Today is the third article in the series “Functional Allocation of Tesla Model 3 from Controller Pin Definitions” – “FBCM”. Without further ado, let’s get straight to the point.
1. In-Vehicle Network
3 routes of CAN, 4 routes of LIN. Although it does not compare to LBCM (5 routes of CAN, 4 routes of LIN) and RBCM (10 routes of CAN, 14 routes of LIN, with ultrasonic radar occupying 12 routes), it is still a considerable amount of resources; it basically encompasses the controller nodes in the front compartment – Homelink located at the front, as shown below.
Figure 1. Homelink ECU Location
2. Low-Voltage Battery
…the delicate low-voltage battery. Based on the interface, it is inferred that the battery voltage sampling circuit is integrated into the FBCM board – the temperature sensor must be placed at the battery end, but the voltage and other sampling may not be necessary.
3. Power Distribution
Although the power distribution list looks complicated, you can actually focus on two main lines: the first is the front compartment, which distributes power nearby, and the second is LBCM/RBCM – FBCM completes the primary power distribution hub, while LBCM/RBCM completes the secondary power distribution, which we will look at in detail later.
In fact, a reverse engineering report from Caresoft a year ago referred to it as PDU (Power Distribution Unit), probably because at that time it was traditionally perceived as just a fuse box. Now everyone knows: FBCM not only realizes power distribution but also drives (at least) functions related to the front compartment and even logical processing (speculated).
4. Accessories & Front Trunk
5. Grille
Closed front face, active air intake grille, interesting.
Figure 2. Active Grille Shutter
6. Air Conditioning & Thermal Management
Combined with the blower from LBCM,
and the HVAC in the passenger compartment from RBCM,
The air conditioning and thermal management of Model 3 are quite comprehensive.
7. External Lighting
This is the hardware interface, and there are also LIN communications directly connected to the FBCM for the left and right front combination lamp control modules.
Figure 3. Active Grille Shutter
8. Steering & Braking
Wake-up output (traditional IGN) and sensor signals, nothing much to say.
…
Next, we need to fill in the gaps left by the previous article,
…In the next article of the series “FBCM”, we hope to sort out the overall power distribution of the vehicle…
Before discussing, let’s align our starting point.
As we all know, the power distribution of the entire vehicle covers a very wide range, from controllers (logical power, driving power, wake-up signals – such as KLR, KL15, etc.), to sensor, switch pull-up, actuator power supply, to load power supply, driving… can all be included; however… organizing this way would be quite a task, haha, let’s simplify it – without affecting the analysis results – just look at the power supply of the controllers.
Figure 3. Tesla Model 3 Network Topology
In fact, this diagram already organizes the power supply information of the controllers:
Red block – battery and DCDC;
Purple block – FBCM;
Green block – LBCM;
Blue block – RBCM.
For better understanding, we also created a schematic diagram as follows,
Figure 4. Tesla Model 3 Controller Node Power Distribution
From the above, it is not difficult to see that,
1. All power distribution goes through FBCM;
2. Divided by area, front compartment, left, right;
3. FBCM belongs to primary distribution, LBCM/RBCM belongs to secondary distribution, and the two together complete the power distribution of the entire vehicle, basically following the principle of “nearby distribution”.
…Additionally, discussing power distribution cannot overlook the eFuse used in the Tesla Model 3, but… I haven’t fully understood it yet [laughing cry],
1. Model 3 does not have a traditional fuse box;
2. It uses a sufficient number of Power Mosfets, mainly three models from On Semiconductor, as seen in the following diagram:
Figure 5. Distribution of Power Mosfets on FBCM/LBCM/RBCM Boards
3. RBCM provides an eFuse Lockout to FBCM, but no corresponding eFuse chip (e.g., On Semiconductor NIS5020?) has been found on FBCM? How to implement diagnostic functions beyond on/off control? What is the relationship with On Semiconductor’s Power Mosfets?
Welcome to discuss.
Alright, those interested in the complete pin definitions of the Tesla Model 3’s FBCM can reply “FBCM” in the backend to obtain.
Who is Cold Winter Melon?
A half-baked automotive electronics engineer, a funny dad; an egomaniac, a low-quality content creator.
Welcome to find me on Weibo/Zhihu/WeChat/Toutiao, let’s accelerate the transformation of cars towards electrification/networking/intelligence/sharing together!
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