Characteristics and advantages and disadvantages analysis of switching regulated power supply

The editor below has compiled an analysis of the characteristics and advantages and disadvantages of switching regulated power supplies. It is worth knowing!

The switching power supply achieves voltage regulation by controlling the on-off time of the regulating tube.

Advantages: small size, light weight, low power consumption, wide voltage stabilization range, and efficiency of 80%~90%.

Disadvantages: The output ripple voltage is high, the noise is large, and the voltage regulation rate and other performance are also poor, especially when powering analog circuits, it will have a greater impact.

Usage: By connecting a low voltage dropout linear regulator to the output end of a switching regulator, active filtering can be achieved, and the voltage stabilization accuracy of the output voltage can be greatly improved without significantly reducing the efficiency of the power supply system.

Switching power supply composition:

Ui is the rectified and filtered DC voltage, Uo is the converted DC output voltage, and the DC-DC converter is used for power conversion.

Classification of switching power supplies:

No matter what kind of switching power supply, the adjustment tube always works in the switching state. The voltage driving the adjustment tube can be a square wave pulse width modulation voltage or a sine wave resonant voltage.

According to the driving voltage, it can be divided into self-excited type and separately excited type.

Self-excited type: The regulating tube and the auxiliary winding of the switching transformer form positive feedback to achieve self-excited oscillation and voltage stabilization.

Separately excited type: Use a dedicated oscillator to generate pulses to control the pass tube.

According to the converter circuit structure, it is divided into non-isolated type and isolated type.

Non-isolated type: input and output share the same ground, suitable for low-voltage DC conversion situations, including buck type, boost type, and buck-boost type.

Isolated: input and output are isolated. Including flyback, forward, push-pull, half-bridge, full-bridge.

According to the pulse modulation mode of the switching tube, it is divided into pulse width modulation type, frequency modulation type and hybrid modulation type.

Pulse width modulation type: Control the duty cycle by changing the on-time of the switch tube to adjust and stabilize the output voltage.

Frequency modulation type: The conduction time of the switch tube remains unchanged, and the output voltage is adjusted and stabilized by changing the pulse frequency of the switch tube.

Hybrid modulation type: The conduction time and pulse frequency of the switching tube are changed, thereby regulating and stabilizing the output voltage.