The invention discloses a three-phase
intermediate frequency power supply. The standard
voltage of a three-phase external
electric network with 380V / 50Hz is input to an industrial frequency
transformer after passing through a three-phase fuse, an input
contactor and an anti-
electromagnetic interference filter, then is input to a three-phase
rectifier after isolation and
voltage reduction and then is filtered through a constant K type inverted-L-shaped L second-order low-pass filter and a constant K type inverted-L-shaped C second-order low-pass filter after being rectified by a bridge
rectifier to obtain the operating direct-
current voltage of a major loop; and the direct-
current voltage is transmitted to an IGBT switching tube in a high-power conversion module, an auxiliary power supply is used for supplying power for a control loop to generate
intermediate frequency as well as an IGBT
pulse width modulation control signal, the IGBT switching tube is driven, the direct-
current voltage is converted into three-phase
intermediate frequency voltage, isolation, integration and regulation are performed on the three-phase intermediate frequency voltage through an output intermediate frequency
transformer, and filtering is performed through the second-order low-pass filter to obtain the standard three-phase intermediate frequency sinusoidal voltage output. The three-phase intermediate frequency power supply overcomes the defects of complex control and driving of intermediate frequency power, excessive high
power loss, low efficiency, poor wave-shape, unstable frequency and poor reliability as the traditional intermediate frequency power supply adopts serially connected regulating transistors for
voltage regulation or adopts a bipolar
transistor, an SCR
thyristor and a GTO
thyristor as the main power tubes.