Method for flying start of position sensorless vector-controlled permanent magnet synchronous motor

Abstract

The invention discloses a method for flying start of a position sensorless vector controlled permanent magnet synchronous motor. During flying start, a speed tracking unit is used to take the real-time running 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 processing is performed until the real-time q-axis 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; an acceleration adaptive control unit compares the current speed command Spd_ref with the flying start target speed Spd_target, if Spd_ref is less than Spd_target, acceleration a=a0 is set; if Spd_ref is greater than Spd_target, a voltage error error is calculated, and then PI processing is performed on the voltage error error to output acceleration a; the method effectively suppresses the reverse rotation of the motor to generate electricity, avoids the risk of overvoltage of the motor controller, has high reliability, simple logic algorithm, and can seamlessly connect the current speed of the motor.

Description

Technical field:

[0001] The invention relates to a flying start method for 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 quietness, and are gradually being used in fan and water pump systems.

[0003] Starting a motor using sensorless vector control has always been a difficult problem 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 speed or at rest. Therefore, in order to overcome this problem, an open-loop current forced drag method is usually used when the motor is started, allowing the rotor to reach a certain speed according to the predetermined acceleration, and then gradually switch to closed-loop FOC magnetic field oriented control.

[0004] Figure 1 This is the flow chart of the FOC magnetic field oriented control of the current position sensorless vector controlled permanent magnet synchronous motor. In the figure, the current speed command Spd_ref is compared with the real-time speed Spd_act of the motor 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 through coordinates to obtain the input of SVPWM, and the output of SVPWM is passed through a three-phase inverter to obtain the phase currents Ia, Ib, and Ic of the three-phase coil windings of the motor; the phase currents Ia, Ib, and Ic are transformed through coordinates to obtain the q-axis real-time current Iq and the d-axis real-time current Id. The figure also includes a position & speed observer. The phase currents Ia, Ib, Ic and the DC bus voltage are used as input data of the position & speed observer. The position & speed observer outputs the real-time speed Spd_act and coordinate transformation angle θ of the motor.

[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 wind 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. The motor is often stopped and started according to the logical instructions of the air conditioning system during use. When restarting, the rotor of the motor may be rotating in the reverse or forward direction due to external air flow pressure or fan inertia. When the motor starts, it does not know whether the motor is rotating because there is no position sensor. If open-loop forced start is used directly, because the speed and position cannot be identified, it is bound to cause the motor to be in the 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, so special treatment is required for the flying start of the motor.

[0006] The patent number is: 201811120169.5, the patent name is: DC fan start-up control method and device, the invention patent of the 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 start-up modes according to the speed. This solution has two problems. First, injecting a 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. Summary of the invention:

[0007] The purpose of the present invention is to provide a method for flying start of a position sensorless vector controlled permanent magnet synchronous motor, mainly to solve the technical problems of complex logic leading to complex algorithm, uncontrollable current control leading to the motor sometimes running in the power generation state, causing overvoltage of the inverter to damage the power devices, and low reliability.

[0008] The objective of the present invention is achieved through the following technical solutions:

[0009] The method for flying start of a position sensorless vector-controlled permanent magnet synchronous motor is characterized by comprising the following steps:

[0010] 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;

[0011] 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.

[0012] 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.

[0013] The above-mentioned speed tracking unit and acceleration adaptive control unit are two units added on the basis of the FOC magnetic field oriented control framework, where:

[0014] 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;

[0015] 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;

[0016] 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.

[0017] 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.

[0018] If Spd_ref is greater than Spd_target, the acceleration a is calculated as follows:

[0019] a=kp×error+(ki×error)dt

[0020] Where kp and 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 various 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 running 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, enter S4; if not, enter S6;

[0025] 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;

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

[0027] 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;

[0028] 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.

[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 has a speed tracking unit that automatically tracks the speed during startup and automatically controls the acceleration of the permanent magnet synchronous motor PMSM, effectively suppressing the motor from rotating in the opposite direction to generate electricity, avoiding the risk of overvoltage in the motor controller, and preventing the inverter from being damaged by overvoltage and causing power devices, and has 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 the current speed of the motor without causing noise due to sudden changes in speed.

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

[0034] Figure 1 It is a schematic diagram of the principle of FOC field oriented control of an existing position sensorless vector controlled permanent magnet synchronous motor.

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

[0036] Figure 3 This is the relationship diagram of various coordinate systems for permanent magnet synchronous motor vector control;

[0037] Figure 4 is a three-dimensional diagram of the permanent magnet synchronous motor of the present invention;

[0038] Figure 5 is a three-dimensional diagram of a motor controller of a permanent magnet synchronous motor of the present invention;

[0039] Figure 6 is a cross-sectional view of the permanent magnet synchronous motor of the present invention;

[0040] Figure 7 It is a principle block diagram of a motor controller of a permanent magnet synchronous motor of the present invention;

[0041] Figure 8 yes Figure 7 The corresponding circuit diagram;

[0042] Fig. 9 is a vector control flow chart of the permanent magnet synchronous motor of the present invention;

[0043] Fig.10 It is a program control flow chart of the present invention;

[0044] Fig.11 yes Fig.10 Program control flow chart of the medium acceleration adaptive control unit;

[0045] Fig.12 It is a diagram showing the change of speed, voltage and acceleration parameters of the present invention when starting downwind;

[0046] Fig.13 This is a current variation diagram of the present invention when starting downwind;

[0047] Fig.14 It is a diagram showing the change of speed, voltage and acceleration parameters of the present invention when starting against wind;

[0048] Fig.15 This is a current variation diagram of the present invention when starting against wind. Specific implementation method:

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

[0050] like Figure 2 As shown, the basic working principle of the position sensorless vector controlled permanent magnet synchronous motor is briefly described (the textbook has a detailed description). 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 mutually perpendicular coordinate system of αβ); 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 synthetic vector of the stator in the figure is S; according to the calculation formula of the electromagnetic torque:

[0051] T e =P0·ψ f ×i q ------(1)

[0052] P0 is the number of pole pairs (constant) of the motor, 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:

[0053] T e =K×i q ------(2)

[0054] K is a constant, and the electromagnetic torque Te of the permanent magnet synchronous motor is only related to the q-axis current.

[0055] like Figure 3 As shown, the stator stationary coordinate system ABC coordinate system is replaced by a mutually perpendicular coordinate system of αβ. The stator stationary coordinate system is the coordinate system of αβ, 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.

[0056] like Figure 4, Figure 5 , Figure 6 As shown, for example: Assume that the present invention is a three-phase permanent magnet synchronous motor with position sensorless vector control, which consists of a motor controller 2 and a motor monomer 1 ( Figure 8 In the figure, the motor monomer 1 includes a stator assembly 12, a rotor assembly 13 and a housing assembly 11. The stator assembly 13 is mounted 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 each phase coil winding of the stator assembly 12. The microprocessor adopts a single-chip microcomputer MCU.

[0057] like Figure 7 , Figure 8 As shown, it is assumed that the phase current detection circuit of the three-phase brushless DC permanent magnet synchronous motor inputs the current Ia, Ib, and Ic of each phase into the microprocessor. After the AC input (AC INPUT) passes through the full-wave rectifier circuit composed of diodes D7, D8, D9, and D10, the DC bus voltage Vbus is output at one end of the capacitor C1. The DC bus voltage Vbus is related to the input AC voltage. The microprocessor inputs a PWM signal with a certain duty cycle to the inverter. The inverter is composed of electronic switch tubes Q1, Q2, Q3, Q4, Q5, and Q6. The control ends of the electronic switch tubes Q1, Q2, Q3, Q4, Q5, and Q6 are respectively controlled by the 6-way PWM signals (P1, P2, P3, P4, P5, and P6) output by the microprocessor. The PWM signal with a certain duty cycle refers to a PWM signal with a duty cycle of Duty.

[0058] like Figure 3 and Fig. 9 As shown, 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 & speed observer. A flux observer can be set in the motor microprocessor. The 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.

[0059] like Fig. 9 As shown, the method for flying start of a position sensorless vector-controlled permanent magnet synchronous motor of the present invention is characterized by comprising the following steps:

[0060] 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;

[0061] 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.

[0062] 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.

[0063] The above-mentioned speed tracking unit and acceleration adaptive control unit are two units added on the basis of the FOC magnetic field oriented control framework, where:

[0064] 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;

[0065] 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;

[0066] 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 car start target speed Spd_target, and finally make the real-time operating speed of the permanent magnet synchronous motor equal to the flying car start target speed Spd_target. 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 use the acceleration a as the step distance to gradually increase the current speed command Spd_ref to perform FOC magnetic field oriented control to gradually approach the flying car start target speed Spd_target.

[0067] The present invention adds a speed tracking unit, an acceleration adaptive control unit, and an MTPA unit used in flying start on the basis of the FOC magnetic field oriented control framework. The so-called flying start refers to what is usually called forward or reverse wind start or reverse wind start on the fan, that is, the motor rotates forward or reverse at a certain speed before starting. When the position sensorless vector control permanent magnet synchronous motor receives the flying start instruction: first, the speed tracking is performed, that is, the speed tracking unit is started, and the real-time running speed Spd_act of the motor is used as the current speed instruction Spd_ref, and the speed tracking unit is started 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 current reference value of the q-axis, Iq_ref is compared with the real-time current Iq for PI processing to form a current loop, Id_ref is the current reference value of the d-axis, Id_ref is compared with the d-axis real-time current Id for PI processing to form another current loop; set the q-axis current Iq0 to a safe limited 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 sudden speed change.

[0068] If Spd_ref is greater than Spd_target, the acceleration a is calculated as follows:

[0069] a=kp×error+∫(ki×error)dt

[0070] Where kp and ki are the parameters of the PI controller.

[0071] 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: Fig.10 and Fig.11 As shown:

[0072] S1: Initialize various parameters and set the speed tracking flag to 1;

[0073] 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;

[0074] S3: Determine whether the speed tracking flag is 1; if so, enter S4; if not, enter S6;

[0075] 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;

[0076] S5: Set Iq_ref and Id_ref to 0, perform FOC field oriented control, and return to S2;

[0077] 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;

[0078] 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.

[0079] When the acceleration a and the current speed command Spd_ref recorded when exiting the speed tracking unit are used for FOC 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 how much Id_ref is required when the maximum torque can be obtained per ampere. This is described in textbooks or patent documents and is a prior art. 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 Iq_ref can be obtained using the speed loop PI:

[0080] Iq_ref=kp×err_spd+(ki×err__spd)dt Kp Ki is a parameter of the PI controller.

[0081] The FOC 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.

[0082] like Fig.12 , Fig.13 As shown, the motor using the method of flying start of the position sensorless vector controlled permanent magnet synchronous motor is tested. The flying start under the tailwind condition (high speed tailwind start 300hz) may cause instantaneous voltage increase. The solution of the present invention is:

[0083] 1. First perform speed tracking, that is, start the speed tracking unit, and 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.

[0084] 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;

[0085] 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 acceleration is adjusted according to the voltage error PI.

[0086] 4. After the acceleration gradually recovers, the current speed command Spd_ref gradually catches up with the startup target speed Spd_target.

[0087] High-speed downwind start (300hz) test chart ( Fig.12 ), the top graph is the speed-given target speed Spd_target and the feedback (the real-time running speed Spd_act of the motor), the middle graph is the bus voltage, and the bottom graph is the acceleration change, where there is a large voltage fluctuation only during the speed tracking process (which can be absorbed by the capacitor), and after the speed tracking is completed, it is smoothly accelerated to the given speed target speed Spd_target. Fig.13 In the process of flying car starting, the maximum fluctuation of current is below 1.267A, which fully meets the design requirements.

[0088] like Fig.14 , Fig.15 As shown, the motor using the method of flying start of the position sensorless vector controlled permanent magnet synchronous motor is tested. The flying start under the headwind condition (high-speed headwind start 300hz) may cause instantaneous voltage increase. The solution of the present invention is:

[0089] 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 rises slightly;

[0090] 2. The voltage will rise at the moment of starting. As the speed is successfully tracked, the acceleration becomes 0 and Iq will decrease. When the Iq value is less than the threshold (i.e., the q-axis current Iq0 is set), the deceleration starts to increase and enters the positive torque control mode. The voltage may rise again. When the real-time 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 an acceleration a=a0 until the current speed command Spd_ref gradually catches up with the startup target speed Spd_target.

[0091] from Fig.14 As shown in the figure, the flying start process only has a large voltage (which can be absorbed by the capacitor) during the speed tracking process. After the tracking is completed, the speed starts to decelerate from -300 Hz. During the deceleration process, the bus voltage is limited to around 20V. Accordingly, the acceleration is reduced from 500 Hz per second to about 200 Hz per second. When the bus voltage drops, the acceleration gradually transitions to the set acceleration a0. Then it enters the low-speed section and crosses the zero point, and then accelerates to 300 Hz according to the set acceleration. Fig.15 In the process of flying start, the maximum fluctuation of current is below 933mA, which fully meets the design requirements.

[0092] The flying car starting method of the present invention has a speed tracking unit that automatically tracks the speed during startup, and automatically controls the acceleration of the permanent magnet synchronous motor, effectively suppresses the motor from rotating in the opposite direction to generate electricity, avoids the risk of overvoltage of the motor controller, and prevents the inverter from being damaged by overvoltage due to power devices, and has high reliability. The flying car starting method of the present invention has a simple logic algorithm, and can ensure that the current is in a controllable state during startup by controlling the current and speed, and can seamlessly connect the current speed of the motor without causing noise due to sudden changes in the speed.

[0093] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited thereto. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention are all equivalent replacement methods and are included in the protection scope 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; 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.

2. The method for flying start of a position sensorless vector-controlled permanent magnet synchronous motor according to claim 1, 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.

3. The method for flying start of a position sensorless vector-controlled permanent magnet synchronous motor according to claim 2, 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 and ki are the parameters of the PI controller.

4. The method for flying start of a position sensorless vector-controlled permanent magnet synchronous motor according to claim 1, 2 or 3, 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.

5. The method for flying start of a position sensorless vector-controlled permanent magnet synchronous motor according to claim 4, 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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