Pierburg GmbH, part of the KSPG Group, has developed an electric compressor for spontaneously boosting the charge pressure of engines fitted with an exhaust-gas turbocharger. This component allows pressure to be increased regardless of the exhaust-gas energy availability.
The compressor is compatible with both gasoline and diesel engines. Initial prototypes are now being tested by various customers. The electric compressor fits in well and without any constraints with the proven strategy of downsizing, the company said.
In contrast to the conventional exhaust-gas turbocharger, which is powered by the energy of the exhaust gases, the electric version responds immediately thanks to the practically instantaneous build-up of charge pressure. This makes it a suitable alternative to multi-stage exhaust-gas turbochargers, which are often very costly and bulky.
The electrical energy needed to boost the charge pressure can be sourced completely or in part from recuperated brake energy which, in turn, leads to another efficiency gain.
The electric compressor has a wear-free, brushless DC motor that was developed using Pierburg’s own longstanding experience in the development and production of electric motors. The motor and the electronic components are cooled by a water jacket connected to the engine cooling system.
Other areas of emphasis in the development work were to reduce the mass inertia of the rotating parts in order to shorten response time, and to comply with set limits for noise emissions and electromagnetic compatibility.
One special challenge was to achieve the required endurance strength for the individual parts. This is especially relevant regarding the configuration of the roller bearings and the sealing of the motor and electronic compartment to prevent the ingress of oil and soot. To this end, Pierburg has integrated an efficient sealing system to ensure maximum protection against premature compressor failure due to contamination.
The electrification of auxiliary assemblies on internal combustion (IC) engines poses rising demands on available electrical energy. In this context, an increase in the on-board system’s supply voltage from 12 to 48 V is frequently discussed and has been announced by some automakers, such as Audi. Given the reduction in current accompanying the increase in voltage for the same power requirement, it will in the future be possible to use very high-power components such as electric motor-driven compressors for boosting charge pressure.