Lynfel Owen is Land Rover’s vehicle engineering senior manager in charge of the Range Rover and Range Rover Sport plug-in hybrid (PHEV). We asked him to describe how the complex system works and what the future holds for electrified Land Rovers and four-wheel drive.
Autoweek: Are there differences between in the calibration of the Range Rover PHEV system and the one in the Range Rover Sport PHEV?
Owen: The hardware is obviously very similar. But the tuning is different. If you are in the Range Rover Sport PHEV, and you’ve selected dynamic mode, sport in the transmission and turned traction control off, you are telling the car you want it set up for optimum performance. There’s a sweet spot in the battery for getting power in and out quickly — we use that window of charge and we make sure you have full power when you need it. And as soon as you lift off the throttle, we’re using heavy regen to top off that battery more quickly.
Autoweek: How is the electric motor integrated with the transmission?
Owen: The electric motor is installed where the torque converter would normally be in the bell housing. So, you’ve got the motor and the primary clutch at the front of the gearbox. Then you’ve got the eight-speed gearset behind it and then the second clutch. It’s the two clutches that allow you to have the EV drive, combined drive or solely engine propulsion. The rear driveshaft is common between the PHEV and non-PHEV Range Rover. And that was really important because we wanted to have an EV with a low range. This configuration allows us to use the common low range transfer case with the gas and diesel Range Rover.
Autoweek: Do you buy the transmission and electric componentry directly from ZF?
Autoweek: What are the advantages of using a hybrid system like the one you’ve chosen for the Range Rover PHEV?
Owen: When we designed the aluminum architecture for Range Rover and Range Rover Sport, we knew we wanted to electrify it. So, that’s what really drove us, having the common hard point to engine with the gas and diesel Range Rovers. We wanted to use that integrated technology in a gearbox because we really didn’t want to repackage the powertrain elsewhere. It was also very important, from a complexity point of view, to maintain the suspension articulation and all the off-road performance. We really didn’t want to redesign all of that for a different solution.
Autoweek: Who makes the battery pack for you?
Owen: So, this battery pack is a collaboration with Samsung. We designed elements of it, and it’s their cell technology. The battery case itself is an aluminum casting. And that was quite important. Having the aluminum casting allows us to quite efficiently package all the cells. And it fits underneath the cargo floor.
Autoweek: How quickly can the Range Rover PHEV charge?
Owen: There are a range of charging options, but it takes 2 hours, 45 minutes from a quick charge. We provide the 110V home charge kit standard with the car. But at the dealer they’ll have a choice of charging options. And for each market, we have a partner with one of the major charging suppliers who will talk to the customers in parallel about whether they’d like to have a home installation or any other options. The vehicle has a 7-kW on-board charger so it’s capable of any supply.
Autoweek: How did you arrive at the size of the battery pack?
Owen: Sizing the battery is definitely an art in itself. It’s a balance of fuel range, electric range and overall vehicle weight. We looked at data that said what we expected people would want to do with the vehicle — what would be a reasonable range that people would want and then worked back from that.
Autoweek: Land Rover has diesel expertise. And it has diesel hybrid expertise. A diesel power source could make an interesting complement to a plug-in hybrid and increase efficiency. Did you look at a diesel, specifically the 2.0-liter diesel in the XE as an option?
Owen: We learned a lot from our previous hybrid program in terms of diesel. (Land Rover sells the SDV6, a V6-powered diesel hybrid Range Rover in markets outside the U.S.) We realized there are some big advantages in going with the gasoline engine. The CO2 output, as well as the integration and character of the car, fit better with the gasoline engine. Four-cylinder turbocharged engines are excellent at delivering refined performance at low speed. And you get the benefits of turbocharging when you work that engine harder too. So, the gas four-cylinder gives you that duality of performance. And that really complements a PHEV powertrain. The maximum torque of a diesel is at very low revs. But with a turbo gas engine, combined with the electric drive, we have a wider spread of torque. That combination of factors made it the right choice.
AW: How Did you calibrate the EV mode for off-road driving?
Owen: So, in terms of the Terrain Response system for 2018, we’ve made a lot of improvements and simplified a lot of the modes. For Range Rover, we’ve added a comfort mode and dynamic mode as bookends. And then we’ve looked at each of the terrain response modes and decided what the most appropriate powertrain calibration is for each one. For example, mud and ruts mode is a good off-road setting to use EV mode because you’re picking your way through the trail more quickly than rock crawl mode. It’s not ultra-slow and it’s not too fast — that’s where the electric mode comes into its own. We decided that grass, gravel, snow should also be available in EV mode, as well as comfort. Sand mode has its own challenges. It’s typically used in a hot environment where you have a high AC load, use a lot of power and there’s quite a bit of drag on the wheels. So, in a pure EV mode, you’d use a lot of battery power very quickly. We got the best performance in sand by tuning in both engine and electric power. In rock crawl, we found in testing that even though the torque was excellent for low-speed maneuvers in places like Moab, we again had better performance using both engine and electrics combined. Rock crawling tends to be a very long, slow and precise process. And we don’t want to use up the battery, get halfway down the trail and then have the engine kick in at some crucial moment and upset the chassis.
AW: Electrification has great potential as a power source for off-road vehicles. The systems could be completely sealed from mud and water — and provide nearly instant torque for slow-speed work. Do you think a pure electric powertrain would pair well with a future Defender model?
Owen: We are looking at all options. We want to show how capable this Range Rover PHEV is with electric drive in low range. I think it’s a really important step to say to people, you know you can do all the stuff you want to do in low range — in EV. That’s the message we want to get out now, this is really the first one. No one else has done a PHEV with low range. I’m a huge believer that you can enhance the off-road performance with electrification.