KR20150041218A - motor and the controlling method of the same - Google Patents

Abstract

The present invention relates to a motor and a method of controlling the same. More particularly, the present invention relates to a driving device for an electric vehicle and a method of controlling the same. Also, the present invention relates to a driving motor for an electric vehicle and a method of controlling the same. According to an embodiment of the present invention, in a motor which includes a rotor having a field magnet wire and a stator having an armature wire, the present invention is to provide a motor which includes a motor control part which controls the motor by a single current combination which minimizes the sum of a armature current value and a field magnet current value among multiple combinations of the armature current value and the field magnet current value which can be applied to generate the same torque.

Description

[0001] The present invention relates to a motor and a control method thereof,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor and a control method thereof, and more particularly, to a driving apparatus for an electric vehicle and a control method thereof. The present invention also relates to a drive motor for an electric vehicle and a control method thereof.

Generally, an automobile is driven through an engine. A variety of carbon-based materials such as gasoline and light oil are used to drive the engine, which can lead to a large amount of carbon emissions. Therefore, in order to reduce the carbon gas emitted from the automobile, many electric automobiles or hybrid automobiles that drive the automobile using the electric battery have been developed.

An electric vehicle refers to a vehicle in which a vehicle is driven by driving a motor through electricity charged in a battery. A hybrid vehicle refers to a vehicle that selectively or simultaneously drives an engine and a motor, depending on conditions. Therefore, hybrid cars can also be called electric vehicles. This is because the hybrid vehicle also includes a drive motor that uses a battery.

The output performance of an electric vehicle using a motor is very close to the output performance of the motor. Therefore, since the performance of the motor can determine the performance of the electric vehicle, the structure, shape and size of the motor and the control method thereof are very important.

The motor is basically a device that uses electric energy to obtain torque (mechanical torque) at the rotating shaft. However, in many motors, only the speed is the object of control, and the torque of the motor is not directly controlled. This is because the torque of the motor appears as a change in speed after low-frequency filtering by mechanical inertia.

Therefore, in general, the average torque is more important than the instantaneous torque of the motor, and the speed control of the motor or the motor by the average torque becomes the main object of control. This is also true of motors for driving electric vehicles.

However, unlike a general motor, a motor for driving an electric car is required to have a rotational speed controlled to 12,000 RPM or more. That is, since the rotation speed band is very wide, there is a very difficult problem in manufacturing or controlling such a motor.

1 is a graph showing a relationship between an output torque (unit Nm), a rotation speed (unit RPM), and an output (unit Kw) of a general electric vehicle drive motor.

As shown, the torque, output, and speed patterns are varied based on the rated speed Nbase. That is, the output torque is constant and the output gradually increases until the speed increases gradually to the rated speed. Above the rated speed, as the speed increases, the output torque decreases and the output becomes constant. That is, at a constant output torque, the speed gradually increases to the rated speed, and the output torque decreases at or above the rated speed. Further, the output gradually increases at a constant output torque, and the output becomes constant at a speed higher than the rated speed. Of course, this assumes that the same command torque is input.

Therefore, if the command torque is constant, it can be seen that the relationship pattern of output, torque, and speed (number of revolutions) is the same regardless of the command torque value as shown in FIG. In other words, it can be seen that the torque curve a at the maximum command torque Tmax and the torque curve b at the arbitrary command torque T are formed in the same pattern.

1, it can be seen that when the same command torque is inputted, an output torque substantially equal to the command torque occurs at a speed lower than the rated speed. It is also understood that, at a speed higher than the rated speed, an output torque that gradually decreases from the command torque is generated. That is, it can be seen that as the speed further increases, the output torque becomes smaller than the command torque.

Here, the operation region below the rated speed may be referred to as a constant torque operation region, and the operation region beyond the rated speed may be referred to as a constant output operation region.

The constant torque operation region can be regarded as an operation region in which a constant torque is generated regardless of the rotational speed with respect to the same command torque. The constant output operation region can be regarded as an operation region in which the torque is reduced and the output is constantly generated as the rotational speed increases with respect to the same command torque.

1 is a graph that does not take into account the traveling environment and time of the electric vehicle. This is because, in the same driving environment, the time to reach the rated speed will become shorter as the command torque becomes larger, and the time from the flat terrain to the rated speed will be shorter than the inclined terrain in the case of the same command torque.

The specifications of the drive motor or electric vehicle can be expressed through the maximum output torque Tmax, the rated speed Nbase, and the maximum output Kw_max. Of course, it can also be expressed through the maximum speed Nmax.

However, the specification of the drive motor may vary from manufacturer to manufacturer. In addition, the required size and shape of the driving motor or driving device may vary from one electric car to another. Therefore, it is very important to improve the performance of the drive motor in the same or similar specifications.

In the electric motor drive motor, there is a field winding motor that can control the field current to control its output. In the field winding motor, the output is controlled so as to follow the input output (command torque), so that when the command torque is inputted, the output of the motor is controlled so as to follow the command torque by controlling the field current. Of course, as will be described later, the command torque and the actual output torque are different in the middle-speed range.

Here, the input output may be calculated in proportion to the angle of the accelerator. That is, the larger the angle at which the user steps on the accelerator, the larger the command torque becomes, and the larger the command torque, the larger the field current can be controlled. In other words, as the command torque value increases, the field current value applied to the motor becomes larger.

Fig. 2 shows an embodiment of a control flow chart of a field coil motor (field coil motor) for controlling the motor output by controlling field current and armature current of the motor. When the field coil motor is used as a driving motor for an electric vehicle, the following flow can be controlled.

First, the command torque is calculated (S2). This command torque can be calculated through the angle of the accelerator pedal. That is, when the driver depresses the accelerator pedal, the angle of the accelerator pedal is inputted (S1), and the command torque is calculated through the angle (S2).

When the command torque is calculated or calculated, the motor is controlled to follow the command torque (S3), and the motor is driven through this control (S6).

The command torque follow-up control S3 is performed while calculating the field current value If and the armature current value Ia inputted to the command torque (S4) and applying the calculated current values to the motor (S5). Then, the motor is driven in accordance with the command torque through the applied current values (S6). Of course, the output torque, speed (revolution) and temperature of the motor are fed back (S7) so that the output of the motor can be controlled to be maximally similar or equal to the command torque.

The torque (T) of the field coil motor can be expressed by the following equation.

[Equation 1]

Torque (T) = Pn {(? F x iq) + (Ld - Lq) x idiq}

Ld is the magnetic flux component reluctance, Lq is the torque component relay, and Lq is the flux component reluctance. In the above equation (1), Pn is the number of poles of the motor,? F is the field flux, iq is the torque component current value of the armature current Ia, id is the flux component current of the armature current, Respectively.

From the equation (1), it can be seen that the constant torque curve shown in FIG. 3 can be generated on the field current If and armature current Ia coordinates. That is, it can be seen that a large number of combinations of the field current value If and the armature current value Ia (hereinafter referred to as "current combination") for generating the same torque can be generated.

The field current value determined by the product of the ratio of the command torque to the maximum torque (torque ratio, T / T_max) and the maximum field current value If_max can be used to facilitate the control of the motor, that is, the command torque follow- have. This can be referred to as a torque ratio reference control.

In order to obtain the maximum torque, the field current value should be maximized. Therefore, when the command torque is input, the field current value can be simply calculated by the following equation.

&Quot; (2) "

If = If_max * T / T_max

As shown in Equation (2), in the torque ratio reference control, the input field current value If can be calculated to be proportional to the command torque value to be input. For example, when the maximum field current is 9.8 A and the maximum output torque is 280 Nm, the input field current value can be simply calculated as 4.9 A when the command torque is 140 Nm.

Therefore, the torque ratio reference control can be regarded as a control method in which the field current value and the armature current value are determined and input based on the maximum torque value, the maximum field current value, and the command torque. Therefore, when the command torque is determined, the field current value corresponding thereto can be determined without additional calculation, and accordingly, the armature current value is determined. Therefore, the control of the motor can be easily performed.

Specifically, for such torque ratio reference control, a current combination corresponding to each command torque value may be provided in the form of a look-up table. Therefore, once the command torque value is input, the single current combination input through the lookup table can be automatically determined without any additional calculation.

However, in the conventional field winding motor, the field current value is determined regardless of the speed. That is, when the same command torque is input, the field current value is determined to be the same regardless of the speed. In other words, even if the actual output torque becomes smaller than the command torque (at or above the rated speed), the field current value of the same value is determined.

For example, when If_max is 9.8 A and T_max is 280 Nm, the field current is always determined to be 4.9 A regardless of the speed when the command torque is 140 Nm. That is, the same field current value is always input regardless of the constant torque region (constant torque operation region) or the constant output region (constant output operation region). Therefore, the copper loss caused by the field current is constantly generated at the same command torque.

However, if the field current value is constant regardless of the rotation speed N, there is a problem that the coiling loss in the stator is large and the efficiency is lowered in the middle-speed region. This is because, in the middle speed range, the command torque is larger than the actual output torque.

Here, the middle / high speed range means a range exceeding the rated speed (constant output range, weak field range), and since weak field control is performed in such a range, large fluctuation is generated in the stator due to the weak field control. The efficiency of the motor as a whole can be greatly reduced through this.

Generally, when the rotor rotates, an induced electromotive force is generated in the stator in a direction that interferes with the rotation of the rotor. This is called a back electromotive force. Since the counter electromotive force is proportional to the time variation of the rotor rotation, the amount of generation of the back electromotive force is small when the rotor rotates at low speed. Therefore, at low speed, the counter electromotive force does not greatly influence the control of the motor.

However, the counter electromotive force generated when the rotor rotates at a high speed becomes larger in proportion to the rotor speed. Therefore, it is difficult to obtain the output speed or output of the desired motor at high speed. Such a problem is called field weakening control in which a reverse flux is generated in a direction opposite to the magnetic flux which generates the back electromotive force and the field flux is reduced.

Specifically, weak field control is performed by increasing the negative direction magnitude of the flux component current id of the armature current Ia. This flux component current id becomes larger as the speed is increased. However, unlike the torque component current (iq) of the armature current (Ia), id is independent of the output of the motor, id has a problem that very large coiling of the stator is caused. Therefore, the total motor loss of the motor significantly increases in the middle-speed operation region (constant output region), and the efficiency of the motor may be reduced.

This decrease in efficiency can be similarly generated in the constant torque region as well as in the non-constant output region. This is because, in the constant torque region, the coarse loss can be relatively large due to the magnitude of the armature current value itself.

Therefore, there is a need to provide a motor and a control method thereof that can improve the efficiency by reducing the motor loss of the entire motor, regardless of the operation region of the motor.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the problems of the conventional motor and the control method thereof.

Through the embodiments of the present invention, it is intended to provide a motor capable of improving the efficiency in the entire operation region and a control method thereof.

The present invention provides a motor and a control method thereof that can improve the efficiency by minimizing the total copper loss by taking into account the relationship between the current value applied to the motor and the total copper loss.

Through the embodiments of the present invention, it is intended to provide a motor and its control method capable of remarkably improving efficiency particularly in a low-speed low-torque operation region.

According to an aspect of the present invention, there is provided a motor including a rotor having a field winding and a stator having an armature winding, And a motor control unit for controlling the field current value If to be gradually decreased as the number of revolutions of the motor increases to reduce copper loss in the winding.

It is preferable that the current combination If and Ia of the armature current value Ia applied to the armature winding corresponding to the applied field current value If and the field current value If is a single combination for the same torque Do.

It is preferable that the single combination is a current combination in which the total motor power loss is lowest among a plurality of current combinations for the same torque.

In the above embodiment, it is also preferable to apply the current combination to the motor such that the total motor motor loss is the lowest among a plurality of current combinations for the same torque in the constant torque operation.

The field current value in the single combination is determined by the product of the ratio of the command torque to the maximum torque (torque ratio, T / Tmax) and the maximum field current value Ifmax (torque ratio reference control) in the constant torque operation region Is substantially larger than the field current value. Of course, there will be no difference in field current values at critical points such as when the command torque value is maximum and when it is minimum.

This is because, in the constant torque operating region, the total copper loss due to the self-magnitude of the armature current value is larger than the total copper loss due to the self-magnitude of the field current value. Therefore, in order to generate the same output torque, it is more preferable in terms of efficiency to have a relatively larger field current value.

The field current value in the single combination is preferably smaller than the field current value determined by the torque ratio reference control in the constant output operation region. This is because, in the constant output operation region, the total coil loss becomes larger due to weak field control through the armature current value. Therefore, it can be seen that, in practice, it is more effective to reduce the field current value and perform the weak field control to some extent in terms of total copper loss.

According to an embodiment of the present invention, there is provided a motor including a rotor provided with a field winding and a stator having an armature winding, wherein a total motor motor loss due to the field winding and the armature winding It is possible to provide a motor including a motor control section for controlling the motor with a single current combination of a field current value and armature current value at which the total motor hand movement is minimized for the same torque.

The field current value in the single current combination is obtained by multiplying the ratio of the command torque to the maximum torque (torque ratio, T / Tmax) by the maximum field current value Ifmax (torque ratio reference control) in the constant torque operation region It is preferable that the field current value is substantially larger than the determined field current value.

It is preferable that the field current value in the single current combination is smaller than the field current value determined in the torque ratio reference control in the constant output operation region.

It is preferable that the field current value in the single current combination is controlled so as to gradually decrease as the number of rotations of the motor increases. That is, as the number of rotations of the motor increases, the magnitude of the counter electromotive force becomes larger. This means that when the weak field control is performed using the armature current value, the energy consumed is further increased.

However, according to the present embodiment, by further reducing the field current value, the energy consumed by the armature current value can be reduced.

According to an aspect of the present invention, there is provided a motor including a rotor provided with a field winding and a stator having an armature winding, wherein the field current value And a motor control unit for controlling the motor with a single current combination in which the sum of the field current value and armature current value is the smallest among a plurality of combinations of armature current values.

This is due to the fact that the copper loss in the conductor is proportional to the square of the current value. As described above, a plurality of current combinations can be obtained for generating the same output torque. A single current combination that minimizes copper loss in such a plurality of current combinations can be determined through a simple operation. Therefore, it is possible to easily determine a single current combination in which the arithmetic sum of the field current value and the armature current value is the minimum.

It is preferable that the field current value in the single current combination has the same value regardless of the rotational speed of the motor in the constant torque operating region.

It is preferable that the constant torque operation region is an operation region in which a constant torque is generated regardless of the rotational speed with respect to the same torque in the section where the rotational speed is less than the rated speed.

The field current value in the single current combination is obtained by multiplying the ratio of the command torque to the maximum torque (torque ratio, T / Tmax) by the maximum field current value Ifmax (torque ratio reference control) in the constant torque operation region It is preferable that the field current value is substantially larger than the determined field current value.

It is preferable that the field current value in the single combination has a value which gradually decreases as the rotational speed of the motor increases in the constant output operation region.

It is preferable that the constant output operation region is an operation region in which the torque is reduced as the rotational speed increases and the output is constantly generated with respect to the same command torque in the section where the rotational speed is equal to or higher than the rated speed.

The field current value in the single current combination is obtained by multiplying the ratio of the command torque to the maximum torque (torque ratio, T / Tmax) by the maximum field current value Ifmax (torque ratio reference control) It is preferable that the field current value is substantially smaller than the determined field current value.

According to an aspect of the present invention, there is provided a method of controlling a motor including a rotor having a field winding and a stator having an armature winding, the method comprising: calculating a command torque; Determining a single current combination of a field current value and an armature current value through which the motor total copper loss is minimized through the calculated command torque or the current output torque; And a control method of the motor for controlling the output of the motor by applying the determined single current combination.

And determining whether the rotational speed is less than the rated rotational speed (the constant torque region) or the rated rotational speed (the constant output region) through the rotational speed of the rotor to be fed back.

If it is determined in the determination step that the current is in the constant torque region, the single current combination is determined through the command torque, and when it is determined that the constant current region is the constant output region, the single current combination is determined through the current output torque.

The current output torque may be determined by the current output torque to be fed back or the number of rotations of the feedback rotor and the command torque.

If it is determined to be the constant output region in the determining step, weak field control is performed to increase the magnitude of the magnetic flux component current id in the negative direction of the armature current value.

Through the embodiments of the present invention, it is possible to provide a motor capable of improving the efficiency in the entire operation region and its control system.

It is possible to provide a motor and a control method thereof that can increase the efficiency by minimizing the total hand loss by taking into account the relationship between the current value applied to the motor and the total copper loss through the embodiments of the present invention.

Through the embodiments of the present invention, it is possible to provide a motor and a control method thereof that can remarkably improve the efficiency particularly in the low-speed low-torque operation region.

1 is a graph showing the relationship between output, torque, and rotation speed of a general motor;
2 is a control flow chart of a conventional motor;
FIG. 3 shows a constant torque curve according to a field current and an armature current;
4 is an exploded perspective view of a field winding motor applicable to an embodiment of the present invention;
5 is a simplified block diagram of the motor shown in FIG. 4;
6 is a graph showing a total copper loss curve on a constant torque curve according to a field current and an armature current;
7 is a control flow chart of a motor according to an embodiment of the present invention;
FIG. 8 illustrates an embodiment of a current combination using a conventional torque ratio reference control; FIG.
9 is an efficiency map generated due to the current combination shown in Fig. 8;
10 is a diagram illustrating an embodiment of a current combination using efficiency reference control according to an embodiment of the present invention;
11 is an efficiency map generated due to the current combination shown in Fig. 10;
12 is a map showing efficiency differences between the efficiency maps shown in Figs. 9 and 11. Fig.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is an exploded perspective view showing a drive motor 1 for an electric vehicle that can be applied to the embodiments according to the present invention. More specifically, one embodiment of the field winding motor 1 is shown.

The motor (1) may include a stator (10) and a rotor (20). The rotor 20 rotates with respect to the stator 10 through an electromagnetic action with the stator 10.

The stator 10 may include a stator core 11. Here, the stator 10 may include a stator coil 12 to form a magnetic flux. The stator coil 12 is wound on the stator core 11. [ Therefore, the stator 10 may be referred to as an electromagnet.

The rotor 20 may be provided to rotate inside the stator 10.

The rotor 20 may include a rotor core 21. In addition, the rotor 20 may include a rotor coil 22 wound around the rotor core 21.

Here, the rotor coil 22 may be referred to as a field coil, and the stator coil 12 may be referred to as an armature coil. Therefore, the output of the rotor 20 can be controlled through the field current If and the armature current value Ia respectively applied to the field coil and the armature coil.

The rotor 20 is connected to a rotary shaft 30, and the rotary shaft 30 can be connected to a drive shaft of an unillustrated automobile. Therefore, the torque and the rotation speed of the rotor 20 can be transmitted to the drive shaft of the automobile through the rotation shaft 30. [ In order to connect the rotary shaft 30 and the drive shaft, a hollow 31 may be formed in the rotary shaft 30. By inserting the drive shaft into the hollow 31, the connection of both can be made.

Such a hollow shape facilitates the connection of both, and it is possible to prevent the length of the motor or the driving device from becoming long for the connection of both. In addition, it is not necessary to provide a separate space for connecting the drive shaft and the rotary shaft 30 to the outside of the motor.

End plates 51 and 52 may be provided on the front and rear of the rotor 20, respectively. Thereby, the field coil 22 can be stably fixed. That is, the field coil 22 can be stably fixed to the rotor core 21 through the end plates 51 and 52 even though the field coil 22 rotates.

The front bracket 61 and the rear bracket 62 may be provided on the front and rear sides of the stator 10 and the rotor 20, respectively. In addition, a frame 80 may be provided to surround the stator 10 and the rotor 20. The stator (10) and the rotor (20) may be provided in the brackets and the frame.

A front bearing 63 may be provided in front of the rotary shaft 30 and a rear bearing 64 may be provided at a rear side thereof. The rotor 20 and the rotary shaft 30 can be rotatably supported with respect to the brackets through these bearings. The bearings are each supported on the brackets. Therefore, the brackets 61 and 62 may be referred to as bearing housings.

The stator 10 can be stably fixed to the inside of the frame 80. In addition, both sides of the frame 80 may be coupled to the front bracket 61 and the rear bracket 62, respectively.

A cooling tube 90 may be provided to prevent overheating of the motor. The cooling tube 90 may be provided in the form of a coil and may be interposed between the stator 10 and the frame 80. Thus, it may be possible to cool the stator 10 and the frame 80 directly as the cooling water flows through the cooling tube 90. That is, the cooling cooling tube 90 may be in direct contact with the stator 10 to enable cooling by heat conduction.

In addition, an air flow device for generating an air flow in the motor 1, specifically, the internal space formed by the frame 80 and the brackets, may be provided. The air flow device may be provided in the form of a fan or blades (41, 42). The blade may be coupled with the rotation shaft 30 to rotate together with the rotation of the rotation shaft. And may be provided in front of and behind the rotary shaft 30, respectively.

A pair of slip rings 70 and a pair of brushes 71 may be provided outside the rear bracket 62. The slip ring 70 is coupled to the rotary shaft 30 and a field current flows through the slip ring 70 to the field coil 22. [

That is, the slip ring 70 and the brush 71 may be configured to allow a field current to flow from the outside of the rotor 20 to the rotating field coil 22. In other words, the field current may be supplied from a DC power source (e.g., a battery) through the brush 71 and the slip ring 70.

The rear bracket 62 may be formed to fix the inlet 91 for supplying the cooling water to the cooling coil 90 and the outlet 92 for the cooling water to be recovered or to connect to the outside. In addition, a connection portion for supplying armature current may be provided in the rear bracket 62. [

Hereinafter, the motor control unit and the circuit for controlling the motor 1 will be described in detail with reference to FIG.

The motor (1) is supplied with DC power through a battery (100). Specifically, the field coil (rotor coil) 22 and the armature coil (stator coil) 12 may be connected in parallel with each other.

The field current value If applied to the field coil and the armature current value Ia applied to the armature coil can be determined through the motor controller 230. [ The field current value determined through the motor controller 230 may be applied to the field coil 22 through the field current controller 210. In addition, the value of the armature current determined through the motor controller 230 may be applied to the armature coil 12 via the inverter circuit 220. 5 shows an example in which a DC current is converted into an AC current of three phases through an inverter circuit 220 and is applied as an armature current. Accordingly, the motor controller 230 may include an inverter driver for driving the inverter circuit 220. [

The field current controller 210, the motor controller 230, and the inverter circuit 220 may be provided as one unit. That is, they can be configured as one unit to facilitate manufacture, handling, and installation. Therefore, all of them can be referred to as the motor control unit 200. [ In addition, the motor control unit 200 may be referred to as an inverter. Therefore, in this case, the inverter includes the field current controller 210, the inverter driving circuit (not shown), and the inverter circuit 220.

The motor controller 230 or the motor controller 200 can receive a lot of information through the rotor 20 and the stator 10. For example, the current speed of the rotor 20, the rotational position of the rotor, the current applied to each phase coil (the current corresponding to u, v and w in the case of the three phases), the torque and the temperature of the stator 10 You can get information about. In addition, information for calculating or calculating the current command torque can be received.

Therefore, the motor controller 230 or the motor controller 200 can control the current combination to be properly applied through the command torque and current state information (output torque, rotation speed, temperature, voltage value, current value) have. That is, feedback control can be performed. To this end, various sensors such as a temperature sensor, a current sensor, a Hall sensor, and a resolver may be provided. In FIG. 5, these sensors are shown with reference numeral 240 in one configuration for convenience.

Hereinafter, a method of controlling a driving motor according to an embodiment of the present invention will be described in detail.

According to an embodiment of the present invention, it is possible to provide a control method of a motor capable of reducing the total coiling loss of the motor caused by the field current value If and the armature current value Ia, thereby improving the efficiency.

As described above, it is theoretically possible to combine a very large field current If and armature current Ia with respect to the same command torque. That is, a myriad of current combinations are possible. This is because both the field current and the armature current value are proportional to the torque. As shown in Fig. 3, as to the same torque, generally, as the field current value becomes larger, the armature current value becomes smaller, and as the field current value becomes smaller, the armature current value becomes larger.

In the conventional torque ratio reference control, the same field current value If is always determined for the same command torque, and accordingly, the armature current value Ia is determined through the constant torque curve shown in Fig.

However, since the field current value is determined regardless of the rotational speed of the rotor, the torque ratio reference control has a problem in that the efficiency of the motor due to the hand loss is lowered.

The total copper loss (the sum of the stator copper loss and the rotor copper loss) in the field winding motor can be expressed by Equation (3) below.

&Quot; (3) "

Wc = I ² + I ² aRa fRf

From equation (3), it can be seen that the total copper loss Wc can be expressed as the sum of the rotor copper stiction (I ² aRa) and rotor copper loss (I ² fRf). The resistances (Ra, Rf) of the armature coils and the field coils are proportional to the resistivity and the coil length, and inversely proportional to the coil cross-sectional area. Therefore, since Ra and Rf can be constants, it can be seen that the total copper loss increases as the field current value and the armature current value become larger.

Actually, the field coil resistance Rf and the armature coil resistance Ra may be different from each other. That is, the scales of both may be different. However, it may be assumed that both are the same. In addition, the scale of Ia and If may be different. Since these conditions can be variously modified, the shape of the total curvature curve represented by Equation (3) may be variously modified.

Referring to Equations (1) and (3), it can be seen that there are numerous combinations of currents for generating the same torque. One of the methods for selecting a specific current combination among a plurality of current combinations may be referred to as a conventional torque ratio reference control.

In this embodiment, unlike the torque ratio reference control, it is possible to select a specific current combination that minimizes total copper loss using Equation (3), and thereby provide an efficiency reference control for controlling the motor.

FIG. 6 shows a total curvature curve appearing on a constant torque curve having a specific value. In other words, the change in the total copper loss caused by a plurality of current combinations for generating a specified command torque is shown.

It can be seen from FIG. 6 that the total curvature curve has a convex curved behavior downward, so that a particular combination of currents with a minimum total copper loss value can be determined.

In other words, it can be seen that the motor can be controlled by the combination of If and Ia nearest to the constant torque curve, thereby minimizing total copper loss.

6 is a graph showing a pattern of a constant torque curve based on a field current value and an armature current value and a pattern of a total curvature curve appearing on the constant torque curve, It may be different from the armature current value. This is because the field current value and armature current value applied to the actual motor may not have the same scale. For example, as shown in Figs. 8 and 10, which will be described later, substantially If_max may be 9.8A and Ia_max may be 588.2A.

The large scale of Ia is for facilitating weak field control, which will be described later. This is to make it possible to control the rotation speed of the motor to a very high speed.

The scale difference (Ra / Rf difference) of the resistance value and the scale difference (when the quantum is the maximum value) of If and Ia may be very large in some cases. Conversely, these scales may be small in difference, and only one scale may be significantly different.

Therefore, it is possible to simply apply the total curvature curve according to the difference of these scales.

For example, the minimum value of the arithmetic sum of the field current and the armature current value may be very similar to the single current combination, which results in the minimum copper loss in the total copper curvature curve.

In addition, efficiency control using this total curvature curve may be performed only in a part of the operation area other than the entire operation area of the motor.

The present embodiment basically provides a control method of controlling a motor with a current combination that generates a minimum total copper loss among a current combination applied for generation of a current output torque. The current output torque can be substantially referred to as the command torque in the constant torque region. The current output torque can be referred to as the actual output torque in the constant output region. The actual output torque itself may be sensed. Also, the actual output torque may be calculated through the number of revolutions to be sensed and the current command torque.

Hereinafter, a control method according to an embodiment of the present invention will be described in detail with reference to FIG.

First, the command torque is calculated (S110). This command torque can be calculated through the angle of the accelerator pedal. That is, when the driver depresses the accelerator pedal, the angle of the accelerator pedal is input (S100), and the command torque can be calculated through the angle (S110).

Conventionally, when the command torque is calculated, a field current value of the same value regardless of the speed or regardless of the operation region is calculated. That is, the field current value was calculated through the torque ratio reference control.

In the constant torque region, the command torque and the actual output torque are substantially equal, so that the motor can be controlled through the same current combination. Since the actual output torque is smaller than the command torque in the constant output range, the current combination is determined so as to match the actual output torque. That is, although the field current value is the same, the output torque gradually becomes smaller, so that the current combination in which the armature current value gradually decreases is determined.

At least one of the control method in the constant torque region and the control method in the constant output region is different from the conventional torque ratio reference control method in the control method according to the present embodiment.

When the command torque is calculated in the command torque calculation step (S110), a single current combination is determined according to the command torque (S120). Here, such a single current combination is a combination in which the total copper loss is minimized with respect to the same command torque. In other words, it can be said that, among the plurality of current combinations that can be applied for generating the same torque, the single current combination in which the total copper loss is minimized is determined (S120).

Therefore, basically, the motor is driven (S160) by applying the determined single current combination. That is, the motor output is controlled.

The motor output is feedback (S170) to an output speed, an output torque, and the like. Therefore, it is possible to control the combination of currents so that a desired motor output is generated through the feedback process.

Here, it may be determined whether the rotational speed N of the motor is less than the rated speed Nbase or not (S 130). That is, the step of determining whether the current operation region is the constant torque region or the constant output region (S130) may be performed.

This determination step is related to determination of current combination and whether to perform weak field control, which will be described in detail.

If it is determined in the determination step S130 that the vehicle is in the constant torque region, the current combination is determined in S120 according to the command torque calculated in S110, as described above. The determined current combination is input to the motor (S140) and the motor is controlled so that the motor follows the input command torque. Of course, in the constant torque region, the current combination can be differently determined in S120 through feedback (S170) and input to the motor.

However, ideally, if the command torque is the same in the constant torque region, it can be said that the single current combination remains unchanged even if the speed increases.

If it is determined in the determination step (S130) that the current output region is the constant output region, the current combination is determined in S120. Of course, in this case, the current combination is determined on the basis of the actual output torque, not the command torque. The actual output torque can be calculated through the command torque and the current number of rotations fed back. Further, the actual output torque can be calculated through the current output torque to be fed back.

In addition, in S120, a single current combination that generates a minimum copper loss among a plurality of current combinations for generating an actual output torque is determined. Therefore, although the number of rotations of the motor increases, it is possible to minimize the occurrence of dynamic loss.

Hereinafter, the efficiency that can be enhanced through the present embodiment will be described with reference to FIG. 8 to FIG.

FIG. 8 shows a current combination applied to a motor at a specific command torque and a specific number of revolutions using a conventional torque ratio reference control, and FIG. 9 shows motor efficiency through the control method shown in FIG.

As shown in FIG. 8, when the specific command torque is determined, it is understood that If is determined in the same manner regardless of the number of revolutions. It can be seen that the id value becomes larger as the speed increases for the weak field control above the rated speed.

Fig. 9 shows the efficiency of the motor controlled by the conventional torque ratio reference control in the front operating range.

As shown in Fig. 9, it can be seen that the efficiency is low at low speed and low torque when the torque ratio reference control is used.

FIG. 10 illustrates a combination of currents applied to a motor at a specified command torque and a specific number of rotations using an efficiency reference control according to an embodiment of the present invention. And FIG. 11 shows the motor efficiency through the control method shown in FIG.

As shown in FIG. 10, it can be seen that If is determined differently according to the number of revolutions. Specifically, it can be seen that If in the constant torque region is determined substantially larger than the conventional If. In addition, if can be determined as a fixed value according to the command torque from the constant torque region to the rated speed (for example, 4100RPM).

Here, the fact that If in the constant torque region is substantially larger than that in the torque ratio reference control means that armature copper loss due to the magnitude of the armature current value Ia itself is larger than the field copper loss due to the magnitude of If .

However, in the constant output region, If becomes smaller as the speed increases. This means that it is possible to directly reduce the generated back electromotive force by reducing If directly directly related to field flux. It can be seen from this that even when the output torque is the same, the id value is smaller than the conventional one. In other words, weak field control is possible even if the increase in the negative direction magnitude of id is minimized.

Therefore, it can be seen that the total copper loss of the motor can be remarkably reduced by minimizing the increase in id.

12 shows the efficiency difference between the torque ratio reference control and the efficiency reference control in the entire operating range.

It can be seen that the efficiency increases substantially in the low speed and low torque regions. This means that the efficiency can be significantly increased in a city driving condition where an electric vehicle repeats a steady state. In addition, it can be seen that the efficiency increase effect can be expected in the entire operation region.

An electric vehicle drives a motor using electric energy charged in a battery. In addition, it uses electric energy to drive various electric components and, in particular, to operate an air conditioning system. Therefore, how efficiently the electric energy charged in the battery can be used is very important.

Therefore, it can be said that the efficiency increase in the entire operation region can be very effective despite the difference depending on the operation region. In particular, it is more encouraging that the effect of increasing the efficiency in the low-speed low-torque operation region, which is generally the most frequent, is remarkable.

10: stator 11: stator core
12: stator coil (armature coil) 20: rotor
21: rotor core 22: rotor coil (field coil)
30: rotation shaft 200: motor control part (inverter)
210: field current controller 220: inverter circuit
230: motor controller 240: sensor

Claims (13)

A motor comprising a rotor provided with a field winding and a stator provided with an armature winding,
In order to reduce the loss of copper loss in the armature winding through weak field control in the constant output operation region, a motor control section (10) controls the field current value (If) applied to the field winding / RTI >
Wherein the field current value in the constant output operation region is a field current value determined by the product of the ratio of the command torque to the maximum torque (torque ratio, T / Tmax) to the maximum field current value (Ifmax) Lt; / RTI > The method according to claim 1,
Wherein the armature current value (Ia) in the constant output operation region is smaller than the armature current value determined by the torque ratio reference control. 3. The method according to claim 1 or 2,
In the constant torque operation region, the field current value (If) is larger than the field current value determined by the torque ratio reference control. The method of claim 3,
In the constant torque operation region, the armature current value (Ia) is smaller than the field current value determined by the torque ratio reference control. The method according to claim 1,
(If, Ia) of the armature current value Ia applied to the armature winding corresponding to the applied field current value If and the field current value If is a single combination with respect to the same torque The motor. 6. The method of claim 5,
Wherein said single combination is a combination of currents in which the total motor power loss is lowest among a plurality of current combinations for the same torque. A motor comprising a rotor provided with a field winding and a stator provided with an armature winding,
And a motor control unit for controlling the motor by a single current combination of a field current value and armature current value at which the total motor manual loss is minimized for the same torque in order to reduce the total motor hand loss by the field winding and the armature winding and,
The field current value If in the constant output operation region is expressed by the following equation
Is smaller than the field current value determined by the product of the ratio of the command torque to the maximum torque (torque ratio, T / Tmax) and the maximum field current value Ifmax (torque ratio reference control) Of the motor. 8. The method of claim 7,
Wherein the field current value If in the single current combination is larger than the field current value determined by the torque ratio reference control in the constant torque operation region. 8. The method of claim 7,
Wherein the armature current value (Ia) in the single current combination is smaller than the armature current value determined by the torque ratio reference control in the constant torque operation region and the constant output operation region. 8. The method of claim 7,
Wherein the field current value If in the single current combination is the same value in the constant torque operation region regardless of the rotational speed of the motor. 1. A control method for a motor including a rotor provided with a field winding and a stator having an armature winding,
Calculating an instruction torque through an angle of the accelerator;
Determining whether the rotational speed is less than the rated rotational speed (the constant torque region) or the rated rotational speed (the constant output region) through the rotational speed of the rotor;
Determining a single current combination of the field current value If and the armature current value Ia through which the motor total copper loss is minimized through the calculated command torque or the current output torque;
And controlling the output of the motor by applying the determined single current combination. 12. The method of claim 11,
Wherein the single current combination is determined through a command torque and the single current combination is determined through a current output torque when it is determined to be a constant torque region in the determination step,
Wherein the current output torque is determined by the current output torque to be fed back or the number of revolutions of the rotor to be fed back and the command torque. 13. The method of claim 12,
If it is determined to be a constant output region in the determination step, weak field control is performed to increase the magnitude of the magnetic flux component current value id in the negative direction, and the field current value decreases as the rotation number increases Wherein the motor control method comprises the steps of:

Images