Abstract: A drive acceleration circuit, including: a drive power supply, including an output end and a reference signal end, where the output end output a drive signal, and the reference signal end is connected to a connection end of a switching device and output a reference signal to the connection end; a first signal route, where the first signal route is connected to the output end of the drive power supply and a control end of the switching device, and is configured to drive, based on the drive signal, the switching device to turn on/off; and a second signal route, connected in parallel with the first signal route, including a drive acceleration unit and a selective conduction unit, one end of the drive acceleration unit is connected to the drive power supply, another end of the drive acceleration unit is connected to the switching device through the selective conduction unit.

Abstract: This application discloses a photovoltaic system, a direct-current combiner box, and a fault isolation method. The photovoltaic system includes a fault isolation circuit and a DC/DC conversion circuit. A first end of the fault isolation circuit is connected to N photovoltaic strings, and a second end of the fault isolation circuit is connected to an input end of the DC/DC conversion circuit. The fault isolation circuit includes a multipole switch, and each group of photovoltaic strings in the N photovoltaic strings is connected to an input end of a power conversion circuit through one pole of switch in the multipole switch. Each group of photovoltaic strings includes at least two photovoltaic strings. When a reverse connection fault occurs in the N photovoltaic strings, the entire multipole switch is turned off in linkage.

Abstract: A first input end of a first inverter is connected to a second end of a direct current positive bus, and a second input end of the first inverter is connected to a second end of a neutral bus. A first input end of a second inverter is connected to the second end of the neutral bus, and a second input end of the second inverter is connected to a second end of a direct current negative bus. A controller is configured to control, in startup and shutdown processes, a voltage to ground of the direct current positive bus, a voltage to ground of the direct current negative bus, and a voltage to ground of the neutral bus each to be less than or equal to a preset voltage threshold, to ensure personal safety and device safety.

Abstract: A direct current converter includes a three-level power switching circuit, a resonant circuit, and a controller. An output voltage at an output end of the three-level power switching circuit is used to charge the resonant circuit. The controller is configured to control power switching components in the three-level power switching circuit, so that when the resonant circuit performs charging or discharging at one half of a direct current voltage, one of the power switching components is connected to a current loop of the resonant circuit, and when the resonant circuit performs charging or discharging at the direct current voltage, two of the power switching components are connected to the current loop of the resonant circuit. By using the direct current converter, a voltage borne by the power switching component in the direct current converter during current conversion can be reduced, thereby improving reliability of the direct current converter.

Abstract: The disclosed invention relates to a low-dose celecoxib oral formulation, and a preparation method therefor, which is characterized in that the strength of the formulation is 60-90% of the original strength of the commercial celecoxib product, and the celecoxib formulation with such reduced strength is bioequivalent to the commercial celecoxib product. The celecoxib formulation can be used for the treatment of mild to moderate pain and mild to moderate chronic pain.

Abstract: A boost power conversion circuit includes an inductor, a first switch module, a second switch module, a first unilateral conduction component, a second unilateral conduction component, a flying capacitor, an upper bus capacitor, a lower bus capacitor, and a third unilateral conduction component. The power supply, the inductor, the first switch module, and the second switch module are connected in series to form a loop. The first unilateral conduction component, the second unilateral conduction component, the upper bus capacitor and the lower bus capacitor are connected in series. The flying capacitor is electrically connected between a reverse cut-off end of the first unilateral conduction component and a forward conduction end of the second unilateral conduction component. The third unilateral conduction component is configured to clamp a voltage stress of the second switch module to a lower-bus voltage.

Abstract: A boost power conversion circuit includes an inductor, a first switch module, a second switch module, a first unilateral conduction component, a second unilateral conduction component, a flying capacitor, an upper bus capacitor, a lower bus capacitor, and a third unilateral conduction component. The power supply, the inductor, the first switch module, and the second switch module are connected in series to form a loop. The first unilateral conduction component, the second unilateral conduction component, the upper bus capacitor and the lower bus capacitor are connected in series. The flying capacitor is electrically connected between a reverse cut-off end of the first unilateral conduction component and a forward conduction end of the second unilateral conduction component. The third unilateral conduction component is configured to clamp a voltage stress of the second switch module to a lower-bus voltage.

Abstract: A DC to DC converter uses a multi-level boost converter topology. In addition to the input voltage being connected to an output node through a boost inductor in series with a pair of diodes, a bridge circuit generates a multi-level waveform on one side of flying capacitor, which is on the other side connected between the series connected diodes. The boost converter topology maintains low voltage stress on its components under abnormal conditions on the output node and allows for simple pre-charging of the flying capacitor.

Abstract: A DC to DC converter uses a multi-level boost converter topology. In addition to the input voltage being connected to an output node through a boost inductor in series with a pair of diodes, a bridge circuit generates a multi-level waveform on one side of flying capacitor, which is on the other side connected between the series connected diodes. The boost converter topology maintains low voltage stress on its components under abnormal conditions on the output node and allows for simple pre-charging of the flying capacitor.