The invention provides a high
power factor soft switching three-phase
induction coil synthetic
heating power supply, three groups of single-
phase conversion circuits are adopted, each single-
phase conversion circuit adopts a single-
phase line for
voltage input and adopts a single-
phase line voltage diode for rectification respectively, a
capacitor is not added for filtering, high-frequency
alternating current pulse voltage which can enable output envelope lines to be sine
waves and adjust the pulse width is formed by conversion through an
inverter circuit, the high-frequency
alternating current pulse voltage is inputted into three induction coils which are independent mutually and wound in parallel through resonant load matching of three groups of high-frequency transformers to form synthetic
magnetic flux, and
eddy current is generated in a workpiece which is heated for heating.
Inverter bridges adopt the phase shift
power control soft switching technology.
Sine wave current outputted by the three single-phase
inverter bridges are sampled and converted to
alternating current voltage signals, the series connection is adopted for connecting the same frequency and the same phase for addition,
square wave signals are formed through a zero-crossing comparison circuit, output pulses can track input square
waves through a phase-locked loop circuit, three
inverter bridge switching tubes are controlled through a power amplification circuit, a pulse distribution circuit and a
driving circuit, and the phase-locked frequency tracking synchronization control is realized.