JP3557924B2 - Motor control device and motor control method - Google Patents

Description

この表において、行は電動機１０の回転数（０、２０００ｒｐｍ、４０００ｒｐｍ、６０００ｒｐｍ）、列は電動機１０の温度（０、１３０度、１４０度、１５０度、１６０度、１７０度）を表す。なお、回転数及び温度がこれらの間の値である場合には、線形補間して出力制限率を求めればよい。
【００１８】
このように、本実施形態では、電動機の温度と回転数に基づいてトルク指令値を決定しているので、電動機の温度保護を図るとともに、特に低回転域においても必要なトルクを得ることができる。
【００１９】
なお、本実施形態では図２に示すように電動機１０の出力制限率Ａを線形に変化させているが、非線形的に変化させてもよい。
【００２０】
また、本実施形態では、Ｔｍ＝Ａ／１００＊Ｔによりトルク指令値を算出しているが、温度に依存する出力制限率Ｂと回転数に依存する出力制限率Ｃとを用いて、Ｔｍ＝Ｂ／１００＊Ｃ／１００＊Ｔによりトルク指令値を算出してもよい。この場合、Ｂは温度が増大するほど低下（出力制限量は増大）し、Ｃは回転数が増大するほど低下（出力制限量は増大）する。
【００２１】
【発明の効果】
以上説明したように、本発明によれば、電動機の回転数によらず最適な出力制限を行うことで、電動機の温度保護及び電動機性能の向上を図ることができる。
【図面の簡単な説明】
【図１】実施形態の構成図である。
【図２】実施形態の出力制限率のグラフ図である。
【符号の説明】
１０ 電動機、１２ 回転数センサ、１４ 温度センサ、１６ コンピュータ、１８ 電力制御回路、２０ アクセル。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a motor control device and method, and more particularly, to limiting the output of a motor.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there is known a technique for limiting the output of a motor used in an electric vehicle or the like based on the temperature of the motor.
[0003]
For example, Japanese Patent Application Laid-Open No. 4-325804 discloses a technique of detecting the temperature of an electric motor and, when the temperature of the electric motor rises, limiting the amount of supply current to prevent heating to reduce the output. The temperature of the motor is, for example, the temperature of the stator.
[0004]
[Problems to be solved by the invention]
When the motor is operated in the low to medium rotation range, the temperature of the stator is almost the same as the temperature of the rotor.There is no problem with the temperature of the motor using the stator temperature, but the motor is continuously operated in the high rotation range. In operation, self-heating occurs due to eddy currents generated in the permanent magnet, and the temperature of the permanent magnet becomes higher than the temperature of the stator. (The temperature of the stator is almost constant regardless of the number of revolutions, but the number of revolutions of the rotor increases. The temperature rises with the increase). Therefore, in the case of a synchronous motor using a permanent magnet for the rotor, it is necessary to increase the output limit of the motor in order to prevent the rotor from heating in a high rotation range and affecting the magnetic field strength of the permanent magnet. is there.
[0005]
However, if the output limiting amount of the motor is uniquely determined so that the rotor is not heated in the high rotation range, the output is limited more than necessary in the low to middle rotation range (low to middle rotation range). As described above, the temperatures of the stator and the rotor are almost the same. Therefore, if the output is limited based on a temperature higher than the temperature of the stator, the output is excessively limited.) Insufficient torque at low speed may cause problems such as a decrease in climbing performance.
[0006]
The present invention has been made in view of the above-mentioned problems of the related art, and has as its object to protect an electric motor and improve electric motor performance by performing optimal output restriction regardless of the number of rotations of the electric motor. It is an object of the present invention to provide an apparatus and a method that can perform the above.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a motor control device that limits the output of a motor in accordance with the temperature of a motor having a permanent magnet on a rotor , wherein a detecting unit that detects a rotation speed of the motor, Control means for limiting the output of the electric motor according to the rotation speed.
[0008]
Also, the present invention provides a motor control method for limiting the output of a motor according to the temperature of a motor having a permanent magnet in a rotor , wherein the output limiting amount of the motor is increased as the rotation speed of the motor increases. And
[0009]
By changing the output limit of the motor according to the number of rotations, that is, by reducing the output limit in the low rotation range and increasing the output limit in consideration of the rise in rotor temperature in the high rotation range, the temperature of the motor is protected. It is possible to achieve both improvement of the motor performance (particularly performance in a low rotation speed range).
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings, taking an electric vehicle (including a hybrid vehicle) as an example.
[0011]
FIG. 1 shows a configuration block diagram of the present embodiment. The AC motor (motor) 10 includes a stator 10a and a rotor 10b. The stator 10a is supplied with three-phase AC from a power control circuit 18 to generate a rotating magnetic field. The power control circuit 18 includes an inverter, converts DC power from a battery (not shown) into AC power, and supplies the AC power to the winding of the stator 10a. The power to be supplied is determined by a computer 16 described later. A permanent magnet is arranged on the outer periphery of the rotor 10b, and rotates synchronously by magnetic interaction with a rotating magnetic field. A drive shaft is connected to the rotor 10 b, and the rotation of the drive shaft, that is, the rotation speed Nm of the electric motor 10 is detected by a rotation speed sensor 12. A temperature sensor 14 is provided on the stator winding as the temperature of the electric motor 10, and detects the temperature of the stator 10 a as the temperature Tm of the electric motor 10. In the case where the rotation speed of the electric motor 10 is low (about 2,000 rpm), the temperature of the stator 10a is almost equal to the temperature of the rotor 10b, and there is no problem with the temperature of the electric motor 10, but when the rotation speed of the electric motor 10 is high ( (About 4000 rpm or more), the temperature of the rotor 10b becomes higher than the temperature of the stator 10a, so that the temperature of the electric motor 10 becomes higher than the detected value in a high rotation range. The detected motor temperature Tm and rotation speed Nm are supplied to the computer 16.
[0012]
The computer 16 calculates a required torque command value based on the accelerator opening signal from the accelerator 20 and outputs the calculated torque command value to the power control circuit 18. When calculating the torque command value, the computer 16 calculates the temperature of the electric motor 10 as in the related art. The calculation is not based only on Tm, but based on the temperature Tm of the electric motor 10 and the rotation speed Nm of the electric motor 10. That is, when the temperature of the electric motor 10 rises, the original torque command value (torque command value determined from the accelerator opening) is limited in order to prevent the heating of the electric motor 10, and the rotation speed of the electric motor 10 is reduced. Even when it rises, the original torque command value is limited. As a result, at the same time as protecting the temperature of the electric motor 10, the output can be limited by a required amount even in a low to middle rotation range, and a sufficient output can be obtained even at a low speed.
[0013]
FIG. 2 shows an output limiting ratio A (%) used when the computer 16 calculates the torque command value. Here, assuming that the original torque command value is T and the torque command value supplied to the power control circuit 18 is Tm, the relationship is Tm = A / 100 * T.
[0014]
In the figure, the horizontal axis represents the temperature of the electric motor 10, and the vertical axis represents the output limiting ratio. In the figure, a solid line 100 indicates an output limiting ratio when the rotation speed Nm of the electric motor 10 is 2000 rpm or less, and a solid line 200 indicates an output restriction ratio when the rotation speed Nm of the electric motor 10 is 4000 rpm or more. In the solid line 100, the output limiting ratio is 100% until the temperature of the electric motor 10 reaches 140 degrees, and the torque command value Tm = T. When the temperature of the electric motor 10 exceeds 140 degrees, the output limiting ratio A continuously decreases from 100% and becomes 0% at 160 degrees. Therefore, when the temperature of the motor 10 exceeds 140 degrees, the torque command value Tm gradually decreases, and at 160 degrees, the torque command value becomes 0, and the motor 10 can be prevented from being heated.
[0015]
On the other hand, in the solid line 200, the output limiting ratio is 100% up to a temperature of the electric motor 10 of 130 degrees, and continuously decreases from 100% when the temperature exceeds 130 degrees, and becomes 0% at 150 degrees. Therefore, similarly to the solid line 100, the motor 10 can be prevented from being heated, and the output is limited from a lower temperature than that of the solid line 100. Therefore, the temperature rise of the rotor 10b due to the increase in the rotation speed of the motor 10 ( As a result, the permanent magnet of the rotor 10b due to the temperature rise can be reliably prevented. In other words, as shown by the solid line 100, when the rotation speed is low, the output is not limited unless the motor 10 reaches a higher temperature, and when the rotation speed is low at the same temperature (for example, 140 degrees), Since the output limiting amount is smaller than that at the high rotation speed (as is clear from the definition, the lower the output limiting ratio A, the larger the output limiting amount), sufficient torque can be obtained even at a low rotation speed. become. In the prior art, the output is limited based only on the temperature of the electric motor 10, and the output is limited as indicated by the solid line 200 regardless of the rotational speed. The advantage of changing the output limiting amount according to the above will be apparent from FIG.
[0016]
Note that FIG. 2 shows only the case where the rotation speed Nm of the electric motor 10 is 2000 rpm or less and 4000 rpm or more. However, when the rotation speed is between 2000 rpm and 4000 rpm, the rotation speed What is necessary is just to define the output limiting ratio A that moves from the solid line 100 to the solid line 200 in accordance with the increase. When the computer 16 calculates the torque command value Tm, the output limiting ratio A is stored in advance in a memory as a map (a two-dimensional map using the temperature and the rotation speed of the electric motor 10 as variables), and the detected electric motor The output limiting ratio A corresponding to the temperature Tm and the rotation speed Nm of 10 may be read from the map. An example of the map is shown below.
[0017]
[Table 1]

In this table, the rows represent the rotation speeds of the motor 10 (0, 2000 rpm, 4000 rpm, 6000 rpm), and the columns represent the temperatures of the motor 10 (0, 130, 140, 150, 160, and 170 degrees). If the rotational speed and the temperature are between these values, the output limiting ratio may be obtained by linear interpolation.
[0018]
As described above, in the present embodiment, the torque command value is determined based on the temperature and the number of rotations of the electric motor, so that the temperature of the electric motor can be protected and a necessary torque can be obtained even in a low rotation region. .
[0019]
In this embodiment, the output limiting ratio A of the electric motor 10 is changed linearly as shown in FIG. 2, but may be changed non-linearly.
[0020]
Further, in the present embodiment, the torque command value is calculated by Tm = A / 100 * T, but Tm = A / 100 * T is used. The torque command value may be calculated from B / 100 * C / 100 * T. In this case, B decreases as the temperature increases (the output restriction amount increases), and C decreases as the rotation speed increases (the output restriction amount increases).
[0021]
【The invention's effect】
As described above, according to the present invention, by performing the optimum output restriction irrespective of the rotation speed of the motor, it is possible to protect the temperature of the motor and improve the motor performance.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an embodiment.
FIG. 2 is a graph showing an output limiting ratio according to the embodiment.
[Explanation of symbols]
10 electric motor, 12 rotation speed sensor, 14 temperature sensor, 16 computer, 18 power control circuit, 20 accelerator.

Claims (2)

In a motor control device that limits the output of the motor according to the temperature of the motor having a permanent magnet in the rotor,
Detecting means for detecting the number of rotations of the electric motor,
In accordance with the stator temperature and the rotation speed of the motor, the output of the motor is limited so that the limit amount increases as the stator temperature increases and as the rotation speed increases. Control means for increasing the limit amount when the rotation speed is large even when the rotation speed is large compared to when the rotation speed is small ;
An electric motor control device comprising: In a motor control method for limiting the output of the motor according to the temperature of the motor having a permanent magnet in the rotor,
As the stator temperature of the electric motor increases, and as the rotation speed increases, the output restriction amount of the motor is increased so that the restriction amount increases. The motor control method characterized by increasing the output restriction amount when is larger than when it is small .

Images