Research To Reduce EMI Level Of DC/DC Boost Converter Using Current Control Methods

On the base of analyzing the chaotic behavior and Electric Magnetic Interference (EMI) phenomena in the DC/DC Boost converter, we have designed a new type of DC/DC Boost converter which working in chaotic switching state and also depressing EMI on the base by peak value current control. Theory analysis, computer simulation and circuit experiment demonstrated that, this kind of converter which working in chaos, compared with the converter which working in periodic state, can depress EMI a great deal. The main work of this paper is presented as follows:1. Having summarized all kinds of methods that had been used to depress EMI and ameliorate EMC of switched-mode power supply. Analyzing the limitation of tradition methods, we present the thought that using chaos control to reduce EMI of switch-mode power supply.2. Regards DC/DC Boost converter as a research object, we have gone deep into high frequency harmonic interference in the converter which working in constant frequency state and chaos switching state. Drawing a conclusion that the DC/DC Boost converter working in chaos state and it depress EMI level in by changing the combination parameters control and especial introduce peak value current control.3. In order to validate the effect of the peak value current control method and working in chaos state of open-loop DC/DC Boost Converter, we have designed an open-loop DC/DC Boost converter and have done circuit experiment. Analyzed and compared by experiment among new type (with maximum-minimum current limited control) and prototype (only with maximum current limited control) and constant frequency controlled DC/DC Boost converters, results demonstrated that it did have obtained definite effect in depressing EMI in the new type converter which working in chaotic switching state.4. On the base of new type of open-loop DC/DC Boost converter, we have designed a new type of closed-loop DC/DC Boost converter with voltage feedback and analyzed the principle of voltage stabilization of closed-loop circuit. Theory analyzing and PSPICE simulation demonstrated that, the principle of voltagefeedback presented in the paper, which can depress EMI by peak value current control and also keep output voltage stabilization. So an important step have been made in practically in depressing EMI of using chaos control.