Assisted zero voltage switching for a DC-to-DC converter

Patent metadata

Field	Value
Publication number	US-9712066-B2
Application number	US-201514728866-A
Country	US
Kind code	B2
Filing date	Jun 2, 2015
Priority date	Jun 2, 2014
Publication date	Jul 18, 2017
Grant date	Jul 18, 2017

Abstract

An apparatus includes a first auxiliary switch connected to a positive connection of a switching leg of a DC-to-DC converter. The switching leg includes a first main switch and a second main switch connected at a main switch midpoint. A second auxiliary switch is connected between a negative connection of the switching leg and the first auxiliary switch. A connection point between the first and second auxiliary switches is an auxiliary midpoint. An auxiliary inductor connects the auxiliary midpoint and the main switch midpoint. The main switch midpoint is also connected to other converter elements. The first and second main switches include a first capacitance a second capacitance. A switch regulation module regulates the first and second auxiliary switches to control current in the auxiliary inductor to provide or remove charge from the first and second capacitances to induce zero voltage switching for the first and second main switches.

First claim

What is claimed is:

1. An apparatus comprising:
a first auxiliary switch connected to a positive connection of a switching leg of a direct current (“DC”) to DC converter, the switching leg comprising a first main switch and a second main switch, the first and second main switches connected at a main switch midpoint;
a second auxiliary switch connected between a negative connection of the switching leg and the first auxiliary switch, wherein a connection point between the first and second auxiliary switches comprises an auxiliary midpoint;
an auxiliary inductor connected between the auxiliary midpoint and the main switch midpoint, the main switch midpoint further connected to elements of the converter in addition to the first and second main switches and the auxiliary inductor, wherein the first and second main power switches turn on and off as part of operation of the converter, the first main switch comprising a first capacitance and the second main switch comprising a second capacitance; and
a switch regulation module that regulates switching of the first and second auxiliary switches to control current in the auxiliary inductor, the auxiliary inductor providing or removing charge from the first capacitance and the second capacitance to adjust voltage across the first main switch and the second main switch to induce zero voltage switching for the first and second main switches, wherein the switch regulation module controls current in the auxiliary inductor by controlling a phase angle between a voltage transition at the auxiliary midpoint and the main switch midpoint, and wherein the switch regulation module controls the phase angle according to the equation:

Φ
N

≥

4
⁢
π
⁢

⁢

f
s

⁢

L
aux

t
d

⁢

(

2
⁢

C
N

-

λ

V
A

⁢

∫

t
d

⁢

i
x

⁡

(
t
)

⁢

ⅆ
t

)

where
Φ N is the phase angle between the voltage transition at the auxiliary midpoint and the main switch midpoint;
f s is the switching frequency of the converter;
L aux is inductance of the auxiliary inductor;
t d is a dead time between switching of the first main switch and the second main switch;
C N is capacitance of one of the first capacitance and the second capacitance;
V A is voltage of the power source;
i x (t) is current in the connection between the elements of the converter and the main switch midpoint; and
λ is +1 when the first main switch is on and −1 when the second main switch is on.

2. The apparatus of claim 1 , wherein the first capacitance comprises one or more of capacitance of the first main switch and a capacitor connected in parallel with the first main switch, and wherein the second capacitance comprises one or more of capacitance of the second main switch and a capacitor connected in parallel with the second main switch.

3. The apparatus of claim 1 , further comprising a current sensing module that senses current in the auxiliary inductor and in the connection between the elements of the converter and the main switch midpoint, wherein the switch regulation module uses current sensed by the current sensing module and switching states of the first and second main switches to regulate switching in the first and second auxiliary switches to adjust current in the auxiliary inductor to adjust voltage across the first and second main switches to achieve zero voltage switching.

4. The apparatus of claim 1 , wherein the converter comprises a resonant power converter.

5. The apparatus of claim 4 , wherein the resonant power converter comprises at least one stage of a dual active bridge series resonant converter (“DABSRC”).

6. The apparatus of claim 1 , wherein the first and second main switches comprise a first switching leg of a full bridge switching network of the converter, wherein the converter comprises a third main switch connected to the positive connection of a second switching leg and a fourth main switch connected to negative connection of the second switching leg, the first and second switching legs forming a full bridge switching network, and further comprising:
a third auxiliary switch connected to the positive connection of the second switching leg;
a fourth auxiliary switch connected to a negative connection of the second switching leg; and
a second auxiliary inductor connected to a second auxiliary midpoint between the third and fourth auxiliary switches and a second main switch midpoint between the third and fourth main switches, the third main switch comprising a third capacitance and the fourth main switch comprising a fourth capacitance,
wherein the switch regulation module regulates switching of the third and fourth auxiliary switches to control current in the second auxiliary inductor, the second auxiliary inductor providing or removing charge from the third capacitance and the fourth capacitance to adjust voltage across the third main switch and the fourth main switch to induce zero voltage switching for the third and fourth main switches.

7. The apparatus of claim 6 , wherein the converter comprises a DABSRC converter, wherein the full bridge switching network comprises a first full bridge switching network on a primary side of the converter and further comprising a second full bridge switching network on a secondary side of the converter and wherein each switching leg of the second full bridge switching network comprises two auxiliary switches and an auxiliary inductor controlled by a switch regulation module to achieve zero voltage switching of switches in the second full bridge switching network.

8. The apparatus of claim

Assignees

• Univ Colorado Regents
• Raytheon Co
• Univ Utah State

Inventors

• Zane Regan A
• Seltzer Daniel
• Maksimovic Dragan
• Jacobson Boris
• Desrosiers Donald

Classifications

• H02M3/33592

  having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer · CPC title

• H02M3/1584

  with a plurality of power processing stages connected in parallel · CPC title

• H02M7/5387

  in a bridge configuration · CPC title

• H02M3/285

  Single converters with a plurality of output stages connected in parallel (parallel operation of a plurality of converters in DC distribution networks H02J1/10) · CPC title

• H02M1/4241

  using a resonant converter · CPC title