JP2006010336A - Resolver anomaly detection apparatus and transmission-ratio-variable steering apparatus for vehicle using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resolver anomaly detection apparatus capable of appropriately determining anomalies of a resolver even in the case that an offset value changes at normal times according to the rotating speed of a rotator and provide a transmission-ratio-variable steering apparatus for vehicles using the same. <P>SOLUTION: A plurality of sampling values a1-a4, b1-b4 among amplitude modulation signals outputted from the resolver 3 are summated to compute an offset value Ofs. A threshold Th for determining anomalies of the resolver 3 is determined on the basis of the rotating speed V of the rotator 4. An absolute value of the threshold Th for determining anomalies increases as the rotating speed V of the rotator increases. In the case that the computed offset value Ofs exceeds the determined threshold value Th for determining anomalies, it is determined that the resolver 3 is in an anomalous state. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a resolver abnormality detection device and a vehicle transmission ratio variable steering device using the same.

Conventionally, a resolver abnormality detection device has an offset value that is a difference between a total of a plurality of sampling values and a zero value of an amplitude modulation signal corresponding to a rotation angle of a rotating body output from a resolver exceeds a certain threshold value. In this case, it is determined that the resolver is abnormal (see, for example, Patent Document 1).
JP 2001-343253 A

  By the way, it was found that even when the resolver is normal, the offset value generated at the time of high speed rotation is larger than the offset value generated at the time of rotating the rotating body at a low speed. However, according to the conventional resolver abnormality detection device, the determination is made based on a certain threshold value. For example, when the threshold value is set to a threshold value that does not determine that the resolver is abnormal when the resolver is operating at high speed, the following problem occurs. That is, the threshold value is very high for the offset value during low-speed rotation. Therefore, a more appropriate resolver abnormality determination cannot be performed during low-speed rotation. On the other hand, for example, when the threshold value is set to a threshold value that does not determine that the resolver is abnormal when the resolver is rotating at low speed, the following problem occurs. That is, the threshold value is very low with respect to the offset value during high-speed rotation. Therefore, at the time of high-speed rotation, there is a possibility of erroneously determining that the resolver is abnormal although the resolver is normal.

  The present invention has been made in view of such circumstances, and even when the normal offset value changes according to the rotational speed of the rotating body, it is possible to appropriately determine the abnormality of the resolver. It is an object of the present invention to provide a resolver abnormality detection device that can be used, and a vehicle transmission ratio variable steering device using the same.

(1) Resolver abnormality detection device of the present invention A resolver abnormality detection device of the present invention is a resolver abnormality detection device that detects an abnormality of a resolver that outputs an amplitude modulation signal corresponding to a rotation angle of a rotating body. Among them, sampling value input means for inputting a plurality of sampling values, offset value calculation means for calculating an offset value that is a difference from a zero value based on the plurality of sampling values, and a rotation speed for inputting the rotation speed of the rotating body Input means, rotational speed-abnormality determination threshold relation storage means storing rotational speed-abnormality determination threshold relation in which the resolver abnormality determination threshold changes according to the rotational speed, the rotational speed and the rotational speed The abnormality determination threshold value determining means for determining the abnormality determination threshold value based on the abnormality determination threshold value relationship, and the offset value is the abnormality determination value. Abnormality determination means for determining that the resolver is in an abnormal state when the abnormality determination threshold value determined by the threshold value determination means is exceeded.

  Here, the plurality of sampling values may be, for example, two places of the amplitude maximum value and the amplitude minimum value of each period of the amplitude modulation signal that is an output signal of the resolver, or the number of places more than that, for example, four places It is good. Here, when the output signal of the resolver is an ideal sine wave, the output value at the time point when the sum of the sampling values of each period becomes almost zero is taken as the sampling value. Specifically, when the sampling values in one cycle are, for example, four locations, and when one cycle is 0.2 msec, the time points are 0.025 msec, 0.075 msec, 0.125 msec, and 0.175 msec from the cycle start time. The output value at is used as a sampling value. In this case, the former two points are the same positive value, and the latter two points are values obtained by inverting the signs of the values of the former two points.

  Further, when the offset value calculated by the offset value calculation means is the sum of a plurality of sampling values, the abnormality determination threshold value has a positive abnormality determination threshold value and a negative abnormality determination threshold value. Become. Further, when the offset value calculated by the offset value calculating means is an absolute value of the sum of a plurality of sampling values, the abnormality determination threshold value is only the positive abnormality determination threshold value. Further, the rotational speed-abnormality determination threshold value relationship may be a relational expression between the rotational speed and the abnormality determination threshold value, or may be a map showing the relationship between the rotational speed and the abnormality determination threshold value.

(2) Vehicle Transmission Ratio Variable Steering Device of the Present Invention The vehicle transmission ratio variable steering device of the present invention is a transmission ratio that varies the rotation transmission ratio between the steering angle of the steering wheel and the turning angle of the steered wheels. A variable motor, a resolver that outputs an amplitude modulation signal corresponding to the relative rotation angle of the rotor with respect to the stator of the transmission ratio variable motor, and a rotation that calculates a relative rotation angle of the rotor based on the amplitude modulation signal An angle calculating means; a resolver abnormality detecting means for detecting an abnormality of the resolver based on the amplitude modulation signal; and the rotation transmission ratio by restricting relative rotation between the stator and the rotor of the transmission ratio variable motor. The transmission ratio variable motor and the lock device are controlled based on the lock device that locks the lock, the steering angle, the relative rotation angle, and the output signal of the resolver abnormality detection means. Control means for controlling.

  And the characteristic matter of the transmission ratio variable steering apparatus for a vehicle according to the present invention is that the resolver abnormality detecting means has sampling value input means for inputting a plurality of sampling values of the amplitude modulation signal, and the plurality of sampling values. An offset value calculating means for calculating an offset value that is a difference from the zero value based on the above, a rotational speed input means for inputting the rotational speed of the rotor, and a threshold for abnormality determination of the resolver according to the rotational speed Rotation speed-abnormality determination threshold value relationship storage means storing the rotation speed-abnormality determination threshold value relationship, and abnormality determination for determining the abnormality determination threshold value based on the rotation speed and the rotation speed-abnormality determination threshold value relationship And the resolver is abnormal when the offset value exceeds the abnormality determination threshold value determined by the abnormality determination threshold value determination means. And abnormality determining means for determining that the state is to comprise a. Further, when the control means determines that the resolver is in an abnormal state by the abnormality determination means, transmission ratio reduction control for reducing the rotation transmission ratio, or driving the lock device to the locked state The lock control is to be performed.

  Here, in the transmission ratio reduction control, for example, an upper limit value of the rotation transmission ratio is determined, and the upper limit value is set when the command value of the rotation transmission ratio commanded by the control means exceeds the upper limit value. Good. In the transmission ratio reduction control, the rotation transmission ratio commanded by the control means may be reduced to a predetermined ratio.

(1) Effect of the resolver abnormality detection device of the present invention According to the resolver abnormality detection device of the present invention, the rotational speed-abnormality determination threshold relation stored in the rotational speed-abnormality determination threshold relation storage means The threshold value for determining the abnormality of the resolver is changed according to the rotational speed. Thus, since the abnormality determination threshold value is changed according to the rotational speed of the rotating body, an appropriate resolver abnormality determination can be performed according to the rotational speed of the rotating body. That is, even when the rotational speed of the rotating body is low, the determination can be made based on an appropriate abnormality determination threshold, and even when the rotational speed is high, the determination can be made without causing erroneous determination.

(2) Effect of the transmission ratio variable steering apparatus for a vehicle according to the present invention According to the variable transmission ratio steering apparatus for a vehicle of the present invention, the same effect can be obtained by the above-described resolver abnormality detection apparatus of the present invention. And since the abnormality determination of a resolver can be performed appropriately, steering feeling can be improved as a result. For example, the steering feeling can be improved by appropriately driving the transmission ratio variable motor in accordance with prevention of erroneous determination when the rotation speed of the transmission ratio variable motor is high.

  Next, the present invention will be described in more detail with reference to embodiments.

(1) Embodiment of Resolver Abnormality Detection Device of the Present Invention As described above, the resolver abnormality detection device of the present invention has a sampling value input means, an offset value calculation means, a rotational speed input means, and a rotational speed-abnormality determination. Threshold relation storage means, abnormality determination threshold value determination means, and abnormality determination means.

  Here, the rotational speed-abnormality determination threshold value relationship may be such that the absolute value of the abnormality determination threshold value increases as the rotational speed increases. The amplitude modulation signal that is the output signal of the resolver has an offset value that increases as the rotational speed of the rotating body increases. Here, when the rotation speed of the rotating body increases, the amplitude modulation period of the amplitude modulation signal becomes shorter, and as a result, the change in the amplitude modulation slope of the amplitude modulation signal increases. When the change in the amplitude modulation slope increases, the variation of the plurality of sampling values in one period of the amplitude modulation signal increases, and the offset value increases. That is, by increasing the absolute value of the abnormality determination threshold as the rotational speed increases, more appropriate resolver abnormality determination can be performed. Note that the abnormality determination threshold for the rotational speed may be increased linearly or may be increased higher-order. Further, the abnormality determination threshold for the rotation speed may be increased stepwise.

  Further, the rotational speed-abnormality determination threshold value relationship includes a relationship between the rotational speed and a plurality of abnormality determination threshold values, and the abnormality determination means includes a plurality of resolvers according to the plurality of abnormality determination threshold values. The abnormal state may be determined. By using a plurality of abnormality determination thresholds, the abnormal state of the resolver can be determined in more detail. For example, the abnormality determination threshold value may be two types, that is, the abnormality determination threshold value in the attention stage and the abnormality determination threshold value in the warning stage. In this case, the abnormality determination threshold value in the warning stage is set higher than the abnormality determination threshold value in the attention stage. The control of the motor using the resolver may be made different depending on whether the offset value exceeds the abnormality determination threshold value in the attention stage or the warning stage abnormality determination threshold value. it can.

  The resolver may be an assist motor of an electric power steering device that assists the steering force of the vehicle, or a vehicle transmission ratio that makes a rotation transmission ratio between a steering angle of a steering wheel and a turning angle of a steered wheel variable. It can be set as the resolver used for detection of the rotation angle of the electric motor for variable transmission ratio of a variable steering device. By using the resolver abnormality detection device of the present invention for an electric power steering device or a vehicle transmission ratio variable steering device, the electric power steering device or the vehicle transmission ratio variable steering device can be appropriately driven. As a result, the steering performance can be improved.

(2) Embodiment of Variable Transmission Ratio Steering Device for Vehicle of the Present Invention As described above, the variable transmission ratio steering device for a vehicle of the present invention is a transmission ratio variable motor, a resolver, a rotation angle calculating means, and a resolver. An abnormality detection means, a lock device, and a control means are provided. Here, the rotational speed-abnormality determination threshold value relationship stored in the rotational speed-abnormality determination threshold value relationship storage means of the resolver abnormality detection means is the rotation speed, the first abnormality determination threshold value, and the second abnormality determination threshold value. The control means performs the transmission ratio reduction control when the abnormality determination means determines that the offset value is a first abnormal state exceeding the first abnormality determination threshold, The lock control may be performed when it is determined by the abnormality determination means that the offset value is in the second abnormal state exceeding the second abnormality determination threshold. The absolute value of the first abnormality determination threshold value is smaller than the absolute value of the second abnormality determination threshold value.

  That is, when the offset value exceeds the first abnormality determination threshold, the rotation transmission ratio is reduced, and when the offset value exceeds the second abnormality determination threshold larger than the first abnormality determination threshold, the lock state is set. Yes. In this way, by performing step-by-step control using the two abnormality determination thresholds, the transmission ratio variable motor can continue to function as long as possible, and a sudden lock state can be avoided. . That is, the steering feeling can be improved.

  Next, the present invention will be described more specifically with reference to the drawings, taking as an example the case where the resolver abnormality detection device of the present invention is applied to a vehicle transmission ratio variable steering device.

(1) Overall Configuration of Vehicle Transmission Ratio Variable Steering Device (E-VGR Device) The overall configuration of the vehicle transmission ratio variable steering device (hereinafter referred to as “E-VGR device”) will be described with reference to FIG. To do. FIG. 1 is a perspective partial sectional view of the overall configuration of the E-VGR apparatus. As shown in FIG. 1, the E-VGR device includes, in order from the steering wheel side, a spiral cable 1, a lock device 2, a resolver 3, a transmission ratio variable motor 4, a speed reducer 5, and an electronic control unit ( Hereinafter, it is referred to as “ECU”) 6 (shown in FIG. 4). This E-VGR device is a device that makes a rotation transmission ratio (hereinafter referred to as “gear ratio”) between a steering angle of a steering wheel and a turning angle of a steered wheel (not shown) variable.

  The spiral cable 1 is a cable that enables electric power to be supplied from the ECU 6 to the variable transmission ratio motor 4, and is a cable that enables an excitation signal to be supplied from the ECU 6 to the resolver 3 and a detection signal to be output from the resolver 3 to the ECU 6. is there. The spiral cable 1 reliably transmits the transmission ratio even when the motor stator 41 of the transmission ratio variable motor 4 and the resolver stator 31 (shown in FIG. 2) of the resolver 3 are rotated by steering the steering wheel. The motor stator 41 of the variable motor 4 and the resolver stator 31 of the resolver 3 can be electrically connected.

  The lock device 2 has a mechanism for mechanically connecting a steering shaft (not shown) connected to the steering wheel and the motor rotor 42 of the transmission ratio variable motor 4. That is, the locking device 2 can switch between a locked state in which the relative rotation between the motor stator 41 and the motor rotor 42 of the transmission ratio variable motor 4 is restricted and a gear ratio is fixed, and an unlocked state in which the gear ratio can be changed. It is a device that can. Normally, the lock device 2 is in an unlocked state.

  The transmission ratio variable motor 4 is composed of an inner rotor brushless DC motor, and the gear ratio between the steering angle of the steering wheel and the turning angle of the steered wheels is variable by driving the transmission ratio variable motor 4. In the transmission ratio variable motor 4, a motor stator (stator) 41 is connected to the steering shaft side, and a motor rotor (rotor) 42 is connected to the steered wheel side. The details of the transmission ratio variable motor 4 will be described later. When the excitation signal is input, the resolver 3 outputs an amplitude modulation signal (detection signal) corresponding to the relative rotation angle of the motor rotor 42 with respect to the motor stator 41 of the transmission ratio variable motor 4. That is, a signal for detecting the relative rotation angle of the motor rotor 42 with respect to the motor stator 41 of the transmission ratio variable motor 4 is output. Details of the resolver 3 will be described later. The reducer 5 decelerates the rotation of the motor rotor 42 of the transmission ratio variable motor 4 and transmits it to the steered wheels.

  Although not shown in FIG. 1, the ECU 6 calculates the relative rotation angle of the motor rotor 42 of the transmission ratio variable motor 4 based on the detection signal of the resolver 3. Further, the transmission ratio variable motor 4 is controlled based on the steering angle of the steering wheel and the relative rotation angle of the motor rotor 42 of the transmission ratio variable motor 4. The ECU 6 detects an abnormal state of the resolver 3 based on the detection signal of the resolver 3. Further, the lock device 2 is controlled to be switched between the locked state and the unlocked state in accordance with the abnormal state of the resolver 3. Details of the ECU 6 will be described later.

(2) Detailed Configuration of Transmission Ratio Variable Motor 4 The detailed configuration of the transmission ratio variable motor 4 will be described with reference to FIG. FIG. 2 is an axial sectional view including the transmission ratio variable motor 4 and the resolver 3. As shown in FIG. 2, the transmission ratio varying motor 4 includes a motor stator 41 fixed on the inner peripheral side of the housing 7, and is disposed facing the inner peripheral side of the motor stator 41. The motor rotor 42 is configured to be relatively rotatable. The motor stator 41 has a motor stator core 411 in which silicon steel plates having a substantially cylindrical shape are stacked, and a three-phase motor winding 412 wound around the motor stator core 411. The motor winding 412 is connected to the ECU 6 via the spiral cable 1 described above. The motor rotor 42 has a rotor shaft (rotor core) 421 made of a magnetic material and a plurality of permanent magnets 422 fixed to the outer peripheral surface of the rotor shaft 421. The transmission ratio variable motor 4 configured as described above can rotate the motor rotor 42 by supplying current from the ECU 6 to the motor windings 412 of each phase.

(3) Detailed Configuration of Resolver 3 Next, the detailed configuration of the resolver 3 will be described with reference to FIGS. FIG. 2 shows an axial sectional view including the transmission ratio variable motor 4 and the resolver 3 as described above. FIG. 3 is a cross-sectional view taken along line AA in FIG. 2, that is, a radial cross-sectional view of the resolver 3. FIG. 4 shows a block diagram of the E-VGR device. As shown in FIGS. 2 and 3, the resolver 3 includes a resolver stator 31 fixed to the inner peripheral side of the housing 7 and an outer peripheral side of the rotor shaft 421 that is disposed to face the inner peripheral side of the resolver stator 31. And a fixed resolver rotor 32. That is, the resolver stator 31 is fixedly disposed on the motor stator 41, and the resolver rotor 32 is fixedly disposed on the motor rotor 42.

  The resolver stator 31 has a resolver stator core 311 and a resolver winding 312 wound around the resolver stator core 311. The resolver stator core 311 is formed by laminating silicon steel plates having a substantially cylindrical shape. Specifically, the resolver stator core 311 includes an annular yoke 311a and a magnetic pole 311b having a substantially T-shaped radial cross-sectional shape disposed at equal intervals from the yoke 311a toward the radially inner peripheral side. Is done.

  The resolver winding 312 is wound around the magnetic pole 311 b of the resolver stator core 311. As shown in FIG. 4, the resolver winding 312 includes an excitation winding 312a, a SIN detection winding 312b, and a COS detection winding 312c. The resolver winding 312 is connected to the ECU 6 via the spiral cable 1 described above. Specifically, an excitation signal composed of an alternating excitation voltage is applied from the ECU 6 to the excitation winding 312a. The SIN detection winding 312b and the COS detection winding 312c output to the ECU 6 a detection signal that is an induced voltage induced by applying an excitation voltage to the excitation winding 312a.

  The resolver rotor 32 is formed by laminating silicon steel plates having a substantially cylindrical shape. As shown in FIG. 3, the resolver rotor 32 has a substantially arc-shaped protrusion 32a formed at equal intervals outward in the radial direction, and a trough 32b formed between the protrusions 32a. It consists of. That is, the gap, which is the distance between the outer peripheral surface side of the resolver rotor 32 and the inner peripheral surface side of the magnetic pole 311 b of the resolver stator core 311, varies depending on the rotation angle of the resolver rotor 32 due to the protrusions 32 a and valley portions 32 b of the resolver rotor 32. I am doing so.

(4) Schematic description of detection signal of resolver 3 Here, the detection signal of the resolver 3 described above will be described with reference to FIGS. 5 and 6 are diagrams illustrating detection signals of the resolver 3. The detection signal of the resolver 3 shown in FIG. 5 is when the rotational speed of the motor rotor 42 is low, and the detection signal of the resolver 3 shown in FIG. 6 is when the rotational speed of the motor rotor 42 is high. Specifically, the rotational speed of the motor rotor 42 in the case of FIG. 6 is about three times the rotational speed of the motor rotor 42 in the case of FIG. Note that the detection signal output from the SIN detection winding 312b and the detection signal output from the COS detection winding 312c only differ in phase from each other, so that both detections are as shown in FIGS. Signal. 5 and 6 are detection signals of the resolver 3 when the transmission ratio variable motor 4 is rotating. 5 and 6, the absolute value of the maximum amplitude value is 1 for convenience.

  Here, before describing the case where the transmission ratio variable motor 4 is rotating, the detection signal of the resolver 3 when the transmission ratio variable motor 4 is not rotating will be described. When the transmission ratio variable motor 4 is not rotating, the relative angle of the motor rotor 42 with respect to the motor stator 41 is constant. Then, the relative angle of the resolver rotor 32 with respect to the resolver stator 31 is also constant. Further, when the protrusion 32a of the resolver rotor 32 is positioned on the inner peripheral surface side of the magnetic pole 311b of the resolver stator core 311, the gap between the magnetic pole 311b and the resolver rotor 32 is reduced, and the magnetic resistance is reduced. Therefore, in this case, when an excitation signal is input to the excitation winding 312a, the detection signals of the SIN detection winding 312b and the COS detection winding 312c have large constant amplitude waveforms. The period of the detection signal of the SIN detection winding 312b and the COS detection winding 312c is the same as the period of the excitation signal.

  On the other hand, when the transmission ratio variable motor 4 is not rotating and the valley portion 32b of the resolver rotor 32 is located on the inner peripheral surface side of the magnetic pole 311b of the resolver stator core 311, the magnetic pole 311b and the resolver rotor are located. The gap with 32 is increased, and the magnetic resistance is increased. Accordingly, when an excitation signal is input to the excitation winding 312a in this case, the detection signals of the SIN detection winding 312b and the COS detection winding 312c have small constant amplitude waveforms.

  Next, when the transmission ratio variable motor 4 is rotating, the resolver rotor 32 rotates relative to the resolver stator 31. Then, the gap between the inner peripheral surface side of the magnetic pole 311b of the resolver stator core 311 and the outer peripheral surface of the resolver rotor 32 changes with the movement of the protrusion 32a and the valley 32b of the resolver rotor 32. That is, the magnetic resistance changes. Therefore, when an excitation signal is input to the excitation winding 312a, the amplitude of the detection signal is modulated as shown in FIGS. The amplitude modulation periods Ta1 and Tb1 of the detection signal composed of the amplitude modulation signal shown in FIGS. 5 and 6 correspond to the distance from one valley portion 32b of the resolver rotor 32 to the adjacent valley portion 32b.

  Here, the amplitude modulation period Tb1 of the detection signal shown in FIG. 6 is shorter than the amplitude modulation period Ta1 of the detection signal shown in FIG. Specifically, the amplitude modulation period Tb1 of the detection signal shown in FIG. 6 is about one third of the amplitude modulation period Ta1 of the detection signal shown in FIG. Therefore, the change in the amplitude modulation slope of the detection signal shown in FIG. 6 is larger than the change in the amplitude modulation slope of the detection signal shown in FIG. This is because the change in the relative rotation angle of the resolver rotor 32 with respect to the resolver stator 31 becomes faster as the rotation speed of the transmission ratio variable motor 4 increases. The period of the detection signal in FIGS. 5 and 6 is the same as the period of the excitation signal even when the transmission ratio variable motor 4 is rotating.

(5) Detailed Configuration of ECU 6 Next, the detailed configuration of the ECU 6 will be described with reference to FIG. FIG. 4 shows a block diagram of the E-VGR device as described above. As shown in FIG. 4, the ECU 6 includes a rotation angle calculation unit (rotation angle calculation unit) 61, a control unit (control unit) 62, and a resolver abnormality detection unit (resolver abnormality detection unit, resolver abnormality detection device) 63. Composed.

(5.1) Rotation angle calculation unit 61
The rotation angle calculation unit 61 inputs detection signals from the SIN detection winding 312 b and the COS detection winding 312 c of the resolver 3 via the spiral cable 1. Based on the input detection signal, the relative rotation angle of the motor rotor 42 with respect to the motor stator 41 of the transmission ratio variable motor 4 is calculated. Since details of the calculation of the relative rotation angle are known, detailed description thereof is omitted.

(5.2) Control unit 62
The control unit 62 controls the transmission ratio variable motor 4 based on the relative rotation angle of the motor rotor 42 with respect to the motor stator 41 calculated by the steering angle and rotation angle calculation unit 61 of the steering wheel. Specifically, the gear ratio of the transmission ratio variable motor 4 is controlled to be changed as appropriate. Further, the control unit 62 performs predetermined control when the resolver abnormality detection unit 63 outputs an abnormality signal of the resolver 3. Specifically, when a resolver abnormality detection unit 63 outputs a gear ratio reduction control signal, which will be described later, the control unit 62 performs gear ratio reduction control (transmission ratio reduction) to reduce the gear ratio of the transmission ratio variable motor 4. Control). In addition, when a later-described lock control signal is output by the resolver abnormality detection unit 63, the control unit 62 performs lock control to drive the lock device 2 and switch from the unlocked state to the locked state.

  Here, the gear ratio reduction control is, for example, determining an upper limit value of the gear ratio, and when the gear ratio command value commanded by the control unit 62 exceeds the upper limit value, To do. The gear ratio reduction control may reduce the gear ratio commanded by the control unit 62 to a predetermined ratio.

(5.3) Resolver abnormality detection unit 63
The resolver abnormality detection unit 63 will be described with reference to FIGS. 5 and 6 are diagrams showing detection signals of the resolver 3 as described above. The detection signal of the resolver 3 shown in FIG. 5 is when the rotation speed of the motor rotor 42 is low (hereinafter referred to as “at the time of low speed rotation”), and the detection signal of the resolver 3 shown in FIG. Is large (hereinafter referred to as “at high speed rotation”). FIG. 7 is an enlarged view of the Ta2 section of the detection signal of FIG. FIG. 8 is an enlarged view of the Tb2 section of the detection signal of FIG. FIG. 9 is a flowchart showing the operation of the resolver abnormality detection unit 63. FIG. 10 is a diagram showing a rotational speed-abnormality determination threshold value relationship.

  As shown in FIG. 4, the resolver abnormality detection unit 63 includes a sampling value input unit 631, an offset value calculation unit 632, a rotation speed input unit 633, a rotation speed-threshold relationship storage unit 634, and a threshold value determination unit 635. The determination threshold storage unit 636 and the abnormality determination unit 637 are configured.

(5.3.1) Sampling value input unit 631
The sampling value input unit (sampling value input means) 631 includes a plurality of sampling values a1 to a4 among detection signals that are amplitude modulation signals output from the SIN detection winding 312b and the COS detection winding 312c of the resolver 3. b1 to b4 are input (step S1 in FIG. 9). The sampling values a1 to a4 and b1 to b4 will be described with reference to FIGS. Sampling values a1 to a4 and b1 to b4 are four places in one cycle of the detection signal. Here, assuming that the period of the excitation signal inputted to the excitation winding 312a of the resolver 3 is 0.2 msec, the periods Ta3 and Tb3 of the detection signals of the SIN detection winding 312b and the COS detection winding 312c of the resolver 3 Is similarly 0.2 msec. The sampling values a1 and b1 are output values at a time point of 0.025 msec from the cycle start time point. Sampling values a2 and b2 are output values at a time point of 0.075 msec from the cycle start time point. Sampling values a3 and b3 are output values at a time point of 0.125 msec from the cycle start time point. Sampling values a4 and b4 are output values at a time point of 0.175 msec from the cycle start time point.

  Here, the reason why such a sampling value is adopted is that when the detection signal of the resolver 3 is an ideal sine wave, the output value at a time point when the sum of the sampling values for each period becomes almost zero. This is because the sampling value is used. However, since the actual detection signal of the resolver 3 is an amplitude modulation signal, the sum of the sampling values does not become a zero value.

  Note that the sampling value a1 in the predetermined period Ta3 during low-speed rotation shown in FIG. 7 is 0.025, a2 is 0.045, a3 is -0.100, and a4 is -0.094. Further, the sampling value b1 in the predetermined period Tb3 during high-speed rotation shown in FIG. 8 is 0.084, b2 is 0.148, b3 is −0.326, and b4 is −0.297.

(5.3.2) Offset value calculation unit 632
The offset value calculation unit (offset value calculation means) 632 calculates the offset value Ofs based on the sampling values a1 to a4 and b1 to b4 input to the sampling value input unit 631 (step S2 in FIG. 9). The offset value Ofs is the sum of sampling values within one period. That is, the offset value Ofs at the time of low speed rotation shown in FIG. 7 is calculated by a1 + a2 + a3 + a4. Here, the offset value Ofs in the predetermined cycle Ta3 during the low-speed rotation is −0.124. Further, the offset value Ofs at the time of high-speed rotation shown in FIG. 8 is calculated by b1 + b2 + b3 + b4. Here, the offset value Ofs in the predetermined cycle Tb3 during high-speed rotation is −0.391.

  Here, the absolute value of the offset value Ofs in the predetermined period Tb3 during high-speed rotation shown in FIG. 8 is larger than the absolute value of the offset value Ofs in the predetermined period Ta3 during low-speed rotation shown in FIG. This is because the change in the amplitude modulation slope is larger during high-speed rotation. Note that the relationship in which the absolute value of the offset value Ofs during high-speed rotation is greater than the absolute value of the offset value Ofs during low-speed rotation is similar in other periods.

(5.3.3) Rotational speed input unit 633
The rotational speed input section (rotational speed input means) 633 inputs the rotational speed (hereinafter referred to as “rotational speed of the motor rotor 42”) V of the motor rotor 42 detected by the electric motor rotational speed detection section 8 with respect to the motor stator 41 (see FIG. Step S3 in FIG. In FIG. 4, the electric motor rotation speed detection unit 8 is separately arranged outside the ECU 6, but may be arranged inside the ECU 6. In this case, for example, the rotation speed of the motor rotor 42 relative to the motor stator 41 may be calculated based on the output signal of the rotation angle calculation unit 61.

(5.3.4) Rotational speed-threshold relationship storage unit 634
The rotational speed-threshold relationship storage unit (rotational speed-abnormality determination threshold relationship storage unit) 634 stores a map of rotational speed-threshold relationship (rotational speed-abnormality determination threshold relationship). As shown in FIG. 10, the rotational speed-threshold relation is a relation of the abnormality determination threshold Th of the resolver 3 with respect to the rotational speed V of the motor rotor 42 of the transmission ratio variable motor 4. Here, the threshold value Th includes a first threshold value Tha1 and Tha2 and a second threshold value Thb1 and Thb2. Specifically, the first positive threshold value Tha1 of the first threshold values is a positive value and increases as the rotational speed V of the motor rotor 42 increases. Of the first threshold values, the first negative threshold value Tha2 is a value obtained by inverting the sign of the first positive threshold value Tha1. That is, the first negative threshold value Tha2 is a negative value and decreases as the rotational speed V of the motor rotor 42 increases. That is, the absolute values of the first thresholds Tha1 and Tha2 are made larger as the rotational speed V of the motor rotor 42 increases.

  Further, the second positive threshold value Thb1 of the second threshold values is a positive value, and is a value obtained by moving the first positive threshold value Thal 1 upward substantially in parallel. That is, the second positive threshold value Thb1 is larger than the first positive threshold value Thal, and increases as the rotational speed V of the motor rotor 42 increases. Of the second threshold values, the second negative threshold value Thb2 is a value obtained by inverting the sign of the second positive threshold value Thb1. That is, the second negative threshold value Thb2 is a negative value, which is smaller than the first negative threshold value Tha2, and decreases as the rotational speed V of the motor rotor 42 increases.

(5.3.5) Threshold determining unit 635
The threshold value determination unit (abnormality determination threshold value determination unit) 635 is a map of the rotational speed V of the motor rotor 42 input by the rotational speed input unit 633 and the rotational speed-threshold relationship stored in the rotational speed-threshold relationship storage unit 634. Based on the above, the current threshold value is determined. Specifically, first, a first positive threshold value Tha1 and a first negative threshold value Tha2 corresponding to the rotational speed V of the motor rotor 42 are determined (step S4 in FIG. 9). Subsequently, the second positive threshold value Thb1 and the second negative threshold value Thb2 corresponding to the rotational speed V of the motor rotor 42 are determined (step S5 in FIG. 9). That is, as the rotational speed V of the motor rotor 42 increases, the absolute values of the determined first threshold values Thal, Tha2 and second threshold values Thb1, Thb2 increase.

(5.3.6) Determination threshold storage unit 636
The determination threshold storage unit 636 stores the first thresholds Thal and Tha2 and the second thresholds Thb1 and Thb2 according to the current rotational speed V of the motor rotor 42 determined by the threshold determination unit 635.

(5.3.7) Abnormality determination unit 637
The abnormality determination unit (abnormality determination unit) 637 is based on the offset value Ofs calculated by the offset value calculation unit 632 and the first threshold value Thal and Tha2 and the second threshold value Thb1 and Thb2 stored in the determination threshold value storage unit 636. It is determined whether or not the resolver 3 is in an abnormal state.

  Specifically, first, the offset value Ofs is determined based on a first determination condition that is larger than the first negative threshold value Tha2 and smaller than the first positive threshold value Tha1 (step S6 in FIG. 9). When the first determination condition is satisfied (step S6: Yes), the abnormality determination unit 637 determines that the resolver 3 is normal. As a result, the abnormality determination unit 637 performs processing for the next offset value Ofs without outputting anything. That is, when the first determination condition is satisfied, the process returns to step S1 in FIG. 9 and the process is repeated.

  On the other hand, when the first determination condition is not satisfied (step S6: No), the offset value Ofs is determined based on the second determination condition that is larger than the second negative threshold Thb2 and smaller than the second positive threshold Thb1 (FIG. 9 step S7). When this second determination condition is satisfied (step S7: Yes), the abnormality determination unit 637 determines that the resolver 3 is in the first stage abnormal state. As a result, the abnormality determination unit 637 outputs a gear ratio reduction control signal to the control unit 62 (step S8 in FIG. 9). Thereafter, processing for the next offset value Ofs is performed. That is, after the abnormality determination unit 637 outputs the gear ratio reduction signal, the process returns to step S1 of FIG.

  On the other hand, when the second determination condition is not satisfied (step S7: No), the abnormality determination unit 637 determines that the resolver 3 is in the second stage abnormal state. As a result, the abnormality determination unit 637 outputs a lock control signal to the control unit 62 (step S9 in FIG. 9). Thereafter, processing for the next offset value Ofs is performed. That is, after the abnormality determination unit 637 outputs the lock control signal, the process returns to step S1 in FIG.

  That is, when the offset value Ofs exceeds the first positive threshold value Tha1 and the first negative threshold value Tha2, the control unit 62 performs the gear ratio reduction control. Further, when the offset value Ofs exceeds the second positive threshold Thb1 and the second negative threshold Thb2, the control unit 62 is caused to perform lock control. Since the absolute values of the first threshold value Thal1 and Tha2 and the second threshold value Thb1 and Thb2 that are determined increase as the rotational speed V of the motor rotor 42 increases, as described above, the low speed rotation speed and the high speed rotation speed are increased. This corresponds to a change in the offset value Ofs with time. That is, it is possible to appropriately determine the abnormality of the resolver 3 according to the rotational speed V of the motor rotor 42.

(6) Others In the above-described embodiment, as shown in FIG. 10, the threshold value Th is set to have a linear relationship with the rotational speed V of the motor rotor 42. However, the present invention is not limited to this. For example, a higher-order relationship may be established. Further, the threshold value Th is a two-stage threshold value of the first threshold value Tha1, Tha2 and the second threshold value Thb1, Thb2, but it may be a single-stage threshold value or a multi-stage threshold value. Further, although the first positive threshold value Thal and the first negative threshold value Tha2, and the second positive threshold value Thb1 and the second negative threshold value Thb2 are symmetrical with each other, they may have different relationships. Further, absolute values may be used for the offset value Ofs and the threshold value Th.

It is a perspective partial sectional view of the whole composition of a transmission ratio variable steering device for vehicles. FIG. 2 is an axial sectional view including a transmission ratio variable motor 4 and a resolver 3. FIG. 3 is a cross-sectional view taken along line AA in FIG. 2, that is, a radial cross-sectional view of a resolver 3. It is a block diagram of a transmission ratio variable steering device for a vehicle. It is a figure which shows the detection signal of the resolver 3 at the time of low speed rotation. It is a figure which shows the detection signal of the resolver 3 at the time of high speed rotation. It is the figure which expanded the area of Ta2 among the detection signals of FIG. It is the figure which expanded the area of Tb2 among the detection signals of FIG. 5 is a flowchart showing the operation of a resolver abnormality detection unit 63. It is a figure which shows the rotational speed-threshold judgment threshold value relationship.

Explanation of symbols

1: Spiral cable 2: Lock device 3: Resolver 4: Transmission ratio variable motor 5: Reducer 6: Electronic control unit (ECU) 7: Housing 31: Resolver stator 32: Resolver rotor 32a: protrusion, 32b: valley, 41: motor stator, 42: motor rotor, 61: rotation angle calculation unit (rotation angle calculation means), 62: control unit (control means), 63: resolver abnormality detection unit (resolver abnormality) Detection means, resolver abnormality detection device), 311: resolver stator core, 312: resolver winding, 311a: yoke, 311b: magnetic pole, 312a: excitation winding, 312b: winding for SIN detection, 312c: winding for COS detection, 411: Motor stator core, 412: Motor winding, 421: Rotor shaft, 42 : Permanent magnet, 631: sampling value input unit (sampling value input unit), 632: offset value calculation unit (offset value calculation unit), 633: rotational speed input unit (rotational speed input unit), 634: rotational speed-threshold relationship Storage unit (rotational speed-abnormality determination threshold value relationship storage unit), 635: threshold value determination unit (abnormality determination threshold value determination unit), 636: determination threshold value storage unit, 637: abnormality determination unit (abnormality determination unit)

Claims (6)

In a resolver abnormality detecting device for detecting an abnormality of a resolver that outputs an amplitude modulation signal according to a rotation angle of a rotating body,
Sampling value input means for inputting a plurality of sampling values of the amplitude modulation signal;
An offset value calculating means for calculating an offset value that is a difference from a zero value based on the plurality of sampling values;
Rotational speed input means for inputting the rotational speed of the rotating body;
A rotational speed-abnormality determination threshold value relationship storage means for storing a rotational speed-abnormality determination threshold value relationship in which the resolver abnormality determination threshold value changes according to the rotational speed;
An abnormality determination threshold value determining means for determining the abnormality determination threshold value based on the rotation speed and the rotation speed-abnormality determination threshold value relationship;
Abnormality determination means for determining that the resolver is in an abnormal state when the offset value exceeds the abnormality determination threshold determined by the abnormality determination threshold determination means;
A resolver abnormality detection device comprising:   2. The resolver abnormality detection device according to claim 1, wherein the absolute value of the abnormality determination threshold increases as the rotation speed increases. The rotational speed-abnormality determination threshold value relationship includes a relationship between the rotational speed and a plurality of the abnormality determination threshold values,
The resolver abnormality detection device according to claim 1, wherein the abnormality determination unit determines a plurality of the abnormal states of the resolver according to a plurality of the abnormality determination thresholds.   The resolver is an assist motor of an electric power steering device that assists the steering force of the vehicle, or a vehicle transmission ratio variable steering that varies a rotation transmission ratio between a steering angle of a steering wheel and a turning angle of a steered wheel. The resolver abnormality detection device according to any one of claims 1 to 3, wherein the resolver abnormality detection device is a resolver used to detect a rotation angle of a motor for changing a transmission ratio of the device. A transmission ratio variable motor that varies the rotation transmission ratio between the steering angle of the steering wheel and the steered wheel;
A resolver that outputs an amplitude modulation signal according to a relative rotation angle of a rotor with respect to a stator of the transmission ratio variable motor;
Rotation angle calculation means for calculating a relative rotation angle of the rotor based on the amplitude modulation signal;
Resolver abnormality detecting means for detecting an abnormality of the resolver based on the amplitude modulation signal;
A locking device that locks the rotation transmission ratio by restricting relative rotation between the stator and the rotor of the transmission ratio variable motor; and
Control means for controlling the transmission ratio variable motor and the locking device based on the steering angle, the relative rotation angle and the output signal of the resolver abnormality detection means;
In a vehicle transmission ratio variable steering apparatus comprising:
The resolver abnormality detection means includes
Sampling value input means for inputting a plurality of sampling values of the amplitude modulation signal;
An offset value calculating means for calculating an offset value that is a difference from a zero value based on the plurality of sampling values;
Rotational speed input means for inputting the rotational speed of the rotor;
A rotational speed-abnormality determination threshold value relationship storage means for storing a rotational speed-abnormality determination threshold value relationship in which the resolver abnormality determination threshold value changes according to the rotational speed;
An abnormality determination threshold value determining means for determining the abnormality determination threshold value based on the rotation speed and the rotation speed-abnormality determination threshold value relationship;
An abnormality determination unit that determines that the resolver is in an abnormal state when the offset value exceeds the abnormality determination threshold value determined by the abnormality determination threshold value determination unit;
When the resolver determines that the resolver is in an abnormal state by the abnormality determination unit, the control unit reduces the rotation transmission ratio, or drives the lock device to enter the locked state. A vehicle transmission ratio variable steering apparatus characterized by performing lock control. The rotational speed-abnormality determination threshold value relationship includes a relationship between the rotational speed and the first abnormality determination threshold value and the second abnormality determination threshold value.
The control means includes
Performing the transmission ratio reduction control when the abnormality determination means determines that the offset value is a first abnormal state exceeding the first abnormality determination threshold;
6. The transmission ratio variable steering for a vehicle according to claim 5, wherein the lock control is performed when the abnormality determination means determines that the offset value is in a second abnormal state exceeding the second abnormality determination threshold value. apparatus.

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