Dongguan Longwei Electronic Technology Co., Ltd

LW (LONGWEI) always adhere to the "quality first, customer first, keep improving" !

Home > News > Content
The Comparison And Development Direction Of Various Dc Power Sources
- Apr 23, 2018 -

General electronic equipment in the work, all need a stable dc voltage. The grid is usually 2 0 v, 5, voltage fluctuations can be 2 0 Hz, or even higher, and may contain peak, surge or high frequency interference. So dc power needs to make efficient conversion, output voltage stability, suppress the interference on the power grid, the smaller the conducted emission and electromagnetic radiation. Tell from the basic principle, choice of linear regulated power supply and switch dc power supply.

Linear stabilized dc power supply.

(1) type of linear regulated power supply in parallel: the method of using parallel zener diode, absorb the additional current requirements input power supply with high internal resistance, is only applicable to the occasion of load current is small, the circuit is simple, but the efficiency is low.

(2) linear regulated power supply series, series voltage adjustment between input power and load, is due to the tube in series between the input power and load voltage adjustment, adjust (a) into a tube on the fever, and adjust the tube must be working in the linear amplification state, in order to guarantee the stability of output voltage, it must be under high voltage difference between collector and emitter, lead to adjust the tube power consumption is larger, the power efficiency is very low (usually only about 4%)

In addition, due to the adjustment of pipe on the consumption of power, so the adjustment of the need to adopt high-power tubes, even need large radiator, so it is hard to meet the demands of the development of electronic devices. When using the MOS tube can be minimal work under the pressure difference (0) 1 mV, reduce loss, but allow current is small, and the high cost.

Switching dc power supply

Switch dc power supply based on the principle of the pulse form the input dc power supply of the energy stored in the inductor or capacitor, reoccupy rectifier filter method will be at the ends of the inductor or capacitor voltage into a dc voltage

Grid rectifier filter, even for grid rectifier filter not only, the power is very small also can be achieved with series capacitance step-down method. Because of the pressure regulating device working in switch mode, so efficiency is very high (9%) to the power consumption is very small, in low temperature, so as to improve the whole 0, the stability and reliability of the machine. And its ability to adapt to the grid has greatly improved, and a range of 20 V series regulated power supply to allow power grid, voltage regulator and switch mode power supply in power grid voltage range from 1 to 6 V change, can obtain the stable output voltage, when the pulse frequency is higher, energy storage and filter can be smaller, so the volume is small, don't even need to power transformer. But switch dc power supply fault is due to the pressure regulating device working in switch mode, so d V, d, is very big, prone to strong I conducted emission and radiation emission. Also because of the high and low potential segment has different ground impedance, and ground network to have larger impedance at high frequency, make the two lines of the earth formed different impedance, namely the high frequency differential mode voltage produced different phase shift, the differential mode voltage will be converted to a common mode voltage, resulting in a disturbance, once produced, common-mode interference is difficult to filter.

The comparison between the linear regulated power supply and the switching dc power supply.

To sum up, the advantages of linear power supply are simple circuit, small output ripple and no radiation interference. The disadvantage is that it is inefficient, bulky and has a narrow range of input voltage. The advantages of switching dc power supply are high efficiency, compact and wide range of input voltage. The disadvantage is that the output ripple is large and it is easy to generate electromagnetic interference and common mode interference.

In terms of production and application, the cost of switching dc power and linear power supply increases with the increase of output power, but the rate of growth is different. Linear power supply cost on a power output point, rather than switch dc power supply, as the costs of the inversion point, makes the switch dc power supply technology in constant innovation, and with the development of electronic technology, to move lower output power end, for the switch benefit power provides a broad space for development. Computer power in the 80 s and the color has comprehensive implementation of switch power supply, dc power, rate to complete the power generation. Into the 90 s switch dc power have entered various electronic, electrical equipment, program-controlled switches, communications, electronic testing equipment, power supply, power supply control equipment, etc are widely used switch dc power supply, the more promote the rapid development of the switch dc power supply technology.