Our factory has a small AC drive controlled 0.75KW 4 pole electric motor, the motor temperature went high with no-load running, the AC drive is Siemens, is there any way to solve this?

If it is convenient, you can give one hour of the motor alone powered, measuring the temperature of the motor; motor recovery at room temperature, and then loaded AC drive, running for an hour, measure the temperature conditions. To see the difference between those two temperatures, if the difference of a few cases, no need worried, just ignore it, if the temperature difference is relatively large, it is important to note.

High harmonic generated by the AC drive in the inverter process into the AC drive, causing the increase of the motor reactive power, reactive power, the form of heat released, so the temperature of the motor increases more quickly.
At this point, you need to add the output filter for the AC drive.
In addition: Siemens drives, most of them do not integrate filter, if include filter, the price is higher and delivery time is slower.

AC drive with the motor due to the harmonic relationship between the motor heat, not high, then make do with it. In addition the ac drive brought the motor is the best inverter dedicated motor, cooling fan power supply and main power of this motor is separate, but also to strengthen the insulation. If an ordinary motor, adjust the speed is low, the cooling fan motor itself brought lost a role if the process is recommended to set the minimum frequency 20HZ, otherwise change the motor.