Difference between revisions of "Using digital Hall sensor feedback without encoder"

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Revision as of 17:17, 9 February 2018

Using an AC & BLDC motor is possible in torque, velocity and position control modes based on their digital Hall sensors only, i.e. not requiring precision position feedback device such as encoder. This page describes how to configure and use such motor with Granite Devices drives.

Hall sensor only allows using low cost BLDC/AC motors in less demanding applications. Hall sensors are mainly intended for motor electrical commutation only (in other words to make it rotate in the first place), but they also provide low resolution position and velocity feedback.

Prerequisites

• Check that your drive supports Hall sensor feedback from Drive feature matrix.
• Following guide assumes that the drive has factory default settings, i.e. no existing configuration. If you wish to reset your drive to default settings, perform an firmware install and check the "Reset device parameters to factory state" in the Granity firmware upgrade dialog.
• Granity version 1.14 or later is required
• Use the latest firmware for your drive (i.e. on IONI firmware V1.7.1 or later is required)
• Read your drive user guide from this wiki before jumping into configuration because the configuration guide below is very much shortened and cuts many corners that you may need to know.

Configuration

In short, procedure for setting up motor in Hall sensor mode operation, perform following operations in Granity.

1. Configure your motor type in Machine page. In minimum, make following settings correct based on your motor specs:
   1. Set Motor typeMT to "3 phase AC or BLDC"
   2. Set Pole countMPC to match your motor magnetic pole count
   3. Set current limits MMC and MCC according to your motor specs, or optionally a lower value
   4. Set FBD to "Digital Hall sensors"
   5. Set FBR to a value of 8192*[MPC]. I.e. on 4 pole motor, set it to 32768.
   6. Set motor coil resistance and inductance if known as parameters MR and ML
   7. Save settings and restart drive. Enable drive to activate the motor either by wiring Enable signal to drive, or using software override enable checkbox "Ignore physical disable signal (force enable)" in Connect page.
      1. Ensure that drive is enabled and the Run (drive active) status is on from the Testing tab status info. If not, troubleshoot why the status is not active.
   8. If MR and ML are at default settings (i.e. not set according to motor specs), use "Measure resistance & inductance" button to set them automatically
   9. Click "Autodetect commutation sensor" button to automatically measure & configure the Hall sensor settings

At this point motor should work well at least in torque mode. To test it, go to Testing tab and use "Increment by TSP1" button several times to increase motor current until it starts spinning. If spin happens, you have completed configuration in torque mode!

If you see faults, such as "overvelocity fault" during torque test, you might need to adjust settings at Fault limits page.

Configuring motor in velocity and/or position control mode follows the standard procedure just like in sensored operation mode. Refer to your drive user guide for details.