ROPEX THEORETICAL MODEL
ROPEX: self-sensing technology
The semiconductor power regulator, the so-called controller, delivers an electric power P (measured in Watts) to the resistive load. The input power P input causes a Joule effect
P = R∙I2
raising the temperature T of the resistor.
Resistivity variation
The temperature variation ∆T alters the resistivity ρ of the material, consequently its electrical resistance R (measured in Ohm), according to the following equation:
RT = R0[1+T-T0]
where R0 is the resistance to a reference temperature T0, and α is the temperature coeffcient of the resistance (TCR).
Measurement and reading: the intrinsic feedback
The change in R acts as an intrinsic feedback signal. This change in resistance is measured by a signal conditioning and data acquisition circuit and converted into an estimated temperature T.
The read value T is processed in real time to determine the new control signal (the power supply P).
No predictive system can match the unbeatable accuracy of ROPEX.
The accuracy of the ROPEX system cannot be matched by a predictive control system that relies on:
- External temperature probes (remote sensors) because they introduce a thermal delay (latency) and measure the temperature of the surrounding environment or media, not the actual temperature of the resistor (sealing band)
- corrective/predictive algorithms (e.g.: arti
Summarizing: a predictive control or a simulation model based on external data (Model-Based Control) does not achieve the dynamic response and precision of an intrinsic direct feedback.
Advantages and conclusions
The use of the resistor itself as an intrinsic temperature sensor guarantees an extremely precise and fast closed-loop control (high bandwidth of the control system), since the feedback comes directly from the heat source (self-sensing).
With ROPEX your process is REALLY under control./strong>
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