A three-level power converter includes a direct current power supply unit including a filter capacitor connected between a high potential line and an intermediate potential line and a filter capacitor connected between the intermediate potential line and a low potential line, and a power conversion circuit that converts a three-level direct current voltage output from the high potential line, the intermediate potential line, and the low potential line into a three-phase alternating current voltage. A controller generates an imbalance signal representing an imbalance between a first capacitor voltage and a second capacitor voltage on the basis of values detected by voltage sensors, and generates a modulation signal for causing the power conversion circuit to perform a two-phase modulation operation on the basis of a superimposed signal obtained by superimposing the imbalance signal on a reference signal of the three-phase alternating current voltage.

Embodiments of the present disclosure relate to parallel 3-level inverter without midpoint connection. The parallel 3-level inverter includes a plurality of parallel converters coupled in parallel between a common DC bus and a common AC output, wherein each of the plurality of parallel converters comprises a midpoint and the midpoints of the plurality of parallel converters are disconnected from each other.

Power converters can include a plurality of switching devices and a combination of one or more inductors and one or more flying capacitors. Both boost and buck converters may employ such topologies, and can achieve high efficiency and small size in at least some applications, including those with high conversion ratios. A control circuit can generate a first pair of complementary gate drive signals to drive a first complementary switch pairs and a second pair of complementary gate drive signals to drive a second complementary switch pair. The control circuit can vary a phase shift between the first pair of complementary gate drive signals and the second pair of complementary gate drive signals to regulate the flying capacitor voltage.

To improve voltage balancing at the DC link capacitor voltages of a multi-level inverter with a split DC link a modulation signal with a modulation signal amplitude as even harmonic signal of the output voltage or output current of the inverter is calculated from an actual electric power difference of the actual electric powers at the DC link capacitors and is superimposed onto the setpoint value for setting an output voltage or output current of the inverter.

A system has a DC bus circuit with first and second terminals, an intermediate node, first and second capacitors, first and second depletion mode FETs, and first and second switching control circuits, where the first depletion mode FET has a drain coupled to the first bus terminal, a source, and a gate coupled to the intermediate node, the second depletion mode FET has a drain coupled to the intermediate node, a source, and a gate coupled to the second bus terminal, the first switching control circuit turns the first depletion mode FET off responsive to a first capacitor voltage of the first bus capacitor being less than or equal to a second capacitor voltage of the second bus capacitor, and the second switching control circuit turns the second depletion mode FET off responsive to the first capacitor voltage being greater than or equal to the second capacitor voltage.

Various examples of power converters including Integrated Capacitor Blocked Transistor (ICBT) cells and methods of control of power converters having ICBT cells are described. In one example, a power converter includes an upper arm including a plurality of upper ICBT cells connected in series to form a series connection path and a lower arm including a plurality of lower ICBT cells connected in series in the series connection path. A controller can be configured to provide a control signal pair to each of the upper ICBT cells and a complementary control signal pair to each of the lower ICBT cells to control the converter output. A capacitor voltage controller can be configured to balance a voltage potential among ICBT capacitors in at least one of the upper arm and the lower arm.

A power device may have at least two capacitors in series with each other and in parallel with a DC power source. The power device may have at least a first converter that has at least a controller configured to balance a voltage of the at least two capacitors. The power device may have at least a second converter connected to the at least two capacitors. The second converter may have at least three input conductors, each connected to a terminal of the at least two capacitors. The second converter may have at least two output conductors. The second converter may have at least a switching circuit between the at least three input conductors and at least two output conductors. The second converter may have at least a controller configured to operate the switching circuit. The second converter may passively preserve the voltage balance between the at least two capacitors.

The present disclosure provides a power supply system and a power conversion device. The power conversion device is used for converting electric energy outputted by a power supply module, and the power conversion device includes an electric energy conversion module and a switching module. The electric energy conversion module is configured to convert the electric energy output from the power supply module into a single-phase two-wire output or a single-phase three-wire output, and includes a half-bridge circuit, a bridge conversion circuit and a neutral line. The switching module is coupled with the electric energy conversion module, and is configured to control the electric energy conversion module to provide the single-phase two-wire output or single-phase three-wire output.

A control apparatus configured to control a chain link voltage source converter, the control apparatus comprising; two converter controllers, each converter controller configured to receive a measure of the output voltage and/or current from the converter and determine a control signal therefrom for controlling the voltage source converter, each converter controller including at least one integrator element configured to perform an integration operation and output an integrator term in said determination of the control signal, a selector configured to select which one of the converter controllers provides its control signal to the converter; wherein each integrator element is configured to have two modes, a first mode in which the integrator element determines the integrator term and a second mode in which the integrator term is provided by a corresponding integrator element in the other converter controller.

The application provides a cascade system distributed control method and device. The method including: taking an output of a closed-loop control for regulating an AC current of the power module as a reference value of a bridge arm voltage; according to the reference value of the bridge arm voltage to obtain an amplitude of the bridge arm voltage, taking the amplitude of the bridge arm voltage as a feedback signal, and after closed-loop control and regulation together with the AC current of the power module, adjusting the reference value of the bridge arm voltage; and controlling the bridge arm voltage according to the reference value of the bridge arm voltage, wherein in at least one working mode of the cascade system, a change of parameters reflecting an active current has a monotonic relation with a change of the amplitude of the bridge arm voltage.