JPH11332298A - Apparatus and method for control of motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce pulsation in a torque in an AC motor. SOLUTION: A current setting part 212 which sets the target current of a d-axis and of a q-axis according to the speed of rotation and the required torque of a motor is installed. On the basis of the target current which is set, a voltage command is set by a PI control operation. By a PWM control operation according to the voltage command, a current is made to flow to every phase of the motor. By repeating this processing, the operation of the motor is controlled. As a current map 214 which is used by the current setting part 212 in order to set the target current, the map 214 in which the target current is changed according to an electrical angle is prepared. In addition, a sensor which detects the electrical angle of the motor is installed. The current setting part 21 sets the target current by taking into consideration the electrical angle which is detected. Thereby, the pulsation of a torque during the rotation of the motor can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device and a control method for controlling the operation of a motor, and more particularly to a control device and a control method for controlling the operation of a motor while suppressing fluctuations in output torque.

[0002]

2. Description of the Related Art In order to obtain a desired rotation torque in a motor in which a polyphase alternating current is passed through a winding and a rotor is rotated by an interaction between a magnetic field generated by the winding and a magnetic field generated by a permanent magnet,
It is necessary to control the polyphase alternating current flowing through the winding according to the required torque. The polyphase alternating current flowing through the winding is set by the current value and the phase angle.

[0003] The phase angle is an angle indicating a deviation between an electric angle indicating an electric rotation position of the rotor with respect to the stator and a direction of a magnetic field generated by a current flowing through the winding. For example, in a synchronous motor having a permanent magnet on the rotor, the direction in which the magnetic field generated by the permanent magnet passes through the center of the rotor is defined as the d-axis direction,
If a direction electrically orthogonal to the d-axis direction is defined as a q-axis direction, a maximum torque is generated when a current flows through the winding at a phase angle at which a magnetic field is generated in a direction close to the q-axis.

Conventionally, a torque to be output from an electric motor,
A map that stores the relationship between the current value and the phase angle of the current flowing through the winding is prepared, and the current flowing through the winding is set by referring to this map based on the required torque.

[0005]

However, it has been found that when the current is set by such a method, pulsation occurs in the output torque of the motor. FIG. 10 shows the pulsation of the output torque. FIG. 10 shows the output torque Tol when the control for outputting the constant required torque Treq is performed.
6 is a graph showing d with an electric angle on the horizontal axis. FIG.
As shown by 0, the output torque Told generated a pulsation that increased or decreased from the required torque Treq in accordance with the change in the electrical angle, that is, the rotation of the electric motor. In the example shown in FIG. 10, pulsation occurs at a cycle of an electrical angle of approximately 60 degrees. The cycle of the pulsation changed according to the number of permanent magnets provided on the rotor of the electric motor and the number of teeth of the stator, and the like.

[0006] Such pulsation of torque is an unfavorable phenomenon in using an electric motor as a power source of various devices. For example, when an electric motor is used as a power source of a so-called hybrid vehicle, there is a possibility that the ride comfort of the vehicle may be impaired due to torque pulsation shown in FIG. In addition, when torque pulsation occurs, the motor outputs excessive torque or lacks torque, so that the operating efficiency is higher than when a constant torque corresponding to the required torque Treq is continuously output. Had declined. This is because the energy output as surplus torque is generally consumed in the form of heat or the like.

FIG. 10 shows an example in which torque pulsation occurs in a synchronous motor. Such torque pulsation has similarly occurred in various AC motors such as induction motors as well as synchronous motors.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and provides a control device and a control method for reducing a pulsation of output torque in a motor for rotating a rotor by flowing a polyphase alternating current through a winding. The purpose is to:

[0009]

Means for Solving the Problems and Their Functions / Effects In order to solve the above problems, the present invention has the following arrangement. The motor control device of the present invention controls the operation of the motor that rotates the rotor by using the rotating magnetic field generated in the winding when the polyphase alternating current flows by controlling the polyphase alternating current flowing in the winding. A motor control device for controlling the motor, comprising: setting means for setting a required torque to be output from the motor; electric angle detecting means for detecting an electric angle defining an electric rotational position of the rotor; Current setting means for setting a current flowing through the winding to output the current in consideration of not only the required torque but also the detected electrical angle, and an energizing means for flowing the set current through the winding. The point is to prepare.

According to such a motor control device, the pulsation of the torque output from the motor can be reduced. As a result, when the electric motor is applied as a power source for various devices, the electric motor and the device to which the electric motor is applied can be operated stably. Further, the electric motor can be operated efficiently. Hereinafter, such an operation will be described.

In order to complete the motor control device of the present invention, it was necessary to find out the cause of the pulsation of the output torque (see FIG. 10) by the conventional control method. FIG.
Various causes can be considered for the torque pulsation shown in FIG. For example, mechanical elements such as fluctuations in the position of the center of gravity of the rotor and non-uniformity of the friction of the bearing, and electrical elements such as non-uniformity of the response of the resistance and switching elements in the circuit for flowing the current through the windings. Elements. The inventor of the present invention measured the current flowing through the windings of the electric motor when the torque of FIG. 10 was output in order to search for the cause of the torque pulsation. FIG. 11 shows the measurement results of the current. A polyphase alternating current flows through the synchronous motor used in FIG. FIG. 11 is a graph showing a change in phase current focusing on one of these phases. As shown in FIG. 11, the current value iopt to be passed through the winding to output a constant torque is compared with the actual current value iold.
There are many or few. As a result, FIG.
It has been found that the main cause of the torque pulsation shown as 0 is the current flowing through the winding.

Next, the inventor paid attention to the fact that the torque pulsation shown in FIG. 10 occurs at a period of an electrical angle of about 60 degrees. Generally, a kind of resistance called inductance is generated in the winding. This resistance changes under the influence of an external magnetic field. When the rotor is rotating, the effect of the magnetic field of the permanent magnet provided on the rotor on the winding changes, so that the inductance of the winding changes. This change appears at a period of the electrical angle corresponding to the number of magnetic poles of the motor. If the inductance changes, the current value actually flowing differs from the current command value even when a voltage is applied based on the current command value set according to the required torque. From such considerations, the inventor has found that the main cause of the torque pulsation shown in FIG. 10 is the change in inductance.

The present invention has been completed in view of the above. The current setting means in the motor control device of the present invention sets the current flowing through the winding in consideration of not only the required torque but also the electrical angle. It differs greatly from the conventional current setting method in that the electrical angle is taken into account. By changing the current flowing through the winding according to the electrical angle in this manner, the current required to output the required torque can be appropriately passed through the winding, and torque pulsation can be reduced. .

"Considering the electrical angle" means that the set current is set so as to be variable according to the electrical angle. As shown in FIG. 10, when torque pulsation occurs at almost the entire electrical angle, the current set at each electrical angle changes periodically. Further, when the torque fluctuates in a pulse at a specific electrical angle, the current changes only at the electrical angle. The “consideration” in the present invention includes both aspects.

The "setting of current" means setting of essential elements related to torque control of the electric motor. Generally, the above-described currents in the d-axis direction and the q-axis direction are essential elements in torque control. As a setting of these elements, a current value in the d-axis direction and a current value in the q-axis direction may be specifically given, or a current value flowing through the winding and a phase angle may be given. Of course, it is also possible to set the magnitude of the current value of each phase actually flowing to the motor.

In the present invention, since "setting of current" is used in the above-mentioned meaning, "setting of current" is such that when replaced with d-axis current and q-axis current, it becomes a constant value regardless of the electrical angle.
Does not correspond to the setting of the current in consideration of the electrical angle in the present invention. For example, the magnitude of the current value of each phase that actually flows through the motor changes according to the electrical angle. However, if the magnitudes of the d-axis current and the q-axis current do not change, the “current setting” in the present invention is used. Not included.

The "required torque setting means" in the motor control device of the present invention may be a means for setting a required torque inside the motor control device, or an output from the motor by inputting the required torque from outside. Means for setting the torque to be used may be used.

The "electric angle detecting means" may be a device for detecting an electric angle using a so-called Hall element or other sensor, or may be operated based on a voltage value and a current value of a winding. Means for detecting an electrical angle may be used.

In the motor control device according to the present invention, the current setting means includes a storage means for storing a relationship between an electric angle and a torque and a current to be passed through the winding to output the torque; And based on the electrical angle
It is preferable to have reference means for obtaining a current to be passed through the winding to output the required torque with reference to the relationship.

According to this configuration, the current flowing through the winding is
It can be set according to the required torque and the electrical angle. Examples of the storage unit include a map that stores a current to be passed through a winding with respect to discrete values of an electric angle and a torque, and a unit that stores a function that gives a relationship between an electric angle, a torque, and a current value. Can be Of course, after once setting the current according to the torque by the conventional control method,
The current set according to the electrical angle may be corrected. In such a case, the storage means stores the relationship for setting the current based on the torque and the relationship for correcting the current set based on the electrical angle according to the electrical angle.

In the case where a map is stored in the storage means, "referencing" refers to reading an appropriate value from the map and performing a complement operation of the map as necessary. In the case where a function is stored in the storage means, it corresponds to calculating the function by substituting necessary quantities. In addition, a method of obtaining the current to be passed through the winding according to the content stored in the storage means corresponds to “reference” in the present invention.

The motor control device of the present invention further includes a rotation speed detecting means for detecting a rotation speed of a rotor of the motor, and the current setting means considers the detected rotation speed. It is desirable to use a means for setting the current.

In this way, it is possible to flow an appropriate current according to the number of rotations. Due to the rotation of the rotor, an induced electromotive force is generated in the winding of the motor. Such an induced electromotive force changes according to the rotation speed of the electric motor. Therefore, in order to output the torque efficiently, it is preferable to change the phase angle of the current flowing through the electric motor according to the rotation speed. According to the above configuration, since the current is set in consideration of the rotation speed, an appropriate torque can be efficiently output according to the rotation speed.

Further, in the motor control device of the present invention, the motor control device further comprises a rotation speed detecting means for detecting a rotation speed of a rotor of the motor, wherein the current setting means is provided when the rotation speed of the motor is not more than a predetermined value. It is also preferable that the means consider only the detected electrical angle.

According to this configuration, the current is set in consideration of the electrical angle only when the rotation speed of the electric motor is equal to or less than the predetermined value. When an electric motor is applied as a power source for a device,
The influence of the torque pulsation on the operation of the device is remarkable when the electric motor is rotating at low speed. Therefore, according to the above configuration, the torque pulsation can be reduced by setting the current in consideration of the electrical angle in a region where the influence of the torque pulsation is remarkable, and thus the utility is high. . The predetermined value in the above invention is a value set in advance based on the influence of torque pulsation as described above.

The present invention is also realized as a motor control method described below. A motor control method according to the present invention is directed to a motor for rotating a rotor using a rotating magnetic field generated in a winding when a polyphase alternating current is applied to the winding to control a current flowing in the winding. A method for controlling operation of an electric motor, the method comprising: (a) setting a required value of a torque to be output from the electric motor; and (b) an electric angle defining an electric rotational position of the rotor. Detecting
(C) By referring to the relationship previously stored between the electric angle and the torque and the current to be passed through the winding to output the torque based on the required torque and the electrical angle, the required torque can be calculated. The gist of the present invention is to include a step of obtaining a current to be passed through the winding in order to output the current, and (d) a step of passing the set current through the winding.

According to this control method, the operation of the motor can be efficiently controlled by reducing the pulsation of the torque by the various operations described above as the control device for the motor.

The above-described motor control device and control method can be applied not only to a so-called inner rotor type motor having a rotor at the center and a stator at the outer periphery, but also to a type of motor called a so-called outer rotor. is there. An outer rotor type electric motor includes a central stator and a rotor surrounding the outer periphery thereof in a circular shape, and a rotating magnetic field is formed by applying a control current to a three-phase coil to rotate the annular outer rotor. It is. Further, the present invention is also applicable to a paired rotor motor including an inner rotor and an outer rotor. In addition, the configuration of the electric motor can be applied to various configurations such as an electric motor having a permanent magnet and an electric motor using an electromagnet instead of the permanent magnet.

Further, by incorporating the motor control device of the present invention, it is possible to configure various inventions using a motor as a power source. Such devices include various machine tools and home appliances. In recent years,
A vehicle that can run using an electric motor as a power source has also been proposed, and can be configured as an invention of such a vehicle as described below. For example, by controlling a polyphase alternating current flowing through a winding, an electric motor that rotates a rotor using a rotating magnetic field generated in the winding when the polyphase alternating current flows, and controls operation of the electric motor. An electric motor control device, wherein the vehicle is capable of traveling using the electric motor as a power source, and further comprising a setting means for setting a required torque to be output from the electric motor in accordance with a traveling state of the vehicle; An electrical angle detecting means for detecting an electrical angle that defines an electrical rotation position of the rotor, and a current flowing through a winding to output the required torque, the detected torque as well as the required torque. The present invention can be summarized as an apparatus including a current setting unit that sets in consideration of an electrical angle and an energizing unit that causes the set current to flow through the winding. Of course, it is possible to apply each of the motor control devices having the various configurations described above.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (1) Configuration of Example: Hereinafter, an embodiment of the present invention will be described using an example. FIG. 1 is an explanatory diagram illustrating functional blocks of a motor control device 10 according to the present embodiment. The object controlled by the motor control device 10 is the motor 40. The motor 40 is, as described later,
It is a synchronous motor that rotates by flowing U, V, and W three-phase alternating current.

The motor control device 10 includes the motor 40
An electrical angle sensor 114 for detecting the electrical angle θ and a rotational speed sensor 115 for detecting the rotational speed N are provided. The electrical angle θ and the rotation speed N detected by these sensors 114 and 115 are passed to the current setting unit 212. The required torque T * set by the required torque setting unit 216 is also passed to the current setting unit 212. Based on these values, the current setting unit 212
And set the current command values id * and iq *.

On the other hand, the three-phase / two-phase converter 210 performs three-phase / two-phase conversion of the current flowing in each of the U, V, and W phases of the motor 40, and outputs the currents id and q flowing on the d-axis. The current iq flowing through the axis is calculated. In FIG. 1, the U-phase current iu and the V-phase current iv of the currents flowing in the U, V, and W phases are shown.
Only those used are shown. This is because, in the case of three-phase alternating current, the total value of the currents flowing through the U, V, and W phases is always 0, so that it is not necessary to detect the current value iw of the W phase.

The previously set current command values id *, iq *
Control units 202d and 202q set voltage command values Vd * and Vq * to be applied to the d-axis and the q-axis, respectively, by so-called proportional-integral control based on the difference between the currents id and iq actually flowing. I do. The voltage command values Vd *, Vq * set in this manner are converted into voltage command values Vu *, Vv *, V of the respective phases U, V, W by the two-phase / 3-phase converter 204.
converted to w *. Based on these command values, PWM
The control unit 206 sets switching signals Su, Sv, Sw for controlling the applied voltage to each phase. By performing switching based on this switching signal, the current supply unit 208 supplies current to each phase.

In the present embodiment, as will be described later, a configuration in which a switching element is provided as the energizing section 208 is employed.
8 for generating a switching signal.
On the other hand, the energizing section 208 having no switching element
Is adopted, the PWM control unit 206 may be omitted. In addition, as long as the control method can realize the voltage command values Vu *, Vv *, Vw *, the switching signal may be generated by another control method without depending on the PWM control. l

Next, the hardware configuration of the motor control device 10 and the motor 40 of this embodiment will be described. FIG.
FIG. 2 is an explanatory diagram illustrating a hardware configuration of a motor control device 10 according to the present embodiment. The motor control device 10 receives an electric angle sensor 114 for detecting the electric angle θ of the motor 40, a rotation speed sensor 115 for detecting the rotation speed N, and receives a torque command from the outside. Control ECU 100 for controlling (V, W phase) motor current, current sensors 102 and 103 for detecting U-phase current iu and V-phase current iv of three-phase synchronous motor 40, and a filter for removing high-frequency noise of the detected current It comprises two analog-to-digital converters (ADCs) 112 and 113 for converting the detected current value into digital data. As an electric angle sensor, a sensor using a Hall element is known. The electric angle sensor 114 and the rotation speed sensor 115
Can also be used. Further, the electrical angle may be obtained by calculation without using a sensor.

As shown, a microprocessor (CP) for performing arithmetic and logical operations is provided in the control ECU 100.
U) 120, a ROM 122 preliminarily storing the processing performed by the CPU 120 and necessary data, a RAM 124 for temporarily reading and writing data necessary for the processing, a clock 126 for clocking, and the like, which are interconnected by a bus. Have been. An input port 116 and an output port 118 are also connected to this bus, and the CPU 120 communicates with the three-phase synchronous motor 40 through these ports 116 and 118.
Current iu, iv flowing in each phase of U, V, and W, electrical angle θ, and rotation speed N can be read.

Further, the control ECU 100 applies an inverter for applying a voltage between the coils of the motor 40 so as to obtain the respective phase currents iu, iv, iw of the motor 40 determined based on the torque command input separately. 130 and a battery 132 are provided at its output. CPU1
The control outputs Su, Sv, Sw, and SD from the inverter 20 are output to the inverter 130, and the three-phase synchronous motor 40
It is possible to externally control the voltage applied to each coil.

In this embodiment, the inverter 130 employs a so-called transistor inverter. Inverter 1
Reference numeral 30 denotes a pair of transistors serving as switching elements for each phase. One of the two transistors of each phase is connected to the source side of the battery 132, and the other is connected to the sink side. Control outputs Su, Sv, Sw, and SD from the control ECU 100 are input to gate signals of these transistors, and control the on / off of each transistor. However, a control output is inverted and input to a transistor provided on the sink side of each phase by an inverter element. Therefore, the transistors of each phase of the inverter are normally configured such that the source side and the sink side are exclusively turned on and off. The control signal SD is a shutdown signal that turns off all the transistors.

The control ECU 100 shown in FIG.
, PI control units 202d, 202q, 2-phase / 3-phase conversion unit 204, PWM control unit 206, 3-phase / 2-phase conversion unit 2
10, a current setting unit 212, a current map 214, and a required torque setting unit 216 that perform the respective functions. In the present embodiment, the required torque setting unit 216 is configured to have a function of setting a torque command value input from the outside as the required torque T *. In addition, the inverter 130 and the battery 132 perform a function corresponding to the power supply unit 208.

Next, the configuration of the motor 40 to be controlled by the motor control device of this embodiment will be described. FIG.
5 is a cross-sectional view of a cross section including the rotation shaft of the motor 40. FIG. FIG. 4 is a cross-sectional view in a cross section orthogonal to the rotation axis. As shown in FIG. 3, the three-phase synchronous motor 40 includes a stator 30, a rotor 50, and a case 60 that houses them. The rotor 50 has permanent magnets 51 to 54 on its outer circumference.
Is attached, and a rotation shaft 55 provided at the center of the shaft is provided.
Are rotatably supported by bearings 61 and 62 provided in the case 60.

The rotor 50 is formed by laminating a plurality of plate-like rotors 57 formed by punching a non-oriented electrical steel sheet. As shown in FIG. 4, the plate-shaped rotor 57 has four salient poles 71 to 74 at orthogonal positions. After laminating the plate-like rotors 57, the rotating shaft 55 is press-fitted, and the laminated plate-like rotors 57 are temporarily fixed. The plate-shaped rotor 57 made of the electromagnetic steel sheet has an insulating layer and an adhesive layer formed on its surface, and is heated to a predetermined temperature after lamination, and is fixed by melting the adhesive layer.

After the rotor 50 is formed in this manner, the permanent magnets 51 to 54 are attached to the outer peripheral surface of the rotor 50 at intermediate positions between the salient poles 71 to 74 in the axial direction. The permanent magnets 51 to 54 are magnetized in the radial direction of the rotor 50, and the polarity of adjacent magnets is different from each other. For example, the outer peripheral surface of the permanent magnet 51 is an N pole, and the outer peripheral surface of the adjacent permanent magnet 52 is an S pole.
It is a pole. The permanent magnets 51 and 52 are
0 is assembled to the stator 30, the plate-like rotor 57
And a magnetic path Md penetrating the plate-shaped stator 20 (FIG. 4).
See broken line).

The plate-like stator 20 constituting the stator 30 is
Like the plate-like rotor 57, it is formed by punching a thin sheet of non-oriented electrical steel sheet, and as shown in FIG.
The teeth 22 are provided. A coil 32 for generating a rotating magnetic field in the stator 30 is wound around a slot 24 formed between the teeth 22. In addition, a bolt hole for passing the fixing bolt 34 is provided at the outer edge of the plate-shaped stator 20, but is not shown in FIG. 4.

The stator 30 is temporarily fixed by heating and melting the adhesive layer in a state in which the plate-like plate-like stators 20 are laminated and pressed against each other. In this state, the coil 32 is wound around the teeth 22 to complete the stator 30, which is assembled to the case 60, and the fixing bolts 34 are inserted into the bolt holes.
And tighten it to secure the whole. Further, the three-phase synchronous motor 40 is completed by assembling the rotor 50 rotatably by the bearings 61 and 62 of the case 60.

When an exciting current is applied to the coil 32 of the stator 30 so as to generate a rotating magnetic field, as shown in FIG. 4, a magnetic path Mq penetrating the adjacent salient poles, the plate-like rotor 57 and the plate-like stator 20 is formed. Is formed. Note that an axis through which the magnetic flux formed by the above-described permanent magnet 51 passes through the rotor 50 in the radial direction through the center of the rotation axis is referred to as a d-axis, and is electrically connected to the d-axis in the rotation plane of the rotor 50. The axis orthogonal to is called the q-axis.
That is, the d-axis and the q-axis are axes that rotate as the rotor 50 rotates. In the present embodiment, the permanent magnets 51 and 53 attached to the rotor 50 have N poles on the outer peripheral surface,
Since the outer peripheral surfaces of the permanent magnets 52 and 54 have S poles, the q-axis is geometrically located at 45 degrees with respect to the d-axis as shown in FIG.

FIG. 5 shows an equivalent circuit of the three-phase synchronous motor 40 of this embodiment. As shown in FIG. 5, the three-phase synchronous motor 40 is represented by an equivalent circuit having U, V, and W three-phase coils and a permanent magnet that rotates around the center of the rotation axis. In this equivalent circuit, the d-axis is represented as an axis passing through the N pole side of the permanent magnet in the positive direction, and the q-axis is represented as an axis geometrically orthogonal to the d-axis. The electrical angle is the rotation angle θ between the axis passing through the U-phase coil and the d axis.

(2) Torque control: Next, the torque control in the motor control device 10 according to the present embodiment will be described with reference to the flowchart of FIG. The torque control routine is a process periodically executed by the CPU 120 shown in FIG.

When this routine is started, the CPU 12
0 reads the target torque T * (step S100).
Next, the electrical angle θ and the number of revolutions N are detected (step S105). The electric angle θ is detected by an electric angle sensor 114, and the rotation speed N is detected by a rotation speed sensor 115. Further, the currents iu and iv are detected (step S11).
0). These values are detected by the current sensors 102 and 103.

Based on the quantities thus detected, the CP
U120 performs three-phase / two-phase conversion to calculate d-axis current id and q-axis current iq (step S115). The three-phase / two-phase conversion is executed by calculating the following equation. i
d = √2 × (−iu · sin (θ−120) + iv · s
in θ); iq = −2 × (−iu · cos (θ−120) + iv ·
cos θ); d-axis current id and q-axis current iq calculated in this way
Is used for setting a voltage command value described later. In the torque control of the electric motor, the d-axis current and the q-axis current are essential parameters. Therefore, in this embodiment, the control is performed by converting these currents into these currents. It is also possible to control the three phases U, V and W without performing such conversion.

Next, the CPU 120 sets d-axis and q-axis target currents id * and iq * based on the target torque T *, the number of revolutions N, and the electrical angle θ (step S120). This processing is performed in accordance with the current map 214 stored in the ROM 122.
From the values corresponding to the target torque T *, the rotation speed N, and the electrical angle θ. The contents of the current map 214 will be described later, including the method of creating the current map 214.

The current map 214 indicates that the target torque T
This is a map that gives target currents id * and iq * to discrete values of *, the rotation speed N, and the electrical angle θ. Therefore, there is a case where the corresponding value does not exist in the map depending on the value of the target torque kT * or the like. In this embodiment, in such a case,
A corresponding value is obtained by linearly complementing the current map 214. When the discrete values of the torque, the number of revolutions, and the electrical angle that compose the map are set sufficiently fine, the supplementary calculation may be omitted. For example, a point closest to the target torque T *, the rotation speed N, and the electrical angle θ may be selected from points existing on the map, and the target currents id *, iq * corresponding to the selected points may be used.

When the target currents id * and iq * are set in this way, the CPU 120 sets voltage command values Vd * and Vq * to be applied in the d-axis direction and the q-axis direction (step S1).
25). This voltage command value is determined by a so-called proportional-integral control (P
I control). That is, step S115
And the target currents id * and i set in step S120.
q * and the difference △ id, △ iq, and the difference △ id,
The voltage command value Vd is determined by the sum of the proportional term and the integral term of Δiq.
*, Vq * are set. Since the proportional-integral control is a well-known control method, further detailed description is omitted.

By the above processing, the voltage command values Vd * and Vq * to be applied to the d-axis and the q-axis are set. Next, CPU1
20 converts these voltage command values to U and U by two-phase / 3-phase conversion.
It is converted into voltage command values Vu *, Vv *, Vw * of each phase of V and W (step S130). The two-phase / three-phase conversion is performed by calculating the following equation.

Vu * = √ (2/3) × (Vd * · cos θ−Vq * · sin θ); Vv * = √ (2/3) × (Vd * · cos (θ−120) −Vq * · sin (Θ-120)); Vw * = − Vu−Vv;

CPU 120 performs PWM control based on the result of the two-phase / three-phase conversion and outputs the result to the inverter. That is, the voltage command values Vu *, Vv *, Vw * of each phase are converted into a duty ratio of the on / off signal of each transistor of the inverter and output. When each transistor of the inverter is turned on / off by this signal, step S120 is performed.
The target currents id * and iq * set in the above flow. As a result, the motor 40 outputs a torque corresponding to the target torque T *. The motor control device of the present embodiment controls the operation of the motor 40 by periodically repeating the above control processing.

(3) Current map: Next, the current map 21 used in step S120 of the torque control described above.
4 will be described. FIG. 7 shows a current map 2 of the present embodiment.
14 is a graph in which basic data used to create the data No. 14 is plotted. The graph of FIG. 7 shows the relationship between the current phase angle, the torque and the current value. The three curves shown in FIG. 7 are curves corresponding to the current values i1, i2, and i3, respectively. The current value satisfies i1 <i2 <i3. In addition, as shown in FIG.
And the number of rotations N.

In the present embodiment, the graph of FIG. 7 was created by a magnetic field analysis using the finite element method or the like. In this analysis, when a certain state during the rotation of the motor 40 is input, the torque acting on the rotor can be output by analyzing the magnetic field between the rotor and the stator. Since such an analysis itself is well known, a detailed description is omitted.

For example, according to this analysis, the electrical angle θ = 0
Degree, rotation speed N = 0 rpm, current value = i2, current phase angle =
When a condition of 20 degrees is given, a result of output torque = T2 is obtained. This is plotted at point P2 in FIG. If the above parameters are changed to various values and the analysis is executed, the curve shown in FIG. 7 can be drawn. Of course, the graph of FIG. 7 may be created experimentally.

Here, the definition of the phase angle φ will be described with reference to an equivalent circuit of a motor (FIG. 5). FIG. 5 shows the phase angle φ.
As shown in FIG. 5, the deviation in the q-axis direction from the direction of the current vector flowing through the winding. Assuming that the magnitude of the current vector is i, the following equation (1) is established between the d-axis current id and the q-axis current iq, as is clear from FIG. id = −i × sinφ; iq = i × cosφ (1)

In general, a synchronous motor can output a large torque when the current vector flowing through the winding is close to the q-axis direction. When the current vector coincides with the d-axis, that is, when the phase angle is 90 degrees, no component for rotating the rotor is generated, and no torque is output. As shown in FIG. 7, the output torque of the motor 40 according to the present embodiment is 0 at the phase angle of 90 degrees regardless of the current value.

The graph shown in FIG. 7 is drawn according to the electrical angle θ and the rotation speed N. In the present embodiment, the electric angle θ is set in increments of 5 degrees, the number of revolutions N is set in increments of 100 rpm, and a graph shown in FIG. 7 is created according to the combination of each electric angle and the number of revolutions. The steps of the electric angle and the number of revolutions can be arbitrarily set according to the characteristics of the motor, the accuracy required for torque control, and the like. Also, it is not always necessary to set them at equal intervals. For example, only an electrical angle of around 30 degrees may be finely set and around 0 degrees may be roughly set.

Further, it is not necessary to draw the graph of FIG. 7 for the entire range of the electrical angle and the rotation speed. In the case of the motor 40 of the present embodiment, the motor is a three-phase synchronous motor, and the same positional relationship between the rotor and the stator is repeated at a cycle of 60 electrical degrees. Therefore, in the present embodiment, a map is prepared in the range of 0 to 60 degrees for electrical angles, and this map is repeatedly used for electrical angles of 60 to 120 degrees and beyond.

Based on the graph of FIG. 7, a current map 214 used for torque control is set. Current map 21
Examples of No. 4 are shown in FIGS. Current map 214
Consists of two maps as shown in these figures. FIG. 8 is a map giving the relationship between the torque and the current phase angle. FIG. 9 is a map giving the relationship between the current phase angle and the motor current. These maps are created using the peak portions of the curves i1, i2, and i3 in the graph of FIG. 7 (points P1, P2, and P3 in FIG. 7). Creating a map using the peak portion indicates that such a portion has the largest output torque with respect to the current value,
This is because the state where the motor can be operated most efficiently is shown.

When the points P1, P2 and P3 in FIG. 7 are plotted with the horizontal axis representing the torque and the vertical axis representing the current phase angle, the points P1, P2 and P3 in FIG. 8 are obtained. Although only three curves are drawn in FIG. 7 for the sake of illustration, the graph of FIG.
Can be obtained.

On the other hand, when plotting the points P1, P2 and P3 in FIG. 7 with the current value on the horizontal axis and the current phase angle on the vertical axis, the points P1, P2 and P3 in FIG. 9 are respectively obtained. In FIG. 7, only three curves are drawn for convenience of illustration, but by creating the graph of FIG. 7 for more current values,
The curve shown in FIG. 9 can be obtained.

In the present embodiment, the maps shown in FIGS.
122. As shown in FIG. 8 and FIG. 9, the point that these maps are prepared according to the electrical angle θ is significantly different from the related art. In the torque control routine described above, the target torque T * is first obtained from the map shown in FIG. 8 according to the detected electrical angle θ and the rotation speed N.
Is obtained. Next, the motor current corresponding to the current phase angle φ is obtained from the map shown in FIG. When the motor current and the current phase angle are obtained in this manner, the target currents id * and i for the d-axis and the q-axis are calculated based on the above equation (1).
q * can be obtained.

In this embodiment, a target current id *, d-axis and target current id *,
iq * is set. On the other hand, instead of the map for providing the motor current and the phase angle, a map for providing the d-axis current and the q-axis current may be used. This way,
Since it is not necessary to calculate the above equation (1), the processing can be speeded up.

According to the motor control device 10 of the present embodiment described above, the pulsation of the torque of the motor 40 can be reduced. FIG. 10 shows the relationship between the torque request value Treq and the output torque. The curve indicated by Told in FIG. 10 shows the torque output by the conventional control method with respect to the required value Treq. As shown, a large pulsation is shown. On the other hand, according to the motor control device of the present embodiment, the output torque can be made substantially equal to the required torque Treq. FIG. 11 shows a phase current flowing during operation of the motor. A curve indicated by iold in FIG. 11 indicates a current when the motor is operated by the conventional control method. A curve indicated by iopt in FIG. 11 indicates a current to be supplied to output the required torque Treq. As shown in the drawing, in the conventional control method, the current value pulsates with respect to the current iopt which should be passed. In contrast, according to the motor control device of the present embodiment,
A current corresponding to the curve ipot can flow.

As described above, according to the motor control device of this embodiment, the motor can be operated with reduced torque pulsation. As a result, according to the motor control device of the present embodiment, the operation efficiency of the motor can be improved.

It should be noted that the torque control of the above embodiment can take several modified forms. For example, in the above embodiment, in step S120, the maps shown in FIGS. 8 and 9 are used to set the target current value. On the other hand, the target current may be set using a function that approximates the curves in FIGS. 8 and 9.

In the above embodiment, the target current is set in accordance with the electrical angle θ by using the maps of FIGS. 8 and 9 regardless of whether the motor 40 is rotating at a low speed or at a high speed. I was When the number of rotations of the motor 40 becomes very high, the process of setting the target current according to the electrical angle θ may not be in time for the rotation of the motor 40. Accordingly, only when the motor 40 is rotating at a relatively low speed, the map considering the electric angle θ as shown in FIGS. 8 and 9 is used, and in other cases, the electric angle θ is not considered. A map similar to the conventional one may be used.

(4) Examples of application of motor control device: In order to show the usefulness of a motor having a motor control device in this embodiment, examples of application of these motors will be described with reference to FIG. FIG. 12 is an explanatory diagram showing a schematic configuration of a hybrid car to which these are applied. A hybrid car is a vehicle equipped with both an engine and a motor. As described below, the hybrid car shown in FIG. 12 has a configuration in which the power of the engine can be directly transmitted to the drive wheels. Such a hybrid car is particularly called a parallel hybrid car.

First, the schematic structure of the hybrid car shown in FIG. 12 will be described. The engine EG is a gasoline engine or a diesel engine used in a normal vehicle. The crankshaft of the engine EG is mechanically connected to the planetary gear PG. Planetary gear P
G is a sun gear SG that rotates at the center, and a planetary carrier PC that revolves while rotating around the sun gear SG.
And a ring gear RG rotatable around the planetary carrier PC. As is well known, the planetary gear PG includes a sun gear SG, a planetary carrier PC,
When the power input / output to any two of the ring gears RG is determined, the power input / output is determined to one of the remaining ring gears RG.

As shown in FIG. 12, in the hybrid car of this embodiment, the crankshaft of the engine EG is connected to the planetary carrier PC. The generator MG1 is connected to the sun gear SG, and the motor GM2 is connected to the ring gear RG. The ring gear RG is coupled to the drive wheels WH via a power transmission mechanism such as a belt. The generator MG1 and the motor MG2 are each a synchronous motor. The generator MG1 and the motor MG2 are electrically connected to the battery BA, and exchange power with the battery BA.

The operation of the engine EG is controlled by the EFIECU. The generator MG1 and the motor M
G2 is electrically connected to the control unit CU via the drive circuits DU1 and Du2, and the operation is controlled by the control unit CU. The control unit CU acquires information necessary for such control by various sensors.
These sensors include, for example, sensors SN1 and SN2 that detect the electrical angle and the rotation speed of the motor MG2. Illustration of other sensors is omitted.

The control unit CU also indirectly controls the operation of the engine EG by outputting information necessary for controlling the engine to the EFIECU.
In correspondence with the motor control device 10 (FIG. 2) in the present embodiment, the control unit CU corresponds to the control ECU 100, the drive circuit DU2 corresponds to the inverter 130, and the motor MG2 corresponds to the motor 40. Current sensors 102 and 103, filters 106 and 107, and AD
C112 and 113 are not shown in FIG.

In the hybrid car having the above configuration, the power output from the engine EG is divided and transmitted by the planetary gear PG. That is, a part is distributed to the sun gear SG and is regenerated as electric power by the generator MG1. This power is stored in battery BA. The remaining power distributed by the planetary gear PG is transmitted to the drive wheels WH via the ring gear RG and used for running the vehicle. The power output from the motor MG2 is also added to the ring gear RG. Control unit CU controls the operation of engine EG, generator MG1, and motor MG2 such that the sum of the power transmitted from engine EG to drive wheels WH and the power output from motor MG2 matches the required power. It is doing. In addition, in such a hybrid car, traveling in various operation modes such as stopping the operation of the engine EG and traveling using only the power output from the motor MG2 is possible.

As described above, since the power output from the motor MG2 can be transmitted to the drive wheels WH, for example, if the output torque from the motor MG2 pulsates, the ride comfort of the vehicle is impaired. In the above-described hybrid vehicle, if the motor control device of the present embodiment is provided, the fluctuation of the torque output from the motor MG2 can be suppressed, and the required torque set according to the traveling state of the vehicle is constantly increased. Since the output can be made, the riding comfort can be improved. Further, by making the motor MG2 operable without torque fluctuation, the operating efficiency of the hybrid car can be improved. In the above-described hybrid car, the generator MG1 is also configured as a synchronous motor, and can function as a motor that receives power supply and outputs torque depending on the operation mode. It is also possible to apply as a device.

In the above description, a parallel hybrid car has been described as an example. However, the motor control device of the present invention is applied to a type of hybrid car in which power output from the engine EG cannot be directly transmitted to the drive wheels WH, that is, a so-called series hybrid car. Is also applicable. Naturally, the present invention can be applied to a so-called electric vehicle without the engine EG.

As described above, the motor control device of the present invention is very useful in that the motor can be smoothly operated without torque fluctuation. In the above description, a hybrid car or an electric car is given as an example, but the application example of the motor control device of the present invention is not limited to this. For example, it is applicable to various devices such as machine tools and home electric appliances.

Although various embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various embodiments can be implemented without departing from the gist of the present invention. For example, in the present embodiment, the torque control is realized by software according to the flowchart shown in FIG. 6, but the same processing may be realized by hardware. Conversely, processing realized by hardware in the present embodiment, for example, detection of an electrical angle, may be realized by software. Further, the electric motor control device of the present invention is applicable not only to a synchronous machine but also to various AC motors such as an induction machine.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing functional blocks of a motor control device of the present invention.

FIG. 2 is an explanatory diagram showing a hardware configuration of the electric motor control device 10.

FIG. 3 is a cross-sectional view of a cross section including a rotation shaft of the motor 40.

FIG. 4 is a cross-sectional view in a cross section orthogonal to a rotation axis.

FIG. 5 is an equivalent circuit diagram of the three-phase synchronous motor 40.

FIG. 6 is a flowchart showing the processing content of a torque control routine.

FIG. 7 is an explanatory diagram showing a relationship between a current phase angle and a torque.

FIG. 8 is an explanatory diagram showing a first map for current setting.

FIG. 9 is an explanatory diagram showing a second map for setting a current.

FIG. 10 is a graph showing torque pulsation with respect to a torque command value.

FIG. 11 is a graph showing a change in a current flowing through a winding.

FIG. 12 is an explanatory diagram showing a configuration of a hybrid vehicle to which the electric motor control device of the present invention is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Motor control apparatus 20 ... Plate stator 22 ... Teeth 24 ... Slot 30 ... Stator 32 ... Coil 34 ... Bolt 40 ... Three-phase synchronous motor 50 ... Rotor 51, 52, 53, 54 ... Permanent magnet 55 ... Rotation Shaft 57: plate-like rotor 60: case 61, 62 ... bearing 71, 72, 73, 74 ... salient pole 100 ... control ECU 102, 103 ... current sensor 106, 107 ... filter 112, 113 ... ADC 114 ... electrical angle Sensor 115 Rotation speed sensor 116 Input port 118 Output port 120 CPU 122 ROM 124 RAM 126 Clock 130 Inverter 132 Battery 202d, 202q PI control unit 204 2-phase / 3-phase conversion unit 206 PWM control unit 208: energizing unit 210: three-phase / two-phase conversion unit 212: current setting unit 21 ... current map 216 ... request torque setting section

Claims (5)

[Claims] An electric motor for controlling an operation of a motor for rotating a rotor by controlling a polyphase alternating current flowing through a winding and utilizing a rotating magnetic field generated in the winding when the polyphase alternating current flows. A control device, comprising: setting means for setting a required torque to be output from the electric motor; electric angle detecting means for detecting an electric angle defining an electric rotation position of the rotor; and outputting the required torque. A current setting means for setting a current flowing through the winding in consideration of not only the required torque but also the detected electrical angle, and an energizing means for flowing the set current through the winding. apparatus. 2. The motor control device according to claim 1, wherein the current setting means stores a relationship between an electric angle and a torque and a current to be passed through the winding to output the torque. An electric motor control device comprising: a reference unit that obtains, based on the required torque and the electrical angle, a current to be passed through the winding to output the required torque with reference to the relationship. 3. The motor control device according to claim 1, further comprising: rotation speed detection means for detecting a rotation speed of a rotor of the motor, wherein the current setting means includes the detected rotation speed. The motor control device is a means for setting the current in consideration of the following. 4. The motor control device according to claim 1, further comprising: a rotation speed detection unit configured to detect a rotation speed of a rotor of the motor, wherein the current setting unit determines that the rotation speed of the motor is a predetermined value. An electric motor control device, which is means for considering the detected electric angle only when the value is equal to or less than the value. 5. An electric motor for rotating a rotor by utilizing a rotating magnetic field generated in a winding when a polyphase alternating current is applied to the winding to control an operation of the electric motor by controlling a current flowing in the winding. A method for controlling a motor to be controlled, comprising: (a) setting a required value of a torque to be output from the motor;
Detecting an electrical angle that defines an electrical rotational position of the rotor; and (c) a relationship stored in advance between the electrical angle and the torque and a current to be passed through the winding to output the torque. Determining a current to be passed through the winding to output the required torque, by referring to
Flowing the set current to the winding.