Method and device for driving a motor at a variable rotation speed

摘要

A method is described for driving an asynchronous motor (4) at a variable rotation speed, in the case of which method a control electronics device (2; 102) of a frequency converter (1; 100) produces a number N of control pulses (S0-S15; S0-S31), which are in each case separated by one clock interval, in order to vary or regulate the rotation speed of the asynchronous motor (4). These control pulses are fed to a power section (3), which supplies the asynchronous motor (4), of the frequency converter (1; 100) which emits an output signal at the frequency fs, the mean value of which output signal is essentially sinusoidal [sic]. According to the invention, it is in this case provided that the pulse width of each control pulse (S0-S15; S0-S31) is defined independently of the rotation speed of the asynchronous motor (4) which is to be varied or regulated, and that the time duration of each clock interval which separates two control pulses (S0-S15; S0-S31) which follow one another in time is varied as a function of the rotation speed, in such a manner that the power section (3; 103) of the frequency converter (1) emits an output signal at the frequency fs, the mean value of which output signal is essentially sinusoidal. <IMAGE>