JPH0580964B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a multifunctional detector capable of detecting the driving position and the center position (gap) of a movable body with a single detector.

(Prior Art) Until now, magnetically levitated actuators using step motors, synchronous motors, etc. have not been developed so much, and it is necessary to use a single detector to detect both the drive position and gap of the movable body of such actuators. I have yet to find anything that can be detected.

Here, as prior art, a conventional gap detection method for a magnetically levitated actuator and a conventional position detection method for a synchronous motor will be described.

(1) Example of gap detection in the case of a magnetically levitated actuator with a rotating rotor Figure 4 is a block diagram of such a conventional gap detector, which detects gap displacement as a change in the self-inductance of the detection coil. It is something. Here, the target portion of the rotor 3 and the core portion 2 of the stator 1 of the detector are made of a magnetic material, and detection coils X ₁ , X ₂ , Y ₁ , and Y ₂ are wound around the magnetic pole portions.

FIG. 5 is _a circuit diagram for detecting gaps in the X and Y directions from the gap detector _shown in FIG. Dummy coil X _D1 , X _D2
A bridge is constructed, and a sine wave from an oscillator 4 is applied to both ends of this bridge. Therefore, if the inductance of both coil X ₁ and coil X ₂ is equal, the connection point of coil X ₁ and coil X ₂ ,
The potential difference between the connection point of the dummy coil X _D1 and the dummy coil X _D2 disappears, and the detected displacement value in the X direction becomes zero. Also, as _the rotor 3 approaches the direction of coil X ₁ on the X axis, the inductance of coil X ₁ increases and the inductance of coil can. That is, the voltage at the center tap is amplified by the differential amplifier 5, and the gap in the X direction can be detected via the synchronous rectifier 6. Note that the same applies to the Y direction. This is an example of gap detection in two directions, X and Y, and the rotation direction of the rotor 3 is detected using another detector. In addition, other detection methods include
There are also examples in which an eddy current type detector or an electrostatic type detector is used instead of this detector.

(2) Example of position detection of a rotary synchronous motor A synchronous motor can also be used in a speed control system.
A motor rotor position detector is required to detect the rotor's magnetic pole position.

In a simple version, as shown in FIG. 6, the position of the magnetic pole of the rotor 7 is detected by a Hall element 8 to rotate the motor. That is, when a voltage proportional to the difference between the command signal and the position signal, that is, the positional deviation, is applied as an input, a motor torque proportional to the deviation voltage is generated. The position of this motor is detected by a Hall element 8 serving as a position sensor, and is amplified by an amplifier 9 to excite the coil X.

(Problem to be solved by the invention) However, when performing magnetic levitation of a movable body,
The gap sensor and the position sensor (rotation How to reduce the proportion of surface area occupied by motors (linear drive, linear drive) has become a performance issue.

In particular, when magnetically levitating a movable body in a non-contact state, the movable body must be a permanent magnet (synchronous motor) or
Movable body with teeth (step motor)
Alternatively, it may be a secondary conductor (induction motor), but in any case, in order to perform positioning using position feedback, a sensor that knows the magnetic pole position of the movable body is required. If the space for the gap sensor and this position sensor are taken separately, the other spaces of the movable body (rotational force, suction force) will be compressed, and as a result,
This will lead to a decrease in performance.

The present invention aims to eliminate the above-mentioned problems, integrate a gap sensor and a position sensor, reduce the occupied space, and provide a multifunctional detector that can reduce the size and weight of a magnetically levitated movable body. purpose.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a magnetically levitated movable body having teeth at a constant pitch on its surface, and detects the teeth by facing the teeth. , a first magnetic detection means that outputs two pairs of detected values each having a sine wave shape and a cosine wave shape; A second magnetic detecting means having the same function as the first magnetic detecting means is provided, and the movement of the movable body is performed by adding and subtracting each sinusoidal detection value of the first and second magnetic detecting means. A sine wave position signal relating to the displacement in the direction is obtained, and a cosine wave position signal relating to the displacement in the moving direction of the movable body is obtained by addition/subtraction calculation of each cosine wave detection value of the first and second magnetic detection means. The drive position of the movable body is detected based on the detected value, and the movable body is detected based on a subtracted value between the sum of the detected values of the first magnetic detecting means and the sum of the detected values of the second magnetic detecting means. It is designed to detect the gap between the body and the fixed part.

(Function) According to the present invention, teeth with a constant pitch are formed on the surface of the magnetically levitated movable body, and the first magnetic detection means detects the teeth by facing the teeth, and detects the teeth in the form of a sine wave and a cosine wave. Output each pair of detected values. On the other hand, the second magnetic detection means has the same function as the first magnetic detection means, and is arranged at a symmetrical position with respect to the first magnetic detection means with the movable body as the center. .

Therefore, by adding and subtracting the sinusoidal detection values of the first and second magnetic detection means, a sinusoidal position signal regarding the displacement in the moving direction of the movable body is obtained, and the first and second magnetic detection means A cosine wave position signal regarding the displacement in the moving direction of the movable body is obtained by adding and subtracting each cosine wave detected value, and based on the detected value, the drive position of the movable body is detected, and the first magnetic A gap between the movable body and the fixed part is detected based on a subtraction value between the total detection value of the detection means and the total detection value of the second magnetic detection means.

Therefore, the drive position of the movable body and the gap between the movable body and the fixed part can be detected with a single detector.

More specifically, (1) When the magnetically levitated movable body is a rotating body, teeth at a constant pitch are formed on the surface of the rotating body, and a first magnetic detection means that opposes the teeth and detects the teeth. The first magnetic detection means outputs two pairs of detected values each having a sine wave and a cosine wave by detecting the teeth, and furthermore, the first magnetic detection means outputs two pairs of detected values in the form of a sine wave and a cosine wave, and furthermore, the first magnetic detection means outputs two pairs of detected values in the form of a sine wave and a cosine wave. A second magnetic detection means having the same function as the first magnetic detection means is provided, and an arithmetic circuit that adjusts and subtracts each of the four sine and cosine wave detected values is used to detect the number of times corresponding to the number of teeth of the rotating body.
Detect sinθ-shaped output, cosθ-shaped output, and output representing the position of the rotating body between the two detectors.
The rotational position of the rotating body and the position of the rotating body for magnetic levitation, that is, the gap, are detected by an integrated detector using a converter that converts detected values in the form of sinθ and cosθ to rotational position.

(2) If the magnetically levitated movable body is a movable body that performs linear motion (propulsion movable body), teeth at a constant pitch are formed on both surfaces of the movable propulsion body, and the teeth on one side of the movable body are The first magnetic detection means detects the teeth and outputs two pairs of detected values in the form of a sine wave and a cosine wave. and a second magnetic detecting means having the same function as the pair of magnetic detecting means is provided at a position line symmetrical with respect to the direction of movement thereof, and as described in (1) above, the first magnetic detecting means is
The drive position of the movable body and the gap between the movable body and the fixed part are detected by a single detector based on each detection value of the second magnetic detection means.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of a multifunctional detector showing a first embodiment of the present invention.

In the figure, 10 is a cylindrical fixed frame, 11 is a first detector, 12 is a second detector, 13 is a magnetically levitated rotor made of a magnetic material, and 14 is a core made of a magnetic material with continuous recesses. Members 15 and 21 are the core member 14
Excitation coils 16 and 22 are wound around the base of the magnetically levitated rotor 1 and applied with a carrier wave, and 16 and 22 are first detection coils.
It is arranged at a point symmetrical position with respect to the rotation center of No. 3. 17, 23 are second detection coils, 18, 24
is a third detection coil, 19 and 25 are fourth detection coils, and like the first detection coils 16 and 22 above, each detection coil is located at a point symmetrical position with respect to the rotation center of the magnetic levitation rotor 13. Each detection coil is wound around a salient pole piece at the tip of the core member 14.
In addition, each detector side is built into the case and has a fixed frame 10.
Fixed.

The operation of this multifunctional detector will be explained.

Here, ω: oscillation angular frequency, d ₁ : gap between the first detector and rotor, d ₂ : gap between the second detector and rotor, θ: rotor rotational electrical angle, α: modulation rate, k : is a constant of signal transmission.

First, a carrier wave sin(ωt-φ) is applied to the excitation coils 15 and 21 of the first detector 11 and the second detector 12, respectively.

Therefore, if the output of the detection coil of the first detector 11 is approximated by the gap _d1 and the rotor rotation electrical angle θ, the output of each detection coil will be as follows.

V _C1+ = (k/d ₁ ) (1+α cosθ) sin ωt V _C1- = (k/d ₁ ) (1−α cosθ) sin ωt V _S1+ = (k/d ₁ ) (1+α sinθ) sin ωt V _{S1 -} = (k/d ₁ ) (1-α sin θ) sin ωt Similarly, if the output of the detection coil of the second detector 12 is approximated by the lower gap d ₂ and the rotor rotation electrical angle θ, then V _C2+ = (k/d ₂ ) (1+α cosθ) sin ωt V _C2- = (k/d ₂ ) (1-α cosθ) sin ωt V _S2+ = (k/d ₂ ) (1+α sinθ) sin ωt V _S2- = ( k/d ₂ ) (1-α sin θ) sin ωt.

Using these, (1) In order to obtain a cos output, the first detector 11
The outputs of the detection coils are added and subtracted as shown below.

V _C1+ −V _C1- +V _C2+ −V _C2- =2kα[(1/d ₁ )+(1/d ₂ )] ×cosθ sinωt (2) Similarly, to obtain the sin output, V _S1+ −V _{S1 -} +V _S2+ -V _S2- = 2kα [(1/d ₁ ) + (1/d ₂ )] × sinθ sinωt (3) The gap detection value is: Upper sum - lower sum = 4k [(1/d ₁ )−(1/ _d2 )]×sinωt.

Here, using linear approximation, if we take the equal position of gap d ₁ and gap d ₂ as reference value d ₀ and approximate it by the deviation Δd from the reference value, we get (1/d ₁ ) + (1/d ₂ ). ≒ [(1/d ₀ ) - (1/d ₀ ² ) x Δd] + [(1/d ₀ ) - (1/d ₀ ² ) x - Δd] = 2/d ₀ In other words, the change in Δd It is constant regardless.

(1/d ₁ ) - (1/d ₂ ) ≒ [(1/d ₀ ) - (1/d ₀ ² ) x Δd] - [(1/d ₀ ) - (1/d ₀ ² ) x - Δd]=−(2/d ₀ ² )×Δd In other words, it is proportional to the displacement of the gap.

Then, by performing synchronous rectification and low-pass filter processing on the above (1), (2), and (3), it is possible to eliminate the frequency of sinωt and obtain cosθ, sinθ, and the gap detection value.

For example, an R/D (resolver digital) converter can be used to obtain the position θ digitally from the outputs of cos θ and sin θ.

With this configuration, the detector 11,
12 can detect both the rotational position and gap of the magnetically levitated rotor 13.

Next, a second embodiment of the present invention will be described using FIG. 2.

In the figure, 10 is a fixed frame, 13 is a magnetically levitated rotor,
31 is a first detector, 32 is a second detector, 33
is a core member, 34 and 41 are permanent magnets, 35 and 42 are first detection elements, 36 and 43 are second detection elements,
37, 44 are the third detection elements, 38, 45 are the fourth detection elements.
This is a detection element. Note that the detector side is built into the case and fixed to the fixed frame 10.

Here, the detectors 31 and 32 use permanent magnets 34 and 41 in place of the excitation coils 15 and 21 that apply the carrier waves described above, and detect changes in the relative position of the teeth between the magnetically levitated rotor 13 and the detector using the magnetism of the gap. The change in magnetic flux is detected as a resistance change, the resulting change in magnetic flux is detected by a detection element that detects magnetic flux, such as a Hall element or a magnetoresistive element, and based on this, the rotational position and gap of the magnetically levitated rotor 13 are detected. There is.

Therefore, the sum of the gap of V _C1+ and the gap of V _C1- is independent of the rotational position of the magnetically levitated rotor 13.
Since it is approximately constant, the output of the detection element of the first detector 31 is approximated by the gap d ₁ of the first detector 31 and the electrical angle of rotor rotation θ, as follows: V _C1+ = (k/d ₁ ) (1+α cos θ) V _C1- = (k/d ₁ ) (1-α cosθ) V _S1+ = (k/d ₁ ) (1+α sin θ) V _S1- = (k/d ₁ ) (1-α sin θ).

Similarly, the output of the detection coil of the second detector 32 is approximated by the lower gap d ₂ and the rotor rotational electrical angle θ, as follows: V _C2+ = (k/d ₂ ) (1+α cos θ) V _C2- = (k /d ₂ )(1−α cosθ) V _S2+ =(k/d ₂ )(1+α sinθ) V _S2− =(k/d ₂ )(1−α sinθ).

Utilizing these, (1) To obtain a cos output, add/subtract each output of the detection element of the first detector as follows.

V _C1+ −V _C1- +V _C2+ −V _C2- = 2kα [(1/d ₁ ) + (1/d ₂ )] ×cosθ (2) Similarly, to obtain the sin output, V _S1+ −V _S1- +V _S2+ −V _S2- = 2kα [(1/d ₁ ) + (1/d ₂ )] × sinθ (3) The gap detection value is: Upper sum - lower sum = 4k [(1/d ₁ ) −(1/d ₂ )] From this point on, the same procedure as in the first embodiment described above is performed.
Cos θ, sin θ and gap detection values can be obtained.

Next, a third embodiment of the present invention will be described based on FIG. 3.

In this embodiment, in the case of a linear type in which the movable body is driven in a linear direction, a single detector is used to detect the displacement of the movable body in the linear direction and the gap.

In the figure, 50 is a movable body driven in a linear direction (propulsive movable body), 51 is a first detector, 52 is a second detector, 53 is a core member, 55, 65 are exciting coils, 56, 66 is the first detection coil, 57, 67
is a second detection coil, 58 and 68 are third detection coils, and 59 and 69 are fourth detection coils. Further, each detector side is built into a case and fixed to a fixed frame.

As shown in FIG. 3, the two detectors are arranged vertically symmetrically with respect to the center line A-A' of the movable propulsion body 50, and the displacement in the direction of the arrow (rightward) In contrast, the detection values of each detection coil output similar envelopes on both the upper and lower sides.

Here, ω: oscillation angular frequency, x: tooth relative displacement,
d ₁ : Gap between the first detector 51 and the movable propulsion body 50, d ₂ : Gap between the second detector 52 and the movable propulsion body 5
Gap between 0 and τ: tooth pitch.

First, the excitation coils 5 of these detectors 51 and 52
A carrier wave sin(ωt−φ) is applied to 5 and 65. Then, the following detection values are output to each detection coil. That is, V _C1+ = (k/d ₁ ) [1+α cos (2Лx/τ)]×
sinωt V _C1- = (k/d ₁ ) [1-α cos (2Лx/τ)]×
sinωt V _S1- = (k/d ₁ ) [1-α sin(2Лx/τ)]×
sinωt V _S1+ = (k/d ₁ ) [1+α sin(2Лx/τ)]×
sinωt Similarly, for each lower detection coil, V _C2+ = (k/d ₂ ) [1+α cos (2Лx/τ)]×
sinωt V _C2- = (k/d ₂ ) [1-α cos (2Лx/τ)]×
sinωt V _S2- = (k/d ₂ ) [1-α sin (2Лx/τ)]×
sinωt V _S2+ = (k/d ₂ ) [1+α sin(2Лx/τ)]×
sinωt is output.

Utilizing these, (1) To obtain a cos output, add/subtract each output of the detection coil of the first detector 51 as follows.

V _C1+ −V _C1- +V _C2+ −V _C2- =2kα[(1/d ₁ )+(1/d ₂ )] ×cos(2Лx/τ)]×sinωt (2) To obtain the sin output, Similarly, V _S1+ −V _S1- +V _S2+ −V _S2- = 2kα [(1/d ₁ ) + (1/d ₂ )] × sin (2Лx/τ)] × sinωt (3) The gap detection value is sum - lower sum = 4k [(1/d ₁ ) - (1/d ₂ )] × sinωt Here, using linear approximation, the equal position of gap d ₁ and gap d ₂ is set to the reference value d ₀ If we approximate it by the deviation Δd from the reference value, (1/d ₁ ) + (1/d ₂ ) ≒ [(1/d ₀ )−(1/d ₀ ^{2 )×Δd] + [(1/d 0 )−(1/d 0 2} )×Δd] d ₀ )−(1/d ₀ ² )×−Δd]=2/d ₀ In other words, it is approximately constant around the reference point.

(1/d ₁ ) - (1/d ₂ ) ≒ [(1/d ₀ ) - (1/d ₀ ² ) x Δd] - [(1/d ₀ ) - (1/d ₀ ² ) x - Δd]=−(2/d ₀ ² )×Δd In other words, it is approximately proportional to the gap displacement around the reference point.

With this configuration, the first detector 51 and the second detector 52 can detect both the drive position and the gap position of the magnetic levitation propulsion movable body 50.

Further, the magnetically levitated movable body can also be a disk-like disk. In this case, teeth with a constant pitch are formed radially on the front and back sides of this disc-shaped disc, and the first magnetic detection means and the second magnetic detection means are symmetrically arranged on the front and back sides of the disc-shaped disc as the center. The detection means are arranged to face each other.

Furthermore, in the magnetic levitation rotor type embodiment, the first and second detectors are arranged around the rotor, but depending on the magnetic levitation application, the first and second detectors may be arranged perpendicular to the gap displacement direction. By arranging the same type of detector in the direction of rotation, and adding the output from this detector, and using the rotation detection signals from a total of four orthogonal detectors, it is possible to eliminate interference caused by gap displacement. No rotational position signal can be obtained.

Note that the present invention is not limited to the above-mentioned embodiments, and various modifications can be made based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

(Effects of the Invention) As described above in detail, according to the present invention, a magnetically levitated movable body having teeth at a constant pitch formed on its surface is provided, and the teeth are detected while facing the teeth, and a sinusoidal waveform is detected. and a first magnetic detection means for outputting two pairs of detection values in the form of a cosine wave; A second magnetic detection means having the same function as the detection means is provided, and the displacement of the movable body in the moving direction is determined by addition/subtraction calculation of each sinusoidal detection value of the first and second magnetic detection means. A cosine wave position signal regarding the displacement in the moving direction of the movable body is obtained by adding and subtracting each cosine wave detection value of the first and second magnetic detection means, and The drive position of the movable body is detected based on the drive position of the movable body, and the drive position of the movable body is detected based on the subtraction value between the sum of the detection values of the first magnetic detection means and the sum of the detection values of the second magnetic detection means. Since the gap between the parts is detected, (1) the detector can be made more compact, and the reference surface for detecting the magnetically levitated movable body can be made smaller, so the space occupied for detection can be reduced; It is possible to improve the magnetic levitation performance by reducing the weight of the magnetic levitation movable body.

(2) Since the detectors are arranged symmetrically around the movable body, interference between the drive, that is, rotation or propulsion, and the gap can be reduced.

(3) The movable body is sandwiched between the detectors, and the hyperbolic nonlinearity of the inductance can be added up and down, and a substantially linear displacement detection value can be obtained within a certain range with respect to the gap displacement. I can do it.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a multi-functional detector showing a first embodiment of the present invention, Fig. 2 is a block diagram of a multi-functional detector showing a second embodiment of the present invention, and Fig. 3 is a block diagram of a multi-functional detector showing a second embodiment of the present invention. FIG. 4 is a configuration diagram of a conventional gap detector, FIG. 5 is a gap detection circuit diagram thereof, and FIG. 6 is a diagram of another conventional gap detector. FIG. 10... Fixed frame, 11, 31, 51... First detector, 12, 32, 52... Second detector, 1
3... Magnetic levitation rotor, 14, 33, 53... Core member, 15, 21, 55, 65... Excitation coil,
16, 22, 56, 66...first detection coil,
17, 23, 57, 67... second detection coil,
18, 24, 58, 68... third detection coil,
19, 25, 59, 69... fourth detection coil,
34, 41... Permanent magnet, 35, 42... First detection element, 36, 43... Second detection element, 3
7, 44... Third detection element, 38, 45... Fourth detection element, 50... Propulsion movable body.

Claims (1)

[Scope of Claims] 1. A magnetically levitated movable body having teeth of a constant pitch formed on its surface is provided, which detects the teeth by facing the teeth, and outputs two pairs of detected values each in the form of a sine wave and a cosine wave. a first magnetic detection means; and a second magnetic detection having the same function as the first magnetic detection means, located at a symmetrical position with respect to the first magnetic detection means about the reference position of the movable body. means, and obtains a sinusoidal position signal regarding the displacement in the moving direction of the movable body by adding and subtracting the sinusoidal detection values of the first and second magnetic detection means, and A cosine wave position signal related to the displacement in the moving direction of the movable body is obtained by addition/subtraction of each cosine wave detection value of the magnetic detection means of No. 2, and a drive position of the movable body is detected based on the detection value, A gap between the movable body and the fixed part is detected based on a subtracted value between the sum of the detection values of the first magnetic detection means and the sum of the detection values of the second magnetic detection means. Multifunctional detector. 2. The magnetically levitated movable body is a cylindrical rotating body, teeth of a constant pitch are formed on the cylindrical surface of the rotating body, and the first magnetic detection sensor is located at a point symmetrical position with respect to the rotation center of the rotating body. 2. The multifunctional detector according to claim 1, wherein the magnetic detection means and the second magnetic detection means are arranged to face each other. 3. The magnetically levitated movable body is a propulsion movable body that performs linear motion, and teeth of a constant pitch are formed on both surfaces of the movable body, and the teeth of the magnetically levitated movable body are located at positions line symmetrical with respect to the center line of the movable direction of the movable body. 2. The multifunctional detector according to claim 1, wherein the first magnetic detection means and the second magnetic detection means are arranged to face each other. 4. The magnetically levitated movable body is a disc-shaped disc, and teeth of a constant pitch are formed radially on the front and back of the disc, and the first magnetic detection means is arranged on the front and back sides of the disc-shaped disc as a center. The multifunctional detector according to claim 1, characterized in that the second magnetic detection means is opposed to each other.