The new PPE (Premium Platform for Electricity) platform is the basis on which some of the Volkswagen Group’s 100% electric cars will be based. The first are the Porsche Macan, the Audi Q6 e-tron and the Audi A6 e-tron, but more models should be coming because the idea is to be able to sell vehicles with this propulsion system profitably while maintaining high quality standards.
Designed by both companies, the PPE platform offers several advantages:
- Design versatility: It is possible to vary the wheelbase, track width and ground clearance. This allows for different models in different segments, allowing each brand to retain its character.
- Mechanical variety: It supports rear-wheel drive and all-wheel drive (with motors on both axles of different outputs), as well as a fully variable electronic rear differential lock. The choice is made of permanent magnet motors (PSM) with hairpin winding, where the rotor is equipped with magnets that generate a natural magnetic field. They offer more power and torque than asynchronous motors (ASM), are more efficient and have a greater recuperation capacity – so that acceleration is available several times in a row. Audi estimates that the new electric motors for the PPE require around 30% less installation space and weigh around 20% less.
- Power electronics: It uses silicon carbide (SiC) instead of silicon as the semiconductor material in the rear axle pulse-drive (PWR) inverter. This significantly reduces losses in the inverter and allows higher frequencies.
- High voltage: The 800-volt high-voltage architecture ensures consistently high performance, significantly shortens charging times and reduces both the weight and space required for cables. They are equipped with batteries with a capacity of around 100 kWh and twelve modules with prismatic cells. The nickel-cobalt-manganese ratio is 8:1:1 for increased energy density.
- Greater recharging capacity: It supports an even higher charging power than the 270 kW of the Taycan. Note that if a 400-volt charging point is reached, it splits the battery into two parts with a nominal voltage of 400 volts to charge in parallel, aligning the charge levels of the two halves of the battery if necessary. In 21 minutes it can go from 10% to 80% charge.
- Space saving: The Integrated Power Box system reduces costs, in addition to the necessary cables and weight. It makes better use of space by combining the built-in alternating current (AC) charger, the high-voltage heater and the DC/DC converter.
Audi estimates that the efficiency measures around the new electric motors for the PPE enable an extra 40 km of range compared to the first generation of the Audi e-tron. In addition to saving weight, they have significant improvements:
- Hairpin windingFor example, the proportion of space occupied by copper windings in the slots in which they are housed has increased to 60%, compared to 45% for conventional windings.
- Electric oil pump in the transmission: Thanks to the cooling of the rotor oil, it has been possible to do without the use of heavy rare earth elements, increasing the power density by 20%.
- Power electronics: The inverter controls the electric motor and converts the direct current from the battery into alternating current. The data is controlled by the HCP1 (High-Performance Computing Platform1) domain computer, which is responsible for the drive system and suspension. In the most powerful version, silicon carbide semiconductors are installed, which are 60% more efficient and more reliable under partial load. This gives a range gain of 20 km.
- Thinner cables: The 800-volt architecture allows for the use of thinner battery and electric motor wiring. This reduces installation space, weight and raw material consumption. The system runs cooler due to reduced heat loss, so the cooling system is smaller and more efficient.
- Intelligent thermal management: In addition to the 800-volt architecture for fast charging, predictive thermal management plays a role. Using data from the navigation system, route, departure timer and usage behaviour, the need for cooling or heating is calculated. If the cooling or heating mode is selected, the efficiencybattery conditioning is activated later, to increase the actual autonomy based on driving. And in the mode dynamicdesigned to achieve the best performance, if traffic does not permit it, the use of energy for battery conditioning is minimized. And the battery temperature is monitored throughout its useful life, even when the vehicle is stationary.
- Air conditioning: To compensate for the increased efficiency of the drive system and the resulting reduction in heat losses, the water-glycol heat pump is supplemented by an air-source heat pump. In addition to the waste heat from the coolant of the electric motor and other components, ambient air can also be used as a heating source.
- Energy recovery: With PPE, around 95% of the entire braking process in everyday driving can be handled by regenerative braking using the electric motors. The recuperation function is no longer managed by the brake control system, but by the HCP1, one of the vehicle’s five high-performance computers. As it is also responsible for the drive system and suspension, the influence of the drive system on the braking system is increased. The Intelligent Brake System (IBS) has been improved and can now combine axle-specific braking powers.
