| 摘要 |
A controller generates a drive signal for a converter circuit that includes an active component (i.e., transistor) that is selectively controlled to convert a rectified input to direct current (DC) output. The controller employs an outer feedback loop (based on monitored output voltage of the converter circuit), an inner feedback loop (based on monitored AC input current drawn by the converter circuit), and a pulse width modulator (PWM) to generate the drive signals necessary to generate the desired DC output voltage and to provide power factor correction to the converter circuit. In particular, the inner feedback loop includes an amplifier and a fault protection and clamp circuit. The amplifier has a first input connected to receive a feedback signal representing the monitored AC input current, a second input, and an output that provides a current feedback signal to the PWM. The fault protection and clamp circuit is connected to monitor the voltage at the second input of the PWM and to detect fault conditions associated with the converter circuit, wherein in response to an over-voltage condition at the second input or a detected fault condition the fault protection and claim circuit clamps the current feedback signal provided to the second input of the PWM to a reference value and provides the reference value in feedback to either the first or second input of the amplifier. |
