A method for realizing motor control in the case of phase failure

Abstract

The present invention relates to the field of motor control technology, and more specifically, to a method for implementing motor control in the event of a phase failure. Compared to the prior art, the present invention designs a method for implementing motor control in the event of a phase failure. The method determines whether a phase failure exists based on the demand current and feedback current. If a phase failure occurs, the method calculates motor control information such as the feedback current, reference voltage, and three-phase duty cycle. This method achieves phase failure control without modifying the motor and controller structures, thereby improving the safety of electronic power steering systems and ensuring that the system can provide power assistance in the event of a phase failure, thereby avoiding danger.

Description

Technical Field

[0001] The present invention relates to the technical field of motor control, in particular to a method for realizing motor control in a phase failure situation. Background Art

[0002] In recent years, permanent magnet synchronous motors (PMSMs) have been widely used due to their high efficiency and compact structure. In the field of electronic power steering (ESP), system safety is a crucial metric, and the fault-tolerant operation of the motor, a core component, has become a research hotspot.

[0003] like Figure 1 As shown, phase failure means that when one-phase set of the motor, such as U-phase, V-phase, or W-phase, or one-phase bridge arm of the inverter, such as Q1D1, Q2D2, Q3D3, Q4D4, Q5D5, or Q6D6, fails to operate normally due to mechanical or electrical failure, the MOSFET field-effect tubes, such as Q7D7, Q8D8, and Q9D9, will be cut off to achieve electrical isolation.

[0004] Currently, most strategies rely on changing the inverter topology to achieve phase loss control, such as a three-phase, four-leg structure. However, this approach requires a special motor with its center point removed. It also requires modifying the conventional three-phase, six-topology inverter structure to a four-phase, eight-topology inverter, increasing costs.

[0005] Therefore, it is necessary to design a method for realizing motor control in the case of phase loss. In the case of phase loss of the permanent magnet synchronous motor, the motor and controller structure are not modified to achieve the purpose of phase loss control, thereby improving the safety of the electronic power steering system. Summary of the Invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for realizing motor control in the case of phase loss. In the case of a permanent magnet synchronous motor phase loss, the motor and controller structure are not modified, and the purpose of phase loss control is achieved, thereby improving the safety of the electronic power steering system.

[0007] In order to achieve the above object, the present invention provides a method for realizing motor control in the case of phase failure, comprising the following steps: Step 1, collecting three-phase current and duty cycle signals, and calculating the motor's D-axis demand current according to the motor's current speed, required torque, and bus voltage. , q-axis demand current , d-axis feedback current , q-axis feedback current ; Step 2, such as d-axis demand current and d-axis feedback current The difference or q-axis demand current and q-axis feedback current If the difference is greater than the maximum sampling error of the current sensor, the EPS system is judged to be in a phase-loss state and proceed to step 3. If the d-axis demand current and d-axis feedback current The difference or q-axis demand current and q-axis feedback current If the difference is less than or equal to the maximum sampling error of the current sensor, the EPS system is judged to be not in a phase-loss state and the d-axis demand current is directly output. , q-axis demand current ; Step 3, cut off the phase separation MOSFET field effect tube and according to the q axis current demand , calculate the motor's D-axis required current using the motor's rotor electrical angle , q-axis demand current , demand phase current ; Step 4, if the phase current is required If the phase current is greater than the maximum allowed, proceed to step 5. If the current is less than or equal to the maximum allowed phase current, the d-axis demand current is directly output. , q-axis demand current ; Step 5, calculate the current d-axis demand current , q-axis demand current ; Step 6, according to the d-axis demand current , q-axis demand current and d-axis feedback current , q-axis feedback current , calculate the d-axis reference voltage , q-axis reference voltage If the EPS system is in a phase-loss state, set the current of the fault phase to 0 and calculate the d-axis feedback current again. , q-axis feedback current , eliminate the sampling effect; Step 7, calculate the alpha axis reference voltage , beta axis reference voltage ; Step 8, calculate the U phase duty cycle , V phase duty cycle , W phase duty cycle If the EPS system is in a phase-loss state, ensure that the power device of the fault phase has no switching action; Step 9, according to the U phase duty cycle , V phase duty cycle , W phase duty cycle Control the motor operation.

[0008] In step 1, calculate the motor's d-axis current requirement , q-axis demand current , d-axis feedback current , q-axis feedback current , in step 6, calculate the d-axis feedback current again , q-axis feedback current The formulas are: , ,in, is the motor phase resistance, is the motor electrical angular frequency, is the motor q-axis current, is the motor d-axis inductance, is the motor q-axis inductance, is the permanent magnet rotor flux, is the voltage circle limit value, Output torque required by the motor, is the number of motor pole pairs, is the motor d-axis current, Collect current for motor U phase, Collect current for motor V phase, Collect current for motor W phase, is the rotor electrical angle.

[0009] The calculation of the motor's D-axis current requirement is , q-axis demand current , demand phase current The formula is: ,in, is the rotor electrical angle.

[0010] The calculation of the current D-axis demand current , q-axis demand current The formula is: ,in, is the maximum value of the motor phase current, is the rotor electrical angle.

[0011] The calculation of the d-axis reference voltage , q-axis reference voltage The formula is: ,in, is the d-axis scale factor, is the d-axis integral coefficient, is the q-axis scale coefficient, is the q-axis integral coefficient.

[0012] The calculation of the alpha axis reference voltage , beta axis reference voltage The formula is: ,in, is the rotor electrical angle.

[0013] The calculation of U phase duty cycle , V phase duty cycle , W phase duty cycle The formula is: , ,in, is the maximum value of the voltage vector.

[0014] Compared with the prior art, the present invention designs a method for realizing motor control in the case of phase loss. Whether a phase loss occurs is determined by the demand current and the feedback current. If a phase loss occurs, the feedback current, the reference voltage, the three-phase duty cycle and other motor control information are calculated. The purpose of phase loss control is achieved without modifying the motor and controller structure, thereby improving the safety of the electronic power steering system and ensuring that the system can provide power assistance when a phase loss fault occurs, thereby avoiding danger. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The diagram is a schematic diagram of a phase-loss topology of a permanent magnet synchronous motor in the prior art.

[0016] Figure 2 This is a flow chart of the calculation of the required current of the permanent magnet synchronous motor in the present invention.

[0017] Figure 3 This is a control flow chart of the permanent magnet synchronous motor in the present invention. DETAILED DESCRIPTION

[0018] The present invention will now be further described with reference to the accompanying drawings.

[0019] See also Figure 2 、 Figure 3 The present invention provides a method for controlling a motor in a phase-out condition, comprising the following steps:

[0020] Step 1: Collect the three-phase current and duty cycle signals, and calculate the motor's D-axis demand current based on the motor's current speed, required torque, and bus voltage. , q-axis demand current , d-axis feedback current , q-axis feedback current .

[0021] Calculate the motor's D-axis current requirement , q-axis demand current , d-axis feedback current , q-axis feedback current The formula is: , ,in, is the motor phase resistance, is the motor electrical angular frequency, is the motor q-axis current, is the motor d-axis inductance, is the motor q-axis inductance, is the permanent magnet rotor flux, is the voltage circle limit value, Output torque required by the motor, is the number of motor pole pairs, is the motor d-axis current, Collect current for motor U phase, Collect current for motor V phase, Collect current for motor W phase, is the rotor electrical angle.

[0022] Step 2: If the d-axis current is required and d-axis feedback current The difference or q-axis demand current and q-axis feedback current If the difference is greater than the maximum sampling error of the current sensor, the EPS system is judged to be in a phase-loss state and proceed to step 3. If the d-axis demand current and d-axis feedback current The difference or q-axis demand current and q-axis feedback current If the difference is less than or equal to the maximum sampling error of the current sensor, the EPS system is judged to be not in a phase-loss state and the d-axis demand current is directly output. , q-axis demand current .

[0023] Step 3: Cut off the phase separation MOSFET field effect tube and adjust the current according to the q axis demand. , calculate the motor's D-axis required current using the motor's rotor electrical angle , q-axis demand current , demand phase current .

[0024] Calculate the motor's D-axis current requirement , q-axis demand current , demand phase current The formula is: ,in, is the rotor electrical angle.

[0025] Step 4: If the phase current is required If the phase current is greater than the maximum allowed, proceed to step 5. If the current is less than or equal to the maximum allowed phase current, the d-axis demand current is directly output. , q-axis demand current .

[0026] Step 5: Calculate the current d-axis demand current , q-axis demand current .

[0027] Calculate the current d-axis demand current , q-axis demand current The formula is: ,in, is the maximum value of the motor phase current, is the rotor electrical angle.

[0028] Step 6: Required current according to d-axis , q-axis demand current and d-axis feedback current , q-axis feedback current , calculate the d-axis reference voltage , q-axis reference voltage If the EPS system is in a phase-loss state, set the current of the fault phase to 0 and calculate the d-axis feedback current again. , q-axis feedback current , excluding the sampling effect.

[0029] Calculate the d-axis reference voltage , q-axis reference voltage The formula is: ,in, is the d-axis scale factor, is the d-axis integral coefficient, is the q-axis scale coefficient, is the q-axis integral coefficient.

[0030] Calculate the d-axis feedback current again , q-axis feedback current The formulas are: , ,in, is the motor phase resistance, is the motor electrical angular frequency, is the motor q-axis current, is the motor d-axis inductance, is the motor q-axis inductance, is the permanent magnet rotor flux, is the voltage circle limit value, Output torque required by the motor, is the number of motor pole pairs, is the motor d-axis current, Collect current for motor U phase, Collect current for motor V phase, Collect current for motor W phase, is the rotor electrical angle.

[0031] Step 7: Calculate the alpha axis reference voltage , beta axis reference voltage .

[0032] Calculate the alpha axis reference voltage , beta axis reference voltage The formula is: ,in, is the rotor electrical angle.

[0033] Step 8: Calculate the U phase duty cycle , V phase duty cycle , W phase duty cycle ,If the EPS system is in a phase-loss state, ensure that the power device of the faulty phase has no switching action.

[0034] Calculate the U phase duty cycle , V phase duty cycle , W phase duty cycle The formula is , ,in, is the maximum value of the voltage vector.

[0035] Step 9: According to the U phase duty cycle , V phase duty cycle , W phase duty cycle Control the motor operation.

Claims

1. A method for controlling a motor in the event of a phase failure, characterized in that: The steps include: Step 1, collecting three-phase current and duty cycle signals, and calculating the motor's D-axis demand current i according to the motor's current speed, required torque, and bus voltage. dref , q-axis demand current i qref , d-axis feedback current i dfed , q-axis feedback current i qfed ; Step 2, if the d-axis current i dref and the d-axis feedback current i dfed The difference or q-axis demand current i qref and q-axis feedback current i qfed The difference between the two is greater than the maximum sampling error of the current sensor, then the EPS system is judged to be in a phase-loss state, and the process goes to step 3. If the d-axis demand current i dref and the d-axis feedback current i dfed The difference or q-axis demand current i qref and q-axis feedback current i qfed If the difference is less than or equal to the maximum sampling error of the current sensor, the EPS system is judged to be not in a phase-loss state and the d-axis demand current i is directly output. dref , q-axis demand current i qref ; Step 3, cut off the phase separation MOSFET field effect tube, and according to the q axis demand current i qref 、Calculate the motor's d-axis required current i using the motor rotor electrical angle dref , q-axis demand current i qref , demand phase current i sref ; Step 4, if the required phase current i sref If the phase current is greater than the maximum allowed, proceed to step 5. sref If the phase current is less than or equal to the maximum allowed, the d-axis demand current i is directly output. dref , q-axis demand current i qref ; Step 5, calculate the current d-axis demand current i dref , q-axis demand current i qref ; Step 6, according to the d-axis demand current i dref , q-axis demand current i qref and d-axis feedback current i dfed , q-axis feedback current i qfed , calculate the d-axis reference voltage U dref , q-axis reference voltage U qref If the EPS system is in a phase-loss state, the current of the fault phase is set to 0 and the d-axis feedback current i is calculated again. dfed , q-axis feedback current i qfed , exclude the sampling effect; Step 7, calculate the alpha axis reference voltage U αref , beta axis reference voltage U βref ; Step 8, calculate the U-phase duty cycle DutyU, V-phase duty cycle DutyV, W-phase duty cycle DutyW. If the EPS system is in a phase-loss state, ensure that the power device of the fault phase has no switching action; Step 9, controlling the motor operation according to the U-phase duty cycle DutyU, the V-phase duty cycle DutyV, and the W-phase duty cycle DutyW; In step 1, the motor's d-axis required current i is calculated. dref , q-axis demand current i qref , d-axis feedback current i dfed , q-axis feedback current i qfed In step 6, the d-axis feedback current i is calculated again. dfed , q-axis feedback current i qfed The formulas are: Among them, R s is the motor phase resistance, w e is the motor electrical angular frequency, i q is the motor q-axis current, L d is the motor d-axis inductance, L q is the motor q-axis inductance, is the permanent magnet rotor flux, U lim is the voltage circle limit value, T e The motor output torque, p n is the number of motor pole pairs, i d is the motor d-axis current, i u Collect current for motor U phase, i v Collect current for motor V phase, i w The current is collected for the W phase of the motor, and θ is the electrical angle of the rotor.

2. The method for controlling a motor in a phase-out condition according to claim 1, wherein: The calculation of the motor's d-axis required current i dref , q-axis demand current i qref , demand phase current i sref The formula is: Where θ is the rotor electrical angle.

3. The method for controlling a motor in a phase failure state according to claim 1, wherein: The calculation of the current d-axis demand current i dref , q-axis demand current i qref The formula is: Among them, i smax is the maximum value of the motor phase current, and θ is the rotor electrical angle.

4. The method for controlling a motor in a phase failure state according to claim 1, wherein: The calculation of the d-axis reference voltage U dref , q-axis reference voltage U qref The formula is: Among them, K pd is the d-axis scale factor, K id is the d-axis integral coefficient, K pq is the q-axis proportional coefficient, K iq is the q-axis integral coefficient.

5. The method for controlling a motor in a phase failure state according to claim 1, wherein: The calculation of the alpha axis reference voltage U αref , beta axis reference voltage U βref The formula is: Where θ is the rotor electrical angle.

6. The method for controlling a motor in a phase failure state according to claim 1, wherein: The formula for calculating the U-phase duty cycle DutyU, the V-phase duty cycle DutyV, and the W-phase duty cycle DutyW is: Among them, U max is the maximum value of the voltage vector.

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