导函数f’(x)=-3x^2+6x+9=-3(x+1)(x-3),
∵-2≤x≤2,
∴-2≤x≤-1时,f(x)递减,
-1≤x≤2时,f(x)递增.
∵f(-1)=1+3-9-d=-5-d,
f(-2)=2-d,
f(2)=22-d,
∴22-d=20,∴d=2,
∴最小值=-5-d=-7