Week 9 Challenge

Energy management system Flowchart to select the battery, Fuel cell, or Ultracapacitor.

The energy management strategy is selecting the energy from Battery, Ultra Capacitor (UC), and Fuel cell based on the power demand from the vehicle.

The flowchart is developed based on the requirements of the vehicle. The power demand is varying from 0 KW to 55 KW. At different power stages, different power sources are being used which is detailed in the flowchart.

The analysis is as follows:

• Case0: Power demand is less than 23 KW. Then Battery checks the State of Charge (SOC) limit of the battery and if SOC is above the minimum SOC level, then Battery is used to propel the vehicle.
• Case1: power demand is to accelerate and the vehicle moves forward with power. The power demand range is between 23KW to 55 KW.

Then the Fuel cell is used to propel the vehicle.

• Case 2: Power demand is not in the range of 23KW to 55 KW and UC SOC is high to its limits, then use Ultra Capacitor to Propel the vehicle.
• Case 3: Power demand is not in the range of 23KW to 55 KW and UC SOC is low to its limits, and if battery SOC is also less than the minimum level, then use a Fuel cell to propel the vehicle.

To satisfy the above-said cases, a MATLAB model is developed.

The signal builder block is chosen to develop the power demand.

The signals in the signal builder block vary the power demand of the vehicle from 0 to 60000K. Based on the power variations/ demand, different energy sources are chosen in the Energy Management Strategy.

Different cases of the limits are shown below through the Interval test blocks.

Result analysis:

Detailed results of all the energy sources are shown below.

• The power demand curve which is pointed in yellow color shows the different power demands at different times.
• FC_power plot which is a blue curve shows the switch on and off period of the Fuel cell. This is satisfying the condition that the FC is on when the power demand is from 23000W to 55,000 W.
• The green plot shows that the Ultracapacitor is turned on when the power demand limits exceed 55,000W.
• The Battery_power plot which is in dark green shows the on-off period when the power demand is below 23,000w.