Studies On AC Electrical Dynamometer And Its Control System

Recently, with the development of the domestic automotive industry and the stricter policy of environment protection, higher-level test technologies are required for the engine test. Aiming at the speed characteristics test, which is one of important test items of engine test, this paper proposes studies of AC electrical dynamometer and its control system. Based on the detailed analysis of operating principle and stability of the electrical dynamometer system, the paper chooses the tested engine, electrical dynamometer and load resistance etc. as research object, mainly studies the modeling of electrical dynamometer, the design of the hardware and software of the control system, as well as the control strategy and the armature reactor analysis of electrical dynamometer when the electrical dynamometer runs with pure resistive load. The development of the control system of the electrical dynamometer is also completed.In this paper, after discussing about the operating principle and the relations among the main torques of electrical dynamometer system, the stability conditions of the system function are analyzed. The electrical dynamometer model is constructed through coordinate transformation and Park equation. The armature reactor of electrical dynamometer is also explored in detail as it runs with pure resistive load. The elementary equation about electromagnetism torque is deduced, and the quantitative analysis of the load control of the system is also carried out. These steps have laid the base of load control strategy for the power-test system.As to the design of hardware of control system, taking industry control computer as its core, the design methods and practical used circuit diagrams are presented to detect the torque, rotation speed, current, voltage, etc. The design of the load resistance regulating and the excitation control system is also presented in detail, which is an important part of power-test control system. For the control strategy of the system, the regulation of cascade control is employed to control the load of power-test system, load resistance and excitation current. And the auto-tuning parameter Fuzzy PID control is applied to the closed-loop control of rotation speed; the corresponding algorithm is studied in detail. Finally, the softwareparts of the electrical dynamometer control system are realized by using Lab VIEW and VC++.A lot of experiment results show that the control system of electrical dynamometer, which is based on LabVIEW and Fuzzy-PID control, possesses satisfactory performance to meet the requirement of engine speed characteristics test.