Slide 1: Managing high-voltage line ripple rejection using high bandwidth DC-DC
Managing high-voltage line ripple rejection using high bandwidth DC-DC Haris Muhedinovic EEHE, June 2023, Essen, Germany
Slide 2: Electric vehicle HV bus overview and inverter ripple
Electric vehicle HV bus overview and inverter ripple High voltage ripple occurs on high voltage bus during propulsion and regeneration as a result of inverter’s (PIM) operation Most of the ripple is filtered by inverter’s bulk capacitor but significant part is injected to HV bus and can cause issues
Slide 3: Impact of inverter ripple on DC-DC converter
Impact of inverter ripple on DC-DC converter n Component degradation: – DC-DC input filter capacitors are exposed to both DC-DC switching current and inverter ripple – Self-heating caused by (𝐼!"# $ 𝑅 %&' ) leads to component degradation n Ripple transfer to DC-DC output – DC-DC closed-loop…
Slide 4: Resonances: HVPM HVDC Filters
Resonances: HVPM HVDC Filters HVDC filters are designed to address EMI noise and not inverter ripple. If designed without taking inverter ripple into consideration, the filter can inadvertently be excited by inverter ripple
Slide 5: Ripple rejection – Example
Ripple rejection – Example HV Ripple: Frequency = 2kHz Magnitude = 19Vp-p Converter Voltage Ripple Magnitude: 0.7 Vp-p HV Ripple: Frequency = 4kHz Magnitude = 20Vp-p Converter Voltage Ripple Magnitude: 1.14 Vp-p HV Ripple: Frequency = 10kHz Magnitude = 23Vp-p Converter Voltage Ripple Magnitude: 1.7
Slide 6: Solutions to address inverter ripple
Solutions to address inverter ripple n Minimize inverter ripple on HV bus: – Modify drive profiles – Increase DC link capacitance – Implement “No-fly” zones to avoid exciting component resonances n Design converters which operate significantly higher above potential oscillations (ripple) on HV bus.
Slide 7: High frequency, soft switching DC-DC and impact on EMI filter
High frequency, soft switching DC-DC and impact on EMI filter n Increased power density n Minimized voltage and current ripple n Minimized EMI filtering effort n Closed loop control bandwidth extended
Slide 8: Example/filter design: Design steps
Example/filter design: Design steps 1. Select the cut-off frequency below the crossover frequency of the converter 2. Choose the inductor L based on maximum input current, calculate C based on equation or determine C based on voltage level and calculate L 3. Select appropriate filter network and cal
Slide 9: Filter comparison
Filter comparison 5kHz cut-off 25kHz cut-off
Slide 10: Filter Comparison – applying ripple voltage on HV input bus
Filter Comparison – applying ripple voltage on HV input bus 5kHz cut-off 25kHz cut-off
Slide 11: Filter output impedance
Filter output impedance In order to keep filter losses lower, output impedance of the high cut-off filter should be below output impedance of the low cut-off, until frequency of interest Lower impedance – lower losses, break even point 16kHz
Slide 12: Size comparison – for filters with equal power losses
Size comparison – for filters with equal power losses L1= 20 x L10 C4= 50 x C17 To keep losses equal and distributed ONLY EXAMPLE
Slide 13: Filter topology influence
Filter topology influence n Undamped filter Series damped might be – Risk of uncontrolled voltage amplification more attractive due to – Avoid inverter switching frequency lower current at high n Simplified damped voltage level. – Weak attenuation at higher frequencies Relative size ratio will n Ser
Slide 14: Vicor's DC-DC converter under HV ripple – time domain
Vicor’s DC-DC converter under HV ripple – time domain VIN = 700 + 20*sin(2*pi*2k*t)
Slide 15: Vicor's DC-DC converter under HV ripple – time domain
Vicor’s DC-DC converter under HV ripple – time domain VIN = 700 + 20*sin(2*pi*10k*t)
Slide 16: Vicor's DC-DC converter under HV ripple – time domain
Vicor’s DC-DC converter under HV ripple – time domain VIN = 700 + 20*sin(2*pi*17k*t)
Slide 17: Vicor's DC-DC converter under HV ripple – frequency response
Vicor’s DC-DC converter under HV ripple – frequency response
Slide 18: Conclusion
Conclusion Vicor DC-DC converter enables: n Highest power density conversion n Smallest EMI filter (high switching frequency and ZVS/ZCS topology) – Shifting frequency range n Reliable system and simplified architecture n High frequency enable higher closed loop bandwidth and rejects inverter ripple
Slide 19: Haris Muhedinovic
Haris Muhedinovic Principal Application Engineer hmuhedinovic@vicr.com +49 171 5647279 ©2023 Vicor 19
Slide 20: Thank you
Thank you Scan and download the presentation ©2023 Vicor 20