JP2006296025A - Motor controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor controller in which an offset value depending on an assemblage error occurring between a position sensor and a motor can be specified more accurately as compared with prior art. <P>SOLUTION: The motor controller determines the actual detection value θ1 of a resolver 25 as an offset value θ2 at the time of zero-crossing of the waveform of an induced voltage E outputted from a motor 19 and stores it in an offset data storage section. The detection value is corrected by subtracting the offset value from the actual detection value of a position sensor varying serially. Since the waveform of the induced voltage E of the motor 19 zero-crosses without fail when the actual electric angle of the motor 19 is 0° regardless of the existence or magnitude of an external load being applied to the motor 19, an offset value θ2 depending on an assemblage error occurring between the resolver 25 and the motor 19 can be specified more accurately as compared with prior art. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a motor control device that controls a rotation of a motor by changing a phase current to the motor in accordance with a detection value of a position sensor.

In general, a motor control device obtains an electrical angle of a motor by a position sensor, and controls rotation of the motor by changing a phase current to the motor in accordance with the electrical angle. For this reason, in order to drive the motor efficiently, it is necessary to make the actual detection value of the position sensor correspond to the actual electrical angle of the motor as designed. Therefore, an offset value is specified in accordance with an assembly error that occurs between the position sensor and the motor, and correction is performed by subtracting the offset value from the actual detection value of the position sensor. In order to specify the offset value, in the conventional motor control device, a predetermined lock current is supplied to the motor, the rotor is locked at an electrical angle corresponding to the lock current, and the actual detection value of the position sensor at this time is obtained. It was obtained as an offset value (see, for example, Patent Document 1).
JP 2003-319680 A (paragraphs [0002] to [0007], [0010], [0029] to [0031])

  However, in the above-described conventional motor control device, the electrical angle at which the rotor is locked with respect to the same lock current varies depending on the presence / absence of the external load on the motor, so the offset value corresponding to the above assembly error can be accurately set. An unspecified situation may have occurred. Specifically, when the motor is used as a power source of the electric power steering device, the friction between the tire and the road surface becomes an external load, and the above-described situation can occur.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a motor control device capable of specifying an offset value according to an assembly error generated between a position sensor and a motor more accurately than in the past. .

  In order to achieve the above object, the motor control device according to the invention of claim 1 is such that when the actual electrical angle of the motor is 0 degrees or 180 degrees, the detection value of the position sensor connected to the motor is 0. A motor control device that corrects the actual detection value of the position sensor so as to change the phase current to the motor according to the corrected detection value and controls the rotation of the motor. An induced voltage detection unit that detects an induced voltage generated when rotating by receiving, an offset value detection unit that obtains an actual detection value of the position sensor when the waveform of the induced voltage crosses zero, and an offset value An offset data storage unit for storing, and a detection value correction unit for correcting the detection value by subtracting the offset value stored in the offset data storage unit from the actual detection value of the position sensor; Characterized in place with.

  According to a second aspect of the present invention, the motor control device according to the first aspect is characterized in that an operation switch is provided for stopping the power supply to the motor and operating the offset value detecting unit.

  According to a third aspect of the present invention, in the motor control device according to the first or second aspect, the automatic update means for automatically starting the power supply to the motor and operating the offset value detecting unit under a predetermined condition set in advance. And an abnormality notifying means for outputting a warning signal when the offset value becomes larger than a predetermined upper limit value.

  According to a fourth aspect of the present invention, in the motor control device according to any one of the first to third aspects, the motor is a power source of an electric power steering device mounted on a vehicle, and there is no gap between the motor control device and the battery. It is characterized in that the vehicle handle can be operated and the offset value detection unit is operated in a state where power supply to the motor is stopped on the condition that the state is switched from the conductive state to the conductive state.

[Invention of Claim 1]
According to the configuration of the present embodiment, the actual detection value of the position sensor when the waveform of the induced voltage output from the motor crosses zero is obtained as the offset value, and this is stored in the offset data storage unit. Then, the detected value is corrected by subtracting the offset value from the actual detected value of the position sensor that changes sequentially. Here, the waveform of the induced voltage of the motor always crosses zero when the actual electrical angle of the motor is 0 degree or 180 degrees regardless of the presence / absence of the external load applied to the motor. The offset value corresponding to the assembly error generated between the position sensor and the motor can be specified more accurately than in the past.

[Invention of claim 2]
According to the configuration of the second aspect, the offset value can be updated at any time by manual operation of the operation switch.

[Invention of claim 3]
According to the configuration of the third aspect, the offset value is automatically updated under a predetermined condition. When the offset value becomes larger than a predetermined upper limit value, a warning signal is output, so that it is possible to quickly cope with an abnormality.

[Invention of claim 4]
When replacing the electric power steering device mounted on the vehicle, the motor control device and the battery are disconnected, and when the electric power steering device is newly installed, the motor control device and the battery are connected. Is done. According to the configuration of claim 4, the steering wheel of the vehicle can be operated in a state in which the power supply to the motor is stopped on condition that the motor control device and the battery are switched from the non-conductive state to the conductive state. become. Therefore, when the handle is manually operated, this becomes an external torque, and the motor rotates to generate an induced voltage. At this time, since the offset value detection unit is operating, the detection value by the position sensor when the waveform of the induced voltage crosses zero is specified as the offset value.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
Reference numeral 11 in FIG. 1 denotes an electric power steering device, which includes a linear motion shaft 16 penetrating inside a cylindrical housing 18. The cylindrical housing 18 is fixed to the main body of the vehicle 10, and a motor 19 is built in an intermediate portion in the axial direction thereof. The motor 19 is a brushless motor, and a stator 20 is fitted and fixed inside the cylindrical housing 18, and a cylindrical rotor 21 is provided inside the stator 20. The linear motion shaft 16 penetrates through the rotor 21 and both ends are exposed from the cylindrical housing 18, and both ends are connected to the steered wheels 50 and 50 via tie rods 17 and 17.

  A ball screw nut 22 is assembled on the inner surface of the rotor 21. Further, a ball screw portion 23 is formed in an intermediate portion of the linear motion shaft 16 in the axial direction. Then, the ball screw mechanism 24 is constituted by the ball screw nut 22 and the ball screw portion 23, and when the ball screw nut 22 rotates together with the rotor 21, the ball screw portion 23 moves directly with respect to the cylindrical housing 18, thereby turning the steered wheels 50, 50 turns. A vehicle speed sensor 36 for detecting the vehicle speed based on the rotation of the steered wheels 50 is provided in the vicinity of the steered wheels 50.

  A rack 30 is formed near the one end of the linear motion shaft 16, and a pinion 31 provided at the lower end portion of the steering shaft 32 is engaged with the rack 30. A steering wheel 33 is attached to the upper end portion of the steering shaft 32, and a steering angle sensor 34 and a torque sensor 35 are attached to the steering shaft 32 at a position closer to the upper end.

  A winding provided in the stator 20 of the motor 19 is connected to a motor drive circuit 42. Specifically, the winding is composed of a U phase, a V phase, and a W phase, and each terminal of the U phase winding, the V phase winding, and the W phase winding is provided with a motor drive circuit 42 (not shown). It is connected to the. The motor drive circuit 42 performs PWM control so that the phase current Iu flows in the U-phase winding, the phase current Iv flows in the V-phase winding, and the phase current Iw flows in the W-phase winding so that the following relational expression is satisfied. Shed. In the following formula, “Ie” is a predetermined constant, and “ωt” is the electrical angle of the motor 19.

Iu = Ie · sin (ωt) (1)
Iv = Ie · sin (ωt−2π / 3) (2)
Iw = Ie · sin (ωt−4π / 3) (3)

  A resolver 25 (corresponding to a “position sensor” according to the present invention) for detecting the rotational position of the rotor 21 is provided at a position near one end of the cylindrical housing 18. The resolver 25 includes a movable part (not shown) that rotates integrally with the rotor 21 and a fixed part (not shown) fixed to the cylindrical housing 18. When the movable coil of the resolver 25 rotates together with the rotor 21, the mutual inductance between the fixed portion and the movable portion in the resolver 25 changes. Then, the resolver signal processing circuit 25C connected to the resolver 25 converts the electrical angle of the resolver 25 into an electrical signal based on the change in mutual inductance, and outputs the electrical signal to the steering control device 41 described later. This output becomes the detection value (hereinafter referred to as “detection value θ1”) of the resolver 25 according to the present invention.

  Here, if the number of poles of the resolver 25 is k, the resolver 25 rotates k times by an electrical angle when it makes one mechanical angle. In other words, the electrical angle of the resolver 25 changes from 0 to 360 degrees while the mechanical angle changes from 0 to 360 / k [degrees]. Therefore, as shown in FIG. 2A, when the relationship between the mechanical angle of the resolver 25 and the electrical angle (detected value θ1) of the resolver 25 is graphed, the graph has a mechanical angle of 360 / k [degrees]. Each time it changes, a triangular wave appears repeatedly. Note that, similarly to the general case, in this embodiment, the number of poles of the resolver 25 and the number of poles of the motor 19 are the same value.

  In FIG. 1, reference numeral 41 denotes a steering control device, which corresponds to a “motor control device” according to the present invention. Various programs such as an assist control program and an offset value update program PG1 (corresponding to the “offset value detection unit” according to the present invention) are stored in the ROM 41R provided in the steering control device 41. Further, the steering control device 41 is provided with a flash memory 41F (corresponding to the “offset data storage unit” according to the present invention) for storing the offset value θ2.

  The steering control device 41 is provided with an induced voltage detector 51 according to the present invention. Then, the induced voltage E generated in the motor 19 is detected by the induced voltage detector 51 when the handle 33 is operated in a state where the power supply to the motor 19 is stopped.

  By the way, the resolver 25 and the motor 19 have the same number of poles, and in terms of design, the detected value θ1 (that is, electrical angle) of the resolver 25 and the electrical angle ωt of the motor 19 (that is, U of the three-phase windings). The phase winding phase). Therefore, by design, at the point where zero crossing occurs in the process in which the waveform of the induced voltage E of the U-phase winding changes from negative to positive value (hereinafter simply referred to as “zero crossing point”), the detection value θ1 of the resolver 25 is designed. It becomes “0” above. However, in actuality, due to the assembly error of the motor 19 and the resolver 25, the actual resolution of the resolver 25 at the zero crossing point of the waveform of the induced voltage E is shown as shown in FIG. 2 (A) and FIG. 2 (C). The detected value θ1 does not become “0” but becomes the offset value θ2. Therefore, the steering control device 41 of the present embodiment executes the offset value update program PG1 to detect the offset value θ2 from the induced voltage E of the U-phase winding and the detected value θ1 of the resolver 25.

  Hereinafter, each program memorize | stored in ROM41R of the steering control apparatus 41 is demonstrated with the effect of this embodiment. When the operation switch 52 (see FIG. 1) provided in the driver's seat is turned on, the steering control device 41 stops the power supply from the motor drive circuit 42 to the motor 19. Then, the offset value update program PG1 is executed. When the offset value update program PG1 is executed, the counter i is initialized to “1” as shown in FIG. 3 (S10). Next, it is determined whether the induced voltage E has changed from a negative value to a positive value and zero-crossed (S11). When the induced voltage E changes from a negative value to a positive value and zero crosses (S11: YES), the actual detection value θ1 of the resolver 25 at that zero cross point is stored in R (i) (S12). .

  Next, the counter i is incremented (S13), and this operation is repeated until the counter i becomes larger than the constant N (loop of S11 to S14). Then, an average value Rav of a plurality of R (i) is obtained (S15), and the value of the offset value θ2 stored in the flash memory 41F is updated to the value of the average value Rav (S16).

  Thus, the offset value update program PG1 ends. Then, the motor drive circuit 42 returns to a state where power can be supplied to the motor 19.

  In a state where the operation switch 52 is not turned on (that is, in a normal state), the steering control device 41 executes an assist control program and is not shown based on detection results of the steering angle sensor 34, the torque sensor 35, and the vehicle speed sensor 36. The assist force to be output to the electric power steering apparatus 11 is determined with reference to the map. Further, in order to output the assist force to the electric power steering device 11, the steering control device 41 controls on / off of an FET (not shown) provided in the motor drive circuit 42, and flows it from the motor drive circuit 42 to the electric power steering device 11. Change the phase current. Specifically, when the assist force is determined by executing the assist control program, the steering control device 41 acquires the detection value θ1 of the resolver 25. Here, when θ1> θ2, correction is performed by subtracting the offset value θ2 from the detected value θ1 as in the following equation (4) to obtain the detected value θn. Further, when θ1 <θ2, as shown in the following equation (5), correction is performed by subtracting the offset value θ2 from the detection value θ1 and adding a value for one period (360 degrees) to obtain the detection value θn. Therefore, as shown in comparison with FIG. 2B and FIG. 2C, the corrected detected value θn becomes “0” when the waveform of the induced voltage E of the U-phase winding reaches the zero cross point. .

θn = θ1-θ2 (4)
θn = 360 + (θ1-θ2) (5)

  The detected value θn after correction is used as the electrical angle ωt of the motor 19, and phase currents Iu, Iv, Iw (see equations (1) to (3)) corresponding to the electrical angle ωt are passed through the motor 19. As a result, the motor 19 is driven and the assist power is output from the electric power steering apparatus 11.

  Thus, in the configuration of the present embodiment, the actual detection value θ1 of the resolver 25 when the waveform of the induced voltage E output from the motor 19 crosses zero is obtained as the offset value θ2. Here, the waveform of the induced voltage E of the motor 19 always crosses zero when the actual electrical angle of the motor 19 is 0 degree regardless of the presence / absence of the external load applied to the motor 19. The offset value θ2 corresponding to the assembly error occurring between the two can be specified more accurately than in the past. The offset value θ2 thus accurately obtained is updated and stored in the flash memory 41F, and the steering control device 41 corrects the offset value θ2 by subtracting it from the actual detection value θ1 of the resolver 25 that changes sequentially. Since the rotation of the motor 19 is controlled by the detection value θn after the correction is performed by the (detection value correction unit), the motor can be driven to rotate more efficiently than in the past.

[Second Embodiment]
This embodiment is not shown, and only the control configuration is different from the first embodiment. Hereinafter, only the configuration different from that of the first embodiment will be described, and the same configuration is denoted by the same reference numeral, and redundant description is omitted. The steering control device 41 according to the present embodiment acquires a travel distance from another control device provided in the vehicle 10 and measures the travel distance every time a predetermined distance is traveled or by a timer provided in the vehicle 10. When the motor 19 no longer needs assistance every time a certain time elapses or when the vehicle speed exceeds 100 km / h, the power supply to the motor 19 is automatically stopped and offset The value update program PG1 is executed. When the offset value θ2 obtained by the offset value update program PG1 becomes larger than a predetermined upper limit value, a warning signal is output. With this configuration, the offset value θ2 is automatically updated and abnormality can be checked at the same time, and a quick response to the abnormality becomes possible.

[Third Embodiment]
In the present embodiment, the steering control device 41 and the battery are switched from the non-conductive state to the conductive state, or the electric power steering device 11 and the steering control device 41 are switched from the non-conductive state to the conductive state. On this condition, the steering control device 41 is configured to automatically execute the offset value update program PG1. Thus, when the steering control device 41 or the electric power steering device 11 is replaced, the offset value θ2 is automatically updated to an accurate value corresponding to the motor 10 built in the electric power steering device 11.

  In the case of the configuration of the present embodiment, in the maintenance manual of the vehicle, “if either the electric power steering device 11 or the steering control device 41 is replaced, the handle 33 is set to update the offset value θ2. “Please rotate left and right” is preferable.

[Other Embodiments]
The present invention is not limited to the above-described embodiment. For example, the embodiments described below are also included in the technical scope of the present invention, and various other than the following can be made without departing from the scope of the invention. It can be changed and implemented.
(1) In the first embodiment, the example in which the present invention is applied to the motor control device for driving the motor 19 as the power source of the electric power steering device 11 of the vehicle 10 has been described. The present invention is not limited, and the present invention may be applied to a motor control device for driving a motor as a drive source for a machine tool, a robot, or the like.

(2) In the first embodiment, the configuration is such that the detection value of the position sensor is 0 when the actual electrical angle of the motor is 0 degrees, but the actual motor configuration is designed. The present invention may be applied to a configuration in which the detection value of the position sensor is 0 when the electrical angle is 180 degrees.

(3) In the first embodiment, the offset value θ2 is detected a plurality of times and the average value thereof is obtained. However, the offset value θ2 may be detected only once.

(4) When the operation switch 52 described in the first embodiment is turned on, a voice guidance to the effect that “turn the handle 33 to the left and right to update the offset value” is played. preferable.

The conceptual diagram of the vehicle which concerns on 1st Embodiment of this invention. (A) Relationship graph between resolver mechanical angle and detected resolver value (B) Relationship graph between resolver mechanical angle and corrected resolver detected value (C) Relationship graph between motor mechanical angle and induced voltage Offset value update program flowchart

Explanation of symbols

11 Electric Power Steering Device 19 Motor 25 Resolver (Position Sensor)
41 Steering control device (motor control device)
42 Motor Drive Circuit 51 Induced Voltage Detection Unit 52 Operation Switch E Induced Voltage Iu, Iv, Iw Phase Current θ1 Detected Value θ2 Offset Value θn Detected Value ωt Electrical Angle

Claims (4)

When the actual electrical angle of the motor is 0 degree or 180 degrees, the actual detection value of the position sensor is corrected so that the detection value of the position sensor connected to the motor becomes 0, and the corrected detection A motor control device for controlling rotation of the motor by changing a phase current to the motor according to a value;
An induced voltage detector that detects an induced voltage generated when the motor is rotated by receiving external torque;
An offset value detection unit for obtaining an actual detection value of the position sensor as an offset value when the waveform of the induced voltage crosses zero;
An offset data storage unit for storing the offset value;
A motor control device comprising: a detection value correction unit that corrects the detection value by subtracting the offset value stored in the offset data storage unit from an actual detection value of the position sensor.   The motor control device according to claim 1, further comprising an operation switch for stopping power feeding to the motor and operating the offset value detection unit. Update automatic starting means for automatically stopping power supply to the motor under a predetermined condition and operating the offset value detection unit;
3. The motor control device according to claim 1, further comprising an abnormality notifying unit that outputs a warning signal when the offset value becomes larger than a predetermined upper limit value. 4. The motor is a power source of an electric power steering device mounted on a vehicle, and power supply to the motor is stopped on condition that the motor control device and the battery are switched from a non-conductive state to a conductive state. 4. The motor control device according to claim 1, wherein the motor control device is configured such that the steering wheel of the vehicle can be operated and the offset value detection unit is operated in a state in which the vehicle is operated.

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