Text/Ruan Jincheng
Looking back at the development history of automobile electrification, there has been a technological revolution that has greatly affected the automobile manufacturing industry in the past ten years. It is just a small EPS (Electronic Power Steering) ).
The earliest automobile steering was hydraulically assisted. In the past ten years, hydraulic assistance has almost disappeared and has been replaced by EPS. EPS is a technology that typically uses electric motors to replace mechanical connections.
But in the era of cars becoming increasingly larger, more luxurious, electrified and autonomous in the future, EPS is just the tip of the iceberg in electric motor applications - many mechanical connections in future cars will be replaced by electric motors.
At the AMEE Shanghai Automobile Chassis Exhibition held in Shanghai recently, several major auto parts suppliers, as well as experts from Tsinghua University, analyzed the direction of future automotive technology at the forum.
Experts from Brose’s Motor Division talked about the future trend of electric vehicles. Brose is the world's fourth largest family-owned auto parts company and a century-old company. Their business is divided into three parts. The first is door and tailgate systems, and the second is seats and frames. The third one is the motor division.
Motors are now everywhere in cars
Nowadays cars have a lot of motor applications. In addition to the front EPS, they also include electronic brakes and transmission system motors. In terms of thermal systems, the engine's cooling system and the air conditioner's blower system, including the electronic air conditioner compressor, are all electric motors.
For example, the motor of the braking system has very high requirements for dynamic response. This is easy to understand. When you step on the brake, you must hope that it will work immediately, right? The steering motor has high requirements for power density, and a small motor is expected to have a large torque.
The second generation steering motor based on modular design
Since more and more motors are used in cars, that trend has become inevitable - modularization.
Just like the modularity of Toyota TNGA and Volkswagen MQB platforms, the car's electric motor has been modularized. The most direct benefit is to reduce costs and greatly shorten the system development cycle.
For example, taking the EPS motor of the steering system as an example, Brose's second-generation steering motor based on modular design unified the stator outer diameter of the motor (86 mm), and then adjusted the stator according to the torque of different applications. The length is extended so that motors with different power and performance requirements can be matched.
This is the same as the Toyota TNGA architecture that can stretch the wheelbase and wheelbase to create different levels of models. But the premise is that the foundation of this architecture must be very excellent.
Brose’s second-generation modular steering motor
In addition to the parts of the modular motor, you can also share the production line, so that the investment is evenly shared cost. In addition, experts from Bobo talked about the modular solution for designing a new motor, which can only take 1 to 2 weeks at the fastest. This was simply unimaginable before.
So, what impact will electric vehicles have on motor design?
A common feature of electric vehicles is that they have a long wheelbase because the battery must be placed between the front and rear axles. A longer wheelbase will have two major impacts:
Second-generation steering motor structure
First, a long wheelbase will increase the turning radius, so large electric vehicles will consider installing a rear axle on the rear axle. A steering motor is added to realize rear wheel steering and improve flexibility.
Secondly, a longer wheelbase will increase the axial load, which will in turn place higher requirements on the steering force of the steering system. At the same time, a motor with greater torque will become a trend in the future.
What are the differences between electric motors for future electrification and autonomous driving?
Today’s fuel vehicle motors are relatively simple. They only need a very simple 3-phase motor or 6-phase motor to do the job. But in the era of hybrid and semi-autonomous driving, safety becomes very important, which requires a redundant 6-phase motor to deal with it.
For example, according to ISO26262's requirements for motors, two safety features are the most important. One is that the motor cannot be stuck, and the other is that the motor's circuit cannot be short-circuited, which are mechanical characteristics and electrical characteristics.
In the future of autonomous driving, we will also enter an era of wired steering, which requires a 6-phase motor based on wired control. Because there is no mechanical connection between the steering wheel and the steering wheel, we need to add a force feedback motor to the steering wheel like a game console.
This article comes from the author of Autohome Chejiahao and does not represent the views and positions of Autohome.