Multi Quadrant Operation of Drives Or DC Motor
Table of Contents
Four Quadrant Operation of drives or DC Motor (Multi Quadrant Operation of Drives Or DC Motor) means that the machine operates in four quadrants. They are reverse braking, reverse motoring, forward braking, and forward motoring.
A motor operates in two modes – Motoring and Braking. A four quadrant variable speed drive is a motor drive that can produce both motoring and regeneration while operating in both directions of rotation.
When the machine is in motoring mode, it functions as a motor and transforms electrical energy into mechanical energy to support motion. When the machine is in braking mode, it functions as a generator, converting mechanical energy into electrical energy, which causes it to oppose motion. The motor is capable of working both forward and backward, or in motoring and braking operations. The power produced by a motor is equal to the product of angular speed and torque. The following conventions regarding the signs of torque and speed are used for the operation of drives in multiple quadrants. The motor is said to be rotating at a positive speed when it is moving forward. The forward speed of drives that only operate in one direction will be those drives’ regular speed.
The speed of the motor causing the upward motion is thought of as being in forward motion in loads involving up and down motions. The forward speed for reversible drives is chosen at random. Reverse rotation produces reverse speed, which is indicated by a negative sign. Positive motor torque is the rate of speed change that is positive in the forward direction or the torque that produces acceleration. The motor torque is viewed negatively in cases of retardation. The direction of the load torque is the exact opposite of the positive motor torque.
The figure below shows the Multi Quadrant Operation of Drives Or DC Motor
The machine is acting as a motor, generating positive power in the I quadrant, and supplying mechanical energy. Forward Motoring is the name of the operation in the I (first) quadrant.Braking is an II (second) quadrant operation.Because the torque is negative and the rotational direction is positive in this quadrant, the machine acts as a generator, creating a negative torque that counteracts the motion. Electrical energy that can be returned to the mains is available as kinetic energy from the rotating parts. Energy is lost during dynamic braking as a result of resistance. Reverse motoring is an operation in the III (third) quadrant. In the opposite direction, the motor operates. While the power is positive, the speed and torque are both negative.
In the IV (fourth) quadrant, the torque is positive, and the speed is negative. This quadrant corresponds to the braking in the reverse motoring mode.
Applications of Four Quadrant Operation
- Transportation drives require operation in both directions.
- Only the I quadrant is required for operation of the compressor, pump, and fan types of load. They are known as one quadrant drive systems because of the unidirectional nature of their operation.
- In hoist drives, a four-quadrant operation is needed.
- Application in each of the four quadrants may be necessary if regeneration is required. If not, the operation is limited to quadrants I and III, necessitating the use of mechanical or dynamic braking.
The four-quadrant operation and its relationship to speed, torque and power output are summarized below in the table:
Function | Quadrant | Speed | Torque | Power Output |
---|---|---|---|---|
Forward Motoring | I | + | + | + |
Forward Braking | II | + | – | – |
Reverse Motoring | III | – | – | + |
Reverse Braking | IV | – | + | – |
So This is all about Four Quadrant operation of DC Motor / Drives.