Adaptive frequency extraction from a signal which has a frequency varying component

I have a signal y which has 3-4 different frequency components. The frequency of one components is varying with time as given in the following code as y2 (5-15 Hz).

 Fs=1000;
Ts=1/Fs;
t=0:Ts:2;
fend=15;
f0=5;
f=f0+t*(fend-f0)/2;
y1=10*sin(2*pi*50*t+0);   % fundamental frequency
y2=1*sin(2*pi*f.*t+0);   % variable 5~18 Hz
y3=1*sin(2*pi*93*t+0);   %  93 Hz
y=y1+y2+y3;   % signal

The signal y may contain other harmonic frequency components.

My question is; how can I extract the variable frequency component from signal y. I dont have the information of a desire signal, I dont want to remove y2 but to extract it from y. Can you anyone suggest me some techniques or filters which can do this job. Thanks