Patent ID: 9692314
Date: 2017-06-27
CPC Classifications: G01R,H02M

Claim:
1. A detection circuit for a three-phase AC-to-AC power converter, the three-phase AC-to-AC power converter having three input ends that are configured to receive respectively a first-phase AC input power signal, a second-phase AC input power signal and a third-phase AC input power signal from a three-phase AC power source, said detection circuit comprising: a voltage divider circuit for generating a divided voltage, and having three AC input terminals that are used to be coupled respectively to the input ends of the three-phase AC-to-AC power converter, a DC input terminal that is used to receive a predetermined first reference voltage from a DC voltage source, and a circuit output terminal at which the divided voltage is generated; and a comparator for generating a detection signal, and having a non-inverting input terminal that is coupled to said circuit output terminal of said voltage divider circuit, an inverting input terminal that is used to receive a predetermined second reference voltage, and a comparator output terminal at which the detection signal is generated; wherein, when at least one of the first-, second- and third-phase AC input power signals from the three-phase AC power source is received at respective one(s) of said AC input terminals of said voltage divider circuit, said voltage divider circuit generates the divided voltage at said circuit output terminal thereof based on the predetermined first reference voltage and said at least one of the first-, second- and third-phase AC input power signals, the divided voltage being greater than the predetermined second reference voltage during an active period of each of said at least one of the first-, second- and third-phase AC input power signals, such that the detection signal outputted by said comparator has a duty cycle associated with a combined duty cycle of said at least one of the first-, second- and third-phase AC input power signals.