Abstract: An inverter, a method and a device for controlling the inverter are provided, to improve efficiency of the inverter. The inverter includes a three-level active clamped topology including a first and second bus capacitors and an inverter circuit, the inverter circuit includes a first switch transistor to a sixth switch transistor. The inverter further includes a seventh switch transistor and an eighth switch transistor; the seventh switch transistor and the eighth switch transistor are connected in series between the positive direct current bus and the negative direct current bus in a same direction, and a serial point of the seventh switch transistor and the eighth switch transistor is connected to a serial point of the second switch transistor and the third switch transistor; and the seventh switch transistor and the eighth switch transistor are anti-parallel connected to corresponding diodes respectively.

Abstract: The present invention discloses a control method and device for a circuit with a bridge arm of a switch. The soft switching converter comprises at least two bridge arms of the switch, and an auxiliary switch assisting in switching of a main switch of the bridge arm of the switch. The control method comprises the steps of: S1. after controlling the auxiliary switch to be turned on for a first period of time, controlling main switches set at the same position of individual bridge arms of the switch to be simultaneously turned on; S2. after a second period of time following a time when the main switches set at the same position of individual bridge arms of the switch are simultaneously turned on, turning off the auxiliary switch. The present invention can reduce system loss and noise, so as to improve efficiency.

Abstract: The present invention discloses a soft switching auxiliary circuit, comprising: an auxiliary coupling inductor configured to receive currents from a respective branch of a main circuit connected to the soft switching auxiliary circuit and perform a current sharing outputting; a clamping diode configured to receive an inductive voltage from the auxiliary coupling inductor and feed the inductive voltage back to a main switch transistor of the main circuit; an auxiliary switch transistor configured to receive a current from the main switch transistor of the main circuit and output the current to the clamping diode. The present invention further discloses a three-level three-phase zero-voltage conversion circuit. By means of the present invention, it is possible to reduce hard switching loss, to improve system switching frequency, to improve efficiency and to reduce electromagnetic interference.

Abstract: An Uninterrupted Power Supply (UPS) power supply system is provided, which includes: a filter module connected to a mains supply and configured to filter an input from the mains supply; a BOOST module, where a first terminal of the BOOST module is connected to the filter module via a first switch group and connected to a battery via a second switch group, and a second terminal of the BOOST module is connected to a positive bus and a negative bus; and a bi-directional Direct Current/Direct Current (DC/DC) module, where a first terminal of the bi-directional DC/DC module is connected to the battery, and a second terminal of the bi-directional DC/DC module is connected to the positive bus and the negative bus.

Abstract: A power supply system and method includes a power grid input unit and a diesel generator input unit, separately used for supplying an alternating current to a power supply unit. An automatic transfer switch unit is connected to the power grid input unit and the power supply unit or connected to the diesel generator input unit and the power supply unit, which is used for converting the received alternating current into a direct current. A control unit, which is used for monitoring a current load current and current diesel generator power, determines when to turn off a preset number of power supply loads according to a magnitude relationship between the current diesel generator power and the current load power, as well as according to priority levels of current loads.

Abstract: Provided is an inductor winding method and an inductor winding device. The inductor winding method comprises steps of: A. dividing turns of coil of each winding of the inductor into a first winding and a second winding based on a preset ratio; B. winding the first winding on one of multiple magnetic columns, and winding the second winding on another one of the multiple magnetic columns which is different from the magnetic column on which the first winding is wound; and C. performing step A and step B cyclically until all the windings of the inductor are wound. With a coupling inductor having interleaving-wound structure, power frequency magnetic fluxes generated by magnetic lines in magnetic columns counteract one another, thereby solving the problem of high magnetic flux density in a magnetic core while achieving certain leakage inductance.

Abstract: A method and a device for controlling a Vienna-like three-level circuit are provided. The method includes: detecting an inductor current of an inductor connected to each operating high-frequency bridge arm in the Vienna-like three-level circuit during a positive half cycle of an AC input voltage; and in a case that a freewheeling switch transistor on the high-frequency bridge arm to which the inductor is connected is in an on state, and a main switch transistor is in an off state, controlling the freewheeling switch transistor to maintain in the on state and the main switch transistor to maintain in the off state if the detected inductor current does not reach a preset negative current, and controlling the freewheeling switch transistor to be turned off and the main switch transistor to be turned on if the detected inductor current reaches the preset negative current.

Abstract: Control method and device for I-type three-level circuit are disclosed, which can realize zero-voltage turn on of switching tube of high-frequency bridge arm, reduce circuit loss and improve circuit efficiency. The control method includes: detecting a current of an inductor connected with each of high-frequency arm bridges in operation state in the circuit; in a positive half cycle of AC connection terminal voltage of the circuit, when a freewheeling switching tube of the high-frequency arm bridge connected with the inductor is in ON state and a main switching tube is in OFF state, controlling the freewheeling switching tube to keep in ON state and the main switching tube to keep in OFF state if the current does not reach a preset negative current, and controlling the freewheeling switching tube to be turned off and the main switching tube to be turned on if the current reaches the preset negative current.

Abstract: The present invention discloses a lossless snubber circuit and an operation method thereof. The lossless snubber circuit includes a first snubber circuit. The first snubber circuit includes a first diode (D7) and a capacitor (C3). The capacitance of the capacitor (C3) is big enough so that a voltage spike generated at the moment when a switch transistor (Q1) is turned off is depressed by charging the capacitor (C3). When the switch transistor (Q1) is on, the electric charges released by the capacitor (C3) are directed to a first capacitor (C1) in a three-phase Vienna structure, so as to avoid the problem of voltage stress difference caused by the large quantity of electric charges released by the capacitor (C3) flowing back to the switch transistor (Q1).

Abstract: An automatic equalization method and apparatus for bus bar voltages of a Power Factor Correction (PFC) circuit. The method includes calculating a difference in voltages of a positive bus bar and a negative bus bar, and increasing the rotation speed of a fan in the PFC circuit according to the difference in voltages of the positive bus bar and the negative bus bar until the voltages of the positive and negative bus bars are equalized. The apparatus includes a voltage difference module configured to calculate a difference in voltages of a positive bus bar and a negative bus bar, and a rotation speed control module configured to increase a rotation speed of a fan in the PFC circuit according to the difference in voltages of the positive bus bar and the negative bus bar, until the voltages of the positive and negative bus bars are equalized.

Abstract: There is provided a grounding detection device and method. The grounding detection device may include an insulation tester and a grounding resistance providing unit. The insulation tester may be mounted in a first cabinet, electrically connected to a positive busbar and a negative busbar to detect an equivalent busbar-to-ground resistance, and grounded via the first cabinet. The grounding resistance providing unit may be mounted at least in part in a second cabinet different from the first cabinet, electrically connected to at least one of the positive busbar and the negative busbar to provide a grounding resistance, and grounded via the second cabinet. The insulation tester may determine, based on resistance values of the equivalent busbar-to-ground resistance and the grounding resistance, whether there is a ground fault or not for the insulation tester, the first cabinet, and the second cabinet.

Abstract: An air conditioner is disclosed. The compressor has an entrance coupled to an exit of the evaporator via the first ON/OFF valve; and an exit coupled to an entrance of the condenser via the first flow-direction valve. The liquid pump has an entrance coupled to an exit of the liquid accumulator via the second ON/OFF valve; and an exit coupled to an entrance of the throttling device via the second flow-direction valve. An exit of the condenser is coupled to an entrance of the liquid accumulator; an exit of the throttling device is coupled to an entrance of the evaporator. The compressor's bypass pipe has an entrance coupled to an exit of the evaporator; and an exit coupled to an entrance of the condenser. The liquid pump's bypass pipe has an entrance coupled to an exit of the liquid accumulator; an exit coupled to an entrance of the throttling device.

Abstract: The present invention relates to a feedback device for a power supply, including a main feedback module, an auxiliary feedback module and a feedback control module. The main feedback module is adapted to sample a voltage on a main output branch of the power supply, and output a main feedback voltage to the feedback control module. The auxiliary feedback module is adapted to reduce the main feedback voltage when a voltage on an auxiliary output branch of the power supply drops. The feedback control module is adapted to control the power supply to increase its power output when the main feedback voltage decreases, so that the voltage on the auxiliary output branch is restored to normal. By using the power supply feedback device of the present invention, the circuit is simple, not only solving voltage sag problems, but also ensuring the power density and cost.

Abstract: A UPS control circuit and a UPS is provided. The UPS includes a rechargeable battery and a UPS control circuit connected with the rechargeable battery. The UPS control circuit includes an input filtering circuit, a rectification circuit, an inversion circuit, a static transfer switch, an output filtering circuit, a control circuit, and a multipurpose DC/DC circuit connected between the rechargeable battery and an output terminal of the rectification circuit. The multipurpose DC/DC circuit is controlled by the control circuit. In a battery mode, the rechargeable battery supplies an input voltage to the inversion circuit via the multipurpose DC/DC circuit. In a mains power mode, the rechargeable battery is charged by an output voltage of the rectification circuit via the multipurpose DC/DC circuit. Therefore, no independent charging circuit is needed to charge the rechargeable battery, causing a simpler circuit structure and a lower cost, and providing greater value to the customer.

Abstract: An air conditioner includes an evaporator (9), a condenser (14), a compressor (11), a liquid pump (3), a liquid accumulator (1), a first ON/OFF control valve element (10), a first valve element for flow direction control (12), a second ON/OFF control valve element (2), a second valve element for flow direction control (5), a throttling device (8), a liquid pump's bypass pipe (16) with a third valve element for flow direction control (6) and a compressor's bypass pipe (18) with a forth valve element for flow direction control (13). An entrance of the compressor (11) is coupled to an exit of the evaporator (9) via the first ON/OFF control valve element (10); an exit of the compressor (11) is coupled to an entrance of the condenser (14) via the first valve element for flow direction control (12).

Abstract: The invention relates to a parallel inverter system, in which each inverter includes a synchronized square wave generator, a voltage given generator, a voltage regulating unit and a power amplifier unit. All of the above components are connected in parallel. The output current given by the voltage regulating unit no longer requires selection of “one out of many components,” but outputs a linear combination result of outputs of all of the voltage regulating units after linear combination, thereby changing an unequal parallel connection to an equalized parallel connection. At the same time, the output square waves of all of synchronizing square wave generators are inputted into voltage given generators as the synchronizing square wave after AND. The output sine waves of all of voltage given generators after linear combination are used as given voltage of voltage regulating units.

Abstract: This invention relates to a method for driving converts of an uninterrupted power supply (UPS), characterized in that the generating circuit of driving signal for power factor correction generates two driving signals (DRV1, DRV2) to drive the switch transistors (Q9, Q11) of the positive and negative power factor correction branch respectively, the holding and shifting circuit of driving pulse-width after the generating circuit of driving signal for power factor correction holds and shifts the pulse-width of the two driving signals, and drives the switch transistors (Q10, Q12) parallel to the aforesaid switch transistors in the positive and negative power factor correction branch respectively. Since a circuit for holding the pulse-width is introduced, the currents of the switch transistors of the two parallel boost converters are maintained substantially the same, thereby improving the reliability of the uninterrupted power supply system.

Abstract: This invention relates to a PFC circuit for an uninterrupted power supply. Such a PFC circuit includes a first converter, a second converter, an energy storing branch composed of two capacitors in series, and a controller. Each of the first and the second converters has an input terminal and two output terminals. The input terminal is connected with the AC live wire of the commercial power, while the two output terminals of each converter are connected in parallel with the two ends of the energy storing branch, with the parallel joints acting as the output terminal of the positive and the negative voltages respectively. The common nod of the two capacitors in series serves as the common output terminal of the positive and the negative voltages, and it is connected with the neutral of the commercial power.

Abstract: This invention relates to a method of establishing a master unit in a multi-unit parallel system. Each module with a respective number is connected through a bus, and has a different host-identifying pulse width Ts and a host-releasing pulse width Tw. According to the respective numbers, each module sends its host-identifying pulse to the bus and receives the feedback pulse, and then establishes a master unit among all of modules after comparing the feedback pulse width Tr and the host-releasing pulse width Tw. This method effectively realizes a decentralized controlling strategy for phase synchronization in a parallel inverter system and ensures that only one master unit exists in the parallel system. The connection of the multi-string parallel signal bus is simple, and can be connected in circle to provide the redundancy. Compared with the prior art, it is much simple in structure and flexible in configuration and adjustment, and has more reliability and real-time capability.

Abstract: The present invention relates to a low loss boost circuit used in power conversion equipment of power supplies or other power systems. It comprises controlling a duty cycle of a power switch; realizing voltage boosting and regulating of the output voltage through the energy storage in a boost inductor; reducing the reverse recovery current using an auxiliary inductor, wherein a secondary winding of the inductor supplies additional energy thereto and provides a path for transferring the energy from the auxiliary inductor to the energy storage capacitor. The present invention has high efficiency and is suitable for power converter with PFC, such as, telecommunication power supply and uninterrupted power supply.