4kW Buck Converter Digital Control

With the development of economy,MH(Metal Halide)lamp has become one of main product in lighting industry.MH lamp has some merits such as high efficiency lighting,long life,small lighting volume,and well performance.However,with character of the time-variation and negative resistance MH lamp brings out the complex in control strategy and difficulty in research.Three-level-ballast can realize the steady operation of MH lamp,which Buck converter plays an important role.However,the research of controlling in MH lamp is fewer.On the other hand,the growth of digital signal process technology promotes Power Electronic.SCM,ARM,DSP,FPGA are widespread use of moter drive and switching power control.It is not only put the modularization and integration in power supply into practice,but increasing the reliablity and security.Based on the two reasons,it is proposed the digital control of Buck converter in MH lamp. The principle analysis is the analysis on analog control,and modeling the smaU signal. Afterwards,it is designes a DSP arithmetic and its relative parameter using the analog to digital method as to model a small signal.In frequency domain,the closed loop system is verfied by Pspice simulation,and programmed by DSP to make ballast run stable which is implemented by experiment.The content of this thesis are as fonow:1)Through reading a 1arge number of reference papers,it is summarizes the property of MH lamp and controlling,give out me simplified prototype and MH lamp electricity model．2)By using digital signal process methods,frequency spectrum of main circui is calculated in order to analyze the main point waveform.Furthermore,it (?) (?) analyzes the effect of output noise in DSP and method to filter out the noise．3)By analyzing the control mode of MH lamp in industrial area,an equiValent small signal modelis set up and the transfornl is obtained to decide the stability．Employing analog to digital method,a DSP control syStem is acquired to select the parameter of PI contr01．In this paper,a way to study the digital contr01 system is proposed．4)Quantization error call not be ignored in DSP programming．The effect of quantization error of input to output is calCUlated aRer remodeling PI cong011er by the theory of digital signal process．...