In stock 36mm Brushless DC Motor with high comments
In the parameter setting of variable frequency motor, when it is lower than the power frequency, it is set according to the constant torque, and when it is higher than the power frequency, it is set according to the constant power. In addition, there will be a lower frequency limit when it is running at low frequency and an upper frequency limit when it is running at high frequency. Are these similar settings necessary? To solve this problem, we make a comprehensive analysis based on the characteristics of frequency converter and motor.
On the common YVF series motor nameplate, the constant output parameters of the motor in different frequency ranges are clearly marked, which is divided by the power frequency of 50Hz. When the frequency range is 5-50Hz, the motor is constant torque output, and when the frequency range is 50-100Hz, it is constant power output. Why set the lower limit of low frequency? Will there be an output when the motor has a lower frequency? The answer is yes, but according to the related conditions of motor temperature rise and torque, when the motor is at 3-5Hz frequency, the motor can output rated torque without causing serious heat, which is a comprehensive balance point. Different frequency converters have some differences in the lowest starting frequency according to their respective operating characteristics.
We can compare and analyze the performance parameters of power-frequency motors with the same power and different poles, such as 2P motor and 8P motor. When the output power of two motors with different poles is the same, the rated torque of high-torque motor is smaller than that of low-speed motor, that is, as we discussed in the original tweet, high-speed motor has a small power moment but runs fast, while low-speed motor has a large power moment but runs slowly. If the larger dynamic torque corresponds to the higher rotational speed at the same time, both the motor and the frequency converter are required to have larger capacity, and a larger constant torque is required at high frequency, which will inevitably lead to the overload problem of the frequency converter and the motor.
For the upper limit of the motor operating frequency, on the one hand, it is based on the actual demand of the towed equipment, and on the other hand, it is necessary to consider the matching compliance of the mechanical parts of the motor (such as bearings).