Abstract: A resonant converter includes: an input power supply, a bleeder circuit, a multi-level switching network, a resonant unit, and a transformer. The input power supply is connected to the bleeder circuit, the multi-level switching network is connected to the bleeder circuit, a clamping middle point of the multi-level switching network is connected to a middle point of the bleeder circuit; one end of the resonant unit is connected to the output terminal of the multi-level switching network, and the other end of the resonant unit is connected to one end of a primary side of the transformer; and the multi-level switching network instructs the output terminal of the multi-level switching network to output a square wave voltage with different amplitudes, to serve as an input voltage of the resonant unit, where the input voltage is used to adjust a gain of the resonant converter.

Abstract: This application discloses an inverter, including: a direct-current conversion unit, a busbar unit, and an inversion unit. The direct-current conversion unit includes a first positive input terminal, a first negative input terminal, a second positive input terminal, a second negative input terminal, a first direct current DC-to-DC module, a second DC-to-DC module, a first on/off control device, a second on/off control device, a first switch, and a second switch. The first positive input terminal and the first negative input terminal are configured to connect a first photovoltaic string, the second positive input terminal and the second negative input terminal are configured to connect a second photovoltaic string, and a connection relationship of a circuit in the direct-current conversion unit can be changed based on combinations of turning-on or turning-off of the first switch and the second switch.

Abstract: This application discloses a photovoltaic direct-current breaking apparatus, including a positive connection terminal and a negative connection terminal for connecting a photovoltaic string and a photovoltaic energy converter, a first diode, a first switch, a convector circuit, and an energy absorption circuit, where the first switch, the convector circuit, and the energy absorption circuit are connected in parallel. The convector circuit can effectively avoid arc discharge and ablation generated when the first switch cuts off a direct-current circuit between the photovoltaic string and the photovoltaic energy converter. The first diode can effectively bypass energy stored by an energy storage device in the photovoltaic energy converter, helping reduce required specifications of a semiconductor device in the convector circuit. The energy absorption circuit can also effectively reduce required specifications of the semiconductor device and a varistor.

Abstract: This application relates to the field of power technologies, and provides a photovoltaic system, which can increase a working voltage of a photovoltaic string. The photovoltaic system includes an adapter circuit, a first photovoltaic string, a second photovoltaic string, and a controller. The controller includes an inverter or a combiner box. The first photovoltaic string and the second photovoltaic string are configured to provide electric energy for the controller. The adapter circuit is configured to be connected to the first photovoltaic string in series, and further configured to connect the second photovoltaic string to the first photovoltaic string in series when a voltage of the first photovoltaic string is lower than a preset threshold.

Abstract: An inverter in a power generation system converts a direct current that is input from a direct-current-side device into an alternating current for power supply. The inverter includes a control apparatus and a communications apparatus. The control apparatus controls the inverter to convert the direct current that is input from the direct-current-side device into an alternating current for power supply. The communications apparatus is coupled to the control apparatus, and sends a networking information request signal used to request networking information to the direct-current-side device in the power generation system through a direct-current power line, where a frequency of the networking information request signal is within a first frequency band. The communications apparatus also receives the networking information from the direct-current-side device; and sends a control signal to the direct-current-side device, where a frequency of the control signal is within a second frequency band.

Abstract: A resonant converter circuit comprises a multi-level inverter circuit placed before a resonant unit, and the multi-level inverter circuit can reduce a voltage to be input to the resonant unit. The reduced input voltage of the resonant unit results in a drop in an output voltage of the entire resonant converter circuit. In this process, the final output voltage is adjusted by adjusting the input voltage of the resonant unit, with no need to substantially adjust a switching frequency of the resonant converter circuit.

Abstract: Voltage in the photovoltaic power generation system can be increased under a same power conversion condition, to reduce a current in the photovoltaic power generation system, thereby reducing energy consumption and reducing costs of the photovoltaic power generation system. The system includes: a photovoltaic array, a direct current conversion unit, a bus unit, and an inverter unit, where there are one or more photovoltaic arrays; the photovoltaic array is configured to: convert solar energy into electric energy, in other words, generate direct current power, and output a direct current voltage. The bus unit stores direct current electric energy output by the direct current conversion unit or directly stores the direct current electric energy output by the photovoltaic array, to increase a bus voltage in the first bus unit.

Abstract: A related power conversion circuit includes a three-level switch circuit and a resonant circuit, and a control method of the related power conversion circuit includes: controlling all transistors in the three-level switch circuit to be turned off, where a body diode connected in parallel to a transistor S1, a body diode connected in parallel to a transistor Q1, and a body diode connected in parallel to a transistor Q2 are all turned on based on a current freewheeling function of the resonant circuit; controlling the S1 to be turned on, to set up a first working state of the power conversion circuit; and after the first working state lasts for a time length T1, controlling the Q1 and the Q2 to be turned on.

Abstract: A resonant converter includes: an input power supply, a bleeder circuit, a multi-level switching network, a resonant unit, and a transformer. The input power supply is connected to the bleeder circuit, the multi-level switching network is connected to the bleeder circuit, a clamping middle point of the multi-level switching network is connected to a middle point of the bleeder circuit; one end of the resonant unit is connected to the output terminal of the multi-level switching network, and the other end of the resonant unit is connected to one end of a primary side of the transformer; and the multi-level switching network instructs the output terminal of the multi-level switching network to output a square wave voltage with different amplitudes, to serve as an input voltage of the resonant unit, where the input voltage is used to adjust a gain of the resonant converter.

Abstract: A resonant converter circuit comprises a multi-level inverter circuit placed before a resonant unit, and the multi-level inverter circuit can reduce a voltage to be input to the resonant unit. The reduced input voltage of the resonant unit results in a drop in an output voltage of the entire resonant converter circuit. In this process, the final output voltage is adjusted by adjusting the input voltage of the resonant unit, with no need to substantially adjust a switching frequency of the resonant converter circuit.

Abstract: There is provided a method of operating a reconfigurable differential protection scheme for carrying out differential protection of an electrical power network, the electrical power network comprising terminals, each of the terminals configured to be in communication with each other within a communications network. The method includes controlling the differential protection scheme to deactivate the differential protection, and selecting a terminal to be configured out of or into the differential protection scheme. The method also includes communicating reconfiguration information among the terminals, the reconfiguration information including the selection of the terminal to be configured out of or into the differential protection scheme.

Abstract: A resonant circuit includes first, second, and third input nodes configured to receive a three phase input power and is formed as a delta circuit including a first leg connected between a first corner node and a second corner node, a second leg connected between the second corner node and a third corner node, and a third leg connected between the third corner node and the first corner node. A first outer resonant device is connected between the first input node and the first corner node, a second outer resonant device connected between the second input node and the second corner node, and a third outer resonant device connected between the third input node and the third corner node. Each leg of the delta circuit includes an inner resonant device connected in series with a corresponding transformer.

Abstract: A wave loss detection circuit includes: an anode of the diode receives a first drive signal, and a cathode of the diode is connected to a first end of the first resistor; a second end of the first resistor is connected to a first end of the first energy storage unit, a first end of the second resistor, and a first input end of the comparison unit; a second end of the first energy storage unit and a second end of the second resistor are connected to a ground level, and a resistance of the first resistor is less than a resistance of the second resistor; a second input end of the comparison unit is configured to receive a threshold voltage, and if a voltage signal received by the first input end is less than the threshold voltage, which indicates that a wave loss occurs in the first drive signal.

Abstract: There is provided a method of operating a reconfigurable differential protection scheme for carrying out differential protection of an electrical power network, the electrical power network comprising terminals, each of the terminals configured to be in communication with each other within a communications network. The method includes controlling the differential protection scheme to deactivate the differential protection, and selecting a terminal to be configured out of or into the differential protection scheme. The method also includes communicating reconfiguration information among the terminals, the reconfiguration information including the selection of the terminal to be configured out of or into the differential protection scheme.

Abstract: A resonant circuit includes first, second, and third input nodes configured to receive a three phase input power and is formed as a delta circuit including a first leg connected between a first corner node and a second corner node, a second leg connected between the second corner node and a third corner node, and a third leg connected between the third corner node and the first corner node. A first outer resonant device is connected between the first input node and the first corner node, a second outer resonant device connected between the second input node and the second corner node, and a third outer resonant device connected between the third input node and the third corner node. Each leg of the delta circuit includes an inner resonant device connected in series with a corresponding transformer.

Abstract: A wave loss detection circuit includes: an anode of the diode receives a first drive signal, and a cathode of the diode is connected to a first end of the first resistor; a second end of the first resistor is connected to a first end of the first energy storage unit, a first end of the second resistor, and a first input end of the comparison unit; a second end of the first energy storage unit and a second end of the second resistor are connected to a ground level, and a resistance of the first resistor is less than a resistance of the second resistor; a second input end of the comparison unit is configured to receive a threshold voltage, and if a voltage signal received by the first input end is less than the threshold voltage, which indicates that a wave loss occurs in the first drive signal.

Abstract: An inversion method and an inverter, in which a fifth switch tube, a sixth switch tube, a fifth diode, a sixth diode, and a first capacitor are added in the existing inverter circuit including a bridge arm, the fifth switch tube is connected in parallel to the fifth diode, and the sixth switch tube is connected in parallel to the sixth diode; wherein the positive pole of the fifth diode is connected to the negative pole of a direct current source, the negative pole of the fifth diode is connected to a connection circuit between a second inductor and an alternating current source, the positive pole of the sixth diode is connected to the negative pole of the direct current source, and the negative pole of the sixth diode is connected to a connection circuit between a first inductor and the alternating current source.