Abstract: A high voltage battery cluster, and an overcurrent protection circuit and a switch box of the high voltage battery cluster are provided. The overcurrent protection circuit includes a first fusing module and a second fusing module. Since a withstand current-time curve of the first fusing module is different from a withstand current-time curve of the second fusing module, in a case that an overcurrent fault occurs in a high voltage battery cluster, one fusing module can cause an open circuit in the high voltage battery cluster prior to another fusing module, thereby preventing the high voltage battery cluster from being broken by a large current when an overcurrent fault occurs in the high voltage battery cluster, thus ensuring an electrical safety of the high voltage battery cluster.

Abstract: A high voltage battery cluster, and an overcurrent protection circuit and a switch box of the high voltage battery cluster are provided. The overcurrent protection circuit includes a first fusing module and a second fusing module. Since a withstand current-time curve of the first fusing module is different from a withstand current-time curve of the second fusing module, in a case that an overcurrent fault occurs in a high voltage battery cluster, one fusing module can cause an open circuit in the high voltage battery cluster prior to another fusing module, thereby preventing the high voltage battery cluster from being broken by a large current when an overcurrent fault occurs in the high voltage battery cluster, thus ensuring an electrical safety of the high voltage battery cluster.

Abstract: A photovoltaic solid-state transformer, a photovoltaic inverter system and a bidirectional high-voltage transformer are provided. The photovoltaic solid-state transformer includes: multiple single phase modules and a filter. Each of the single phase modules includes multiple multiple-output isolated DC/DC converters and multiple cascade DC/AC modules, where each of the multiple-output isolated DC/DC converters includes a DC/AC module, a high frequency transformer and multiple AC/DC modules. The multiple single phase modules are connected to the grid via the filter in a star connection or a delta connection. The DC/DC converters and the cascade DC/AC modules are simple logical switches and have conversion efficiency higher than 99%, such that the photovoltaic solid-state transformer has a reduced volume, and an improved overall efficiency higher than 98.5%.

Abstract: A primary coil can be inside the recess, where the primary coil is wound around the center of the recess. A secondary magnetic core can include a protruding center portion that is configured for insertion into the center of the recess so that the protruding center portion overlaps the primary magnetic core side wall and is configured to provide separation between the primary magnetic core and the secondary magnetic core. A secondary coil can be wound around the protruding center portion of the secondary magnetic core.

Abstract: A medium and high voltage energy conversion system is provided. An input terminal of each of high-voltage isolated DC/DC converters in a phase circuit of the system is connected to a common DC bus. Each of the high-voltage isolated DC/DC converters converts, based on an open-loop control strategy or a closed-loop control strategy, a DC input voltage of a cascade module connected to the high-voltage isolated DC/DC converter into an instruction value related to a voltage of the common DC bus. A system controller of the system calculates, based on at least a voltage-current double loop control strategy, a three-phase modulation instruction to be sent to the cascade modules in three phases according to a parameter related to the voltage of the common DC bus, to implement grid-connected control on three phase circuits.

Abstract: A medium-high voltage photovoltaic (PV) power generation system is provided. A PV string of the system is insulated from the ground via an insulator of a medium-high voltage withstanding level, so that the PV string is applicable under a high voltage level. The PV strings are connected to cascade modules. An output voltage of series-connected cascade modules is grid-connected to a 10 kV power grid through a three-phase filter, without a power booster transformer or a high-frequency isolated DC/DC converter in a conventional power station, thereby improving the system efficiency.

Abstract: Provided are a cascaded photovoltaic grid-connected inverter, a control method and a control device for the same. The method includes: determining whether at least one of inverter units of the cascaded photovoltaic grid-connected inverter is over-modulated; injecting a reactive current to a power grid to make a grid-connected current effective value greater than or equal to ?{square root over (2)}*idcmin, in a case that at least one of the inverter units is over-modulated; determining a voltage U0 required for grid connection for the cascaded photovoltaic grid-connected inverter corresponding to a current grid-connected current effective value; and adjusting an output active voltage of each of the inverter units according to Ujd=Pj/P0*U0d, and adjusting an output reactive voltage of each of the inverter units in a case that none of the inverter units is over-modulated.

Abstract: A cooperative control method and device for a photovoltaic optimizer and a photovoltaic inverter are provided. The cooperative control method and device are applicable to a grid-connected photovoltaic system including N photovoltaic components, N photovoltaic optimizers and one photovoltaic inverter. The N photovoltaic components are respectively connected to input sides of the N photovoltaic optimizers, and output sides of the N photovoltaic optimizers are connected to a DC side of the photovoltaic inverter, N being an integer greater than or equal to 1. The cooperative control method includes determining an operation parameter of the grid-connected photovoltaic system; judging whether the operation parameter is lower than a preset value; and adjusting a voltage of the DC side of the photovoltaic inverter until the operation parameter is not lower than the preset value, in a case that the operation parameter is lower than the preset value.

Abstract: A control apparatus and a combiner box are provided. In a case that component maintenance needs to be performed, an optimizer connected to the combiner box is controlled to operate in a safe mode, and a switch-off signal is outputted to disconnect the combiner box from an inverter if an output current of the combiner box is smaller than a threshold. In a case that the maintenance is completed, the optimizer connected to the combiner box is controlled to operate in a maximum power point tracking mode, and the combiner box is connected to the inverter if an input voltage of the combiner box is greater than an output voltage of the combiner box, that is, if an output voltage of a corresponding string increases gradually to a value exceeding a direct current bus voltage.

Abstract: A medium and high voltage energy conversion system is provided. An input terminal of each of high-voltage isolated DC/DC converters in a phase circuit of the system is connected to a common DC bus. Each of the high-voltage isolated DC/DC converters converts, based on an open-loop control strategy or a closed-loop control strategy, a DC input voltage of a cascade module connected to the high-voltage isolated DC/DC converter into an instruction value related to a voltage of the common DC bus. A system controller of the system calculates, based on at least a voltage-current double loop control strategy, a three-phase modulation instruction to be sent to the cascade modules in three phases according to a parameter related to the voltage of the common DC bus, to implement grid-connected control on three phase circuits.

Abstract: A medium-high voltage photovoltaic (PV) power generation system is provided. A PV string of the system is insulated from the ground via an insulator of a medium-high voltage withstanding level, so that the PV string is applicable under a high voltage level. The PV strings are connected to cascade modules. An output voltage of series-connected cascade modules is grid-connected to a 10 kV power grid through a three-phase filter, without a power booster transformer or a high-frequency isolated DC/DC converter in a conventional power station, thereby improving the system efficiency.

Abstract: An AC-DC photovoltaic device is provided, including: a photovoltaic module, a direct current side capacitor, a DC-PWM power switching circuit and a controller. The direct current side capacitor is connected in parallel with an output terminal of the photovoltaic module. An input terminal of the DC-PWM power switching circuit is connected with the output terminal of the photovoltaic module. The DC-PWM power switching circuit includes a controllable switch transistor. The controller is configured to output a switch control signal to control a switching state of the controllable switch transistor in the DC-PWM power switching circuit, to control the DC-PWM power switching circuit to output a direct current PWM wave in a case that the switch control signal is a direct current modulation signal, and output an alternating current PWM wave in a case that the switch control signal is an alternating current modulation signal.

Abstract: A photovoltaic solid-state transformer, a photovoltaic inverter system and a bidirectional high-voltage transformer are provided. The photovoltaic solid-state transformer includes: multiple single phase modules and a filter. Each of the single phase modules includes multiple multiple-output isolated DC/DC converters and multiple cascade DC/AC modules, where each of the multiple-output isolated DC/DC converters includes a DC/AC module, a high frequency transformer and multiple AC/DC modules. The multiple single phase modules are connected to the grid via the filter in a star connection or a delta connection. The DC/DC converters and the cascade DC/AC modules are simple logical switches and have conversion efficiency higher than 99%, such that the photovoltaic solid-state transformer has a reduced volume, and an improved overall efficiency higher than 98.5%.

Abstract: A cascaded multi-level inverter system, a modulation method and a controller for the same are provided. The method includes performing a maximum power point tracking control based on a voltage signal and a current signal of each DC source and a voltage signal and a current signal of the power grid obtained by sampling, calculating a first modulation signal for suppressing power imbalance, and outputting the first modulation signal to each inverter unit; and calculating, based on the calculated reactive current instruction value, the calculated active current instruction value, and a current signal of the reactive compensation device obtained by sampling, a second modulation signal for causing an output power factor of the cascaded multi-level inverter system to be 1, and outputting the second modulation signal to the reactive compensation device.

Abstract: An ANPC inverter, a zero-crossing switching method and a zero-crossing switching apparatus of the ANPC inverter are provided. The method includes: controlling switch states of switch devices in a bridge leg to change according to a preset logic when zero-crossing switching occurs in an output voltage instruction of the bridge leg, so as to prevent overvoltage in the switch device in the bridge leg. The preset logic includes switching among a sequence of switch state combinations. Switch state combinations of the switch devices before and after the zero-crossing switching occurs are defined as the first and second switch state combinations of the sequence. The second to the penultimate switch state combinations are all safe switch state combinations selected in advance, in each of which a maximum voltage borne by the switch devices in the bridge leg is clamped to a safe limit value.

Abstract: A communication host and a photovoltaic power generation system are provided. The communication host includes an acquiring module, a determining module and a control module. The acquiring module is configured to acquire an operating state parameter of the system. The determining module is configured to determine whether the optimizer meets a first preset triggering condition based on the operating state parameter. In a case where the optimizer meets the first preset triggering condition, a first triggering instruction is transmitted, to instruct the system to decrease, in response to the first triggering instruction, the direct current bus voltage of the grid-connected inverter, and/or a second triggering instruction is transmitted, to instruct the system to increase, in response to the second triggering instruction, an output voltage limiting value of at least one of the optimizers meeting the first preset triggering condition.

Abstract: A communication host and a photovoltaic power generation system are provided. The communication host includes an acquiring module, a determining module and a control module. The acquiring module is configured to acquire an operating state parameter of the system. The determining module is configured to determine whether the optimizer meets a first preset triggering condition based on the operating state parameter. In a case where the optimizer meets the first preset triggering condition, a first triggering instruction is transmitted, to instruct the system to decrease, in response to the first triggering instruction, the direct current bus voltage of the grid-connected inverter, and/or a second triggering instruction is transmitted, to instruct the system to increase, in response to the second triggering instruction, an output voltage limiting value of at least one of the optimizers meeting the first preset triggering condition.

Abstract: A cascaded H-bridge inverter and a method for handling a fault thereof are provided. An output voltage or an output power of each of N solar panels is detected by a controller. In a case that the output voltage of at least one of the N solar panels is lower than a preset voltage, or that the output power of at least one of the N solar panels is lower than a preset power, the controller controls a corresponding switching device to be switched off, and changes a set value of a voltage across a capacitor in the direct current side. Then, the controller controls a corresponding H-bridge module to perform inverting by taking the set value of the voltage across the capacitor in the direct current side as an input value, so that a total output modulation voltage of the cascaded H-bridge inverter meets a preset condition.

Abstract: A control apparatus and a combiner box are provided. In a case that component maintenance needs to be performed, an optimizer connected to the combiner box is controlled to operate in a safe mode, and a switch-off signal is outputted to disconnect the combiner box from an inverter if an output current of the combiner box is smaller than a threshold. In a case that the maintenance is completed, the optimizer connected to the combiner box is controlled to operate in a maximum power point tracking mode, and the combiner box is connected to the inverter if an input voltage of the combiner box is greater than an output voltage of the combiner box, that is, if an output voltage of a corresponding string increases gradually to a value exceeding a direct current bus voltage.

Abstract: An ANPC inverter, a zero-crossing switching method and a zero-crossing switching apparatus of the ANPC inverter are provided. The method includes: controlling switch states of switch devices in a bridge leg to change according to a preset logic when zero-crossing switching occurs in an output voltage instruction of the bridge leg, so as to prevent overvoltage in the switch device in the bridge leg. The preset logic includes switching among a sequence of switch state combinations. Switch state combinations of the switch devices before and after the zero-crossing switching occurs are defined as the first and second switch state combinations of the sequence. The second to the penultimate switch state combinations are all safe switch state combinations selected in advance, in each of which a maximum voltage borne by the switch devices in the bridge leg is clamped to a safe limit value.