Inverse Estimation of Dynamic Heat Flux Using Proportional Integral Derivative Control

To improve long-term dynamic heat flux prediction using an embedded thermocouple, a novel inverse estimation approach using a proportional integral derivative (PID) control scheme is proposed. A feedforward model of the discrete integer-order transfer function was identified from a one-dimensional dynamic heat-flux sensor using the calibrated heat flux with varying amplitudes of the pseudo-random binary sequence and its single-temperature response data. Using the model and unit-step temperature response as the controlled plant and reference input signal, the PID controller with a low-pass filter was designed. Using the on-site temperature measurement data as the reference signal instead of the unit-step temperature, the time-history control output values, that is, the inverse estimated dynamic heat flux of the designed PID controller, were obtained. The comparison of the test results and the discussion indicate that 1) the proposed inverse method avoids the impact of the thermal inertia of the thermocouple and significantly alleviates the effects of measurement noise, and 2) in addition to high identification efficiency and measurement fidelity, further improvement in the effective measuring time of the dynamic heat flux was observed.