Two Quadrant Type A Chopper or Class C Chopper or Reversible Chopper

The  quadrant type A Chopper  is also  known as reversible chopper   because  the polarity of the load current can be  reversed.

Mode I

When SW₁ is ON  V₀= V_s and the  direction of current  is shown  as figure  therefore current I₀ and voltage V_o will be positive.

When SW1  of OFF V₀ =0 but  now load inductor releases the energy and  current is  maintained in the same direction. In  this case V₀= 0 because the polarity of inductance will be  reversed and V_L = -E therefore.

V₀ = V_L +  E = -E  + E =0

Hence the V_o - I_o characteristic is drawn in first quadrant  since both V₀ = I₀  are positive as shown  in figure.

Mode II

When SW₂ is on V_o + 0 but current  will be  flowing from load  t oSW₂  in negative direction.  Inductance stores  energy due to E₂.

When SW₂  is off Vo = E +L  di / dt exceeds V_s  and therefore  diode D is  forward biased and current  flows  from load  to source  through  diode D.

Hence  the V_o -I₀  characteristics for mode II is  drawn in  second  quadrant  since Vo is positive  but I0 is negative  as shown  in figure.