The DC Choppers convert the input DC voltage into fixed or variable DC output. Hence DC chopper is also called as dc to dc converter.

The output $V_o$ can be greater or lesser than the input. Hence the chopper can be step-down or step-up type.

Classification of Chopper:

(A) According to the Input/Output Voltage Levels

(i) Step-down choper: The output voltage is less than the input

(ii) Step-up chopper: The output voltage is greater than the input voltage.

(B) According to the Directions of Output Voltage and Current

(i) Class A (type A) chopper

(ii) Class B (type B) chopper

(iii) Class C (type C) chopper

(iv) Class D (type D) chopper

(v) Class E (type E) chopper

(C) According to Circuit Operation

(i) First-quadrant chopper: The output voltage and both must be positive (Type A).

(ii) Two-quadrant chopper: The output voltage is positive and current can be positive or negative (class-C) or the output current is positive and the voltage can be positive or negative (class-D).

(iii) Four-quadrant chopper: The output voltage and current both can be positive or negative (class-E).

(D) According to Commutation Method

(i) Voltage-commutated choppers

(ii) Current-commutated choppers

(iii) Load-commutated choppers

(iv) Impulse-commutated choppers