A DC/DC power converter for converting voltage at an input to a voltage at an output of the DC/DC power converter is provided, wherein the output voltage is a multiple of the input voltage. The DC/DC power converter comprises two switching circuits electrically connected in series, two capacitor units electrically connected in series, and a resonant circuit comprising a resonant capacitor and a resonant inductor. A first switching circuit of the two switching circuits is electrically connected to one side of the first capacitor unit opposite to the other side of the first capacitor unit connected to the second capacitor unit of the two capacitor units. The switches of the first switching circuit are controllable semiconductor switches. The first switching circuit comprises one or more diode units electrically connecting the first capacitor unit to the two switching units of the first switching circuit.

A switching power supply unit includes: a transformer; an inverter circuit including first to fourth switching devices, first to third capacitors, first and second rectifying devices, a resonant inductor, and a resonant capacitor; and a driver. The first to fourth switching devices are coupled in series. The first and second capacitors are coupled in series. The first rectifying device is disposed between a first connection point between the first and second capacitors and a second connection point between the first and second switching devices. The second rectifying device is disposed between the first connection point and a third connection point between the third and fourth switching devices. The third capacitor is disposed between the second and third connection points. The resonant capacitor, the resonant inductor, and a primary winding are coupled in series between a fourth connection point between the second and third switching devices and the first connection point.

A system comprises a first 3-phase rectifier having a positive DC lead and a negative DC lead and a second 3-phase rectifier having a positive DC lead and a negative DC lead. The system also includes a 4-phase, 3-level inverter connected to the first and second 3-phase rectifiers. A method comprises receiving variable frequency, 3-phase power from a first generator, receiving variable frequency, 3-phase power from a second generator, rectifying the variable frequency, 3-phase power from each of the first and second generators into DC power. And inverting the DC power into 4-phase, constant frequency power for powering a load.

A power system includes a pulse width modulation device. The pulse width modulation device outputs first, second, third and fourth driving signals. The pulse width modulation device receives a control signal. The control signal is divided into a positive periodic signal and a negative periodic signal. A portion of the positive periodic signal higher than or equal to a maximum threshold voltage is clamped as the maximum threshold voltage to generate a first comparison waveform. The positive periodic signal is clamped as the reference voltage level to generate a second comparison waveform. According to the first comparison waveform, a first ramp signal is generated. According to the second comparison waveform, a first pulse width modulation signal is generated. The first, second, third and fourth driving signals are adjusted according to the first ramp signal and the first pulse width modulation signal.

An apparatus may include a first switch leg connected between a first input terminal and a first output terminal, the first switch leg comprising serially connected switches. The apparatus may also include a second switch leg connected between a second input terminal and the first output terminal, the second switch leg comprising serially connected switches. The apparatus may further include a third switch leg connected between an input voltage midpoint and the first output terminal. A control circuit may control the first switch leg, the second switch leg and the third switch leg.

An apparatus may include a first switch leg connected between a first input terminal and a first output terminal, the first switch leg comprising serially connected switches. The apparatus may also include a second switch leg connected between a second input terminal and the first output terminal, the second switch leg comprising serially connected switches. The apparatus may further include a third switch leg connected between an input voltage midpoint and the first output terminal. A control circuit may control the first switch leg, the second switch leg and the third switch leg.

In accordance with at least one aspect of this disclosure, a converter system for a three level boost converter. In embodiments, the system includes a voltage input configured to connect to a voltage source, a switching module operatively connected to the voltage input to output quasi-square wave, a voltage output configured to supply voltage to a load, and a logic module. In embodiments, the logic module can be configured to control the switching module to modulate voltage from the voltage source to the voltage output to maintain a zero-voltage switching condition for at least a specified interval, using a method.

Embodiments of this application disclose an inverter apparatus and an inverter apparatus control method. The inverter apparatus includes an inverter circuit and a control unit, and the control unit detects a driving mode of the inverter circuit based on a running state of the inverter circuit. When the inverter circuit outputs reactive power and an output current amplitude is greater than a current threshold, the control unit controls the inverter circuit in a full-bridge two-level bipolar control mode; and in other cases, the control unit controls the inverter circuit in a three-level control mode. This reduces a risk of breaking down horizontal bridge semiconductor switching devices by a voltage spike in an active turn-off process.

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.

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.