Light-Load Recovery in a Multi-Level Converter
AssigneepSemi Corporation
InventorGregory Szczeszynski
Life of this patent
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Abstract
Circuits and methods that solve the light-load problem of a multi-level converter by generating a ripple signal in the control loop of the multi-level converter that causes a large output current ripple during light load conditions. This added current ripple does not change the average output current but does create a temporary positive and negative current that can be used to balance and charge/discharge the fly capacitors of the multi-level converter. An alternative approach is to add extra switching cycles for the fly capacitors when the output ripple current crosses zero.
Claims20
A multi-level converter including:
- (a) an M-level converter cell configured to transform an input voltage applied to an input terminal to an output voltage on an output terminal in response to control inputs;
- (b) a controller coupled to the M-level converter cell, the controller configured to monitor a node of the M-level converter cell and to generate the control inputs to the M-level converter cell in response to such monitoring;
- and
- (c) a sub-harmonic generator coupled to the controller and configured to selectively inject a sub-harmonic signal into a signal path of the controller.
A multi-level converter including:
- (a) an M-level converter cell that includes:
- (1) an input terminal;
- (2) a set of switches series-coupled between a voltage source and a reference voltage;
- (3) an output terminal coupled to an innermost pair of the set of switches and configured to be coupled to an inductor;
- (4) switch control inputs coupled to the set of switches;
- and
- (5) at least one fly capacitor coupled in series with certain respective switches and in parallel with switches situated in between the respective switches;
- wherein the M-level converter cell is configured to transform an input voltage applied to the input terminal to an output voltage on the output terminal in response to control signals on the switch control inputs;
- (b) a controller coupled to the inductor and to the switch control inputs, the controller configured to monitor the output of the M-level converter cell and dynamically generate a set of switch control input values to the M-level converter cell in response to such monitoring;
- and
- (c) a sub-harmonic signal generator coupled to the controller and configured to selectively inject a sub-harmonic signal into a signal path of the controller.
Dependencies are inferred from the claim text.