The technological innovation and mass production application of axial flux motors may effectively solve some of the outstanding problems currently faced by the field of electric vehicles, such as light weight, torque density and cruising range, which people are most concerned about. In Mercedes-Benz's Vision One Eleven concept, as well as the Ferrari SF90 Stradale, 296GTB and McLaren Artura, which have already been unveiled in various high-performance models, the entire vehicle drive system is equipped with an axial flux motor, which is also considered by the major ultra-luxury car brands to be "the best solution for the road to electrification of high-performance cars today".
While radial flux motors have ushered the entire automotive industry into the era of electrification, axial flux motors are better in every way: they are not only lighter and smaller, but they also deliver more torque and more power, and these breakthrough motors are able to create more impact in a smaller, lighter body, opening up a whole new world of possibilities for automotive designers.
The torque of the radial flux motor is proportional to the square of the rotor radius, while the torque of the axial motor is proportional to the cube of the rotor radius, so it can produce a higher torque figure, and the axial flux motor is 50% smaller and 50% lighter than the radial flux motor with the same output power, such as the axial flux motor mounted in the Mercedes-Benz Vision One-Eleven pure electric concept car, which weighs only 1/3 of the ordinary motor with the same output power.
The advantage of volume and weight not only greatly reduces the use of materials such as copper, iron and permanent magnets required for motor production, but also allows the axial flux motor to be arranged in a narrower place, such as the notch of the automobile wheel hub, thereby reducing the participation of gearbox, transmission shaft and other parts, reducing kinetic energy loss, so the driving efficiency is higher, and the torque compensation effect is more direct.
At the same time, because the axial flux motor is very compact and lightweight, less structure is required to install it, which saves more weight, and it does not rotate at the same speed as a conventional radial flux motor, so there can be no reduction gears, further reducing the total weight of the system, and other subsystems can also benefit from weight reduction, such as braking and cooling systems. Overall, a 5-10% increase in efficiency and range can be achieved.
Mercedes-Benz axial flux drive motor technology exposed
Mercedes-Benz has just unveiled its new concept sports car, the Vision One Eleven, which, in addition to its unique styling and design, is equipped with four drive motors, each with a maximum output of 480 horsepower, and the vehicle has a maximum output of 1,920 horsepower. Acquired by Mercedes-Benz in October 2021, the YASA next-generation axial motors will be produced at Mercedes-Benz's Berlin-Mallingfeld plant and will be the centerpiece of the next powertrain in the performance segment.
Currently, 99% of electric vehicles are equipped with radial flux motors, but YASA's axial flux motors are 1/3 the depth of radial flux motors. Due to the small number of components, the weight is also 1/3 of the original. What's more, the compact motors produce 480 horsepower each, 145 horsepower more than similar motors developed by Koenigsegg.
Tim Woolmer, Founder and CTO of YASA, said, "In a traditional radial flux motor, the current is perpendicular to the axis of rotation, whereas in an axial flux motor, the electromagnetic current is highly efficient because it flows parallel to the axis of the motor and rotates, making it more powerful and durable than a radial flux motor capable of reaching a whole new level of performance." ”
And the benefits of this axial flux motor are not only "weight and size", but also increase the freedom of installation. An electric motor, which previously had to be mounted in the front and rear center of the vehicle, can now be mounted inside the wheels and can also be used as a brake to store power efficiently, and can also be used as a brake caliper. Since there is no need to install an electric motor on the side of the body, the cabin and luggage compartment are more spacious and the design freedom of the body itself is increased. The benefits of this axial flux motor are not only "weight and size", but also "high degree of installation freedom".
If you want to be a little more daring, you can remove the engine, gearbox, exhaust system, etc. of the gasoline car, install this axial flux motor on each wheel, and install the battery and inverter in an empty place somewhere to quickly build an electric car, or you can use the gasoline car platform to make a cheap electric car.
Of course, torque vectoring of the wheels can also be done with a more efficient and simpler system. Since there is no need to install a differential or drive shaft, the front and rear wheels can be moved more widely, making it possible to achieve unprecedented car movement. Torque vectoring has always been a passive control of "braking the inner ring and relatively increasing the torque of the outer ring", but with this axial flux motor, it will be possible to control the driving force of the front, rear, left and right more freely, and it will be possible to achieve a completely different performance dimension.
In other words, this axial flux motor has unlimited potential to do things that gasoline-powered vehicles can't do and can achieve layouts that traditional radial flux motors can't. Not only maneuverability, but also the internal space and carrying capacity will be significantly increased.
Electric vehicle start-up Infinitum
推出Aircore Mobility motor3
Electric vehicle start-up Infinitum has launched the Aircore Mobility motor3, an axial flux propulsion and traction motor designed to provide more sustainable power for passenger and commercial electric vehicles, as well as other emerging electric platforms such as aviation, marine and construction equipment. According to Infinitum, the Aircore Mobility motor is 10% more efficient, 50% smaller and lighter than a radial flux motor with the same torque rating. The axial flux motor design achieves this by using patented PCB stator technology, which requires 66% less copper and does not require a heavier core.
Increased efficiency and reduced weight mean longer driving ranges for electric vehicles and other electric platforms, smaller, cheaper battery packs, and faster charging times.
Axial flux motor technology
Most motors are some variants of radial flux motors that use an iron-core stator and windings to create a rotating magnetic field that moves the rotor within the stator. Iron helps to concentrate and increase the strength of the magnetic field, but it is heavy and adds a lot of weight to the motor. In an axial flux motor, the rotor disc is located next to the stator, and the axial magnetic force (the force parallel to the axis of rotation) causes motion in the rotor. Axial flux motors typically have a high torque-to-weight ratio, which makes them ideal for transportation applications such as electric vehicles and even aviation.
Radial and axial flux motors
Printed circuit board stator
The key to the small size and light weight of Infinitum axial flux motors is the PCB stator. Infinitum's air-core motors do not use iron cores and copper windings in the stator. Unlike conventional motors, copper coils are etched directly onto the PCB stator, making the motor 50% lighter and smaller than conventional designs. In EV powertrain applications, the drive current from the traction inverter generates an axial magnetic flux through the fixed PCB stator windings to move the rotor and drive the vehicle forward.
In addition to size and weight, other benefits of not having an iron core include reduced stator hysteresis and eddy current losses, resulting in increased efficiency or physical output per unit of electrical input. PCB stators also improve motor reliability by eliminating potential points of failure associated with copper windings and insulation in conventional motors.
Iron core and PCB stator
Modular design is scalable
The modular design of Aircore Mobility allows it to be scaled according to the power needs of the application without changing the core motor structure. With this approach, multiple PCB stators and rotors can be combined as needed to meet the power needs of the application, from small passenger cars to Class 8 commercial trucks such as the Tesla Semi. The flexibility of the design allows engineers to experiment with different configurations, quickly adding stators and rotors to determine which configuration best suits their power and torque requirements.
According to Ramon Guiart, vice president of engineering at Infinitum, this higher power scalability is a key differentiator for Aircore Mobility compared to previous models. "The difference is in the scalability that we can achieve," Guiart said. These specific units are around 150 kilowatts or 200 horsepower. ”
In terms of cost, PCB stators can be manufactured using widely available standard board production techniques.
Aircore Mobility motors have multiple rotors and stators
Cooling of high power density motors
The ability to add multiple rotors and stators allows Aircore motors to scale in power, but there are also challenges in thermal management in the motor's compact space. For Infinitum, replacing air cooling with an oil-based system is the answer to this challenge.
Panhub Power launched ICD150K axial flux motor
The ICD150K axial flux motor of the disc hub power, a drive motor weighing only 24 kg, can output a peak power of about 150 kW and a maximum torque of 325 Nm.
Through technological innovation and positive research and development, Panhub Power has launched a three-in-one distributed drive solution for new energy passenger vehicles based on ICD150K, through the highly integrated design of motor, reducer and electric control box, the weight of the assembly is greatly reduced, the volume of the assembly is reduced, the weight of the whole system assembly does not exceed 100Kg, the peak power reaches 300Kw, and the total success rate density of the system exceeds 3kW/ kg, and can be customized according to the actual needs of the vehicle development platform, in which the "parallel axis scheme" is conducive to reserving more chassis space in the Z direction height and Y width, and the "coaxial scheme" layout method can obtain greater design freedom in the X direction, and the length of the left and right half shafts of the scheme is consistent, and the assembly mass distribution is more uniform.
Hangzhou Zhonghao Electric Technology Co., Ltd. developed
The application of axial flux motor in the range extender of light trucks
Not long ago, Hangzhou Zhonghao Electric Technology Co., Ltd. held a ceremony for the batch production of new extended-range generators.
Axial flux range extender and light truck products
Zhonghao 45kw range extender generator products
Zhonghao 60kw range extender generator products
Dual-stator axial flux motor technology
The product adopts double stator axial flux motor technology, which is 1/3 smaller in volume and 30% less weight than mainstream products in the market. Its flat structure and low-speed and high-torque performance characteristics perfectly match the needs of range extender products for generators. The motor did not even extend beyond the engine's air intake system after installation. The structural design of the whole system of range extender is very small, which can better adapt to the narrow space of vehicle assembly and meet the needs of vehicle lightweight.
Carbon fiber spiral wound rotor disc
In addition, the traditional dipping process is canceled, and a more advanced vacuum potting process is adopted, which greatly improves the structural strength and NVH performance while ensuring that the production process is clean and environmentally friendly.
Carbon fiber spiral wound rotor disc
Stator assembly
Iron core punching and coiling forming process
The stator core of the product adopts the one-time forming process of punching and rolling, and the material utilization rate is extremely high, and the raw material cost is reduced by 30% compared with the stamping core, while the axial permanent disk motor, with its unique magnetic flux structure, determines that its axial thickness is more than 2/3 thinner than that of conventional motors. The rotor disc has a similar structure to the flywheel and is axially mounted, which can replace the flywheel part of the range extender, which not only greatly reduces the manufacturing cost when designing and developing the range extender, but also improves the energy conversion efficiency.
Iron core punching and coiling forming process
From the point of view of the power generation efficiency of the range extender, the product uses an axial flux permanent magnet motor to match the optimal fuel consumption point of the engine, which will make the system more efficient. In the case of gasoline and diesel engines with rated speeds of only 1500rpm to 3000rpm, the axial flux permanent magnet motor has high efficiency and has a wide range of high efficiency. The overall efficiency of the range extender system can reach more than 95%. The direct benefit of the high-efficiency power generation system is that the fuel saving rate of the vehicle can reach more than 20%.
Appreciation of high-definition large picture of axial flux motor
YASA
Koenigsegg
EMRAX
EVO
magnax
Saietta
Siemens
Traxial
Source:
1. RIO electric drive