正弦电压U的最大值为311V,初相位为负60,求它的瞬时值解析式,并写出t=0.0025时的瞬时值.
问题描述：
正弦电压U的最大值为311V,初相位为负60,求它的瞬时值解析式,并写出t=0.0025时的瞬时值.
答
U = 311sin(100πt + π/3) = 220√2sin(100πt + π/3)
当t = 0.0025时，
U = 3220√2sin(π/4 + π/3)
= 220√2[sin(π/4)cos(π/3) + cos(π/4)sin(π/3)]
= 220√2[(√2/2)(1/2) + (√2/2)(√3/2)]
= 110(1 + √3)
≈ 300.53(V)
答
最大值：Um = 311 初相位：φ = - 60 * 2Π / 360 = - Π / 3 频率：f = 50 (假设） 角频率:ω = 2Πf = 100 Πu = Um sin (ω t - Π / 3 ) = 311 sin (100 Π t - Π / 3 ) t = 0.0025 u = 311sin (100 Π * 0.002...