TW201622337A - Motor control apparatus - Google Patents

Abstract

A motor control apparatus disclosed herein can increase the maximum current of the motor control apparatus while preventing reductions in power cycle life and thermal cycle life of a power semiconductor device, and increase the maximum torque of a motor. The motor control apparatus includes a motor, and a control unit configured to control the motor. Upon driving the motor momentarily, the control unit increases the maximum value of an absolute value of torque of the motor in accordance with an increase of an absolute value of speed of the motor when the absolute value of the speed is less than a predetermined value.

Description

Motor control unit

One embodiment of the present invention relates to a motor control device.

In recent years, in a mechanical device including a motor, in order to reduce the manufacturing cost of using the mechanical device, it is required to shorten the cycle time. To shorten the cycle time, for example, the maximum speed of the motor that drives the mechanism is increased. However, the maximum speed of the motor is limited by the power transmission mechanism. Therefore, there is a limit in increasing the maximum speed of the motor.

On the other hand, in order to shorten the cycle time, it is also considered to shorten the time for acceleration and deceleration of the motor. This is achieved, for example, by increasing the maximum torque of the motor. In order to increase the maximum torque of the motor, for example, increase the maximum output current of the motor control device. However, the power semiconductor element used in the inverter unit of the motor control device is limited to the maximum output current. Therefore, it is difficult to simply increase the output current of the motor control device.

Therefore, for example, a protection function of a power semiconductor element is provided in a motor control device. The protection function limits, for example, the current value flowing to the power semiconductor element to be within a certain value. Thereby suppressing electricity The semiconductor element is used to flow a current greater than the maximum output current.

In particular, in the motor control device that drives the synchronous motor, if the torque is to be obtained by the motor in the stopped state (unrotated state), the current concentrates to a specific phase (one phase). At this time, there is a possibility that a current of a maximum output current or more flows in the power semiconductor element of the specific phase. The protection function suppresses a current equal to or higher than a value allowed by the element from flowing to the power semiconductor element even when the torque is to be obtained by the motor in the stopped state.

Further, the overload protection function protects the power semiconductor element when the time when the rated current is flowing for a predetermined time or longer is determined as an overload state. The predetermined time is based, for example, on the ratio of motor current to continuous rating. Thereby, the load of the power semiconductor element is excessively suppressed by the current of the continuous rated or higher. In other words, the overload protection function suppresses a current exceeding a current allowed by the load factor from flowing to the power semiconductor element.

In connection with the technique of increasing the maximum output current value of the motor control device, an overload integration trip circuit of a inverter is described in Japanese Laid-Open Patent Publication No. Hei 9-93953. The overload integral trip circuit includes an integrator and a comparator. The integrator integrates the difference between the load of the reflux and the predetermined amount. The comparator outputs a trip signal of the inverter when the output of the integrator exceeds a predetermined value.

The overload integral trip circuit has an overload integration time characteristic. That is, in the overloaded integral trip circuit, the amount of integration obtained by the integrator is increased in a frequency range lower than a predetermined frequency.

In this technique, when the current is concentrated in the power semiconductor element of a specific phase, the operational time is shortened. Thereby, it is possible to increase the maximum output current of the motor control device while increasing the torque while suppressing the overload.

However, in a motor control device used for pushing or the like, the motor in a stopped state outputs torque for a predetermined period of time. Therefore, it is difficult to apply the technique of Japanese Laid-Open Patent Publication No. Hei 9-93953. In the technique of Japanese Laid-Open Patent Publication No. Hei 9-93953, the overload detection time in the low speed range is short. Therefore, by operating the protection function in the middle, there is a possibility that the torque output of the motor is stopped.

On the other hand, the power semiconductor element has a power cycle life or a thermal cycle life. In applications such as pushing, if the maximum output current of the motor control device is increased, the temperature of the specific phase changes drastically, and the life may be shortened.

In the case of rapid acceleration/deceleration, if the motor is suddenly accelerated from the stop state, the maximum current will flow to a specific phase. Even in the case where the motor is stopped with rapid deceleration, the maximum current flows to a specific phase. If the acceleration from the same position is repeated or stopped at the same position, there is a possibility that the life of the specific phase is shortened.

In the technique of the Japanese Patent Publication No. Hei 9-93953, the technique of the action protection operation at a low speed is known.

Japanese Laid-Open Patent Publication No. 2002-218779 discloses a technique of controlling an AC servo motor by an AC servo driver having a protection function. More specifically, the overload protection device for the AC servo motor described in Japanese Laid-Open Patent Publication No. 2002-218779 controls the mechanical device by an AC servo motor.

The overload protection device of the AC servo motor has an overload limiting portion. The overload limiting unit transmits a speed signal detected by a speed detector provided in the AC servo motor through a speed monitoring unit provided in the AC servo driver. The overload limiting portion has a limiter characteristic as shown below. That is, the speed signal to which the overload limiting unit is introduced sets the output signal of the AC servo motor to the lowest torque limiter value (100 of the rated torque of the AC servo motor) during the period of ±N1. %). On the other hand, when the speed signal exceeds ±N1 and becomes ±N2, the output signal of the AC servo motor is set to the maximum torque limiter value (300% of the rated torque of the AC servo motor). ).

In the technique of Japanese Laid-Open Patent Publication No. 2002-218779, the output signal to the AC servo motor is set to the lowest torque limiter value (the rated torque of the AC servo motor during the speed signal to ±N1). 100%). As a result, the AC servo motor and the entire system are stopped by the overload monitoring function.

However, as described above, in the technique of Japanese Laid-Open Patent Publication No. Hei 9-93953, the overload detection time in the low speed range is short. Therefore, by operating the protection function in the middle, there is a possibility that the torque output of the motor is stopped.

Further, in the technique of Japanese Laid-Open Patent Publication No. 2002-218779, the torque is reduced during the speed signal to ±N1. Therefore, if it will be normal When the motor accelerates and decelerates, there is a problem that the acceleration and deceleration time becomes longer. Therefore, it is difficult to shorten the cycle time.

The present invention has been made to solve the above problems. One object of the present invention is to provide a motor control device as shown below. This motor control device can increase the maximum current of the motor control device and increase the maximum torque of the motor while suppressing shortening of the power cycle life and the thermal cycle life of the power semiconductor element.

A motor control device according to an embodiment of the present invention includes: a motor; and a control unit that controls the motor, wherein the control unit drives the motor instantaneously, and when an absolute value of a speed of the motor does not reach a predetermined value, The increase in the absolute value of the aforementioned speed increases the maximum value of the absolute value of the torque of the aforementioned motor.

It is preferable that the control unit has a semiconductor that controls electric power supplied to the motor, and when the absolute value of the speed of the motor is zero, the maximum value of the absolute value of the torque of the motor, that is, T1, is as described above. At least one or more of the junction temperature, the power cycle life, and the thermal cycle life of the semiconductor are determined.

It is preferable that the maximum value of the absolute value of the torque of the motor when the absolute value of the speed of the motor is equal to or greater than the predetermined value is T3, which satisfies the relationship of T3>T1.

It is preferable that the predetermined value is set to avoid the speed of thermal destruction of the semiconductor.

According to the motor control device described above, it is possible to increase the maximum current of the motor control device and increase the maximum torque of the motor while suppressing shortening of the power cycle life and the thermal cycle life of the power semiconductor element.

1‧‧‧Motor control unit

10‧‧‧Speed Detection Department

11‧‧‧About the Ministry of Absolute Value

12‧‧‧Torque Limiter

13‧‧‧ Torque controller

20‧‧‧Motor

21‧‧‧Encoder

100‧‧‧Control Department

Fig. 1 is an explanatory view of a motor control device according to an embodiment of the present invention.

Fig. 2 is a characteristic diagram of a torque limit value of a motor control device according to an embodiment of the present invention.

Fig. 3 is a characteristic diagram of a torque-rotation speed of a conventional motor control device.

Fig. 4 is a characteristic diagram showing a torque-rotation speed of a motor control device according to an embodiment of the present invention.

For the purposes of explanation, various specific details are set forth However, it is apparent that more than one embodiment can be implemented without such specific content. In other instances, well-known structures and devices are illustrated in schematic form to simplify the illustration.

Embodiments of the present invention will be described below.

Fig. 1 is an explanatory view of a motor control device according to an embodiment of the present invention.

The motor control device 1 includes a control unit 100, a motor 20, and an encoder 21. The control unit 100 includes a speed detecting unit 10, an absolute value unit 11, a torque limiter unit 12, and a torque controller 13. horse The control device 1 receives power supply from an external power source.

The control unit 100 drives the motor 20. The rotation (rotation speed) of the motor 20 is detected by the encoder 21. The rotational speed (speed) of the detected motor is input to the motor control device 1.

A description will be given of a portion for controlling the motor 20.

The position of the motor 20 is converted into an electric signal (hereinafter referred to as "motor rotation signal") by the encoder 21, and is output to the speed detecting portion 10 of the control unit 100.

The speed detecting unit 10 differentiates the motor rotation signal (motor position signal) to calculate the speed (rotation speed). The speed detecting unit 10 outputs the calculated value (hereinafter referred to as "speed value") to the absolute value converting unit 11.

The absolute value unit 11 performs absolute value of the velocity value. The absolute value unit 11 outputs the absoluteized speed value to the torque limiter unit 12 as the rotational speed value.

The torque limiter unit 12 receives a rotational speed value (absolute value) and a torque command value of the motor 20 from the absolute value unit 11. The torque limiter unit 12 controls the value to be output to, for example, the torque controller 13 in accordance with the characteristic map of the torque limit value shown in FIG. 2 which will be described later.

More specifically, the torque limiter unit 12 directly outputs the torque command value as long as the absolute value of the torque command value does not reach the maximum value of the absolute value of the torque set for each of the rotational speed values. Output to the torque controller 13.

On the other hand, the torque limiter unit 12 is the absolute value of the torque command value. When the value is equal to or greater than the maximum value of the absolute value of the torque set for each rotation speed value, the torque limit value shown in the following (1) and (2) is output without the value of the torque command value.

(1) If the torque command value is positive, it is the maximum value of the absolute value of the torque.

(2) If the torque command value is negative, the value is the maximum value of the absolute value of the torque multiplied by -1.

Figure 2 is a characteristic diagram of the torque limit value. Regarding Figure 2, it will be detailed later.

The torque controller 13 drives the motor 20 in accordance with the input torque command value or torque limit value. Thereby, the motor 20 is controlled to output, for example, a predetermined torque.

The motor 20 is controlled by the above works. Next, the characteristics of the torque limit value of the motor control device 1 in the embodiment of the present invention will be described. As described above, Fig. 2 is a characteristic diagram of the torque limit value of the motor control device 1 in the embodiment of the present invention.

The absolute value of the rotational speed of the horizontal axis motor 20, that is, the rotational speed value output by the absolute value unit 11. The vertical axis is a torque limit value that is output by the torque limiter unit 12. That is, the vertical axis corresponds to the maximum value of the torque (the maximum value of the allowable torque) that is set for the absolute value of each rotational speed. That is, when the rotational speed value of the motor 20 is within a predetermined range, the motor 20 is allowed to output torque in a range that becomes the inner side of the line shown in FIG. 2.

Here, the torque limit value of the motor control device 1 is as shown in FIG. 2, and the same characteristic is displayed in the positive direction or the opposite direction, and thus the relative horizontal axis (torque horizontal axis) is symmetrical.

Here, the characteristic map of the torque limit value of the motor control device shown in FIG. 2 indicates the maximum value of the allowable torque at the time of instantaneous torque output.

In the characteristic diagram of the torque limit value of the motor control device of Fig. 2, when the rotational speed value is zero, the torque limit value becomes ±T1.

When the absolute value (rotational speed value) of the rotational speed increases from zero to N1 of the predetermined value, the absolute value of the torque limit value (the maximum value of the absolute value of the torque) increases. When the rotation speed value becomes N1, the torque limit value becomes ±T3.

Here, the relationship of T3>T1 is established. Similarly, the relationship of -T3<-T1 is also established.

The torque limit value T1 is a value that is set to maintain the durability of the power semiconductor element when the motor is stopped. Here, for example, the T1 is the same value as the allowable torque value when the absolute value of the rotational speed of the predetermined motor in the prior art is zero (see also FIG. 3). That is, T1 is, for example, the maximum torque value that is allowed when the current is completely concentrated in a specific phase.

When the rotational speed value is equal to or greater than the predetermined rotational speed value N1, the torque limiter unit 12 sets the torque limit value to a constant torque limit value that is higher than the torque limit value T1 when the rotational speed value is zero. T3.

Here, the predetermined rotational speed value N1 is set to a rotational speed value that suppresses a rise in junction temperature due to concentration of a current to a specific phase and a decrease in power cycle life and thermal cycle life in accordance with the characteristics of the motor 20. .

When the rotational speed value is equal to or higher than the rotational speed value N1, it is less likely that current concentrates to a specific phase. Therefore, the maximum output current of the motor control device 1 can be set to a higher value than in the related art.

When the motor current flows to the power semiconductor element of the torque controller 13 of the motor control device 1 for the maximum output current value of the motor control device 1, the junction temperature of the power semiconductor element can be set not to exceed the predetermined temperature. The current value is the same as the current value when the power cycle life and the thermal cycle life are zero and the current concentration is one phase. In other words, for example, the rotational speed value N1 is set to a rotational speed value that avoids or suppresses thermal destruction of the power semiconductor element (semiconductor).

In the past, the maximum torque (torque limit value) was stopped at T1. On the other hand, in the present embodiment, it is possible to increase the maximum current of the motor control device 1 while increasing the maximum torque of the motor 20 while suppressing shortening the life of the power semiconductor element.

Next, the characteristics of the torque-rotation speed of the conventional motor control device and the characteristics of the torque-rotation speed of the motor control device according to the embodiment of the present invention will be described.

Fig. 3 is a characteristic diagram of a torque-rotation speed of a conventional motor control device. Fig. 4 is a characteristic diagram showing the torque-rotation speed of the motor control device in the embodiment of the present invention.

2 shows the maximum value (torque limit value) of the torque that is instantaneously allowed. The actual motor 20 is not only the maximum value of the torque that is instantaneously allowed, but also has the maximum value of the torque that is allowed when the torque is continuously generated. Figures 3 and 4 show both of these.

A region indicating the relationship between the rotational speed value (the absolute value of the rotational speed) when the motor 20 is continuously driven and the maximum value of the absolute value of the torque is referred to as a continuous region. A region indicating the relationship between the rotational speed value when the motor 20 is instantaneously driven and the torque maximum value (the maximum value of the absolute value of the torque) is referred to as an instantaneous region. The maximum value of the torque in the state in which the rotational speed value in the transient region is zero is set to T1 (T1 value). The maximum torque value in a state where the rotational speed value in the continuous region is zero is set to T2 (T2 value). Here, T1>T2 is obtained. The reason is based on the fact that the motor 20 and the semiconductor circuit that supplies electric power to the motor 20 can withstand a high load if it is instantaneous.

As shown in FIG. 3, in the characteristic of the torque-rotation speed (rotation speed value) of the conventional motor control device, the maximum value of the torque in the state where the rotational speed value in the transient region is zero is T1. Until the value of the rotation speed becomes a large value from a small value, the maximum value of the torque is a constant T1. Therefore, when the rotational speed value is large, the motor is not efficiently driven because the torque is small.

Next, the characteristics of the torque-rotation speed (rotation speed value) of the motor control device 1 in the embodiment of the present invention shown in FIG. 4 will be described. As shown in FIG. 4, in the instantaneous region, the value of the rotational speed of the motor 20 increases as it increases from zero, and the maximum value of the torque increases. As described above, T1 is the torque maximum value (the maximum value of the absolute value of the torque) in a state where the rotational speed value in the transient region is zero. T2 is the maximum value of the torque in a state where the rotational speed value in the continuous region is zero. Between T1 and T2, the relationship of T1>T2 is established.

Among them, the power supplied to the motor is made of semiconductor (the half of the power) The conductor element) is controlled. The T1 is determined based on at least one of a junction temperature, a power cycle life, and a thermal cycle life of the semiconductor. Thereby, the durability of the semiconductor can be improved.

In the characteristics of the torque-rotation speed of the motor control device 1 in the embodiment of the present invention, in the instantaneous region, the value of the rotational speed increases from zero, and the maximum value of the torque (the absolute value of the torque limit value) is T1 increases. When the absolute value of the rotational speed becomes a predetermined value, that is, N1 or more, the maximum torque value becomes T3. That is, the control unit 100 is in the transient region, and if the rotational speed value is less than the predetermined value N1, the torque maximum value is increased as the rotational speed value is increased. Therefore, if the rotational speed value of the motor 20 is small, the torque limit value is changed as the rotational speed value increases. Thereby, the maximum torque can be obtained efficiently.

Further, the present invention is not limited to the above embodiment. The technology of the present invention encompasses a variety of variations in construction, construction, and control.

For example, the motor control device 1 can also be controlled by a program. In the above embodiment, the torque limiter unit 12 limits the current output by the motor control device 1 by limiting the torque command value. Alternatively, the current output by the motor control device 1 may be limited by the current command limiter of the torque controller 13.

However, at least one of the torque maximum values T1, T2, and T3 may be set by the control unit 100.

The vertical axis of Fig. 2 can also be referred to as the maximum value of the torque that can be tolerated for the absolute value of each rotational speed. In the absolute value of the predetermined number of rotations, the motor 20 can also be allowed to be only in the inner portion of the line indicated in FIG. Output torque.

Embodiments of the present invention may be the following first to fourth motor control devices.

The first motor control device includes: a motor; and a control unit that controls the motor, wherein the control unit drives the motor instantaneously, and the absolute value of the speed is an absolute value of the speed. The increase increases the maximum value of the absolute value of the torque.

In the first motor control device, the control unit includes a semiconductor that controls electric power supplied to the motor, and the maximum value of the absolute value of the torque when the absolute value of the speed is zero is T1 is determined by at least one or more of the junction temperature, the power cycle life, and the thermal cycle life of the semiconductor.

In the second motor control device, the T3 value having a maximum value of the absolute value of the absolute value of the torque whose absolute value of the speed is a predetermined value is T3>T1 in the control unit.

In the fourth motor control device of any of the first to third motor control devices, in the control unit, the predetermined value is set to a speed at which thermal destruction of the semiconductor does not occur.

The above detailed description is for the purpose of illustration and description. Various modifications and changes can be made by the above teachings. It is not intended to be exhaustive or to limit the invention. Although the present invention has been described in terms of specific language and/or method of operation, it is understood that the invention is not limited to the specific features or acts described. Conversely, the specific features or actions disclosed above are only the scope of the patent application. An exemplary form.

1‧‧‧Motor control unit

10‧‧‧Speed Detection Department

11‧‧‧About the Ministry of Absolute Value

12‧‧‧Torque Limiter

13‧‧‧ Torque controller

20‧‧‧Motor

21‧‧‧Encoder

100‧‧‧Control Department

Claims (4)

A motor control device comprising: a motor; and a control unit that controls the motor, wherein the control unit drives the motor instantaneously, and when the absolute value of the speed of the motor is less than a predetermined value, the speed is The increase in the absolute value increases the maximum value of the absolute value of the torque of the aforementioned motor. The motor control device according to claim 1, wherein the control unit has a semiconductor that controls electric power supplied to the motor, and the absolute torque of the motor when the absolute value of the speed of the motor is zero The maximum value of the value, that is, T1, is determined by at least one or more of the junction temperature, the power cycle life, and the thermal cycle life of the semiconductor. The motor control device according to claim 2, wherein the T1 and the maximum value of the absolute value of the torque of the motor when the absolute value of the speed of the motor is equal to or greater than the predetermined value are T3. Meet the relationship of T3>T1. The motor control device of claim 2, wherein the predetermined value is set to avoid a speed of thermal destruction of the semiconductor.