電器類畢業(yè)設(shè)計外文翻譯----開關(guān)穩(wěn)壓電源-其他專業(yè)-展示頁
2025-01-31 03:21本頁面
【正文】 arantee the switching transistor by the cutoff switches are being 3 more and more normal state, therefore the protection of the setting up of a boot to tie in with the soft start. overcurrent protection When the load shortcircuit, 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 no overcurrent protection device, high power switching transistor may be damaged. Therefore, the switching regulator in the overcurrent protection is monly used. The most economical way is to use simple fuse. As a result of the heat capacity of small transistors, general fuse protection in general can not play a role in the rapid fuse mon 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 overcurrent protection measures brought about by the inconvenience of frequent replacement of fuses. Linear voltage regulator monly used in the protection and current limiting to protect the cutoff in the switching regulator can be applied. However, according to the characteristics of switching regulators, the protection circuit can not directly control the output transistor switches, and overcurrent protection must be converted to pulse output mands to control the modulator to protect the transistor switch. In order to achieve overcurrent protection are generally required sampling resistor in series in the circuit, this will affect the efficiency of power supply, so more for lowpower switching regulator of occasions. In the highpower 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 be converted to overcurrent protection, and undervoltage protection. overvoltage protection Switching regulator39。s input overvoltage protection, including overvoltage protection and output overvoltage protection. Switching regulator is not used in DC power supply voltage regulator and rectifier, 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 overvoltage protection circuit. Using transistors and relays protection circuit. In the circuit, when the input DC power supply voltage higher than the voltage regulator diode breakdown voltage value, the breakdown voltage regulator tube, a current 4 flowing through resistor R, so that V turnon transistor, relay, normally closed contact off open, cut off the input. Voltage regulator voltage regulator which controls the value of Vz = ESrmaxUBE. The polarity of input power with the input protection circuit can be bined with overvoltage protection, polarity protection constitute a differential circuit and overvoltage protection. Output overvoltage protection switching power supply is essential. In particular, for the 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 nonregulated DC power supply voltage value, causing great loss instantaneous. Commonly used method is shortcircuit protection thyristor. The simplest overvoltage protection circuit. When the output voltage is too high, the regulator tube breakdown triggered thyristor turnon, the output shortcircuit, resulting in overcurrent through the fuse 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 thyristor is about 5 ~ 10μs. The disadvantage is that its action is fixed voltage, temperature coefficient, and action points of instability. In addition, the
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