Kodai Abe

Input current harmonics reduction control for electrolytic capacitor less inverter based IPMSM drive system

This paper proposes a current harmonics reduction method to improve the input current waveform of electrolytic capacitor less single-phase to three-phase power converters. Typically, the back electromotive force (EMF) on interior permanent magnet (IPM) motor is not sinusoidal and contains harmonics caused by the rotor structure; therefore, it causes harmonic distortion in the motor control system and generates harmonics in the input current. This paper analyzes the cause of the input current harmonics aims to the back EMF and the d-q axis current controller. This paper proposes two control methods to reduce the current harmonics distortion. The first method filters out the harmonics of feedback d-q axis current by using harmonics filter. The second method compensates the d-q axis voltage references to reduce the input current harmonics. The d-q axis compensation voltages are obtained by feed forward controller. The maximum power factor of the proposed method obtains 98.47 %. The experimental results confirm that the proposed control method clears the guideline EN61000-3-2.

Current harmonics reduction method of electrolytic capacitor-less diode rectifier using inverter-controlled IPM motor

This paper proposes a current harmonic reduction method to improve the input current waveform in electrolytic capacitor-less single-phase to three-phase power converters. Typically, the back EMF of an IPM motor is not sinusoidal and contains harmonics caused by the rotor structure; therefore, it causes harmonic distortion in the motor control system and generates harmonics in the input current. In this study, the cause of the input current harmonics induced in the back EMF and the d-q axis current controller are analyzed. Furthermore, this paper proposes a control method to reduce the current harmonic distortion. In the proposed method, the d-q axis voltage references are compensated to reduce the input current harmonics. The d-q axis compensation voltages are obtained by a feed-forward controller. The maximum power factor obtained by the proposed method is 98.0[%]. The experimental results confirm that the proposed control method conforms to the EN61000-3-2 guideline.

Fine current harmonics suppression control for the input current of electrolytic capacitor-less inverter for IPMSM

This paper proposes a current harmonics control method for the input current of an electrolytic capacitor-less inverter for an interior permanent magnet synchronous motor (IPMSM). In general, an IPMSM has large spatial harmonics caused by the rotor structure. The back electromotive force (EMF) of an IPMSM contains harmonics and generates three-phase current harmonics. The three-phase current harmonics result in the input current harmonics of an electrolytic capacitor-less inverter because the power converter system has little energy storage on the DC-link. This paper analyzes an input current harmonics generation mechanism based on averaged DC-link current. The proposed control method that controls the input current harmonics is based on the analysis mechanism. The validity of the proposed method is confirmed through simulation and experimental results.

Fine Current Harmonics Reduction Method for Electrolytic Capacitor-Less and Inductor-Less Inverter Based on Motor Torque Control and Fast Voltage Feedforward Control for IPMSM

In an electrolytic capacitor-less and inductor-less single-phase-to-three-phase inverter, the inverter controls not only the motor but also the input power factor. If the motor has large spatial harmonics, the harmonics flow into the input current at the source side. This paper proposes two new power factor correction methods to improve the input current response of a fundamental frequency and to reduce the input current harmonics. The first method realizes high-power-factor operation by adopting a motor torque control strategy that focuses on the relationship between the input power and the motor torque. The motor torque control allows for designing the gain of the controller to realize a high power factor and enhances the robustness against motor parameter variations. The second method improves the inverter output power response by using a fast voltage feedforward control (FVFFC) that controls the inverter output power directly by focusing on the average dc-link current. The FVFFC reduces the input current harmonics owing to the spatial harmonics of an interior permanent-magnet synchronous motor, and the input current harmonics satisfy the recommendations of guideline JIS 61000-3-2. The effectiveness of the proposed methods is verified through experiments.

Realization of IPMSM drive systems without both an electrolytic capacitor and an line inductor

This paper proposes a control method to realize interior permanent magnet synchronous motor (IPMSM) drive system without using both an electrolytic capacitor and an line inductor. In general, an electrolytic capacitor-less inverter shows input current vibration in the source side if there is a line impedance on the source. This vibration is caused by resonance with the line impedance and the DC-link capacitor. The current vibration causes current distortion and lowers the power factor. In general, the input current vibration has high frequency components because of low line impedance values. Thus, in order to reduce the input current vibration using the conventional dumping feedback control, it is necessary to lower the frequency by adding an inductor to the line impedance. In this paper, the authors propose a method that adds a cancellation voltage pulse to the three-phase voltage reference of the inverter, in order to prevent input current vibration. The simulation and experimental results confirm that the proposed method reduces the input current vibration effectively. The maximum power factor obtained by using the proposed method is 98.09 % and THD is 17.95 %.

Harmonic current reduction control of IPMSM drive inverter without inductor or electrolytic capacitor

In a single-phase to three-phase inverter that does not have an inductor or electrolytic capacitor, the inverter must control not only the motor but also the input power factor because there is no power factor correction circuit or energy buffer. To improve the input power factor, several control methods are proposed. However, if the motor has large spatial harmonics caused by the rotor structure, the bandwidth limitations of the control system adversely affect the source current response and thereby cause source current harmonics. This paper proposes a harmonic current reduction controller that makes it possible to obtain a sinusoidal source current. The proposed controller focuses on the relationship between the source current and the average DC-link current and controls the source current using a feedforward control method. The effectiveness of the proposed method is experimentally verified.

Soft-switching-interleaved power factor correction converter with lossless snubber

This paper describes a soft-switching-interleaved power factor correction (PFC) converter. The proposed PFC converter reduces the input-current ripple by using an interleave-control method and realizes high efficiency through the soft-switching operation of all switching devices, without requiring a large auxiliary resonant circuit. In order to confirm that the proposed converter achieves soft-switching operation, a prototype of the PFC converter was experimentally investigated. The experimental results indicate that the proposed converter can realize soft-switching operation on all switching devices, reduce the amount of input current ripple, generate a unity input power factor of 99% or more, and maintain both a sinusoidal input current and a constant output-voltage control. The efficiency of the proposed PFC converter with a lossless snubber is higher than that of the PFC converter without the snubber. Moreover, an improvement technique for reducing the power-source current distortion is proposed. Improvement in the amount of source-current distortion is confirmed by using a waveform-improvement method in both the simulation and the experiment, reducing the total harmonic distortion (THD) by 2.74%.