SSD UT 4

V/f control maintains synchronous motor speed by adjusting the:

•       : a) Frequency only

• b) Frequency and voltage

• c) Voltage only

• d) Rotor field

Self-control methods rely on the inherent characteristics of the

•     a) Stator

• b) Rotor

• c) Inverter

• d) Power supply

Which statement is TRUE about self-control compared to V/f control?

•    a) It offers easier speed control.

• b) It has higher efficiency at low speeds.

• c) It requires additional field excitation.

• d) It is unsuitable for variable speed applications.

The margin angle in a synchronous motor is the angle between the

•     a) Stator current and rotor current

• b) Stator magnetic field and rotor field

• c) Stator voltage and rotor voltage

• d) Supply frequency and rotor speed

Increasing the margin angle will lead to

•      a) Increased torque, decreased power factor

• b) Decreased torque, increased power factor

• c) Both torque and power factor increase

• d) Both torque and power factor decrease

Which control method can directly regulate the power factor of a synchronous motor?

• a) V/f control

• b) Margin angle control

• c) Self-control

• d) Open-loop control

BLDC motors achieve commutation through:

•     a) Mechanical brushes

• b) Sensorless control and electronic switching

• c) Permanent magnets on the rotor and field windings

• d) A combination of b and c

Synchronous reluctance motors are often used in:

•      a) Servo drives requiring high precision

• b) Industrial pump and fan drives for efficiency

• c) Electric traction due to high starting torque

• d) Home appliances needing low noise

Which type of inverter is more suitable for high-performance electric vehicles?

• a) VSI with PWM control

• b) CSI with constant current control

• c)VSI with resistance control

• d ) CSI with constant current control

Compared to VSIs, CSIs offer:

•       a) Simpler control but lower torque

• b) Higher efficiency but complex switching

• c) Better regenerative braking but higher cost

• d) None of the above