digital power conversion basics: from analog to digital

Digital power conversion basics: from analog to digital control XMCTM microcontrollers May 2016

Agenda

Why digital control in power conversion?

What to expect when moving from analog to digital control

Basics of digital control

XMC™ power conversion peripherals

Development steps vs. XMC™ support

Development tools and software

General information

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2 Copyright © Infineon Technologies AG 2016. All rights reserved.

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Digital control is a natural evolution

Evolution


*(Source: Freepik)

*

Benefits of digital control

› Implement and protect your own IP from read access

› Embedded HW protections in case of SW fault

› Housekeeping: diagnostics, metering & reporting

› Remote SW update

› Remote controllable, i.e. diming

Security Communications

Adaptability Advance control

› Adaptive control

› Multimode operation: CCM, DCM

› Auto calibration

› Non lineal control

› System linearization

› Allow full performance by tuning SW to specific design

› Programmable operation limits

› Scalable to different designs

› Programmable fault handling


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What to expect when moving from analog to digital control?

Don’t panic! XMCTM ecosystem will provide you with what you

need!

The major problem that digital control has is:

freedom!

Together with freedom comes:

responsibility!


I heard I can do anything!?

*(Source: Pixabay)

*

*

What to expect when moving from analog to digital control?

XMCTM + SW example +

demo board

Empty µC (without SW)

Extra steps Extra steps

› Design control algorithms › Adapt SW parameters for new design

› Resources assignment: pins, PWM, ADC…

› Code algorithms

› Debug

XMCTM


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Simple PI regulator: Analog vs. digital

Feedback pin

ADC PWM unit

Calculate error

PI regulator feedback

pin

PWM

pin

Reference pin

HW

Reference

SW HW

PWM

pin


Digital PI regulator in C code

Calculate error

PI regulator

reference

SW

Digitalized

feedback

Digital

PI_output

error = reference - feedback; PI_storage = (error * PI_ki) + PI_storage_1; PI_storage_1 = PI_storage; PI_output = (error * PI_kp) + PI_storage;

PI_ki PI_kp

Where are the

PI parameters?

Vs.


The impact of the execution time

Measured inputs

Calculate error

Calculate required output

Update output

Execute

Execution time

› Execution time add a delay to the control loop

› Due to execution time we may not be able to “regulate” the system every switching cycle

› The faster the CPU the faster we can close the loop

› Executing the control loop faster than switching frequency may not help


Fix point vs. floating point

Floating point Fix point

› More expensive HW (or slow execution)

› Cheaper HW › Do not need variables scaling

› Danger of operations overflow

› Low overflow risk

› May required scaling factors

› Faster execution (in general)

› Type conversion to access HW registers

› Easy coding and easy to understand

› Higher code reusability


XMCTM examples SW architecture

HW

XMCTM peripherals

Hardware access layer (HAL)

Control loop

APIs

Options

› Low level drivers

› DAVE™ APPs (based on LLDs)

› Custom

› Combination of previous


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How key peripherals help? CPU usage

PWM unit › Frequency › Duty cycle

Pin

› Peripherals are state machines which can run independently and interact with the CPU or with other peripherals

While(1) { signal_high= 100; while (signal_high--); set_pin_low(); signal_low= 200; while (signal_low--); set_pin_high(); }

Vs.

› Block CPU

› It is unprecise

› Precise

› CPU is free


Key peripherals

Peripherals for power conversion applications

Highlights

Analog front end together with full configurability allows most advanced power supply control

With the support of ARM® Cortex® cores and high resolution PWM (150 ps), accurate and fast control loops execution are possible for improved figure of merits in power supply design

Customer benefits Key feature

VADC ACMP ERU

HRPWM

CSG

CCU8/4

› High resolution PWM (150 ps) › Regulate voltages/current with higher

accuracy

› Smart analog comparators › Analog comparators with smart features

such as slope compensation

› Fast and flexible ADC and timers › Permit complex PWM patterns and

sophisticated measure sequences


1.8 V+/- 65 mV

Vout

PWM Stepwidth 12.5 ns

Stepwidth 150ps

Higher accuracy Better control

stability

1.8 V +/- 35 mV

Key peripheral example 1: High Resolution PWM


Key peripheral example 2: Smart analog comparators

› XMC4000 comparators include filtering, blanking and clamping capabilities as well as a DAC for automatic reference or slope generation

› XMC1000 comparators can configure hysteresis and output filtering


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Development flow vs. Infineon support

XMCTM pinout

uC-Probe

Imple

menta

tion

concept

HW SW

specs

APPs / LLDs

System specification

Converter topology

Control concept

HW / SW function split

Parts selection

Schematic design

Board design

Test / debugging

Coding

resource assignment

SW architecture

Dem

o

board

s D

AVE™

Application n

ote

s

Code

exam

ple


Shorten your development time

Want to reuse SW from a running system?

Which entry point do your target?

Want to code your own control loop?

Want to configure MCU peripherals?

System concept

XMCTM peripherals

Hardware access layer (HAL)

Control loop

APIs

HW

Reuse Reuse Reuse


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Development tools and software DAVE™– software development made easy


Development tool and software

› DAVETM – Free development platform for code generation

– Eclipse IDE

– Compiler

– Debugger

– Application library and examples

– Software can be used with 3rd party tools

› For download and support:

DAVETM website


http://www.infineon.com/cms/en/product/promopages/aim-mc/DAVE_3_Download.html

http://www.infineon.com/dave




µC/Probe™: Read/write your data on the fly without code modification!

› PFC example GUI:

www.infineon.com/ucProbeXMC

* Digital scope functionality requires adding of debug code


http://www.infineon.com/ucProbeXMC

XMC™ Flasher

› Easy code download to your XMCTM


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Support material:

› Product Briefs

› Selection Guides

› Application Brochures

› Presentations

› Press Releases, Ads

› Application Notes

› Technical Articles

› Simulation Models

› Datasheets, MCDS Files

› PCB Design Data

› Technical Videos

› Product Information

Videos

› Forums

› Product Support

Collaterals and

Brochures

Technical Material

Videos

Contact

› www.infineon.com/XMC

› www.infineon.com/XMC

› Kits and Boards

› DAVETM

› Software and Tool Ecosystem

› Infineon Media Center

› XMC Mediathek

› Infineon Forums

› Technical Assistance Center (TAC)


http://www.infineon.com/XMC

http://www.infineon.com/XMC

http://www.infineon.com/cms/en/product/microcontroller/32-bit-industrial-microcontroller-based-on-arm-registered-cortex-registered-m/32-bit-xmc1000-industrial-microcontroller-arm-registered-cortex-registered-m0/xmc-development-tools-kits-and-boards/channel.html?channel=db3a30433d5e5530013d64397b0c2043

http://www.infineon.com/cms/en/product/microcontroller/32-bit-industrial-microcontroller-based-on-arm-registered-cortex-registered-m/32-bit-xmc1000-industrial-microcontroller-arm-registered-cortex-registered-m0/dave-version-4-free-development-platform-for-code-generation/channel.html?channel=5546d46145f1f3a4014619e925171bcc

http://www.infineon.com/cms/en/product/microcontroller/32-bit-industrial-microcontroller-based-on-arm-registered-cortex-registered-m/32-bit-xmc1000-industrial-microcontroller-arm-registered-cortex-registered-m0/dave-version-4-free-development-platform-for-code-generation/channel.html?channel=5546d46145f1f3a4014619e925171bcc

http://www.infineon.com/cms/en/product/microcontroller/32-bit-industrial-microcontroller-based-on-arm-registered-cortex-registered-m/32-bit-xmc1000-industrial-microcontroller-arm-registered-cortex-registered-m0/xmc-development-tools-software-tools-and-partner/channel.html?channel=5546d46145f1f3a4014619e9bcfa1bcd

http://www.infineon.com/mediacenter

http://www.infineon.com/mediacenter

http://www.infineon.com/cms/media/Applications/microcontrollers/XMC/Mediathek.html

http://www.infineon.com/cms/media/Applications/microcontrollers/XMC/Mediathek.html

http://www.infineonforums.com/

http://www.infineon.com/cms/en/about-infineon/company/contacts/product-support-form/




Glossary abbreviations

› VADC Versatile Analog Digital Converter

› CCU Capture Compare Unit

› ACMP Analog Comparator

› PWM Pulse Width Modulation

› HRPWM High Resolution Pulse Width Modulation

› DAVE™ Free development IDE for XMC

› CSG Comparator & Slow Generator

› ERU Event Request Unit

› PFC Power Factor Correction


Disclaimer

The information given in this training materials is given as a hint for the implementation of the Infineon Technologies component only and shall not be regarded as any description or warranty of a certain functionality, condition or quality of the Infineon Technologies component.

Infineon Technologies hereby disclaims any and all warranties and liabilities of any kind (including without limitation warranties of non-infringement of intellectual property rights of any third party) with respect to any and all information given in this training material.

The images were designed by Freepik and Pixabay, see footer.

digital power conversion basics: from analog to digital

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