In phase control and Integral cycle control the supply voltage is ac and the armature voltage is rectified ac, where as in chopper control the supply is dc and the average armature voltage is proportional to the duty ratio of the chopper. The chopper system is used for dc traction & battery operated vehicle - Choppers using thyristors are more complicated than the phase control system. This is because an auxiliary commutation arrangement is necessary for choppers, whereas commutation is natural owing to a.c. supply in phase control or integral cycle control. Read the paragraph carefully and answer the question based on it.
In a single quadrant chopper how can the direction of dc motor be reversed
by changing the field
The question is about changing the direction of a DC motor in a single quadrant chopper. The correct answer is to change the field, which affects the direction of rotation of the motor.
A single quadrant chopper is a type of DC-DC converter that only allows operation in one of the four quadrants of the speed-torque space. Typically, it facilitates motoring operation, where the motor rotates in a single direction and operates as a load.
- Changing the Field: The direction of a DC motor can be reversed by changing the direction of either the armature current or the field current. In practical applications, it is more common to change the field current direction since it requires less power and minimizes sparking in the armature.
- Explanation of Incorrect Options:
- By changing the direction of the freewheeling diode: This does not affect the motor's direction. A freewheeling diode allows the current to continue flowing through the inductive load when the switch is turned off, helping to prevent voltage spikes.
- By changing the chopper frequency: The frequency of the chopper influences the switching characteristics and efficiency but does not change the direction of motor rotation.
- By applying a filter: Filters are used to smooth out voltage or current ripples but do not affect the motor's direction.
- Conclusion: To reverse the direction of a DC motor in a system using a single quadrant chopper, the field current direction should be changed.
Therefore, the most appropriate way to reverse the direction of a DC motor in a single quadrant chopper is by changing the field.
Similar Questions
A load commutated chopper fed d.c. drive uses 100 V d.c. supply. The maximum chopper frequency is 5 kHz. The value of maximum load current is 100 A. The commutating capacitance will be :
In a lossless buck converter, an average power of 20 W to a load with a regulated 12 V output, while operating at a duty cycle of 0.8 with continuous inductor current. Following data is given :
(a) The average value of input voltage is given by 15 V
(b) The average value of input voltage is 16 V
(c) The average value of input current is 4/3 A
(d) The average value of input current is 3/4 AWhich is correct out of the following ?
In phase control and Integral cycle control the supply voltage is ac and the armature voltage is rectified ac, where as in chopper control the supply is dc and the average armature voltage is proportional to the duty ratio of the chopper. The chopper system is used for dc traction & battery operated vehicle - Choppers using thyristors are more complicated than the phase control system. This is because an auxiliary commutation arrangement is necessary for choppers, whereas commutation is natural owing to a.c. supply in phase control or integral cycle control.
Read the paragraph carefully and answer the question based on it.
Filter for chopper should be designed such a way in the DC Drive that the chopper operating frequency should be at least.
Important Questions from Choppers
A step-up chopper is supplied through a source of 200 V and operated at a duty cycle of 50%. Find the average output voltage of the chopper.
Choppers are _______ converters.
A chopper is a -
Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R
Assertion A: Chopper converts fixed d.c. input voltage to a controllable d.c. output voltage. The Chopper circuit require forced or load commutation to turn off the thyristors.
Reason R: The Chopper circuits are dependent upon the type of commutation and also on the direction of power flow.
In the light of the above statements, choose the most appropriate answer from the options given below
A load commutated chopper fed d.c. drive uses 100 V d.c. supply. The maximum chopper frequency is 5 kHz. The value of maximum load current is 100 A. The commutating capacitance will be :
