B.1: I 2 T Algorithm - Copley Controls Xenus Plus Series User Manual

Xenus Plus User Guide
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B.1: I T Algorithm
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B.1.1: I T Overview
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The I T current limit algorithm continuously monitors the energy being delivered to the motor using
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the I T Accumulator Variable. The value stored in the I
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I T setpoint that is calculated from the user-entered Peak Current Limit, I
Continuous Current Limit. Whenever the energy delivered to the motor exceeds the I
algorithm protects the motor by limiting the output current or generates a fault.
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B.1.2: I T Formulas and Algorithm Operation
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Calculating the I T Setpoint Value
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The I T setpoint value has units of Amperes
motor data. The setpoint is calculated from the Peak Current Limit, the I
Continuous Current Limit as follows:
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I T setpoint =
(Peak Current Limit
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I T Algorithm Operation
During drive operation, the I
related to the output current Sampling Frequency. The value of the I
incrementally increased for output currents greater than the Continuous Current Limit and is
incrementally decreased for output currents less than the Continuous Current Limit. The I
Accumulator Variable is not allowed to have a value less than zero and is initialized to zero upon
reset or +24 Vdc logic supply power-cycle.
Accumulator Increment Formula
At each update, a new value for the I
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I T Accumulator Variable n+1 =
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I T Accumulator Variable n
+(Actual Output Current n+1
After each sample, the updated value of the I
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setpoint. If the I T Accumulator Variable value is greater than the I
limits the output current to the Continuous Current Limit. When current limiting is active, the output
current will be equal to the Continuous Current Limit if the commanded current is greater than the
Continuous Current Limit. If instead the commanded current is less than or equal to the Continuous
Current Limit, the output current will be equal to the commanded current.
Copley Controls
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-seconds (A
– Continuous Current Limit
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T algorithm periodically updates the I
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T Accumulator Variable is calculated as follows:
– Continuous Current Limit
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T Accumulator Variable is compared with the I
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T Accumulator Variable is compared with the
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S) and is calculated from programmed
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) * I T Time Limit
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T Accumulator Variable at a rate
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T Accumulator Variable is
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) * Update period
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T Setpoint value, then the drive
16-01344 Rev 06
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T Time Limit, and
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T setpoint, the
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T Time Limit, and the
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T
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T