6 Questions
What is the total number of possible states that can be represented by the 4-digit binary number (x1x2x3x4)2 in a 4-quadrant dc chopper?
16
Which of the following states is not utilized in a 4-quadrant dc chopper?
State 5
In the first quadrant operation of a 4-quadrant dc chopper, what is the binary state when S1 is ON?
(1001)2
A four-quadrant chopper operates with a switching frequency of 1kHz. What is the period of the switching signal?
1 ms
In a 4-quadrant chopper, what is the voltage control range for the third quadrant of operation when the input voltage is 240 V?
-240 V to 0 V
What is the magnitude control ratio of the chopper when it operates in the fourth quadrant with an on-time of 0.75 ms and an off-time of 0.25 ms?
-0.75
Study Notes
4-Quadrant DC Chopper
- The 4-digit binary number (x1x2x3x4)2 represents the chopper state, with a total of 16 possible states.
- Only states 0, 1, 4, 6, and 9 are utilized, as the remaining states would either short-circuit the supply source or spoil the symmetry of control.
First Quadrant Operation
- ON state: S1 and S4 are ON, represented by state 9 (1001)2.
- OFF state: only S4 is ON, represented by state 1 (0001)2.
Quadrant Operation Modes
- Four modes of operation: first, second, third, and fourth quadrants.
Example Problem
- A four-quadrant chopper operates with a switching frequency of 1kHz and supplies power to a dc motor with an armature EMF of –216 V.
- Input voltage of the chopper is 240 V.
Control Range and Time Calculations
- Voltage control ranges for the third and fourth quadrants of operation depend on the magnitude control ratio.
- ON-time and OFF-time of the modulating switch can be calculated for specific magnitude control ratios in each quadrant.
- Example:
- Third quadrant operation with magnitude control ratio of –0.95.
- Fourth quadrant operation with magnitude control ratio of –0.75.
Learn about the different operation modes of a 4-quadrant DC chopper, including first quadrant operation and its ON and OFF states. Understand how the chopper state is represented in binary form.
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