Proportionnels

Proportionnels is a term found in French-language technical literature that generally refers to elements or concepts based on proportionality. In English discussions of control theory and systems, the closest equivalent is proportional control, and the plural form “proportionnels” is sometimes encountered when translating French texts or describing related components. The core idea is that the output is scaled directly by a proportional factor relative to an input quantity or error signal.

In control systems, a proportional controller, or P controller, produces an output that is proportional to the measurement error e(t) = setpoint − process_variable. The control action is u(t) = Kp · e(t), where Kp is the proportional gain. A higher Kp yields faster response but can increase overshoot and cause instability if set too high. A lower Kp reduces aggressiveness and may leave a steady-state error in some processes. P controllers are simple, robust, and inexpensive to implement, making them common in servo loops, temperature controls, and basic regulation tasks.

Limitations of proportional control include the potential for steady-state error in the presence of constant disturbances or nonzero load and sensitivity to model uncertainties. Because the control action depends only on the instantaneous error, there is no integral action to eliminate offset over time. In practice, P control is often combined with integral and/or derivative terms, forming PI or PID controllers, to improve accuracy and dynamic performance.

Beyond control theory, proportionnels also appear in mathematics and physics to describe direct proportionality, where one quantity scales linearly with another via a constant of proportionality. See also direct proportion, proportionality, and gain.