How does an electric motor start without a starter motor?
1 Answer
In most cases, electric motors require a starter mechanism to initiate their rotation, especially in larger and more complex motor systems. However, for some smaller and simpler electric motors, especially those used in certain household appliances and low-power applications, they may be designed to start without a dedicated starter motor. Instead, they use a different approach to achieve self-starting. Here are a few common methods:
Capacitor-Start Induction Motors: Some single-phase induction motors, used in applications like refrigerators, air conditioners, and washing machines, utilize a capacitor-start mechanism. This design includes an auxiliary winding and a capacitor that creates a phase shift between the main and auxiliary winding currents. This phase shift generates a rotating magnetic field that starts the motor's rotation. Once the motor reaches a certain speed, a switch disconnects the auxiliary winding and capacitor from the circuit.
Shaded-Pole Motors: These are simple single-phase induction motors with salient poles, where each pole has a shading coil around a portion of it. When an alternating current flows through the main winding, it induces currents in the shading coil, creating a phase difference. This phase difference creates a rotating magnetic field that initiates the motor's rotation.
Permanent Magnet Motors: Some small electric motors use permanent magnets to create the initial rotating magnetic field necessary for self-starting. These motors don't require additional starter components because the magnets themselves provide the required magnetic field to initiate rotation.
Brushless DC Motors: While brushless DC motors require electronic control circuitry, they do not have a separate starter motor. Instead, they utilize a sequence of electronic commutation to control the direction of current flow in the motor windings, creating a rotating magnetic field and enabling the motor to start and run smoothly.
It's important to note that larger electric motors, such as those used in industrial applications or electric vehicles, usually require more sophisticated control systems and often have a separate starter motor or starter circuit to ensure a controlled and reliable start-up process. The methods mentioned above are generally limited to smaller motors with specific design considerations for self-starting applications.
Capacitor-Start Induction Motors: Some single-phase induction motors, used in applications like refrigerators, air conditioners, and washing machines, utilize a capacitor-start mechanism. This design includes an auxiliary winding and a capacitor that creates a phase shift between the main and auxiliary winding currents. This phase shift generates a rotating magnetic field that starts the motor's rotation. Once the motor reaches a certain speed, a switch disconnects the auxiliary winding and capacitor from the circuit.
Shaded-Pole Motors: These are simple single-phase induction motors with salient poles, where each pole has a shading coil around a portion of it. When an alternating current flows through the main winding, it induces currents in the shading coil, creating a phase difference. This phase difference creates a rotating magnetic field that initiates the motor's rotation.
Permanent Magnet Motors: Some small electric motors use permanent magnets to create the initial rotating magnetic field necessary for self-starting. These motors don't require additional starter components because the magnets themselves provide the required magnetic field to initiate rotation.
Brushless DC Motors: While brushless DC motors require electronic control circuitry, they do not have a separate starter motor. Instead, they utilize a sequence of electronic commutation to control the direction of current flow in the motor windings, creating a rotating magnetic field and enabling the motor to start and run smoothly.
It's important to note that larger electric motors, such as those used in industrial applications or electric vehicles, usually require more sophisticated control systems and often have a separate starter motor or starter circuit to ensure a controlled and reliable start-up process. The methods mentioned above are generally limited to smaller motors with specific design considerations for self-starting applications.