Belt speed restarting method of flywheel energy storage permanent magnet synchronous motor

Abstract

The invention relates to the technical field of operation and maintenance of a permanent magnet synchronous motor, in particular to a belt speed restarting method of a flywheel energy storage permanent magnet synchronous motor, which comprises the following steps of: acquiring a current back electromotive force signal of the permanent magnet synchronous motor; judging the current working state of the permanent magnet synchronous motor; and when the permanent magnet synchronous motor is in an abnormal state, analyzing the current back electromotive force signal to obtain the current estimated rotating speed of the permanent magnet synchronous motor rotor. According to the embodiment of the invention, the counter electromotive force signal of the permanent magnet synchronous motor in the abnormal working state is collected to carry out preliminary rotor speed estimation, and then the estimation interval of the rotor speed is matched with a proper rotor speed measurement strategy, so that the defect that the error of the rotor speed measurement strategy in some intervals is relatively high is effectively avoided; therefore, the position and the rotating speed of the rotor can be quickly and accurately calculated when the permanent magnet synchronous motor is in an abnormal working state, and the permanent magnet synchronous motor can be restarted at a stable belt speed.

Description

Technical Field

[0001] The present application relates to the technical field of permanent magnet synchronous motor operation and maintenance, and in particular to a belt speed re-start method for a flywheel energy storage permanent magnet synchronous motor. Background Art

[0002] After the flywheel energy storage permanent magnet synchronous motor enters the inert working condition after power failure, it takes a long time to release kinetic energy and reach a static state. Therefore, it is necessary to determine the speed and position of the rotor to achieve the motor speed re-start and reduce the motor's downtime waiting time.

[0003] The permanent magnet synchronous motor rotor speed measurement method has a limited speed range. When the speed measurement method used measures a rotor that is not within its optimal measurement range, large errors in the rotor speed and position calculations will occur. When the calculation error is large, the motor speed re-start will fail, causing the motor to vibrate and be damaged. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present application provides a method for re-starting the speed of a flywheel energy storage permanent magnet synchronous motor. The embodiment of the present application performs a preliminary rotor speed estimation by collecting the back electromotive force signal of the permanent magnet synchronous motor under abnormal working conditions, and then matches the appropriate rotor speed measurement strategy through the estimated rotor speed interval, thereby effectively avoiding the defect of the rotor speed measurement strategy having high errors in certain intervals, so that the permanent magnet synchronous motor can quickly and accurately calculate the rotor position and speed under abnormal working conditions, so that the permanent magnet synchronous motor can be stably re-started at speed.

[0005] The above application objectives of this application are achieved through the following technical solutions: A method for re-starting a flywheel energy storage permanent magnet synchronous motor at a high speed, comprising the following steps: Get the current back electromotive force signal of the permanent magnet synchronous motor; Determine the current working state of the permanent magnet synchronous motor; When the permanent magnet synchronous motor is in an abnormal state, the current back electromotive force signal is analyzed to obtain the current estimated rotation speed of the permanent magnet synchronous motor rotor; A speed measurement strategy for matching a permanent magnet synchronous motor based on the current estimated rotation speed of the rotor; According to the selected speed measurement strategy, calculate the current reliable speed and reliable position of the rotor; The current reliable speed and reliable position of the rotor are brought into the permanent magnet synchronous motor speed re-start procedure.

[0006] In summary, this application has the following beneficial technical effects: The embodiment of the present application performs preliminary rotor speed estimation by collecting the back electromotive force signal of the permanent magnet synchronous motor under abnormal working conditions, and then matches the appropriate rotor speed measurement strategy through the estimated rotor speed interval, thereby effectively avoiding the defect of high error of the rotor speed measurement strategy in certain intervals, so that the permanent magnet synchronous motor can quickly and accurately calculate the rotor position and speed under abnormal working conditions, and the permanent magnet synchronous motor can be re-invested at a stable speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a schematic diagram of a flow chart of an implementation method of the present application; Figure 2 It is a schematic diagram of the layout of a permanent magnet synchronous motor according to an embodiment of the present application; Figure 3 This is a schematic diagram of the layout of the signal winding of the permanent magnet synchronous motor in one embodiment of the present application; Figure 4 This is a schematic diagram of a short circuit of a three-phase inverter according to an embodiment of the present application; Figure 5 This is a schematic diagram of a zero voltage vector of a secondary pulse method according to an embodiment of the present application; Figure 6 This is a schematic diagram of two short-circuit current vectors of a vector pulse method according to an embodiment of the present application; Figure 7 Schematic diagram of the current vector and the stationary coordinate axis according to an embodiment of the present application.

[0008] Figure numerals: 1. signal winding; 2. permanent magnet; 3. rotor core; 4. transmission shaft; 5. permanent magnet sheath; 6. signal winding one; 7. signal winding two. DETAILED DESCRIPTION

[0009] The following is combined with Figure 1 -Attached Figure 7 This application is described in further detail.

[0010] In order to more clearly understand the technical solution presented in the embodiment of the present application, a brief introduction to the operation of the existing flywheel energy storage permanent magnet motor is first given.

[0011] Permanent magnet synchronous motors are widely used in fans, compressors, pumps, flywheel energy storage, high-speed centrifuges and other fields due to their high power density and high energy efficiency ratio. With the increasing demand for energy, it has high research value and application prospects. The permanent magnet synchronous motor control system uses a position sensor to obtain the motor rotor position and rotor speed to achieve motor vector control. However, the use of position sensors increases the size and complexity of the system, and they are expensive and have low reliability. They cannot meet the high reliability requirements under specific industrial working conditions. In addition, in order to eliminate the influence of air resistance on the flywheel speed, new flywheel energy storage equipment often works in a vacuum chamber as a whole, which further increases the difficulty of maintenance and repair.

[0012] In some industrial fields, it is necessary to shut down and close the switch to clear some power supply faults, which will also cause the motor driver to be temporarily powered off. If the permanent magnet synchronous motor control system does not have the ability to re-start with speed, it often takes a long time to wait, wasting energy and delaying industrial production. In the one-to-many application of pumps, when the pump machine is switched from industrial frequency to variable frequency, the inverter is required to have the ability to immediately start the pump, which also requires the motor running at industrial frequency to be re-started with speed. Under the above working conditions, when the motor is in abnormal conditions such as power failure or failure, the motor enters the idling running state. For permanent magnet synchronous motors with no-transmission control, after the motor enters the idling condition, the stator side current quickly decays to 0, and the no-transmission control algorithm cannot construct the rotor position and speed of the motor. The motor is in an out-of-control state. Due to the friction torque caused by the load torque and mechanical structure, the motor rotor speed will gradually decay. Even if the permanent magnet synchronous motor is powered off for a short time, it is impossible to estimate the motor rotor information at the moment of re-start based on the rotor speed and rotor position of the motor at the moment of power failure. Therefore, when the motor is powered on again, the rotor speed and rotor position of the motor are unknown. If the speed re-start of the permanent magnet synchronous motor is to be realized, the rotor position and rotor speed of the permanent magnet synchronous motor at the moment of speed re-start need to be accurately observed. Inaccurate estimation of the rotor position and rotor speed will cause a large difference between the back electromotive force and the inverter output voltage at the moment of motor re-start, resulting in a large impact current and impact torque, causing the motor to tremble after re-start, and in severe cases damaging the motor control system.

[0013] In summary, during the operation of permanent magnet synchronous motors, abnormal situations such as power outages and grid failures may occur, causing the motor to stop, which brings inconvenience and losses to production and use. Therefore, studying the speed re-throw technology of permanent magnet synchronous motors can effectively improve the reliability and operating efficiency of the motors, reduce downtime, and has important engineering application value. This technology can restart the motor quickly and smoothly in a short time, thereby avoiding time and economic losses in production and use.

[0014] In order to solve the above technical problems, the embodiment of the present application provides a method for re-starting a flywheel energy storage permanent magnet synchronous motor at high speed, comprising the following steps: S101, obtaining the current back electromotive force signal of the permanent magnet synchronous motor; S102, determining the current working state of the permanent magnet synchronous motor; S103, when the permanent magnet synchronous motor is in a normal working state, return to step S101 to achieve real-time and continuous monitoring of the permanent magnet synchronous motor; S104, when the permanent magnet synchronous motor is in an abnormal state, analyzing the current back electromotive force signal, and obtaining the current estimated rotation speed of the permanent magnet synchronous motor rotor through the waveform of the current back electromotive force signal; S105, matching a speed measurement strategy of the permanent magnet synchronous motor based on the current estimated rotation speed of the rotor; S106, calculating the current reliable speed and reliable position of the rotor according to the selected speed measurement strategy; S107, bringing the current reliable speed and reliable position of the rotor into the permanent magnet synchronous motor speed re-start program, so that the permanent magnet synchronous motor in the inert working condition is re-started with speed.

[0015] The following is a further introduction based on specific usage scenarios.

[0016] First, execute step S101 to obtain the current back electromotive force signal of the permanent magnet synchronous motor. It should be understood that the rotating rotor of the permanent magnet synchronous motor cuts the stator winding, and can generate a back electromotive force on the stator side whose direction and magnitude are related to the rotor speed. In the embodiment of the present application, a two-phase signal winding is arranged on the stator side winding of the permanent magnet synchronous motor, and the signal winding and the stator excitation winding are in the same slot. The functions of the signal winding and the stator excitation winding are independent of each other. Specifically, the signal winding is distributed on the stator core, and each phase diagnostic winding occupies three slots, and the two phases differ by 120 electrical degrees. The signal winding and the main winding coexist in the same slot, but the functions are independent. The signal winding The group is dedicated to the monitoring of no-load back electromotive force, and the main winding is used for the normal operation and power output of the generator. The air gap makes the amplitude of the signal winding and the excitation winding with the same number of turns inconsistent. In order to reduce abnormal signal interference and the signal pickup rate of the signal winding, the stator side excitation winding and the two signal windings are wound in the form of alternating forward and reverse rotation, and the number of turns of the signal winding is more than that of the excitation winding. The signal winding has the characteristics of high temperature resistance, good insulation, and friction resistance. It can cope with the high temperature, vibration, and strong magnetic field environment inside the motor. The signal winding is wound outside the excitation winding, and the number of turns is greater than the excitation winding, so that the signal amplitude transmitted by the signal winding is close to the voltage amplitude of the excitation winding; The rotor of the permanent magnet synchronous motor is a surface-mounted salient pole rotor. The salient pole rotor needs to have obvious magnetic poles in the permanent magnet synchronous motor. The characteristic of the salient pole rotor is that there are obviously protruding magnetic poles on the rotor core. These magnetic poles are usually composed of permanent magnets or electromagnets. The magnetic circuit of the salient pole rotor is asymmetric, which means that the magnetic circuit structures of the d-axis and the q-axis are different. This design makes the air gap magnetic field of the rotor have significant spatial harmonic components, which is convenient for the signal winding to detect. The current back electromotive force signal of the permanent magnet synchronous motor is obtained through the signal winding. The back electromotive force signal in the permanent magnet synchronous motor can be captured in real time through the signal winding without adding other sensors. The signal winding forms passive detection through its own induction, and its failure rate is significantly lower than that of other active sensors. The signal winding set on the stator side core can reduce the system volume, complexity and use cost, and improve reliability; S102, judging the current working state of the permanent magnet synchronous motor. In the usage scenario of the embodiment of the present application, the permanent magnet synchronous motor has two kinds of normal working state and abnormal working state. The main difference is whether it is necessary to calculate the current position and speed of the permanent magnet synchronous motor rotor. When the permanent magnet synchronous motor is in normal working state, there is no need to select the current position and speed of the permanent magnet synchronous motor rotor. When the permanent magnet synchronous motor is in abnormal working state, the rotor is in an idling condition when it needs to be stopped. At this time, it is necessary to calculate the current position and speed of the permanent magnet synchronous motor rotor, so as to realize the subsequent belt speed re-investment of the permanent magnet synchronous motor. The aforementioned abnormal working state of the motor includes a power-off shutdown state, a fault state, etc. In the embodiment of the present application, a data set can be established by first acquiring the back-electromotive force signal and the position and speed of the rotor under various typical abnormal states of the permanent magnet synchronous motor. Each possible back-electromotive force signal in the data set has a corresponding motor working state label and the position and speed of the rotor. The current back-electromotive force signal of the permanent magnet synchronous motor obtained is compared with the data set to find the back-electromotive force signal that matches it. The motor working state label and the position and speed of the rotor corresponding to the back-electromotive force signal in the data set can be obtained, and the permanent magnet synchronous motor state label obtained above is used as the current state of the permanent magnet synchronous motor. It should be understood that in the embodiment of the present application, by matching the current back-EMF signal obtained with the back-EMF signal in the data set, a comparison can be performed by calculating the overlap rate of the waveforms. When the obtained back-EMF signal does not match the back-EMF signal in the data set, it is determined that the permanent magnet synchronous motor is currently in a normal working state.

[0017] S103, when the permanent magnet synchronous motor is in a normal working state, there is no need to obtain and calculate the position and speed of the rotor, and the process returns to step S101 to achieve real-time and continuous monitoring of the permanent magnet synchronous motor; S104. When the permanent magnet synchronous motor is in an abnormal state, the current back electromotive force signal is analyzed, and the current estimated rotation speed of the permanent magnet synchronous motor rotor is obtained through the waveform of the current back electromotive force signal. In the embodiment of the present application, the current estimated rotation speed of the permanent magnet synchronous motor rotor can be obtained through the aforementioned data set. First, the obtained current back electromotive force signal of the permanent magnet synchronous motor is compared with the data set, and the overlap is calculated. The rotation speed of the permanent magnet synchronous motor rotor corresponding to the back electromotive force signal with the highest overlap in the data set is used as the current estimated rotation speed. S105, matching the speed measurement strategy of the permanent magnet synchronous motor based on the current estimated rotation speed of the rotor. In the embodiment of the present application, the possible speed interval of the rotor is first divided into a low speed interval and a high speed interval. The dividing point between the high speed interval and the low speed interval is 1500 revolutions per minute. The aforementioned speed measurement strategy is selected based on the speed interval to which the current estimated speed of the rotor belongs; In the embodiment of the present application, when the current estimated rotation speed of the rotor is in the low speed range, the current speed and position of the rotor are calculated based on the current back electromotive force signal waveform of the permanent magnet synchronous motor, and the current speed and position of the rotor calculated based on the current back electromotive force signal waveform are used as the current credible speed and credible position of the rotor; when the current estimated rotation speed of the rotor is in the high speed range, the secondary vector pulse method is used to calculate the current credible speed and credible position of the rotor; S106. According to the selected speed measurement strategy, the current reliable speed and reliable position of the rotor are calculated. When the current rotation speed of the rotor is low, the current reliable speed and reliable position of the rotor can be quickly output by analyzing the current back electromotive force signal waveform. The method of identifying the current position and speed of the rotor by the back electromotive force signal waveform has less error and high accuracy in the low speed range, and the calculation and output efficiency are high. The secondary vector pulse method is suitable for the measurement of the rotor position and speed in the high speed range. When the rotor is in the high speed range, the secondary vector pulse method has high measurement accuracy and small error of the position and speed. S107, bringing the current reliable speed and reliable position of the rotor into the permanent magnet synchronous motor speed re-start program, so that the permanent magnet synchronous motor in the inert working condition is re-started with speed.

[0018] In general, the embodiment of the present application performs preliminary rotor speed estimation by collecting the back electromotive force signal of the permanent magnet synchronous motor under abnormal working conditions, and then matches the appropriate rotor speed measurement strategy through the estimated rotor speed interval, thereby effectively avoiding the defect of high error of the rotor speed measurement strategy in certain intervals, so that the permanent magnet synchronous motor can quickly and accurately calculate the rotor position and speed under abnormal working conditions, so that the permanent magnet synchronous motor can be re-invested at a stable speed.

[0019] For example, the two signal windings provided in the embodiment of the present application, signal winding one and signal winding two are as follows: Figure 2 and Figure 3 As shown, the system as a whole includes a signal winding, a permanent magnet, a rotor core, a transmission shaft, and a permanent magnet sheath, wherein the signal winding includes a signal winding 1 and a signal winding 2. The secondary vector pulse method is used to observe the rotor speed and position. Figure 4 Topology diagram of a permanent magnet synchronous motor inverter using short-circuit current to inject zero vector voltage on the stator side. Figure 5 It represents the injection of zero voltage vector and its time interval by the secondary vector pulse method. When the motor is running in coasting mode, the inverter IGBTs are all in the off state. When the short-circuit current method is used, the inverter T2, T4, and T6 tubes are turned on (the lower bridge arm is short-circuited). By limiting the zero voltage vector injection time interval, only two zero voltage vector injections are required to estimate the motor speed and rotor position under coasting conditions. The following will specifically introduce how the secondary vector pulse method can be used to observe the motor speed and rotor position under coasting conditions.

[0020] The voltage equation of the permanent magnet synchronous motor (PMSM) in the dq coordinate system is Equation 1: When the motor is running in the idling condition, a zero voltage vector is injected into the lower bridge arm of the inverter, and the stator side of the motor is short-circuited. At this time, the terminal voltage of the motor is 0. Since the time constant τ of the motor stator winding is much larger than the zero voltage vector conduction time T, the stator resistance voltage drop can be ignored. REF _Ref180971645 \h \* MERGEFORMAT Formula 1 can be written as Formula 2: Defining the short-circuit current vector , because the initial current is 0, the change of motor rotor speed under the action of zero voltage vector is negligible, then use Laplace equation to solve public REF _Ref180971995 \h \* MERGEFORMAT formula 2 to get the short-circuit current vector The instantaneous value is formula 3: The detected three-phase short-circuit current is transformed into a two-phase stationary coordinate system by coordinate transformation, and the current components in the two stationary coordinate systems are obtained. , The angle in the stationary coordinate system is: Injecting zero voltage vector twice into the lower bridge arm of the inverter in a short period of time, it can be considered that the PMSM rotor speed is almost unchanged. From Equation 3, it can be seen that when the speed remains unchanged, the duration T of the two injected zero voltage vectors is kept the same, the angle between the two short-circuit current vectors in the rotating coordinate system is fixed, and the rotation frequency of the short-circuit current vector is consistent with the rotor frequency. From Equation 3, it can be seen that the rotation angle of the short-circuit current vector is the rotor rotation angle. The rotor angular velocity estimation value Equation 5 can be obtained by calculation: In formula 5, N is the number of revolutions of the rotor within T+τ12, ωreal is the real electrical angular velocity of the rotor, ωest is the estimated electrical angular velocity, τ12 is the time interval between two injections of the zero voltage vector, θ11, θ12 are , Angle in the stationary coordinate system.

[0021] It can be seen from Formula 5 that when using the secondary vector pulse method, in order to accurately observe the rotor angular velocity and rotation direction, it is necessary to ensure that the actual number of motor rotations N=0 within the time period T+τ12, that is, within the time period T+τ12, the actual rotation angular velocity of the motor is less than 180°. Therefore, in order to accurately estimate the motor rotor rotation angular velocity, the selection of the injected zero vector voltage width T and the two zero vector voltage intervals τ12 are constrained by the formula, Formula 6: Where ωmax is the maximum speed of the PMSM, therefore, τ12 must satisfy equation 7: The rotor position estimation is based on the rotor angular velocity estimation in the rotor angular velocity estimation method. Figure 7 It represents the relationship between the short-circuit current vector and the three-phase coordinate system. The angle θ0 between the short-circuit current vector and the rotating coordinate system can be obtained by 7777REF _Ref180972670 \h \* MERGEFORMAT Formula 3: from Figure 7 It can be seen that the initial position of the permanent magnet synchronous motor rotor in the three-phase stationary coordinate system is: The flywheel energy storage device motor can be restarted by injecting the rotor position information into the belt speed re-throw program.

[0022] As a feasible specific implementation method of the embodiment of the present application, the current credible speed and credible position of the rotor calculated by the secondary vector pulse method are compared with the speed of the permanent magnet synchronous motor rotor corresponding to the current back electromotive force signal in the data set; Based on the comparison results, when the deviation rate between the current credible speed and credible position of the rotor calculated by the secondary vector pulse method and the speed of the permanent magnet synchronous motor rotor corresponding to the current back-electromotive force signal in the data set is greater than the threshold, the current credible speed and credible position of the rotor calculated by the secondary vector pulse method will be used as the speed of the permanent magnet synchronous motor rotor corresponding to the current back-electromotive force signal in the data set, thereby realizing the dynamic update of the data set, so that the rotor position information corresponding to the back-electromotive force signal in the data set is more in line with the rotor information of the permanent magnet synchronous motor under the actual operating conditions.

[0023] Furthermore, the current speed and position of the rotor calculated according to the current back electromotive force signal waveform are used as the current reliable speed and reliable position of the rotor and input into the belt speed re-throwing program to obtain the working state of the permanent magnet synchronous motor after the belt speed re-throwing; Subsequently, when the permanent magnet synchronous motor is in normal working state after speed re-start, the current speed and position of the rotor calculated based on the current back-EMF signal waveform will be used as the permanent magnet synchronous motor rotor speed corresponding to the back-EMF signal in the data set, and the data set will be dynamically updated. Therefore, when the same motor working condition is encountered next time, the correct rotor position and speed information can be quickly obtained by comparing the data set, making the rotor information acquisition efficiency higher.

[0024] In the embodiment of the present application, after the position and speed information of the rotor is input into the belt speed re-throwing program, that is, after the current reliable speed and reliable position of the rotor are brought into the permanent magnet synchronous motor belt speed re-throwing program, the current back electromotive force signal of the permanent magnet synchronous motor is obtained; Then, based on the current back electromotive force signal, it is determined whether the permanent magnet synchronous motor is in an abnormal state after the belt speed is re-started; Then, when the permanent magnet synchronous motor is in an abnormal state after the belt speed is re-started, the speed measurement strategy of the permanent magnet synchronous motor is matched based on the current estimated rotation speed of the rotor to recalculate the rotor speed and position of the synchronous motor. By obtaining the current state and rotor position information of the permanent magnet synchronous motor at one time, the remedy for the failure of the belt speed re-start is achieved, so that the permanent magnet synchronous motor can quickly stabilize its operation.

[0025] The embodiments of this specific implementation method are all preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. Therefore, all equivalent changes made based on the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for re-starting a flywheel energy storage permanent magnet synchronous motor with a belt speed, characterized in that: include: Get the current back electromotive force signal of the permanent magnet synchronous motor; Determine the current working state of the permanent magnet synchronous motor; When the permanent magnet synchronous motor is in an abnormal state, the current back electromotive force signal is analyzed to obtain the current estimated rotation speed of the permanent magnet synchronous motor rotor; A speed measurement strategy for matching a permanent magnet synchronous motor based on the current estimated rotation speed of the rotor; According to the selected speed measurement strategy, calculate the current reliable speed and reliable position of the rotor; The current reliable speed and reliable position of the rotor are brought into the permanent magnet synchronous motor speed re-start procedure.

2. A belt speed re-start method for a flywheel energy storage permanent magnet synchronous motor according to claim 1, characterized in that: A two-phase signal winding is arranged on the stator side winding of the permanent magnet synchronous motor. The signal winding and the stator winding are in the same slot. The signal winding and the stator winding are independent of each other. The current back electromotive force signal of the permanent magnet synchronous motor is obtained through the signal winding.

3. A belt speed re-start method for a flywheel energy storage permanent magnet synchronous motor according to claim 2, characterized in that: Determining the current working state of the permanent magnet synchronous motor includes: Obtain the back electromotive force signal and rotor position and speed of the permanent magnet synchronous motor under various typical abnormal conditions and establish a data set; The acquired current back electromotive force signal of the permanent magnet synchronous motor is compared with the data set to obtain the permanent magnet synchronous motor working state label corresponding to the current back electromotive force signal in the data set.

4. A belt speed re-start method for a flywheel energy storage permanent magnet synchronous motor according to claim 3, characterized in that: The step of obtaining the current estimated rotation speed of the permanent magnet synchronous motor rotor comprises: Compare the acquired current back electromotive force signal of the permanent magnet synchronous motor with the data set to obtain the position and speed of the permanent magnet synchronous motor rotor corresponding to the current back electromotive force signal in the data set; The rotation speed of the permanent magnet synchronous motor rotor corresponding to the current back electromotive force signal in the data set is taken as the current estimated rotation speed.

5. A belt speed re-start method for a flywheel energy storage permanent magnet synchronous motor according to claim 4, characterized in that: The speed measurement strategy of matching the permanent magnet synchronous motor based on the current estimated rotation speed of the rotor includes: Divide the possible speed range of the rotor into a low speed range and a high speed range; Based on the current estimated rotation speed of the rotor, determining the rotation speed range in which the current rotation speed of the rotor is located; When the current estimated rotation speed of the rotor is in a low speed range, the current speed and position of the rotor are calculated based on the current back electromotive force signal waveform of the permanent magnet synchronous motor, and the current speed and position of the rotor calculated based on the current back electromotive force signal waveform are used as the current reliable speed and reliable position of the rotor; When the current estimated rotation speed of the rotor is in the high-speed range, the secondary vector pulse method is used to calculate the current reliable rotation speed and reliable position of the rotor.

6. A belt speed re-start method for a flywheel energy storage permanent magnet synchronous motor according to claim 5, characterized in that: Also includes: The current reliable speed and reliable position of the rotor calculated by the secondary vector pulse method are compared with the speed of the permanent magnet synchronous motor rotor corresponding to the current back electromotive force signal in the data set; When the deviation rate between the current credible speed and credible position of the rotor calculated by the secondary vector pulse method and the speed of the permanent magnet synchronous motor rotor corresponding to the current back electromotive force signal in the data set is greater than a threshold, the current credible speed and credible position of the rotor calculated by the secondary vector pulse method will be used as the speed of the permanent magnet synchronous motor rotor corresponding to the current back electromotive force signal in the data set, and the data set will be updated.

7. A belt speed re-start method for a flywheel energy storage permanent magnet synchronous motor according to claim 6, characterized in that: Also includes: After the current rotor speed and position calculated according to the current back electromotive force signal waveform are input into the belt speed re-throwing program as the rotor current reliable speed and reliable position, the working state of the permanent magnet synchronous motor after the belt speed re-throwing is obtained; When the permanent magnet synchronous motor is in normal working state after the speed is restored, the current speed and position of the rotor calculated according to the current back electromotive force signal waveform are used as the permanent magnet synchronous motor rotor speed corresponding to the back electromotive force signal in the data set to update the data set.

8. A belt speed re-start method for a flywheel energy storage permanent magnet synchronous motor according to claim 7, characterized in that: Also includes: After the current reliable speed and reliable position of the rotor are brought into the permanent magnet synchronous motor speed re-throwing program, the current back electromotive force signal of the permanent magnet synchronous motor is obtained; Based on the current back electromotive force signal, it is determined whether the permanent magnet synchronous motor is in an abnormal state after the speed is restarted; When the permanent magnet synchronous motor is in an abnormal state after the speed is re-started, the speed measurement strategy of the permanent magnet synchronous motor is matched based on the current estimated rotation speed of the rotor to recalculate the rotor speed and position of the synchronous motor.

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