Comparison between linear socket and switch socket
The switch socket mainly includes an input network filter, an input rectifying filter, an inverter, an output rectifying filter, a control circuit and a protection circuit. Their functions are described below.
(1) input grid filter: to eliminate interference from the power grid, such as motor start, electrical on / off, lightning and other interference, but also to prevent the switch socket high-frequency noise to spread to the grid.
(2) input rectifier filter: the input voltage of the grid rectifier filter for the converter to provide DC voltage.
(3) inverter: a key part of the switch socket, which converts the DC voltage into high-frequency AC voltage, and play the output part of the role of isolation from the input power grid.
(4) output rectifier filter: the converter output of the high-frequency AC voltage rectifier filter to get the required DC voltage, but also to prevent high-frequency noise on the load interference.
(5) control circuit: Detect the output DC voltage, and compare it with the reference voltage to amplify, modulating the pulse width of the oscillator, thus controlling the converter to maintain the stability of the output voltage.
(6) protection circuit: When the switching power supply over-voltage, over-current short circuit, the protection circuit to stop switching power supply to protect the load and power itself. ^
Linear power supply is generally the output voltage of the sample with the reference voltage with the reference voltage into the comparison voltage amplifier, the voltage amplifier output voltage regulator as the input to control the regulator to adjust the junction voltage changes with the input to adjust its The output voltage. But the switching power supply is to change the regulation by the opening and closing time (ie duty cycle) to change the output voltage.
Linear outlet and water pipe is similar, because there is no switch involved, making the water has been in the water, if there is more water, it will leak out, which is often seen in some of the linear outlet M0S tube heat a lot, All the energy used to convert into heat. From this perspective, the linear conversion efficiency of the socket is very low, and high heat, the component life is bound to decline, affecting the final results. Since linear power devices work in a linear state, their efficiency is low, typically 50% to 60%. Linear sockets work, making the low voltage from the high voltage step-down transformer must be, and then through the rectifier output DC voltage, thus causing its large size, bulky, low efficiency, heat is also large. Of course, linear sockets also have advantages: small ripple, good regulation, external interference, suitable for analog circuits, various types of amplifiers.
The switch socket of the power devices work in the switch state (a one on, the frequency is very fast, the general flat-panel switch socket frequency of 100-200kHz, the module power supply for the 300-500kHz), while it requires transformers, Conductivity of the material to make the transformer.
In short, compared with linear sockets, switch socket power conversion efficiency, up to 65% ~ 90% (the best US VICOR switch socket module efficiency up to 99%), less heat, power factor can send 60? Voltage and load stability, the output voltage holding time is as long as 20ms, the switch socket does not need the power frequency transformer, the working frequency is high, the required filter capacitance and inductance are small, so its voltage and current are small. Small size, light weight, fast dynamic response; open-type socket switching frequency of goods in 20kHz, beyond the ears of the hearing range, no annoying noise; switch socket can be effective power factor correction technology, Factor of 0.9 or more, high even up to 0.99 (An Sheng HD4850 rectifier module). These make the switch socket in the field of communication power has been a large number of linear power supply instead.
Switch socket is the main drawback of the complex line, the output ripple large, switch socket circuit come out of the beginning, the control circuit is composed of discrete components or operational amplifiers and other integrated circuits; components and more complex lines, the resulting reliability Poor performance and other reasons seriously affected the wide range of switch socket applications.
The development of switches and sockets depends on the development of components and magnetic materials. In the late 1970s, with the highly developed conductor technology, high-voltage fast switching power switch-free power frequency transformer switching power supply quickly practical. And the rapid development of integrated circuits for the switch socket control circuit integration laid the foundation. The emerging switch socket dedicated pulse modulation circuit, such as SG3525 and TI494, such as switching power supply provides low cost, excellent performance and reliability, the use of bubble will be integrated control circuit chip, making the switch socket circuit from complex to simple. At present, the output ripple switch socket has dropped to below 100mv, radio frequency interference and electromagnetic interference is also suppressed to a very low level. In short, with the development of power electronics technology, the shortcomings of the switch socket is gradually being overcome, and its advantages can be brought into full play. Especially in the current situation of relatively tight energy V, the high efficiency of the switch socket can make a great contribution to energy saving. Because the switch socket has these advantages, so it has been vigorous development.
Behind, we then detail the single-chip switch and socket classification, please attention.
