The invention provides a method, device and
system for controlling a PMSM (
Permanent Magnet Synchronous Motor) to put into operation again at the
belt speed. The counter EMF of the PMSM is obtained by the speed of a trailer, and is compared with the
voltage on the
inverter side, if the counter EMF is higher than the
voltage on the
inverter side, the PMSM is not allowed to be put into operation again at the
belt speed, otherwise, the PMSM is put into operation again at the
belt speed. When the PMSM is allowed to be put into operation again at the belt speed, a separation
contactor is closed; when the PMSM is not allowed to be put into operation again at the belt speed, the separation
contactor is switched off. Therefore, the method, the device and the
system can be used for computing the rotor position angles through dividing the working conditions into low-speed working conditions and medium-high speed working conditions according to
Omega e, and the PMSM is started through the rotor position angles; the overall control method is provided from the view of
system, the PMSM at the high speed section is not allowed to be put into operation again at the belt speed, the position for the PMSM at the medium-high speed section to be put into operation again is determined through adopting a one-step short-circuit method to compute the rotor position angles, the position for the PMSM at the
low speed section to be put into operation again is determined through adopting an INFORM (Indirect Flux detection by On-line
Reactance Measurement) method to compute the rotor position angles.