直流开关稳压电源的保护技术毕业论文 外文翻译中英文.doc

1、题 目： 直流开关稳压电源的保护技术 DC Switching Power Supply Protection TechnologyAbstract: The DC switching power supply protection system, protection system design principles and machine protection measures, an analysis of switching power supply in the range of protected characteristics and its design methodology

2、, introduced a number of practical protection circuit.Keywords: switching power supply protection circuit system designA、IntroductionDC switching regulator used in the price of more expensive high-power switching devices, the control circuit is also more complex, In addition, the load switching regu

3、lators are generally used a large number of highly integrated electronic systems installed devices. Transistors and integrated device tolerance electricity, less heat shocks. Switching Regulators therefore should take into account the protection of voltage regulators and load their own safety. Many

4、different types of circuit protection, polarity protection, introduced here, the program protection, over-current protection, over-voltage protection, under-voltage protection and over-temperature protection circuit. Usually chosen to be some combination of protection, constitutes a complete protect

5、ion system.B、Polarity protectionDC switching regulator input is generally not regulated DC power supply. Operating errors or accidents as a result of the situation will take its wrong polarity; switching power supply will be damaged. Polarity protection purposes, is to make the switching regulator o

6、nly when the correct polarity is not connected to DC power supply regulator to work at. Connecting a single device can achieve power polarity protection. Since the diode D to flow through switching regulator input total current, this circuit applied in a low-power switching regulator more suitable.

7、Power in the larger occasion, while the polarity protection circuit as a procedure to protect a link, save the power required for polarity protection diodes, power consumption will be reduced. In order to easy to operate, make it easier to identify the correct polarity or not, collect the next light

8、.C、Procedures to protect Switching power supply circuit is rather complicated, basically can be divided into low-power and high-power part of the control part of the switch. Switch is a high-power transistors, for the protection of the transistor switch is turned on or off power safety, we must firs

9、t modulator, amplifier and other low-power control circuit. To this end, the boot to ensure the correct procedures. Switching Regulators generally take the input of a small inductor, the input filter capacitor. Moment in the boot, filter capacitor will flow a lot of surge current, the surge current

10、can be several times more than the normal input current. Such a large surge current may contact the general power switch or relay contact melting, and the input fuse. In addition, the capacitor surge current will damage to shorten the life span of premature damage. To this end, the boot should be ac

11、cess to a current limiting resistor, through the current limiting resistor to capacitor charging. In order not to make the current limiting resistor excessive power consumption, thus affecting the normal switching regulator, and the transient process in the boot after a short period then automatical

12、ly relays it to DC power supply directly to the switching regulator power supply. This circuit switching regulator called a soft start circuit.Switching regulator control circuit of the logic components required or op-amp auxiliary power supply. To this end, the auxiliary power supply must be in the

13、 switch circuit. This control circuit can be used to ensure the boot. Normal boot process is: to identify the polarity of input power, voltage protection procedures boot auxiliary power supply circuit and through current limiting resistor R of the switching regulator input capacitor C charge modulat

14、ion switching regulator circuit, short-circuit current limiting resistor stability switching regulator.In the switching regulator, the machines just because the output capacitance, and charge to the rated output voltage value of the need for a certain period of time. During this time, sampling the o

15、utput amplifier with low input voltage sampling, closed-loop regulation characteristics of the system will force the switching of the transistor conduction time lengthened, so that switching transistor during this period will tend to continuous conduction, and easily damaged. To this end, the requir

16、ements of this paragraph in the boot time, the switch to switch the output modulation circuit transistor base drive signal of the pulse width modulation, can guarantee the switching transistor by the cut-off switches are becoming more and more normal state, therefore the protection of the setting up

17、 of a boot to tie in with the soft start.D、Over-current protection When the load short-circuit, overload control circuit failure or unforeseen circumstances, such as would cause the flow of switching voltage regulator transistor current is too large, so that increased power tubes, fever, if there is

18、 no over-current protection device, high power switching transistor may be damaged. Therefore, the switching regulator in the over-current protection is commonly used. The most economical way is to use simple fuse. As a result of the heat capacity of small transistors, general fuse protection in gen

19、eral can not play a role in the rapid fuse common fuse. This method has the advantage of the protection of vulnerable, but it needs to switch transistor in accordance with specific security requirements of the work area to select the fuse specifications. This disadvantage is over-current protection

20、measures brought about by the inconvenience of frequent replacement of fuses.Linear voltage regulator commonly used in the protection and current limiting to protect the cut-off in the switching regulator can be applied. However, according to the characteristics of switching regulators, the protecti

21、on circuit can not directly control the output transistor switches, and over current protection must be converted to pulse output commands to control the modulator to protect the transistor switch. In order to achieve over-current protection are generally required sampling resistor in series in the

22、circuit, this will affect the efficiency of power supply, so more for low-power switching regulator of occasions. In the high-power switching power supply, by taking into account the power consumption should be avoided as far as possible access to the sampling resistor. Therefore, there will usually

23、 be converted to over-current protection, and under-voltage protection. E、Over-voltage protection Switching regulators input over-voltage protection, including over-voltage protection and output over-voltage protection. Switching regulator is not used in DC power supply voltage regulator and rectifi

24、er, such as battery voltage, if too high, so switching regulator is not working properly, or even damage to internal devices, therefore, it is necessary to use the input over-voltage protection circuit. Using transistors and relays protection circuit.In the circuit, when the input DC power supply vo

25、ltage higher than the voltage regulator diode breakdown voltage value, the breakdown voltage regulator tube, a current flowing through resistor R, so that V turn-on transistor, relay, normally closed contact off open, cut off the input. Voltage regulator voltage regulator which controls the value of

26、 Vs. = Earwax-UBE. The polarity of input power with the input protection circuit can be combined with over-voltage protection, polarity protection constitute a differential circuit and over voltage protection. Output over-voltage protection switching power supply is essential. In particular, for the

27、 5V output of the switching regulator, it is a lot of load on a high level of integration of the logic device. If at work, switching regulator sudden damage to the switch transistor, the output potential may be increased immediately to the importation of non-regulated DC power supply voltage value,

28、causing great loss instantaneous. Commonly used method is short-circuit protection thirsted. The simplest over-voltage protection circuit. When the output voltage is too high, the regulator tube breakdown triggered thirstier turn-on, the output short-circuit, resulting in over-current through the fu

29、se or circuit protective device to cut off the input to protect the load. This circuit is equivalent to the response time of the opening time of thirstier is about 5 10s. The disadvantage is that its action is fixed voltage, temperature coefficient, and action points of instability. In addition, the

30、re is a voltage regulator control parameters of the discrete, model over-voltage start-up the same but has different values, difficult to debug. Esc a sudden increase in output voltage, transistors V1, V2 conduction, the thruster conduction. Reference voltage Vs. by type.F、Under-voltage protection O

31、utput voltage below the value to reflect the input DC power supply, switching regulator output load internal or unusual occurrence. Input DC power supply voltage drops below the specified value would result in switching regulator output voltage drops, the input current increases, not only endanger t

32、he switching transistor, but also endanger the input power. Therefore, in order to set up due to voltage protection. Due to simple voltage protection. When no voltage regulator input normal, ZD breakdown voltage regulator tube, transistors V conduction, the relay action, contact pull-in, power-switc

33、hing regulator. When the input below the minimum allowable voltage value, the regulator tube ZD barrier, V cut-off, contact Kai-hop, switching regulator can not work. Internal switching regulator, as the control switch transistor circuit disorders or failure will decrease the output voltage; load sh

34、ort-circuit output voltage will also decline. Especially in the reversed-phase step-up or step-up switching regulator DC voltage of the protection due to over-current protection with closely related and therefore more important. Implementation of Switching Regulators in the termination of the output

35、 voltage comparators.Normally, there is no comparator output, once the voltage drops below the allowable value in the comparator on the flip, drive alarm circuit; also fed back to the switching regulator control circuit, so that switching transistor cut-off or cut off the input power. G、Over-tempera

36、ture protection Switching regulator and the high level of integration of light-weight small volume, with its unit volume greatly increased the power density, power supply components to its work within the requirements of the ambient temperature is also a corresponding increase. Otherwise, the circui

37、t performance will deteriorate premature component failure. Therefore, in high-power switching regulator should be set up over-temperature protection. Relays used to detect the temperature inside the power supply temperature, when the internally generated power supply overheating, the temperature of

38、 the relay on the action, so that whole circuit in a warning alarm, and the realization of the power supply over-temperature protection. Temperature relay can be placed in the vicinity of the switching transistor, the general high-power tube shell to allow the maximum temperature is 75 , adjust the

39、temperature setting to 60 . When the shell after the temperature exceeds the allowable value to cut off electrical relay on the switch protection. Semiconductor switching device thermal hot thirstier, in the over-temperature protection, played an important role. It can be used as directed circuit te

40、mperature. Under the control of p-hot-gate thirstier (TT102) characteristics, by RT value to determine the temperature of the device turn-on, RT greater the temperature the lower the turn-on. When placed near the power switching transistor or power device, it will be able to play the role of tempera

41、ture instructions. When the power control the temperature of the shell or the internal device temperature exceeds the allowed value, the heat conduction thirstier on, so that LED warning light. If the opt coupler with, would enable the whole circuit alarm action to protect the switching regulator. I

42、t can also be used as a power transistor as the over-temperature protection, crystal switch the base current by n-type gate control thirstier TT201 thermal bypass, cut-off switch to cut off the collector current to prevent overheating.H、The future development of relay protectionProtection technology

43、 to future trends is computerized, network, intelligent, protection and control, measurement and data communications integration development.1) ComputerizedAlong with the rapid development of computer hardware, microcomputer protection and development in hardware. Former north electricity institute

44、of computer line protection hardware has experienced three development stages: from eight single CPU structure of the microcomputer relay protection, less than 5 years time to develop more CPU structure, and to develop the large dont bus module, performance greatly improve module structure, widely u

45、sed. Huazhong university of science and technology development of microcomputer protection from 8 bits CPU, is the core part in polymerizing-kettle development based on 32-bit microcomputer protection.Nanjing institute of electrical automation began a 16-bit CPU is developed on the basis of computer

46、 line protection, has been widespread in the study, also protect the hardware system 32 bits. The development of southeast university computer hardware and equipment to protect and improve through a lot. Tianjin university is a start with more than 16 bits CPU developed on the basis of computer line

47、 protection, which began in 1988 study 32-bit digital signal processor (DSP) for the protection and control, measuring devices, microcomputer integrated with Zhuhai jin electrical automation equipment company developed into a fully functional 32-bit big modules, a module is a small computer. Using 3

48、2-bit microcomputer chip is not only because the accuracy and precision of the A/D converter by the resolution limit, more than 16 when converting speed and cost is unacceptable, More important is the 32-bit microcomputer chip with high integrity, high frequency and computing speed and large space,

49、rich addressing the command system and more input output. The CPU registers, data bus, the address bus are 32-bit memory management function, and memory protection function and tasks, and the conversion function will Cache (Cache) and floating-point components are integrated in the CPU.2）NetworkPower system of microcomputer protection requirement, besides improving the basic function of protection, also should have the capacity of the fault information and data storage space, long-term fast