JP2001119989A - Motor controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor controller, in which generation of torque ripples can be prevented by estimating an error, e.g. offset, of current sensors. SOLUTION: A voltage sensor 17 detects the neutral voltage of an AC three- phase motor M, and a neutral voltage E detected by the voltage sensor 17 is inputted to an offset-estimating section 18. The offset-estimating section 18 estimates offsets Du, Dv of current sensors 14U, 14V, based on the neutral voltage E. Based on the offsets Du, Dv received from the offset estimating section 18 and the difference between respective phase currents Iu, In, Iw and the target levels thereof Iru, Irv, Irw received from subtracting sections 12U, 12V, 12W, a control section 16 controls the currents being fed to phases U, V, W of the three-phase motor M.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control device for driving and controlling a three-phase AC motor used as a drive source of an electric power steering device.

[0002]

2. Description of the Related Art For example, a three-phase AC motor is used as an electric motor in an electric power steering apparatus for assisting steering by transmitting torque generated by an electric motor to a steering mechanism of a vehicle. The magnitude of the torque generated by the three-phase AC motor is determined, for example, by a control unit including a microcomputer, which performs feedback control of a sine wave current supplied from the driver to each phase (U phase, V phase, W phase) of the motor. It is adjusted by doing. That is, U
A U-phase current, which is a sine wave current flowing in the phase, and a V-phase current, which is a sine wave current flowing in the V phase, are respectively detected by current sensors, and outputs of these current sensors are input to the control unit. The control unit controls W based on the output of each current sensor.
A W-phase current, which is a sine wave current flowing through the phase, is calculated. Then, deviations between the U-phase current, the V-phase current, and the W-phase current and target currents set for the respective phases are calculated, and the driver is controlled based on the calculated deviations.

[0003]

The current sensor has an offset which is a deviation of a sensor output from an actually flowing current, and a sensitivity error which is a rate of change of the sensor output with respect to a change of an actually flowing current. Otherwise, the U-phase current or the V-phase current is not accurately detected.
Therefore, in this case, if the driver is controlled based on the output of each current sensor, the sinusoidal current supplied to the U-phase, V-phase and W-phase deviates from the ideal target, and as a result, the three-phase AC Ripple occurs in the torque generated by the motor.

An object of the present invention is to provide a motor control device capable of estimating an offset of a current sensor. Another object of the present invention is to provide a motor control device capable of estimating a sensitivity error of a current sensor. Still another object of the present invention is to provide a motor control device capable of preventing occurrence of torque ripple.

[0005]

Means for Solving the Problems and Effects of the Invention According to the first aspect of the present invention, there is provided a three-phase AC motor having a current flowing in two phases out of a U phase, a V phase and a W phase. Is respectively detected by two current sensors, and the three-phase AC motor is feedback-controlled based on the outputs of the two current sensors, and detects a voltage at a neutral point of the three-phase AC motor. Neutral voltage detecting means, and error estimating means for estimating a detection error of the two current sensors based on the voltage at the neutral point detected by the neutral voltage detecting means. It is a motor control device characterized by the above-mentioned.

According to the present invention, the detection error of the current sensor can be estimated. Therefore, by controlling the three-phase AC motor in consideration of the estimated detection error, the sine wave current flowing in each phase of the three-phase AC motor can be an ideal target, and the generation of torque ripple can be reduced. Can be prevented. The error estimating means may include an offset estimating means for estimating an offset of an output of each current sensor with respect to a current actually flowing in a phase to be detected by the two current sensors (claim 2). .

In this case, it is preferable that the offset estimating means estimates the offset based on a ripple component generated in the voltage at the neutral point in the same cycle as the electrical angle cycle. Further, the offset estimating means includes:

[0008]

(Equation 3)

Based on the above, it is more preferable to estimate the offset Du of one current sensor and the offset Dv of the other current sensor (claim 4). Further, the error estimating means may further include sensitivity error estimating means for estimating an error in sensitivity of each current sensor with respect to a current actually flowing in each of the phases to be detected by the two current sensors ( Claim 5). In this case, it is preferable that the sensitivity error estimating means estimates the sensitivity error based on a ripple component generated in the voltage at the neutral point in a cycle of half the electrical angle cycle. .

Further, the sensitivity error estimating means includes:

[0011]

(Equation 4)

It is more preferable to estimate the sensitivity error Gu of one current sensor and the sensitivity error Gv of the other current sensor on the basis of the above (claim 7). According to another aspect of the present invention, there is provided a current calculating means for calculating a current flowing through the remaining one phase which is not detected by the two current sensors, based on outputs of the two current sensors, and each phase of the three-phase AC motor. The current to be supplied to each phase of the three-phase AC motor is controlled based on the target current set for each phase, the outputs of the two current sensors and the current calculation means, and the estimation result of the error estimation means. 2. The apparatus according to claim 1, further comprising control means.
8. A motor control device according to any one of claims 1 to 7.

According to the present invention, when the error estimating means includes the offset estimating means, the offsets of the two current sensors are estimated, and the estimated offset, each phase target current, and the two The current to be supplied to the U-phase, V-phase, and W-phase of the three-phase AC motor is controlled based on the outputs of the current sensor and the current calculation means.
Thus, an error due to an offset can be eliminated from the outputs of the two current sensors, and a sine wave current flowing in the U phase, the V phase, and the W phase can be an ideal target. therefore,
The occurrence of torque ripple due to the offset can be prevented.

When the error estimating means includes the sensitivity error estimating means, the sensitivity errors of the two current sensors are estimated, and the estimated sensitivity error, each phase target current and the two currents are estimated. U-phase, V-phase, W-phase of the three-phase AC motor
The current to be supplied to the phase is controlled. As a result, an error due to a sensitivity error can be eliminated from the outputs of the two current sensors, and sine wave currents flowing in the U, V, and W phases can be set as ideal targets. Therefore, the occurrence of torque ripple due to the sensitivity error can be prevented.

[0015]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing the configuration of the motor control device according to the first embodiment of the present invention. The motor control device 10 is for controlling a drive of a three-phase AC motor M used as a drive source of an electric power steering device for a vehicle, for example. The motor control device 10 includes, for example, a CP
It comprises a microcomputer including a U, a RAM and a ROM, and its functions are shown by blocks in FIG.

The motor control device 10 includes target currents Iru, Irv, Irw of each phase (U phase, V phase, W phase) of the motor M.
Is provided for each phase.
For example, when the three-phase AC motor M is used in the electric power steering apparatus, each phase target current setting unit 11 determines the target current based on the magnitude of torque applied to a steering wheel provided in the vehicle. Then, each phase target current Iru, Irv, Irw is set. U-phase target current Iru and V-phase target current I output from each phase target current setting unit 11
rv and the W-phase target current Irw are respectively
U, 12V, and 12W.

The other input terminals of the subtractors 12U, 12V and 12W are connected to the U-phase, V-phase,
Currents Iu, Iv, Iw flowing in the W phase are given. U
The current (U-phase detection current) Iu flowing in the phase and the current (V-phase detection current) Iv flowing in the V-phase are respectively a U-phase current sensor 14U provided in a current supply path 13U to the U-phase winding.
And a V-phase current sensor 14V provided in a current supply path 13V to the V-phase winding. The current (W-phase detection current) Iw flowing in the W-phase is obtained by a calculation executed by the W-phase current calculation unit 15. That is, the outputs Iu and Iv of the current sensors 14U and 14V are given to the W-phase current calculation unit 15, and the W-phase current calculation unit 15 determines that the sum of the currents flowing in each phase of the three-phase AC motor M is zero. From the following equation
The current Iw flowing through the W phase is calculated according to (1).

Iw = 0-Iu-Iv (1) The subtraction units 12U, 12V, and 12W output the target currents Iru, Irv, and Irw for each phase of the three-phase AC motor M, respectively. The deviation from the phase detection currents Iu, Iv, Iw is calculated, and the calculation result is given to the control unit 16. On the other hand, in connection with the three-phase AC motor M, a voltage sensor 17 for detecting a voltage at a neutral point (connection point of the U-phase, V-phase and W-phase) of the three-phase AC motor M is provided. The neutral point voltage E detected by the voltage sensor 17 is input to the offset estimating unit 18. The offset estimating unit 18 estimates the offsets Du and Dv of the current sensors 14U and 14V based on the neutral point voltage E input from the voltage sensor 17. Offset D
u and Dv are the deviations of the outputs of the current sensors 14U and 14V with respect to the currents actually flowing in the U and V phases, respectively.

Here, assuming that the U-phase, V-phase, and W-phase field magnetic fluxes are φu, φv, and φw, respectively, the three-phase AC motor M
Is generated by the following equation (2). T = φu × Iu + φv × Iv + φw × Iw (2) That is, the torque T is the product of the U-phase field magnetic flux φu and the U-phase detection current Iu, and the V-phase field magnetic flux φv and V-phase detection. The sum of the product of the current Iv and the product of the W-phase field magnetic flux φw and the W-phase detection current Iw.

[0020] In addition, the magnetic field flux φu, φv, and the maximum value of the φw and φ _0, each phase of the magnetic field flux φu, φv, φw is, the following formulas (3-1), (3-2), It is represented by (3-3). _{φu = φ 0 sinθ ······ (3-1} ) φv = φ 0 sin [θ- (2/3) π] ······ (3-2) φw = φ 0 sin [θ- (4/3) π] (3-3) Further, the maximum value of the current actually flowing in each phase is defined as Im,
Assuming that the current sensors 14U and 14V have no offset, the phase detection currents Iu, Iv and Iw are represented by the following equations (4-1), (4-2) and (4-3), respectively. .

Iu = Imsin θ (4-1) Iv = Imsin [θ- (2/3) π] (4-2) Iw = Imsin [θ- (4 / 3) π] (4-3) Therefore, the above equations (3-1), (3-2), (3-3),
Substituting (4-1), (4-2) and (4-3) and rearranging, the torque T
Is expressed as: T = (3/2) × φ ₀ × Im (5) Thus, when the current sensors 14U and 14V have no offset, the three-phase AC motor M
Is a stable value independent of the phase angle θ of the current flowing in the U-phase, V-phase, and W-phase.

On the other hand, it is assumed that offsets Du and Dv occur in the outputs of the current sensors 14U and 14V, respectively. In this case, the U-phase detection current Iu and the V-phase detection current Iv do not become the above equations (4-1) and (4-2), respectively, and the following equations (6-1) and (6-2) Will be represented by Iu = Im sin θ + Du (6-1) Iv = Im sin [θ− (2/3) π] + Dv (6-2) The W-phase detection current Iw is calculated by the above equation. (1) and equation (6-1),
From (6-2), Iw = − (Imsin θ + Du) − [Imsin [θ− (2/3) π] + Dv] (6-3). Therefore, the above equations (3-1) and (3-
By substituting 2), (3-3), (6-1), (6-2), and (6-3), the torque T becomes

[0023]

(Equation 5)

## EQU1 ## Thereby, the current sensor 14
When U and 14V have offsets Du and Dv, respectively, it can be seen that the magnitude of the torque T generated by the three-phase AC motor M varies according to the phase angle θ of each phase.
In other words, if the current sensors 14U and 14V have offsets Du and Dv, respectively, it can be seen that torque ripple occurs in the three-phase AC motor M. Here, since the first term of the above equation (7) is a term irrelevant to the phase angle θ, if this first term is eliminated, the above equation (7) shows the torque ripple components caused by the offsets Du and Dv, respectively. The second and third terms that represent Then, an equation consisting of only the term representing the torque ripple component is given by T = K × φ ₀ × Im
By substituting (K: constant) and Im = E / R (R: resistance value of each phase winding), the neutral point voltage E can be expressed by the following equation (8).

[0025]

(Equation 6)

That is, the above equation (8) indicates that the current sensor 14
When U and 14V have offsets Du and Dv, respectively, it indicates that the neutral point voltage E changes with the change of the phase angle θ. When observing the change in the neutral point voltage E accompanying the change in the phase angle θ, when only the U-phase current sensor 14U has the offset Du, for example, a waveform as shown in FIG. 2A is obtained. Also, a V-phase current sensor 14V
Only have an offset Dv, see FIG.
The waveform shown in (b) is obtained, and the U-phase current sensor 14U
And V-phase current sensor 14V are both offset Du,
In the case of having Dv, for example, a waveform as shown in FIG.

The offset estimating section 18 includes a voltage sensor 17
From the waveforms of the neutral point voltage E as shown in FIGS. 2 (a), 2 (b) and 2 (c) obtained on the basis of the input from ₁ and cosθ
= Acquires the value E ₂ of the neutral point voltage E at the phase angle θ to be 0. Then, sin θ = 0 (cos θ = 1) and the value E ₁ of the neutral point voltage E are substituted into the above equation (8), and the following equation (9-
1), and cos θ = 0 (sin θ = 1) and the value E ₂ of the neutral point voltage E are substituted into the above equation (8) to obtain the following equation (9).
-2) is obtained.

E ₁ = (R / K) × [(Du / 2) + Dv] (9-1) E ₂ = (3R / 2K) × Du (9- 2) When the above equation (9-2) is rearranged, Du = 2K · E ₂ / 3R, and the offset Du can be estimated. Substituting this Du into the above equation (9-1) and rearranging it,

[0029]

(Equation 7)

Thus, the offset Dv can be estimated. The offset estimating unit 18 gives the offsets Du and Dv estimated as described above to the control unit 16. The control unit 16 calculates the deviation between the offsets Du and Dv given from the offset estimating unit 18 and the phase target currents Iru, Irv and Irw given from the subtracting units 12U, 12V and 12W and the phase detection currents Iu, Iv and Iw. , The current to be supplied to the U, V, and W phases of the three-phase AC motor M is controlled. Specifically, based on the offsets Du and Dv given from the offset estimating unit 18, the subtracting units 12U, 12V, 12V
The deviation given from W is calculated from the target currents Iru, Irv, Irw of each phase.
And the currents actually flowing in the U-phase, V-phase, and W-phase are corrected so as to match, and based on the corrected deviations, U
The current to be supplied to the phase, V phase, and W phase is controlled. Thereby, the U-phase current sensor 14U and the V-phase current sensor 14V
Has the offsets Du and Dv, respectively, it is possible to realize the motor control excluding the influence of the offsets Du and Dv.

As described above, according to this embodiment, the offsets Du and Dv of the U-phase current sensor 14U and the V-phase current sensor 14V are estimated, and the estimated offsets Du and Dv and the target currents Iru of each phase are estimated. , Irv, I
Based on the deviation between rw and each phase detection current Iu, Iv, Iw,
The current to be supplied to the U, V, and W phases of the three-phase AC motor M is controlled. Thereby, each phase target current Iru, Irv, I
From the deviation between rw and each phase detection current Iu, Iv, Iw, errors due to offsets Du, Dv can be eliminated, and the U phase, V
The amplitude of the sinusoidal current flowing in the phase and the W phase can be made uniform. Therefore, the occurrence of torque ripple due to the offset can be prevented.

[0032] Incidentally, in this embodiment, to obtain the above-mentioned formula (9-1) the value E ₁ of the sin [theta = 0 and becomes such a phase angle θ and the neutral point voltage E is substituted into the equation (8) Together with co
Substituting the phase angle θ such that sθ = 0 and the value E ₂ of the neutral point voltage E into the above equation (8), the above equation (9-2) is obtained, and the thus obtained equation (9-1) is obtained. , (9-2), the offsets Du and Dv are estimated. However, the offsets Du and Dv can be estimated as follows.

That is, at the peak point of the neutral point voltage E,
Ratio dE of change of neutral point voltage E to change of phase angle θ
/ Dθ is zero, and the above equation (8) is converted to the phase angle θ.
Differentiating once, and substituting dE / dθ = 0,

[0034]

(Equation 8)

Can be obtained. Therefore, the offset estimating unit 18 receives an input from the voltage sensor 17 based on the waveform of the neutral point voltage E as shown in FIGS. 2 (a), (b), and (c) obtained based on the input from the voltage sensor 17. Neutral point voltage E
The offsets Du and Dv can be estimated by obtaining two phase angles θp of the peak points of the above and solving the simultaneous equations obtained by substituting the obtained phase angles θp into the above equation (10).

FIG. 3 is a block diagram showing a configuration of a motor control device according to a second embodiment of the present invention. In FIG. 3, parts corresponding to the respective parts shown in FIG. 1 described above are denoted by the same reference numerals. In this embodiment, the output of the voltage sensor 17 for detecting the voltage at the neutral point of the three-phase AC motor M is a sensitivity error estimation for estimating the sensitivity errors Gu and Gv of the current sensors 14U and 14V, respectively. Input to the unit 19. The sensitivity errors Gu and Gv are
It refers to an error in sensitivity, which is a change rate of the output of each of the current sensors 14U and 14V with respect to a change in the current actually flowing in the U phase and the V phase.

It is assumed that the current sensors 14U and 14V have sensitivity errors Gu and Gv, respectively. In this case, the U-phase detection current Iu and the V-phase detection current Iv do not become as in the above equations (4-1) and (4-2), respectively.
1) and (11-2). Iu = GuIsin θ (11-1) Iv = GvIsin [θ− (2/3) π] (11-2) The W-phase detection current Iw is calculated by the above equation 1) and equation (11-1),
From (11-2), Iw = −GuIsin θ−GvIsin [θ− (2/3) π] (11-3) Therefore, the above equations (3-1) and (3-
2), (3-3), (11-1), (11-2), and (11-3) are substituted and rearranged.

[0038]

(Equation 9)

## EQU1 ## Thereby, the current sensor 14
If U and 14V have sensitivity errors Gu and Gv, respectively, the magnitude of the torque T generated by the three-phase AC motor M may fluctuate according to the phase angle θ of the current flowing in each phase. Understand. In other words, if the current sensors 14U and 14V have sensitivity errors Gu and Gv, respectively, torque ripple occurs in the three-phase AC motor M. Here, the above equation (1
From 2), a torque component independent of the phase angle θ (3/2) × φ ₀ ×
By removing Im, an expression representing the torque ripple component caused by the sensitivity errors Gu and Gv is obtained. T = K × φ ₀ × Im
By substituting (K: constant) and Im = E / R (R: resistance value of each phase winding), the neutral point voltage E can be expressed by the following equation (13).

[0040]

(Equation 10)

That is, the above equation (13) indicates that the current sensor 14
If U and 14V have sensitivity errors Gu and Gv, respectively, it indicates that the neutral point voltage E changes with the change of the phase angle θ. When observing the change in the neutral point voltage E accompanying the change in the phase angle θ, if only the U-phase current sensor 14U has the sensitivity error Gu, for example, a waveform as shown in FIG. 4A is obtained. If only the V-phase current sensor 14V has the sensitivity error Gv, for example, a waveform as shown in FIG. 4B is obtained, and the U-phase current sensors 14U and V
When both phase current sensors 14V have sensitivity errors Gu and Gv, for example, a waveform as shown in FIG. 4C is obtained.

The sensitivity error estimating unit 19 determines that sin θ = 0 from the waveform of the neutral point voltage E as shown in FIGS. 4A, 4B, and 4C obtained based on the input from the voltage sensor 17. The value E ₃ of the neutral point voltage E at the phase angle θ, and cos θ =
The value E ₄ of the neutral point voltage E at the phase angle θ that is 0 is obtained. Then, sin θ = 0 (cos θ = 1) and the value E ₃ of the neutral point voltage E are substituted into the above equation (13), and the following equation (14-
1) and substituting cos θ = 0 (sin θ = 1) and the value E ₄ of the neutral point voltage E into the above equation (13),
(14-2) is obtained.

E ₃ = (3R / 2K) × Im × (Gv−1) (14-1) E ₄ = (3R / 2K) × Im × (Gu−1) Rearranging ... (14-2) above formula (14-1), it becomes _{Gu = (2K · E 4 /} 3R · Im) +1, it is possible to estimate the sensitivity error Gu. Moreover, when organizing the above formula (14-2) can be estimated _{Gv = (2K · E 3 /} 3R · Im) +1 , and the sensitivity error Gv.

The sensitivity error estimating section 19 gives the sensitivity errors Gu and Gv estimated as described above to the control section 16. The control unit 16 controls the sensitivity errors Gu and Gv given from the sensitivity error estimating unit 19, the phase target currents Iru, Irv and Irw given from the subtraction units 12U, 12V and 12W, and the phase detection currents Iw.
u, Iv, Iw and the three-phase AC motor M
The current to be supplied to the U-phase, V-phase, and W-phase is controlled. Specifically, the sensitivity error G given from the sensitivity error estimation unit 19
Based on u and Gv, the deviations given by the subtractors 12U, 12V, and 12W are used to calculate the target currents Iru, Irv, Irw and U of each phase.
The phase, the V-phase, and the W-phase are corrected so as to be equal to the deviation from the current actually flowing. Based on the corrected deviation, the U-phase,
The current to be supplied to the V and W phases is controlled. This allows
Even when the U-phase current sensor 14U and the V-phase current sensor 14V have sensitivity errors Gu and Gv, respectively,
Motor control excluding the effects of the sensitivity errors Gu and Gv can be realized.

As described above, according to this embodiment, the sensitivity errors Gu and Gv of the U-phase current sensor 14U and the V-phase current sensor 14V are estimated, and the estimated sensitivity errors Gu and Gv and each phase target The current to be supplied to the U, V, and W phases of the three-phase AC motor M is controlled based on the deviation between the currents Iru, Irv, Irw and the phase detection currents Iu, Iv, Iw. As a result, the amplitudes of the sinusoidal currents flowing in the U-phase, V-phase and W-phase can be made constant by eliminating the effects of the sensitivity errors Gu and Gv, and ripples are generated in the torque generated by the three-phase AC motor M. It can be prevented from occurring.

It is to be noted that the present invention is not limited to the above-described method, and for example, it is also possible to realize a motor control excluding the effects of the sensitivity errors Gu and Gv as follows. U phase current sensor 14U
Has a sensitivity error Gu, the sensitivity error Gu
Does not affect the phases of the phase detection currents Iu, Iv, Iw, the phase angle of the neutral point voltage E peak point (torque ripple peak point) is constant regardless of the magnitude of the sensitivity error Gu. . Similarly, when the V-phase current sensor 14V has a sensitivity error Gv, the phase angle of the neutral point voltage E peak point (torque ripple peak point) is constant regardless of the magnitude of the sensitivity error Gv. And the U-phase current sensor 14
The U and V phase current sensors 14V each have a sensitivity error G
When u and Gv are present, the phase of the peak point of the neutral point voltage E is constant regardless of the magnitude of the sensitivity errors Gu and Gv.

Focusing on the above point, if the phase angle of the peak point of the neutral point voltage E is known, it can be determined from the phase angle whether only the U-phase current sensor 14U has the sensitivity error Gu or the V-phase current sensor. Whether only 14V has a sensitivity error Gv,
It can be determined whether both phase current sensor 14U and V-phase current sensor 14V have sensitivity errors Gu and Gv, respectively. Then, the phase angle of the peak point of the neutral point voltage E when the U-phase current sensor 14U has the sensitivity error Gu is substituted into the above equation (13), and in this equation (13), the neutral point voltage E Is obtained as a map of the sensitivity error Gu with respect to the neutral point voltage E, the U-phase current sensor 14U detects the sensitivity error Gu.
When it is determined that the neutral point voltage E has the sensitivity error Gu from the peak value of the neutral point voltage E,
Can be estimated. Therefore, it is possible to realize the motor control excluding the influence of the sensitivity error Gu.

The V-phase current sensor 14V has a sensitivity error G
Substituting the phase angle of the peak point of the neutral point voltage E in the case of having v into the above equation (13), the sensitivity when the value of the neutral point voltage E is variously changed in the equation (13) If the error Gv is obtained and held as a map of the sensitivity error Gv with respect to the neutral point voltage E, when it is determined that the U-phase current sensor 14U has the sensitivity error Gv, this map is referred to. Thus, the sensitivity error Gv can be estimated from the peak value of the neutral point voltage E. Therefore, it is possible to realize the motor control excluding the influence of the sensitivity error Gv.

Further, when the U-phase current sensor 14U and the V-phase current sensor 14V have sensitivity errors Gu and Gv, respectively, the phase angle of the peak point of the neutral point voltage E is calculated by the above equation (1).
In equation (13), the relationship between the sensitivity error Gu and the sensitivity error Gv when the value of the neutral point voltage E is variously changed is calculated, and for each value of the neutral point voltage E If a map representing the relationship between the sensitivity error Gu and the sensitivity error Gv is held, a map to be referred to from the peak value of the neutral point voltage E when it is determined that the sensitivity errors Gu and Gv are present. The relationship between the sensitivity error Gu and the sensitivity error Gv can be estimated from the selected map. Then, based on the relationship between the estimated sensitivity error Gu and sensitivity error Gv, the U-phase current sensor 1
From the outputs of the 4U and V-phase current sensors 14V, the sensitivity error G
By eliminating the influences of u and Gv, the amplitudes of the sinusoidal currents flowing in the U-phase, V-phase and W-phase can be made uniform, and ripples are generated in the torque generated by the three-phase AC motor M. Can be prevented.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. For example, in the above-described embodiment, the current flowing in the U-phase and the V-phase is detected by the current sensor, and the current flowing in the W-phase is estimated by calculation.
The current flowing in the phase may be detected by a current sensor, and the current flowing in the V phase may be estimated by calculation, or the current flowing in the V phase and the W phase may be detected by the current sensor to calculate the current flowing in the U phase. May be estimated by

In the first embodiment, a configuration for estimating the offset based on the ripple component of the neutral point voltage will be described. In the second embodiment, the configuration will be described based on the ripple component of the neutral point voltage. Although the configuration for estimating the sensitivity error has been described, the case where the current sensor has both the offset and the sensitivity error may be considered. In this case, it is preferable to estimate both the offset and the sensitivity error based on the neutral point voltage detected by the voltage sensor.

As a method for estimating both the offset and the sensitivity error, there is the following method, for example. That is, when the current sensor has an offset, a ripple occurs in the neutral point voltage at the same cycle as the electrical angle cycle, whereas when the current sensor has a sensitivity error, Ripple occurs in the neutral point voltage in a cycle of 1/2 of the electrical angle cycle. Focusing on this point, the waveform of the neutral point voltage detected by the voltage sensor is applied to a band separation filter to separate it into a ripple component waveform due to an offset and a ripple component waveform due to a sensitivity error. The offset and the sensitivity error may be estimated based on each waveform in the same manner as in the method described in each embodiment.

In addition, various design changes can be made within the scope of the technical matters described in the claims.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a motor control device according to a first embodiment of the present invention.

FIG. 2 is a waveform diagram showing torque ripple (fluctuation of neutral point voltage) that occurs when an offset occurs.

FIG. 3 is a block diagram illustrating a configuration of a motor control device according to a second embodiment of the present invention.

FIG. 4 is a waveform diagram illustrating torque ripple (fluctuation of neutral point voltage) that occurs when a sensitivity error occurs.

[Explanation of symbols]

 Reference Signs List 10 Motor controller 11 Target current setting section for each phase 14U U-phase current sensor 14V V-phase current sensor 15 W-phase current calculation section (current calculation section) 16 Control section (control section) 17 Voltage sensor (neutral point voltage detection section) 18 Offset Estimator (Offset Estimator) 19 Sensitivity Error Estimator (Sensitivity Error Estimator) M Three-Phase AC Motor

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Nobuyoshi Sugitani 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation F-term (reference) 5H575 AA17 BB04 BB10 DD03 GG04 HB01 JJ03 JJ04 JJ17 JJ25 LL22 LL24 LL29 MM16

Claims (8)

[Claims] A current flowing in two phases of a U-phase, a V-phase and a W-phase of a three-phase AC motor is detected by two current sensors, respectively, and based on the outputs of the two current sensors, the three-phase AC is detected. A motor control device that performs feedback control of a motor, comprising: a neutral point voltage detecting unit that detects a voltage at a neutral point of the three-phase AC motor; and a neutral point voltage detected by the neutral point voltage detecting unit. An error estimating means for estimating a detection error of the two current sensors based on the voltage. 2. An apparatus according to claim 1, wherein said error estimating means includes offset estimating means for estimating an offset of an output of each current sensor with respect to a current actually flowing in a phase to be detected by said two current sensors. The motor control device according to claim 1. 3. The motor according to claim 2, wherein the offset estimating means estimates the offset based on a ripple component generated in the voltage at the neutral point in the same cycle as the electrical angle cycle. Control device. 4. The offset estimating means comprises: , The offset Du of one current sensor and the offset Dv of the other current sensor
The motor control device according to claim 2, wherein the motor controller is estimated. 5. The apparatus according to claim 1, wherein said error estimating means further includes sensitivity error estimating means for estimating an error of sensitivity of each current sensor with respect to a current actually flowing in a phase to be detected by said two current sensors. The motor control device according to any one of claims 1 to 3, wherein: 6. The apparatus according to claim 1, wherein said sensitivity error estimating means is one of the electrical angle periods.
6. The motor control device according to claim 5, wherein a sensitivity error is estimated based on a ripple component generated in the voltage at the neutral point in a cycle of / 2. 7. The sensitivity error estimating means comprises: , The sensitivity error G of one current sensor has
7. The motor control device according to claim 5, wherein a sensitivity error Gv of u and the other current sensor is estimated. 8. Based on the outputs of the two current sensors,
Current calculating means for calculating a current flowing in the remaining one phase which is not detected by these two current sensors; a target current for each phase set for each phase of the three-phase AC motor; the two current sensors and the current calculating means And control means for controlling a current to be supplied to each phase of the three-phase AC motor based on the output of the three-phase AC motor and the estimation result of the error estimating means.
The motor control device according to any one of the above.