Abstract : Pump-controlled load sensing systems are widely used due to their energy saving and high efficiency. This paper starts from the theoretical flow formula of hydraulic pumps and controls the flow by changing the pump speed according to the load signal, enabling the hydraulic fixed displacement pump to achieve variable flow. Based on this variable flow principle, a pump-controlled load sensing system composed of an AC motor controlled by a frequency converter and a fixed displacement pump is designed. The mathematical model of the AC frequency converter motor pump-controlled load sensing system is analyzed, a control scheme is proposed, and simulation results are given. Keywords : Load sensing system; Frequency converter; Hydraulic system 1 Introduction A pump-controlled load sensing system is a closed-loop system with differential pressure feedback that realizes the hydraulic pump's follow-up control of load pressure under flow command conditions. There are many methods to implement a pump-controlled load sensing system, but the starting point is the same: how to achieve optimal flow control. Therefore, if you want to change the flow, you can do so by changing the pump's displacement and speed. There are two methods: one is to change the pump's displacement according to the load signal to change its flow, and the other is to change the pump's speed according to the load signal to achieve the purpose of flow control. The emergence and maturity of AC variable frequency technology provides us with a new approach to regulating the output flow of hydraulic pumps. This involves using variable frequency technology to enable traditional hydraulic fixed displacement pumps to achieve pump-controlled load sensing control. Its main characteristics are high-efficiency driving performance and good control characteristics, thus possessing significant theoretical and practical value. 2. Working Principle of the New Pump-Controlled Load Sensing System Current pump-controlled load sensing systems utilize pumps with fixed angular velocity and variable displacement. The new design uses a pump with fixed displacement and variable angular velocity, achieved by driving a motor with a variable frequency drive. Its advantage lies in simplifying the overall system structure. However, this system also has a drawback: the requirement to use a variable frequency drive. [b][align=center]For more details, please click: Research and Simulation of Pump-Controlled Load Sensing System Based on Variable Frequency Motor[/align][/b]