JPH04145887A - Controlling method for starting motor-driven driving system - Google Patents

Abstract

PURPOSE:To suppress the vibration of a driving system so as to easily control the acceleration of the driving system at the time of starting the driving system by gradually increasing the input to a motor as the time elapses so as to suppress the accumulation of energy in an elastic element when the driving system is started. CONSTITUTION:When the input to a motor 1 is gradually increased as the time elapses at the time of starting a driving system, such a characteristic that the speed Vm of the motor 1 gradually increases is obtained as shown by the broken line in the figure. The energy released from an elastic element corresponds to the area S2, but the acceleration of a load is small, since the energy is naturally smaller than the energy released from the elastic element of the conventional motor-driven driving system. When the input to the motor 1 is controlled so that the speed Vm of the motor 1 and the moving speed VL of a load 2 can coincide with each other at the time when the energy is completely released from the elastic element, vibration of a driving system can be prevented at the time of starting the driving system.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for starting and controlling an electric drive system in which a load having an elastic element is driven by an electric motor.

[Prior Art] It may be necessary to provide an elastic element such as a spring in a path for transmitting power from an electric motor to a load. Further, since a member provided in a path for transmitting power to a load has elasticity, it may become an elastic element. 11th
The figure shows an example of an electric drive system having an elastic element in the power transmission system to the load. In the figure, 1 is an electric motor, 2 is a load, and 3 is a spring as an elastic element. The load 2 is a so-called slider, and is provided so as to slide on the kite rail 4. A pulley 5 is attached to the output shaft of the electric motor 1, and pulleys 6 and 7 are attached to the load 2. Further, pulleys 9 and 10 are attached to the fixed frame 8, and the pulley 6, pulley 5. 9. A wire 11 is passed between the wire 10 and the pulley 7. and wire 11
one end is connected to the fixed frame 12 via the spring 3,
The other end of the wire 11 is fixed to the fixed frame 8.

In this electric drive system, a spring 3 is provided to apply tension to the wire 11, and in a stationary state, the spring 3 is stretched by a predetermined amount.

In this electric drive system, the speed VL of the load is controlled, for example, as shown in FIG. That is, the electric motor is started to increase the speed of the load, and after the load speed VL reaches the specified speed Vn, the vagina speed Vn is maintained, and when the load reaches the target position, the electric motor is braked and stopped. . In FIG. 10, a period T1 is a startup period in which the speed VL of the load is increased to the specified speed Vn. Further, the period T2 is a constant speed operation period in which the speed of the load is maintained at the specified speed Vn, and the period T3 is a deceleration period.

In this type of conventional electric drive system, the waveform of the drive voltage applied to the electric motor is pulsed, and the drive ratio (duty ratio) of the electric motor is kept constant for startup. The operation during the startup period T1 in this case is as follows.

When the electric motor 1 is driven at time 1=0 and the pulley 5 is rotated counterclockwise in the figure, the wire 11 moves in the direction of the arrow H.
driven in the direction. In the initial state where the load 2 is stationary, the friction between the load 2 and the guide rail is static friction, so the frictional load is large. When the electric motor 1 is started in this state with a constant drive ratio, the speed Vm [m/+ecl of the electric motor increases linearly with a constant acceleration, but at first a large amount of energy is required to store energy in the elastic element 3. Since energy is used, the speed of the load VL [m/s
ec] can be suppressed to a small rate of increase. After that, the energy stored in the spring is released in accordance with the time constant of the drive system, so the rate of increase in the speed of the load increases. When the spring's stored energy is exhausted, the rate of increase in speed becomes smaller because energy is used to store the spring again.

FIG. 9 shows an enlarged view of the operation during the startup period T1. The straight line in FIG. 9 shows the motor speed Vm, and the curve shows the load moving speed VL. During period A in Fig. 9, the electric motor is started, but the load cannot move due to static friction, and the spring 3 stretches (
energy is stored in the spring). When period B begins, the load starts to move, but since the speed of load movement is slower than the speed of the electric motor, the spring 3 continues to stretch. Once in period C, the spring 3 is compressed to its initial length (spring releases energy) and accelerates the load above the speed of the motor. In period D, the spring is further compressed and the load moves at a speed higher than the speed of the motor. When period E begins, the spring begins to stretch again (energy is stored in the spring), so the moving speed of the load becomes slower than the moving speed of the motor. Thereafter, the same operation as in period BD is repeated while the speed of the load increases.

In FIG. 9, during periods A and B, energy corresponding to the area S1 of the shaded portion in the figure is accumulated in the spring, and during periods C and D, the area S2 of the shaded portion is accumulated in the spring. Energy corresponding to is released from the spring. Here, the area S1 and the area S2 are equal.

In addition, when the electric motor rotates clockwise in Fig. 11, the spring 3
shrinks. Therefore, the influence of the spring 3 appears, although not as much as when the electric motor is driven counterclockwise, and the same phenomenon as described above occurs.

[Problems to be Solved by the Invention] As described above, in the conventional drive system, energy is repeatedly stored in the elastic element and energy is released from the elastic element during startup. However, as shown in the starting characteristics shown in FIG. 9, the speed VL of the load 2 pulsates, causing the drive system to vibrate.

As shown in Figure 9, if the drive system vibrates during startup, there are problems such as difficulty in controlling acceleration during startup, abnormal noises during startup acceleration, and shortened life of mechanical parts of the drive system. was there.

An object of the present invention is to suppress vibrations in the drive system when starting an electric drive system in which an elastic element is included in the power transmission system to the load, to facilitate acceleration control at the time of start-up, and to The purpose of this invention is to propose a start control method for an electric drive system that can extend the life of the electric drive system.

[Means for Solving the Problems] The present invention relates to a method for starting control of an electric drive system in which an elastic element is included in the power transmission system that transmits the driving force of an electric motor to a load. gradually increases the input to the motor over time to suppress the accumulation of energy in the elastic element during start-up.

In the invention in Box 2, after starting the load by applying a predetermined input to the electric motor, the input to the electric motor is temporarily reduced to suppress the acceleration of the load due to the release of energy from the elastic element, and then the load is The input to the electric motor is increased so that the acceleration of the motor approaches the target value.

In the invention of Box 3, each instantaneous speed of the electric motor is required to suppress the speed fluctuation of the load caused by the accumulation of energy in the elastic element and the release of energy from the elastic element during startup. At the same time, a motor speed detection signal indicating the speed of the motor is obtained, and an input to the motor is made so as to make the deviation between the mold motor speed detection signal and the set speed signal at startup zero. Control.

In the invention in Box 4, upon startup, the speed of the load and the speed of the motor are detected, and the input to the motor is controlled so as to reduce the deviation between the speed of the load and the speed of the motor to zero.

[Function] As in the first invention above, when the input to the electric motor is increased over time so as to suppress the accumulation of energy in the elastic element during startup, energy is released from the elastic element. Since the energy is reduced, an increase in the speed of the load due to the release of energy from the elastic element is suppressed, and vibrations in the drive system are suppressed.

As in the invention in Box 2, after starting a load by applying a predetermined input to the electric motor, once the input to the electric motor is reduced to suppress the acceleration of the load due to the release of energy from the elastic element, Since the amount of energy stored in the elastic elements can be reduced, vibrations in the drive system can be suppressed.

δ Also, as in the third invention, a start-up set speed signal indicating each instantaneous speed of the electric motor necessary to compensate for speed fluctuations of the load due to the elastic element is generated, and a motor speed detection signal indicating the speed of the electric motor is generated. By controlling the input to the motor so that the deviation between the speed signal and the set speed signal at startup is zero, the accumulation of energy in the elastic element and the acceleration of the load due to the release of energy from the elastic element can be minimized. Since the engine can be started while the engine is running, vibrations in the drive system can be suppressed.

Furthermore, as in the fourth invention, when the load speed and the motor speed are respectively detected and the input to the motor is controlled so as to make the deviation between the load speed and the motor speed zero, as a result, the elastic element Since the accumulation of energy and the release of energy are suppressed, vibrations in the drive system can be reduced.

[Examples] Examples of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows the overall configuration of an embodiment of the present invention, and in this embodiment, it is assumed that the electric drive system of FIG. 11 is controlled according to the time chart of FIG. 10.

In FIG. 1-, 1 is an electric motor, and 2 is a load driven by the electric motor 1-. The power transmission system from the electric motor 1- to the load 2 includes an elastic element such as a spring (spring 3 in FIG. 11).

A speed detector 20 detects the speed of the motor 1 and generates a motor speed detection signal, and this speed detector generates, for example, a pulse proportional to the speed of the output shaft of the motor.

Reference numeral 21 denotes a set speed generating means, which outputs a start-up set speed signal indicating the set speed of the electric motor at each moment of start-up according to a function indicating the speed characteristics that the electric motor needs to have in order to suppress vibrations in the drive system. do.

Reference numeral 22 denotes a speed control unit for controlling the speed of the electric motor 1, which inputs the output of the speed detector 20 and a set speed signal given from the set speed generating means 21, and adjusts the detected speed of the motor to match the set speed. By controlling the input to the motor 1, the speed of the motor is controlled.

As already explained, in the conventional electric drive system, as shown in FIG. 9, the drive system vibrates due to repeated accumulation of energy in the elastic element and release of energy from the elastic element. At startup, the load cannot move at first due to large static friction, so the driving force of the electric motor is absorbed by the elastic element, and a large amount of energy corresponding to the area S1 is stored in the elastic element. The load is then accelerated beyond the speed of the motor until this large amount of energy is released (until S2=Sl), resulting in large vibrations at startup.

As a result of analyzing the mechanism of vibration at startup as described above, the present inventor has determined that the speed Vm of the electric motor 1 should be controlled to reduce the energy initially accumulated in the elastic element, or that the energy accumulated in the elastic element should be reduced. We focused on the fact that vibrations in the drive system can be suppressed by controlling the speed of the motor to suppress load acceleration due to energy release.

In order to reduce the energy initially stored in the elastic element, the input supplied to the electric motor at startup may be gradually increased over time.

When a constant input is given to the motor at startup, as shown in Figure 9, the speed Vm of the motor increases linearly at startup even though the load cannot move, and the elastic element A lot of energy is stored in. On the other hand, if the input supplied to the motor at startup is gradually increased over time, a characteristic is obtained in which the speed Vm of the motor gradually increases at startup, as shown by the broken line in FIG. In this case, energy corresponding to the area S1 shown in the figure is stored in the elastic element, but this energy is equal to the energy stored in the elastic element at the initial stage of startup in the conventional electric drive system (the area S1 in FIG. much less than the equivalent). Next, the energy released from the elastic element corresponds to the area S2 (-3I) in Fig. 6, but since this energy is naturally smaller than the energy released from the elastic element in the conventional electric drive system, the energy is Acceleration of the load due to discharge is slight.

By controlling the input to the motor so that the speed Vm of the motor and the moving speed L of the load match exactly at the time when the energy release from the elastic element is completed, vibrations in the drive system at startup can be prevented. It can be prevented.

In reality, it is difficult to ideally control the input to the motor as described above, but by increasing the input to the motor at the beginning of startup over time, the By reducing the amount of energy used,
Since it is certain that the amplitude of the vibration that occurs afterwards can be suppressed, it is possible to reliably suppress the vibration of the electric drive system, and it is possible to converge the load speed VL to the motor speed Vm in a short time. .

In order to change the input given to the motor over time, for example, the waveform of the drive current or drive voltage given to the motor is made into a pulse waveform, and the pulse width (driving time) td is changed while keeping the period T constant. Accordingly, the drive ratio td/T may be increased or decreased. Further, in this case, the driving ratio td/T may be increased or decreased by keeping the driving time td constant and changing the period T.

Furthermore, instead of changing the drive ratio, the magnitude of the drive voltage or drive current applied to the motor 1 may be changed.

In the example shown in Figure 6, by controlling the input to the electric motor at startup so that it gradually increases over time, the accumulation of energy in the elastic element is reduced and vibration is suppressed, but the electric motor After starting the electric motor by applying a predetermined input to the electric motor, the input to the electric motor is temporarily reduced to lower the speed Vm of the electric motor, thereby suppressing the acceleration of the load due to the release of energy from the elastic element. Vibrations in the electric drive system can also be suppressed by controlling the input to the electric drive system.

Figure 7 shows an example of this. In this example, the same input as when starting the electric motor with a constant acceleration as shown in Figure 9 is used, as shown by the dashed line curve a in the figure. is applied to the motor, and after the load starts moving, the speed Vm of the motor is reduced by reducing the input to the motor,
Acceleration of the load due to release of energy (corresponding to area S1) accumulated in the elastic element is suppressed. Then, the input supplied to the motor is once decreased, and then gradually increased, so that the speed of the motor matches the speed of the load when the energy stored in the elastic element (energy corresponding to area S2) has been released. It's in control.

Figure 8 shows another example in which the input to the electric motor is controlled so as to suppress the acceleration of the load due to the release of energy from the elastic element.
After applying a sufficiently larger input to the motor than in the example shown in the figure to start the load in a shorter time than in the case of Fig. 7, immediately reduce the input applied to the motor to lower the speed of the motor.
Acceleration of load due to release of energy from the elastic element is suppressed. The point in FIG. 7 that after decreasing the input to the motor, the input is gradually increased to control the speed of the motor to match the speed of the load when the release of energy from the elastic element is completed. Similar to the example.

In order to perform the control shown in FIGS. 6 to 8,
The motor speed Vm shown by the chain lines in FIGS. 6 to 8 is expressed as a time function V s (t), and the set speed generating means 21 calculates the set speed Vs at each time t based on this function. Then, a startup set speed signal indicating the set speed Vs is generated. Then, the motor speed detection signal obtained from the speed detector 20 and the set speed signal at startup are input to the speed control unit 22 so that the deviation between the two signals becomes zero (the motor speed Vm matches the set speed Vs). control the human power to the electric motor 1 so as to

Control algorithms for controlling the above electric motor using a microcomputer are shown in FIGS. 3 and 4. In the case of this control algorithm, the set speed generating means is realized by a microcomputer. First, the third
As shown in the figure, the detected value Vmx of the speed detector 20 is read as the current speed Vm of the electric motor, and this speed Vm is compared with the specified speed Vn,000. Initially, the speed Vm is the specified speed Vn (first
Since the speed calculated based on the function ■ (0 is set as the current set speed Vs of the motor, this set speed and the speed Vm of the motor are compared. As a result, the speed Vm of the motor is set When the motor speed is smaller than Vs, the input to the motor is increased, and when the motor speed Vm is larger than the set speed ■s, the input to the motor is decreased to bring the motor speed closer to the set speed Vs. The speed Vm can be changed along the curves shown by the dashed lines in Figures 6 to 8.The speed V of the motor
When the speed reaches the specified speed Vn, it is determined that the startup has been completed, and the process proceeds to the process shown in FIG.

In this process, first, it is determined whether the load has reached the target position. This target position can be determined, for example, by driving a limit switch when the load reaches the target position.

If the load has not reached the target position, the detected value VmX of the speed detector is read as the motor speed Vm, and the speed Vm is compared with the specified speed Vn.

As a result, if the speed Vm is larger than the specified speed Vn, the input to the motor is decreased, and if the speed Vm is smaller than the specified speed Vn, the input to the motor is increased to bring the motor speed to the specified speed. keep.

Then, when it is detected that the position of the load has reached the target position, a deceleration command is generated, for example, the drive current applied to the motor is reversed, thereby applying braking to the motor and stopping the motor.

FIG. 2 shows another embodiment of the present invention. In this embodiment, a speed detector 23 for detecting the speed of the load 2 is provided in addition to the speed detector 20 for detecting the speed of the electric motor 1-. The outputs Vmx and VLX of the speed detectors 20 and 23 are input to the speed control section 22. The speed control unit 22 receives the outputs of the speed detectors 20 and 23 and controls the input to the motor 1 so as to make the deviation between the speed of the motor and the speed of the load zero. FIG. 5 shows a control algorithm for performing this control. In this example, first, the speed detector 2
The output Vmx of is taken in as the motor speed Vm at that time, and this speed Vm is compared with the specified speed Vn. As a result, when the speed Vm is smaller than the specified speed Vn (when the startup is not completed), the output VLX of the speed detector 23 is taken as the load speed VL at that time, and the motor speed Vm and the load speed VL are taken in. Compare with. Motor speed V
When m is smaller than the load speed VL, the input to the motor is increased, and when the motor speed Vm is larger than the load speed ■L, the input to the motor is decreased, so that the motor speed Vm and the load speed VL are The input to the motor is controlled so that the deviation from the

When the speed Vm of the electric motor reaches the specified speed Vn, it is determined that the startup has been completed, and the process proceeds to the process shown in FIG. 4.

In the embodiment shown in FIG. 5, the speed Vm of the electric motor is the specified speed Vn.
However, if the load speed is detected, the load speed VL is compared with the specified speed Vn, and the startup is determined to be complete when the speed reaches VLVn. It may also be determined.

In the process shown in Figure 4, after the start-up is completed, the motor speed Vm
is equal to the load speed V, L, compare the motor speed Vm with the specified speed Vn and set the load speed to the specified speed V.
Constant speed control is performed to maintain the load speed VL at the specified speed Vn, but if a speed detector is provided to detect the load speed VL, the load speed VL is compared with the specified speed Vn and the load speed VL is maintained at the specified speed Vn. It is also possible to perform control to maintain the current level.

[Effects of the Invention] As described above, according to the invention described in claim 1, the input to the electric motor is increased over time so as to suppress the accumulation of energy in the elastic element during startup. As a result, the energy released from the elastic element can be reduced, and the increase in the speed of the load due to the release of energy from the elastic element can be suppressed, thereby suppressing the vibration of the drive system.

According to the invention set forth in claim 2, after starting the load by applying a predetermined input to the electric motor, the input to the electric motor is temporarily reduced to suppress acceleration of the load due to release of energy from the elastic element. As a result, it is possible to reduce the subsequent accumulation of energy in the elastic elements, and it is possible to suppress vibrations of the drive system.

Further, according to the invention described in claim 3, a set speed signal at startup indicating each instantaneous speed of the electric motor necessary to compensate for speed fluctuations of the load due to the elastic element is generated, and a motor speed indicating the speed of the electric motor is generated. Since the input to the motor is controlled so that the deviation between the detection signal and the set speed signal at startup is zero, the load is accelerated by accumulating energy in the elastic element and releasing energy from the elastic element. It is possible to start the engine while minimizing the amount of vibration, and vibrations in the drive system can be suppressed.

Furthermore, according to the invention set forth in claim 4, the speed of the load and the speed of the electric motor are detected, respectively, and the input to the electric motor is controlled so as to reduce the deviation between the speed of the load and the speed of the electric motor to zero. Therefore, as a result, accumulation of energy in the elastic element and release of the energy can be suppressed, and vibrations of the drive system can be reduced.

[Brief explanation of the drawing]

FIG. J and FIG. 2 are block diagrams showing the configurations of different embodiments of the present invention, FIGS. 3 to 5 are flowcharts showing the control algorithm of the embodiment of the present invention, and FIG.
8 through 8 are diagrams showing the speed characteristics at startup in different embodiments of the present invention, FIG. 9 is a diagram showing the speed characteristics at startup of a conventional electric drive system, and FIG. 10 is a diagram showing the speed characteristics at startup of the conventional electric drive system. A time chart showing the operation of the load, and FIG. 11 is a configuration diagram showing an example of the configuration of the electric drive system. DESCRIPTION OF SYMBOLS 1... Electric motor, 2... Load, 20.23... Speed detector, 22... Speed control part. t [sec] -

Claims (4)

[Claims] (1) In a start-up control method for an electric drive system in which an elastic element is included in the power transmission system that transmits the driving force of the electric motor to a load, the electric motor is controlled to suppress the accumulation of energy in the elastic element during start-up. 1. A method for controlling start-up of an electric drive system, characterized by gradually increasing an input to the motor over time. (2) In a start control method for an electric drive system in which an elastic element is included in the power transmission system that transmits the driving force of the electric motor to the load, after starting the load by applying a predetermined input to the electric motor,
suppressing the acceleration of the load due to the release of energy from the elastic element by once reducing the input to the electric motor;
A method for starting control of an electric drive system, the method comprising: then increasing input to the electric motor so as to bring the acceleration of the load closer to a target value. (3) In a start control method for an electric drive system in which an elastic element is included in the power transmission system that transmits the driving force of the electric motor to a load, energy is accumulated in the elastic element of the load at the time of start-up and from the elastic element. generating a startup set speed signal indicating each instantaneous speed of the electric motor necessary to suppress speed fluctuations of the load caused by the release of energy; and obtaining a motor speed detection signal indicating the speed of the electric motor; 1. A start control method for an electric drive system, comprising controlling an input to the electric motor so that a deviation between a motor speed detection signal and a start-up set speed signal is zero. (4) In a start-up control method for an electric drive system in which the power transmission system that transmits the driving force of the electric motor to the load includes an elastic element, at the time of start-up, the speed of the load and the speed of the electric motor are respectively detected and the load is controlled. 1. A method for controlling start-up of an electric drive system, comprising controlling an input to the electric motor so as to make a deviation between the speed of the electric motor and the speed of the electric motor zero.