JP2010112899A - Abnormality detection method for resolver, and control system using the method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology capable of heightening availability of a system by not only detecting an abnormality of a resolver but also determining whether an influence thereof exerted on the system is serious or not. <P>SOLUTION: In order to attain the object, following means are taken. (1) The amplitude of a signal from the resolver is monitored, and monitored whether or not the value of sinθ<SP>2</SP>+cosθ<SP>2</SP>is deviated from 1. (2) When the value of sinθ<SP>2</SP>+cosθ<SP>2</SP>is deviated from 1 in step (1), sinθ, cosθ are plotted respectively as coordinates (sinθ, cosθ) on an orthogonal coordinates, and in the case where each plot of the coordinates (sinθ, cosθ) exists in all the four quadrants within a prescribed time, it is determined to be normal, and in the other cases, it is determined to be abnormal and driving of a motor is prohibited. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a resolver / digital converter, and more particularly to a resolver / digital converter having a failure detection function or a failure detection function of a resolver / digital converter.

  In the servo control system, a rotation angle sensor is necessary to detect the rotation angle and perform feedback control. Further, in brushless motor control, since it is necessary to energize the motor coil in accordance with the rotation angle of the motor, a rotation angle sensor is required in addition to the servo control system. Conventionally, resolvers have been widely used as rotation angle sensors because of their robustness and environmental resistance resulting from their simple structure.

  In addition, a servo control system applied to electric power steering, x-by-wire, particularly steer-by-wire, fly-by-wire, etc. requires safety and reliability, and therefore requires a failure detection function.

Document 1: According to Japanese Patent Laid-Open No. 9-280890, a resolver failure is detected by utilizing the property of a trigonometric function that is an output of a resolver of sin θ ² + cos θ ² = 1. Further, according to Document 2: Japanese Patent Application Laid-Open No. 2005-308634, the calculation is simplified with the determination area as a regular polygon.

JP-A-9-280890 JP 2005-308634 A

According to the above prior art, when the signal from the resolver or to the resolver is broken, the signal from the resolver becomes abnormal and the relationship between sinθ and cosθ is not established, and the value of sinθ ² + cosθ ² deviates from 1. Can be detected and notified to the microcomputer.

  In the conventional technology described above, further consideration is desirable not only in detecting an abnormality, but also in determining whether or not the influence of the abnormality on actual system operation is important. The determination of whether or not a failure has a significant effect on the operation of the system is important in increasing the availability of the system without securing the safety and immediately shutting down the system. In particular, in an electric power steering applied to an automobile having a large vehicle weight, it is desirable from the viewpoint of ensuring safety that the assist by the motor is continued unless a dangerous event occurs due to a control abnormality.

  Therefore, an object of the present invention is to provide a technique for increasing the availability of a system by determining whether or not the influence on the system is serious, not just detecting the abnormality of the resolver.

  In order to achieve the above object, the present invention includes a motor and a resolver coupled to the motor via a rotating shaft, and the resolver is proportional to the sine and cosine of the rotating angle at the electrical angle of the rotating shaft. A resolver abnormality detection method used in a control system that inputs a resolver sine amplitude signal and a resolver cosine amplitude signal when the resolver sine amplitude signal amplitude and the resolver cosine amplitude signal amplitude have a first relationship And, when plotted on orthogonal coordinates with the amplitude of the resolver sine amplitude signal and the amplitude of the resolver cosine amplitude signal as axes, prohibiting motor drive when there is a quadrant that does not exist for a certain period of time. Features.

  As described above, according to the present invention, it is possible to distinguish between a resolver failure that does not affect the safety of system operation and a resolver failure that affects the safety of system operation. In the case of a resolver failure that does not affect the safety of the operation, the operation can be continued and the availability of the system can be increased while ensuring the safety.

The best mode of the present invention will be described below together with the principle of the present invention.
(1) Monitor the amplitude of the signal from the resolver, and monitor whether the value of sin θ ² + cos θ ² deviates from 1.
(2) When the value of sinθ ² + cosθ ² is different from 1 in (1), sinθ and cosθ are plotted on the orthogonal coordinates and the coordinates (sinθ, cosθ) are plotted, and 4 within a predetermined time. If there is a plot of coordinates (sinθ, cosθ) in all four quadrants, it is considered normal, otherwise it is regarded as abnormal and motor drive is prohibited.

  The influence on the system caused by the abnormality of the resolver is torque fluctuation due to the magnetic pole position detection error of the motor. The relationship between the magnetic pole position detection error and the torque fluctuation is expressed by the following equation.

τm = K ・ iq ・ cosθe
However, τm: Motor output torque K: Torque constant iq: q-axis current θe: Magnetic pole position detection error From this equation, if it is within the range of | θe | <± 90 °, torque fluctuation occurs due to the magnetic pole position detection error. It can be seen that the performance and operability are only deteriorated. Further, when | θe |> ± 90 °, the value of cosθe becomes negative and the signs of iq and τm are reversed, so that it can be seen that the motor rotates in the direction opposite to the direction in which the motor is to be rotated. When such a state occurs in the feedback control system, the polarity of the feedback is reversed, so that the negative feedback becomes positive feedback and the control system diverges. When such a state occurs in, for example, an electric power steering apparatus, a phenomenon such as self-steering that turns the steering without permission occurs. Such a phenomenon must be avoided.

  When the resolver is normal, the plot of the coordinates (sinθ, cosθ) on the sinθ, cosθ orthogonal coordinates, that is, the Lissajous locus draws a unit circle centered on the origin O as shown in the locus A in FIG. In such a case, it is known that the unit circle deviates like the locus B and the locus C. As a result of the failure analysis of the resolver, the origin O is included in the Lissajous locus when | θe | <± 90 °, and the origin O is not included in the Lissajous locus when | θe |> ± 90 °. all right.

  Here, including the origin O within the Lissajous locus means that the Lissajous locus passes through all four quadrants, and not including the origin O within the Lissajous locus means that the Lissajous locus is one of the four quadrants. It will not pass through the quadrant.

  Therefore, when the coordinates (sinθ, cosθ) are plotted on the sinθ, cosθ orthogonal coordinates and the plots of the coordinates (sinθ, cosθ) exist in all four quadrants within a predetermined time, it is normal. Can be considered abnormal. However, in the case of electric power steering, θ may be almost constant when going straight, and the plot of coordinates (sinθ, cosθ) may not pass through all four quadrants within a predetermined time. It should be determined in combination with another diagnosis, for example, the diagnosis of (1) above.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a basic embodiment of the present invention. When the excitation signal f (t) from the excitation signal generator 2 is applied to the primary winding, the resolver 1 receives the signal f (t) according to the rotation angle θ of the rotary shaft 7 attached to the resolver 1 and the motor 5. sinθ, f (t) cosθ is induced in the secondary winding. The excitation signal generator 2, the motor 5, and the rotary shaft 7 are not shown in FIG. 1, but are shown in FIGS. The signals f (t) sinθ and f (t) cosθ induced in the secondary winding of the resolver 1 are converted into digital signals by the A / D converter 11 and input to the error detection function 12. The error detection function 12 executes a Lissajous locus amplitude determination 121 and a Lissajous locus quadrant determination 122 together with other diagnoses 129. When the Lissajous locus amplitude determination 121 determines that the detection range is 1 and the Lissajous locus quadrant determination 122 determines that the abnormality is detected, it is determined that motor driving is prohibited. Further, when it is determined that there is an abnormality in the other diagnosis 129, it is determined that the motor drive is prohibited.

  In addition, it is desirable that the error detection function 12 is realized by software in the microcomputer 10 and that the A / D converter 11 includes the microcomputer 10 because the amount of hardware can be reduced.

  According to this embodiment described above, it is possible to distinguish between a resolver failure that does not affect the safety of the system operation and a resolver failure that affects the safety of the system operation. In the case of a resolver failure that does not affect the safety of the system, the operation can be continued and the availability of the system can be increased while ensuring the safety. In the case of a resolver failure that does not affect the safety of system operation, it is possible to turn on a warning lamp or limit the motor drive output.

  FIG. 2 shows an example of the Lissajous locus amplitude determination 121.

  When the coordinates (sin θ, cos θ) are plotted on the sin θ, cos θ orthogonal coordinates from the signals f (t) sin θ, f (t) cos θ, and the plot is in the detection area 1, it is regarded as abnormal.

  Note that the detection area 1 is a unit circle in this embodiment, for example, a unit circle if normalized with the amplitude of f (t). In this embodiment, the circle has a radius r0 including the amplitude of f (t). It is set with a certain width inside and outside. This constant width may be determined in consideration of individual differences of resolvers and electronic circuits, temperature characteristics, and deterioration over time. In FIG. 2, the center value of the radius in the normal state is r0, the upper limit is r1, and the lower limit is r2.

  FIG. 3 shows the detection principle of the Lissajous locus quadrant determination 122. When the resolver is normal, the plot of the coordinates (sinθ, cosθ) on the sin θ, cos θ orthogonal coordinates, that is, the Lissajous locus draws a unit circle like the locus A in FIG. 3, and when the resolver fails, the locus B, It is known that it deviates from the unit circle like the locus C. As a result of the failure analysis of the resolver, the origin O is included in the Lissajous locus when | θe | <± 90 °, and the origin O is not included in the Lissajous locus when | θe |> ± 90 °. know.

  FIG. 4 shows an example of the Lissajous locus quadrant determination 122. If all four quadrants pass within a predetermined time such as the trajectories A and B, it is considered normal, and if only two quadrants pass like the trajectory 2, it is considered abnormal.

  In addition, whether it exists in each quadrant can be judged from the positive / negative of sin (theta) and cos (theta) as follows.

Quadrant 1: sinθ> 0, cosθ> 0
Second quadrant: sinθ> 0, cosθ <0
Third quadrant: sinθ <0, cosθ <0
Quadrant 4: sinθ <0, cosθ> 0

  The determination of whether all four quadrants have been passed within a predetermined time is, for example, memorized the time when each testimony is passed, and whether or not the difference from the current time is within a predetermined time. Judgment can be made.

  FIG. 5 shows an embodiment in which the detection area of the Lissajous locus quadrant determination 122 is a square. According to the present embodiment, an abnormality can be detected only by determining whether or not the absolute values of sinθ and cosθ are within a predetermined range, so that the amount of calculation can be reduced as compared with the case where the detection area is a circle. Can do. In this case, it can be determined by the following logical expression.

| Sinθ |> b and | cosθ |> b,
And (| sinθ | <a or |cosθ|>><a)
Then normal,
Otherwise, it is abnormal.

  Similarly, the detection area can be a regular polygon.

  6 and 7 show an embodiment in which the detection range of the Lissajous trajectory amplitude determination 121 is divided into two stages, a detection area 1 and a detection area 2. FIG. In FIG. 6, when the detection range 2 is determined in the Lissajous locus amplitude determination 121, the motor drive is prohibited regardless of the result of the Lissajous locus quadrant determination 122. However, if it is determined to be abnormal, motor drive is prohibited.

  As shown in FIG. 7, the detection area 2 is set to an area having an amplitude smaller than that of the detection area 1 (within a circle having a radius r3), and the amplitude of the signal from the resolver is reduced, and the S / N is reduced. When θe |> ± 90 °, prohibition of motor drive is prohibited.

  The method of making the detection area in two steps as in the present embodiment can be similarly applied to a square or regular polygon.

  FIG. 8 shows an embodiment in which the present invention is applied to a motor control system.

  The microcomputer 10 controls the motor driver 4, and the motor driver 4 drives the motor 5. A rotating shaft 7 of the motor 5 is connected to the resolver 1 and the controlled object 6. The resolver 1 detects the rotation angle (magnetic pole position) of the motor 5 via the rotating shaft 7, and the microcomputer 10 drives and controls the motor 5 by the motor driver 4 based on the result. Further, the motor 5 controls the control object 6 via the rotating shaft 7.

  When the motor detection prohibition is stopped by the error detection function 12, the control system stops the driving of the motor 5. In this case, there are several methods for stopping the driving of the motor 5, but a method of cutting off the control signal to the motor driver 4, a method of stopping the power supply to the motor driver 4, and an output from the motor driver 4 to the motor 5 There is a way to shut off.

  FIG. 9 shows an embodiment in which the present invention is applied to an electric power steering.

  The control target 6 is mechanically connected to a wheel steering mechanism via a reduction gear, a column shaft, a pinion, and a rack, and the column shaft is mechanically connected to a steering wheel 8 and a torque sensor 9. An operation input from the driver via the steering wheel 8 is detected by a torque sensor 9, a detection signal of the torque sensor 9 is input to the microcomputer 10, and the microcomputer 10 detects the driver's operation torque detected by the torque sensor 9 ( The driver's steering is assisted by controlling the output torque of the motor 5 in accordance with the steering force.

1 shows a basic embodiment of the present invention. The embodiment which is an embodiment of the Lissajous locus amplitude determination 121. Detection principle of Lissajous locus quadrant determination 122. An example of Lissajous locus quadrant determination 122. The embodiment which made the detection area of the Lissajous locus quadrant determination 122 square. The embodiment which made the detection range of the Lissajous locus amplitude determination 121 into two stages. The embodiment which made the detection range of the Lissajous locus amplitude determination 121 into two stages. An example of a motor control system. An example of electric power steering.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Resolver 2 Excitation signal production | generation part 3 Conversion trigger production | generation part 4 Motor driver 5 Motor 6 Control object 7 Rotating shaft 8 Steering wheel 9 Torque sensor 10 Microcomputer 11 A / D converter 12 Error detection function 121 Lissajous locus amplitude determination 122 Lissajous locus quadrant Judgment 123 AND (logical product)
124 OR (logical sum)

Claims (12)

A resolver sine amplitude signal and a resolver cosine amplitude signal from the resolver proportional to the sine and cosine of the rotation angle at the electrical angle of the rotation shaft. A resolver abnormality detection method used in an input control system,
When the amplitude of the resolver sine amplitude signal and the amplitude of the resolver cosine amplitude signal are in a first relationship, and plotted on orthogonal coordinates with the amplitude of the resolver sine amplitude signal and the amplitude of the resolver cosine amplitude signal as axes When
A resolver abnormality detection method characterized by prohibiting motor drive when there is a quadrant that does not exist for a certain period of time. The resolver abnormality detection method according to claim 1,
The first relationship is that the sum of the square of the amplitude of the resolver sine amplitude signal and the square of the amplitude of the resolver cosine amplitude signal deviates from a first predetermined range. Resolver abnormality detection method. The resolver abnormality detection method according to claim 1,
The first relationship is
Either the absolute value of the amplitude of the resolver sine amplitude signal or the absolute value of the amplitude of the resolver cosine amplitude signal is greater than a first predetermined value,
Alternatively, both the absolute value of the amplitude of the resolver sine amplitude signal and the absolute value of the amplitude of the resolver cosine amplitude signal are smaller than a second predetermined value,
The resolver abnormality detection method characterized by the above-mentioned. The resolver abnormality detection method according to claim 1,
When the first relationship is plotted on an orthogonal coordinate with the amplitude of the resolver sine amplitude signal and the amplitude of the resolver cosine amplitude signal as axes, the first relationship is greater than the circumference of a predetermined diameter centered on the origin O. A resolver abnormality detection method characterized by having a distance equal to or greater than a predetermined third predetermined value. The resolver abnormality detection method according to claim 1,
When the first relationship is plotted on an orthogonal coordinate with the amplitude of the resolver sine amplitude signal and the amplitude of the resolver cosine amplitude signal as axes, the sides of a regular polygon of a predetermined size having the origin O as the center of gravity A resolver abnormality detection method characterized by having a distance equal to or greater than a predetermined fourth predetermined value. The resolver abnormality detection method according to claim 1,
A resolver abnormality detection method, wherein motor drive is prohibited when the amplitude of the resolver sine amplitude signal and the amplitude of the resolver cosine amplitude signal are in a second relationship. The resolver abnormality detection method according to claim 6,
The second relationship is that the sum of the square of the amplitude of the resolver sine amplitude signal and the square of the amplitude of the resolver cosine amplitude signal deviates from a second predetermined range. Resolver abnormality detection method. The resolver abnormality detection method according to claim 6,
The second relationship is that both the absolute value of the amplitude of the resolver sine amplitude signal and the absolute value of the amplitude of the resolver cosine amplitude signal deviate from a second predetermined range. Resolver abnormality detection method. The resolver abnormality detection method according to claim 6,
When the second relationship is plotted on an orthogonal coordinate with the amplitude of the resolver sine amplitude signal and the amplitude of the resolver cosine amplitude signal as axes, the circumference of a predetermined diameter centered on the origin O is preliminarily determined. A resolver abnormality detection method characterized by having a distance equal to or greater than a predetermined fifth predetermined value. The resolver abnormality detection method according to claim 6,
When the second relationship is plotted on an orthogonal coordinate with the amplitude of the resolver sine amplitude signal and the amplitude of the resolver cosine amplitude signal as axes, an edge of a regular polygon of a predetermined size having the origin O as the center of gravity A resolver abnormality detection method characterized by having a distance greater than or equal to a predetermined sixth predetermined value. A motor and a resolver coupled to the motor via a rotating shaft;
A motor drive circuit for driving the motor;
A motor control circuit for controlling the motor drive circuit by a signal from a resolver,
A motor control device using the resolver abnormality detection method according to claim 1. A motor and a resolver coupled to the motor via a rotating shaft;
A motor drive circuit for driving the motor;
A reduction gear, a column shaft, a pinion, a rack, and a steering mechanism for a wheel mechanically coupled via them,
A steering wheel mechanically coupled via the column shaft, a torque sensor,
A drive control circuit unit for driving and controlling the motor by a signal from the resolver and a signal from the torque sensor;
An electric power steering using the resolver abnormality detection method according to claim 1.

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