通用串行总线（USB）作为一种新的微机总线接口规范，具有便捷、易扩展、低成本、低干扰等优点-Universal Serial Bus (USB) as a new computer bus interface specification, with convenient, easy expansion, low-cost, low interference, etc.

Multivariate least squares fitting method of nonlinear equations, esprit algorithm signal frequency interference can be assessed Based on SVPWM three-level inverter matlab simulation.