CN1091325C

CN1091325C - Electric control for rapid vertical location of mainshaft of machine-tool

Info

Publication number: CN1091325C
Application number: CN99117805A
Authority: CN
Inventors: 管宝山
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-08-14
Filing date: 1999-08-14
Publication date: 2002-09-18
Anticipated expiration: 2019-08-14
Also published as: CN1250702A

Abstract

In order to reach the goal of quick electric positioning (positioning can also be called accurate parking) of a main shaft of a machine tool, a power supply of a main circuit is cut off in the control process, and induction potential is generated on a stator winding by the remanence of a rotor of a squirrel cage motor of the main shaft; then, a capacitor is connected with the stator winding so as to enhance the magnetic field of the rotor, so that the induction potential of the rotor is increased; a resistor is connected with the stator winding, so that most of the mechanical energy 0.5J omega <2> of the rotor is fast consumed on the resistor in an electric energy mode; because of the reduction in rotation speed, the voltage amplitude value and the frequency are reduced, and the magnetic increase action of the capacitor fast disappears with the reduction in the rotation speed; subsequently, a capacitor with high capacitance which is in reverse proportion to the second power of the rotation speed is connected with a stator loop, so that stator voltage is increased again; when a rotation angle reaches a definite position, the three-phase stator winding is short-circuited fast, so that the remanent mechanical energy is immediately consumed on the resistor of the stator winding, and thus, the rotation of the rotor immediately stops so as to fast accomplish positioning control.

Description

The control method that is used for the electric location of three-phase squirrel cage motor of machine tool chief axis

Technical field:

The present invention relates to the electrical Location control method of phase asynchronous interconnected cage motor.

Background technology:

Machine tool chief axis generally all is that three-phase squirrel cage is motor-driven, so-called location, finish processing exactly after, when needing withdrawing, not only require main shaft to stop the rotation, also require the cutter on the main shaft to stop at exactly in the corner of regulation, therefore the location also is called " accurate stopping " .At present, the positioning control of interconnected cage motor does not thoroughly solve both at home and abroad as yet.Domestic half-wave plug braking technology commonly used is difficult in 3 seconds and finishes, and also often burns motor.In addition, " the capacitance resistance dynamic brake of interconnected cage motor " technology only is applied to Brake stop, 10 kilowatts of just can of and the above motor of not be braked parking fully, and sliding of free state arranged.

Summary of the invention:

Purpose of the present invention, deep level development " the capacitance resistance dynamic brake technology of interconnected cage motor " adopts the vertical control of capacitance current, thoroughly solves the electrical Location control of interconnected cage motor.For this purpose, this control divided for two steps carried out: the first step is that rated speed is reduced to low speed as quick as thought, the mechanical energy overwhelming majority that makes storage with the form consumption of electric energy on outer meeting resistance: second step was the motor that is in lower-speed state, on stator, connect special big electric capacity once more, it is suitable with no-load current that capacitance current is returned to, short circuit stator during the location on the resistance of stator winding, is realized location fast to remaining mechanical energy consumption.

Embodiment:

For the reduction of speed that is exceedingly fast, the present invention has cancelled the self-excitation process of this technology in the past using.In the past in Brake stop, always cut off the motor power of specified operation earlier, and then on the stator loop, connect electric capacity, electric capacity can only obtain very little capacitance current under the induced potential of rotor remanent magnetism, this less capacitance current goes again to strengthen rotor remanent magnetism, so the stator-induced electromagnetic gesture is also strengthened, capacitance current also increases, the capacitance current that increases goes to strengthen the rotor field again, and the self-excitation that circulates has and so forth delayed control procedure.Rapidity of the present invention is the beginning in positioning control, elder generation connects electric capacity in the stator loop of the interconnected cage motor of specified operation, and then cut off the electricity supply, like this, capacitance current and rotor field almost do not change, and be very powerful all the time, just change on-position at once over to by motoring condition, (when cutting off the electricity supply, electric capacity parallel resistance, perhaps electric capacity and resistance parallel connection simultaneously) slack time has been cancelled.

Along with the braking reduction of speed, all proportional decline of the frequency of stator electromotive force and amplitude, so the attenuation ratio rotating speed of capacitance current square also want fast.When capacitance current also not complete attenuation just should begin the control in second step before the exhaustion, if rotating speed has been reduced to 0.1 of rated value, then to recover capacitance current and no-load current I again this moment ₀Quite, stator must insert 100 times of former electric capacity.The finished product AC capacitor of market supply is basic does not just have so huge capacitance (microfarad up to ten thousand).Breakthrough of the present invention is exactly that electrochemical capacitor with direct current is connected with diode and substitutes: with the DC electrolytic condenser and the common diode reverse parallel connection (being that heteropolarity is in parallel) of single big capacity (microfarad up to ten thousand), the anodal current potential that has guaranteed electrochemical capacitor is higher than negative level, otherwise then by short circuit.Again two identical like this doublet same polarities are connected series connection, be applied to exchange low frequency stator power by a narrow margin.

In addition, utilize ac capacitor to connect, also can be equivalent to the limited increase of capacitance with inductance.Time braking is too strong in order to prevent the short circuit stator, can series resistance suitably cushion, but as the resistance of series connection excessive, then do not reach the purpose of moment location.

The locator key of interconnected cage motor: one for reduction of speed releases energy, and two is to keep low speed during near allocation control points, to guarantee locating accuracy.So during reduction of speed, electric capacity is unsuitable excessive, resistance is unsuitable too small, otherwise will Brake stop, can't realize the location.

For improving positioning accuracy, the electronic switch that should adopt action to be exceedingly fast during the short circuit stator.The electronic switch that the present invention uses is that three-phase bridge rectifier and thyristor are formed by connecting, and the stator end line connects the input of three-phase bridge rectifier, thyristor forward output in parallel, need only the thyristor conducting then motor stator by short circuit.

When positioning accuracy request is not too high, the also available contactor of short circuit stator, but must add the lead S of one section control in the location before the set point, i.e. allocation control points.

The angle position signal converter of main shaft location has a variety of finished products to use.The present invention is also very desirable with the dry-reed relay repacking, its principle is to return to no-load current when suitable when special big capacitance current, the dry-reed relay coil just has enough electric currents, and the energized relay circuit closure must arrive to allocation control points between the set point of location in main axis rotation, so principle of signal conversion is the magnetic circuit closure.

It has all shown remarkable advantage than any positioning control technology in the past:the first, and quick property, 10 kilowatts of electronic Machine of the following capacity of is finished the location and was no more than for, 2 seconds; The second, the security of motor is because employing is that outer meeting resistance consumes the overwhelming majority Mechanical energy, the temperature rise of motor in the control process can be ignored, and be more more advantageous than reversing braking and energy consumption braking. The 3rd, Simply, element is few, and reliability increases, and price is cheap; The 4th, realize that easily falling on the fast AC capacitor market has finished product Supply, the big electric capacity of special interchange is also very convenient. The 5th, the control debugging is also very simple and convenient, and falling the rear increase of speed electric capacity can the time spent Between control principle, also can use the Control of Voltage principle. Realize that with relay the Control of Voltage principle is simpler. If the programmable of using Controller is controlled whole lathe or other equipment, and then time control is just more convenient. The 6th, the control process is energy-conservation. Because main Circuit does not connect power supply. In the future large-scale variable capacitance and variable resistor can be arranged, this technology also can realize the location relaxed Control makes elevator and crane lifting equipment also can use this technology. Just can say that the orientation problem of mouse-cage electric motivation is fully thorough this moment The end, solved.

Claims

The control method of the main shaft electrical Location that 1 one kinds of three-phase squirrel cage motor are dragged is characterized in that:

1) the three-phase squirrel cage motor of motoring condition is connected electric capacity and resistance earlier, and then is cut off the electricity supply on the stator, make its reduction of speed immediately;

2) through the braking reduction of speed, stator is connected special big electric capacity, and its each phase electric capacity all is that the electrochemical capacitor same polarity by two identical microfarads up to ten thousand is connected in series and forms, and each electrochemical capacitor is the heteropole parallel diode again;

3) current increases of special big electric capacity to no-load current quite after, when the allocation control points,, thereby realize the location in main axis rotation immediately with the whole short circuits of stator winding.
2 control methods according to claim 1 is characterized in that: described special big electric capacity is in series by AC capacitor and inductance.
3 control methods according to claim 1, described stator short circuit: the input of three stator termination three-phase bridge rectifiers, thyristor is in parallel with the output of three-phase bridge rectifier, the thyristor conducting then stator winding by short circuit.
4 control methods according to claim 1 is characterized in that: described stator short circuit is to adopt contactor to make main motor stator short circuit location, and will there be suitable lead at the control point of location.
5 according to claim 3 or 4 described control methods, before the stator short circuit, it is characterized in that: the current increases of special big electric capacity is to no-load current when suitable, and the coil of dry-reed relay just obtains the electric current that needs; When the magnetic conductive board on the main shaft just is transmitted to tongue tube to magnetic field to the location between the set point at allocation control points, the closed triggering and conducting thyristor of reed switch contact or connect contactor coil makes stator short circuit braking location.