Microstepping Driver - AV-iQ
Contents
1. 11 Factors Affecting Microstep Accuracy 12 Motor Aceuraey da aa dA ges Aid us 12 Motor Linearity sa asie andet duene E 12 Motor Load sa sis g RUM 13 Anti Resonance Circuit se see see ee ek ER ek ee 13 Disaddvantages uuu Seg is ja a sas Pes sye posede Ge Eg edo ege 15 Performance Considerations 16 Torque and Power vs Speed 16 Factors Affecting Power and Torque 17 Power Supply Voltage u 17 Series vs Parallel Operation 18 JTOUQUE sie RE a 19 Power Supply Current e ee e ek ee 20 Heating Considerations eee 21 Motor Speed Torque and Speed Power Curves 22 Specifications re oret sorai A eta ave A AR e ea 30 GENERAL DESCRIPTION CvberResearch s s SMD 703 and SMD 707 are step motor drives whose major features are microstepping and anti resonance circuitrv These compensate for low speed vibration and mid band instabilitv respectivelv The SMD 707 is designed to run unipolar hvbrid PM step motors with current ratings from 75 to 7 amps per phase the SMD 703 is designed to work with motors rated at 1 5 to 14 amps per phase The control interface for these drives is opto isolated for maximum noise immunity The inputs are directly compatible with TTL drivers and do not require additio2. Motion Control SMD 703 24 60V 0 75 3 6A Microstepping Driver SMD 707 24 60V 1 5 7A Microstepping Driver USER S MANUAL REVISION 1 0 2001 No part of this manual may be reproduced without permission CyberResearch Inc www cyberresearch com 25 Business Park Drive Branford CT 06405 USA 203 483 8815 9am to 5pm EST FAX 203 483 9024 Copyright 2001 CvberResearch Inc All Rights Reserved Revision 1 2001 The information in this document is subject to change without prior notice in order to improve reliability design and function and does not represent a commitment on the part of CyberResearch Inc In no event will CyberResearch Inc be liable for direct indirect special incidental or consequential damages arising out of the use of or inability to use the product or documentation even if advised of the possibility of such damages This document contains proprietary information protected by copyright All rights are reserved No part of this manual may be reproduced by any mechanical electronic or other means in any form without prior written permission of CvberResearch Inc TRADEMARKS CyberResearch SMD 703 and SMD 707 are trademarks of CyberResearch Inc Other product names mentioned herein are used for identification purposes only and may be trademarks and or registered trademarks of their respective companies NOTICE CyberResearch Inc does not authorize any CyberRes
3. volts 1 8 2 0 VDC ENVIRONMENTAL Operating temp 20 75 C Humidity 0 100 Shock 150 G Dust oil etc NO LIMIT MECHANICAL Weight 19 20 OZ Size Sh x 4vvx4 54 inches Mounting hole centers 3 625 x 3 625 inches Mounting screw size 6 8 SAT 38
4. Wht Green Red Red Wht Rapidsvn Grn Wht Green Red Red Wht Imc Grn Wht Green Red Red Wht Sigma Yellow Red Black Orange Oriental Motor Blue Red Black Green Portescap Yel Wht Red Org wht Brown Bodine Yellow Red Brown Orange Digital Motor Yellow Red Black Orange Warner Red Yellow Orange Brown Japan Servo Yellow Green Blue Red TABLE 2 PARALLEL WIRED Manufacturer T3 T4 T5 T6 Superior Electric White Green Red Black Rapidsyn White Green Red Black Imc White Green Red Black Sigma Red Yel Red Org Blk Orange Oriental Motor Blue White Yellow Green Portescap Yel Wht Red Org wht Brown Bodine Red Wht Red Org wht Orange Digital Motor Red Wht Red Black BIk Wht Warner Red White Orange Black Japan Servo White Green Blue White Under some conditions the unused wires mav have voltages in excess of 120 volts Consequentiv all motor wires not used should be insulated and not allowed to touch anvthing The SMD 703 707 are high frequencv switching tvpe drives Because of the power involved and the rapid rate of current and voltage change inherent in this tvpe of control considerable RFI is generated The following precautions must be taken to prevent this noise from coupling back to the inputs and causing erratic operation 1 Never bundle the motor leads in the same cable as the STEP and DIRECTION input leads 2 Alwavs keep power supplv leads as short as possible If this is impractical use 1 pF and 100 uF capacitors directly across TERMINALS 1 and 2 a
5. difference what the current set was What would be significant would be the greatly reduced motor and control heating at low speed at the lower current setting POWER SUPPLY CURRENT Power supply current depends on the current set resistor value the speed the motor is running and the load applied to the motor Generally speaking the power supply current for a 6 wire motor in the series configuration will not exceed 1 3 the motor s rated per phase current A parallel configured motor will require no more than 2 3 the rated per phase current 20 Fig 12 is representative of a parallel configured motor s power supplv current requirements vs speed The solid curve is for an unloaded motor while the dotted curve is for a fully loaded motor SUPERIOR M062 FD04 1 5A SMD 707 PARALLEL WIRED 27V POWER SUPPLV CURRENT 0 10K 20K FULL STEPS PER SECOND Figure 12 MOTOR AND CONTROL HEATING Motor and control heating is equivalent to the difference between the electrical power input and the motor s mechanical power output The ratio of the power out vs power in is the system efficiency The power losses are dependent on motor speed load and winding configuration the power supply voltage current set and other factors The power losses in the step motor drive are primarily resistive and therefore relatively easy to calculate Each channel of the drive may be considered to be equivalent to a 55 ohm resistor WARNING T
6. in amplitude with time until it reaches a peak equal to the step angle When this happens the motor loses synchronization and stops x13 Generally the amplitude build up takes from tens to hundreds of cycles to reach this level so up to several seconds may elapse from the start of the oscillation until the motor stops This time is sufficiently long to permit the motor to accelerate through this speed band however continuous operation in this range is not possible Above and below this range of speeds the oscillation amplitude may not be sufficient to stop the motor but it is still present Fig 8 shows the parametric resonance frequency versus motor step rate for three unrelated step motors In all three cases resonance breaks out at 5 to 7 revolutions per second and is most severe at the higher torsional frequencies lowest step rates SUPERIOR 062 004 150Hz ifad _7 RAPIDSYN 34D 9208A 50Hz SIGMA 20 22350 28175 RESONANT FREQUENCY 0 5KHz 10KHz 1 8 DEGREE STEP RATE Figure 8 Because any torsional oscillation implies acceleration and deceleration of a mass torque that otherwise would have been available for useful work is wasted to sustain this oscillation Both the SMD 703 and the SMD 707 incorporate a midband anti resonance compensation circuit that closes the loop on this instability and electronically damps it out Since the motor is now unable to sustain oscillation torque previously wasted i
7. the motor torque in region 1 Motor torque is approximatelv proportional to motor current times the number of winding turns that carrv the current In series operation twice the number of turns carry current as do in parallel operation so only half the current is needed to generate a given level of torque Unfortunately series operation quadruples the effective winding inductance In region 2 motor power is proportional to the inverse of the square root of the winding inductance Fig 11 illustrates the effect of various winding currents on motor performance A 4 Amp per phase motor was driven from 1 to 6 Amps per phase in 1 Amp increments In region 1 motor torque is nearly proportional to motor current Torque remains constant until it intersects the motor s load line which may be approximated as T kV fL T torque k motor constant f steps per second L motor inductance V power supply voltage The intersection of the constant torque line and the motor load line marks the beginning of region 2 Above this speed motor torque is not dependent on the current set resistor 19 400 350 6A PHASE 300 5A PHASE TORQUE 4A PHASE OZ IN 250 3A PHASE 2A PHASE 200 1A PHASE 150 100 POWER WATTS 1K 2K 3K 4K 5K 6K 7K 8K 9K 10K FULL STEPS PER SECOND SUPERIOR ELECTRIC M092 FD08 AA 3V Figure 11 Note that if the motor in fig 11 is operated in excess of 4000 steps sec it would make no performance
8. this compensates for the motor s non linearity will determine the microstep placement accuracy of the control 490 ELECTRICAL ANGLE 90 1 8 0 1 8 MECHANICAL ANGLE Figure 6 elin The electrical to mechanical angle function is dependent on motor current Bv varving the current set resistor value it mav be possible to trim out anv residual positional error Should this be insufficient MOTOR LOAD A step motor only generates torque when a rotor error angle exists The relationship between rotor displacement angle and restoring torque for a typical motor is shown in fig 7 The function that relates error angle to torque is approximately sinusoidal so an error angle equal to one microstep occurs with torque load of only 16 of holding torque Generally speaking motor load is the single most significant contributor to microstep positioning error If the load is transient or due to acceleration the rotor error will decrease to a residual level upon removal of that transient 300 TORQUE OZ IN 00 3 MECHANICAL ANGLE Figure 7 ANTI RESONANCE CIRCUIT Most step motors are prone to parametric instability or resonance when rotating between 4 to 15 revolutions per second Variously called midband instability resonance or other terms it manifests itself as a torsional oscillation of 50 to 150 Hz when the motor is running in this speed range The torsional oscillation has a tendency to increase
9. 0 350 JAPAN SERVO KPM8AM2 001 HK 2K 3k 4K 5K 6k 7K SK FULL SIEPS PER SECOND VEXTA PH268 05 euet ett seat TORQUE OZN pr 2 oo g w POWER WATTS ai n aid pr EEN OK 1K 2K 3K 4K 5K 6K 7K 8K 9K 10K 78 75 70 71 71 73 67 60 53 46 40 16 31 47 63 81 94 95 93 89 wass HK 2K 3k 4K bk 6k 7K SK FULL SIEPS PER SECOND 30 SUPERIOR MO91 FDO9 400 OK 137 0 1K 129 28 350 2K 123 54 3K 118 78 AK 98 87 300 5K 82 91 6K 70 93 7K 59 91 250 8K 49 88 m 9K 43 87 10K 37 82 200 150 TORQLE DE e kk ON 50 mm HK 2K 3K MK 5K 6K 7K B 9K 10K FULL STEPS PER SECOND in SUPERIOR MO61 FD08 OK 48 0 IK 44 9 125 2K 39 17 3K 36 24 4K 39 35 150 5K 43 48 6K 44 59 7K 43 67 125 8K 43 77 9K 42 85 0 100 10K 4 89 m REM me TORQUE oat ul 50 OZIN HK 2K 3K 4K bk 6K 7K SK 9 10K FULL STEPS PER SECOND 331 200 RAPIDSYN 23D 6306 OK 147 0 1K 138 30 175 2K 129 57 3K 120 80 4K 101 89 150 5K 77 85 6K 65 87 YK 53 83 125 TORQUE 46 82 74 OZIN 67 100 75 50 POWER MATE s oe 25 f HK 2K lk lak SK lek k k l k 10k FULL SIEPS PER SECOND m RAPIDSYN 34 9601A OK 146 0 IK 140 31 350 2K 134 59 3K 109 72 4K 87 77 3
10. 00 5K 701 77 6K 57 76 7K 48 74 250 8K 40 71 9K 34 68 10K 29 65 200 150 TORQUE 100 OZIN POWER FULL STEPS PER SECOND 2 39 a HK 2K 3K ak bk lek K B OK 400 350 300 SUPERIOR M091 FD 6006 OK IK 2K 3K 4K 5K 6K 7K 8K 10K 135 131 124 98 76 63 51 43 35 29 100 PE OZIN 50 POWER TV x HK 2K dlak 4K SK lek 7K SK j 10K FULL STEPS PER SECOND 400 VEXTA PH299 01 OK 283 0 1K 260 57 350 2K 170 75 3K 112 74 4K 78 69 300 5K 63 70 6K 49 66 7K 43 67 250 SK 35 63 Ki 31 62 10K 26 58 TORQUE OZIN aa 3K lak 5K lek FULL SIEPS PER SECOND 33 76 SK lak 10K 200 RAPIDSYN 23D 6204 TORQUE 75 OZIN HK 2K k 4K bk lek 7K SK FULL STEPS PER SECOND 200 SUPERIOR MO62 FDO4 175 150 125 100 TORQUE OZIN foa has 5 we n T d a LI ver z 4 OK IK 2K 3K 4K 5K 6K 7K 8K 9K 10K 99 95 88 67 53 42 34 28 24 21 17 21 39 45 46 47 45 42 41 39 HK 2K 3k 4K bk 6K 7K SK FULL SIEPS PER SECOND 34 10K 200 WARNER SM 200 0080 B8 OK 59 0 1K 56 12 1 5 2K 53 23 3K 53 35 AK 44 39 150 5K 36 40 6K 28 37 TK 23 36 125 SK 19 34 9K 17 34 10K 0 0 100 75 50 TORQUE OZIN ND DA 25 POWER P EMEN WATIS e
11. 0125 BC 16 a 45 53 72 92 106 126 133 152 TORQUE OZIN 3K lak 5K lek JK FULL STEPS PER SECOND MAE MY200 2240 460A8 8K 9K 10K 31 61 92 109 125 132 134 132 133 131 3K lak 5K lek JK FULL STEPS PER SECOND 24 lak 10K MAE MY200 3437 400A8 400 OK 224 1K 238 52 350 2K 229 101 3K 184 122 AK 151 134 300 5K 120 133 TORQUE 6K 101 134 7K 85 133 250 Gan 8K 73 129 130 127 HK 2K 3K AK BK 6K 7K B K 10K FULL SIEPS PER SECOND 400 SUPERIOR M093 FD11 0K 397 350 1K 397 88 E 2K 294 130 132 300 132 ml 129 124 250 120 row OZIN 200 100 150 POWER 100 WATTS 50 fu HK 2K dlak 4K SK lek 7K lek k 10K FULL STEPS PER SECOND 25 400 BODINE 3413 2005 TORQUE OZIN 76 123 125 125 126 124 118 116 111 107 00 WATTS HK 2K 3k 4K SK lek k SK l k FULL STEPS PER SECOND J APAN SERVO KP88M2 001 OK IK 2K 3K 4K 5K 6K 7K 8K 9K TORQUE 10K OZ N POWER cr ou ro mma f a res q 397 397 269 188 135 107 87 73 60 51 43 88 119 125 120 119 116 113 107 102 96 HK 2K 3K AK 5K lek 70 BK J9K FULL STEPS PER SECOND 26 10K 400 RAPIDSYN 34D 9206A OK 246 1K 234 51 350 2K 213 94 3K 156 103 4K 121 107 300 5K 98 108 6K 81 107 7K
12. 1 microsecond The maximum pulse rate is I Mhz when a 50 duty cvcle square wave is used TERMINAL 11 12 CURRENT SET The primary function of the CURRENT SET terminal is to set the magnitude of the motor phase currents This is done by connecting a 1 4 watt resistor between terminals 11 and 12 The correct resistor value in ohms is chosen from the tables below For convenience the appropriate table is also printed on the face of the step motor drive If a 6 wire motor is to be series connected use the first column otherwise use the second column for parallel connected motors Match the motor s per phase current to the closest listed table entiv then pick the resistor associated with that current TABLE 3 SMD 707 CURRENT SET RESISTOR TABLE SERIES PARALLEL RESISTOR 1 5A 75A 12K 2 0A 1 00A 15K 2 5A 1 25A 27K 3 0A 1 50A 33K 3 5A 1 75A 47K 4 0A 2 00A 68K 4 5A 2 25A 82K 5 0A 2 50A 120K 5 5A 2 75A 180K 6 0A 3 00A 270K 6 5A 3 25A 560K 7 0A 3 50A 3 3M E TABLE 4 SMD 703 CURRENT SET RESISTOR TABLE SERIES PARALLEL RESISTOR 3 0A 1 5A 12K 4 0A 2 0A 15K 5 0A 2 5A 27K 6 0A 3 0A 33K 7 0A 3 5A 47K 8 0A 4 0A 68K 9 0A 4 5A 82K 10 0A 5 0A 120K 11 0A 5 5A 180K 12 0A 6 0A 270K 13 0A 6 5A 560K 14 0A 7 0A 3 3M CAUTION Without a current set resistor present the SMD 707 and the SMD 703 default to 3 6 amp and 7 2 amp drive currents respectively If these current levels are in excess of a motor s rated per phase current thev ma
13. 67 104 250 8K 57 102 oK 49 199 10K 43 96 200 TORQLE 150 OZIN 100 me darc EEE ee kitan m a Nana POWER WATTS 50 2 xa NOR HK 2K 3K jak BK lek 7K B 9 10K FULL SIEPS PER SECOND 200 VEXTA PH265 05 OK 461 1K 39 8 175 2K 36 16 3K 35 23 AK 39 35 5K 43 48 150 6 46 62 TK 47 73 8K 49 87 125 9K 48 96 10K 49 108 100 SP di 75 TORQUE OZIN O 5 5 25 POWER nt WATS ss HK 2K 3K ak 5K lek 7K B 9 10K FULL STEPS PER SECOND a je s VEXTA PH296 01 400 OK 151 0 IK 141 31 350 2K 140 62 3K 135 90 4K 113 100 300 5K 93 103 6K 81 107 7K 68 106 250 8K 57 102 K 49 99 10K 43 96 200 TORQUE 150 _ Z N HK 2K 3k 4K bk 6K 7K SK 9 10K FULL SIEPS PER SECOND 400 BODINE 3412 2104 OK 262 0 350 1K 248 54 m 2K 213 94 3K 159 105 AK 118 105 300 2 5K 93 103 6K 74 99 94 250 88 83 200 79 3K lak 5K lek FULL SIEPS PER SECOND 28 7K 400 SUPERIOR M092 FD08 HK 2K 3K ak BK lek 7K B 9K 10K FULL STEPS PER SECOND 200 SUPERIOR ME61FD 80083 OK 74 0 WE K 70 15 a 2K 65 29 3K 65 43 4K 67 59 150 5K 68 76 6K 64 86 TK 60 oa 125 8K 54 96 9K 49 97 10K 44 98 EDU 777770 A v TORQUE 50 OZIN 2 2K 3k 4K 5K 6K 7K SK OK 10K FULL STEPS PER SECOND 29 40
14. CTOR DESCRIPTION TERMINAL 1 2 POWER SUPPLY Terminal 1 internallv connected to Terminal 12 is the power supply return or ground connection Terminal 2 is the positive power supplv input connection The power supplv voltage range is from 24 VDC to 60 VDC The power supply need not be regulated however if an unregulated power supply is used care must be taken to insure that the power supply ripple and line voltage tolerance do not exceed this specified supply voltage range The recommended power supply ripple voltage is 1 volt peak to peak or less for best performance Power supply current may be estimated for a 6 wire motor as 1 3 of the motor s per phase current rating for series operation fig 3 For parallel operation fig 4 use 2 3 of motor s per phase current rating for estimating supply current At light loads and medium speeds considerably less current is needed See PERFORMANCE CONSIDERATIONS page 16 for more information about the selection of an appropriate power supply voltage and motor operating mode WARNING ALWAYS DISCONNECT POWER TO THE DRIVE BEFORE EITHER CONNECTING OR DISCONNECTING ANY MOTOR LEADS FAILURE TO DO THIS WILL RESULT IN IRREPARABLE DAMAGE TO THE DRIVE During rapid deceleration of large inertial loads step motors generate considerable power This power is returned to the power supply by the step motor drive Usually the filter capacitor in the power supply is sufficient to absorb this power s
15. EED TORQUE amp SPEED POWER CURVES The following pages contain motor speed torque and speed power curves Two sets of curves are plotted per motor using the SMD 703 One set was taken at 54 VDC power supply voltage the other at 27 VDC The dynamometer moment of inertia was adjusted to be equivalent to the motor s moment of inertia The test data was collected at 100 points between zero and 10 000 full steps per second The motors were operated in the parallel configuration for both test runs The lower voltage test run is representative of a series configured motor run at 54 VDC supply voltage A power supply voltage between the two test run voltages would yield results between the plotted results The dotted power output curve is the mechanical power output of the motor measured in watts 205 400 SUPERIOR M093 FD14 OK 397 1K 397 88 350 2K 380 168 3K 279 185 AK 215 190 300 5K 171 190 TORQUE 140 186 OZIN 181 250 176 171 150 1 POWER WATTS 100 50 2K 3K 4K SK lek 7K B 9 10K FULL SIEPS PER SECOND 400 RAPIDSYN 34D 9214R OK 224 0 1K 213 47 350 2K 204 90 3K 195 129 4K 163 145 300 5K 137 152 TORQUE 6K 118 157 250 020 7K 99 154 8 87 154 152 w sk 76 152 200 150 100 WATIS aa A oean 50 a HK 2K 3K 4K 5k lek JK B 9K 10K FULL STEPS PER SECOND lt 23 TORQUE OZIIN WARNER SM 200
16. HE DRIVE MUST HAVE SUFFICIENT HEAT SINKING TO KEEP THE CASE TEMPERATURE BELOW 475 DEGREES C 4167 DEGREES F OR PERMANENT DAMAGE WILL RESULT 2l Step motor drive dissipation in region 1 is always considerably higher than in region 2 In region 1 motor phase currents and therefore drive channel currents are sinusoidal The peak amplitude is equal to the rated per phase current in the parallel mode and half of that in the series mode In region 1 power dissipation is approximatelv W 55 I9 for parallel wired motors W 55 10 2 for series wired motors Note that the power dissipation is 4 times higher for the parallel connection In region 2 power dissipation can be calculated as W 1 1 10 3 for parallel wired motors W 1 1 10 6 for series wired motors Region 1 power dissipation is 4 5 times greater than region 2 power dissipation If the motor will spend most of its time stopped or in region 1 use region 1 power dissipation equations to evaluate the needs for heat sinking Alternately consider reducing motor set current while the motor is stopped to reduce power dissipation As a practical guide heat sinking will almost certainly be required if the drive is set to 3 amps or more Generally if the unit is too hot to touch it needs additional cooling The case temperature should never under any circumstance be allowed to exceed 475 degrees C 167 degrees F since this will destrov the drive MOTOR SP
17. afely and keep the voltage rise to acceptable limits If the power supply cannot absorb this power the voltage generated may exceed the 60 VDC limit of the drive Damage may result to the control power supply or both In this rare instance an external voltage clamp such as a 68 volt zener diode is recommended as protection For protection against motor to ground shorts power supply voltage reversal and other anomalies use a 5 AMP fuse from the power supply to TERMINAL 2 EXAMPLE Design an unregulated power supply for use with a SUPERIOR ELECTRIC M092 FDOA Series operation at 35 VDC will be used dz VDC 1 The M092 FDO4 has a current rating of 4 Amps per phase Because series operation is to be used power supply current will not exceed Isupply IM 3 4 3 1 33 AMPS 115 V Figure 1 2 For a ripple voltage of 1 volt or less the minimum capacitor C1 size is C1 Isupply x 8333 1 33 x 8333 11 000 MFD 3 The transformer T1 secondary voltage is going to be VRMS Vsupply x 7071 35 x 7071 25 VAC The secondary current rating should be at least 1 5 AMPS TERMINAL 3 4 5 6 MOTOR OUTPUT One motor winding connects to terminals 3 and 4 while the other winding connects to terminals 5 and 6 The step motor drive will operate 4 6 and 8 wire motors The 6 and 8 wire motors may be wired in either a series or parallel configuration For 8 wire motors follow the manufacturer s hook up diagrams for s
18. ain speed the motor torque begins to drop off as the inverse of the speed Motor winding inductance limits the rate of current rise and as speed increases progressively less current can be forced into the windings Because motor torque is proportional to phase current and in region 2 current is proportional to the step period torque decreases as the inverse of the step rate Because power is the product of speed and torque power remains constant with speed in region 2 in a loss less step motor There are speed related power losses in the motor i e friction magnetic losses windage and other losses that result in a shallow slope to the power curve Where this slope intersects the speed axis is the maximum speed at which the motor will run CAUTION The SMD 703 707 drive is capable of running step motors at speeds high enough to cause damage to motor bearings FACTORS AFFECTING POWER AND TORGUE POWER SUPPLY VOLTAGE The choice of power supply voltage affects the power a step motor generates in region 2 The speed to which constant torque is maintained is proportional to power supply voltage Consequently maximum motor shaft power is also proportional to the power supply voltage The step motor drive has a power supply range from 24 to 60 VDC This results in a motor power range of 2 5 1 Increasing power supply voltage increases motor heating Taking this into consideration the choice of power supply voltage should be
19. earch product for use in life support systems medical equipment and or medical devices without the written approval of the President of CyberResearch Inc Life support devices and systems are devices or systems which are intended for surgical implantation into the body or to support or sustain life and whose failure to perform can be reasonably expected to result in injury Other medical equipment includes devices used for monitoring data acquisition modification or notification purposes in relation to to life support life sustaining or vital statistic recording CyberResearch products are not designed with the components required are not subject to the testing required and are not submitted to the certification required to ensure a level of reliability appropriate for the treatment and diagnosis of humans CONTENTS General DesEriptiON u EE a 1 Connector Description esse see see ee ena 3 Power Supply Requirements 3 PUSE RE RE N EE EE EE kwense se 3 Motor Outp t a b ee ee esee FA 4 Motor WINE S AE i W AE va ih eds 5 Series Wired iion e 5 Parallel Wired sie festen SG EE y a aa GEE eio tees 5 Motor Wire Color Codes eee 6 Noise Precau tions eere re eene AA 7 Direction and Step Inputs eee 7 Ea e dina 8 Default Current soos qu cenit oo W AC nek aa 9 Standby Implementation 9 AAA ere
20. eries or parallel operation WARNING BEFORE EITHER CONNECTING OR DISCONNECTING ANY MOTOR LEADS ALWAYS DISCONNECT THE POWER FIRST IF THIS IS NOT DONE THE DRIVE WILL BE PERMANENTLY DAMAGED The most common step motor has 6 lead wires which connect to a pair of center tapped windings A typical 6 wire motor is shown below fig 2 The SUPERIOR ELECTRIC color code is used in this example 4 m RED WHT GREEN WHITE GRN WHT Figure 2 SERIES WIRED RED Pin 5 RED WHT d Pin 6 NC GREEN GRN WHT Pin 4 Pin 3 Figure 3 PARALLEL WIRED RED Pin 5 BLACK Pin 6 NC GREEN WHITE Pin 4 Pin 3 Figure 4 5 Parallel wired step motors have twice the peak shaft power as series wired step motors Parallel wired step motors also have more that twice as much heat dissipation as do series wired motors For a more thorough discussion see the PERFORMANCE CONSIDERATIONS section starting on page 16 When using the series configuration select the appropriate current set resistor from the CURRENT SET RESISTOR TABLE When using the parallel configuration or a 4 wire motor make the selection from the PARALLEL column The proper motor wire color code to drive connector hook up for series and parallel operation is shown in the tables below This hook up will yield clockwise motor rotation when the DIRECTION input is at a logical O TABLE 1 SERIES WIRED Manufacturer T3 T4 T5 T6 Superior Electric Grn
21. es motor vibration The multiplier is 10 for the SMD 707 and the SMD 703 Thus a 200 step per revolution motor when driven by this control will take 2000 steps to complete one revolution Microstepping is accomplished by driving the motor windings with sine and cosine weighted currents A 90 degree electrical angle change in these currents results in a mechanical angle change of 1 8 degrees in a 200 step motor or one full step The number of microsteps per step is determined by the number of sine and cosine values stored for a span of 90 degrees In the SMD 703 707 values are stored for every 9 electrical degrees for a total of 10 for the 90 degree span A counter in the SMD 703 707 addresses a look up table that contains pre calculated sine and cosine values These values are multiplied by a value proportional to the motor s rated current determined by the current set resistor The results are converted to phase currents and applied to the motor The STEP input in conjunction with the DIRECTION input increments or decrements this counter which then selects the next look up table entry Low speed vibration results from the start stop or incremental motion of the motor This generates periodic acceleration and deceleration reaction torques at the step rate When the step rate matches or is a sub harmonic of the mechanical resonant frequency of the motor the vibrations become particularly severe Microstepping decreases the magn
22. iod at the STEP input Any variation in excess of this limit may result in missed steps There are some digital pulse sources that have more than a 15 period to period variation To use these sources without error the anti resonance disabled version of the step motor drive should be ordered 15 PERFORMANCE CONSIDERATIONS This section will deal with factors that affect motor performance and the interactions between these factors This should permit the designer to achieve the optimum balance of performance trade offs The factors considered will be TORQUE OUTPUT POWER POWER SUPPLY VOLTAGE SERIES vs PARALLEL OPERATION POWER SUPPLY CURRENT MOTOR HEATING MOTOR DRIVE HEATING TORGUE AND POWER vs SPEED Step motor performance curves exhibit two distinct regions with respect to speed In region 1 fig 9 motor torque is constant with speed while motor shaft power is proportional to speed In region 2 motor torque decreases as the inverse of the speed while motor shaft power remains constant 400 REGION 1 REGION 2 300 OZ IN TORQUE 250 200 150 POWER 100 POWER WATTS 50 5K 6K FULL STEPS PER SECOND 7K 8K 9K 10K Figure 9 16 In region 1 the motor torque is held constant bv controlling the magnitude of the motor phase current The step rate in this region is sufficiently low to permit motor current to reach the programmed value Above a cert
23. itude of each step ten fold with a commensurate decrease in vibration Vibration is further reduced because at any given speed the microstep rate is 10 times higher than the equivalent full step rate One apparent benefit of microstepping is an increase in the number of resolvable angular positions However there are a number of factors which limit its achievable open loop accuracy ba FACTORS AFFECTING MICROSTEP ACCURACY MOTOR ACCURACY Most step motors are specified as having a 5 non accumulative step tolerance This implies that a 200 step per revolution motor will have an absolute accuracy of 1 part out of 2000 If the motor were run open loop as most step motors are only a ten fold increase in accurately resolvable locations can be expected Consequently a 125 microstep drive cannot position a motor any more accurately than a 10 microstep drive such as the SMD 703 707 in an open loop configuration MOTOR LINEARITY For every motor there is a function that relates the angle of rotation to the electrical angle of the winding currents If it were directly proportional then sine and cosine varying currents would cause a uniform rate of rotation Alternately this would result in uniformly spaced microsteps For most motors this function is S shaped to a greater or lesser degree fig 6 The motor current profiles must be distorted from their ideal sine cosine profiles to compensate for this non linearity How well
24. just high enough to meet the application s power requirements and no higher Liz SERIES vs PARALLEL OPERATION The customer has the option of wiring 6 and 8 wire motors in either series or parallel configuration Parallel operation doubles the maximum motor power output over what can be obtained with series operation The speed to which constant torque is maintained is also doubled This performance improvement comes at the expense of greater motor and control heating Series operation is preferred for low speed region 1 operation and suitable in region 2 if the available power is sufficient Series operation benefits are low motor and control heating and modest power supply current requirements Using the power supply voltage range in conjunction with either series or parallel operation permits a 5 1 range in maximum motor power Fig 10 illustrates the effects of series vs parallel operation at low and high power supply voltages on motor performance Note that series operation at 54 VDC supply voltage yields performance virtually identical to parallel operation at 27 VDC supply voltage 200 175 T1 P1 27 volts full winding T2 P2 54 volts full winding T3 P3 27 volts half winding 150 T4 P4 54 volts half winding TORQUE OZ IN P4 105W 50 POWER WATTS 25 IK 2K 3K 4K 5K 6K 7K SK 9K 10 FULL STEPS PER SECOND Figure 10 18 TORQUE The current set resistor determines
25. nal components The drives require a single voltage unregulated DC power supply between 24 VDC and 60 VDC The power supply current requirements are very modest For 6 wire step motors wired in the series configuration the power supply current is approximately 1 3 of the motor s rated per phase current A high efficiency switching H bridge output utilizes power MOSFETS to keep heating to a minimum Under most conditions the drives will not require heat sinking It is sufficient to bolt them down to a metal chassis in the user s system The drives are small measuring 4 x 4 5 x 8 and weighing only 1 2 Ib They come encapsulated in a heat conductive epoxy and encased in an anodized aluminum outer cover The result is a compact environmentally rugged package that resists abuse that would destroy most other controls 200 WARNER SM 200 0125 BC OK 81 0 175 1K 73 16 2K 71 31 3K 67 45 150 AK 601 53 m oe 125 BK 65 72 RE d 6K 69 92 100 Torque e SK 67 126 OZIN _ 9K 67 133 a 10K 68 152 ng wag ee e 50 Por d POWER eum 25 WATS jen ak 2K 3k jak SK Jek 7K SK ek oK FULL SIEPS PER SECOND 200 MAE MY200 2240 460A8 OK 145 1K 144 31 175 ASE 2K 138 61 Gan 3K 139 92 AK 124 109 125 132 134 132 133 131 2K l k 4 5 jk k SK 9K 10K FULL SIEPS PER SECO ND CyberResearch s SMD 703 MICROSTEP DRIVE Actual Size 22 CONNE
26. s now available 14 With anti resonance the motor mav be run continuousiv at speeds where de svnchronization would otherwise occur The motor no longer exhibits forbidden continuous operation speed bands and there is more torque available outside these speed ranges as well The operation of the anti resonance circuit in most applications is transparent to the user in the sense that no special provisions have to be taken to accommodate it There are three instances where it mav be disadvantageous 1 VERY HIGH SPEED The anti resonance circuit limits the maximum speed to 30 000 full steps per second 300 000 pulses per second Should it be necessarv to run the motor faster than that up to 100 000 full steps per second a special anti resonance disabled version of the step motor drive can be ordered a SUPERIOR ELECTRIC ME61 8001 will exceed 100 000 full step per second or 30 000 RPM 2 VERY LARGE INERTIAL LOAD Microstepping permits reliable operation with inertial loads in excess of 100 times the motor s moment of inertia However a very large inertial load so lowers the mechanical resonant frequency that the anti resonance circuit may cause oscillation It may be better to order the drive without the circuit since resonance usually is not a problem with moderate to large inertial loads anyway 3 IRREGULAR PULSE TRAIN To operate properly the anti resonance circuit cannot tolorate more than a 15 variation in the pulse per
27. s ons HK 2K lak 4K BK 6K 7K B 9 10K FULL STEPS PER SECOND 400 SUPERIOR M091 FD03 OK 149 IK 131 29 350 2K 76 33 3K 51 34 AK 37 33 300 SK 26 29 6K 21 29 250 TK 17 26 gt amp 0 0 9 0 0 200 10K 01 TORQUE OZIN 180 07M 5K 6 K 9K 10K FULL STEPS PER SECOND GAS RAPIDSYN 23D 6102 200 OK 63 0 175 IK 56 12 2K 55 24 3K 47 31 4K 36 32 150 5K 28 31 6K 22 30 7K 18 29 125 8K 0 0 9K 0 0 10K 0 0 100 75 50 TORQUE OZIN 25 POWER ORE aaa WAT Pa HK 2K lak 4K Bk 6K 7K B 9 10K FULL STEPS PER SECOND 200 SUPERIOR MO61 FDO2 OK 63 0 1K 59 13 125 2K 50 22 3K 35 23 150 4K 28 24 5K 21 23 6K 17 23 125 TK 0 0 8K 0 0 9K 0 0 100 10K 0 75 50 TORQU OZIN 25 BOMER A WATTS it HK 2K 3K 4K bk GK 7K SK 9 10K FULL STEPS PER SECOND 36 SPECIFICATIONS PARAMETER MIN MAX UNITS ELECTRICAL GENERAL Resolution SMD 703 SMD 707 1 1 Full step Supply voltage 24 60 VDC Current no motor 50 60 mA PWM frequency 18 24 kHz Motor current SMD 707 75 3 5 ampere SMD 703 1 5 7 0 ampere Motor Inductance 1 mH STEP PULSE INPUT Voltage 0 5 0 VDC Input impedance 12 20 mA Pulse high 1 USEC Pulse low 1 uSEC Rise time 5 HSEC Fall time 5 USEC Frequency 500 KHz Logic 1 volts 1 8 2 0 VDC DIRECTION INPUT Voltage 0 5 0 VDC Current 12 20 mA Logic 1
28. t the step motor drive 3 Never wire capacitors inductors or any other components to the motor output terminals 4 Always ground the chassis that the step motor drive is mounted on 5 Always ground the motor case 6 Never use op amps optocouplers or other slow transitioning devices to drive the STEP input Keep the logic transitions to 200 nSec or less TERMINAL 7 NO CONNECTION SMD 703 707 On the SMD 703 707 microstep drives this terminal is reserved for future use Do not connect TERMINAL 8 9 10 DIRECTION AND STEP INPUTS Terminal 8 is DIRECTION input A low level on this terminal will result in a clockwise microstep when the STEP input is pulsed on a SMD 703 or SMD 707 microstep drive Terminal 9 is the STEP input A step occurs on the high to low transition of the STEP input the direction being set by the level on the DIRECTION input at that moment Terminal 10 is the 5 VOLT common to terminal 8 and 9 E The DIRECTION and STEP inputs are opticallv isolated from the rest of the step motor drive circuitrv The isolated inputs are intended to be driven directly by standard TTL or open collector outputs Because TTL is current sink logic the driver 5 VDC power supply must be connected to terminal 10 5 VOLT Both the DIRECTION and STEP inputs require 16 mA current sink capability The logic transition time for the STEP input must be 200 nanoseconds or less The minimum pulse width for the STEP input is
29. v damage the motor For good low speed smoothness with the SMD 703 707 the motor set current should not vary more than 20 from the nominal value This is because accurate microstep spacing occurs over a narrow range of currents Currents substantiallv above or below this range mav reduce microstep positioning accuracv and increase low speed vibration The CURRENT SET terminal has a secondarv function One optional use for the CURRENT SET input is to set a lower standbv current while the motor is stopped or shut off motor current altogether A standbv current can be set bv switching another resistor in parallel with the current set resistor The standbv current will be equivalent to the resulting parallel wired resistor If the current set resistor is shorted out motor current goes to zero and the motor is freewheeling Fig 5 shows how an opticallv isolated standbv torque and freewheeling functions mav be implemented 9 STANDBV CURRENT ET RESISTOR io Wou o mz 4 Figure 5 WARNING NEVER CONNECT OR DISCONNECT ANY OF THE MOTOR LEADS WITHOUT FIRST DISCONNECTING THE POWER IF POWER IS NOT TURNED OFF BEFORE ATTACHING OR REMOVING THE MOTOR WIRES THE DRIVE WILL BE DAMAGED BEYOND REPAIR 10 MICROSTEPPING Microstepping is a technique that electronically multiplies the number of steps a motor takes per revolution This is useful because it increases motor angular resolution and decreas
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