Take A Look Into How Porsche’s Electric Motors Work In Detail!

The Porsche Taycan Turbo S is renowned for its performance, thanks to it’s unique drive technology which allows the vehicle to unleash its collective torque of 12,000 Nm of all four wheels at once without any delay. 

It’s no coincidence that the Center of Automotive Management (CAM) has declared the taycan as the world’s most innovative model in 2020. With the current ability of the vehicle, it is not a difficult task at all to exploit the potential innovation of the electric drive unlike anything before. 

This concept has been around for almost 120 years, going back to when a young Ferdinand Porsche scored a world first with the development of electric vehicles with steered wheel hub motors. Combining the thrust from the two electric motors on the front and rear axles result in an astounding top speed while becoming the world’s first all-wheel-drive passenger vehicle. 

For Porsche, the company has made use of the permanently excited synchronous machine (PSM) which offers higher continuous output compared to the cheaper asynchronous machine (ASM). This is possible as the PSM overheats less easily which therefore does not have to be turned down. Porsche’s PSM is controlled and supplied via power electronics with three-phase AC voltage, whereby the pulse inverter sets the frequency of the rotating field in the stator and regulates the speed of the rotor for Taycan motors. 

The Porsche gene is reflected in a special feature of the Taycan motors known as the hairpin winding. Here, the stator coils consist of rectangular wires and not rounded. Unlike the classic winding processes, hairpin technology is known as a forming-based assembly process. The rectangular copper wire is divided into sections and bent into a U-shape, similar to a hairpin. These hairpins are then inserted in the stator laminations in which the winding is mounted with the surfaces of the cross-section lying on top of each other.

A decisive advantage form the hairpin technology is that it allows the wires to be densely packed, adding more copper to the stator. The technology also has a fill factor of almost 70 percent, which is 20 percent more than the conventional winding method. This results in an increase of power and torque with the same installation space. 

Another advantage of the hairpin technology is the homogeneous contact between adjacent copper wires which improves heat transfer while ensuring the hairpin stator can be cooled efficiently. It is important for the motors to have a cooling water jacket as over 90 per cent of energy is converted to propulsion in the electric motors, which also releases heat that needs to be dissipated. 

It is also vital for the power electronics to identify the exact angular position of the rotor in order to control a permanently exciter synchronous motor. This is where a resolver steps in, which consists of a rotor disc made of field-conducting metal, an exciter coil and two receiver coils - The exciter coil generates a magnetic field transmitted via the encoder to the receiving windings, which induces voltage in the receiving coils resulting in the control system to calculate the exact angular of the rotor’s position. Also known as the pulse inverter, it converts the battery direct current at 800 volts into alternating current and supplying it to the two e-motors. 

Porsche was the first manufacturer to ever implement a voltage level of 800 volts, which was originally developed for the Porsche 919 Hybrid race car. With the voltage level, it has reduced the weight and installation space in series production which enables shorter charging times. The result? An electric motor that goes up to 16,000 revolutions per minute.

Not only that, it is also important to ensure the front and rear drive units have their own transmission. With two transmissions, drivers can make optimum use of this speed range for Porsche’s signature spread between dynamics, efficiency and top speed. The Taycan is the first electric sports car to have a transmission with two shiftable gears on the rear axle, with the first of which having a short reduction ratio while an input planetary gearbox transmits power to the wheels on the front axle.

This results in a state-of-the-art Tacan Turbo S which translates 440 Nm generated by the electric motor to approximately 3,000 Nm for the front axle and 610 Nm to about 9,000 Nm of axle torque to the rear axle. The task of the longer-ratio second gear is to ensure power and efficiency reserves at high speed. 

With pioneering technology applied to the smallest details, Porsche is striving to continue it’s traditions of innovation in the age of the electric drive.