JP2003158886A - Motor controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor controller which achieves offset correction at low cost and besides at real time, by suppressing the increase of quantity of calculation without increasing the number of circuit parts. SOLUTION: An offset detection means 13 successively detects an offset by the difference between the present value of a motor current converted into a two-phase by three-phase - two-phase conversion with a motor current detection means 12 and the value of a half cycle ahead of the motor current. Moreover, an offsetting means 14 performs offset correction by successively subtracting the detected offset from the present value of the motor current converted into the two-phase.

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, and more particularly, to a motor utilizing reluctance torque generated by an inductance change of an armature winding and an armature current, or a magnetic flux of a reluctance torque and a permanent magnet and an electric machine. The present invention relates to a device for controlling a motor that is used in combination with a magnet torque generated by a child current.

[0002]

2. Description of the Related Art Generally, a motor utilizing reluctance torque generated with an inductance change of an armature winding and an armature current, or a reluctance torque and a magnetic torque generated with a magnetic flux of a permanent magnet and an armature current. In a motor control device that controls a motor that is used together, the motor current supplied to each phase of the motor is detected by a current detection circuit, and the motor torque, speed, or position is detected based on the detection output of this current detection circuit. Etc. are configured to control. The current detection circuit is composed of a current detection sensor using, for example, a Hall element and an analog amplifier such as an operational amplifier for amplifying the output of the current detection sensor.

However, it is known that these sensors and analog amplifiers produce a signal other than 0, that is, a so-called offset, at the output thereof even though the input thereof is 0. This offset gives an error to the motor current detection signal detected by the current detection circuit, adversely affects the control of the motor torque, speed or position, and deteriorates the control performance thereof.

Therefore, as a method for correcting this offset, for example, Japanese Unexamined Patent Publication No. 5-252785 shown in FIG.
The motor control device described in the publication is proposed. Figure 7
In, the main circuit is composed of the motor 3 and the power amplifier 72 that supplies power to the motor 3 based on the motor drive signal from the controller 71. Further, the motor 3 is provided with an encoder 73 for generating rotational position information and a pole sensor 74 for generating magnetic pole position information.

On the other hand, the control circuit includes current sensors 11a and 11b for detecting the motor current and current sensors 11a and 11b.
Amplifiers 75a, 75b for amplifying the output signal of
And an analog-to-digital converter 76 that converts the analog signals from the analog amount to the digital amount in order to capture the output signals of the analog amplifiers 75a and 75b into the controller 71, motor current information obtained from the analog-digital converter 76, and rotational position information from the encoder 73. And a controller 71 that generates a motor drive signal using the magnetic pole position information from the pole sensor 74.

Here, in the controller 71, the motor current detected by the current sensors 11a and 11b is integrated over one cycle, or the ratio of the positive / negative time of the motor current is obtained, and the integrated value or the positive / negative time is calculated. The offset value is calculated directly from the ratio, and the offset value is sequentially subtracted from the motor current detected by the current sensors 11a and 11b to perform the offset correction.

[0007]

However, in the above-mentioned conventional configuration, the motor current is integrated over one cycle,
Alternatively, since the positive / negative time ratio of the motor current is calculated and the offset value is calculated directly from this integral value or the positive / negative time ratio, the cost increases due to the increase in the capacity of the arithmetic unit as the calculation amount increases, and the calculation time increases. However, there is a problem that the reliability of the motor control performance is deteriorated with the increase of.

Further, in the above-mentioned conventional configuration, the offset correction can be performed only in the steady state in which the motor is driven at a constant rotation speed, and the offset correction cannot be performed in the transient state in which the motor is accelerated / decelerated. Had the problem of being.

The present invention is intended to solve such a conventional problem, and it is a motor control that realizes offset correction in real time at a low cost by suppressing an increase in the amount of calculation without increasing the number of circuit components. The purpose is to provide a device.

[0010]

In order to solve the above-mentioned problems, a motor control device according to the present invention uses a reluctance torque generated by an inductance change of an armature winding and an armature current, or Motor current detecting means for detecting a motor current supplied to each phase of a motor, which uses the reluctance torque, the magnetic flux of the permanent magnet and the magnet torque generated by the armature current in combination, is provided. In a motor control device for controlling a motor based on the detection output of, the offset detection means that sequentially detects the offset of the detection output from at least a half cycle of the detection output of the motor current detection means, and the detected offset is sequentially subtracted from the detection output. And an offset canceling means for canceling the offset.

[0011]

According to the motor control device of the present invention, since the offset is sequentially detected from the half cycle of the detection output of the motor current detection means, the increase in the amount of calculation is suppressed and the cost increase due to the increase in the capacity of the calculation device is prevented. In addition, offset correction can be performed in real time.

Further, the offset detecting means has a time measuring means for measuring an elapsed time from the start of operation of the motor, and compares the elapsed time measured by the time measuring means with a preset predetermined time, It is possible to employ one that detects the offset only when the time is an integral multiple of the predetermined time.

According to the above arrangement, since the offset detection is performed every predetermined time, the calculation time associated with the offset detection can be greatly shortened, the load capacity of the calculation device can be reduced, and the cost can be reduced.

As the offset canceling means, there is provided time measuring means for measuring the elapsed time from the start of operation of the motor, and the elapsed time measured by the time measuring means is compared with a preset predetermined time, It is possible to employ one that cancels the offset only when the time is an integral multiple of the predetermined time.

According to the above configuration, since the offset correction is performed every predetermined time, the calculation time required for the offset correction is significantly shortened, the load capacity of the calculation device is reduced, and the peripheral circuit for the offset correction is simplified. Is possible.

As the offset detecting means, there is provided a stable state determining means for determining whether or not the motor control system has reached a stable state, and detecting the offset only when the motor control system reaches the stable state. It is possible to adopt.

According to the above construction, the offset detection is performed only when the control system of the motor reaches a stable state. Therefore, the calculation time required for the offset detection is shortened, the load capacity of the arithmetic unit is reduced, and the cost is reduced. Not only can it be achieved, but offset detection can be avoided when the motor control system is unstable, and deterioration of motor control performance can be prevented.

Further, as the offset canceling means, there is adopted a stable state judging means for judging whether or not the motor control system has reached a stable state, and canceling the offset only when the motor control system is in the stable state. It is possible to

According to the above arrangement, the offset correction is performed only when the motor control system is in a stable state.
Not only can the calculation time associated with offset correction be shortened, the load capacity of the arithmetic unit can be reduced, and the peripheral circuits associated with offset correction can be simplified, but offset correction when the motor control system is unstable can be avoided. However, it is possible to prevent deterioration of motor control performance.

Further, it is possible to employ, as the offset detecting means, one having an offset detection stable switching means having hysteresis before and after switching between the time when the offset is detected and the time when the offset is not detected.

According to the above arrangement, it is possible to secure the control stability associated with switching between the time when the offset is detected and the time when the offset is not detected, and to reduce noise and vibration.

As the offset canceling means, it is possible to employ one having an offset canceling stable switching means having a hysteresis before and after switching between offset canceling and non-cancelling.

According to the above configuration, it is possible to secure control stability associated with switching between offset offset and non-offset offset, and prevent out-of-step of the motor.

Further, as the offset canceling means, a means for comparing the value of the offset detected by the offset detecting means with a preset predetermined value and canceling the offset only when the offset value is larger than the predetermined value is adopted. It is possible to

According to the above configuration, the offset correction is performed only when the influence of the offset is large. Therefore, the calculation time required for the offset correction is shortened, the load capacity of the calculation device is reduced, and the peripheral circuit accompanying the offset correction is reduced. Not only can the motor be simplified, but also the motor control performance can be improved.

Further, it is possible to employ, as the offset canceling means, one which functions in synchronization with the offset detecting means.

According to the above arrangement, the calculation time required for the offset detection and the offset correction can be shortened to the maximum, the load capacity of the calculation device can be further reduced, and the cost can be largely reduced.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 shows a system configuration of an embodiment of a motor control device according to the present invention. In FIG. 1, the main circuit is composed of a DC power supply 1 and three sets of two switching elements connected in series, which are connected in parallel, and an inverter 2 for converting DC power into AC power and an inverter 2 for conversion. It is composed of a motor 1 driven by AC power.

On the other hand, the control circuit includes the current sensors 11a, 11b and 11c attached to the main circuit and the current sensor 1.
A motor current detection unit 12 that detects a motor current by using outputs from 1a, 11b, and 11c as inputs, an offset detection unit 13 that sequentially detects an offset from a half cycle of the motor current detected by the motor current detection unit 12, and a motor Offset cancellation unit 1 that performs offset correction (offset cancellation) by sequentially subtracting an offset from a current
4, a motor control calculator 15 that generates a motor drive signal based on the offset-corrected motor current, and an energization distributor 16 that outputs a gate signal to the switching element of the inverter 2.

Generally, when performing sine wave drive,
In order to facilitate the control calculation, the parameters of the motor are set to u, v, w
The three phases are converted into a direct current by performing a three-phase / two-phase conversion from the three-phase to the two phases of the dq axes. The definition of coordinate axes in the three-phase to two-phase conversion is shown in FIG. In FIG. 2, θ is an actual magnetic pole position obtained from a position sensor such as an encoder. The method of converting from three phases to two phases is publicly known and will not be described.

Specifically, offset correction is performed using the following method.

When the output signal of the motor current detector 12 is set to outside 1, the motor current i actually supplied to the motor is i.
u, iv, iw and offset ΔI due to current sensor, etc.
It is expressed as in Equation 1 using u, ΔIv, and ΔIw.

[Outer 1]

[Equation 1] Further, assuming that the motor current effective value is I1, the current phase angle is β, and the actual magnetic pole position is θ, the motor currents iu, iv, and iw are expressed as in Equation 2.

[0033]

[Equation 2] Here, when the three-phase / two-phase conversion is performed using the equations 1 and 2, the two-phase currents id and iq on the dq axes are represented by the equation 3.

[0034]

[Equation 3] That is, at the two-phase currents id and iq, the offset ΔI
It can be seen that u, ΔIv, and ΔIw are converted into AC components.

Next, the offset detection method will be described.

An embodiment of the offset detection method is shown in FIG. In FIG. 3, the horizontal axis represents the actual magnetic pole position θ, and the vertical axis represents the q-axis current iq of the equation 3.

Here, assuming that the current value of the magnetic pole position is θs, the offset Δiq [θs] at this time is expressed by the equation 4 using the value of the half cycle before.

[0038]

[Equation 4] That is, the offset is sequentially detected based on the difference between the current value of the q-axis current iq and the value half cycle before.

Although the offset Δiq is derived only for the q-axis current iq in the above description, the offset Δid of the d-axis current id can be derived by using a similar method.

Regarding the value before the half cycle, only the half cycle value of the two-phase currents id and iq may be stored in the internal register of the arithmetic unit such as the microcomputer.

The offset can be corrected by successively subtracting the offset Δiq from the current value of the q-axis current iq.

That is, the current value of the magnetic pole position is θs, the current value of the q-axis current is iq [θs], and the current value of the offset is Δiq.
If [θs] is set, the correction current outside 2 is expressed as in Equation 5.

[Outside 2]

[Equation 5] In the above description, only the q-axis current iq is outside the correction current 3
, But using the same method, d-axis current id
The correction current outside 4 can be derived.

[Outside 3]

[Outside 4] As described above, since the offsets are sequentially detected from the half-cycles of the two-phase currents id and iq, it is possible to suppress the increase in the amount of calculation, prevent the cost increase due to the increase in the capacity of the calculation device, and perform the offset correction in real time. is there.

Regarding the offset detection method, the offset may be detected by obtaining the average value of the two-phase currents id and iq and successively subtracting the average value from the current value.

That is, the average value of the two-phase currents id and iq is
Then, the offsets Δid and Δiq are expressed as in Equation 6.

[Outside 5]

[Equation 6] Here, the average value outside 5 is expressed as in Equation 7.

[0045]

[Equation 7] In the above description, θ is the actual magnetic pole position obtained from the position sensor such as an encoder, but it is also applicable to the case where the magnetic pole position is estimated without using the position sensor.
In this case, the estimated position may be used instead of the actual magnetic pole position.

(Second Embodiment) FIG. 4 shows a system configuration of a second embodiment of the motor control device according to the present invention. The same components as those of the motor control device shown in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted to avoid duplication and only different portions will be described here. In FIG. 4, the offset detecting unit 13 compares the elapsed time Tnow measured by the time measuring unit 41 from the start of operation of the motor with a preset predetermined time T1 by the comparison calculator 42, and Tnow =
Offset detection is performed only when the condition of mT1 (m = 1, 2, 3) is satisfied.

Further, the offset canceling section 14 compares the elapsed time Tnow measured by the time measuring section 41 from the start of the operation of the motor with a preset predetermined time T2 by the comparison calculator 43, and Tnow = mT2 ( m = 1, 2, 3)
Offset correction is performed only when the condition of is satisfied.

Here, the time measuring unit 41 can obtain the elapsed time from the start of operation by performing addition from the time when the motor is started by an arithmetic unit such as a microcomputer. However,
When an arithmetic unit such as a microcomputer is used for addition, it is necessary to take measures against errors such as overflow.

Note that the method of the first embodiment is used as a specific method of offset detection and offset correction.

As described above, the offset detection and / or the offset correction are performed at predetermined time intervals, so that the calculation time associated with the offset detection and / or the offset correction is greatly reduced, and the load capacity of the arithmetic unit is reduced. Therefore, the cost can be reduced as compared with the motor control device according to the first embodiment.

In the above description, the predetermined time T1 in the offset detection and the predetermined time T2 in the offset correction are different, but T1 and T2.
Is equivalent, that is, the effect is greatest when the offset detection and the offset correction function in synchronization, and the calculation time associated with the offset detection and the offset correction is shortened to the maximum.
It is possible to further reduce the load capacity of the arithmetic unit and significantly reduce the cost.

(Third Embodiment) FIG. 5 shows a system configuration of a third embodiment of the motor control device according to the present invention. Figure 1
The same components as those of the motor control device shown in are shown by the same reference numerals, and the description thereof will be omitted to avoid duplication and only different parts will be described here. In FIG. 5, the offset detection unit 13 performs the offset only when the stable state determination unit 51 that determines whether the motor control system has reached the stable state determines that the motor control system has reached the stable state. Perform detection.

Further, the offset canceling section 14 determines whether or not the motor control system has reached the stable state by the stable state determining section 51 which determines whether or not the motor control system has reached the stable state. Perform offset correction.

Here, the stable state determination unit 51 determines whether the difference between the current value of the actual motor speed ω obtained by differentiating the actual magnetic pole position θ with time and the previous value, that is, the fluctuation speed is within a predetermined value α. Make a decision.

Specifically, the current value of the actual speed of the motor is set to ω
Now, if the previous value is ωlast, the fluctuation speed Δωn
Is expressed as Equation 8.

[0056]

[Equation 8] Here, offset detection and / or offset correction are performed only when the condition of | Δωn | ≦ α is satisfied.

The specific method of offset detection and offset correction is the method of the first embodiment.

As described above, when the motor control system reaches the stable state, the offset detection, the offset correction, or both are performed.
Alternatively, the calculation time associated with offset correction, or both, is reduced, the load capacity of the calculation device is reduced, and offset detection and / or offset correction in a state where the motor control system is unstable are avoided. It is possible to prevent deterioration of motor control performance.

In the above description, it is determined whether or not the stable state is reached by using the actual motor speed ω, but instead of ω, the two-phase currents id and iq derived by the equation 7 are obtained.
A value other than the average value of 5 may be used.

That is, it is judged whether or not the difference between the current value of the outer 5 and the previous value, that is, the current deviation is within the predetermined value α.

(Embodiment 4) FIG. 6 shows an embodiment of the offset detection stable switching method according to the present invention. In the motor control device of Embodiment 3, a hysteresis is set for the variable speed Δωn. This is an offset detection stable switching method. In FIG. 6, the fluctuation speed | Δωn | = α
A hysteresis characteristic having a fluctuation range of ωh is added to the boundary of ωh, and the switching of the offset detection mode (when the offset is detected / when the offset is not detected) is stably performed with respect to the speed fluctuation near | Δωn | = α. Is possible.

Here, if the fluctuation width ωh is appropriately selected, it is possible to minimize the control instability element such as hunting accompanying switching of the offset detection mode.

In the hysteresis characteristic of FIG. 6,
Although the switching of the offset detection mode is abrupt, it is possible to further improve the control stability by giving an inclination to this and gradually switching the control mode.

Although only the offset detection stable switching method has been described in the above description, the same hysteresis characteristic should be set for the offset cancellation mode (offset cancellation / offset cancellation). Can be applied to the offset cancellation stable switching method.

(Fifth Embodiment) A fourth embodiment of the motor control device according to the present invention will be described. Since the system configuration is exactly the same as that of the motor control device shown in FIG. 1, description of the system configuration will be omitted. In FIG. 1, the offset canceller 14 compares the offset value detected by the offset detector 13 with a preset predetermined value, and performs offset correction only when the offset value is larger than the predetermined value. Is.

Specifically, as expressed by the equation 4, the offsets Δid and Δiq sequentially detected from at least half cycle of the two-phase currents id and iq and the predetermined value ε set in advance.
d and εq are respectively compared, and Δid ≧ εd and Δi
Offset correction is performed only when both conditions of q ≧ εq are satisfied.

As described above, since the offset correction is performed only when the influence of the offset is large, the calculation time required for the offset correction can be shortened, the load capacity of the calculation device can be reduced, and the motor control performance can be improved more effectively. .

[0068]

As is apparent from the above, according to the invention described in claim 1, since the offset is sequentially detected from the half cycle of the detection output of the motor current detecting means, the increase of the calculation amount is suppressed and the calculation device of the calculation device is suppressed. Preventing cost increase due to capacity increase,
In addition, it is possible to perform offset correction in real time, and further it is possible to prevent deterioration of motor control performance at all times by performing offset correction in real time.

According to the second aspect of the present invention, since the offset detection is performed at every predetermined time, the calculation time required for the offset detection is significantly reduced, and the load capacity of the calculation device is reduced.
This has the effect of reducing costs and improving motor control performance.

According to the third aspect of the present invention, since the offset correction is performed every predetermined time, the calculation time required for the offset correction is significantly shortened, the load capacity of the arithmetic unit is reduced, and the peripheral circuit for the offset correction is reduced. It is possible to simplify and further improve the motor control performance.

According to the invention described in claim 4, since the offset is detected when the control system of the motor reaches a stable state, the calculation time associated with the offset detection is shortened, the load capacity of the arithmetic unit is reduced, and the cost is reduced. In addition to the above, it is possible to avoid the offset detection when the control system of the motor is unstable and prevent the deterioration of the motor control performance.

According to the fifth aspect of the present invention, the offset correction is performed when the control system of the motor reaches a stable state. Therefore, the calculation time required for the offset correction is shortened, and the load capacity of the calculation device is reduced. Not only can peripheral circuits associated with offset correction be simplified, but offset correction can be avoided when the motor control system is unstable, and motor control performance can be prevented from deteriorating. .

According to the invention described in claim 6, it is possible to secure the control stability associated with the switching between the time when the offset is detected and the time when the offset is not detected, and to reduce the noise and vibration, so that a stable motor drive system can be realized. Has the effect of being

According to the invention described in claim 7, it is possible to secure control stability associated with switching between offset offset and non-offset offset, and prevent out-of-step of the motor. There is an effect that it can be realized.

According to the invention described in claim 8, since the offset correction is performed only when the influence of the offset is large, the calculation time required for the offset correction is shortened, the load capacity of the arithmetic unit is reduced, and the offset correction is performed. Not only can the peripheral circuits be simplified, but also the motor control performance can be improved.

According to the ninth aspect of the present invention, the calculation time required for the offset detection and the offset correction is shortened to the maximum, the load capacity of the calculation device is further reduced, and the cost is significantly reduced and the motor control performance is further improved. The effect is achieved.

[Brief description of drawings]

FIG. 1 is a block diagram of a motor control device showing an embodiment of the present invention.

FIG. 2 is a definition diagram of coordinate axes in three-phase / two-phase conversion.

FIG. 3 is a diagram showing an embodiment of an offset detection method according to the present invention.

FIG. 4 is a block diagram of a motor control device showing a second embodiment of the present invention.

FIG. 5 is a block diagram of a motor control device showing a third embodiment of the present invention.

FIG. 6 is a diagram showing an embodiment of an offset detection stable switching method according to the present invention.

FIG. 7 is a block diagram of a motor control device showing a conventional example.

[Explanation of symbols]

3 motor 12 Motor current detector 13 Offset detector 14 Offset offset section 41 hour measurement section 51 Stable state determination unit

Continued front page    F term (reference) 5H560 BB04 BB18 DA14 DC12 EB01                       RR03 SS01 TT07 UA02 XA02                       XA13 XB04                 5H576 BB04 BB10 CC01 DD02 DD09                       EE01 EE18 EE19 GG04 HA02                       HB01 JJ03 JJ18 LL22

Claims (9)

[Claims] 1. A motor utilizing reluctance torque generated in association with an armature winding inductance change and armature current, or a magnet generated in association with the reluctance torque and magnetic flux of a permanent magnet and the armature current. Motor current detecting means (1) for detecting a motor current supplied to each phase of a motor used in combination with torque
In a motor control device including 2), which controls the motor (3) based on the detection output of the motor current detection means (12), the detection is performed from at least half cycle of the detection output of the motor current detection means (12). Motor control comprising: an offset detection means (13) for sequentially detecting an output offset; and an offset cancellation means (14) for canceling the offset by successively subtracting the detected offset from the detected output. apparatus. 2. The offset detecting means (13) has a time measuring means (41) for measuring an elapsed time from the start of operation of the motor (3), and the time measuring means (41).
The motor control device according to claim 1, wherein the offset is detected only when the elapsed time measured by the above is compared with a preset predetermined time and the elapsed time is an integral multiple of the predetermined time. 3. The offset canceling means (14) has a time measuring means (41) for measuring an elapsed time from the start of operation of the motor (3), and the time measuring means (41).
3. The motor control device according to claim 1, wherein the offset time is canceled only when the elapsed time measured by the above is compared with a preset predetermined time, and only when the elapsed time becomes an integral multiple of the predetermined time. . 4. The offset detection means (13) has a stable state determination means (51) for determining whether or not the control system of the motor (3) has reached a stable state, and controls the motor (3). The motor control device according to claim 1, wherein the offset is detected only when the system reaches a stable state. 5. The offset canceling means (14) has a stable state judging means (51) for judging whether or not the control system of the motor (3) has reached a stable state, and controls the motor (3). The motor control device according to claim 1, wherein the offset is canceled only when the system reaches a stable state. 6. The offset detection stable switching means having hysteresis before and after switching between the time when the offset is detected and the time when the offset is not detected, according to any one of claims 2 to 5. The described motor control device. 7. The offset canceling stable switching means having hysteresis before and after switching between the offset canceling and the non-cancelling offsets, the offset canceling stable switching means (14) according to claim 2. The described motor control device. 8. The offset canceling means (14) compares the offset value detected by the offset detecting means (13) with a preset predetermined value, and the offset value is less than the predetermined value. The motor control device according to claim 1, wherein the offset is canceled only when the value is also large. 9. The motor control device according to claim 1, wherein the offset canceling means (14) functions in synchronization with the offset detecting means (13).