Abstract: Embodiments of the present disclosure relate to an uninterruptible power supply. The uninterruptible power supply comprises a switch, a power management module, an inverter and a controller. The switch is arranged between a load and a power source, the power source configured to supply power to the load. The power management module comprises a main energy storage and configured to reduce a ripple experienced by the main energy storage. The inverter is arranged between and coupled to the power management module and the load. The controller is coupled to the power management module, the inverter and the switch, the controller configured to control the inverter to regulate output voltage magnitude and frequency by regulating the power exchange between the inverter and the power source. According to embodiments of the present disclosure, the overcharging of the energy storage during sudden load rejections or utility phase jumps can be avoided.

Abstract: Embodiments of the present disclosure relate to parallel 3-level inverter without midpoint connection. The parallel 3-level inverter includes a plurality of parallel converters coupled in parallel between a common DC bus and a common AC output, wherein each of the plurality of parallel converters comprises a midpoint and the midpoints of the plurality of parallel converters are disconnected from each other.

Abstract: Embodiments of the present disclosure provide an electrical apparatus, a power supply system having the same and a method of manufacturing the electrical apparatus. The electrical apparatus includes a detecting circuit coupled to a generator and configured to detect a frequency of the generator. The electrical apparatus also includes a controller coupled to the detecting circuit and configured to receive a first signal indicating the detected frequency and adjust the frequency of the generator in response to determining that the detected frequency is out of a predetermined frequency range. In this way, an actively controlling of the changing rate of the power to and from generator may be achieved, if the generator frequency exceeds the configured limits.

Abstract: Embodiments of present disclosure relate to apparatus and method for flux management in the ZISC based UPS system. The apparatus comprises: a first determining unit configured to determine a first offset flux on a series reactor in the ZISC based UPS system when power quality events occur in a grid connected to the ZISC based UPS system and the ZISC based UPS system operates in a grid-connected mode; and a first resetting unit configured to provide synthetic impedance damping to the series reactor to reset the first offset flux.

Abstract: Embodiments of the present disclosure relate to method and apparatus for detecting grid islanding in a grid supporting voltage source converter. The method includes modulating an output voltage at an output of the grid supporting voltage source converter; determining at least one grid parameter at an input to the grid supporting voltage source converter; and detecting the grid islanding for the grid supporting voltage source converter based on the at least one grid parameter.

Abstract: Embodiments of the present disclosure provide an electrical apparatus, a power supply system having the same and a method of manufacturing the electrical apparatus. The electrical apparatus includes a detecting circuit coupled to a generator and configured to detect a frequency of the generator. The electrical apparatus also includes a controller coupled to the detecting circuit and configured to receive a first signal indicating the detected frequency and adjust the frequency of the generator in response to determining that the detected frequency is out of a predetermined frequency range. In this way, an actively controlling of the changing rate of the power to and from generator may be achieved, if the generator frequency exceeds the configured limits.