All digital input and output ports of the inverter are isolated by photocouplers. In addition to photocoupler isolation, transformer isolation is used for the trigger pulse output circuit of only thyristor to prevent reverse interference of higher voltage in the main circuit. The 01 circuit is also used to improve its anti-interference ability. In order to ensure the normal operation of the floating ground of the computer, the ground wire of the analog input port should also be isolated from the ground wire of the computer. Although the use of isolating amplifiers can realize the isolation of internal and external ground wires, due to the use of transformer coupling technology in such amplifier modules, the anti-interference ability is limited. Control failure. For this reason, before entering the microcomputer after the analog quantity is converted into a digital quantity, a photocoupler is used to isolate each digital quantity.
Because the optocoupler is a current-type device, it has a better inhibitory effect on the narrow peak pulse interference signal, and can obtain better anti-interference ability and higher conversion accuracy. Power supply anti-interference: The power supply of the microcomputer adopts the power supply mode of ferromagnetic AC voltage stabilizer, super isolation transformer, two-wire low-pass filter, and anti-interference type switching power supply for microcomputer. Tests show that this system has good anti-interference performance, which can ensure that the microcomputer is not disturbed by the AC power supply. The power supply of the peripheral circuit is led out from the AC voltage stabilizer and realized by another super isolation transformer, preventing the connection between the peripheral circuit and the microcomputer. mutual interference. Other anti-interference measures include: signal input filter network, digital filter program, trap program, use of integrated circuits, separate wiring of power lines and control lines, and shielded lines for computer signal lines.
