Application manual
Air quality multisensor and regulator EK-ES2-TP
Release 1.0 - Updated: 14/02/2020
Application Manual
© EKINEX S.p.A. - All rights reserved
Page 88
Picture 14 - Continuous Proportional-Integral control
Integral Time is the amount of time necessary to repeat the vaue of the control variable of a purely proportional controller,
when error is constant.
For example, with a purely proportional controller with Proportional Band = 4 K, if Setpoint = 20°C and
Measured Temperature = 18°C, the control variable will be 50%. If Integral Time = 60 minutes, if error remains constant, the control
variable will be 100% after 1 hour, i.e. the controller will add to the control variable a contribution equal to the value due to its
proportional part.
In heating and air conditioning systems, a purely proportional controller cannot guarantee reaching the Setpoint. An integral action is
mandatory in order to reach the Setpoint: for this reason the integral action is also called automatic reset.
9.3
PWM Proportional-Integral control
The proportional-integral PWM (Pulse Width Modulator) controller uses an analog control variable to modulate
the duration of the time intervals in which a binary output is in the On or Off state. The controller operates in a
periodic manner over a cycle, and in each period it maintains the output to the On value for a time proportional
to the value of the control variable. As shown in Picture 15, by varying the ratio between the ON time and the
OFF time, the average time of activation of the output varies, and consequently the average intake of heating
or cooling power supplied to the environment.
T ambient [°C]
0%
100%
T Setpoint
T ambiente [°C]
T Setpoint
Narrow Proportional Band
50%
Wide Proportional Band
0%
100%
50%
Narrow Proportional Band
Wide Proportional Band