Design of high-power switching power supply based on DSP

　　1. Overall power supply solution

　　The basic principle block diagram of the switching power supply designed in this paper is shown in Figure 1. It mainly consists of a power main circuit, a DSP control loop and other auxiliary circuits.

　　The main advantage of switching power supply lies in "high frequency". Usually, filter inductors, capacitors and transformers account for a large proportion of the volume and weight of the power supply device. From the relevant knowledge of "circuit" and "electrical machinery", it can be known that increasing the switching frequency can reduce the parameters of the filter and miniaturize the transformer, thereby effectively reducing the volume and weight of the power supply device. Taking the transformer with an iron core as an example, the analysis is as follows:

　　Figure 1 System composition block diagram

　　2. System hardware design

　　The main power circuit of this power supply adopts the "AC-DC-AC-DC" conversion structure, which is mainly composed of input grid EMI filter, input rectifier filter circuit, high-frequency inverter circuit, high-frequency transformer, output rectifier filter circuit and other parts, as shown in Figure 2.

　　Figure 2 Schematic diagram of the main power circuit

　　In order to build the DSP controller software framework and make the program easy to write, check errors, test, maintain, modify, update and expand, modular design is adopted in the software design, and the entire software is divided into initialization module, ADC signal acquisition module, PID operation processing module, PWM wave generation module, LCD display module and key scanning module. The process of each module is shown in Figure 3.

　　Figure 3 Software module flow chart

　　The main technical indicators are as follows: input voltage: three-phase AC380V±5%; output voltage: DC220V±2%; output current: 50A; rated power: 11kW.

　　The output waveform of the test prototype at rated load is shown in Figure 4(a). From the actual reading in Figure 4(a), it can be seen that the response time of the output voltage rising from 0 to 220V is about 1s, and the power supply system has a fast response speed. At the same time, from the partial enlarged view of the voltage waveform in Figure 4(b), it can be seen that when the output voltage is 220V, the voltage fluctuation is about 2V, and its maximum voltage fluctuation is less than 1%.

　　Figure 4 Output waveform of the prototype at rated load

　　4 Conclusion

　　The high-power high-frequency switching power supply based on DSP introduced in this article fully utilizes the powerful functions of DSP, can control the switching power supply in many aspects, and can simplify the components, reduce costs, reduce power consumption, and improve the reliability of the equipment. The test data shows that the indicators meet the design requirements, and the power supply can maintain good output performance.