A method controls a converter assembly which has a line-commutated converter. The line-commutated converter has an alternating voltage terminal which can be connected via a phase conductor to an alternating voltage network. The converter assembly further has a switch module branch which is arranged serially in the phase conductor and which contains a series circuit of switch modules at each of the terminals of which bipolar voltages can be generated which add up to a branch voltage. A connection voltage to a connection point between the switch module branch and the converter is controlled by adjusting an amplitude of a positive sequence component of the branch voltage. The converter assembly is configured to carry out a control method for controlling the converter assembly.

A power conversion device includes a power supply, a converter, a current detection circuit, and a control circuit. The power supply includes positive and negative terminals. The converter includes a primary side and a secondary side. The converter is configured to output a first current to a load. The primary side is electrically connected to the positive terminal and the negative terminal of the power supply in parallel. The secondary side is electrically connected to the positive terminal of the power supply and the load in series. The current detection circuit is coupled between the secondary side and the load, and is configured to detect the first current to output a current detection signal. The control circuit is coupled to the current detection circuit for outputting a control signal to the converter according to the current detection signal and a reference current signal.

A system may be provided that may include a first battery, and an inverter coupled to the battery. The system may also include a first active filter including a first switch element, second switch element, third switch element, and fourth switch element. Each switch element may be coupled to the first battery or the inverter. The first, second, third, and fourth switch elements may be configured to increase or decrease an applied voltage or current of the first battery.

Apparatus for power conversion are provided. One apparatus includes a power converter including an input circuit and an output circuit. The power converter is configured to receive power from a source for providing power at a DC source voltage V.sub.S. The power converter is adapted to convert power from the input circuit to the output circuit at a substantially fixed voltage transformation ratio K.sub.DC=V.sub.OUT/V.sub.IN at an output current, wherein V.sub.IN is an input voltage and V.sub.OUT is an output voltage. The input circuit and at least a portion of the output circuit are connected in series across the source, such that an absolute value of the input voltage V.sub.IN applied to the input circuit is approximately equal to the absolute value of the DC source voltage V.sub.S minus a number N times the absolute value of the output voltage V.sub.OUT, where N is at least 1.

The present invention relates to a DC-DC power converter which comprises a switched converter core operated in accordance with a primary control signal to supply a primary DC output current (Io) of the converter; said primary control signal exhibiting a minimum resolution, e.g. a minimum time step, leading to a corresponding minimum current step of the primary DC output current. The DC-DC power converter additionally comprises a controllable resistive path, or a controllable current source, connected between a pair of terminals selected from a group of: (the positive output terminal, the negative output terminal, the positive input terminal, the negative input terminal) and configured to add or subtract a secondary DC output current (Icon) to the primary DC output current (Io) in accordance with a secondary control signal to adjust the load current.

A voltage drop Vz.sub.s is calculated based on an output current detection value Iac and a virtual synchronous impedance Zs or a corrected virtual synchronous impedance Zs′, and a value obtained by subtracting the voltage drop Vz.sub.s from an internal induced voltage Ef is output as a grid voltage command value Vac*. Zs calculation unit 7 limits an output current phase θ so that the output current phase θ is within an effective range by a phase limiter 12a, and calculates the corrected virtual synchronous impedance Zs′ based on a limited output current phase θ, the internal induced voltage Ef, a grid voltage detection value Vac and a current limit value Ilim. Accordingly, in grid interconnection power conversion device that controls a virtual synchronous generator, it is possible to continue operation while suppressing an overcurrent and possess a synchronizing power generated by action or working of a virtual synchronous impedance.

A power supply system 1 includes: a variable voltage power supply 7 that outputs power of a variable voltage from a pair of secondary-side input/output terminals 72p and 72n; and power lines 21 and 22 that connect the pair of secondary-side input/output terminals 72p and 72n and a load 4. The first power line 21 is provided with a first switch unit 31 and a third power line 23 that connects both ends of the first switch unit 31, and the third power line 23 is provided with a third switch unit 33, a DC power supply 30, and a second switch unit 32 in series. The fourth power line 24 connects the third power line 23 and the second power line 22. The fourth power line 24 is provided with a fourth diode 34a that allows an output current of the DC power supply 30.

A power conversion device includes a first converter configured to convert at least first battery power output by a first battery into first output power of a first voltage waveform based on an output waveform profile that has been input or set and output the first output power and a first generator configured to generate and output second output power based on the first battery power. Third output power of an alternating current (AC) control waveform generated by adding the first output power to the second output power is supplied to a load.

A power supply system 1 includes: a variable voltage power supply 7 that outputs power of a variable voltage E1 from a pair of secondary-side input/output terminals 72p and 72n; a first power line 21 and a second power line 22 that connect the pair of secondary-side input/output terminals 72p and 72n and a load 4; a first switch unit 31 that is provided on the first power line 21; a third power line 23 that connects both ends of the first switch unit 31; and a bypass line 25 that connects the pair of secondary-side input/output terminals 72p and 72n, a first DC power supply 33 is provided on the third power line 23 to output DC power, and a bypass diode 33a is provided on the bypass line 25 to allow an output current of the first DC power supply 38.

According to one aspect of the present disclosure, there is provided an apparatus that includes first, second, and third power converter stages connected to a transformer module. At least one of the first, second, and third power converter stages is a multi-level power converter stage that has multiple configurations to generate different output voltages from an input voltage.