Abstract: This paper introduces the application of AC variable frequency speed control technology in ship navigation control systems. It describes a system using an Intel 8751 microcontroller as the core, supplemented by corresponding peripheral hardware circuits, to achieve real-time control of the output frequency and three-phase output phase sequence of an AC motor inverter, ultimately enabling monitoring of the ship's navigation attitude. This control method is simple in structure, convenient to control, and has good performance, making it a highly suitable electric propulsion system for medium and small-sized ships. Keywords : AC variable frequency speed control technology; microcontroller; navigation control console 1 Introduction Ship propulsion mainly falls into two categories: Firstly, mechanical transmission propulsion systems; secondly, electric propulsion systems. Ships using electric propulsion systems are often used for tourist attractions, such as yachts and cruise ships sailing on rivers or lakes, due to their low noise, low pollution, maneuverability, ease of operation, and ease of maintenance. However, analog control electric propulsion systems composed of discrete components suffer from a series of problems, such as long design cycles, numerous connection lines, many solder points, complex installation and debugging, and difficulty in maintenance. Furthermore, the control precision is not high. Introducing a single-chip microcomputer-controlled AC variable frequency speed regulation electric propulsion system not only overcomes many problems existing in analog control systems, but also has superior control performance. [b]2 System Introduction 2.1 System Design Concept[/b] This system uses the ship's own diesel generator set outputting 50Hz, AC380V AC power as the power source. It uses an Intel 8751 single-chip microcomputer as the core, supplemented by corresponding control programs, to remotely control the output frequency and phase sequence of two AC variable frequency speed controllers, respectively driving the ship's left and right asynchronous motors to rotate their respective propellers. Through different combinations of the left and right propeller directions and speeds, the ship can perform various navigation actions such as forward, backward, and turning at different speeds. The system also monitors the main operating parameters of the ship in real time, and uses pointer instruments and LED digital tubes to dynamically track and display the propeller speed. Abnormal situations occurring during the operation of the electric propulsion system are promptly detected by audible and visual alarms to alert the ship's operators. Automatic shutdown can be implemented when necessary to ensure the ship's navigation safety. In the event of a control system malfunction, the ship's navigation can be maintained by operating the operating condition selection switch, emergency control knob, and backup rudder on the control console. [b][align=center]For more details, please click: Application of AC Variable Frequency Speed ​​Control Technology in Ship Navigation Control Systems[/align][/b]