EcoStruxure™ Control Expert - HVAC Library

Heating, Ventilation and Air Conditioning Solutions EFB Library
Published by Schneider Electric

Features

  • Library Content
  • Scaling and Descaling Control
  • Single or Multi Loop Controls
  • Cascade Controller
  • Air Mix Controller for Air Conditioning
  • PI Controller
  • Scaling / Sequence Block
  • Summer/Winter Setpoint Compensation
  • Universal PI Controller

Library Content

HVAC Library contains 11 function blocks:


6 basic function blocks (Basic Group)

  • The basic function blocks implement low level functions for basic air conditioning solutions

  • 5 complex function blocks (Complex Group)

  • The complex function blocks implement the more complex functions found in controllers which are frequently used in air conditioning systems. They are built using the basic function blocks
  • Library Content

    Scaling and Descaling Control

    A control set up consists of 3 parts:

  • The scaling of input variables
  • The scaling of inputs can be handled using standard libraries or the HVAC library SEQ_VAC EFB can be used.


  • The controller
  • For the purposes of the HVAC library, the controller and output sequencing are combined into 1 EFB. The combination of the controller with the output sequencing has been done to simplify the parameterization of the EFB as the output sequence parameters can be assigned at the same time as the controller parameters


  • The sequencing of output variables
  • ”Output Sequencing” is used to take the controller single output, split it into several parts, and to scale the resultant outputs. It can be used for example, to split the controller output amongst multiple actuators

    Scaling and Descaling Control

    Single or Multi Loop Controls

    Single Loop

  • In the case of simple, single loop controls, the purpose of the output sequencing is simply to match the controller output to the process actuators)
  • For controllers operating in simple P–mode, the controller output will equal zero when the setpoint is equal to the process variable.
  • Multi Loop

  • As well as single loops directly connected to process outputs, cascaded loops where the output of 1 controller is connected as the setpoint of another controller are often required for HVAC systems.
  • The use of cascaded controllers gives improved dynamics, it also results in a clearer and easier to understand layout of the HVAC controls.
  • Single or Multi Loop Controls

    Cascade Controller

    The CC2_VAC block is a cascade controller used to provide temperature or humidity control of the inlet air to a room

  • It consists of a P–only outer loop which uses the room temperature/humidity as process variable and an inner PI loop that controls the temperature/humidity of the inlet air supplying the room.
  • winter/summer setpoint compensation as per DIN 1946 pert 2
  • 4 quadrant operation of the output sequence scaling
  • Operation with Anti–Windup–Reset (AWR)
  • Cascade Controller

    Air Mix Controller for Air Conditioning

    The MC_VAC block is a controller designed for applications that require switching of the controller direction, and maximum/minimum selection of outputs.


    Examples of such applications would be air mixing controls where the control direction will depend on the relative values of the outside air temperature and return air temperature, or heat exchanger controls used in energy conservation schemes

  • selection of operating mode as a ”Direct Controller” or ”Auxiliary Controller” with max/min selection
  • winter/summer setpoint compensation as per DIN 1946 pert 2
  • 4 quadrant operation of the output sequence scaling
  • Operation with Anti–Windup–Reset (AWR)
  • Air Mix Controller for Air Conditioning

    PI Controller

    The PI_VAC basic function block is a general PI–controller designed for air conditioning applications.


    It can be used for temperature control, humidity control, air mixing control or other general functions. This basic function block consist of a PI controller only with no setpoint compensation, output sequencing, or other functions. It is used extensively by the complex function blocks.

  • SP (setpoint), PV (process variable) and BIAS inputs
  • Bumpless initialization of the I contribution as well as bumpless switching between I and PI operation
  • HALT operating mode for freezing the controller output at its current value with tracking of the I Contribution
  • DYNAMIC HALT operating mode that helps to avoid step–changes in the controller output when the setpoint is changed
  • Operation with Anti–Windup–Reset (AWR)
  • PI Controller

    Scaling / Sequence Block

    SEQ_VAC is a basic function block that can be used to scale real input variables to real output variables using a linear relationship.


    The block can be used to scale both process variable inputs as well as controller outputs.

  • 4 quadrant operation, allowing the creation of both positive, negative, forward and reverse acting sequences
  • limitation of the outputs Y1...Y2 when the input range X1...X2 is exceeded When this happens, the variables QMIN and QMAX are set.
  • manual operation mode to allow the presetting of the output in percentage form
  • Scaling / Sequence Block

    Summer/Winter Setpoint Compensation

    SW_VAC is a basic function block that provides summer/winter compensation of a temperature setpoint based on the outside air temperature command variable CV.

  • summer/winter setpoint compensation with summer compensation following the DIN 1946 Part 2 standard
  • switchable operating modes offering the choice of compensation or no compensation
  • Summer/Winter Setpoint Compensation

    Universal PI Controller

    The UC2_VAC complex function block is a general PI–controller designed for air conditioning applications.


    It can be used for temperature control, humidity control, air mixing control or other general functions.


    It consists of a PI controller, summer/winter setpoint compensation and 2 or 3 output sequences.

  • winter/summer setpoint compensation as per DIN 1946 part 2
  • 4 quadrant operation of the output sequence scaling
  • operation with Anti–Windup–Reset (AWR)
  • Universal PI Controller
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