DC-link electrolytic capacitor critically affects the lifetime of the motor drive system. This paper proposes an inverter power control strategy based on dc-link voltage regulation for the ...electrolytic capacitor-less interior permanent magnet synchronous motor drive system. The dc-link electrolytic capacitor is replaced by a small film capacitor and the power factor correction circuit is also eliminated. Hence, the inverter power should be regulated effectively to achieve high input power factor and low grid current harmonics. The inverter power control loop based on proportional resonant (PR) controller is established to regulate the inverter power into sinusoidal wave. The PR controller can be designed to achieve a high gain at the desired frequency and the parameters are easy to design due to the simple structure. In addition, a power compensation method based on the dc-link voltage regulation is used to diminish the error of inverter power control, which does not depend on the precise calculation and is easy to realize. The effectiveness of the proposed method is demonstrated by the experimental results on an air conditioner. The input power factor can reach 0.992 and the harmonics of grid current are considerably lower than the requirement of EN61000-3-2 standard.
In electrolytic capacitorless permanent magnet synchronous motor (PMSM) drives, the DC-link voltage will fluctuate in a wide range due to the use of slim film capacitor. When the flux-weakening ...current is lower than −ψf/Ld during the high speed operation, the flux-weakening control loop will transform to a positive feedback mode, which means the reduction of flux-weakening current will lead to the acceleration of the voltage saturation, thus the whole system will be unstable. In order to solve this issue, this paper proposes a novel flux-weakening method for electrolytic capacitorless motor drives to maintain a negative feedback characteristic of the control loop during high speed operation. Based on the analysis of the instability mechanism in flux-weakening region, a quadrature voltage constrain mechanism is constructed to stabilize the system. Meanwhile, the parameters of the controller are theoretically designed for easier industrial application. The proposed algorithm is implemented on a 1.5kW electrolytic capacitorless PMSM drive to verify the effectiveness of the flux-weakening performance.
To extend the lifetime, improve the power density and reduce the system cost, the film capacitor is applied to replace the large-volume electrolytic capacitor in motor drives. As the dc-link voltage ...fluctuates periodically, the rotor position estimation error and operation stability are necessary to be concerned in the position sensorless control methods. A cross-decoupling complex filtering-based position estimation method is investigated for the reduced capacitance interior permanent magnet synchronous motor drive system. Harmonic components of the extended back electromotive force (EEMF) caused by the dc-link voltage fluctuation are analyzed to evaluate the additional rotor position error. A cross-decoupling complex filter realized by the multiple first-order complex filters with different center frequencies is designed to improve the position estimation precision. Harmonics of the EEMF are suppressed and the position error can be eliminated. The estimation precision and operation ability are improved. Experimental results are performed to verify the effectiveness of the proposed method.
The power density can be improved and the system cost can be saved in the reduced dc-link capacitance motor drive system. The line inductance can also be diminished to reduce the system volume ...further. In previous research works, the active damping control methods mainly concentrated on the drive system equipped with a larger line inductor. In this article, a dc-link voltage estimation feedback-based active damping method is proposed to suppress the grid current harmonics and improve the drive system stability with low line inductance. The dc-link voltage ripple caused by the LC resonance is analyzed to evaluate the direct dc-link voltage feedback-based active damping control method. To improve the damping performance, the resonant component of the dc-link voltage caused by the LC resonance could be obtained through the grid current to establish the feedback control loop. The sampling delay should be compensated to improve the control performance. The stability of the drive system is evaluated by the Nyquist plots of the impedance model, and the grid current is also analyzed, which could satisfy the harmonic requirements of IEC-61000-3-2. Experimental results are performed to verify the effectiveness of the proposed method.
As the dc-link capacitance decreases obviously, the dc-link voltage fluctuates severely in the electrolytic capacitorless permanent magnet synchronous motor (PMSM) drives for compressor applications. ...The control performance of the compressor deteriorates, and the dc-link may suffer from the fault of overvoltage. In this article, an acceleration extraction-based torque ripple compensation method considering safe operation with dc-link anti-overvoltage is proposed for electrolytic capacitorless PMSM compressor drives. The fluctuation characteristics of the compressor torque and the speed caused by the interaction of the dc-link voltage and the load are analyzed. The load torque is estimated online using the orthogonality theory to suppress the torque ripple. Based on the hybrid proportional-integral-resonant regulator, an anti-overvoltage control strategy is proposed for the safe operation of the regenerating state. Experimental results are performed in the air-conditioner compressor drive system to verify the effectiveness of the proposed method.
The application of permanent magnet synchronous motor (PMSM) is becoming more and more popular. The reliability of PMSM has become a research hotspot. The fault diagnosis method of current sensor for ...PMSM drive system is studied in this paper. The fault type of the current sensor is analyzed and the fault model is built. Using the method of changing the stationary coordinate frame, the current reference value is compared with the sampled value from the sensor. Then the fault diagnosis method based on the residual error is used to diagnose the fault of the current sensor. Experimental results show that the proposed method could realize the fast and accurate positioning of the fault phase current sensor.
A sensorless control method based on pseudo-random high-frequency(HF) sinusoidal voltage injection is studied to solve the noise problem caused by the conventional HF injection strategy in this ...paper. In the low-speed and zero-speed range, HF injection strategy is widely used as a sensorless control strategy for IPMSM drives. However, the harsh noise caused by the HF signals is unexpected. By injecting two HF signals with different frequencies in a random manner, instead of traditional fixed frequency signal, noise problems can be attenuated while sustaining the estimation accuracy. The signal processing is analyzed to select the frequency and amplitude of the pseudo-random high-frequency (PRHF) sinusoidal signals. This method is verified by simulation and experiment on a 2.2-kW IPMSM drive platform.
The space vector modulation-based direct torque control (SVM-DTC) based permanent magnet synchronous motor (PMSM) suffers from large speed ripples due to the periodic fluctuation of load torque. An ...adaptive load torque feedforward compensation method is proposed based on the observation of the periodic pulsation component in the load torque. The reference torque in the torque loop is compensated according to the torque feedforward. This method can effectively reduce the speed ripples and improve the steady-state performance meanwhile maintaining the advantages of the conventional SVM-DTC. The effectiveness of the proposed method is verified by conducting experiments on the 1.5kW air conditioning compressor.
To reduce costs and improve performance, sensorless control is widely adopted for permanent magnet synchronous motor (PMSM) drives. In the low speed range, the high-frequency injection method can be ...used, but the harsh noise limits its application. In this paper, a random high-frequency square-wave voltage injection sensorless control method based on chaotic mapping is used for reduce the additional noise. Four kinds of square-wave signals with different frequencies and amplitudes are selected in this control strategy, and the chaotic mapping method is used to generate a random number sequence. According to the value of the random number sequence, the type of injected square-wave is selected. Then the signal processing process of random high-frequency square-wave injection is deduced. Finally, the experimental verification is carried out on the platform of PMSM drive, and the effectiveness of the scheme is proved by the analysis of the motor phase current power spectral density (PSD).
To improve the efficiency of sensorless interior permanent magnet synchronous motor (IPMSM) drives, a simultaneous maximum torque per ampere (MTPA) and sensorless control strategy for IPMSM drives ...based on high-frequency (HF) signal injection is proposed. This method can avoid HF signals mutual interference by making full use of the d-q axis HF current response and tracking MTPA point with qaxis virtual signal injection. The experiments on the 2.2-kW IPMSM platform verify the proposed method can realize sensorless control and MTPA control simultaneously at low-speed region.
