发布时间 : 星期一 文章外文翻译电气工程及自动化更新完毕开始阅读
of thirstier is about 5 ~ 10μs. The disadvantage is that its action is fixed voltage, temperature coefficient, and action points of instability. In addition, there 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
Output 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 the 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-switching 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 short-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 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-temperature 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 circuit 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 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 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 \can be used as directed circuit temperature. 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 temperature 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. It 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 protection
Protection technology to future trends is computerized, network, intelligent, protection and control, measurement and data communications integration development.
1) Computerized
Along with the rapid development of computer hardware, microcomputer protection and development in hardware. Former north electricity institute 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 don't bus module, performance greatly improve module structure, widely used. 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 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 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 32-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, 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）Network
Power 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 data processing function, strong communication ability, and other protection and control devices and the whole system by sharing network dispatching data, information and network resources, the ability to program in a high-level language, etc. This requires microcomputer protection device is equivalent to a PC. In the early development of computer to protect, once thought to use a small computer finish relay protection device. Due to the large size, then minicomputers high cost and reliability of this idea is not reality. Now, with microprocessor-based protection function of similar size, speed, work-managing machine greatly exceed the storage capacity of minicomputer, therefore, make use of the relay protection sets polymerizing-kettle time is ripe, this is the development direction of the microcomputer relay protection.
Tianjin University has developed with microprocessor-based protection device with an identical structure reform polymerizing-kettle of relay protection device. This device has several advantages: (1) 486PC machine can meet all the functions of the current and future demands of microcomputer protection function. (2) dimension and structure and the current protection device, exquisite workmanship, shockproof, prevent overheating, preventing electromagnetic interference ability is strong, can run in very bad working environment, cost can be accepted. (3) using STD bus or PC bus, hardware modular, for different protection can be arbitrarily choose different modules, flexible configuration, easy extension.
The microcomputer relay protection device, computerized is irreversible trend. But how to better satisfy power system, how to further improve the reliability of the relay protection, and how to obtain more economic benefit and social benefit, still must specifically in-depth research.
820 networks
The computer network information and data communication tool has become the mainstay of the information age, make human production technology and social life of the fundamental changes have taken place. It is deeply affect all industries, as well as various industry provides powerful means of communication. So far, in addition to the differential protection disoperation and protection of the relay protection device, all can only protect the
electricity installation reaction. Protection function is limited, reduce accidents resection fault components. This is mainly due to the lack of data communications. Strong Foreign had put forward the concept of protection system, which was mainly refers to the safety automatic device. Because of the relay protection function not only fault components and limit resection impact accident (this is to ensure priority), the safe and stable operation of the whole system. This requires each protection unit can be altogether I、Conclusion
Discussed above in the switching regulator of a variety of conservation, and introduces a number of specific ways to achieve. Of a given switching power supply is concerned, but also protection from the whole to consider the following points:
1) The switching regulator used in the switching transistor in the DC security restrictions on the work of regional work. The transistor switches selected by the manual available transistors get DC safe working area. According to the maximum collector current to determine the input value of over-current protection. However, the instantaneous maximum value should be converted to the average current. At rated output current and output voltage conditions, the switch of the dynamic load line does not exceed a safe working area DC maximum input voltage, input over-voltage protection is the voltage value.
2) The switching regulator output limit given by the technical indicators within. Work within the required temperature range, the switching regulator's output voltage, the lower limit of the output is off, due to the voltage value of voltage protection. Over-current protection can be based on the maximum output current to determine. False alarm in order not to protect the value of a certain margin to remain appropriate.
3) From the above two methods to determine the protection after the power supply device in accordance with the needs of measures to determine the alarm. Measures the general alarm sound and light alarm two police. Voice of the police applied to more complex machines, power supply parts and do not stand out in a place, it can give staff an effective warning of failure; optical Police instructions can be eye-catching and fault alarm and pointed out that the fault location and type. Protection measures should be protected as to determine the location. In the high-power, multi-channel power supply, always paying, DC circuit breakers, relays, etc. high-sensitivity auto-protection measures, to cut off the input power supply to stop working the system from damage. Through the logic control circuit to make the appropriate program cut-off switch transistor is sensitive it is convenient and economic. This eliminated large, long response time, the price of your high-power relay or circuit breaker.
4) The power of putting in the protection circuit will be affected after the reliability of the system, for which want to protect the reliability of the circuit itself is higher in order to