DC-DC converter

Patent metadata

Field	Value
Publication number	US-9641089-B2
Application number	US-201314891479-A
Country	US
Kind code	B2
Filing date	Dec 5, 2013
Priority date	Jul 11, 2013
Publication date	May 2, 2017
Grant date	May 2, 2017

Abstract

A first switching circuit is connected between a transformer first winding and a DC power supply. A second switching circuit is connected between the transformer second winding and a battery. When charging the battery, a control circuit turns off an element in a second bridge circuit in the second switching circuit, and controls a phase shift amount of a first diagonal element, and a phase shift amount of a second diagonal element in the second bridge circuit, relative to a drive phase of a first reference element in a first bridge circuit in the first switching circuit. When discharging the battery, the control circuit turns off an element in the first bridge circuit and controls a phase shift amount of the second diagonal element and a phase shift amount of the first diagonal element relative to a drive phase of a second reference element in the second bridge circuit.

First claim

The invention claimed is:

1. A DC-DC converter which performs bidirectional power transmission between a first DC power supply and a second DC power supply, the DC-DC converter comprising:
a transformer;
a first converter unit composed of a full-bridge circuit having two bridge circuits each having a plurality of semiconductor switching elements to each of which an antiparallel diode and a parallel capacitor are connected, the first converter unit being connected between the first DC power supply and a first winding of the transformer, and performing bidirectional power conversion between DC and AC;
a second converter unit composed of a full-bridge circuit having two bridge circuits each having a plurality of semiconductor switching elements to each of which an antiparallel diode and a parallel capacitor are connected, the second converter unit being connected between the second DC power supply and a second winding of the transformer, and performing bidirectional power conversion between DC and AC;
a first reactor and a second reactor connected on respective AC input/output lines of the first converter unit and the second converter unit; and
a control circuit for drive-controlling each semiconductor switching element in the first converter unit and the second converter unit, thereby controlling the first converter unit and the second converter unit, wherein
in first power transmission from the first DC power supply to the second DC: power supply, the control circuit
turns off all the semiconductor switching elements of a second bridge circuit which is one of the bridge circuits of the second converter unit,
controls each semiconductor switching element in the first converter unit so as to perform zero voltage switching, using the first reactor, and
when voltage of the second DC power supply is higher than voltage generated on the second winding of the transformer, controls the second converter unit so as to perform step-up operation, using the second reactor, and

in second power transmission from the second DC power supply to the first DC power supply, the control circuit
turns off all the semiconductor switching elements of a first bridge circuit which is one of the bridge circuits of the first converter unit,
controls each semiconductor switching element in the second converter unit so as to perform zero voltage switching, using the second reactor, and
when voltage of the first DC power supply is higher than voltage generated on the first winding of the transformer, controls the first converter unit so as to perform step-up operation, using the first reactor.

2. The DC-DC converter according to claim 1 , wherein
in the first power transmission, the control circuit controls semiconductor switching elements on a positive side and semiconductor switching elements on a negative side in three bridge circuits other than the second bridge circuit in the first converter unit and the second converter unit, with an ON time ratio of 50%, respectively, excluding a short-circuit prevention time, and
in the second power transmission, the control circuit controls semiconductor switching elements on a positive side and semiconductor switching elements on a negative side in three bridge circuits other than the first bridge circuit in the first converter unit and the second converter unit, with an ON time ratio of 50%, respectively, excluding a short-circuit prevention time.

3. The DC-DC converter according to claim 2 , wherein
a semiconductor switching element on one of a positive side and a negative side in the first bridge circuit in the first converter unit is defined as a first reference element,
a semiconductor switching element on one of a positive side and a negative side in the second bridge circuit in the second converter unit is defined as a second reference element,
in the first converter unit, a semiconductor switching element diagonal to the first reference element is defined as a first diagonal element,
in the second converter unit, a semiconductor switching element diagonal to the second reference element is defined as a second diagonal element,
in the first power transmission, the control circuit controls a first phase shift amount of a drive signal for the first diagonal element and a second phase shift amount of a drive signal for the second diagonal element relative to a phase of a drive signal for the first reference element, and
in the second power transmission, the control circuit controls a third phase shift amount of a drive signal for the second diagonal element and a fourth phase shift amount of a drive signal for the first diagonal element relative to a phase of a drive signal for the second reference element.

4. The DC-DC converter according to claim 3 , wherein
in the first power transmission,
the control circuit controls the first phase shift amount and the second phase shift amount by the same amount, and when increasing a power transmission amount from the first DC power supply to the second DC power supply, reduces the first phase shift amount and the second phase shift amount,

in the second power transmission,
the control circuit controls the third phase shift amount and the fourth phase shift amount by the same amount, and when increasing a power transmission amount from the second DC power supply to the first DC power supply, reduces the third phase shift amount and the fourth phase shift amount, and

the control circuit switches between the first power transmission and the second power transmission, when the first phase shift amount and the second phase shift amount are maximum in the first power transmission, and when the third phase shift amount and the fourth phase shift amount are maximum in the second power transmission.

5. The DC-DC converter according to claim 4 , wherein
in the first power transmission, using as a first reference point a point at which both the first phase shift amount and the second phase shift amount are minimum, when increasing a power transmission amount from the first DC power supply to the second DC power supply from the first reference point, the control circuit increases the second phase shift amount while keeping the first phase shift amount to be minimum, and
in the second power transmission, using as a second reference point a point at which both the third phase shift amount and the fourth phase shift amount are minimum, when increasing a power transmission amount from the second DC power supply to the first DC power supply from the second reference point, the control circuit increases the fourth phase shift amount while keeping the third phase shift amount to be minimum.

6. The DC-DC converter according to claim 5 , wherein the control circuit limits, by a set maximum amount, the second phase shift amount when a power transmission amount from the first DC power supply to the second DC power supply increases from the first reference point, and the fourth phase shift amount when a power transmission amount from the second DC power supply to the first DC power supply increases from the second reference point.

7. The DC-DC converter according to claim 4 , wherein the control circuit limits the first to fourth phase shift amounts by a set minimum amount, when controlling the first phase shift amount and the second phase shift amount by the same amount in the first power transmission, and when controlling the third phase shift amount and the fourth phase shift amount by the same amount in the second power transmission.

8. The DC-DC converter according to claim 7 , wherein the set minimum amount is variable.

9. The DC-DC converter according to claim 4 , wherein the control circuit calculates an output DUTY ratio based on a power transmission amount between

Assignees

• Mitsubishi Electric Corp

Inventors

• HIGAKI Yusuke
• Kondo Ryota
• Yamada Masaki
• Tan Yohei

Classifications

• H02J7/865

  Battery or charger load switching, e.g. concurrent charging and load supply (H02J7/50 takes precedence) · CPC title

• H02J2207/20

  Charging or discharging characterised by the power electronics converter · CPC title

• H02M3/3353

  having at least two simultaneously operating switches on the input side, e.g. "double forward" or "double (switched) flyback" converter · CPC title

• H02M3/33546 Primary

  with automatic control of the output voltage or current (H02M3/33561 takes precedence) · CPC title

• H02M3/33584

  Bidirectional converters · CPC title