Quantization by ΔΣ modulators for anti-windup control

This paper considers a control system that has saturation and quantization of its control input. A system with saturation may be suffered from windup. Then, quantization generates quantization errors, which may deteriorate control performance. In this paper, the windup is mitigated by an anti-windup controller, whereas the effect of the quantization errors is reduced by a ΔΣ modulator. To keep the stability obtained by the anti-windup controller, the ΔΣ modulator is tuned off when the control signal is saturated. The ΔΣ modulator is designed to minimize the H2 norm of the transfer function from the quantization error to the system output. Numerical examples are provided to demonstrate the performance of our proposed system. © 2021 The Institute of Electrical Engineers of Japan.