Similarities and differences between E-tron and Taycan inverters

Taycan powertrain assembly

Let's talk about the inverter design of E-tron and Taycan. There are several points that are different from our understanding:

1) The E-tron and Taycan use a similar inverter design, which is from Hitachi. There are great similarities between the front and rear axles and the two cars (400V and 800V).

2) The main difference between 400V and 800V is the modification of the IGBT power module (the withstand voltage of the IGBT chip is expanded from 700V to 1,200V). It is quite unexpected that other major components such as smoothing capacitors, motor controller motherboards, current sensors, etc. are developed as standard components. I would like to start from the inverter.

Note: The main source of information is the presentation on "High Voltage and High Power Density Technology for Automotive Inverters" at the Japan Society of Automotive Engineers. There is a special topic on these topics on Marklines.

Figure 1 Inverter developed by Hitachi for Audi

01. Similarities between E-tron and Taycan inverters

Let’s first list the similarities:

1) Both inverters were developed by Hitachi with the help of Audi and Porsche engineers

2) Both are done in a compatible way, as shown below, the Etron is installed through an integrated installation arrangement, and the Taycan is installed through a bridge, so that the same parts can be combined to obtain different drive axles

Figure 2: Front and rear axle inverters of E-tron and Taycan

02. Differences between E-tron and Taycan inverters

1) Parameters and usage

The E-tron inverter has a voltage range of 150V-460V, a maximum current of 530A for 10 seconds, a maximum continuous current of 260A, a power density of 30kVA/L, and uses three IGBT modules (power modules) inside.

Taycan's inverter covers a voltage range of 450V-850V, and is divided into two different types. Inverter 300 has three new IGBT power modules, with a maximum phase current of 335A for 2 seconds, a continuous working current of 190A, and a power density of 62.3kVA/L. Inverter 600 uses two IGBT power modules in parallel on the power unit (a total of 6), with a maximum phase current of 670A for 2 seconds and a continuous working current of 380A, both twice the former, and an output power density of 94.3kVA/L.

Figure 3 Inverter parameters

As shown in the figure below, the weights of the three inverters are 8kg, 7.4kg and 10.5kg respectively.

Figure 4 Two different models of Taycan

From the schematic diagram, there are differences in filter design and passive discharge resistors. The E-tron only has an active discharge circuit, while the Taycan also adds a passive discharge circuit. From the perspective of current amplification, the Taycan can be considered in parallel.

Figure 5 Inverter schematic diagram

In terms of the overall internal layout, since the Taycan needs to provide space for 6 IGBTs in a similar volume, the two have very different IGBT driver and control boards, IGBT layout directions (E-tron is lying, Taycan is standing), and busbar designs. Taycan's AC/DC terminals, signal terminals, and DC terminals at the opening of the power module use a structure with 2 positive and 2 negative poles alternately configured to reduce parasitic inductance by offsetting the magnetic flux caused by reverse transient current.

Figure 6: Differences in the layout of the two inverters

Summary: Porsche does use SiC devices, but the components are mainly used for charging. We can pay close attention to detailed information later. I personally feel that many aspects of Taycan have been compromised in the development of some technologies for mass production, with performance as the priority goal.