Abstract: The present invention provides an auxiliary pre-charging device for a power converter. The power converter includes at least one power unit with an input end being connected to a medium and high voltage AC power source, and an output end being connected to a low voltage DC bus, wherein the auxiliary pre-charging device includes a switch, a transformer, a pre-charging resistor, and a rectifier sequentially connected in series, one end of the switch is connected to the medium and high voltage AC power source, and an output end of the rectifier is connected to the low voltage DC bus. The present invention also provides a pre-charging method for a power converter, which uses the aforementioned auxiliary pre-charging device to start pre-charging at the low-voltage output end of the power converter.

Abstract: A ripple control method for a modular cascaded power conversion device is provided. The method obtains, according to a grid voltage vector of three-phase AC power, a second-order fluctuating voltage superposition vector representing the total amount of second-order fluctuating voltages on respective floating DC sides of the three phases; determines a single-phase power control amount of each phase to be transferred from the floating DC sides to a low-voltage DC side; determines a single-module power control amount of each power module to be transferred to a low-voltage DC side thereof; and generates a single-module control signal for controlling the power module, so as to transfer a second-order fluctuating voltage on a floating DC side of the power module to the low-voltage DC side thereof. A modular cascaded power conversion device is also provided.

Abstract: The present invention provides an auxiliary pre-charging device for a power converter. The power converter includes at least one power unit with an input end being connected to a medium and high voltage AC power source, and an output end being connected to a low voltage DC bus, wherein the auxiliary pre-charging device includes a switch, a transformer, a pre-charging resistor, and a rectifier sequentially connected in series, one end of the switch is connected to the medium and high voltage AC power source, and an output end of the rectifier is connected to the low voltage DC bus. The present invention also provides a pre-charging method for a power converter, which uses the aforementioned auxiliary pre-charging device to start pre-charging at the low-voltage output end of the power converter.

Abstract: A power converter and a staircase modulation method therefor are provided. The power converter includes n cascaded bridges, where n?2, the n cascaded bridges are each configured to output same multilevel pulses, the output n multilevel pulses are sequentially phase-shifted by a same angle, and the n multilevel pulses are superposed on each other to form a desired output pulse waveform of the power converter. Each of the n cascaded bridges is configured such that an output pulse of each cascaded bridge includes 2k+1 sub-pulses in each half cycle, where k?1; and the 2k+1 sub-pulses are symmetrically distributed by using a (k+1)th sub-pulse as a center, pulse widths from a 1st sub-pulse to the (k+1)th sub-pulse sequentially increase, and pulse widths from the (k+1) sub-pulse to a (2k+1)th sub-pulse sequentially decrease.

Abstract: A power converter is provided. The power converter is configured to be connected between a multi-phase alternating current power supply derived from an alternating current power network and a load. For each phase of the alternating current power supply, the power converter includes n power modules, and each power module has: one alternating current input end; m power units connected in parallel to the alternating current input end; and m direct current output ends. Alternating current input ends of the n power modules are sequentially connected in series and are connected between a corresponding phase and a common node. Direct current output ends of selected power units are connected in parallel to form one direct current output of the power converter. The disclosure can simultaneously meet loads with different requirements without adding additional DC/DC converters, thereby reducing consumption generated in a power conversion process.

Abstract: Provided are a transformer winding and a method for constructing a transformer winding. The transformer winding includes: a lead wire of a winding conductor of the transformer winding; an insulating layer wrapping the lead wire; a ground shielding layer covering a side, close to the winding conductor, of the insulating layer; and a stress grading material layer, which is made of a semi-conductive material, covers a side, away from the winding conductor, of the insulating layer, and is electrically connected to the ground shielding layer, where the stress grading material layer is impedance-matched with the insulating layer.

Abstract: Provided are a transformer winding and a method for constructing a transformer winding. The transformer winding includes: a winding conductor having a ring structure; a first insulating layer wrapped on a surface of the winding conductor formed by winding; a conductor tape attached in an unclosed surrounding manner to a surface of the first insulating layer along a circumferential direction of the first insulating layer, where the conductor tape is attached to a position having a minimum value of a leakage flux on the surface of the first insulating layer; a first shielding layer attached to the surface of the first insulating layer with the conductor tape attached thereto; a second insulating layer cast outside the first shielding layer; and a second shielding layer wrapped on an outer surface of the second insulating layer.

Abstract: Provided is a direct current voltage sampling circuit used for a medium-voltage power module. The medium-voltage power module includes two cascaded H-bridge circuits. The sampling circuit includes two sampling sub-circuits, with each connected to one H-bridge circuit. The sampling sub-circuit includes: a voltage dividing circuit connected in parallel to an output end of the H-bridge circuit, an isolation module connected to the voltage dividing circuit, a direct current isolated power supply which supplies power to the isolation module independently of the H-bridge circuit, and an amplifier conditioning module which converts an isolated voltage signal into a sampled voltage output. Parasitic capacitances of the isolation module and the direct current isolated power supply are both less than 2 pF, and the sampled voltage outputs of the two sampling sub-circuits are provided to a same local controller.

Abstract: A harmonic suppression method and apparatus for a three-phase three-wire cascaded power conversion apparatus is disclosed.

Abstract: The present invention provides a multi-active bridge converter.

Abstract: The present invention provides a Pulse Width Modulation (PWM) method for a Cascaded H-bridge (CHB) converter. Each phase of the converter is provided with n Cascaded H-bridge rectifier circuits, or may also be provided with n Cascaded H-bridge rectifier circuits+1 redundant H-bridge rectifier circuit. The method includes following steps of: S1, generating groups of sinusoidal signals as reference waveforms, and generating n carrier signals having sequentially decreasing levels and equal amplitudes to correspond to the H-bridge rectifier circuit at the first to the nth levels, where the levels of the n carrier signals are cascaded to fill the voltage amplitude of a unipolar half cycle of the reference waveform; and S2, determining PWM signals for controlling power transistors of the corresponding H-bridge rectifier circuits based on each reference waveform and each carrier signal.

Abstract: The present invention provides a multi-active bridge converter.

Abstract: The present invention provides an auxiliary pre-charging device for a power converter. The power converter includes at least one power unit with an input end being connected to a medium and high voltage AC power source, and an output end being connected to a low voltage DC bus, wherein the auxiliary pre-charging device includes a switch, a transformer, a pre-charging resistor, and a rectifier sequentially connected in series, one end of the switch is connected to the medium and high voltage AC power source, and an output end of the rectifier is connected to the low voltage DC bus. The present invention also provides a pre-charging method for a power converter, which uses the aforementioned auxiliary pre-charging device to start pre-charging at the low-voltage output end of the power converter.

Abstract: The present disclosure relates to autogenic software testing. In some embodiments, a method of the present disclosure includes scanning source code to identify one or more methods to be tested. The method further includes generating one or more test cases which perform requests using the one or more methods. The method further includes generating one or more logs comprising results of the requests. The method further includes scanning the one or more logs to identify a pattern associated with a request. The method further includes determining that the pattern is not stored in a test data store. The method further includes generating a first test and a first expected response based on the pattern. The method further includes storing the first test and the first expected response in the test data store. The first test may be executed and evaluated based on the first expected response.