Kazuma Suzuki

Input power factor control of high-frequency-link AC/DC converter

This paper presents input-power-factor control of a high-frequency-link AC/DC converter. The authors propose the circuit topology and its PWM strategy of the high-frequency-link AC/DC converter for improving the input-power-factor to all the angle range. The effectiveness of a control method of high-frequency-link AC/DC converter has been verified by experiments.

Soft-switching three-phase AC to DC converter isolated by high-frequency transformer

This paper presents a soft-switching three-phase AC to DC converter isolated by high-frequency transformer. The-soft switching conditions are indicated and the soft-switching control method are derived. The effectiveness of the proposed circuit and control method are verified by experiments using a 1 kW prototype.

New PWM technique for grid-tie isolated bidirectional DC-AC inverter based high frequency transformer

This paper presents a new PWM switching technique for controlling a bidirectional isolated DC-AC-AC inverter along with its soft-switching technique. The proposed PWM technique has the ability to control the input DC current and to inject a sinusoidal three-phase current to the grid at unity power factor. In the first stage, an H-bridge converter is used to convert the DC voltage to a high-frequency square-wave single-phase voltage. In the second stage, a matrix converter is used to convert the high-frequency voltage waveform to conventional three-phase voltage synchronized with the grid. Therefore, a high-frequency transformer is used to link the H-bridge output voltage to the matrix converter input voltage. The proposed soft-switching technique is achieved by connecting shunt capacitors across the DC-AC-AC converter switches. The mathematical model and the circuit operation for soft-switching are presented along with the voltage controllable limits. The effectiveness of the proposed technique has been verified experimentally using a laboratory prototype.

Modeling and control of bidirectional isolated battery charging and discharging converter based high-frequency link transformer

This paper presents a new PWM technique for controlling a bidirectional isolated grid-tie AC-AC-DC converter. The proposed PWM technique has the ability to control the dc voltage and current in addition to achieving unity power factor at the grid side. In the first stage, a matrix converter is used to convert the grid three-phase voltage to a high-frequency square-wave single-phase voltage. In the second stage, an H-bridge converter is used to convert the high-frequency square-wave voltage to dc voltage. Therefore, a high-frequency transformer is used to link the matrix and the H-bridge converters. A conventional PI controller has been used to control the dc voltage and current for battery charging and discharging control. The grid current is always in-phase with the grid voltage for unity power factor. The effectiveness of the proposed technique has been verified experimentally using laboratory prototype.

Conducted noise reduction on AC/DC converter using SiC-MOSFET

This paper describes the frequency analysis method of the conducted noise in AC/DC converter using SiC-MOSFET on the basis of the leakage current by switching. The error of the experimental and simulation result of the disturbance voltage is 10 dBμV. The simulation result can be closely simulated including resonance points. Furthermore, this paper presented verification results of designed EMI filters by performing the experiment. The disturbance voltage can be reduced by maximum 20dBμV with the common-mode filter. Moreover, the experimental result with the common-mode filter shows good agreement with the simulation result. Effectiveness is verified by several experimental and simulation results.

Isolated AC/DC Converter Using Soft-Switching Technique

This paper presents the suppression control of the source current harmonics of the bi-directional isolated AC/DC converter. The proposed circuit consists of three-phase AC to high-frequency single-phase AC matrix converter, high-frequency transformer, and single-phase AC to DC converter. The authors have achieved the soft-switching of all commutations of the both converters. The further downsizing of the isolated AC/DC converter can be achieved without decreasing the system efficiency by using the soft-switching technique. However, in the converter, the source currents are distorted due to the approximation of the transformer current as the rectangular waveform. Therefore, the authors propose the improved control for the suppression of the source current harmonics of the bi-directional isolated AC/DC converter. The effectiveness of the improved control is verified by experiments.

Suppression control of source current harmonics of bi-directional isolated AC/DC converter using soft switching technique

This paper presents the suppression control of the source current harmonics of the bi-directional isolated AC/DC converter. The proposed circuit consists of three-phase AC to high-frequency single-phase AC matrix converter, high-frequency transformer, and single-phase AC to DC converter. The authors have achieved the soft-switching of all commutations of the both converters. The further downsizing of the isolated AC/DC converter can be achieved without decreasing the system efficiency by using the soft-switching technique. However, in the converter, the source currents are distorted due to the approximation of the transformer current as the rectangular waveform. Therefore, the authors propose the improved control for the suppression of the source current harmonics of the bi-directional isolated AC/DC converter. The effectiveness of the improved control is verified by experiments.

Isolated bidirectional single-phase AC/DC converter using a soft-switching technique

This paper presents an isolated bidirectional single-phase AC/DC converter using a soft-switching technique. The AC/DC converter consists of a single-phase matrix converter, a high-frequency transformer and an H-bridge converter. The authors propose the soft-switching control for all switches. The efficiency improvement of the proposed converter using the soft switching technique is verified by experiments.

High-frequency link AC/DC converter using matrix converter with soft-switching technique

This paper presents a high-frequency link AC/DC converter using a soft-switching technique, which consists of primary matrix converter, high-frequency link transformer and secondary diode rectifier circuit. The control method of the high-frequency link AC/DC converter to satisfy the soft switching conditions is proposed. The switching loss can be reduced because of using soft switching. The effectiveness of the proposed PWM strategy and soft switching in the high-frequency link AC/DC converter have been verified by experiments.

Soft-switching parameter design for an isolated three-phase AC/DC converter

In recent years, a demand of an isolated AC/DC converter for the grid connection increases. The authors have proposed an isolated three-phase AC/DC converter using soft-switching technique and the control. This paper presents a soft-switching parameter design for the isolated three-phase AC/DC converter. The effectiveness is verified by experiments.