In a method for operating a drive system, and drive system, having a rectifier and at least one inverter including an electric motor, the electric motor is connected at the AC-voltage-side connection of the inverter, the DC-voltage-side connection of the inverter is connected via inductance(s) in addition to the line inductance, to the DC-voltage-side connection of the rectifier, a capacitance is connected at the DC-voltage-side connection of the inverter and/or at the DC-voltage-side connection of the rectifier, a series circuit, including a resistor and a controllable semiconductor switch is connected at the DC-voltage-side connection of the inverter and/or at the DC-voltage-side connection of the rectifier, the braking chopper being operated using a single frequency during the particular time span in which the braking chopper is in operation, the frequency, e.g., being set apart from the resonant frequency of the resonant circuit including the inductance or the capacitances.

An uninterruptible power supply device includes a bidirectional chopper that converts a first DC voltage supplied from a battery into a second DC voltage and supplies the second DC voltage to an inverter when a power failure of a commercial AC power supply occurs. The bidirectional chopper includes a capacitor that stabilizes the second DC voltage. The uninterruptible power supply device further includes: a current detector that detects an output current of the battery; and a control circuit that, based on a detection result by the current detector, calculates an estimated temperature increase value of the capacitor every time a predetermined time period elapses, and stops an operation of the bidirectional chopper when the calculated estimated temperature increase value is higher than an upper limit value.

An uninterruptible power supply apparatus includes: an electromagnetic contactor including a first terminal that receives a first AC voltage supplied from an AC power supply and a second terminal connected to an AC node; a capacitor that is connected to a DC line and stores DC power; a converter that transmits and receives electric power between the AC node and the DC line; and a controller. In an activation mode, the controller turns on the electromagnetic contactor after controlling the converter such that a frequency and a phase of a second AC voltage supplied from the converter to the AC node match a frequency and a phase of the first AC voltage. In a normal operation mode after the activation mode, the controller controls the converter such that a DC voltage of the DC node attains to a reference voltage.

Aspects of the disclosure provide an uninterruptible power supply comprising an input configured to receive input power from an input-power source, the input having a mains neutral connection coupled to a reference node, an energy-storage-device interface configured to be coupled to an energy-storage device to provide back-up power, the energy-storage-device interface having an energy-storage-device neutral connection coupled to the reference node, an output configured to provide output power derived from at least one of the input power and the back-up power, a power-factor-correction circuit (PFC) comprising a PFC input, a capacitor coupled to the PFC and being galvanically coupled to the energy-storage-device interface, a bidirectional converter coupled to the input and coupled to the energy-storage-device interface, and a switch coupled to the energy-storage-device interface and to the PFC input.

Various embodiments of the present disclosure relate to power conversion using a planar transformer assembly that provides medium-voltage isolation at high frequencies. A planar transformer comprises primary and secondary planar windings configured to generate an isolated output. Each primary and secondary winding is interleaved on layers of a printed circuit board using one or more vias within the layers of the printed circuit board. The planar transformer also comprises a magnetic core and a field-shaping apparatus coupled with the printed circuit board. The field-shaping apparatus is configured to shape an electric field generated by the windings. The primary windings can be coupled to a DC source via switching devices while the secondary windings can be coupled via switching devices to one or more DC ports followed by AC inverters configured to generate three single-phase AC outputs for medium voltage applications.

The present disclosure discloses an offshore wind farm low-frequency alternating-current uncontrolled rectification electric power transmission system, comprising an onshore converter station and an offshore alternating-current system. The offshore alternating-current system comprises wind turbine generators, alternating-current submarine cables, a confluence bus, and offshore booster stations; the onshore converter station comprises a wind field side alternating-current bus, an alternating-current system side alternating-current bus, an alternating-current filter, an energy dissipation device, a rectifier, and a converter; the rectifier is composed of a three-phase six-pulse uncontrolled rectifier bridge, and the converter may be an MMC or an LCC; the rated frequency of the offshore alternating-current system is selected to be close to 10 Hz.

A power conversion device including a switching element includes: a temperature change estimation unit estimating temperature change in a semiconductor chip containing the switching element; a number calculator calculating the number of power cycles to fracture of the semiconductor chip due to power cycles; and a degradation degree calculator computing a degree of degradation of the semiconductor chip caused by the power cycles. The temperature change estimation unit calculates a maximum value and a minimum value of temperature of the semiconductor chip in one power cycle based on a first threshold of temperature fall allowed when it is determined that the temperature of the semiconductor chip is rising, and a second threshold of temperature rise allowed when it is determined that the temperature of the semiconductor chip is falling. The number calculator calculates the number of power cycles to fracture based on the maximum value and the minimum value.

The present disclosure relates to a power converter for use in a host vehicle. The power converter comprises a DC link, a DC link capacitor, and a pre-charge circuit configured to charge the DC link capacitor. The pre-charge circuit comprises a boost converter comprising a switch and inductor coupling terminals configured to couple to an inductive component external to the power converter.

A system for use in generating a power signal includes a first stage circuit having: a first input line coupled to a first stage first parallel line having a first stage first switch positioned thereon, a second input line coupled to a first stage second parallel line having a first stage second switch positioned thereon, and a first stage third parallel line oriented in parallel with the first stage first parallel line and the first stage second parallel line between a positive rail and a negative rail, the first stage third parallel line having a first capacitor positioned thereon. The system further includes a second stage circuit having a resonant inverter coupled between the positive rail and the negative rail and configured to output the power signal.

A power apparatus applied in an SST structure includes a first AC-to-DC conversion unit, a first DC bus, an isolated transformer, a DC-to-AC conversion unit, a second AC-to-DC conversion unit, and a second DC bus. The first AC-to-DC conversion unit has a first bridge arm and a second bridge arm. The first DC bus provides a first DC voltage. The isolated transformer has a primary side and a secondary side. The DC-to-AC conversion unit has a third bridge arm and a fourth bridge arm. The second AC-to-DC conversion unit has a fifth bridge arm and a sixth bridge arm. The second DC bus provides a second DC voltage.