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Chapter 3 Paramters/Functions Innovation Series Medium Voltage GP Type - G Drives GEH-6385
System Data Parameters

Exec time/Chop freq

The parameter Exec time/Chop freq defines the Task 1 executi on period and the
chopping frequency for the Innovation Series drive product.
Task 1 is the fastest sch eduled software process executed wi thin the control.
Primary bridge inter face and high-bandwidth aspect s of the motor control algorith m
operate in Task 1. Slower ta sks execute at integer multip les of the Task 1 interval.
The Task 1 execution period determines the maximum inner regulator bandwidth and
maximum fundamenta l operating frequency.
The chopping frequency defines the rate at which the power devices may switched
through a full modulation cycle (for example, from the on state, to the off state, and
back to the on state again) . The chopping frequency affects t he spectral content of
the output waveform, and defines a bridge power de-rating factor which must be
considered in th e application of the product.
Chopping frequencies are synchronized to the Task 1 interval such that exactly one
transition or two transitions can be configured to occur per Task 1 period.

Values

The following table describes the available selection s for Exec time/Chop freq:
Parameter
Selection
Exec
Time
(usec)
Chop
Freq
(KHz)
Fund
Freq
(Hz)
Power
Derate
(%)
Comments
333 usec, 1.5 KHz 333.3 1.5 200 100 Default
500 usec, 1.0 KHz 500.0 1.0 133 100 Evaluation
only

Motor ctrl alg sel

Parameter Motor ctrl alg sel specifies the presence or absence of a tachometer in the
system and the use of the tach ometer in the motor control.
The drive can run the motor using a tachometer-based contr ol scheme, a tachless
control scheme, or a mixtur e of the two. Tachometer-based control uses speed
feedback from the tachometer to regulate the speed and torque of th e motor. Tachless
control provides motor speed and torque regulation without a tachometer. The hybrid
control scheme uses ta chometer feedback for speed regula tion but not for motor
torque regulation. Greater speed and torque accurac y can be attained when a pulse
tachometer is used with the tachometer-based control .
The following values ar e available for Motor ctrl alg sel:
• Tachless control: Tachless control of motor speed and torque.
• Tach control and sfb: Tach ometer-based control of motor sp eed and torque.
• Tachles ctl/Tach sf b: Tachometer-based control of motor speed, tachless control
of motor torque.