APPARATUS AND METHOD FOR PROTECTING SECONDARILY OVER VOLTAGE

摘要

PURPOSE: An apparatus and a method for protecting secondarily over voltage are provided to prevent the damage of circuits due to the over voltage by using the secondary over voltage protection device instead of the primary over voltage protection device having a defect. CONSTITUTION: An apparatus for protecting secondarily over voltage includes an AC/DC converter(21), a PWM control signal output unit(28), a power factor improvement unit(22), a first over voltage detector(26), a first over voltage protection unit(27), a second over voltage detector(24), and a second over voltage protection unit(25). The AC/DC converter(21) is used for converting AC to DC. The PWM control signal output unit(28) generates a PWM control signal as a switching signal. The power factor improvement unit(22) improves a power factor of the converted DC according to the PWM control signal. The first over voltage detector(26) is used for outputting the first over voltage detection signal when the voltage of the DC power of the power factor improvement unit is higher than the first threshold voltage. The first over voltage protection unit(27) prevents the first over voltage according to the first over voltage detection signal. The second over voltage detector(24) is used for outputting the second over voltage detection signal when the voltage of the DC power of the AC/DC converter is higher than the second threshold voltage. The second over voltage protection unit(25) prevents the second over voltage according to the second over voltage detection signal.