Patent ID: 9252665
Filing Date: 2016-02-02
CPC Classification: H02M

Claim Text:
1. An apparatus for controlling a DC-DC converter having a magnetic-field canceling type transformer including first and second windings wound in reverse directions, each of the windings being connected to a positive electrode terminal of a low-voltage port at one end and connected to a positive electrode terminal of a high-voltage port through a common terminal at other end; a first switching element interposed between the other end of the first winding and a negative electrode wire connecting a negative electrode terminal of the low-voltage port with a negative electrode terminal of the high-voltage port; and a second switching element interposed between the other end of the second winding and the negative electrode wire, the apparatus comprising: current detecting means for detecting a current flowing through a positive electrode wire connecting the common terminal with the positive electrode terminal of the high-voltage port, the current detecting means detecting a first current flowing through the positive electrode wire via the first winding at a first time point and a second current flowing through the positive electrode wire via the second winding at a second time point different from the first time point in accordance with ON and OFF states of the first and second switching elements; and control means for controlling operations of the first and second switching elements based on the first current and the second current detected by the current detecting means so that a current difference of the first and second windings becomes zero, wherein a duty ratio for controlling the first switching element and a duty ratio for controlling the second switching element by the control means are equal to each other, the current detecting means detect an excitation current flowing through the first winding due to mutual induction as the first current when the first switching element is turned OFF and the second switching element is turned ON by the control means, while the current detecting means detect an excitation current flowing through the second winding due to mutual induction as the second current when the first switching element is turned ON and the second switching element is turned OFF by the control means, and a time that the current detecting means takes to detect the excitation current flowing through the second winding from when the first switching element is turned ON is equal to a time that the current detecting means takes to detect the excitation current flowing through the first winding from when the second switching element is turned ON.