Abstract: The opening and closing process of an elevator door is a variable speed motion process, requiring speed control of the elevator door system's drive motor. This paper proposes an elevator door operator variable frequency speed control system based on the high-performance single-chip microcomputer 87C196MC, with the power drive circuit using the dedicated integrated circuit IR2130 for driving MOSFETs. The method of controlling elevator door operator operation based on PWM technology is analyzed. By integrating the AC frequency converter and drive controller of the door system motor into a single unit using a single-chip microcomputer and a dedicated power drive integrated circuit, a highly reliable, flexible, low-cost, and compact elevator door operator controller is obtained. Keywords: Frequency converter; Sinusoidal pulse width modulation; Elevator door operator system 1. Introduction The elevator door operator system is a very important subsystem of the elevator. The performance of the door operator system directly affects the normal operation of the entire elevator system. Therefore, the design, development, and manufacturing of the door operator system is a key aspect of elevator system design, development, and manufacturing. From a control perspective, the research focus should be on how to apply advanced variable frequency speed control technology to the door operator system to enable it to operate efficiently, economically, and reliably. In current engineering practice, there are two main methods for variable frequency speed control of AC motors: Sinusoidal Pulse Width Modulation (SPWM) and Space Vector Pulse Width Modulation (SVPWM). The basic principle of SPWM is as follows: when the fundamental wave (sine wave) is higher than the triangular carrier wave, the corresponding switching device is turned on; conversely, when the fundamental wave is lower than the triangular carrier wave, the corresponding switching device is turned off. The generated PWM pulse sequence serves as the drive control signal for the inverter's power switching devices. This system uses the SPWM modulation method and employs the Intel 87C196MC, a 16-bit high-performance microcontroller, as the core control chip. The PWM waveform generation module of the 87C196MC generates PWM signals to drive the power circuit, thereby causing the door operator to run according to a pre-set operating curve. For details, please click: A New Type of Elevator Door Operator Control System