CN103532468A

CN103532468A - Motor control circuit

Info

Publication number: CN103532468A
Application number: CN201310503459.9A
Authority: CN
Inventors: 不公告发明人
Original assignee: Suzhou Baker Microelectronics Co Ltd
Current assignee: Suzhou Baker Microelectronics Co Ltd
Priority date: 2013-10-24
Filing date: 2013-10-24
Publication date: 2014-01-22

Abstract

The invention discloses a motor control circuit. A current of the motor control circuit limits the circuit. The circuit is applied to a conversion motor which is in series connection; a current passing through a resistor is monitored, so that a mode of the motor is selected; however, the noise current of the motor is not monitored; and a current on a simulation resistor comes from a speedometer on the motor and is in direct proportion to the speed of the motor.

Description

A kind of circuit for controlling motor

Technical field

Briefly, the present invention has avoided measurement noise, unsettled current of electric, by a speed proportional, represents the voltage that motor speed table produces.This voltage is directly used or is combined with resistance, optionally records the counting (getting back to EMF) of electromotive force, and the resistance of motor internal is received control.Select suitable logical circuit, its direct voltage or voltage proportional to resistance (increasing a fixing voltage) are controlled motor, and this depends on the velocity interval of motor.This control system, is particularly suitable for exchanging or the serial conversion motor of direct current.Other advantage will show in describing in detail below in addition.

Background technology

The Electric Machine Control of prior art is measured the electric current of the speed of motor and the motor of flowing through conventionally, and regulate it, make its Adaptive control apparatus, to keep constant airspeed or to make energy input enough low, or avoid a large amount of input currents, or realize other object.The problem of this mode is, the operating characteristic of motor is that electric current is very unstable, and has noise, interruption.Therefore, electric current must have the mean value of minimum interval, to other similar devices such as filters, at any time in, average current is had to a relatively accurate measurement.Experience shows, the unexpected variation of load or other operation in motor can cause the electric current that electric current will be required faster than actual measurement in minimum interval.

Summary of the invention

These fluctuations are will be to electrode unfavorable or damage fuse.My invention solves these problems.

Contrast patent documentation: CN102931899A motor rotation-speed control circuit 201210409438.6.

Accompanying drawing explanation:

Shown in Fig. 1 is the schematic diagram of the Electric Machine Control of typical prior art.

Shown in Fig. 2 is the schematic diagram of my the new control system of inventing.

Embodiment:

Described in Fig. 1 is the method for typical prior art Electric Machine Control.Power supply is from 10, its be pressurizer 12 by regulating, pressurizer 12 may comprise, for example, a triac or similar device.An electric current that motor 14 receives from series resistance 16.Voltage on resistance 16, by filter 17, is eliminated the irregular electric current of the motor 14 of flowing through.Filter 17 provides average voltage for maximum current detector 15.When electric current reaches default KB limit, detector 15 provides signal for controller 18, and the controller 18 that prevents pressurizer 12 of take provides too much electric current as motor 14.A differential amplifier 23 provides the indication of a speed difference, and this speed difference comes from the comparative voltage of velocity selector 19, and its voltage is to be provided by tachometer 20 and FV convertor 22.Controller 18 reduces the differential voltage of amplifier 23 as required to zero, the maximum constraints of setting up to adapt to detector 15.Controller 18 can be so simple as an Analogical Electronics, or more complicated, or utilize microprocessor, carries out related rational operation sequence below.

The problem of the system maximum shown in Fig. 1 is the variation from the large electric current of terminal 10, can be by filtering before filter 17, and the variation of average current that can display controller 18.The useful life that this transient current spike may cause responding to the unnecessary fusing of fuse and shorten motor.Control circuit shown in Fig. 2 has overcome these problems.

My invention is not measured unsettled electric current by motor itself, the substitute is the metastable motor model that uses digital circuit, and it is subject to the control of the analog circuit shown in software program or Fig. 2.In Fig. 2, resistance

with

as the simulation model of internal resistance, it is controlled that real electrical machinery returns to the characteristic of EMF.As previously described, motor 14 is from power supply 10 and pressurizer 12 received currents, the control of the controlled device 18 of pressurizer 12.The frequency of the output signal of tachometer 20, depends on the rotating speed of motor, and it converts a voltage to by FV convertor 22.When the work of motor close to arrange speed time, the voltage on transducer 22 is compared with the desired voltage of velocity selector 19.An output voltage is provided on differential amplifier 23 online 27

, be taken as the control voltage of controller 18.It should be noted that this control voltage

by logical circuit 25, selected, it is than another voltage

little.Logic 25 comparative voltages

with , select little voltage to pass through switch.In this case,

be less than

, switch 24 cuts out.If a load causes motor 14 slack-off, thereby cause the unexpected increase of electric current, slowing down of tachometer 20 causes the voltage of transducer 22 to reduce.The corresponding minimizing of voltage on node 28, becomes voltage by

amplifier

30 and 32

.It enough slows down and makes voltage

be less than voltage

, logic 25 is opened switch 24, and closing switch 26 makes the voltage on line 27 be

.Therefore, the railway voltage of controller 18 is

, according to

lower than zooming voltage

, the electric current of restricted passage pressurizer 12.Resistance with

selection, for line 27 provides voltage

,

voltage

with summation.Voltage

with the speed of motor proportional (proportional with EMF),

represent the internal resistance of motor, by pressurizer 12, provide a constant electric current for motor 14.Only have when motor is free to accelerate to approach it and normally speed is set, thereby reduce voltage

to the level of a safety, lower than voltage , controller 18 will allow response again

, under normal regulating mode, work.

If motor stops, voltage with

by vanishing, will there is no the electric current motor of flowing through.For fear of this, resistance

produce a minimum electric current that starts, it is connected between reference voltage 34 and earth point, to go out to set up a fixed voltage at node 36

.A summing amplifier 32 is by voltage

with

be added, make

at least equal fixed voltage

.

We can find out thus, resistance

the model that can regard the internal resistance of motor 14 as is set up the minimum voltage of controlling on the line 27 of controller 18

.Resistance

the model that can regard the EMF of motor 14 as, when the speed of motor 14 exists add

be less than

situation under when working, keep current of electric constant.

Claims

1. a circuit for controlling motor, is characterized in that: adopt serial conversion motor, it comprises: velocity measuring device is connected on motor, and its work produces first voltage, to show the speed of motor; The work of motor control assembly regulates the electric weight that is supplied to motor, to respond the input control signal on input control line; Speed choice device; Comparison means is connected on speed choice device, that is, and and velocity measuring device, its work produces the first input control signal, its size is appropriate, so that the work that motor control assembly is motor provides suitable electric weight, the operating rate of motor is determined by speed choice device; In motor simulation device, circuit is selected the counter of simulated interior resistance and motor powered gesture, and the connection of this circuit is to receive the first voltage from velocity measuring device, and this first voltage is that motor is distinctive, proportional with the second input control signal of its generation; The first logic device is connected on analogue means and comparison means, when the first and second input control signals on the input control line of motor control assembly are low-voltage, make motor control assembly be subject to control from the low-voltage input control signal of analogue means or comparison means.

2. a kind of circuit for controlling motor according to claim 1, it is characterized in that: analogue means comprises resistance circuit, it has first resistance to be connected between reference voltage and velocity measuring device, counter with simulated machine electromotive force, the voltage producing and the speed of motor are proportional, also have the connection of second resistance to set up a fixing minimum voltage, internal resistance with simulated machine, the summation of motor simulation device export ratio, is the second input control signal from the fixedly minimum voltage of the first and second resistance.

3. a kind of circuit for controlling motor according to claim 2, is characterized in that: velocity measuring device comprises that a tachometer is connected on motor, converts the output of tachometer to typical velocity voltage signal, so that the first voltage to be provided.