Electric Motors Quiz: AC vs DC

The stationary part of an electric motor housing the magnetized poles, which can be either permanent magnets or field coils. These poles generate the radial magnetic field.

The rotating inner part of an electric motor. It includes the shaft, armature windings, and in DC motors, a commutator.

The small gap between the stator and rotor where magnetic fields interact to induce rotation.

A device in brushed DC motors that controls the direction of current in the armature windings.

Electrical components contacting the commutator in brushed DC motors, delivering and controlling current.

Simple construction, cost-effectiveness, and reliability are advantages of brushed DC motors.

Friction between brushes and commutator leads to energy loss and heat, reducing efficiency.

Brushes wear over time, requiring maintenance for replacement. There's a limited operational speed due to brush and commutator wear.

AC motors where the rotor rotates slower than the stator field, creating a 'slip' that allows for induction, hence the name 'induction motors'.

AC motors where the rotor speed perfectly matches the stator field rotation, achieving synchronized operation without slip.

The difference in speed between the stator field and the rotor in an asynchronous motor.

Permanent Magnet (PM) DC Motors utilize a permanent magnet for creating the magnetic field, simplifying construction and improving efficiency.

The magnetic field created by a permanent magnet in a PM DC motor is responsible for driving the torque and rotation of the motor.

The rotating part of a DC motor that contains the winding coils where current flows. This interaction between the magnetic field and the current creates torque for rotation.

PM DC Motors have higher efficiency because they eliminate the energy losses associated with field coils, leading to better performance.

Reversing the direction of current flowing through the armature windings changes the polarity of the magnetic field, effectively reversing the direction of rotation.

The electrical equation of a DC motor, describing the relationship between input voltage, back EMF, armature current, and armature resistance. It shows how the electrical energy is transformed into mechanical motion.

The mechanical equation of a DC motor, describing the relationship between torque, inertia, and external forces.

The torque generated by a DC motor is proportional to the armature current. This means that increasing the armature current will increase the torque produced by the motor.

The torque constant of a DC motor represents the relationship between the armature current and the generated torque, quantifying the amount of torque produced per unit of armature current.

The back electromotive force (back EMF) is a voltage generated by the rotating armature of a DC motor, opposing the input voltage.

The steady-state equations are simplified versions of the electrical and mechanical equations, valid when the motor operates at a constant speed and current.

The steady-state torque of a DC motor is calculated using the steady-state current and the torque constant.

This equation relates the steady-state torque of a DC motor to the input voltage and speed. It's a useful equation for calculating the torque output of a DC motor under specific conditions.

The maximum power delivered to the load occurs when "omega" is equal to half the maximum speed (omega_max).

The power delivered by a DC motor is calculated by multiplying the torque (T) by the angular velocity (omega). This is expressed by the equation P(omega) = T * omega.

A method for controlling the speed of a DC motor by rapidly switching the voltage between ON and OFF states. The average current through the armature is regulated, effectively controlling the motor's speed.

The ratio of output power to input power, indicating the motor's efficiency in converting electrical energy into mechanical energy.

A DC motor with a permanent magnet used for creating the magnetic field. This simplifies construction and often leads to higher efficiency.

The average current is higher for a higher DTC, resulting in a higher speed. The average current is lower for a lower DTC, resulting in a lower speed.

This control approach relies on sensor feedback (e.g., tachometer) to monitor the actual speed and adjust the motor's input (PWM) to achieve the desired speed. This allows for more accurate speed regulation.

A feedback loop that continuously adjusts the motor's position based on the difference between the desired position and the actual position.

The desired position or velocity of the servo motor, set by the user.

A sensor that measures the actual position of the servo motor shaft.

The control signal sent to the servo motor consists of a series of pulses with a specific frequency and width.

The frequency of the control signal for a servo motor should be 50Hz, meaning a pulse occurs every 20 milliseconds.

The width of the pulse in the control signal determines the angular position of the servo motor.

The controller amplifies the error signal and uses it to drive the motor to the desired position.

The difference between the reference input and the feedback signal, indicating how far the motor is from the desired position.