JP2019193532A - Motor system, motor control device, and motor rotation speed detection method - Google Patents

Abstract

To reduce speed ripple when the rotation speed of a motor is detected in a motor control device that targets a motor whose rotation angle is detected by a rotation angle sensor and is controlled by vector control.SOLUTION: A table creation unit TBLG uses a trigger when the rotation angle θ from a rotation angle sensor reaches each of a plurality of reference rotation angles θ [r] in the preparatory stage before the actual use in a state where the motor is normally rotated, and a correction table CTBL for determining a correction value is created by calculating an axis error Δθ between the dq axis and the γδ axis by using a motor voltage equation. In the actual use stage, a correction value calculation unit CCAL determines a correction value (speed correction value Δω) corresponding to the rotation angle θ on the basis of the correction table CTBL by receiving the rotation angle θ. The rotational speed before correction of the motor is corrected by the correction value.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a motor system, a motor control device, and a motor rotation speed detection method, and, for example, relates to a motor rotation speed detection technique using a rotation angle sensor.

  Patent Document 1 estimates an error angle of a phase angle from a rotation detection unit added to a motor by performing an operation of an extended induced voltage equation using a disturbance observer in a motor control device. A method of correcting the phase angle with an error angle is shown. Non-Patent Document 1 describes a model of an extended dielectric voltage equation regarding a disturbance observer used when position / speed sensorless control of an embedded magnet synchronous motor (IPMSM) is performed.

JP 2014-158336 A

Morimoto and 2 others, “IPMSM position / velocity sensorless control using estimated position error information”, Electron Theory D, Vol. 122, no. 7, 2002, p. 722-729

  As a motor control method, as shown in Patent Document 1 and the like, a rotation angle sensor such as a resolver is used to detect the rotation angle and rotation speed of the motor, and vector control is performed based on the detected rotation angle and rotation speed. A method of performing is known. On the other hand, the rotation angle from the rotation angle sensor may include an angle error. Such an angle error causes a speed ripple of the rotational speed. Therefore, as shown in Patent Document 1, a method of correcting the rotation angle from the rotation angle sensor by estimating the angle error using a disturbance observer can be considered.

  However, in the method using such a disturbance observer, when a motor with a large number of pole pairs is to be controlled, the estimation accuracy of the angle error is lowered due to the problem of responsiveness, and the speed ripple may not be sufficiently reduced. . When speed ripple occurs, it may be difficult to improve accuracy and responsiveness in motor speed control.

  Embodiments to be described later have been made in view of the above, and other problems and novel features will become apparent from the description of the present specification and the accompanying drawings.

  A motor control device according to an embodiment executes first and second processing for a motor whose rotation angle is detected by a rotation angle sensor and controlled by vector control. As a first process, the motor control device, in a preparatory stage before actual use, in a state in which the motor is normally rotated, the rotation angle from the rotation angle sensor is set to each of a plurality of reference rotation angles different at predetermined angular intervals. Using the arrival time as a trigger, the motor voltage equation is used to calculate the axis error between the dq axis of the motor and the γδ axis based on the detection result of the rotation angle sensor. Then, the motor control device creates a correction table for determining correction values for each of the plurality of reference rotation angles based on the calculation result. As a second process, in the actual use stage, the motor control device receives the rotation angle from the rotation angle sensor, determines a correction value corresponding to the rotation angle based on the correction table, and reflects the correction value. Calculate the corrected motor rotation speed.

  According to the embodiment, when detecting the rotation speed of the motor using the rotation angle sensor, it is possible to reduce the speed ripple.

It is the schematic which shows the structural example of the motor system by Embodiment 1 of this invention. It is the schematic which shows the structural example of the motor in FIG. It is a schematic diagram which shows the equivalent circuit and coordinate axis on the electrical angle in the motor of FIG. It is the schematic which shows the structural example of the error correction part in FIG. FIG. 5 is a schematic diagram illustrating an operation example of an error correction unit in FIG. 4. It is a figure explaining the acquisition number of the reference | standard rotation angle in the correction table of FIG. It is a flowchart which shows an example of the processing content of the table preparation part in FIG. It is a figure which shows the relationship between the dq axis | shaft used as the real axis | shaft of a motor, and the (gamma) (delta) axis used as a motor control axis. It is a flowchart which shows an example of the processing content of the correction value calculation part in FIG. FIG. 5 is a schematic diagram showing a modified example of the motor system of FIG. 1 and showing a configuration example around an error correction unit different from FIG. 1. (A), (b) and (c) is a figure which shows an example of the rotational speed detection system which does not use a differential calculation. It is a figure explaining the premise problem in the motor system by Embodiment 2 of this invention. In the motor system by Embodiment 2 of this invention, it is the schematic which shows the structural example and operation example of the table preparation part contained in the error correction part of FIG. FIG. 6 is a schematic diagram illustrating a configuration example of an error correction unit in FIG. 1 in a motor system according to a third embodiment of the present invention. It is the schematic which shows the structural example of the motor system by Embodiment 4 of this invention. It is the schematic which shows the structural example of the motor system used as the comparative example of this invention. It is a figure which shows an example of time transition of the rotation angle (mechanical angle) output from a rotation angle sensor at the time of steady rotation of a motor.

  In the following embodiment, when it is necessary for the sake of convenience, the description will be divided into a plurality of sections or embodiments. However, unless otherwise specified, they are not irrelevant, and one is the other. Some or all of the modifications, details, supplementary explanations, and the like are related. Further, in the following embodiments, when referring to the number of elements (including the number, numerical value, quantity, range, etc.), especially when clearly indicated and when clearly limited to a specific number in principle, etc. Except, it is not limited to the specific number, and may be more or less than the specific number.

  Further, in the following embodiments, the constituent elements (including element steps and the like) are not necessarily indispensable unless otherwise specified and apparently essential in principle. Needless to say. Similarly, in the following embodiments, when referring to the shapes, positional relationships, etc. of the components, etc., the shapes are substantially the same unless otherwise specified, or otherwise apparent in principle. And the like are included. The same applies to the above numerical values and ranges.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment, and the repetitive description thereof will be omitted.

(Embodiment 1)
<< Outline of Motor System (Embodiment 1) >>
FIG. 1 is a schematic diagram showing a configuration example of a motor system according to Embodiment 1 of the present invention. FIG. 2 is a schematic diagram showing a structural example of the motor in FIG. FIG. 3 is a schematic diagram showing an equivalent circuit and coordinate axes on an electrical angle in the motor of FIG. The motor system shown in FIG. 1 includes a motor control device MCD, an inverter INV, a current sensor ISEN, a motor MT, and a rotation angle sensor RSEN.

  The motor MT is, for example, a three-phase (u-phase, v-phase, w-phase) synchronous motor (in other words, a brushless DC motor) including a rotor RT and a stator ST, as shown in FIG. In this example, the rotor RT is composed of a permanent magnet having 14 poles (the number of pole pairs (P) is 7), and the stator ST includes 12 slots each wound with a coil. Thus, in the case of the motor MT having the number of pole pairs (P) of 7, one rotation (360 °) of the mechanical angle θ corresponds to seven rotations (7 × 360 °) of the electrical angle θe, and the electrical angle θe is the mechanical angle. It becomes P times θ.

  Such a motor MT has a three-phase resistance component Ru, Rv, Rw, an inductance component Lu, Lv, Lw, and an induced voltage when viewed on a three-phase axis (u-axis, v-axis, w-axis) as fixed coordinates. It is represented by Eu, Ev, Ew. Taking the u phase as an example, the resistance component Ru, the inductance component Lu, and the induced voltage Eu are coupled in series between the midpoint and the u-phase drive terminal PNu with the rotor RT as a midpoint. The u-axis, v-axis, and w-axis are arranged in the energization direction (current direction) of the u-phase, v-phase, and w-phase, respectively, and are sequentially arranged at an electrical angle interval of 120 ° with respect to the rotation direction of the rotor RT.

  On the other hand, the fixed coordinates (three-phase axes) can be converted into two-phase axes (d-axis and q-axis) serving as rotational coordinates. The d axis is arranged in the magnetic flux direction of the rotor RT, and the q axis is arranged in a direction orthogonal to the d axis. The rotation angle (electrical angle) θe usually represents the angle between the u axis and the d axis, and is information representing the positional relationship between the three phases (u phase, v phase, w phase) and the rotor RT. When viewed on a two-phase axis serving as rotational coordinates, the motor MT is represented by a resistance component Ra, a d-axis inductance component Ld and a q-axis inductance component Lq, and a d-axis induced voltage Ed and a q-axis induced voltage Eq. . However, the d-axis induced voltage Ed is zero. When current (q-axis current Iq) flows in the q-axis direction by vector synthesis of three-phase currents, torque in the rotational direction is generated with respect to the rotor RT.

  Here, as a structure of the motor MT (specifically, the rotor RT), an SPM (Surface Permanent Magnet) structure (non-salient pole structure) in which Lq = Ld and an IPM (Interior Permanent Magnet) structure in which Lq ≠ Ld ( Salient pole structure) is known. In the case of the SPM structure, the current in the d-axis direction (d-axis current Id) does not contribute to torque. In the case of the IPM structure, torque (reactance torque) is also generated by the d-axis current Id. Further, the resistance component Ra has the same value for the d-axis and the q-axis regardless of the SPM structure or the IPM structure.

  Returning to FIG. 1, the inverter INV functions as a motor driver, and a drive voltage Vu, based on PWM (Pulse Width Modulation) signals PWMu, PWMv, PWMw is applied to the three-phase drive terminals PN (u, v, w) of the motor MT. Vv and Vw are applied, respectively. Although not shown, the inverter INV includes a three-phase high-side switching element provided between the three-phase drive terminal PN (u, v, w) and the high-potential side power supply voltage, and a three-phase external terminal. A three-phase low-side switching element provided between PN (u, v, w) and the low-potential-side power supply voltage.

  The current sensor ISEN detects three-phase drive currents Iu and Iv (and Iw) of the motor MT. In this example, two-phase (u-phase, v-phase) drive currents Iu, Iv are detected, and the remaining one-phase (w-phase) drive current Iw is calculated based on the relationship of “Iu + Iv + Iw = 0”. Various specific current detection methods are known, and any of them may be applied. Typically, a method of inserting a shunt resistor in the current path of each phase in the inverter INV, a method of providing a sense transistor in the inverter INV, or a current transformer in the output path of each phase from the inverter INV. The method etc. are mentioned.

  The rotation angle sensor RSEN is, for example, a resolver having one pole pair installed on the rotation shaft of the motor MT, and detects the rotation angle (mechanical angle) θ of the motor MT. When the resolver is used, the rotation angle sensor RSEN includes a resolver digital converter (RDC), and the rotation angle (mechanical angle) θ is obtained as a digital value. The rotation angle sensor RSEN is not necessarily limited to the resolver, but may be a magnetic sensor such as a rotary encoder, a rotary potentiometer, a Hall element, or an MR element.

  The motor control device MCD includes, for example, a microcontroller equipped with a processor, an analog / digital converter, a PWM modulator (PWM generation timer), and the like, and controls the motor MT by vector control. The motor control device MCD includes a PWM signal generation unit PWMG, a three-phase / two-phase conversion unit (current coordinate conversion unit) AXCC, a rotation speed calculation unit RSCAL, an error correction unit ERC, a speed controller RSCT, and current control. And ICT.

Although details will be described later, the error correction unit ERC creates a correction table for determining correction values for a plurality of different reference rotation angles at predetermined angular intervals in a preparation stage before actual use. Further, in the actual use stage, the error correction unit ERC receives the rotation angle (mechanical angle) θ from the rotation angle sensor RSEN, and based on the correction table, a correction value (corresponding to the rotation angle (mechanical angle) θ) ( Here, the speed correction value Δω _C ) is output.

The rotation speed calculation unit RSCAL receives the correction value (speed correction value Δω _C ) from the error correction unit ERC and calculates the corrected rotation speed ω _C of the motor MT by reflecting the speed correction value Δω _C. Specifically, the rotation speed calculation unit RSCAL first calculates the rotation speed ω before correction based on the differential calculation of the rotation angle (mechanical angle) θ from the rotation angle sensor RSEN. Next, the rotation speed calculation unit RSCAL corrects the uncorrected rotation speed ω with the speed correction value Δω _C from the error correction unit ERC (specifically, “ω−Δω _C ” is calculated using the subtractor SBc). And the corrected rotation speed ω _C (= ω−Δω _C ) is output. Further, the rotational speed calculation unit RSCAL generates a rotational angle (electrical angle) θe in response to the rotational angle (mechanical angle) θ from the rotational angle sensor RSEN. For example, in the case of the motor MT of FIG. 2, the rotation angle (electrical angle) θe is generated by multiplying the rotation angle (mechanical angle) θ by seven.

  The three-phase / two-phase converter (current coordinate converter) AXCC converts each phase current detected by the current sensor ISEN into a d-axis current Id and a q-axis current Iq. Specifically, the three-phase / two-phase conversion unit AXCC converts the two-phase (u-phase, v-phase) drive currents Iu and Iv from the current sensor ISEN using an analog / digital converter, and performs the remaining conversion. One-phase (w-phase) drive current Iw is calculated by digital calculation. The three-phase / two-phase conversion unit AXCC converts the drive currents Iu, Iv, Iw of the fixed coordinates (u, v, w coordinates) thus obtained from the rotation angle (electrical angle) from the rotation speed calculation unit RSCAL. Using θe, the rotation coordinate (dq coordinate) is converted into a d-axis current Id and a q-axis current Iq.

Speed controller RSCT defines the q-axis target current Iq ^* in accordance with the error between the rotational speed omega _C after correction from the target rotation speed omega ^* and the rotation speed calculation unit RSCAL motor MT. Specifically, the speed controller RSCT includes a subtractor SBrs, a speed PI controller PICrs, and a torque constant multiplier TQM. Subtractor SBrs calculates an error of the target rotation speed omega ^* and the rotation speed omega _C corrected. The speed PI controller PICrs calculates a torque value (operation amount) necessary to bring the error close to zero using PI control (proportional / integral control). The torque constant multiplier TQM multiplies the torque value from the speed PI controller PICrs by “1 / Kt (Kt is a torque constant)” to obtain the q-axis target current Iq ^* necessary for obtaining the torque value. Determine.

The current controller ICT includes a q-axis target current Iq ^* from the speed controller RSCT, a predetermined d-axis target current Id ^* (zero in this example), a d-axis current Id from the three-phase / two-phase converter AXCC, and The d-axis target voltage Vd ^* and the q-axis target voltage Vq ^* are determined according to the error from the q-axis current Iq. Specifically, the current controller ICT includes subtractors SBid and SBiq and current PI controllers PICid and PICiq.

The subtractor SBid calculates an error between the d-axis target current Id ^* and the d-axis current Id from the three-phase / two-phase converter AXCC, and the current PI controller PICid is necessary to bring the error close to zero. The d-axis target voltage Vd ^* is calculated using PI control. Similarly, the subtractor SBiq calculates an error between the q-axis target current Iq ^* and the q-axis current Iq from the three-phase / two-phase converter AXCC, and the current PI controller PICiq causes the error to approach zero. Q-axis target voltage Vq ^* required for the calculation is calculated using PI control.

The PWM signal generation unit PWMG generates PWM signals PWMu, PWMv, and PWMw for the three phases of the motor MT based on the d-axis target voltage Vd ^* and the q-axis target voltage Vq ^* from the current controller ICT. Specifically, the PWM signal generation unit PWMG includes a two-phase / three-phase conversion unit AXCR and a PWM modulator PWMMD. The two-phase / three-phase converter AXCR performs conversion from the rotation coordinate (dq coordinate) to the fixed coordinate (u, v, w coordinate) using the rotation angle (electrical angle) θe from the rotation speed calculation unit RSCAL. The d-axis target voltage Vd ^* and the q-axis target voltage Vq ^* are converted into the u-phase target voltage Vu ^* , the v-phase target voltage Vv ^*, and the w-phase target voltage Vw ^* . The PWM modulator PWMMD generates three-phase PWM signals PWMu, PWMv, and PWMw each having a duty ratio corresponding to the three-phase target voltages (Vu ^* , Vv ^* , Vw ^* ).

As a specific example, the target rotational speed ω ^* during steady rotation of the motor MT is 60 Hz (3600 rpm) or the like. The rotation speed calculation unit RSCAL updates the corrected rotation speed ω _C and rotation angle (electrical angle) θe at a predetermined speed control cycle (sampling cycle) such as 5 kHz, and accordingly, the error correction unit ERC also performs a predetermined correction. A speed correction value Δω _C is output at the speed control period. The speed controller RSCT operates at a predetermined speed control cycle, and its control band (PI control band) is set to about several tens of Hz. The current controller ICT operates at a predetermined current control period such as 10 kHz, for example, and its control band (PI control band) is set to about several hundred Hz. The three-phase / two-phase conversion unit AXCC operates at a predetermined current control cycle, and the PWM signal generation unit PWMG operates at a predetermined PWM control cycle such as 20 kHz.

  In addition, here, each part constituting the motor control device MCD is mainly implemented by program processing by a processor in the microcontroller. However, of course, the present invention is not limited to this, and part or all of them are dedicated. It can also be implemented by hardware. Further, the motor system of FIG. 1 performs speed control with the speed control loop as a major loop and the current control loop inside as a minor loop. For example, the speed control loop is a minor loop and position control provided outside the speed control loop. The configuration may be such that position control is performed using a loop as a major loop.

<< Outline and problems of motor system (comparative example) >>
FIG. 16 is a schematic diagram illustrating a configuration example of a motor system as a comparative example of the present invention. FIG. 17 is a diagram illustrating an example of temporal transition of the rotation angle (mechanical angle) output from the rotation angle sensor during steady rotation of the motor. The motor system shown in FIG. 16 differs from the motor system shown in FIG. 1 in that the motor control device MCD ′ includes a disturbance observer DOBS and a differential operation unit DCAL instead of the error correction unit ERC shown in FIG. Is a point provided with a different rotational speed calculation unit RSCAL ′.

  First, as shown in FIG. 17, during the steady rotation of the motor MT, the rotation angle (mechanical angle) θ output from the rotation angle sensor RSEN is ideally constant with time as indicated by the ideal characteristic ISP. It changes with the slope of. However, the rotation angle (mechanical angle) θ that is actually output is an angle with reference to the ideal characteristic ISP, as shown in the actual characteristic RSP, due to manufacturing variations of the rotation angle sensor RSEN, installation variations with respect to the motor MT, and the like. The value includes the error Δθ. When such an angle error Δθ occurs, a speed ripple occurs in the rotation speed obtained by the differential calculation of the rotation angle (mechanical angle) θ.

Therefore, the differential calculation unit DCAL in FIG. 16 calculates the rotational speed ω before correction by differentially calculating the rotation angle (mechanical angle) θ from the rotation angle sensor RSEN. The disturbance observer DOBS sequentially estimates the angle error Δθ using various parameters (Vd ^* , Vq ^* , Id, Iq, ω) including the rotational speed ω before correction. The rotation speed calculation unit RSCAL ′ uses the subtractor SBc ′ to correct the rotation angle (mechanical angle) θ from the rotation angle sensor RSEN with the angle error Δθ from the disturbance observer DOBS, and the corrected rotation angle θ _C The corrected rotational speed ω _C is calculated by differentiating. Here, as shown in Non-Patent Document 1, etc., the disturbance observer DOBS estimates, for example, an extended induced voltage regarded as a disturbance using a feedback circuit reflecting the extended induced voltage equation, and the estimated extended induced voltage The circuit is configured to calculate the angle error Δθ based on the above.

  In order to obtain a highly accurate correction value (angle error Δθ), it is usually necessary to set the control band of the feedback circuit constituting the disturbance observer DOBS to be several times the frequency of the electrical angle θe. For example, when a motor MT having the number of pole pairs = 7 as shown in FIG. 2 is used and the frequency of the mechanical angle θ is 60 Hz, the frequency of the electrical angle θe is 420 Hz. However, in practice, the upper limit of the control band is limited to, for example, about 1 kHz from the viewpoint of preventing oscillation of the control system. As a result, the higher the frequency of the electrical angle θe (the greater the number of pole pairs of the motor) and the higher the rotational speed, the more the control band becomes short, and as a result, the estimation accuracy of the angle error Δθ decreases.

When the estimation accuracy of the angle error Δθ is reduced, the rotational speed omega _C after correction, which may speed ripple somewhat large remains. As a result, it may be difficult to improve the accuracy and responsiveness when controlling the speed of the motor MT. Specifically, for example, when the control gain (proportional gain, integral gain, etc.) of the speed controller RSCT is increased in order to increase the speed control response, the speed ripple is also amplified, making it difficult to increase the response.

On the other hand, a method of reducing speed ripple by providing a filter for ripple removal at the output of the rotation speed calculation unit RSCAL ′ is also conceivable. However, since the frequency of the speed ripple is often low and often included in the control band of the speed controller RSCT, it is difficult to obtain an effect. Further, when providing a filter for ripple rejection, since a delay in rotation speed omega _C after correction from rotation speed calculation unit RSCAL 'occurs, it may cause a decrease in responsiveness. Therefore, it is useful to use the error correction unit ERC and the like of FIG.

<< Details around the error correction section >>
FIG. 4 is a schematic diagram illustrating a configuration example of the error correction unit in FIG. The error correction unit ERC shown in FIG. 4 includes a table creation unit TBLG and a correction value calculation unit CCAL. The table creation unit TBLG creates the correction table CTBL using the axis error calculation unit ECAL in a state where the motor MT is normally rotated in a preparatory stage before actual use. The preparation stage before actual use is a stage after the motor system as shown in FIG. 1 is constructed (in other words, assembled), and before actual actuator control using the motor MT is actually performed (that is, actual use). This is the previous stage. The correction table CTBL is mounted on, for example, a non-volatile memory in a microcontroller, and once created, it can be used continuously unless the specifications of the motor system are changed.

  The correction table CTBL is for determining correction values for a plurality of different reference rotation angles θr [n] at a predetermined angular interval (4.5 ° in this example), and in this example, a plurality of reference rotation angles. The angle error Δθ [n] for each θr [n] is held. The axis error calculation unit ECAL uses the motor voltage equation as a trigger when the rotation angle (mechanical angle) θ from the rotation angle sensor RSEN reaches each of a plurality of reference rotation angles θr [n], and uses the motor voltage equation as the dq axis of the motor. And the axis error between the γδ axes in motor control based on the detection result of the rotation angle sensor RSEN. Then, the axis error calculation unit ECAL regards the axis error obtained by the calculation as the angle error Δθ [n] and registers it in the correction table CTBL.

In the actual use stage, the correction value calculation unit CCAL recognizes the angle error Δθ [n] corresponding to the rotation angle (mechanical angle) θ from the rotation angle sensor RSEN based on the correction table CTBL, and corrects the speed by the differential operation. The value Δω _C is calculated and output. Specifically, the correction value calculation unit CCAL determines two reference rotation angles θr [k], which are adjacent to each other from among a plurality of reference rotation angles θr [n] according to the rotation angle (mechanical angle) θ. θr [k−1] is determined. Then, the correction value calculation unit CCAL has two axis errors (angle errors) Δθ [k] and Δθ [k−1 corresponding to the two reference rotation angles θr [k] and θr [k−1], respectively. ] Is divided by a predetermined speed control period (for example, a period of 5 kHz (200 μs)) Ts to calculate a speed correction value Δω _C.

FIG. 5 is a schematic diagram illustrating an operation example of the error correction unit in FIG. FIG. 5 shows an example of a change in the angle error Δθ accompanying a change in the rotation angle (in other words, time) during the steady rotation of the motor MT. In the rotation angle sensor RSEN, as indicated by the actual characteristic RSP, an angle error Δθ can occur with respect to the rotation angle (mechanical angle) θ. Along with this, a speed error Δω (= d (Δθ) / dt) may also occur due to the differential calculation of the angle error Δθ. Therefore, the correction value calculation unit CCAL determines two reference rotation angles θr [k] and θr [k−1] corresponding to the rotation angle (mechanical angle) θ as shown in FIG. A speed correction value Δω _C for canceling the speed error Δω is calculated based on a difference value between the two axis errors (angle errors) Δθ [k] and Δθ [k−1].

The two reference rotation angles θr [k] and θr [k−1] can be determined by various methods. For example, in the case of “θr [k−1] <θ ≦ θr [k]”, there is a method in which “θr [k], θr [k−1]” is set as two reference rotation angles. In this case, in the correction table CTBL of FIG. 4, for example, two reference rotation angles “θr [2] (= 9.0 °), θr [ 1] (= 4.5 °) ”is selected, and the speed correction value Δω _C is calculated based on the difference value (dt2−dt1) between the corresponding angle errors Δθ [2] and Δθ [1].

In this example, the correction table CTBL holds an angle error (axis error) Δθ [n] for each of a plurality of reference rotation angles θr [n]. However, if the speed control cycle Ts is constant, the speed correction value Δω _C is uniquely determined with respect to the reference rotation angles θr [k] and θr [k−1]. It is also possible to hold a speed correction value (Δω _C [n]) for each of a plurality of reference rotation angles θr [n].

  FIG. 6 is a diagram illustrating the number of acquisitions of the reference rotation angle in the correction table of FIG. As shown in FIG. 6, when the angle error Δθ can be approximated by a linear function, the angle error Δθ can be reproduced if, for example, there are at least about 10 acquisition points every 90 °. In this case, the number of acquisitions (Nmax) is, for example, about 40 points (= 10 points × 4 × primary). The number of acquisitions (Nmax) when the angle error Δθ can be approximated by a quadratic function is, for example, about 80 points (= 10 points × 4 × second order).

  In the example of the correction table CTBL in FIG. 4, the reference rotation angle acquisition number (Nmax) is 80 points, and the angle interval θcalc (FIG. 6) between adjacent reference rotation angles is 4.5 °. The size (required storage capacity) of the correction table CTBL is, for example, “4 bytes (floating point) × number of acquisitions”. Here, the acquisition number is determined based on the order of the angle error Δθ. However, the acquisition number may be determined based on the order of the speed ripple waveform when the rotation angle sensor RSEN makes one rotation. In addition, if the necessary storage capacity can be secured, the reproducibility of the angle error Δθ increases as the number of acquisitions increases, so the number of acquisitions may be further increased.

FIG. 7 is a flowchart showing an example of processing contents of the table creation unit in FIG. The flow is executed by, for example, program processing in a preparation stage before actual use. First, the table creating unit TBLG constantly rotates the motor MT using the speed control loop and the current control loop of FIG. 1 with the control band of the speed controller RSCT of FIG. 1 lower than the actual use stage (step S101). ). Specifically, the control band in the actual use stage of the speed controller RSCT is, for example, several tens of Hz, etc., but with the motor MT being reduced to half or less (preferably about 1/10). It is rotated at the target rotational speed ω ^* during steady rotation in the actual use stage.

  As a result, fluctuations in the rotational speed of the motor MT (and consequently fluctuation factors of the rotational angle (mechanical angle) θ) resulting from the control operation of the speed controller RSCT can be suppressed, so that the rotational angle (mechanical angle) from the rotational angle sensor RSEN can be suppressed. ) Θ is purely a value reflecting the angle error Δθ caused by the rotation angle sensor RSEN. The control band of the speed controller RSCT is determined by the control gain (proportional gain, integral gain) of the speed PI controller PICrs. The speed PI controller PICrs is configured so that the control gain can be variably set.

  Next, the table creating unit TBLG sets n = 0 (step S102), and sets the reference rotation angle θr [n] to “θcalc × n” using the angle interval θcalc shown in FIG. 6 (step S103). Subsequently, the table creating unit TBLG waits for the rotation angle (mechanical angle) θ from the rotation angle sensor RSEN to reach the reference rotation angle θr [n] determined in step S103 (steps S104 and S105). When the rotation angle (mechanical angle) θ reaches the reference rotation angle θr [n], the table creation unit TBLG uses the axis error calculation unit ECAL as a trigger, and uses the dq axis of the motor and the rotation angle sensor RSEN. An axis error with respect to the γδ axis in motor control based on the detection result is calculated (step S106). The axis error obtained thereby can be regarded as an angle error Δθ [n] at the reference rotation angle θr [n] of the rotation angle sensor RSEN.

  Therefore, the table creation unit TBLG registers the correspondence between the reference rotation angle θr [n] and the angle error Δθ [n] obtained in step S106 in the correction table CTBL (step S107), and increments n (step S107). S108). Thereafter, the table creating unit TBLG repeats the loop processing of steps S103 to S108 until n exceeds a predetermined maximum value (number of acquisition) Nmax (for example, 79) (step S109). Thereby, the correction table CTBL as shown in FIG. 4 is created.

  Here, the processing content of the axis error calculation unit ECAL in step S106 will be specifically described. First, the d-axis and q-axis voltage equations of the motor MT are expressed by the equations (1) and (2) based on the equivalent circuit shown in FIG.

Vd ^* = (Ra + s × Ld) × Id−ω × Lq × Iq + Eγ (1)
Vq ^* = (Ra + s × Lq) × Iq + ω × Ld × Id + Eδ (2)
“Vd ^* ” and “Vq ^* ” are the d-axis and q-axis target voltages from the current controller ICT, and “Id” and “Iq” are the d-axis and q from the three-phase / two-phase converter AXCC. It is a shaft current. “Ra”, “Ld” and “Lq” are the resistance component, d-axis and q-axis inductance component of the motor MT, and are set in advance manually or using a known parameter identifier or the like. “Ω” is a rotation speed before correction in the rotation speed calculation unit RSCAL. When the flow of FIG. 7 is executed, the speed correction value Δω _C is set to zero, and “ω _C = ω”. “S” is a differential operator. “Eγ” is a γ-axis induced voltage on the γ-axis (motor control axis) corresponding to the d-axis (real motor axis), and “Eδ” is δ corresponding to the q-axis (real motor axis). This is the δ-axis induced voltage on the shaft (motor control axis).

  Here, when the motor MT is in a steady rotation state and the rotation angle θ from the rotation angle sensor RSEN does not include the angle error Δθ, the γδ axis on the motor control based on the detection result of the rotation angle sensor RSEN is the motor MT. Coincides with the dq axis. In this case, the γ-axis induced voltage Eγ calculated by the equation (1) is zero, which is the same as the d-axis induced voltage Ed. On the other hand, when the rotation angle θ includes an angle error Δθ, it is reflected in the rotation speed ω before correction, and the γ-axis induced voltage Eγ calculated by the equation (1) does not match the d-axis induced voltage Ed (ie, Non-zero). As a result, as shown in FIG. 8, an axis error corresponding to the angle error Δθ occurs between the dq axis and the γδ axis.

  FIG. 8 is a diagram showing the relationship between the dq axis that is the real axis of the motor and the γδ axis that is the control axis of the motor. As shown in FIG. 8, when the γ-axis induced voltage Eγ is non-zero, the dq axis and the qq-induced voltage Eq are set so that the vector composite value of the γ-axis induced voltage Eγ and the δ-axis induced voltage Eδ matches the q-axis induced voltage Eq. An axial error (Δθ) occurs between the γδ axes. The axis error (Δθ) is determined by Expression (3), and can be regarded as the angle error Δθ of the rotation angle sensor RSEN.

Δθ = tan ⁻¹ (Eγ / Eδ) (3)
Here, the γ-axis induced voltage Eγ and the δ-axis induced voltage Eδ required when calculating the angle error (axis error) Δθ of Expression (3) are as shown in Expression (1) and Expression (2). Includes the differential operator “s”. For this reason, in order to perform the calculation of Expression (3), a disturbance observer composed of a feedback circuit is usually required. However, if a disturbance observer is used, the problem of the control band occurs as in the case of FIG. 16, and it may be difficult to create the correction table CTBL with high accuracy.

On the other hand, particularly in the motor MT that requires high-speed rotation, the resistance component “Ra” and the inductance components “Ld” and “Lq” in Equation (1) and Equation (2) are both small, so the first term on the right side is ignored. Even in this case, the γ-axis induced voltage Eγ and the δ-axis induced voltage Eδ can be calculated with practically sufficient accuracy. Therefore, the axis error calculation unit ECAL calculates an angle error (axis error) Δθ by the equation (4). As a result, the axis error calculation unit ECAL can calculate the angle error Δθ by a simple mathematical calculation process, thereby eliminating the problem of the control band. Each parameter (Vd ^* , Vq ^* , Id, Iq) in the equation (4) is updated at a predetermined current control period (such as a 10 kHz period). For this reason, the axis error calculation unit ECAL also calculates the angle error Δθ of Expression (4) with a predetermined current control period.

Δθ = tan ⁻¹ ((Vd ^* + ω × Lq × Iq) / (Vq ^* −ω × Ld × Id)) (4)
FIG. 9 is a flowchart showing an example of processing contents of the correction value calculation unit in FIG. The flow is executed by, for example, program processing in the actual use stage. The correction value calculation unit CCAL acquires the rotation angle (mechanical angle) θ from the rotation angle sensor RSEN at a predetermined speed control period (such as a period of 5 kHz) (step S201). Next, as described with reference to FIGS. 4 and 5, the correction value calculation unit CCAL determines the reference rotation angles θr [k] and θr [k−1] corresponding to the acquired rotation angle (mechanical angle) θ and corrects the correction. Corresponding angle errors Δθ [k], Δθ [k−1] are acquired from the table CTBL (step S202). Subsequently, the correction value calculation unit CCAL using a predetermined speed control period Ts, the speed correction value [Delta] [omega _C is calculated and outputted by the formula (5) (step S203).

Δω _C = (Δθ [k] −Δθ [k−1]) / Ts (5)
As described above, by using the motor system of FIG. 1, the angle error Δθ can be estimated without using the disturbance observer DOBS as shown in FIG. Thereby, for example, even when the motor MT having a large number of pole pairs as shown in FIG. 2 is used, the angle error Δθ can be estimated with high accuracy. As a result, the speed ripple of the rotational speed can be reduced. It becomes possible. If the speed ripple can be reduced, it becomes possible to improve the accuracy and responsiveness in the speed control of the motor MT. Further, since the ripple removing filter as described with reference to FIG. 16 is not necessary, a delay problem does not occur, and sufficient responsiveness can be maintained.

<< Details of the error correction area (modified example) >>
FIG. 10 is a schematic diagram illustrating a configuration example around an error correction unit that is a modification of the motor system of FIG. 1 and is different from FIG. The error correction unit ERCa illustrated in FIG. 10 includes the table creation unit TBLG illustrated in FIG. Unlike the error correction unit ERC shown in FIG. 1 and FIG. 4, the error correction unit ERCa receives the rotation angle (mechanical angle) θ from the rotation angle sensor RSEN and responds based on the correction table CTBL in the actual use stage. Is output as an angle correction value. That is, while the error correction unit ERC in FIGS. 1 and 4 outputs the speed correction value [Delta] [omega _C, error correction unit ERCa of Figure 10, and outputs the angle correction value ([Delta] [theta]).

Similarly to the case of FIG. 16, the rotation speed calculation unit RSCAL ′ corrects the rotation angle (mechanical angle) θ with the angle correction value (Δθ) using the subtractor SBc ′, and calculates the corrected rotation angle θ _C. The corrected rotational speed ω _C is calculated by differentiating. When the correction table CTBL is created, the angle correction value (Δθ) is set to zero, and accordingly, the corrected rotational speed ω _C becomes equal to the uncorrected rotational speed ω.

When the configuration example as shown in FIG. 10 is used, the angle error Δθ can be estimated without using the disturbance observer as shown in FIG. For this reason, for example, even when the motor MT having a large number of pole pairs is used, the speed ripple can be reduced. However, when the configuration example of FIG. 10 is used, the rotational speed calculation unit RSCAL ′ calculates the corrected rotational speed ω _C by differentiating the corrected rotational angle θ _C. As a result, the correction accuracy may be reduced.

That is, in the configuration example of FIG. 10, the rotational speed is substantially corrected with a value obtained by superimposing the quantization error associated with the differential operation on the angle correction value (Δθ), not the angle correction value (Δθ). Become. On the other hand, the configuration example of FIG. 1 is a direct correction to method the rotational speed at a speed correction value [Delta] [omega _C, the speed correction value [Delta] [omega _C, the quantization error due to differential operation is not overlapped. Therefore, from the viewpoint of correction accuracy, it is preferable to use the configuration example of FIG. 1 rather than the configuration example of FIG.

In addition, when the configuration example of FIG. 1 is used, if the rotation speed ω before correction that is to be corrected by the speed correction value Δω _C is calculated by a method that does not use differential operation, the quantum that can be included in the rotation speed ω before correction is included. Since the influence of the conversion error can be eliminated, the correction accuracy can be further improved. FIG. 11A, FIG. 11B, and FIG. 11C are diagrams illustrating an example of a rotational speed detection method that does not use differential calculation.

  FIG. 11A shows an equivalent circuit of a resolver RSV as an example of what constitutes the rotation angle sensor RSEN. When the resolver RSV is supplied with the excitation signal Vin having the excitation frequency fin from the motor control device MCD of FIG. 1, the resolver RSV is modulated with a sine component (sin θ) of the rotation angle (mechanical angle) θ, and the rotation angle A position signal Vo2 modulated by a cosine component (cos θ) of (mechanical angle) θ is output. An RDC (resolver digital converter) included in the rotation angle sensor RSEN combines these position signals Vo1 and Vo2 to obtain an RDC output signal Vo. For this reason, when the rotational speed (rotational frequency) of the resolver RSV is fr, the frequency of the RDC output signal Vo becomes “fin ± fr” along with the modulation.

  When the motor MT (resolver RSV) is stationary, the frequency of the RDC output signal Vo based on the position signals Vo1 and Vo2 is equal to the excitation frequency fin of the excitation signal Vin as shown in FIG. On the other hand, when the motor MT (resolver RSV) is in a rotating state, as shown in FIG. 11 (c), between the frequency of the RDC output signal Vo based on the position signals Vo1 and Vo2 and the excitation frequency fin of the excitation signal Vin. Produces a frequency difference equal to the rotational frequency fr. Therefore, the motor control device MCD in FIG. 1 can detect the rotation frequency fr (and thus the rotation angle θ before correction) by monitoring the phase difference between the excitation signal Vin and the RDC output signal Vo, for example.

<< Main effects of the first embodiment >>
As described above, by using the motor system of the first embodiment, it is possible to reduce the speed ripple when detecting the rotational speed of the motor MT using the rotational angle sensor RSEN. Further, since the speed ripple can be reduced without using the high-precision (and expensive) rotation angle sensor RSEN, the cost of the motor system can be reduced.

(Embodiment 2)
《Prerequisite problems》
FIG. 12 is a diagram for explaining a premise problem in the motor system according to the second embodiment of the present invention. As described in the first embodiment, the angle error Δθ [n] for each of the plurality of reference rotation angles θr [n] is registered in the correction table CTBL in FIG. Each angle error Δθ [n] is a digital value, and actually includes a quantization error associated with various digitizations. Specifically, for example, in FIG. 1, the quantization error when digitizing each phase current (Iu, Iv) or the quantum when digitizing the rotation angle (originally an analog value) of the rotation angle sensor RSEN. Conversion error and the like.

In the example of FIG. 12, the quantization error ΔQ [i] is included in the angle error Δθ [i] corresponding to the reference rotation angle θr [i], and the angle error Δθ [i + 2] corresponding to the reference rotation angle θr [i + 2]. Includes a quantization error ΔQ [i + 2]. The inclusion of such a quantization error, higher speed ripple rotational speed omega _C after correction can be superimposed.

<< Details of Table Creation Unit (Embodiment 2) >>
FIG. 13 is a schematic diagram illustrating a configuration example and an operation example of the table creation unit included in the error correction unit of FIG. 1 in the motor system according to the second embodiment of the present invention. The table creation unit TBLGb of FIG. 13 includes a moving average processing unit MAV in addition to the axis error calculation unit ECAL shown in FIG. The table creation unit TBLGb further performs a moving average process on the axis error Δθr [n] (that is, the correction table CTBL in FIG. 4) for each of the plurality of reference rotation angles θr [n] in a preparation stage before actual use. Thus, the correction table CTBLb is created. The correction value calculation unit CCAL shown in FIG. 4 calculates and outputs a speed correction value Δω _C based on the correction table CTBLb.

  In this example, the moving average processing unit MAV targets the angular errors Δθ [n] of the reference rotation angle θr [n] and j angular errors Δθ [n−j] to Δθ [n− positioned on the descending order side. 1] and j angular errors Δθ [n + 1] to Δθ [n + j] located on the ascending order side, a moving average process (ie, adding and averaging) is performed. Then, the moving average processing unit MAV registers the angle error Δθa [n] obtained as a result in the correction table CTBLb in association with the reference rotation angle θr [n]. At this time, after n = 79, it is regarded that n = 0. For example, “j = 5”.

<< Main effects of the second embodiment >>
As described above, by using the motor system of the second embodiment, the same effect as that of the first embodiment can be obtained. At this time, it is possible to reduce high-order speed ripples.

(Embodiment 3)
<< Details of Error Correction Unit (Embodiment 3) >>
FIG. 14 is a schematic diagram illustrating a configuration example of the error correction unit in FIG. 1 in the motor system according to the third embodiment of the present invention. The error correction unit ERCc shown in FIG. 14 is different from the error correction unit ERC shown in FIG. 4 in that a disturbance observer DOBS is provided in the table creation unit TBLGc instead of the axis error calculation unit ECAL of FIG. Is different. The disturbance observer DOBS estimates the axis error Δθ by the feedback circuit as in the case of FIG. 16, and registers the axis error Δθ in the correction table CTBL as in the case of FIG.

  Specifically, the disturbance observer DOBS estimates the axis error (Δθ) of the equation (3) based on the γ-axis induced voltage Eγ of the equation (1) and the δ-axis induced voltage Eδ of the equation (2), for example. It is a feedback circuit. When such a disturbance observer DOBS is used, the estimation accuracy may be further improved as compared with the case where the axis error (Δθ) is estimated using the equation (4) as in the error correction unit ERC of FIG. . However, as described above, it is assumed that the control band of the disturbance observer DOBS can be sufficiently secured with respect to the frequency of the electrical angle θe of the motor MT.

Therefore, the table preparation unit TBLGc calculates the axis error Δθ using the disturbance observer DOBS in a state in which the motor MT is regularly rotated at a rotation speed lower than the rotation speed in the actual use stage in the preparation stage before actual use. . Specifically, the table creation unit TBLGc sets the target rotational speed ω ^* to a value of about a fraction of the actual use stage when the motor MT is rotated at step S101 in FIG.

  Thereby, it is possible to sufficiently secure the control band of the disturbance observer DOBS with respect to the frequency of the electrical angle θe of the motor MT, and it is possible to estimate the axis error Δθ with high accuracy. At this time, the angle error (axis error) Δθ of the rotation angle sensor RSEN does not depend on the rotation speed in principle, so that no particular problem occurs even if the calculation is performed with the rotation speed lowered. Further, in the actual use stage, the disturbance observer DOBS does not operate, so that the problem of the control band does not particularly occur.

<< Main effects of Embodiment 3 >>
As described above, by using the motor system of the third embodiment, the same effect as that of the first embodiment can be obtained. Furthermore, there is a case where the rotational speed correction accuracy can be further improved (and thus the speed ripple can be further reduced) as compared with the case of the first embodiment. Note that the method of the third embodiment can be combined with the method of the second embodiment.

(Embodiment 4)
<< Outline of Motor System (Embodiment 4) >>
FIG. 15 is a schematic diagram illustrating a configuration example of a motor system according to the fourth embodiment of the present invention. The motor system shown in FIG. 15 is different from the configuration example shown in FIG. 16 in that an axis error calculation unit ECAL as shown in FIG. 4 is provided instead of the disturbance observer DOBS. However, unlike the case of FIG. 4, the axis error calculation unit ECAL calculates the angle error (axis error) Δθ using the above-described equation (4) in the actual use stage. As described with reference to FIG. 16, when the disturbance observer DOBS is used in the actual use stage, the problem of the control band may occur, but the problem of the control band can be solved by using the axis error calculation unit ECAL.

<< Main Effects of Embodiment 4 >>
As described above, by using the motor system of the fourth embodiment, the same effect as that of the first embodiment can be obtained. However, in the configuration example of FIG. 15, as in the case of FIG. 10, there is a possibility that the quantization error accompanying the differential operation is superimposed on the angle correction value (Δθ), and the movement as described in FIG. 13 is performed. Adding average processing can also be difficult. Therefore, from such a viewpoint, a method using the correction table CTBL as in the first embodiment is desirable.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiments. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. For example, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to one having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. . Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

<Appendix>
(1) A method of detecting a rotation speed of a motor using a motor control device for a motor whose rotation angle is detected by a rotation angle sensor and controlled by vector control,
The motor control device receives the rotation angle from the rotation angle sensor, sets the rotation speed before correction of the motor to “ω”, sets the d-axis target voltage to “Vd ^* ”, and sets the q-axis target voltage to “Vq ^* ”. D-axis current is “Id”, q-axis current is “Iq”, d-axis inductance component and q-axis inductance component are “Ld” and “Lq”, dq-axis and γδ-axis based on the detection result of the rotation angle sensor The axis error of “Δθ” is
Δθ = tan ⁻¹ ((Vd ^* + ω × Lq × Iq) / (Vq ^* −ω × Ld × Id))
To calculate the rotational speed after the correction of the motor reflecting the axis error,
Method for detecting the rotational speed of a motor.

AXCC 3-phase / 2-phase converter (current coordinate converter)
CCAL correction value calculation unit CTBL correction table DOBS disturbance observer ECAL axis error calculation unit ERC error correction unit ICT current controller INV inverter ISEN current sensor Id d-axis current Iq q-axis current Ld d-axis inductance component Lq q-axis inductance component MAV moving average Processing unit MCD motor control device MT motor PWMG PWM signal generation unit RSCAL rotation speed calculation unit RSCT speed controller RSEN rotation angle sensor RSV resolver TBLG table creation unit Ts speed control cycle Vd ^* d-axis target voltage Vq ^* q-axis target voltage Δθ angle Error (axis error)
Δω _C speed correction value θ Rotation angle (mechanical angle)
θcalc angle interval θe rotation angle (electrical angle)
θr Reference rotational angle ω Rotational speed before correction ω ^* Target rotational speed ω _C rotational speed after correction

Claims (20)

A motor controlled by vector control;
A rotation angle sensor for detecting a rotation angle of the motor;
A current sensor for detecting each phase current of the motor;
A current coordinate conversion unit that converts each phase current detected by the current sensor into a d-axis current and a q-axis current;
In a preparation stage before actual use, a correction table for determining correction values for a plurality of different reference rotation angles at predetermined angular intervals is created, and in the actual use stage, the rotation angle from the rotation angle sensor is received. An error correction unit that outputs a correction value corresponding to the rotation angle based on the correction table;
A rotation speed calculation unit that receives the correction value from the error correction unit and calculates a rotation speed after correction of the motor by reflecting the correction value;
A speed controller that determines a target current according to an error between the target rotational speed of the motor and the corrected rotational speed from the rotational speed calculation unit;
A current controller that determines a d-axis target voltage and a q-axis target voltage according to an error between the target current from the speed controller and the d-axis current and the q-axis current from the current coordinate conversion unit;
A PWM signal generator for generating a PWM signal for each phase of the motor based on the d-axis target voltage and the q-axis target voltage from the current controller;
Have
In the preparation stage, the error correction unit is configured to trigger the time when the rotation angle from the rotation angle sensor reaches each of the plurality of reference rotation angles in a state where the motor is normally rotated. Detection result of the dq axis of the motor and the rotation angle sensor using a motor voltage equation using the rotational speed before correction, the d axis target voltage, the q axis target voltage, the d axis current and the q axis current as parameters. Calculating an axis error with the γδ axis based on the above, and creating the correction table based on the calculation result of the axis error for each of the plurality of reference rotation angles,
Motor system. The motor system according to claim 1,
The error correction unit outputs a speed correction value corresponding to the rotation angle from the rotation angle sensor in the actual use stage,
The rotational speed calculation unit corrects the rotational speed of the motor before the correction with the speed correction value in the actual use stage.
Motor system. The motor system according to claim 2, wherein
The rotation speed calculation unit calculates the rotation speed before the correction based on a differential operation of the rotation angle from the rotation angle sensor;
Motor system. The motor system according to claim 2, wherein
The error correction unit determines two reference rotation angles that are adjacent to each other among the plurality of reference rotation angles according to the rotation angle from the rotation angle sensor, and corresponds to each of the two reference rotation angles. The speed correction value is calculated by dividing the difference value of the two axis errors by a predetermined control cycle.
Motor system. The motor system according to claim 1,
The speed controller is configured so that a control band can be variably set,
The error correction unit calculates the axis error in the preparation stage in a state where the control band of the speed controller is lower than the actual use stage.
Motor system. The motor system according to claim 1,
The error correction unit sets the rotation speed before correction to “ω”, the d-axis target voltage to “Vd ^* ”, the q-axis target voltage to “Vq ^* ”, the d-axis current to “Id”, and the q Assuming that the shaft current is “Iq”, the d-axis inductance component and the q-axis inductance component of the motor are “Ld” and “Lq”, and the shaft error is “Δθ”,
Δθ = tan ⁻¹ ((Vd ^* + ω × Lq × Iq) / (Vq ^* −ω × Ld × Id))
,
Motor system. The motor system according to claim 1,
The error correction unit includes a disturbance observer that estimates the axis error by a feedback circuit, and the disturbance is performed in a state in which the motor is normally rotated at a rotation speed lower than a rotation speed in the actual use stage in the preparation stage. Calculating the axis error using an observer,
Motor system. The motor system according to claim 1,
The error correction unit creates the correction table by performing a moving average process on the axis error for each of the plurality of reference rotation angles in the preparation stage.
Motor system. The motor system according to claim 1,
The rotation angle sensor is a resolver.
Motor system. A motor control device that controls, by vector control, a motor whose rotation angle is detected by a rotation angle sensor,
A current coordinate converter for converting each phase current of the motor into a d-axis current and a q-axis current;
In a preparation stage before actual use, a correction table for determining correction values for a plurality of different reference rotation angles at predetermined angular intervals is created, and in the actual use stage, the rotation angle from the rotation angle sensor is received. An error correction unit that outputs a correction value corresponding to the rotation angle based on the correction table;
A rotation speed calculation unit that receives the correction value from the error correction unit and calculates a rotation speed after correction of the motor by reflecting the correction value;
A speed controller that determines a target current according to an error between the target rotational speed of the motor and the corrected rotational speed from the rotational speed calculation unit;
A current controller that determines a d-axis target voltage and a q-axis target voltage according to an error between the target current from the speed controller and the d-axis current and the q-axis current from the current coordinate conversion unit;
A PWM signal generator for generating a PWM signal for each phase of the motor based on the d-axis target voltage and the q-axis target voltage from the current controller;
Have
In the preparation stage, the error correction unit is configured to trigger the time when the rotation angle from the rotation angle sensor reaches each of the plurality of reference rotation angles in a state where the motor is normally rotated. Detection result of the dq axis of the motor and the rotation angle sensor using a motor voltage equation using the rotational speed before correction, the d axis target voltage, the q axis target voltage, the d axis current and the q axis current as parameters. Calculating an axis error with the γδ axis based on the above, and creating the correction table based on the calculation result of the axis error for each of the plurality of reference rotation angles,
Motor control device. The motor control device according to claim 10,
The error correction unit outputs a speed correction value corresponding to the rotation angle from the rotation angle sensor in the actual use stage,
The rotational speed calculation unit corrects the rotational speed of the motor before the correction with the speed correction value in the actual use stage.
Motor control device. The motor control device according to claim 11, wherein
The rotation speed calculation unit calculates the rotation speed before the correction based on a differential operation of the rotation angle from the rotation angle sensor;
Motor control device. The motor control device according to claim 11, wherein
The error correction unit determines two reference rotation angles that are adjacent to each other among the plurality of reference rotation angles according to the rotation angle from the rotation angle sensor, and corresponds to each of the two reference rotation angles. The speed correction value is calculated by dividing the difference value of the two axis errors by a predetermined control cycle.
Motor control device. The motor control device according to claim 10,
The speed controller is configured so that a control band can be variably set,
The error correction unit calculates the axis error in the preparation stage in a state where the control band of the speed controller is lower than the actual use stage.
Motor control device. The motor control device according to claim 10,
The error correction unit sets the rotation speed before correction to “ω”, the d-axis target voltage to “Vd ^* ”, the q-axis target voltage to “Vq ^* ”, the d-axis current to “Id”, and the q Assuming that the shaft current is “Iq”, the d-axis inductance component and the q-axis inductance component of the motor are “Ld” and “Lq”, and the shaft error is “Δθ”,
Δθ = tan ⁻¹ ((Vd ^* + ω × Lq × Iq) / (Vq ^* −ω × Ld × Id))
,
Motor control device. The motor control device according to claim 10,
The error correction unit includes a disturbance observer that estimates the axis error by a feedback circuit, and the disturbance is performed in a state in which the motor is normally rotated at a rotation speed lower than a rotation speed in the actual use stage in the preparation stage. Calculating the axis error using an observer,
Motor control device. The motor control device according to claim 10,
The error correction unit creates the correction table by performing a moving average process on the axis error for each of the plurality of reference rotation angles in the preparation stage.
Motor control device. A method of detecting a rotation speed of a motor using a motor control device for a motor whose rotation angle is detected by a rotation angle sensor and controlled by vector control,
The motor control device
In a preparatory stage before actual use, with the motor rotating in a steady state, the time when the rotation angle from the rotation angle sensor reaches each of a plurality of reference rotation angles different at predetermined angular intervals, as a trigger, Based on the detection result of the dq axis of the motor and the rotation angle sensor using a motor voltage equation using the rotation speed, d-axis target voltage, q-axis target voltage, d-axis current and q-axis current as parameters. a first process for calculating a shaft error with respect to the γδ axis and creating a correction table for determining a correction value for each of the plurality of reference rotation angles based on the calculation result;
In the actual use stage, the rotation angle from the rotation angle sensor is received, a correction value corresponding to the rotation angle is determined based on the correction table, and the correction speed is reflected to reflect the correction value. A second process for calculating
Run the
Method for detecting the rotational speed of a motor. The method of detecting the rotational speed of the motor according to claim 18.
In the second process, the motor control device determines a speed correction value corresponding to the rotation angle from the rotation angle sensor based on the correction table, and determines the rotation speed before the correction of the motor as the speed correction. Correct by value,
Method for detecting the rotational speed of a motor. The motor rotation speed detection method according to claim 19,
The motor control device determines two reference rotation angles that are adjacent from the plurality of reference rotation angles according to the rotation angle from the rotation angle sensor, and corresponds to the two reference rotation angles, respectively. The speed correction value is calculated by dividing the difference value of the two axis errors by a predetermined control cycle.
Method for detecting the rotational speed of a motor.

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