The working process of the transformer type linear regulated power supply can be briefly described as follows: after the 220V/50HZ power frequency grid voltage is reduced through a linear transformer, it is rectified, filtered and linearly stabilized, and finally a DC voltage with ripple voltage and stability meeting the requirements is output. Linear stabilized voltage power supply: According to custom, linear stabilized voltage power supply can be divided into two types: transformer type linear stabilized voltage power supply and switch type linear stabilized voltage power supply. Shanghai switching power supply | power automation power supply | Shanghai industrial control power supply | Shanghai distribution network power supply | rail type power supply | SVG variable frequency high-voltage power supply
The advantages of transformer type linear regulated power supply are high stability, low output ripple voltage and fast transient response; The circuit structure is simple, easy to understand and maintain, no high-frequency switching noise, and high working reliability. The disadvantages are high internal power consumption and low conversion efficiency. Its conversion efficiency is only about 45%. It is large and heavy, which is not convenient for miniaturization. It has low filtering efficiency and must have large input and output filtering capacitors;, The dynamic range of input voltage is small, and the linear adjustment rate is low; The output voltage cannot be higher than the input voltage. There are many kinds of such stable power supplies, which can be divided into voltage stabilized power supply and current stabilized power supply and voltage stabilized current (bistable) power supply integrating voltage stabilized and current stabilized.
The switching regulated power supply is composed of a full wave rectifier, a power switch V, a pulse width modulation (PWM) control and driver, a freewheeling diode VD, an energy storage inductor L, an output capacitor C, and a sampling feedback circuit. In fact, the core of the switching regulated power supply is a DC transformer. The switching voltage stabilized power supply has small internal power loss, high conversion efficiency, small size, light weight, wide voltage stabilization range, high linear adjustment rate, greatly improved filtering efficiency, greatly reduced capacity and volume of filtering capacitor, flexible and diverse circuit forms, and wide choice. However, switching regulated power supply has relatively serious switching noise and interference, generally ≤ 1% VO (P-P), which can be dozens of mV (P-P) or smaller if it is good. The circuit structure is complex, inconvenient for maintenance, high cost and low reliability. Its power can range from several watts to thousands of watts.
Common switching power supply types:
(1) DC/DC power supply
In the communication system, it is also called the secondary power supply. It is a DC input voltage provided by the primary power supply or DC battery pack, and one or several DC voltages are obtained at the output end after DC/DC conversion.
(2) AC/DC power supply
This type of power supply is also called primary power supply. It obtains energy from the power grid, and obtains a DC high voltage through high-voltage rectification and filtering. It is used for DC/DC converter to obtain one or several stable DC voltages at the output end. The power is from several watts to several kilowatts, and is used in different occasions.
There are many specifications and models of these products, and the primary power supply (AC220 input, DC48V or 24V output) in the communication power supply also belongs to this category according to the user's needs
(3) Module power supply
With the rapid development of science and technology, the requirements for power supply reliability and capacity/volume ratio are becoming higher and higher, and the modular power supply is increasingly showing its advantages. It has high operating frequency, small size, high reliability, and is easy to install and expand, so it is increasingly widely used.
At present, although there are corresponding modules produced in China, the failure rate is relatively high because the production process fails to catch up with the international level. Although the cost of DC/DC module power supply is relatively high at present, from the overall cost of the long application cycle of the product, especially the high maintenance cost and goodwill loss caused by system failure, it is cost-effective to select this power supply module. It is also worth mentioning the Rogowski converter circuit. Its outstanding advantages are simple circuit structure, high efficiency and output voltage and current ripple values close to zero.
(4) In essence, the communication power supply is a DC/DC converter type power supply, but it generally uses DC - 48V or - 24V power supply, and uses the backup battery as the backup of DC power supply to convert the DC power supply voltage into the working voltage of the circuit. Generally, it is divided into central power supply, hierarchical power supply and single board power supply. The latter has the highest reliability.
(5) Radio power supply
The power input of the radio station is AC220V/110V, and the output is DC13.8V. The power depends on the power of the radio station supplied. Several amperes and several hundred amperes are available In order to prevent the AC power grid from powering down and affecting the work of the radio station, a battery pack is required as a backup. Therefore, in addition to outputting a 13.8V DC voltage, this type of power supply also has the function of automatic conversion of battery charging.
(6) Special power supply
High voltage low current power supply, high current power supply, 400Hz input AC/DC power supply, etc. can be classified into this category and can be selected according to special needs. The price of switching power supply is generally 2-8 yuan/watt. The price of special low-power and high-power power supply is slightly higher, up to 11-13 yuan/watt.