JPH0466801A - Position and temperature detector - Google Patents

Abstract

PURPOSE:To detect a temperature without a temperature sensor provided by permitting constant bias current to flow to a coil of an inductance detection type position sensor unit and detecting dc voltage from an output of the coil. CONSTITUTION:High frequency voltage of constant amplitude is input from an oscillator 4 to an inverting input terminal of an operational amplifier 10 while constant bias voltage is input from a dc power source 5 to a non-inverted input terminal of the amplifier 10. Thus current wherein high frequency current with constant amplitude overlaps constant bias current flows through a transistor 11 to a coil 1. At a position outputting unit 7, inductance of the coil 1, that is a position, is calculated from the high frequency voltage detected by a high-pass filter. A low-pass filter 8 permits a dc component, that is dc voltage corresponding to the bias current, to be detected from the output of the coil 1. Dc resistance of the coil 1 varies according to a temperature. Then on a temperature outputting unit 9, dc resistance of the coil, that is temperature, is calculated from the dc voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to a position and temperature detection device used, for example, to detect the position of a rotor in a magnetic bearing device.

BACKGROUND OF THE INVENTION As a rotor position detecting device for a magnetic bearing device, one is known that detects the rotor position based on a change in inductance when a high frequency current is passed through a coil of an inductance detection type position sensor.

By the way, in a magnetic bearing device, while the rotor is rotating,
The inside of the bearing device is heated due to motor heat generation, wind damage, iron loss, etc., which causes temperature changes in the position sensor gain and offset, or changes in the rotor shaft length, resulting in errors in position detection and There is a problem that the performance of the device cannot be obtained. In order to eliminate such temperature effects, it is necessary to add a temperature sensor to detect the temperature inside the bearing device and correct the output of the position sensor accordingly.

In addition to magnetic bearing devices, it is often necessary to perform correction based on temperature when detecting the position of an object, and in such cases, it is necessary to add a temperature sensor in addition to the position sensor.

An object of the present invention is to solve the above problems and provide a position and temperature detection device that can detect temperature without adding a temperature sensor.

Means for Solving the Problems A position and temperature detection device according to the present invention includes: an inductance detection type position sensor section having a sensor coil; means for passing a constant bias current through the coil of the sensor section;
The apparatus includes means for detecting DC voltage from the output of the coil of the sensor section, and means for calculating temperature based on this DC voltage.

The DC resistance of the coil of the working inductance detection type position sensor section changes depending on the temperature. Therefore, by flowing a constant bias current through this coil and detecting a DC voltage from the output of the coil, it is possible to calculate the DC resistance of the coil, that is, the temperature, from this DC voltage.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawing schematically shows the overall configuration of the position and temperature detection device.

The detection device includes an inductance detection type position sensor section (2) having a sensor coil (1), a constant current circuit (3) for driving the coil (1) with a constant current, and a constant high frequency voltage applied to the constant current circuit (3). An oscillator (4) for inputting a constant bias voltage to the constant current circuit (3), a DC power supply (5) for inputting a constant bias voltage to the constant current circuit (3), and a high-pass filter (HPF) that passes an AC portion from the output of the coil (1). (6), a position output section (7) that calculates and outputs the position from the output of the high-pass filter (6), and a low-pass filter (LPF) (8) that passes only the DC component from the output of the coil (1). ), and a temperature output section (9) that calculates and outputs the temperature from the output of the low-pass filter (8).

Although not shown, the coil (1) is arranged to face an object, such as a rotor of a magnetic bearing device, with a predetermined gap therebetween.

The constant current circuit (3) is a well-known one, and includes an operational amplifier (1).
0) and a transistor (11). A high frequency voltage of constant amplitude is input from the oscillator (4) to the inverting input terminal of the operational amplifier (10), and at the same time, the operational amplifier (
A constant bias voltage is input from the DC power supply (5) to the non-inverting input terminal of the coil (10), and a current consisting of a constant bias current and a high frequency current of a constant amplitude is passed through the transistor (11) and is applied to the coil (1). ).

A high-pass filter (6) detects a high-frequency voltage corresponding to the alternating current component, that is, a high-frequency current, from the output of the coil (1). When a high frequency current is passed through the coil (1), the inductance of the coil (1) changes depending on the position of the object. Since the amplitude of the high frequency current flowing through the coil (1) is constant, the high frequency voltage detected by the high pass filter (6) corresponds to the inductance of the coil (1).

Then, in the position output section (7), the inductance, that is, the position of the coil (1) is calculated from this high frequency voltage.

A low-pass filter (8) detects a direct current component of the output of the coil (1), that is, a direct current voltage corresponding to the bias current. The DC resistance of the coil (1) changes depending on the temperature. Since the bias current flowing through the coil (1) is constant, the DC voltage detected by the low-pass filter (8) corresponds to the DC resistance of the coil (1). Then, in the temperature output section (9), the DC resistance of the coil (1), that is, the temperature is calculated from this DC voltage.

The outputs of the position output section (7) and the temperature output section (9) can be used independently.

Also, the position output section (7) is output by the output of the temperature output section (9).
Temperature correction can also be performed by correcting the output of When this detection device is used in a magnetic bearing device, temperature correction in this way improves position detection accuracy, expands the operating temperature range, and improves the rigidity of the bearing device, among other benefits. It is played. Note that this detection device can also be used as a position detection device or a temperature detection device.

Effects of the Invention According to the position and temperature detection device of the present invention, as described above, temperature can also be detected without adding a temperature sensor.

[Brief explanation of the drawing]

The drawing is a block diagram of a position and temperature detection device showing an embodiment of the present invention. (1)...sensor coil, (2)...inductance detection type sensor section, (3)...constant current circuit, (5)...
...DC power supply, (8) ...Low pass filter, (9)
...Temperature output section. that's all

Claims (1)

[Claims] an inductance detection type position sensor section having a sensor coil; means for passing a constant bias current through the coil of the sensor section; means for detecting a DC voltage from the output of the coil of the sensor section; A position and temperature sensing device comprising means for calculating.