Four quadrants: If the torque and speed of the motor are taken as the coordinate system of the horizontal and vertical coordinates, then the four quadrants in the coordinate system represent the four types of work of the motor: positive force boost, negative force boost, positive force decentralization, Decentralization. The direction of rotation of a DC motor is determined by both the direction of the armature voltage and the direction of the magnetic field. In general DC speed control devices, the direction of the magnetic field is constant, that is, the torque direction is controlled by the armature voltage direction. The direction of the torque of the DC motor is determined by both the direction of the armature current and the direction of the magnetic field. In general DC speed control devices, the magnetic field direction is constant, that is, the torque direction is controlled by the armature current direction. If your DC motor needs to operate in all four quadrants, then you need a DC quadri gler that can adapt to the four-quadrant operation of the motor. You have to select a four-quadrant governor. In the four-quadrant governor, the thyristor is a three-way full-control bridge after being connected in parallel. Therefore, a total of 12 thyristors are used to generate different armature voltage and current directions. And if your motor only needs to run in one direction of operation and torque, then you can use single quadrants. So whether to use a single quadrant or four quadrants depends on the operating conditions of your motor.