Research On Buck AC Chopper Regulator

AC chopper, which is usually regarded as voltage regulator, is kind of device to transform one type of AC to another. With changing the amplitude of the AC, power can be supplied to alternating load or power system. As an important part of power electronics, it has been paid much attention to. Using bidirectional power switch, on the guard of simple practical DC/DC topology, bidirectional power conversion can be realized.This paper takes Buck AC chopper converter for example. It describes the change of bidirectional power switch and suitable applications, analyzes the work principle of the converter under steady-state and gives a feasible idea to the current commutation of the switch. Furthermore, several regulations are put forward on the general structure parameters.With thorough theory, the converter uses the switch cycle current equalized method to establish fair more precise equivalent circuit model and alternating small signal model. On the base of these models, the transfer function model among the system's crucial variable is given. Meanwhile, the average current control scheme is adopted here, which use current control in the inner loop and voltage control in the outer loop. As for the parameters of the two loops, it uses the method of frequency compensation method through Bode chart in the frequency field.Combined with the designed parameters , the whole chopping converter simulation model is established with matlab simulink. The simulation result indicates that the designed parameter of the compensation device is reasonable, and the relationship between the input filter and the THD of input current is found out. A pair of parameters of the input filter is determined for the time being. The result of the simulation supports the hardware's design very well. The chip called DSP F2812 which is produced by Ti is used to realize controlling the whole test appliance under the control programs. Through the experiment on the device, it proves that Buck AC chopping converter's hardware structure is simple and easy to realized; its control software is practical and of good reliability. Wave form of the final output voltage displays favorable and has high precision.