We conducted detailed analysis of the hazards and prote […]
We conducted detailed analysis of the hazards and protective measures taken by different types of circuits on LED downlight power:
1. LED downlight power supply for overvoltage circuit
If the current is short-circuited, the voltage across the current-sense resistor drops to zero. Once the setpoint is not zero, the regulator will cause the output voltage to rise sharply to the maximum value, which is dangerous when the load connection is poor. For loads such as LED semiconductor refrigeration, when overvoltage occurs, the primary task is to protect the load, and secondly to protect the switching power tube.
2. LED downlight power supply for overcurrent circuit
When there is an unexpected situation such as load short circuit, overload or control circuit failure, the current flowing through the switch tube will be too large, so that the power consumption of the tube will increase and heat. If there is no overcurrent protection device, the high power switch tube will There is a possibility of damage, and the failure of the regulating circuit may cause overcurrent damage to the LED downlight.
3. LED downlight power supply for straight-through circuit
The half-bridge and the full-bridge are common expansion structures of the switching power supply. The straight-through circuit poses a great threat to the switch. The straight-through is a phenomenon in which two transistors of the same bridge arm are simultaneously turned on at the same time. During the commutation period, the switching power supply is susceptible to interference and causes a straight-through. Excessive through current can damage the power electronics used for the inverter. Once there is a straight-through phenomenon, it is necessary to detect and immediately turn off the drive as soon as possible to prevent the PN junction of the switching device from accumulating excessive heat and burning out.
4. LED downlight power supply for overshoot circuit
The steady current switching power supply is prone to current overshoot when it is turned on and off. The load such as the LED downlight power supply is not allowed for the current overshoot of the ms stage. The impact of the instantaneous large current may damage the LED downlight device. Therefore, current overshoot must be strictly prevented.