Current source permanent magnet synchronous motor controller design method

Abstract

The application discloses a current source type permanent magnet synchronous motor controller design method, aiming at the problems of the filter capacitor and the motor inductance constituting a second-order resonance network in the current source type inverter driving system, easy to cause oscillation, poor stability and difficult controller parameter setting, etc., the application adopts a double-loop framework of voltage inner loop proportional control and current outer loop proportional-integral control. The voltage inner loop offsets and decouples through current feedback and d-q axis cross coupling, the proportional parameter is determined according to the over-damping condition of the second-order system, and the resonance is effectively inhibited; the current outer loop introduces feedback decoupling, simplifies the parameter design based on zero-pole cancellation, and quantitatively calculates the proportional and integral parameters combined with the expected cutoff frequency, so that the experience trial and error is avoided. The experimental results show that the application can significantly improve the stability of the system, the total harmonic distortion rate of the current is as low as 1.23% under the steady state, and the torque ripple is small; under the dynamic condition, there is no overshoot, no oscillation and no static error, excellent steady-state accuracy and dynamic response performance are considered, and the engineering practicability is high.

Description

Technical Field

[0001] This invention relates to a design method for a current-source type permanent magnet synchronous motor controller. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) offer advantages such as high efficiency and high power density, leading to their widespread application in industrial fields. Currently, voltage source inverters are commonly used as their drive topology, and their modulation and control technologies are quite mature. However, because the output voltage of a voltage source inverter is a rectangular wave, the ripple in the motor current and torque fluctuations are significant and cannot be improved through control methods. In contrast, current source inverters have a filter capacitor at the output terminal, which absorbs high-frequency switching harmonics in the inverter output current, resulting in a sinusoidal motor voltage. Therefore, compared to the commonly used voltage source grid-connected inverters, using a current source inverter to drive a PMSM can significantly improve the motor's steady-state performance. However, the addition of the capacitor creates a second-order system with the motor inductance. Furthermore, due to the motor's low internal resistance, resonance occurs, amplifying harmonics within the resonant frequency range and reducing system stability. Secondly, the increased system order complicates controller design and degrades dynamic performance. However, existing control schemes for current-source permanent magnet synchronous motors mostly adopt the control framework of voltage-source inverters, lacking effective strategies for LC resonance suppression, dq-axis cross-coupling decoupling, and systematic parameter design. Controller parameters often rely on repeated trial and error based on engineering experience, resulting in long debugging cycles, poor consistency, and difficulty in ensuring good steady-state accuracy and dynamic performance across a wide range of operating conditions. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a design method for a current-source type permanent magnet synchronous motor controller, which provides stable driving, effectively reduces resonance jitter, effectively eliminates inter-shaft interference, and has good performance.

[0004] To achieve the above objectives, this invention provides a design method for a current-source permanent magnet synchronous motor controller, comprising a voltage inner-loop proportional controller and a current outer-loop proportional-integral controller. The voltage inner-loop proportional controller is used to achieve current feedback loop cancellation and decoupling of the cross-coupling of the two-phase rotating dq coordinate system. The control algorithm of the voltage inner-loop proportional controller is as follows:

[0005] In the formula, i * dt and i * qt This represents the given value of the inverter output current in the dq coordinate system. u* d and u * q This represents the given value of the capacitor voltage in the dq coordinate system. u d and u q This represents the sampled value of the capacitor voltage in the dq coordinate system; i d and i q This represents the sampled value of the stator current in the dq coordinate system; ω e Indicates the electrical angular frequency of the motor. C Indicates the size of the filter capacitor. k up This indicates the proportional parameters of the voltage inner loop proportional controller.

[0006] As a further feature of the present invention, the closed-loop transfer function of the inner current loop is derived. G id ( s The expression is:

[0007] In the formula, L d and R s This indicates the inductance and resistance of the motor.

[0008] As a further provision of the present invention, the range of values ​​for the voltage inner loop proportional parameter kup is determined by using the constraint that the second-order system constituted by the current inner loop closed-loop transfer function Gid(s) is in an overdamped state: .

[0009] As a further feature of the present invention, the current outer loop proportional-integral controller incorporates a feedback decoupling element, and its control algorithm expression is as follows: In the formula, k ip and k ii This represents the proportional and integral parameters of the proportional-integral controller. i * d and i * q This represents the given value of the inverter stator current in the dq coordinate system.

[0010] As a further feature of the present invention kip and k ii Set as τL d and τR s The open-loop transfer function expression for the inner current loop is: .

[0011] As a further feature of the present invention, the open-loop transfer function of the inner current loop can be calculated based on the desired cutoff frequency. τ The calculation method is as follows:

[0012] In the formula, ω c This indicates the cutoff frequency of the current loop.

[0013] The beneficial effects of this configuration are as follows: Addressing key issues in current-source permanent magnet synchronous motor drive systems, such as LC resonance, poor stability, difficulty in parameter tuning, and insufficient dynamic performance, this configuration proposes a dual-loop parameter design method combining inner-loop voltage proportional control and outer-loop current proportional-integral control, achieving significant technical results. This scheme achieves current feedback cancellation and dq-axis cross-coupling decoupling through the inner-loop voltage proportional controller. It accurately determines the proportional parameters based on the overdamping condition of the second-order system, effectively suppressing the resonance spikes formed by the filter capacitor and motor inductance, eliminating the risk of system oscillation, and significantly improving the operational stability of the drive system. Simultaneously, the outer-loop current proportional-integral controller introduces a feedback decoupling stage, simplifying the parameter design logic. It correlates the proportional and integral parameters with the inherent parameters of the motor through zero-pole cancellation, and calculates the gain coefficient using the desired cutoff frequency quantization. This avoids the drawbacks of traditional trial-and-error parameter adjustments based on experience, shortens the debugging cycle, and ensures the consistency and optimality of parameter tuning. Experimental verification shows that under this technical solution, the total harmonic distortion rate of the current during steady-state operation is about 1.3%, and the torque ripple is significantly reduced, effectively reducing electromagnetic noise and operating losses. Under dynamic conditions, the motor acceleration process is free from overshoot, oscillation, and steady-state error, with fast and accurate response. It takes into account both excellent steady-state accuracy and dynamic response performance, effectively solving the technical bottleneck in the engineering application of current source type permanent magnet synchronous motor drive system, and significantly improving the overall system operation quality and engineering practicality. Attached Figure Description

[0014] Figure 1 This is the topology of the current-source permanent magnet synchronous motor drive system in this embodiment of the invention; Figure 2 This is a structural block diagram of the control system proposed in an embodiment of the present invention; Figure 3The amplitude-frequency and phase-frequency characteristic curves of the voltage inner loop closed-loop transfer function under different scaling factors are shown in the embodiments of the present invention. Figure 4 The above are the amplitude-frequency and phase-frequency characteristic curves of the closed-loop transfer function of the current outer loop under different coefficients in the embodiments of the present invention. Figure 5 The waveforms of the speed, torque, current and voltage of the permanent magnet synchronous motor under steady-state conditions are shown in the embodiments of the present invention. Figure 6 This is a harmonic analysis diagram of the current under steady-state conditions in an embodiment of the present invention; Figure 7 The diagram shows the speed, torque, and current waveforms of the permanent magnet synchronous motor under acceleration conditions in an embodiment of the present invention. Detailed Implementation

[0015] Examples of the implementation of the current-source type permanent magnet synchronous motor controller design method of the present invention Figures 1 to 7 As shown: In this embodiment, a 380 V, 7.5 kW, 1500 r / min permanent magnet synchronous motor is selected as the controlled object. The motor parameters are as follows: stator resistance... R s = 0.15Ω, d-axis inductance L d =8mh, filter capacitor C =100μF; corresponding electrical angular frequency ω e =200πrad / s; Cutoff frequency of the current loop ω c =2000πrad / s; For current-source permanent magnet synchronous motor drive systems, see the topology section. Figure 1 The voltage inner loop employs proportional control and introduces current feedback to cancel out and decouple the cross-coupling of the dq axis. See the block diagram below. Figure 2 Its control algorithm is as follows: After substituting the system parameters, the closed-loop transfer function of the d-axis current inner loop is derived: Draw different k up Down G id ( s For the amplitude and phase frequency curves, see [link to curve]. Figure 3 .along with k up Increase, G id ( sThe resonant peak of the second-order system gradually decreases, transitioning from an underdamped to an overdamped state, and the phase margin also increases, thus improving stability. The second-order system shown in equation (2) G id ( s ) is under the condition of overdamping, k up The range of values ​​for is determined as follows: The algorithm for the current outer loop proportional-integral controller is as follows: In the formula, k ip and k ii This indicates the proportional and integral parameters of the proportional-integral controller. i * d and i * q This represents the given value of the inverter stator current in the dq coordinate system.

[0016] k ip and k ii Set as τL d and τR s Open-loop transfer function of the inner current loop. T oid ( s The expression is: Draw different τ Values T oid ( s For the amplitude and phase frequency curves, see [link to curve]. Figure 4 .along with τ The increase in cutoff frequency leads to an increase in closed-loop system bandwidth and a faster dynamic response.

[0017] Parameters can be calculated based on the desired cutoff frequency. τ The calculation method is as follows: With a cutoff frequency of 1kHz, the controller parameters were calculated according to equations (3) and (6), and steady-state verification was performed at 1500 rpm and 10 N·m. The waveform and current harmonic analysis results were used in the calculation. Figure 5 As can be seen, the system has very small torque ripple, and the total harmonic distortion of the current is only 1.23%.

[0018] Experimental verification was conducted under the condition of a load of 5 N·m and a given speed increasing from 750 rpm to 1500 rpm. The waveform is as follows. Figure 6 As shown, the dynamic process exhibits no overshoot or oscillation, and the steady-state process has no steady-state error.

[0019] The above examples are merely one preferred embodiment of the present invention. Ordinary variations and substitutions made by those skilled in the art within the scope of the technical solution of the present invention are all included within the protection scope of the present invention.

Claims

1. A design method for a current-source type permanent magnet synchronous motor controller, characterized in that: It includes a voltage inner-loop proportional controller and a current outer-loop proportional-integral controller. The voltage inner-loop proportional controller is used to achieve current feedback loop cancellation and decoupling of the cross-coupling of the two-phase rotating dq coordinate system. The control algorithm of the voltage inner-loop proportional controller is as follows: In the formula, i * dt and i * qt This represents the given value of the inverter output current in the dq coordinate system. u * d and u * q This represents the given value of the capacitor voltage in the dq coordinate system. u d and u q This represents the sampled value of the capacitor voltage in the dq coordinate system; i d and i q This represents the sampled value of the stator current in the dq coordinate system; ω e Indicates the electrical angular frequency of the motor. C Indicates the size of the filter capacitor. k up This indicates the proportional parameters of the voltage inner loop proportional controller.

2. The design method of a current source type permanent magnet synchronous motor controller according to claim 1, characterized in that: Derive the closed-loop transfer function of the inner current loop. G id ( s The expression is: In the formula, L d and R s This indicates the inductance and resistance of the motor.

3. The design method for a current-source type permanent magnet synchronous motor controller according to claim 1, characterized in that: Given that the second-order system, defined by the current inner loop closed-loop transfer function Gid(s), is in an overdamped state, the range of values ​​for the voltage inner loop proportional parameter kup is determined as follows: 。 4. The design method of a current source type permanent magnet synchronous motor controller according to claim 1, characterized in that: The current outer loop proportional-integral controller introduces a feedback decoupling element, and its control algorithm expression is as follows: In the formula, k ip and k ii This represents the proportional and integral parameters of the proportional-integral controller. i * d and i * q This represents the given value of the inverter stator current in the dq coordinate system.

5. The design method of a current source type permanent magnet synchronous motor controller according to claim 1, characterized in that: k ip and k ii Set as τL d and τR s ; The open-loop transfer function expression for the inner current loop is: 。 6. The design method of a current source type permanent magnet synchronous motor controller according to claim 1, characterized in that: The open-loop transfer function of the inner current loop can be calculated based on the desired cutoff frequency. τ The calculation method is as follows: In the formula, ω c This indicates the cutoff frequency of the current loop.

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