Time Domain Identification of PWM Converters for Digital Controllers Design

Fast power converters are desired in microprocessors, audio, and servomotor power supplies. Fixed-topology dc-dc converters have a minimum time in which to respond to line, load, and control change. This response depends on converter control, topology, and circuit parameters. Minimum-time control (MTC) considers these three items when it predicts postdisturbance steady-state points and directs capacitor voltage and inductor current in the shortest time. In this paper a nonlinear model-predictive control steers energy using geometrical curved control surfaces derived from piecewise linear (PWL) and bilinear models. The MTC differs from previous work on the topic in that it considers lossy com- ponents (a cause for nontriangular ripple) and is an open-form solution (as originally proposed by LaSalle in 1959). The different approach revealed a quantitative link between the needed control surface memory and state/parameter resolution. Results are generalized for two-state dc-dc converters and all parameter/controldisturbances. An unconventional digital method was devised to accommodate the open-form solutions. It involved a priori control surface calculations, A/D scaling, surface quantizing, and image compression. The final control executed no real-time arithmetic operations. MTC performance was compared with other pulsewidth modulation controls and time-optimal control in simulations, and tests were performed in hardware using synchronous buck and boost converters.

Section: Hardware and Simulated Experimentsmentioning

confidence: 99%

Minimum-Time Transient Recovery for DC–DC Converters Using Raster Control Surfaces

Pitel

Krein

2009

“…Typically, Fourier transform methods are then applied to find the frequency response of the system. Unfortunately, the identification process can take significant amounts of time to complete and may need to process long data sequences [2]. In addition, during the identification process, the system operates in open loop without regulation [10].…”

Section: System Identification Methodsmentioning

confidence: 99%

“…Therefore, it is more suited to offline scenarios. Peretz and Bin-Yaakov [2] also propose an offline system identification approach to determine an open-loop, time-domain model of a dc-dc converter. The iterative least square minimization approach (Steiglitz and McBride method) is used to estimate system parameters and then to design the digital controller directly by the Ragazzini method [18], [19].…”

Section: System Identification Methodsmentioning

confidence: 99%

Active Online System Identification of Switch Mode DC–DC Power Converter Based on Efficient Recursive DCD-IIR Adaptive Filter

Al‐Greer

Armstrong

Giaouris

2012

This paper introduces a novel technique for online system identification. Specific attention is given to the parameter estimation of dc-dc switched-mode power converters; however, the proposed method can be applied to many alternative applications where efficient and accurate parameter estimation is required. The proposed technique is computationally efficient, based on a dichotomous coordinate descent algorithm, and uses an infinite impulse response adaptive filter as the plant model. The system identification technique reduces the computational complexity of existing recursive least squares algorithms. Importantly, the proposed method is also able to identify the parameters quickly and accurately, thus offering an efficient hardware solution that is well suited to real-time applications. Simulation analysis and validation based on experimental data obtained from a prototype synchronous dc-dc buck converter is presented. Results clearly demonstrate that the estimated parameters of the dc-dc converter are a very close match to those of the experimental system. The approach can be directly embedded into adaptive and self-tuning digital controllers to improve the control performance of a wide range of industrial and commercial applications.Index Terms-Adaptive filter, dichotomous coordinate descent (DCD), infinite impulse response (IIR) adaptive filter, recursive least squares (RLS), switch mode dc-dc power converter, system identification.

“…The small-signal open-loop response of the converter A(z) can be obtained by either theoretical calculations [12], [13], prediction, or by experimental parameters extraction procedure such as system identification [14]- [16].…”

Section: Time-domain Compensator Design Methodsmentioning

confidence: 99%

Time-Domain Design of Digital Compensators for PWM DC-DC Converters

Peretz

Ben‐Yaakov

2012

Self Cite

Abstract-A time-domain design method for the digital controller of pulsewidth modulation dc-dc converters was developed. The proposed approach is based on the fact that the closed-loop response of a digitally controlled system is largely determined by the first few samples of the compensator. This concept is used to fit a digital PID template to the desired response. The proposed controller design method is carried out in the time domain and, thus, bypasses errors related to the transformation from the continuous to discrete domain and to discretization. The method was tested by simulations and experimentally. Digital PID controllers for experimental buck-and boost-type converters were designed according to the proposed method and implemented on a TMS320LF2407 DSP core. The measured closed-loop attributes were found to be in good agreement with the design goals. The study was further expanded to investigate the possible realistic closed-loop performance that can be obtained from a system that is controlled by a PID template controller, as well as the stability boundaries of the proposed time-domain controller design approach. The results of the study delineate a normalized map of deviation from the target closed-loop performance goals possible for PID control of switchmode converters and the areas in which the use of this control law is feasible.