This is a summary from the presentation by the same title by Chris Botting, Manager of Research Engineering at Delta-Q Technologies, at the Future of Electrification 2023 conference. Watch the full session here:
Battery charging technology is a crucial underpinning of our modern electrified world, and we’ve witnessed significant evolutions over the past decades.
A Glimpse into the Past (1960s-1990s)
Between the ‘60s and ‘90s, battery and charging technology remained somewhat dormant. Chargers of this era predominantly showcased:
- Ferroresonant or SCR-based technology
- Operation at a line frequency of 50 or 60 hertz
- A hefty construction consisting of many kilograms of steel and copper
These chargers had notable drawbacks. They were unsealed, inefficient, and bulky—ill-suited for onboard applications.
Into the New Millennium (2000s Onwards)
Delta Q Technologies, leading from the front in high-frequency, switch-mode power supplies, introduced its first product: The QuiQ Series chargers. This brought a marked improvement in efficiency:
- 1000x frequency boost from 60 hertz to 60 kilohertz
- 30x smaller, lighter transformers
- Approximately 50% reduction in charger efficiency losses
Other innovations included the charger's sealed design and the integration of modern microprocessor control to customize and optimize the battery charge algorithm.
By the 2010s, Design for Manufacturing (DFM) principles came into play, reshaping the packaging of charging technology. The IC650 charger from Delta-Q Technologies, launched in 2013, once again illustrated this shift—being the first industrial charger sealed in a die-cast aluminum enclosure for resilience to mechanical shock, drop, and vibration.
The Lithium-Ion Revolution
Lithium-ion batteries have undeniably redefined the charging landscape, overshadowing traditional lead-acid batteries. Their advantages are manifold:
- Energy density – Modern lithium-ion packs for electric vehicles offer an impressive 450 Wh/L. In contrast, lead-acid batteries provide only 70 Wh/L. This represents a 500% increase in energy density for lithium-ion batteries, and the trend continues upward.
- Cost-efficiency – The average cost of lithium-ion battery packs has seen a steady decline, moving from $1,000/kWhr in 2011 to $150/kWhr in 2022. Even with stalling growth due to supply chain challenges since 2020, they are on track to achieve cost parity with lead-acid.
- Charging capabilities – Lithium promises faster, more efficient charging cycles. Unlike lead-acid batteries, which require extended charging periods (4-8 hours minimum) and risk capacity loss if not fully charged, lithium batteries can achieve full charges in under an hour.
This paradigm shift in battery technology also translated into new challenges and avenues for charger manufacturers. With the elimination of charge acceptance as a bottleneck, the focus has now pivoted back to optimizing chargers themselves.
Overcoming Modern Charging Challenges
The advancement in battery technology has created a need for equally advanced charging solutions. Key challenges include:
- AC supply – Power requirements determine plug-in points. For higher power needs, beyond conventional residential outlets, industrial plugs or even 3-phase power become imperative.
- DC current – Issues like conduction loss, resistance, and heating risks pose challenges. One solution lies in increasing the DC voltage rather than relying on the diminished returns of increased cooling or expensive copper.
- Onboard charger size – Industry demand for compact yet powerful chargers emphasizes the need for increasing power density.
Addressing the challenges in modern battery charging technology necessitates innovative and pragmatic solutions. To navigate these bottlenecks, several strategies have emerged at the forefront:
- Increasing energy efficiency – A pivotal step towards sustainable charging solutions, improving energy efficiency ensures that chargers are consuming and delivering power in the most effective manner, minimizing waste.
- Utilizing soft switching – Soft switching reduces the energy losses and electromagnetic interference usually associated with hard switching. This change can greatly enhance the performance and efficiency of charging systems.
- Replacing or removing diodes for better AC-DC rectification – Diodes, although fundamental in traditional charging circuits, introduce losses. By replacing or eliminating them, possibly using methods like bridgeless totem-pole PFC, we can more efficiently deliver rectified current.
- Incorporating GaN and SiC for faster switching – Gallium Nitride (GaN) and Silicon Carbide (SiC) are materials that allow for quicker and lower-loss switching in power electronic devices. By integrating them into charging systems, we can shrink passive components and cooling systems, enhancing power density.
- Leveraging cooling techniques – Efficient cooling, be it passive, fan-based, or liquid cooling, ensures charger components operate within optimal temperature ranges. This improves efficiency and enhances the longevity of the device.
- Opting for denser construction methodologies – Efficiently utilizing space in charger designs, both horizontally and vertically, can achieve greater power density without increasing the physical size of the charger. Denser construction, however, demands meticulous design to ensure components remain shielded and insulated.
- Integrating systems to minimize internal components – Embracing integrated designs can reduce the internal complexities of chargers. Solutions like DC fast charging stations are stellar examples—a hybrid approach that combines onboard and offboard charging capabilities.
As the industry evolves, these tactics will likely serve as the foundation upon which the next generation of charging solutions is built.
Key Takeaways
From relative stagnancy in the 1960s to our current electrified era, battery charging technology has undergone significant innovation. Lithium-ion batteries have set new benchmarks in terms of energy density, cost-efficiency, and charging capabilities—shifting the emphasis to optimizing the charger’s performance.
Addressing modern charging challenges means exploring avenues like increasing energy efficiency, soft switching, integrating advanced materials like GaN and SiC, and refining construction methodologies.
This holistic approach, comprising system integration and innovative strategies, will shape the trajectory of future charging solutions, ensuring they are robust, efficient, and aligned with industry demands.