Control

The ELFA drive system is adapted to the needs of the vehicles in a modular way and therefore guarantees the highest amount of flexibility. The energy supply system, the mechanical integration and the necessary control software can be adapted according to the individual needs of the customer and different bus sizes.

The control software is organized in two essential modules, the software which is close to the inverter and therewith the control software which is close to the drive on the lower level and the system software on the upper level. The inverter software is integrated directly into the inverter, and fulfils different tasks in the drive applications with a high efficiency and reliability. Different applications like the control of drive motors, generators, DC/DC-inverters or auxiliary motors or the generation of a single or three phase system is modularly realized in a single software. The different applications can be calibrated by using parameter settings, which dependent on the application. The motors and generators can be operated in a torque and/or speed control mode. The auxiliary motors can be operated with a frequency or speed control mode. Besides these basis functions, software routines regarding a safety concept and limited operating strategies are implemented as well.

The communication to the upper level system software and between the different inverter software modules is based on a newly developed CAN-bus protocol named DCAN (Drive CAN). The system software runs at an individual hardware with the name DICO (Digital Input Control). The system software includes the customer specific interfaces to the vehicle and to the lower level inverter controls. In addition to that the module drive control, hybrid control and the safety software concept are integrated. Next to the binary and analogue input and outputs a CAN bus based protocol can be used too as the vehicle interface. The CAN-bus is customer specific and based on the standardized CAN protocol J 1939. As shown in the following picture, the communication with the drivers panel (EVCU), with the internal combustion engine control (ECU), with the electronic brake system (EBS, ABS/ASR) and with the battery management unit (BMU) is realized with the vehicle interface.

Customer specific routines are integrated into the CAN module on the vehicle side. Together with the standardized software modules the drive control, the hybrid control and the safety software build the complete system control. The drive control gets the setpoint values of the throttle and brake pedal and the direction command. It takes into account the internal and external system limits and determines torque and speed setpoint values for the different motors, generators and auxiliary systems. The drive control calculates the necessary system power as an input for the hybrid control. The energy management software of the hybrid control determines the power distribution between the internal combustion engine and the energy storage device for the different operations and applications. This is optimized according to different criteria. The control works with all the different drive system types, i.e. diesel electric and pure fuel cell systems, hybrid systems with internal combustion engines or fuel cell or battery systems. The drive and hybrid control can be parameterized in their standard versions and therefore offer an extremely flexible utilization.