How to calculate cumulative sum based on pattern in Matlab?

I am trying to simulate battery level of electric car (EV) based on driving and parking patterns from dataset table. Basically, I have driving/parking duration(time intervals), starting battery capacity of EV(SoCin), distance travelled with car energy consumption rate while driving, and charging speed. Here how data looks like:

%%CONSTANTS
energy_con = 6; charging_rate = 4; SoCin = 35; SoCfull=41;
%% TIME INTERVALS
start_time ['00:00' '06:30' '07:00' '16:15' '17:45']
end_time  ['06:30' '07:00' '16:15' '17:45' '23:59']
%% VARIABLES 
pattern = [p d p d p]  % parking/driving pattern
duration = [6.5 0.5 9.25 1.5 6.25]
distance = [0 15 0 25 0]

By idea, it should charge while parking if SoC level lower than full capacity(charging_rate multiplied to parking time), and discharge while driving with the rate distance*energy_con.

I am a newbie to Matlab, but I have tried following:

timediff = duration*60; % time of end and start time difference in minutes
singularvalue = d./timediff; % value per hour
MinScale = zeros(24*60+1,1);   % from 1 to 1440 scale is created to simulate day      
                                 % in minutes (+1 is for to avoid 0 values in  
                                 % time)
traffic_DCH = zeros(24*60+1,1);  
e_con = zeros(24*60+1,1);
%% INTERVAL SPREAD
for i = 1:length(end_time)
    [~, ~, ~, H, MN, ~] = datevec(start_time(i));
    TrSt = H*60+MN+1;
    [~, ~, ~, H, MN, ~] = datevec(end_time(i));   
    TrEn = H*60+MN+1;
    if isnan(TrEn) || isnan(TrSt)
        continue
    else
        while SoCin < SoCfull 
           if pattern == 'p'
               e_con(TrSt:TrEn,1) = e_con(TrSt:TrEn,1) + cumsum(ch_rate./timediff(i));
           else
               e_con(TrSt:TrEn,1) = e_con(TrSt:TrEn,1) - cumsum(econ_rate*singularvalue(i));% 

           end
        end
    end
end

%TIME AXIS
close all
TimeM = 1:length(MinScale);
TimeH = TimeM/60;

figure
hold on
plot(TimeH,traffic_DCH)
xlim([1 24])
xlabel("Time (h)")
ylabel("Distance travelled (km)")
grid on

figure
% hold on
plot(TimeH,e_con)
xlim([1 24])
xlabel("Time (h)")
ylabel("SoC (kW)")
grid on

Code might be very bad I admit, it's only showing instant decrease or increase instead of contionous minute by minute change for example when driving or charging. Maybe there is an another approach to it, any help would be much appreciated.

Answer 1

[Pranjal Kaura]

Hey,

It’s my understanding that you want to use parameters like energy_con, charging_rate, duration, pattern etc to simulate the battery level of a car.

I have assumed that the charging and discharge rates are per hour and the units of charging_rate and SoCin/SoCfull are identical.

Problems in your code:

1. Error in while loop, it will never exit as SoCin and Socfull are not getting updated inside the loop.
2. Instant decrease or increase in the final graph is because you are assigning all the values in the duration [TrSt:TrEn] with the value of the battery at the TrEn.
3. Incorrect usage of hold on commands
4. There is no usage of traffic_DCH in your code and thus I have commented it out

Here's the updated code for simulating and anaylsing the battery levels of a car.

energy_con = 6; charging_rate = 4; SoCin = 35; SoCfull=41;
%% TIME INTERVALS
start_time =  ["00:00", "06:30", "07:00", "16:15", "17:45"];
end_time   = ["06:30" "07:00" "16:15" "17:45" "23:59"];
%% VARIABLES 
pattern = ["p" "d" "p" "d" "p"];  % parking/driving pattern
duration = [6.5 0.5 9.25 1.5 6.25];
distance = [0 15 0 25 0];

timediff = duration*60; % time of end and start time difference in minutes
singularvalue = distance./timediff; % value per hour
MinScale = zeros(24*60,1);   
% traffic_DCH = zeros(24*60,1);  %commented it out, because hasnt been used
% in code
e_con = zeros(24*60,1);
e_con(1) = SoCin; %starting charge/level of the battery

for i = 1:length(end_time)
    [~, ~, ~, H, MN, ~] = datevec(start_time(i));
    TrSt = H*60+MN+1;
    [~, ~, ~, H, MN, ~] = datevec(end_time(i));   
    TrEn = H*60+MN+1;
    if isnan(TrEn) || isnan(TrSt)
        continue
    else
        if pattern(i) == 'p'
            for j = TrSt:TrEn  %for loop to iterate over the timings when the car is parked and update the battery level based off 
                %the previous battery level.
                   e_con(j, 1) = min(e_con(max(j - 1, 1),1) + charging_rate/60, SoCfull);
            end
        else
             for j = TrSt:TrEn
                   e_con(j,1) = max(e_con(max(j - 1, 1),1)  - energy_con/60, 0);%energy_con/60, because rates are hourly
            end
        end
    end
end

close all
TimeH = (1:length(MinScale))/60;
% figure
% hold on
% plot(TimeH,traffic_DCH)
% xlim([1 24])
% xlabel("Time (h)")
% ylabel("Distance travelled (km)")
% grid on
% hold on
figure
plot(TimeH,e_con)
xlim([1 24])
xlabel("Time (h)")
ylabel("SoC (kW)")
grid on

[Asrorkhuja Ortikov]

Yes, @Pranjal Kaura your statements are right. This code works like a charm now. I was confused by iteration loops between loops interval. Now I have got it. Thanks a loooooot !!!!!!!!