Introduction
Last weekend, I saw a series of introductions about different parts of Taycan, which was made by Porsche for its after-sales service. There were some interesting points in it, and I would like to introduce these details in a few parts based on the materials I received:
1) The design of high-voltage and low-voltage electrical systems of Taycan
2) The battery system and charging strategy of Taycan
3) The design of the whole vehicle thermal management system
4) The characteristics of the driving system
After reading these materials many times, I feel that the approach of German engineers to the development of electric cars is very distinctive. Of course, Porsche has no shortage of funds, so the cost structure of the PPE developed in collaboration with Audi will gradually go down over time, but it will take some time.
Note: I believe that Tesla’s greatest value actually lies in the iterative approach of combining powertrains, EE architecture, and software organically, creating many new things. However, there is a whole set of methodologies for designing cars in the engineering department, and many things may need to be changed. The most important thing is how to change them to meet the demands of the future.
Some features of the high-voltage part
Taycan is the first to implement an 800 V system, but in fact, Taycan considered multiple voltage systems in the design of the entire vehicle system, including 800 V (power battery), 400 V, 48 V, and 12 V (LFP battery). The two voltage platforms do not have batteries to buffer.
1) 800 V voltage and other voltage systems: Taycan has multiple voltage platforms, as shown below:
DCDC: This DCDC is interesting because it converts voltage to 400 V, 48 V, and 12 V.
Thermal management system: The air conditioning compressor is 400 V, and the PTC is 800 V.
The following picture may be clearer. The red parts are all 800 V, and the most important part is supplied to the front and rear inverters.
2) DCDC converter
This converts 800 V to 400 V, mainly to provide power to the air conditioning compressor. According to German engineer friends, the next-generation 800 V air conditioning compressor will be available, so this converter will be eliminated.
From an energy management perspective, it is necessary to manage the high-voltage battery, manage the 12V LFP battery, and coordinate the 48V load. The load balancing of multiple voltage conversions here is quite interesting. This control is placed in the gateway (Porsche’s gateway is actually integrated with the body, similar to ICAS1 in MEB, which has complex functions).
Note: When we analyze the details of MEB and PPE in the future, we can carefully organize the software details of these energy management systems.
Considerations for High-voltage Boost Converter Design
3) Charging Boost Converter
Thanks to this design, the working principle of Porsche Taycan’s 400V to 800V high-voltage charger is somewhat complicated, as shown below:
I used to think that this was a non-isolated, adjustable voltage DCDC product. In reality, it is a charging pump that uses high-frequency switching to double the voltage. The characteristic of this pump is that it does not require a coil. It simply tells the external DC charging station what half of the actual desired voltage is and then pulls it back with the voltage pump.
The charging pump principle uses a 60 Hz control frequency to first charge the circuit to C1 and C2, and then series-connect C1 with the voltage source to reduce the output voltage by twice the voltage minus the diode drop.
Summary
After reading this material, we can learn that there were many trade-offs involved in Taycan’s selection of 800V technology.
This article is a translation by ChatGPT of a Chinese report from 42HOW. If you have any questions about it, please email bd@42how.com.