Why does the voltage of the inverter change in proportion to the frequency

       Why does the voltage of the inverter change in proportion to the frequency
　　The electromagnetic torque of any motor is the result of the interaction between the current and the magnetic flux. The current is not allowed to exceed the rated value, otherwise it will cause the motor to heat up. Therefore, if the magnetic flux is reduced, the electromagnetic torque must also be reduced, resulting in a reduction in the load-carrying capacity.
　　From the formula E=4.44*K*F*N*Φ, it can be seen that the magnetic circuit of the motor changes in a considerable range with the operating frequency fX during the variable frequency speed regulation, which is very easy to make the magnetic circuit of the motor serious. saturation, resulting in severe distortion of the excitation current waveform, resulting in a high peak current spike.
　　Therefore, the frequency and voltage should be changed proportionally, that is, the output voltage of the inverter should be controlled while changing the frequency, so that the magnetic flux of the motor should be kept constant, and the phenomenon of weak magnetic field and magnetic saturation should be avoided. This control method is mostly used in energy-saving inverters for fans and pumps.