USER MANUAL DC TORQUE MOTOR
Contents
1. M Time mechanical constant m ms This is the value computed by using the equation m Static friction torque Tr cN m This is themotor dry friction torque mainly of magnetic origin Viscous damping coefficient Fo N m rad s K K This is the value computed by using the equation Fo M Heat constant Tr C W This is the winding temperature rise versus the motor dissipated power This value is measured on a thermally insulated motor in calm atmosphere The winding maximum temperature 90 C This value depends on the insulation class of the magnet wire and the electro insulating materials Rotor inertia Jm g cm This is the measured inertia for the motor rotating armature Maximum theoretical acceleration rad s _ i l T This is the value computed by using the equation 4 2 Torque motors with commutator Peak torque Tp N m This electromagnetic torque is obtained under short circuit conditions at a current Ip This is the average of the torque values measured in both directions of rotation and in both directions of power supply Power at peak torque Pp W Absorbed power corresponding to the peak torque es es SA WWW ICpe ro ___sicpeS A on Splaiul Unirii 313 030138 Bucuresti RO 423140 J40 21438 92 be S ES tel O21 589 33 00 fax 021 589 34 34 RO40 CRDZ 024A 0863 9047 6001 D nail Office icpe ro MKB NexteBank Energy service company Electrical engineering company Re2. C Peak current Ip A This is the motor current consumption required to obtain the peak torque with the winding at 25 C Resistance Ry Q This is the resistance viewed from the motor output leads measured at 250C Torque constant Kr The electromagnetic torque at 0 25 p or at another value mentioned in the specification divided by the current value Back EMF constant Ke V rad s es es SA WWW ICpe ro ___sicpeS A on Splaiul Unirii 313 030138 Bucuresti RO 423140 J40 21438 92 be S ES tel O21 589 33 00 fax 021 589 34 34 RO40 CRDZ 024A 0863 9047 6001 D nail Office icpe ro MKB NexteBank Energy service company Electrical engineering company Research institute for electrotechnics This is the induced voltage speed ratio when the motor is driven at 80 of the maximum no load speed Inductance Ly mH This is the value computed by using the equation Lu e Rm WWW ICD rO icpe S A FX a AA Splaiul Unirii 313 030138 Bucure ti RO 423140 J40 21438 92 8 ED anes tel 021 589 33 00 tax 021 589 34 34 RO40 CRDZ 024A 0863 9047 6001 NE email Office icpe ro MKB NexteBank
3. Energy service company Electrical engineering company Research institute for electrotechnics hi ICPE lt USER MANUAL DC TORQUE MOTOR The present manual shows an opportunity for the servomechanisms builders of choosing the DC torque motors with high performances low price and immediate delivery ICPE SA Department 4 designs and manufactures DC permanent magnets torque motors whose windings are optimized so that a maximum torque within overall size housing outside diamater 1 5 inch 5 1 inch can be obtained 1 Features of the DC torque motor These motors are designed in such a way as to function in direct drive construction The fixed element the stator is equipped with permanent magnets and the rotor with a DC specific winding which is connected to an extra flat commutator brushes system the rotor can perform a continuous rotation and the main advantages of this construction are Lack of the gear or the mechanical multiplier Direct mounting on the leading shaft High useful mechanical torque at low speeds Big ratio torque inertia moment Linear characteristic of the useful mechanical torque function the speed Big ratio useful mechanical torque power Time electrical constant small Noise and vibration free operation Simple but solid construction This electro mechanical construction allows the servosystem designer to obtain the following advantages e Rigid coupling Quick response to the controls
4. Static positioning accurate Dynamic positioning accurate Consumed electrical power low The servosystem operates without any noise and vibrations The servosystem can be designed in a compact construction e High reliability The DC direct drive construction torque motor is equivalent to a DC servomotor with a gear or mechanical multiplier but because of the latter s absence gear mechanical multiplier the servosystem is ideal for very fast accelerations or decelerations The lack of the gear in the system eliminates the errors caused by the frictions the clearances among the gear sides and other mechanical accuracy errors determines a very high positioning sensitivity arc seconds This positioning sensitivity firistly depends on the transducer detection accuracy feed back synchro resolver encoder which is directly coupled onto the load shaft WWW ICpe rO ___siicpe S A Splaiul Unirii 313 030138 Bucuresti RO 423140 J40 21438 92 te 021 589 33 00 tax 021 589 34 34 RO40 CRDZ 024A 0863 9047 6001 Office icpe ro MKB NexteBank Energy service company Electrical engineering company Research institute for electrotechnics hi ICPE lt The DC torque motor offers a perfect linearity M f in relation to the AC two phase servomotor Fig 1 due to the fact that the frictions are constant compared to those of the other one where they are variable function the speed and the control voltage The performance of the DC torq
5. consist of two armatures e stator made up of stamped and glued laminations equipped with a ring type winding beacause of this construction the cogging torque is null e rotor provided with permanents magnets Figure 3 1 1 shows the construction of this type of torque motor This construction limits the domain of the rotor rotation movement which is function the number of the rotor pole pairs consequently these motors are called limited angle torque motors Figure 3 1 2 shows the mechanical feature corresponding to a four pole construction 3 2 Torque motors with commutator Unlike the first type these 0 2 7 motors have a reversed construction the stator is equipped with permanent magnets and the rotor is similar to that of a DC classic motor Fig 3 2 WWW ICpe ro icpe S A aN Splaiul Unirii 313 030138 Bucure ti RO 423140 J40 21438 92 amp S ES tel O21 589 33 00 fax 021 589 34 34 RO40 CRDZ 024A 0863 9047 6001 D il Office icpe ro MKB NexteBank Energy service company Electrical engineering company WWW ICDe rO icpe S A m Splaiul Unirii 313 030138 Bucuresti RO 423140 J40 21438 92 aS gD ania te 021589 3300 tax 021589 34 34 ROAO CRDZ 024A 0863 9047 6001 KNet email Office icpe ro MKB NexteBank papi OHSAS 18001 Fig 3 1 1 Tp oz in T oz in T oz in unghi CL Fisier Extins Standard PRINT Fig 3 1 2 The rotor lamination stack is made up slot stamped and gl
6. eg This is the angular operating range Power Pp W This is the power absorbed at the peak torque computed value Rwlp Tp VP The supply voltage Up V This is the voltage required to obtain current Ip with the winding at 20 C Peak current Ip A This is the motor current consumption required to obtain the peak torque with the winding at 25 C Maximum current Imax A Motor constant Km this is the value computed by WWW ICDeC fO icpe S A Splaiul Unirii 313 030138 Bucuresti RO 423140 J40 21438 92 tel 021 589 33 00 tax021 589 34 34 RO40 CRDZ 024A 0863 9047 6001 email Office icpe ro MKB NexteBank Energy service company Electrical engineering company Research institute for electrotechnics hi ICPE lt This is the value given for the metal permanent magnet type motors below wich there is no risk of demagnetization Resistance Ry Q This is the resistance viewed from the motor output leads measured at 29 C Torque constant Kr The electromagnetic torque at 0 25 p or at another value mentioned in the specification divided by the current value Back EMF constant Ke V rad s This is the induced voltage speed ratio when the motor is driven at 1000 rev min or at another value mentioned in the specification Time electrical constant e ms With the rotor locked this is the time taken by the current to reach 63 of the value r where U is the voltage required to obtain 0 251p
7. ii 313 030138 Bucure ti RO 423140 J40 21438 92 tel O21 589 33 00 fax 021 589 34 34 RO40 CRDZ 024A 0863 9047 6001 email Office icpe ro MKB NexteBank Energy service company Electrical engineering company Research institute for electrotechnics hi ICPE lt E back electromotive force back EMF V Rm R DC resistance of the rotor winding Q T torque Nm w rotation angular speed rad sec Kr torque constant Ke Ks back EMF constant If in equation 2 1 ther are introduced equations 2 2 and 2 3 there results T R U Kr0 t 2 4 T where the first term of equation 2 4 represents the part of the supply voltage necessary to produce the motor back EMF at the requested speed and the 274 term represents the part of the supply voltage necessary to produce requested torque The torque motors can satisfactorily operate practicaly at any level of supply voltage without the essential change of the mechanical characteristics the power torques and electro mechanical constants remain unchanged Fig 2 shows the equivalent diagram of the torque motor where the F ratio represents the time electric constant The L component stands for the armature inductivity and can be minimized through an adequate design of the magnetic circuit Fig 2 Equivalent circuit of DC brushed motor WWW ICpe ro icpe S A Splaiul Unirii 313 030138 Bucure ti RO 423140 J40 21438 92 tel 021 589 33 00 ta
8. search institute for electrotechnics hi ICPE lt p V P Electrical time constant e ms With the rotor locked this is the time taken by the current to reach Motor constant Km ao this is the value computed by 63 of the value where U is the voltage required to obtain 0 251p M Time mechanical constant m ms This is the value computed using the equation m 5 Static friction torque Tr N m Average of the friction torque values measured on a motor which is not energized and is driven at a very low speed a few rev min Viscous damping coefficient Fo N m rad s This is the value computed by using the equation Fo Saree M Ripple torque Tr This is the value computed by using the equation Tr 1002m me at max min a current of 0 25 p or at another value mentioned in the specification Heat constant Tr C W This is the winding temperature rise versus the motor dissipated power This value is measured on a thermally insulated motor in calm atmosphere The winding maximum temperature 90 C This value depends on the insulation class of the magnet wire and the electro insulating materials Rotor inertia Jm kg m This is the measured inertia for the motor rotating armature Maximum no load speed wz rad s This is the value computed by using the equation yz Up Kg The supply voltage Up V This is the voltage required to obtain the current Jp with the winding at 257
9. ue motor can be estimated accurately enough by using the linearity conventional hypotheses of the servosystem Thus the servosystem time mechanical constant has the same magnitude order milliseconds as that of an AC servomotor In any case the effective time constants of the AC low power servomotors for low positioning speeds are twice up to five times smaller in comparison with the catalogue values In this case the higher values are determining factors for the establishing of the system stability On the other hand the time electric constant of a DC torque motor is very small fractions of milliseconds In a system with performances of the 274 order the time electric constant is that which determines the system stability Due to the linear characteristics of the DC torque motor they are recommended for being used in the servosystems requesting a position tracking accuracy within the speed range from several thousandes up to one The dynamic regime is about ten times faster than that of the AC servomotor Rated Voltage Operation AC Servo Motor Low Voltage Operation Fig 1 Torque Speed characteristic of the DC torque motor compared to that of the AC servomotor 2 Operating equations The DC torque motor has a construction similar to that of a DC classic motor consequently there can be used its operating equations U E IRm 2 1 E Keo 2 2 T Krl 2 3 where U supply voltage V WWW ICpe ro icpe S A Splaiul Unir
10. ued laminations within which a DC winding is distributed and connected to the commutator As far as the commutator is concerned it can have a classic construction if the length outside diameter ratio is overunitary and if this ratio is underunitary ICPE SA Department 4 has developed a technology enabling the attachment of the commutator directly to the front side of the winding The brush block assembly with the commutator brushes is carried Research institute for electrotechnics AS AS Energy service company Electrical engineering company N Research institute for electrotechnics CPE out in a detachable construction and it is operational by being attached to the stator housing by the user it is delivered separately The commutator brushes are of the silver graphite type and the springs which are made from bronze beryllium also represents the paths of current With the two types of torque motors ICPE SA Department 4 uses for the achievement of the armatures with permanent magnets the SPM type technology surface mounted permanent magnet on demand there can also be used IPM technology inside mounted permanent magnet Fig 3 2 4 Definition of the electromechanical parameters 4 1 Torque motors without commutator Peak torque Tp N m This electromagnetic torque is obtained under short circuit conditions at a current Ip in the reference position of the rotor a 0 Fig 3 1 2 Angular range a d
11. x021 589 34 34 RO40 CRDZ 024A 0863 9047 6001 email Office icpe ro MKB NexteBank Energy service company Electrical engineering company Research institute for electrotechnics hi ICPE lt Energy relations If equation 2 1 is multiplied by the absorbed current I then there results the power balance UI EI RP 2 5 The first term of equation 2 5 represents the absorbed power the second term EJ stands for the mechanical power W developed in the motor shaft which includes the friction and iron losses the third term represents the copper losses The mechanical power developed in the motor shaft results from equation 2 6 EJ T Ss 2 6 0 007062 Under short circuit conditions equation 2 6 becomes Tp M 0 007062 where wo is the no load theoretical speed without the losses effect Heat considerations the absorbed winding electrical power is changed into mechanical power deweloped by the rotor on one hand as well as into calorific power dissipated in the winding on the other hand For this reason the user must have in view that the motor overtemperature should not exceed its insulation class and at the same time the operating critical temperature of the magnets which generally are made of rare earths 3 Construction From a constructive viewpoint one distinguishes two types of DC torque motors torque motors with and without commutator 3 1 Torque motors without commutator These
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