Zeros of sampled systems with Backward Triangle Sample and Hold realized by Zero Order Hold

For a controlled system, it is difficult to have desired control performance, with a non-minimum phase. The minimum phase can be reflected by the stability of zeros. In the previous works of literature has been shown that backward triangle sample and hold improve the stability of zeros of sampled control system compared with zero order hold. However, it is hard work to use the backward triangle sample and hold in practice. In this paper, an approximated method of using backward triangle sample and hold is proposed. The expression for sampling zeros and the theorem for its’ stability of linear control system is proved as the sampling period is small. The results of this paper show that the proposed method has the same advantages as the accurate one. Finally, a numerical example was provided to verify our results.