1. Power PSoC 110: Power Converter Efficiency Analysis

2. Section 1: Introduction Course Outline Section 2: Circuit Parasitics and Loss Mechanisms Section 3: Steady State Solutions Section 4: Improving Efficiency in Converters

3. Course Objectives At the end of this course, you should be able to: Understand how to minimize the effects of such mechanisms Understand power loss mechanism in power converters Understand how power converter transfer functions vary when non-idealities in circuit parameters are introduced Explain the methods to improve efficiency in power converters

4. 1 Introduction

5. Efficiency - Fundamental Characteristic of a Power Converter Power loss – Intrinsic Nature Non-idealities prevent us from attaining 100% efficient power conversion Maximize efficiency Introduction

6. Power Converter Circuit Elements 2 Circuit Parasitics and Loss Mechanisms

7. P CONDmosfet = I MOSFETon(avg) 2 x R DSon x D P CONDdiode = I DIODEon(avg) x V D x (1-D) Power Losses in Converters V OUT = D x V IN I IN = D x I OU T

8. P SWmosfet = 0.5 x V D x I D x (t SWon + t SWoff ) x f s P SWdiode = 0.5 x V REVERSE x I RRpeak x t RR2 x f s Power Losses in Converters

9. P CONDinductor = I OUT(avg) 2 x R DCR P CONDcapacitor = I C(avg) 2 x R ESR Power Losses in Converters

10. Operating Principle 3 Steady State Solutions

11. MOSFET ON MOSFET OFF Steady State Equations

12. v L (t) = V IN – i L (t)R DCR – i MOSFET (t)R ON –v out (t) Using small ripple approximation, v L (t) = V IN – I OUT R DCR – I OUT R ON – V OUT Steady State Equations

13. v L (t) = – i L (t)R DCR – i D (t)R D – v out (t) -V D Using small ripple approximation, v L (t) = -V OUT – I OUT R DCR – I OUT R D – V D Steady State Equations

14. V OUT = DV IN – (D'V D + D' I OUT R D + I OUT R L + DI OUT R ON ) Using inductor volt-sec balance, average inductor voltage =0 = when MOSFET is on + when MOSFET is off = D v L (t) –D' v L (t) =0 D = T ON /T S ; D’=1-D=1-(T ON /T S )=T OFF /T S T ON :time when MOSFET is on T OFF :time when MOSFET is off T S =T ON +T OFF Steady State Equations

15. 4 Improving Efficiency in Converters

16. Improving Efficiency

17. Course Summary Discussed the concept of efficiency and power loss in power converters Understood how to minimize the effects of such mechanisms Showed how circuit transfer function is affected due to power loss causing factors Explained how to over come the non-idealities of circuit components and improve efficiency in converters

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