FREQUENCY CONTROL METHOD OF ASYNCHRONOUS ELECTRIC MOTOR Russian patent published in 2017 - IPC H02P23/00 H02P25/02 H02P27/04 H02P27/06 

FIELD: electricity.

SUBSTANCE: frequency control method of asynchronous electric motor, containing the voltage rectifier, the capacitor filter and the self-contained voltage inverter, the amplitude and output voltage frequency of which are formed in accordance with the specified motor speed, which is realized in the control system, closed at rotation speed through the speed controller, the input signal of which is the discrepancy of the assignment and the feedback signals, which is obtained by the speed sensor, mounted on the motor shaft. The feedback signal proportional to the motor speed is generated in the control system by adding the synchronous and slip frequency signals, taken with the minus sign, to form which the control unit is added to the control system, the input of which is supplied with the signals proportional to the average value of the inverter input current, the maximum value of the inverter input current and the modulation factor. The signal corresponding to the current slip frequency is determined from the expression

,

where I_sanom - the value of the stator current active component in the nominal operating mode, ω_rnom - slip frequency in the nominal operating mode, I_in - the signal proportional to the average value of the inverter input current, I_m - the signal proportional to the maximum inverter current, R_s - active resistance of the stator winding phase AD, U_dc - average value of the capacitor voltage in the intermediate link of the frequency converter, m - modulation factor.

EFFECT: reliability increase and expansion of the application field.

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