Abstract:
Background Stepper motor driver is the main equipment of the cabinet of Absorption Sphere Shutdown System of HTR-PM, which can control the stepper motor to act according to the preset value, if it works abnormally due to the influence of interference, it will cause the stepper motor to run unexpectedly, which may cause the risk of the absorption sphere falling or refusing to fall by mistake and affect normal operation or nuclear safety of Nuclear Power Plant. Purpose The stepper motor driver adopts pulse width modulation(PWM) technology, accepts the weak current pulse instruction, converts the input 220VAC rectification into direct current(DC), and then inverts and modulates it into a high-voltage pulse signal to control the rotation angle and running speed of the stepper motor, and the output of pulse width modulation contains a large number of high-order harmonic components, which causes pollution and impact to the power grid and grounding system, and causes interference to the weak current control signal in the system and causes abnormal operation of the stepper motor. In this project, the stepper motor driver is not only the source of interference, but also the object of interference, and there are inherent difficulties in the anti-interference design, through research and analysis, a scientific and reasonable anti-interference scheme is formulated, which effectively reduces the pollution and impact of the power grid and grounding system caused by the PWM mechanism, and avoids the abnormal operation of the stepper motor driver. Methods Through theoretical calculations and practical tests, this study thoroughly studied the transmission path, mechanism and influence degree of interference caused by PWM, and designed customized optoelectronic isolation equipment. Dedicated reactor and filter are arranged on the corresponding interference source transmission path, which effectively blocks the interference propagation and suppresses the influence of interference, which conforms to the unique working
environment of the cabinet of the absorption sphere shutdown drive mechanism. Results The anti-interference design scheme of the cabinet project of the absorption sphere shutdown drive mechanism effectively suppresses the impact of interference on the system, ensures the accurate and stable operation of the stepper motor driver, and realizes the angle deviation of the stepper motor within 1°for every 20*360° operation, which effectively prevents the risk of malfunction of the stepper motor and improves the reliability of the system operation. Conclusions This research scheme has a good guiding significance for the anti-interference design of various control systems of the same type, and has certain promotion significance.