Graphical analysis of the design and production of digital power supply based on dsPIC30F

Control board power supply: flyback switching power supply, output 4 sets of independent power supply

Drive mode: 250 power drive optocoupler, +15V, -3.3V negative voltage

Can drive IGBT: MOSFET

Output mode: single-stage, H-bridge power frequency transformer output.

Feedback method: communication sampling feedback.

Software design: Use SVPWM, single-phase space vector modulation, to optimize switch control timing.

Control idea: internal model repetitive control principle + voltage timing hysteresis loop + PI control technology.

Design results: There is basically no frequency error, the voltage difference between no-load and full-load is no more than 2%, the forward conversion voltage difference between no-load and full-load is no more than 2%, and it can be stabilized within 2 cycles.

The above is the waveform with resistive load. The figure below is the control waveform of voltage hysteresis loop.

We also conducted an experiment

After preliminary testing of the system, the voltage repetitive control principle has a good compensation effect on the distortion of the voltage waveform. And it has high static following accuracy and fast dynamic response, which is an ideal digital power supply platform. Of course, the main chip can be reduced to 30F2020, maintaining the operation speed of 30MIP, but the price can be 20 yuan. When repetitive control is used for waveform correction of the inverter, its basic idea is to assume that the waveform distortion that appeared in the previous fundamental cycle will be repeated at the same time in the next fundamental cycle. Under this assumption, the controller determines the required correction signal according to the error between the given signal and the feedback signal of each switching cycle, and then superimposes this signal on the original control signal at the same time in the next fundamental cycle to eliminate the repetitive distortion that will appear in the subsequent fundamental cycles. Therefore, repetitive control only has an inhibitory effect on periodic disturbances that produce waveform distortion, but cannot inhibit non-periodic disturbances. However, in practice, most of the disturbances that produce waveform distortion of the inverter are periodic, and the disturbances caused by the dead zone and the load are periodic disturbances. Therefore, repetitive control technology can have a good correction effect on the waveform distortion caused by the dead zone and the load at the same time. Now there is no experiment with a large number of inductive loads, and the focus is shifted to solving the current front-end problems that are bothering me.

Hardware issues:

This 16-bit digital power platform DC bus power supply adopts 60V DC power supply. However, to make a variable frequency, high performance and high power power supply, the front stage needs a high power factor PFC circuit. In addition, to obtain a 60V DC voltage, a 3525 full-bridge soft switch conversion is required. These are some of the difficulties encountered at present. I hope my colleagues can give me some advice!! At the same time, an experiment was also conducted to superimpose the 150HZ third harmonic on the 50HZ fundamental wave, and the harmonic amplitude was 10% of the fundamental wave. The figure below is the output waveform, indicating that the hysteresis loop tracking is good.