Overview Stepper otor is a high accuracy position control otor which digital control rotating by a set echanical angle decided by input pulses is available. It is available to control a rotation angle and speed accurately and it has lots of proper applications to be used. We have hybrid stepper otor with high characteristic such as a high accuracy and torque, which is used in a wide range of to OA fi eld. Also, we have the driver (MD5/MD2U Series) and controllers (PMC Series) in order to get a high effi ciency with our stepper otor. Rotor core Shaft Shaft Bearing Rotor core Rotor teeth Bearing Coil Bobbin Stator core eatures Coil Stator teeth lange Cover Stator core Peranent agnet It is available to control a rotation angle and speed easily. 5-phase stepper otor is available to control the rotation angle and speed easily by electrical pulse (digital) signal as it is the otor rotating by a set echanical angle decided by input pulse (digital) signal. It is a high torque and response otor. Stepper otor is sall & light and can get a high torque. Also, rapid starting/stopping and reversing are available due to rapid acceleration as it has a stopping and starting torque. It is available to control a position in a high resolution and accuracy. Our 5-phase hybrid stepper otor rotates by 0.72 / pulse and it is a high-resolution otor, which is available to rotate by 0.00288 /pulse when using icro step driver with 250 division. And, it stops in a high accuracy of ±3in (0.05 at non-load) when driving by 0.72 /pulse. It has a self-holding torque. 5-phase stepper otor has a high holding torque when stopped in power on. Therefore, it is available to hold a stop position without echanical break or control signal. Settling is short and there is no hunting status when stopped. Settling which otor axis is stopped after noral and reverse rotation by load inertia is short when otor is stopped at a stop position. There is no hunting which otor axis is stopped with delicate noral and reverse rotation when holding a stop position after settling. < Stepper otor > Rotation angle Stop position No Hunting in the stop position after oving Usage of Stepper Motor Stepper otor can control a rotation angle and speed easily by nuber and speed of input pulse as follows. Rotation angle control Rotation angle[ ]Step angle[ ]Pulse nuber Input pulse nuber Rotation angle 1-pulse 0.72 2-pulse 1.44 500-pulse 360 < ull step operation of 5-phase stepper otor (0.72 ) > Rotation speed control Rotation speed[rp] Pulse speed[hz] 60[Sec] 360 /Stop angle[ ] Input pulse nuber Rotation speed 500[Hz] 60[rp] 2000[Hz] 240[rp] 5000[Hz] 600[rp] < ull step operation of 5-phase stepper otor (0.72 ) > A driver only for the stepper otor and the controller only for controlling the driver are necessary in order to drive the stepper otor. Stepper otor Autonics has various stepper otor to eet custoer's needs. 5-phase stepper otor Shaft type AK-Series Built-in brake type AK-B Series Rotary actuator type AK-R Series Hollow shaft type AHK-Series Geared type AK-G Series Geared + Built-in brake type AK-GB Series Rotary actuator + Built-in brake type AK-RB Series Driver It is an exclusive driving circuit to drive the stepper otor and provides power to the otor in the order of the otor phase. We have the dedicated drivers for stepper otor. 5-phase stepper otor driver < Servo otor > Settling Hunting Tie (t) MD5-ND14 MD5-HD14 MD5-HD14 MD5-H14 MD5-H28-2X/3X 2-phase stepper otor driver Rotation angle Stop position Settling There is hunting in the stop position after oving Tie (t) MD2U-MD20 MD2U-ID20 Q-70
Controller It controls a rotation angle and speed etc. of the stepper otor. We have the dedicated controllers. PMC-1HS/2HS (1/2-Axis high speed) PMC-2HSP/2HSN (2-Axis high speed Interpolation Noral) Stepper otor driving syste PLC PC Start/Stop CW, CCW signal signal Setting signal for rotating direction PMC-1HS/2HS MD5-HD14 (1 2-Axis high speed) PMC-4B-PCI (4-Axis board type) Stepper otor Micro Step? Micro step is a way to divide the basic step angle of the otor into saller steps by decreasing the current to one phase. Micro step has the better resonance and vibration characteristics. It realizes high-accuracy controlling with saller step angles divided by controlling coil current. Realizing low-speed / low-vibration and low noise driving Dividing otor's basic step angle into 250 divisions (0.72 to 0.00288 ) DC Power Driver Vs AC Power Driver Characteristics In case of AC power supply, the higher speed, the better torque characteristics than DC power. Under the sae driver conditions, the higher the power supply, the better torque characteristics otors can have. Proper safety countereasures ust be ensured when supplying high power supply. It ay cause high heat generation. Torque (kgf c) 10 8 6 4 MD5-HD14 (20VDC) MD5-HD14 (35VDC) MD5-H14 (100VAC) MD5-H14 (220VAC) 2 0 5 10 15 Speed (PPS) ailure Diagnosis and Countereasures Resonance The otor ay cause resonance within the specific frequency area. Take the easureent before driving the otor. 5-phase stepper otor driver resonance area: Approx. 300 to 500pps 2-phase stepper otor driver resonance area: Approx. 200pps How to iprove vibration characteristics Adjusting RUN current Changing input pulse frequency Applying icro step function Selecting geared type otors Using DAMPER Using anti-vibration rubber Using elastic couplings Heat generation Possible causes for heat generation include applying higher power supply, driving with higher RUN current than rated current and long & continuous driving without stops. How to iprove heat generation characteristics Adjusting RUN current Adjusting RUN DUTY ratio (Setting STOP longer than RUN.) Mounting heat prevention panels Applying Auto current down, HOLD O functions Using a fan Missing step A phenoenon that a stepper otor is incapable of rotating as the frequency of input pulse. Major Causes Motor failure Rapid De/Acceleration of Motor Iproper otor torque selecting for load Wrong driving speed setting (lower than ax. starting frequency) Low input current Troubleshooting Change a otor Reduce driving speed / Make otor's acceleration longer Change a otor having high torque. Select a geared type otor Drive a otor within starting frequency band. (Refer to otor's characteristics.) Increase input current (A) Photoelectric (B) iber Optic (C) Door/Area (D) Proxiity (E) Pressure () Rotary Encoders (G) Connectors/ Connector Cables/ Sensor Distribution Boxes/Sockets (H) Teperature (I) SSRs / Power (J) Counters (K) Tiers (L) Panel (M) Tacho / Speed / Pulse (N) Display Units (O) Sensor (P) Switching Mode Power Supplies (Q) Stepper Motors & Drivers & (R) Graphic/ Logic Panels (S) ield Network Devices DC Power Driver 20 to 35VDC Relatively low torque characteristics Siple circuit structure Cost effective vs AC Power Driver 100 to 220VAC High torque characteristics Relatively coplex circuit structure due to AC to DC conversion circuit Expensive (T) Software Q-71
Calculation Method for Selecting Stepper Motor It shows calculation ethod required in the selecting order. In real calculation it is ipossible to get echanical constant in any cases. Therefore, siple calculations are shown herewith. Decision of driving pattern It is shown as the drawing converting the operation of the driving equipent to the rotating operation of the otor in the equipent using stepper otor. The below chart by starting speed acceleration /deceleration, driving speed and position decision of otor. The stepper otor is selected based on driving pattern chart. speed Acceleration Moving distance Position decision < Pattern > Necessary pulse nuber for the aount of oving distance Positioning < Start-stop driving pattern > Deceleration Calculation of Necessary pulse nuber It is the nuber of the pulse that should be input to stepper otor in order to transfer an object fro starting position to target position by the carrying equipent. It is calculated as follows. Necessary pulse nuber Moving distance of object 360 Moving distance for 1 revolution Step angle Calculation of the It is the necessary in order to rotate as uch as the necessary pulse nuber in the set position decision. The necessary pulse nuber, the position decision and the acceleration/deceleration calculate the driving. 1)or start-stop driving Start-stop driving is what the stepper otor stops after revolving as uch as the necessary pulse nuber for the position decision operating in the driving without acceleration/ deceleration on the otor driving. Start-stop driving is used when driving a otor in low speed. Also, it needs high acceleration/deceleration torque as it needs a rapid speed change. The driving of start-stop driving is calculated as follows: [Hz] Necessary pulse nuber[pulse] Positioning [sec] 2)or acceleration/deceleration driving Acceleration/deceleration driving is what stepper otor stops decelerating the speed into the starting region after driving at the for certain when driving in accelerating the rotation speed of the otor by changing slowly the driving in the starting region for the positioning. Acceleration/deceleration should be set properly depending on the carrying distance/speed and positioning. In case of acceleration/deceleration driving it needs lower acceleration/deceleration torque than self-start driving as its speed changes gently. The driving of acceleration /deceleration is calculated as below. [Hz] Necessary pulse nuber-starting [Hz] Acceleration Deceleration [sec] Positioning [sec] - Acceleration Deceleration [sec] pulse speed Starting pulse speed Acceleration Deceleration Necessary pulse nuber for the aount of oving distance Positioning < Acceleration Deceleration driving pattern > Siple calculation of the necessary otor torque The necessary otor torque (Load torque + Acceleration Deceleration torque) Safety rate Calculation of load torque (T L ) Load torque indicates the friction power of a contacting part of the carrying equipent and this torque is always needed when the otor is driving. Load torque is changed by the kinds of carrying equipent and the weight of an object. The calculation of load torque according to the kinds of carrying equipent is as below. Siple calculations without considering the constant are shown as below because it is ipossible to get echanical constant in any cases. Load torque can be calculated referring to below figures and nuerical forulas. 1) Ball-Screw driving Calculation of load torque α Directly connected coupling T L P B μ + 0 0 P B 1 [kgf c] 2πη 2π i Siple calculation of load torque A + (sinα+μcosα)[kg] T L P B 1 [kgf c] (horizontal load) T L P B 1 2 [kgf c] (vertical load) Q-72
2) Wire-Belt/Rack-Pinion driving Calculation of load torque T L πd D 2ηi A + (sin + μcos α) [kg] Siple calculation of load torque [kgf c] T L D 1 1 [kgf c] (horizontal load) 2 η i T L D 1 1 2 [kgf c] (vertical load) 2 η i 3) Pulley driving Calculation of load torque T L μ A+ πd 2π i (μ A+)D [kgf c] 2i Siple calculation of load torque T L D 1 [kgf c] 2 i 4) By real easureent Load SET B Spring balance [kg] It is the calculation ethod by reading the scale ark of the spring balance at the when the pulley is rotated when drawing the spring balance slowly. It is available to get ore accuracy load torque than by the calculation. It is available to calculate the load torque as follows with the value ( B ) calculated by the spring balance. T L BD [kgf c] 2π [Index] : Load of axis direction[kg] 0 : Pre-pressure load η : Efficiency ratio (0.85 to 0.95) [kg] ( 1/3 ) A : External force[kg] i : Deceleration rate μ : riction coefficient : The total weight of μ 0 : Internal friction coefficient of pre-pressure NUT (0.1 to 0.3) work and table[kg] α : Slop angle[ ] P B : Ball-screw pitch[c/rev] B : The force when starting the revolution of ain shaft[kg] D : Outside diaeter of pulley Calculation of Acceleration/Deceleration torque (Ta) Acceleration Deceleration torque is for accelerating or decelerating the carrying equipent connected to the otor. It changes largely depending on the of acceleration deceleration and the value of load inertia oent of the carrying equipent. Therefore, the torque between self-start driving and acceleration deceleration driving will show a big difference. Acceleration Deceleration Torque is calculated as follows: or start-stop driving (high acceleration deceleration torque is required) Acceleration Deceleration Torque[kg. c] Rotator inertia oent[kgf. ²] + Load inertia oent[kg. ²] Gravitational acceleration[c/sec²] π Step angle[ ] frequency²[hz] 180 3.6 / Step angle[ ] Acceleration/Deceleration driving Acceleration Deceleration Torque[kgf. c] Rotator inertia oent[kg. ²] + Load inertia oent[kg. ²] Gravitational acceleration[c/sec²] π Step angle[ ] 180 frequency[hz]-starting frequency[hz] Acceleration Deceleration [sec] Calculation Exaple for Motor Selection Calculation of the nuber of the necessary pulse and the speed of the driving pulse. These are practical exaples for the nuber of the necessary pulse and the speed of the driving pulse with 5-phase stepper otor as below. When driving ball-screw When carrying an object as follow figure for 1sec. by using 5-phase stepper otor (0.72 /step), the nuber of the necessary pulse and the speed of the driving pulse are calculated as follows: Necessary pulse nuber 100 360 5,000[Pulse] 10 0.72 Ball screw Pitch 10[] Transportation distance 100[] If it executes start-stop driving for a second the speed of the driving pulse is calculated as 5,000[Pulse]/1[sec]5[kHz] but, the start-stop driving is ipossible at 5[kHz] and it should be driven with acceleration deceleration driving. If calculating with setting the acceleration deceleration as 25% of the position decision and 500[Hz] of the starting, it will be calculated as follows: pulse 500[Pulse] -500[Hz]0.25[sec] speed[hz] 1[sec]-0.25[sec] 6.5[kHz] (A) Photoelectric (B) iber Optic (C) Door/Area (D) Proxiity (E) Pressure () Rotary Encoders (G) Connectors/ Connector Cables/ Sensor Distribution Boxes/Sockets (H) Teperature (I) SSRs / Power (J) Counters (K) Tiers (L) Panel (M) Tacho / Speed / Pulse (N) Display Units (O) Sensor (P) Switching Mode Power Supplies (Q) Stepper Motors & Drivers & (R) Graphic/ Logic Panels (S) ield Network Devices (T) Software Q-73
It will be figured as follows: 6.5[kHz] Starting 500[kHz] 0.25[sec] 0.25[sec] 1[sec] <Acceleration Deceleration driving pattern > When driving the tiing belt When carrying an object as following figure for 1sec. by using 5-phase stepper otor (0.72 /step), the oving distance/revolution is approx. 50[] by 2πr as the circuference of the pulley. As the oving distance/ revolution is 50[] the nuber of the necessary pulse is calculated as follows: Necessary pulse 1,100 360 11,000[Pulse] nuber 50 0.72 It will be figured as follows: Transportation distance 1,100[] D16 If driving with acceleration deceleration like the exaple of a ball-screw the driving is calculated as follows: pulse 11,000[Pulse] -500[Hz]0.25[sec] speed[hz] 1[sec]-0.25[sec] 14.5[kHz] 14.5[kHz] Starting 500[Hz] 0.25[sec] 0.25[sec] 1[sec] <Acceleration Deceleration driving pattern > Calculation exaple of load torque (T L ) It is a real calculation exaple of load torque by using 5-phase stepper otor by siple nuerical forulas. When using ball-screw for driving horizontal load When carrying an object by using a ball-screw with 90[%] of efficiency and 40[kg] of the load weight as following figure, the load torque is calculated as follows; T L P B 1 [kgf c] T L 40[kg]1[c] 1 7.07[kgf c] 2π0.9 1 40[kg] When using tiing belt for driving horizontal load When carrying an object by using a tiing belt with 90[%] of efficiency, 16[] diaeter of pulley and 9[kg] of the load weight as following figure, the load torque is calculated as follows; 9[kg] T L D 1 1 [kgf c] 2 η i T L 1.6[c] 1 1 9[kg] 8[kgf c] 2 0.9 1 When using ball-screw and decelerator for driving horizontal load When carrying an object by using a ball screw with 5[] pitch, 90[%] of efficiency and 250[kg] of the load weight as following figure, the load torque is calculated as follows; Stepper otor Decelerator Deceleration rate1:10 D16 T L P B 1 [kgf c] T L 250[kg]0.5[c] 1 2.21[kgf c] 2π0.9 10 The calculation result is for a horizontal load. Vertical load torque is 2 s of the horizontal load torque. Its result is only for load torque. Acceleration Deceleration torque should be added for real necessary torque of the otor. But, it is very difficult to get the oent of load inertia in the calculation. In order to solve the difficulty it will be easy to calculate applying the start-stop driving or a large safety rate when acceleration deceleration is rapid at the calculated load torque. Q-74
Glossary Torque (kgf c) 1) Holding Torque 2) Maxiu running Torque 3) Pull-in Torque 4) Pull-out Torque 7) Maxiu slewing frequency (A) Photoelectric (B) iber Optic (C) Door/Area 5) Pull-in range 6) Slew range (D) Proxiity requency (pps) 9) Unstable range 8) Maxiu starting frequency Torque Torque, oent of force, is the tendency 2c of a force to rotate an object. Torque unit: N or kgf c (1 N 10.1972 kgf c) Required torque to rotate a rotator of which radius is 1c in case of 1kg 1kg weight is applied. Refer to torque-frequency reference below. 1) to 6) have direct effect on driver's perforance. 1) Holding torque The aount of torque the otors produce at standstill while rated current is applied to the otors. In general, it is referred to as stepper otor's driving capacity. 2) Maxiu running Torque Max. torque when running stepper otor with low speed (10pps) 3) Pull-in torque Max. torque to drive a load within starting frequency range. 4) Pull-out torque Max. torque required for a stepper otor to drive without pull-out within axiu starting frequency. 5) Pull-in range (Max. starting range) Max. torque range that a stepper otor can drive a load with a certain frequency lower than ax. starting frequency. It is allowed for the load to start & stop and forward & reverse rotation without de/acceleration within pull-in range. In case of driving a otor out of pull-in range, start a otor within pull-in range and do de/acceleration driving. 6) Slew range (Pull-out range) Max. torque range required for a stepper otor to drive without pull-out within axiu starting frequency 7) Maxiu slewing frequency Max. frequency at which a stepper otor can rotate without fail to synchronize when driving a otor within ax. starting frequency range in order to increase input frequency. 8) Maxiu starting frequency Maxiu frequency is required for stepper otors to start & stop and forward & reverse rotation without de/ acceleration in the state of no load. If it is required to drive a otor with higher frequency than ax. starting frequency, drive a otor fro ax. starting frequency and do de/ acceleration driving. 9) Unstable range Within low speed area, resonance ay occur. Drive the otor after taking the easureent for resonance area. (E) Pressure () Rotary Encoders (G) Connectors/ Connector Cables/ Sensor Distribution Boxes/Sockets (H) Teperature (I) SSRs / Power (J) Counters (K) Tiers (L) Panel (M) Tacho / Speed / Pulse (N) Display Units (O) Sensor (P) Switching Mode Power Supplies (Q) Stepper Motors & Drivers & (R) Graphic/ Logic Panels (S) ield Network Devices (T) Software Q-75