JPS6216085A - Controller for driving of dc motor - Google Patents

Abstract

PURPOSE:To prevent an excess over currents required for acceleration and deceleration of peak currents, and to reduce noises and the vibrations of a device by controlling applied voltage on the basis of a speed command signal, a signal indicating a driving mode and a counter-electromotive voltage signal. CONSTITUTION:A signal Vc from a speed deviation detector 5, a mode indicating signal (m) and a counter-electromotive voltage signal Vm for a motor 1 are inputted to a motor applied-voltage computing element 11, and the computing element 11 conducts required arithmetic operation on the basis of these signals. A voltage control signal Vcv outputting optimum voltage Vv to be applied to the motor 1 and a polarity control signal VD for the motor are outputted from the motor applied-voltage computing element 11. Accordingly, peak currents fed to the motor do not exceed current values necessary for accelerating and decelerating the motor, thus reducing noises, then minimizing the vibrations of the device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a DC motor drive control device for controlling a DC motor used in a positioning servo device such as a table feeding device of a machine tool.

[Background of the invention]

In servo positioning mechanisms using high-output DC motors, chopper drive type DC motor drive control devices are often used. The reason for this is that it has extremely good power efficiency and can therefore be used as a small and inexpensive power element for driving a DC motor. A DC motor drive control device using such a chopper drive method will be explained with reference to the drawings.

FIG. 5 is a block diagram of a conventional DC motor drive control device. In the figure, 1 is a DC motor in the servo positioning mechanism, 2 is a speed detector connected to the DC motor 1, and 3 is a position detector also connected to the DC motor 14. The speed detector 2 outputs a speed signal ay proportional to the rotational speed of the motor 1.
The position detector 3 outputs a position signal Sp proportional to the rotation speed (rotation angle) of the motor 1. Reference numeral 4 denotes a position deviation detector which receives the device signal Sp and the position command signal Sc from the position detector 3 and detects the difference between the two. The position command signal S (is obtained from a numerical control device etc. in the servo positioning mechanism.5 is the difference between the speed signal determined according to the deviation of the position deviation detector 4 and the speed signal Sv output from the speed detector 2 This is a speed deviation detector that detects the difference, and outputs a control signal VC for the motor supply voltage according to the difference.

Reference numeral 6 represents a triangular wave signal generator that generates a triangular wave signal of a constant period, and 7 represents a signal comparison circuit that compares the control signal vc output from the speed deviation detector 5 with the triangular wave signal. The signal comparison circuit 7 outputs a pulse width modulation signal v8. 8 is a DC power supply, which outputs a constant voltage VH. Reference numeral 9 denotes a voltage switching circuit that turns on and off the voltages 2 and 4 in response to a signal v8 from the signal comparison circuit 7, and this turned on and off voltage is supplied to the motor 1.

FIG. 6 is a circuit diagram of the motor and voltage switching circuit shown in FIG. 5. In the figure, %1 is the motor shown in Figure 5, T
rl, Tr2. Tr3. Tr4 is a power transistor and is configured as a bridge circuit. R1, R2, R
,, R4bt resistance, LcH+t cheek fill. Note that RM indicates the resistance of the armature of the motor 1.

In such a conventional control device, the position deviation detector 4
, the speed deviation detector 5 is connected to the speed detector 2 and the position detector 3 to form a positioning servo loop, and outputs a control signal V of the motor supply voltage corresponding to the position command signal sc. Output. This control signal is compared with a constant cycle triangular wave signal in the signal comparison circuit 7, and as a result, the signal comparison circuit 7 outputs a pulse width modulated signal v8 with a duty factor proportional to the control signal. In the voltage switching circuit 9, according to the signal v8, each transistor Tr, to Tr4 performs on/off control and polarity control (
The control voltage shown in FIG.

Here, the value of the constant voltage VH is determined by the back electromotive force MM of the motor 1 when the motor 1 reaches the maximum number of rotations used, the motor current IMA required to obtain the necessary acceleration, and the motor 1's back electromotive force MM Based on the value of armature resistance RM, it is determined to satisfy VH>VMM+'M-RM. This is a necessary condition to ensure the designated acceleration even when the motor 1 is rotating at around the maximum number of rotations used.

However, in the conventional control system described above, a current with a large peak value flows when the motor 1 accelerates or decelerates, which causes noise and vibration of the device. and,
For example, in NC drill devices, there have been problems such as the drill breaking due to vibration. An example of such a motor current peak value is RM=1.5Ω, iMA=4OA
(When performing trapezoidal acceleration/deceleration)? VMM = 80
Describing the case of driving a V motor, 1, V, = 80 + 40 x 1.5 = 140 (V) + 1,
The current when acceleration starts from a stationary state is i = Yuyue =
93 (A) Pl, 5 111, the current when accelerating near the maximum operating speed is lv
, Current when motor 1 decelerates while rotating with back electromotive force around 60V (40XL5). In this case, since it is necessary to apply a voltage of opposite polarity to the motor 1 to decelerate it, the maximum peak 'gL current flows.

In this way, for the required effective current value of 4OA, the maximum
A peak current of 33 A flows, and this peak current is restricted by the choke coil LCH shown in FIG. 6 from the viewpoint of circuit impedance, servo stability, etc., and it is difficult to smooth it sufficiently.

[Purpose of the invention]

An object of the present invention is to provide a DC motor drive control rack that can solve the problems of the prior art described above, suppress peak current, and further reduce noise and vibration of the device being controlled. ? It is on offer.

[Summary of the invention]

To achieve the above object, the present invention outputs a supply voltage signal to the motor based on detection signals of a position detector and a speed detector connected to the motor, and a position command signal, and the supply voltage signal is - 1: Calculate the motor drive voltage and determine its polarity using the overnight back electromotive force signal and the drive mode instruction signal that instructs the motor drive mode (acceleration mode, constant speed mode, deceleration mode), The motor is characterized by chopper control according to the drive voltage and polarity.

[Embodiments of the invention]

Hereinafter, the present invention will be explained based on illustrated embodiments.

FIG. 1 is a block diagram of a DC motor control device according to an embodiment of the present invention. In the figure, parts that are the same as those shown in FIG. 5 are given the same reference numerals and explanations will be omitted. Reference numeral 11 denotes a motor applied voltage calculator which inputs the signal Y (, mode instruction signal m, and back electromotive voltage signal VM of the motor 1) from the speed deviation detector 5, and performs necessary calculations based on these signals. The voltage calculator 11 outputs a voltage control signal vcv for outputting the optimum voltage vv to be applied to the motor 1, and its polarity control signal Vp.12 is a pulse width modulation signal output from the signal comparison circuit 7. This is a DC switching regulator that switches a constant voltage according to a signal v8.The above optimal voltage vv is output from the DC switching regulator 12.The DC switching regulator 12 is controlled by a polarity control signal Y1) from the motor applied voltage calculator 11. This is a voltage polarity inverter that inverts the voltage from DC, and when the polarity control signal VD is negative,
Voltage Vv output from switching regulator 12
Let the voltage be -■v.

FIG. 2 is a circuit diagram of the motor applied voltage calculator shown in FIG. 1. In the figure, 1 is a motor, 2 is a speed detector, and the first
Same as shown in the figure. A differential amplifier 15 extracts the voltage across the speed detector 2 and amplifies it appropriately, and the differential amplifier 15 outputs a signal corresponding to the back electromotive force vM of the motor 1. The back electromotive voltage vM is the motor terminal voltage EE
It can be obtained by detecting vT, motor current iM, and motor internal resistance RMft and calculating V M = V 7 - i M The voltage of speed detector 2 is used.

Reference numeral 16 denotes an absolute value circuit that outputs only the absolute value of the output signal of the differential amplifier 15, and outputs a signal corresponding to the absolute value f of the back electromotive voltage.

Reference numeral 17 denotes an analog selector which is activated by a drive mode signal, and is composed of three switches 17aj17bj17c. The switch 17a closes when the drive mode signal is an acceleration instruction signal and outputs a voltage signal vAc corresponding to the acceleration voltage VAC.
output. The switch 17b closes when the constant speed instruction signal is received, and outputs a voltage signal -vAc corresponding to the voltage -VA. Further, the switch 17c is closed when there is a deceleration instruction signal, and outputs a voltage signal -2vAC corresponding to the voltage -2VAc. The above acceleration, constant speed, and deceleration mode signals are 1
For example, it can be obtained from an NC device or the like. In addition, the accelerating voltage AC
is the value obtained by subtracting the optimal voltage (7) and the back electromotive force (2)M, which corresponds to (iMAxRM).

18 are resistors 18a, 18b, 18c# and differential amplifier 1
This is an adder consisting of 8d. Each resistor 18a, 18b
, 18cKkt, the output signal V (, the back electromotive voltage signal from the absolute value circuit 16, and the drive mode signal from the analog selector 17) of the speed deviation detector 5 are inputted, respectively.The differential amplifier 18d adds these signals. 19 is a level comparator that compares the level of the signal output from the adder 18 and determines the polarity of the output signal, and the level comparator 19 outputs a polarity control signal vD. 620 is an absolute value circuit that outputs the absolute value of the output signal from the adder 18, and outputs a voltage control signal vcv.

FIG. 3 is a circuit diagram of the DC switching regulator shown in FIG. 1. 23 is an AC input terminal for inputting AC voltage from an AC power source (not shown); 24 is a rectifier;
25 is a resistor, and 26 is a capacitor. capacitor 26
A constant voltage ■ is obtained across the terminals of . 27 is a switching element using a transistor, and the signal v8 from the signal comparison circuit 7 is input thereto. 28 is a choke coil, 29
is a capacitor.

Next, the operation of this embodiment will be explained with reference to the graph shown in FIG. In FIG. 4, the horizontal axis represents the motor rotation speed, and the vertical axis represents the motor applied voltage.

NM is the maximum rotation speed of motor 1, and NX is the rotation speed of motor 1. Also, VAC is the voltage required to accelerate motor 1, 7MM is the back electromotive force at the maximum rotation of motor 1,
is the power supply voltage of motor 1.

In the figure, a broken line F1 is a straight line indicating a back electromotive force, which increases or decreases in proportion to an increase or decrease in the rotational speed of the motor 1. The straight line F2 is a straight line indicating acceleration, and is obtained by adding the back electromotive chain acceleration voltages. The straight line F3 is a straight line indicating deceleration, and is obtained by subtracting the accelerating voltage from the back electromotive force.

Now, when the motor 1 is in a stopped state, the position command signal S (
is input, the motor applied voltage calculator 1 calculates the voltage applied to the motor according to the difference between the current position of the device driven by the motor 1 and the commanded position.
A signal vc is inputted to the input terminal 1, and at the same time, an acceleration command signal for instructing the drive mode is also inputted. The switch 17a is closed by the input of the acceleration command signal, the voltage signal vAc is input, and the voltage applied to the motor 1 is 1. Then,
The motor 1 is in a stationary state at point S. Then move to point S1. If the signal VC indicating the speed is a trapezoidal signal, the state of the motor 1 moves along the straight line F2, that is, the applied voltage and rotational speed increase, and the motor 1 is accelerated. This continues until the acceleration part of the trapezoidal signal ends (until point SX2 on straight line F2 is reached).

Next, when the signal V( shifts to the constant speed portion, a constant speed command signal is input to the motor applied voltage calculator 11, the switch 17a is opened, and the switch 17b is closed, so that the voltage signal -vAc is input. , the voltage applied to motor l also decreases by the value vAc, i.e.
The state of motor 1 is point Sx! Point Sx1 on straight line F1 from
Move to. In this state, the motor 1 has a constant rotation speed Nx. This continues until the constant speed portion of the trapezoidal signal ends. Next, when the signal Vc moves to the deceleration part of the trapezoidal signal, a deceleration command signal is inputted to the motor applied voltage calculator 11, the switch 17b is opened, the switch 17c is closed, and the voltage signal -2vAC is inputted. , the motor 1 further increases the voltage VAc from the state where the voltage vAc has decreased.
The state of motor 1 is therefore reduced to point Sx
1 to point Sx3 on the line 111 F s. In addition, in this deceleration part, the state of the motor 1 is at point sx
After moving to point S, move in the direction of the arrow on straight line F3.

The voltage becomes O, the voltage polarity inverter 13 is activated by the polarity control signal VD, and the polarity of the output voltage vv from the DC switching regulator 12 is inverted. Thereafter, at point SX, the motor 1 stops and returns to point S0.

Note that when the difference between the position command signal Sc and the current position signal Sp of the position detector 3 is small, the signal VC from the speed deviation detector 5 is not a trapezoidal signal but a triangular shape with only an acceleration part and a deceleration part. The signal becomes F2, and the state of motor 1 is straight line F2.
It immediately moves to straight line F.

In this way, in this embodiment, a motor applied voltage calculator is provided to control the voltage to be applied to the motor regardless of the motor drive mode, so that the peak current supplied to the motor is The current value does not exceed the value required for acceleration and deceleration, reducing noise and vibration of the device. Furthermore, an element with a low current rating can be used as the power switching element.

In the above embodiment, an analog signal processing circuit was used as an example of the motor applied voltage calculation unit, but this can also be configured with a digital signal processing circuit, and a microcomputer 'iff may also be used. can.

〔Effect of the invention〕

As described above, in the present invention, the voltage to be applied to the motor is controlled based on the supply voltage signal (speed command signal) to the motor, the signal instructing the drive mode of the motor, and the back electromotive voltage signal of the motor. As a result, the peak current supplied to the motor does not exceed the current required for acceleration and deceleration of the motor, and as a result, noise and vibration of the device can be reduced.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a block diagram of a DC motor drive control device according to an embodiment of the present invention, and FIGS. 2 and 3 are a block diagram of a motor applied voltage calculator and a DC switching regulator shown in FIG. 1, respectively. 4 is a graph explaining the operation of the device shown in FIG. 1, FIG. 5 is a block diagram of a conventional DC motor drive control device, and FIG. 6 is a diagram of the motor and voltage switching circuit shown in FIG. 5. FIG. 1...Motor, 2...Speed detector, 3
...Position detector, 4...Position deviation detector, 5...Speed deviation detector, 6...Triangular wave signal generator, 7... ... Signal comparison circuit, 11.
...Motor applied voltage calculator, 12...D
C switching regulator, 13... Voltage polarity inverter, 17... Analog selector, 18.
...Adder. '6'(p:”',:' Figure 1

Claims (1)

[Claims] A DC motor that outputs a supply voltage signal for the DC motor based on detection signals and a position command signal from a speed detector and a position detector connected to the DC motor, and drives the DC motor in accordance with the supply voltage signal. The motor drive control device calculates the drive voltage of the DC motor based on the supply voltage signal, a drive mode instruction signal that instructs the drive mode of the DC motor, and a back electromotive voltage signal of the DC motor, and calculates the drive voltage of the DC motor. 1. A drive control device for a DC motor, comprising: a calculation unit that performs polarity determination; and a control unit that performs chopper control of the DC motor according to the drive voltage and polarity obtained by the calculation unit.