Controller of electrically controlled three-speed medium voltage motor and operation mode of controller

The invention discloses a controller of an electrically controlled three-speed medium voltage motor and an operation mode of the controller. The controller comprises a controller body, a main control valve, a high speed switching valve, a low speed switching valve, a safety tension valve, a balance valve and a one-way valve, wherein the main control valve, the high speed switching valve, the a low speed switching valve, the safety tension valve, the balance valve and the one-way valve are arranged inside the controller body; the high speed switching valve, the low speed switching valve are pilot control type valves; the high speed switching valve comprises a high speed electromagnet; the low speed switching valve comprises a low speed electromagnet; and the safety tension valve comprises a safety electromagnet and a proportion electromagnet. When the controller is used, hydraulic oil outflows from the oil outlet of the main control valve; then the low speed switching valve and the high speed switching valve are closed; the oil compensating operation of the one-way valve is added; thus the switches of a heavy-load low-speed payoff cable, a medium-load medium-speed payoff cable, a light-load high-speed payoff cable and a heavy-load high-speed takeup cable are achieved; and in addition, the tension of a mooring rope can be adjusted or emergency release is achieved by the safety tension adjustment valve. According to the design, three-gear speed change of a hydraulic motor can be achieved, the controller has the functions of tension adjustment, emergency release and stepless control, and has the advantages of being high in integration degree, simple in structure and convenient to remove and overhaul stoppages.