[Abstract] This article details the issue of personal safety in high voltage testing, proposes the application of remote control technology in high voltage testing, and provides a more detailed solution. [Keywords] Remote control; high voltage testing; microcontroller; stepper motor High voltage testing poses great dangers to personnel and equipment. In traditional high voltage testing, the transformer is adjusted manually to gradually increase the voltage from zero to high voltage. When the transformer malfunctions or is operated improperly, the operator may be struck by high voltage, with unimaginable consequences. If the transformer can be controlled remotely to gradually increase the voltage from zero to high voltage, it will greatly help ensure personal safety. [IMG=High Voltage Device Block Diagram]/uploadpic/THESIS/2008/1/2008010809532736308H.jpg[/IMG] 1. Composition and Working Principle of the Device In order to control the transformer remotely, the entire device can be divided into three parts, as shown in Figure 1. (1) Generation and Reception of Control Signals According to the experimental requirements of high voltage testing, the required control signals are generated and sent to the microcontroller for processing. (2) Stepper motor pulse signal generation and voltage regulation section: The microcontroller generates corresponding pulse waves according to different control signals, drives the stepper motor to rotate forward or reverse, thereby driving the voltage regulating transformer to generate voltage boosting and voltage reduction processes. (3) High voltage power generator: The 50Hz power supply is converted into the high voltage power required for high voltage testing using power electronics technology. The first and second parts are mainly introduced here. 1.1 Control signal generation and reception section: The signal transmission and reception section is divided into two parts. (1) Infrared remote control transmitting circuit: The principle of the transmitter is shown in Figure 2. IC1 (CD4067) encodes the input state into 8421 BCD code and outputs it. IC2 (MC145026) compresses the BCD code sent by IC1 and outputs the encoded information serially through pin 15. The oscillation circuit composed of IC3 completes the modulation of the encoded information output by IC2, and after amplification, it is transmitted through the infrared emitting tube SE303. [IMG=Infrared Remote Control Transmitter Circuit Diagram]/uploadpic/THESIS/2008/1/2008010809533323147M.jpg[/IMG] (2) Infrared Remote Control Receiver Circuit The receiver circuit consists of a light-emitting diode PH302, a remote control signal receiving integrated circuit CX20106A, and an MC145027, as shown in Figure 3. CX20106A is a bipolar integrated circuit used as a remote control signal receiving circuit in an infrared remote control system. It consists of a preamplifier, a limiting amplifier, a band filter, a peak detector, and a waveform shaping circuit. MC145027 converts the serial signal output from pin 7 of CX20106A into a parallel signal output for the microcontroller to query. [IMG=Infrared Remote Control Receiver Circuit]/uploadpic/THESIS/2008/1/2008010809533771822S.jpg[/IMG] 1.2 Generation and Voltage Regulation of Stepper Motor Pulse Signals The voltage regulation process of the voltage regulating transformer in this device can be done manually or by driving a stepper motor. A stepper motor is a commonly used actuator. Its working principle is to control the current in each phase coil to make the stepper motor rotate in steps. Its input is a countable pulse, which directly receives digital signals from the computer, and the output is the angle of motor rotation. The stepper motor control system mainly consists of three parts: stepper motor, controller, and driver. In recent years, the MCS-96 series microcontroller has been introduced. Its good anti-interference capability provides an ideal model for stepper motor control systems. The 8098 microcontroller receives commands from the remote control and processes them accordingly, through high-speed output ports HSO.0, HSO.1, and HSO. 2. Output the pulse signal required for the stepper motor to rotate, and connect it to the three phases A, B, and C of the stepper motor through an inverter, optocoupler, and driver respectively to control the rotation of the stepper motor. (1) Software design Since the parameters of the controlled object stepper motor are different and the voltage regulation requirements of the voltage regulating transformer are different, no specific program list is given in the software design. Only three main program flowcharts are given, as shown in Figure 4. The specific explanation is as follows: ① The stepper motor adopts a three-phase double three-beat working mode in the program. When the current is AB→BC→CA→AB, the stepper motor rotates forward; when the current is AB→CA→BC→AB, the stepper motor rotates in reverse. ② The remote control can flexibly control the forward and reverse rotation of the stepper motor. That is, each time the control button on the remote control is pressed, the stepper motor can rotate forward or reverse by a certain angle, so as to achieve the purpose of adjustable output voltage of the high voltage power generator. ③ In the main program, the microcontroller first queries the input signal. When it is a boost command, it switches to the boost subroutine; when it is a buck command, it switches to the buck subroutine. ④ In order to make the stepper motor rotate continuously, the stepper motor status bit AL is set in the program. This status bit must be checked before the stepper motor rotates. (2) Adjustment of high voltage power supply In the high voltage test, the basic requirements for voltage regulation are: ① The voltage regulation should start from zero, be uniform and smooth, and the change of each voltage level should be very small. ② The voltage rise rate can be relatively fast in the first 75% of the discharge voltage, but in the last 25%, the voltage rise per second should be controlled to not exceed 2% of the discharge voltage. ③ The voltage waveform output by the voltage regulator should be kept as a sine wave. ④ The voltage regulation should be in a stable working state. [IMG=Software Flowchart]/uploadpic/THESIS/2008/1/20080108095341706635.jpg[/IMG] By controlling the rotation angle and speed of the stepper motor, the sliding contact of the secondary voltage regulator is driven, and the position of the sliding contact is changed, thereby changing the number of turns of the secondary winding, so that the output voltage is adjustable and meets the voltage regulation requirements in high voltage tests. 2 Conclusion Applying remote control technology to high voltage testing does not require much change to the traditional high voltage testing device, and the technical implementation is not complicated. It only requires adding a control signal generation and receiving circuit and a stepper motor pulse signal generation circuit. This will effectively ensure personal safety during operation, and at the same time make the voltage regulation process more convenient, safe and reliable. Of course, other problems will be encountered in practice, which need to be further improved in future work. [References] [1] Zhang Renyu. High Voltage Testing Technology [M]. Beijing: Tsinghua University Press, 1982. [2] Kang Huaguang. Fundamentals of Electronic Technology. 3rd Edition [M]. Beijing: Higher Education Press, 1988. [3] Liu Fuhua. Principles and Applications of 8098 Microcontroller [M]. Beijing: Tsinghua University Press, 1991. [4] Pan Xinmin, Wang Yanfang. Practical System Design of Single-Chip Microcomputer [M]. Beijing: Posts & Telecom Press, 1992.