CONTROL OF POWER CONVERTERS
Control techniques and circuits for resonant power converters and other power converters are described. Control of power converters based on more than one control parameter can provide improved efficiency over a wide operating range. A resonant power converter may have its switching frequency controlled within a narrow band to improve efficiency.
1 . A power module, comprising:
a resonant power converter including:
a switch network having one or more switches; and
a resonant tank circuit; and
a controller configured to control the resonant power converter, the controller being configured to switch the one or more switches of the switch network at a switching frequency, the controller being configured to sub-modulate the resonant power converter on and off at a second frequency lower than the switching frequency with a sub-modulation duty ratio, the controller being configured to control the resonant power converter by varying the switching frequency and the sub-modulation duty ratio.
2 . The power module of claim 1 , wherein the controller is configured to control the resonant power converter based on an input to the resonant power converter.
3 . The power module of claim 2 , wherein the controller is configured to vary the switching frequency based on the input to the resonant power converter.
4 . The power module of claim 1 , wherein the controller is configured to control the resonant power converter based on an output of the resonant power converter.
5 . The power module of claim 4 , wherein the controller is configured to vary the sub-modulation duty ratio based on the output of the resonant power converter.
6 . The power module of claim 5 , wherein the controller is configured to vary the sub-modulation duty ratio using hysteresis.
7 . The power module of claim 5 , wherein the controller is configured to vary the switching frequency based on an input to the resonant power converter.
8 . The power module of claim 1 , wherein the controller is configured to vary the switching frequency based on an input and/or output of the resonant power converter, and the controller is configured to vary the sub-modulation duty ratio based on an input and/or output of the resonant power converter.
9 . The power module of claim 8 , wherein the controller is configured to vary the switching frequency based on the input to the resonant power converter and the output of the resonant power converter.
10 . The power module of claim 8 , wherein the controller is configured to vary the sub-modulation duty ratio based on the input to the resonant power converter and the output of the resonant power converter.
11 . The power module of claim 1 , wherein the controller is configured to vary the switching frequency based on the sub-modulation duty ratio.
12 . The power module of claim 1 , wherein the controller is configured to vary the sub-modulation duty ratio based on the switching frequency.
13 . The power module of claim 1 , wherein the power module is configured to receive an AC line voltage.
14 . The power module of claim 13 , wherein the power module does not have a power factor correction circuit.
15 . The power module of claim 13 , wherein the power module is configured to receive an AC line voltage with a magnitude of between 100 V and 240 V RMS.
16 . The power module of claim 1 , wherein the power module is a power adapter.
17 . The power module of claim 1 , wherein the resonant power converter comprises an LLC converter or a phi-2 converter.
18 . The power module of claim 1 , wherein the switching frequency is at least 500 kHz and below 300 MHz and the second frequency is at least 20 kHz.
19 . A controller for a resonant power converter including a switch network having one or more switches and a resonant tank circuit, the controller comprising:
circuitry configured to control the resonant power converter to switch the one or more switches of the switch network at a switching frequency, to sub-modulate the resonant power converter on and off with a sub-modulation duty ratio at a second frequency lower than the switching frequency, and to control the resonant power converter by varying the switching frequency and the sub-modulation duty ratio
20 . A method of controlling a resonant power converter including a switch network having one or more switches and a resonant tank circuit, the method comprising:
switching the one or more switches of the switch network at a switching frequency;
sub-modulating the resonant power converter on and off with a sub-modulation duty ratio at a second frequency lower than the first frequency; and
varying the switching frequency and the sub-modulation duty ratio of the resonant power converter.
21 . A power module, comprising:
a power converter having one or more switches; and
a controller configured to control the power converter, the controller being configured to switch the one or more switches at a switching frequency, the controller being configured to sub-modulate the power converter on and off with a sub-modulation duty ratio at a second frequency lower than the switching frequency, the controller being configured to control the power converter by varying the sub-modulation duty ratio as a first control parameter and by varying a second control parameter of the power converter.
22 . The power module of claim 21 , wherein the second control parameter comprises a second duty ratio.
23 . A controller for a power converter, the power converter having one or more switches, the controller comprising:
circuitry configured to switch the one or more switches at a switching frequency, to sub-modulate the power converter on and off with a sub-modulation duty ratio at a second frequency lower than the switching frequency, and to control the power converter by varying the modulation duty ratio as a first control parameter and by varying a second control parameter of the power converter.
24 . The controller of claim 23 , wherein the second control parameter is duty ratio D.
25 . A method of controlling a power converter having one or more switches, the method comprising:
switching the one or more switches at a first frequency;
sub-modulating the power converter on and off with a sub-modulation duty ratio at a second frequency lower than the switching frequency; and
controlling the power converter by varying the sub-modulation duty ratio as a first control parameter and by varying a second control parameter of the power converter.