Automated System Identification of Digitally-Controlled Multi-phase DC-DC Converters

Abstract

Real-time system identification is desirable for designing a proper feedback controller in a practical system. Digital control provides the potential advantages of on-line programmability to apply adaptive control. The digital nature of the feedback signal facilitates the communication between the converter and the processing unit (e.g., microcontroller). These features of digital control make it possible to estimate the real-time system parameters by means of system identification in situ (in-place), and then design and configure the controller accordingly. In this paper, an automated system identification method for digitally-controlled multi-phase DC-DC converters is set forth. Fourier analysis is utilized because of the potential for closed-loop identification and high measurement signal-to-noise ratio. The phase loss and zero-order-hold due to digital control are considered. The identification results for single- and multi-phase DC-DC converters closely match those obtained from conventional network analyzer and models. The proposed method can be done by a stand-alone digital controller; therefore it eliminates the expense of external test equipment. The identification results can be used for controller configuration without pre-existing knowledge of the power stage parameters. This opens up a possibility of moving the determination of the loop compensation from a lab bench to a factory floor or even to an end customer's application.