Phase lead

Valid for S300, S700

The servo amplifiers have an adjustable current- (torque-) dependent or speed-dependent phase lead for servomotors.

Speed-dependent phase lead

This can also be called field suppression for permament magnet servomotors (in contrast to asynchronous machines). (\velocity angle advance", parameter MVANGLB,  MVANGLF,  MVANGLP)

Each magnet rotor induces a voltage, proportional to the speed, in the stator windings, which is inverse to the voltage driving the rotor (generator principle). This means that at a particular voltage in the intermediate circuit a speed will always be reached at some point at which the full current is no longer obtained in the windings because the voltage is insufficient; at some point the induced voltage will be sufficiently large that no more current can be generated in the windings at all.

As long as this boundary is not reached (rated speed), there will be no further malfunction, but sometimes high speeds are required. If a rotor is now used that is less strongly magnetized, this boundary will be reached at a higher speed, but the torque is also lower at the same current (same voltage, same current = constant output: higher speed => lower torque).
Of course, it is not practicable to replace the rotor if you want more torque at a reduced speed on one occasion, and on another need high speeds and thus have to accept a reduced torque.
Field-oriented control, however, gives us the opportunity to electrically weaken the magnetic field by generating a directional magnetic field counter to the rotor field. In this way, higher speeds can be reached with the same power supply.

The phase lead behavior is preselected using the MVANGLMODE parameter:

MVANGLMODE 0 :
Recommendation for speed-controlled applications and/or those that require a rapid response (dynamic response): So that a spindle, for example, can sensibly hold a speed above the rated speed, a field-weakening current is always applied even if no torque is otherwise required. This operation also secures a voltage headroom so that the maximum possible current and, accordingly, the maximum possible torque can be generated immediately in the case of a load impulse.

MVANGLMODE 1 :
Recommendation for current-controlled operation or with minimum current, e.g. in the case of applications where the axis simply "spins" at times and is actually driven by another motor. Although no torque is required, the regulator applies a current above MVANGLB. As in a torque phase lead, only the angle is advanced; the absolute current value is, however, unchanged. This mode reacts less dynamically than mode 0.

Torque-dependent phase lead

This setting is only required for motors with buried magnets (internal or buried magnets) such as the Kollmorgen Goldline Series (torque angle advance; parameter MTANGLP). In the case of machines with this type of rotor, the commutation angle, at which the optimal maximum torque is produced for this particular current, will shift dependent on the absolute current value.
In contrast to this, AKM motors have surface-mounted magnets (surface magnets) and do not require this setting.

Problematic applications

Hall Feedback:
As the field suppression affects the rotor magnetic field and Hall sensors evaluate this magnetic field, Hall-only feedback will not function together with field suppression.

Sensorless:
Sensorless operation will also be problematic as the induced voltage will be changed.

Help:
For these operating modes, always switch off (both) at least at the start of the phase leads.
( MTANGLP=0,  MVANGLB= VLIM,  MVANGLF=0,  MVANGLP=0)