JP2003018900A - Motor controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the amount of computation to lighten a load on a microcomputer in a motor controller provided with a fundamental current control system and a harmonic current control system. SOLUTION: When the rotational speed of a motor is not less than a predetermined threshold value, correction by dead time compensating means 15 to 19 is not effected but control by harmonic current controlling means 8 to 12 is exercised. When the rotational speed of the motor is higher than the threshold value, control by the harmonic current controlling means 8 to 12 is not exercised but correction by the dead time compensating means 15 to 19 is effected. Thus, the effect of reducing current distortion is obtained to the same level as conventional and yet the amount of computation performed by the microcomputer is significantly reduced. Even as compared with conventional motor controllers which are not provided with a harmonic current reducing function, the amount of computation is slightly higher. Therefore, a load on the microcomputer is reduced, and current distortion can be reduced without use of an expensive microcomputer having high processing capability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AC motor control device.

[0002]

2. Description of the Related Art Generally, in a current control circuit of a three-phase AC motor, a control operation is performed by converting a three-phase AC amount, which is complicated to handle, into a DC amount (for example, Japanese Patent Laid-Open No. 08-331).
885 gazette).

FIG. 6 shows the configuration of a widely used control device for a three-phase AC motor. In this type of control device, for example, when the motor is a permanent magnet synchronous motor, the direction of the magnetic flux by the magnet is set to the d axis, and
The direction orthogonal to the d-axis is set to the q-axis, and the current component is decomposed in the dq-axis coordinate system that rotates in synchronization with the motor rotation. That is, the fundamental wave of the motor is steady in a steady state by decomposing it into a d-axis current that generates a magnetic flux in the d-axis direction and a q-axis current that generates a magnetic flux in the q-axis direction and performing current control for each current component. The current component is converted into a DC amount and controlled, and the current control deviation is reduced.

On the other hand, in AC motors, in order to achieve miniaturization and high efficiency, the adoption of a rotor having an internal embedded magnet structure and a stator having a concentrated winding structure as shown in FIG. 7 is increasing. The former rotor has a structure that can effectively utilize magnet torque and reluctance torque. A motor having a rotor having such a structure has an IPM (Interior Permane)
It is called an nt-magnet motor) motor. On the other hand, the latter stator has a structure capable of greatly reducing the coil end. A motor equipped with the rotor and the stator having the above-mentioned structure is called a concentrated winding IPM motor, and is attracting attention as a motor that can realize high efficiency in a small size.

By the way, the concentrated winding IPM motor described above is a motor suitable for miniaturization and high efficiency, but has a characteristic that the spatial harmonics are large. Since the motor of the concentrated winding structure has a small number of slots per pole, the distribution of the magnetic flux becomes more uneven and the spatial harmonics become larger than those of the motor of the distributed winding structure.

In addition, as shown in FIG. 8, the surface of the rotor is covered with a magnet, and the surface magnet structure has an SPM (Surface Pe) structure.
In the IPM motor with the internal embedded magnet structure shown in FIG. 7, there is a portion where the magnet is embedded and a portion where the magnet is not present, so the change in the magnetic flux is larger than that of the rmanent magnet) motor. Therefore, the spatial harmonic component becomes large.

When the spatial harmonics of the motor are large, the harmonic components of the current flowing through the motor become large, the effect of improving the efficiency of the motor becomes small, and the torque ripple becomes large. Since the components are superposed, there is a problem that the peak value of the current becomes large.

In order to solve such a problem, the applicant of the present invention has proposed a motor control device in Japanese Patent Application No. 2000-356117 for reducing the harmonic current flowing in an AC motor. This device consists of a fundamental wave current control system that controls the motor current in the dq-axis coordinate system that rotates in synchronization with the motor rotation speed, and a harmonic current that controls the motor current in the orthogonal coordinate system that rotates at an integral multiple frequency. A control system is provided to generate a voltage command value to be applied to the motor based on the outputs of the two current control systems. According to this device, the harmonic component current can be greatly reduced.

[0009]

However, in the latter motor control device described above, the fundamental wave current control system that mainly controls the fundamental wave component current and the harmonic current control system that mainly regulates the harmonic current are used. Since it has two current control systems, the control performance of harmonic current is greatly improved compared to the conventional motor control device, but the harmonic current control is newly added to the conventional dq axis fundamental wave current control system. Since the system is added, there is a problem that the amount of calculation processing of the control device is greatly increased.

In recent years, the motor control device has been shifting from an analog type current control circuit to an all digital type current control circuit for performing all arithmetic control by a microcomputer in response to a demand for miniaturization and cost reduction.
In the arithmetic control of the motor by the microcomputer, the heavy load is the current control arithmetic. In the current control calculation, the electric time constant of the motor is small, so that the current control routine is executed at short time intervals, which imposes a heavy load on the microcomputer. The motor control device provided with the fundamental wave current control system and the harmonic current control system described above just increases the calculation load of the microcomputer, and is higher than the microcomputer used in the conventional motor control device. It is necessary to use a microcomputer having an arithmetic processing capability, which causes a problem of increasing the cost of the device.

It is an object of the present invention to reduce the amount of calculation processing and reduce the load on the microcomputer in a motor control device having a fundamental current control system and a harmonic current control system.

[0012]

The present invention will be described with reference to FIG. 2 showing the configuration of an embodiment. (1) The invention of claim 1 synchronizes with the rotation of a three-phase AC motor M. Fundamental wave current control means 1, 2, 2a, 2 for controlling the fundamental wave component of the motor current in a rotating rectangular coordinate system
b, 3, 8 and harmonic current control means 8 to 12 for controlling the harmonic components contained in the motor current in an orthogonal coordinate system that rotates at a frequency that is an integral multiple of the fundamental wave component of the motor current, and the fundamental current control. Voltage command value generation means 3, 13, for adding the outputs of the means 1, 2, 2a, 2b, 3, 8 and the outputs of the harmonic current control means 8 to 12 to generate a three-phase AC voltage command value.
14 and DC power supply voltage 3 depending on the three-phase AC voltage command value
Power conversion means 4 for converting into a three-phase AC voltage and outputting it to the three-phase AC motor M, and a dead for correcting the three-phase AC voltage command value in order to compensate the distortion of the output voltage due to the dead time of the power conversion means 4. A motor controller provided with time compensating means 15 to 19, which is speed detecting means PS, 5 for detecting the rotation speed of the three-phase motor M and three-phase motor M.
If the rotation speed of the three-phase motor M is less than or equal to a predetermined threshold value, the dead-time compensation means 15-19 are not used for correction, and the harmonic current control means 8-12 are used to control the rotation speed of the three-phase motor M. When it is higher than the threshold value, the control selection means 20 to 2 for performing the correction by the dead time compensation means 15 to 19 without performing the control by the harmonic current control means 8 to 12.
2 and, thereby achieving the above object. (2) In the motor control device according to the second aspect, the threshold value used for the control selection determination is provided with hysteresis. (3) In the motor control device according to a third aspect of the present invention, the control selection means 20 to 22 continue the currently selected control for at least the predetermined time even if the control selection determination is made to switch the control again after switching the control. .

In the section of means for solving the above-mentioned problems, the drawings of one embodiment are used for the sake of easy understanding of the description, but the present invention is not limited to this embodiment. .

[0014]

According to the invention of claim 1, when the rotation speed of the motor is equal to or lower than a predetermined threshold value, the harmonic current control means controls without performing the correction by the dead time compensation means. When the rotation speed of the motor is higher than the threshold value, the correction by the dead time compensation means is performed without performing the control by the harmonic current control means. While getting
The calculation processing amount of the microcomputer can be significantly reduced, and the increase in the calculation processing amount is small even when compared with the conventional motor control device that does not have the harmonic current reduction function. Therefore, the load on the microcomputer can be reduced, and the current distortion can be reduced without using an expensive microcomputer having a high arithmetic processing capability. (2) According to the invention of claim 2, since the threshold value used for the control selection determination is provided with hysteresis, it is possible to prevent frequent switching between the harmonic current control and the dead time compensation control, and it is possible to prevent the control selection determination. It is possible to prevent frequent occurrence of transient current distortion due to frequent switching of control in the vicinity of the threshold rotation speed. (3) According to the invention of claim 3, even if the control selection judgment is made to switch the control again after switching the control, the control which is currently selected is continued for at least a predetermined time, so that the control is frequently performed. Can be prevented from occurring, and frequent occurrence of transient current distortion due to frequent switching of control in the vicinity of the rotation speed of the control selection determination threshold value can be prevented.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION << First Embodiment of the Invention >> FIG.
2 shows the configuration of the first embodiment. The motor control device according to the present embodiment drives and controls a three-phase AC motor by vector control, includes a fundamental current control system and a harmonic current control system, and reduces the harmonic current.

First, in FIG. 1, the fundamental wave current control system is
Three-phase AC currents iu, iv, i flowing in the three-phase AC motor M
The motor M is converted by converting w into a d-axis current component and a q-axis current component of a rectangular coordinate system (hereinafter referred to as dq-axis coordinate system) that rotates in synchronization with the rotation of the motor, and controlling those dq-axis currents. It is a circuit that mainly controls the fundamental wave component of the three-phase alternating currents iu, iv, and iw flowing in the.

On the other hand, the harmonic current control system is an orthogonal coordinate system (hereinafter, referred to as a coordinate system which rotates at the frequency of a harmonic component of a predetermined order generated when the motor currents iu, iv, iw are controlled only by the fundamental current control system. , Harmonic coordinate system or dhqh axis coordinate system), in other words, motor currents iu, iv, iw
Is a circuit for controlling the harmonic components contained in the motor currents iu, iv, and iw in the harmonic coordinate system that rotates at a frequency that is an integral multiple of the frequency of the fundamental wave component.

The fundamental current control system comprises a torque control circuit 1,
A fundamental wave current control circuit (dq axis current control circuit) 2, subtractors 2a and 2b, a dq / 3-phase conversion circuit 3, and a 3-phase / dq conversion circuit 8 are provided. The configuration of this fundamental wave current control system is shown in FIG.
It is similar to the conventional motor control device shown in FIG.

The torque control circuit 1 uses the torque command value Te ^*
Based on the motor rotation speed ωe, the command value id ^* of the d-axis current and the command value iq ^* of the q-axis current are calculated from the current command value table. The fundamental wave current control circuit (dq-axis current control circuit) 2 is a fundamental wave of the d-axis and the q-axis for making the actual currents id and iq of the d-axis and the q-axis coincide with the current command values id ^* and iq ^* , respectively. The voltage command values vd1 ^* and vq1 ^* are calculated. That is, the subtractors 2a and 2b subtract the actual currents id and iq from the d-axis and q-axis current command values id ^* and iq ^* to obtain the current deviation, and the operational amplifier built in the fundamental wave current control circuit 2 The fundamental wave voltage command values vd1 ^* and vq1 ^* on the d-axis and the q-axis for making the current deviation zero are calculated.

The dq / 3-phase conversion circuit 3 converts the dq-axis voltage command values vd ^* , vq ^* into three-phase AC voltage command values vu_nc ^* , vv_nc ^* , vw_nc ^* based on the fundamental wave current phase θe. The adders 15 to 17 are three-phase AC voltage command values vu_n
Dead time compensation voltage vu_ for c ^* , vv_nc ^* , vw_nc ^*
By adding c, vv_c, and vw_c, the voltage command values vu ^* , vv ^* , and vw ^* that compensate for the voltage distortion caused by the so-called dead time of the power conversion device 4 are calculated.

The dq / 3-phase conversion circuit 18 converts the dq-axis fundamental wave current command values id ^* , iq ^* into the 3-phase AC current command values iu ^* , iv.
^* , Iw ^* converted to dead time compensation amount calculation circuit 19
Determines the polarity of the current based on the three-phase AC current command values iu ^* , iv ^* , iw ^* , and calculates the dead time compensation voltages vu_c, vv_c, vw_c according to the polarity.

The power converter (inverter) 4 is an IG
A switching element such as BT switches the DC voltage of a DC power supply (not shown) such as a battery according to the three-phase AC voltage command values vu ^* , vv ^* , vw ^* to generate three-phase AC voltages VU, VV, VW. Applied to the three-phase AC motor M.

The encoder PS is a three-phase AC motor M
And detects the rotational position θm of the motor M. The phase / speed calculation circuit 5 uses the rotational position signal θm from the encoder PS to determine the rotational speed ωe of the motor M, the phase θe of the fundamental wave component of the magnetic flux, and the phase θe of the harmonic component of the magnetic flux.
computes h

The current sensors 6 and 7 detect the U-phase and V-phase actual currents iu and iv of the three-phase AC motor M. Three
The phase / dq conversion circuit 8 uses the fundamental wave current phase θe to calculate the actual currents iu, iv, iw (= −iu− of the three-phase AC motor M).
iv) is converted into d-axis and q-axis real currents id and iq.

On the other hand, the harmonic current control system includes a three-phase / dq conversion circuit 8, a high-pass filter 9, a dq / dhqh conversion circuit 10, a harmonic current control circuit (dhqh axis current control circuit) 11 and a dhqh / dq conversion. The circuit 12 is provided. The high-pass filter 9 has a dq-axis real current id,
iq is filtered to extract high frequency components.
The dq / dhqh conversion circuit 10 is an orthogonal coordinate system (harmonic coordinate system) that rotates at a frequency of a harmonic component of a predetermined order that occurs when the motor currents iu, iv, and iw are controlled only by the fundamental wave current control system described above. ) Dhqh, and the harmonic components of the real currents id and iq of the dq axes are the real currents i of the harmonic coordinate system dhqh.
Convert to dh, iqh.

The harmonic current control circuit (dhqh-axis current control circuit) 11 controls the dh-axis and the qh-axis to match the actual currents idh and iqh of the dh-axis and the qh-axis with the current command values idh ^* and iqh ^* , respectively. Calculate the harmonic voltage command values vdh ^* and vqh ^* . Here, the harmonic current command values idh ^* and iqh ^* are both 0, and the harmonic current control unit 11 controls the motor current iu,
The harmonic current is controlled so that the harmonic component of the predetermined order among the harmonic components included in iv and iw becomes zero.

The dhqh / dq conversion circuit 12 has a dh axis and a qh.
Axis harmonic voltage command value vdh^*, Vqh ^*Is the height of d-axis and q-axis
Harmonic voltage command value vd2^*, Vq2^*Convert to. Adder 1
3 and 14 are the fundamental wave voltage generated by the fundamental wave current control system.
Command value vd1^*, Vq1^*And is generated by the harmonic current control system
Harmonic voltage command value vd2^*, Vq2^*And add and final
D-axis voltage command value vd^*(= Vd1^*+ Vd2^*) And q-axis
Pressure command value vq^*(= Vq1^*＋ vq2^*) Is calculated.

From the motor control device of the first embodiment shown in FIG. 1, a high pass filter 9, a dq / dhqh conversion circuit 10, a harmonic current control circuit 11, a dhqh / dq conversion circuit 12 and adders 13, 14 are provided. Excluding the above, the current control system of the conventional motor control device shown in FIG. 6, that is, the fundamental wave current control system for controlling the motor current by the dq axis coordinate system that rotates in synchronization with the rotation of the motor is obtained. It is difficult to secure the followability of the actual current to the current command value up to the frequency band of the harmonic current caused by the spatial harmonics of the motor by the current control calculation using only the dq axis coordinate system. The efficiency improvement effect of the IPM motor becomes smaller,
There is a problem that the torque ripple becomes large or the peak value of the current becomes large.

This problem will be described in detail. Since the dq-axis coordinate system is a coordinate system that rotates in synchronization with the rotation of the motor, the fundamental wave current of the motor has a DC amount in the dq-axis coordinate system. On the other hand, if the angular frequency of the harmonic current is ωeh and the angular velocity of the motor, that is, the angular frequency of the fundamental wave current is ωe, the angular frequency ωeh_d of the harmonic current in the dq axis coordinate system.
q becomes (ωeh-ωe), and the harmonic component of the motor current does not become a direct current amount even in the dq axis coordinate system. Therefore, when the rotation speed of the motor increases and the frequency of the motor current increases, the followability of the fundamental wave component of the motor current is good, but the harmonic component increases in frequency according to the rotation speed of the motor, and The actual current cannot follow the command value.

Therefore, in the first embodiment, as shown in FIG.
By using the harmonic current control systems 8 to 12 and the adders 13 and 14, the current followability of the harmonic component of the predetermined order is improved and the harmonic current of the predetermined order is reduced. In order to make the explanation easy to understand, it is assumed that the kth harmonic component is reduced in the first embodiment. The real currents id and iq of the d-axis and the q-axis output from the three-phase / dq conversion circuit 8 have a fundamental wave component of a DC amount but a harmonic component of an AC amount. Thus, only high frequency components are extracted from the real currents id and iq. θeh is the phase of the kth harmonic current
Then, when the k-th order harmonic components included in the dq-axis currents id and iq are converted into real currents idh and iqh in the dhqh-axis coordinate system which rotates at the phase θeh by the dq / dhqh conversion circuit 10, these become direct current amounts. . Therefore, if the current control calculation is performed in the dhqh axis coordinate system, the current command value idh of the kth harmonic current is
^The ability to follow ^* , iqh ^* (= 0) is greatly improved. As a result, the harmonic currents contained in the motor currents iu, iv, iw can be reduced. In particular, the k-th order harmonic current and its vicinity can be significantly reduced.

FIG. 9 shows the waveform of the U-phase current with respect to the U-phase current command value when the concentrated winding IPM motor having large spatial harmonic components is driven by the conventional motor control device. Further, FIG. 1 shows the waveform of the U-phase current with respect to the U-phase current command value when driven by the motor control device of the first embodiment.
It shows in 0. When driven by a conventional motor controller,
As is clear from FIG. 9, the motor current contains large harmonic components. On the other hand, when driven by the motor control device of the first embodiment, the harmonic components are greatly reduced as is apparent from FIG. In this way, it is possible to reduce the harmonic component centered on the predetermined order included in the motor current.

Next, with reference to FIG. 2, a circuit added to the first embodiment in order to reduce the current control calculation amount without using an expensive microcomputer having a high calculation processing capability will be described. In FIG. 2, control blocks having the same functions as those in FIG. 1 are designated by the same reference numerals, and different points will be mainly described.

As described above, in order to reduce the harmonic components contained in the three-phase AC motor M, the harmonic current control system is added to the fundamental current control system, so that only the conventional fundamental current control system is used. Compared with a motor control device equipped with, the computational processing amount of the microcomputer has increased significantly.
In the first embodiment, in order to reduce the amount of calculation processing, reduce the load on the microcomputer, and shorten the calculation processing time, the DT (Dead Time) compensation / harmonic control selection circuit 20 and the input switching are selected. Switches 21 and 22 are provided.

The input selector switch 21 controls the dq axis voltage command values vd2 ^* , vq2 ^* (dh) calculated by the harmonic current control system.
The output of the qh / dq conversion circuit 12) and "0" are switched. The input changeover switch 22 is provided with the dead time compensation voltages vu_c, vv calculated by the dead time compensation amount calculation circuit 19.
_c, vw_c and "0" are switched. These input changeover switches 21 and 22 are changed over by the DT compensation / harmonic control selection circuit 20.

The switching operation of the input changeover switches 21 and 22 by the DT compensation / harmonic control selection circuit 20 will be described in detail. First, referring to FIG. 3, the dq / 3-phase conversion circuit 1
8 and dead time compensation amount calculation circuit 19 will be described. In the power conversion device 4, a square-wave voltage distortion as shown in FIG. 3 occurs due to the dead time depending on the polarity of the current. That is, when the polarity of the current is positive (the direction from the power converter 4 to the motor M), negative voltage distortion occurs and the actual output voltage becomes a value lower than the voltage command value. On the contrary, when the current polarity is negative, positive voltage distortion occurs. Since such a square wave disturbance is applied to the motor control system, the motor current is distorted. Therefore, the voltage distortion due to the dead time can be compensated by adding the compensation voltage vu_c as shown in FIG. 3 to the three-phase AC voltage command value vu_nc ^* according to the polarity of the current. In FIG. 3, the U phase will be described as an example, but the same applies to the V phase and the W phase.

A harmonic current composed of a three-phase / dq conversion circuit 8, a high-pass filter 9, a dq / dhqh conversion circuit 10, a harmonic current control circuit (dhqh axis current control circuit) 11, and a dhqh / dq conversion circuit 12. The control system has a large effect of compensating for voltage distortion due to dead time, in addition to the effect of reducing harmonic current due to spatial harmonics. Both the spatial harmonic components of the motor and the voltage distortion due to dead time are disturbances including harmonic components for the motor control device. By the way, the frequency components of the voltage (line-to-line) distortion due to the dead time described above are, in descending order, the fundamental wave component, the 5th component, the 7th component ,. On the other hand, the spatial harmonic components of the motor are also large in the 5th, 7th, ... Therefore, if the control is performed by this harmonic current control system, the harmonic current component caused by either of them is reduced. However, since this harmonic current control system controls the harmonic components by feedback, its effect becomes small in an operating region where the motor rotation speed is high, in other words, in a region where the motor current frequency is high.

Therefore, in the first embodiment, of the harmonic current control and the dead time compensation control, the most effective control is selected based on the motor rotation speed. That is, in the low rotation speed region of the motor, the harmonic current control that achieves the necessary and sufficient current distortion reduction effect is performed, and the dead time compensation control is not performed. On the other hand, in the high rotation speed region, dead time compensation control is performed, which has a great effect even in the high rotation speed region, and harmonic current control is not performed.

The DT compensation / harmonic control selection circuit 20 selects either the harmonic current control or the dead time compensation control according to the rotation speed ωe of the motor M, and the selection flag
Output f_cont. In the low rotation speed region where the motor rotation speed is equal to or lower than a predetermined threshold value, the harmonic current control is selected and the control selection flag f_cont = 1 is output. According to the control selection flag f_cont = 1, the input selector switch 2
1 is the output of the harmonic current control system (dhqh / dq conversion circuit 1
2 output), and the input changeover switch 22 selects “0” input. When the harmonic current control is selected, all the arithmetic processing relating to the dead time compensation control is unnecessary and is not executed. As a result, in the low rotation speed region of the motor, the current distortion is sufficiently reduced by the harmonic current control, and the dead time compensation control that was conventionally executed is not performed, so the amount of calculation processing is reduced accordingly. This reduces the load on the microcomputer. In the low rotation speed region of the motor, the increase in the amount of calculation processing can be suppressed to a minimum even when compared with the conventional motor control device that does not have the function of reducing the harmonic current for spatial harmonics.

On the other hand, in the high rotation speed region where the motor rotation speed is higher than the above threshold value, the dead time compensation control is selected and the control selection flag f_cont = 0 is output. According to the control selection flag f_cont = 0, the input changeover switch 2
1 selects the "0" input, and the input changeover switch 22 selects the output of the dead time compensation amount calculation circuit 19. When the dead time compensation control is selected, all arithmetic processing relating to the harmonic current control is unnecessary and is not executed. As a result, in the high rotation speed region of the motor, the current distortion is reduced by the dead time compensation control, and the harmonic current control that was conventionally executed is not performed, so the amount of calculation processing is reduced accordingly. The load on the microcomputer is reduced. In the high rotation speed range of the motor, the increase in the amount of calculation is small compared to the conventional motor control device that does not have the function of reducing the harmonic current for the spatial harmonics.

As described above, when the rotation speed of the motor is equal to or lower than the predetermined threshold value, the harmonic current control is performed without performing the dead time compensation control, and the rotation speed of the motor is lower than the threshold value. When the value is high, by performing dead time compensation control without performing harmonic current control, it is possible to obtain the same level of current distortion reduction effect as before, while significantly reducing the amount of computational processing of the microcomputer. Even when compared with the conventional motor control device that does not have the wave current reduction function, the amount of calculation processing is slightly increased. Therefore, the load on the microcomputer can be reduced, and the current distortion can be reduced without using an expensive microcomputer having a high arithmetic processing capability.

<< Second Embodiment of the Invention >> FIG.
Another configuration example of the DT compensation / harmonic control selection circuit 20 shown in FIG. The DT compensation / harmonic control selection circuit 20 of the first embodiment is configured to switch the harmonic current control and the dead time compensation control by comparing the motor rotation speed ωe with a predetermined threshold value. D of this second embodiment
The T compensation / harmonic control selection circuit 20A is provided with hysteresis in the motor rotation speed used for control selection judgment, and frequent occurrence of transient current distortion due to frequent switching of control near the rotation speed of the control switching condition. To prevent.

The rotation speeds at which the control selection flag f_cont = 1 → 0, that is, the rotation speeds at which the harmonic current control is switched to the dead time compensation control are ωlhp and ωlhn, respectively. Further, the rotation speed at which the control selection flag f_cont = 0 → 1 is set, that is, the rotation speed at which the dead time compensation control is switched to the harmonic current control is positive and negative ωhlp, respectively.
It is ωhln. The rotation speeds of these are ωhlp <ωlh
By setting p and ωlhn <ωhln, and providing a hysteresis in the motor rotation speed of the control switching condition, it is possible to prevent frequent switching between harmonic current control and dead time compensation control, and control selection Frequent occurrence of transient current distortion due to frequent switching of control in the vicinity of the rotation speed of the determination threshold value can be prevented.

<< Third Embodiment of the Invention >> FIG.
Another configuration example of the DT compensation / harmonic control selection circuit 20 shown in FIG. The DT compensation / harmonic control selection circuit 20B of the third embodiment is configured by a software form of a microcomputer. In the DT compensation / harmonic control selection circuit 20B, even if the control selection determination condition based on the motor rotation speed is satisfied, the current control is continued for a predetermined time and then the control is switched.

The DT compensation / harmonic control selection circuit 20B is
The control selection program shown in FIG. 5 is executed every predetermined time. In step 1, the rotation speed ωe of the motor M is fetched, and in subsequent steps 2 and 6, the motor rotation speed ωe
Is compared with the positive and negative thresholds ωhp and ωhn. If the motor rotation speed ωe is less than ωhn, proceed to step 3,
It is confirmed whether or not the value of the timer time1 which counts the elapsed time after entering the rotation speed range (ωe <ωhn) is equal to or longer than the predetermined time TIME. The value of timer time1 is the predetermined time TI
In case of ME or more, go to step 4 and count the elapsed time after entering another rotation speed range, timer2,
Clear time3. Then, in step 5, the control selection flag f_cont is set to 0 to select the dead time compensation control.

If the timer time1 is less than the predetermined time TIME in step 3, the process proceeds to step 13 and the timer ti
Count up me1. By the above processing, even if the condition for switching to the dead time compensation control is satisfied when the motor rotation speed ωe becomes less than the threshold value ωhn,
TIME continues harmonic current control, and then switches to dead time compensation control.

When the motor rotation speed ωe is equal to or more than the threshold value ωhn and is equal to or less than the threshold value ωhp, the process proceeds to step 7 and the timer time2 for counting the elapsed time after entering this rotation speed range (ωhn ≦ ωe ≦ ωhp) Check whether the value of is greater than or equal to TIME for the specified time. The value of timer time2 is the predetermined time TI
If it is equal to or more than ME, go to step 8 and count the elapsed time since entering the other rotation speed range, timer1
Clear time3. Then, in step 9, the control selection flag f_cont is set to 1 to select the harmonic current control.

If the timer time2 is less than the predetermined time TIME in step 7, the process proceeds to step 14 and the timer ti
Count up me2. By the above process, even if the condition for switching to the harmonic current control is satisfied when the motor rotation speed ωe falls within the range of ωhn ≤ ωe ≤ ωhp, the predetermined time TI
The ME continues the dead time compensation control and then switches to the harmonic current control.

When the motor rotation speed ωe exceeds the threshold value ωh, the routine proceeds to step 10, where this rotation speed range (ωe
> Ωhp) Check if the value of timer time3 that counts the elapsed time after entering is greater than or equal to the predetermined time TIME. When the value of the timer time3 is equal to or longer than the predetermined time TIME, the process proceeds to step 11, and the timers time1 and time2 for counting the elapsed time after entering the other rotation speed range are cleared. Then, in step 12, the control selection flag f_cont is set to 0.
Set and select the dead time compensation control.

If the timer time3 is less than the predetermined time TIME in step 10, the process proceeds to step 15 and the timer
Count up time3. By the above processing, even if the condition for switching to the dead time compensation control is satisfied when the motor rotation speed ωe exceeds the threshold value ωhp, the predetermined time TI
The ME continues harmonic current control and then switches to dead time compensation control.

According to the third embodiment, the harmonic current control or the dead time compensation control is continued for at least the predetermined time TIME or more, and frequent switching of the control can be prevented. It is possible to prevent frequent occurrence of transient current distortion due to frequent switching of control in the vicinity of the rotation speed of the control selection determination threshold value.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a first embodiment.

FIG. 2 is a diagram showing a configuration of a first embodiment.

FIG. 3 is a diagram illustrating output voltage distortion due to dead time of the power conversion device.

FIG. 4 is a diagram showing a configuration of a DT compensation / harmonic control selection circuit according to a second embodiment.

FIG. 5 is a flowchart showing an operation of a DT compensation / harmonic control selection circuit according to a third embodiment.

FIG. 6 is a diagram showing a configuration of a conventional motor control device including only a fundamental wave current control system.

FIG. 7 is a cross-sectional view of a rotor having an internal embedded magnet structure.

FIG. 8 is a sectional view of a rotor having a surface magnet structure.

FIG. 9 is a diagram showing a current control result by a conventional motor control device.

FIG. 10 is a diagram showing a result of current control according to the first embodiment.

[Explanation of symbols]

1 Torque control circuit 2 Fundamental wave current control circuit 3 dq / 3-phase conversion circuit 4 Power converter 5 Phase / speed calculation circuit 6,7 Current sensor 8 3 phase / dq conversion circuit 9 High-pass filter 10 dq / dhqh conversion circuit 11 Harmonic current control circuit 12 dhqh / dq conversion circuit 13 to 17 adder 18 dq / 3-phase conversion circuit 19 Dead time compensation amount calculation circuit 20,20A DT compensation / harmonic control selection circuit 21,22 Input selector switch

Continued front page    F term (reference) 5H560 BB04 DA14 DA18 DB14 DC01                       DC12 EB01 GG04 JJ02 RR01                       RR06 SS06 UA06 XA02 XA04                       XA13 XA15                 5H576 BB04 CC05 DD02 DD07 EE01                       EE02 GG06 HA04 HB01 JJ03                       JJ13 KK05 LL14 LL22 MM02                       MM15

Claims (3)

[Claims] 1. A fundamental wave current control means for controlling a fundamental wave component of a motor current in a Cartesian coordinate system that rotates in synchronization with rotation of a three-phase AC motor, and a revolution at an integral multiple frequency of the fundamental wave component of a motor current. A three-phase AC voltage command by adding the output of the fundamental wave current control means and the output of the harmonic current control means to the harmonic current control means for controlling the harmonic component contained in the motor current in the orthogonal coordinate system Voltage command value generation means for generating a value, power conversion means for converting a DC power supply voltage into a three-phase AC voltage according to the three-phase AC voltage command value and outputting the three-phase AC motor to the three-phase AC motor, and the power conversion means And a dead time compensating means for compensating the three-phase AC voltage command value for compensating the distortion of the output voltage caused by the dead time of the three-phase motor. A speed detecting means for detecting, said when the rotational speed of the three-phase motor is below the threshold a predetermined performs control by the higher harmonic current control means without correction by the dead time compensation means, the 3
When the rotation speed of the phase motor is higher than the threshold value,
A motor control device comprising: a control selection unit that performs correction by the dead time compensation unit without performing control by the harmonic current control unit. 2. The motor control device according to claim 1, wherein the threshold value used for the control selection determination is provided with hysteresis. 3. The motor control device according to claim 1, wherein the control selection means is currently selected for at least a predetermined time even if a control selection determination is made to switch the control again after switching the control. A motor control device characterized by continuing the control being performed.