Rotation angle detection device and electric power steering system using the same

• US 20120078560A1
• Filed: 09/13/2011
• Published: 03/29/2012
• Est. Priority Date: 09/23/2010
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Uryu, Nobuhiko, Satou, Takafumi
• Granted Patent: US 8,781,777 B2
• Time in Patent Office: Days
• US Class Current: 702/94
• CPC Class Codes: B62D 15/0235 by measuring or deriving directly at the electric power steering motor
• CPC Class Codes: G01D 5/2449 using hard-stored calibration data

Abstract

A bridge circuit includes a plurality of half-bridges formed of sensor elements, which change impedance in accordance with a rotation angle of a detection target. A control circuit acquires output signals of the half-bridges and calculates a phase correction value for correcting a phase deviation. A memory circuit stores the phase correction value. The control circuit corrects a pre-correction rotation angle by the phase correction value. Since the pre-correction rotation angle is corrected by the phase correction value, a rotation angle of the detection target is detected with high accuracy even if the sensor elements are assembled with some positional deviations.

Claims

1. A rotation angle detection device comprising:

a sensor circuit including a plurality of sensor element pairs, each of which is formed of sensor elements and senses a rotating magnetic field varying with rotation of a detection target and changes impedance in accordance with a rotation angle of the detection target;

a control circuit including an output signal acquisition section for acquiring output signals produced by the plurality of sensor element pairs individually, a pre-correction rotation angle calculation section for calculating a pre-correction rotation angle of the detection target based on the output signals acquired by the output signal acquisition section, and a correction section for correcting the pre-correction rotation angle calculated by the pre-correction rotation angle calculation section by correction values; and

a memory circuit for storing the correction values, wherein

the control circuit further includes a phase correction value calculation section for calculating phase correction values, as the correction values, for correcting phase deviations between the output signals based on the output signals acquired by the output signal acquisition section,

the correction section corrects the pre-correction rotation angle by the phase correction values stored in the memory circuit, and

the output signal acquisition section acquires the output signals, which are a plurality of signals of different phases.

2. The rotation angle detection device according to claim 1, wherein:

the output signal acquisition section acquires a cosine signal and a sine signal as the output signals of the sensor circuit.

3. The rotation angle detection device according to claim 1, wherein:

the output signal acquisition section acquires four or more signals of the sensor circuit as the output signals.

4. The rotation angle detection device according to claim 3, wherein:

the output signal acquisition section acquires, as the output signals of the sensor circuit, a +cosine signal, a −

cosine signal, a +sine signal and a −

sine signal.

5. The rotation angle detection device according to claim 4, wherein:

the pre-correction rotation angle calculation section calculates the pre-correction rotation angle based on the +cosine signal, the −

cosine signal, the +sine signal and the −

sine signal; and

the phase correction value calculation section calculates the phase correction value based on the +cosine signal, the −

cosine signal, the +sine signal and the −

sine signal.

6. The rotation angle detection device according to claim 4, wherein:

the pre-correction rotation angle calculation section calculates the pre-correction rotation angle based on the +cosine signal or the −

cosine signal; and

the phase correction value calculation section calculates the phase correction value based on the +cosine signal or the −

cosine signal.

7. The rotation angle detection device according to claim 4, wherein:

the pre-correction rotation angle calculation section calculates the pre-correction rotation angle based on the +sine signal or the −

sine signal; and

the phase correction value calculation section calculates the phase correction value based on the +sine signal or the −

sine signal.

8. The rotation angle detection device according to claim 1, wherein:

the sensor circuit is operatively arranged to detect the rotation of a motor provided in an electric power steering apparatus.