1. Technical Field
The present invention relates to a magnetic balance type current sensor using a magnetoresistive effect element (TMR element, GMR element).
2. Related Art
In an electric vehicle, a motor is driven with electricity generated by an engine, and the magnitude of a current for driving the motor is detected by, for example, a current sensor. As the current sensor, for example, a magnetic balance type current sensor is known which is described in Japanese Unexamined Patent Application Publication No. 2006-125962.
In this magnetic balance type current sensor, if a measured current flows into a primary conductor, an output voltage is generated in a magnetic detection element by a primary magnetic field according to the measured current, and a voltage signal output from the magnetic detection element is converted into a current which will flow in a secondary conductor. A magnetic field (cancel magnetic field) generated by the current flowing in the secondary conductor and the magnetic field generated by the measured current cancel each other, such that the magnetic field constantly becomes zero. At this time, the current flowing in the secondary conductor is converted to a voltage which will be extracted as an output. In Japanese Unexamined Patent Application Publication No. 2006-125962, a magnetoresistive effect element, such as a GMR (Giant Magneto Resistance) element, is used as the magnetic detection element, and a bridge circuit is constituted by a magnetoresistive effect element. The bridge circuit may be constituted by a magnetoresistive effect element and a pinned resistor, as in Japanese Unexamined Patent Application Publication No. 2008-516255.