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. The power supply system is a flexible power supply system and includes the oil engine and a plurality of loads.

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. The power supply system also includes a storage battery and an alternating current electric equipment group.

Abstract: The present invention discloses a control method and device for a circuit with a bridge arm of a switch. The soft switching converter includes 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 includes 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: 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: A current limiting control method for a three-level inverter, comprising the following steps: S1. when a current output from a bridge arm is greater than or equal to a current limiting threshold and a received overcurrent signal is enabled, first turning off the main switch transistors and then turning off the auxiliary switch transistors; S2. when the current output from the bridge arm drops to lower than the current limiting threshold and the received overcurrent signal is disabled, turning on the auxiliary switch transistors; S3. when the received overcurrent signal is disabled and a next PWM effective edge of the main switch transistors arrives, turning on the main switch transistors. The present invention relates also to a current limiting control device for a three-level inverter. By implementing the present invention, it is possible to ensure voltage waveform quality and reduce switching loss.

Abstract: Provided is a multi-level inverter, which includes a first bus capacitor, a second bus capacitor, a third bus capacitor, a fourth bus capacitor, a seventh switch unit, an eighth switch unit, an inverter circuit and a filtering circuit. The first bus capacitor, the second bus capacitor, the third bus capacitor and the fourth bus capacitor are connected between a positive direct current bus and a negative direct current bus in series, and a series point between the second bus capacitor and the third bus capacitor is grounded. The switch transistor of the anti-parallel diode having small on-state resistance is used in the multi-level inverter, thereby reducing power loss of the switch unit in the multi-level inverter and reducing power consumption of the circuit.

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 current limiting control method for a three-level inverter, comprising the following steps: S1. when a current output from a bridge arm is greater than or equal to a current limiting threshold and a received overcurrent signal is enabled, first turning off the main switch transistors and then turning off the auxiliary switch transistors; S2. when the current output from the bridge arm drops to lower than the current limiting threshold and the received overcurrent signal is disabled, turning on the auxiliary switch transistors; S3. when the received overcurrent signal is disabled and a next PWM effective edge of the main switch transistors arrives, turning on the main switch transistors. The present invention relates also to a current limiting control device for a three-level inverter. By implementing the present invention, it is possible to ensure voltage waveform quality and reduce switching loss.

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: 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: Provided is a multi-level inverter, which includes a first bus capacitor, a second bus capacitor, a third bus capacitor, a fourth bus capacitor, a seventh switch unit, an eighth switch unit, an inverter circuit and a filtering circuit. The first bus capacitor, the second bus capacitor, the third bus capacitor and the fourth bus capacitor are connected between a positive direct current bus and a negative direct current bus in series, and a series point between the second bus capacitor and the third bus capacitor is grounded. The switch transistor of the anti-parallel diode having small on-state resistance is used in the multi-level inverter, thereby reducing power loss of the switch unit in the multi-level inverter and reducing power consumption of the circuit.