Reduced common mode voltage emission converter
Power systems including converters that exhibit reduced common mode voltage emissions are described. In one example, a power converter system includes an input and an output, a multi-level switch bridge coupled between the input and the output, an input capacitor branch coupled across the input, an output capacitor branch coupled across the output, and a controller configured to generate switching control signals for the multi-level buck-boost switch bridge. The multi-level switch bridge also includes a plurality of inductors in one example. In one case, a quadrangular or quadrangle control mode can be relied upon to switch the multi-level switch bridge, to minimize the ripple in the inductors, achieve zero voltage switching, reduce common mode electromagnetic interference emission by the converter, and for other benefits.
1 . A power converter system, comprising:
an input and an output;
a multi-level buck-boost switch bridge coupled between the input and the output, the multi-level buck-boost switch bridge comprising:
a plurality of inductors;
an input leg of four input-side switches coupled in series across the input, the input leg of four input-side switches comprising a first input-side switch, a second input-side switch, a third input-side switch, and a fourth input-side switch; and
an output leg of four output-side switches coupled in series across the output, the output leg of four output-side switches comprising a first output-side switch, a second output-side switch, a third output-side switch, and a fourth output-side switch;
an input capacitor branch coupled across the input;
an output capacitor branch coupled across the output; and
a controller configured to implement a quadrangular control mode in which a switching cycle having a period is divided into four sequential sub-periods comprising a first sub-period, a second sub-period, a third sub-period, and a fourth sub-period, wherein:
during the first sub-period of the switching cycle, the first input-side switch, the fourth input-side switch, the second output-side switch, and the third output-side switch are turned on while the second input-side switch, the third input-side switch, the first output-side switch, and the fourth output-side switch are turned off;
during the second sub-period of the switching cycle, the first input-side switch, the fourth input-side switch, the first output-side switch, and the fourth output-side switch are turned on while the second input-side switch, the third input-side switch, the second output-side switch, and the third output-side switch are turned off;
during the third sub-period of the switching cycle, the second input-side switch, the third input-side switch, the first output-side switch, and the fourth output-side switch are turned on while the first input-side switch, the fourth input-side switch, the second output-side switch, and the third output-side switch are turned off;
during the fourth sub-period of the switching cycle, the second input-side switch, the third input-side switch, the second output-side switch, and the third output-side switch are turned on while the first input-side switch, the fourth input-side switch, the first output-side switch, and the fourth output-side switch are turned off; and
each of the four sequential sub-periods involves at least four switches being concurrently turned on to actively regulate power transfer through the plurality of inductors.
2 . The power converter system according to claim 1 , wherein one or more switches among the four input-side switches of the input leg and the four output-side switches of the output leg comprise III-Nitride.
3 . The power converter system according to claim 1 , wherein the plurality of inductors are each coupled, at one end, between respective nodes among the four input-side switches of the input leg and, at another end, between respective nodes among the four output-side switches of the output leg.
4 . The power converter system according to claim 1 , wherein the input leg of four input-side switches comprises the first input-side switch coupled in series with the second input-side switch, the second input-side switch coupled in series with the third input-side switch, and the third input-side switch coupled in series with the fourth input-side switch.
5 . The power converter system according to claim 4 , wherein the output leg of four output-side switches comprises the first output-side switch coupled in series with the second output-side switch, the second output-side switch coupled in series with the third output-side switch, and the third output-side switch coupled in series with the fourth output-side switch.
6 . The power converter system according to claim 5 , wherein:
the input capacitor branch comprises two input capacitors coupled in series across the input; and
the output capacitor branch comprises two output capacitors coupled in series across the output.
7 . The power converter system according to claim 6 , wherein:
a center input capacitor branch node between the two input capacitors of the input capacitor branch is coupled to a center input leg node between the second input-side switch and the third input-side switch of the input leg of four input-side switches.
8 . The power converter system according to claim 6 , wherein:
a center output capacitor branch node between the two output capacitors of the output capacitor branch is coupled to a center output leg node between the second output-side switch and the third output-side switch of the output leg of four output-side switches.
9 . The power converter system according to claim 5 , wherein:
a first inductor among the plurality of inductors is coupled, at one end, between the first input-side switch and the second input-side switch of the input leg of four input-side switches and, at another end, between the first output-side switch and the second output-side switch of the output leg of four output-side switches; and
a second inductor among the plurality of inductors is coupled, at one end, between the third input-side switch and the fourth input-side switch of the input leg of four input-side switches and, at another end, between the third output-side switch and the fourth output-side switch of the output leg of four output-side switches.
10 . The power converter system according to claim 9 , wherein the first inductor and the second inductor are magnetically coupled.
11 . The power converter system according to claim 5 , further comprising a midpoint bridge connection between the input leg of four input-side switches and the output leg of four output-side switches.
12 . The power converter system according to claim 1 , further comprising a midpoint bridge connection coupled between the input and the output.
13 . The power converter system according to claim 1 , wherein the controller is further configured to vary duty cycles of the first sub-period, the second sub-period, the third sub-period, and the fourth sub-period based on feedback metrics comprising at least one of an output voltage and an output current.
14 . The power converter system according to claim 1 , wherein the controller is further configured to generate drive control signals for sequentially activating switch pairs during the four sequential sub-periods according to the quadrangular control mode.
15 . The power converter system according to claim 1 , wherein the controller is further configured to:
receive feedback metrics comprising at least one of an input voltage and an output current; and
vary duty cycles of the first sub-period, the second sub-period, the third sub-period, and the fourth sub-period based on the feedback metrics.