Friends living in the north should have had this experience. Riding a bicycle on icy and snowy roads, once pedaling hard or braking suddenly, the bicycle will suddenly slip out of control, and even fall hard.

The principle here is actually quite simple, that is, the original tire and the ground maintain “rolling friction” (ie static friction), due to sudden changes in torque (rapid acceleration or Sudden deceleration) causes the force applied to the tire to exceed the limit of friction. The static friction changes to dynamic friction, and the tire cannot be attached to the roadside, and then slipping out of control occurs.

(Static friction and dynamic friction indication)

Note: Simply explain, the rough “potholes” between the two contact surfaces are stuck with each other, that is, static friction is formed; and once displacement occurs, the two The contact area of ​​each surface is greatly reduced, so the dynamic friction coefficient is smaller than the static friction coefficient.

For cars, the same thing will happen.

It’s just that many cars today have TCS (Traction Control System) systems, which intervene after knowing that the tires are slipping through sensors to restore grip as soon as possible to ensure safety.

For fuel vehicles, TSC generally has the following methods, individually or in parallel to intervene in the vehicle:

  • Adjust the ignition of one or more cylinders of the engine;

  • Reduce the fuel injection volume of one or more cylinders;

  • If wired throttle is controlled, turn off the throttle input;

  • In a turbocharged engine, reduce the turbo pressure;

  • Brake single or multiple wheels.

To sum up, in fact, it is either to reduce the output of the engine or to brake the wheels to reduce the torque on the wheels; thus, the tires restore static friction from dynamic friction.

Note: The corresponding ABS (Auto Brake System, anti-lock braking system), that is, the braking torque is too large during sudden braking, and the pulse Release the brakes in order to reduce the torque on the wheels and realize that the tires recover static friction from dynamic friction.

(Front-wheel drive and left front wheel skid, single wheel braking, restoring grip to achieve steering)

For internal combustion engines, controlling power output is not simple, but for electric motors, it is very easy.

To put it simply, the four-stroke internal combustion engine requires a flywheel to ensure a large moment of inertia, which leads to a long time to reduce the output power; and the rotor of the motor has a very small moment of inertia, which can quickly reduce the power. In addition, the output power control of the motor is much more accurate than that of the internal combustion engine, so the TCS of electric vehicles is much simpler than that of fuel vehicles.

As for the brakes, there is not much substantial difference between the two. Both can be controlled more accurately and quickly through electrical signals.

However, the electric vehicle TCS, which has shortened the response time, still cannot keep up with the extremely rapid torque changes of the motor; the torque changes transmitted by the motor instantly make the entire TCS system always “lag” by half a step.

The actual driving experience is that when the tires encounter a road with a very low friction coefficient, when the switch is suddenly stepped on, the vehicle will “rush” first, the tires will slip, and then the power will be weakened. , Restore the grip, but keep repeating the process; just like two people playing an online game, the delay of one person is very high, and the “reception” made is always half a beat slow.

When such “stuck” and “panic” occur in the vehicle, if the driver is not very experienced, it is easy to cause panic and even make mistakes in dangerous operations.

There is no need to say more about electric vehicles becoming the mainstream. Afterwards, cheaper and cheaper electric vehicles have more and more power. If this problem is not solved, it will be a hidden danger for car owners or other vehicles or pedestrians.

Under this general trend and environment, Bosch and BYD have jointly developed and verified for 4 years and launched dTCS (distributed TCS,

Distributed Traction Control System); claims to be able to make the vehicle completely non-slip on low-attachment roads (water, snow, ice, mud, etc.).

After the author experienced in Bosch’s own test track, I couldn’t help but sigh at their technology research and development and the long-term vision they had 4 years ago. The most important thing is that this system only requires OTA to be implemented, and does not require hardware modification. That is to say, models equipped with Bosch brake systems such as BYD Han can have this function after a software upgrade.

In order to explain the differences in this system, we first need to add some knowledge. Generally speaking, TCS and ABS share the braking system and wheel speed sensor, so due to the specialization of the dTCS systemBoth the rights and the technical core are on the Bosch side. Naturally, its functions need to be implemented on vehicles with Bosch IPB (Integrated Power Brake), but in fact, this set of technical principles is not limited to Bosch’s IPB. .

In the ordinary electric vehicle TCS response process, the sensor (here in the IPB) transmits the signal to the VCU (Vehicle Control Unit, vehicle controller), and then transmits the signal to the motor MCU (Microcontroller Unit) after processing. Respond to the motor; each process takes 100ms. This length of time does not seem to be much, but for the motor, it is already “A thousand year later”.

The dTCS system of Bosch canceled the transmission of the VCU at this stage, redesigned the software part of the electronic and electrical architecture, and directly transmitted the signal to the motor MCU. The response time of the whole process was shortened by 10 times and achieved 10ms. .

Take the partner BYD Han EV as an example. During the interview driving on low adhesion roads, the electric gate was stepped to the bottom, and the author did not feel any abrupt sense of electronic intervention. In other words, at the moment of stepping on, dTCS immediately intervened in the work, limiting the power output and the torque on the wheels. The whole process was very smooth, and only the slower acceleration of the vehicle could be noticed.

Especially when the left and right tires are on roads with different adhesion coefficients, the dTSC system can keep the torque in a dynamic and stable condition without the author noticing it, maintain a stable grip, and drive smoothly.

According to the official statement of Bosch and BYD, the four-wheel drive version of Han EV equipped with dTCS can shorten the acceleration time of 0-50km/h on ice by 2s, and shorten the acceleration time of 0-60km/h on snow. About 0.8s; in the snow circle test, the maximum controllable cornering speed of the Han EV four-wheel drive version can be increased by about 5-10km/h.

Of course, the author was amazed, and carefully pondered the meaning behind the cooperation between Bosch and BYD to develop dTCS.

First, among the models equipped with the Bosch IPB system, BYD has the most attention and popularity in the market; Bosch’s system can upgrade the vehicle without changing the hardware by software upgrade, then When BYD Han EV produced such performance improvements, other OEMs had to buy from BoschBuy dTCS to enhance the competitiveness of your products.

Secondly, it took 4 years for dTCS to complete R&D and testing. The most critical part is the electrical and electronic architecture and software. The author has mentioned in many previous articles that in the era of electric vehicles, the key to the speed of progress is who holds the data. BYD is not the only company carrying the Bosch IPB system, but the three-electric system is completely developed and controlled by itself. Except for Tesla, BYD is currently the only one.

This means that when the system is undergoing R&D and testing, BYD does not need to find other suppliers to provide “black box” data, and can provide it completely by itself. This has shortened a lot of time and cost for Bosch to develop dTCS.

Note: Generally speaking, when the software and hardware are provided by the supplier, the data is semi-closed or completely closed and needs to be retrieved from the supplier Data, the communication cost during this period is very huge for the current development speed of the automotive industry.

So based on the above two points, Bosch’s choice of BYD for cooperation is an obvious win-win result.

But having said that, for most consumers, dTCS will only feel the safety and stability brought by this system in an emergency. Most of the time, the perception is not deep, so the improvement of product strength is not Not too big; in addition, because the patent rights and core data are in the hands of Bosch, more models with dTCS will definitely appear on the market, and BYD Han’s first-mover advantage may only last for 1-2 years.

But one thing is certain. As the innate advantages of electric vehicles are constantly being “excavated” by industry giants, it is inevitable that the performance of electric vehicles will beat fuel vehicles step by step in all aspects.

It is not the past brilliance of fuel vehicles that limits people’s imagination, but the speed at which the “big men” of the auto industry introduce more “black technologies”. When people are accustomed to all kinds of “black technology”, it is the season when people start to abandon fuel vehicles.