开关电源中英文翻译.pdf

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1、 Switching Power Supply Switching power supply is a voltage conversion circuit,the main work is the step-up and step-down,are widely used in modern electronic products.Always work because the switching transistor in the on and off state,so called switching power supply.Switching power supply in real

2、 terms is an oscillator circuit,the conversion of electrical energy not only used in power circuit,the circuit in other applications are also common,such as LCD backlight circuits,such as fluorescent lamps.Switch the source compared with the transformer high efficiency,good stability,small size and

3、other advantages,disadvantages is the relatively small power,and high-frequency interference on the circuit,circuit complexity,such as easy maintenance.Talking about switching power supply before you familiar with the feedback oscillator circuit transformer,can produce a regular pulse current or vol

4、tage of the circuit is called oscillation circuit,transformer feedback oscillator circuit is able to meet these conditions the circuit;it in the basic amplifier circuit with a feedback loop composed of C2,L1 election to form a parallel resonant frequency circuit,the instantaneous power in the circui

5、t turn-VT,this time in the C2,L1,composed of parallel resonant circuits have a very rich harmonic,when the plus parallel resonance frequency and the natural frequency of the same circuit,the circuit to enter a state of oscillation,and VT through L3 feedback to further enlarge the base,and ultimately

6、 the formation of a regular pulse current or voltage output to the load RL.Switching power supply is around the transformer and the feedback oscillator circuit design,but the basis of the original increase in the number of protection and control circuits,analysis of our oscillation circuit can be us

7、ed to analyze the method of switching power supply.Switching Power Supply vibration by way of sub-swing can be divided into self-excited and it excited the two,since there is no need for plus-excited self-oscillation signal source,since the excitation can see it as a feedback oscillator circuit tran

8、sformer,and it is excited is totally dependent on the outside to maintain the oscillation,in the practical application of self-excitation of a comprehensive range of applications.According to the structure of incentives signal classification;can be divided into pulse-width-modulated pulse amplitude

9、modulation and two pulse-width-modulated signal to control the width,that is,frequency,pulse amplitude modulation control signal of the magnitude of the role of the two the same so that oscillation frequency is maintained at within a certain range,to the effect of voltage stability.Winding transform

10、er can be divided into three types in general,a group involved in the primary winding of the oscillation,a group is to maintain the oscillation of the feedback winding,there is a group of the load windings.Household appliances used in switching power supply,after the AC to 220V bridge rectifier,conv

11、erted into about 300V DC,filter into the transformer is added after the switch to high-frequency oscillations of the collector,feedback winding back to the base to maintain the oscillation circuit,load sensor windings of the electrical signal,by rectification,filtering,the DC voltage regulator has b

12、een to provide power to the load.Winding in the provision of electric power load,but also take up the capacity of voltage stability,the theory is then a circuit voltage output voltage sampling devices to monitor the output voltage changes,timely feedback to adjust the oscillation frequency oscillato

13、r circuit to achieve the voltage stability The purpose of the circuit in order to avoid interference,the feedback voltage to the oscillator circuit will be isolated optocoupler.Most switches have a standby power circuit,switching power supply in standby mode still oscillating,but the frequency of no

14、rmal working hours than lower.Some switching power supply are complex,numerous components,many protection and control circuit,in the absence of technical support,maintenance is a headache with the matter.I face this kind of situation is,first of all,I will find the switch and its participation in th

15、e external oscillation circuit,it separated from the circuit to see if it met the conditions for oscillation,such as detection bias and whether it is normal,whether positive feedback failure,as well as its own switches,switching power supply has very large protection,after exclusion of the prosecuti

16、on and load control and protection circuit.the control circuit while output from the sample,with the set standards,then controlled inverter,change its frequency or pulse width output achieve stability,on the other hand,according to test data provided by the circuit by circuit protection identificati

17、on,Control circuit for the unit for various protection measures.SMPS developments and trends in the United States in 1955 Roje(GH.Roger)invention of the self-excited oscillation push redeem transistor single transformer DC converters,high-frequency conversion is the beginning of control circuit,1957

18、 United States investigation tournament(Jen Sen)since the invention of the push-pull double Flyback transformers,1964 American scientists proposes to abolish the frequency transformer series switching power supply scenario,This power to the right size and weight of the decline was a fundamental way.

19、To the 1969 high-power silicon transistor because the pressure increase diode reverse recovery time shortened,and other components improve,and finally turned into a 25 kHz switching power supply.Currently,switching power supply to small,Light volume and the characteristics of high efficiency has bee

20、n widely used in electronic computer-driven variety of terminal equipment,Communications equipment almost all electronic equipment,the electronic information industry indispensable to the rapid development of a power mode.Currently the market for sale in the switching power supply using bipolar tran

21、sistors made of 100kHz.use made of 500kHz MOS power,though practical,but its frequency to be further enhanced.To improve the switching frequency,it is necessary to reduce the switching loss,and to reduce the switching loss,you need to have high-speed switching devices.However,the switching speed,wil

22、l be affected by the circuit inductance and capacitance diode or stored charge arising from the impact of the surge or noise.This will not only affect the surrounding electronic equipment,but also greatly reduce the reliability of the power supply itself.Among them,with the switch to prevent Kai-clo

23、sed by the voltage surge,it is R-C or L-C Composite bumpers,and the storage charge by the diode current surge caused by the use made of amorphous cores such as magnetic bumper.However,the high frequency of 1 MHz and above,using resonant circuit,Switch to enable the voltage or current through the swi

24、tch was a sine,which could reduce the switching loss,This can also control the surge occurred.Switches such as resonant mode switching.Currently such SMPS of very active,because this means no significant increase switching speed can theoretically put switching loss fall to zero.and the noise is smal

25、l,is expected to become high-frequency switching power supply of one of the main ways.At present,many countries in the world are working on several trillion Hz converter practical research.开关电源 开关电源是一种电压转换电路，主要的工作内容是升压和降压，广泛应用于现代电子产品。因为开关三极管总是工作在“开”和“关”的状态，所以叫开关电源。开关电源实质就是一个振荡电路，这种转换电能的方式，不仅应用在电源电路，

26、在其它的电路应用也很普遍，如液晶显示器的背光电路、日光灯等。开关源与变压器相比具有效率高、稳性好、体积小等优点，缺点是功率相对较小，而且会对电路产生高频干扰，电路复杂不易维修等。在谈开关电源之前，先熟悉一下变压器反馈式振荡电路，能产生有规律的脉冲电流或电压的电路叫振荡电路，变压器反馈式振荡电路就是能满足这种条件的电路；它于基本放大电路与一个反馈回路组成，其中 C2、L1组成一个并联谐振选频电路，在电路通电的瞬间 VT 导通，此时在 C2、L1组成的并联谐振电路上产生非常丰富的谐波，当外加频率和并联谐振电路的固有频率相等时,电路进入振荡状态，并通过 L3反馈到 VT 的基极进一步放大，最终形成有

27、规律的脉冲电流或电压输出到负载 RL 上。开关电源就是围绕变压器反馈式振荡电路而设计，只不过在原来的基础上增加了一些保护和控制电路，我们可以用分析振荡电路的方法来分析开关电源。开关电源振按荡方式分，可以分为自激式和它激式两种，自激式是无须外加信号源能自行振荡，自激式完全可以把它看作是一个变压器反馈式振荡电路，而它激式则完全依赖于外部维持振荡，在实际应用中自激式应用比较广泛。根据激励信号结构分类；可分为脉冲调宽和脉冲调幅两种，脉冲调宽是控制信号的宽度，也就是频率，脉冲调幅控制信号的幅度，两者的作用相同都是使振荡频率维持在某一范围内，达到稳定电压的效果。变压器的绕组一般可以分成三种类型，一组是参与

28、振荡的初级绕组，一组是维持振荡的反馈绕组，还有一组是负载绕组。在家用电器中使用的开关电源，将220V 的交流电经过桥式整流，变换成300V 左右的直流电，滤波后进入变压器后加到开关管的集电极进行高频振荡，反馈绕组反馈到基极维持电路振荡，负载绕组感应的电信号，经整流、滤波、稳压得到的直流电压给负载提供电能。负载绕组在提供电能的同时，也肩负起稳定电压的能力，其原理是在电压输出电路接一个电压取样装置，监测输出电压的变化情况，及时反馈给振荡电路调整振荡频率，从而达到稳定电压的目的，为了避免电路的干扰，反馈回振荡电路的电压会用光电耦合器隔离。大多数 开关电源有待机电路，在待机状态开关电源还在振荡，只是频

29、率比正常工作时要低。有些开关电源很复杂，元件密密麻麻，很多保护和控制电路，在没有技术支持的情况下，维修起来是一件很头疼的事。在我面对这种情况是，首先我会找到开关管及其参与振荡的外围电路，把它从电路中分离出来，看它是否满足振荡的条件，如检测偏置是否正常，正反馈有无故障，还有开关管本身，开关电源有极强大的保护功能，排除后检察控制和保护及负载电路。一方面从输出端取样，经与设定标准进行比较，然后去控制逆变器，改变其频率或脉宽，达到输出稳定，另一方面，根据测试电路提供的资料，经保护电路鉴别，提供控制电路对整机进行各种保护措施。1955 年美国罗耶（GH.Roger)发明的自激振荡推挽晶体管单变压器直流变

30、换器，是实现高频转换控制电路的开端，1957 年美国查赛（Jen Sen)发明了自激式推挽双变压器，1964 年美国科学家们提出取消工频变压器的串联开关电源的设想，这对电源向体积和重量的下降获得了一条根本的途径。到了 1969 年由于大功率硅晶体管的耐压提高，二极管反向恢复时间的缩短等元器件改善，终于做成了 25 千赫的开关电源。目前，开关电源以小型、轻量和高效率的特点被广泛应用于以电子计算机为主导的各种终端设备、通信设备等几乎所有的电子设备，是当今电子信息产业飞速发展不可缺少的一种电源方式。目前市场上出售的开关电源中采用双极性晶体管制成的 100kHz、用 MOSFET 制成的 500kHz

31、 电源，虽已实用化，但其频率有待进一步提高。要提高开关频率，就要减少开关损耗，而要减少开关损耗，就需要有高速开关元器件。然而，开关速度提高后，会受电路中分布电感和电容或二极管中存储电荷的影响而产生浪涌或噪声。这样，不仅会影响周围电子设备，还会大大降低电源本身的可靠性。其中，为防止随开关启-闭所发生的电压浪涌，可采用 R-C 或 L-C 缓冲器，而对由二极管存储电荷所致的电流浪涌可采用非晶态等磁芯制成的磁缓冲器。不过，对 1MHz 以上的高频，要采用谐振电路，以使开关上的电压或通过开关的电流呈正弦波，这样既可减少开关损耗，同时也可控制浪涌的发生。这种开关方式称为谐振式开关。目前对这种开关电源的研究很活跃，因为采用这种方式不需要大幅度提高开关速度就可以在理论上把开关损耗降到零，而且噪声也小，可望成为开关电源高频化的一种主要方式。当前，世界上许多国家都在致力于数兆 Hz 的变换器的实用化研究。