Post Ramp Reference (02.001), i.e. during deceleration. As the motor slows down power is fed into the d.c. link of the drive which causes the voltage to

rise. When the voltage reaches the level defined by the Standard Ramp Voltage (02.008) the d.c. link voltage controller becomes active and provides a

torque producing current reference. This system regulates the d.c. link voltage to hold it at the level defined by the Standard Ramp Voltage (02.008).

Generally as the motor slows down the deceleration needs to be increased to provide enough power to maintain the d.c. link level. The frequency is not

allowed to fall faster than the final deceleration rate, and so a point is reached where the controller de-activates itself, and the final deceleration rate is

used until the motor reaches standstill. If at any point the Pre-ramp Reference (01.003) is equal to or further from zero than the Post Ramp Reference

(02.001), i.e. not decelerating, the d.c. link voltage controller is de-activated.

2: Standard ramp with motor voltage boost

Standard ramp with motor voltage boost is the same as standard ramp mode except that the motor voltage is boosted by 20% to increase the motor

losses and reduce the deceleration time.

If the Standard Ramp Voltage (02.008) is set to a level that is below the nominal d.c. link voltage level the motor will coast during deceleration because

the torque producing current reference is limited to prevent the motor from accelerating. There are circumstances where the motor may not decelerated

and so there is a system within the drive to detect this. In some circumstances this feature is undesirable and so can be disabled

(see Deceleration Fail Detection Disable (02.009) ).

3: Fast ramp with motor voltage boost

Fast ramp with motor voltage boost is the same as Fast ramp mode except that the motor voltage is boosted by 20% to increase the motor losses and

reduce the deceleration time.

Unidrive M200 Parameter Reference Guide

Issue: 01.05.00.10

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