Abstract: Disclosed herein is a dual-active bridge converter and methods of operating the same. The dual-active bridge converter can include a transformer, a DC-AC converter, an AC-DC converter, and/or a control device. The DC-AC converter can be coupled to a first DC bus and a primary side of the transformer. The AC-DC converter can be coupled to a secondary side of the transformer and a second DC bus. The control device can send a first PWM signal to the DC-AC converter and a second PWM signal to the AC-DC converter. The first and second PWM signals can initiate the output voltage at zero, add jump edges at odd-numbered current harmonics, or make a phase of the input voltage trail a phase of the output voltage of the DC-AC converter. The control device can adjust the PWM signals for transformer current regulation or pulse overlap control.

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 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 disclosure provides a distributed phase-shifting transforming apparatus, including N transformer rectifier units, where each transformer rectifier unit includes two three-phase three-winding transformers and four rectifier circuits, each three-phase three-winding transformer includes first windings on the primary side and second windings and third windings on the secondary side, AC power output by the second windings and the third windings on the secondary side is output after being rectified by the rectifier circuits. Each transformer rectifier unit is configured such that: one set of the two first windings on the primary side and the two second windings on the secondary side is phase-shifted by 150 from each other, and the other set has the same phase angle; and the second windings and the third windings of each three-phase three-winding transformer are phase-shifted by 300 from each other.

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 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.