Alternator Charging and Power Distribution System with Load Manager

Datsen Davies Tharakan

Introduction:
This example shows a typical automotive charging and power distribution system. An automobile under extreme operating conditions (like night driving in rainy and dense traffic) can consume a lot of electrical energy. Therefore, the alternator and the battery need to be adequately sized for meeting the vehicle's electrical loads under extreme conditions without draining the battery.

Circuit Snapshot:
Refer to the attached snapshot "charging_system_load_manager.png".

Details:
This example illustrates the alternator charging and power distribution system under a worst-case driving condition (high load demand and low vehicle speed) using a lead acid battery with typical electrical loads and some self-heating wire harness considerations. In this scenario, the Battery SOC will keep reducing as the electrical load demand is very high and the vehicle speed is low throughout the driving cycle. If such driving conditions continue for a prolonged period, the battery might be discharged completely. In such conditions, some possibilities that could be employed to keep the battery SOC healthy are to increase the battery size, and/or generator size, and to employ a load-management scheme.
In this example a load-management scheme is implemented. The StateAMS tool in SaberRD is used to create the load manager.
The load manager calculates the battery SOC dynamically when the simulation is in progress and shuts down some of the loads dynamically if the SOC goes below the set threshold. When the SOC regains a value little above the set SOC threshold value, the designated load is turned ON again. In this example, the heater loads ON/OFF status is controlled by the STATE AMS based load manager model. The electrical loads were modeled using load building blocks from the SaberRD parts library and using the "Load Profile Editor" tool in SaberRD. An arbitrary load profile was set up to switch the electrical loads "ON" and "OFF". A standard, typical, city drive cycle is being used from the "Drive Cycle Editor" tool to evaluate the system performance.

Please refer to the attached "README" zip file for usage notes and for further details about this design example. Also the associated Saber files are enclosed in Alternator_charging_system_with_load_manager.

Note:
This design works only in SaberRD Commercial Edition