# Four quadrant DC motor operation

## Motoring mode and braking mode

A DC motor can operate in one of two modes - motoring mode or braking mode.

- In the motoring mode electrical energy is converted into mechanical energy, the motor produces the torque that is necessary for rotation;
- In the braking mode the situation is opposite - under the influence of external forces, the motor works as a generator, converting mechanical energy into electrical energy. The load torque in this case counteracts the rotation of the motor.

A DC motor can rotate both forward or reverse. Operation can be in the motoring mode or in the braking mode and in two variants of the rotation direction. Other words, the DC motor can operate in both directions of rotation and produce both movement and braking. These four modes of operation are four-quadrant DC motor operation.

The power produced by the motor is determined by the product of the angular velocity and the torque. The driving mode is such a mode of operation of the DC motor when the power it produces has a positive sign. The braking mode is the mode of operation in which the product of the angular velocity and the torque has a negative sign.

## Four quadrant operation

A DC motor can operate in one of two modes - motoring mode or braking mode.

### Quadrant I

The power produced by the electric motor in the first quadrant is positive. The work is carried out in the motoring mode, there is a conversion of electrical energy into mechanical energy. The operation of the motor in the first quadrant is motoring in the forward direction.

### Quadrant II

In the second quadrant, the motor rotates in the forward direction, its speed has a positive sign. The torque value has a negative sign. The direction of rotation is positive, i.e. the speed is positive and the torque is negative. Consequently, the power produced by the motor also has a negative value, the motor operates in the generator mode, counteracting the movement. The kinetic energy of the motor rotor is converted into electrical energy. Therefore, the operation of the motor in the second quadrant is called braking in the forward direction.

### Quadrant III

In the third quadrant, both rotational speed and torque are negative. Their product determines the positive power value. The operation of the motor in the third quadrant is reverse motoring.

### Quadrant IV

In the fourth quadrant, the motor speed has a negative value, while the produced torque has a positive sign. Therefore, the motor power is negative, which corresponds to the braking mode. The operation of the motor in the fourth quadrant is reverse braking.