Nidec Unidrive M600 Series User Manual

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164 Unidrive M Regen Design Guide
Issue Number: 4
9.4 Menu 4: Current control
In Regen mode separate current control is provided for the active and reactive currents. The active current reference is normally produced by the
DC bus voltage controller and power feed-forwards system, although it is possible for the user to define the active current reference if required.
The reactive current reference is either defined directly from the Reactive Current Reference (04.008) or from the Reactive Power Input kVAR
(03.020). See Menu 3 for more details.
Drive rating information
Current rating
The drive output currents can be represented as a vector. The limits and the scaling applied to the drive output currents are defined by the magnitude
of this vector as shown below.
Throughout this section Rated Current (05.007) and other parameters related to motor 1 are used.
The full scale current is the maximum current that the drive can measure and if the current exceeds this level the drive produces an over current trip.
Kc is the current scaling for the drive and is used in determining the control performance of the drive. This is given in Full Scale Current Kc (11.061)
and Kc is equal the full scale current in r.m.s. Amps. (Note that this is a change from Unidrive SP which used the full scale current multiplied by 0.45
for Kc.)
The maximum current reference is the highest magnitude of the current reference vector in the drive under any circumstances. The area between the
maximum current reference and the full scale current provides headroom to allow for overshoot in the current controllers without tripping the drive. In
all modes except Open-loop mode, the current limits can be adjusted so that the maximum current reference vector (IMaxRef) is equal to 0.9 x Kc
provided Rated Current (05.007) is set to the Maximum Heavy Duty Rating (11.032) or less. If Rated Current (05.007) is set to a higher level then the
current limits can be adjusted so that the maximum current reference vector (IMaxRef) is equal to 1.1 x Maximum Rated Current (11.060) or 0.9 x Kc
whichever is lower.
The drive can have a heavy duty rating intended for applications where high overload current may be required under transient conditions, or it can
have a normal duty rating where a lower level of overload current is required. The duty rating is selected automatically by the drive based on the
setting of Rated Current (05.007). The Maximum Heavy Duty Rating (11.032) and Maximum Rated Current (11.060) are fixed for each drive size and
the table below shows the possible duty ratings that can be selected depending on the levels of these parameters.
The different duty ratings modify the inductor protection characteristic (see Inductor Thermal Time Constant (04.015)). The different duty ratings can
also change the level of IMaxRef as described previously.
In a drive that contains multiple power modules Full Scale Current Kc (11.061) is the full scale current of an individual module multiplied by the
number of modules. Maximum Heavy Duty Rating (11.032) and Maximum Rated Current (11.060) are the value for an individual module multiplied by
the number of modules.
Variable Maximums applied to the current limits
In Regen mode the drive orientates the output current vector to align with the voltage vector that represents the voltage at its terminals, and so unless
specifically required, all the current is active current and there is no reactive current. Therefore the maximum value for the current limit parameters is
calculated as:
VM_MOTOR1_CURRENT_LIMIT = (I
MaxRef
/ I
Rated
) x 100%
Conditions Possible duty ratings
Maximum Heavy Duty Rating (11.032) = 0.00 Normal duty operation only
Maximum Heavy Duty Rating (11.032) < Maximum Rated Current (11.060)
Heavy duty operation if rated current > MAX, otherwise
normal duty operation
Maximum Heavy Duty Rating (11.032) = Maximum Rated Current (11.060) Heavy duty operation only
Current
vector
I
MaxRef
= 0.9 x Kc
Kc
Current
vector
Drive output current vector scaling and limits
Kc
I
MaxRef
= 0.7 x Kc I
PeakLimit
= 0.8 x Kc
Reactive
current
Reactive
current
Active
current
Active
current
Open loop current control mode
All modes except open loop mode
I
MaxRef
= 0.7 x Kc

Nidec Unidrive M600 Series Specifications

General

Brand	Nidec
Model	Unidrive M600 Series
Category	DC Drives
Language	English