# Four Quadrant Operation of Motors

### Four Quadrant Operation of Motors:

We know that,
(1) All types of DC-DC converters are capable of operating the motor operation in the first quadrant.
(2) Some converters are capable of operating in two quadrants and some in all four quadrants.
(3) Power semiconductor devices(like SCR, MOSFET) used in chopper circuits are unidirectional devices.
(4) So the polarities of output voltage VO and the direction of output current IO are restricted.
(5) However, by using appropriate arrangement of semiconductor devices and passive components, a chopper can operate in any of the four quadrants.

Based on the number of quadrant a chopper can operate, the chopper circuits can be classified as follows:

• Single Quadrant Chopper:-
Example: Type-B Chopper
• Two quadrant Chopper:-
Example: Type-C Chopper, Type-D Chopper
• Four quadrant Chopper;-
Example: Type-E Chopper

In some text books these chopper circuits are mentioned as Class-A, Class-B .... Class-E in place of Type-A, Type-B..... Type-E respectively.
In this Post, we will discuss about the four quadrant operation in detail.
Before proceeding further it is highly recommended to know about the basics, principle of operation, classification of DC-DC Converter Circuits (Choppers). Please click here to read about Chopper basics.

#### Four Quadrant Operation of Motor:

• When a motor draws power from supply, the voltage and current are in the same direction.
• Now the motor is said to be in motoring operation, its operation corresponds to first quadrant.
• If there is a possibility of reversing the current direction keeping the voltage polarity same, the motor is said to be operating in second quadrant.
• This happens when regenerative braking is applied on the motor.
• During regeneration operation, reverse power flow will happen. ie, power will fed back to the supply system.
• If the voltage polarity and load current are reversed simultaneously, the motor's operation will be in the opposite direction ( but the power is consumed by the load).
• This operation is corresponds to the third quadrant and even now it is said to be in motoring operation (in reverse direction).
• If the voltage polarity is reversed maintaining the current direction from source to load, the power reversed and the operation corresponding to the fourth quadrant.
• Now the motor is said to be in reverse regeneration operation (ie, regeneration in reverse direction).

Thanks for reading about the four Quadrant Operation of Motors....