Abstract: A precharge system and method are provided. The precharge system comprises a load circuit, a precharge circuit and a control circuit. The load circuit comprises an input terminal, an input switch and a bus capacitor. The precharge circuit comprises a precharge resistor and a precharge switch. The precharge method comprises: during the load circuit being in a precharge mode, controlling the input switch to be in an off state, and controlling the precharge switch to switch between the on and off state for multiple times; and during the load circuit being in a work mode, controlling the input switch to be in an on state. During the load circuit being in the precharge mode, when the precharge switch is in the on state, a consuming power of the precharge resistor is larger than a threshold power and is smaller than or equal to a limit power of the precharge resistor.

Abstract: A precharge system and method are provided. The precharge system comprises a load circuit, a precharge circuit and a control circuit. The load circuit comprises an input terminal, an input switch and a bus capacitor. The precharge circuit comprises a precharge resistor and a precharge switch. The precharge method comprises: during the load circuit being in a precharge mode, controlling the input switch to be in an off state, and controlling the precharge switch to switch between the on and off state for multiple times; and during the load circuit being in a work mode, controlling the input switch to be in an on state. During the load circuit being in the precharge mode, when the precharge switch is in the on state, a consuming power of the precharge resistor is larger than a threshold power and is smaller than or equal to a limit power of the precharge resistor.

Abstract: An inverter and an active power filter system have been disclosed in the invention, so that the application range of the inverter under the occasions of different capacitor requirement can be widened, the cost can be decreased, and the efficiency can be improved. The technical scheme is: an auxiliary capacitor module can be added on the traditional inverter structure and connected in parallel selectively with the capacitor in the inverter. In a system without connecting an external auxiliary capacitor module, the value of capacitance can be designed to be smaller to satisfy the application under normal occasions. If the device operates under the occasions having large harmonic current or having large neutral line current, the ripple current on the capacitor will be larger so that large capacitance will be required to satisfy the life requirement, therefore, the problem can be solved by a method of installing an auxiliary capacitor module.

Abstract: A feedback control circuit for a power converter and a power converter system, includes a sampling network, configured to sample an input or output of the power converter, and output a first sampled signal; a filtering network, configured to receive the first sampled signal and output a second sampled signal, the filtering network filtering a ripple signal at a preset frequency out from the first sampled signal, so as to remain signals therein outside the preset frequency, while maintaining a phase delay between the second sampled signal and the first sampled signal within a preset range; a control and drive circuit, configured to receive the second sampled signal, and regulate in accordance with the second sampled signal a control signal outputted from the control and drive circuit to the power converter.

Abstract: An inverter and an active power filter system have been disclosed in the invention, so that the application range of the inverter under the occasions of different capacitor requirement can be widened, the cost can be decreased, and the efficiency can be improved. The technical scheme is: an auxiliary capacitor module can be added on the traditional inverter structure and connected in parallel selectively with the capacitor in the inverter. In a system without connecting an external auxiliary capacitor module, the value of capacitance can be designed to be smaller to satisfy the application under normal occasions. If the device operates under the occasions having large harmonic current or having large neutral line current, the ripple current on the capacitor will be larger so that large capacitance will be required to satisfy the life requirement, therefore, the problem can be solved by a method of installing an auxiliary capacitor module.