Control method and method for switching power grid driving of escalator into variable frequency driving

The invention discloses a control method and a device for switching power grid driving of an escalator into variable frequency driving. The method comprises the following steps: disconnecting a driving motor of the escalator with a power grid; sampling the two-phase current of a motor stator after disconnection time reaches a preset first time; computing the output voltage target value of an inverter unit through a following logic algorithm, and determining the frequency target value of the inverter unit; gradually transiting the output voltage of the inverter unit to the output voltage target value according to the output voltage target value and the frequency target value, so as to drive the motor and accomplish the switching of the escalator from power grid driving into variable frequency driving. According to the method, when switching is performed, the driving motor of the escalator is actively disconnected from the power grid, the current rotate speed of the motor is rapidly tracked, the switching from power grid driving into variable frequency driving is accomplished, the method is simple and practical, during switching, the current of the motor stator is stable, overcurrent cannot occur, the escalator is smooth in transition, and the method has good engineering practice value.