Proposed is an automatic transfer switch with an N-phase overlapping structure, the switch including: a driving unit including a drive shaft provided to generate power; a three-contact switching unit including a normal power shaft and an emergency power shaft provided to be rotated by the drive shaft, and a normal power terminal and an emergency power terminal for inputting/releasing normal power and emergency power; and an N-phase overlapping unit including a first insertion part having a first insertion hole, an N-phase normal contact terminal provided to input/release an N-phase normal power, a second insertion part having a second insertion hole, an N-phase emergency contact terminal provided to input/release an N-phase emergency power, and a connection bar connected between the first insertion part and the second insertion part so as to be interlocked with each other.

When a power outage occurs, an uninterruptable power supplies may lose all grid connections including a neutral connection which may be connected to ground. To avoid the loss of a ground connection to the power circuits of the UPS, a switch unit may be used to selectively connect a neutral conductor of the circuit to a ground terminal. The switch unit may comprise a power relay, a fast switch device (FSD), and a controller. The power relay and FSD may be connected in series between the neutral conductor of the circuit and a ground terminal. The controller may be configured to: close the FSD when the voltage between ground and neutral (Vng) goes above a first threshold, open the FSD when the voltage between any grid connection and neutral (Vg) goes above a second threshold, and close the FSD when Vg is below the second threshold.

Each of n uninterruptible power supplies connected in parallel includes m uninterruptible power supply modules connected in parallel between an input terminal and an output terminal. In each uninterruptible power supply module, a controller controls an inverter so that the current value of AC power supplied from the inverter to a load matches a first instruction value. The n×m controllers are connected to one another to constitute an integrated controller. When a failure is detected in one of the m uninterruptible power supply modules in any one of the n uninterruptible power supplies, the integrated controller disconnects the failed uninterruptible power supply module and changes the first instruction value to a second instruction value so as to equalize the current values of AC power output from the inverters of the remaining normal uninterruptible power supply modules.

In the present uninterruptible power supply apparatus (U1), in a power failure of a commercial AC power supply (41), a switch (1) is turned off to electrically cut off the commercial AC power supply (41) from an AC input filter (2), and when DC voltage (ΔE=Ep−En) that is the difference between terminal-to-terminal voltages (Ep, En) of first and second capacitors (C1, C2) exceeds a threshold voltage (ETH), first and second IGBT devices (Q1, Q2) or third and fourth IGBT devices (Q3, Q4) included in the converter (3) are turned on and off to reduce DC voltage (ΔE).

The present disclosure provides to a power converter including an AC input terminal (ACin), a neutral terminal (N), an AC output terminal (ACout), an AC/DC converter circuit (210) connected between the AC input terminal, a positive DC terminal (DCP), and a negative DC terminal (DCN), a DC capacitor (C15) connected between the positive DC terminal (DCP) and the negative DC terminal (DCN), a line frequency commutated neutral circuit (220) connected between the positive DC terminal (DCP), the negative DC terminal (DCN), and the neutral terminal (N), and a DC/AC converter circuit (230) connected between the positive DC terminal (DCP), the negative DC terminal (DCN), the AC output terminal (ACout), and the neutral terminal (N). The power converter further includes an auxiliary converter circuit (240) connected between the positive DC terminal (DCP), the negative DC terminal (DCN), and the neutral terminal (N).

The present disclosure provides a multi-input power converter, including three bridge arm units connected between a three-phase alternating current power supply and a positive/negative direct current bus. A first capacitor and a second capacitor are connected in series between the positive direct current bus and the negative direct current bus, and a node formed by connecting the capacitors is connected to a neutral point. Each bridge arm unit includes an inductor and a bidirectional switch unit that are connected in series, and a current direction control bridge arm connected between the positive direct current bus and the negative direct current bus, and a node formed by connecting the inductor to the bidirectional switch unit is connected to the current direction control bridge arm. Second ends of bidirectional switch units of the three bridge arm units are connected to the neutral point. In a battery mode, two of the bridge arm units are used as battery mounting bridge arms to constitute a direct current loop with a rechargeable battery, to supply power to the positive direct current bus and the negative direct current bus, and the remaining bridge arm unit enables an inductor on the bridge arm unit to alternately connect the positive direct current bus and the negative direct current bus, to balance a bus capacitance voltage. The power converter has high conversion quality, a small quantity of elements, and a reduced volume.

In an uninterruptible power supply apparatus, in a power failure of a commercial AC power supply, a switch is turned off to electrically cut off the commercial AC power supply from an AC input filter, and a DC voltage converter is controlled such that a DC voltage that is the difference between terminal-to-terminal voltages of first and second capacitors is eliminated, and when the DC voltage exceeds a threshold voltage, a converter is controlled to reduce the DC voltage.

The present disclosure provides a high-power-density power converter topology with a common neutral between its input and output AC ports while having a single DC bus. The topology may also be embodied as an online uninterruptible power supply (UPS). The presently-disclosed topology enables high power density by utilizing half-bridge switch structures suitable for MHz-frequency operation.

An Uninterruptible Power Supply (UPS) system, the UPS system comprising an input configured to receive input AC power having an input voltage level and an input frequency, an output configured to provide output AC power to a load, the output power having an output voltage level and an output frequency, a converter coupled to the input and configured to convert the input AC power into DC power, an inverter coupled to the output and configured to convert the DC power into the output AC power and provide the output AC power to the output, a DC bus coupled between the converter and the inverter including a first capacitive element and a second capacitive element, the first capacitive element being coupled to a first output and a second output of the converter and the second capacitive element being coupled to a first input and a second input of the inverter, a de-coupler circuit coupled between the first and second capacitive elements and configured to selectively decouple the inverter from the converter, and a controller configured to operate the converter, the inverter, and the de-coupler circuit in a first mode of operation such that the output voltage level and output frequency of the output AC power are the same as the input voltage level and input frequency of the input AC power and a second mode of operation such that at least one of the output voltage level or output frequency of the output AC power differs from the input voltage level and input frequency of the input AC power.

A circuit includes an emergency lighting system and an AC/DC converter. An output terminal of the emergency lighting system is electrically connected to a LED load, and the other output terminal LED_ON of the emergency lighting system is electrically connected to a switch S2. The switch S2 is controlled by the emergency lighting system. The emergency lighting system includes an AC input detection module, a switching time detection module and a lithium battery. The AC input detection module is electrically connected to a neutral wire VN and a live wire VL. The switching time detection module is electrically connected between an output terminal of the AC input detection module and the LED_ON terminal. An output terminal of the AC/DC converter is electrically connected to a positive electrode of the lithium battery, and the other output terminal of the AC/DC converter is electrically connected to the LED load.