Rotation angle detection device and rotation angle detection method

Patent metadata

Field	Value
Publication number	US-10151605-B2
Application number	US-201415514349-A
Country	US
Kind code	B2
Filing date	Nov 6, 2014
Priority date	Nov 6, 2014
Publication date	Dec 11, 2018
Grant date	Dec 11, 2018

Abstract

In a rotation angle detection device for detecting a rotation angle and a rotation speed of a motor generator by using a resolver, a resolver detection accuracy is improved by raising the amplitude or frequency of an excitation signal when the motor generator is performing a driving operation. Furthermore, by reducing the amplitude or frequency of the excitation signal when the motor generator is not performing a driving operation, it is possible to suppress the amount of heat generated by the excitation circuit and the resolver, while maintaining a resolver detection accuracy that enables information about the rotation speed of the motor generator to be obtained.

First claim

The invention claimed is:

1. A rotation angle detection device, comprising:
a resolver which has an excitation coil and an induction coil, and in which a magnetic field formed by an excitation signal applied to the excitation coil is frequency-modulated by rotation of a motor generator and induced in the induction coil;
an excitation circuit which applies the excitation signal, which is sinusoidal, to the excitation coil of the resolver;
a power supply circuit which supplies power to the excitation circuit;
an amplification circuit which amplifies and outputs an amplitude of an induction signal induced in the induction coil; and
an angle calculation unit which detects a rotation angle and a rotation speed of the motor generator, which is capable of a driving operation and a power generating operation, from the excitation signal output by the excitation circuit and from the induction signal output by the amplification circuit,
the rotation angle detection device further comprising:
a first switching circuit which, in an on state, switches an amplitude or a frequency of the excitation signal to an amplitude value when on, or a frequency when on, by which a required value of a detection accuracy of the resolver during the driving operation of the motor generator is satisfied, and in an off state, switches the amplitude or frequency of the excitation signal to an amplitude value when off, or a frequency when off, by which a detection accuracy of the resolver that enables information about the rotation speed of the motor generator to be obtained is maintained;
a second switching circuit which switches an amplification rate of the amplification circuit in such a manner that the amplitude of the induction signal output by the amplification circuit is maintained at a signal level required by the angle calculation unit, regardless of the on/off switching state of the first switching circuit; and
a control unit which implements control of on and off of switching on the first switching circuit and the second switching circuit, wherein
the control unit switches on both the first switching circuit and the second switching circuit when the motor generator is performing the driving operation; and
switches off both the first switching circuit and the second switching circuit when the motor generator is not performing the driving operation.

2. The rotation angle detection device according to claim 1 ,
wherein when the first switching circuit is in an off state, a resistance value of a feedback resistance of an operating amplifier constituting the excitation circuit is set in such a manner that the amplitude of the excitation signal becomes the amplitude value when off; and
the first switching circuit is provided in the excitation circuit and, when in an on state, switches the feedback resistance of the operating amplifier of the excitation circuit to a first resistance by which the amplitude of the excitation signal becomes the amplitude value when on, and, when in an off state, to the feedback resistance of the operating amplifier of the excitation circuit.

3. The rotation angle detection device according to claim 2 , wherein:
the second switching circuit is provided in the amplification circuit;
when the second switching circuit in an on state, an amplification rate of the amplification circuit is controlled to suppress the amplification rate of the amplification circuit;
when the second switching circuit in an off state, the amplification circuit is controlled to have an amplification state; and
the second switching circuit is controlled in such a manner that an effect of increasing the amplitude of the excitation signal by the first switching circuit and an effect of suppressing the amplitude of the induction signal by the second switching circuit cancel each other out when both the first switching circuit and the second switching circuit are in the on state.

4. The rotation angle detection device according to claim 1 , wherein:
the first switching circuit is provided in the power supply circuit;
when the first switching circuit is in the off state, an output voltage of the power supply circuit is controlled in such a manner that the amplitude of the excitation signal becomes the amplitude value when off; and
when the first switching circuit is in the on state, the output voltage of the power supply circuit is controlled in such a manner that the amplitude of the excitation signal becomes the amplitude value when on.

5. The rotation angle detection device according to claim 4 , wherein:
the second switching circuit is provided in the amplification circuit;
when the second switching circuit is in an on state, amplification rate of the amplification circuit is controlled to suppress the amplification rate of the amplification circuit;
when the second switching circuit is in an off state, the amplification circuit is controlled to have an amplification state; and
the second switching circuit is controlled in such a manner that an effect of increasing the amplitude of the excitation signal by the first switching circuit and an effect of suppressing the amplitude of the induction signal by the second switching circuit cancel each other out when both the first switching circuit and the second switching circuit are in the on state.

6. The rotation angle detection device according to claim 1 , wherein:
the first switching circuit is provided in the excitation circuit;
when the first switching circuit is in the off state, a transmission frequency of the excitation circuit is controlled in such a manner that the frequency of the excitation signal becomes the frequency when off; and
when the first switching circuit is in the on state, the transmission frequency of the excitation circuit is controlled in such a manner that the frequency of the excitation signal becomes the frequency when on.

7. The rotation angle detection device according to claim 6 , wherein:
the second switching circuit is provided in the amplification circuit;
when the second switching circuit is in an on state, an amplification rate of the amplification circuit is controlled to suppress the amplification rate of the amplification circuit;
when the second switching circuit is in an off state, the amplification circuit is controlled to have an amplification state; and
the second switching circuit is controlled in such a manner that an effect of increasing the amplitude of the excitation signal by the first switching circuit and an effect of suppressing the amplitude of the induction signal by the second switching circuit cancel each other out when both the first switching circuit and the second switching circuit are in the on state.

8. The rotation angle detection device according to claim 1 , wherein:
the second switching circuit is provided in the amplification circuit;
when the second switching circuit is in an on state, an amplification rate of the amplification circuit is controlled to suppress the amplification rate of the amplification circuit;
when the second switching circuit is in an off state, the amplification circuit is controlled to have an amplification state; and
the second switching circuit is controlled in such a manner that an effect of increasing the amplitude of the excitation signal by the first switching circuit and an effect of suppressing the amplitude of the induction signal by the second switching circuit cancel each other out when both the first switching circuit and the second switching circuit are in the on state.

9. A rotation angle detection method used in a rotation angle detection device including:
a resolver which has an excitation coil and an induction coil, and in which a magnetic field formed by an excitation

Assignees

• Mitsubishi Electric Corp

Inventors

• Fujie Kenichi
• Tsujimoto Katsuya
• Tottori Isao
• Suetake Naruki

Classifications

• H02K24/00

  Machines adapted for the instantaneous transmission or reception of the angular displacement of rotating parts, e.g. synchro, selsyn · CPC title

• G01D5/2066 Primary

  by movement of a single coil with respect to a single other coil · CPC title

• G01D5/20 Primary

  by varying inductance, e.g. by a movable armature · CPC title