Key Technology Research On High Frequency And High Voltage Power Supply

Many devices based on X-ray are widely used in major research areas such as defense automotive,chemical,metallurgy,steel, materials and so on. With the rapid development of equipment related to X-ray, the reliability,stability and accuracy of the power supply should reach a higher level.The critical point we faced in high voltage power supply area is to improve its accuracy and stability.The present paper lays emphasis on improving the accuracy of the X-ray power.Voltage doubing circuit and filament supply in the process of design and production of high frequency and voltage power supply is selected as the research object.A high-voltage silicon stack simulation model is established via doubling circuit simulation using Pspice,then comparing the output ripple and loading ability of Schenkel, CW circuits and relevant improved circuit, studying deeply the output characters of different input signals,the impact of and capacitance and diode on the double circuit. Via the simulation, the discoveries are as follows:capacitance at the output position has the largest influence on the output ripple the influence of capacitanceat the non-output position on the output ripple in doubling voltage circuit is limited;however,steady-state time of doubling voltage circuit is largely affected by the capacitance at the non-output position.Besides,theoretically,in CW doubling voltage circuit the voltage value capacitance bears twice times the peak value of input AC voltage,however,due to the existence of voltage drop of doubling circuit under the circumstance of load,the voltage back-level bears is far less than the one front-level bears,so when designing doubling voltage circuit we can select different values for the two kinds of capacitance,which one has more impact on the output,and the other not,and select different withstanding voltages for the front and back level to lower output ripple,improve loading capacity,decrease size and reduce cost.This paper researches X-ray filament power supply.The filament power requires a sinusoidal AC voltage whose output peak voltage value is 3-10 V, whose frequency is400 Hz and whose power is under 30 W.So SPWM is selected to control half-bridge inversion as the power topology,for the unbalanced voltage of DC dividing capacitance in the half-bridge inversion based on regular double closed-loop control method of voltage and current, without adding circuit components,add sin AC output signals with DC component to modulating wave by low pass filter or integration element with DC component as feedback signal, theoretically absolutely eliminate the problem of the unbalanced voltage of DC dividing capacitance.During specific design processing,this paper adopts digital control scheme to sample DC dividing capacitance midpoint voltage,then via AD convention add the sampling value into control loop circuit to eliminate DC capacitance bias voltage. At last through experiment,the scheme reaches predicting result.