A precharge system for precharging a DC bus circuit includes a first input, first and second circuit branches, and a controller, where the first circuit branch includes a first contactor between the first input and an AC to DC converter, the second circuit branch has: a disconnect switch coupled to the first input; a variable frequency drive (VFD) with an AC input coupled to the disconnect switch; an inductor coupled to an AC output of the VFD; and a second contactor coupled to the inductor. The precharge VFD provides precise control of the precharge operation such as charging time, current limiting, short-circuit and ground fault protection, monitoring DC Bus capacitance and verifies the health of the shared DC bus circuit through startup diagnostic. The controller opens the first contactor and closes the second contactor and the disconnect switch in a first mode to precharge the DC bus circuit using the VFD, and in a second mode, the controller closes the first contactor and opens the second contactor and the disconnect switch.

A switching mode power supply (SMPS) circuit is disclosed herein which includes: a first input rectification circuit, a first capacitor, a feedback control and driving circuit, and at least one boost circuit. The first input rectification circuit rectifies an input voltage and charges the first capacitor, forming a first loop. The second input rectification circuit rectifies the input voltage and charges the second capacitor, forming a second loop. The first inductor, second capacitor and first switching component form a third loop in which rectified voltage on the second capacitor charges the first inductor. The first inductor, second capacitor, first capacitor and first output rectification circuit form a fourth loop in which induced voltage on the first inductor and voltage on the second capacitor are superimposed to charge the first capacitor through the first output rectification circuit. The SMPS circuit provides low noise, high efficiency, and no inrush current in the first output rectification circuit.

A frequency converter includes a rectifier on an input side and a support capacitor downstream of the rectifier. Input-side phases of the rectifier feed the backup capacitor via multiple half-bridges of the rectifier. The half-bridges have active switching elements and the rectifier is designed as a recovery rectifier, The input-side phases are connected to grid-side phases of a multiphase supply grid via an upstream circuit. Each grid-side phase is connected to one of the input-side phases within the upstream circuit via a respective phase capacitor. A control facility controls the active switching elements when a first charge state of the support capacitor is reached and input-side phase voltages are applied to the input-side phases via the active switching elements. Voltages running in the opposite direction to the grid-side phase voltages are applied to the grid-side phases to which the input-side phases are connected via the phase capacitors.

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.

In accordance with some embodiments of the present invention, a wireless power receiver that ramps an ASK impedance is presented. A method of amplitude shift key (ASK) modulation in a wireless power receiver includes initiating transition of an ASK impedance from a first state to a second state, the ASK impedance being coupled to a resonant circuit that includes a wireless power receive coil that receives a time-varying magnetic field; transitioning the ASK impedance from the first state to the second state according to the transition over a plurality of switching cycles of the time-varying magnetic field; and holding the second state.

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 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.

A converter including a first terminal and a second terminal, the first terminal configured for connection to a first network, the second terminal configured for connection to a second network; at least one switching module arranged to interconnect the first terminal and the second terminal, the switching module including at least one module switching element and at least one energy storage device, the module switching element and the energy storage device arranged to be combinable to selectively provide a voltage source, the switching module switchable to control a transfer of power between the first and second networks; the switching module including a discharge circuit, the discharge circuit including a discharge switching element and a discharge resistor, the discharge switching element switchable to switch the corresponding discharge resistor into and out of the corresponding switching module; and a controller configured to selectively control the switching of the discharge switching element.

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.

The present disclosure provides a power supply circuit without a charging loop, and a power management system. The power supply circuit comprises an alternating current switch component, a photovoltaic switching component and a direct-current bus capacitor. The alternating current switch component is configured to electrically connect a live wire of a three-phase alternating current to a direct-current bus, and cause, when an alternating current is selected to charge the direct-current bus capacitor, a voltage across two ends of a direct-current bus capacitor to steadily rise to a target voltage. The photovoltaic switching component is configured to electrically connect a photovoltaic power supply to the direct-current bus, and cause, when the photovoltaic power supply is selected to charge the direct-current bus capacitor, the voltage across the two ends of the direct-current bus capacitor to steadily rise to the target voltage. The direct-current bus capacitor is electrically connected between a positive electrode and a negative electrode of the direct-current bus. When the alternating current or the photovoltaic power supply is electrically connected to the direct-current bus, the alternating current switch component or the photovoltaic switching component can control the voltage across the two ends of the direct-current bus capacitor to stably rise to the target voltage, thereby preventing causing damage to components on the direct-current bus by a large impact current generated by a rapid rise of the voltage across the two ends of the direct-current capacitor.