A soft-switching solid-state power transformer, including: a high-frequency (HF) transformer comprising first and second winding connections; a first auxiliary resonant circuit coupled to the first winding connection, the first auxiliary resonant circuit comprising: a resonant capacitor coupled across the first winding connection, a resonant inductor coupled across the first winding connection in parallel with the resonant capacitor, and a damping feature coupled across the first winding connection in series with the resonant capacitor and the resonant inductor; a first current-source inverter (CSI) bridge coupled to the first auxiliary resonant circuit, the first CSI bridge comprising reverse blocking switches configured to conduct current in one direction and block voltage in both directions; a second auxiliary resonant circuit coupled to the second winding connection; and a second CSI bridge coupled to the second auxiliary resonant circuit, the second CSI bridge comprising reverse blocking switches.

A converter circuitry between a first network, which may be either a poly-phase medium-voltage alternating current (AC) network, at least one polyphase low-voltage AC network or at least one direct-current (DC) network, and a second network, which may be either a polyphase medium-voltage AC network or a medium-voltage DC network, wherein the converter circuitry comprises at least one power bus and low-voltage power cells both at the first and at the second network side such that each power cell is connected to a power bus via a transformer. Each power bus is connected to a low-voltage power unit, which is able to supply pre-charging power via the power bus to all power cell intermediate DC-link filtering capacitors before the converter is started. The low-voltage power unit is also able to take care of a resistor braking in case the first network cannot take the power supplied by the load connected to the second network.

A multilevel stage of a bidirectional AC power converter, comprising: a set of switches in series, a set of capacitors in series, the set of capacitors being in parallel with the set of switches; a number of sets of diodes in series; a center tap along the set of switches in series; and a pair of taps, respectively after the first and before the last switch of the set of switches in series; wherein each node between respective capacitors is connected to a node between respective diodes. A converter first stage for a 3-level converter has 6 switches, two capacitors, and two diodes, with the junction between diodes connected to the junction between capacitors, and the diode legs between switches 2-3 and 4-5. The center tap is between switches 3-4, and the pair of taps between switches 1-2 and 5-6.

A modular power conversion system is provided which includes a plurality of building blocks comprised of transformers and power conversion bridges, and a high frequency AC link that transfers power and provides galvanic isolation between the building blocks. The high frequency link includes an insulating tube separating an AC link conductor and the building blocks. The insulating tube is further provided with conductive or semiconductive layers on its inner and outer surfaces for referencing them to the electric potentials of the adjacent conductors and windings, thereby placing the high electric fields substantially directly across the tube and reducing electric fields and partial discharge or corona in the adjoining space or media. The building blocks may be arranged in multiple stacks for DC or AC interface, preferably with neutral or lower voltage connections at the outer edges of the stacks and higher voltage terminals at the centers of the stack.

A control device (110) includes a first multiplexing unit (202) configured to segregate a first PWM signal having a first switching frequency into a second PWM signal having a second switching frequency and a third PWM signal having a third switching frequency. Also, the control device (110) includes an integrator unit (204) configured to generate a first integrated signal and a second integrated signal based on the second PWM signal and the third PWM signal, and a modulator unit (206) configured to receive the first integrated signal and the second integrated signal and generate a modulation signal based on the first integrated signal and the second integrated signal. Furthermore, the control device (110) includes a generator unit (208) configured to receive the modulation signal and generate a fourth PWM signal having a fourth switching frequency different from the first switching frequency based on the modulation signal.

A solid-state transformer (SST) comprises a transformer core, a primary winding, a secondary winding, a primary-side switch bank, and a secondary-side switch bank. Each of the switch banks includes six 4-quadrant switches. The twelve 4-quadrant switches are toggled on and off over six clock cycles in a repetitive sequence with a period that is a function of a desired operating frequency of the transformer. The sequence is configured such that at any given time, 2 of 3 input and output phases are connected to the primary and secondary windings. The SST further includes L-C filter circuits that are configured to filter high-frequency components of current and voltage waveforms such that these components are not back-fed to the electrical mains or delivered to a load. The SST includes a primary-side filter circuit and a secondary-side filter circuit that can each include respective L-C filters for three input or output phases.

A power supply system includes an onboard rectifier that may be disposed onboard an electric vehicle. The onboard rectifier is configured to receive an alternating current conducted from a power generating station via a transmission line at a frequency that is at least a utility power line frequency. The onboard rectifier may change the alternating current into a direct current and to output the direct current to an electric propulsion system of the electric vehicle to power the propulsion system and propel the electric vehicle.

An arrangement contains an asynchronous machine, which, in generator operation, is configured to feed electric power into an AC network. Accordingly, the asynchronous machine can be dual-fed by a modular multi-stage converter in a matrix configuration. The asynchronous machine has a rotor and the modular multi-stage converter is connected to the rotor of the asynchronous machine.

Aspects of the invention overcome a monolithic approach to conventional low-frequency LPTs by using a high-frequency solid-state alternating current ac/ac modular power-conversion approach. Embodiments of the invention enable the ability to incorporate new technologies without in all cases redoing a LPT design from scratch. Furthermore, given that LPTs are for the long term, aspects of the invention ensure that they are durable, efficient, and fault tolerant with overloading capability.

A direct AC to AC converter includes a modulation stage, a transformer and a de-modulation stage. The modulation stage is configured to convert an AC input voltage with a first frequency into a bipolar PWM voltage with a second frequency, wherein the second frequency is higher than the first frequency. The transformer has a primary winding and secondary winding, wherein the primary winding is coupled to the modulation stage to receive the bipolar PWM voltage. The de-modulation stage is coupled to the secondary winding of the transformer and configured to convert the voltage across the secondary winding of the transformer into an AC output voltage with the first frequency.