high bandwidth automotive power supply for low-cost pwm audio amplifiers mikkel c. w. høyerby...
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![Page 1: High Bandwidth Automotive Power Supply for Low-cost PWM Audio Amplifiers Mikkel C. W. Høyerby (Ørsted·DTU) Dennis R. Andersen (Bang & Olufsen ICEpower](https://reader035.vdocuments.site/reader035/viewer/2022062719/56649ee55503460f94bf408a/html5/thumbnails/1.jpg)
High Bandwidth Automotive Power Supply for Low-cost PWM Audio
Amplifiers
Mikkel C. W. Høyerby (Ørsted·DTU)
Dennis R. Andersen (Bang & Olufsen ICEpower a/s)
Michael A. E. Andersen (Ørsted·DTU)
Lars Petersen (Bang & Olufsen ICEpower a/s)
![Page 2: High Bandwidth Automotive Power Supply for Low-cost PWM Audio Amplifiers Mikkel C. W. Høyerby (Ørsted·DTU) Dennis R. Andersen (Bang & Olufsen ICEpower](https://reader035.vdocuments.site/reader035/viewer/2022062719/56649ee55503460f94bf408a/html5/thumbnails/2.jpg)
High Bandwidth Automotive Power Supply for Low-cost PWM Audio
Amplifiers
• Reduction of switching amplifier output EMI • Reduction of switching amplifier idle losses • Requires high bandwidth and dv/dt• Tracking supply for PWM SE amplifiers is new ground
![Page 3: High Bandwidth Automotive Power Supply for Low-cost PWM Audio Amplifiers Mikkel C. W. Høyerby (Ørsted·DTU) Dennis R. Andersen (Bang & Olufsen ICEpower](https://reader035.vdocuments.site/reader035/viewer/2022062719/56649ee55503460f94bf408a/html5/thumbnails/3.jpg)
”Supply pumping”
• Switching SE amplifier transfers power between rails• Tracking converter must have bidirectional outputs in
addition to high bandwidth!• SE amplifier still desirable in multi-channel system
due to low cost
![Page 4: High Bandwidth Automotive Power Supply for Low-cost PWM Audio Amplifiers Mikkel C. W. Høyerby (Ørsted·DTU) Dennis R. Andersen (Bang & Olufsen ICEpower](https://reader035.vdocuments.site/reader035/viewer/2022062719/56649ee55503460f94bf408a/html5/thumbnails/4.jpg)
Suitable topology
• No single stage solution found suitable• Energy storage is cheaper than energy transfer when
dealing with ”supply pumping” in the buck topology
![Page 5: High Bandwidth Automotive Power Supply for Low-cost PWM Audio Amplifiers Mikkel C. W. Høyerby (Ørsted·DTU) Dennis R. Andersen (Bang & Olufsen ICEpower](https://reader035.vdocuments.site/reader035/viewer/2022062719/56649ee55503460f94bf408a/html5/thumbnails/5.jpg)
Current measurement vs. estimation
• High control bandwidth requires current feedback• Short-circuit protection not essential• Current estimation eliminates noise problems• DC information is not available with current
estimation => Current loop transfer function is altered
Standard current measurement Employed estimation technique
![Page 6: High Bandwidth Automotive Power Supply for Low-cost PWM Audio Amplifiers Mikkel C. W. Høyerby (Ørsted·DTU) Dennis R. Andersen (Bang & Olufsen ICEpower](https://reader035.vdocuments.site/reader035/viewer/2022062719/56649ee55503460f94bf408a/html5/thumbnails/6.jpg)
Effect of employing current estimation
• Dominant pole movement caused by load variation is restricted when LF cutoff is introduced in current loop
• Reducing current loop gain at output filter cutoff frequency causes increased influence of filter Q on closed loop transfer function
Low current loop LF cutoff frequency Higher current loop LF cutoff frequency
![Page 7: High Bandwidth Automotive Power Supply for Low-cost PWM Audio Amplifiers Mikkel C. W. Høyerby (Ørsted·DTU) Dennis R. Andersen (Bang & Olufsen ICEpower](https://reader035.vdocuments.site/reader035/viewer/2022062719/56649ee55503460f94bf408a/html5/thumbnails/7.jpg)
Control system achievements
• Inductor current signal is practically noiseless
• Closed-loop bandwidth is high• Controller is stable with any resistive load
Estimated inductor current
Actual inductor current
4Ω loadUnloaded
![Page 8: High Bandwidth Automotive Power Supply for Low-cost PWM Audio Amplifiers Mikkel C. W. Høyerby (Ørsted·DTU) Dennis R. Andersen (Bang & Olufsen ICEpower](https://reader035.vdocuments.site/reader035/viewer/2022062719/56649ee55503460f94bf408a/html5/thumbnails/8.jpg)
Conclusion
• Tracking PSU for single ended switching amplifiers is technically possible
• Tracking PSU with suitable topology has been prototyped
• Current estimation provides an alternative set of properties when compared to current measurement
The prototype tracking PSU