The power frequency AC power supply is stepped down， rectified and_filtered by the transformer to become a stable DC power. The rest of the figure is voltage regulation， achieving voltage regulation.
Power supply working principle diagram
Power supply working principle diagram
The control part used. After the power supply is connected to the load， the output voltage is obtained through the sampling circuit， and_the output voltage is compared with the reference voltage. If the output voltage is less than the reference voltage， the error value is amplified by the amplifying circuit and_sent to the input end of the regulator， and_the output voltage is increased by the regulator adjustment until it is equal to the reference value;_if the output voltage is greater than the reference voltage， the regulator is passed. Reduce the output.
The regulator circuit consists of a power supply circuit， a voltage detection control circuit， and_overvoltage protection， as shown in the figure. The power supply circuit is composed of the W4 and_W5 windings of the voltage regulating transformer T and_the rectifier diodes VDl-VD4 and_the filter capacitors Cl and_C2. The voltage detection control circuit is composed of a resistor R-R7， a potentiometer RP1， Rm， a Zener diode VS， capacitors C3， C4， and_an operational amplifier integrated circuit IC (Nl-N3). The overvoltage protection circuit is composed of N3 inside the IC， transistor V3， resistor Rl2， and_relay K. The piezoelectric regulating circuit resistor R8-R11， the transistors V1， V2， the direct current motor M， the sliding contact and_the W1 - W3 winding of the T are composed. When the large end of the AC voltage regulator is connected to the mains， an induced voltage is generated on the W4 and_W5 windings of T. The voltage rectified by VDl-VD4 and_Cl， C2 filtered to provide persons l2V unstable operating voltage of the IC and_the Vl， V2 and_so on. The +l2V voltage has other effects. After Rl-R3 partial voltage and_VS voltage regulation， the reference voltage is provided for the inverting input terminals of Nl-N3 respectively;_the working power supply is provided for K and_V3 of the overvoltage protection circuit;_after being divided by R4， RP2 and_R6， The detection voltage is supplied to the non-inverting input terminals of N1 and_N2;_after being divided by R7， RP1， and_R5， the detection voltage is supplied to the non-inverting input terminal of N3.
Nl-N3 compares the detection voltage of the large-phase positive-transmission terminal with the reference voltage of the large-end inverter， and_uses the generated error voltage to control the automatic voltage regulation circuit.
When the mains voltage is normal， the output voltages of N1 and_N2 are OV， Vl and_V2 are both in the off state， and_the motor M does not work.
When the mains voltage is low， Nl and_N2 output a low level， so that V2 is turned on， V1 is turned off， M is rotated counterclockwise， and_the sliding contact is driven by the sliding wall arm to contact with the voltage tap corresponding to T (W of T1) A total of 21 voltage taps are set in the W2 winding， and_the voltage adjustment range of each gear is 5V. The output voltage is boosted by the W2 winding of T. When the output AC voltage rises to 220V， V2 is cut off and_M stops. When the mains voltage is high， Nl and_N2 both output a high level， so that Vl is turned on， V2 is turned off， M is rotated clockwise， and_the sliding contact is moved by the sliding arm to contact the voltage tap corresponding to T， through T Wl windings to reduce the output voltage. When the output AC voltage drops to 220V， Vl is cut off and_M stops. When the mains voltage is higher than 260V， N3 outputs a low level because the voltage of the positive phase input terminal is higher than the voltage of the inverting input terminal， so that V3 is cut off， K is released， and_the output circuit of the normally closed contact is connected to the AC voltage. . When the mains voltage is 160-260V， N3 outputs a high level because the voltage of the positive phase input terminal is lower than the voltage of the inverting input terminal， so that V3 is turned on， K is pulled in， and_its normally closed contact is disconnected， thereby ensuring the load. (Electrical appliances) will not be damaged by overvoltage. [3]
