The Research Of AC Electric Dynamometer Control System

Recently, with the rapid development of the domestic automotive industry andthe stricter environment protection policy, the performance testing for generator hasmore stringent requirements. With the advantage of easily controlled test conditions,convenient collected and managed parameters and the high measuring precision,AC Electric Dynamometer System can simulate the mechanical load at runtime ofthe generator installed on the vehicle in the lab, At present, there is a big gap in thisfield at home and abroad. Thus, the research for the high performance AC ElectricDynamometer control system can do well for the development of the domesticDynamometer and has the vital practical significance. The study includes thefollowing aspects.The hardware and software of AC Electric Dynamometer control system aredesigned with the comprehensive study of the basic structure, working principle andmathematical models of the dynamometer. And its overall program is stillestablished.In the hardware design, taking Siemens S7-200PLC as its core controller, thedata acquisition and processing circuit diagrams and the specific schematic aredesigned to detect the rotational speed and torque. Design scheme ofcommunication and circuit diagrams are used to PLC connecting the various parts.MODBUS communications achieves communication between the PLC and inverter.Free port communications achieves communication between the PLC and touchscreen. Ethernet model achieves communication between PLC and PCIn the software design, taking PLC as the software development platform,using computer and human-computer interaction techniques, real-time controlsubroutine and human-computer interaction subroutine are designed. According tothe requirements of AC Electric Dynamometer control system, using modularprocessing, complete the software design of the system. Filtering methods isaveraging method after removing the maximum and minimum. Control strategy isthe nine-point control-PID control.The dynamometer system experiments have been made on the states of no-load and generate electricity. During the no-load test, experiments have the rotationalspeed signal tests and the torque signal tests. During the generate electricity test,experiments have the given a constant rotational speed to dynamometer-changingtorque of measured motor and the given a constant torque to measured motor-changing rotational speed of dynamometer. Large number of experimental resultsshows that AC Electric Dynamometer control system using nine-point control-PIDcontrol can achieve better control effect, and meet the requirements of theperformance test of generator.The system can achieve the control methods which are rotational speed control,torque control, constant torque in rotational speed control mode and constantrotational speed in rotational torque control mode. With a high stability, this systemhas simulated the mechanical properties of the measured motor. It has been initiallycompleted the research and analysis of generates electricity of dynamometer.