Analytical Closed-Loop Response of Discrete-PI-Controlled High-Bandwidth Current Loop in PWM Converters & Drives

Upamanyu, K and Narayanan, G (2022) Analytical Closed-Loop Response of Discrete-PI-Controlled High-Bandwidth Current Loop in PWM Converters & Drives. In: 2022 IEEE International Conference on "Power Electronics, Smart Grid, and Renewable Energy", PESGRE 2022, 2-5 Jan 2022, Trivandrum.

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Abstract

High-bandwidth current loop of a PWM converter or drive includes a transport delay. Since this delay is represented by an exponential function, the closed-loop reference-tracking and disturbance-rejection transfer functions of the loop are of infinite-order. To obtain finite-order polynomial transfer functions, the exponential function is usually replaced with first order pole or Padè approximations. These models provide inaccurate results when the bandwidth of the current loop is comparable to the delay time. Inaccuracy also results from a continuous-time representation of the discrete-time PI controller. This paper proposes a discrete-time domain based modelling approach to derive equivalent continuous-time domain transfer functions, which are accurately represented in terms of poles and zeros. These two transfer functions corresponding to conventionally designed PI controller parameters are shown to be dominated by a faster complex-conjugate pole pair and a slower real pole, respectively. Closed-form expressions of the time-domain current responses to step changes in the reference and disturbance are derived in terms of PI controller parameters. The analytical expressions are shown to be accurately estimating the current responses of a synchronous boost converter, obtained through simulations and experiments. © 2022 IEEE

Item Type:	Conference Proceedings
Publication:	PESGRE 2022 - IEEE International Conference on "Power Electronics, Smart Grid, and Renewable Energy"
Publisher:	Institute of Electrical and Electronics Engineers Inc.
Additional Information:	The copyright for this article belongs to Institute of Electrical and Electronics Engineers Inc.
Keywords:	Bandwidth; Continuous time systems; Controllers; DC-DC converters; Disturbance rejection; Exponential functions; Poles; Pulse width modulation; Two term control systems; Z transforms, Current loop; High bandwidth; Matched Z-transform method; PI controller parameters; Proportional-integral control; Pulse-width modulated converter; PWM converter; PWM drive; Time domain; Z-transform methods, Transfer functions
Department/Centre:	Division of Electrical Sciences > Electrical Engineering
Date Deposited:	19 May 2022 05:25
Last Modified:	19 May 2022 05:25
URI:	https://eprints.iisc.ac.in/id/eprint/71869

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