.Buildings.Controls.OBC.CDL.Reals.Ramp

Information

Block that limits the rate of change of the input u by a ramp if the boolean input active is true, otherwise the block outputs y = u.

This block computes a threshold for the rate of change between input u and output y as thr = (u-y)/Td, where Td > 0 is a parameter. The output y is computed as follows:

• If thr < fallingSlewRate, then dy/dt = fallingSlewRate,
• if thr > raisingSlewRate, then dy/dt = raisingSlewRate,
• otherwise, dy/dt = thr.

A smaller time constant Td > 0 means a higher accuracy for the derivative approximation.

Note that when the input activate switches to false, the output y can have a discontinuity.

Implementation

For the block to work with arbitrary inputs and in order to produce a differentiable output, the input is numerically differentiated with derivative time constant Td.

Revisions

• February 15, 2024, by Michael Wetter:
  Updated documentation.
• November 16, 2022, by Jianjun Hu:
  First implementation.