An exemplary heating ventilation and cooling (HVAC) system includes a multi-phase power input, an AC-DC rectifier connected to a DC-AC inverter via a DC power bus, a multi-phase power output connecting the DC-AC inverter to a fan blower motor, and at least one redundancy power system. The redundancy power system is configured to bypass at least one of the AC-DC rectifier and the DC-AC inverter.

Provided is a system for seamless power conversion in DC power distribution, the system including power conversion devices connected in parallel, and performing conversion from a AC voltage to a DC voltage between an AC power distribution network and a DC power distribution network, wherein a master power conversion device among the power conversion devices converts the AC voltage supplied from the AC power distribution network into the DC voltage including an AC voltage at a preset level, and supplies the DC voltage to a DC power distribution line of the DC power distribution network, and the remaining power conversion devices that are slave power conversion devices detect the DC voltage at the DC power distribution line in real time, and when the AC voltage is not sensed from the detected DC voltage, one of the slave power conversion devices is converted into a master power conversion device.

Provided is a system for seamless power conversion in DC power distribution, the system including power conversion devices connected in parallel, and performing conversion from a AC voltage to a DC voltage between an AC power distribution network and a DC power distribution network, wherein a master power conversion device among the power conversion devices converts the AC voltage supplied from the AC power distribution network into the DC voltage including an AC voltage at a preset level, and supplies the DC voltage to a DC power distribution line of the DC power distribution network, and the remaining power conversion devices that are slave power conversion devices detect the DC voltage at the DC power distribution line in real time, and when the AC voltage is not sensed from the detected DC voltage, one of the slave power conversion devices is converted into a master power conversion device.

A power conversion device achieves size reduction and reliability by reducing the number of components of the system. The power conversion device has a semiconductor module of a half-bridge configuration in which two semiconductor elements are arranged in series. The semiconductor module has a cuboidal shape and has, along a longitudinal direction thereof, a positive pole terminal, a negative pole terminal, and terminals for inputting or outputting alternating current or for forming a single phase of the power conversion device. In the vertical direction corresponding to a widthwise direction of the cuboid, a plurality of the semiconductor modules are arranged vertically, forming a plurality of phases of the power conversion device. The semiconductor modules of the plurality of phases are installed in contact with a cooling unit, and one or more capacitors are disposed so as to face the cooling unit across the semiconductor modules of the plurality of phases.

A tag circuit which allows a load connectable thereto to have a wider power consumption range and which is usable in a wider input power range is provided. The tag circuit includes: a control part which is configured to respond to a command extracted from a radio wave received by an antenna by controlling a load; and a rectifying part which is configured to generate DC power to be supplied to the control part and DC power to be supplied to the load by converting a radio wave received by the antenna into DC power, the rectifying part being capable of changing power conversion characteristics of converting the radio wave received by the antenna into DC power to be supplied to the load.

A tag circuit which allows a load connectable thereto to have a wider power consumption range and which is usable in a wider input power range is provided. The tag circuit includes: a control part which is configured to respond to a command extracted from a radio wave received by an antenna by controlling a load; and a rectifying part which is configured to generate DC power to be supplied to the control part and DC power to be supplied to the load by converting a radio wave received by the antenna into DC power, the rectifying part being capable of changing power conversion characteristics of converting the radio wave received by the antenna into DC power to be supplied to the load.

A wireless power reception apparatus including a bridgeless rectifier in a wireless power transfer (WPT) system for an electric vehicle (EV) may include: a bridgeless rectifier configured to rectify power transferred from a reception coil and to supply a direct current to a battery mounted in the EV; and a controller configured to control operation of the bridgeless rectifier. The bridgeless rectifier may include at least one switch and at least one diode connected to the at least one switch.

A wireless power reception apparatus including a bridgeless rectifier in a wireless power transfer (WPT) system for an electric vehicle (EV) may include: a bridgeless rectifier configured to rectify power transferred from a reception coil and to supply a direct current to a battery mounted in the EV; and a controller configured to control operation of the bridgeless rectifier. The bridgeless rectifier may include at least one switch and at least one diode connected to the at least one switch.

The switching power supply device is provided with: a plurality of power supply circuits corresponding to phases of a multi-phase AC power supply; a switching circuit that is capable of switching a phase connected to a power supply circuit not corresponding to one discretionary phase of the multi-phase AC power supply between the one discretionary phase and a phase to which the power supply circuit corresponds; an inrush current prevention circuit for preventing inrush current that is provided on a negative-electrode-side power supply line of the multi-phase AC power supply and at a position further toward the multi-phase AC power supply than is a connection point to which each of the plurality of power supply circuits are connected; and a filter circuit that is provided between the multi-phase AC power supply and the inrush current prevention circuit and has all lines of the plurality of phases magnetically coupled thereto.

A multi-level inverter topology is disclosed. A power converter circuit converts a DC source at its input to provide an alternating current (AC) at its output. The power converter circuit may have a controller operably attached to multiple series connections of switches. The controller may control one or more of the multiple series connections of switches to convert a DC input to provide multi-level AC voltages with DC offset across two terminals of the power converter circuit. The multi-level AC voltages with DC offset may then be converted by use of a plurality of series connections of switches to provide a single-phase AC voltage at a first output terminal with respect to at least one of a neutral potential, an earth potential, or a terminal of the power converter circuit.