What is the maximum rotation speed that a sine wave drive motor driver IC can support?

The maximum speed of a motor is mainly determined by its characteristics and the power supply voltage. However, it is also affected by the carrier frequency of the PWM control, which is set by the IC. For sinusoidal PWM drive, the recommended maximum rotation speed is about 1/100 or less of the PWM frequency.

For example, using the TC78B041FNG to drive a 4-pole motor (which consists of two pole pairs of N and S poles),
When the motor rotates at 5,000 rpm, the sinusoidal drive frequency is as follows,
5,000 rpm x 2 pole pairs / 60 seconds = 167 Hz

When the PWM carrier frequency the TC78B041FNG is set to 18 kHz,
it results in a resolution of 108 PWM pulses per sinusoidal drive cycle (18kHz / 167Hz = 108).

On the other hand, if the motor rotates at 15,000 rpm, the sinusoidal drive frequency is as follows
15,000 rpm x 2 pole pairs / 60 seconds = 500 Hz

The resolution will be 36 PWM pulses per sinusoidal drive cycle (18 kHz/500 Hz=36).
With this resolution, each PWM will xxx about 10° phase difference.

The recommended resolution is 100 or higher PWM pulses per sinusoidal drive cycle. However, motors may still rotate at resolutions under 100. In such cases, waveform distortion or noise may occur. Since it depends on the characteristics of the motor, please confirm whether the required rotation performance can be obtained with the actual motor.

Related Links

The following documents also contain related information.

FAQs

Catalog

Video

Tools & Software

e-Learning