High efficiency and fast response AC-DC voltage converters
View Patent ↗The present invention discloses circuits and methods for high efficiency and fast response AC-DC voltage converters. In one embodiment, an AC-DC voltage converter can include: (i) a first stage voltage converter having an isolated topology with a power factor correction function, where the first stage voltage converter is configured to convert an AC input voltage to a series-connected N branches of first stage voltages, where N is a positive integer of at least two; (ii) a second stage voltage converter having a non-isolated topology, where the second stage voltage converter is configured to convert one of the N branches of the first stage voltages to a second stage voltage; and (iii) where the second stage voltage and a remaining of the N branches of the first stage voltages are configured to be series-connected and converted to a DC output voltage.
1. An AC-DC voltage converter configured to convert an AC input voltage to a DC output voltage, the AC-DC voltage converter comprising:
a) a first stage voltage converter having an isolated topology with a power factor correction function, wherein said first stage voltage converter is configured to convert said AC input voltage to a series-connected N branches of first stage voltages, wherein N is a positive integer of at least two;
b) a second stage voltage converter having a non-isolated topology, wherein said second stage voltage converter is configured to convert one of said N branches of said first stage voltages to a second stage voltage; and
c) wherein said second stage voltage and a remaining of said N branches of said first stage voltages are configured to be series-connected and converted to said DC output voltage at an output terminal of said AC-DC voltage converter.
2. The AC-DC voltage converter of claim 1 , wherein said second stage voltage converter comprises a pulse-width modulation (PWM) control circuit configured to receive said DC output voltage, and to generate a PWM signal configured to control duty cycles of switches in said second stage voltage converter to convert said one branch of said first stage voltages to said second stage voltage.
3. The AC-DC voltage converter of claim 1 , wherein said first stage voltage converter comprises:
a) a rectifier bridge configured to convert said AC input voltage to a DC input voltage;
b) a multi-output isolated converter coupled to said rectifier bridge, wherein said multi-output isolated converter is configured to convert said DC input voltage to said series-connected N branches of said first stage voltages; and
c) a power factor correction (PFC) control circuit configured to maintain said DC input voltage in a same phase as an input current of said PFC control circuit.
4. The AC-DC voltage converter of claim 3 , wherein said multi-output isolated converter comprises one of: a forward converter and a flyback converter.
5. The AC-DC voltage converter of claim 3 , wherein said multi-output isolated converter is controllable by a primary-side control method by detecting an auxiliary voltage of an auxiliary winding of said multi-output isolated converter.
6. The AC-DC voltage converter of claim 3 , wherein said PFC control circuit is configured to utilize a quasi-resonance control method to control a primary-side switch.
7. The AC-DC voltage converter of claim 1 , wherein said non-isolated topology of said second stage voltage converter comprises at least one of: a non-isolated buck regulator, a non-isolated boost regulator, and a non-isolated boost-buck regulator.