Energy System Group University of Toronto

1. Laboratory for Low-Power Management and Integrated SMPS Power Stage Parameter Estimation and Digital Controller Design for SMPS with the Use of Limit Cycle OscillationZhenyu Zhao, Aleksandar Prodic Energy System Group University of Toronto

2. Laboratory for Low-Power Management and Integrated SMPS • Fast design & programming flexibility in digitally controlled SMPS • Controller auto-tuning Project Introduction

3. Laboratory for Low-Power Management and Integrated SMPS Limit-Cycle Oscillations (LCO) in SMPS • Reason for LCO in SMPS • Resolution mismatch of two quantizers • analog-to-digital converter (ADC) • digital pulse width modulator (DPWM)

4. Laboratory for Low-Power Management and Integrated SMPS Limit-Cycle Oscillations (LCO) in SMPS • System parameters can be extracted from LCO features • LCO Features: amplitude, frequency etc. • System parameters: load, output capacitance, input voltage and inductance etc. • Practical implementation • Look-up tables

5. Laboratory for Low-Power Management and Integrated SMPS Construction of Look-up tables from relationship Diagram (1) LCO Amplitude LCO Frequency R C R C

6. Laboratory for Low-Power Management and Integrated SMPS Experimental vs Theoretical (1) LCO Frequency LCO Amplitude R R

7. Laboratory for Low-Power Management and Integrated SMPS Experimental results • Output voltage during auto-tuning upon sudden change of output capacitance

8. Laboratory for Low-Power Management and Integrated SMPS Bandwidth Controlled PID Auto-tuning for SMPS • Two test phases to meet bandwidth requirements • Tuning PID zeros • Tuning PID gain

9. Laboratory for Low-Power Management and Integrated SMPS Conclusions • A new digital system that allows introduction of auto-tuning in low-power dc-dc switching converters is presented. • System parameters are identified using information of limit cycle oscillations that is intentionally introduced. • Effective auto-tuning of PID controller provides fast control over a large range of system parameters.