【正文】 ng load switch machine, reduce the adjustment of the plex procedures.四. Small volume light weight the prehensive use of anticorrosive craft, enhance the ability of anticorrosion products, prolong the life.五. Energy saving, high working efficiency reached more than 90%, any more than a linear always voltage matching. Save the traditional rectifier regulator and the energy loss, in more than 35%, greatly reduce the cost, the reason of surface treatment industryHigh frequency switching power supply一． The main circuitFrom the input and output of dc exchange network, including:1．The whole the effect is input filter: there will be the clutter power filter, also hindered the feedback to produce clutter of public power.2．And rectification and filtering: ac power grid directly to a smooth dc rectification, in order to the next level.3．Inverter: after rectifying dc into high frequency alternating, this is the core part of switch power supply, the higher the frequency volume, and weight and output power than smaller.4．And output rectifier and filtering: according to provide reliable, load of the dc power supply.Second control circuit ：On one hand, the sample from the output terminal with setting standards, and then pared to control the inverter, change the frequency or pulse width, achieve output stability, on the other hand, according to the test circuit, the information provided by differential protection circuit, control circuit of various protection measures.Third detection circuit：In addition to providing protection circuit is running in the various parameters but also provide various display meter data.Four, the auxiliary powerTo provide all the different requirements of a circuit switching voltage control principleSwitch to certain time interval K repeatedly through and disconnect the switch, the power input, K E through switch and filter circuits provide load RL, throughout the switch power load during to provide energy, E, When the switch, input power disconnection K E will provide energy interrupted. Visible, to provide the energy input power load is intermittent, for the load can be provided for energy switching power supply, a storage device, must be in switch will be part of the energy stored in the switch to load, release. In the figure, the inductance and capacitance C2 and diode L circuit, is posed of D this function. Inductance used in storing energy, l., and stored in the switch of energy through the diode inductance L D, released to load get steady and continuous energy, because diode D make continuous load current, so called freewheeling diode. In EAB average voltage between AB says: under the type used:EAB = TON/T * EFor every TON of time, the switch to switch the huge T works cycle (. switch time TON TOFF cutoff time and sum).By type, changing switch time and work cycle, the ratio between the average voltage AB also changed, therefore, with the load and the input voltage changes automatically adjusted TON and the proportion of T he can make the output voltage V0 remain unchanged. Change through Time and work cycle TON of pulse that changing proportion of this method, SHCH as Time Ratio Control (from Time, abbreviation for TRC).According to the control principle TRC have three ways:A Pulse Width Modulation (Pulse Width Modulation, the abbreviation for PWM)Switch is constant, by changing the pulse width to change the way SHCH.Second, Pulse Frequency, Pulse Modulation (some Modulation abbreviated PFM)The constant change of the pulse width, through the working frequency switches to change the way SHCH.Third, mix modulationConduction pulse width and switch jobs are not fixed frequency, each other can change the way, and it is more than two ways of mixed.High frequency switching power supply [1] don39。 10% fluctuate, but switching voltage stabilizer in voltage in a 110260 volts range change, can obtain stable output voltage.The high frequency switching power supply is the development of technology innovation technology, high frequency of the benefit is that switching power supply device to miniaturization, and make an unprecedented power switch into a wide range of areas, especially in the hightech fields of application, promote the hightech products of miniaturization, light. Now on the market of switch power supply power tube with a bipolar transistor, switch frequency can reach several KHZ, The switch power MOSFET using frequency conversion of hundreds of KHZ. To improve the switch frequency, must adopt high speed switching devices. For the power switch frequency than MHZ available resonant circuit this way of working is called resonant switching mode.It can greatly improve switch speed, theoretically switch loss to zero, the noise is small, and it is to improve the working frequency of switch power. By way of resonant switching converter has practical level MHZ. Pursuit of switch power supply technical development trend and can be summarized in the following four aspects.A miniaturization, thin, light, high frequency switching power supply of of volume, weight is mainly posed of storage devices (magnetic ponents and capacitance), so the miniaturization of switch power supply is essentially to minimize the volume of storage devices, In a certain range, the switch frequency, not only can effectively reduce capacitance and inductance and the size of the transformer, but also can restrain the interference, improve the dynamic performance of the system. Therefore, high frequency switching power is the main development direction.Second, high reliability the use of switch power supply for a job than ponents ten times, thus increasing the reliability. From the Angle of life, capacitors, optical coupler and platoon devices such as life determines the munication power of life. So, from design, use less as far as possible, improve integration. Such not only solved the reliability of plex, the circuit, also inc