A momentary-voltage-drop compensation apparatus interconnecting a power system and a DC power supply to a load. The apparatus includes a system interconnection switch connected between the power system and the load, a first power converter that performs DC-AC conversion to DC power of the DC power supply, a second power converter that includes a first terminal connected to the first power converter and the DC power supply, and a second terminal connected between the system interconnection switch and the power system, for performing AC-DC conversion to the AC power supplied from the power system, and a control unit that is connected to the first power converter, and is configured to control, in response to a voltage drop in the power system, the first power converter to output a zero-phase current, a current value of which is no larger than that of a current flowing through the system interconnection switch.

A momentary-voltage-drop compensation apparatus interconnecting a power system and a DC power supply to a load. The apparatus includes a system interconnection switch connected between the power system and the load, a first power converter that performs DC-AC conversion to DC power of the DC power supply, a second power converter that includes a first terminal connected to the first power converter and the DC power supply, and a second terminal connected between the system interconnection switch and the power system, for performing AC-DC conversion to the AC power supplied from the power system, and a control unit that is connected to the first power converter, and is configured to control, in response to a voltage drop in the power system, the first power converter to output a zero-phase current, a current value of which is no larger than that of a current flowing through the system interconnection switch.

The present disclosure includes a precision voltage and frequency converter, comprising of a power factor correction circuit configured to correct the conduction angle of input AC current, in phase with AC voltage source, a reserve DC filter and energy storage unit, a multi-phase unfolding bridge circuit configured to receive a rectified, isolated, and filtered DC voltage derived from the input AC, a voltage and current feedback pulse-width modulator circuit and compensation circuit configured to modify a signal from the multi-phase unfolding bridge circuit, an isolation transformer having a first side and a second side, wherein the isolation transformer is configured to receive an unfolded half-sine signal generated by the multi-phase unfolding bridge on the first side, the second side of the transformer is regulated via an isolated feedback voltage control circuit and compensation circuit to generate on the second side a first output precision voltage and frequency converted AC signal.

The present disclosure includes a precision voltage and frequency converter, comprising of a power factor correction circuit configured to correct the conduction angle of input AC current, in phase with AC voltage source, a reserve DC filter and energy storage unit, a multi-phase unfolding bridge circuit configured to receive a rectified, isolated, and filtered DC voltage derived from the input AC, a voltage and current feedback pulse-width modulator circuit and compensation circuit configured to modify a signal from the multi-phase unfolding bridge circuit, an isolation transformer having a first side and a second side, wherein the isolation transformer is configured to receive an unfolded half-sine signal generated by the multi-phase unfolding bridge on the first side, the second side of the transformer is regulated via an isolated feedback voltage control circuit and compensation circuit to generate on the second side a first output precision voltage and frequency converted AC signal.

A converter circuit converts AC electric power into DC power. An inverter circuit converts the DC power into AC power. A capacitor is connected in parallel to each of the converter circuit and the inverter circuit between these circuits. The capacitor allows variation of an output voltage from the converter circuit, and absorbs variation of an output voltage from the inverter circuit due to a switching operation. An overvoltage protection circuit includes a resistor and a semiconductor element connected in series to each other. The overvoltage protection circuit is connected in parallel to the capacitor to protect the inverter circuit from an overvoltage. First and second control units respectively control the inverter circuit and the overvoltage protection circuit.

A power supply device is provided. The power supply device includes a rectifier circuit for rectifying an inputted alternating current power supply, a capacitor circuit comprising a first and second capacitor which are connected in series, and smoothing the alternating current power supply rectified in the rectifier circuit, an inverter for converting the output power of the capacitor circuit to a preset power and outputting same, a switch for selectively connecting a middle node of the first capacitor and the second capacitor and an end of the alternating current power, a sensor for detecting a size of the alternating current power, and a controller which confirms a power mode of the alternating current power on the basis of an output value of the sensor, and which controls the switch so that the capacitor circuit multiplies and amplifies the selectively rectified alternating current power based on the confirmed power mode.

A power supply device is provided. The power supply device includes a rectifier circuit for rectifying an inputted alternating current power supply, a capacitor circuit comprising a first and second capacitor which are connected in series, and smoothing the alternating current power supply rectified in the rectifier circuit, an inverter for converting the output power of the capacitor circuit to a preset power and outputting same, a switch for selectively connecting a middle node of the first capacitor and the second capacitor and an end of the alternating current power, a sensor for detecting a size of the alternating current power, and a controller which confirms a power mode of the alternating current power on the basis of an output value of the sensor, and which controls the switch so that the capacitor circuit multiplies and amplifies the selectively rectified alternating current power based on the confirmed power mode.

A motor drive device has an abnormality detection function for a power supply unit between its own device and a power supply, and includes: a forward converter that is inputted AC power from the power supply via the power supply input part, and converts the AC power into DC power; a reverse converter that converts the DC power from the forward converter into AC power; a DC link capacitor provided to a DC link between the forward converter and the reverse converter; a voltage detection part that detects voltage of the DC link capacitor; and an abnormality detection part that obtains a voltage change amount for a predetermined time of the DC link capacitor based on voltage values detected by the voltage detection part, and performs abnormality detection on the power supply input part based on the voltage change amount thus obtained.

A power conversion device is provided, which includes: a power conversion circuit that performs power conversion between a primary power and a secondary power; a buffer data accumulation circuit that, in a predetermined buffer cycle, repeatedly acquires data sets relating to a state of the power conversion circuit and store the data sets in a ring buffer; a state monitoring circuit that generates a trigger signal in a case where a state of a predetermined monitoring target satisfies a predetermined condition; and a data replication circuit that, in a case where a trigger signal is generated, stores, in a data storage circuit, a plurality of the data sets accumulated in the ring buffer in a target storage period including a time before a generation time of the trigger signal.

Power conversion systems and methods are provided for ride through of abnormal grid conditions or disturbances, in which a system rectifier is operated in a first mode to regulate a DC voltage of an intermediate DC circuit, an inverter is operated in the first mode to convert DC power from the intermediate DC circuit to provide AC output power to drive a load. In response to detecting an abnormal grid condition, the system changes to a second mode in which the rectifier is turned off and the inverter regulates the DC voltage of the intermediate DC circuit using power from the load.