Difference between revisions of "Using stepping motor with IONI"
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Using stepping motor with [[IONI]] drive is possible in three ways: | Using stepping motor with [[IONI]] drive is possible in three ways: | ||
− | ;Open loop (no encoder) | + | ;Mode1 - Open loop (no encoder) |
:This is the traditional stepping motor drive method. Will achieve highest speed and is easily configurable but there is no feedback, so if motor stalls/loses synchronism, the absolute position will be unknown before referencing/homing. | :This is the traditional stepping motor drive method. Will achieve highest speed and is easily configurable but there is no feedback, so if motor stalls/loses synchronism, the absolute position will be unknown before referencing/homing. | ||
− | ;Closed loop (with encoder feedback) | + | ;Mode 2 - Closed loop (with encoder feedback) |
:This is open loop mode combined with encoder feedback. The advantages are that drive can detect loss of synchronism and restore to commanded position with ''clear faults'' command. May be used also with linear encoder to enhance system accuracy. | :This is open loop mode combined with encoder feedback. The advantages are that drive can detect loss of synchronism and restore to commanded position with ''clear faults'' command. May be used also with linear encoder to enhance system accuracy. | ||
− | ;Servo (with encoder feedback) | + | ;Mode 3 - Servo (with encoder feedback) |
:In this mode, a stepping motor is used as high pole count brushless servo motor. In this mode, motor efficiency is high (no current if no load) and motor do not lose synchronism. However, motor speed is limited by back EMF of motor and typically can achieve lower top speed than the other modes. | :In this mode, a stepping motor is used as high pole count brushless servo motor. In this mode, motor efficiency is high (no current if no load) and motor do not lose synchronism. However, motor speed is limited by back EMF of motor and typically can achieve lower top speed than the other modes. | ||
Revision as of 19:07, 14 June 2015
Using stepping motor with IONI drive is possible in three ways:
- Mode1 - Open loop (no encoder)
- This is the traditional stepping motor drive method. Will achieve highest speed and is easily configurable but there is no feedback, so if motor stalls/loses synchronism, the absolute position will be unknown before referencing/homing.
- Mode 2 - Closed loop (with encoder feedback)
- This is open loop mode combined with encoder feedback. The advantages are that drive can detect loss of synchronism and restore to commanded position with clear faults command. May be used also with linear encoder to enhance system accuracy.
- Mode 3 - Servo (with encoder feedback)
- In this mode, a stepping motor is used as high pole count brushless servo motor. In this mode, motor efficiency is high (no current if no load) and motor do not lose synchronism. However, motor speed is limited by back EMF of motor and typically can achieve lower top speed than the other modes.
Setting up open loop mode
In this mode, drive emulates encoder internally and some tuning parameters need to be set to allow operation:
- MT Motor type
- Stepping motor
- FBD Feedback device
- None
- FBI Invert feedback direction
- Unticked
- FBR Feedback device resolution
- 6400 (this is the emulated encoder resolution, 6400 PPR = 25600 steps/rev)
- MCC Motor continuous current
- This is the resting current when motor stands still. Drive will switch to this after 0.5 seconds of standing still.
- MMC Motor peak current limit
- This is the motor rated current that is used when motor is rotating.
- MR Motor coil resistance
- See motor datasheet or if not known, start with low values such as 1 ohm
- ML Motor coil inductance
- See motor datasheet or if not known, start with low values such as 1 mH
- CM Control mode
- Set to Position control (typical) or Velocity control mode
- KVP Velocity P gain
- 0
- KVI Velocity I gain
- 900
- AFF and VFF
- 0
- KPP Position P gain
- 150
- PFF Position feed-forward gain
- 100%
- FEV Over speed fault
- 1000
- FPT and FVT fault limits
- 1000
Other settings are not critical and can be configured as desired (such as acceleration and velocity limits).
Use Granity's Measure resistance & inductance button to automatically set MR and ML |
To save time, you may load this template settings file to drive. Usage: connect to the drive with Granity, and click Load settings from file. After loading the file, just set motor current limits MMC and MCC to match your motor. After saving & restarting drive, use Measure resistance & inductance button to automatically set MR and ML. |
NOTE: these values and settings apply from firmware version 1.2.1 (1064). For older firmware version, check out earlier version of this page here.
Seting up closed loop mode (with encoder feedback)
In this mode, follow parameterization of closed loop mode except:
- FBD Feedback device
- Choose your feedback device (other than None)
- FBI Invert feedback direction
- Try both settings and choose the one with stability
- FBR Feedback device resolution
- Set your feedback device resolution
- KVI and KPP
- Tune KVI and KPP values (and possibly other gains if non-zero) to have nice response
- FMO Motion fault limit
- Set non-zero value (perhaps 100-1000) to cause a fault state when motor stalls
Setting up servo mode
To set-up stepper as servo motor, just follow the IONI & IONICUBE user guide and consider the stepper motor as servo motor. For a typical 1.8 degree/step two-phase stepping motor the correct motor type parameters are: