Emerson Unidrive SPM User Manual Download Page 258

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Safety

Information

Introduction

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System

configuration

Mechanical

Installation

Electrical

Installation

Getting
Started

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parameters

Running

the motor

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SMARTCARD

operation

Onboard

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Data

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UL Listing

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258

Unidrive SPM User Guide

www.controltechniques.com Issue Number: 3

Defines the time of injection braking during phase 1 with stopping modes
3 and 4, and during phase 2 with stopping mode 2 (see Pr

6.01

When this bit is set the drive remains active even when the run
command has been removed and the motor has reached standstill. The
drive goes to the 'StoP' state instead of the 'rdy' state.

13.21.6 Line power supply loss modes

0: diS

There is no line power supply loss detection and the drive operates
normally only as long as the DC bus voltage remains within specification
(i.e. >Vuu). Once the voltage falls below Vuu an under-voltage ‘UV’ trip
occurs. This will reset itself if the voltage rises above Vuu Restart, as
stated in the table below.

1: StoP - Open-loop

The action taken by the drive is the same as for ride through mode,
except the ramp down rate is at least as fast as the deceleration ramp
setting and the drive will continue to decelerate and stop even if the line
power supply is re-applied. If normal or timed injection braking is
selected the drive will use ramp mode to stop on loss of the supply. If
ramp stop followed by injection braking is selected, the drive will ramp to
a stop and then attempt to apply dc injection. At this point, unless the line
power supply has been restored, the drive is likely to initiate a trip.

1: StoP - Closed-loop vector or Servo

The speed reference is set to zero and the ramps are disabled allowing
the drive to decelerate the motor to a stop under current limit. If the Line
power supply is re-applied while the motor is stopping any run signal is
ignored until the motor has stopped. If the current limit value is set very
low level the drive may trip UV before the motor has stopped.

2: ridE.th

The drive detects line power supply loss when the DC Bus voltage falls
below Vml

. The drive then enters a mode where a closed-loop

controller attempts to hold the DC Bus level at Vml

. This causes the

motor to decelerate at a rate that increases as the speed falls. If the line
power supply is re-applied it will force the DC Bus voltage above the
detection threshold Vml

and the drive will continue to operate normally.

The output of the line power supply loss controller is a current demand
that is fed into the current control system and therefore the gain Pr

4.13

and Pr

4.14

must be set up for optimum control. See parameters Pr

4.13

and Pr

4.14

for set-up details.

The following table shows the voltage levels used by drives with each
voltage rating.

* Vml

is defined by Pr

6.48

. The values in the table above are the

default values.

The line power supply loss detection level can be adjusted using this
parameter. If the value is reduced below the default value, the default
value is used by the drive. If the level is set too high, so that the line
power supply loss detection becomes active under normal operating
conditions, the motor will coast to a stop.

Open-loop

These parameters control the proportional and integral gains of the
current controller used in the open loop drive. As already mentioned the
current controller either provides current limits or closed loop torque
control by modifying the drive output frequency. The control loop is also
used in its torque mode during line power supply loss, or when the
controlled mode standard ramp is active and the drive is decelerating, to
regulate the flow of current into the drive. Although the default settings
have been chosen to give suitable gains for less demanding applications
it may be necessary for the user to adjust the performance of the
controller. The following is a guide to setting the gains for different
applications.

Current limit operation:

The current limits will normally operate with an integral term only,
particularly below the point where field weakening begins. The
proportional term is inherent in the loop. The integral term must be
increased enough to counter the effect of the ramp which is still
active even in current limit. For example, if the drive is operating at
constant frequency and is overloaded the current limit system will try
to reduce the output frequency to reduce the load. At the same time
the ramp will try to increase the frequency back up to the demand
level. If the integral gain is increased too far the first signs of
instability will occur when operating around the point where field

6.07

Injection braking time

Uni

0.0 to 25.0 s

1.0

6.08

Hold zero speed

Bit

OFF (0) or On (1)

OFF (0)

On (1)

6.03