Single-chip microcomputer control technology used in air conditioner power-on delay start protector-EEWORLD

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introduction

　　In some places where the power supply voltage is unstable, the air conditioner is often used after the power is cut off and then the power is immediately restored. It is necessary to manually restart the air conditioner and set the working mode and status repeatedly. The more serious situation is that it is easy to burn the compressor. In order to solve this problem, the author designed an air conditioner power-on delay start protector, which can solve this problem well. When the air conditioner power-on delay start protector is used every time a call comes, the control circuit of the air conditioner is powered on for 3 to 5 minutes. The method is to connect an electronic switch controlled by the air conditioner power-on delay start protector in parallel at both ends of the air conditioner start button switch to automatically control the air conditioner button switch to start the machine. In addition, according to the function and working principle of the reset circuit, the role of the reset circuit in the air conditioner control circuit is manually cancelled. In this way, it is only necessary to set the working mode and status for the first time when the air conditioner is powered on. After repeated restarts, the air conditioner can be powered on and run according to the working mode and status set for the first time. In places where the power supply voltage is unstable, the air conditioner power-on delay start protector is used. When the air conditioner is powered off, no matter when the power comes back on, the compressor will not be burned out, and there is no need to manually restart the air conditioner and set the working mode and status repeatedly.

　　Hardware circuit

　　The power supply of the air conditioner and the circuit of the air conditioner power-on delay start protector are powered on. At this time, the U1 single-chip AT89C51 in the delay start protector circuit (Figure 1) is powered on, the reset circuit is reset, and the AT89C51 operates normally according to the designed program. The output of pin 21 of U1 maintains the "0" level for 5 minutes, and the transistors in the power drive circuit of pins 7 and 10 of the U2 seven-unit power drive circuit 2003A are cut off, and the pin 10 of U2 outputs the "1" level, the internal light-emitting diode in the U3 light-controlled thyristor MOC3020 is cut off, the light-controlled bidirectional thyristor is cut off, the trigger circuit of the Q bidirectional thyristor has no trigger control signal, Q is cut off, and the electronic switch controlled by the air conditioner delay start protector connected in parallel at both ends of the key switch is disconnected. The control circuit of the air conditioner cannot be started because it is not powered on, and the light bulb indicating the power-on start state of the air conditioner does not light up.

Figure 1 Single-chip controlled air conditioner power-on delay start protector circuit

　　When the power-on delay time of the air conditioner delay start protector is 5 minutes, at this time, the 21st pin of U1 outputs the "1" level, and the power drive circuit of the 7th pin and the 10th pin of U2 works, the 10th pin of U2 outputs the "0" level, the light-emitting diode inside U3 turns on and emits light, the light-controlled bidirectional thyristor turns on under the light, and generates a trigger control signal to the trigger circuit of Q. The Q bidirectional thyristor turns on under the action of the AC 220V or 380V, and the electronic switch controlled by the air conditioner delay start protector connected in parallel at both ends of the key switch is closed, which is equivalent to the key switch of the air conditioner being closed, and the air conditioner is powered on and started to work. At the same time, the light bulb indicating the power-on status of the air conditioner lights up. After 3 seconds, the 21st pin of U1 outputs the "0" level again. At this time, the state of the air conditioner delay start protector circuit is the same as the previous situation where the 21st pin of U1 outputs the "0" level. The power-on start of the air conditioner is completed. After the power-on start of the air conditioner is completed, it enters the normal working state. The above has completed the working process of the air conditioner power-on delay of 5 minutes. When the power is off and then on again, the above working process will be repeated to achieve the function of the air conditioner power-on delay start protection. [page]

　　Program design

　　Here are the subroutines for delaying 1S and delaying 1 minute

　　Subroutine with 1S delay

　　YSIS: MOV R5, #100; delay 1 second

　　D1: MOV R6, #20; delay 10 ms

　　D2: MOV R7, #248;

　　HERE: DJNZ R7, HERE;

　　DJNZ R6, D2;

　　DJNZ R5, D1

　　RET

　　
　　Delay 1 minute subroutine program

　　Delay: MOV R4, #60; Subroutine delay 60 seconds

　　Do: MOV R5, #100; 1 sec

　　D1: MOV R6, #20; 10 ms