Switching power supply overvoltage and undervoltage protection circuit, switching power supply and air conditioner
A technology of switching power supply and protection circuit, which is applied in the direction of emergency protection circuit device, protection against overvoltage, protection against undervoltage or no voltage, etc. problem, to achieve the effect of extending the voltage detection range and realizing the overvoltage protection function
Active Publication Date: 2021-04-30
NINGBO AUX ELECTRIC
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Problems solved by technology
[0005] The problem solved by the present invention is that the voltage detection range of the existing switching power supply is smaller than the working voltage range of the air conditioner, and the problem that both overvoltage protection and undervoltage protection cannot be taken into account
Method used
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[0033] In order to make the above objects, features and advantages of the present invention more comprehensible, specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.
[0034] see figure 1 The structure schematic diagram of the switching power supply protection circuit of the existing air conditioner is shown, the input AC voltage is rectified by the rectifier bridge to obtain the DC voltage V DC , resistor R 1 , R 3 Form a voltage divider circuit.
[0035] Voltage control chip IC 1 The voltage at input pin 2 (BR pin) is sensed by R 3 Voltage across both ends, indirectly detect V DC voltage range. Assume that the internal low voltage threshold of the voltage control chip is V1, and the internal high voltage threshold is V 2 . When V DC below V DC1 =(V 1 / R 3 )*(R 1 +R 3 ), the chip stops working and enters the undervoltage protection state. When V DC higher than V DC2 =(V 2 / R 3 )*(R 1...
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The invention provides a switching power supply overvoltage and undervoltage protection circuit, a switching power supply and an air conditioner. The circuit comprises a voltage detection circuit and a shunt circuit; the voltage detection circuit comprises a first resistor and a third resistor; a first end of the first resistor is connected with the output end of a rectifying circuit, a second end of the first resistor is connected with a first end of the third resistor, and a second end of the third resistor is grounded; a first end of the third resistor is connected with a voltage input pin of a voltage control chip; the shunt circuit comprises a second resistor and a voltage drop element, and the conduction voltage drop of the voltage drop element is greater than the internal low-voltage threshold of the voltage control chip and less than the internal high-voltage threshold of the voltage control chip; the second resistor and the voltage drop element are connected in series and then connected in parallel with the third resistor. According to the invention, the voltage detection range of the voltage control chip can be expanded, so that the under-voltage protection function can be realized, and the overvoltage protection function can also be realized.
Description
technical field [0001] The invention relates to the technical field of air conditioners, in particular to a switching power supply overvoltage and undervoltage protection circuit, a switching power supply and an air conditioner. Background technique [0002] Switching power supply has the advantages of small size, low cost, stable output voltage, and wide input voltage range. At present, switching power supply is mostly used as control power supply in inverter air conditioner control boards, which has gradually replaced the linear transformer solution. [0003] With the continuous improvement of economic level, air conditioners have entered thousands of households. In some remote areas, due to the problem of power supply distance, the user's power supply is often unstable. Too high or too low AC voltage will cause the air conditioner to run abnormally or even burn the air conditioner control panel. Therefore, the switching power supply control chip is equipped with an inpu...
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IPC IPC(8): H02H3/20H02H3/24H02H7/10F24F11/89
CPCH02H3/207H02H3/24H02H7/10F24F11/89
Inventor 陈志强文健
Owner NINGBO AUX ELECTRIC