JP2008170178A - Resolver system and electric power steering apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resolver system and an electric power steering apparatus, capable of improving the detection accuracy of the rotation angle to be detected by a resolver. <P>SOLUTION: In the resolver system of the electric power steering apparatus, a CPU 61 acquires amplitude values Asin&theta;+N, Acos&theta;+N of output signals that are output from a first resolver and the like by using an amplitude calculating section 61a, compensates the amplitude values Asin&theta;+N, Acos&theta;+N acquired by the amplitude calculating section 61a, by using a compensated value outputting section 61c which subtracts an error value N (=N') therefrom due to the noise induced in an input-side detection coil or an output-side detection coil by fluxes generated by a rotary transformer, and calculates the rotation angle &theta; of a rotor relative to a stator, based on the compensated amplitude values Asin&theta;, Acos&theta; by using an arc tangent calculating section 61f. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a resolver system including a resolver and a signal processing unit thereof, and an electric power steering apparatus using the resolver system.

  In a resolver having a rotary transformer composed of a primary side coil provided on a stator (stator) and a secondary side coil provided on a rotor (rotor) facing the primary side coil, magnetic flux leaking from the rotary transformer ( (Hereinafter referred to as “leakage magnetic flux”) easily interferes with the iron cores of the rotor and the stator or the input coils and output coils wound around them. The same applies to the case where the rotor is provided with the primary side coil and the stator is provided with the secondary side coil.

If such a leakage magnetic flux from the rotary transformer interferes with the stator core or the like, it is superimposed on the output signal of the resolver as induction noise, which may adversely affect the rotational angle detection accuracy. For this reason, in the invention of the “brushless type rotation detection device” disclosed in Patent Document 1 below, by providing a stator magnetic shield that can shield magnetism between the rotary transformer and the iron core of the stator, This prevents the leakage magnetic flux from interfering with the stator iron core and the like, thereby suppressing the influence of the leakage magnetic flux on the output signal.
Japanese Patent Laying-Open No. 2005-102374

  However, even if a stator magnetic shield is provided between the rotary transformer and the iron core of the stator as in the technique disclosed in Patent Document 1, it is difficult to completely shield the leakage magnetic flux from the rotary transformer. . For this reason, there is a problem that a part of the leakage magnetic flux that cannot be shielded by the stator magnetic shield part interferes with the iron core of the stator and the like, which may reduce the rotation angle detection accuracy.

  In addition, when the resolver is configured, the need for such a stator magnetic shielding portion increases the number of parts, and the cost of the product as a resolver increases due to the increase in the number of management steps and the cost of the parts themselves. There also arises a problem that directly leads to an increase.

  Furthermore, since it is necessary to provide such a stator magnetic shielding part and a space must be secured between the rotary transformer and the iron core of the stator, the resolver becomes long in the direction of the rotation axis of the rotor. For this reason, the problem that it leads to the enlargement of a resolver inevitably arises, and the problem that the weight of resolver itself increases and counters the trend of miniaturization and weight reduction also arises.

  Also, in order to avoid interference of leakage magnetic flux from the rotating transformer, the resolver becomes longer in the direction of the rotation axis of the rotor even in the case of adopting a configuration in which the interval between the rotating transformer and the iron core of the stator is increased. There arises a problem that the size of the resolver is increased.

  Further, when an electric power steering apparatus is configured using a resolver having such a low detection accuracy, an assist force is generated according to a steering state (for example, steering torque or steering angle) detected by the resolver. As a result, a problem arises that the driver may be given an uncomfortable feeling of steering.

  The present invention has been made to solve the above-described problems, and its purpose is to provide (1) a resolver system capable of improving the detection accuracy of the rotation angle by the resolver, and (2) product cost of the resolver. To provide a resolver system that can reduce the size and weight, and (3) to provide an electric power steering device that can improve the steering feeling given to the driver.

In order to achieve the above object, in the resolver system according to claim 1, a primary side coil provided in one of the stator and the rotor and the other side of the stator and the rotor facing the primary side coil are provided. A rotary transformer composed of a secondary side coil, an input coil provided in a stator or rotor provided with the secondary side coil of the rotary transformer and connected in parallel to the secondary side coil, and When an AC signal is input to the stator or rotor provided with a primary coil and an AC signal is input to the primary coil, an output signal whose amplitude increases or decreases according to the rotation angle of the rotor with respect to the stator is output. An resolver having an output coil,
An amplitude value acquisition process for acquiring the amplitude value of the output signal output from the resolver, and an amplitude value acquisition process for an error due to noise generated by the magnetic flux generated by the rotary transformer being induced in the input coil or the output coil. An amplitude value correction process for correcting the amplitude value acquired by the method, and a rotation angle calculation process for calculating the rotation angle of the rotor relative to the stator based on the amplitude value corrected by the amplitude value correction process; A signal processing unit having
It is a technical feature to have.

  In a resolver system according to a second aspect of the present invention, in the first aspect, between the primary coil of the rotary transformer and the input coil or the output coil, or the secondary coil of the rotary transformer and the input coil or the output A technical feature is that a magnetic shield that can shield magnetism is not provided between the coil and the coil.

  Furthermore, in the resolver system of claim 3, in claim 1 or 2, the signal processing unit is configured to rotate the rotor of the resolver within a rotatable range thereof, and to output the maximum amplitude value and the minimum value of the output signal. A correction value generation process that uses a value obtained by dividing the sum of amplitude values by 2 as a correction value by the amplitude value correction process, wherein the amplitude value correction process uses the correction value generated by the correction value generation process as the correction value; A technical feature is that the corrected amplitude value is subtracted from the amplitude value of the output signal output from the resolver.

  Furthermore, the resolver system according to claim 4 further comprises a semiconductor memory device that stores the correction value generated by the correction value generation process according to claim 3, and the amplitude value correction process is stored in the semiconductor memory device. A technical feature is that the corrected correction value is subtracted from the amplitude value of the output signal output from the resolver to obtain the corrected amplitude value.

  In order to achieve the above object, the electric power steering apparatus according to claim 5 detects the steering state and generates an assist force corresponding to the steering state by the motor to assist the steering. It is an apparatus, Comprising: It is a technical characteristic to detect the said steering state using the resolver system as described in any one of Claims 1-4.

  In the invention of the resolver system according to claim 1, the signal processing unit acquires the amplitude value of the output signal output from the resolver by the amplitude value acquisition process, and the magnetic flux generated by the rotary transformer is output from the input coil or the output by the amplitude value correction process. An error due to noise generated by induction in the coil is corrected with respect to the amplitude value acquired by the amplitude value acquisition processing. Then, by the rotation angle calculation process, the rotation angle of the rotor with respect to the stator is calculated based on the amplitude value corrected by the amplitude value correction process. As a result, even if the leakage magnetic flux from the rotary transformer interferes with the stator, the rotor, the input coil, or the output coil, the error due to the noise generated thereby is corrected with respect to the amplitude value. It is possible to prevent the detection accuracy from being lowered due to the interference. Therefore, the detection accuracy of the rotation angle by the resolver can be improved.

  In the invention of the resolver system according to claim 2, the resolver is provided between the primary coil of the rotary transformer and the input coil or the output coil, or between the secondary coil of the rotary transformer and the input coil or the output coil. The magnetic shield which can shield the magnetism is not provided. Thus, as in the technique disclosed in Patent Document 1 described above, the parts are compared with those provided with a stator magnetic shield (magnetic shield) between the rotary transformer and the stator core (stator). The score can be reduced. Therefore, the product cost of the resolver can be reduced, and the size and weight can be reduced by the amount not provided with such a magnetic shield.

  In the invention of the resolver system according to claim 3, the signal processing unit calculates the maximum amplitude value and the minimum amplitude value of the output signal obtained by rotating the resolver rotor within the rotatable range by the correction value generation processing. A value obtained by dividing the sum by 2 is used as a correction value by the amplitude value correction processing, and after correction by subtracting the correction value generated by the correction value generation processing from the amplitude value of the output signal output from the resolver by the amplitude value correction processing. The amplitude value of As a result, the correction value can be obtained by a relatively simple calculation process, so that the configuration of the signal processing unit can be simplified.

  In the invention of the resolver system according to claim 4, the semiconductor memory device that stores the correction value generated by the correction value generation processing is provided, and the amplitude value correction processing outputs the correction value stored in the semiconductor memory device from the resolver. The amplitude value after correction is subtracted from the amplitude value of the output signal to be corrected. As a result, for example, in the inspection process of the resolver system, the correction value obtained is stored in the semiconductor storage device, so that the signal processing unit obtains the correction value by the correction value generation process in the amplitude value correction process. There is no need to calculate each time, and the correction value can be read from the semiconductor memory device and used for the correction process as appropriate. Therefore, the calculation speed of the signal processing unit is not slowed down.

  In the electric power steering apparatus according to the fifth aspect, the steering state is detected using the resolver system according to any one of the first to fourth aspects. Thereby, according to the steering state with high detection accuracy, the assist force can be generated by the motor to assist the steering, so that the assist suitable for the driver's steering state is possible. Therefore, the steering feeling given to the driver can be improved.

  Embodiments of a resolver system and an electric power steering apparatus using the same will be described below with reference to the drawings. First, the configuration of the electric power steering apparatus 20 according to the present embodiment will be described with reference to FIGS.

  As shown in FIGS. 1 and 2, the electric power steering apparatus 20 mainly includes a steering wheel 21, a steering shaft 22, a pinion shaft 23, a rack shaft 24, a torque sensor 30, a motor 40, a motor resolver 44, and a ball. It is composed of a screw mechanism 50, an ECU 60, and the like, and detects the steering state by the steering wheel 21 by the torque sensor 30, and generates assist force according to the steering state by the motor 40 to assist the steering by the driver. is there. Note that wheels (not shown) are connected to both sides of the rack shaft 24 via tie rods or the like.

  That is, as shown in FIGS. 1 and 2, one end side of a steering shaft 22 is connected to the steering wheel 21, and the other end side of the steering shaft 22 is connected to a torque sensor 30 housed in a pinion housing 25. The input shaft 23 a and the torsion bar 31 are connected by a pin 32. Further, the output shaft 23b of the pinion shaft 23 is connected to the other end 31a of the torsion bar 31 by spline coupling.

  The input shaft 23a of the pinion shaft 23 is rotatably supported in the pinion housing 25 by the bearing 33a, and the output shaft 23b is also rotatably supported by the bearing 33b. Further, between the input shaft 23a and the pinion housing 25, The first resolver 35 and the second resolver 37 are provided between the output shaft 23b and the pinion housing 25, respectively. The first resolver 35 and the second resolver 37 constituting the torque sensor 30 are capable of detecting the rotation angle by the steering wheel 21 and are electrically connected to the ECU 60 via terminals 39, respectively. On the other hand, a pinion gear 23c is formed at the end of the output shaft 23b of the pinion shaft 23, and a rack groove 24a of the rack shaft 24 is coupled to the pinion gear 23c so as to be able to mesh. Thus, a rack and pinion type steering mechanism is configured.

  The rack shaft 24 is accommodated in the rack housing 26 and the motor housing 27, and a ball screw groove 24b is formed in a spiral shape at an intermediate portion thereof. A cylindrical motor shaft 43 is provided around the ball screw groove 24 b and is supported by a bearing 29 so as to be rotatable coaxially with the rack shaft 24. This motor shaft 43 constitutes the motor 40 together with the stator 41, the excitation coil 42, etc., and the field generated by the excitation coil 42 wound around the stator 41 is generated on the outer periphery of the motor shaft 43 corresponding to the rotor. The motor shaft 43 can be rotated by acting on the provided permanent magnet.

  The ball screw mechanism 50 includes a ball screw nut 52 attached to the inner periphery of the motor shaft 43, and a number of ball screw mechanisms 50 interposed between the ball screw groove of the ball screw nut 52 and the ball screw groove of the rack shaft 24 so as to allow rolling. The rack shaft 24 is movable in the axial direction by the rotation of the motor shaft 43. Thereby, the rotational torque of the forward / reverse rotation of the motor shaft 43 can be converted into a reciprocating motion in the axial direction of the rack shaft 24, and this reciprocating motion together with the rack shaft 24 forms a rack and pinion type steering mechanism. It becomes an assist force that reduces the steering force of the steering wheel 21 via 23. A motor resolver 44 capable of detecting the rotation angle (electrical angle) θMe of the motor shaft 43 is provided between the motor shaft 43 of the motor 40 and the motor housing 27. The motor resolver 44 is not shown. It is electrically connected to ECU 60 via a terminal.

  As shown in FIG. 3, the ECU 60 includes a CPU 61, a nonvolatile memory 62, buffer amplifiers 63, 64, 65, and the like. A first resolver 35, a second resolver 37, and a motor resolver 44 are electrically connected to the CPU 61 via buffer amplifiers 63, 64, 65, and a non-volatile memory 62 (EEPROM or EEPROM) is connected via a system bus. EPROM, etc.) and a semiconductor memory device as a main storage device (not shown) are connected. The main storage device stores programs, data, and the like related to the assist control processing by the motor 40 and the resolver signal processing described later.

  As a result, an excitation signal can be output from the output port Po of the CPU 61 to the first resolver 35 and the like via the buffer amplifier 63, while the analog-digital conversion input A / D of the CPU 61 is output from the first resolver 35. The output signals of the sin phase and the cos phase can be input via the buffer amplifiers 64 and 65.

  The CPU 61 shown in FIG. 3 corresponds to a “signal processing unit” recited in the claims, and the first resolver 35 and the like can correspond to a “resolver” recited in the claims. Moreover, the concept which united both can correspond to embodiment of the resolver system of this invention, and code | symbol RS is attached | subjected in FIG.

  With this configuration, the rotation angle of the steering shaft 22, that is, the rotation angle θTm by the steering wheel 21 can be detected by the electrical angle θT1 by the first resolver 35 and the electrical angle θT2 by the second resolver 37. Further, the torsion amount (corresponding to the steering torque) of the torsion bar 31 can be detected as the torsion angle from the angle difference between the electrical angle θT1 and the electrical angle θT2, the angle ratio, or the like. Since the steering torque T can be calculated from the relative rotation angle difference Δθ, which is the twist angle of the torsion bar 31, and the spring coefficient of the torsion bar 31, the steering force is assisted according to the steering torque T. The known assist control is performed by the CPU 61 of the ECU 60. As a result, the steering by the driver can be assisted by the steering force generated by the motor 40 described above. Note that the rotation angle θTm and the steering torque T of the steering wheel 21 (steering shaft 22) can correspond to the “steering state” described in the claims.

  Next, configurations of the first resolver 35, the second resolver 37, and the motor resolver 44 will be described with reference to FIG. 4 and FIG. Here, among these, the first resolver 35 will be described as a representative.

  As shown in FIG. 4A, the first resolver 35 is a so-called brushless type resolver, which is a stator St, a rotor Rt, a rotary transformer TR, an input side detection coil SC-r, and an output side detection coil SC-s1, SC. -S2 etc.

  The stator St is composed of an annular belt-shaped base portion that can be accommodated in a cylindrical housing (not shown), and a plurality of stator iron cores SX-s protruding from the base portion toward the center of the circle. Called. The stator core SX-s is wound with output side detection coils SC-s1 and SC-s2. The output-side detection coil SC-s1 and the output-side detection coil SC-s2 are wound so that their electrical angles are shifted from each other by 90 degrees. Further, when the number of counter electrodes is 1 (so-called 1X), it is also 90 mechanically. It is arranged at a deviated degree. Hereinafter, the case of 1X is illustrated for ease of explanation. As shown in FIG. 4B, these output side detection coils SC-s1, SC-s2 have output terminals t3 to t6 that can output an output signal to the buffer amplifiers 64, 65 described above. Each is electrically connected.

  The rotor Rt is a plurality of rotor shafts J that protrudes in the circumferential direction so as to be opposed to the stator core SX-s of the stator St described above and the rotor shaft J that is configured to be rotatable around the axis of the stator St. The rotor iron core SX-r is also called a rotor. An input side detection coil SC-r is wound around the rotor core SX-r, and is electrically connected in parallel to a secondary side excitation coil DC-r of a rotary transformer TR described below. Yes.

  As shown in FIG. 4 (A), the rotary transformer TR includes a primary side exciting coil DC-s wound around the primary side iron core DX-s and a secondary side wound around the secondary side iron core DX-r. It is composed of an exciting coil DC-r. The primary side excitation coil DC-s is wound around a primary side iron core DX-s formed in a U-shaped annular shape with a cross section opened to the inner peripheral side over the entire inner periphery of the stator St. As shown in FIG. 4B, the primary side excitation coil DC-s is electrically connected to input terminals t1 and t2 through which the excitation signal can be input via the buffer amplifier 63 described above.

  On the other hand, the secondary side excitation coil DC-r is wound around the secondary side iron core DX-r so as to be concentrically opposed to the primary side excitation coil DC-s. That is, the secondary side iron core DX-r is formed in a U-shaped annular shape whose cross section is open to the outer circumference side over the entire outer circumference of the rotor Rt, and the secondary side iron core DX-s of the primary side iron core DX-s on the stator St side is formed. A rectangular magnetic path can be formed together with a U-shaped cross section. As a result, the secondary side exciting coil DC-r is wound around the secondary side iron core DX-r of the rotor Rt, so that it can be electromagnetically coupled to the primary side exciting coil DC-s of the stator St side. Become. For this reason, the excitation signal input to the primary side excitation coil DC-s can be taken out from the secondary side excitation coil DC-r. As shown in FIG. 4B, the input side detection coil SC-r is electrically connected to the secondary side excitation coil DC-r.

  By configuring the first resolver 35, the second resolver 37, and the motor resolver 44 as described above, when a sine wave excitation signal having a predetermined frequency is input from the CPU 61 to the input terminals t1 and t2 via the buffer amplifier 63. An excitation signal is induced from the primary side excitation coil DC-s of the rotary transformer TR to the secondary side excitation coil DC-r and input to the input side detection coil SC-r. And this excitation signal is induced | guided | derived to output side detection coil SC-s1, SC-s2 which opposes the input side detection coil SC-r, and it passes through buffer amplifiers 64 and 65 from each output terminal t3-t6. To the CPU 61.

  At this time, the amplitude of the output signal output from the first resolver 35 or the like increases or decreases depending on the rotation angle θ of the rotor Rt with respect to the stator St. For example, in the case of a 1 × resolver, as shown in FIG. 5 (A), the electrical angle (phase) of the sin-phase output signal and the cos-phase output signal are shifted by 90 degrees as envelopes of the respective amplitude values. Since a sine wave (or cosine wave) for one cycle is obtained, the rotation angle θ of the rotor Rt relative to the stator St can be calculated from this phase difference. When the number of counter electrodes is n, an n-cycle sine wave or the like is obtained as the envelope.

That is, the output-side detection coil SC-s1 outputs a sin-phase output signal A · sinθ, and the output-side detection coil SC-s2 outputs a cos-phase output signal A · cosθ (A is , Amplification factor by buffer amplifiers 64 and 65). Therefore, by taking the arc tangent (tan ⁻¹ ) of both, it becomes possible to obtain the rotation angle θ of the rotor Rt with respect to the stator St, and the resolution improves as the counter electrode number n increases. In the present embodiment, for example, the number of counter electrodes of the first resolver 35 is set to “5”, and the number of counter electrodes of the second resolver 37 is set to “6”.

  As described above, the output signal output from the first resolver 35 and the like is signal-processed by the CPU 61, whereby the rotation angle θ of the rotor Rt with respect to the stator St can be calculated. However, as described in the “Background Art” section, the leakage magnetic flux from the rotary transformer TR (broken line Mn shown in FIGS. 4A and 4B) is caused by the stator core SX-s and the output side detection coil SC. When interfering with -s1, SC-s2, etc., it will be superimposed on the output signal of the first resolver 35 etc. as induction noise.

Then, for example, as shown in FIG. 5B, the sin-phase output signal A · sinθ and the cos-phase output signal A · cosθ as the envelope of the amplitude value to be output are shifted by the amount of induced noise. Is output. That is, the output signal of the sin phase is A · sin θ + N, and the output signal of the cos phase is A · cos θ + N. For this reason, if the rotation angle θ is determined by the arc tangent (tan ⁻¹ ) of both while including this noise component (the error due to noise), the accuracy of θ will be reduced, and various problems as described above will occur. Cause.

  Therefore, in the resolver system RS used in the electric power steering apparatus 20 according to the present embodiment, a resolver signal process that can avoid the influence of such induction noise by providing a signal processing unit as shown in FIG. It is carried out.

  That is, as shown in FIG. 6, in the resolver system RS of the present embodiment, the CPU 61 performs an amplitude value calculation unit 61a, a correction value generation unit 61b, a correction value output unit 61c, subtraction units 61d and 61e, and an arctangent calculation unit 61f. The rotation angle θ is obtained by performing resolver signal processing including the above.

  When an output signal from the first resolver 35 or the like is input to the CPU 61 via the buffer amplifiers 64 and 65, the amplitude value is first calculated by the amplitude value calculation unit 61a. Specifically, A · sinθ · sinωt + Nsinωt = (A · sinθ + N) sinωt is input as an output signal of the sin phase, and A · cosθ · sinωt + Nsinωt = (A · cosθ + N) sinωt is input as the output signal of the cos phase. Therefore, the amplitude values A · sin θ + N and A · cos θ + N are calculated by a known signal processing technique (for example, the signal processing technique disclosed in Japanese Patent No. 3508718).

  Next, when the correction value output unit 61c reads the correction value N ′ (the error due to noise) from the nonvolatile memory 62 and outputs it to the subtraction units 61d and 61e, the subtraction units 61d and 61e have the amplitude value A Subtract the correction value N ′ from sin θ + N and A · cos θ + N, respectively. The correction value N ′ (− N) is generated by a correction value generation unit 61b described later, and is set approximately equal to the absolute amount of the noise component N.

  As a result, the amplitude values A · sin θ (= A · sin θ + N−N) and A · cos θ (= A · cos θ + N−N) from which the noise component N equivalent is removed are output from the subtracting units 61d and 61e, and the arc It is input to the tangent calculation unit 61f. For this reason, the arc tangent calculation unit 61f, based on the sin phase output signal A · sin θ and the cos phase output signal A · cos θ not including the noise component N, as described above, the rotation angle of the rotor Rt with respect to the stator St. θ can be calculated.

  Here, the flow of the correction value generation processing by the correction value generation unit 61b will be described with reference to FIG. The correction value generation process is performed in a range in which the inspection operator or the inspection jig can rotate the rotor Rt such as the first resolver 35 (for example, 0 to 360 degrees) in the inspection process of the resolver system RS. The correction value N ′ obtained by the rotation is stored in the nonvolatile memory 62. For this reason, it is not always necessary to perform normal resolver signal processing.

  As shown in FIG. 7, in the correction value generation process, while the rotor Rt of the first resolver 35 etc. is rotating, the output signal output from the first resolver 35 etc. is acquired in step S101, and further the step In S103, an amplitude value is calculated. The processes in steps S101 and S103 are the same as the normal resolver signal process described above, and are performed by the amplitude value calculator 61a. Next, in step S105, a process for storing the maximum and minimum amplitude values is performed, and in step S107, it is determined whether or not the rotor Rt has made one rotation. That is, in steps S101 to S107, the maximum value / minimum value of the amplitude value output from the first resolver 35 and the like while the rotor Rt rotates once is stored.

  If it is determined in step S107 that the rotor Rt has made one revolution (S107; Yes), the maximum value Max and the minimum value Min stored in the main storage device or the like are read in the subsequent step S109 and corrected in the next step S111. Processing for calculating the value N (error due to noise) ′ is performed. Specifically, a value obtained by dividing the sum of the maximum value Max and the minimum value Min by 2 is set as a correction value N ′ (= (maximum value Max + minimum value Min) / 2).

  For example, although A · sin θ + N and A · cos θ + N are obtained as amplitude values, -1 ≦ sin θ ≦ + 1 (−1 ≦ cos θ ≦ + 1) is obtained by rotating the rotor Rt once, so the maximum value Max is A + N, Since the minimum value Min is −A + N, the sum of both is (A + N) + (− A + N) = 2N. Therefore, N corresponding to the noise component can be calculated by dividing 2N by 2.

  Thus, the correction value N ′ (= N) calculated in step S111 is stored in the non-volatile memory 62 by the subsequent write processing of the correction value N ′ in step S113, and a series of main correction value generation processing ends. .

  The correction value N ′ stored in the nonvolatile memory 62 in this way is appropriately read out from the nonvolatile memory 62 by the amplitude value correcting unit 61c of the resolver signal processing described above, and from the amplitude values A · sin θ + N and A · cos θ + N. By subtracting, the amplitude value is corrected.

  The correction value generation unit 61b is performed individually for each resolver. For this reason, in the present embodiment, the correction value N ′ stored by the ECU 60 is generated for each resolver (the first resolver 35, the second resolver 37, and the motor resolver 44) and stored in the nonvolatile memory 62. . Further, when the signal processing unit of the ECU is provided for each resolver, the correction value generation processing is performed by the correction value generation unit 61b described above individually.

  In the above-described example, the correction value generation processing is performed by the resolver inspection process or the like. However, if the electric power steering device is equipped with a manipulator or the like that rotates such a resolver within a predetermined range, the correction value generation processing is appropriately performed. The correction value generation processing by the correction value generation unit 61b described above may be performed.

  As described above, in the resolver system RS of the electric power steering apparatus 20 according to the present embodiment, the CPU 61 of the ECU 60 causes the amplitude value of the output signal output from the first resolver 35 and the like by the amplitude value calculation unit 61a. A · sin θ + N and A · cos θ + N are obtained, and the correction value output unit 61c causes the magnetic flux generated by the rotating transformer TR to be induced to the input side detection coil SC-r or the output side detection coils SC-s1 and SC-s2 and generated. Is subtracted from the amplitude values A · sin θ + N and A · cos θ + N acquired by the amplitude value calculator 61a to correct the error. Then, the arc tangent calculation unit 61f calculates the rotation angle θ of the rotor Rt with respect to the stator St based on the corrected amplitude values A · sin θ and A · cos θ. Thus, even if the leakage magnetic flux Mm from the rotary transformer TR interferes with the stator St, the rotor Rt, the input side detection coil SC-r, or the output side detection coil SC-s1, the error N due to the noise generated thereby is amplified. Since the value is corrected, it is possible to prevent the detection accuracy from being lowered due to the interference of the leakage magnetic flux Mm. Therefore, the detection accuracy of the rotation angle by the first resolver 35 or the like can be improved.

  Further, since the detection accuracy of the rotation angle θTm and the steering torque T of the steering wheel 21 (steering shaft 22) is increased, the assisting force is generated by the motor in accordance with these to assist the steering, so that the driver's steering state can be obtained. Suitable assist is possible. Therefore, the steering feeling given to the driver can be improved.

  Further, the first resolver 35 or the like is provided between the primary side excitation coil DC-s and the input side detection coil SC-r of the rotary transformer TR or the output side detection coils SC-s1 and SC-s2, or the secondary of the rotary transformer TR. Between the side excitation coil DC-r and the input coil or the input side detection coil SC-r or between the output side detection coils SC-s1 and SC-s2, a magnetic shield plate (magnetic shield) that can shield magnetism is provided. ) Is not provided. Thus, as in the technique disclosed in Patent Document 1 described above, the parts are compared with those provided with a stator magnetic shield (magnetic shield) between the rotary transformer and the stator core (stator). The score can be reduced. Accordingly, since the magnetic shield plate (magnetic shield) is not provided, the product cost of the first resolver 35 and the like can be reduced and the size and weight can be reduced.

It is a lineblock diagram showing the composition of the electric power steering device concerning this embodiment. FIG. 2 is an enlarged view inside an ellipse by a one-dot chain line II shown in FIG. 1. It is a block diagram which shows the structure of the resolver system used for the electric power steering device which concerns on this embodiment. FIG. 4A is a schematic schematic diagram showing the mechanical configuration of the resolver, and FIG. 4B is a circuit diagram showing the electrical configuration of the resolver. 5A is a waveform diagram showing a waveform example (upper stage) of the excitation signal input to the resolver and a waveform example of the output signal output from the resolver (middle stage, lower stage), and FIG. 5B is a diagram showing the rotation of the rotor. It is a wave form diagram which shows the example of a waveform by the amplitude which changes with it. It is a block diagram which shows the structural example of the resolver signal processing by CPU. It is a flowchart which shows the flow of a correction value production | generation process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 ... Electric power steering apparatus 30 ... Torque sensor 35 ... 1st resolver (resolver)
37 ... Second resolver (resolver)
40 ... motor 44 ... motor resolver (resolver)
60 ... ECU
61 ... CPU (signal processing unit)
61a: Amplitude value calculation unit (amplitude value acquisition processing)
61b ... Correction value generation unit (correction value generation processing)
61c: Correction value output unit (rotation angle calculation process)
61d, 61e ... subtraction unit (amplitude value correction processing)
61f ... Arc tangent calculation section (rotation angle calculation processing)
62... Nonvolatile memory 62 (semiconductor memory device)
DC-s ... Primary side excitation coil (Primary side coil)
DC-r ... Secondary excitation coil (secondary coil)
DX-s ... Primary side core DX-r ... Secondary side core RS ... Resolver system Rt ... Rotor (rotor)
SC-r ... Input side detection coil (input coil)
SC-s1 ... Output side detection coil (output coil)
SC-s2 ... Output side detection coil (output coil)
St ... Stator (stator)
SX-s ... Stator core SX-r ... Rotor core TR ... Rotating transformer

Claims (5)

A rotary transformer comprising a primary side coil provided on one of the stator and the rotor and a secondary side coil provided on the other side of the stator and the rotor so as to face the primary side coil; An input coil provided on a stator or rotor provided with a secondary coil and connected in parallel to the secondary coil, and provided on a stator or rotor provided with a primary coil of the rotary transformer An output coil that outputs an output signal whose amplitude increases or decreases according to a rotation angle of the rotor with respect to the stator when an AC signal is input to the primary coil;
An amplitude value acquisition process for acquiring the amplitude value of the output signal output from the resolver, and an amplitude value acquisition process for an error due to noise generated by the magnetic flux generated by the rotary transformer being induced in the input coil or the output coil. An amplitude value correction process for correcting the amplitude value acquired by the method, and a rotation angle calculation process for calculating the rotation angle of the rotor relative to the stator based on the amplitude value corrected by the amplitude value correction process; A signal processing unit having
A resolver system comprising:   Magnetic shielding capable of shielding magnetism between the primary coil of the rotary transformer and the input coil or the output coil, or between the secondary coil of the rotary transformer and the input coil or the output coil. The resolver system according to claim 1, wherein the resolver system is not provided with a body. The signal processing unit is configured to calculate a value obtained by dividing a sum of a maximum amplitude value and a minimum amplitude value of the output signal obtained by rotating the resolver rotor within a rotatable range, by the amplitude value correction process. Correction value generation processing to be a correction value by
2. The amplitude value correction process, wherein the correction value generated by the correction value generation process is subtracted from an amplitude value of an output signal output from the resolver to obtain the corrected amplitude value. Or the resolver system of 2. A semiconductor storage device for storing the correction value generated by the correction value generation process;
4. The amplitude value correction processing subtracts the correction value stored in the semiconductor memory device from an amplitude value of an output signal output from the resolver to obtain the corrected amplitude value. The described resolver system. An electric power steering device that detects a steering state and assists steering by generating an assist force according to the steering state by a motor,
The electric power steering apparatus characterized by detecting the said steering state using the resolver system as described in any one of Claims 1-4.

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