A power conversion device includes a voltage-type power converter and a current-type power converter each of which performs power conversion between AC and DC, and a controlling circuitry, and power is transmitted/received between AC sides via a DC circuit. In first starting control for starting the voltage-type power converter and the current-type power converter, the controlling circuitry controls a semiconductor element of at least one of the voltage-type power converter and the current-type power converter, to adjust DC voltage at DC terminals of the voltage-type converter to a set first voltage value, thereby controlling current flowing through the DC circuit to be first current not greater than a rated current value of the semiconductor elements.

A direct power converter includes a converter that rectifies a single-phase AC voltage, converts AC power into DC power, and outputs first instantaneous power; a power buffer circuit that receives and supplies power between the converter and a DC link and that performs buffering second instantaneous power; and an inverter that converts a DC voltage at the DC link into a second AC voltage and outputs the second AC voltage. A period for which a current that flows from the converter to the power buffer circuit continuously flows in a period shorter than a half-period of the AC voltage is longer when third power input to the inverter, fourth power output by the inverter, or an average value of the first instantaneous power decreases to a value which is less than a first threshold, from a value which is greater than or equal to a second threshold that is greater than or equal to the first threshold.

This application provides a rectifier, an inverter, and a wireless charging device. The rectifier includes a signal conversion unit and a switchable capacitor unit that are mutually coupled. The switchable capacitor unit is configured to switch a rectification mode of the rectifier. The rectification mode may include but is not limited to any one of the following: a voltage multiplier rectification mode or a full-bridge rectification mode. Therefore, a variable dynamic range of an output voltage of the rectifier provided in embodiments of this application is large.

The present invention provides an adaptively modulated multi-state inverter system, comprising: a split capacitor, four bridge arms and an isolation switch group, on each of the four bridge arms a pair of complementary power switch groups is arranged; the isolation switch group comprises four fuses and six bidirectional thyristors. The output branches of the first bridge arm, the second bridge arm and the third bridge arm are respectively connected in series with a fuse to output a three-phase voltage, and at three-phase output voltage side two shared auxiliary branches are arranged, one auxiliary branch starts from the fourth bridge arm output branch on which a fuse is connected in series and is then connected to the output terminal of the three-phase voltage via three bidirectional thyristors. The other auxiliary branch starts from the DC side feed branch from the midpoint of the split capacitor, and is connected with the output terminal of the three-phase voltage via three bidirectional thyristors respectively. The invention also provides a modulating method of the multi-state inverter system. The use of the adaptive modulating technology enables the multi-state inverter to have the functions of overcurrent protection, isolation of faulty bridge arms and fault-tolerant control on any single and double bridges.

The present invention provides an adaptively modulated multi-state inverter system, comprising: a split capacitor, four bridge arms and an isolation switch group, on each of the four bridge arms a pair of complementary power switch groups is arranged; the isolation switch group comprises four fuses and six bidirectional thyristors. The output branches of the first bridge arm, the second bridge arm and the third bridge arm are respectively connected in series with a fuse to output a three-phase voltage, and at three-phase output voltage side two shared auxiliary branches are arranged, one auxiliary branch starts from the fourth bridge arm output branch on which a fuse is connected in series and is then connected to the output terminal of the three-phase voltage via three bidirectional thyristors. The other auxiliary branch starts from the DC side feed branch from the midpoint of the split capacitor, and is connected with the output terminal of the three-phase voltage via three bidirectional thyristors respectively. The invention also provides a modulating method of the multi-state inverter system. The use of the adaptive modulating technology enables the multi-state inverter to have the functions of overcurrent protection, isolation of faulty bridge arms and fault-tolerant control on any single and double bridges.

The disclosure discloses a commutation failure prediction method, device and storage medium based on energy accumulation features of inverter. The method includes the following steps: collecting instantaneous values of three-phase valve side current and calculating the derivatives of the three-phase valve side current according to the instantaneous values of three-phase valve side current; the derivative includes positive, negative and zero states; according to the derivatives of the three-phase valve side current, determining the locations of incoming valve and ongoing valve; based on the valve side current of the incoming valve and ongoing valve, calculating energy accumulation features of the 12-pulse inverter; predicting whether the commutation failure from the incoming valve to the ongoing valve will happen according to the states of the derivatives of the three-phase valve side current and the energy accumulation features of the 12-pulse inverter.

The present invention is directed to provide a semiconductor device capable of protecting a switching element even though having a capacitor connected to a control signal input terminal of the switching element. Semiconductor device includes an IGBT including a gate configured to be input a gate signal and a current detection terminal used to detect at least one of overcurrent or short-circuit current, a gate capacitor arranged between the gate and a reference potential terminal, the gate capacitor being disconnected from the gate as needed, and a disconnection unit configured to disconnect a connection between the gate capacitor and the gate when a detection current being a current output from the current detection terminal is equal to or larger than a first current set on a basis of a minimum current causing oscillation in a loop circuit formed by including the IGBT and the gate capacitor.

The present invention is directed to provide a semiconductor device capable of protecting a switching element even though having a capacitor connected to a control signal input terminal of the switching element. Semiconductor device includes an IGBT including a gate configured to be input a gate signal and a current detection terminal used to detect at least one of overcurrent or short-circuit current, a gate capacitor arranged between the gate and a reference potential terminal, the gate capacitor being disconnected from the gate as needed, and a disconnection unit configured to disconnect a connection between the gate capacitor and the gate when a detection current being a current output from the current detection terminal is equal to or larger than a first current set on a basis of a minimum current causing oscillation in a loop circuit formed by including the IGBT and the gate capacitor.

A direct power converter includes a converter that rectifies a single-phase AC voltage, converts AC power into DC power, and outputs first instantaneous power; a power buffer circuit that receives and supplies power between the converter and a DC link and that performs buffering second instantaneous power; and an inverter that converts a DC voltage at the DC link into a second AC voltage and outputs the second AC voltage. A period for which a current that flows from the converter to the power buffer circuit continuously flows in a period shorter than a half-period of the AC voltage is longer when third power input to the inverter, fourth power output by the inverter, or an average value of the first instantaneous power decreases to a value which is less than a first threshold, from a value which is greater than or equal to a second threshold that is greater than or equal to the first threshold.

A parallel control method and a parallel control system for single-phase inverters and an inverter. Acquiring an output voltage and an output current of each of the single-phase inverters; transforming a voltage and a current in static abc coordinates into dq coordinates by reconstruction and coordinate transformation so as to realize decoupling of the voltage and the current; transforming an output voltage command value of a current loop in dq coordinates into abc coordinates by coordinate transformation; and modulating and generating modulation waves according to an output voltage command value in abc coordinates to control a switching of a power device. In the present application, a plurality of single-phase inverters are controlled to be connected in parallel and are simultaneously started to work, after one of the single-phase inverters is faulted, any other single-phase inverter automatically bears the load of the faulted single-phase inverter, so that a problem of restarting delay of a mutual backup module is solved, a real uninterrupted power supply of the power supply is realized, high reliability is achieved, and influences to vehicle driving are avoided.