A field of electric drive devices and electric machines, such as electric motors and electric generators for industrial applications and more particularly to a method and an arrangement for controlling vibration of a variable frequency drive controlled electric machine. In the method for controlling vibration of a variable frequency drive controlled electric machine, the resonance frequency/frequencies and the stiffness are determined in a ramp up/ramp down test; amount of damping is determined in an impulse test; a mechanical transfer function is determined in a steady drive test; a vibration control model is determined utilizing said resonance frequency/frequencies, said stiffness, the amount of damping and the mechanical transfer function; and vibration is controlled utilizing the vibration control model.

A fluid pressure unit is provided with an inverter (17), a motor (10) controlled by the inverter, a pump (11) driven by the motor to discharge a fluid, a detector (16) configured to detect a pressure of the fluid, a flow rate of the fluid, or both, a controller (20) configured to control the inverter such that a pressure of the pump, a flow rate of the pump, or both becomes a predetermined value based on a detected value by the detector, and a suppressor (33) configured to suppress a change of an output of the inverter caused by a pulsation frequency component of the fluid included in the detected value.

A fluid pressure unit is provided with an inverter (17), a motor (10) controlled by the inverter, a pump (11) driven by the motor to discharge a fluid, a detector (16) configured to detect a pressure of the fluid, a flow rate of the fluid, or both, a controller (20) configured to control the inverter such that a pressure of the pump, a flow rate of the pump, or both becomes a predetermined value based on a detected value by the detector, and a suppressor (33) configured to suppress a change of an output of the inverter caused by a pulsation frequency component of the fluid included in the detected value.

A linear motor system includes: a stator including first to tenth coils; a mover including a permanent magnet; a switcher that switches one or more power supply target coils; and a control device that supplies power to the one or more power supply target coils by using a deviation integral value obtained by integrating a speed deviation that is a difference between an instructed speed of the mover and an actual speed of the mover. The control device includes: a compensator that calculates a post-division deviation integral value by dividing a post-summation deviation integral value, which is a value obtained by summing the deviation integral value used to supply power to each of the one or more power supply target coils immediately before the switching, by the total number of the one or more power supply target coils immediately after the switching; and a current control unit.

The present disclosure refers to a method for controlling the speed of a reciprocating load motor, wherein the motor speed is a function of two input variables, namely a user defined speed set-point and a load dependent input variable. According to the disclosure, the load dependent input variable is a function of the motor current. The disclosure also refers to a variable frequency drive for controlling the speed of a reciprocating load motor, wherein the drive is programmed to perform the presently described method.

A method includes determining whether a multiphase electric machine is unstable. The method also includes, in response to a determination that the multiphase electric machine is unstable, setting a gate voltage of a first three terminal semiconductor switch to zero. The method also includes, in response to a determination that the multiphase electric machine is stable, setting the gate voltage of the first three terminal semiconductor switch to nonzero. The method also includes, in response to the first three terminal semiconductor switch being set to zero, increasing electrical conduction from one phase of the multiphase electric machine to another phase of the multiphase electric machine. The method includes, in response to the first three terminal semiconductor switch being set to nonzero, increasing electrical resistance from the one phase of the multiphase electric machine to the another phase of the multiphase electric machine.

The subject of the invention is a method and a device for determination of a torsional deflection of a rotation shaft in the electromechanical drivetrain. The method uses a current and a voltage signals measurement of the driving electrical machine and an angular speed measurement of the shaft of the drivetrain and includes the step of measuring of a voltage U.sub.DC of the DC link unit of a converter; the step of calculating a value of a load torque T.sub.load of the driving electrical machine; the step of detecting of an oscillation O.sub.SC(T.sub.load) in the load torque T.sub.load and calculation magnitudes of characteristic frequencies of Fast Fourier Transform FFT(U.sub.DC) of the voltage U.sub.DC of DC link unit; the step of determining of a timestamp indicators t.sub.Tload for oscillations O.sub.SC(T.sub.load) and t.sub.FFT of U.sub.DC for magnitudes of characteristic frequencies of FFT(U.sub.DC) of the voltage U.sub.DC of DC link unit; the step of comparing the value of the timestamp indicators t.sub.Tload and t.sub.FFT and determining a torsional deflection of the rotation shaft if t.sub.Tload<t.sub.FFT; the step of presenting the result of the comparison to the user in a diagnostic unit.

The subject of the invention is a method and a device for determination of a torsional deflection of a rotation shaft in the electromechanical drivetrain. The method uses a current and a voltage signals measurement of the driving electrical machine and an angular speed measurement of the shaft of the drivetrain and includes the step of measuring of a voltage U.sub.DC of the DC link unit of a converter; the step of calculating a value of a load torque T.sub.load of the driving electrical machine; the step of detecting of an oscillation O.sub.SC(T.sub.load) in the load torque T.sub.load and calculation magnitudes of characteristic frequencies of Fast Fourier Transform FFT(U.sub.DC) of the voltage U.sub.DC of DC link unit; the step of determining of a timestamp indicators t.sub.Tload for oscillations O.sub.SC(T.sub.load) and t.sub.FFT of U.sub.DC for magnitudes of characteristic frequencies of FFT(U.sub.DC) of the voltage U.sub.DC of DC link unit; the step of comparing the value of the timestamp indicators t.sub.Tload and t.sub.FFT and determining a torsional deflection of the rotation shaft if t.sub.Tload<t.sub.FFT; the step of presenting the result of the comparison to the user in a diagnostic unit.

An adaptive torque disturbance cancellation method and motor control system for rotating a load are described. The system has: (i) a speed controller for receiving a first input signal indicating a desired motor speed and, in response, for outputting a motor control signal; (ii) current sensing circuitry for sensing current through a motor that rotates in response to the speed controller; (iii) circuitry for storing, into a storage device, history data representative of the current through a motor when the motor operates to rotate the load; and (iv) circuitry for modifying the motor control signal in response to the history data.

An adaptive torque disturbance cancellation method and motor control system for rotating a load are described. The system has: (i) a speed controller for receiving a first input signal indicating a desired motor speed and, in response, for outputting a motor control signal; (ii) current sensing circuitry for sensing current through a motor that rotates in response to the speed controller; (iii) circuitry for storing, into a storage device, history data representative of the current through a motor when the motor operates to rotate the load; and (iv) circuitry for modifying the motor control signal in response to the history data.