With the rapid development of the electronic information industry, inverter power is widely used in many fields. A reliable and high-quality inverter power supply can ensure reliable and safe operation of the system. Therefore, the inverter power supply is an important research field. Square wave inverter is a simple conversion method. It is suitable for various rectification loads. It has low technical requirements and simple design circuit. According to the basic principle of square wave inverter power supply, this paper modularizes the realization circuit of inverter power supply, including high frequency PWM main circuit based on SG3525 control, full bridge inverter circuit, necessary protection circuit and related drive circuit, and gives Experimental results and analysis.
1. Principle and design 1.1. Basic principle of inverter power supplyThe inverter power supply uses a typical two-stage conversion: the first stage is a DC/DC boost converter, and the second stage is a DC/AC inverter. The DC/DC boost converter converts 12V DC into a high-frequency square wave by the PWM wave generated by the SG3525 chip. After being boosted by the high-frequency transformer, the secondary side of the transformer can obtain a high-frequency square wave with a peak value of 155V, and then undergo full-wave. The rectification obtains a stable 310V DC voltage; the DC/AC conversion uses a square wave inverter method to invert the stable DC voltage into a 310V power frequency square wave voltage. The effective value of the voltage is about 220V, the frequency is 50Hz, and can be driven. Load [1]. In order to ensure the normal operation of the system, a feedback circuit is needed to protect the system and prompt its working status. The protection circuit collects the high-voltage side DC voltage signal, the output current signal and the battery voltage signal, and inputs it to the SG3525 controller through the comparator circuit to realize voltage regulation, over-current protection, over-temperature protection, over-voltage protection and under-voltage protection.
The inverter power system block diagram is shown in Figure 1.
Figure 1 Block diagram of the square wave inverter
1.2, hardware circuit design1.2.1, DC / DC boost converter circuit
The inverter power supply is a battery with an output of 100W and an input of 12V. The DC/DC converter uses a push-pull circuit, and the push-pull circuit is generally used in small and medium power applications where the input voltage is low. The center of the high-frequency transformer is connected to the 12V battery at the center tap, and the two ends of the primary coil are respectively connected to two sets of parallel switching tubes. The parallel connection can increase the input current to avoid the current caused by the excessive current of the transformer after the load is connected. damage. The peripheral circuit built by SG3525 outputs high-frequency PWM signal to control the alternate operation of two sets of switching tubes, namely Q1Q2 and Q3Q4, and the secondary side of the transformer outputs high-frequency square wave. Parallel switching tubes increase the output power and allow the input circuit to have a greater current resistance. The switch tube of NTP60N06 model is designed to have a withstand voltage of 60V and a flow resistance value of 60A. Push-pull structure can reduce transformer volume and reduce inverter power costs. The output of the secondary winding is connected in the form of full-wave rectification, and the step-up rectification obtains a DC voltage of 310V. The main circuit is shown in Figure 2.
Figure 2 DC / DC structure transformation diagram
All In One Pc 21.5 Inch,All In One Pc Intel Core I5,Intel I5 All In One,Computer All In One Core I7
Guangdong Elieken Electronic Technology Co.,Ltd. , https://www.elieken.com