Principle of High Power Voltage Regulator
High-power regulated power supply circuit consists of = l2V power supply circuit, voltage detection control circuit, over-voltage protection, l2V power supply circuit consists of regulator transformer T's W4, W5 windings and rectifier diodes VDl-VD4, filter capacitors Cl, C2. The voltage detection control circuit consists of resistors R-R7, potentiometers RPl, Rm, voltage regulator diode VS, capacitors C3, C4 and operational amplifier IC (Nl-N3). The overvoltage protection circuit consists of N3 inside the IC, transistor V3, resistor Rl2 and relay K. The automatic voltage regulation circuit consists of resistors R8-Rll, transistors Vl, V2, DC motor M, sliding contacts and the Wl-W3 windings of T. After connecting the transmission end of the AC high-power regulated power supply with the mains, an induced voltage is generated on the W4 and W5 windings of T. This voltage is rectified by VDl-VD4 and filtered by Cl and C2 to provide 士l2V unstable working voltage for IC and Vl, V2, etc. The +l2V voltage has other functions. After Rl-R3 voltage divider, VS voltage regulator, respectively, for the inverted input of Nl-N3 to provide reference voltage; over-voltage protection circuit Shen K and V3 to provide working power; after R4, RP2, R6 voltage divider, for the positive-phase input of Nl and N2 to provide a detection voltage; after R7, RPl, R5 voltage divider, for the positive-phase input of N3 to provide a detection voltage.
Nl-N3 compare the detection voltage at the positive-phase input with the reference voltage at the inverted-phase input, and use the resulting error voltage to control the automatic voltage regulation circuit.
When the mains voltage is normal, the output voltages of Nl and N2 are OV, Vl and V2 are in the cut-off state, and the motor M does not work.
When the mains voltage is low, Nl and N2 output a low level, making V2 conductive and Vl cutoff, M rotates counterclockwise, driving the sliding contacts to move through the sliding wall arm, and contacting with the corresponding voltage taps of T. (A total of 21 voltage taps are set up in the Wl and W2 windings of T, with the voltage adjustment range of 5V for each gear), and boosting the output voltage through the W2 windings of T. When the output AC voltage rises to 220V, V2 cuts off and M stops. When the mains voltage is high, both Nl and N2 output a high level, making Vl conductive and V2 cut-off, M rotates clockwise, driving the sliding contact to move through the sliding arm, contacting with the corresponding voltage tap of T, and lowering the output voltage through the Wl winding of T. When the output AC voltage drops to 220V, Vl cuts off and M stops rotating. When the mains voltage is higher than 260V, N3 outputs a low level because the voltage at the positive-phase input terminal is higher than that at the inverted-phase input terminal, so that V3 cuts off, K releases, and its normally-closed contact connects to the output circuit of AC voltage. When the mains voltage is 160-260V, N3 outputs a high level because the positive-phase input voltage is lower than the inverted-phase input voltage, making V3 conductive, K absorbed, and its normally closed contact disconnected, thus ensuring that the load (electrical appliances) will not be damaged due to overvoltage.
