Motor control method and motor control circuit

Abstract

This application provides a motor control method and a motor control circuit. The motor control method includes: acquiring the d-axis voltage and q-axis voltage of the motor in a two-phase rotating coordinate system; if the motor rotor is in a low modulation region and the q-axis voltage is within a set prohibited range of the q-axis region, optimizing the q-axis voltage to generate an optimized q-axis voltage, the optimized q-axis voltage being equal to the boundary value of the prohibited range of the q-axis region with the same positive and negative sign as the q-axis voltage, the boundary value including an upper boundary value and a lower boundary value; and generating a PWM pulse signal for controlling the motor based on the d-axis voltage and the optimized q-axis voltage. By increasing the absolute value of the q-axis voltage, which is relatively small when the motor rotor is in the low modulation region, the width of the generated PWM pulse signal can be increased, thereby satisfying the minimum time window for current sampling, avoiding motor start-up failure or abnormal stop, and improving the stability of motor operation.

Description

Technical Field

[0001] This application relates to the field of motor control technology, and in particular to a motor control method and a motor control circuit. Background Technology

[0002] In sensorless FOC control systems for motors, current sampling is a crucial component. Current sampling includes single-resistor sampling, dual-resistor sampling, and three-resistor sampling. Single-resistor sampling is the preferred choice due to its simple circuitry, requiring only one sampling resistor, and is often chosen when cost is a concern or PCB space is limited. However, single-resistor sampling requires two samplings within a single sampling period to reconstruct the three-phase current, resulting in an unobservable region. If the minimum time window is not met, the sampling results will be erroneous.

[0003] In related technologies, to address the sampling problem in the unobservable region, a phase-shifting method is used to shift the phase of the PWM pulse signal so that the phase-shifted PWM pulse signal meets the minimum time window. However, when the motor uses the direct back EMF method for closed-loop starting, the current value is very small, resulting in a very small width of the generated PWM pulse signal. Even with phase shifting, the minimum time window required for sampling cannot be met, leading to inaccurate sampling. Incorrect current values ​​generate incorrect voltage values ​​in the closed-loop control, which in turn generate incorrect pulse signals, causing motor start-up failure or abnormal stop. Summary of the Invention

[0004] This application provides a motor control method and a motor control circuit to solve at least some of the problems in the related art.

[0005] This application provides a motor control method, including:

[0006] Obtain the d-axis and q-axis voltages of the motor in a two-phase rotating coordinate system;

[0007] If the rotor of the motor is in the low modulation region and the q-axis voltage is within the set prohibited range of the q-axis region, the q-axis voltage is optimized to generate an optimized q-axis voltage. The optimized q-axis voltage is equal to the boundary value of the prohibited range of the q-axis region that has the same sign as the q-axis voltage. The boundary value includes an upper boundary value and a lower boundary value.

[0008] Based on the d-axis voltage and the q-axis optimized voltage, a PWM pulse signal for controlling the motor is generated.

[0009] Optionally, if the rotor of the motor is in the low modulation region and the q-axis voltage is within a set prohibited range of the q-axis region, optimizing the q-axis voltage to generate an optimized q-axis voltage includes:

[0010] If the absolute value of the vector sum of the d-axis voltage and the q-axis voltage is less than the set low modulation region threshold, and the q-axis voltage is within the prohibited range of the q-axis region, the q-axis voltage is optimized to generate an optimized q-axis voltage.

[0011] Optionally, the control method further includes: if the rotor of the motor is in the low modulation region and the d-axis voltage is within the set prohibited range of the d-axis region, optimizing the d-axis voltage to generate an optimized d-axis voltage, wherein the optimized d-axis voltage is equal to the boundary value of the prohibited range of the d-axis region that has the same positive and negative sign as the d-axis voltage, and the boundary value includes an upper boundary value and a lower boundary value.

[0012] Optionally, after optimizing the d-axis voltage to generate an optimized d-axis voltage when the motor rotor is in the low modulation region and the d-axis voltage is within a set prohibited range of the d-axis region, the method further includes:

[0013] The d-axis optimized voltage is constrained by a limit circle to generate the d-axis target voltage;

[0014] The PWM pulse signal is generated based on the target voltage along the d-axis.

[0015] Optionally, after optimizing the q-axis voltage to generate an optimized q-axis voltage when the motor rotor is in the low modulation region and the q-axis voltage is within a set prohibited range for the q-axis region, the method further includes:

[0016] The q-axis optimized voltage is subjected to limit circle constraint to generate the q-axis target voltage;

[0017] The PWM pulse signal is generated based on the target voltage along the q-axis.

[0018] Optionally, the method further includes:

[0019] If the rotor of the motor is in the low modulation region and the q-axis voltage is not within the prohibited range of the q-axis region, the q-axis voltage is subject to limit circle limitation to generate the q-axis target voltage;

[0020] The PWM pulse signal is generated based on the target voltage along the q-axis; and / or

[0021] If the rotor of the motor is in the low modulation region and the d-axis voltage is not within the prohibited range of the d-axis region, the d-axis voltage is subject to limit circle limitation to generate the d-axis target voltage;

[0022] The PWM pulse signal is generated based on the target voltage along the d-axis.

[0023] Optionally, the method further includes:

[0024] If the rotor of the motor is not in the low modulation region, the d-axis voltage and the q-axis voltage are subject to limit circle constraints to generate target q-axis voltage and target d-axis voltage, and the PWM pulse signal is generated based on the target q-axis voltage and target d-axis voltage.

[0025] Optionally, the q-axis optimized voltage is equal to the boundary value of the prohibited range of the q-axis region that has the same sign as the q-axis voltage. The boundary value includes an upper boundary value and a lower boundary value, wherein the absolute values ​​of the upper boundary value and the lower boundary value are equal or unequal.

[0026] Another aspect of this application provides a motor control circuit, the motor control circuit comprising:

[0027] The voltage acquisition unit is used to acquire the d-axis voltage and q-axis voltage of the motor in a two-phase rotating coordinate system.

[0028] A voltage region prohibition unit, connected to the voltage acquisition unit, is used to optimize the q-axis voltage if the motor rotor is in a low modulation region and the q-axis voltage is within a set q-axis region prohibition range, generating an optimized q-axis voltage. The optimized q-axis voltage is equal to a boundary value of the q-axis region prohibition range that has the same sign as the q-axis voltage, and the boundary value includes an upper boundary value and a lower boundary value.

[0029] The signal generation unit, connected to the voltage region disable unit, is used to generate a PWM pulse signal for controlling the motor based on the d-axis voltage and the q-axis optimized voltage.

[0030] Optionally, the voltage region disable unit is used for:

[0031] If the absolute value of the vector sum of the d-axis voltage and the q-axis voltage is less than the set low modulation region threshold, and the q-axis voltage is within the prohibited range of the q-axis region, the q-axis voltage is optimized to generate an optimized q-axis voltage.

[0032] Optionally, the voltage region inhibiting unit is further configured to:

[0033] If the rotor of the motor is in the low modulation region and the d-axis voltage is within the set prohibited range of the d-axis region, the d-axis voltage is optimized to generate an optimized d-axis voltage. The optimized d-axis voltage is equal to the boundary value of the prohibited range of the d-axis region that has the same positive and negative sign as the d-axis voltage. The boundary value includes an upper boundary value and a lower boundary value.

[0034] The motor control method provided in this application optimizes the q-axis voltage when the motor rotor is in the low modulation region and the q-axis voltage is within a set prohibited range of the q-axis region. This generates an optimized q-axis voltage, which is equal to the boundary value of the prohibited range of the q-axis region, sharing the same positive and negative sign as the q-axis voltage. This boundary value includes both an upper and lower boundary value. The absolute value of the q-axis voltage, which is relatively small when the motor rotor is in the low modulation region, can be increased. Therefore, when generating the PWM pulse signal for controlling the motor based on the optimized q-axis voltage, the width of the generated PWM pulse signal can be increased, thereby satisfying the minimum time window for current sampling. This avoids motor start-up failure or abnormal stoppage caused by not meeting the minimum sampling time window, improving the stability of motor operation. Attached Figure Description

[0035] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0036] Figure 1 This is a block diagram illustrating the principle of motor control in related technologies;

[0037] Figure 2 This is a schematic flowchart illustrating a motor control method in one embodiment;

[0038] Figure 3 This is a schematic diagram of the q-axis voltage before optimization.

[0039] Figure 4 This is a schematic diagram of the optimized q-axis voltage;

[0040] Figure 5 This is a flowchart illustrating a motor control method according to another embodiment;

[0041] Figure 6 This is a flowchart illustrating a motor control method in another embodiment;

[0042] Figure 7 This is a schematic diagram of the motor control method in another embodiment;

[0043] Figure 8 This is a schematic block diagram of a motor control circuit according to one embodiment;

[0044] Figure 9 This is a schematic block diagram of a motor control circuit according to another embodiment;

[0045] Figure 10 This is a circuit diagram of a motor control circuit as shown in one embodiment;

[0046] Figure 11 This is a circuit diagram of a motor control circuit shown in another embodiment.

[0047] Figure reference numerals: 2. Motor control circuit; 3. Voltage acquisition unit; 4. Voltage region prohibition unit; 5. Signal generation unit; 6. Voltage judgment module; 7. First switch module; 8. Voltage optimization module; 9. Vector synthesizer; 10. First comparator; 11. First gating device; 12. First gating device; 13. Filter; 14. Limit circle protection unit; 15. Limit circle upper boundary protection module; 16. Limit circle lower boundary protection module; 17. Positive / negative judgment module; 18. Second switch module; 19. Positive voltage optimizer; 10. Negative voltage optimizer; 10. Second comparator; 11. Second gating device; 12. Third comparator; 13. Third gating device; 14. Third gating device; 15. q-axis voltage optimization module; 16. d-axis voltage optimization module. Detailed Implementation

[0048] This application provides a motor control method and a motor control circuit. The motor control method and motor control circuit of this application will be described in detail below with reference to the accompanying drawings. Unless otherwise specified, the features of the following embodiments and implementations can be combined with each other.

[0049] One embodiment of this application provides a motor control method, including:

[0050] Obtain the d-axis and q-axis voltages of the motor in a two-phase rotating coordinate system;

[0051] If the motor rotor is in the low modulation region and the q-axis voltage is within the set prohibited range of the q-axis region, the q-axis voltage is optimized to generate the q-axis optimized voltage. The q-axis optimized voltage is equal to the boundary value of the prohibited range of the q-axis region that has the same positive and negative sign as the q-axis voltage. The boundary value includes the upper boundary value and the lower boundary value.

[0052] Based on the d-axis voltage and the q-axis optimized voltage, a PWM pulse signal is generated to control the motor.

[0053] The motor control method provided in this application optimizes the q-axis voltage when the motor rotor is in the low modulation region and the q-axis voltage is within a set prohibited range of the q-axis region. This generates an optimized q-axis voltage, which is equal to the boundary value of the prohibited range of the q-axis region, sharing the same positive and negative sign as the q-axis voltage. This boundary value includes both an upper and lower boundary value. The absolute value of the q-axis voltage, which is relatively small when the motor rotor is in the low modulation region, can be increased. Therefore, when generating the PWM pulse signal for controlling the motor based on the optimized q-axis voltage, the width of the generated PWM pulse signal can be increased, thereby satisfying the minimum time window for current sampling. This avoids motor start-up failure or abnormal stoppage caused by not meeting the minimum sampling time window, improving the stability of motor operation.

[0054] Please refer to Figure 1 , Figure 1 This is a block diagram illustrating the principle of motor control in related technologies, such as... Figure 1As shown, under the control of sampling trigger and interrupt trigger signals, the sampling unit collects the phase current of the motor. The CPU unit writes the collected phase current into the system. The collected phase current is the current in the three-phase stationary coordinate system. The current in the three-phase stationary coordinate system is converted into a current IdIq in the two-phase rotating coordinate system by the Clark-Park transformation unit. The current IdIq in the two-phase rotating coordinate system is then converted into a voltage UdUq in the two-phase rotating coordinate system by the PI loop regulation unit. The voltage in the two-phase rotating coordinate system is then converted into a three-phase voltage UuUvUw in the three-phase stationary coordinate system by the inverse Park-inverse Clark transformation unit. The PWM generation unit generates a PWM pulse signal based on the three-phase voltage and controls the motor through the PWM pulse signal. During the coordinate transformation process, the angle estimation unit estimates the rotation angle of the motor rotor and provides it to the Clark-Park transformation unit and the inverse Park-inverse Clark transformation unit, providing angle parameters for the coordinate transformation.

[0055] When the sampling unit is a single-resistor sampling unit, two samples are required within one sampling period to reconstruct the three-phase current. If the minimum time window is not met, the sampling result will be incorrect. Furthermore, when the motor uses the direct back EMF method for closed-loop starting, the current value is very small, resulting in a very small width of the generated PWM pulse signal. Even with phase shifting, the minimum time window required for sampling cannot be met, leading to inaccurate sampling. Incorrect current values ​​generate incorrect voltage values ​​in the closed-loop control, which in turn generate incorrect pulse signals, causing the motor to fail to start or stop abnormally.

[0056] Please refer to Figure 2 , Figure 2 This is a flowchart illustrating a motor control method according to one embodiment. Figure 2 As shown, motor control method 1 includes steps 10 to 30.

[0057] Step 10: Obtain the d-axis voltage and q-axis voltage of the motor in a two-phase rotating coordinate system.

[0058] In some embodiments, acquiring the d-axis and q-axis voltages of the motor in a two-phase rotating coordinate system includes acquiring and reconstructing the three-phase currents of the motor, performing coordinate transformation on the three-phase currents, first converting them to currents in a two-phase stationary coordinate system and then to currents in a two-phase rotating coordinate system. The currents in the two-phase rotating coordinate system are input to an adjustment unit, which compares the currents in the two-phase rotating coordinate system with the target current and outputs the voltages in the two-phase rotating coordinate system, which are the d-axis and q-axis voltages of the motor in the two-phase rotating coordinate system.

[0059] Step 20: If the motor rotor is in the low modulation region and the q-axis voltage is within the set prohibited range of the q-axis region, optimize the q-axis voltage to generate an optimized q-axis voltage. The optimized q-axis voltage is equal to the boundary value of the prohibited range of the q-axis region that has the same positive and negative sign as the q-axis voltage. The boundary value includes the upper boundary value and the lower boundary value.

[0060] Step 30: Generate a PWM pulse signal for controlling the motor based on the d-axis voltage and the q-axis optimized voltage.

[0061] Please refer to Figure 3 and Figure 4 , Figure 3 This is a schematic diagram of the q-axis voltage before optimization. Figure 4 This is a schematic diagram of the optimized q-axis voltage. From... Figure 3 and Figure 4 It can be seen that the absolute value of the q-axis voltage, which has a small absolute value, can be increased. Therefore, when generating the PWM pulse signal for controlling the motor based on the optimized q-axis and d-axis voltages, the width of the generated PWM pulse signal can be increased, thereby satisfying the minimum time window for current sampling. This avoids motor start-up failure or abnormal stoppage caused by not meeting the minimum sampling time window, thus improving the stability of motor operation.

[0062] exist Figure 2 In the embodiment shown, the q-axis voltage is optimized only when the motor rotor is in the low modulation region and the q-axis voltage is within the set prohibited range of the q-axis region, generating an optimized q-axis voltage. The d-axis voltage is not optimized.

[0063] In this embodiment, if the motor rotor is in the low modulation region and the q-axis voltage is within the set prohibited range of the q-axis region in step 20, the q-axis voltage is optimized to generate an optimized q-axis voltage, including:

[0064] If the absolute value of the vector sum of the d-axis voltage and the q-axis voltage is less than the set low modulation region threshold, and the q-axis voltage is within the prohibited range of the q-axis region, the q-axis voltage is optimized to generate an optimized q-axis voltage.

[0065] Understandably, if the absolute value of the vector sum of the d-axis voltage and the q-axis voltage is less than the set low modulation zone threshold, it indicates that the vector sum of the voltage in the two-phase rotating coordinate system is too small. Consequently, the voltage converted to the two-phase stationary coordinate system is also too small, located near the center of the two-phase stationary coordinate system. The length of the non-zero vector used to synthesize this voltage is also too small, ultimately resulting in an excessively small width of the generated PWM pulse.

[0066] Using the absolute value of the vector sum of the d-axis voltage and the q-axis voltage being less than the set low modulation zone threshold as the criterion for determining whether the motor rotor is in the low modulation zone, can not only accurately determine whether the motor rotor is in the low modulation zone, but also, because the voltage in the two-phase rotating coordinate system has fewer parameters than the voltage in the two-phase stationary coordinate system and the voltage in the three-phase stationary coordinate system, and the coordinate system in which the parameters are located is stationary relative to the rotor, it is convenient for data acquisition and control.

[0067] In some embodiments, the q-axis optimized voltage is equal to a boundary value of the prohibited range of the q-axis region that has the same sign as the q-axis voltage. This boundary value includes an upper boundary value and a lower boundary value, where the absolute values ​​of the upper and lower boundary values ​​are equal, i.e., symmetrical about the voltage 0 axis. In another embodiment, the absolute values ​​of the upper and lower boundary values ​​are not equal, and there is no symmetrical setting about the voltage 0 axis.

[0068] In single-resistor sampling, the current of two phases is first acquired, and then the three-phase current is reconstructed based on the principle that the vector sum of the three-phase currents is zero. If the current acquisition is inaccurate, the reconstructed three-phase current will show negative values, and the voltage generated after coordinate transformation and PI regulation will also be negative. Therefore, the restricted area includes an upper and lower boundary, encompassing small positive voltages, small negative voltages, and even zero voltage. The setting of the restricted area should be tailored to the specific scenario. While ensuring the motor's starting success rate and smoothness, the width of the restricted area should be minimized to avoid excessive intervention. While meeting the minimum time window required for sampling, excessive intervention can distort the acquired current values. The restricted area should strike a balance between meeting sampling requirements and ensuring accurate current data.

[0069] Please refer to Figure 5 , Figure 5 This is a flowchart illustrating a motor control method according to another embodiment. Figure 5 In the embodiment shown, the motor control method 1 further includes steps 20, 21 and 31.

[0070] Step 20: If the motor rotor is in the low modulation region and the q-axis voltage is within the set prohibited range of the q-axis region, optimize the q-axis voltage to generate an optimized q-axis voltage. The optimized q-axis voltage is equal to the boundary value of the prohibited range of the q-axis region that has the same positive and negative sign as the q-axis voltage. The boundary value includes the upper boundary value and the lower boundary value.

[0071] Step 21: If the motor rotor is in the low modulation zone and the d-axis voltage is within the set prohibited range of the d-axis region, optimize the d-axis voltage to generate the d-axis optimized voltage. The d-axis optimized voltage is equal to the boundary value of the prohibited range of the d-axis region that has the same positive and negative sign as the d-axis voltage. The boundary value includes the upper boundary value and the lower boundary value.

[0072] Step 31: Generate PWM pulse signals for controlling the motor based on the d-axis optimized voltage and the q-axis optimized voltage.

[0073] Step 21 is used to optimize the q-axis voltage, and step 22 is used to optimize the d-axis voltage. Steps 21 and 22 can be performed simultaneously or sequentially, and there is no restriction on the order of steps 21 and 22.

[0074] exist Figure 5 In the illustrated embodiment, both the q-axis voltage and the d-axis voltage were optimized using steps 21 and 22. When the motor rotor is in the low modulation region, the absolute values ​​of both the q-axis and d-axis voltages, which were initially small, were increased. This allows for a wider PWM pulse signal to be generated for controlling the motor based on the optimized q-axis voltage and the optimized d-axis voltage.

[0075] exist Figure 1 In the illustrated embodiment, if the motor rotor is in the low modulation region and the q-axis voltage is within the set prohibited range of the q-axis region, the q-axis voltage is optimized to generate an optimized q-axis voltage. The optimized q-axis voltage is equal to the boundary value of the prohibited range of the q-axis region that has the same positive and negative sign as the q-axis voltage. The boundary value includes the upper boundary value and the lower boundary value. When the motor rotor is in the low modulation region, the absolute value of the q-axis voltage, which has a smaller absolute value, is increased, but the absolute value of the d-axis voltage, which also has a smaller absolute value, is not increased.

[0076] In motor control, the q-axis voltage is directly related to the motor's torque output. The q-axis voltage is used to regulate the torque generated by the motor, affecting its acceleration and load capacity. Increasing the q-axis voltage also increases the width of the generated PWM pulse signal. The d-axis voltage is typically proportional to the motor's magnetic flux or excitation. The d-axis voltage is used to control the motor's magnetic field strength. Controlling the d-axis voltage helps maintain the motor in a certain operating state, ensuring that it does not fluctuate excessively when the load changes.

[0077] Therefore, the width of the generated PWM pulse signal can be increased by either increasing the absolute values ​​of the q-axis and d-axis voltages, which have relatively small absolute values, or by increasing only the absolute value of the q-axis voltage, which has a smaller absolute value. This increases the width of the generated PWM pulse signal while preventing fluctuations in the motor's operating state. The specific choice can be made based on the actual operating conditions of the motor and the motor control requirements.

[0078] exist Figure 5 In the illustrated embodiment, when optimizing the q-axis and d-axis voltages, the prohibited areas of the d-axis and q-axis regions can be the same or different. Depending on the specific scenario, the width of the prohibited areas can be minimized as much as possible while ensuring the motor's start-up success rate and smoothness.

[0079] Please refer to Figure 6 , Figure 6 This is a flowchart illustrating a motor control method in another embodiment. Figure 6 The illustrated embodiments and Figure 2 The illustrated embodiments are essentially the same. The difference lies in that... Figure 6 In the illustrated embodiment, if the motor rotor is in the low modulation region and the q-axis voltage is within the set prohibited range of the q-axis region in step 20, the q-axis voltage is optimized to generate the optimized q-axis voltage. After this step, the motor control method 1 further includes step 40, which limits the optimized q-axis voltage to a limit circle to generate the target q-axis voltage.

[0080] Step 30 generates a PWM pulse signal for controlling the motor based on the d-axis voltage and the q-axis optimized voltage, including generating the PWM pulse signal based on the q-axis target voltage.

[0081] Limiting the q-axis optimized voltage with a limiting circle prevents the motor rotor from entering the over-modulation region due to excessive q-axis voltage. The over-modulation region refers to the state where the motor's output voltage exceeds its rated modulation range. In the over-modulation region, the motor cannot continue to increase torque at the expected rate, leading to a non-linear torque response. This causes the torque output to no longer be linearly related to the input voltage, making precise motor control difficult. Therefore, in this embodiment, by limiting the q-axis optimized voltage with a limiting circle to generate a target q-axis voltage, and generating a PWM pulse signal based on the target q-axis voltage, the control accuracy of the motor can be improved.

[0082] Please refer to Figure 7 , Figure 7 This is a schematic flowchart illustrating a motor control method in yet another embodiment. Figure 7 In the embodiment shown, if the motor rotor is in the low modulation region and the d-axis voltage is within the set prohibited range of the d-axis region in step 21, the d-axis voltage is optimized to generate the d-axis optimized voltage. The motor control method further includes steps 41 and 32.

[0083] Step 41: Apply limit circle constraints to the d-axis optimized voltage to generate the d-axis target voltage;

[0084] Step 32: Generate PWM pulse signals for controlling the motor based on the target voltage of the q-axis and the target voltage of the d-axis.

[0085] In some embodiments, the motor control method further includes:

[0086] If the motor rotor is in the low modulation region and the q-axis voltage is not within the prohibited range of the q-axis region, the q-axis voltage is limited by a limit circle to generate the q-axis target voltage; a PWM pulse signal is generated based on the q-axis target voltage.

[0087] Thus, if the motor rotor is in the low modulation region, when the q-axis voltage is within the prohibited range of the q-axis region, its absolute value is increased; when the q-axis voltage is not within the prohibited range of the q-axis region, its absolute value is not increased, and the q-axis voltage is directly limited by the limit circle to generate the q-axis target voltage. The PWM pulse signal is then generated based on the q-axis target voltage.

[0088] In other embodiments, the motor control method further includes: if the motor rotor is in the low modulation region and the d-axis voltage is not within the prohibited range of the d-axis region, limiting the d-axis voltage by a limit circle to generate a d-axis target voltage; and generating a PWM pulse signal based on the d-axis target voltage.

[0089] Thus, if the motor rotor is in the low modulation region, when the d-axis voltage is within the prohibited range of the d-axis region, its absolute value is increased; when the d-axis voltage is not within the prohibited range of the d-axis region, its absolute value is not increased, and the d-axis voltage is directly limited by the limit circle to generate the d-axis target voltage. The PWM pulse signal is then generated based on the d-axis target voltage.

[0090] In some other embodiments, the motor control method further includes: if the rotor of the motor is not in the low modulation region, limiting the d-axis voltage and q-axis voltage by a limit circle, generating a target q-axis voltage and a target d-axis voltage, and generating a PWM pulse signal based on the target q-axis voltage and the target d-axis voltage.

[0091] Thus, if the motor rotor is not in the low modulation region, the PWM pulse signal generated based on the d-axis voltage and the optimized q-axis voltage has a relatively wide width, which can generally meet the minimum sampling time window. Even if the minimum time window is not met, it can generally be solved by phase shifting. Therefore, there is no need to judge whether the q-axis voltage is within the prohibited range of the q-axis region or whether the d-axis voltage is within the prohibited range of the d-axis region. Limit circle protection can be directly applied to the d-axis voltage and the q-axis voltage to prevent the rotor from entering the over-modulation region.

[0092] This application also provides a motor control circuit, please refer to... Figure 8 , Figure 8 This is a schematic block diagram of a motor control circuit according to one embodiment. Figure 8 In the embodiment shown, the motor control circuit 2 includes a voltage acquisition unit 3, a voltage region prohibition unit 4, and a signal generation unit 5.

[0093] Voltage acquisition unit 3 is used to acquire the d-axis voltage and q-axis voltage of the motor in a two-phase rotating coordinate system.

[0094] The voltage region prohibition unit 4 is connected to the voltage acquisition unit 3. It is used to optimize the q-axis voltage if the rotor of the motor is in the low modulation region and the q-axis voltage is within the set q-axis region prohibition range, and generate a q-axis optimized voltage. The q-axis optimized voltage is equal to the boundary value of the q-axis region prohibition range that has the same positive and negative sign as the q-axis voltage. The boundary value includes an upper boundary value and a lower boundary value.

[0095] The signal generation unit 5, connected to the voltage region inhibit unit 4, is used to generate a PWM pulse signal for controlling the motor based on the d-axis voltage and the q-axis optimized voltage.

[0096] The motor control circuit 2 provided in this application includes a voltage region prohibition unit 4. This unit 4 optimizes the q-axis voltage when the motor rotor is in a low modulation region and the q-axis voltage is within a set q-axis region prohibition range, generating an optimized q-axis voltage. This optimized q-axis voltage is equal to a boundary value of the q-axis region prohibition range that has the same positive and negative sign as the q-axis voltage. This boundary value includes an upper boundary value and a lower boundary value. This allows for an increase in the absolute value of the q-axis voltage when the motor rotor is in the low modulation region and its absolute value is small. Thus, when generating a PWM pulse signal for controlling the motor based on the optimized q-axis voltage, the width of the generated PWM pulse signal can be increased, thereby satisfying the minimum time window for current sampling. This avoids motor start-up failure or abnormal stoppage due to not meeting the minimum sampling time window, improving the stability of motor operation.

[0097] In some embodiments, the voltage region prohibition unit 4 is used to: optimize the q-axis voltage and generate an optimized q-axis voltage if the absolute value of the vector sum of the d-axis voltage and the q-axis voltage is less than a set low modulation region threshold, and the q-axis voltage is within the q-axis region prohibition range. Thus, using the absolute value of the vector sum of the d-axis voltage and the q-axis voltage being less than a set low modulation region threshold as the criterion for determining whether the motor rotor is in the low modulation region not only accurately determines whether the motor rotor is in the low modulation region, but also, because the voltage in the two-phase rotating coordinate system is closer to linear than the voltage in the two-phase stationary coordinate system and the voltage in the three-phase stationary coordinate system, voltage control can be represented by a simple DC value, resulting in a simple control algorithm.

[0098] In some embodiments, the voltage region prohibition unit 4 is further configured to: if the rotor of the motor is in a low modulation region and the d-axis voltage is within a set d-axis region prohibition range, optimize the d-axis voltage to generate an optimized d-axis voltage. The optimized d-axis voltage is equal to a boundary value of the d-axis region prohibition range that has the same positive and negative sign as the d-axis voltage, and the boundary value includes an upper boundary value and a lower boundary value. Thus, when the rotor of the motor is in a low modulation region, the absolute values ​​of both the q-axis voltage and the d-axis voltage, which have relatively small absolute values, are increased. When generating a PWM pulse signal for controlling the motor based on the optimized q-axis voltage and the optimized d-axis voltage, the width of the generated PWM pulse signal can be increased.

[0099] Please refer to Figure 9 , Figure 9 This is a schematic block diagram of motor control circuit 2 shown in another embodiment. Figure 9 In the illustrated embodiment, the voltage region prohibition unit 4 includes a voltage judgment module 6, a first switch module 7, and a voltage optimization module 8. The voltage judgment module 6 is connected to the voltage acquisition unit 3. The voltage acquisition unit 3 is connected to the voltage optimization module 8 and the signal generation unit 5 through the first switch module 7. The voltage optimization module 8 is connected to the signal generation module. The voltage judgment module 6 is used to determine whether the motor rotor is in the low modulation region. The voltage optimization module 8 is used to generate a q-axis optimized voltage based on the q-axis voltage. The voltage judgment module 6 is connected to the first switch module 7 and is used for:

[0100] If the motor rotor is in the low modulation region, the first switch module 7 connects the voltage acquisition unit 3 and the voltage optimization module 8, and disconnects the voltage acquisition unit 3 and the signal generation unit 5. If the motor rotor is not in the low modulation region, the first switch module 7 connects the voltage acquisition unit 3 and the signal generation unit 5, and disconnects the voltage acquisition unit 3 and the voltage optimization module 8. Thus, by setting the voltage judgment module 6 and the first switch module 7, it is possible to determine whether to optimize the q-axis voltage within the prohibited range of the q-axis region based on whether the motor rotor is in the low modulation region.

[0101] Please refer to Figure 10 , Figure 10 Here is a circuit diagram of motor control circuit 2 as shown in one embodiment. Figure 10In the illustrated embodiment, the voltage judgment module 6 includes a vector synthesizer 61 and a first comparator 62 connected to the vector synthesizer 61. The vector synthesizer 61 is connected to the voltage acquisition unit 3 and is used to calculate the vector sum of the d-axis voltage and the q-axis voltage. The first comparator 62 is used to compare the vector sum with a preset low modulation region threshold value. The first comparator 62 is connected to the first switch module 7 and is used to: if the absolute value of the vector sum is less than the low modulation region threshold value, control the first switch module 7 to connect the voltage acquisition unit 3 and the voltage optimization module 8; if the absolute value of the vector sum is not less than the low modulation region threshold value, control the first switch module 7 to connect the voltage acquisition unit 3 and the signal generation unit 5. The voltage judgment module 6 also includes a filter 64, used to filter the q-axis voltage and d-axis voltage acquired by the voltage acquisition unit 3.

[0102] exist Figure 10 In the embodiment shown, a limit circle protection unit 9 is connected between the voltage acquisition unit 3 and the signal generation unit 5, and a limit circle protection unit 9 is also connected between the voltage optimization unit and the signal generation unit 5. The limit circle protection unit 9 is used to perform limit circle protection on the d-axis voltage, q-axis voltage, or d-axis voltage and q-axis optimized voltage to prevent the rotor from entering the high modulation region.

[0103] The limit circle protection unit 9 includes a limit circle upper boundary protection module 91 and a limit circle lower boundary protection module 92. The upper boundary protection module 91 is used for limit circle protection of the q-voltage and the q-axis optimized voltage, while the lower boundary protection module 92 is used for protection of the d-axis voltage. This is because when the rotor is in the high modulation region, the q-axis voltage or the q-axis optimized voltage is positive, so only upper boundary protection is required; conversely, the d-axis voltage or the d-axis optimized voltage is negative, so only lower boundary protection is required.

[0104] exist Figure 10 In the embodiment shown, the voltage judgment module 6 further includes a first selector 63, which is connected between the first comparator 62 and the first switch module 7. The first selector 63 is used to output different selection signals according to the comparison result of the first comparator 62, and control the on / off state of the first switch module 7 according to the selection signals.

[0105] exist Figure 10In the illustrated embodiment, the voltage optimization module 8 includes a positive / negative judgment module 81, a second switch module 82, a positive voltage optimizer 83, and a negative voltage optimizer 84. The positive / negative judgment module 81 is connected to the first switch module 7 and is used to determine the sign of the q-axis voltage. The first switch module 7 is connected to the positive voltage optimizer 83 and the negative voltage optimizer 84 through the second switch module 82. The positive / negative judgment module 81 and the second switch module 82 are connected for the following purposes: If the q-axis voltage is positive, the second switch module 82 is controlled to connect the first switch module 7 and the positive voltage optimizer 83, and the positive voltage optimizer 83 is used to optimize positive voltages within the prohibited area to the upper boundary value. If the q-axis voltage is negative, the second switch module 82 is controlled to connect the first switch module 7 and the negative voltage optimizer 84, and the negative voltage optimizer 84 is used to optimize negative voltages within the prohibited area to the lower boundary value.

[0106] exist Figure 10 In the embodiment shown, the positive voltage optimizer 83 includes a second comparator 831 and a second selector 832 connected to the second comparator 831. The second comparator 831 is connected to the second switch module 82. The second comparator 831 is used to compare the q-axis voltage and the upper boundary value, and controls the second selector 832 to output the maximum value of the q-axis voltage and the upper boundary value as the optimized q-axis voltage.

[0107] The negative voltage comparator includes a third comparator 841 and a third selector 842 connected to the third comparator 841. The third comparator 841 is connected to the second switch module 82. The third comparator 841 is used to compare the q-axis voltage and the lower boundary value, and controls the third selector 842 to output the value with the largest absolute value between the q-axis voltage and the lower boundary value as the optimized q-axis voltage.

[0108] Please refer to Figure 11 , Figure 11 Here is a circuit diagram of motor control circuit 2 as shown in another embodiment. Figure 11 The illustrated embodiments and Figure 10 The illustrated embodiments are essentially the same. The difference lies in that... Figure 11 In the illustrated embodiment, there are two voltage optimization modules 8: a q-axis voltage optimization module 85 and a d-axis voltage optimization module 86. The voltage acquisition unit 3 is connected to the q-axis voltage optimization module 85, the d-axis voltage optimization module 86, and the signal generation unit 5 via a first switch module 7. Both the q-axis voltage optimization module 85 and the d-axis voltage optimization module 86 are connected to the signal generation unit 5. The q-axis voltage optimization module 85 is used to optimize the q-axis voltage within the prohibited range of the q-axis region, and the d-axis voltage optimization module 86 is used to optimize the d-axis voltage within the prohibited range of the d-axis region. The signal generation unit 5 is used to generate PWM pulse signals based on the optimized q-axis voltage and the optimized d-axis voltage.

[0109] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the application disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the following claims.

[0110] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A motor control method, characterized in that, include: Obtain the d-axis and q-axis voltages of the motor in a two-phase rotating coordinate system; If the rotor of the motor is in the low modulation region and the q-axis voltage is within the set prohibited range of the q-axis region, the q-axis voltage is optimized to generate an optimized q-axis voltage. The optimized q-axis voltage is equal to the boundary value of the prohibited range of the q-axis region that has the same sign as the q-axis voltage. The boundary value includes an upper boundary value and a lower boundary value. Based on the d-axis voltage and the q-axis optimized voltage, a PWM pulse signal for controlling the motor is generated.

2. The motor control method according to claim 1, characterized in that, If the rotor of the motor is in the low modulation region and the q-axis voltage is within the set prohibited range of the q-axis region, the q-axis voltage is optimized to generate an optimized q-axis voltage, including: If the absolute value of the vector sum of the d-axis voltage and the q-axis voltage is less than the set low modulation region threshold, and the q-axis voltage is within the prohibited range of the q-axis region, the q-axis voltage is optimized to generate an optimized q-axis voltage.

3. The motor control method according to claim 1, characterized in that, The control method further includes: if the rotor of the motor is in the low modulation region and the d-axis voltage is within the set prohibited range of the d-axis region, optimizing the d-axis voltage to generate an optimized d-axis voltage, wherein the optimized d-axis voltage is equal to the boundary value of the prohibited range of the d-axis region that has the same positive and negative sign as the d-axis voltage, and the boundary value includes an upper boundary value and a lower boundary value.

4. The motor control method according to claim 3, characterized in that, After optimizing the d-axis voltage to generate an optimized d-axis voltage, when the motor rotor is in the low modulation region and the d-axis voltage is within a set prohibited range of the d-axis region, the method further includes: The d-axis optimized voltage is constrained by a limit circle to generate the d-axis target voltage; The PWM pulse signal is generated based on the target voltage along the d-axis.

5. The motor control method according to claim 1, characterized in that, After optimizing the q-axis voltage to generate an optimized q-axis voltage, if the motor rotor is in the low modulation region and the q-axis voltage is within a set prohibited range for the q-axis region, the method further includes: The q-axis optimized voltage is subjected to limit circle constraint to generate the q-axis target voltage; The PWM pulse signal is generated based on the target voltage along the q-axis.

6. The motor control method according to claim 1, characterized in that, The method further includes: If the rotor of the motor is in the low modulation region and the q-axis voltage is not within the prohibited range of the q-axis region, the q-axis voltage is subject to limit circle limitation to generate the q-axis target voltage; The PWM pulse signal is generated based on the target voltage along the q-axis; and / or If the rotor of the motor is in the low modulation region and the d-axis voltage is not within the prohibited range of the d-axis region, the d-axis voltage is subject to limit circle limitation to generate the d-axis target voltage; The PWM pulse signal is generated based on the target voltage along the d-axis.

7. The motor control method according to claim 1, characterized in that, The method further includes: If the rotor of the motor is not in the low modulation region, the d-axis voltage and the q-axis voltage are subject to limit circle constraints to generate target q-axis voltage and target d-axis voltage, and the PWM pulse signal is generated based on the target q-axis voltage and target d-axis voltage.

8. The motor control method according to claim 1, characterized in that, The q-axis optimized voltage is equal to the boundary value of the prohibited range of the q-axis region that has the same sign as the q-axis voltage. The boundary value includes an upper boundary value and a lower boundary value, wherein the absolute values ​​of the upper boundary value and the lower boundary value are equal or unequal.

9. A motor control circuit, characterized in that, The motor control circuit includes: The voltage acquisition unit is used to acquire the d-axis voltage and q-axis voltage of the motor in a two-phase rotating coordinate system. A voltage region prohibition unit, connected to the voltage acquisition unit, is used to optimize the q-axis voltage if the motor rotor is in a low modulation region and the q-axis voltage is within a set q-axis region prohibition range, generating an optimized q-axis voltage. The optimized q-axis voltage is equal to a boundary value of the q-axis region prohibition range that has the same sign as the q-axis voltage, and the boundary value includes an upper boundary value and a lower boundary value. The signal generation unit, connected to the voltage region disable unit, is used to generate a PWM pulse signal for controlling the motor based on the d-axis voltage and the q-axis optimized voltage.

10. The motor control circuit according to claim 9, characterized in that, The voltage region disable unit is used for: If the absolute value of the vector sum of the d-axis voltage and the q-axis voltage is less than the set low modulation region threshold, and the q-axis voltage is within the prohibited range of the q-axis region, the q-axis voltage is optimized to generate an optimized q-axis voltage.

11. The motor control circuit according to claim 9, characterized in that, The voltage region inhibiting unit is also used for: If the rotor of the motor is in the low modulation region and the d-axis voltage is within the set prohibited range of the d-axis region, the d-axis voltage is optimized to generate an optimized d-axis voltage. The optimized d-axis voltage is equal to the boundary value of the prohibited range of the d-axis region that has the same positive and negative sign as the d-axis voltage. The boundary value includes an upper boundary value and a lower boundary value.

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