Power grid voltage sag often causes protection action of the coal feeder frequency converter in the thermal power plant, which affects the normal power production. A novel means of using the permanent magnet coupling speed regulating motor in coal feeder is proposed to realize low voltage ride-through (LVRT) by the motor′s properties. The LVRT operating principle of the permanent magnet coupling speed regulating motor is analyzed. The double-closed-loop control system is designed. A 5.5 kW electrical drive system experimental platform of the coal feeder is built. The experimental results show that the proposed motor and its control system have good rapidity and accuracy, and when voltage sag occurs in the power grid, the coal feeder can work normally and have LVRT ability.