Patent ID: 11881788
Assignee: MITSUBISHI ELECTRIC CORPORATION
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H  Y | IPC H

Claim 0:
1. A DC/AC converter that performs bidirectional power transmission between a first DC power source and a second DC power source, the DC/DC converter 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,
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
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 in each of the first bridge circuit and the second bridge circuit, and
in the second converter, 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 the third bridge circuit and performing on/off drive control of the positive electrode-side switching element and the negative electrode-side switching element in the fourth bridge circuit, and
when a first power transmission amount by the first power transmission is smaller than a first reference value, the control circuit lowers a switching frequency for driving on and off of the respective positive electrode-side switching elements and the respective negative electrode-side switching elements of the first bridge circuit, the second bridge circuit, and the fourth bridge circuit, compared with when the first power transmission amount is equal to or greater than the first reference value.