Luenberger observer in state space

I am trying to build a Luenberger observer for my state-space model.

For the Luenberger observer I need my state space in the form of;

xdot = Ax + Bu + L(y-Y)

y = Cx+Du.

Does anyone know how to implement this in my current state space model and how I can solve that state space so the results can be compared between the normal state space and the one with an observer?

Ts = 1;
R0_bat = 0.01196;
R1_bat = 0.0110;
R2_bat = 0.0076;
C1_bat = 1.2818*10^4;
C2_bat = 297.6403;


A_statespace_terminal = [1-(Ts/(R1_bat*C1_bat)) 0 0; 0 1-(Ts/(R2_bat*C2_bat)) 0; 0 0 1];
B_statespace_terminal = [Ts/C1_bat; Ts/C2_bat; Ts/(3600*Capacity_true)];   %12.5Ah  = 12.5*3600 As
C_statespace_terminal = [1 1 alpha_affine];
D_statespace_terminal = R0_bat;

state_space = ss(A_statespace_terminal, B_statespace_terminal, C_statespace_terminal, D_statespace_terminal, Ts);

[Y_sp_out, time_vector]=lsim(state_space,pulse_discharge.amps,pulse_discharge.time);
V_sp = Y_sp_out + (alpha_affine+beta_affine);