide application prospect due to the advantages of simple realization, low cost and the like. By injecting a high-frequency carrier signal into the stator winding, a current response signal related to the salient pole position is further extracted, and then a position observer is utilized, so that estimated rotor position information is obtained. However, the position observer based on the high frequency injection may converge to N or S pole, so that the polarity determination is required for the initial position identification.

The main idea of polarity judgment is to inject positive and negative pulses into the estimation direct axis, and then to compare the current peak value, so as to judge the N/S pole. If the estimated direct axis is the real direct axis, the magnetic increasing process is performed when the direct axis is positive, so that the current peak value is smaller than that when the direct axis is added with negative pulse, and vice versa. The main parameters of polarity determination such as voltage amplitude, duration, etc. are very important.

In the small-capacitance-value bus capacitor control system, the large-capacitance-value electrolytic capacitor for storing energy after the power grid voltage is rectified is replaced by the small-capacitance-value capacitor, so that the bus voltages at two ends of the capacitor are simultaneously influenced by the power grid voltage and the load. On the one hand, the bus voltage will pulsate at twice the frequency of the grid voltage; on the other hand, the bus voltage will fluctuate with load variations, with the bus voltage falling off the greater the load. When the load is large and the bus voltage is low, especially when the bus voltage will not be enough to provide the control voltage needed for controlling the motor, it will cause the motor current to be difficult to follow the current command dynamically and well.

In a permanent magnet brushless motor small-capacitance value bus capacitance control system, when polarity judgment is carried out by using high-frequency injection initial position identification, in the process of injecting positive and negative pulses into an estimation direct axis, the bus voltage can drop or even can be insufficient to provide control voltage required by pulse injection, and then the polarity judgment cannot be accurately carried out through current feedback.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art or the related art.

To this end, an aspect of the present invention is to provide a polarity determination method.

Another aspect of the present invention is to provide a polarity determination apparatus.

Yet another aspect of the present invention is to provide a motor control system.

Yet another aspect of the present invention is to provide a computer-readable storage medium.

In view of the above, according to one aspect of the present invention, there is provided a polarity determining method for determining a polarity of a rotor of an electric motor, the polarity determining method including: injecting at most two groups of pulse signals into an estimated direct axis of the motor, wherein each group of pulse signals in the at most two groups of pulse signals comprises a positive pulse signal and a negative pulse signal; acquiring a positive feedback current peak value and a negative feedback current peak value of the estimated straight axis; comparing the absolute value of the positive feedback current peak value with the absolute value of the negative feedback current peak value; and determining the rotor polarity of the motor according to the comparison result.

The polarity judgment method provided by the invention can avoid the condition that the bus voltage drops or even is insufficient to provide the control voltage required by pulse injection, which leads to the fact that the polarity judgment can not be carried out through current feedback by injecting one group or two groups of positive and negative pulse signals in the process of judging the high-frequency injection polarity of the small-capacitance bus capacitor controller, namely, the polarity judgment is carried out through the current feedback peak value on the premise that the bus voltage is sufficient to provide the control voltage required by pulse injection, thereby accurately realizing the high-frequency injection polarity judgment of the small-capacitance bus capacitor controller of the permanent magnet synchronous motor on the premise of not increasing the system cost of the existing controller, having higher precision and being simple and easy to realize.

It can be understood that after a group of positive and negative pulse signal injection is completed, if the condition that the bus voltage drops or even the control voltage required by the pulse injection is not enough is not generated, the polarity judgment of the initial position identification of the motor rotor can be realized only by one positive and negative pulse injection; if bus voltage drops and even the bus voltage drops are not enough to provide the control voltage required by pulse injection, a group of positive and negative pulses are injected to ensure that polarity judgment is carried out through a current feedback peak value.

In addition, the bus capacitor adopted by the bus capacitor controller with a small capacitance value has a capacitance value range less than or equal to 10uF, but is not limited thereto.

According to the polarity determination method of the present invention, the following technical features may be provided:

in the above technical solution, each of at most two groups of pulse signals is pulse voltage, and a product of an amplitude of positive pulse voltage and injection time in each group of pulse voltage is equal to a product of an amplitude of negative pulse voltage and injection time, and at a time when injection of negative pulse voltage is started, it is estimated that a forward feedback current of the direct axis has been restored to zero.

In the technical scheme, the product of the amplitude of the positive pulse voltage and the injection time in each group of pulse voltages is equal to the product of the amplitude of the negative pulse voltage and the injection time, so that the volt-second area balance of the positive pulse voltage and the negative pulse voltage is ensured, and further, the polarity judgment can be accurately carried out through the current feedback peak value. In addition, the injection time of the negative pulse is to ensure that the positive current feedback of the positive pulse is restored to zero so as to ensure that the initial points of injecting the positive and negative pulses are the same, thereby ensuring the accuracy of polarity judgment.

In any of the above technical solutions, the step of injecting at most two groups of pulse signals into the estimated direct axis of the motor, where the at most two groups of pulse signals include a first group of pulse voltages and a second group of pulse voltages, specifically includes: detecting the bus voltage during the process of injecting the first group of pulse voltages, and comparing the bus voltage with a critical voltage threshold; stopping injecting the current pulse voltage based on the condition that the bus voltage is less than or equal to the critical voltage threshold value, and recording the duration of the current pulse voltage, wherein the current pulse voltage comprises a positive pulse voltage and/or a negative pulse voltage in the first group of pulse voltages; and updating the injection time of the second group of pulse voltages according to the duration of the positive pulse voltage and/or the negative pulse voltage in the first group of pulse voltages, and injecting the updated second group of pulse voltages after the injection of the first group of pulse voltages is finished.

In the technical scheme, in the process of injecting the first group of pulse voltages, the bus voltage is detected in real time or at certain time intervals, and whether the injection of the second group of positive and negative pulse voltages is needed or not is judged by comparing the bus voltage with a critical voltage threshold. And if the second group of pulse voltages need to be injected, updating the injection time of the second group of pulse voltages according to the duration of the positive pulse voltage and/or the negative pulse voltage in the first group of pulse voltages. Specifically, if the bus voltage falls to a critical voltage threshold value in the process of injecting the positive pulse voltage, stopping injecting the positive pulse voltage, and recording the duration of injecting the positive pulse voltage; if the bus voltage drops to the threshold voltage threshold value in the process of injecting the negative pulse voltage, stopping injecting the negative pulse voltage, and recording the duration time of injecting the negative pulse; then, updating the injection time of a second group of pulse voltages according to the recorded duration time of the positive pulse voltages and/or the duration time of the negative pulse voltages, and obtaining a polarity judgment result according to the comparison of the absolute value of the positive current feedback peak value and the absolute value of the negative current feedback peak value after the second group of pulse voltages are injected; and if the second group of pulse voltages are not required to be injected, directly obtaining a polarity judgment result according to the comparison of the absolute value of the positive current feedback peak value and the absolute value of the negative current feedback peak value.

It can be understood that when the bus voltage drops to the threshold voltage during the injection of the positive pulse, or when the bus voltage drops to the threshold voltage during the injection of the negative pulse, even when the bus voltage drops to the threshold voltage during the injection of the positive and negative pulses, the second set of positive and negative pulse injections is performed, and the pulse injection time is updated according to the result of the first set of positive and negative pulse injections (i.e. the duration of the positive pulse voltage and/or the negative pulse voltage in the first set of pulse voltages).

In addition, after one positive and negative pulse injection is completed, if the bus voltage is always higher than the threshold voltage, the absolute values of the feedback peak values of the positive current and the negative current of the straight shaft can be directly obtained and estimated, and judgment is carried out.

Compared with the electrolytic capacitor controller scheme, the polarity judgment method provided by the invention only needs to determine the threshold voltage threshold additionally, and is simple and easy to implement.

In any of the above technical solutions, the step of updating the injection time of the second group of pulse voltages specifically includes: based on U_pAnd T_pcIs equal to U_nAnd T_ncThe injection time of the second group of pulse voltages does not need to be updated; based on U_pAnd T_pcIs greater than U_nAnd T_ncThe injection time T of the positive pulse voltage in the second group of pulse voltages_pIs equal to U_nAnd T_ncIs divided by U_pInjection time T of negative pulse voltage_nIs equal to T_nc(ii) a Based on U_pAnd T_pcIs less than U_nAnd T_ncThe injection time T of the positive pulse voltage in the second group of pulse voltages_pIs equal to T_pcInjection time T of negative pulse voltage_nIs equal to U_pAnd T_pcIs divided by U_n(ii) a Wherein, U_pIs the amplitude, T, of a positive pulse voltage in the first set of pulse voltages_pcIs the duration of a positive pulse voltage, U, of the first set of pulse voltages_nIs the amplitude, T, of the negative pulse voltage in the first set of pulse voltages_ncIs the duration of the negative pulse voltage in the first set of pulse voltages.

In the technical scheme, the injection time of the second group of positive and negative pulse voltages is U when the first group of pulse voltages are injected_pT_pc(U_pAnd T_pcProduct of) and U_nT_nc(U_nAnd T_ncProduct of) is determined. If U is present_pT_pcGreater than U_nT_ncInjection time T of the second set of positive pulses_p＝U_nT_nc/U_pInjection time T of the second set of negative pulses_n＝T_nc(ii) a On the contrary, if U_pT_pcLess than U_nT_ncInjection time T of the second set of positive pulses_p＝T_pcInjection time T of the second set of negative pulses_n＝U_pT_pc/U_n. After the second group of positive and negative pulses are injected, the absolute values of the feedback peak values of the positive and negative currents of the estimated straight axis can be obtained, and a polarity judgment result is obtained through judgment.

In any of the above technical solutions, the threshold voltage is greater than or equal to the bus voltage corresponding to the time when the slope of the estimated direct axis feedback current starts to decrease.

In the technical scheme, a bus voltage value corresponding to an inflection point at which the slope of feedback current of an estimated direct axis begins to decrease is determined, so that a critical voltage threshold value is determined, the critical voltage threshold value needs to be larger than or equal to the bus voltage value, once the critical voltage threshold value is smaller than the bus voltage value corresponding to the inflection point, positive and negative pulses are continuously injected, the bus voltage may drop too fast or even not enough to provide control voltage required by a control motor, and a system mistakenly considers that the bus voltage does not drop all the time, so that misjudgment is caused.

In any of the above technical solutions, the step of determining the polarity of the rotor of the motor according to the comparison result specifically includes: estimating the straight axis as a real straight axis based on the condition that the absolute value of the positive feedback current peak value is smaller than the absolute value of the negative feedback current peak value; and based on the condition that the absolute value of the positive feedback current peak value is larger than or equal to the absolute value of the negative feedback current peak value, the direction of the real direct axis is opposite to that of the estimated direct axis.

In the technical scheme, when the absolute value of the positive feedback current peak value is smaller than the absolute value of the negative feedback current peak value, the estimated straight shaft is a real straight shaft, namely, the magnetic pole direction pointed by the initial position of the motor rotor is consistent with the positive direction of the estimated straight shaft, and when the absolute value of the positive feedback current peak value is larger than or equal to the absolute value of the negative feedback current peak value, the estimated straight shaft is opposite to the real straight shaft in the reverse direction, namely, the magnetic pole direction pointed by the initial position of the motor rotor is opposite to the positive direction of the estimated straight shaft.

According to another aspect of the present invention, there is provided a polarity determination apparatus including: a memory storing a computer program; and the processor is used for realizing the polarity judgment method of any one technical scheme when executing the computer program.

In the polarity determination apparatus provided by the present invention, the computer program, when executed by the processor, implements the steps of the polarity determination method according to any of the above-mentioned technical solutions, and therefore the polarity determination apparatus includes all the advantageous effects of the polarity determination method according to any of the above-mentioned technical solutions.

According to still another aspect of the present invention, there is provided a motor control system including: a memory storing a computer program; and the processor is used for realizing the polarity judgment method of any one technical scheme when executing the computer program.

In the motor control system provided by the invention, the computer program is executed by the processor to realize the steps of the polarity judgment method in any one of the above technical schemes, so that the motor control system has all the beneficial effects of the polarity judgment method in any one of the above technical schemes.

In the above technical solution, the method further comprises: and the bus capacitance control device is used for injecting at most two groups of pulse signals into the estimated direct axis of the motor.

In any of the above technical solutions, a capacitance value range of a bus capacitor adopted by the bus capacitor control device is as follows: greater than 0 and less than or equal to 10 uF.

In the technical scheme, after the amplitude of a first group of positive and negative pulse voltages is determined, the positive and negative pulse voltages are injected into an estimation direct axis through a small-capacitance bus capacitor controller, in the process of injecting the positive and negative pulse voltages, the bus voltages are collected, including the bus voltages collected in real time or at fixed time intervals, and whether the injection of the positive and negative pulse voltages needs to be carried out again and the injection time of the pulse positive and negative pulse voltages needs to be updated is judged through the comparison of the bus voltages and a critical voltage threshold; and finally, obtaining a polarity judgment result according to the comparison of the absolute value of the positive current feedback peak value and the absolute value of the negative current feedback peak value. The motor control system provided by the invention can accurately realize the judgment of the high-frequency injection polarity of the small-capacitance value bus capacitor controller of the permanent magnet synchronous motor by injecting positive and negative pulses once or twice aiming at the condition that the bus falls off in the judgment process of the high-frequency injection polarity of the small-capacitance value bus capacitor controller.

According to yet another aspect of the present invention, a computer-readable storage medium is provided, on which a computer program is stored, which when executed by a processor implements the polarity determination method according to any of the above-mentioned aspects.

The computer-readable storage medium provided by the present invention, when being executed by a processor, implements the steps of the polarity determination method according to any of the above-mentioned technical solutions, and therefore, the computer-readable storage medium includes all the beneficial effects of the polarity determination method according to any of the above-mentioned technical solutions.

Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

fig. 1 is a flowchart illustrating a polarity determination method according to a first embodiment of the present invention;

fig. 2 is a flow chart illustrating a polarity determination method according to a second embodiment of the present invention;

FIG. 3 is a flow chart illustrating a method for updating injection times of a second set of pulse voltages according to an embodiment of the present invention;

FIG. 4 is a flow chart illustrating a method of injecting a positive pulse voltage according to an embodiment of the invention;

FIG. 5 is a schematic flow chart of a method of injecting negative pulsed voltage according to an embodiment of the present invention;

FIG. 6 illustrates a bus voltage, d-axis command voltage, and d-axis current feedback diagram of a specific embodiment of the present invention;

FIG. 7 illustrates a high frequency injection d-axis command voltage diagram according to an embodiment of the present invention;

FIG. 8 is a schematic diagram of positive pulse injection logic for one embodiment of the present invention;

FIG. 9 illustrates a negative pulse injection logic diagram of an embodiment of the present invention;

FIG. 10 is a schematic diagram illustrating a second set of positive and negative pulse injection decision logic and injection timing update in accordance with an embodiment of the present invention;

FIG. 11 illustrates a d-axis forward and reverse current feedback comparison logic diagram for an exemplary embodiment of the present invention;

fig. 12 shows a schematic block diagram of a polarity determination apparatus of an embodiment of the present invention;

FIG. 13 shows a schematic block diagram of a motor control system of one embodiment of the present invention.

Detailed Description

In order that the above objects, features and advantages of the present invention can be more clearly understood, a more particular description of the invention will be rendered by reference to the appended drawings. It should be noted that the embodiments of the present invention and features of the embodiments may be combined with each other without conflict.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced in other ways than those specifically described herein, and therefore the scope of the present invention is not limited to the specific embodiments disclosed below.

In an embodiment of the first aspect of the present invention, a polarity determining method is provided for determining the polarity of a rotor of an electric machine, and the polarity determining method is described in detail by the following embodiments.

First embodiment, fig. 1 shows a flowchart of a polarity determination method according to a first embodiment of the present invention. The polarity judgment method comprises the following steps:

102, injecting at most two groups of pulse signals into an estimated direct axis of the motor, wherein each group of pulse signals in the at most two groups of pulse signals comprises a positive pulse signal and a negative pulse signal;

104, acquiring a positive feedback current peak value and a negative feedback current peak value of the estimated straight axis;

step 106, comparing the absolute value of the positive feedback current peak value with the absolute value of the negative feedback current peak value;

and step 108, determining the rotor polarity of the motor according to the comparison result.

The polarity judgment method provided by the embodiment of the invention can avoid the condition that the bus voltage drops or even is insufficient to provide the control voltage required by pulse injection, which leads to the fact that the polarity judgment cannot be carried out through current feedback due to one group or two groups of positive and negative pulse signal injection in the process of judging the high-frequency injection polarity of the small-capacitance bus capacitor controller, namely, the polarity judgment is carried out through the current feedback peak value on the premise that the bus voltage is sufficient to provide the control voltage required by the pulse injection, so that the high-frequency injection polarity judgment of the small-capacitance bus capacitor controller of the permanent magnet synchronous motor can be accurately realized on the premise of not increasing the system cost of the existing controller, the precision is higher, and the method is simple and easy to realize.

It can be understood that after a group of positive and negative pulse signal injection is completed, if the condition that the bus voltage drops or even the control voltage required by the pulse injection is not enough is not generated, the polarity judgment of the initial position identification of the motor rotor can be realized only by one positive and negative pulse injection; if bus voltage drops and even the bus voltage drops are not enough to provide the control voltage required by pulse injection, a group of positive and negative pulses are injected to ensure that polarity judgment is carried out through a current feedback peak value.

In addition, the bus capacitor adopted by the bus capacitor controller with a small capacitance value has a capacitance value range less than or equal to 10uF, but is not limited thereto.

In the above embodiment, each of the at most two groups of pulse signals is a pulse voltage, and the product of the amplitude of the positive pulse voltage and the injection time in each group of pulse voltages is equal to the product of the amplitude of the negative pulse voltage and the injection time, and at the time of starting to inject the negative pulse voltage, the forward feedback current of the straight axis is estimated to be returned to zero.

In the embodiment, the product of the amplitude of the positive pulse voltage and the injection time in each group of pulse voltages is equal to the product of the amplitude of the negative pulse voltage and the injection time, so that the volt-second area balance of the positive pulse voltage and the negative pulse voltage is ensured, and further, the polarity judgment can be accurately carried out through the current feedback peak value. In addition, the injection time of the negative pulse is to ensure that the forward current feedback of the estimated direct axis based on the positive pulse is restored to zero so as to ensure that the initial points of injecting the positive and negative pulses are the same, thereby ensuring the accuracy of polarity judgment.

Second embodiment, fig. 2 is a flowchart illustrating a polarity determination method according to a second embodiment of the present invention. The polarity judgment method comprises the following steps:

step 202, detecting the bus voltage in the process of injecting the first group of pulse voltages;

step 204, judging whether the bus voltage is less than or equal to a critical voltage threshold value; executing step 206 based on the condition that the bus voltage is less than or equal to the critical voltage threshold, and executing step 210 based on the condition that the bus voltage is greater than the critical voltage threshold;

step 206, stopping injecting the current pulse voltage, and recording the duration of the current pulse voltage, wherein the current pulse voltage comprises a positive pulse voltage and/or a negative pulse voltage in the first group of pulse voltages;

step 208, updating the injection time of the positive pulse voltage and the negative pulse voltage in the second group of pulse voltages according to the duration time of the positive pulse voltage and/or the negative pulse voltage in the first group of pulse voltages, and injecting the updated second group of pulse voltages after the injection of the first group of pulse voltages is finished;

step 210, acquiring a positive feedback current peak value and a negative feedback current peak value of the estimated straight axis;

step 212, comparing the absolute value of the positive feedback current peak value with the absolute value of the negative feedback current peak value;

and step 214, determining the rotor polarity of the motor according to the comparison result.

In the embodiment, whether positive and negative pulse injection is needed again and the injection time of the pulse is updated is judged by comparing the bus voltage with the threshold voltage; and finally, obtaining a polarity judgment result according to the comparison of the absolute value of the positive current feedback peak value and the absolute value of the negative current feedback peak value. Specifically, if the bus voltage falls to a threshold voltage threshold value in the process of injecting the positive pulse voltage, stopping injecting the positive pulse voltage, and recording the duration of injecting the positive pulse voltage; and injecting negative pulse voltage into the estimated direct axis, stopping injecting the negative pulse voltage if the bus voltage falls to a critical voltage threshold value in the process of injecting the negative pulse voltage, and recording the duration of the injected negative pulse. And updating the injection time of the positive pulse voltage and the negative pulse voltage in the second group of pulse voltages according to the duration of the positive pulse and the negative pulse. After the injection of the first set of pulse voltages is completed, an updated second set of pulse voltages is injected. And then, obtaining a positive feedback current peak value and a negative feedback current peak value, and further finishing polarity judgment.

After the first group of positive and negative pulse injection is completed, if the bus voltage is always higher than the threshold voltage, the absolute values of the feedback peak values of the positive and negative currents of the straight shaft can be directly obtained and estimated, and judgment is carried out.

It can be understood that when the bus voltage drops to the threshold voltage during the injection of the positive pulse, or when the bus voltage drops to the threshold voltage during the injection of the negative pulse, even when the bus voltage drops to the threshold voltage during the injection of the positive and negative pulses, the second set of positive and negative pulse injections is performed, and the pulse injection time is updated according to the result of the first set of positive and negative pulse injections (i.e. the duration of the positive pulse voltage and/or the negative pulse voltage in the first set of pulse voltages).

Compared with the electrolytic capacitor controller scheme, the polarity judgment method provided by the embodiment of the invention only needs to determine the threshold voltage threshold additionally, and is simple and easy to implement.

In the above embodiment, the method for updating the injection time of the second group of pulse voltages is shown in fig. 3, and specifically includes:

step 302, adding U_pAnd T_pcProduct of (D) and U_nAnd T_ncComparing the products of (a) and (b);

step 304, based on U_pAnd T_pcIs equal to U_nAnd T_ncThe injection time of the second group of pulse voltages does not need to be updated;

step 306, based on U_pAnd T_pcIs greater than U_nAnd T_ncThe injection time T of the positive pulse voltage in the second group of pulse voltages_p＝U_nT_nc/U_pInjection time T of negative pulse voltage_n＝T_nc；

Step 308, based on U_pAnd T_pcIs less than U_nAnd T_ncThe injection time T of the positive pulse voltage in the second group of pulse voltages_p＝T_pcInjection time T of negative pulse voltage_n＝U_pT_pc/U_n；

Wherein, U_pIs the amplitude, T, of a positive pulse voltage in the first set of pulse voltages_pcIs the duration of a positive pulse voltage, U, of the first set of pulse voltages_nIs the amplitude, T, of the negative pulse voltage in the first set of pulse voltages_ncIs the duration of the negative pulse voltage in the first set of pulse voltages.

In this embodiment, the injection time of the second set of positive and negative pulse voltages is U when the first set of pulse voltages is injected_pT_pc(U_pAnd T_pcProduct of) and U_nT_nc(U_nAnd T_ncProduct of) is determined. If U is present_pT_pcGreater than U_nT_ncInjection time T of the second set of positive pulses_p＝U_nT_nc/U_pInjection time T of the second set of negative pulses_n＝T_nc(ii) a On the contrary, if U_pT_pcLess than U_nT_ncInjection time T of the second set of positive pulses_p＝T_pcInjection time T of the second set of negative pulses_n＝U_pT_pc/U_n. After the second group of positive and negative pulses are injected, the absolute values of the feedback peak values of the positive and negative currents of the estimated straight axis can be obtained, and a polarity judgment result is obtained through judgment.

In any of the above embodiments, the method of injecting the positive pulse voltage is as shown in fig. 4, and specifically includes:

step 402, injecting positive pulse voltage of a first group of pulse voltage into an estimated direct axis of the motor;

step 404, judging whether the duration of the positive pulse voltage injection is longer than the injection time T1; if not, go to step 406, if yes, go to step 410;

step 406, detecting the bus voltage, and judging whether the bus voltage is greater than a threshold voltage; if not, go to step 408, if yes, return to step 402;

step 408, stopping the injection of the positive pulse voltage, and recording the duration T of the positive pulse voltage injection_pc；

In step 410, the injection time T1 of the positive pulse voltage is assigned to the duration T of the positive pulse voltage injection_pc。

In this embodiment, during the injection of the positive pulse voltage, if the bus voltage drops to the threshold voltage, the injection of the positive pulse is stopped, and the duration T of the injection of the positive pulse is recorded_pc(ii) a If the bus voltage is always higher than the threshold voltage, the positive pulse voltage continues to be injected until the injection time reaches the preset injection time T1.

In any of the above embodiments, the method of injecting the negative pulse voltage is as shown in fig. 5, and specifically includes:

step 502, injecting negative pulse voltage of a first group of pulse voltage into an estimated direct axis of the motor;

step 504, judging whether the duration of the injected negative pulse voltage is longer than the injection time T2; if not, go to step 506, if yes, go to step 510;

step 506, detecting the bus voltage, and judging whether the bus voltage is greater than a critical voltage threshold value; if not, go to step 508, if yes, return to step 502;

step 508, stopping the injection of the negative pulse voltage, and recording the duration T of the injection of the negative pulse voltage_nc；

Step 510, assigning the injection time T2 of the negative pulse voltage to the duration T of the negative pulse voltage injection_nc。

In this embodiment, during the injection of the negative pulse voltage, if the bus voltage drops to the threshold voltage, the injection of the negative pulse is stopped, and the duration T of the injection of the negative pulse is recorded_pc(ii) a If the bus voltage is always higher than the threshold voltage, the negative pulse voltage continues to be injected until the injection time reaches the preset injection time T2.

In any of the above embodiments, the threshold voltage is greater than or equal to the bus voltage corresponding to the time when the slope of the estimated direct-axis feedback current begins to decrease.

In this embodiment, a bus voltage value corresponding to an inflection point at which the slope of the feedback current of the estimated direct axis starts to decrease is determined, so as to determine a threshold voltage threshold, where the threshold voltage threshold needs to be greater than or equal to the bus voltage value, and once the threshold voltage threshold is smaller than the bus voltage value corresponding to the inflection point, positive and negative pulses are continuously injected, so that the bus voltage may drop too fast or even be insufficient to provide a control voltage required by a control motor, and the system mistakenly assumes that the bus voltage is not dropped all the time, thereby causing a false determination.

In any of the above embodiments, the step of determining the polarity of the rotor of the motor according to the comparison result specifically includes: estimating the straight axis as a real straight axis based on the condition that the absolute value of the positive feedback current peak value is smaller than the absolute value of the negative feedback current peak value; and based on the condition that the absolute value of the positive feedback current peak value is larger than or equal to the absolute value of the negative feedback current peak value, the direction of the real direct axis is opposite to that of the estimated direct axis.

In this embodiment, when the absolute value of the positive feedback current peak is smaller than the absolute value of the negative feedback current peak, the estimated direct axis is the true direct axis, that is, the magnetic pole direction pointed by the initial position of the motor rotor is the same as the positive direction of the estimated direct axis, and when the absolute value of the positive feedback current peak is greater than or equal to the absolute value of the negative feedback current peak, it indicates that the estimated direct axis is opposite to the true direct axis, that is, the magnetic pole direction pointed by the initial position of the motor rotor is opposite to the positive direction of the estimated direct axis. In a system for controlling a bus capacitor with a small capacitance value of a permanent magnet synchronous motor, when the polarity determination method provided by the invention is used, the method mainly comprises the following steps:

as shown in fig. 6, the curve S1 is a bus voltage, the straight line S2 is a threshold voltage, the curve S3 is a d-axis (i.e., estimated straight axis) command voltage (i.e., pulse voltage), the curve S4 is a d-axis feedback current, and after the positive and negative pulse injection amplitudes are determined, the command voltage is injected to the d-axis through the small-capacitance bus capacitor controller, wherein the capacitance value of the small-capacitance bus capacitor is less than or equal to 10uF, the threshold voltage should be greater than or equal to a bus voltage value corresponding to an inflection point where the slope of the d-axis feedback current starts to decrease, and as shown in fig. 6, an intersection point of the curve S4 and the straight line S5 is the inflection point of the present embodiment.

The method comprises the following steps: as shown in fig. 7 and 8, when a positive pulse voltage is injected into the estimated d-axis (i.e., the estimated direct axis), the pulse amplitude is U_pThe pulse injection time is T_pIf the bus voltage is always higher than the critical voltage threshold value, recording the absolute value I of the feedback peak value of the forward current of the currently estimated d axis at the end moment of injecting the positive pulse voltage_pAnd recording the duration T of the positive pulse voltage injection_pc＝T_p(ii) a If the bus voltage falls to the threshold voltage threshold value in the process of injecting the positive pulse into the estimated d axis, stopping injecting the positive pulse voltage into the estimated d axis, and recording the duration T of injecting the positive pulse voltage_pc。

Step two: as shown in FIGS. 7 and 9, when negative pulses are injected into the estimated d-axis, the pulse amplitude is-U_nThe pulse injection time is T_nIf the bus voltage is always higher than the threshold voltage, recording the absolute value I of the feedback peak value of the current d-axis negative current at the end of injecting the negative pulse_nAnd recording the duration T of the negative pulse injection_nc＝T_n(ii) a If the bus voltage falls to the critical voltage in the process of injecting negative pulse to the estimated d axisStopping injecting negative pulse to the estimated d axis and recording the duration T of the negative pulse_nc。

U_pT_pNeed to be equal to U_nT_nTo ensure the volt-second area balance; and the injection timing of the negative pulse is to ensure that the positive current feedback of the positive pulse has returned to zero.

Step three: as shown in fig. 10, the second positive and negative pulse injection time is from the first pulse injection time U_pT_pcAnd U_nT_ncThe smaller of them. If U is present_pT_pcGreater than U_nT_ncThe injection time Tp of the second positive pulse is equal to U_nT_ncThe injection time Tn of the second negative pulse is Tnc; on the contrary, if U_pT_pcLess than U_nT_ncInjection time T of the second positive pulse_p＝T_pcInjection time T of the second negative pulse_n＝U_pT_pc/U_n. And after the second positive and negative pulse injection, the absolute values of the positive and negative current feedback peak values of the d axis can be obtained, and a polarity judgment result is obtained through judgment.

Step four: as shown in fig. 11, when the polarity determination pulse injection is ended, the polarity determination current feedback absolute value comparison is performed. If the absolute value of the feedback peak value I of the d-axis forward current_pLess than d-axis negative current feedback peak absolute value I_nIf yes, the current estimated d axis is the real d axis; otherwise, the current estimated d-axis is the opposite of the true d-axis.

According to the polarity judgment method provided by the embodiment of the invention, aiming at the condition that the bus falls off in the judgment process of the high-frequency injection polarity of the small-capacitance-value bus capacitor controller, the high-frequency injection polarity judgment of the small-capacitance-value bus capacitor controller of the permanent magnet synchronous motor can be accurately realized through one or two times of positive and negative pulse injection, and the precision is higher; compared with the electrolytic capacitor controller, the method only needs to determine the threshold voltage threshold additionally, and is simple and easy to implement.

In the embodiment of the second aspect of the present invention, a polarity determination apparatus is proposed, and fig. 12 shows a schematic block diagram of a polarity determination apparatus 600 according to the first embodiment of the present invention. The polarity determination apparatus 600 includes:

a memory 602, the memory 602 storing a computer program;

a processor 604, wherein the polarity determination method according to any of the above embodiments is implemented when the processor 604 executes a computer program.

In the polarity determination apparatus 600 according to the embodiment of the present invention, when being executed by the processor 604, the computer program implements the steps of the polarity determination method according to any one of the above embodiments, so that the polarity determination apparatus 600 includes all the beneficial effects of the polarity determination method according to any one of the above embodiments.

In a third embodiment of the present invention, a motor control system is provided, and fig. 13 shows a schematic block diagram of a motor control system 700 according to a first embodiment of the present invention. Wherein, this motor control system 700 includes:

a memory 702, the memory 702 storing a computer program;

a processor 704, wherein the polarity determination method according to any of the above embodiments is implemented when the processor 704 executes a computer program.

In the motor control system 700 provided by the embodiment of the present invention, when the computer program is executed by the processor 704, the steps of the polarity determination method according to any one of the above embodiments are implemented, so that the motor control system 700 includes all the beneficial effects of the polarity determination method according to any one of the above embodiments.

In the above embodiment, the motor control system 700 further includes: and the bus capacitance control device is used for injecting at most two groups of pulse signals into the estimated direct axis of the motor.

In any of the above embodiments, the capacitance value range of the bus capacitor used by the bus capacitor control device is as follows: greater than 0 and less than or equal to 10 uF.

In the embodiment, after the amplitude of the first group of positive and negative pulse voltages is determined, the positive and negative pulse voltages are injected into the estimation direct axis through the bus capacitor controller with a small capacitance value, in the process of injecting the positive and negative pulse voltages, the bus voltages are collected, including the bus voltages collected in real time or at fixed time intervals, and whether the injection of the positive and negative pulse voltages needs to be carried out again and the injection time of the pulse positive and negative pulse voltages needs to be updated is judged through the comparison between the bus voltages and the threshold voltage; and finally, obtaining a polarity judgment result according to the comparison of the absolute value of the positive current feedback peak value and the absolute value of the negative current feedback peak value. The motor control system provided by the invention can accurately realize the judgment of the high-frequency injection polarity of the small-capacitance value bus capacitor controller of the permanent magnet synchronous motor by injecting positive and negative pulses once or twice aiming at the condition that the bus falls off in the judgment process of the high-frequency injection polarity of the small-capacitance value bus capacitor controller.

According to a fourth aspect of the present invention, there is provided a computer-readable storage medium, on which a computer program is stored, the computer program, when executed by a processor, implementing the polarity determination method according to any one of the above embodiments.

The present invention provides a computer-readable storage medium, wherein a computer program is executed by a processor to implement the steps of the polarity determination method according to any of the above embodiments, and therefore the computer-readable storage medium includes all the advantages of the polarity determination method according to any of the above embodiments.

In the description herein, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance unless explicitly stated or limited otherwise; the terms "connected," "mounted," "secured," and the like are to be construed broadly and include, for example, fixed connections, removable connections, or integral connections; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the description herein, the description of the terms "one embodiment," "some embodiments," "specific embodiments," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.