Research On Digital High Voltage Power Supply System Based On DSP

Digital high voltage power supply, which transforms power frequency into a special form of the power is a electronic equipment, it is widely used in many fields. Many high technology development, such as research of crop electrostatic effect in agriculture field and numeric imaging of X-ray for medical uses are required high voltage power supplies with high frequency and high power. With semiconductor technology, power electronics and control theory, the development of high voltage power supply by digital control has been widely attention. But now, low-cost, high-performance digital signal processor (DSP) controllers and high frequency switch power supply technology provide wide development space to digital high voltage power supply. The principle of phase-shift full bridge zero-voltage-switching (PS-FB-ZVS) converter and its digital control technology are proposed, the digital high voltage power supply system has been designed in hardware. With the development environment CCS for a platform and the digital phase-shift PWM control method, the development of the power system has been completed.Firstly, the paper has expounded the DC/DC converter. And then it has selected the topology of phase-shifted ZVS full-bridge which is suitable for this thesis, then expounded its basic principles and realization strategy of ZVS soft-switching. It also has focused on the working process of full-bridge inverter, the voltage and current expression are given as well. Secondly, the thesis has designed the main circuit topology which we selected, and gave the methods of parameters designing and calculation for main circuit, including the parameters designing of input rectifier filter circuit, high-frequency transformer and the times rectifier circuit. Finally, the paper has designed the whole power system hardware structure. With TMS320F2812of Texas instruments (TI) in America as a control core, the drive circuit, detection circuit, protection circuit and auxiliary power supply circuit have been designed at last.On the other hand, with the advent and development of microprocessor, there has been an increasing interest in digital control of switch mode power supply, instead of analog control. Digital control technology can make the control circuit simplify, and can greatly improve the anti-interference ability, the control flexibility and intelligence of system. Therefore, based on the dynamic analysis of the full-bridge inverter circuit, this paper introduces a digital control system, in which a DSP IC (TMS320F2812) is used as the core. The paper also presents a design method of an integral digital PI algorithem.Digital high voltage power supply system with CCS for development platform, it adopted a novel method which can generate digital phase-shifted PWM pulse based on the full comparision units of DSP. This method uses the two comparision units of DSP from the EV event management generating a four-way digital signal PWM waveform as a driver instead of analog control and the control is more flexible.Finally, the simulation and experimental debugging of the power system have been conducted. The result demonstrates that the correctness of the theory analysis and design, experimental results and waveform are given.