Terzo Strives to Electrify Fluid Power
The California company focuses on electrohydraulic pumps to enable electrification across multiple off-highway applications, starting with a mini-excavator.
The intricacies of a traditional hydraulic system are typically where technical issues arise, according to Mike Terzo, CEO of Terzo Power Systems. Simplifying the inherent complexity of fluid power is what his California-based company has worked to address over the past seven years, developing and now commercializing its Hydrapulse electrohydraulic technology.
“Our system effectively digitizes the control of hydraulics, which makes the complex hydraulic system of pressure control valves, directional control valves, pump compensation controls, flow dividers, coolers, etc. a thing of the past,” Terzo told SAE Mobility Media. By combining these discrete components into one “system,” Terzo claims to have made electrification a more “plug-and-play” approach for engineers and designers.
“They don’t need to understand the differences between a pressure compensating pump and a load-sense pump or an open center system and a closed center system to get an extremely compact, lightweight, and energy-efficient hydraulic system,” said the CEO who essentially serves as the company’s CTO as well. “They simply tell us what the work function is (hydraulic cylinder or hydraulic motor) and we can provide the correct size Hydrapulse. They then can easily control the flow rate, pressure and logic all digitally now. That is one of the true advantages of electrification.”
Terzo Power Systems used a mini excavator to demonstrate its electrohydraulic technology to OEMs. The system is scalable for larger machines across the mobile industry, Terzo said. “We developed a flexible voltage and power architecture that allows us to adapt to the numerous variations seen in the off-highway vehicle market,” he said.
Since every vehicle platform is different in terms of duty cycles, individual work function, power levels, control requirements and weight restrictions, Terzo engineers decided to make the system flexible enough to address this high degree of diversity to have widespread adoption. “We can address almost any size of vehicle by utilizing either a single or multiple Hydrapulse system as the prime mover, or as a distributed pump system where one Hydrapulse is dedicated to one work function, similar to how a CNC machine has one servo motor per axis,” Terzo explained.
The company can produce any single Hydrapulse unit in power levels “well over” 100 kW (134 hp), including custom units up to 300 kW (402 hp). By utilizing these units in series or parallel, Terzo can produce more than 1,000 kW (1,341 hp) of hydraulic work output, which addresses the vast majority of vehicles in the off-highway industry, he said.
What makes the Hydrapulse system unique compared to other electrohydraulic offerings is its full integration, according to Terzo. “We incorporate the pump, motor, control electronics, J1939 communications, motor inverter, connectors, HVIL [high-voltage inter-lock], etc. all into one package that is fully tested as a system before shipping to the customer,” he said. “What some may call a complete system usually requires an external inverter drive to control the motor, or they need to provide external liquid cooling, or you need to add hydraulic valves or even add your own pump.”
The liquid cooling is one of the more important aspects that is often overlooked, Terzo said. His team spent years working out the details. “Our motor and control electronics are liquid-cooled with the hydraulic oil itself all internally, so the customer does not need to provide the additional cost, connections, hoses and cooling system to support the system,” he explained.
With any new technology comes limitations and/or trade-offs. With the Hydrapulse system, there are two main limitations, according to Terzo. “For most electrification efforts by an OEM, they must adopt a fully electric or hybrid power platform to utilize the Hydrapulse technology, meaning it’s not easy to retrofit onto existing platforms,” he said. “It’s very difficult to make the numbers (cost) work to provide a viable solution to the end user, so almost all of our work is with OEMs on new development.”
If a customer only wants one unit, the 100- to 300-kW unit size could be another limiting factor. “We address this limitation by working with the customer to understand how to design our product into their vehicle and educating them on the benefits of doing this,” he said.
Mini excavator demo
For its mini excavator demonstrator, Terzo Power Systems did not remove the existing diesel engine and hydraulics. The team added the battery-powered electrohydraulic system alongside the existing ICE system so they could demonstrate, in real time, a side-by-side comparison.
“This allowed us to instantly switch between the systems to compare the performance of every single function,” Terzo said. “This is important since the industry needs to understand how best to implement our technology (or similar technology) at the work function level and to see that it can provide, at a minimum, the exact same performance as the traditional system.”
Terzo selected the Vanguard Commercial lithium-ion battery to pair with its Hydrapulse technology. The 5 kWh, 48V battery system was easy to integrate: “We only needed to add a disconnect and their onboard charger (Level 2 / 1 kW / 240 vac). Everything else is included – the battery management system, voltage monitoring, fault information, CAN bus connection, mounting and sealed enclosure,” he said.
“The Vanguard battery’s modularity allows us to scale to our electrical needs,” Terzo added. “Integration is the whole ticket to the OEM’s world. If they can’t integrate it into their platform, they’re not going to use it.”
In addition to the Vanguard battery, Terzo also added the wireless safety and control system from Pennsylvania-based Fort Robotics. This allowed the team to wirelessly control the entire system. To demonstrate the simplicity of the electronics systems, a single MRS Electronics module was used to control the entire vehicle. “The purpose of the project was not only to provide a demonstration and gain a deeper understanding of how to electrify off-highway equipment, but also to show how truly simple and fast it is to gain the benefits of electrification,” Terzo said.
The project demonstrated improved performance to every work function including the ground drive, according to Terzo, and efficiency improvements of at least 60% and up to 80%. “Most important is that we can show that you can achieve those improvements right now with the same system cost as the traditional system,” he said.
Significant gains also were shown in maintenance, safety, noise and productivity. “It depends on which is the most important metric for a given OEM in a given sector with a given application,” Terzo said.
Terzo Power Systems is actively working with “dozens” of OEMs across off-highway, on-highway and industrial markets worldwide, Terzo said. Commercial units are ready to ship to customers to integrate into their electrification projects. “Expect to see vehicles coming out with our system by early 2022,” he said.
“We are working with large OEMs who have E-mobility groups that are bringing new platforms to market over the next several years, as well as smaller OEMs who we work with to help them develop their whole system,” Terzo said. Vanguard works in tandem with Terzo and other suppliers on the system development.