Current fed active clamp forward boost converter
AssigneeApple Inc.
InventorBogdan T. Bucheru
Life of this patent
Estimating the term…
Abstract
A current fed active clamp forward boost (CAFB) converter can include a primary coil coupled to an input voltage and a main switch, an input choke serially coupled with the primary coil, and a clamp switch coupled to the primary coil, input choke, and a clamp capacitor. The main switch may operate to regulate an output voltage of the converter. The clamp switch may operate alternately with respect to the main switch, and the auxiliary switch may selectively couple a DC bus voltage to the primary coil. The converter can be operated in a CAFB mode if the input voltage is greater than the boost voltage threshold or in a current fed active clamp forward (CAF) mode if the input voltage is not greater than the boost voltage threshold.
Claims21
A current fed active clamp forward boost converter comprising:
- a primary coil coupled to a rectified input voltage;
- an input choke serially coupled between the primary coil and a main switch;
- and
- a clamp switch electrically coupled across the input choke via a clamp diode, the clamp switch being further coupled to a first terminal of a clamp capacitor having a second terminal coupled to a DC bus of the converter, the DC bus being selectively decouplable from the rectified input voltage and the primary coil by an auxiliary switch;
- wherein:
- the main switch is configured to be operated to regulate a voltage appearing at an output of the converter;
- the clamp switch is configured to operate alternately with respect to the main switch;
- and
- the auxiliary switch is configured to selectively couple the DC bus voltage to the primary coil when the rectified input voltage is greater than a boost voltage threshold.
(canceled)
The current fed active clamp forward boost converter of claim 1 wherein the choke coil is integral with the primary coil. (original) The current fed active clamp forward boost converter of claim 6 wherein the transformer is a high leakage transformer.
A method of operating a current fed active clamp forward boost (CAFB) converter, the CAFB converter comprising a main switch, a clamp switch, and an auxiliary switch, the method comprising:
- comparing an input voltage of a CAFB converter to a boost voltage threshold;
- and
- operating the main switch, the clamp switch, and the auxiliary switch of the CAFB converter in a CAFB mode if the input voltage is greater than the boost voltage threshold, wherein operating the main switch, the clamp switch, and the auxiliary switch of the CAFB converter in the CAFB mode comprises operating the auxiliary switch of the CAFB converter to selectively couple a DC bus voltage of the converter to a primary coil of the CAFB converter, wherein operating the auxiliary switch of the CAFB converter to selectively couple a DC bus voltage of the converter to a primary coil of the CAFB converter comprises cycling through a sequence of switching states, the sequence of switching states comprising:
- a first switching state, commencing when the main switch is turned on, the clamp switch is turned off, and the auxiliary switch is on;
- a second switching state commencing when the auxiliary switch is opened with the main switch remaining on and the clamp switch remaining off;
- a third switching state commencing when the main switch is turned off and the clamp switch is turned on, with the auxiliary switch remaining off;
- and
- a fourth switching state commencing when the auxiliary switch is turned on, with the main switch remaining off, and the clamp switch remaining on.
11-12. (canceled)
(canceled)
A method of operating a current fed active clamp forward boost (CAFB) converter, the CAFB converter comprising a main switch, a clamp switch, and an auxiliary switch, the method comprising:
- comparing an input voltage of a CAFB converter to a boost voltage threshold;
- and
- operating the main switch, the clamp switch, and the auxiliary switch of the CAFB converter in a current fed active clamp forward (CAF) mode if the input voltage is not greater than the boost voltage threshold;
- wherein operating the CAFB converter in the CAF mode comprises cycling through a sequence of switching states, the sequence of switching states comprising:
- a first switching state, commencing when a main switch is turned on, a clamp switch is turned off, and the auxiliary switch is on;
- a second switching state commencing when the main switch is turned off, the clamp switch is turned on, with the auxiliary switch remaining on;
- and
- a third switching state commencing when a current through a primary coil of the CAFB converter reverses polarity, while main switch remains off, and the clamp switch and the auxiliary switch remain on.
Dependencies are inferred from the claim text.