E-buses: How auxiliary drives protect the environment

T6 system from KEB for integration of up to six inverter modules

Conventional vehicles in urban traffic consume a large part of the energy for the auxiliary drives alone. In order to save emissions and costs, KEB Automation uses an inverter system for the electrification of air compressor, power steering pump and co. This enables buses to reach a new level of sustainability.

Electromobility can contribute to significant CO2 savings and pave the way to climate-neutral transport. More and more consumers are turning to environmentally friendly modes of transport. And a change is also taking place in the area of commercial vehicles and mobile machinery. In addition to the main drives, electrification also affects the auxiliary drives in the vehicle, which include power steering pumps, air compressors, ventilation systems, CO2 heat pumps, transport cooling systems, hydraulic pumps and generator applications.

Electrified power take-offs are highly efficient, require comparatively little maintenance, are simple in design and are convincing in terms of torque output and low operating costs. In addition, users benefit from compact dimensions, low noise levels and reduced energy consumption, which increases the range of an electric bus, for example.

Inverter system with integrated UDS features

For reliable operation of the auxiliary units, KEB offers the appropriate drives, controls and software solutions from a single source. For example, the T6 APD is a scalable and modular inverter system with integrated power electronics, intelligent mobile control unit and EMC filter solutions. The T6 system can be flexibly adapted to different vehicle requirements and enables the integration of up to six inverter modules, which are available in three power levels with rated output currents of 16.5 A, 33 A and 60 A. Two CAN ports are available for communication, supporting all common CAN protocols such as J1939, CANopen, UDS (Unified Diagnostic Services) and many more.

“The software of the T6 APD is modular and customisable. Users can choose from a pool of different apps for each inverter output. On the one hand, generic apps from KEB are available, but also apps directly from the aggregate manufacturer,” says Boris Schneider, team leader for the E-Mobility application area at KEB. With the latest software version, the T6 APD now also supports the UDS diagnostic protocol on the CAN bus. Based on a collection of different services within the protocol, almost all available parameters can be read and written. Error memories can be read out or deleted. It is also possible to transfer files and software via the UDS interface. 

The electrification of buses marks a step towards climate-neutral mobility. Especially in urban traffic, advantages such as the quiet operation of the auxiliary units come into their own. A better driving experience due to significantly less noticeable vibrations in the interior and the overall increased efficiency are further aspects that speak for the electrification of main and auxiliary drives.