Civil engineering
The first electric cars appeared before cars with internal combustion engines (ICE), in 1828. At the beginning of the 20th century, electric vehicles accounted for over a third of the entire US vehicle fleet. However, then they gradually began to give up their positions, yielding to cars in terms of range, convenience of refueling and other parameters.
Several design options for electric vehicles can be implemented. A classic electric vehicle is powered by batteries charged at a charging station. An electric vehicle with an external supply of electrical energy receives electricity from external conductors by a contact method or by means of electromagnetic fields. An internal combustion engine with a generator can be installed to recharge the batteries of an electric vehicle, or electricity can be generated from liquid or gaseous fuels directly using catalytic fuel cells. All of the above schemes can be combined in various ways.
Periodically, interest in electric vehicles resumed, usually during the rise in prices for petroleum products, but quickly faded away: cars with internal combustion engines remained out of competition. As a result, equipment with electric propulsion has become widespread in the segment of transport with an external supply of electric energy: electric trains, trams and trolleybuses, in the niche of warehouse equipment.
A separate segment can be distinguished by special equipment, for example, mining dump trucks with a carrying capacity of over 100 tons, on which an electromechanical transmission is used.
At the beginning of the 21st century, interest in electric vehicles resumed at a new level. The determining factor was not the rise in prices for oil products, but the demand of environmental activists to reduce harmful emissions. The American company Tesla, adored (hated) by many Elon Musk, became the manufacturer that has ridden the "environmental wave" as much as possible.
But no matter who and no matter how they relate to Elon Musk, it cannot be denied that Tesla has done a great job: in fact, a separate segment of the car market has been created, electric cars have become an area in which auto giants have begun to actively invest. If development is actively carried out in some direction, the result will be achieved sooner or later. There will be new batteries with increased capacity, high charging rates and an extended temperature range of application, more efficient and compact electric motors, with integrated gearboxes that can be placed in motor wheels with a low unsprung weight and other developments.
There is no doubt that in the foreseeable future, electric cars will practically replace cars with internal combustion engines, and not for environmental reasons, but because of the general technical superiority of electric vehicles.
Military equipment
In 1917, the French company FAMH produced 400 Saint Chamond tanks with Crochat Collendeau electric transmission, in which a Panhard gasoline engine was connected directly to an electric generator, which powered two electric motors, each of which was connected to a drive wheel and a caterpillar drive. Also in 1917, a tank with electric transmissions from Daimler and British Westinghouse was tested in Great Britain.
Later examples include the German heavy self-propelled artillery unit (SAU) "Ferdinand" ("Elephant") weighing 65 tons. Power plant "Ferdinand" included two V-shaped 12-cylinder carburetor water-cooled engines "Maybach" HL 120 TRM with a capacity of 265 liters. pp., two electric generators Siemens-Schuckert Typ aGV with a voltage of 365 volts and two traction electric motors Siemens-Schuckert D149aAC with a power of 230 kW, located in the rear of the hull, which drove each of their wheels through a reduction gear made according to a planetary scheme.
While Ferdinand is relatively new, there are not many complaints about her work. As such, one can note the greater complexity and cost compared to power plants of the classical design, as well as the need to use a significant amount of copper, which is in short supply in Germany.
In addition to the Ferdinand self-propelled guns, the use of electric propulsion was also considered in the German super-heavy tank, the 188-ton Maus tank.
Around the same period, an experimental EKV heavy tank with an electromechanical power plant was developed in the USSR on the basis of the KV-1 tank. The technical design of the EKV tank was developed in September 1941, and in 1944 the prototype of the EKV tank was put out for testing. It was assumed that the use of an electromechanical transmission on the tank would reduce fuel consumption, improve the maneuverability and dynamic characteristics of the tank.
The electromechanical transmission of the EKV tank included a DK-502B starter-generator, connected to a V-2K diesel engine, and two DK-301V traction electric motors, with two onboard gearboxes and control equipment.
According to the test results, the design of the EKV tank was recognized as unsatisfactory, the work on the project was curtailed.
Projects of "electric" tanks were carried out in Britain, the USA, the USSR, Germany and France, as well as in other countries throughout the XX century. Nevertheless, at the moment, tanks and armored vehicles of a traditional layout have received maximum development.
Benefits and perspectives
Why is there a constant return to the issue of ensuring the electric propulsion of ground combat vehicles, despite the large number of closed experimental projects?
On the one hand, there is a development of technologies, the use of which in electric propulsion systems makes it possible to count on obtaining positive results that were previously unattainable. Permanent magnet and asynchronous electric motors, high efficiency electric current generators, power distribution systems, fast charging batteries and much more are being developed.
Recently, we are talking not only about ground technology with electric propulsion, but also about the creation of fully electric aircraft up to fairly large passenger models.
On the other hand, the advantages that electric propulsion can provide to ground combat equipment are increasingly in demand:
- the possibility of a flexible layout of the combat vehicle due to the absence in the electric transmission of units with a rigid mechanical connection provided by the shafts;
- increased survivability of military equipment due to the possibility of redundancy of the components of the electric transmission;
- the possibility of abandoning fire-hazardous hydraulic drives in favor of electrical ones;
- the possibility of movement of military equipment on limited sections of the path in the maximum camouflage mode, with minimal unmasking by sound and thermal characteristics;
- the ability to recuperate electricity during braking;
- the best dynamic characteristics and cross-country parameters of armored vehicles equipped with an electric transmission;
- great ease of control of armored vehicles with electric propulsion;
- the ability to provide a sufficient amount of electricity for an ever-increasing number of equipment, sensors, advanced weapons.
Let's take a closer look at these benefits. The main source of energy is a diesel or a gas turbine, in cars with electric transmission they will have a greater resource and efficiency due to the fact that the optimal engine speed can be initially selected, at which it will have minimum wear and maximum fuel efficiency. The increased loads during acceleration and vigorous maneuvering will be compensated by the buffer batteries.
For example, in combination with a generator, a high-speed gas turbine can be installed, which will operate in the "on / off" mode to recharge the buffer batteries, without changing the speed.
In the electric transmission, there is no need to install bulky shafts and gearboxes. The mechanical connection in the electric transmission is available only in the engine-electric generator and electric motor-wheel pairs, but these units can be made as a single unit. The rest of the units are connected with flexible cables.
Unlike mechanical connections, electrical connections can be redundant many times over. For example, at the stage of assembling the case, protected cable channels can be laid, which will house a universal power and data bus, including power and data cables.
The spatial separation of energy sources, supply and communication channels, as well as engines and propellers with an increased probability will allow the combat vehicle to maintain mobility and situational awareness when damaged, which will ensure the possibility of withdrawing the combat vehicle from the firing zone and evacuating from the battlefield.
The rejection of hydraulic drives in favor of electric ones will also help to increase the survivability of ground combat vehicles, both because of the lower fire hazard of the latter, and because of their greater reliability. The Russian Air Force plans to abandon hydraulic drives on the fifth-generation Su-57 fighter by 2022.
The presence of buffer batteries will allow you to remain mobile without turning on the main engine, albeit over a fairly limited section. This will allow promising combat vehicles to implement new tactical scenarios for conducting combat operations from an ambush, when in standby mode the armored vehicle is in full combat readiness, while its thermal signature will be comparable to the ambient temperature.
Batteries will also provide the ability to move in the event of a failure of the main power plant, which will allow armored vehicles to leave the battlefield on their own. In some cases, to evacuate a combat vehicle with an electric transmission, it will be enough to simply connect it to an external power source. For example, an armored recovery vehicle in this way can simultaneously evacuate two other armored vehicles with a partially damaged electric transmission, simply by throwing power cables over them.
As in civilian electric vehicles, in armored vehicles with an electric transmission, energy recovery can be carried out during braking.
Ground combat vehicles with electric transmission will have the best characteristics of mobility and controllability due to the stepless transmission of power to the propellers, as well as flexible power distribution between the electric motors on the port and starboard sides. For example, during a turn, the decrease in power on the trailing bead motor will be compensated for by an increase in the power of the trailing bead motor.
One of the most important advantages of electric transmission will be the ability to provide power to equipment and sensors, for example, radar stations (radars) for reconnaissance, guidance and all-round defense of an active protection complex.
In the near future, laser weapons will become an integral part of ground combat vehicles, which will be able to largely neutralize the threat from small unmanned aerial vehicles (UAVs), anti-tank guided missiles and cluster submunitions with thermal and optical homing heads.
Electricity may also be required for active camouflage systems for armored vehicles in the thermal and optical wavelength ranges.
conclusions
The creation of ground-based combat vehicles with electric propulsion is likely to become inevitable as technology improves and the requirements for the power supply of on-board equipment and weapons increase. The civilian market for electric vehicles can have a significant impact on the rate of introduction of ground-based combat vehicles with electric propulsion.
Promising ground combat vehicles with electric transmission will surpass the "classic" models in terms of dynamism, maneuverability, ease of control, survivability and security, as well as, if possible, placement of promising weapons and sensors with high energy consumption on them.
