Abstract: A shadowing compensation device for a solar cell module has an input port, an isolated DC-DC power converter, and an output port. The input port is connected to two output ends of a solar cell array including multiple solar cell modules connected in series. The output port is connected to one of the multiple solar cell modules of the solar cell array. When one of the solar cell modules connected to the output port of shadowing compensation device has been shaded, the isolated DC-DC power converter outputs a compensating current to the solar cell module that has been shaded for increasing the output voltage of the solar cell module that has been shaded, and increasing the output voltage and output power of the solar cell array.

Abstract: A multilevel AC/DC power converter device includes a high-frequency power converter including a first AC port and a low-frequency power converter including a second AC port and a DC port. A power converting method includes: serially connecting the first AC port of the high-frequency power converter and the second AC port of the low-frequency power converter; operating frequency of the low-frequency power converter synchronized with frequency of an AC power source and operating the high-frequency power converter with high-frequency PWM to generate a multilevel AC voltage; and controlling the multilevel AC voltage to obtain a current of an input AC port being sinusoidal and in a same phase with a voltage of the AC power source. Accordingly, the input power factor approaches unity and the low-frequency power converter supplies a DC voltage to a load via a DC output port.

Abstract: A cascade bridge-type DC-AC power converter device includes a low-frequency bridge-type power converter including an AC terminal and a DC bus and a high-frequency bridge-type power converter including an AC terminal. A power conversion method includes: serially connecting the AC terminal of the high-frequency bridge-type power converter and the AC terminal of the low-frequency bridge-type power converter; operating frequency of the low-frequency bridge-type power converter synchronized with frequency of an AC source; and operating the high-frequency bridge-type power converter with high-frequency PWM to generate a multilevel AC voltage. A DC power source connects to the DC bus of the low-frequency bridge-type power converter. No additional power supply circuit will be required for power supply to a DC bus of the high-frequency bridge-type power converter. Accordingly, the power circuit is simplified, and the manufacturing cost is reduced.

Abstract: A shadowing compensation device for solar cell module has an input port, an isolated DC-DC power converter, and an output port. The input port is connected to two output ends of a solar cell array comprised of multiple solar cell modules connected in series. The output port is connected to one of the multiple solar cell modules of the solar cell array. When one of the solar cell modules connected to the output port of shadowing compensation device has been shaded, the isolated DC-DC power converter outputs a compensating current to the solar cell module been shaded for increasing the output voltage of the solar cell module been shaded, and increasing the output voltage and output power of the solar cell array.

Abstract: A cascade bridge-type DC-AC power converter device includes a low-frequency bridge-type power converter including an AC terminal and a DC bus and a high-frequency bridge-type power converter including an AC terminal. A power conversion method includes: serially connecting the AC terminal of the high-frequency bridge-type power converter and the AC terminal of the low-frequency bridge-type power converter; operating frequency of the low-frequency bridge-type power converter synchronized with frequency of an AC source and operating the high-frequency bridge-type power converter with high-frequency PWM to generate a multilevel AC voltage. A DC power source connects to the DC bus of the low-frequency bridge-type power converter. No additional power supply circuit will be required for power supply to a DC bus of the high-frequency bridge-type power converter. Accordingly, the power circuit is simplified and the manufacturing cost is reduced.

Abstract: A multilevel AC/DC power converter device includes a high-frequency power converter including a first AC port and a low-frequency power converter including a second AC port and a DC port. A power converting method includes: serially connecting the first AC port of the high-frequency power converter and the second AC port of the low-frequency power converter; operating frequency of the low-frequency power converter synchronized with frequency of an AC power source and operating the high-frequency power converter with high-frequency PWM to generate a multilevel AC voltage; controlling the multilevel AC voltage to obtain a current of an input AC port being sinusoidal and in same phase with a voltage of the AC power source. Accordingly, the input power factor approaches unity and the low-frequency power converter supplies a DC voltage to a load via a DC output port.

Abstract: A UPS system includes one or more UPS units with identical or different capacities. A control circuit, used to control a DC/AC inverter of the UPS unit, includes a voltage feedback control circuit and a current feedforward control circuit. The voltage feedback control circuit is used to control the amplitude and the waveform of load voltage. The current feedforward control circuit is used to operate the DC/AC inverter of the UPS unit as a virtual fundamental resistor and a virtual harmonic resistor which are serially connected to an output terminal of the DC/AC inverter such that each UPS unit can be distributed to provide an output current according to the capacity ratio of the UPS system.

Abstract: A UPS system includes one or more UPS units with identical or different capacities. A control circuit, used to control a DC/AC inverter of the UPS unit, includes a voltage feedback control circuit and a current feedforward control circuit. The voltage feedback control circuit is used to control the amplitude and the waveform of load voltage. The current feedforward control circuit is used to operate the DC/AC inverter of the UPS unit as a virtual fundamental resistor and a virtual harmonic resistor which are serially connected to an output terminal of the DC/AC inverter such that each UPS unit can be distributed to provide an output current according to the capacity ratio of the UPS system.