A power conversion system according to the present disclosure includes a first circuit, a second circuit, and a third circuit. The first circuit has a first external terminal thereof electrically connected to either an AC power supply or an AC load. In the power conversion system, a first internal terminal, a second internal terminal, and a third internal terminal are electrically connected to the same connection unit. The second circuit controls a current or power being input to, or output from, the second circuit itself such that the current or the power is synchronized with power ripples caused by the AC power supply or the AC load. Either the AC power supply or the AC load is electrically connected to the first circuit.

A power conversion apparatus connected to three or more voltage units, includes three or more power conversion circuits connected to respective units of the three or more voltage units; and a multiport transformer connected to the three or more power conversion circuits at mutually different ports, in which at least one voltage unit of the three or more voltage units is an electrical load.

A power conversion system configured to determine whether or not an abnormality is present in a power conversion circuit, and diagnosis method and program for the power conversion circuit are provided. A power conversion system includes a power conversion circuit, a snubber circuit, and a diagnosis unit. The power conversion circuit includes a transformer and a switching element configured to be electrically connected to the transformer, and the power conversion circuit is configured to convert electric power. The snubber circuit is electrically connected to the transformer and is configured to extract electrical energy from the power conversion circuit. The diagnosis unit is configured to make diagnosis for the power conversion circuit in accordance with at least one of a voltage at a terminal of the transformer, a voltage generated at the snubber circuit, or a current generated at the snubber circuit.

The present disclosure provides a method and apparatus for providing electrical isolation using a converter comprising a first converter working in a rectifier mode receiving AC current and providing DC current, a second converter working in an inverter mode receiving said DC current from said first converter and providing AC current, a transformer receiving said AC current from said second converter having an input and output, said transformer providing electric isolation between said input and output, a third converter working in a rectifier mode receiving AC current from said transformer and providing DC current, wherein at least one of said first, second and third converters is a multilevel converter.

Embodiments of this application provide a power conversion circuit. The power conversion circuit includes at least one first power conversion unit connected in series to a first phase line, at least one second power conversion unit connected in series to a second phase line, at least one third power conversion unit connected in series to a third phase line, a plurality of first start circuits connected in series to the first phase line, and a plurality of second start circuits connected in series to the second phase line. Each first start circuit includes a first relay and a first resistor that are connected in parallel, and first relays in all the first start circuits are sequentially closed after the power conversion circuit is powered on, to start the power conversion circuit. Each second start circuit includes a second relay and a second resistor that are connected in parallel.

Disclosed are a switch driving device, in which individual zero voltage switching control of a first switch element and a second switch element forming a bidirectional switch is performed, and a switching power supply including a primary winding to which an alternating-current input voltage is applied, a secondary winding electromagnetically coupled to the primary winding, the bidirectional switch connected in series with the primary winding, a resonance capacitor connected in parallel with at least one of the bidirectional switch and the primary winding, a full-wave rectifier circuit that performs full-wave rectification of an induced voltage occurring in the secondary winding, a smoothing capacitor that smooths output of the full-wave rectifier circuit, and the switch driving device that drives the bidirectional switch. The alternating-current input voltage is directly converted into a direct-current output voltage by extracting a flyback voltage or a forward voltage and the flyback voltage from the secondary winding.

A current fed high-frequency isolated matrix converter and the corresponding modulation and control schemes are provided. The converter includes a current source full-bridge converter, a high-frequency transformer, a matrix converter, and a three-phase filter. An optimized space vector modulation solution is used for controlling the converter, and by comparing magnitudes of three-phase filter capacitor voltages to determine an action sequence of space vectors, switch tubes are turned on at zero voltage. A current source full-bridge circuit adopts a commutation strategy of a secondary clamping, and by calculating a leakage inductive current commutation time, full-bridge switch tubes are turned off at zero current to achieve safe and reliable commutation, and having advantages of a low system loss, a high efficiency, and a high power density.

A system and method for an interleaved inverter including a set of module circuits and an inverter controller. The module circuits include multiple switches. The inverter controller is configured to assign a first phase shift value to each of the module circuits during a normal mode of operation and assign a second phase shift value to at least one of the module circuits during a failure mode of operation. The second phase shift value is greater than the first phase shift value.

An electronic circuit to receive input AC signals having different phases, and to control bidirectional switches corresponding to phases to generate, based on input AC signals having the phases, output AC signals having the phases and having a frequency different from a frequency of the input AC signals, the electronic circuit has reference signal circuitry to generate a reference signal having a frequency higher than the frequency of the output AC signals, and a commutation circuitry to control switching between voltage commutation and current commutation, wherein, in the voltage commutation, the commutation circuitry switches the bidirectional switches corresponding to the phases in sequence based on a voltage level of the output AC signals of the phases before and after a time point when an amplitude of the reference signal becomes a specific amplitude value, and in the current commutation, the commutation circuitry switches the bidirectional switches in parallel.

A circuit for improving the switching speed of a power electronic switching chip and application thereof are provided. The design method of improving the switching speed of the power electronic switching chip is to switch its state in the saturated conductive state to the simulated saturated-high-on-voltage state which is much higher than the traditional low-saturated-on-voltage state. In this way, the carrier density in the base region and the trailing time constant are greatly reduced and the total power consumption of trailing in the cut-off period can be greatly reduced, and the design limit of switching speed can be improved and the service reliability can be achieved. Therefrom, a design method for power supply of high frequency power electronic transformer (converter) is further disclosed.