METHOD OF FREQUENCY CONVERTER CONTROL Russian patent published in 2009 - IPC H02M5/453 

FIELD: electricity.

SUBSTANCE: invention relates to converting engineering and may be used in induction heating systems with semi-conducting frequency transducers. The technical result is achieved by the control method for frequency converter. The frequency converter includes serial connection of rectifier, filter and two-stroke bridge inverter. Each transistor of the inverter is bridged by the opposite diode. The transistors in the adjustable inverter rack are provided with parallel connection of switching capacitors. Opening and closing pulses are generated and alternatively supplied to inverter transistors. Besides the rate of switching capacitors charge is monitored from the voltage under 0.2 to a maximum level. The opening pulses with length defining the inter-switching period are supplied to the vertical non-adjustable rack transistors, while opening pulses with length defining output voltage value are supplied to the adjustable rack transistors. In addition at the moment of one transistor switching off in non-adjustable pair, the voltage on the adjacent switching capacitor is monitored. If the measured voltage exceeds 0.2 from the maximum level, the length of opening pulses in adjustable transistor pair is reduced at the next period of frequency converting. All transistors are switched on by the signal coming from current sensor at the moment when loading current crosses the zero point as a result of output frequency adjustment.

EFFECT: favourable transistor switching, ie reduction of total commutation losses, increase of converter power factor while ensuring safe recharging of damping capacitors within all ranges of frequency converter control.

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