Four Quadrant chopper / Type E chopper

Four Quadrant chopper or Type E chopper:

First Quadrant:

 

four quadrant chopper / Type E chopper circuit diagram

• For this operation CH4 is kept on, CH3 is kept off and CH1 is operated.
• With CH1, CH4 on, load voltage Vo = Vs and load current io begins to flow.
• When CH1 is turned off, positive current free wheels through CH4, D2.

Second Quadrant: 

• Here CH2 is operated and CH1, CH3 and CH4 are kept off.
• With CH2 on, reverse current flows through L, CH2, D4 and E. Inductor L stores energy during CH2 is on. When CH2 is turned off, current is fed back to source through diodes D1, D4. Note that here ( E + L. di /dt) is more than the source voltage Vs.

Third Quadrant:

•  For this operation, CH1 is kept off, CH2 is kept on and CH3 is operated. Polarity of load emf E must be reversed for this quadrant working.
• CH3 is on, load gets connected to source Vs so that both Vo, io are negative leading to third quadrant operation.
• When CH3 is off, negative current freewheels through CH2, D4.

Fourth Quadrant:

• Here CH4 is operation and other are kept off. Load emf E has its polarity as in 3rd quadrant. With CH4 on, positive current flows through CH4, D2, L and E. Inductor L stores energy during the time CH4 is on.
• When Ch4 is turned off, current is fed back to source through diodes D2, D3. Here load voltage is negative, but load current is positive. All power is fed back from load to source.