Linear DC power supply and switching power supply have how to distinguish between
Linear Power Supply
The main circuit of the linear power supply is as follows:
That is, ~ 220V mains controlled by the SCR only part of the primary transformer in the main transformer. When the output voltage Uo higher, SCR conduction angle is larger, most of the mains voltage by the SCR "put over", and thus the voltage added to the transformer primary, that is, Ui higher, which of course rectified and filtered output voltage is relatively high.
When the output voltage Uo is very low, the SCR conduction angle is very small, the vast majority of the mains voltage by the SCR "card cut off", only a very low voltage added to the transformer primary, that is, Ui is very low, which of course, the rectifier filtered output voltage is also very low.
The current production of switching power supply used in a variety of PWM integrated chip, mainly from the output voltage variation range is small, the output current is more stable point of view to the design.
But the so-called PWM chip, is a pulse width modulator, when the output voltage is higher, the output current is larger, the power supply internal switching tube turn-on time is longer and turn-off time is shorter:
If the output voltage and current continue to fall, the requirements of the control pulse continues to narrow, but the PWM circuit has been unable to meet, then the circuit becomes intermittent work, such as:
Pulse from time to time, a burst, the power supply will issue noise, ripple, etc. will also become large, poor electrical performance, the so-called "low-end instability", in fact, has become a substandard product. In order to solve this problem, our company to take new technical measures to better solve (no more details).
Linear power supply and switching power supply comparison
1, linear power supply accuracy is good (better than switching power supply 1-3 orders of magnitude), ripple is small, the adjustment rate is good, external interference is small, applicable to a variety of occasions.
2, linear power supply power devices work in a linear state, so the loss is relatively high relative to the switching power supply, the efficiency of the switching power supply is better.
3, the size of the switching power supply compared to the linear power supply is small, but the switching power supply has the problem of pollution of the power grid and amplitude interference.
4 Switching power supply is not suitable for use in the output of high voltage and high current when the 0-voltage starting adjustable continuously adjustable occasions, but is suitable for fixed output or relatively fixed output on the occasions of radiation interference is not too demanding.
5, maintenance on the linear power supply is relatively easy to maintain. Switching power supply due to the dense components, to bring some difficulty in maintenance. In addition, because the circuit is very different from the linear power supply, the technical quality of the maintenance staff requires a high level of oscilloscope to observe the circuit at various points of the working state.
