Research On Forward Active Clamping Voltage Mode Switching Power Supply

With the continuous development of personal consumer electronics,communication equipment and automotive electronics,designers are constantly optimizing the circuit structure of traditional non-isolated converters to improve their performance,while still innovating ideas to break through mode restrictions and actively exploring isolated converters Theoretical research and design practice.In this paper,the main problems of mainstream switching power supply,such as small input power supply voltage range,poor system dynamic response,low load drive current and low energy conversion efficiency,need to be solved,and mainly carry out the power tube control pulse modulation method in the forward switching power supply.Theoretical research on loop feedback control mode and core reset method,determined the system design architecture and key technical support of the forward active clamp voltage mode switching power supply,and used the research results to design a PWM pulse generation control The form of the chip is verified.The research results and innovations of this paper are as follows:1.The system architecture and control modes of several basic topological structures of switching power supplies are analyzed in this article.The analysis and comparison of the basic circuit structure of the traditional non-isolated power supply leads to the exploration of the advantages and disadvantages of the isolated conversion power supply and the circuit topology.It mainly controls the pulse modulation method,loop feedback control mode and magnetic core reset of the power tube in the forward converter.Theoretical research on issues such as method and other aspects,a forward active clamp voltage mode switching power supply system model was built.2.A wide-voltage input fast-start voltage stabilization technology built-in integrated circuit is proposed.Through the built-in fast bias stage and the idea of two-stage step-down,the high-voltage input quick start is completed.It is mainly considered from the aspects of process determination,selection of high-voltage devices,high-voltage design of circuit structure,and high-voltage considerations of circuit layout drawing.3.A composite gate power drive technology for isolated power supplies is proposed.The power drive circuit of the isolated power supply is designed with a composite structure of power MOSFET and triode grid.The power MOSFET mainly controls the switching action,and the triode mainly provides the driving current,and its peak current is as high as 3A.4.The internal bandgap reference circuit and the internal power supply module circuit has designed.The internal bandgap reference circuit is designed with a novel circuit structure with voltage pre-modulation unit priority intervention,which can output a stable reference voltage of 1.24 V within 4μs after power-on.The internal power supply circuit can provide a high-stability output voltage of 5V to supply power to other circuit modules in the integrated circuit.5.Based on the BCD integrated circuit design process of 0.18μm feature size,use software such as Cadence and Spectre to perform integrated circuit design and simulation verification,and design and layout the chip’s high voltage devices and ESD protection.Based on the 0.18μm 1P6 M 100V BCD integrated circuit design and manufacturing process,a PWM pulse generation control chip with a wide range of input voltage up to 13～100V is designed.Its operating temperature range is-40℃～125℃,which is actually used in low output voltage.(As low as 3.3V),high output current(up to 30A)active clamp forward converter,can provide control pulse signal for the main power and active clamp power tube at the same time.The final layout of this paper has a total area of about 1.6mm×1.9mm,and an ESD protection design is added to the pins that require high-voltage protection in the layout.