Rechèch sou subharmonic oscillation in pik aktyèl mòd nan oblije chanje pouvwa ekipman pou ekipman pou
DC-DC switching power supply has been widely used in the fields of electronics, electrical equipment, and home appliances due to its advantages of small size, light weight, high efficiency, and stable performance, entering a period of rapid development. The DC-DC switching power supply uses power semiconductors as switches and adjusts the output voltage by controlling the duty cycle of the switches. The control circuit topology is divided into current mode and voltage mode. Current mode control is widely used due to its advantages such as fast dynamic response, simplified compensation circuit, large gain bandwidth, small output inductance, and easy current sharing. Current mode control is further divided into peak current control and average current control. The advantages of peak current are: 1) fast transient closed-loop response, as well as fast transient response to changes in input voltage and output load; 2) The control loop is easy to design; 3) Equipped with simple and automatic magnetic balance function; 4) Equipped with instantaneous peak current limiting function, etc. However, peak inductance current may cause subharmonic oscillations in the system. Although many literature have introduced this to some extent, there has been no systematic research on subharmonic oscillations, especially their causes and specific circuit implementation. This article will conduct a systematic study on subharmonic oscillations.
Paske nan 1st harmonic osilasyon
Lè w ap pran PWM modulation pik aktyèl oblije chanje ekipman pou yon egzanp (kòm montre figi 1, ak bay yon desann konpansasyon estrikti)% 2c yon detaye analiz fèt soti nan diferan pèspektiv kòz nan subharmonic oscillation oscillation.
For the current inner loop control mode, Figure 2 shows the inductance current change when the system duty cycle is greater than 50% and the inductance current undergoes a small step Δ, where the solid line represents the inductance current waveform during normal system operation, and the dashed line represents the actual working waveform of the inductance current. It can be seen that: 1) the inductance current error of the latter clock cycle is greater than the inductance current error of the previous cycle, that is, the inductance current error signal oscillates and diverges, and the system is unstable; 2) The oscillation period is twice the switching period, that is, the oscillation frequency is 1/2 of the switching frequency, which is the origin of the name subharmonic oscillation. Figure 3 shows the variation of inductance current when the system duty cycle is greater than 50% and there is a small step AD in the duty cycle, indicating that the system will also experience subharmonic oscillation. When the system duty cycle is less than 50%, although disturbances in the inductance current or duty cycle can also cause oscillation in the inductance current error signal, this oscillation belongs to attenuation oscillation. The system is stable.
