JPH08331895A - Motor and control method therefor - Google Patents

Abstract

PURPOSE: To obtain an electric automobile which can run comfortably by switching the stator windings in series or parallel to feed each stator winding with a current for rotating the rotor and/or a field current for increasing the magnetic force of the rotor thereby varying the rotation and torque continuously from a low level to a high level. CONSTITUTION: When a transition is made from region 2, an operation similar to that in the region 2 is performed in region 4, i.e., the stator windings are connected in series by a windings switching means and only a rotating current is fed to each stator winding from a current supply means. Torque T2 corresponds to the starting torque of vehicle on a flat land. When a transition is made from region 3 or 1 to region 2, the stator windings are connected in parallel by the winding switching means and a combination current of rotating current and field current is fed to each stator winding from the current supply means. Consequently, the number of switching times of winding can be decreased and the vehicle is not subjected to impact every time when the speed is changed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor suitable for a permanent magnet type AC servomotor which controls winding switching, and a control method thereof.

[0002]

2. Description of the Related Art Conventionally, a motor used in an electric vehicle or the like requires a characteristic that a small torque can be turned up to a high rotation even though a large torque is required at a low rotation of the motor. It was For this reason,
Generally, it has been considered that the best method is to use a field weakening induction motor.

In consideration of efficiency and the like, instead of the field weakening type induction motor, a winding switching type permanent magnet type A is used.
In some cases, even if a small torque was used, high rotation was possible by using a C servo motor and switching windings.

However, the field-weakening induction motor requires a field current, which causes a loss due to winding resistance and the like, and is therefore less efficient than the permanent magnet AC servomotor.

Further, in the winding switching type permanent magnet type AC servo motor, the characteristics are stepwise as shown in FIG. 6, and this characteristic change makes the riding comfort of the electric vehicle extremely bad, so that comfortable running is possible. Was a big obstacle to me.

Therefore, in order to solve the problems of the prior art, the present invention is capable of continuously changing from a low rotation speed to a high rotation speed and from a large torque to a small torque by a simple structure and method and is comfortable to run. It is an object of the present invention to provide a motor and a method of controlling the motor, which is particularly suitable for electric vehicles.

[0007]

In order to solve the above-mentioned problems, a motor according to the present invention comprises a rotor formed of a permanent magnet, a stator having a plurality of windings, and each winding of the stator connected in series or in parallel. And a current supply means for supplying a rotating current for rotating the rotor and / or a field current for increasing the magnetic force of the rotor to each winding of the stator.

A method of controlling a motor in which the output characteristic of the motor is changed by switching the connection of the windings of the stator in series or in parallel, wherein a rotating current and / or a field current for rotating the motor is applied. It is characterized in that the output characteristics of the motor are changed by passing the current through the winding of the stator.

In particular, the windings are connected in series and
By supplying only the rotation current to the winding, a torque higher than a predetermined torque (high torque) and a rotation speed lower than the predetermined rotation speed (low rotation speed) can be obtained.

Further, the windings are connected in parallel, and
A torque (low torque) equal to or lower than a predetermined torque is obtained by passing only a rotating current through the winding.

Further, the windings are connected in parallel and a current obtained by combining the rotation current and the field current is passed through the windings, so that the torque is higher than a predetermined torque (high torque) and higher than the predetermined rotation speed. Make sure to obtain the rotation speed (high rotation speed).

[0012]

EXAMPLE An example according to the present invention will be described in detail. The motor used in this example was a winding-switching permanent magnet AC servo motor connected to the wheels of an electric vehicle. And on the winding of the stator of this motor,
A control unit that applies current similar to that of the field-weakening induction motor is provided.

That is, specifically, a rotor formed of a permanent magnet, a stator having a plurality of windings, winding switching means for connecting each winding of the stator in series or in parallel, and each winding of the stator. A motor is provided with a current supply means for supplying a rotating current for rotating the rotor and / or a field current for increasing the magnetic force of the rotor.

Next, the current flowing through the winding of the motor stator will be described. In a region 1 shown in FIG. 1 (a low torque region where the required torque is equal to or lower than the predetermined torque T1, where the predetermined torque T1 is, for example, a torque at which a general vehicle can climb a slope having a gradient of several%), As shown in, the stator windings of the motor are connected in parallel, and although the torque that can be output by the motor is small, it can be rotated to a high rotation range.

The current flowing through the stator winding may be a current only for generating torque in the motor, that is, only a rotating current. By doing so, it is possible to obtain the same efficiency as that of the permanent magnet type servo motor.

Region 2 of FIG. 1 (region in which the required torque is higher than the predetermined torque T1 (high torque) and the required rotation speed is lower than the predetermined rotation speed (low rotation speed), where the predetermined rotation speed is flat (For example, about 30 to 40 km / h), the stator windings are connected in series as shown in FIG. 3, and when the same current as that of the region 1 is applied to this winding, the torque of about 3 times is increased in this embodiment. Is obtained. However, since the number of turns of the winding is three times, the induced voltage is three times that in the case of region 1, and the maximum rotation speed of the motor is 1 in the case of region 1.
It can only be rotated up to / 3.

In the region 3 of FIG. 1 (the region where the required torque is higher than the predetermined torque T1 (high torque) and the required rotation speed is higher than the predetermined value (high rotation speed)), the same winding connection as in the region 1 is performed. As shown in FIG. 4, the current is a combination of the torque current (rotating current) vector AB and the field current vector CA flowing in the direction of increasing the magnetic flux density of the permanent magnet of the rotor, that is, the actual current of the current vector CB. Therefore, it can be driven with a smaller current than the conventional field weakening induction motor.

That is, in the conventional field-weakening induction motor whose characteristics are shown in FIG. 5, the current vector for generating the same magnetic force in FIG. 4 is DB, which is the amount of the DC 'vector (here, The size of the vector BC = the size of the vector BC ′) The current can be driven with a small current, and the efficiency can be improved accordingly.

In addition, the upper limit of this area 3 is fixed (see FIG. 1).
Constant output line CP) from P1 at the end of the constant torque line CT in FIG. 1 to P2 at the end of the constant output line CP.
It is possible to change continuously up to the point, it is possible to obtain a good and smooth acceleration feeling equivalent to a field weakening induction motor, and it is possible to obtain a very comfortable running sensation in an electric vehicle.

A region 4 in FIG. 1 (for example, a region where an electric vehicle normally runs) is a region from the region 2 to another region or from another region to the region 2, and chattering is prevented by switching windings. It is set as an area to do. In this region 4, when moving from the region 2 to another region, the same operation as in the region 2, that is, the winding switching means connects the stator windings in series, and the current supply means connects the stator windings. Only rotating current is applied to. The torque T2
Corresponds to the torque when the vehicle starts on the flat ground.

On the contrary, when moving from the area 3 or the area 1 to the area 2, the same operation as the area 3 is performed. That is, each winding of the stator is connected in parallel by the winding switching means, and a combined current of the rotating current and the field current is supplied to each winding of the stator by the current supply means.

In this way, it is possible to reduce the number of times the windings are switched, and it is possible to carry out a very comfortable running without receiving an impact at each shift, as in the conventional case.

In this embodiment, the control method described above is only an example and is not limited to this, and various modifications may be made without departing from the scope of the present invention.

[0024]

As described above, according to the motor and its control method of the present invention, the motor and its control capable of continuously changing from a large torque to a small torque, which is optimum for an electric vehicle, from low rotation to high rotation. A method can be provided.

When the required torque is less than a predetermined value, the windings of the motor are connected in parallel and only the rotating current is passed through the winding. When the required torque is higher than the predetermined value and the required rotation speed is lower than the predetermined value, the windings are connected in series and only the rotation current is passed through the winding. When the required torque is higher than the predetermined value and the required rotation speed is higher than the predetermined value, the windings are connected in parallel and a current obtained by combining the rotation current and the field current is passed through the winding.・ When the required torque shifts from a region below the predetermined value to a region where the required torque is higher than the predetermined value and the required rotation speed is lower than the predetermined value, or when the required torque is higher than the predetermined value and the required rotation speed is higher than the predetermined value. When shifting from the region to the region where the required torque is higher than the predetermined value and the required rotation speed is lower than the predetermined value, the windings are connected in parallel and the combined current of the rotating current and the field current is applied to the winding. Shed on. When shifting from a region where the required torque is higher than a prescribed value and a required rotational speed is lower than the prescribed value to a region where the required torque is a prescribed value or less, or to a region where the required torque is higher than the prescribed value and the required rotational speed is higher than the prescribed value. , The windings are connected in series and only the rotating current is passed through the windings. By performing the control as described above, the number of shifts of the motor can be reduced, the high efficiency of the motor can be maintained, and it is possible to enjoy extremely comfortable running in the electric vehicle.

[Brief description of drawings]

FIG. 1 is a characteristic diagram showing a relationship between a rotation speed and a torque of a motor according to an embodiment of the present invention.

FIG. 2 is a wiring diagram showing parallel connection when switching windings of a stator.

FIG. 3 is a wiring diagram showing a series connection in switching windings of a stator.

FIG. 4 is a diagram illustrating composition of current vectors.

FIG. 5 is a characteristic diagram showing the relationship between the rotational speed and torque of a conventional motor.

FIG. 6 is a characteristic diagram showing the relationship between the rotation speed and torque of another conventional motor.

[Explanation of symbols]

 CT: Constant torque line PT: Constant output line

Claims (2)

[Claims] 1. A rotor formed of a permanent magnet, a stator having a plurality of windings, winding switching means for connecting each winding of the stator in series or in parallel, and a rotor for each winding of the stator. A motor provided with a current supplying means for supplying a rotating current for rotating and / or a field current for enhancing the magnetic force of the rotor. 2. The motor according to claim 1, wherein each winding of the stator is connected in series by the winding switching means, and only the rotating current is flowed to each winding of the stator by the current supply means. A high torque / low rotation speed state by means of connecting the windings of the stator in parallel by means of the winding switching means, and supplying only the rotating current to the windings of the stator by means of the current supply means, thereby reducing the low torque. In this state, each winding of the stator is connected in parallel by the winding switching means, and the rotation current and the field current are caused to flow from the current supply means to each winding of the stator, thereby achieving high torque / high rotation. A method of controlling a motor, which is characterized by setting a number of states.