Abstract: A power conversion system includes a converter circuit and a control circuit. The control circuit controls, through use of PWM signals, high potential-side switches for a U-phase circuit, a V-phase circuit, and a W-phase circuit, respectively. The control circuit alternately switches between a first modulation method and a second modulation method at each half carrier period of each of the PWM signals. In the first modulation method, the control circuit determines, as a first value, a duty ratio of the PWM signal for one of a U phase, a V phase, and a W phase that has a maximum phase voltage. In the second modulation method, the control circuit determines, as a second value, the duty ratio of the PWM signal for one of the U phase, the V phase, and the W phase that has a minimum phase voltage.

Abstract: A control unit controls an inverter circuit such that a positive voltage and a negative voltage are alternately applied to a primary winding. The control unit controls a cycloconverter so as to allow no power to be transmitted between the cycloconverter and the inverter circuit in a first period including an inversion period during which a voltage of the primary winding has its polarity inverted. The control unit also controls the cycloconverter so as to allow power to be transmitted either in a first direction from the cycloconverter toward the inverter circuit, or in a second direction opposite from the first direction, in a second period different from the first period.

Abstract: The control unit controls the converter unit not to cause transfer of power between the transformer circuit unit and the converter unit in the first time period including the reversal time period in which a reversal of polarity of the voltage across the primary winding occurs. The control unit controls the converter unit to cause transfer of power in the first direction from the transformer circuit unit to the converter unit or the second direction opposite to the first direction in the second time period different from the first time period.

Abstract: A power conversion system includes a first capacitor, an isolated type converter circuit, and a control circuit. The first capacitor is connected to the direct-current power supply via an inrush current prevention circuit. The inrush current prevention circuit is switchable at least between a high-impedance state and a low-impedance state. The converter circuit includes a transformer, and the first capacitor is connected to a primary winding wire of the transformer. The control circuit controls the inrush current prevention circuit and the converter circuit to cause the converter circuit to start operating, and then, the control circuit switches the inrush current prevention circuit from the high-impedance state to the low-impedance state.

Abstract: A power conversion system includes a converter circuit and a control circuit. The control circuit controls, through use of PWM signals, high potential-side switches for a U-phase circuit, a V-phase circuit, and a W-phase circuit, respectively. The control circuit alternately switches between a first modulation method and a second modulation method at each half carrier period of each of the PWM signals. In the first modulation method, the control circuit determines, as a first value, a duty ratio of the PWM signal for one of a U phase, a V phase, and a W phase that has a maximum phase voltage. In the second modulation method, the control circuit determines, as a second value, the duty ratio of the PWM signal for one of the U phase, the V phase, and the W phase that has a minimum phase voltage.

Abstract: A power conversion system includes a first capacitor, an isolated type converter circuit, and a control circuit. The first capacitor is connected to the direct-current power supply via an inrush current prevention circuit. The inrush current prevention circuit is switchable at least between a high-impedance state and a low-impedance state. The converter circuit includes a transformer, and the first capacitor is connected to a primary winding wire of the transformer. The control circuit controls the inrush current prevention circuit and the converter circuit to cause the converter circuit to start operating, and then, the control circuit switches the inrush current prevention circuit from the high-impedance state to the low-impedance state.

Abstract: The control unit controls the converter unit not to cause transfer of power between the transformer circuit unit and the converter unit in the first time period including the reversal time period in which a reversal of polarity of the voltage across the primary winding occurs. The control unit controls the converter unit to cause transfer of power in the first direction from the transformer circuit unit to the converter unit or the second direction opposite to the first direction in the second time period different from the first time period.

Abstract: A control unit controls an inverter circuit such that a positive voltage and a negative voltage are alternately applied to a primary winding. The control unit controls a cycloconverter so as to allow no power to be transmitted between the cycloconverter and the inverter circuit in a first period including an inversion period during which a voltage of the primary winding has its polarity inverted. The control unit also controls the cycloconverter so as to allow power to be transmitted either in a first direction from the cycloconverter toward the inverter circuit, or in a second direction opposite from the first direction, in a second period different from the first period.