Challenges of Designing Electric Mining Vehicles’ Power Electronics

Challenges of Designing Electric Mining Vehicles’ Power Electronics

• Explosion protection, extreme torque, difficult terrains, and high power pose a new challenge for off-highway vehicle manufacturers, and China is one step ahead of the West.

• HummingbirdEV manufactures heavy-duty EV power for Keshi Group’s mining vehicles in China, read this interview with the co-founder Vinay Jayachand to hear about their challenges along the way.

Can you give us an introduction to HummingbirdEV?

HummingbirdEV started in 2015, aiming to vertically integrate powertrain components for medium and heavy-duty OEMs. Our first customer was in the mining industry, which posed a unique set of challenges, for example:

Challenge #1 – Mining vehicles are very diverse. People movers, dump trucks, excavators, etc. all have varying requirements and functions. Within the vehicle types, they branch out with even more diversity. Some people movers may have 5 seats, some with 16, load carriers can range from 5-12 tons, etc. There are several vehicles in a mining operation with varying gross vehicle weight (GVW) and payload capacities. 

The goal was to develop a modular architecture that allows the reuse of components in both low and high-class vehicles to save cost. 

Challenge #2 – The power required is nothing like passenger vehicles. They have astronomical power take-off (PTO) needs, a wide range of peak power, and operate with hydraulic power. For instance, a 9 or 12-ton load carrier has peak power levels around 250-300 kilowatts, and they need to operate between 12-18 hours. That’s pretty high utilization, unlike a passenger car which is frequently idle.

It’s integral to understand how long they need to operate, at what power levels, etc., and design the powertrain accordingly, along with accompanying infrastructure.

Challenge #3 – They need to be safe and outperform their diesel counterparts. China, so far the world leader in mining electrification, has strict requirements on vehicles such as explosion protection. 

Years ago, the performance of our prototype systems caught the attention of Chinese off-highway manufacturer Keshi Group, and today our power electronics are in about 400-500 Keshi vehicles in Chinese mines. 

How did this relationship begin? 

Initially, we were retrofitting Keshi Group combustion chassis designs by integrating packs, motors, transmissions, etc. The traction by itself was fine, but when it came to auxiliary power, you ran into issues when switching from a belt-driven system to an electric one, so we tore it down to begin a ground-up electric design. 

We developed inverters, bi-directional chargers, power distribution units, etc., with accompanying software. Keshi handles its battery module sourcing, cell-to-pack battery packaging, electric motor design, and integration into explosion-proof enclosures. Regulations prevent you from putting the electronics and cells together in one compartment, so we worked closely with them for the competent placement of the powertrain components as well. 

HummingbirdEV provides AC charging stations, compatible with both single and three-phase power. Along with our onboard charger, we can provide up to 40-60 kilowatts of charging power from the grid. Mining operators tend to have a mixture of DC and AC chargers on-site, depending on the level of infrastructure investment they prefer.

What are some of the advantages for mine operators to go electric?

Companies are just now waking up to the several potential benefits, a lot of which we’ve learned from China. 

Protection: 

Diesel emissions are harmful to the environment, of course, but they’re even worse in a closed-off environment such as deep inside a mine. It’s a health hazard for the workers, and electrification can eliminate this. 

Drive cycles and cost:

These machines are high-torque, low-speed, very repeatable, and predictable, which is a perfect fit for electrification. 

Diesel prices fluctuate, adding unknown cost variables to the operation. Grid energy costs tend to be more stable, and you can even offset that if you implement solar panels and bi-directional charging. 

Lastly, combustion engines are full of moving parts, which equates to more machine servicing. Electric powertrains have much fewer moving pieces and tend to have a longer operating life requiring less maintenance. 

Economically, it makes sense to go electric. 

What does that initial deployment look like? I imagine a big switch isn’t easy…

The initial deployments are always the most challenging, everybody has upskilling to do, which is difficult. 

The operators need to educate workers on how electric powertrains function. For instance, the power is completely different, and previous high-voltage systems took up to 30 seconds to start, while diesel systems started instantly.  

Keshi recognized this early on, and they offer services with the vehicles for staff training. They deploy Keshi drivers on-site who teach operators about fault code reporting, how the battery systems work, how the inverters work, what to do when things go wrong, what to expect, etc. This has helped smooth things out, and they’ve found once the staff becomes knowledgeable, they wake up to the EV advantages. The feedback has been excellent so far, and it’s quickly spreading.

How long until you think we’re all electric in North America?

The market is getting aggressive, you have all of the main players in North America pushing for electrification in all aspects of off-highway, and I think by 2035, or worst case scenario 2050 we’ll have fully electric mining operations.  

Special thanks to Vinay Jayachand

The post Challenges of Designing Electric Mining Vehicles’ Power Electronics first appeared on EV Tech Insider.