Discuss electric vehicles, it must be said how many kWh battery capacity, how many kilometers of mileage. Because of the anxiety of battery life and charging anxiety, it has always been two major problems that plague electric vehicles.
However, some time ago, the Mercedes-Benz EQC motor failure storm made people realize that the motor, the most important driving component in the electrified model, has a status that cannot be underestimated.
In the electrified model, there is a motor with a strong power output and efficient energy consumption, which often makes a great contribution to the performance improvement of the vehicle.
So from the Rhône Porsche hybrid more than 100 years ago to the current electric vehicle with a hundred flowers, the motors of electrified models are also constantly evolving. Today, let the professor take you to see from the very beginning of the hybrid model to the current electric vehicle, what kind of development process the motor has experienced, and what the future motor will be.
Pure electric vehicles appeared long before the invention of the first car, but they were quickly abandoned because of their poor endurance and low practicality. For hybrids, the earliest motor for vehicles appeared in the Rhône Porsche hybrid in 1900, the oldest electrified vehicle in existence, which used two wheel motors, and Rhone Porsche became the originator of the wheel motor.
The hub motor was used as a drive motor at this time not because of its mature technology, but because the mechanical lubrication technology at that time was not as advanced and perfect as it is now, and the less mechanical transmission in the driving process, the higher the efficiency. So at that time, the wheel motor became the preference of the car's chief designer, Ferdinand Porsche.
Hub motor does not have a complex transmission system, the motor shell rotor is directly the hub, the biggest feature is of course the transmission path is extremely short, the efficiency is much higher than the transmission system with a reduced gearbox. In 1900, such an in-wheel motor could reduce mechanical transmission losses by up to 83%, which was very efficient.
However, the wheel hub motor will lead to a large sub-spring mass, seriously affecting comfort and handling, in the current transmission system efficiency is getting higher and higher, the wheel hub motor's high drive efficiency advantage is not obvious. Therefore, the visibility of the wheel hub motor in the passenger car is not so high, and the wheel hub motor is widely used in models with low quality requirements under the spring such as commercial vehicles.
There are still vehicle and parts manufacturers developing in-wheel motors for passenger cars. Among the new high-end brands that BYD will release this year, the first off-road vehicle to debut will use in-wheel motors. BYD has applied wheelside motors on commercial vehicles such as buses, which shows the depth of BYD's technical reserves.
In the long history of automobile development, due to the lag of electrical technology, electrified models could not become mainstream for a long time, and the development of electrified models experienced a vacuum period.
Until 1997, Toyota, with the first generation of Prius, announced the arrival of the "world's first mix" - THS.
THS motor actually has a very long history, although all the way to use permanent magnet synchronous motor, but in some technical details, THS motor is still evolving, these technological evolution also radiated to Toyota's pure electric vehicles and fuel cell vehicles.
Toyota's electrified models, including the THS, have invariably used permanent magnet synchronous motors, such as the 1KM motor used on the second-generation Toyota MIRAI, which is an improvement from the motor on the Lexus GS450h.
The GS450h uses a 1KM motor with a maximum power of 147 kW and a maximum torque of 275 Nm. The second generation of MIRAI uses a 1KM motor with a maximum power of 134 kW and a maximum torque of 300 Nm. The same is a 1KM type motor, in addition to the book data what is different?
The answer is hidden in the permanent magnet rotor. The housing of the permanent magnet rotor has added several cross grooves, which are to better guide the magnetoresistive torque and magnet torque, and the internal of the permanent magnet rotor has been greatly upgraded.
The original two magnets in the rotor unit were re-divided into 3 pieces and rearranged, so that the amount of magnet used was reduced by 20%, and the hollowing out design of the electromagnetic steel plate also made the permanent magnet rotor more lightweight and provided a higher synthetic torque, so the peak torque of the entire motor was increased.
As for the efficiency of the motor itself, after more than 20 years of evolution, the maximum efficiency of the THS motor has reached 95%, which is up to 40% higher than the motor used by the first generation of Prius. Although the 1KM motor still uses a circular coil centralized winding, the MG2 drive motor in the latest TNGA hybrid model has been upgraded to a more efficient distributed winding flat wire motor.
Toyota is also working together on a variety of energy routes, and Honda next door has made an iron effort to invest in the research and development of pure electric vehicles. Their accumulation in motor technology is also very deep.
Below are the F/H5 motors used in the Honda e, e:HEV models and the H4 motors used in i-MMD systems. Looking at the picture, it is obvious that the difference between the two motors is clear.
Both H4 and H5 motors use distributed windings, but one of the biggest changes to the H5 is the replacement of round wires with flat wires. The advantages of flat wires over round wires I have mentioned in the previous article, lower resistance, greater magnetic flux, greater power density, more conducive to making small size high power density motors.
The winding of the F/H5 type motor is also very distinctive, in the outer edge of the motor, the winding form of the flat wire is like an S shape, Honda calls this winding method "Watari", in the winding that does not generate a magnetic field, through this unique winding method to shorten the winding length as much as possible, further reducing the copper loss.
At the same time, in order to minimize the eddy current generated when the motor is rotated at high speed, the thickness of the electromagnetic steel plate purchased from the outside is only 2 mm, and the entire rotor part is made of multiple layers of electromagnetic steel plates. This is a great test of precision during processing, and once the multilayer electromagnetic steel plate is misaligned during processing, the magnet inserted into it can easily cause damage.
For the working range of the e:HEV model, Honda also added a boost converter (VCU) to the H5 motor dedicated to hybrid models to help the motor have better power performance and efficiency when running at high speeds.
The above two motors are representatives of Japanese hybrid motors, they have made indelible contributions to the electrification of automobiles, so what will the motor look like in the era of pure electricity?
Audi recently released the e-tron S based on the MLB Evo platform, compared to the e-tron using dual induction asynchronous motors, the e-tron S solution is simpler and rougher - directly in the rear axle under the two induction asynchronous motors, and the front axle induction motors form a three-motor system, in Boost mode can output a maximum power of 370kW and a maximum torque of 973Nm.
Compared to permanent magnet synchronous motors, the induction asynchronous motors used by the e-tron S have slight differences in structure, and the rotor becomes a winding set. But the essence of the e-tron S motor is not in its structure, but in its control.
Audi created a torque vectoring control system for the e-tron S that can change the torque output of the two rear axle motors in a matter of milliseconds, with a maximum torque output difference of up to 2100 Nm. Compared to quattro systems using Tolson differentials or electronically controlled LSDs, the response time is 4 times faster.
Of course, the disadvantage of this system is of course that the induction asynchronous motor is larger and bulkier than the permanent magnet synchronous motor, and this problem can only be left to the new car built by the subsequent use of the PPE platform. But the speed of the motor's response can still be seen on this e-tron S.
In the future, the research and development of electric vehicles, whether it is battery-led or motor-led, at least for now, the range of data that everyone is most concerned about, the battery is still the most critical factor.
But can it be said that the motor is useless? Of course not. As the core of converting electrical energy into driving force, the motor is one of the three major systems of electric vehicles that can be compared with batteries. Without the motor, it is impossible to talk about making the electric car run.
And if the battery technology has not been able to make a significant breakthrough for a long time in the future, improving the efficiency of the motor will become the next mountain for R&D personnel to tackle the problem. High-efficiency motor + power exchange system may therefore become the main component of electric vehicles in the future for a period of time. Therefore, the status of motor research and development is still not to be underestimated.