JP2002218782A - Motor drive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor driver which can drive a synchronous motor with high efficiency. SOLUTION: In the driver of an IPM motor 1, a target waveform computer 22 computes the target waveform for driving the motor 1 with high efficiency, based on the torque waveform per phase of the coil, read out of a coil one-phase torque waveform storage 21. A coil voltage controller 28, etc., controls the coil voltage, so that the detected current waveform and the target current waveform conform to each other. Accordingly, this driver can efficiently drive the IPM motor 1 with which the torque waveform pulsates.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor driving device, and more particularly to a motor driving device for driving a synchronous motor having a rotor on which a permanent magnet is mounted.

[0002]

2. Description of the Related Art In recent years, environmental issues have become a social topic, and energy saving has become an important concern. Especially in the field of motors, from the viewpoint of energy saving,
There is a strong need for a motor with high efficiency and high output. Typical examples of the conventional motor include a dielectric motor and an SPM (Surface Permanent Magnet) motor in which a magnet is mounted on the rotor surface, and both are excellent in mass productivity. On the other hand, various motors with structures different from the conventional one have been developed. Among them, by embedding permanent magnets inside the rotor and using reluctance torque in addition to framing torque,
IPM (Interior Permanent Magne) with even higher efficiency
t) Motors are attracting attention (see FIG. 2).

In this IPM motor, a permanent magnet 32 is embedded in a rotor 31 made of an iron core of a high magnetic permeability material or a laminated silicon steel plate. With this configuration, the inductance Ld in the d-axis direction, which is the direction connecting the center of the permanent magnet 32 and the center of the rotor 31, and d
There is a difference between the inductance and the inductance Lq in the q-axis direction, which is a direction rotated by an electrical angle of 90 ° with respect to the axis.
, A reluctance torque Tr is generated in addition to the framing torque Tm. These relationships are analyzed in "Rotator requiring reluctance torque" (Matsui Nobuyuki et al., T.EE Japan, Vol. 114-D, No. 9, 1994). According to this document, the relationship between the Fleming torque Tm and the reluctance torque Tr is expressed by the following equation (1).
Meet.

[0004]

(Equation 1)

Where Pn is the number of pole pairs, φa is the flux linkage,
Ld is the inductance in the d-axis direction, Lq is the inductance in the q-axis direction, id is the current in the d-axis direction, iq is the current in the q-axis direction, β is the current phase, and ia is the magnitude of the current vector.

FIG. 13 is a diagram showing changes in the fleming torque Tm, the reluctance torque Tr, and the total torque Td when the current phase β is changed. As shown in FIG. 13, the framing torque Tm is such that the current phase β is 90
It shows the maximum value at the time of °, becomes smaller as it leaves 90 °, and becomes zero at 180 °. On the other hand, the reluctance torque Tr shows the maximum value when the current phase β is 135 °. Therefore, the total torque Tt, which is the sum of the reluctance torque Tr and the framing torque Tm, changes depending on the respective torque ratios, but the current phase β is 115 °.
It shows the maximum value near. Therefore, the IPM motor that effectively uses the reluctance torque Tr can output a higher torque at the same current than the SPM motor that operates using only the framing torque Tm.

As a factor for determining the magnitude of the motor torque, a motor drive control method is important. As a conventional current driving method, 120 ° rectangular wave driving is generally used. This 120 ° rectangular wave driving method is a three-phase U,
A current is applied to the two-phase coil in V and W, and 120 °
In this method, the current is connected every time to control the inverter so that the current becomes DC. In the case of the 120 ° rectangular wave drive, there is an energization suspension period for the coils of each phase,
Rotation of the rotor is controlled by detecting an induced voltage generated in the stator coil due to rotation of the rotor magnet during the power suspension period. I using the reluctance torque Tr described above
In a PM motor, energization timing is important for maximizing torque. Therefore, for the IPM motor, the rotor phase is calculated by detecting the induced voltage during the energization suspension period by performing the 120 ° rectangular wave drive.

On the other hand, as a motor drive control method for improving the motor efficiency, there is a 180 ° sine wave drive system in which the energization width is set to 180 ° in electrical angle. "Brushless D
The C motor drive control method, its device, and electric equipment (International Publication No. WO95-27328) provide a motor with a conduction angle of 180 electrical degrees for a motor embedded in a permanent magnet.
And a method of detecting a magnetic pole position based on a difference between a first center point potential of a motor coil and a second center point potential of a bridge circuit electrically parallel to the coil.

Here, the brushless DC motor control device described in this document will be described. FIG.
FIG. 1 is a diagram schematically showing a configuration of a motor control device described in this document. In FIG. 14, three pairs of switching transistors 72 to 77 and three pairs of diodes 78 to 83 constitute an inverter 84 between terminals of a DC power supply 71, and each pair of switching transistors 72, 73, 74
And 75, and the connection point voltage between 76 and 77 are brushless DC
The stator windings 86u, 8 of each phase of the Y-connected motor 85
6v and 86w.

In addition, each pair of switching transistors 7
2, 73, 74, 75, 76 and 77 are also applied to the Y-connected resistance elements 87u, 87v, 87w, respectively. Further, the stator windings 86u, 86
The voltage at the neutral point 86d of v, 86w is supplied to the inverting input terminal of the operational amplifier 89 via the resistance element 88, and the voltage at the neutral point 87d of the Y-connected resistance elements 87u, 87v, 87w is converted to the operational amplifier 89. Is supplied to the non-inverting input terminal of A differential amplifier 91 is configured by connecting a resistance element 90 between the output terminal and the inverting input terminal of the operational amplifier 89.

Here, the stator windings 86u, 86v, 86
The voltage En0 at the neutral point 86d of w is the sum of the output waveform of the inverter 84 and the 3nth harmonic component (n is an integer) included in the motor induced voltage waveform. On the other hand, the voltage at the neutral point 87d of the Y-connected resistance elements 87u, 87v, 87w is determined only by the output waveform of the inverter 84. Therefore, by obtaining the difference between the voltage En0 at the neutral point 86d and the voltage at the neutral point 87d, it is possible to extract a 3 ng harmonic component included in the motor induced voltage waveform.

The output signal from the differential amplifier 91 is
The signal is converted into a magnetic pole position detection signal by an integrator 94 including a capacitor 2 and a capacitor 93 and a zero-cross comparator 96 including an operational amplifier 95. Microprocessor 97
Is a base drive circuit 98 based on the magnetic pole position detection signal.
Through the switching transistor 7 of the inverter 84
2 to 77 are controlled. As a result, a 180 ° driving method that is more efficient than the 120 ° rectangular wave driving method is realized.

[0013]

However, in an actual motor, a higher-order harmonic component is superimposed on a spatial magnetic flux density in a gap portion contributing to torque, so that the torque waveform is not affected by the harmonic component. As a result, a waveform having irregularities is obtained. This is conceptually shown in FIG. In FIG.
The horizontal axis indicates the rotation angle, the vertical axis indicates the dimensionless values of the torque and the current, the solid curve indicates the torque waveform corresponding to the coil 1 when the IPM motor 1 is driven by the sine wave, and the dashed-dotted curve. Shows a drive current waveform corresponding to the coil 1 in the 180 ° sine wave drive. As shown in FIG. 15, higher harmonic components are superimposed on the actual torque waveform,
There are irregularities compared to a sine wave. However, when the driving current waveform is a sine wave, a large current is applied to a point having a small uneven torque, that is, a concave point, so that torque cannot be generated effectively, resulting in a problem that efficiency is deteriorated.

[0014] Therefore, a main object of the present invention is to provide a motor driving device capable of driving a synchronous motor with high efficiency.

[0015]

SUMMARY OF THE INVENTION A motor driving device according to the present invention is a motor driving device for driving a synchronous motor having a rotor on which a permanent magnet is mounted, and supplies a driving current to a coil of the synchronous motor. Controllable power supply, current detecting means for detecting a current flowing through a coil of the synchronous motor, motor information generating means for generating motor information related to the rotational torque of the synchronous motor, and motor information generating means A current waveform generating means for generating a target current waveform for driving a synchronous motor with high efficiency based on the motor information from the CPU, a current waveform detected by the current detecting means, and a current generated by the current waveform generating means. Control means for controlling the output of the power supply so that the waveforms coincide with each other.

Preferably, the motor information generating means includes a torque waveform storing means in which a torque waveform corresponding to the coil 1 of the synchronous motor is stored in advance, and the motor information is a torque waveform read from the torque waveform storing means. .

Preferably, the torque waveform is obtained by connecting the rotating shaft of the synchronous motor and the rotating shaft of the load motor by a torque detecting device, driving the synchronous motor, and detecting the torque by the torque detecting device.

[0018] Preferably, the motor information generating means includes:
The apparatus includes voltage waveform detection means for detecting a back electromotive voltage waveform of the coil of the synchronous motor, and the motor information is a back electromotive voltage waveform detected by the voltage waveform detection means.

Preferably, the apparatus further comprises phase difference detecting means for detecting a phase difference between the output voltage of the power supply and the current detected by the current detecting means, and the control means further includes a phase difference detecting means. The output of the power supply is controlled so that the phase difference becomes a desired value.

[0020] Preferably, the apparatus further comprises rotation number detecting means for detecting the rotation number of the synchronous motor, and the control means further comprises: a rotation number detecting means for adjusting the rotation number detected by the rotation number detecting means to a desired value. Performs power supply output control.

Preferably, the motor information generating means includes:
The motor information includes torque waveform storage means in which the relationship between the torque waveform corresponding to the coil 1 of the synchronous motor and the rotation speed of the synchronous motor is stored in advance, and the motor information is stored in a torque waveform according to the rotation speed detected by the rotation speed detection means. 6 is a torque waveform read from a storage unit.

Preferably, the control means further comprises a driving method storing means in which a relationship between the number of rotations of the synchronous motor and a driving method for driving the synchronous motor with high efficiency at the number of rotations is stored in advance. Further, the output of the power supply is controlled by the driving method read from the driving method storing means in accordance with the number of rotations detected by the rotation number detecting means.

Preferably, the apparatus further comprises output calculating means for calculating an output of the synchronous motor based on the number of revolutions detected by the number of revolutions detecting means, wherein the motor information generating means comprises a torque equivalent to the coil 1 of the synchronous motor. A torque waveform storage unit in which a relationship between the waveform and the output of the synchronous motor is stored in advance, and the motor information is a torque waveform read from the torque waveform storage unit in accordance with the output of the synchronous motor calculated by the output calculation unit. is there.

Preferably, the apparatus further comprises a driving method storing means in which a relationship between an output of the synchronous motor and a driving method for driving the synchronous motor with high efficiency at the output is stored in advance, and the control means further comprises: In accordance with the output of the synchronous motor calculated by the output calculation means, the output of the power supply is controlled by the driving method read from the driving method storage means.

Preferably, the synchronous motor includes a three-phase coil, and a neutral point of the three-phase coil is grounded.

Preferably, the synchronous motor is an IPM motor having a rotor having a permanent magnet built therein.

[0027]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the drawings, the same or corresponding portions have the same reference characters allotted, and description thereof will not be repeated.

[First Embodiment] FIG. 1 is a circuit block diagram showing a configuration of a driving device of IPM motor 1 according to a first embodiment of the present invention. In FIG. 1, the motor driving device includes an AC power supply 2, an AC / DC converter circuit 3 for converting an output voltage of the AC power supply 2 into a DC voltage, and three pairs of I / O converters.
GBT (Insulated Gate Bipolar Transistor) 5-1
AC / D including 0 and 3 pairs of diodes 11 to 16
3 based on the DC voltage generated by the C converter circuit 3.
An inverter circuit 4 that generates a phase AC voltage and supplies the three-phase coil to the IPM motor 1; a current sensor 17 for detecting a current flowing through one coil of the IPM motor 1; and three pairs of IGBTs 5 to 10 of the inverter circuit 4. And a control unit 20 for controlling the base voltage of the power supply.

The control unit 20 includes a coil one-phase torque waveform storage unit 21, a target current waveform calculation unit 22, and a coil current detection unit 2.
3. Detection / target current comparison unit 24, rotation speed / position calculation unit 2
5, a target rotation speed storage unit 26, a rotation speed comparison unit 27, a coil voltage control unit 28, and a PWM generation / phase distribution unit 29.

The coil one-phase torque waveform storage 21 stores I
A torque waveform corresponding to the coil 1 is stored as information related to the rotation torque of the PM motor 1. The target current waveform calculation unit 22 calculates an ideal coil current waveform for driving the IPM motor 1 with maximum efficiency based on the torque waveform read from the coil one-phase torque waveform storage unit 21. The coil current detection unit 23 detects a coil current at the time of driving the IPM motor 1 via the current sensor 17. The detection / target current comparison unit 24 compares the target current waveform calculated by the target current waveform calculation unit 22 with the coil current waveform during driving detected by the coil current detection unit 23.

The rotation speed / position calculation unit 25 includes the current sensor 1
Based on the coil current information output from 7, the rotation number and the rotation position of the IPM motor 1 are detected or calculated.
The target rotation speed storage unit 26 stores a target rotation speed of the IPM motor 1. The rotation speed comparison unit 27 compares the rotation speed and the rotation position detected or calculated by the rotation speed / position calculation unit 25 with the target rotation speed read from the target rotation speed storage unit 26. The coil voltage control unit 28 has a target rotation speed and a target current waveform based on the target rotation speed information output from the rotation speed comparison unit 27 and the target current information output from the detection / target current comparison unit 24. The error correction voltage and the energized phase correction information are supplied to the PWM generation / phase distribution unit 29. The PWM generation / phase distribution unit 29 provides a PWM waveform signal to the bases of the switching transistors 5 to 10 of the inverter circuit 4 based on the error correction voltage and the energization phase correction information provided from the coil voltage control unit 28.

The control unit 20 is constituted by a microcomputer, and performs the functions of the above-described components 21 to 29 by software. The program contents related to these processes are:
The program may be stored in a memory such as a ROM (Read Only Memory) at the time of shipment from the factory, or may be stored in a rewritable memory such as a flash RAM so that the contents of the program can be updated and modified at any time. Is also good. However, the present invention is not limited to these, and the control unit 20 may be configured by hardware means capable of performing the same processing.

First, an AC voltage output from the AC power supply 2 is converted into a DC voltage by an AC / DC converter circuit 3 and supplied to an inverter circuit 4. Inverter circuit 4
Are switched at a desired duty ratio by a PWM waveform signal output from the PWM generation / phase distribution unit 29. This allows I
A drive current is supplied to the three-phase coil of the PM motor 1 to drive the motor 1.

The torque waveform corresponding to the coil 1 is stored in the coil one-phase torque waveform storage unit 21 in advance. The torque waveform may be a measured value of motor torque data measured in advance, or a calculated value calculated from a motor model represented by a mathematical expression. The torque waveform corresponding to the coil 1 is stored in the target current waveform calculator 22 from the coil one-phase torque waveform storage 21.
The optimum coil current waveform for driving the IPM motor 1 with maximum efficiency is calculated by the target current waveform calculation unit 22. The actual coil current waveform detected via the current sensor 17 and the coil current detection unit 23 when the IPM motor 1 is driven and the optimum coil current waveform are input to the detection / target current comparison unit 24, and the detection / target current comparison is performed. An error signal with a desired current waveform is given from the section 24 to the coil voltage control section 28.

On the other hand, the rotation speed / position calculator 25 detects or calculates the rotation speed and the rotation position of the IPM motor 1 based on the output signal of the current sensor 17. In this motor driving device, the motor rotation speed and rotation position information are obtained based on the output signal of the current sensor 17, but may be calculated from the induced voltage of the coil of the motor 1 or may be obtained by using the rotation detection value. Alternatively, an external center point detection circuit may be used, or the calculation may be performed from the inductance of the motor coil.

The IP read from the target rotation speed storage unit 26
The target rotation speed of the M motor 1 and the actual rotation speed and rotation position information of the IPM motor 1 calculated by the rotation speed / position calculation unit 25 are input to the rotation speed comparison unit 27, and the rotation speed and position error information are input. From the rotation speed comparison unit 27 to the coil voltage control unit 28
Given to. The coil voltage control unit 28 generates an error correction voltage and energization phase correction information based on these pieces of information, and provides them to the PWM generation / phase distribution unit 29. The PWM generation / phase distribution unit 29 determines the duty ratio of the PWM waveform signal based on the voltage data, distributes the PWM waveform signal to the bases of the IGBTs 5 to 10 included in the inverter circuit 4, and switches each of the IGBTs 5 to 10. Let it.

The optimum current waveform for obtaining the maximum efficiency in the motor driving device configured as described above will be described in detail. The IPM motor 1 uses the reluctance torque in addition to the framing torque by embedding the permanent magnet 32 inside the rotor 31 in order to obtain higher efficiency. In the IPM motor 1, since the magnet 32 is embedded in the rotor 31, the magnetic flux density distribution is not a smooth sine wave, and there is a problem in compatibility with the applied current. The magnetic flux density or torque distribution contributing to the torque generation was confirmed by a three-dimensional dynamic magnetic field simulation.

FIG. 2 is a sectional view showing a main part of the IPM motor 1. In FIG. 2, the rotor 31 is formed by laminating thin plates of a high magnetic permeability material whose outer shape is punched out in a circular shape. Therefore, the rotor 31 has a cylindrical shape. Further, the rotor 31 is provided with a slit 33 for inserting an arc-shaped permanent magnet 32. Four arc-shaped permanent magnets 32 are arranged in the IPM motor 1, and are arranged so that the polarity is inverted in a 90 ° pair. The shape of the permanent magnet 32 and the slit 33 is formed in an arc shape concentric with the center side of the rotor 31.
The rotational force of the rotor 31 is transmitted to the outside by the rotating shaft 34. A predetermined number of teeth 36 are provided on the stator 35, and a stator winding 37 is wound around each of the teeth 36. When an alternating current is applied to the stator winding 37 forming the three-phase U, V, W coils, a rotating magnetic flux is generated,
Fleming torque and reluctance torque act on the rotor 31 by the rotating magnetic flux, and the rotor 31 is driven to rotate. The line connecting the center of the permanent magnet 32 and the center of the rotor 31 is the d-axis, and the q-axis is obtained by rotating the d-axis by an electrical angle of 90 °.

FIG. 3 shows a result obtained by three-dimensional magnetic field simulation of torque generated when a low current is applied to a one-phase coil in the IPM motor 1 configured as described above.
Shown in In FIG. 3, the abscissa indicates the current application timing, and the ordinate indicates the torque. The three curves respectively show the reluctance torque, the magnet torque, and the total torque combining them. When obtaining the reluctance torque, the magnetic permeability was set assuming that the permanent magnet was air in the motor model. As shown in FIG. 3, the actual reluctance torque and magnet torque include higher harmonic components. In particular, the torque pulsation due to the disturbance of the magnetic flux at the boundary between the four built-in permanent magnets is remarkable in the magnet torque.

In consideration of the actual (simulation) torque waveform, the motor performance when a coil voltage having the same waveform as the torque waveform was applied was simulated. FIG. 4 shows the coil current, the coil voltage, and the simulation result. In FIG. 4, the abscissa indicates a value in which the rotation angle is dimensionless, the ordinate on the right indicates torque, and the ordinate on the left indicates a value in which current and voltage are dimensionless. The three curves respectively show the applied voltage, the coil current as a simulation result, and the torque.
Table 1 summarizes the simulation results.

[0041]

[Table 1]

In Table 1, waveform (A) is a sinusoidal waveform of the conventional driving method, and waveform (B) is the optimum current waveform of the present invention. The iron loss includes an eddy current loss and a hysteresis loss caused by a time change of the magnetic flux, and the copper loss is a Joule loss generated in the motor coil. The efficiency is calculated from the motor output and the loss. As shown in Table 1, the optimal current waveform of the present application has a small pulsation of iron loss due to the pulsation of the waveform as compared with the normal sine wave waveform, but since the torque can be effectively used, the same torque is generated. And the current applied to the coil is reduced, and as a result, the efficiency is improved.

More preferably, as shown in FIG.
The neutral point 38d of the three-phase coils 38a, 38b, 38c of the PM motor 1 may be grounded. As a result, it is possible to independently supply current to each of the three-phase coils 38a to 38c, and a more stable motor drive can be realized.

The coil one-phase coil waveform storage unit 21 for storing a torque waveform corresponding to the coil 1 may store a motor torque data measured value waveform measured in advance.
FIG. 6 shows an example of the torque waveform measuring device. 6, the torque waveform measuring device includes a load device (external motor) 41, a torque detecting unit 42, a load device driving unit 43, and a target motor data measuring / driving unit 44.

When the torque of the target motor 1 is measured, the external motor 41 is driven by the load device driving unit 43 under a constant load, and the target motor data measuring / driving unit 44 is operated.
Supplies electric power to the target motor 1 to drive the motor 1. However, the rotation methods of the motors 1 and 41 are reversed, and the external motor 41 is driven to have a brake torque. At this time, the external motor 41 generates a constant torque without pulsation, but the target motor 1 generates a torque pulsation.
As a result, the torque pulsation of the target motor 1 is
Is detected by Here, the torque for one phase of the stator coil is represented by the sum of the series of sin and cos in consideration of torque pulsation. The torque of the entire motor 1 is
From the torque waveform for one phase and the torque waveform, π / 3, 2π
Two torque waveforms out of phase by / 3 (shape is the same)
And the sum of The one-phase torque waveform obtained from the magnetic flux density distribution is compared with the one-phase torque waveform obtained from the actual torque waveform to accurately obtain the one-phase torque waveform.

As described above, by controlling the coil applied voltage so as to have an actual torque waveform of the IPM motor 1, that is, a current waveform adapted to the actual magnetic flux density and inductance, the applied current is effectively converted to motor torque. And efficiency can be improved.

FIG. 7 is a circuit block diagram showing a modification of the first embodiment. The control unit 45 of this motor driving device is different from the control unit 20 of FIG. 1 in that a coil one-phase back electromotive force waveform is obtained based on coil voltage information of the IPM motor 1 instead of the coil one-phase torque waveform storage unit 21. This is the point that a back electromotive voltage waveform detection unit 46 for detecting is provided.
The target current waveform calculation unit 22 calculates the IPM based on the coil one-phase back electromotive voltage waveform detected by the back electromotive voltage waveform detection unit 46.
An ideal coil current waveform for driving the motor 1 with the highest efficiency is calculated.

In this modified example, the actual back electromotive voltage waveform of the coil of the IPM motor 1 is detected, and the applied voltage is controlled so that the current waveform conforms to the actual magnetic flux density and inductance. The applied current can be converted to a motor torque, and the efficiency can be improved.

[Second Embodiment] FIG. 8 is a circuit block diagram showing a configuration of a motor driving device according to a second embodiment of the present invention. 8, the control unit 50 of this motor driving device is different from the control unit 20 of FIG. 1 in that a target phase difference storage unit 51, a voltage / current phase difference detection unit 52, and a comparison unit 5
3 is added, the coil voltage control unit 28 is replaced by the coil voltage control unit 54, and the rotation speed / position calculation unit 25 and the rotation speed comparison unit 27 are deleted.

The target phase difference storage section 51 stores a target phase difference between the coil applied voltage and the coil current. Voltage/
The current phase difference detector 52 detects a phase difference between the coil applied voltage of the IPM motor 1 and the coil current at the time of driving detected by the coil current detector 23. The comparison unit 53 compares the target phase difference read from the target phase difference storage unit 51 with the phase difference detected by the voltage / current phase difference detection unit 52, and compares the voltage / voltage difference.
The current phase difference information is generated and provided to the coil voltage control unit 54. The coil voltage control unit 54 compares the target rotation speed information read from the target rotation speed storage unit 51 with the voltage /
Based on the current phase difference information, the coil application voltage is controlled via the PWM generation / phase distribution unit 29 so that the target rotation speed and the target current waveform are obtained.

In the second embodiment, the same effects as those of the first embodiment can be obtained, and the operation of detecting the rotation speed and the position of the rotor 31 of the motor 1 is not required.

[Third Embodiment] FIG. 9 is a circuit block diagram showing a configuration of a motor drive device according to a third embodiment of the present invention. 9, the control unit 55 of this motor drive device is different from the control unit 20 of FIG. 1 in that the coil one-phase torque waveform storage unit 21 is replaced by a rotation speed-coil one-phase torque waveform storage unit 56. It is. Number of rotations-coil 1
The phase torque waveform storage section 56 stores a table showing the relationship between the number of rotations of the motor 1 and the coil 1 phase torque waveform.
The rotation speed of the motor 1 calculated by the rotation speed / position calculation unit 25 is given to a rotation speed-coil one-phase torque waveform storage unit 56, and a torque waveform corresponding to the rotation speed is obtained by the rotation speed-coil 1
The data is read from the phase torque waveform storage unit 56 and provided to the target current waveform calculation unit 22. Other configurations and operations are the same as those of the motor driving device of FIG.

Here, the relationship between the rotational speed and the torque waveform will be described. As described above, in the present invention, a target current waveform suitable for an actual torque waveform or a back electromotive force waveform is set,
Although the applied voltage is controlled so as to have the target current waveform, the induced voltage waveform or the torque waveform often differs depending on the rotation speed. This can be seen from the following formula (2) regarding the back electromotive voltage.

E = (Φ ₁ −Φ ₂ ) / t (2) where E is an induced voltage, Φ ₁ and Φ ₂ are magnetic fluxes, and t is time.

As is apparent from the equation (2), the coil back electromotive voltage E depends on the temporal change of the magnetic flux Φ. In the case of a motor, the back electromotive voltage E increases as the rotation speed increases. Further, a difference between the applied voltage and the back electromotive voltage is applied to the coil, and a coil current flows to generate a torque. Therefore,
It is desirable to detect the number of rotations of the motor 1 and set a target current waveform suitable for the torque waveform and the back electromotive voltage waveform.

In the third embodiment, the applied voltage is adjusted so that the actual torque waveform of the IPM motor 1 in consideration of the influence of the rotation speed, that is, the current waveform suitable for the magnetic flux density and the inductance in consideration of the influence of the rotation speed. Since the control is performed precisely, the applied current can be effectively converted into the motor torque, and the efficiency can be further improved.

FIG. 10 is a circuit block diagram showing a modification of the third embodiment. The difference between the control unit 57 of this motor drive device and the control unit 55 of FIG.
The coil one-phase torque waveform storage unit 56 stores the load torque calculation unit 5
8 and motor output-coil one-phase torque waveform storage section 59
Is replaced by The load torque calculator 58 calculates
The load torque is calculated based on the rotation speed and the coil current of the motor model formula of the IPM motor 1, and further, the motor output is calculated based on the calculated torque and the rotation speed. Give to. The calculation method of the load torque is described in the IEEJ technical report on torque observer control and the like (No. 737). Motor output-coil one-phase torque waveform storage section 59
Reads a coil one-phase torque waveform corresponding to the motor output provided from the load torque calculator 58 and supplies the waveform to the target current waveform calculator 22. Other configurations and operations are the same as those of the motor driving device of FIG.

Here, the motor output and the torque waveform will be described. As described above, the actual torque waveform and the back electromotive force waveform change depending on the number of revolutions. Further, as shown in Expression (1), the magnet torque of the IPM motor 1 is proportional to the current, and the reluctance torque is the square of the current. Is proportional to Therefore, when the load torque is small, that is, when the coil current is small and when the load torque is large, the torque waveforms are different. Therefore, a target current waveform suitable for both the parameters of the rotation speed and the load torque is set, and the target current waveform and It is desirable to control the applied voltage so that

In this modified example, an actual torque waveform of the IPM motor 1 in consideration of the influence of the rotation speed and the load torque, that is, a current waveform suitable for the inductance of the magnetic flux density in consideration of the influence of the rotation speed and the load torque is obtained. Since the applied voltage is precisely controlled, the applied current can be effectively converted into a motor torque, and the efficiency can be further improved.

[Fourth Embodiment] FIG. 11 is a circuit block diagram showing a configuration of a motor driving device according to a fourth embodiment of the present invention. In FIG. 11, the control unit 60 of this motor drive device is different from the control unit 55 of FIG.
The point is that an efficiency storage unit 61, a driving method selecting unit 62 and each driving method corresponding unit 63 are added. The rotation speed / efficiency storage unit 61 stores data on the efficiency and the driving method at each rotation speed of the IPM motor 1. The driving method selection unit 62 refers to the data in the rotation speed / efficiency storage unit 61 and
The driving method that maximizes the efficiency is selected according to the rotation speed of the PM motor 1. Each driving method corresponding unit 63 stores a 120 ° rectangular wave driving method, a 180 ° sine wave driving method, and the like, and sends a signal corresponding to the driving method selected by the driving method selecting unit 62 to the coil voltage control unit 28. give. The coil voltage control unit 28 controls the inverter circuit 4 via the PWM reproduction / phase distribution unit 29 according to a signal from each driving method corresponding unit 63.

Here, the relationship between the rotational speed, the efficiency, and the driving method will be described. As described above, the efficiency is determined by the eddy current loss, the iron loss which is a hysteresis loss, the copper loss of the coil portion, and the like. In general, iron loss can be classified into eddy current loss and hysteresis loss, and the relationship between these is described in “Characteristics of Rotating Machine Iron Loss and How to Reduce It” (Open Road and Other Motor Technology Symposium A-2-3-1, A-2-3-17) is represented by the following equation (3).

[0062]

(Equation 2)

Where We is the eddy current loss, Wh is the hysteresis loss, w is the drive frequency, Bve is the magnetic flux density, ρ _Fe is the electric low efficiency, d is the density, k is the correction coefficient, Bm is the magnetic flux density peak, μ _s Is the transmission magnetic permeability, and t is the plate thickness.

From the above equation (3), the eddy current loss is proportional to the driving frequency and the square of the magnetic flux density, and the hysteresis loss is proportional to the driving frequency and the square of the magnetic flux density. Table 1
As shown in (2), in the current waveform corresponding to the torque, the magnetic flux change tends to be larger than that in the sine wave drive. Further, when the rotation speed increases, the iron loss increases, and when the rotation speed exceeds the reduction amount of the copper loss, there is a rotation range in which the efficiency is worse than that of the sine wave drive. Therefore, a method of selecting a driving method according to the number of rotations is desirable. As for the relationship between the rotational speed and the optimal driving method, a method of measuring in advance is preferable.

In the fourth embodiment, the applied voltage is precisely adjusted so that the torque waveform of the IPM motor 1 in consideration of the influence of the rotation speed, that is, a current waveform suitable for the magnetic flux density and the inductance in consideration of the influence of the rotation speed, will be described. Control, and select the driving method with the highest efficiency according to the number of rotations.
The applied current can be effectively converted to motor torque,
It is possible to further improve efficiency.

FIG. 12 is a circuit block diagram showing a modification of the fourth embodiment. 12, the control unit 65 of this motor drive device is different from the control unit 60 of FIG. 11 in that a load torque calculation unit 58 is added and the number of rotations /
The point is that the efficiency storage unit 61 and the rotation speed-cork one-phase torque waveform storage unit 56 are replaced by a motor output / efficiency data storage unit 66 and a motor output-coil one-phase torque waveform storage unit 59, respectively. The load torque calculation unit 58 calculates a motor output based on the rotation speed of the motor 1 calculated by the rotation speed / position calculation unit 25 and supplies the motor output to the drive method selection unit 62 and the motor output-coil one-phase torque waveform storage unit 59. . The motor output / efficiency data storage section 66 stores data on the efficiency and the driving method for each motor output. The driving method selection unit 62 refers to the data in the motor output / efficiency data storage unit 66 and selects a driving method capable of obtaining the highest efficiency according to the motor output. Other configurations and operations are the same as those of the motor driving device of FIG.

In this modified example, the actual torque waveform of the IPM motor 1 in consideration of the influence of the rotation speed and the load torque, that is, a current waveform suitable for the magnetic flux density and the inductance in consideration of the influence of the rotation speed and the load torque is obtained. The voltage applied to the coil is precisely controlled, and the drive method that maximizes the efficiency is selected according to the number of revolutions. Therefore, the applied current can be effectively converted to motor torque, and the efficiency can be further improved. It becomes possible.

The embodiments disclosed this time are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

[0069]

As described above, in the motor driving device according to the present invention, the power supply capable of controlling the output for supplying the drive current to the coil of the synchronous motor and the power supply for detecting the current flowing in the coil of the synchronous motor are provided. Current detection means, motor information generation means for generating motor information related to the rotation torque of the synchronous motor, and a target current waveform for driving the synchronous motor with high efficiency based on the motor information from the motor information generation means. There are provided a current waveform generating means for generating, and a control means for controlling the output of the power supply such that the waveform of the current detected by the current detecting means matches the current waveform generated by the current waveform generating means. Therefore, since the coil can be driven with a current waveform corresponding to the rotation torque of the synchronous motor, it is possible to prevent unnecessary current from being consumed,
High efficiency is obtained.

Preferably, the motor information generating means includes a torque waveform storing means in which a torque waveform corresponding to the coil 1 of the synchronous motor is stored in advance, and the motor information is a torque waveform read from the torque waveform storing means. . In this case, a target current waveform is generated based on the torque waveform read from the torque waveform storage means.

Preferably, the torque waveform is obtained by connecting the rotating shaft of the synchronous motor and the rotating shaft of the load motor with a torque detecting device, driving the synchronous motor and detecting the torque waveform with the torque detecting device. In this case, a torque waveform can be easily generated.

Preferably, the motor information generating means includes:
The apparatus includes voltage waveform detection means for detecting a back electromotive voltage waveform of the coil of the synchronous motor, and the motor information is a back electromotive voltage waveform detected by the voltage waveform detection means. In this case, the target current waveform is generated based on the actual back electromotive voltage waveform of the coil detected by the voltage waveform detecting means.

Preferably, there is provided a phase difference detecting means for detecting a phase difference between an output voltage of the power supply and a current detected by the current detecting means, and the control means further comprises a phase difference detecting means for detecting the phase difference detected by the phase difference detecting means. Of the power supply is controlled so as to obtain a desired value. In this case, the motor can be driven at a desired rotation speed without detecting the rotation speed of the motor.

[0074] Preferably, the apparatus further comprises rotation number detecting means for detecting the rotation number of the synchronous motor, and the control means further comprises a control means for setting the rotation number detected by the rotation number detecting means to a desired value. Performs power supply output control. In this case, the number of rotations of the motor can be set to a desired value.

Preferably, the motor information generating means includes:
The motor information includes torque waveform storage means in which the relationship between the torque waveform corresponding to the coil 1 of the synchronous motor and the rotation speed of the synchronous motor is stored in advance, and the motor information is stored in a torque waveform according to the rotation speed detected by the rotation speed detection means. 6 is a torque waveform read from a storage unit. In this case, a current waveform is generated based on the torque waveform read from the torque waveform storage means according to the rotation speed.

Preferably, further, there is provided a driving method storing means in which a relationship between the number of revolutions of the synchronous motor and a driving method for driving the synchronous motor with high efficiency at the number of revolutions is stored in advance, and the control means comprises: Further, the output of the power supply is controlled by the driving method read from the driving method storing means in accordance with the number of rotations detected by the rotation number detecting means. In this case, the power supply is controlled by the driving method read from the driving method storage means according to the number of rotations.

Preferably, furthermore, output calculating means for calculating the output of the synchronous motor based on the rotational speed detected by the rotational speed detecting means is provided, and the motor information generating means includes a torque corresponding to the coil 1 of the synchronous motor. A torque waveform storage unit in which a relationship between the waveform and the output of the synchronous motor is stored in advance, and the motor information is a torque waveform read from the torque waveform storage unit in accordance with the output of the synchronous motor calculated by the output calculation unit. is there. In this case, a target current waveform is generated based on the torque waveform read from the torque waveform storage means according to the motor output.

Preferably, further, there is provided driving method storing means in which a relationship between an output of the synchronous motor and a driving method for driving the synchronous motor with high efficiency at the output is stored in advance, and the control means further comprises: In accordance with the output of the synchronous motor calculated by the output calculation means, the output of the power supply is controlled by the driving method read from the driving method storage means.
In this case, the power supply is controlled by the driving method read out from the driving method storage means according to the motor output.

Also preferably, the synchronous motor includes a three-phase coil, and a neutral point of the three-phase coil is grounded. In this case, since each coil can be controlled independently,
The motor can be driven with high efficiency without interference between phases.

Preferably, the synchronous motor is an IPM motor having a rotor having a permanent magnet built therein. In this case, particularly high efficiency is obtained.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram showing a configuration of a motor drive device according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a main part of the IPM motor shown in FIG.

FIG. 3 is a diagram for explaining a torque waveform of the IPM motor shown in FIGS. 1 and 2;

FIG. 4 is a diagram illustrating a simulation result of the motor driving device illustrated in FIG. 1;

FIG. 5 is a diagram showing a modification of the first embodiment.

FIG. 6 is a block diagram showing an apparatus for generating a torque waveform of the IPM motor 1.

FIG. 7 is a circuit block diagram showing another modification of the first embodiment.

FIG. 8 is a circuit block diagram showing a configuration of a motor drive device according to a second embodiment of the present invention.

FIG. 9 is a circuit block diagram showing a configuration of a motor drive device according to a third embodiment of the present invention.

FIG. 10 is a circuit block diagram showing a modification of the third embodiment.

FIG. 11 is a circuit block diagram showing a configuration of a motor drive device according to a fourth embodiment of the present invention.

FIG. 12 is a circuit block diagram showing a modification of the fourth embodiment.

FIG. 13 is a diagram for explaining torque of an IPM motor.

FIG. 14 is a circuit block diagram showing a configuration of a conventional motor control device.

FIG. 15 is a diagram for explaining a problem of a conventional motor drive device.

[Explanation of symbols]

1 IPM motor, 2 AC power supply, 3 AC / DC converter circuit, 4,84 inverter circuit, 5-10 IG
BT, 11 to 16, 78 to 83 diode, 17 current sensor, 20, 45, 50, 55, 57, 60, 65
Control unit, 21 Coil one-phase torque waveform storage unit, 22
Target current waveform calculator, 23 Coil current detector, 24
Detection / target current comparison unit, 25 rotation speed / position calculation unit, 2
6 Target rotation speed storage unit, 27 rotation speed comparison unit, 28,5
4 Coil voltage control unit, 29 PWM creation / each phase distribution unit,
31 rotor, 32 permanent magnet, 33 slit, 34
Rotating shaft, 35 stator, 36 teeth, 37 stator winding, 38u, 38v, 38w, 86u, 86
v, 86w coil, 38d, 86d, 87d neutral point,
41 Load device, 42 Torque detection unit, 43 Load device drive unit, 44 Target motor data measurement / drive unit, 46 Back electromotive force waveform detection unit, 51 Target phase difference storage unit, 52 Voltage / current phase difference detection unit, 53 Comparison Part, 56 rpm-
Coil one-phase torque waveform storage, 58 Load torque calculation, 59 Motor output-coil one-phase torque waveform storage,
61 rotation speed / efficiency storage unit, 62 drive method selection unit, 6
3 each drive method corresponding section, 66 motor output / efficiency data storage section, 71 DC power supply, 72 to 77 switching transistor, 85 brushless DC motor, 87u, 87
v, 87w, 88, 90, 92 resistance element, 89, 95
Operational amplifier, 91 differential amplifier, 93 capacitor,
94 integrator, 96 zero cross comparator, 97
Microprocessor, 98 Base drive circuit.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H02P 6/16 H02P 6/02 341N F-term (Reference) 5H002 AA09 AB07 AE07 AE08 5H560 BB04 BB17 DB14 DC12 EB01 EC01 GG04 RR10 SS07 TT07 TT11 UA06 XA02 XA04 5H619 AA01 BB24 PP02 PP08 5H621 AA03 BB07 BB10 GA04 HH01 5H622 AA03 CA06 CA10 CA13 CB05 PP10

Claims (12)

[Claims] 1. A motor drive device for driving a synchronous motor having a rotor on which a permanent magnet is mounted, comprising: a power supply capable of controlling output for supplying a drive current to a coil of the synchronous motor; Current detection means for detecting a current flowing in the coil of, motor information generation means for generating motor information related to the rotational torque of the synchronous motor, based on the motor information from the motor information generation means,
Current waveform generating means for generating a target current waveform for driving the synchronous motor with high efficiency; and a current waveform detected by the current detecting means coincides with a current waveform generated by the current waveform generating means. And a control unit for controlling the output of the power supply. 2. The motor information generating means includes a torque waveform storage means in which a torque waveform corresponding to the coil 1 of the synchronous motor is stored in advance, and the motor information is a torque read from the torque waveform storage means. The motor driving device according to claim 1, wherein the motor driving device has a waveform. 3. The torque waveform is obtained by connecting a rotation axis of the synchronous motor and a rotation axis of a load motor by a torque detection device, driving the synchronous motor, and detecting the torque waveform by the torque detection device. Item 3. A motor drive device according to item 2. 4. The motor information generating means includes voltage waveform detecting means for detecting a back electromotive voltage waveform of a coil of the synchronous motor, and the motor information includes a back electromotive voltage waveform detected by the voltage waveform detecting means. The motor drive device according to claim 1, wherein 5. A phase difference detecting means for detecting a phase difference between an output voltage of the power supply and a current detected by the current detecting means, wherein the control means further detects the phase difference by the phase difference detecting means. 5. The motor drive device according to claim 1, wherein output control of the power supply is performed so that the obtained phase difference becomes a desired value. 6. The apparatus according to claim 1, further comprising: a rotation speed detection unit configured to detect a rotation speed of the synchronous motor, wherein the control unit further controls the rotation speed detected by the rotation speed detection unit to a desired value. 2. The motor drive device according to claim 1, wherein output control of the power supply is performed. 7. The motor information generating means includes torque waveform storage means in which a relationship between a torque waveform corresponding to the coil 1 of the synchronous motor and a rotation speed of the synchronous motor is stored in advance, and the motor information is: The motor drive device according to claim 6, wherein the torque waveform is a torque waveform read from the torque waveform storage means according to the rotation speed detected by the rotation speed detection means. 8. A driving method storing means in which a relationship between a rotational speed of the synchronous motor and a driving method for driving the synchronous motor with high efficiency at the rotational speed is stored in advance, wherein the control means comprises: 8. The motor drive device according to claim 7, further comprising controlling the output of said power supply by a driving method read from said driving method storage means in accordance with the rotation speed detected by said rotation speed detection means. 9. An output calculating means for calculating an output of the synchronous motor based on a rotational speed detected by the rotational speed detecting means, wherein the motor information generating means includes a coil 1 of the synchronous motor.
A torque waveform storage unit in which a relation between a corresponding torque waveform and an output of the synchronous motor is stored in advance, wherein the motor information is stored in accordance with an output of the synchronous motor calculated by the output calculation unit. 7. The motor drive device according to claim 6, wherein the torque drive is a torque waveform read from the means. 10. A driving method storing means in which a relationship between an output of the synchronous motor and a driving method for driving the synchronous motor with high efficiency at the output is stored in advance, and the control means further comprises: 10. The motor drive device according to claim 9, wherein output control of the power supply is performed by a drive method read from the drive method storage means according to the output of the synchronous motor calculated by the output calculation means. 11. The motor drive device according to claim 1, wherein the synchronous motor includes a three-phase coil, and a neutral point of the three-phase coil is grounded. 12. The motor drive device according to claim 1, wherein the synchronous motor is an IPM motor having a rotor having a permanent magnet built therein.