Research On Main Circuit Of Power Converter Circuit With Open - Loop Dynamic Impedance Self - Matching Function

PWM (pulse width modulation) mode is most commonly used in modulation of power electronic converter technology.This way can make the power electronic equipment become smaller, lighter, higher conversion efficiency, but also has some disadvantages:First,the loss of switch devicees in the circuit are increasing as the PWM pulse frequency increased. The second,when it comes to current transformer load and the output short circuit in traditional methods, it mainly through quick break protection to prevent the failure of expanded, because of the variety of distributed parameter in the circuit, so when it is quick break protection, the interaction of the high current rate in Circuit and the line distributed inductance, the high voltage spike pulse could make the main power device breakdown and burned easily.Third, is constant power output characteristics of the traditional technology must rely on the current and voltage of double feedback to implementation,this put forward a very high request to the sampling rate and the speed of operation in digital feedback circuit, therefore, for high frequency waveform synthesis, the rate of a feedback loop for high-frequency constant power output waveform synthesis is a limiting factor. Forth, the pulse control mode in existing PWM converter technology, basically using pulse width continuously adjustable analog control, if using the control mode of digital signal directly, it will make the whole control process can be simplified.This paper gives the results of previous research commissioned by enterprise development projects.The requirement of the project is a kind of high performance requirements of underwater resources detection equipment, its core index requirement as follows:output waveform is a standard sine wave; continuous adjustable frequency range of40Hz-100KHz; load impedance4Ω～1000Ω continuously adjustable; within the frequency bands and the load impedance range required output power is constant1KW; and a full range of waveform distortion to less than1%. From the point related to retrieve, so far, it haven’t conform to the requirements of similar products in domestic. And under the condition of existing technology, using traditional methods is difficult to fully meet the requirements of the target. Based on the above technology present situation, around the target task to complete, this paper discusses the problems in existing technology, put forward and proved a theory called constant energy pulse frequency modulation mode, a new method of power converter, make the completed power converter system not only have the open loop dynamic impedance matching function, and compared with the conventional PWM converter circuit, with lower switching loss, only use ordinary fuse protection can ensure that the main power device is not damaged, it can realize broadband continuous variation under the constant power load from the matching, and the main switch devices can be completely controlled by digital signal directly, etc. Finally, by building hardware circuit experiment to verify the feasibility of the whole system, from the perspective of the experimental results of complete, the design has reached the goal request, and the final results prove the correctness of the theory and the feasibility of the implementation plan.First of all, the body part of this paper has carried on the brief introduction about power electronic converter technology, at the same time points out the PWM technology advantages and existing problems, then discusses the relevant basic knowledge on the project research, at the same time put forward the constant energy chopper bridge and constant power pulse Series synthetic waveforms theory and has carried on the detailed analysis and derivation of the theory, next is analyzed the actual circuit of the whole system, introduced the main circuit in the choice of a variety of devices in details. As the control circuit and control program in this paper is carried by xie hongling classmate of team members, so this part is illustrated in details in his paper, in this paper, it can only do a simple introduction. Finally, through the experiment of the whole system, combined with the experimental results and related waveforms to verified the feasibility of the system, and at the same time demonstrate the correctness of the theory.