Research On Experimental Methods Of Towed Systems Based On Fully Controllable Electrical Environment

In this paper,the experimental method of the back-to-back drive system is studied,and a comprehensive experimental platform structure is proposed,which can realize the speed regulation functions of the dynamometer,the synchronous generator,the doubly fed generator and the asynchronous motor.On the other hand,the platform also has the completely controllable function of the electrical environment.For example,the voltage amplitude and frequency can be controlled,the voltage balance and imbalance can be achieved.Firstly,this paper describes the composition and function of the whole back-to-back drive system including the towing unit,electrical system and control system.The utility model is composed of a winding asynchronous motor,a three-phase asynchronous motor and an encoder arranged on the rotating shaft.The electrical system consists of a voltage source converter and a voltage and current acquisition circuit.The control system consists of a host computer and a Universal real-time experiment platform(UREP).The conditions and methods for the realization of various motor experiments are described.Secondly,the control strategy and hardware implementation of the fully controllable electric environment are determined.Structure of back-to-back voltage source converter is used.The control strategy of constant DC voltage constant reactive power(Vdc/Q)is used to the rectifier,and The control strategy of voltage amplitude and frequency(V/F)is used to the Inverter.The simulation model is built in Matlab/Simulink,and its simulation and verification are carried out.In the case of unbalanced voltage drop,it is difficult to realize the effective control of AC components for proportional integral controller,so the proportional integral resonance(PIR)is used to solve the problem in this paper.Aiming at the problem that the software phase locked loop(SRF-PLL)based on the traditional synchronous reference frame can't provide accurate voltage reference,a resonant PLL is used to solve the problem.In addition,the voltage source converter in this paper is designed independently,which is convenient for the secondary development of the system.and the specific structure is "DSP+IGBT".Controller is mainly run in the internal SPWM modulation program,which produces PWM wave control IGBT switching devices.Therefore,the control level signal is converted to the power level signal.The main function of host computer is to issue instructions and monitor the operation of the whole system.The main function of the Universal real-time experiment platform is to run the real-time control model,and generate the PWM reference three phase modulation signal.Finally,the above-mentioned system is tested,and the experimental results show that the integrated experimental platform of machine designed in this paper can realize its function better.