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Medium Frequency Power Supply Control Part Characters:
(1) Control part includes: Power Supply, regulator, phase shift control, protective circuit, phase sequence self-adaption circuit, start figuring circuit, inverter frequency tracking, inverter pulse formation, pulse amplification, and pulse transformer. Core Parts use American made high-performance, high density, large-scale dedicated integrated circuit ASIC-2, makes all the interior circuit parts digitization, except regulator.
Rectifier flip-flop part doesn’t need any adjustment, and has high reliability, high pulse degree symmetry, strong anti-interference ability, and speedy reaction. With phase sequence self-adaption circuit, no need of synchronization transformer, when do field adjustment, no need of phase sequence adjustment, refer to synchronous work, only need to put the KP silicon controlled gate extreme line insert connection end on control board, then rectifier can be put into operation.
(2) The main circuit inverter bridge load is parallel resonant circuit composed of induction furnace and capacitor, set capacitor with same capacity to induction furnace return circuit, higher voltage, makes voltage reaches to 1500v when into furnace.
(3) Rectification part uses 3 phase bridge rectifier, control return circuit use digital touch screen circuit, with most advanced integrated circuit, good consistency pulse, strong anti-interference ability. Inverter uses sweep frequency style zero-voltage soft start, and set with repeat start circuit, which improves start reliability. When loaded quality factor equals to or larger than 2.5, start success rate can reach 100%. Frequency tracking circuit uses average value sampling, improves antijamming capability of inverter system. Besides, adds inverter theta angle automatic adjustment circuit and impedance regulator to inverter circuit, can reach largest power output no matter in which load situation, which reaches aim of time saving, power saving, and improves net test power factor.
(4) Regulator circuit part, uses medium frequency voltage, DC current double closed loop PI regulator, and double closed loop works when starting, reaches aim of system work steady.
(5) Protective circuit. There wouldn’t be any undesirable impact to system from power transmission, outage precedence of main circuit and control circuit, or operation worker’s misoperation. Detailed protection functions are: default protection, overcurrency protection, overvoltage protection, undervoltage protection, under water pressure, water-break protection. This system is with completed protection functions, acousto-optic alarm in any fault state appears, and also makes the device automatic stop working.
(6) Start method of medium frequency power supply is sweep frequency style zero-voltage soft start, means during power starting, load voltage and currency increases gradually from zero, so there is no currency impact to power system, there is also automatic repeat start circuit, avoids occasional start failure of power supply, make start success rate keeps 1000%. Frequency tracking circuit uses average value sampling, improves inverter antijamming ability. Key electric equipment components parameters is confirmed by computer simulation, and is proved by practice that it has higher exactness and reliability. All control circuit distributed in one print board, reduces faults caused of connectors bad contact.
IGBT serious Medium Frequency Power Supply