Current sensor and attachment structure of the same

Patent metadata

Field	Value
Publication number	US-9638767-B2
Application number	US-201213613835-A
Country	US
Kind code	B2
Filing date	Sep 13, 2012
Priority date	Sep 19, 2011
Publication date	May 2, 2017
Grant date	May 2, 2017

Abstract

In a current sensor for detecting an electric current flowing in a current path, a magnetic field generating element generates a second magnetic field perpendicular to a first magnetic field generated by the electric current of the current path, and a magnetic sensor generates at least one of a first signal containing a sine value according to an angle defined between the second magnetic field and a synthetic magnetic field composed of the first magnetic field and the second magnetic field and a second signal containing a cosine value according to the angle. A signal processing unit includes a calculation circuit that calculates a tangential value according to the angle using the at least one of the first signal and the second signal, and outputs a sensor signal containing the tangential value.

First claim

What is claimed is:

1. A current sensor for detecting an electric current flowing in a current path, the electric current generating a first magnetic field, the current sensor comprising:
a magnetic field generating element generating a second magnetic field perpendicular to the first magnetic field;
a magnetic sensor including a magnetoresistive element, the magnetoresistive element including a pin layer, a tunnel layer and a free layer, the pin layer having a fixed magnetization direction, the tunnel layer being provided by an insulating member and being disposed between the pin layer and the free layer, the free layer having a property where a magnetization direction changes according to an external magnetic field, the magnetic sensor generating at least one of a first signal containing a sine value according to an angle defined between the second magnetic field and a synthetic magnetic field composed of the first magnetic field and the second magnetic field and a second signal containing a cosine value according to the angle defined between the second magnetic field and the synthetic magnetic field; and
a signal processing unit receiving the at least one of the first signal and the second signal, the signal processing unit including a calculation circuit, wherein the calculation circuit calculates a tangential value according to the angle defined between the second magnetic field and the synthetic magnetic field using the at least one of the first signal and the second signal to calculate the first magnetic field/the second magnetic field, and outputs a sensor signal containing the tangential value and the sensor signal is linearly proportional to the first magnetic field.

2. The current sensor according to claim 1 , wherein
the magnetic sensor includes a first detection unit and a second detection unit,
each of the first detection unit and the second detection unit includes the magnetoresistive element,
the magnetoresistive element of the first detection unit and the magnetoresistive element of the second detection unit are disposed such that the magnetization directions of the pin layers thereof are perpendicular to each other,
the magnetoresistive element of the first detection unit outputs the first signal, the magnetoresistive element of the second detection unit outputs the second signal, and
the calculation circuit calculates the tangential value by performing division of the first signal by the second signal.

3. The current sensor according to claim 1 , wherein
when the calculation circuit receives one of the first signal and the second signal from the magnetic sensor, the calculation circuit calculates one of a cosine value from the sine value of the first signal and a sine value from the cosine value of the second signal, and
the calculation circuit calculates the tangential value based the one of the cosine value and the sine value calculated and the one of the first signal and the second signal received.

4. The current sensor according to claim 1 , wherein
the magnetic field generating element includes a magnet, and
the magnetic sensor is disposed on the magnet.

5. The current sensor according to claim 1 , wherein
the magnetic field generating element includes substantially a U-shaped magnet that has a first part and second parts extending perpendicularly from opposite ends of the first part, and
the magnetic sensor is disposed between the second parts of the U-shaped magnet.

6. The current sensor according to claim 1 , wherein
the magnetic field generating element includes a coil that is configured to generate the second magnetic field when being supplied with an electric current.

7. The current sensor according to claim 6 , wherein
the magnetic field generating element is configured such that a magnitude of the second magnetic field is changed when a value of the electric current supplied to the coil is changed at a predetermined timing.

8. The current sensor according to claim 1 , wherein
the magnetic field generating element includes a thin film coil that generates the second magnetic field when being supplied with an electric current, and
the thin film coil is disposed in the magnetic sensor.

9. The current sensor according to claim 1 , wherein
the magnetic field generating element includes a ferromagnetic film, and
the ferromagnetic film is disposed on the free layer of the magnetoresistive element.

10. The current sensor according to claim 1 , wherein
the pin layer of the magnetoresistive element includes a ferromagnetic film, and
the magnetic field generating element is provided by the ferromagnetic film.

11. The current sensor according to claim 1 , wherein
the signal processing unit is disposed in a circuit chip, and
the magnetic sensor and the circuit chip are integrally sealed in a molded resin.

12. The current sensor according to claim 1 , wherein
the magnetic sensor is sealed in a molded resin, and
the signal processing unit is electrically connected to the magnetic sensor through a lead to receive the at least one of the first signal and the second signal, the lead extending from an inside of the molded resin to an outside of the molded resin.

13. The current sensor according to claim 1 , further comprising:
a magnetic core having a cylindrical shape with a gap to surround the current path, and concentrating the first magnetic field, and
the magnetic sensor is disposed in the gap of the magnetic core.

14. The current sensor according to claim 1 , wherein
the magnetic sensor includes a magnetic core for concentrating the first magnetic field.

15. A current sensor for detecting an electric current flowing in a current path, the electric current generating a first magnetic field, the current sensor comprising:
a magnetic field generating element generating a second magnetic field perpendicular to the first magnetic field;
a magnetic sensor including a magnetoresistive element, the magnetoresistive element including a pin layer, a tunnel layer and a free layer, the pin layer having a fixed magnetization direction, the tunnel layer being provided by an insulating member and being disposed between the pin layer and the free layer, the free layer having a property where a magnetization direction changes according to an external magnetic field, the magnetic sensor generating at least one of a first signal containing a sine value according to an angle defined between the second magnetic field and a synthetic magnetic field composed of the first magnetic field and the second magnetic field and a second signal containing a cosine value according to the angle defined between the second magnetic field and the synthetic magnetic field; and
a signal processing unit receiving the at least one of the first signal and the second signal, the signal processing unit including a calculation circuit, wherein the calculation circuit calculates a tangential value according to the angle defined between the second magnetic field and the synthetic magnetic field using the at least one of the first signal and the second signal, and outputs a sensor signal containing the tangential value, wherein
the magnetic sensor includes a first detection unit and a second detection unit,
each of the first detection unit and the second detection unit includes the magnetoresistive element,
the magnetoresistive element of the first detection unit and the magnetoresistive element of the second detection unit are disposed such that the magnetization directions of the pin layers thereof are perpendicular to each other,
the magnetoresistive element of the first detection unit outpu

Assignees

• Nomura Kousuke
• Kurumado Norihiro
• Denso Corp

Inventors

• Nomura Kousuke
• Kurumado Norihiro

Classifications

• G01R33/09 Primary

  Magnetoresistive devices · CPC title