Automotive Cell Balancing and Safety

Advanced Multi Cell Balancing Solutions improve vehicle safety through unmatched cell and pack measurement accuracy and improved system communication and diagnostics.

Transcript

Niall Lyne: We have a new generation of devices at Intersil for multi-cell balancing. The primary device is the ISL78600. We also have some backup devices, one being the ISL78601. The cell balancing device, what it actually does in the vehicle is basically it monitors each of the cells within a pack. So, within a smaller vehicle, you can 96 cells, larger vehicles up to 160-190 cells. What you're doing with the device is monitoring the voltage across all the cells, the current, the temperature of the cells, actually the communications across the devices as well. The 601 device is just purely as a monitor as a backup device, as a backup safety system within the vehicles.

Tony Allen: One of the things we paid a lot of attention to when we were looking at the latest generation of cell balancing powers, is safety. So the ISL78600, for example, which is the current generation of our cell balancing part has lots of diagnostics capability built in. And what this is there to do is to always inform the user if there's any issue. And that could be an issue with measurement accuracy, it could be an issue with balancing operation, whatever it is. That there's a diagnostic function built in to cover just about any eventuality that you can get at system level.

Niall Lyne: One of the major benefits of having really good efficiency on a multi-cell balancing system, in our case, we have the best, the highest accuracy cell balancing device on the market. It monitors to an accuracy of 2.5mV. What that means to the consumer is, in a given range, or trip in a vehicle, you can get up to in excess of 10% better efficiency, i.e., instead of 100 miles, you get now 110 miles range. Also, what you gain by having a really well-balanced battery system, really high efficiency, is battery packs in vehicles today are warrantied up to 10 years. Not like, we'll say in laptops, where they're rated for 2 to 3 years. Due to the efficiency and the balancing of these devices, instead of just 10 years, now you can get 11 years, if it's 10% better efficiency.

Tony Allen: One of the biggest differentiators in this type of product is actually the communication system that's used. You'll have a battery module with a few cells. You'll have a balancing IC attached to that module. You'll have a microcontroller. And you'll have a CAN interface going back to a central control unit. The problem with that is it's expensive. If you look at what's happening in the market today, there's a big push towards a cheaper communication system. The ISL78600 actually uses a proprietary communication system that was developed by Intersil. It's a two-wire system that's fully bidirectional so we handle all the communications up and down the chain on these two wires. The importance of reducing wire count is both cost and reliability. Obviously, the fewer connections you have, the lower cost the system, also, the more reliable the system. The two-wire system that we have on the ISL78600 has been fully tested for EMC. It's extremely robust, it's fairly fast, it operates at 500kB per second and, it's been shown to operate over a long daisy chain length, very reliably.