Difference between revisions of "Essential Basics"
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| − | These basics are the most fundamental steps to get a motor running in order for an application to work properly | + | These basics are the most fundamental steps to get a motor running in order for an application to work properly. |
# Motor supply voltage (HV) can be higher than nominal motor voltage | # Motor supply voltage (HV) can be higher than nominal motor voltage | ||
Revision as of 11:53, 25 July 2018
These basics are the most fundamental steps to get a motor running in order for an application to work properly.
- Motor supply voltage (HV) can be higher than nominal motor voltage
- Digital servo drives are practically sophisticated switching step-down voltage regulators, and the torque controller takes care that the current to the motor (and thus the voltage) is correct.
- The HV can be at least five times the nominal motor voltage without any issues and reduced performance.
- The maximum current to the motor is not the maximum current of the PSU
- Considered as a step-down regulator, the digital servo drive transfers power, not current to the motor. Because of this, the PSU's current rating affects maximum power that can be driven into a motor, not maximum current.
- E.g. 48 V PSU with 10 A current rating can output 480 W power. If the required voltage to a motor to drive 24 A current is 20 V, the transferred power is the same what the PSU can supply.
- Encoder must be attached directly to the motor shaft
- In practice, all gears and other similar mechanics have non-idelities such as play, torsion, and/or possibility of slipping.
- Play and torsion will introduce delay to the feedback loop, and will cause oscillation due to which the tuning is impossible to get precise.
- Slipping encoder will cause false angle data, which will cause the motor to either stall or run loose.
- Encoder resolution must be exact for each rotation. Rounded data will also cause the magnetic angle to be lost, and the motor will stall or run loose after few turns.
- Torque tuning must be done properly
- Poor torque tuning will result in excessive current spikes and at worst mechanical oscillation
- Testing motor and encoder wiring in torque mode
- Before velocity or position tuning, the system must be tested without any load in torque mode to ensure proper functionality.
- Follow the instructions here: Servo motor torque mode test
