JPH07170800A - Control method for motor - Google Patents

Abstract

PURPOSE:To perform field weakening by comparing a first torque command current, obtained from the deviation between a speed signal to a motor and the present speed of the motor, with the torque current corresponding to each torque, and determining a second torque command current and a weakening current according to which range the first torque command current is within. CONSTITUTION:A torque command current I*q0 is obtained by arithmetic operation from the deviation between a speed command omega* and the present speed omega. The magnitude of the torque command current I*q0 is I*q0, and has an inclination determined according to the magnitude of speed gain. Torques produced at the present speed are obtained from the characteristic charts 1, 2 and 3. Torque is T1 in the characteristic chart 1, T1 in the characteristic chart 2 and T3 in the characteristic chart 3. A torque command current I*q0, obtained from the deviation of speed, is compared with the magnitude of torque currents Iq1-Iq3 that can be produced at the present speed to determine a weakening current I*d and a torque command current I*q, which are then output.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control method for controlling a synchronous motor which is a power source of an electric vehicle, for example.

[0002]

2. Description of the Related Art With the establishment of vector control theory, control for making d-axis current (hereinafter referred to as I _d current) zero is generally used for efficient control. Recently, for the purpose of high-speed range the control of the rotation of the motor, using the I _d current actively, by flowing the I _d currents weaken effective magnetic flux of the motor, field weakening control to enable high-speed range rotating,
It is being introduced.

The inventor of the present invention has proposed that a synchronous motor is used as a drive motor for an electric vehicle, and a high speed rotation control of the motor is performed by positively flowing an I _d current. FIG. 13 shows a schematic configuration diagram of an electric vehicle. In FIG. 13, 51 is the vehicle body, 52 is the front wheels, 53 is the rear wheels, 5
4 is a motor, 55 is a transmission, and 56 is a battery. A controller 57 receives an accelerator signal and a brake signal. This electric vehicle has a battery 56
The motor 54 is operated by using the
4 driving force is transmitted to the rear wheel 53 via the transmission 55.
Be transmitted to. The controller 54 controls the motor 54.

The following are examples of the effects obtained by controlling the d-axis current of an electric vehicle. It is assumed that the motor only goes up to a certain number of revolutions (for example, 5000 rpm). When the vehicle speed becomes high, the number of rotations of the motor must also be made high in conjunction with the wheels, but when the number of rotations of the motor reaches 5000 rpm, the number of rotations does not increase further, so to further increase the speed, This is done by increasing the speed using the transmission.

However, when the d-axis current control (field-weakening control) proposed this time is performed, as shown in FIG. 14, unless field-weakening control is performed, the rotation speed is only up to 5000 rpm (solid line A).
₁ ) 1000 by controlling the field weakening of the motor
It becomes possible to rotate up to 0 rpm (solid line A ₂ ), and it can be expected that a vehicle without a transmission can be provided as an electric vehicle. In FIG. 14, TT ₁ , TT ₁
/ 2 shows the torque when the motor is stopped.

Further, since the transmission is eliminated, the cost and the weight can be reduced and the efficiency can be improved. Then, if the control is appropriately performed, the control can be efficiently performed, and the efficiency is good with the limited energy (battery), so that an effect such as extension of the cruising range can be expected. If a motor capable of rotating up to 10000 rpm is manufactured, the motor will be large and the weight will be greatly increased, and such a configuration cannot be adopted in an electric vehicle.

[0007]

However, the means for specifically realizing the field-weakening control have not been published. Therefore, an object of the present invention is to provide a motor control method capable of performing field weakening and efficiently controlling the motor.

[0008]

According to a first aspect of the present invention, there is provided a method of controlling a motor, wherein a speed-torque characteristic of a motor to be controlled is weakened and a weakening current is applied at one level or a plurality of different levels. The step of obtaining the first torque command current from the deviation between the speed command to the motor and the current speed of the motor, and the torque generated at the current speed to the speed-torque characteristic. The step of obtaining the weakening current and the step of obtaining the weakening current at one level or a plurality of different levels, and the torque obtained in the previous step and the torque constant of each speed-torque characteristic. A step of calculating a torque current corresponding to the torque, a deviation between a speed command for the motor and a current speed of the motor Wherein the first torque command current determined al compares the torque current corresponding to the torque, the first
Determining and outputting the second torque command current and the weakening current according to the range of the torque current corresponding to each torque.

According to a second aspect of the present invention, there is provided a method of controlling a motor, wherein a step of obtaining a torque command current from a deviation between a speed command for a motor to be controlled and a current speed of the motor is calculated, and a current for weakening current is not applied. A step of determining whether the sum of the voltage vectors of the respective parts of the motor is within a limit circle determined by the voltage applied to the motor when the torque command current is set at the speed of, and the voltage vector of the respective parts of the motor. Is not within the limit circle determined by the voltage applied to the motor, the sum of the voltage vectors of the parts of the motor is within the limit circle determined by the voltage applied to the motor, and the torque current is While appropriately changing the weakening rate under the condition that it becomes equal to the value obtained by multiplying the command torque current obtained from the speed deviation by the weakening rate, And determining a leakage current.

According to a third aspect of the present invention, there is provided a motor control method according to the first aspect of the present invention, in which the motor is controlled by utilizing field weakening control. A method of controlling a motor that returns to a state, in which a weakening current value is fixed and the torque current is gradually reduced, a weakening current value is reduced, and a torque current is corrected at that time.
The method includes the steps of holding the final state for a specific time, fixing the weakening current value and gradually increasing the torque current, and increasing the weakening current value and correcting the torque current.

According to a fourth aspect of the present invention, there is provided a motor control method according to the first or second aspect of the present invention, wherein the regenerative braking force is controlled by the motor control method. The method includes a step of calculating a necessary weakening current from the torque characteristic and a step of calculating a torque current from the calculated weakening current value.

[0012]

According to the structure of the first aspect, one or more kinds of weakening currents are set in advance, and the first torque command current and each torque obtained from the deviation between the speed command for the motor and the current speed of the motor are set to each torque. The corresponding torque current is compared, and the second torque command current and the weakening current are determined and output according to the range of the torque current corresponding to each torque. As a result, the second torque command current and the weakening current can be determined easily and efficiently.

According to the second aspect of the invention, the sum of the voltage vectors of the respective parts of the motor falls within the limit circle determined by the voltage applied to the motor, and the torque current is weakened against the command torque current obtained from the deviation of the speed. The weakening current and the torque current are determined while appropriately changing the weakening rate under the condition that they become equal to the value obtained by multiplying by. As a result, maximum torque can be generated with a small weakening current, and maximum efficiency control is possible.

According to the third aspect of the invention, when a command to reduce the output of the motor is input, the output of the motor is gradually reduced by appropriately changing the torque current and the weakening current. According to the structure of claim 4, when the motor is in the over-rotation state, the appropriate weakening current and torque current are calculated to control the motor, thereby preventing over-regeneration due to over-rotation.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. [First Embodiment] A motor control method according to a first embodiment of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 shows a motor according to the first embodiment of the present invention.
Current weakening current of the synchronous motor in the control method of
Flow rate to explain the algorithm for determining
FIG. In Figure 1, 1 is a weakening current
When there is no (I_d= 0), that is, battery voltage and motor constant
In the characteristic diagram determined by the number, the torque constant of the motor at that time
K_T1, No load speed ω₁And 2 is weakening current I_d1To
When shed (I_d= I _d1) Characteristic diagram,
Torque constant of K_T2, No load speed ω₂And Three
Is the weakening current I as in the characteristic diagram 2._d2(I_d= I_d2)
In the characteristic diagram when the_T3, Non-negative
Load rotation speed is ω₃And

The algorithm for determining the motor weakening current will be described below. First, the torque command current I ^* _q0 is calculated from the deviation between the speed command ω ^* and the current speed ω. The magnitude of this torque command current I ^* _q0 is shown in FIG.
I ^* _{q0 in} the figure, and the dotted line in the figure has a slope determined by the magnitude of the velocity gain. In the figure, a straight line is approximated in order to make the explanation easy to understand.

Next, the torque generated at the current speed is specified.
Obtained from sex charts 1, 2, and 3. From Fig. 1
Torque is T₁, The torque in the characteristic diagram 2 is T₂,Characteristic
The torque in Fig. 3 is T₃Becomes Torque constant K_tAnd to
The relationship between the torque T and the torque current i is given by [Equation 1].
Therefore, the torque constant K of each characteristic diagram 1, 2 and 3 is_T1~ K_T3When
Torque T at that time₁~ T ₃And then the required torque current
I_q1~ I_q3Is calculated using [Equation 2].

[0019]

[Equation 1]

[0020]

[Equation 2]

[0021] Then, the current weakening the torque command current I ^* _q0 determined from the deviation of the speed, according to the following conditions by comparing the magnitude of the torque current I _q1 ~I _q3 that can occur in current speed I ^* _d and torque command current I ^*
Determine _q and output. I ^* _q0 ≤ I _q1 torque command current: I ^* _q = I ^* _q0 weakening current: I ^* _d = 0 I _q1 <I ^* _q0 ≤ I _q2 torque command current: I ^* _q = I ^* _q0 × (ω ₂ / ω ₁ ) Weak current: I ^* _d = I _d1 I _q2 <I ^* _q0 Torque command current: I ^* _q = I ^* _q0 × (ω ₃ / ω ₁ ) Weak current: I ^* _d = I _d2 Weak current I _d1 and I _d2 are calculated in advance by using [Equation 3] from the motor constant and the weakening rate.

[0022]

[Equation 3]

However, n ₀ : weakening rate (= ω ₂ / ω ₁ ) n ₁ : weakening rate (= ω ₃ / ω ₁ ) L: motor inductance ψ: effective magnetic flux of the motor Torque command current I ^* _q0
If, when performing size determination of the torque current I _q1, I _q2, I _q3 required to issue a torque generated at the current speed, the torque command current I ^* _q and weakening current I ^* _d a to chattering In order to prevent it, it is preferable to provide a hysteresis to the currents I _q1 , I _q2 , and I _q3 . Further, it is preferable that the width of the hysteresis can be set individually for the currents I _q1 , I _q2 and I _q3 .

In the above description, the description has been made on the assumption that two patterns of weakening currents are passed, but even if the weakening current value is further increased to obtain smooth rotation of the motor, the same algorithm can be used for the control. Needless to say. The weakening current I _d (also the torque current I _q ) is determined by the algorithm described above.

Since the maximum current value I _max of the motor is restricted by the switching element, the upper limit of the torque current I _q is restricted by the following equation. That is,

[0026]

[Equation 4]

From

[0028]

[Equation 5]

It becomes Therefore, the speed-torque characteristic of the motor is as follows when the above limitation of the torque current I _q is added.
As shown in FIG. 2, the characteristics are stepwise. In FIG.
B ₁ point is a torque position corresponding to I _max = I _q , B ₂ point is a torque position corresponding to I _q satisfying I _max ² = I _d1 ² + I _q ² , and B ₃ point is I _max ² = I It is the position of the torque corresponding to I _q that satisfies _d2 ² + I _q ² .

The above algorithm is shown in the flow chart of FIG. Here, it is clear from FIG. 2 that the smoother the rotation, the more the weakening current pattern increases. According to the motor control method of this embodiment, the weakening current can be determined by a simple method, and the motor can be efficiently controlled.

[Second Embodiment] A motor control method according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 4 is a vector diagram for explaining an algorithm for determining the weakening current (field weakening current) of the synchronous motor in the motor control method according to the second embodiment of the present invention. The torque current I _q and the weakening current are shown in FIG. It is a vector diagram of the voltage of each part of a motor when I _{d is made} to flow and the motor is rotating. In FIG. 4, K _t is the torque constant of the motor, L _q is the q-axis inductance of the motor, L _d is the d-axis inductance of the motor, R is the resistance of the motor, P is the number of pole pairs, ω _m is the current speed, and V is It is the voltage applied to the motor.

In the figure, K _t · ω _m is ω _m
It is the induced voltage generated by the motor when rotating at the speed of. I _q · R is a voltage generated when the torque current I _q flows through the resistance of the motor. ωL _q · I _q is
It is a voltage generated in the q-axis inductance when rotating at a speed of ω _m . I _d · R is a voltage generated when the weakening current I _d flows through the resistance of the motor. ωL _d
· I _d is the voltage generated in the d-axis inductance when rotating at a speed of omega _m.

Here, the d-axis current is advanced by 90 ° from the q-axis. Next, regarding the field weakening control, FIG.
Will be described with reference to. As shown in FIG. 5 (a), when gradually increasing the rotation speed omega, the induced voltage ω _m · k _t is increased, RI _q and .omega.L _q I _q and the voltage value obtained by vector addition is becomes a voltage limit circle , The rotation speed cannot be increased any further.

Therefore, as shown in FIG. 5 (b), a current I _{d is made} to flow with respect to the voltage of the voltage limiting circle to generate a voltage ωL _d I _d in the direction of returning to the voltage limiting circle, so that the voltage margin is increased. generate. Then, as shown in FIG. 5C, a large torque is generated by increasing the rotation speed of the electric motor by the generated voltage margin, or when the speed is constant, flowing a torque current for the voltage margin. be able to.

Here, the current I that causes a voltage margin
_d may be the minimum value that returns to the voltage limiting circle. This is because if the current I _d is applied above the minimum value, the efficiency will decrease due to the copper loss generated by passing the current I _d . Therefore,
Based on the calculated torque command current and rotation speed, it is checked whether the voltage value obtained by vector addition is within the voltage limit circle.
Then, if it is within the voltage limiting circle, it is not necessary to flow the current I _d (there is a voltage margin). On the contrary, if it exceeds the voltage limit circle, it must be returned to the voltage limit circle by flowing the current I _d .

For that purpose, first, the weakening rate is set, and the current I
Determine the size of _d . Then, in order to limit the magnitude of the current I _d (prevent magnet demagnetization), the current I _d is limited by limiting the weakening rate n. Then, the calculated current I _d and I _q checks whether the current upper limit value of the switching device, and finally by checking whether the back of the voltage within the limit circle, determines the magnitude of the current I _d .

The algorithm for obtaining the d-axis current will be described below. (A) Now, in order to rotate the motor at the rotation speed ω _m with the torque current I _q and the weakening current I _d , the vector sum of the generated voltages shown in FIG. 4 is the limit circle of the applied voltage V of the motor. Must be inside. (B) from the deviation between the command speed ω ^* _m and the current speed ω _m,
The torque command current I ^* _q0 is calculated.

(C) Based on the calculated torque command current I ^* _q0 , it is determined whether or not a weakening current is to flow. First,

[0039]

[Equation 6]

When the conditions are satisfied, the weakening current I ^* _d = 0 and the torque current I ^* _q = I ^* _q0 are set. Also,

[0041]

[Equation 7]

When the condition is satisfied, a weakening current is passed. (D) The weakening current I ^* _d and the torque current I ^* _q are determined as follows. (D-1) First, the weakening current I ^* _d is

[0043]

[Equation 8]

It is calculated by Here, ψ is the effective magnetic flux (= K _t / P) of the motor, and n is the weakening rate (n> 1). (D-2) Next, the torque current I ^* _q is obtained as follows. The motor current is

[0045]

[Equation 9]

As can be obtained from the above, since it is necessary to limit the motor current to I _max from the upper limit of the switching element,

[0047]

[Equation 10]

It is necessary to apply the relationship of Therefore, the torque current I ^* _q0 is changed to a value that conforms to the above formula, and the value of the torque current I ^* _q output to the motor is calculated by [Equation 11].

[0049]

[Equation 11]

It is calculated by. (D-3) Next, the limit circle of the voltage V (explained in (A))
Whether it is in or not is determined by [Equation 12].

[0051]

[Equation 12]

(D-4) If [Equation 12] is satisfied, it is next determined whether or not to secure the command torque value corresponding to the torque current I ^* _q0 . And

[0053]

[Equation 13]

When the processing is performed and the condition is not satisfied,
The weakening rate n is increased to satisfy all the conditions.
Is determined and I ^* _q and I ^* _d are determined based on the weakening rate n. A flowchart of the above algorithm is shown in FIG. (D-5) Next, some examples of the method of varying the weakening rate n will be described.

By increasing n from 1 sequentially, (D
The weakening current rate n satisfying the condition of [Equation 13] in -4) is adopted. As shown in FIG. 7, the classification method is used. (Example) When n = 2, the condition is determined, and the value of n is changed according to Yes / No as shown in the above figure, and the optimum weakening rate n that satisfies the condition is determined.

An approximate solution is obtained, and then n is varied (see FIG. 6). The approximate expression

[0057]

[Equation 14]

This corresponds to ωL _d · I _d in FIG. 6, but the weakening current I _d and the weakening rate n are calculated based on this approximate expression. The weakening current I _d can be obtained by [Equation 15].

[0059]

[Equation 15]

The weakening rate n can be obtained from [Equation 16] obtained by modifying [Equation 8].

[0061]

[Equation 16]

Then, the weakening rate n obtained from the approximate expression is sequentially increased to adopt n satisfying the condition of [Equation 13] of (D-4). (E) In the above description, the limiting circle of the voltage V has been considered to be constant, but when the battery is used as the power source, the voltage V applied to the motor changes depending on the magnitude of the motor current due to the internal resistance of the battery. come. That is, the voltage V
That is, the limit circle of moves, and the voltage V at that time is defined by [Equation 17].

[0063]

[Equation 17]

However, V _Batt is the battery voltage, R _B is the battery internal resistance, V _drop is the voltage drop due to the switching element, and η is the efficiency. According to the motor control method of this embodiment, the maximum torque can be generated with a small (optimal) weakening current, and thus maximum efficiency control can be performed. [Third Embodiment] A third embodiment of the present invention will be described with reference to FIGS.

This embodiment shows a method (algorithm) of limiting the motor current in order to reduce the output of the motor due to an abnormality such as heat generation in the motor, which will be described in detail below. First, the case where no weakening current is applied will be described. FIG. 9 shows the speed-torque characteristic when the weakening current is not applied. The algorithm for limiting the motor current will be described with reference to FIG.

A command to reduce the output is input. The torque command current I ^* _q0 is calculated from the deviation between the speed command ω ^* and the current speed ω. This calculation method is similar to that of the first embodiment. The value of the calculated torque command current I ^* _q0 is gradually reduced (→ I ^* _q0 ′).

The loss of the motor for t seconds is calculated according to [Equation 18].

[0068]

[Equation 18]

However, the current I is represented by [Equation 19].

[0070]

[Formula 19]

It is It is determined every t seconds whether or not the loss value L _S exceeds the abnormal loss L _SER . That is, the determination of [Equation 20] is performed.

[0072]

[Equation 20]

If an abnormality occurs, in order to suppress the loss,
It is necessary to reduce I _q and I _d . Therefore, the method of making it smaller is described below. In addition, how much the loss should be suppressed is, for example, if 50% loss is suppressed,

[0074]

[Equation 21]

Is used as a reference value. When the weakening current is 0 (7-1) _{Calculate the} torque current I ^* _q01 obtained from the deviation

[0076]

[Equation 22]

It is corrected and output. At this time, for example, k ₁
= 0.95. Further, the maximum value I _{max of the} current that the device is restricted is also corrected by [Equation 23].

[0078]

[Equation 23]

(7-2) Obtain the loss of the output current. (7-3) The integral value X of (7-2) at every certain time.
Compare _add with the X _CMP . The conditions for establishment are

[0080]

[Equation 24]

It is (7-4) If the condition is not satisfied, the torque command current I ^* _qO2 obtained from the deviation at the next sampling is corrected according to the following equation.

[0082]

[Equation 25]

[0083]

[Equation 26]

That is,

[0085]

[Equation 27]

It is (7-5) If the condition of (7-3) is satisfied at k _n , the gain k _n at that time is used to correct the torque current obtained from the deviation and the maximum value of the current.

[0087]

[Equation 28]

[0088]

[Equation 29]

If the condition is satisfied, this gain k _n is fixed for t seconds and output. (7-6) Then, the process until the recovery is described. The torque current and maximum current value obtained from the deviation are corrected with the gain of k _n , but conversely

[0090]

[Equation 30]

[0091]

[Equation 31]

[0092]

[Equation 32]

[0093]

[Expression 33]

K_{n + 1}Gain of k₁
^(n-1)Correct with (calculate loss). (7-7) Similarly to the above, the integration
Loss value X_addAnd X_CMPCompare with (see [Equation 24]
See). If the conditions are met, the next sampling
Torque current I obtained from deviation _{q0 (n + 2)}Is complemented by
To correct.

[0095]

[Equation 34]

[0096]

[Equation 35]

[0097]

[Equation 36]

(7-8) Finally, k _{n + n} = 1
When, the torque current obtained from the normal speed deviation is output. That is, the torque current I _q0n obtained from the deviation is corrected with a certain gain k, and at the same time, the maximum current value is also corrected.

[0099]

[Equation 37]

[0100]

[Equation 38]

The gain k is reduced as described above for each sample, the loss value is compared with the target value at constant time intervals T, and the gain k is reduced until the target is achieved. When the target is achieved, the gain is corrected with a gain of k _n for T seconds, and when returning, the gain k is increased by the reverse process described above until the final k = 1, and then the torque current is adjusted to a value larger than the normal deviation. The motor is controlled by I _q and the maximum current value F _XMAX .

When weakening current> 0 The method of reducing the torque current is the same as when weakening current = 0, and the method of reducing the weakening current is as described above.
FIG. 10 shows the change over time in the torque current I ^* _q at this time. In FIG. 10, the torque current I ^* _q is I ^* _q0 at time 0.
On the other hand, at times t, 2t, 3t and 4t, n ₁ ·
_{^{I * q1, n 2 · I}} * q2, n 3 · I * q3, n 4 · I
^* _q4 , the judgment is made at each time t, 2t, 3t, 4t, the condition is _{met at} time 4t seconds, and then the torque current n ₄ · I ^* _qn ′ continues to flow for T seconds, and then the torque is increased. It shows that the current I ^* _q gradually rises every t seconds. Incidentally, n ₁ ~n ₄ is a value smaller than 1.

Next, the algorithm when the weakening current is flowing will be described with reference to FIG. (2-1) The torque current I ^* _q0 determined from the speed deviation, as in the case of I _d = 0 as described above, is calculated using a correction gain k. At the same time, the maximum value of the current is also corrected.

[0104]

[Formula 39]

[0105]

[Formula 40]

Using the corrected torque current I ^* _q ,
The weakening current I ^* _d is determined by the algorithm described in the first embodiment. The torque current I ^* _q is corrected again using the calculated weakening current I ^* _d . At this time, the maximum value of the current to which the device is restricted is F _XMAX ′. (2-2) Judgment is performed every t seconds. This determination is as described above.

(2-3) When the determination of (2-2) is not established, the output current is calculated by using the correction gain k for the torque current, and the weakened current I ^* _d is calculated using the corrected torque current.
To decide. Since the torque current is reduced, the motor speed is reduced, and as a result, the weakening current I ^* _d is, for example, I
_It can be seen from FIG. 11 that the torque current is corrected by the difference in the weakening rate when shifting from _d2 to I _d1 .

(2-3) If the conditions of (2-2) are satisfied, the torque current is calculated using the correction gain k calculated last, and the weakening current is calculated using the torque current. Perform for T seconds. (2-5) Thereafter, the above algorithm is followed in reverse, and the torque current obtained from the normal speed deviation and the weakening current obtained from the torque current and the current speed are output.

The algorithm described above is shown in FIG. In FIG. 11, a stepwise solid line shows the change in the torque current. In this description, the condition (2-2) is satisfied after 3t, but when the condition is satisfied at t and 2t, the correction gain k calculated last is also used. It goes without saying that I _d and I _q are obtained by the above, they are output for T seconds, and then the process returns to the reverse.

In the above description, the case where the weakening current value has two patterns has been described, but the same processing may be performed even if the weakening current patterns increase. According to this embodiment, the motor output can be gradually reduced by gradually reducing the torque current and outputting the weakening current from the corrected torque current and speed.

[Fourth Embodiment] A fourth embodiment of the present invention will be described with reference to FIG. This embodiment is an embodiment showing a method (algorithm) for preventing the motor from over-rotating and over-regenerating to the battery. The algorithm will be described below with reference to FIG.

Assuming that the current speed is ω _m and the no-load rotational speed at which a weakening current does not flow is ω ₁ , first, the weakening rate n is calculated by
1].

[0113]

[Formula 41]

Next, the weakening current I _d is calculated according to [Equation 42] (see the characteristic diagram 4 shown by the broken line in FIG. 11).

[0115]

[Equation 42]

However, I _dFW is a weakening current value that can completely cancel the effective magnetic flux of the motor. Performs weakening current limit processing. The upper limit current I _max of the switching element limits the current value as shown in [Equation 43].

[0117]

[Equation 43]

The torque current I _q is calculated. (4-1) When I _d = I _max , I _q = 0. (4-2) When I _d <I _max (A) From the upper limit of the switching element, the torque current I _q
The maximum value I _{qmax1 of} is calculated according to [ _Equation 44].

[0119]

[Equation 44]

(B) _Assuming that the maximum value of the charging current to the battery is I _Bmax , the maximum value I _qmax1 of the torque current I _q and the maximum value I _Bmax of the charging current are compared to determine the maximum value I _{qm ax} of the torque current. calculate. However, I _qmax > 0 and I _Bmax > 0. When I _qmax1 ≧ I _Bmax , I _qmax = I _{Bmax When} I _qmax1 <I _Bmax , I _qmax = I _qmax1 (C) The torque command current I ^* _q0 obtained from the speed deviation is calculated. With the weakening rate n calculated above, the torque command current I
^{* When} _q0 is corrected, it becomes like [ _Equation 45].

[0121]

[Equation 45]

(D) The torque current limit process is performed. When | I ^* _q | ≦ _Iqmax , the torque current is I ^* _q
And When | I ^* _q |> _Iqmax , the torque current is
_Let I _qmax . (4-3) Output current calculated in (4-2), that is the torque current I ^* _q or -I _qmax weakening current _{I d = (1-1 / n)} I dFW, over-regeneration condition is avoided If the output current continues to be output and is avoided, the output current is determined by a normal method (see Examples 1 and 2).

According to this embodiment, it is possible to protect the battery due to over regeneration (overcharge). (Controlling the regeneration amount) In other words, it is possible to reduce the motor rotation while suppressing the regeneration amount.

[0124]

According to the motor control method of the first aspect,
One or more kinds of weakening currents are set in advance, the first torque command current obtained from the deviation between the speed command for the motor and the current speed of the motor is compared with the torque current corresponding to each torque, and the first torque command current is compared. Since the second torque command current and the weakening current are determined and output according to the range of the torque current corresponding to each torque, the second torque command current and the weakening current can be easily and efficiently determined. You can decide.

According to the motor control method of the second aspect, the sum of the voltage vectors of the respective parts of the motor falls within the limit circle determined by the voltage applied to the motor, and the torque current becomes the command torque current obtained from the deviation of the speed. Since the weakening current and the torque current are determined by appropriately changing the weakening rate under the condition that the weakening rate is equal to the value obtained by multiplying the weakening rate, the maximum torque can be generated with a small weakening current, and the maximum efficiency control can be performed. Is possible.

According to the motor control method of the third aspect, when a command to reduce the output of the motor is input, the output of the motor is gradually reduced by appropriately changing the torque current and the weakening current. Is possible. According to the configuration described in claim 4, when the motor is in the over-rotation state, the appropriate weakening current and torque current are calculated to control the motor, so that over-regeneration due to over-rotation can be prevented. .

[Brief description of drawings]

FIG. 1 is a torque-speed characteristic diagram showing an algorithm of a motor control method according to a first embodiment of the present invention.

FIG. 2 is a torque-speed characteristic diagram showing an algorithm of a motor control method according to the first embodiment of the present invention.

FIG. 3 is a flow chart showing an algorithm of a motor control method according to the first embodiment of the present invention.

FIG. 4 is a voltage vector diagram of each portion of the motor showing an algorithm of the motor control method according to the second embodiment of the present invention.

FIG. 5 is a vector diagram of field weakening control in the motor control method according to the second embodiment of the present invention.

FIG. 6 is a voltage vector diagram of each portion of the motor showing an algorithm of the motor control method according to the second embodiment of the present invention.

FIG. 7 is a schematic diagram showing a method of determining a weakening rate.

FIG. 8 is a flowchart showing an algorithm of a motor control method according to the second embodiment of the present invention.

FIG. 9 is a torque-speed characteristic diagram showing an algorithm of a motor control method according to a third embodiment of the present invention.

FIG. 10 is a torque current-time characteristic diagram showing an algorithm of the motor control method according to the third embodiment of the present invention.

FIG. 11 is a torque-speed / time characteristic diagram showing an algorithm of a motor control method according to the third embodiment of the present invention.

FIG. 12 is a torque-speed characteristic diagram showing an algorithm of a motor control method according to a fourth embodiment of the present invention.

FIG. 13 is a schematic configuration diagram of an electric vehicle.

FIG. 14 is a torque showing a state of field weakening control of the motor.
It is a speed characteristic diagram.

[Explanation of symbols]

ω ^* speed command ω speed T _{1 to} T ₃ torque KT _{1 to} KT ₃ torque constant I _{q1 to} I _q3 torque current

Claims (4)

[Claims] 1. A step of obtaining a speed-torque characteristic of a motor to be controlled in a state in which a weakening current is not applied and a state in which a weakening current is applied at one level or a plurality of different levels, respectively, and a speed command for the motor. A step of calculating a first torque command current from the deviation of the current speed of the motor; a state in which the torque generated at the current speed is weakened on the speed-torque characteristic and no current flows; one level or a plurality of levels; A step of obtaining a weak current at different levels and a step of calculating a torque current corresponding to each torque from the torque obtained in the previous step and a torque constant of each speed-torque characteristic; The first torque command current obtained from the deviation between the speed command and the current speed of the motor And a second torque command current and a weakening current are determined and output according to the range of the torque current corresponding to each of the torques. And a method of controlling a motor. 2. A step of calculating a torque command current from a deviation between a speed command for a motor to be controlled and a current speed of the motor, and a step of setting the torque command current at a current speed without applying a weakening current. And a step of determining whether the sum of the voltage vector of each part of the motor is within the limit circle determined by the applied voltage to the motor, and the sum of the voltage vector of each part of the motor is the applied voltage to the motor. When it is not within the limit circle determined by, the sum of the voltage vector of each part of the motor is within the limit circle determined by the applied voltage to the motor, and the torque current is the command torque current obtained from the deviation of the speed. The step of determining the weakening current and the torque current while appropriately changing the weakening rate under the condition that it becomes equal to the value obtained by multiplying the weakening rate. Control method of the non-motor. 3. A system for controlling a motor using field weakening control, which is a method for controlling a motor in which the motor output is reduced by heat generated by the motor to return to a normal state, in which a weakening current value is fixed. Steps of gradually decreasing the torque current, steps of decreasing the weakening current value and correcting the torque current at that time, steps of holding the final state for a specific time, fixing the weakening current value, 2. The motor control method according to claim 1, further comprising the steps of gradually increasing the current and increasing the weakening current value to correct the torque current. 4. A motor control method for controlling regenerative braking force, the method comprising: a step of calculating a necessary weakening current from a motor speed and a motor speed-torque characteristic; and a torque current calculated from the calculated weakening current value. The method of controlling a motor according to claim 1, further comprising a step of calculating.