The control circuit of the full bridge topology designed in this paper mainly includes controller, protection circuit, current feedback, voltage feedback, drive circuit and auxiliary power supply. The control circuit is the core part of the switching power supply. Its design is very important for the performance of the switching power supply. Many indicators of the power supply such as constant voltage constant current, ripple size, input and output characteristics are closely related to the control circuit, and at the same time, the main circuit It is a full-bridge topology. When designing the control circuit, it is necessary to take corresponding measures to prevent the shoot-through phenomenon. The following is a detailed design and introduction of the functional circuits of each part of the control circuit. UC3846 is used as the control chip. The chip uses a high current totem pole type double-ended output, output peak current up to 500mA, can directly drive the FET, built-in precision bandgap adjustable reference voltage, high frequency oscillator, error amplifier, differential current sense amplifier, owed The voltage lock circuit and the boot soft start circuit have an automatic shutdown function. Its main advantages are current limit, automatic feedforward compensation, undervoltage protection, terminal lock protection, and better load response characteristics. The peripheral control circuit is simple and the operating frequency is up to 500KHZ. The maximum input voltage is 40V and the reference voltage output is typically 5.1V. The internal structure is shown in the figure. Figure UC3846 internal structure block diagram Figure UC3846 control circuit diagram In high-power circuits, current transformers are often used to detect current. Current transformer detection can not only improve efficiency, but also achieve electrical isolation, which is an ideal choice. Based on the above, this paper selects the current transformer to detect the primary current. as the picture shows. Lithium-boron alloy is a composite material composed of a brittle Li7B6 matrix phase with a porous structure and a ductile Li filling phase. The density is 0.88±0.04g/cm3. The appearance is silver-white metal. It is extremely unstable. It is easily deteriorated when exposed to air and reacts with water. severe. Lithium-boron alloy is mainly used as anode material for lithium-based thermal batteries. It has outstanding advantages such as high specific energy, high specific power and low polarization, electrochemical potential similar to that of pure lithium, and solid state above 600℃. It is a new type of lithium-based thermal battery. The excellent negative electrode material. Compared with the currently widely used Lithium-Silicon Alloy, the unit cell assembled with the lithium-boron alloy as the negative electrode material has better performance in both the highest voltage and the discharge working time. Shandong Huachuang Times Optoelectronics Technology Co., Ltd. , https://www.dadncell.com
