A power converter comprising an energy transfer element is coupled between an input of the power converter and an output of the power converter. A cascode circuit generates a first sense signal and a second sense signal. A controller controls the switching of the cascode circuit to transfer energy from the input of the power converter to the output of the power converter. The controller comprising a current sense circuit generates a current limit signal and an overcurrent signal in response to the first sense signal and the second sense signal. A control circuit generates a control signal in response to the current limit signal and the overcurrent signal. A drive circuit comprising a first stage gate drive circuit generates a drive signal in response to the control signal to reduce EMI, and a second stage of gate drive circuit to enable accurate current sensing of the cascode circuit.

The present invention discloses a power conversion system and a method for pre-charging DC-Bus capacitors therein. The power conversion system comprises a plurality of power modules, each including a power input end; a charging input end; a power output end; at least one power conversion unit, each of the power conversion unit including at least one DC-Bus capacitor and being electrically connected to the power input end and the power output end; and a pre-charging unit electrically connected to the charging input end for receiving direct current and electrically connected to the DC-Bus capacitor for pre-charging the DC-Bus capacitor. The power input ends of the plurality of power modules are connected in series and then electrically connected to an AC power source, and the power output ends of the plurality of power modules are connected in parallel.

A system for providing power from an AC power supply to an external load. The system includes a current limiter circuit, connected to an input of a switched-mode power supply. The system includes the switched-mode power supply that provides a first voltage signal and a second voltage signal. The system includes a supervisor circuit that is connected to the first output of the switched-mode power supply and coupled to a relay control circuit. The supervisor circuit monitors the first voltage signal and enables the relay control circuit. The relay control circuit provides a first voltage corresponding to the first voltage signal to a first voltage rail and provides a second voltage corresponding to the second voltage signal to a second voltage rail. A relay powered by a connection to the first voltage rail or the second voltage rail connects the AC power supply to an external load.

A voltage source inverter comprises a rectifier circuit having an input for connection to a multi-phase AC power source and converting the AC power to DC power and an inverter circuit for receiving DC power and converting the DC power to AC power. A DC bus circuit is connected between the rectifier circuit and the inverter circuit to provide a relatively fixed DC voltage for the inverter circuit, the DC bus circuit comprising a DC bus including a first bus rail comprising an inductor and a second bus rail, and a soft charge circuit connected in series with a DC bus capacitor network between the first and second rails, the DC bus capacitor network comprising a first capacitor branch including a pair of capacitors with a fuse connected in series between the capacitors, a balancing resistor across each capacitor and a snubbing capacitor connected across the fuse.

A power converter comprising an energy transfer element is coupled between an input of the power converter and an output of the power converter. A cascode circuit generates a first sense signal and a second sense signal. A controller controls the switching of the cascode circuit to transfer energy from the input of the power converter to the output of the power converter. The controller comprising a current sense circuit generates a current limit signal and an overcurrent signal in response to the first sense signal and the second sense signal. A control circuit generates a control signal in response to the current limit signal and the overcurrent signal. A drive circuit comprising a first stage gate drive circuit generates a drive signal in response to the control signal to reduce EMI, and a second stage of gate drive circuit to enable accurate current sensing of the cascode circuit.

A power conversion apparatus includes: a converter converting AC voltage supplied from an AC power supply via a switch unit, into DC voltage; a smoothing capacitor smoothing the DC voltage output from the converter; a resistor suppressing electric current flowing into the smoothing capacitor; a switch short-circuiting the both ends of the resistor; a filter including reactors and capacitors and that removes noise; and a control unit controlling opening and closing of the switch unit and the switch. The control unit changes the switch unit from the open state to the closed state with the switch in an open state if the voltage across the smoothing capacitor is lower than a voltage threshold, and changes the switch unit from the open state to the closed state with the switch in an closed state if the voltage across the smoothing capacitor is equal to or greater than the voltage threshold.

A load control device for controlling power delivered from an alternating-current power source to an electrical load may comprise a controllably conductive device, a control circuit, and an overcurrent protection circuit that is configured to be disabled when the controllably conductive device is non-conductive. The control circuit may be configured to control the controllably conductive device to be non-conductive at the beginning of each half-cycle of the AC power source and to render the controllably conductive device conductive at a firing time during each half-cycle (e.g., using a forward phase-control dimming technique). The overcurrent protection circuit may be configured to render the controllably conductive device non-conductive in the event of an overcurrent condition in the controllably conductive device. The overcurrent protection circuit may be disabled when the controllably conductive device is non-conductive and enabled after the firing time when the controllably conductive device is rendered conductive during each half-cycle.

The invention provides an inverter system and a method of using said inverter system. A rectifier stage of the inverter system is used to charge a DC link stage to a first voltage level and a control module determines whether voltages over series connected capacitors of the DC link stage are balanced. If those voltages are balanced, the rectifier stage charges the DC link stage to a second voltage level higher than the first voltage level.

A semiconductor device includes a rectifier circuit that rectifies an AC input voltage, a zero-cross detection circuit that detects a zero-cross of the AC input voltage, a control circuit that turns on the rectifier circuit at a timing determined by the zero-cross detected by the zero-cross detection circuit and a predetermined phase angle, and the phase angle is set so that an output voltage of the rectifier circuit is gradually increased.

The invention relates to a converter configured to supply an energy consuming element during an operating phase, and to charge said capacitor during a pre-charging phase prior to the operating phase. Said converter comprises a power factor correction circuit comprising said capacitor and thyristors. Said converter further comprises a control system configured to control said pre-charging phase. Said control system comprises a control unit configured to, during said operating phase, detect the state of charge of the capacitor, and to generate a control signal configured to control said thyristors as a function of the state of charge of the capacitor.