Power supply protection circuit and method
A power supply protection and circuit technology, applied in the field of power supply, can solve problems such as overvoltage and overheating damage of thin-film X capacitors, overheating damage of bypass diodes, and failure of power supply modules, achieving low-cost maintenance, high detection reliability, and realization of low cost effect
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Embodiment 1
[0023] like figure 1 Shown is a block diagram of the power supply protection circuit of the present invention, including a film capacitor capacity decay detection unit, an ADC and a signal processing unit 20, and a fault protection unit 30. The film capacitor capacity decay detection unit includes a voltage sampling unit 00 and a peak voltage detection unit 10. The voltage sampling unit 00 samples the voltage across the film capacitor in the power supply in real time, and inputs the voltage to the peak voltage detection unit 10 . The peak voltage detection unit 10 detects the peak voltage at both ends of the film capacitor from the sampled voltage, and inputs it into the ADC and the signal processing unit 20 . The ADC and signal processing unit 20 performs analog-to-digital conversion on the peak voltage, compares the obtained peak voltage value with the set threshold, and controls the fault protection unit 30 to implement fault protection for the power supply equipment accord...
Embodiment 2
[0025] like figure 2 Shown is the circuit diagram of the peak voltage detection unit. Us is the sampling voltage at both ends of the film capacitor, which is sampled by the voltage sampling circuit, and the voltage sampling circuit can be realized by adopting the existing technology. The sampling voltage Us is divided by the resistors R11 and R12, and enters the non-inverting terminal of the op amp U1A. The diode D11 is connected in parallel to the resistor R12 to clamp the negative voltage at the non-inverting terminal. Considering the resistance power and voltage requirements, the resistance R11 is equivalently obtained through multiple series resistances. The output of the operational amplifier U1A is connected to the anode of a small signal diode D12, the cathode of the diode D12 is connected to the inverting terminal of the operational amplifier U1A one way, and one way is connected to the ADC and the signal processing unit through the filter circuit composed of the res...
Embodiment 3
[0032] as attached Figure 4 As shown, taking three-phase PFC as an example, implementing fault protection for power supply equipment according to the comparison result between the detected peak voltage value and the set threshold value includes the following steps:
[0033] Determine whether the peak voltage Upka, Upkb, Upkc (peak voltage of the three-phase X film high-frequency capacitor) exceeds the upper limit Upkmax:
[0034] When the detection values of Upka, Upkb, and Upkc are greater than Upkmax, the processor chip U2 outputs a fault shutdown signal Fault at a high level, and the PWM drive buffer chip U3 is disabled, and a fault protection shutdown is implemented on the power supply device.
[0035] Determine whether the peak voltage Upka, Upkb, Upkc exceeds the rated value Upknor:
[0036] When the detection values of Upka, Upkb, and Upkc are greater than Upknor and less than or equal to the upper limit value Upkmax, the processor chip U2 outputs a fault shutdown...
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