Electrification Update


It’s been awhile since our last posts on Electrification – too long, actually, especially since we’ve been doing quite a bit of work in key electrification technologies.

If you’ve been to our site in the past, welcome back, and thanks for your patience!

If you’ve just landed here for the first time from one of our ads, thanks for the interest!

This post is the first in a series that we hope will be informative and useful to you, and perhaps give us a basis for further conversations about your Electrification goals.

We’d like to do three things

(1) First: we’d like to offer a brief review of Electrification’s role in Off-Highway power, particularly in the small (less than 50HP) product range. This market segment can benefit from reduced emissions, new vehicle features, etc. – all resulting from Electrification — as much as large machines do.

This video presentation addresses basic considerations of “Why Electrify” for smaller product market participants who are now considering a move to the technology. Even if none of this is new to you, please take a look – it’s a simple presentation (no headphones/speakers required).

(2) Second: we’ve been working on Electrifying the ZTR since 2014. Our technology and marketing efforts have taken us down some interesting paths as we’ve struggled to understand the needs of landscaping businesses. Electrification offers so many possibilities, not just in reduced fuel and emissions, but also in aspects ranging from operator comfort and safety to business metrics connectivity.

At the root of all these possibilities is that the system naturally combines system Intelligence (from the drive-by-wire integration) when the platform is Electrified.

So: Intelligent Electrification = IntElectTM . Fundamentally, Electrification really IS just a smart idea, not only for the ZTR but also many other platform applications, and the name stuck. Our short promotional video for the concept is here:

(3) Third: Here’s a brief summary – a “teaser”, really — of some of our ongoing Electrification work. We’ll follow up with more detailed posts soon.

Some of you may recall our Hybrid “Mule” project started way back in 2014. We adapted an existing 54-inch, hydrostatically-powered Husqvarna ZTR for the purpose, removing all belts, pulleys, clutches and hydraulic equipment to make it a true Series Hybrid. Here’s a picture of our General Manager George Kuczenski in the first drive of a “naked” machine under battery power.

We had a LOT of surgery to do – BTW: many thanks to Husqvarna for building such a robust platform that endured several plasma cuts in its evolution to a Hybrid!

But eventually we hit a wall. A great, well-packaged design for a rugged conventional hydrostatic ZTR isn’t easily repurposed to hybrid. Besides finding volume for motor controls, wiring, etc., we had to make a lot of compromises in our drivetrain configuration to fit. That led to less-than-optimal gear ratios and installation (see below):

[Adapting to the space we had: not optimal!]

We also learned that affordable off-the shelf brushless motor controllers didn’t have the characteristics we needed for the unique needs of the ZTR’s mission. So we were stuck at less-than satisfactory vehicle dynamics — acceleration, maneuverability, responsiveness – and fell short of proving operator experience as good as or better than a premium hydrostatically-coupled platform.

So last year we undertook two things:

  1. We started building a test and development platform that we simply call our “Sled”.
  2. We designed and built a rugged, production-intent Motor Control for the Low Voltage (<60v) Off-Highway market segment

The Sled:

It’s a modular design, built up of subframe segments that can be changed out fairly easily and permit us to drop in new design elements, install or remove sensors and instrumentation, or troubleshoot/replace components. Here are a couple of pictures of Chad Clendening, our Senior System Engineer, doing some maneuverability testing on a course we set up. Note that he’s driving on one view using a single joystick, and in the other (after the sun came out!) he’s using dual controls.

We chose the odd-looking tiered support for the joystick so that we could experiment with the comfort/ergos of stick location. (It’s definitely not a choice for production configuration.) We think operator comfort should take a higher priority, and we’re looking for ways to use the flexibility of Drive-by-Wire to move from traditional “levers”. The industry may not be quite ready for the joystick yet, which is OK. We can do the levers if that’s desired. Nonetheless we think it’s useful to demonstrate it as a control option for a generation of potential users around the world who are very comfortable with it.

Just to note: we’re also running the machine without a person in the seat, both by wireless remote by emulating a path stored in memory.

This figure is a closer shot of the propulsion subframe with the engine/generator removed. Here you get a good look at the motor controls as we’ve mounted them exposed to the elements.

This figure gives a better view of the production intent gearboxes and motors installed under the motor controls in the picture above.

Finally here is a look at the present engine/generator set. It’s “hardware of opportunity” in the form of a 16HP engine and a small 6.6kVA generator. The output is not sufficient to support mowing, but surprisingly adequate for checking out the coffin-corners of acceleration/deceleration, regeneration, and extreme maneuvering. Buoyed with the instantaneous energy available from the small Hybrid storage battery, the operator can command responsiveness from the >1000lb Sled with authority.

Motor controls

There’s a lot going on in our motor control development and it certainly deserves its own entry; we’ll provide that soon. The following is a brief update.

This picture shows it “unfolded”. (Note there are some aspects of the board designs that we’re sensitive about so please do forgive the fact that it’s obscured a bit.)


This is a thermal photo of the power board on test at >175A continuous has gone very well).

Based on how warm the conductors are while power switching elements are comfortably cool, I hope you can see that we have made a robust product that’s definitely up to the rigors of the expected environment. They’re designed to be mounted pretty much anywhere without forced airflow, IP66 rated. We’ll start environmental chamber testing later this year.

Also we can add that we’ve been using the core power module design to develop a bi-directional converter. This will be a key part of our overall Hybrid architecture in our Power Control and Conditioning Center (PC3) which integrates vehicle and power control, as well as off-board connectivity).

As for performance: it’s great. Reversals from high forward speed to reverse spin the wheels on grass and “chirp” them on asphalt. Genuine zero-turn rotation — spinning the vehicle with the center of the rear axis stationary — is right on. We’ll continue to map the joystick and groom acceleration characteristics (optimizing acceleration vs controllability/confidence). Very low speed (crawling ~5cm/sec to squeeze past the car and park in the garage) is very smooth and precise. BTW: It works with economical Hall sensors and sensorless.

To our potential OEM customers: We’re not mower designers by any measure, and we know that. But we understand how this system can be laid out/installed in a fashion that enhances the utility of the Zero-Turn platform. This figure is a packaging concept for the entire power system (sized for a 60 inch “premium” market professional platform). There’s no engine shown – we’re agnostic to brand, fuel, EFI or conventional, etc.

Our path necessarily demands the leadership of a capable ZTR manufacturer to move ahead. We’re eager to have those discussions whenever its suits the industry, and hopefully move soon to execute an “alpha” design that meets the needs of the professional landscaping community. And, while this is a ZTR-centric discussion, a variety of off-highway applications are also suitable for the technology.

Well: THAT was a pent-up discussion that needed sharing! Thanks for following along

Please give a shout if you have any questions at all. We’d welcome a call, web meeting or face-to-face to discuss more.

In the meantime, stand by for more updates (and details) soon.