JPH0345188A - Controller for motor - Google Patents

Abstract

PURPOSE:To eliminate the delay of the speed of a motor or the vibration of the same by a method wherein a voltage, impressed on the motor upon starting, is increased gradually to determine the control constant of the speed control of a speed control means by a voltage, impressed on the motor when the rotation of the same is started, whereby the speed of the motor is controlled. CONSTITUTION:A voltage, impressed on a motor 1 upon starting the same, is increased gradually to estimate a load for the motor 1 by a voltage, impressed on the same when the rotation of the motor 1 is started, to control the speed of the motor 1 employing the control constant of the operational control of a speed control means 4, which is obtained experimentally and previously in accordance with the magnitude of the load or obtained by calculation. In this case, the optimum control constant is determined in accordance with the load of the motor 1 upon starting the same. According to this method, the speed of the motor may be controlled without any delay of the speed of the motor or vibration of the same even under no load condition or loaded condition.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a motor control device for smoothly controlling the speed of a motor even when the load changes.

BACKGROUND OF THE INVENTION In recent years, unmanned, self-propelled vehicles have come into widespread use as factories become increasingly unmanned and automated. Such self-propelled vehicles are powered by storage batteries, run at a constant speed, and require smooth start-up and stop control. The motor control device is generally constructed as shown in FIG. In Fig. 4, 1 is the motor, 2 is an encoder that generates pulses in proportion to the amount of rotation of the motor 1, 3 is a speed command means that gives a speed command for the motor 1, and 4 is a speed controller that calculates the speed from the pulse signal of the encoder 2. speed control means for calculating the voltage applied to the motor 1 and outputting a PWM signal so that the rotation speed of the motor 1 follows the speed command;
is a driving means that amplifies the PWM signal and supplies power to the motor 1.

The speed control means 4 may be composed of an analog circuit or a digital circuit. If it is composed of digital circuits, for example, "System and Control JVO 1, 26, No.

11, pp. 695-703.1983. A speed control block diagram of the speed control means 4 when constructed from a digital circuit is shown in FIG.

In the block diagram of FIG. 3, the portion surrounded by broken lines is a block diagram of the motor. Kt is the induced voltage constant of the motor, Ke is the torque constant of the motor, J is the moment of inertia of the motor and load, and R and L are the resistance and inductance of the motor windings.

There are two ways to detect speed: one is to calculate the number of encoder pulses that come in within a certain sampling time, and the other is to calculate the speed by counting the cycle of encoder pulses using a reference clock and calculating the reciprocal. , either method is fine. The speed calculated above is multiplied by Kf and compared with the command speed, the value obtained by multiplying the speed deviation by Kp and the value obtained by integrating the speed deviation and multiplied by Ki are added, and then the change in detected speed is calculated by Kd. Subtract the multiplied value and use the result as K
Calculate the PWM output by multiplying by v. Kf, Kp, Ki, K
d and kv are control constants. The PWM signal output value vp is calculated using the following formula.

Vp=〈KpXE+KiXI-KdxD) However, with the above method, if the conditions differ greatly between when driving without a load, such as when driving a self-propelled vehicle, and when driving while carrying or towing a heavy object, it is necessary to adjust the If the control constants are set, there will be a large delay with respect to the speed command when a load is applied, and if the control constants are set according to the load condition, vibrations will occur in the no-load condition. There was a problem that this could happen.

In view of the above-mentioned problems, the present invention attempts to control the speed so that there is no speed delay or vibration whether under no load or under load.

Means for Solving the Problems In order to solve the above problems, the present invention provides a motor, an encoder that generates pulses in proportion to the amount of rotation of the motor, speed command means that gives a speed command of the motor, and pulses of the encoder. A speed controller that calculates the speed from the signal, sets the motor's rotational speed, calculates the voltage applied to the motor, and outputs a PWM signal so that the motor's rotational speed follows the speed command.
In a motor control device consisting of a drive unit that amplifies a PWM signal and supplies power to the motor, the voltage applied to the motor is gradually increased when the motor is started, and the speed is adjusted from the applied voltage when the motor starts rotating. A control constant for speed control of the control means is determined to control the speed of the motor.

When a load is applied to the motor and the load torque increases, a large amount of current must flow through the motor, so the voltage applied to the motor at startup varies depending on the size of the load. The present invention gradually increases the voltage applied to the motor when starting the motor, estimates the load size from the applied voltage when the motor starts rotating, and calculates the load size experimentally in advance according to the load size. The speed of the motor is controlled using control constants for the arithmetic control of the speed control means, which have been determined or calculated. Therefore, since the optimum control constant is determined according to the load when starting the motor, the speed can be controlled without speed delay or vibration even when there is no load or under load.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows the constituent countries of the motor control device of the present invention, and FIG. 2 is a flowchart of speed control. First, FIG. 1 will be explained. In FIG. 1, 1 is a motor, and 2 is an encoder that generates pulses in proportion to the amount of rotation of the motor.

3 is a speed command means for giving a speed command to the motor;
1 is a CPU that calculates speed command data, 32 is a CPU 3
1 is a ROM that stores the processing program, 33 is a CP
RAM used temporarily by U31 when executing calculation processing, 3
4 is Ilo for inputting signals from sensors and outputting signals to the outside. 4 is a speed control means that calculates the speed from the pulse signal of the encoder, sets it as the rotational speed of the motor, calculates the voltage applied to the motor 1, and outputs a PWM signal so that the rotational speed of the motor follows the speed command; 4
1 is a CPU that performs speed control calculation processing, 42 is a CPU 4
1 is a ROM that stores the processing program, 43 is a CP
Used temporarily by U41 when executing arithmetic processing, or by CPU3
1 and a 2-bot RAM for exchanging data, 44
is a counter that counts pulses from the encoder 2. 5 is a driving means for amplifying the PWM signal and supplying power to the motor; 51 is a DC power supply for driving the motor 1; 52 is a resistor for detecting the current flowing from the DC power supply; 53 is a resistor 52; Current limiting circuit for limiting the detected current, 54.55.56.57 is motor 1
Power MO8FET for passing current to, 58 is CPU
The pulse width data of the PWM signal calculated in step 41 is converted into a pulse width signal proportional to the pulse width data, amplified, and then sent to the power MO8FET5.
4. PWM circuit that sends a gate signal to 55.56.57,
60.61.62.63 are freewheeling diodes.

Next, its operation will be explained. In FIG. 1, it is assumed that the motor 1 is currently stopped. l1034 from outside
When a sensor signal is received to start the motor 1 and rotate it at a certain speed, the CPU 31 reads the preprogrammed processing content from the ROM 32, executes it, and writes speed command data to the two-bit RAM 43. CPU
41 executes a program stored in the ROM 42 and having the contents shown in the flowchart of FIG.

Next, the process will be explained according to the flowchart shown in FIG. C.P.
When the U41 reads the speed command data from the CPU 31 from the 2-bot RAM 43, it sends the pulse width data of a PWM signal of a certain value to the PWM circuit 58, and the PWM circuit 58 converts it into a pulse width signal proportional to the pulse width data. and amplify it to power MO3FET54.55 or power M
Send gate signals to O3FETs 56 and 57 and apply voltage to motor 1. The CPU 41 reads the data of the counter 44 and checks whether the value of the counter 44 has changed. If the value of the counter 44 is changing, it means that the speed is changing. If the value of the counter 44 has not changed, the speed has not changed, so the pulse width data of the PWM signal is increased by a certain value from the previous time and sent to the PWM circuit 58. As in the previous case, the PWM circuit 58 converts the pulse width data into a pulse width signal proportional to the pulse width data, amplifies it, and sends it to the power MO3FET54.55 or the power MO8.
Send gate signals to FETs 56 and 57 to apply voltage to motor 1. Similarly to the previous time, the CPU 41 reads the value of the counter 44 and checks whether the speed has changed. If the speed does not change, the same process is repeated and the voltage applied to the motor 1 is increased. If the speed changes, it is determined that the motor 1 has started rotating, and from the pulse width data of the PWM signal at that time, the tlf l constants Kf, Kp, Kf, Kd, kv
, read the data from the counter 44, calculate the speed, perform calculations similar to the conventional method as shown in the block diagram of speed control in Figure 3, calculate the voltage applied to the motor 1, and set PW.
The pulse width data of the M signal is output to the PWM output circuit 58, and this calculation is repeated to perform speed control. Control constants Kf and Kp determined from pulse width data of PWM signal
, Ki, Kd, and kv are stored in the ROM 42 as a table in the form of a table, which is determined experimentally or calculated in advance depending on the magnitude of the load.

As described above, according to this embodiment, the voltage applied to the motor is gradually increased when the motor is started, the load size is estimated from the applied voltage when the motor starts rotating, and the optimal control constant is determined. Therefore, speed control can be performed to avoid speed delays and vibrations even when there is no load or when a load is applied.

In this embodiment, a DC motor is driven, but an AC
Needless to say, the same applies to motors. Further, although the control block diagram of the speed control means does not include a current control loop which is a minor speed loop, there is no problem even if a current control loop is included by detecting the current.

Effects of the Invention As described above, according to the present invention, the voltage applied to the motor is gradually increased when the motor is started, the load size is estimated from the applied voltage when the motor starts rotating, and the optimum control constant is determined. Since the speed is determined, it is possible to control the speed so that there is no speed delay or vibration even when there is no load or under load.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a motor control device according to an embodiment of the present invention, Fig. 2 is a flowchart of the same speed control, and Fig. 3 is a speed control block diagram of a speed control means configured with a digital circuit. , FIG. 4 is a block diagram of a general motor control device. 1...Motor, 2...Encoder, 3
... speed command means, 4 ... speed control means, 5 ... drive means.

Claims (1)

[Claims] a motor; an encoder that generates pulses in proportion to the amount of rotation of the motor; a speed command means that provides a speed command for the motor; a speed control means for calculating a voltage applied to the motor and outputting a PWM signal so that the rotational speed follows the speed command;
In a motor control device comprising driving means for amplifying a WM signal and supplying power to the motor, the voltage applied to the motor is gradually increased when the motor is started, and the voltage applied to the motor is increased from the voltage applied when the motor starts rotating. A motor control device characterized in that the speed of the motor is controlled by determining a control constant for calculation control of a speed control means.