Challenge

Week 8 Challenge

PPratik Joshi11 Jul 2022

Aim: To built Ultracapacitor model.

Batteries and ultracapacitors are complementary technologies: batteries provide energy for the long term while ultracapacitors provide the fast reaction and high power. Together, ultracapacitors and batteries are the future of electrification.

STEPS TO CONSTRUCT UC MODEL:

Three equations in UC model are defined first which gives us SoC, current and OCV.

This are the three parameters which influences UC.

OCV defines the SoC of Ultracapacitor

Max Voltage or Voltage is directly proportional to the charge stored in the battery. • Amount of charge is directly proportional to the current that can flow in the circuit.

SOC= f(I*n)/Qdt

Where

n is the Coulomb efficiency.

Q is the electric quantity or charge on UC.

I is the current.

Q=C*OCV

Q depends on capacitance which is the charge storage capacity measured in measured in Farads

The OCV is a measure of the electric field between plates

OCV = ∫(I/C)dt

Capacitance and OCV gives 'Q'

The integration of current over 'C' gives 'OCV. In UC model calculation for current and SoC are done as said below. Firstly the current consumed is calculated which is fed into a SoC calcultaion block.

The SoC is then calculated based on the amount of current drawn and pushed back into the UC.

Hence fomula for current is given as:

I = SOC*Vmax-sqrt(SOC*Vmax^2 - 4*R*PUC*n)/2*R

Where

Ris the lumped resistance

Vmax is the max. voltage:

n is the efficiency during the charge-discharge cycle. PUC is the power demand which is to supplied by UC and it is the first input in this model

which basically comes from Energy management systems.

As per the equation discussed above the model is constructed and its shown below

Opening it we get the following model:

WORKING OF MODEL

1. PUC is our input here which is nothing but the Power demand for the UC. 20K watts is the value. In a complete Fuel cell or lectric vehicle model it comes from the EMS (Energy management system) block. This input goes inside the Current calculation block. With that inside of Current calculation block is shown.