Method for runaway start-up of permanent magnet synchronous motor using vector control without position sensor

Abstract

A method for runaway start-up of a permanent magnet synchronous motor using vector control without position sensor, comprising: by using a rotating speed tracking unit, during runaway start-up, taking the real-time operating rotating speed Spd_act of a motor as a current rotating speed instruction Spd_ref, setting Iq_ref and Id_ref to be 0, carrying out field oriented control (FOC) processing until a q-axis real-time current Iq is smaller than a set q-axis current Iq0, and in this case, quitting the rotating speed tracking unit and recording the current rotating speed instruction Spd_ref; an acceleration adaptive control unit comparing the current rotating speed instruction Spd_ref with a runaway start-up target rotating speed Spd_target, and if the Spd_ref is smaller than the Spd_target, setting acceleration a to be equal to a0; and if the Spd_ref is greater than the Spd_target, calculating a voltage error error, and then performing PI processing on the voltage error error to output the acceleration a. Therefore, reverse rotation power generation of the motor is effectively inhibited, the risk of overvoltage of a motor controller is avoided, the reliability is high, the logic algorithm is simple, and the current rotating speed of the motor can be seamlessly connected.

Description

Method for flying start of position sensorless vector controlled permanent magnet synchronous motor Technical field:

[0001] The invention relates to a method for flying start of a position sensorless vector-controlled permanent magnet synchronous motor. Background technology:

[0002] Permanent magnet synchronous motors use vector control to fully unleash the efficiency of the motor and ensure quiet operation, and are gradually being used in fan and water pump systems.

[0003] Starting a motor using sensorless vector control has always been a challenge in the industry. This is because the sensorless algorithm based on the motor model has difficulty accurately identifying the motor's speed and position at low speeds or when stationary. To overcome this problem, open-loop current forced drag is usually used during motor startup to force the rotor to reach a certain speed according to a predetermined acceleration, and then gradually switch to closed-loop FOC field-oriented control.

[0004] Figure 1 is a flow chart of the current FOC field-oriented control of a sensorless vector-controlled permanent magnet synchronous motor. In the figure, the current speed command Spd_ref is compared with the motor's real-time speed Spd_act and then PI processing is performed to obtain the q-axis current Iq_ref, which is the PI processing of the speed loop. The q-axis injected current Iq_ref is compared with the q-axis real-time current Iq and then PI processing is performed to obtain the q-axis voltage input vector Uq, which is the first current loop. The d-axis current Id_ref is equal to 0 and is compared with the d-axis real-time current Id and then PI processing is performed to obtain the d-axis voltage input vector Ud, which is the second current loop. The d-axis voltage input vector Ud and the q-axis voltage input vector Uq are transformed into the input of the SVPWM through coordinate transformation. The output of the SVPWM passes through a three-phase inverter to obtain the phase currents Ia, Ib, and Ic of the motor's three-phase coil windings. The phase currents Ia, Ib, and Ic are transformed into the q-axis real-time current Iq and the d-axis real-time current Id through coordinate transformation. The figure also shows a position and speed observer. The phase currents Ia, Ib, Ic and the DC bus voltage serve as input data for the position and speed observer. The position and speed observer outputs the real-time speed Spd_act of the motor and the coordinate transformation angle θ.

[0005] The sensorless vector control of permanent magnet synchronous motor (PMSM) may encounter the problem of flying start in actual use. The so-called flying start is usually called forward or reverse start on the fan - that is, the motor rotates forward or reverse at a certain speed before starting. For example, the outdoor unit of the air conditioner usually uses a permanent magnet synchronous motor as the heat exchange of the outdoor fan. During use, the motor is often stopped and started according to the logic instructions of the air conditioning system. When restarting, the motor rotor may be rotating in the reverse or forward direction due to external air flow pressure or fan inertia. Because there is no position sensor at the time of starting, it is not known whether the motor is rotating. If open-loop forced start is directly used, because the speed and position cannot be identified, it is bound to cause the motor to be in generator operation state, which will cause the DC bus voltage to pump up, either triggering overvoltage protection or causing overvoltage damage to the power device. Therefore, special treatment is required for the flying start of the motor.

[0006] The patent number is: 201811120169.5, the patent name is: Starting control method and device for DC fan, the invention patent of outdoor unit proposes a better solution. It is necessary to inject zero voltage before starting the motor (in the case of a three-phase bridge circuit, the upper and lower bridge PWM = 50% duty cycle) to confirm the phase current of the motor, so as to confirm the initial speed and rotation direction of the motor, and then perform different types of starting modes according to the speed. This solution has two problems. First, the injection of 0 voltage vector will cause a larger phase current when the rotor speed is high, and this current is uncontrollable. Second, different processing modes must be entered according to different speeds, which increases the difficulty of processing.

[0007] Summary of the invention:

[0008] The purpose of the present invention is to provide a method for flying start of a position sensorless vector controlled permanent magnet synchronous motor, which mainly solves the technical problems in the prior art of the method for flying start of a position sensorless vector controlled permanent magnet synchronous motor, such as complex logic leading to complex algorithm, uncontrollable current control causing the motor to sometimes run in a power generation state, causing overvoltage of the inverter to damage power devices, and low reliability.

[0009] The purpose of the present invention is achieved through the following technical solutions:

[0010] A method for flying start of a position sensorless vector controlled permanent magnet synchronous motor is characterized by comprising the following steps:

[0011] Speed ​​tracking: When the flying car is started, the speed tracking unit is used to take the real-time speed Spd_act of the motor as the current speed command Spd_ref, set Iq_ref and Id_ref to 0, and perform FOC magnetic field oriented control to reduce the real-time operating current;

[0012] Acceleration adaptive control: The acceleration adaptive control unit is used to determine whether the start is with a tailwind or headwind. If it is a headwind start, the acceleration a is set to a0, where a0 is the set acceleration. If it is a tailwind start, the voltage error error is calculated as the maximum bus voltage minus the real-time bus voltage value. The voltage error error is then processed by PI and output as acceleration a.

[0013] Where Iq_ref is the current reference value of the q-axis, Id_ref is the current reference value of the d-axis, the speed Spd_act is the real-time speed of the motor, and the speed command Spd_ref is the current speed command given in the speed loop.

[0014] The above-mentioned speed tracking unit and acceleration adaptive control unit are two units added on the basis of the FOC field-oriented control framework, where:

[0015] When the car is started, the speed tracking unit uses the real-time speed Spd_act of the motor as the current speed command Spd_ref, sets Iq_ref and Id_ref to 0, and performs FOC magnetic field oriented control processing until the q-axis real-time current Iq is less than the set q-axis current Iq0. Then the speed tracking unit exits and records the current speed command Spd_ref. Iq_ref is compared with the real-time current Iq and PI processing is performed to form a current loop. Id_ref is compared with the real-time current Id of the d-axis and PI processing is performed to form another current loop.

[0016] The acceleration adaptive control unit compares the current speed command Spd_ref recorded when exiting the speed tracking unit with the flying start target speed Spd_target. If Spd_ref is less than Spd_target, the acceleration a is set to a0, where a0 is the set acceleration. If Spd_ref is greater than Spd_target, the voltage error error is calculated as the maximum bus voltage minus the real-time bus voltage value. The voltage error error is then processed by PI and output as acceleration a.

[0017] The acceleration a and the current speed command Spd_ref recorded when exiting the speed tracking unit are used to perform FOC magnetic field oriented control to gradually approach the flying start target speed Spd_target, and finally make the real-time operating speed of the permanent magnet synchronous motor equal to the flying start target speed Spd_target.

[0018] The above method takes the current speed command Spd_ref recorded when exiting the speed tracking unit as the starting point, takes acceleration a as the step size, gradually increases the current speed command Spd_ref to perform FOC magnetic field oriented control and gradually approaches the flying car starting target speed Spd_target.

[0019] If Spd_ref is greater than Spd_target, the acceleration a is calculated as follows: a=kp×error+∫(ki×error)dt

[0020] Where Kp Ki are the parameters of the PI controller.

[0021] The specific steps of the above-mentioned flying car start are as follows:

[0022] S1: Initialize all parameters and set the speed tracking flag to 1;

[0023] S2: Read the bus voltage Vbus, phase current and startup target speed Spd_target, and calculate the real-time speed Spd_act, q-axis real-time current Iq and d-axis real-time current Id of the permanent magnet synchronous motor;

[0024] S3: Determine whether the speed tracking flag is 1; if so, go to S4; if not, go to S6;

[0025] S4: Speed ​​tracking: Use the real-time motor speed Spd_act as the current speed command Spd_ref, and determine whether the q-axis real-time current Iq is less than the set q-axis current Iq0. If not, proceed to S5; if so, set the speed tracking flag Flag to 0, record the current speed command Spd_ref, and proceed to S6;

[0026] S5: Set Iq_ref and Id_ref to 0, perform FOC magnetic field oriented control processing, and return to S2;

[0027] S6: Acceleration adaptive control: Is the current speed command Spd_ref greater than the target speed Spd_target? If not, set acceleration a = a0, where a0 is the set acceleration. If so, calculate the voltage error error, which is equal to the maximum bus voltage minus the real-time bus voltage value. Then, perform PI processing on the voltage error error to obtain the acceleration a, and proceed to step 7.

[0028] S7: Recalculate the current speed command Spd_ref using acceleration a, compare the current speed command Spd_ref with the real-time speed Spd_act of the motor, perform PI processing, perform FOC magnetic field oriented control processing, and return to S2.

[0029] When the FOC magnetic field oriented control is performed using the acceleration a and the current speed command Spd_ref recorded when exiting the speed tracking unit, Id_ref is generated by the MTPA unit operation.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1) The flying start method of the present invention automatically tracks the speed during startup and automatically controls the acceleration of the permanent magnet synchronous motor (PMSM), effectively suppressing the reverse rotation of the motor to generate electricity, avoiding the risk of overvoltage in the motor controller, and preventing damage to power devices caused by overvoltage in the inverter, thereby achieving high reliability.

[0032] 2) The flying start method of the present invention has a simple logic algorithm. By controlling the current and speed, it can ensure that the current is in a controllable state during startup and can seamlessly connect to the current speed of the motor without noise caused by sudden changes in speed.

[0033] 3) Other advantages of the present invention are further described in the embodiment section. Description of the drawings:

[0034] FIG1 is a schematic diagram showing the principle of FOC field oriented control of an existing position sensorless vector controlled permanent magnet synchronous motor.

[0035] Figure 2 is a schematic diagram of the principle of a position sensorless vector controlled permanent magnet synchronous motor.

[0036] FIG3 is a diagram showing the relationship between various coordinate systems of a permanent magnet synchronous motor vector control;

[0037] FIG4 is a perspective view of a permanent magnet synchronous motor according to the present invention;

[0038] FIG5 is a perspective view of a motor controller of a permanent magnet synchronous motor according to the present invention;

[0039] FIG6 is a cross-sectional view of a permanent magnet synchronous motor according to the present invention;

[0040] 7 is a block diagram of a motor controller for a permanent magnet synchronous motor according to the present invention;

[0041] FIG8 is a circuit diagram corresponding to FIG7;

[0042] FIG9 is a flow chart of vector control of a permanent magnet synchronous motor according to the present invention;

[0043] FIG10 is a program control flow chart of the present invention;

[0044] FIG11 is a program control flow chart of the acceleration adaptive control unit in FIG10 ;

[0045] FIG12 is a diagram showing changes in speed, voltage, and acceleration parameters during downwind startup of the present invention;

[0046] FIG13 is a diagram showing current changes during downwind startup of the present invention;

[0047] FIG14 is a diagram showing changes in speed, voltage, and acceleration parameters of the present invention when starting against wind;

[0048] FIG15 is a diagram showing current changes during headwind startup of the present invention. Specific implementation method:

[0049] The present invention will be further described in detail below through specific embodiments in conjunction with the accompanying drawings.

[0050] As shown in Figure 2, the basic working principle of the position sensorless vector controlled permanent magnet synchronous motor is briefly described (textbooks have detailed descriptions). The permanent magnet synchronous motor is regarded as the result of the interaction between the rotating magnetic field of the stator and the rotating magnetic field of the rotor. There are two coordinate systems in the figure, one is the rotor rotating coordinate system dq axis; the other is the stator stationary coordinate system ABC coordinate system (which can be converted into a coordinate system with αβ perpendicular to each other); the rotor can be regarded as rotating at a speed wr due to the action of the excitation current if, and the stator can be regarded as rotating at a speed ws due to the action of the excitation current is. The resultant vector of the stator in the figure is S; according to the calculation formula of the electromagnetic torque: T e =P0·ψ f ×i q ------(1)

[0051] P0 is the number of pole pairs of the motor (constant), Ψf is the magnetic flux generated by the excitation current if. Since the rotor is a permanent magnet rotor, if=0, Ψf becomes a constant, and the formula for electromagnetic torque becomes: e =K×i q ------(2)

[0052] K is a constant, and the electromagnetic torque Te of the permanent magnet synchronous motor is only related to the q-axis current.

[0053] As shown in Figure 3, the stator stationary coordinate system ABC is replaced by a mutually perpendicular coordinate system αβ. The stator stationary coordinate system is the αβ coordinate system, and the rotor rotating coordinate system is the dq coordinate system. The angle between the αβ coordinate system and the dq coordinate system is θ.

[0054] As shown in Figures 4, 5 and 6, for example: assuming that the present invention is a three-phase permanent magnet synchronous motor with position sensorless vector control, it consists of a motor controller 2 and a motor monomer 1 (indicated by M in Figure 8). The motor monomer 1 includes a stator assembly 12, a rotor assembly 13 and a housing assembly 11. The stator assembly 13 is installed on the housing assembly 11, and the rotor assembly 13 is sleeved on the inner side or the outer side of the stator assembly 12. The motor controller 2 includes a control box 22 and a control circuit board 21 installed in the control box 22. The control circuit board 21 generally includes a power supply circuit, a microprocessor, a bus voltage detection circuit, and an inverter. The power supply circuit supplies power to each part of the circuit. The bus voltage detection circuit inputs the DC bus voltage Vbus to the microprocessor. The microprocessor controls the inverter. The inverter controls the on and off of the coil windings of each phase of the stator assembly 12. The microprocessor adopts a single-chip microcomputer MCU.

[0055] As shown in Figures 7 and 8, assume that the phase current detection circuit of a three-phase brushless DC permanent magnet synchronous motor inputs the currents Ia, Ib, and Ic of each phase into a microprocessor. The AC input (AC INPUT) passes through a full-wave rectifier circuit composed of diodes D7, D8, D9, and D10, and outputs a DC bus voltage Vbus at one end of capacitor C1. This DC bus voltage Vbus is related to the input AC voltage. The microprocessor then inputs a PWM signal with a fixed duty cycle to the inverter. The inverter consists of electronic switches Q1, Q2, Q3, Q4, Q5, and Q6. The control terminals of these switches are controlled by six PWM signals (P1, P2, P3, P4, P5, and P6) output by the microprocessor, respectively. A PWM signal with a fixed duty cycle is a PWM signal with a duty cycle of 1:1.

[0056] As shown in Figures 3 and 9, the d-axis real-time current Id and the q-axis real-time current Iq can be calculated using the currents Ia, Ib, and Ic of each phase. The angle θ between the αβ coordinate system and the dq coordinate system and the real-time speed Spd_act of the permanent magnet synchronous motor can be obtained using the position and speed observer. The motor microprocessor can be equipped with a flux observer. The magnetic flux φ can be calculated using parameters such as the d-axis real-time current Id, the q-axis real-time current Iq, the angle θ, the motor resistance, the inductance, and the real-time speed Spd_act of the motor. These are all recorded in textbooks and will not be described here.

[0057] As shown in FIG9 , the method for flying start of a position sensorless vector controlled permanent magnet synchronous motor according to the present invention is characterized in that it includes the following steps:

[0058] Speed ​​tracking: When the flying car is started, the speed tracking unit is used to take the real-time speed Spd_act of the motor as the current speed command Spd_ref, set Iq_ref and Id_ref to 0, and perform FOC magnetic field oriented control to reduce the real-time operating current;

[0059] Acceleration adaptive control: The acceleration adaptive control unit is used to determine whether the start is with a tailwind or headwind. If it is a headwind start, the acceleration a is set to a0, where a0 is the set acceleration. If it is a tailwind start, the voltage error error is calculated as the maximum bus voltage minus the real-time bus voltage value. The voltage error error is then processed by PI and output as acceleration a.

[0060] Where Iq_ref is the current reference value of the q-axis, Id_ref is the current reference value of the d-axis, the speed Spd_act is the real-time speed of the motor, and the speed command Spd_ref is the current speed command given in the speed loop.

[0061] The above-mentioned speed tracking unit and acceleration adaptive control unit are two units added on the basis of the FOC field-oriented control framework, where:

[0062] When the car is started, the speed tracking unit uses the real-time speed Spd_act of the motor as the current speed command Spd_ref, sets Iq_ref and Id_ref to 0, and performs FOC magnetic field oriented control processing until the q-axis real-time current Iq is less than the set q-axis current Iq0. Then the speed tracking unit exits and records the current speed command Spd_ref. Iq_ref is compared with the real-time current Iq and PI processing is performed to form a current loop. Id_ref is compared with the real-time current Id of the d-axis and PI processing is performed to form another current loop.

[0063] The acceleration adaptive control unit compares the current speed command Spd_ref recorded when exiting the speed tracking unit with the flying start target speed Spd_target. If Spd_ref is less than Spd_target, the acceleration a is set to a0, where a0 is the set acceleration. If Spd_ref is greater than Spd_target, the voltage error error is calculated as the maximum bus voltage minus the real-time bus voltage value. The voltage error error is then processed by PI and output as acceleration a.

[0064] Using acceleration a and the current speed command Spd_ref recorded when exiting the speed tracking unit, Field Oriented Control (FOC) is used to gradually approach the target speed Spd_target for the start of a flying start, ultimately ensuring that the permanent magnet synchronous motor's real-time operating speed equals the target speed Spd_target for the start of a flying start. The main function of the acceleration adaptive control unit is to use the current speed command Spd_ref recorded when exiting the speed tracking unit as the starting point, and using acceleration a as the step size to gradually increase the current speed command Spd_ref, using Field Oriented Control (FOC) to gradually approach the target speed Spd_target for the start of a flying start.

[0065] The present invention adds a speed tracking unit, an acceleration adaptive control unit, and an MTPA unit to the FOC field-oriented control framework for flying start. The so-called flying start is usually called a headwind start or a headwind start on a wind turbine, that is, the motor rotates forward or reverse at a certain speed before starting. When the position sensorless vector-controlled permanent magnet synchronous motor receives a flying start command, it first performs speed tracking, that is, starts the speed tracking unit, uses the real-time running speed Spd_act of the motor as the current speed command Spd_ref, and starts the speed tracking unit to set Iq_ref and Id_ref to 0. Perform FOC magnetic field oriented control processing until the q-axis real-time current Iq is less than the set q-axis current Iq0, then exit the speed tracking unit and record the current speed command Spd_ref, where Iq_ref is the q-axis current reference value, Iq_ref is compared with the real-time current Iq to perform PI processing to form a current loop, and Id_ref is the d-axis current reference value, Id_ref is compared with the d-axis real-time current Id to perform PI processing to form another current loop; set the q-axis current Iq0 to a safe limit current to ensure that the d-axis real-time current Id and the q-axis real-time current Iq are not too large when preparing for a speed mutation.

[0066] If Spd_ref is greater than Spd_target, the acceleration a is calculated as follows: a=kp×error+∫(ki×error)dt

[0067] Where Kp Ki are the parameters of the PI controller.

[0068] The specific steps of the method for flying start of a position sensorless vector controlled permanent magnet synchronous motor of the present invention are as follows, as shown in Figures 10 and 11:

[0069] S1: Initialize all parameters and set the speed tracking flag to 1;

[0070] S2: Read the bus voltage Vbus, phase current and startup target speed Spd_target, and calculate the real-time speed Spd_act, q-axis real-time current Iq and d-axis real-time current Id of the permanent magnet synchronous motor;

[0071] S3: Determine whether the speed tracking flag is 1; if so, go to S4; if not, go to S6;

[0072] S4: Speed ​​tracking: Use the real-time motor speed Spd_act as the current speed command Spd_ref, and determine whether the q-axis real-time current Iq is less than the set q-axis current Iq0. If not, proceed to S5; if so, set the speed tracking flag Flag to 0, record the current speed command Spd_ref, and proceed to S6;

[0073] S5: Set Iq_ref and Id_ref to 0, perform FOC field oriented control, and return to S2;

[0074] S6: Acceleration adaptive control: Is the current speed command Spd_ref greater than the target speed Spd_target? If not, set acceleration a = a0, where a0 is the set acceleration. If so, calculate the voltage error error, which is equal to the maximum bus voltage minus the real-time bus voltage value. Then, perform PI processing on the voltage error error to obtain the acceleration a, and proceed to step 7.

[0075] S7: Recalculate the current speed command Spd_ref using acceleration a, compare the current speed command Spd_ref with the real-time speed Spd_act of the motor, perform PI processing, perform FOC magnetic field oriented control processing, and return to S2.

[0076] When the acceleration a and the current speed command Spd_ref recorded when exiting the speed tracking unit are used for FOC magnetic field oriented control, Id_ref is generated by the MTPA unit. The MTPA unit calculates the maximum torque per ampere. The purpose is to determine the required Id_ref when the maximum torque can be obtained per ampere. This is described in textbooks or patent documents and is prior art, so it will not be described here. When exiting the speed tracking unit, the q-axis current Iq_ref is determined by the difference between the current speed command Spd_ref and the real-time speed Spd_act of the motor. The speed difference err_spd = Spd_ref - Spd_act, and the speed loop PI can be used to obtain Iq_ref: Iq_ref = kp × err_spd + ∫ (ki × err_spd) dt

[0077] Kp Ki are the parameters of the PI controller.

[0078] The FOC magnetic field oriented control is performed using the Iq_ref output by the speed loop PI and the Id_ref generated by the MTPA unit operation to obtain the maximum torque per ampere effect.

[0079] As shown in Figures 12 and 13, a motor using a method for flying start of a position sensorless vector controlled permanent magnet synchronous motor is tested. In the case of tailwind (high-speed tailwind start 300 Hz), flying start may cause instantaneous voltage increase. The solution of the present invention is:

[0080] 1. First perform speed tracking, that is, start the speed tracking unit, use the real-time running speed Spd_act of the motor as the current speed command Spd_ref, set Iq_ref and Id_ref to 0, and monitor the real-time current Iq value of the q axis at the same time. If the Iq value is small enough, exit the downwind phase lock (that is, exit the speed tracking unit) and enter the normal speed setting, that is, enter the acceleration adaptive control unit.

[0081] 2. After the voltage rises during the speed tracking process, the actual speed decreases, and the set current speed command Spd_ref also decreases accordingly;

[0082] 3. During the speed tracking process, the acceleration is calculated as 0 by PI. When entering the normal speed setting, the real-time value of the acceleration is adjusted according to the voltage error PI.

[0083] 4. After the acceleration gradually recovers, the current speed command Spd_ref gradually catches up with the startup target speed Spd_target.

[0084] In the test diagram for a high-speed tailwind start (300 Hz) (Figure 12), the top graph shows the target speed Spd_target and the feedback (the motor's real-time running speed Spd_act), the middle graph shows the bus voltage, and the bottom graph shows the acceleration change. Significant voltage fluctuations (which can be absorbed by the capacitor) occur only during speed tracking. After speed tracking is complete, the motor accelerates smoothly to the given target speed Spd_target. In Figure 13, the maximum current fluctuation during the flying start process is below 1.267A, fully meeting the design requirements.

[0085] As shown in Figures 14 and 15, a motor using a method for flying start of a position sensorless vector controlled permanent magnet synchronous motor is tested. In the case of headwind (high-speed headwind start 300 Hz), flying start may cause instantaneous voltage increase. The solution of the present invention is:

[0086] 1. First, perform speed tracking, that is, start the speed tracking unit, use the real-time speed Spd_act of the motor as the current speed command Spd_ref, set Iq_ref and Id_ref to 0, and monitor the real-time current Iq value of the q axis. If the Iq value is small enough, exit the downwind phase lock (that is, exit the speed tracking unit), and the estimated speed (that is, the real-time speed Spd_act of the motor) will gradually decrease. This is braking, and the voltage will rise slightly.

[0087] 2. The voltage will rise at the moment of startup. As the speed is successfully tracked, the acceleration becomes 0 and Iq will decrease. When the Iq value is less than the threshold (that is, the set q-axis current Iq0), the deceleration begins to increase and the positive torque control mode is entered. The voltage may rise again. When the real-time running speed Spd_act of the motor is close to 0, the acceleration is limited to the minimum. After forward rotation, it enters the normal operation mode, that is, it starts to accelerate with acceleration a=a0 until the current speed command Spd_ref gradually catches up with the startup target speed Spd_target.

[0088] As shown in Figure 14, the flying start process only generates a significant voltage (which can be absorbed by the capacitor) during speed tracking. After tracking is complete, deceleration begins from -300 Hz. During deceleration, the bus voltage is limited to approximately 20V, and accordingly, the acceleration decreases from 500 Hz per second to approximately 200 Hz per second. After the bus voltage drops, the acceleration gradually transitions to the set acceleration a0. It then enters the low-speed section, crossing the zero point, and then accelerates to 300 Hz according to the set acceleration. As shown in Figure 15, the maximum current fluctuation during the flying start process is below 933 mA, fully meeting the design requirements.

[0089] The flying start method of the present invention utilizes a speed tracking unit to automatically track the speed during startup and automatically controls the acceleration of the permanent magnet synchronous motor, effectively suppressing the motor's reverse rotation to generate electricity, avoiding the risk of overvoltage in the motor controller and overvoltage damage to the inverter's power components, resulting in high reliability. The flying start method of the present invention utilizes a simple logic algorithm. By controlling current and speed, it ensures that the current is controllable during startup and seamlessly connects to the motor's current speed, eliminating noise caused by sudden speed changes.

[0090] The above embodiments are preferred implementations of the present invention, but the implementations of the present invention are not limited thereto. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention are equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for flying start of a position sensorless vector-controlled permanent magnet synchronous motor, characterized in that: The steps include: Speed ​​tracking: When the flying car is started, the speed tracking unit is used to take the real-time speed Spd_act of the motor as the current speed command Spd_ref, and Iq_ref and Id_ref are set to 0, and FOC magnetic field oriented control is performed to reduce the real-time operating current; Acceleration adaptive control: Use the acceleration adaptive control unit to determine whether it is a headwind start or a tailwind start. If it is a headwind start, set the acceleration a=a0, where a0 is the set acceleration. If it is a tailwind start, calculate the voltage error error equal to the maximum value of the bus voltage minus the real-time value of the bus voltage, and then perform PI processing on the voltage error error to output the acceleration a. Where Iq_ref is the current reference value of the q-axis, Id_ref is the current reference value of the d-axis, the speed Spd_act is the real-time running speed of the motor, and the speed command Spd_ref is the current speed command given in the speed loop.

2. The method for flying start of a position sensorless vector-controlled permanent magnet synchronous motor according to claim 1, characterized in that: The speed tracking unit and the acceleration adaptive control unit are two units added on the basis of the FOC field oriented control framework, where: When the speed tracking unit starts, the real-time speed Spd_act of the motor is used as the current speed command Spd_ref, and Iq_ref and Id_ref are set to 0, and FOC magnetic field oriented control is performed until the q-axis real-time current Iq is less than the set q-axis current Iq0, then the speed tracking unit is exited and the current speed command Spd_ref is recorded, Iq_ref is compared with the real-time current Iq to perform PI processing to form a current loop, and Id_ref is compared with the d-axis real-time current Id to perform PI processing to form another current loop; The acceleration adaptive control unit compares the current speed command Spd_ref recorded when exiting the speed tracking unit with the flying car start target speed Spd_target. If Spd_ref is less than Spd_target, the acceleration a=a0, a0 is the set acceleration; if Spd_ref is greater than Spd_target, the voltage error error is calculated to be equal to the maximum value of the bus voltage minus the real-time value of the bus voltage, and then the voltage error error is processed by PI to output the acceleration a; The acceleration a and the current speed command Spd_ref recorded when exiting the speed tracking unit are used to perform FOC magnetic field oriented control to gradually approach the flying start target speed Spd_target, and finally make the real-time operating speed of the permanent magnet synchronous motor equal to the flying start target speed Spd_target.

3. The method for flying start of a position sensorless vector-controlled permanent magnet synchronous motor according to claim 2, characterized in that: Taking the current speed command Spd_ref recorded when exiting the speed tracking unit as the starting point and acceleration a as the step size, the current speed command Spd_ref is gradually increased to perform FOC magnetic field oriented control and gradually approach the flying car starting target speed Spd_target.

4. The method for flying start of a position sensorless vector-controlled permanent magnet synchronous motor according to claim 3, characterized in that: If Spd_ref is greater than Spd_target, the acceleration a is calculated as follows: a=kp×error+∫(ki×error)dt Where Kp Ki are the parameters of the PI controller.

5. The method for flying start of a position sensorless vector-controlled permanent magnet synchronous motor according to claim 1, 2, 3 or 4, characterized in that: The specific steps of flying start are as follows: S1: Initialize various parameters and set the speed tracking flag to 1; S2: Read the bus voltage Vbus, phase current and startup target speed Spd_target, and calculate the real-time running speed Spd_act, q-axis real-time current Iq and d-axis real-time current Id of the permanent magnet synchronous motor; S3: Determine whether the speed tracking flag is 1; if so, enter S4; if not, enter S6; S4: Speed ​​tracking: Take the real-time speed Spd_act of the motor as the current speed command Spd_ref, and judge whether the real-time current Iq of the q-axis is less than the set q-axis current Iq0. If not, enter S5; if yes, set the speed tracking flag Flag=0, record the current speed command Spd_ref, and enter S6; S5: Set Iq_ref and Id_ref to 0, perform FOC field oriented control, and return to S2; S6: Acceleration adaptive control, whether the current speed command Spd_ref is greater than the target speed Spd_target, if not, set the acceleration a=a0, a0 is the set acceleration; if yes, calculate the voltage error error equal to the maximum value of the bus voltage minus the real-time value of the bus voltage, then perform PI processing on the voltage error error to output the acceleration a, and enter step 7; S7: Recalculate the current speed command Spd_ref using the acceleration a, compare the current speed command Spd_ref with the real-time speed Spd_act of the motor, perform PI processing, perform FOC magnetic field oriented control processing, and return to S2.

6. The method for flying start of a position sensorless vector-controlled permanent magnet synchronous motor according to claim 5, characterized in that: When FOC field oriented control is performed using the acceleration a and the current speed command Spd_ref recorded when exiting the speed tracking unit, Id_ref is generated by the MTPA unit operation.

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