Electrolytic capacitor-free PMSM weak magnetic control method based on adaptive reference voltage

Abstract

The invention discloses an electrolytic capacitor-free PMSM weak magnetic control method based on adaptive reference voltage, and the method specifically comprises the steps: collecting the actual three-phase current and output rotating speed of a motor drive system, and obtaining a d-axis voltage instruction and a q-axis voltage instruction through the processing of a controller; adaptively calculating a reference voltage according to the output current, the given rotating speed and the output rotating speed in combination with a system preset parameter rotating speed allowable error, a current maximum value and a current intermediate value; the difference between the reference voltage and the feedback voltage is obtained, the difference is adjusted by a voltage loop PI regulator, and then the d-axis negative compensation flux-weakening current is output in an amplitude limiting mode. According to the control method, the effect that the motor enters the flux weakening area is optimized, so that the bus voltage utilization rate and the motor torque pulsation are both considered, and the machine side speed expansion operation effect of the non-electrolytic capacitor permanent magnet synchronous motor driving system is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of permanent magnet synchronous motor control, and in particular relates to a non-electrolytic capacitor PMSM weak magnetic control method based on an adaptive reference voltage. Background Art

[0002] Permanent magnet synchronous motor (PMSM) electrolytic capacitor-free technology reduces the hardware cost of the motor driver and improves system reliability by using small-capacity film capacitors or small-capacity electrolytic capacitors to replace large-capacity electrolytic capacitors and removing the power factor correction (PFC) circuit. Weak magnetic control is to further increase the output speed at the cost of losing torque output by planning the current trajectory when the output voltage of the motor driver has been fully utilized.

[0003] Traditional weak magnetic control methods usually refer to feedback weak magnetic control, that is, negatively compensating the d-axis current through a voltage closed loop; first, the current given voltage vector amplitude is calculated and compared with the reference voltage vector amplitude. If the current given voltage vector amplitude exceeds the reference value, the d-axis current is negatively compensated. This method is highly robust and has a stable control effect, and is widely used in engineering. However, since the bus voltage of the electrolytic capacitor-free motor drive will fluctuate periodically, when the output power increases further and the motor enters the weak magnetic region, the traditional weak magnetic control method based on a constant bus voltage design will be difficult to take into account both the bus voltage utilization and the motor torque pulsation, and cannot achieve satisfactory control effects. Summary of the invention

[0004] The object of the present invention is to provide a non-electrolytic capacitor PMSM weak magnetic control method based on adaptive reference voltage, so as to improve bus voltage utilization and reduce torque pulsation.

[0005] The technical solution adopted by the present invention is a non-electrolytic capacitor PMSM weak magnetic control method based on an adaptive reference voltage, which is specifically implemented according to the following steps:

[0006] Step 1: Collect the actual three-phase current and output speed of the motor drive system, and obtain the d-axis voltage command after processing by the controller. and q-axis voltage command u q * ;

[0007] Step 2: Based on the output current, given speed and output speed, the system presets the speed tolerance parameter ω set 、Maximum current I max and the current intermediate value I m , adaptively calculate the reference voltage u ref ;

[0008] Step 3: Set the reference voltage u ref With feedback voltage u s The voltage loop PI regulator adjusts the difference, and then limits the output of the d-axis negative compensation weak magnetic current i d_FW .

[0009] The present invention is also characterized in that:

[0010] In step 1, specifically:

[0011] Step 1.1: Collect the actual three-phase current i of the motor driver through the sensor a 、i b 、i c , three-phase current i a 、i b 、i c After coordinate transformation, we get the d-axis current i d and q-axis current i q , as shown in formula (1):

[0012]

[0013] Among them, θ e is the rotor electrical angle;

[0014] Step 1.2, obtain the d-axis current command i through the PI speed regulator and stator current distribution strategy d * and q-axis current command i q * , as shown in formula (2):

[0015]

[0016] Where s is the complex parameter in Laplace transform, ω m is the rotor mechanical angular velocity, Preset a given speed for the system, i d_FW is the d-axis negative compensation weak magnetic current, K pw and K iw It is the system preset PI speed regulator parameter;

[0017] Step 1.3, obtain the d-axis voltage command through the PI current regulator and q-axis voltage command As shown in formula (4):

[0018]

[0019] K pd , K id , K pq and Kiq is the system preset PI current regulator parameter, and the reference value is shown in formula (3):

[0020]

[0021] Where J is the moment of inertia, n p is the pole pair number, ψ f is the permanent magnet flux.

[0022] In step 1.3, K pd , K id , K pq and K iq The reference value of is shown in formula (5):

[0023]

[0024] Among them, L d , L q are the d-axis inductance component and the q-axis inductance component, R is the stator resistance, α is the current loop bandwidth, and τ is the time constant.

[0025] In step 2, specifically:

[0026] Step 2.1, by giving the speed ω ref , rotor mechanical angular velocity ω m , d-axis current command and q-axis current command Calculate the speed error Δω e And given current amplitude I ref ; As shown in formula (6):

[0027]

[0028] Step 2.2, according to the speed error Δω e And given current amplitude I ref Combined speed tolerance ω set 、Maximum current I max and the current intermediate value I m , adaptively calculate the reference voltage u ref Specifically:

[0029] Condition 1: When Δω≤ω set When the reference voltage u ref The calculation formula is shown in formula (7):

[0030]

[0031] Where β is the magnetic field weakening gain coefficient, as shown in formula (8):

[0032]

[0033] U dcmax and U dcmin are the maximum bus voltage and the minimum bus voltage, respectively, as shown in formula (9):

[0034]

[0035] Among them, U phase is the effective value of the three-phase input phase voltage;

[0036] Condition 2: When Δω>ω set When the reference voltage u ref The calculation formula is shown in formula (10):

[0037]

[0038] In step 3, specifically:

[0039] Step 3.1: According to the d-axis voltage command output by the PI current regulator and q-axis voltage command u q * , calculate the feedback voltage u s , as shown in formula (11):

[0040]

[0041] Step 3.2, set the reference voltage u ref With feedback voltage u s The voltage loop PI regulator adjusts the output weak magnetic current to a value i d_FW_w After limiting, the output d-axis negative compensation weak magnetic current i d_FW , as shown in formulas (12) and (13):

[0042]

[0043] Among them, K pd_FW and K id_FW It is the system preset PI voltage regulator parameter.

[0044] The beneficial effect of the present invention is that the method of the present invention combines the system preset parameter speed tolerance ω according to the given speed, output speed and given current. set 、Maximum current I max and the current intermediate value I m Adaptive calculation of reference voltage u in voltage feedback method ref size, optimizes the effect of the motor entering the weak magnetic area, thereby taking into account the bus voltage utilization and motor torque pulsation, and improving the machine-side speed expansion operation effect of the electrolytic capacitor-free permanent magnet synchronous motor drive system. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a control block diagram of the control system of the permanent magnet synchronous motor without electrolytic capacitor in the present invention;

[0046] Figure 2 is the A-phase stator current i during the switching process of the weak magnetic control mode of the method of the present invention a Simulation diagram of

[0047] Figure 3 is the output torque T during the switching process of the weak magnetic control mode of the method of the present invention e Simulation diagram of

[0048] Figure 4 is the output speed ω during the switching process of the weak magnetic control mode of the method of the present invention m Simulation diagram of . DETAILED DESCRIPTION

[0049] The present invention is described in detail below in conjunction with specific implementation modes and accompanying drawings.

[0050] Example 1

[0051] The invention discloses an electrolytic capacitor-free PMSM weak magnetic control method based on adaptive reference voltage, which specifically comprises the following steps: collecting the actual three-phase current and output speed of a motor drive system, and obtaining a d-axis voltage command and a q-axis voltage command through processing by a controller; adaptively calculating a reference voltage based on the output current, a given speed and an output speed, and combining system preset parameters of speed tolerance, current maximum value and current intermediate value; making a difference between the reference voltage and the feedback voltage, adjusting the difference through a voltage loop PI regulator, and then limiting the output d-axis negative compensation weak magnetic current.

[0052] Example 2

[0053] The present invention provides a PMSM weak magnetic control method without electrolytic capacitor based on adaptive reference voltage, which is specifically implemented according to the following steps:

[0054] Step 1: Collect the actual three-phase current and output speed of the motor drive system through the sensor, and obtain the d-axis voltage command after processing by the controller. and q-axis voltage command u q * ; Specifically:

[0055] Step 1.1, the permanent magnet synchronous motor control block diagram is as follows Figure 1 As shown, the actual three-phase current i of the motor driver is collected by the sensor. a 、i b 、i c , three-phase current i a 、i b 、i cAfter coordinate transformation, we get the d-axis current i d and q-axis current i q , as shown in formula (1):

[0056]

[0057] Among them, θ e is the rotor electrical angle;

[0058] Step 1.2, obtain the d-axis current command i through the PI speed regulator and stator current distribution strategy d * and q-axis current command i q * , as shown in formula (2):

[0059]

[0060] Where s is the complex parameter in Laplace transform, ω m is the rotor mechanical angular velocity, Preset a given speed for the system, i d_FW is the d-axis negative compensation weak magnetic current, K pw and K iw is the system preset PI speed regulator parameter, and the reference value is shown in formula (3):

[0061]

[0062] Where J is the moment of inertia, n p is the pole pair number, ψ f is the permanent magnet flux;

[0063] Step 1.3, obtain the d-axis voltage command through the PI current regulator and q-axis voltage command As shown in formula (4):

[0064]

[0065] Where K pd , K id , K pq and K iq is the system preset PI current regulator parameter, and the reference value is shown in formula (5):

[0066]

[0067] Among them, L d , L q are the d-axis inductance component and the q-axis inductance component, R is the stator resistance, α is the current loop bandwidth, and τ is the time constant.

[0068] Step 2: Based on the output current, given speed and output speed, the system presets the speed tolerance parameter ω set 、Maximum current I max and the current intermediate value I m , adaptively calculate the reference voltage u ref ; Specifically:

[0069] Step 2.1, by giving the speed ω ref , rotor mechanical angular velocity ω m , d-axis current command and q-axis current command Calculate the speed error Δω e And given current amplitude I ref ; As shown in formula (6):

[0070]

[0071] Step 2.2, according to the speed error Δω e And given current amplitude I ref Combined speed tolerance ω set 、Maximum current I max and the current intermediate value I m , adaptively calculate the reference voltage u ref ;

[0072] Condition 1: When Δω≤ω set When the reference voltage u ref The calculation formula is shown in formula (7):

[0073]

[0074] Where β is the magnetic field weakening gain coefficient, as shown in formula (8):

[0075]

[0076] U dcmax and U dcmin are the maximum bus voltage and the minimum bus voltage, respectively, as shown in formula (9):

[0077]

[0078] Among them, U phase is the effective value of the three-phase input phase voltage;

[0079] Condition 2: When Δω>ω set When the reference voltage u ref The calculation formula is shown in formula (10):

[0080]

[0081] Step 3: Set the reference voltage u ref With feedback voltage u s The voltage loop PI regulator adjusts the difference, and then limits the output of the d-axis negative compensation weak magnetic current i d_FW ; Specifically:

[0082] Step 3.1: According to the d-axis voltage command output by the PI current regulator and q-axis voltage command u q * , calculate the feedback voltage u s , as shown in formula (11):

[0083]

[0084] Step 3.2, set the reference voltage u ref With feedback voltage u s The voltage loop PI regulator adjusts the output weak magnetic current to a value i d_FW_w After limiting, the output d-axis negative compensation weak magnetic current i d_FW , as shown in formulas (12) and (13):

[0085]

[0086] Among them, K pd_FW and K id_FW It is the system preset PI voltage regulator parameter, and its value is selected through trial and error, with the maximum limit value being 0 and the minimum limit value being -I max .

[0087] Example 3

[0088] The present invention designs a weak-field control method for a permanent-magnet synchronous motor without an electrolytic capacitor based on an adaptive reference voltage. Compared with a traditional weak-field control method for a permanent-magnet synchronous motor, it can better balance bus voltage utilization and motor torque pulsation and achieve better control effect.

[0089] Example 4

[0090] Figure 1 The control block diagram of the permanent magnet synchronous motor without electrolytic capacitor in the present invention collects and processes the actual three-phase current and output speed of the motor driver to obtain the d-axis current i d , q-axis current i q and speed error The d-axis current command i is obtained through the speed regulator and stator current distribution strategy d * and q-axis current command i q * , obtain the α-axis voltage command u through the current regulatorα * and β-axis voltage command u β * , and then the PWM pulse signal required by the converter is generated through modulation processing, and the PWM pulse signal is output to the electrolytic capacitor-free motor driver to drive the permanent magnet synchronous motor.

[0091] Example 5

[0092] Figure 2-Figure 4 is the A-phase stator current i during the switching process of the weak magnetic control mode of the method of the present invention a , output torque T e and output speed ω m Simulation diagram. At 0s, the speed is given (1p.u.) and the load (0.476pu) is started. It reaches steady state at 0.3s. The dynamic speed increase performance is good, and the motor speed can rise smoothly. It is loaded to (1p.u.) at 0.5s, and reaches steady state at 0.6s. The torque fluctuation is 4.09%, and the loading performance is good. The speed is given (1.15pu) at 0.7s, and reaches steady state at 0.9s. The torque fluctuation is 9.57%, the dynamic speed increase performance is good, and the motor speed can rise smoothly. The speed is given (1.05pu) at 1.5s, and reaches steady state at 1.6s. The torque fluctuation is 11.95%, the dynamic deceleration performance is good, and the motor speed can drop smoothly. The observed speed in each interval can stably track the given speed. Obviously, by adopting the control method of the present invention, the permanent magnet synchronous motor has better output performance in the weak magnetic field area, which shows that the control method of the present invention can better improve the bus voltage utilization rate while reducing torque pulsation and improving the machine-side speed expansion operation effect of the electrolytic capacitor-free permanent magnet synchronous motor drive system.

[0093] Example 6

[0094] The present invention provides a non-electrolytic capacitor permanent magnet synchronous motor weak magnetic field control method based on adaptive reference voltage to improve the operating performance of the non-electrolytic capacitor permanent magnet synchronous motor drive system in the weak magnetic field area. According to the given speed, output speed and given current, the system preset parameter speed allowable error ω is combined. set 、Maximum current I max and the current intermediate value I m Adaptive calculation of reference voltage u ref size, and optimize the effect of the motor entering the weak magnetic area, so as to better improve the bus voltage utilization while reducing torque pulsation and improving the machine-side speed expansion operation effect of the electrolytic capacitor-free permanent magnet synchronous motor drive system.

Claims

1. A PMSM weak magnetic control method without electrolytic capacitor based on adaptive reference voltage, characterized in that: Follow the steps below to implement it: Step 1: Collect the actual three-phase current and output speed of the motor drive system, and obtain the d-axis voltage command after processing by the controller. and q-axis voltage command u q * ; Step 2: Based on the output current, given speed and output speed, the system presets the speed tolerance parameter ω set 、Maximum current I max and the current intermediate value I m , adaptively calculate the reference voltage u ref ; Step 3: Set the reference voltage u ref With feedback voltage u s The voltage loop PI regulator adjusts the difference, and then limits the output of the d-axis negative compensation weak magnetic current i d_FW .

2. The method for controlling PMSM weak magnetic field without electrolytic capacitor based on adaptive reference voltage as claimed in claim 1, characterized in that: In the step 1, specifically: Step 1.1: Collect the actual three-phase current i of the motor driver through the sensor a 、i b 、i c , three-phase current i a 、i b 、i c After coordinate transformation, we get the d-axis current i d and q-axis current i q , as shown in formula (1): Among them, θ e is the rotor electrical angle; Step 1.2, obtain the d-axis current command i through the PI speed regulator and stator current distribution strategy d * and q-axis current command i q * , as shown in formula (2): Where s is the complex parameter in Laplace transform, ω m is the rotor mechanical angular velocity, Preset a given speed for the system, i d_FW is the d-axis negative compensation weak magnetic current, K pw and K iw It is the system preset PI speed regulator parameter; Step 1.3, obtain the d-axis voltage command through the PI current regulator and q-axis voltage command As shown in formula (4): Where K pd , K id , K pq and K iq It is the system preset PI current regulator parameter.

3. The method for controlling PMSM weak magnetic field without electrolytic capacitor based on adaptive reference voltage as claimed in claim 2, characterized in that: In step 1.2, K pw and K iw The reference value of is shown in formula (3): Where J is the moment of inertia, n p is the pole pair number, ψ f is the permanent magnet flux.

4. The method for controlling PMSM weak magnetic field without electrolytic capacitor based on adaptive reference voltage as claimed in claim 2, characterized in that: In step 1.3, K pd , K id , K pq and K iq The reference value of is shown in formula (5): Among them, L d , L q are the d-axis inductance component and the q-axis inductance component, R is the stator resistance, α is the current loop bandwidth, and τ is the time constant.

5. The method for controlling PMSM weak magnetic field without electrolytic capacitor based on adaptive reference voltage as claimed in claim 2, characterized in that: In the step 2, specifically: Step 2.1, by giving the speed ω ref , rotor mechanical angular velocity ω m , d-axis current command and q-axis current command Calculate the speed error Δω e And given current amplitude I ref ; As shown in formula (6): Step 2.2, according to the speed error Δω e And given current amplitude I ref Combined speed tolerance ω set 、Maximum current I max and the current intermediate value I m , adaptively calculate the reference voltage u ref .

6. The method for controlling PMSM weak magnetic field without electrolytic capacitor based on adaptive reference voltage as claimed in claim 5, characterized in that: In the step 2.2, specifically: Condition 1: When Δω≤ω set When the reference voltage u ref The calculation formula is shown in formula (7): Where β is the magnetic field weakening gain coefficient, as shown in formula (8): U dcmax and U dcmin are the maximum bus voltage and the minimum bus voltage, respectively, as shown in formula (9): Among them, U phase is the effective value of the three-phase input phase voltage; Condition 2: When Δω>ω set When the reference voltage u ref The calculation formula is shown in formula (10):

7. The method for controlling PMSM weak magnetic field without electrolytic capacitor based on adaptive reference voltage as claimed in claim 6, characterized in that: In the step 3, specifically: Step 3.1: According to the d-axis voltage command output by the PI current regulator and q-axis voltage command u q * , calculate the feedback voltage u s , as shown in formula (11): Step 3.2, set the reference voltage u ref With feedback voltage u s The voltage loop PI regulator adjusts the output weak magnetic current to a value i d_FW_w After limiting, the output d-axis negative compensation weak magnetic current i d_FW .

8. The method for controlling PMSM weak magnetic field without electrolytic capacitor based on adaptive reference voltage as claimed in claim 7, characterized in that: i d_FW_w and i d_FW The calculation formula is shown in equations (12) and (13): Among them, K pd_FW and K id_FW It is the system preset PI voltage regulator parameter.

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