The growing energy consumption of on-board vehicle systems gives new technologies a chance to seize the opportunity to radically change the power and mobility of military vehicles in the future
Given that the next generation of the American army is likely to have a hybrid power plant, the industry needs a large-scale program so that it can introduce its energy technologies, which it has already developed (along with the inevitable modifications), into the bulk of combat vehicles. A fly in the ointment in this barrel of honey, however, is that according to current plans, the army plans to adopt such vehicles around 2035. Major decisions about its configuration will most likely not be made before 2025, unless the corresponding programs are accelerated into the Trump presidency.
Huge needs are an excellent incentive for the development of new technologies, which in turn can provide solutions to meet these needs. For example, the growing demand for electrical energy on the battlefield is combined with the need to reduce the logistics burden associated with fuel supplies, as well as to increase the off-road capability of combat forces and combat support forces. All of this strongly supports the widespread adoption of auxiliary power units, intelligent engine controls and hybrid electric drive and, as a result, a sharp increase in the power generated for external consumers.
Overcome inertia
With extensive experience in the production of hybrid vehicle technology demonstrators for various military structures and in the production of hybrid buses for the civilian sector, BAE Systems is well positioned to assess exactly where this technology is today and what its prospects are. The same is true for DRS Technologies, which has also participated in many demonstration projects. Tom Weaver, Commercial Director at DRS Network Computing and Test Solutions, said the market is still emerging and that the benefits of electric vehicles have yet to overcome the inertia of traditional vehicles. Such inertia has a negative impact on the progress of machines capable of generating the necessary power for external consumers, despite the needs that have increased "by at least 100%" over the past decade.
“DRS is working with different customers to demonstrate machines with integrated new technologies in various performance tests. Successful demonstrations and positive user reviews did not lead to the deployment of such vehicles in the troops, moreover, the requirements for them were not even developed. But demand will nevertheless continue to grow, especially for expeditionary operations and specialized vehicles such as directed energy weapons systems.”
DRS now offers an onboard power system for Medium Tactical Vehicle (MTV) and HMMWV equipment in the form of a Transmission Integral Generator developed in collaboration with Allison. This system, installed on an MTV truck, for example, generates power up to 125 kW for onboard or external systems. The company also manufactures other energy management systems for various vehicles. Chief engineer Andrew Rosenfield of BAE Systems, which also deals with such systems, believes it is unlikely that purely electric vehicles will play a major role in ground combat, mainly due to problems with recharging batteries.
“While the powertrain technology for all-electric operation is well established, the refueling issue may well prevent purely electric vehicles from being put into action,” he continued. "After all, diesel is available anywhere in the world, while finding a battery recharging station in the desert is very difficult, but even if you do find one, waiting eight hours for them to be fully charged is probably not feasible."
Weaver agreed that hybrid cars are likely to prevail, also mentioning the limitations of the clean electric car charging infrastructure and the ubiquity of diesel and JP8 jet fuel. However, Rosenfield emphasized that purely electric vehicles could play a large role at military bases, since they could move goods, as is the case in modern factories or at airports (airfield tractors). “Fuel cell machines would most likely be able to perform such tasks, as they need free access to hydrogen reserves,” he said.
Weaver believes that there is a difficult path ahead of fuel cell vehicles. “Firstly, there is no hydrogen gas infrastructure yet, and there will be a certain distrust in the deployment of the new fuel. The path of such vehicles will begin with well-organized expeditionary operations."
Hybrid designs are also more sophisticated than purely electrical designs and have several features that make them more attractive than purely electrical and conventional power-driven machines. “First, hybrid electric platforms use the same fuel as traditional diesel vehicles. Second, low-RPM torque is ideal for a machine traveling over rough terrain or climbing a very steep slope."
He added that the ability to generate large amounts of electricity on board is becoming increasingly important as new capabilities such as communications and weapons systems that use powerful lasers are deployed. The ability to export this energy is also a huge advantage, as these machines can power communities and hospitals whose own power grids are out of service due to combat damage or natural disaster.
"Finally, the reduced operating and maintenance costs associated with substantial fuel savings and greater reliability make hybrid electric vehicles a smart and long-term choice."
As Weaver noted, the demand for electrical energy on board combat vehicles has never decreased, they will only grow from year to year. "Newer functional systems require more and more power from the carrier platform, as well as continuous upgrades to the power generation and distribution systems of current vehicles."
“Once you've added features such as silent locomotion, radar, advanced communications, signal jamming, and electromagnetic armor or weaponry, the platform falls behind and becomes unmanageable without switching to a hybrid electric scheme. In the next decade, for all combat vehicles, one of the most important components will be the ability to generate large amounts of electricity on board."
“Electrically powered vehicles have to do their job as well as or better than their traditional mechanical counterparts,” he continued. “Not only are motorized systems significantly simpler and have fewer moving parts than motorized systems, but they often have a surprisingly good level of redundancy, making them more reliable. For example, most transverse electric transmissions can operate normally with a single motor that has failed."
Weaver said the key technologies nurtured in public transport are already in place and ready to enter the market. “The widespread use of hybrid and electrical circuits, especially in intercity buses and trams, has led to the development of motor controllers, inverters and converters that are close to what the military needs,” he said. “All the industry needs are customers willing to pay for the qualification process, as well as enough to keep the cost down.”
In the meantime, work continues on the demonstration. General Motors (GM) at the AUSA show in October 2016 showed a "ready-to-go" version of its Chevrolet Colorado ZH2 fuel cell vehicle, which is based on an elongated mid-size pickup truck chassis. According to the schedule, the Colorado ZH2, with the assistance of the TARDEC Armored Research Center, is to undergo a series of military tests "in extreme operating conditions" during 2017.
It was an accelerated program. GM and TARDEC worked together to create a demo in less than a year after signing the contract. “The speed at which innovative ideas can be demonstrated and evaluated is very high, which is why industrial ties are so important to the military,” said TARDEC Director Paul Rogers. "Fuel cells have the potential to significantly enhance the capabilities of military vehicles through quiet operation, power generation for external consumers and stable torque - all of these advantages make this technology more closely explored."
“ZH2 enables the army to demonstrate and assess the readiness of fuel cell technology for military applications, while at the same time answering the question of how useful fuel cell electric vehicles can be in certain conditions and in certain combat missions,” said Doug Hallo, spokesman for TARDEC.
The anticipated benefits that TARDEC must evaluate include near-silent operation allowing for silent surveillance, reduced thermal signatures, high wheel torque at all speeds, low fuel consumption across the entire operating range, and drinking water as a chemical byproduct. processes occurring in fuel cells. The Colorado ZH2 has an onboard power take-off for external consumers.
The propulsion system is based on proton exchange membrane fuel cells capable of generating up to 93 kW of direct current, and a battery that provides an additional 35 kW for the propulsion system and is charged during regenerative braking. This is what GM's ZH2 Project Manager Christopher Kolkit explains.
“The vehicle's tanks hold about 4.2 kg of compressed hydrogen at 10,000 psi, which is more than 689 times the atmospheric pressure. Atmospheric air is a source of oxygen required for the electrochemical process, as a result of which the required electricity is generated; only water vapor is released,”he noted.
For all electric drive systems, the delivery of energy from the source to the wheels is easier than with traditional vehicles. “The ZH2 does not have a transmission in the usual sense of the word. An AC traction motor with a single-stage gearbox transfers torque directly to the transfer case and four-wheel drive system,”explained Kolkit.
Portable infrastructure
Through this program, the TARDEC Center is also exploring what could be at least a partial solution to the hydrogen availability (infrastructure) problem. Its solution here is favored by the fact that this chemical element can be produced in various ways from different sources. According to the representative of the TARDEC Center, at the initial stage of work on the ZH2 project, the idea is to obtain compressed hydrogen during the reforming of aviation kerosene JP8 in a portable reformer, which will be moved to each test site along with the machine, because this will increase the number of solved at this stage of tasks.
“We are currently looking to create a reformer that can use a variety of sources available locally, such as natural gas, JP8 jet fuel, DF2 diesel or propane, to produce hydrogen,” he said. - Local electrical networks, including possibly renewable energy sources, along with water resources, can also be used for hydrogen production. This would allow the army to reduce the amount of fuel that is brought to a specific theater of war and rely on what is available in that theater."
Whether it's batteries, fuel cells or mixed diesel-electric power plants as the prime mover, converting electric current into forward propulsion requires reliable and efficient electric drives. The British company Magtec manufactures electric drive systems for the aerospace, marine and automotive markets, offering, for example, several options for converting commercial trucks with new propulsion systems.
However, the company also developed complete powertrains for tracked and wheeled platforms to demonstrate hybrid technologies manufactured by BAE Systems Hagglunds for the British and Swedish defense agencies in the early 2000s.
For SEP (Splitterskyddad EnhetsPlattform) platforms, both wheeled 6x6 and tracked, the company has developed in-wheel hub motors (motor-wheels), including a two-stage reduction gear and braking system in each, twin generators, control equipment and power distribution. For SEP, she also developed, installed and tested software to control key functions such as power distribution, traction control, electronic differential locks and steering that allows the machine to turn on the spot. In addition, this system meets all military EMC and environmental regulations.
Magtec's chief executive said he sees good growth potential for electric vehicles with extended range for combat support missions. At the same time, new technologies contribute to a significant improvement in mobility, a decrease in fuel consumption, greater redundancy, plus they allow making original layout decisions. He also noted that the electric propulsion simplifies the implementation of remote operation and autonomy.
Regarding the further development of the necessary technologies, he noted that the drive systems are ready to enter the market with improved power electronics (for controlling power drives) based on silicon carbide semiconductor circuits. They are necessary to control the high voltage on which new generation electrical systems operate. The director of Magtec noted that the 24 volts, on which most modern systems operate, are now too low for the main consumers of electricity (increasing the voltage allows you to transfer more power through the cables without excessively increasing the amperage).
One company in the field, GE Aviation, has won a $ 2.1 million contract to develop and demonstrate silicon carbide power electronics. Following an 18-month development program, the company is expected to demonstrate the benefits of its silicon carbide metal oxide FET technology combined with gallium nitride devices in a 15 kW, 28/600 volt bidirectional DC / DC converter.
According to the company, this equipment can handle twice the power, while occupying half the volume of current silicon power electronics, while the converters will be able to work in parallel and be programmed in accordance with the CAN standard.
The company is developing a next-generation vehicle power architecture from TARDEC, calling it disruptive technology, and hopes a technology demonstration will be ready by mid-2017.
Double speed
Another breakthrough technology is the DARPA Defense Advanced Research Projects Agency's Ground X-Vehicle Technology (GXV-T) project, in which electrical systems will play a significant role. The goal of the project is to halve the size, weight and number of the crew of promising armored vehicles, to double their speed, the ability to overcome 95% of the terrain, as well as to reduce the signs of visibility.
In July 2016, DARPA gave Qinetiq a $ 2.7 million investment to refine the technology of electric drive systems for the GXV-T project. The company describes this technology as compact and extremely powerful electric motors inside the wheels that replace various gearboxes, differentials and drive shafts. This approach, the company said, dramatically reduces the overall weight of the platform and opens up new design options that will improve safety and performance.
Qinetiq emphasizes that in addition to its use in new concepts, such as the GXV-T, this technology can also enhance the capabilities of existing vehicles during retrofits. For example, a multi-wheeled infantry vehicle retrofitted with hub drives or motor-wheels "could benefit from the increased power and mobility that weight savings provide, or vice versa, use these savings to improve protection, install equipment, or increase passenger capacity."
The investment was followed by a contract, announced in September 2015, under which the concept will be translated into a real design and tested, after which two full working prototypes will be produced.
“Conventional actuators are quite heavy, have limited capacity and are made up of components that can turn into lethal projectiles if exploded by a mine,” said the head of research at Qinetiq, commenting on the contract. "Moving the drives to the wheels removes this threat and breaks the tendency for vehicles to become heavier and less mobile due to the increased level of protection and the power of weapons."
Existing machines can also benefit from the electrification of non-propulsion subsystems. For example, the German company Jenoptik is to supply 126 electrical turret and weapon stabilization systems for the Polish Leopard 2PL tank modernization program. According to the company, the electrical systems will replace the hydraulic systems on the tank, thereby reducing maintenance and heat generation.
Deliveries are due in 2017-2020 under a $ 23 million contract signed with Poland's Bumar Labédy in October 2016. The very same company Bumar Labedy signed a cooperation agreement on the modernization of tanks with the German company Rheinmetall in February 2017.
One of the activities of Jenoptik is the development and production of compact stabilized weapon / sensor platforms, drive systems for towers and weapons, and mirrors for stabilizing the line of sight of armored vehicles.
For example, a gun and turret drive system for large weapons systems consists of horizontal and vertical guidance electric motors, which direct the gun in azimuth and elevation, respectively, depending on the signals of the main and backup control units. Both drives include absolute positioning brushless synchronous motors with zero clearance between the output gear of each motor and the toothed sector of the weapon assembly.
The system, capable of operating with a supply voltage of 28 and 610 volts DC, can throw the gun in each plane at a speed of up to 60 ° / s or slower than 0.2 mrad / s.
The drive control unit, in accordance with the input signals from sensors, controls and an active sight, transforms the power supply into a pair of three-phase systems, one for each of the turret and weapon guidance, stabilization and actuator servomotors.
The global vehicle electrification market will be worth $ 300 billion by 2026, according to a report by research firm IDTechEx released last year. This growth, driven by an increase in the number of electric motor controllers per vehicle (as steering, suspension and other previously mechanical, pneumatic and hydraulic parts will replace electrical systems), will provide a technological basis for the mass market, thus reducing their cost for military vehicles.
