CIRCUIT ARRANGEMENT FOR AN ASYNCHRONOUS MOTOR DRIVE OF CONTROLLED STEPPING

Abstract: A circuit arrangement for an asynchronous motor drive of controlled stepping, i.e. for control of the number of revolutions of asynchronous squirrel-cage motors, in which the output of the supply unit is connected to a potentiometer, the other terminal of which is connected to the common terminal of the abjusting resistors. The non-common terminal of one of the resistors is connected to one of the inputs of a switch-inductance, whereas the collector of a transistor is connected to the other input. The emitter of the transistor is connected to the negative pole of the supply unit, while one switching point of the switch-inductance is connected to one of the inputs of the NAND-gate having several inputs. There is a magnetic coupled control coil arranged in the system being common for the switch-inductance and the uncoupling coil, while there are as many circuits of identical layout consisting of the switch-inductances, the single abjusting resistors and the transistors, as the number of pulses required for the control. The NAND-gate is connected through a switch-amplifier to the control input of the inverter.

Description: Circuit arrangement for an asynchronous motor drive of controlled stepping Technical field The invention relates to a circuit arrangement for $ asynchronous motor drive of controlled stepping, i.e. for the control of the number of revolutions of asyn- chrous squirrel-cage mo ors, raking and the realization of highly accurate driving units. By the application of the circuit arrangement according to the invention control of the motor may be performed with cha acteristica, hich are well suitable fee the optimal control-technical and energetic adjustment of 0 the drive unit. Background art Systems tending to utilize the drive-technical applicat¬ ion of the squirrel-cage ςiotors have been known. Taking into consideration,that the asynchronous squirrel - 5 cage motor is showing a simple structural design and no peculiar maintenance is re uired,these types of motor have been willingly used for complying with drive- technical requirements.However, the drawback of said drives lies in,that when they are produced in a good o quality,cost expenditures are utmost high. In order to eliminate said drawback in the recent years intense research work has been performed to improve electrical drive units,partly to be able to comply with technical requirements, partly to produce a pro- 5 duct with marketable prices. As a result of the researching . a developing activity having been performed, solution became known,at which separate fluzus-control and separate moment control -are used,τyhich are exerting an influence on the input of o the D-oC " . intermediate circuit feeding the asynchronous -2- otor. According to" this solution the intensity $nd frequency of the stator-current are controlled.Esse ly fluxus control is influencing the intensity of th current, hile the control of the moment is affecting frequenc .Accordingly, by controlling the fluxus,not only the current intensity,but also the moment will b influenced.As a consequence, in order to be able to approximate precise control, at the known control - technical systems - at which current intensity, ol a and frequency are of predetermined value - the said predetermined characteristics of the asynchronous mot are used to be influenced by feed-back, by means of t rather complicated,internal dynamical structural elem of the motorvHowever, confirmed by the experiences ga in practice, neither advantageous control- technical features,nor controllability could be obtained"," At an other known solution having been described in the Hungarian Patent No.167 688 the current and fluxu of the stator are reduced to components in a rect- angular co-ordinate and tb.e value of said quantities are separately prescribed ' . ' In course of the control pr cess the difference of the two quantities delivers th signals performing adjustment /intervention/. The dra back of this solution lies in the complicated struct in the high production costs,simultaneously the de¬ sired accuracy cannot obtained at all.' The aim of the invention is to eliminate the above- mentioned drawbacks b ,providing an expedient circu arrangement. By the application of the solution according to the invention control of the motor may b -3- performeςl by the aid of simple means and with high accuracy. Disclosure of Invention The essence of the invention is represented by the pulse- width modulator on sine basis,provided with current control according to figure 1, which i? delivering the signals needed for pulse-width control; " The invention relates to a circuit arrangement for an asynchronous motor drive of controlled stepping and the control of the number of revolutions of asynchron¬ ous squirrel-cage mo ors, espectively, braking and the realization of highly accurate driving units. The solut¬ ion can be characterized in, hat to the output of the supply unit one of the connecting points of the po- tentiometer is connecte ,while to the same potentiometer the common terminal of adjusting resistors has been connected.The other terminal of the first resistor is connected to one of the inputs of the switch - induc¬ tance, while to the otlier output of the s$me the collector of the transistor is connected. The emitter of the tran±stor is connected to the negative pole of the supply unit, while one of the switch points of the outcoupling coil of the switch-inductance is connected to one of the inputs of the NAND - gate having several inputs,while the other terminal of the outcoupling coil is connected to the earthpoint and in the magnetic coupling being common for the switch- inductance and the outcoupling coil, here is a pre- magnetizing inductive coil arranged.The system contains circuit arrangements consisting of the switch-inductance, OMPi -4- the resistor,as v/ell as the transistor of analogue out and connected in series,built into the system i a proper number,at last the N-AND-gate is connected through the switch-amplifier to the control input o the inverter. Brief Description of Drawings The invention is described in detail by means of ex only,with reference' to preferred embodiments illustr in the accompanying drawing,wherein: Figure 1 is showing the pulse- idth modulator, Figure 2 the entire block-schematic of the drive Figure 3 frbe pulse-timediagra s, and. Figure 4 illustrates a further preferable embodi of the circuit arrangement according to the invention.' Best Mode of Carrying Out the Invention Referring to figure 1, one of the connecting points th .potentiometer P is connected to the output of t DvC.supply unit T, whereas the other connecting poi of the potentiometer P is connected to one of the co terminals of the adjusting resistors H ,E ι E 3i ^ » ^ * and Eg. The other connecting point of the resistor E j _ is connected to one of the outputs of the switch- inductance L , while the collector of the transistor is connected to the other input of said switch in¬ ductance L- j _. The emitter of the transistor T-^ is connected to the negative terminal of the supply uni Simultaneously one of the switching points of the outcoupling coil of the switch-inductance In has be connected to one of the inputs of the NAND-gate N O ■ ":_?! provided with more inputs-.' The o—ther output,of the outcoupling coil is connected to the earthpoint. The control coil E-^ belongs also to the switch-inductance 1^. The tasi of said coil is to bring the switch-inductance 1^ into a magnetized state being proportional to the current of the motor. The system contains as many circuits being analogue in respect to layout and consisting of the resistor R- j _ , the switch-inductance -, and the transistdr - connect- ed in series,as many pulses are needed for inducing the hal -wave of the phase voltage of the motor." These cir¬ cuits - being absolutely identical with each other - are connected to the first circuit arrangement in such a wanne , hat the common points of the single resistors Ε.-^ * . , * are connected to one of the terminals of the potentiometer, while the common emitter points of the transistors of the previously mentioned circuits connected in series are conneςted to the negative terminal of the supply unit ^ : One of the outputs of the outcoupling coils of the single switch-inductances -, IL is connected to the negative terminal- of the supply unit T, while the other output is connected to an,input each of the NAND -gate N with several inputs". Simultaneously the output of the NAND-gate. is connect¬ ed to the input of the switch- amplifier E, the output of which having been connected to the control input of the pulse-width modulator I. The pre agne izing in¬ ductive coils belonging to the single switch - inductance are connected in series. -6- The main characteristics of the resistors applied therein lies in,that their values are chang in dependence of the . amplitude of the sine function. Supposing, that we . are selecting the proportion of t number of the windings of the coils of the switch - inductances -,....L^ in accordance with the amplitud of the sine function, the resistors may be of the sa valueo The premagnetizing inductive coils E-, E(- Eg are induced by an signal being proportional to current-signal of the motor current. As already mentioned before, the switch-amplifier, wh is serving for the drive of the bridge-branch of the pulse-width modulator,is connected to the output of NAND-gate N with six inputs. In accordance with a preferred embodiment three units are to be formed from the pulse-modulator consistsi of the switch-inductance l,the resistor R-, and the transistor T-. ,the schematical arrangement is best see in figure 2, wherein is shown that three AND- gates each with several inputs are connected to the pre¬ viously described pulse-width modulator I. To one of the inputs of the AND-gates a three-phase generato and altogether three time-genaraiors ' -^J ' 2» J are connected. The signals of the three-phase generator as well as the signals of the time- generator J-,,be¬ longing to the first phase,of the three-phase generat are to be seen in figure 3« A further preferred embodiment of the circuit arrange -7- according to the invention is shown in igure 4-.' The single phases of the three-phase mains are connected to the input of the three-phase mains rectifier E . The output of the rectifier E-, ,is connected to the input of a transistored chopper 0', hile the output of the same chopper is connected via the choke-coil F to the heavy-current input of the inverter Iv and after having been branched before said input,it is fed back via,the diode D-, to the positive output of the rectifier Ei. The output of the dual driving circuit Y is connected to the control input of the chopper C and to the input of the driving circuit Y the current transformers /shunt-resistors/— having been connected to the out¬ put of the inverter Iv - are connected via the amplifier ErV The driving circuit Y is built up,as follows: The output of the constant frequency timebasis- - generator 5 is connected to the input of the flip-flop circuit Ik,whereas one of the outputs of the same is , connected to the input of the pulse-width modulator I. The output of said modulator is connected through the OR-gate to the previously mentioned switch - amplifier K, while the other output is connected via the level- translator Sz to the input of a further pulse-width modulator I, being absolutely identical with the previous one, whereas the output thereof is connected to the other input ς>f the switch - amplifier K via the same OR-gate. The circuit arrangement according to the invention functions,as follows: -8- In the usual way D.C. voltage is generated from the three-phase mains and led onto the chopper C.After ha left the chopper C, the voltage,is supplied into the system through the choke-coil F. In the present circu arrangement the voltage needed for the inverter Iv and defined by the parameters of the motor is generat by controlling the chopper. The operation of the chop is controlled by the signal formed from the motor current ' . ' The timebasis-genera or G generates the constant puls frequency f ,from which a signal being identical with the flip-flop circuit Ik with two outputs and an ant phase signal are formed /see figure 4/. The two signa appear at the outputs Q and of the flip-flop circu By means of the level -translator the signal of the output is transformed into a.signal with a level si to that of the original signal. The pulse-^width modul ator I is operatdd with the previously mentioned signals; the modulator is driving the switch -ampli K via the OR-gate,wheyeby the control of the chopper C is also taking place. " When we apply voltage-pulses onto the basis of the fi transistor T-, of the pulse-width modulator, the circ arrangement consisting of the resistor R-, ,the induct I s switched to the voltage - attenuated by the potentiometer P - whereby the intensity of the curren will increase in the circuit arrangement with a slope depending on the choice of the elements as long as the inductance In becomes saturated. After having rea the saturated state, the voltage attenuated by the po -9- tentiometer arrives in its entjα?ety to the resistor - j , accordingly , on the outcoupling coil a voltage- pulse depending ς>n the satur^ion time of the iron • will be generated. The inductive premagnetizing coils E-, Eg are in¬ duced by a current signal being proportional to the current-signal of the motor current". The driving circuit is connected to the output of the NAND-gate with six inputs and serves for driying the bridge- branch of the pulse-width modulator.

Claims: Claims : IV Circuit arrangement for an asynchronous motor drive of controlled stepping and the control. the number of revolutions of asynchronous squirrel- cage motors,respectively, braking and the realizati of highly accurate driving units, characterized in that to the output of the supply unit /T/ one of th connecting points' " of the potentiometer /P/ is conhe ed, while to the same potentiometer /P/ e common terminal of the adjusting resistors / j _.... g/ ha been connected; the other terminal of the first re¬ sistor / / is connected to one of the inputs of th switch -inductance / ,/, while to the other input of the same the collector of the transistor /T is connected; the emitter of the transistor /T, / is connected to the negative pole of the supply uni /T/,while one of the switch points of the outcoupli coil of the switch-inductance /L-,/ is connected to one of the inputs of the NAND-gate /N/ with several inputs, while the other terminal of the outcoupling coil is connected to the earthpoint and in the magn ic coupling being common for the switch- inductan /L,/ and the outcoupling coil there is a premagnet inductive coil /E^/ as a control- coil arranged; the system contains circuit arrangements consistin of the switch-induc ance,the resistor.and the trans istor of analogue layouts/ p ,R p , ^.♦... Lg,Rg,Tg / and connected in series,built into the system in a proper number,at last the NAND-gate /N/ is connec , ed via the switch-ampli ier to the control-input V of the inverter /Iv/. -11- 2. Circuit arrangement as claimed in claim 1, characterized in that one of the outputs of the mains rectifier /Ξ-,/ is connected to the input of the chopper /C/ and the output thereof is connected to the heavy- current input of the inverter/Iv/ via the choke-coil /F/ and after having been branched before said input,it is connected via the diode /D-,/ to the input of the chopper /C/; the input of the amplifier /ΞR/ is connect¬ ed to the shunt-r sis ance arranged on one of the out- puts of the inverter /Iv/ and the outp ' ut of said amplifier is connected to the input of the driving circuit /V/, whereas the output of the driving circuit /Y/ is connected to the input of the chopper/C/. 3. Circuit arrangement as claimed in claim 1 or 2, characterized in that the driving circuit /Y/ is formed by the flip-flop circuit/Ik/ connected via its input to the output of the generator /G/ delivering the basic signal and by the pulse-width modulator/I/ having been connected to the output of the flip-flop o circuit and the output of said modulator is connected to the input of the εwitch-amplifier /K/ via the OR- gate, while the output / / is connected through the level-translating circuit /Sz/ to the input of a further pulse-width modulator /I/ and the output of the same is connected to the other input of the OR- gate, OMPI v. ; :-Ό

Inventors: GYOERGYI V
Applicants: GYOERGYI V, NOVEX FOREIGN TRADE CO LTD, NOVEX FOREIGN TRADE DEV COMMERC INVENT
Application year: 1980
Main classification: H02P7
IPC codes: H02P8, H02P27, H03K7, H03K17