Liebert Corporation

Xueli Xiao

Chuntao Zhang

Xiaofei Zhang

The present invention discloses a control method for a soft switch circuit in a switch power source, which generates an alternating primary power filter current by controlling first and second primary power switching devices to be closed and opened, and generates an intermittent alternating resonant current in the same direction as the primary power filter current in a resonant branch by controlling forward and backward auxiliary switching devices to be closed and opened to thereby achieve closing of the first and second primary power switching devices at a zero voltage, and which generates a balance current with the same magnitude as and in the opposite direction to the resonant current in the resonant branch in at least a period of time during the resting of the resonant current by further controlling the forward and backward auxiliary switching devices to be closed and opened to thereby achieve an average current of zero across the resonant branch in a switching cycle. Without any additional balance circuit, this control method can address the imbalance problem of output power of the positive and negative direct current input voltage sources in a soft switch circuit of an existing switch power source.

Control method for soft switch circuit in switch power source

The present invention relates to a control method for a soft switch circuit in a switch power supply, which controls first and second main power switch devices to be turned on and turned off constantly to generate an alternating main power filter current, and controls forward and backward auxiliary switch devices to be turned on and turned off to generate an intermittent alternating resonant current across a resonant branch in the same direction as the main power filter current to thereby achieve zero-voltage turn-on of the first and second main power switch devices; and further controls the forward and backward auxiliary switch devices to be turned on and turned off to generate compensation currents across the resonant branch in the opposite direction to the alternating main power filter current in at least a period of time during resting of the resonant current to thereby accomplish a charging and discharging process of resonant capacitors in a dead time. Thus, a freewheeling diode can be turned on normally, so that it is possible to avoid a damage to the devices due to an impact current and a spark voltage resulting at zero crossing of the current in the soft switch circuit.

Control method for soft switch circuit in switch power supply

The present invention relates to a driving circuit of switch device. The present invention employs transformer isolated driving. The number of said transformers is two. The primary sides of the two transformers are connected to two driving modulators, respectively. The input terminal of a high frequency carrier signal and the input terminal of a driving signal are connected to the input terminal of a first driving modulator. The input terminal of a driving signal being connected with an inverter together with the input terminal of the high frequency carrier signal are connected to the input terminal of a second driving modulator. The first secondary side of the first transformer is connected to a power supply circuit which may provide a necessary voltage for turning on the switch device during a high level period of the driving signal. The first secondary side of a second transformer is connected to a voltage discharging circuit which may discharge a turn-on voltage of the switch device into a low level during a low level period of the driving signal. Therefore, the pair transistor amplification circuit in the existing transformer isolated driving becomes unnecessary, which provides a high driving power. In addition, employing no optical coupler isolated element makes the working life even longer.

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Shenzhen, China

Xueli Xiao