CN114865989B - A permanent magnet synchronous motor resolver fault detection and control method - Google Patents

Abstract

The present invention discloses a permanent magnet synchronous motor resolver fault detection and control method, the steps include: 1) judging whether there is an initial fault in the resolver decoding chip; 2) if there is an initial fault in the resolver decoding chip, a non-sensing control mode is adopted to control the operation of the permanent magnet synchronous motor, otherwise a sensing control mode is adopted to control the operation of the permanent magnet synchronous motor, and a resolver fault detection of the permanent magnet synchronous motor is performed, if there is no resolver fault in the permanent magnet synchronous motor, the motor position is calculated using the resolver decoding position, if there is a resolver fault in the permanent magnet synchronous motor, it is judged whether the fault of the permanent magnet synchronous motor is an occasional fault or a continuous fault, if it is an occasional fault, the fault is reset, if it is a continuous fault, the non-sensing control mode is switched to the non-sensing control mode. The present invention monitors the fault state of the resolver decoding chip in real time in the motor, and when a fault occurs, it is judged what kind of fault it is, and enters the corresponding operation mode to ensure that the motor can continue to operate when the resolver fails.

Description

A permanent magnet synchronous motor resolver fault detection and control method

Technical Field

The invention relates to the technical field of permanent magnet synchronous motor control, and in particular to a permanent magnet synchronous motor resolver fault detection and control method.

Background Art

The resolver (resolver for short) is a commonly used position sensor for permanent magnet synchronous motors, which is used to provide rotor position information to permanent magnet synchronous motors. The controller performs motor control based on the position information provided by the resolver. Once the resolver fails, the motor control system will not be able to operate normally.

Summary of the invention

The object of the present invention is to provide a permanent magnet synchronous motor resolver fault detection and control method, comprising the following steps:

1) Before starting the permanent magnet synchronous motor, use the controller to perform fault detection on the resolver decoding chip to determine whether the resolver decoding chip has an initial fault;

The steps for fault detection of the resolver decoding chip include:

1.1) Initialize the fault counter k=0;

1.2) The controller determines whether the resolver decoding chip uploads fault information. If so, it proceeds to step 1.4), otherwise it proceeds to step 1.3);

1.3) Determine whether the output pins LOT and DOS of the resolver decoding chip are both at low level. If so, proceed to step 1.4), otherwise proceed to step 1.5);

1.4) Reset the resolver decoding chip, set the fault counter k=k+1, and proceed to step 1.6);

1.5) Determine whether the current fault counter k is greater than 0. If so, set the fault counter k=k-1 and proceed to step 1.6);

1.6) Determine whether the current fault counter k is greater than the threshold kmax. If so, determine that the resolver decoding chip has an initial fault. Otherwise, proceed to step 7);

1.7) Determine whether the controller receives the permanent magnet synchronous motor start signal. If so, determine that the resolver decoding chip does not have an initial fault. Otherwise, return to step 2).

2) When the controller receives the permanent magnet synchronous motor start signal, if there is an initial fault in the resolver decoding chip, the permanent magnet synchronous motor is controlled to run in a sensorless control mode, otherwise, proceed to step 3);

The sensorless control mode includes a pulse high frequency injection sensorless control mode and a sliding mode sensorless control mode.

The steps of controlling the operation of a permanent magnet synchronous motor using a sensorless control mode include:

2.1) Inject high-frequency pulse voltage into the d-axis of the permanent magnet synchronous motor in the estimated synchronous rotating coordinate system, and sample the current of the q-axis in the estimated synchronous rotating coordinate system. Calculate the high-frequency ripple current component

2.2) Estimation of the Q-axis high-frequency current in the synchronous rotating coordinate system based on the permanent magnet synchronous motor Calculate the speed through PI Speed Integral calculation of rotor position When the Q-axis high-frequency current is equal to zero, the estimated rotor position coincides with the actual rotor position.

2.3) Determine the polarity of the permanent magnet synchronous motor and correct the rotor position of the permanent magnet synchronous motor. The correction steps include:

2.3.1) At time t0, a positive high-frequency voltage is injected into the D axis for a period of Δt until time t1, and the peak current Imax1 is collected at time t1;

2.3.2) Stop voltage injection until time t2, then start injecting negative high-frequency voltage into the D axis for a period of Δt until time t3, and collect the peak current Imax2 at time t3;

2.3.3) Determine whether the peak current Imax1 is greater than the peak current Imax2. If so, the magnetic pole polarity is correct and no magnetic pole position correction is performed. Otherwise, the rotor position is increased by 180° electrical angle.

2.4) After obtaining the position of the permanent magnet synchronous motor, the pulse high-frequency injection sensorless control mode is used to control the operation of the permanent magnet synchronous motor. After the speed of the permanent magnet synchronous motor is greater than h1rpm, the sliding mode observer is started. When the speed of the permanent magnet synchronous motor is greater than h3rpm, it is switched to the sliding mode sensorless control mode; after entering the sliding mode sensorless control mode, when the speed of the permanent magnet synchronous motor is lower than h2rpm, it is switched to the pulse high-frequency injection sensorless control mode; the speed of the permanent magnet synchronous motor in the sensorless control mode is obtained by the observer.

0＜parameter h1＜parameter h2＜parameter h3.

3) Using the sensor control mode to control the operation of the permanent magnet synchronous motor, and performing permanent magnet synchronous motor resolver fault detection, if there is no permanent magnet synchronous motor resolver fault, the motor position is calculated using the resolver decoding position, if there is a permanent magnet synchronous motor resolver fault, then go to step 4);

The method for detecting a resolver fault of a permanent magnet synchronous motor comprises: determining whether at least one of the following conditions is met, if so, the permanent magnet synchronous motor has a resolver fault, and if none of the following conditions are met, the permanent magnet synchronous motor does not have a resolver fault;

Condition 1: The controller receives the fault information sent by the resolver decoding chip, and the fault information is not zero;

Condition 2: The output pins LOT and DOS of the resolver decoding chip are both at low level;

Condition three: The absolute value of the difference between the current position of the permanent magnet synchronous motor and the previous position is greater than the threshold dmax.

4) Determine whether the fault of the permanent magnet synchronous motor is an occasional fault or a continuous fault. If it is an occasional fault, perform a fault reset. If it is a continuous fault, switch the sensorless control mode to the sensorless control mode.

The steps for determining whether the fault of the permanent magnet synchronous motor is an occasional fault or a continuous fault include:

4.1) When a resolver fault is detected in the permanent magnet synchronous motor, the resolver decoding chip fault reset is performed;

4.2) Re-detect the permanent magnet synchronous motor resolver fault and return to step 1) until a detection cycle is completed. After a detection cycle, calculate the value p of the permanent magnet synchronous motor resolver fault counter. If the permanent magnet synchronous motor resolver fault counter p is greater than the threshold value pmax, the permanent magnet synchronous motor fault is judged to be a continuous fault, otherwise it is an occasional fault.

The method for calculating the value p of the permanent magnet synchronous motor resolver fault counter includes:

If the detection result shows that the permanent magnet synchronous motor has a resolver fault, then p=p+1;

If the detection result shows that the permanent magnet synchronous motor does not have a resolver fault and p>0, then p=p-1.

When the permanent magnet synchronous motor fault is an occasional fault, the current rotor position is deduced based on inertia, and the resolver decoding chip fault reset is performed;

The current rotor position is equal to the previous position data plus the position increment filter output value Δθ _r (n).

Among them, the position increment filter output value Δθ _r (n) is as follows:

Δθ _r (n)=(1-a)*Δθ _r (n-1)+a*[θ _r (n)-θ _r (n-1)] (1)

Wherein, θ _r (n) is the rotor position sampled in the current current loop cycle; θ _r (n-1) is the rotor position sampled in the previous current loop cycle; and a is the low-pass filter coefficient.

The steps to switch the sensorless control mode to the sensorless control mode include:

a) Adjust the speed command slope to h4rpm/s; parameter h4 is smaller than parameter h1.

b) Check whether the current speed is less than or equal to h2rpm; if the current speed is greater than h2rpm, enter the sliding mode sensorless control mode; if the current speed is ≤h2rpm, enter the high-frequency injection sensorless control mode.

The technical effect of the present invention is unquestionable. The present invention monitors the fault status of the resolver decoding chip in real time before and during the operation of the motor, and when a fault occurs, determines whether it is a startup fault (initial fault), an occasional fault or a continuous fault, and enters the corresponding operation mode to ensure that the motor can continue to run when the resolver fails.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic flow chart of the method of the present invention;

Fig. 2 is a flowchart of the rotary transformer fault detection before starting in the present invention;

FIG3 is a flow chart of the non-sensing control in the present invention;

FIG4 is a flow chart of fault mode determination in the present invention;

FIG5 is a flow chart of switching from sensory control to non-sensing control in the present invention;

FIG6 is a flow chart of high frequency ripple current component calculation;

FIG7 is a flow chart of rotor position calculation;

FIG8 is a flow chart of correcting the rotor position of a permanent magnet synchronous motor.

DETAILED DESCRIPTION

The present invention is further described below in conjunction with the embodiments, but it should not be understood that the above subject matter of the present invention is limited to the following embodiments. Without departing from the above technical ideas of the present invention, various substitutions and changes are made according to the common technical knowledge and customary means in the art, which should all be included in the protection scope of the present invention.

Embodiment 1:

Referring to FIG. 1 to FIG. 8 , a method for detecting and controlling a permanent magnet synchronous motor resolver fault comprises the following steps:

1) Before starting the permanent magnet synchronous motor, use the controller to perform fault detection on the resolver decoding chip to determine whether the resolver decoding chip has an initial fault;

The steps for fault detection of the resolver decoding chip include:

1.1) Initialize the fault counter k=0;

1.2) The controller determines whether the resolver decoding chip uploads fault information. If so, it proceeds to step 1.4), otherwise it proceeds to step 1.3);

1.3) Determine whether the output pins LOT and DOS of the resolver decoding chip are both at low level. If so, proceed to step 1.4), otherwise proceed to step 1.5);

1.4) Reset the resolver decoding chip, set the fault counter k=k+1, and proceed to step 1.6);

1.5) Determine whether the current fault counter k is greater than 0. If so, set the fault counter k=k-1 and proceed to step 1.6);

1.6) Determine whether the current fault counter k is greater than the threshold kmax. If so, determine that the resolver decoding chip has an initial fault. Otherwise, proceed to step 7);

1.7) Determine whether the controller receives the permanent magnet synchronous motor start signal. If so, determine that the resolver decoding chip does not have an initial fault. Otherwise, return to step 2).

2) When the controller receives the permanent magnet synchronous motor start signal, if there is an initial fault in the resolver decoding chip, the permanent magnet synchronous motor is controlled to run in a sensorless control mode, otherwise, proceed to step 3);

The sensorless control mode includes a pulse high frequency injection sensorless control mode and a sliding mode sensorless control mode.

The steps of controlling the operation of a permanent magnet synchronous motor using a sensorless control mode include:

2.1) Referring to FIG6 , a high-frequency pulse voltage is injected into the d-axis of the permanent magnet synchronous motor in the estimated synchronous rotating coordinate system, and the q-axis sampling current in the estimated synchronous rotating coordinate system is calculated. Calculate the high-frequency ripple current component

2.2) Referring to FIG7, the Q-axis high-frequency current in the synchronous rotating coordinate system is estimated based on the permanent magnet synchronous motor. Calculate the speed through PI Speed Integral calculation of rotor position When the Q-axis high-frequency current is equal to zero, the estimated rotor position coincides with the actual rotor position.

2.3) Determine the polarity of the permanent magnet synchronous motor and correct the rotor position of the permanent magnet synchronous motor. The correction method is shown in FIG8 , and the steps include:

2.3.1) At time t0, a positive high-frequency voltage is injected into the D axis for a period of Δt until time t1, and the peak current Imax1 is collected at time t1;

2.3.2) Stop voltage injection until time t2, then start injecting negative high-frequency voltage into the D axis for a period of Δt until time t3, and collect the peak current Imax2 at time t3;

2.3.3) Determine whether the peak current Imax1 is greater than the peak current Imax2. If so, the magnetic polarity is correct and no magnetic pole position correction is performed. Otherwise, the magnetic pole position is increased by 180°.

2.4) After obtaining the position of the permanent magnet synchronous motor, the pulse high-frequency injection sensorless control mode is used to control the operation of the permanent magnet synchronous motor. After the speed of the permanent magnet synchronous motor is greater than 500rpm, the sliding mode observer is started. When the speed of the permanent magnet synchronous motor is greater than 800rpm, it is switched to the sliding mode sensorless control mode; after entering the sliding mode sensorless control mode, when the speed of the permanent magnet synchronous motor is lower than 600rpm, it is switched to the pulse high-frequency injection sensorless control mode; the speed of the permanent magnet synchronous motor in the sensorless control mode is obtained by the observer.

3) Using the sensor control mode to control the operation of the permanent magnet synchronous motor, and performing permanent magnet synchronous motor resolver fault detection, if there is no permanent magnet synchronous motor resolver fault, the motor position is calculated using the resolver decoding position, if there is a permanent magnet synchronous motor resolver fault, then go to step 4);

The method for detecting a resolver fault of a permanent magnet synchronous motor comprises: determining whether at least one of the following conditions is met, if so, the permanent magnet synchronous motor has a resolver fault, and if none of the following conditions are met, the permanent magnet synchronous motor does not have a resolver fault;

Condition 1: The controller receives the fault information sent by the resolver decoding chip, and the fault information is not zero;

Condition 2: The output pins LOT and DOS of the resolver decoding chip are both at low level;

Condition three: The absolute value of the difference between the current position of the permanent magnet synchronous motor and the previous position is greater than the threshold dmax.

4) Determine whether the fault of the permanent magnet synchronous motor is an occasional fault or a continuous fault. If it is an occasional fault, perform a fault reset. If it is a continuous fault, switch the sensorless control mode to the sensorless control mode.

The steps for determining whether the fault of the permanent magnet synchronous motor is an occasional fault or a continuous fault include:

4.1) When a resolver fault is detected in the permanent magnet synchronous motor, the resolver decoding chip fault reset is performed;

4.2) Re-detect the permanent magnet synchronous motor resolver fault and return to step 1) until a detection cycle is completed. After a detection cycle, calculate the value p of the permanent magnet synchronous motor resolver fault counter. If the permanent magnet synchronous motor resolver fault counter p is greater than the threshold value pmax, the permanent magnet synchronous motor fault is judged to be a continuous fault, otherwise it is an occasional fault.

The method for calculating the value p of the permanent magnet synchronous motor resolver fault counter includes:

If the detection result shows that the permanent magnet synchronous motor has a resolver fault, then p=p+1;

If the detection result shows that the permanent magnet synchronous motor does not have a resolver fault and p>0, then p=p-1.

When the permanent magnet synchronous motor fault is an occasional fault, the current rotor position is deduced based on inertia, and the resolver decoding chip fault reset is performed;

The current rotor position is equal to the previous position data plus the position increment filter output value.

The calculation method of the position increment filter output value Δθ _r (n) is as follows: when there is no fault in the resolver position, the output value of the difference between the rotor position θ _r (n) sampled in the current loop cycle and the rotor position θ _r (n-1) sampled in the previous current loop cycle after low-pass filtering. The specific formula is as follows, where a is the low-pass filter coefficient.

Δθ _r (n)=(1-a)*Δθ _r (n-1)+a*[θ _r (n)-θ _r (n-1)]

The steps to switch the sensorless control mode to the sensorless control mode include:

a) Adjust the speed command slope to 300 rpm/s.

b) Check whether the current speed is less than or equal to 600rpm; if the current speed is greater than 600rpm, enter the sliding mode sensorless control mode; if the current speed is ≤600rpm, enter the high-frequency injection sensorless control mode.

Embodiment 2:

Referring to FIG. 1 to FIG. 5 , a method for detecting and controlling a permanent magnet synchronous motor resolver fault comprises the following steps:

S1. Perform initial fault detection of resolver decoding chip before startup;

S2. Detect whether there is an initial fault in the resolver decoding chip;

S3. After receiving the startup information, if there is an initial failure of the resolver decoding chip, enter the non-sensing control mode

S4. After receiving the startup information, if there is no initial failure of the resolver decoding chip, enter the sensor control mode;

S5. In the sensor control mode, perform resolver fault detection;

S6, when there is no fault in the resolver, the position of the motor is calculated using the position decoded by the resolver;

S7. When the resolver fails, determine whether it is an occasional failure or a continuous failure;

S8. If it is an occasional fault, use the rotor position derived from inertia and perform fault reset; after receiving fault-free information for 5 consecutive times, use the resolver to calculate the output position as the motor rotor position;

S9: If the fault persists, switch directly to the sensorless control mode.

In S2, the detection of the initial fault adopts reading fault information and resetting. If the fault information is continuously received within 100ms and any one of the LOT and DOS signals is low, it is judged as an initial fault of the resolver.

In S3, a pulse square wave with an amplitude of 20% of the bus voltage is first injected into the D axis, the motor position is calculated according to the high-frequency current of the Q axis, and then the motor polarity is judged. After the polarity is judged and the position is corrected, the high-frequency square wave injection senseless control mode is entered; when the speed is greater than 500rpm, the sliding mode observer is started; after the speed is higher than 800rpm, it is switched to the sliding mode senseless control mode; after entering the sliding mode senseless control mode, when the speed is lower than 600rpm, it is switched to the pulse high-frequency injection senseless control mode.

In S4, the sliding mode observer is started when the rotation speed is greater than 500 rpm.

In S5, if the fault information read is not zero, any of the LOT and DOS signals is low, and the absolute value of the difference between the position information read this time and the last position is greater than 5000, it is determined that there is a fault in the resolver decoding within the current loop cycle.

In S7, when a resolver fault is detected, a fault reset is performed in the main loop. If the resolver fault is detected for 10 ms continuously, it is determined that there is a long-term fault, otherwise it is determined to be an occasional fault.

In S8, a first-order low-pass filter is performed on each position increment, and the filter coefficient is set to 0.125; if a fault is detected, the current position data is equal to the previous position data plus the position increment filter output value.

In S9, the speed command slope is first reduced to 300rpm/s. If the current speed is less than 600rpm, the control mode is switched to the pulse high-frequency injection senseless control mode; otherwise, the control mode is switched to the sliding mode senseless control mode. After entering the sliding mode senseless control mode, when the speed is lower than 600rpm, the control mode is switched to the pulse high-frequency injection senseless control mode.

Embodiment 3:

Referring to FIG. 1 to FIG. 5 , a method for detecting and controlling a permanent magnet synchronous motor resolver fault comprises the following steps:

S1, motor controller initialization;

S2. Detect whether there is an initial fault in the resolver decoding chip;

S3. After receiving the startup information, if there is an initial failure of the resolver decoding chip, enter the non-sensing control mode

S4. After receiving the startup information, if there is no initial failure of the resolver decoding chip, enter the sensor control mode;

S5. In the sensor control mode, perform resolver fault detection;

S6, when there is no fault in the resolver, the position of the motor is calculated using the position decoded by the resolver;

S7. When the resolver fails, determine whether it is an occasional failure or a long-term failure;

S8. If it is an occasional fault, use the rotor position derived from inertia and perform fault reset; after receiving fault-free information for 5 consecutive times, use the resolver to calculate the output position as the motor rotor position;

S9: If the fault persists, switch to the sensorless control mode.

Embodiment 4:

Referring to FIG. 2 , a method for detecting and controlling a permanent magnet synchronous motor resolver fault is shown in Example 3. The main steps are as follows:

a1. Read the resolver information once every 1ms to check whether the resolver decoding chip fault information read is not zero;

a2. Read the output pins LOT and DOS of the resolver decoding chip to see if they are at a low level;

a3. When a1 or a2 is satisfied, it is determined that a resolver fault has occurred in this cycle, the fault register of the resolver decoding chip is read, and the resolver decoding chip fault reset is performed;

a4. When a1 or a2 is satisfied, add 1 to the fault counter;

a5. When a1 or a2 is not satisfied, and the fault counter is greater than 0, the counter is reduced by 1;

a6. Determine whether the fault counter is greater than 100;

a7. If the fault counter is greater than 100, it is determined that a resolver startup fault has been detected;

a8. When the start signal is received, the fault counter is less than 100;

a9. Exit the resolver startup fault detection.

Embodiment 5:

Referring to FIG3 , a method for detecting and controlling a permanent magnet synchronous motor resolver fault is shown in Example 3. The main steps are as follows:

b1. Inject a pulse voltage into the assumed D-axis and perform initial position detection through the high-frequency response current of the Q-axis;

b2. Perform magnetic pole identification by injecting positive and negative pulse voltages on the D axis and detecting the D axis current response to determine the magnetic pole polarity. After the identification is completed, perform magnetic pole correction.

b3. Enter the pulse high frequency injection non-sensing control mode;

b4. Start the sliding mode observer when the speed is greater than 500 rpm;

b5. When the speed is greater than 800rpm, it enters the sliding mode sensorless control mode;

b6. After entering the sliding mode sensorless control mode, the speed is less than 600rpm and enters the pulse high frequency injection sensorless control mode.

Embodiment 6:

Referring to FIG4 , a method for detecting and controlling a permanent magnet synchronous motor resolver fault is shown in Example 3. The main steps are as follows:

c1. After the motor starts running, read the resolver information once every 200us to check whether the resolver decoding chip fault information read is not zero;

c2. Read whether the output pins LOT and DOS of the resolver decoding chip are at low level;

c3. When c1 or c2 is satisfied, it is determined that a resolver fault has occurred in this cycle, the fault register of the resolver decoding chip is read, and the resolver decoding chip fault reset is performed;

c4. When a1 or a2 is satisfied, add 1 to the fault counter;

c5. When neither a1 nor a2 is satisfied and the fault counter is greater than 0, the counter is reduced by 1;

c6. Determine whether the fault counter is not equal to 0;

c7. Determine whether the fault counter is greater than or equal to 50;

c8, the fault counter is equal to 0, and it is determined that the resolver has no fault;

c9. The fault counter is greater than 0 and less than 50, indicating that the resolver has an occasional fault;

c10. If the fault counter is greater than or equal to 50, it is determined that the resolver has a continuous fault.

Embodiment 7:

Referring to FIG5 , a method for detecting and controlling a permanent magnet synchronous motor resolver fault is shown in Example 3. The main steps are shown in Example 3, wherein the process of switching from inductive to non-inductive is as follows:

d1. When the speed command slope is adjusted to 300rpm/s;

d2. Check whether the current speed is less than or equal to 600rpm;

d3. The current speed is greater than 600rpm, and the sliding mode sensorless control mode is entered;

d4. When the current speed is ≤600rpm, the system enters high-frequency injection sensorless control mode.

Claims (9)

1. The method for detecting and controlling the rotational failure of the permanent magnet synchronous motor is characterized by comprising the following steps of:

1) Before starting the permanent magnet synchronous motor, detecting faults of the rotary decoding chip by using a controller, and judging whether the rotary decoding chip has initial faults or not;

2) When the controller receives a permanent magnet synchronous motor starting signal, if the initial fault of the rotary-transformer decoding chip exists, the operation of the permanent magnet synchronous motor is controlled by adopting a non-inductive control mode, otherwise, the step 3 is entered;

3) Controlling the permanent magnet synchronous motor to run by adopting a inductive control mode, detecting the rotation failure of the permanent magnet synchronous motor, calculating the motor position by utilizing the rotation decoding position if the rotation failure of the permanent magnet synchronous motor does not exist, and entering the step 4 if the rotation failure of the permanent magnet synchronous motor exists;

4) Judging whether the fault of the permanent magnet synchronous motor is an accidental fault or a continuous fault, if the fault is the accidental fault, resetting the fault, and if the fault is the continuous fault, switching the inductive control mode into the noninductive control mode;

When the fault of the permanent magnet synchronous motor is an accidental fault, deducing the current rotor position according to inertia, and resetting the fault of the rotary-transformer decoding chip;

The current rotor position is equal to the last position data plus a position delta filter output value Δθ _r (n);

Wherein the position delta filter output value Δθ _r (n) is as follows:

Δθ_r(n)＝(1-a)*Δθ_r(n-1)+a*[θ_r(n)-θ_r(n-1)](1)

Wherein, theta _r (n) is the rotor position of the current loop period sampling; θ _r (n-1) is the rotor position of the last current loop cycle sample; a is a low pass filter coefficient.

2. The method for detecting and controlling the rotational failure of a permanent magnet synchronous motor according to claim 1, wherein the step of detecting the failure of the rotational decoding chip comprises:

1) Initializing a fault counter k=0;

2) The controller judges whether the rotary decoding chip uploads fault information or not, if yes, the step 4) is entered, and if not, the step 3) is entered;

3) Judging whether output pins LOT and DOS of the rotary-transformer decoding chip are low level or not, if yes, entering the step 4), otherwise, entering the step 5);

4) Resetting the rotary decoding chip, enabling the fault counter k=k+1, and entering the step 6);

5) Judging whether the current fault counter k is larger than 0, if so, enabling the fault counter k=k-1, and entering a step 6);

6) Judging whether the current fault counter k is larger than a threshold kmax or not, if yes, judging that an initial fault exists in the rotary decoding chip, otherwise, entering a step 7);

7) Judging whether the controller receives a permanent magnet synchronous motor starting signal, if yes, judging that the rotary-transformer decoding chip has no initial fault, otherwise, returning to the step 2).

3. The method for detecting and controlling the rotational failure of the permanent magnet synchronous motor according to claim 1, wherein the non-inductive control mode includes a pulse vibration high frequency injection non-inductive control mode and a sliding mode non-inductive control mode.

4. The method for detecting and controlling the rotational failure of a permanent magnet synchronous motor according to claim 1, wherein the step of controlling the operation of the permanent magnet synchronous motor in the sensorless control mode comprises:

1) Injecting high-frequency pulse vibration voltage on d axis of permanent magnet synchronous motor under the estimated synchronous rotation coordinate system, sampling current according to q axis under the estimated synchronous rotation coordinate system Calculating to obtain high-frequency ripple current component

2) Estimating Q-axis high-frequency current under synchronous rotation coordinate system according to permanent magnet synchronous motorCalculation of the rotational speed by PIRotational speedIntegral calculation of rotor positionWhen the Q-axis high frequency current is equal to zero, the estimated rotor position coincides with the actual rotor position;

3) Judging the polarity of the permanent magnet synchronous motor, and correcting the rotor position of the permanent magnet synchronous motor, wherein the correcting step comprises the following steps:

3.1 Injecting a forward high-frequency voltage into the D shaft at the time t0, lasting delta t time to the time t1, and collecting a peak current Imax1 at the time t 1;

3.2 Stopping voltage injection until the negative high-frequency voltage starts to be injected into the D axis at the time t2, continuing the delta t time to the time t3, and collecting the peak current Imax2 at the time t 3;

3.3 Judging whether the peak current Imax1 is larger than the peak current Imax2, if yes, the magnetic pole polarity is correct, and the magnetic pole position correction is not performed, otherwise, the rotor position is added with 180 DEG electrical angle;

4) After the position of the permanent magnet synchronous motor is obtained, a pulse vibration high-frequency injection noninductive control mode is adopted to control the permanent magnet synchronous motor to run, after the rotating speed of the permanent magnet synchronous motor is greater than h1rpm, a sliding mode observer is started, and when the rotating speed of the permanent magnet synchronous motor is greater than h3rpm, the sliding mode noninductive control mode is switched to; after entering a slip form noninductive control mode, switching to a pulse vibration high-frequency injection noninductive control mode when the rotating speed of the permanent magnet synchronous motor is lower than h2 rpm; the rotating speed of the permanent magnet synchronous motor in the noninductive control mode is obtained by an observer.

5. The method for detecting and controlling the rotational failure of a permanent magnet synchronous motor according to claim 4, wherein 0< parameter h1 < parameter h2 < parameter h3.

6. The method for detecting and controlling the rotational failure of the permanent magnet synchronous motor according to claim 1, wherein the method for detecting the rotational failure of the permanent magnet synchronous motor comprises the steps of: judging whether at least one of the following conditions is met, if yes, the permanent magnet synchronous motor has a rotation failure, and if none of the following conditions is met, the permanent magnet synchronous motor has no rotation failure;

Condition one: the controller receives fault information sent by the rotary-transformer decoding chip, and the fault information is not zero;

Condition II: output pins LOT and DOS of the rotary-transformer decoding chip are both low level;

and (3) a third condition: the absolute value of the difference between the current permanent magnet synchronous motor and the last position is greater than a threshold dmax.

7. The method for detecting and controlling a rotational failure of a permanent magnet synchronous motor according to claim 1, wherein the step of judging whether the failure of the permanent magnet synchronous motor is an occasional failure or a continuous failure comprises:

1) When detecting that the permanent magnet synchronous motor has a rotation failure, executing the rotation decoding chip failure reset;

2) And (3) re-detecting the permanent magnet synchronous motor rotation failure, returning to the step (1) until one detection period is completed, calculating the value p of the permanent magnet synchronous motor rotation failure counter after one detection period is completed, and judging that the failure of the permanent magnet synchronous motor is continuous failure if the permanent magnet synchronous motor rotation failure counter p is larger than a threshold value pmax, otherwise, judging that the failure is accidental failure.

8. The method for detecting and controlling the rotational failure of the permanent magnet synchronous motor according to claim 1, wherein the method for calculating the value p of the rotational failure counter of the permanent magnet synchronous motor comprises the steps of:

if the detection result is that the permanent magnet synchronous motor has a rotation failure, p=p+1;

if the detection result is that the permanent magnet synchronous motor has no rotation failure and p is more than 0, let p=p-1.

9. The method for detecting and controlling the rotational failure of the permanent magnet synchronous motor according to claim 1, wherein the method comprises the following steps: the step of switching the inductive control mode to the non-inductive control mode includes:

1) Adjusting the slope of the speed command to h4rpm/s; parameter h4 is less than parameter h1;

2) Checking whether the current rotation speed is less than or equal to h2rpm; the current rotating speed is greater than h2rpm, and entering a slip form non-inductive control mode; the current rotating speed is less than or equal to h2rpm, and a high-frequency injection noninductive control mode is entered.