The way a DC controlled power supply works
1、 The working principle of DC regulated power supply
A DC regulated power supply is a device that converts 220V AC power into a regulated output DC voltage. It needs to go through four stages: voltage transformation, rectification, filtering, and voltage stabilization to complete.
The working principles of the four links are as follows:
(1) Power transformer: It is a step-down transformer that converts the 220V AC voltage of the power grid into the required AC voltage and sends it to the rectifier circuit. The transformation ratio of the transformer is determined by the secondary voltage of the transformer.
(2) Rectification and filtering circuit: The rectification circuit converts the AC voltage Ui into a pulsating DC voltage. After filtering the larger ripple components through the filtering circuit, the DC voltage U1 with smaller ripple is output. The commonly used rectification and filtering circuits include full wave rectification and filtering, bridge rectification and filtering, etc.
(3) Filter circuit: Most of the AC component in the output voltage of the rectifier circuit can be filtered out to obtain a relatively smooth DC voltage. Each filter capacitor C satisfies RL-C=(3-5) T/2, or T is the input AC signal period, and RL is the equivalent load resistance of the rectifier filter circuit.
(4) Voltage stabilizing circuit: The function of a voltage stabilizing circuit is to stabilize the output DC voltage and not change with changes in AC grid voltage and load. The commonly used integrated voltage regulators include fixed three terminal voltage regulators and adjustable three terminal voltage regulators. The output voltage of the common voltage regulator can be adjusted from 1.25V to 37V, and the external components of the simple circuit only need a fixed resistor and a Potentiometer. The chip has transition, overheating, and work zone protection, with a maximum output current of 1.5A. The resistance R1 and the Potentiometer R2 form the output voltage regulator. The expression of the output voltage Uo is: Uo ＝ 1.25 (1 ＋ R2/R1) where R1 is generally 120-240 ohms, and the voltage difference between the output end and the adjustment end is the reference voltage of the regulator (typical value is 1.25 V).
2、 The Application of DC Stabilized Voltage Power Supply
DC regulated power supply is an indispensable equipment in the field of electronic technology. Most common DC regulated power supplies use the principle of series feedback voltage stabilization, and adjust the output voltage by adjusting the Potentiometer in the sampling resistance branch at the output end. Because of the nonlinearity of Potentiometer resistance change and narrow adjustment range, it is difficult to adjust the output voltage of ordinary DC regulated power supply.
3、 The Prospects of DC Stabilized Power Supply
In recent years, with the development of technology, the working frequency of DC regulated power sources has increased from tens of kilohertz to hundreds of kilohertz now; Research has shifted to the topology theory, working principle, modeling analysis, and other aspects of high-frequency power sources; The development and application of DC regulated power sources have become increasingly mature.
