Aspects of the disclosure include a power system comprising at least one three-wire active harmonic filter (AHF) configured to be coupled to, and provide compensation current to, a three-phase load, at least one four-wire AHF configured to be coupled to, and provide compensation current to, the three-phase load, and a controller configured to determine a total compensation current to provide to the three-phase load, the total compensation current including a zero component and a non-zero component, determine an output capacity of the at least one three-wire AHF and the at least one four-wire AHF, calculate a current-compensation ratio based on the output capacity of the at least one three-wire AHF and the at least one four-wire AHF, and control the at least one four-wire AHF to provide at least a portion of the non-zero component of the total compensation current to the three-phase load based on the current-compensation ratio.

The present disclosure provides a control method of a DC/DC converter and a related DC/DC converter. The control method allows for: detecting a difference between a first voltage and a second voltage; if an absolute value of the difference between the first voltage and the second voltage is greater than or equal to a preset value, reselecting desired operating states of respective switches in a 1-level state according to the difference between the first voltage and the second voltage and a direction of an average current from a fourth node to a first passive network in the 1-level state; and thus outputting a control signal to enable the voltage difference between the first capacitor and the second capacitor to be reduced, thereby effectively adjusting the neutral-point voltage balance of the DC/DC converter.

Embodiments of the present disclosure provide an insulation monitoring device applied to a power system and a power system. The power system includes at least one power electronic converter module. The insulation monitoring device includes an insulation component, a signal source, an impedance module, and a monitoring module. The insulation component at least partially wraps around the power electronic converter module. The signal source is electrically coupled to a circuit node in the power electronic converter module, the impedance module is connected between the signal source and the insulation component, and the monitoring module is configured to monitor an insulation resistance value of the insulation component, so that an insulation state of the power electronic converter module may be determined.

A converter for an air conditioning system includes a rectifier section configured to receive a multiphase, AC input voltage; a voltage regulator section coupled to the rectifier section, the voltage regulator section configured to control a DC output voltage across a positive DC bus and a negative DC bus; and a controller in communication with the rectifier section and the voltage regulator section, the controller configured to control the converter in a first mode or a second mode in response to a transient detected in the converter.

In one embodiment, an EV charging system includes: a plurality of first converters to receive and convert grid power at a distribution grid voltage to at least one second voltage; a high frequency transformer coupled to the first converters to receive the at least one second voltage and output at least one high frequency AC voltage; and a plurality of port rectifiers coupled to a plurality of secondary windings of the high frequency transformer, each of the port rectifiers comprising a unidirectional AC-DC converter to receive and convert the at least one high frequency AC voltage to a DC voltage. At least some of the port rectifiers may be coupled in series to provide at least one of a charging current or a charging voltage to at least one dispenser to which at least one EV is to couple.

A 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 including an AC/DC conversion unit and at least one DC-Bus capacitor and being connected to the power input end and the power output end; and a pre-charging unit connected to the charging input end for receiving direct current and connected to the DC-Bus capacitor. The pre-charging unit starts to charge the DC-Bus capacitor of one of the power modules when said power module breaks down or the load of the power conversion system is light so that no current flows through the AC/DC conversion unit. The power input ends of the power modules are connected in series and then connected to an AC power source, and the power output ends of the power modules are connected in parallel.

An inverter includes an upper unit comprises a first switch, a second switch and a third switch, wherein during a first half of a cycle of the inverter, the second switch is turned on before and turned off after the third switch, a lower unit comprising a fourth switch, a fifth switch and a sixth switch, wherein during a second half of the cycle of the inverter, the fifth switch is turned on before and turned off after the sixth switch, a flying capacitor connected between the upper unit and the lower unit, and a filter connected to a common node of the upper unit and the lower unit.

An inverter includes an upper unit comprises a first switch, a second switch and a third switch, wherein during a first half of a cycle of the inverter, the second switch is turned on before and turned off after the third switch, a lower unit comprising a fourth switch, a fifth switch and a sixth switch, wherein during a second half of the cycle of the inverter, the fifth switch is turned on before and turned off after the sixth switch, a flying capacitor connected between the upper unit and the lower unit, and a filter connected to a common node of the upper unit and the lower unit.

Systems and methods of this disclosure use low voltage energy storage devices to supply power at a medium voltage from an uninterruptible power supply (UPS) to a data center load. The UPS includes a low voltage energy storage device (ultracapacitor/battery), a high frequency (HF) bidirectional DC-DC converter, and a multi-level (ML) inverter. The HF DC-DC converter uses a plurality of HF planar transformers, multiple H-bridge circuits, and gate drivers for driving IGBT devices to generate a medium DC voltage from the ultracapacitor/battery energy storage. The gate drivers are controlled by a zero voltage switching (ZVS) controller, which introduces a phase shift between the voltage on the primary and secondary sides of the transformers. When the primary side leads the secondary side, the ultracapacitor/battery discharges and causes the UPS to supply power to the data center, and when the secondary side leads the primary side, power flows from the grid back to the UPS, thereby recharging the ultracapacitor/battery.

Systems and methods of this disclosure use low voltage energy storage devices to supply power at a medium voltage from an uninterruptible power supply (UPS) to a data center load. The UPS includes a low voltage energy storage device (ultracapacitor/battery), a high frequency (HF) bidirectional DC-DC converter, and a multi-level (ML) inverter. The HF DC-DC converter uses a plurality of HF planar transformers, multiple H-bridge circuits, and gate drivers for driving IGBT devices to generate a medium DC voltage from the ultracapacitor/battery energy storage. The gate drivers are controlled by a zero voltage switching (ZVS) controller, which introduces a phase shift between the voltage on the primary and secondary sides of the transformers. When the primary side leads the secondary side, the ultracapacitor/battery discharges and causes the UPS to supply power to the data center, and when the secondary side leads the primary side, power flows from the grid back to the UPS, thereby recharging the ultracapacitor/battery.