JPH07119620B2 - Linear synchro resolver device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a linear synchro resolver for a linear motor.

Technical background Linear motor systems are widely used in robot systems and various other servo systems. According to the servo system using the direct drive motor, backlash is eliminated, reliability is increased, and maintenance work of gears, belts, shaft couplings, and the like is reduced, so that the structure of the mechanical system is simplified. However, many conventional servo systems have a series of operational problems, unnecessary manufacturing costs, and
And has problems such as undesirable weight and space requirements.

A position sensor is provided at the heart of the servo system coupled to the motor. Conventional conventional position sensors in the form of synchroresolvers require primary and secondary windings, and some have mechanical contacts such as slip rings, which pose maintenance and reliability issues. increase. Moreover, conventional synchro-resolvers used in servo systems do not have sufficient resolution and are not as accurate as desired for digital direct drive servo positioning systems. Also, in some cases, the output signal of the synchro-resolver may be disturbed by the induction of the motor windings.

As a problem of driving a conventional brushless servomotor using a resolver, in addition to the problems of resolution and accuracy described above, it is difficult to obtain a synchronous position signal related to a commutation method of the motor. In driving these servo motors, the current waveform to be passed to each phase is determined according to the position within the teeth according to the tooth pitch of the motor, and the amplitude is not changed when the load increases. must not.
Therefore, the input to the motor, such as the current waveform of the motor and the phase of each phase, must be calculated from the position within the tooth pitch of the motor, but conventional resolvers do not use a detector with the same tooth pitch as the motor. Therefore, this problem cannot be solved.

The above-mentioned drawbacks and other drawbacks of the conventional synchro-resolver used in the servo motor system are that the slider having a plurality of teeth of the same pitch arranged in the longitudinal direction on the side surface of the member movable in the longitudinal direction and the slider. A stator having a plurality of pole pieces projecting toward the surface having the teeth and provided with a plurality of pole piece teeth facing the teeth of the slider with a slight gap therebetween, and each pole of the stator. A coil wound around one of the coils and an oscillator for exciting each coil, magnetizing adjacent pole pieces of the stator to polarities different from each other and forming a closed magnetic circuit in cooperation with the slider; At least three circuits are formed independently in the axial direction, and the pole piece teeth of the two pole pieces of the stator included in one of the circuits are separated from each other by an integral multiple of the pitch of the slider teeth. The pole piece teeth of the adjacent circuits are offset by an integer multiple of the pitch of the slider teeth, which is one pitch of the number of phases used for position detection, and the teeth of the slider are aligned with the teeth of the stator. A linear synchro resolver device according to the present invention is provided with differential amplifying means for extracting a current change generated in the coil due to a change in inductance due to a degree as a signal and obtaining a position signal based on signals differentially amplified for two different phases. To be overcome.

In addition, the above-mentioned disadvantages similarly occur in a slider having a plurality of teeth of the same pitch arranged in the longitudinal direction on both side surfaces of a member that is movable in the longitudinal direction and a side surface having the teeth of the slider. A stator having a plurality of pole pieces, each pole piece facing each other with the slider provided with a plurality of pole piece teeth facing the teeth of the slider with a slight gap therebetween. And a coil wound around each pole piece of the stator, and an oscillator for exciting each of the coils, and a magnetic circuit in which adjacent pole pieces of each stator are magnetized to have mutually different polarities and closed in cooperation with the slider. At least three circuits are formed independently in the axial direction, and the pole piece teeth of the two pole pieces of the stator included in one of the circuits are separated from each other by an integral multiple of the tooth pitch of the slider. Is next to the The pole piece teeth of the matching circuits are offset by an integer multiple of the pitch of the slider teeth, which is one pitch less than the number of phases of the phase used for position detection. The inductance depends on the degree of matching of the teeth of the slider with the teeth of the stator. Is overcome by the linear synchro resolver device of the present invention, which comprises a differential amplification means for taking out a change in current generated in the coil as a signal by a change in the signal and obtaining a position signal based on signals differentially amplified for two different phases. .

As for the inductance of the stator pole piece, the magnetic flux path due to the excitation of the coil is made strong or weak due to the phase relationship of the facing teeth, so the current flowing in the coil makes the tooth pitch of the slider tooth with the stator pole piece tooth 360 electrical angle. And the relative phase function.

An alternating electric signal source is connected to each phase of the stator coil to detect the mutual magnitude of alternating currents flowing through the coils of each phase that internally generate an electric signal by the detection means, and to detect the magnitude of the detected signal in each phase. The difference is used to synchronously rectify and compare the magnitudes of the signals and the result of this comparison provides an output signal representative of slider position relative to the stator pole pieces.

An important aspect of this synchro-resolver is the availability of its sela-cancellation properties. That is, in the case where the two stators symmetrically opposed to the slider are provided, this can correct misalignment of the slider gap. When the slider approaches one of the two stators, the inductance of one increases and the inductance of the other decreases. The linear resolvers are independent of the center position of the slider because the phases facing each other across the slider are in series, and therefore the contributions of both inductances are added. Of course, in that case, the total gap of both gaps must be the same (the slider cannot be tapered).

In view of the above, it is an object of the present invention to provide an accurate and high-resolution linear synchro resolver device which has a simple structure and requires minimum maintenance.

Another object of the present invention is to provide a linear synchro resolver device for controlling balanced commutation of a servo motor.

A further object of the present invention is to provide a linear synchro resolver that is composed of the same parts as a variable reluctance type linear motor that drives the linear synchro resolver.

Embodiments Turning now particularly to FIG. 1 of the accompanying drawings, there is illustrated a linear synchro resolver of a first embodiment of the present invention. The linear synchro resolver includes a first stator assembly 10 and a second stator assembly 16. Each stator assembly is composed of a plurality of stator pole pieces arranged in pairs representative of phases A, B, C and D, as described in further detail below. The poles of the stator assembly 10 are arranged opposite the poles of the stator assembly 16. Thus, the stator assembly 10 includes a plurality of stator pole piece teeth 26 at each end of the first pair of pole pieces 12a and 14a (A phase). The pole piece teeth of these pole pieces 12a and 14a are separated by an integer multiple of the pitch of the teeth 26.

Opposed to the stator pole pieces 12a and 14a of the stator assembly 10 are the corresponding stator pole pieces 18 of the stator assembly 16.
a and 20a. These pole pieces 18a and 20a have stator pole piece teeth 26 at their ends, and the stator pole piece teeth 26 of these pole pieces 18a and 20a are spaced by an integral multiple of the pitch of the pole piece teeth 26. Has been done. The opposing stator teeth 26 of opposing pole pieces 12a and 18a and 14a and 20a of these stator assemblies 10 and 16 are configured to be aligned (peak to peak and valley to valley facing).

A slider 22 is interposed between the stator assemblies 10 and 16, and the slider 22 has protruding teeth 24 having the same pitch as that of the stator teeth 26 on both surfaces facing the stator assembly. The slider 22 is mounted so as to be movable in the longitudinal direction, that is, between the stator assemblies 10 and 16 in the left-right direction in the drawing,
A gap is formed which is slightly spaced from the ends of the pole piece teeth of the stator pole pieces 12a, 14a, 18a and 20a. The teeth 24 of the slider 22 can be perfectly aligned with the teeth 26 of the stator pole pieces 12a-20a.

Coils 28a, 30a, 32a and 34a are pole pieces 12a, 14a and 18a, respectively.
And each of 20a. When energized, these coils are connected and wound so that the magnetic polarity of the coil 28a is opposite to that of the coils 30a and 32a and has the same polarity as the coil 34a.

As will be described in detail below, the coil is excited by the number of its phases using the signal source. When this excitation is carried out, a magnetic flux path 36a is formed, which magnetic flux path passes from the stator pole piece 12a through the stator assembly 10, across the gap between the slider 22 and the stator pole piece 14a, and through the slider 22. To the stator pole piece 20a, and further passes through the stator assembly 16 and the stator pole piece 18a to cross the gap and the slider 22 to return to the stator pole piece 12a.

The above describes a single phase of a linear synchro resolver. Each of the stator assemblies 10 and 16 includes phases B, C and D.
And a pair of similarly configured stator pole pieces corresponding to Thus, the stator assembly 10 comprises a pair of pole pieces 12b and 14b, which are coils 28b and 30b, respectively.
Surrounded by. This stator pole piece pair is a corresponding pair of stator pole pieces 18b and 20b on the stator assembly 16.
Are opposed to each other. Coils 32b and 34b are wound around these pole pieces 18b and 20b, respectively. Pole pieces 12b and 14b
The spacing between and between the pole pieces 18b and 20b is an integral multiple of the pitch of the stator pole piece teeth 26. It also has slider teeth 22
Is an integral multiple of the pitch. However, the spacing between pole pieces 14a and 12b and the spacing between pole pieces 20a and 18b are not integral multiples of the stator and slider tooth pitch. In this example,
Since four phases are used, the above interval is an integral multiple of the tooth pitch plus 1/4 of the tooth pitch (1 / phase number).

The configurations of the coils and pole pieces for the other phases C and D are almost the same as those for the phases A and B, so a detailed description thereof will be omitted here. These configurations are given the same reference numbers with the letters c or d corresponding to phases C and D respectively. In each case, the distance between pole pairs of a certain phase and the distance between pole pairs of the next adjacent phase should be the integral multiple of the pitch of the stator and slider teeth plus 1/4 tooth pitch. It is transitioning from one phase to the next.

As described above, in FIG. 1, the slider teeth 24 are the stator pole pieces 12c, 14c,
It is perfectly aligned with the teeth 26 of 18c and 20c. As described above, the alignment of the slider tooth 24 with the stator tooth 26 provided on the stator pole piece 14b is smaller by 1/4 tooth pitch than when perfect alignment is obtained. Similarly, the alignment between the slider teeth 24 and the stator pole piece teeth 26 provided on the stator pole piece 14a is 1/2 tooth pitch apart than if perfect alignment were obtained. Stator pole piece tooth 26 for slider tooth 24 and stator pole piece 12d
The misalignment between is 1/4 tooth pitch ahead of the case where perfect alignment is obtained. Therefore, with respect to the phase C of the stator coil, the phase B causes a phase difference of −90 °, the phase A causes a phase difference of 180 °, and the phase D causes a phase difference of + 90 °.

Referring now to FIG. 3, there is shown an apparatus for detecting various misalignments of slider and stator teeth by phase. The signal source 50 as an oscillator in this case generates an AC signal with an oscillating frequency of 3000 Hz, which is the power amplifier 52.
Is amplified by and is fed to all the coils of the phases connected in parallel. In this way, the coil 54 shown in FIG.
Represents the coils 28a, 30a, 32a and 34a wound and connected so that the opposite pole pieces have different polarities as shown in FIG. 1 and are electrically connected in series. . Similarly, the coils 56, 58 and 60 shown in FIG. 3 represent coils of the stator polarity corresponding to the phases B, C and D shown in FIG. 1, respectively. The coils 56, 58, 60 and 54 are grounded through resistors 64, 66, 68 and 62, respectively.

The node of coil 54 and resistor 62 is connected to the non-inverting input of differential amplifier 72. The node between coil 56 and resistor 64 is directly connected to the non-inverting input of differential amplifier 70. The node between coil 58 and resistor 66 is coupled through resistor 76 to the inverting input of amplifier 72. Similarly, the connection between coil 60 and resistor 68 is coupled to the inverting input of differential amplifier 70 through resistor 74.

When the teeth of the slider and the stator pole pieces are aligned with each other as described above, the inductance of the excitation pole piece winding, and thus the impedance, becomes smaller than in the case where the teeth are not aligned. This reduction in impedance causes the coil 54
The current of the constant voltage signal source 50 flowing in the coil increases and the voltage drop of the resistor 52 connected to this coil increases, so this voltage is detected and used as the input signal of the differential amplifier.

The current amplitudes between the coils of each phase have their own phase. Phases A, C, B and D are always 90 ° out of phase with each other, and phases A and C are 180 ° and phase B and D are 180 ° respectively, so that the phase of the difference in the coil current amplitudes is relative to the stator assembly. Gives the cosine and sine function of the slider position. The two outputs of amplifiers 70 and 72 provide sine and cosine wave functions. These outputs are delivered as separate inputs to a synchro-to-digital converter module, or resolver-to-digital converter 78. The signal source 50 is connected to provide a reference input. Such devices are known in the art and are commercially available. For example, XDC19109-3 from ILC Data Devices Corporation of 105 Wilva Place, NY 11716, Bohemia.
01 is commercially available. This device produces as its output 82 a digital resolver position signal which can be used to commutate a variable reluctance linear motor which is constructed approximately equivalent to the resolver shown in FIG. However, this is not necessary when the slider 22 is linearly driven with respect to the stator assemblies 10 and 16 by sequentially applying a drive current to each of the coil phases.

Since the current is being sensed by differential amplifiers 70 and 72, a 90 ° phase shift is induced from the drive voltage. For this reason,
Signal source 50 and resolver-to-digital (resolver-to
-Digital) introduces a phase shift circuit between the reference input of the converter ("RDC") module 78. This phase shifter 80
Delays the phase from source 50 by 90 °. Here is the fourth
Referring to the figures, there is shown a further embodiment of the detection means according to the invention.

According to this embodiment, the differential amplifier inputs the voltage of each phase to the RDC module 78, and the reference signal is input in the converter by the reference signal input as in FIG. 3 (omitted in FIG. 4). It is used to synchronously rectify two phases, compare two-phase signals, and generate a position signal.

The signal source 50 has its output connected to a voltage divider circuit 84 which forms one half of the double bridge circuit. The output of this signal source 50 is further coupled to the end of the phase A coil 54 and the phase C which forms the other half of the bridge.
Is connected to the end of the series connection with the coil 58 of. Similarly,
The output of the signal source 50 is connected to the end of the phase B coil 56 and the end of the series connection with the phase D coil 60 forming the second half of the second bridge. The junction of coils 54 and 58 is connected to the inverting input of differential amplifier 86 through resistor 88. The center tap of voltage divider 84 is connected through resistor 90 to the non-inverting input of amplifier 86. The junction between coils 56 and 60 is connected through resistor 94 to the inverting input of differential amplifier 92, and the center tap of voltage divider 84 is connected through resistor 96 to the non-inverting input of differential amplifier 92. The output of amplifier 86 corresponds to a cosine function to the detected phase difference, which represents the position of the slider with respect to the stator assembly, and the output of amplifier 72 corresponds to a sine function. These two outputs are input to the RDC module 78, which is the digital resolver position signal.
Output 82.

Referring now to FIG. 5, there is shown yet another embodiment for detecting the phase difference as the amplitude of the sine, cosine.
The phase A coil 54 and the phase C coil 58 are connected in series to the output of the signal source 50. The phase B coil 56 and the phase D coil 60 are also connected in series to the signal source 50.

To detect the phase difference as the amplitude of sine and cosine, 2
Subsequent windings are wound around the stator pole piece coils and are both connected in antiphase to provide a differential detection circuit. In this way, 2
The secondary coil 98 provides a series connected stator pole piece coil wound above (or below) the Phase A coils 28a, 30a, 32a and 34a. Here, the secondary coil 98 is wound in a designated direction. Similarly, the second set of coils 100
Is a phase C coil 28 represented by the coil 58 of FIG.
Wound around (or down) c, 30c, 32c and 34c,
Then, the secondary coil 98 is connected in series. However, here, the coil 100 is connected in anti-phase with the coil 98 (or the coil 100 can be wound around the stator pole piece in the opposite direction used when winding the secondary coil 98). Please pay attention to the points. The coils 98 connected in anti-phase with each other
End of resolver-to-digital converter module
Coil 100 is connected to the sine function input to 78 and grounded.

Similarly, secondary coil 102 is wound around (or down) the Phase B stator pole piece coil represented by coil 56 of FIG. 5, and secondary coil 104 is further coil 60 of FIG.
Is wound around (or below) the phase D stator pole piece coil represented by These secondary coils 102
Is connected to the cosine input to the RDC module 78 and the coil 104 is grounded.

Also in this case, the operation of the detection circuit shown in FIG. 5 and the operation of FIGS. 3 and 4 are the same. That is, the phase of the difference between the signal amplitudes flowing through the coils of the respective phases is compared with the reference signal input with the phase shifted of the signal source 50 by the RDC module 78, and the digital synchronization position signal 82 is generated by the comparison result.

As can be seen by paying attention to FIG. 2, another embodiment of the synchro resolver is shown. This embodiment is shown in FIG. 1 except that the magnetic flux path on one side is formed only for the coil in the stator assembly on one side and does not extend to the coil of the opposing pole piece provided on the opposing stator assembly. The configuration is similar to that shown. Thus, for example, for phase A, coils 28a and 30a are connected in series and are either wound or connected to provide opposite magnetic polarities upon excitation.

Similarly, the coils 32a and 34a provided on the opposite pole pieces 18a and 20a are connected in series so as to give opposite magnetic polarities. These coils also have corresponding opposite pole pieces 12a and 14a with opposite polarities.
Are arranged so as to have a reverse magnetic polarity. In this way, the coil 32a will have an N-pole magnetic polarity that opposes the N-pole magnetic polarity of the coil 28a. Coil 30
a has a south pole magnetic polarity opposite to the south pole magnetic polarity of the coil 34a. In this way, the coils 28a-34a are connected to the reference signal source.
When excited by 50, separate flux paths 106a and 108a will be formed. Of these, the magnetic flux path 106a returns to the pole piece 12a through the stator pole piece 12a, the stator assembly 10, the stator pole piece 14a, and a part of the slider 22 in the longitudinal direction. On the other hand, the magnetic flux path 108a passes through similar paths to the stator pole pieces 18a, 20a and the slider 22.

Although a four phase resolver has been described above, it should be noted that the present invention allows for applications to different phase number embodiments. What is important in the present invention is a reluctance resolver for differential phase comparison. The common mode impedance due to this differential phase comparison is canceled and the signal is converted from a multi-phase unipolar signal to a multi-phase bipolar signal. Here, for example, a converter for converting from multiple phases (4 phases) to 2 phases is shown.

Further, while the above embodiment shows two stator assemblies, the resolver of the present invention can also be used with a single stator assembly, as shown in FIG. The mechanical position accuracy in that case is stricter than that of the above-described embodiment, but except for that, almost the same result as that of the embodiment of FIG. 2 is obtained.

The configuration of the magnetic flux path of the coil in this example is substantially the same as in the previous embodiment and is therefore given the corresponding reference number.

Since the above linear resolver uses the difference between phases, it operates for more than two phases. This resolver cannot provide a negative impedance when the teeth are misaligned, only a positive impedance when matched. To obtain a negative signal, another phase is used, preferably a 180 ° offset phase.

The terms and expressions used above are used for convenience of explanation and do not impose any limitation. Also,
The use of such terms and expressions is not intended to exclude some or all of the features illustrated or described above. Therefore, it goes without saying that various modifications can be made without departing from the scope of the present invention.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a synchro resolver according to a first embodiment of the present invention, and FIG. 2 is a vertical sectional view of a synchro resolver according to a second embodiment of the present invention. FIG. 6 is a schematic view of another embodiment of the synchro resolver detection circuit, and FIG. 6 is a vertical sectional view of the synchro resolver according to the third embodiment of the present invention. [Explanation of symbols of main parts] 10,16 ... Stator assembly 12a, 14a, 18a, 20a, 12b, 14b, 18b, 20b, 12c, 14c, 18c, 20
c, 12d, 14d, 18d, 20d …… stator pole piece 22 …… slider 24 …… slider tooth 26 …… stator pole piece tooth 50 …… signal source 52 …… power amplifier 54,56,58,60,98,100… … Coil 62,64,66,68,74,96 …… Resistor 70,72,86,92 …… Differential amplifier 80 …… Phase shifter 84 …… Voltage divider circuit

Claims (4)

[Claims] 1. A slider having a plurality of teeth of the same pitch arranged in the longitudinal direction on a side surface of a member movable in the longitudinal direction, and a plurality of pole pieces protruding toward a surface of the slider having the teeth. A stator having a plurality of pole piece teeth facing the teeth of the slider with a slight gap in the pole piece, coils wound around the pole pieces of the stator, and an oscillator for exciting each of the coils. A magnetic circuit in which adjacent pole pieces of the stator are magnetized to have mutually different polarities and which is closed in cooperation with the slider is formed independently of at least three circuits in the axial direction. The pole piece teeth of the two pole pieces of the stator included in one of the circuits are spaced from each other by an integral multiple of the pitch of the slider teeth, and the pole piece teeth of the adjacent circuits are an integral multiple of the pitch of the slider teeth. In contrast The phases used for detection are shifted by one-pitch of the number of phases, and the change in current generated in the coil due to the change in the inductance due to the degree of matching of the teeth of the slider with respect to the teeth of the stator is extracted as a signal to amplify the two different phases. And a differential amplifying means for obtaining a position signal based on the generated signal. 2. A slider having a plurality of teeth of the same pitch arranged in the longitudinal direction on both side surfaces of a member movable in the longitudinal direction, and a plurality of poles protruding toward one side surface having the teeth of the slider. A plurality of pole piece teeth, each of which has a plurality of pole piece teeth and faces the teeth of the slider with a slight gap between the pole pieces; A magnetic circuit is provided which includes a coil wound around a pole piece and an oscillator for exciting each coil, magnetizes adjacent pole pieces of each stator to polarities different from each other, and forms a closed magnetic circuit in cooperation with the slider. At least three circuits are independently formed in the axial direction, and the pole piece teeth of the two pole pieces of the stator included in one of the circuits are separated from each other by an integral multiple of the pitch of the slider teeth and are adjacent to each other. Circuits to each other The pole piece teeth are shifted by an integer multiple of the pitch of the slider teeth, which is 1 / pitch of the number of phases used for position detection, and the inductance changes due to the degree of matching of the teeth of the slider with the teeth of the stator. A linear synchro resolver device comprising: a differential amplification means for extracting a change in current generated in a coil as a signal and obtaining a position signal based on signals differentially amplified for two different phases. 3. The pole pieces facing each other of the stator are magnetized to have the same polarity as each other.
The linear synchro resolver device according to the item. 4. The linear synchro resolver device according to claim 2, wherein the pole pieces facing each other of the stator are magnetized to have polarities different from each other.