An energy conversion system includes a low-impedance generator having at least one armature winding set. The armature winding set includes a plurality of single-phase coils. The system also includes a current source converter assembly electrically coupled to an armature of the generator. The current source converter assembly includes at least one current source converter that includes a current source rectifier coupled to a current source inverter via a DC link and at least one capacitor across the plurality of single-phase armature coils. The capacitor(s) of the current source converter(s) is configured to absorb high frequency components of current pulses generated by the current source converter so as to minimize current ripple in a current applied to the plurality of single-phase coils.

The inverter generator controller equipped with the engine generator unit driven by the engine and operates to prompt user to specify the load to be used (S10); to respond to load specified by user in response to prompt by selecting and connect to the engine generator unit at least one among multiple batteries differing in discharge capacity per unit time (S12 to S22); and to control charge/discharge of the connected battery/batteries and operation of the engine generator unit based on load output demand from the specified load (S24).

The invention provides an inverter system and a method of using said inverter system. A rectifier stage of the inverter system is used to charge a DC link stage to a first voltage level and a control module determines whether voltages over series connected capacitors of the DC link stage are balanced. If those voltages are balanced, the rectifier stage charges the DC link stage to a second voltage level higher than the first voltage level.

For a power supply with a reduced number of semiconductor devices, a transformer receives a three-phase primary voltage and steps the three-phase primary voltage up or down to a secondary voltage with a plurality of secondary winding sets to a plurality of first phase voltages, a plurality of second phase voltages, and a plurality of third phase voltages. A plurality of power cell sets each include a plurality of power cells cascaded connected. Each power cell comprises a rectifier and an inverter. The rectifier includes two first active switches that are serially connected and receive a phase voltage at a first switch midpoint, two second active switches that are serially connected and receive another phase voltage at a second switch midpoint, and two capacitors that are serially connected and receive another phase voltage at a capacitor midpoint between the capacitors.

For a power supply with a reduced number of semiconductor devices, a transformer receives a three-phase primary voltage and steps the three-phase primary voltage up or down to a secondary voltage with a plurality of secondary winding sets to a plurality of first phase voltages, a plurality of second phase voltages, and a plurality of third phase voltages. A plurality of power cell sets each include a plurality of power cells cascaded connected. Each power cell comprises a rectifier and an inverter. The rectifier includes two first active switches that are serially connected and receive a phase voltage at a first switch midpoint, two second active switches that are serially connected and receive another phase voltage at a second switch midpoint, and two capacitors that are serially connected and receive another phase voltage at a capacitor midpoint between the capacitors.

An inverter of a power supply apparatus includes a smoothing circuit. The smoothing circuit includes a circuit body having a positive-side output terminal and a negative-side output terminal, and a plurality of capacitors mounted on the circuit body and connected in parallel between the positive-side output terminal and the negative-side output terminal. A difference between the maximum value and the minimum value among positive-negative electrical path lengths ln.sub.PNi=ln.sub.Pi+ln.sub.Ni (i=1, 2, and 3) for the respective capacitors is equal to or smaller than 30% of the minimum value.

A method and system for controlling a three-phase drive connected to a three phase power source. The method includes connecting a converter to transfer power from the power source to a first direct current (DC) bus, where the converter and the first DC bus each have a neutral common point (NCP). Connecting a second DC bus to the first DC bus and configuring an inverter connected to the second DC bus to draw power from the second DC bus to provide a plurality of motor signals, the inverter having an inverter NCP. The method also includes connecting a neutral point selection device to the first DC bus NCP and selectively connecting to the converter NCP or the inverter NCP, the bus selection device configured to disconnect the converter NCP or the inverter NCP from the first DC bus NCP under selected conditions.

An arrangement provides an AC current to a load for direct electrical heating. The arrangement includes a AC-DC-AC converter cell. The converter cell has at least two converter input terminals connected to at least two transformer output terminals. The converter cell has a first converter output terminal and a second converter output terminal, wherein the first converter cell output terminal is adapted to be connected to the load.

A regenerative drive (30) and method for providing power from such to at least one auxiliary power supply (41, 43) is disclosed. The drive may include a converter (32) and an inverter (34) connected by a DC bus (33), and a controller (54) configured to apply at least one of unipolar modulation and bipolar modulation to the converter (32) and the inverter (34), and to provide about half of the output voltage across the upper portion (130) of the DC bus (33) and about half of the output voltage across the lower portion (136) of the DC bus (33), when the upper and lower portions (130, 136) of the DC bus (33) are unevenly loaded. A first auxiliary power supply (41) may be connected to one of the upper and lower portions (130, 136) of the DC bus (33) and may receive power from the multilevel regenerative drive (30).

It is described an arrangement for providing an AC current to a load for direct electrical heating, the arrangement comprising a AC-DC-AC converter cell (133, 433, 533, 633, 733), the converter cell having at least two converter input terminals (111, 112, 113) connected to at least two transformer output terminals, the converter cell having a first converter output terminal (135, 435, 535) and a second converter output terminal (137, 437, 537), wherein the first converter cell output terminal (135) is adapted to be connected to the load (350, 650, 750, 850).