基于电机闭环系统辨识的数字前反馈控制。采用零相差前反馈控制器，实现系统在全频范围内相移为零，系统输出高精度地跟踪输入指令。-Motor closed-loop feedback control based on system identification numbers before. Using zero difference before feedback controller, the system in the whole frequency range of the phase shi