Patent ID: 11955904
Assignee: MITSUBISHI ELECTRIC CORPORATION
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. A DC/DC converter that performs bidirectional power transmission between a first DC power source and a second DC power source, comprising:
a transformer having a first winding and a second winding magnetically coupled;
a first converter connected between the first DC power source and the first winding; and
a second converter connected between the second DC power source and the second winding, wherein
the first converter includes
a first bridge circuit and a second bridge circuit connected in parallel to each other to the first DC power source,
each of the first, bridge circuit and the second bridge circuit has
a positive electrode-side switching element and a negative electrode-side switching element connected in series between a positive electrode and a negative electrode of the first DC power source, and
a diode connected in antiparallel with each of the positive electrode-side switching element and the negative electrode-side switching element of the first bridge circuit or the second bridge circuit, and
the first winding is connected between a connection point of the positive electrode-side switching element and the negative electrode-side switching element of the first bridge circuit and a connection point of the positive electrode-side switching element and the negative electrode-side switching element of the second bridge circuit, the second converter includes
a third bridge circuit and a fourth bridge circuit connected in parallel to each other to the second DC power source,
each of the third bridge circuit and the fourth bridge circuit has
a positive electrode-side switching element and a negative electrode-side switching element connected in series between a positive electrode and a negative electrode of the second DC power source, and
a diode connected in antiparallel with each of the positive electrode-side switching element and the negative electrode-side switching element of the third bridge circuit or the fourth bridge circuit, and
the second winding is connected between a connection point of the positive electrode-side switching element and the negative electrode-side switching element of the third bridge circuit and a connection point of the positive electrode-side switching element and the negative electrode-side switching element of the fourth bridge circuit, the DC/DC converter further comprising

a control circuit to perform on/off drive control of the respective positive electrode-side switching elements and the respective negative electrode-side switching elements of the first converter and the second converter, wherein
in first power transmission in which power is transmitted from the first DC power source to the second. DC power source,
in the first converter, the control circuit performs DC/AC power conversion by performing on/off drive control of the positive electrode-side switching element and the negative electrode-side switching element such that the positive electrode-side switching elements and the negative electrode-side switching elements are alternately turned on at equal intervals with a short-circuit prevention time interposed, in each of the first bridge circuit and the second bridge circuit;
in the short-circuit prevention time, both of the positive electrode-side switching element and the negative electrode-side switching element are brought to an off state in the first and second bridge circuits,
in the second converter, when a first power transmission amount by the first power transmission is greater than a predetermined first reference value. the control circuit stops onioff drive of the positive electrode-side switching element and the negative electrode-side switching element in the third bridge circuit and performs on/off drive control of the positive electrode-side switching element and the negative electrode-side switching element in the fourth bridge circuit, whereas when the first power transmission amount is smaller than the first reference value, the control circuit performs AC/DC power conversion by stopping on/off drive of the positive electrode-side switching element and the negative electrode-side switching element in both of the third bridge circuit and the fourth bridge circuit,
the control circuit sets, as a first phase shift amount, a phase shift amount of an on/off drive signal of a first diagonal element with respect to an on/off drive signal of a first reference element, the first reference element is one switching element of the positive electrode side and the negative electrode side of the first bridge circuit, and the first diagonal element is the other switching element of the positive electrode side and the negative electrode side of the second bridge circuit,
the control circuit sets, as a second phase shift amount, a phase shift amount of an on/off drive signal of a second diagonal element that is the other switching element of the positive electrode side and the negative electrode side of the fourth bridge circuit with respect to the on/off drive signal of the first reference element, and
the control circuit calculates an output DUTY ratio based on a power transmission amount between the first DC power source and the second DC power source, and changes the first phase shift amount and the second phase shift amount based on the calculated output DUTY ratio.