A power supply system includes a power supply, a converter, and a processor. The converter converts voltage of the electric power supplied from the power supply. The processor is configured to generate a first control signal to control the converter to output a target voltage or a target current via a feedback control based on the first control signal. The processor is configured to generate a second control signal to detect a state of the power supply. The processor is configured to combine the first control signal and the second control signal to control the converter.

Due to increase of demand for safety of device, reinforcement of insulation of exposed conductive parts is required also in power conversion device. Relay unit having optical transmission unit, signal processing unit and power generating unit is provided between control circuit unit and gate drive circuit unit which form control device for an inverter. A gate signal generated in the control circuit unit is inputted into the signal processing unit of the relay unit through the optical transmission unit, and is outputted to the gate drive circuit unit from the signal processing unit through the optical transmission unit. Further, AC power is supplied to the power generating unit of the relay unit from a control device low-voltage AC power source through high-withstand voltage transformer. AC power is supplied to the gate drive circuit unit from the power generating unit of the relay unit through high-withstand voltage transformer.

Due to increase of demand for safety of device, reinforcement of insulation of exposed conductive parts is required also in power conversion device. Relay unit having optical transmission unit, signal processing unit and power generating unit is provided between control circuit unit and gate drive circuit unit which form control device for an inverter. A gate signal generated in the control circuit unit is inputted into the signal processing unit of the relay unit through the optical transmission unit, and is outputted to the gate drive circuit unit from the signal processing unit through the optical transmission unit. Further, AC power is supplied to the power generating unit of the relay unit from a control device low-voltage AC power source through high-withstand voltage transformer. AC power is supplied to the gate drive circuit unit from the power generating unit of the relay unit through high-withstand voltage transformer.

A photovoltaic inverter is provided, including an inverter circuit, a data sampling module, and a control module. The inverter circuit includes a switch component and an alternating current output terminal. The data sampling module is configured to collect, from the alternating current output terminal, an instantaneous current value at each sampling point moment in target sampling duration and an instantaneous value of each-phase current at a target moment. The control module is configured to: determine a valid current value of the target sampling duration based on the instantaneous current value at each sampling point moment, determine an upper switching frequency limit and a lower switching frequency limit of an N.sup.th switching period based on the valid current value, and determine a target instantaneous current value I.sub.N based on the instantaneous value of each-phase current at the target moment.

A photovoltaic inverter is provided, including an inverter circuit, a data sampling module, and a control module. The inverter circuit includes a switch component and an alternating current output terminal. The data sampling module is configured to collect, from the alternating current output terminal, an instantaneous current value at each sampling point moment in target sampling duration and an instantaneous value of each-phase current at a target moment. The control module is configured to: determine a valid current value of the target sampling duration based on the instantaneous current value at each sampling point moment, determine an upper switching frequency limit and a lower switching frequency limit of an N.sup.th switching period based on the valid current value, and determine a target instantaneous current value I.sub.N based on the instantaneous value of each-phase current at the target moment.

This conversion device converts DC powers from a plurality of DC power supplies, to AC power and supplies the AC power to a load. The conversion device includes: a filter circuit including an AC reactor and a first capacitor; a DC/AC inverter connected to the load via the filter circuit; DC/DC converters provided between the respective plurality of DC power supplies and the DC/AC inverter; a second capacitor provided between the DC/AC inverter and the DC/DC converters; and a control unit configured to set a current target value for each of the DC/DC converters to thereby be synchronized with current of the AC power, based on voltage of the AC power, voltage variation due to current flowing through the AC reactor and an impedance thereof, reactive currents respectively flowing through the first capacitor and the second capacitor, and voltage of each DC power.

This conversion device converts DC powers from a plurality of DC power supplies, to AC power and supplies the AC power to a load. The conversion device includes: a filter circuit including an AC reactor and a first capacitor; a DC/AC inverter connected to the load via the filter circuit; DC/DC converters provided between the respective plurality of DC power supplies and the DC/AC inverter; a second capacitor provided between the DC/AC inverter and the DC/DC converters; and a control unit configured to set a current target value for each of the DC/DC converters to thereby be synchronized with current of the AC power, based on voltage of the AC power, voltage variation due to current flowing through the AC reactor and an impedance thereof, reactive currents respectively flowing through the first capacitor and the second capacitor, and voltage of each DC power.

A power system includes an inverter that convert a DC voltage to a three-phase alternating current (AC) voltage. One or more switch drivers generate a pulse width modulation (PWM) drive signal that drives the inverter. The power system further includes a controller that determines a modulation index associated with the PWM drive signal and injects a harmonic into the PWM drive signal in response to the modulation index exceeding a modulation index threshold value.

An electrical assembly comprising power conversion system (PCM) having an output (OT1), a filter device (2) connected to the output (OT1) of the power conversion system (PCM), a pre-charging circuit (PCC), and an interface (ITF) for connecting the electrical assembly to an electrical power network (GRD). The filter device (2) comprises inductor system and filter capacitor system adapted to co-operate with the inductor system for filtering an alternating current. The filter device (2) comprises a capacitor switch device (S3) for disconnecting the filter capacitor system from the inductor system. The electrical assembly comprises a grid switch device (S4) connected in parallel with the pre-charging circuit (PCC).

The parallel connected pre-charging circuit (PCC) and grid switch device (S4) are operationally connected between the output (OT1) of the power conversion system (PCM) and the interface (ITF) of the electrical assembly.

An electrical assembly comprising power conversion system (PCM) having an output (OT1), a filter device (2) connected to the output (OT1) of the power conversion system (PCM), a pre-charging circuit (PCC), and an interface (ITF) for connecting the electrical assembly to an electrical power network (GRD). The filter device (2) comprises inductor system and filter capacitor system adapted to co-operate with the inductor system for filtering an alternating current. The filter device (2) comprises a capacitor switch device (S3) for disconnecting the filter capacitor system from the inductor system. The electrical assembly comprises a grid switch device (S4) connected in parallel with the pre-charging circuit (PCC).

The parallel connected pre-charging circuit (PCC) and grid switch device (S4) are operationally connected between the output (OT1) of the power conversion system (PCM) and the interface (ITF) of the electrical assembly.