For variable-frequency motors, starting is typically relatively straightforward. However, for asynchronous motors, starting performance has always been a crucial operational indicator. Within the performance parameters of asynchronous motors, starting torque and starting current are two critical performance indicators, often expressed as multiples of the rated torque and rated current, respectively.

From an application perspective, it is generally desirable for motors to have a larger starting torque, ensuring that they can start easily within a shorter period. This is particularly crucial for motors that undergo frequent starts and stops, as the magnitude of the starting torque directly impacts the overall operational efficiency of the equipment. Simultaneously, there is a desire to minimize the starting current to prevent adverse effects on the motor itself and the power grid.

One effective method to resolve this contradiction is to increase rotor resistance, which greatly contributes to improving starting performance. However, this may negatively affect other performance indicators of the motor, necessitating a balance between starting performance and other operational parameters.

In wound-rotor asynchronous motors, one relatively easy and effective approach is to connect external resistors in series with the rotor circuit to increase rotor resistance. When the motor starts and transitions into normal operation, these external resistors can be disconnected, thereby achieving a dual assurance effect for starting and running performance.

For squirrel-cage rotor asynchronous motors, common improvement methods include using deep-slot rotors and double-cage rotors. Utilizing the "skin effect" allows for a dynamic balance between starting performance and running performance.

For specific applications where high starting performance is required, high slip motors are available as an option. These motors employ rotor bars made of materials with higher resistivity to increase starting torque by increasing rotor resistance.

To address the contradiction between starting torque and starting current in asynchronous motors and to balance starting performance with other operational parameters, auxiliary starting measures such as reduced voltage starting and variable frequency starting have been introduced.These measures facilitate a comprehensive evaluation of different performance indicators to meet the specific requirements of various applications.