The Type of Switching Power Supply is Based on the Modulation Method

The types of switching power supplies are divided into the following three types according to the modulation method:

 

1、PWM switching power supply circuit

The frequency of the PWM (or SPWM) drive signal remains unchanged, and the output voltage is regulated and controlled by changing the pulse width (that is, adjusting the duty cycle). Most switching power supply circuits use a feedback closed-loop loop composed of sampling circuits, coupling circuits, etc. to control the pulse width of the PWM (or SPWM) drive signal, and finally achieve the purpose of stabilizing the output voltage amplitude.

 

2、Pulse Frequency Modulated Switching Power Supply Circuit

The duty cycle of the PFM (or SPFM) driving signal remains unchanged, and the purpose of adjusting and stabilizing the output voltage amplitude is achieved by changing the oscillation frequency of the oscillator. Most of the general self-excited switching power supply circuits use this method to adjust and stabilize the output voltage amplitude.

 

3、Hybrid switching power supply circuit

The purpose of adjusting and stabilizing the output voltage amplitude is achieved by adjusting the frequency and pulse width (duty cycle) of the PWM (or SPWM) drive signal. This type of switching power supply circuit generally works in the pulse width modulation mode under heavy load, and works in the pulse frequency modulation mode under light load or no load.