Yuki Nakata’s research while affiliated with Nagaoka University of Technology and other places

This paper discusses pulse density modulation (PDM) control methods for a single-phase to three-phase matrix converter (MC) in high-frequency applications. The proposed circuit is used as an interface converter for a wireless power transfer system. This converter can input a frequency of several hundred kilohertz and output a low frequency, that is, 50 Hz or 60 Hz, for a commercial power grid. The proposed circuit implements zero voltage switching (ZVS) operation by using PDM control methods and obtains high efficiency. In this paper, two PDM control strategies are compared: delta–sigma conversion and the PDM pattern generation method based on space vector modulation (SVM), which is proposed here. Also, the experimental results obtained with the proposed system will be presented and discussed. The total harmonic distortions (THDs) of the output voltage with delta–sigma conversion and the PDM pattern generation method based on SVM are found to be 5.96% and 2.15%, respectively. In addition, the maximum efficiencies with delta–sigma conversion and the PDM control based on SVM are 93.4% and 97.3%, respectively. From the results, the validity of the PDM control based on SVM has been confirmed for improvement of the output waveforms and reduction of the switching loss.

This paper presents a direct-type single-phase to three-phase matrix converter with a pulse density modulation (PDM) control method for high-frequency applications. The input frequency of the proposed converter is several hundred kilohertz, and the output frequency is a commercial frequency. The proposed converter reduces the switching loss by zero voltage switching from the PDM control. In this study, the PDM based on space vector modulation (SVM) is applied to a direct-type matrix converter. From the experimental results, the total harmonic distortion in the output voltage is 2.09%, and the maximum efficiency is 95.0%.

This paper discusses pulse density modulation (PDM) control methods for a single-phase to three-phase matrix converter (MC) in high-frequency applications. The proposed circuit is used as an interface converter for a wireless power transfer system. This converter can input a frequency of several hundred kilohertz and output a low frequency, i.e. 50Hz or 60Hz, for commercial power grids. The proposed circuit achieves zero voltage switching operation by using the PDM control method and obtains high efficiency. In this paper, two PDM control strategies are compared: PDM control based on space vector modulation (SVM) (the conventional method) and the proposed PDM method, which combines SVM and delta-sigma modulation. Also, the experimental results of the proposed system will be demonstrated and discussed. As a result, the total harmonic distortion (THD) of the output voltage with the conventional method and the proposed method are 9.05% and 1.87%, respectively, when the modulation ratio is 0.5. Thus, the validity of the proposed method has been confirmed for improvement of the output waveforms.

This paper discusses the pulse density modulation (PDM) control methods for a single-phase to three-phase matrix converter (MC) in the high-frequency application. This converter outputs a commercial power grid frequency, i.e. 50 Hz or 60 Hz from the input of several-hundred-kHz frequency. The proposed circuit achieves zero voltage switching operation by using the PDM control method. In this paper, two PDM control strategies are compared between a conventional PDM control method based on space vector modulation (SVM) and the proposed PDM control method, which is combined with SVM and a delta-sigma conversion. Also, the experimental results of the proposed control method will be demonstrated and discussed. As a result, the total harmonic distortion (THD) of the output voltage with the proposed PDM control method is improved to 1.87% from 9.05% of the conventional PDM control method.

This paper discusses pulse density modulation (PDM) control methods for a single-phase to three-phase matrix converter for high-frequency applications such as the grid interface converter for a wireless power transfer system and high-frequency transformer link system. The input frequency for this converter is assumed as several hundred kHz, and at the same time outputting a commercial frequency, i.e. 50 Hz or 60 Hz. The proposed circuit achieves high efficiency by zero voltage switching from a PDM control method. In the PDM control using delta-sigma conversion, the output waveform has inverse voltage pulse and clamp phenomena on the output voltage waveform. Hence, an improvement method of the output waveform based on SVM is proposed. In this paper, the experimental results using the prototype circuit of indirect matrix converter (IMC) and conventional matrix converter (CMC) with the two PDM control methods are compared. As a result, the THD of the output voltage with delta-sigma conversion and PDM pattern method based on SVM are 5.96% and 2.15% respectively in the experiment using IMC. Furthermore, the maximum efficiency has been improved from 93.4% to 97.3% by applying the proposed PDM method. From the results, the validity of PDM control based on SVM has been confirmed. In addition, a prototype of direct type circuit (CMC) has been built and tested. From the results, the switching at zero voltage and clear sinusoidal output waveform has been confirmed too. As a result, the output voltage THD, which is controlled by the proposed PDM based on SVM are 3.25%.

This paper discusses pulse density modulation (PDM) control methods for a single-phase to three-phase matrix converter (MC) in high-frequency applications. The proposed circuit is used as an interface converter for a wireless power transfer system. This converter can input a frequency of several hundred kilohertz and output a low frequency, i.e., 50Hz or 60Hz, for a commercial power grid. The proposed circuit implements a zero voltage switching (ZVS) operation by using PDM control methods and obtains high efficiency. In this paper, two PDM control strategies are compared: delta-sigma conversion and the PDM pattern generation method based on space vector modulation (SVM), which is proposed here. Also, the experimental results obtained with the proposed system will be presented and discussed. The total harmonic distortions (THDs) of the output voltage with delta-sigma conversion and the PDM pattern generation method based on SVM are found to be 5.96% and 2.15%, respectively. In addition, the maximum efficiencies with delta-sigma conversion and the PDM control based on SVM are 93.4% and 97.3%, respectively. From the results, the validity of the PDM control based on SVM has been confirmed for improvement of the output waveforms and reduction of the switching loss.