JPH0332392A - Motor driver - Google Patents

Abstract

PURPOSE:To shorten starting time of a motor by setting the maximum current limiting values of a current limiter at respective motors, and increasing or decreasing the values according to the number of the motors. CONSTITUTION:In a motor driver which can, for example, drive three motors 1a-1c, current limiting value switching units are provided in current limiters 5a'-5c', switching signals 9a-9c are output from a controller 2', the values are switched according to the number of the motors to be started, and the current capacity of a power source 7 is utilized to the maximum limit. That is, the limiters 5a'-5c' switch the values upon reception of a signal. Thus, even if the number of the motors to be driven simultaneously is varied, the power source capacity of the power source 7 can be utilized to the maximum limit. Therefore, starting time can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a motor drive device that is a power supply device with a constant voltage and current capacity and drives a plurality of motors.

[Conventional technology]

FIG. 2 shows a schematic block diagram of a motor drive device according to the prior art. In Figure 2, engineering a.

lb and lc are DC motors A, B, and C, respectively.

2 is a control circuit, and 3a, 3b, and 3c are the aforementioned DCs.
Drive circuits for driving motors A, B, and C, 4a, 4b,
4c is the DC mall 1-A, respectively.

A detection resistor 5a detects the current flowing through B and C.

5b and 5c are the DC motors A and B based on the current values detected by the detection resistors 4a, 4-b and 4c.

A current limiting circuit that limits the maximum current flowing through C, 6a, 6
b, 6c are output from the control circuit 2, and drive circuits 3a, 3
A command signal indicating whether or not to conduct electricity is supplied to b and 3c, and 7 is a power supply device with a constant voltage and current capacity.

Reference numeral 8 is a drive command for instructing which of the DCC motors A, B, and C should be driven, and is given from the outside. In response to the drive command 8I, the control circuit 2 sends finger signals 6a, 6b to the drive circuits connected to the moles 1 to 1 to be rotated.
, 6c, or all of them. According to this command signal, the drive circuit 3a.

3b and 3c transmit power supplied from the power supply device 7 to DC motors A, B, and C, respectively. When starting, a large current flows through a DC motor due to its characteristics.

Detection resistors 4a, 4-b, 4. c, detect the current value, and if the value exceeds a certain value (for example, determined by the current capacity of electronic components used in the drive circuit),
Drive circuit 3 a by current limiting circuits 5 a, 5 b, and 5 c.
The maximum current value is limited by, for example, cutting off power transmission at +3 b r 3 c for a certain period of time. Related devices of this type include, for example, those described in Institute of Electrical Engineers of Japan information processing research material IP-82-34.

[Problem to be solved by the invention]

The above conventional technology does not take into consideration the relationship between the number of motors to be started at the same time and the capacity of the power supply, and even when starting multiple motors from the viewpoint of preventing damage to the power supply due to overcurrent, the total It is necessary to keep the limit value of the current limiting circuit low so that the maximum current of the power supply does not exceed the current capacity of the power supply.For example, when starting only one unit, the current is limited at the low limit value mentioned above. This will cause the startup time to become longer.
There was a problem.

SUMMARY OF THE INVENTION An object of the present invention is to provide a motor drive device capable of driving a plurality of motors, which can shorten the starting time even when driving, for example, - motors.

[Means to solve the problem]

In order to achieve the above object, a current limit value switching section is provided in the current limit circuit (a switching signal is output from the control circuit).
The current limit value is changed according to the number of motors to be started, so that the maximum current capacity of the power supply device can be used.

[Effect]

For example, in a mole driving device that can drive three motors, the control circuit determines the limit value of each current limiting circuit based on the current capacity of the power supply device and the number of moles that are driven at the same time. When driving one unit, set the limit value to one-half of the current capacity of the power supply device, and when driving three units, set the limit value to 1/2 of the current capacity of the power supply device.
1/2 as the limit value) and outputs a switching signal. The current limit circuit receives the signal and switches the limit value. By doing the above, even if the number of motors driven at the same time changes, the power capacity of the power supply device can be used to the maximum.
Start-up time can be shortened.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. In the figure, 1 a, 1. b, 1 c, 3
a, 3b.

3c, 4a, 4b, 4c, 6a, 6b, 6c, and 7°8 are the same as those in the prior art, 2' is a control circuit according to the present invention, and 5a', 5b', and 5c' are current limiters also according to the present invention. Circuits A, B, C, 9a.

9b and 9c are switching signals indicating the limit values of the current limiting circuits A, , B, and C. Similar to the prior art, the control circuit 2'
receives the drive command 8 from the outside, and the drive circuit 3 a +
Command signals 6a and 6b are provided to 3b and 3c.

6c, and the drive circuits 3a, 3b, 3c supply power from the power supply 'JA device to the motors 1.6c in accordance with the command signals 6a, 6b, 6c. a, lb, 1. Tell c.

At that time, the detection resistors 4a, 4-b, 4. The current limiting circuit 5a' is configured so that the maximum value of the current value detected in c is below a certain value.
, 5b' and 5c' provide current limitation. At this time, the control circuit 2' automatically determines how many motors are to be driven at the same time, and changes the current limit value according to the number of motors (for example, when only motor A 1 a is driven, The limit value is the value of the current capacity of the power supply device 7, and the number of modules 1 to 1A is 1.b-2.
When driving the units at the same time, a switching signal (such as setting each limit value to one half of the current capacity of the power supply device 7) is output to switch the current limit value of each current limit circuit.

As described above, according to the present invention, even if the number of motors driven at the same time changes, the power supply device does not always output an overcurrent, and the maximum current can be utilized, so that the starting time of the motors can be shortened. There is an effect.

In addition, in the second embodiment, when driving multiple units at the same time,
Although the current capacity of the power supply device is divided equally, for example, the current limit value may be set large for motors for which starting time is important, and the current limit value may be set small for other motors.

In the above embodiment, three units are driven, but the same applies even if the number of units is changed.

〔Effect of the invention〕

According to the present invention, since the current limit value can be automatically changed depending on the number of cantered units, the current capacity can be utilized to the maximum without damaging the power supply device, which has the effect of shortening the starting time of the motor. .

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram of an embodiment of the present invention, and FIG. 2 is a schematic block diagram of a conventional technique. 1, a, lb, 1c = motor, 2.2'--control device, 5a, 5b, 5c, 5a, 5b', 5c current limiting circuit, 7... power supply device, 9a, 9b.

Claims (1)

[Claims] 1. A plurality of motors, a control circuit that controls the rotation of the motors, a drive circuit that energizes the motors based on a command signal from the control circuit, a detection resistor that detects the current flowing through the motors, and a detection resistor that detects the current flowing through the motors. a current limiting circuit that receives the current value and limits the maximum current to a certain value or less, and a power supply device having a certain voltage and current capacity that supplies power for energizing the motor to the drive circuit. In the motor drive device equipped with the above, the maximum current limit value of the current limit circuit can be set for each motor, and the limit value is increased or decreased according to the number of motors that are started at the same time. Motor drive device.