A method for determining a resonance frequency of a mechanical system including an electric motor coupled to a mechanical load, the method including: starting the motor by providing a supply voltage using a motor controller; once the electric motor is running at a predefined target rotational speed, applying a first excitation signal comprising a voltage pulse superimposed to the supply voltage; measuring a mechanical response of the mechanical system, using a measurement system coupled to the motor; and analyzing the measured response, to determine at least one resonance frequency of the mechanical system.

Embodiments of a mixing device power system generally include a power control module, an AC motor, and a variable frequency drive, wherein upon application of AC power to the system, electrical power is provided to the power control module which transmits electrical power to the AC motor, whereby rotation of a mixing spindle is initiated. After the spindle has begun rotating, transmission of electrical power from the power control module to the AC motor is ceased, and substantially simultaneously electrical power transmission is commenced from the power control module to the variable frequency drive which transmits electrical power to the AC motor, whereby rotation of the mixing spindle is continued. A method of using the mixing device power system to mix a fluid sample is also provided.

An output-torque estimation unit obtains a value of a current input to a motor, from a power converter, and calculates an estimated output torque value which is an estimated value of output torque of the motor, from the obtained value of the current. A load estimation unit estimates a load value of a hanging cargo based on the estimated output torque value which is calculated by the output-torque estimation unit, a speed reduction ratio of a speed reducer, an effective radius of a winch drum, and the winding number which is set by the number setting unit.

The invention relates to a method for starting a synchronous motor. The synchronous motor includes a rotor for creating a first magnetic field and a stator with stator windings connected to an electrical energy converter for converting a supply voltage into a stator voltage to be applied to the stator windings to create a rotating second magnetic field interacting with the first magnetic field. The method includes the following steps: applying reference stator voltages to the stator windings, wherein the reference stator voltages are determined from a reference current vector and a reference rotor speed; measuring stator currents in the stator windings; calculating an estimated rotor speed and an estimated rotor position of the rotor from the applied stator voltages and the measured stator currents; calculating a speed error by subtracting the estimated rotor speed from the reference rotor speed; determining a reference torque producing current component from the speed error and modifying the reference current vector with the reference torque producing current component; calculating a position error by subtracting the estimated rotor position from a reference rotor position, wherein the reference rotor position is determined from the reference rotor speed and a reference rotor speed correction, wherein the reference rotor speed correction increases and decreases with the position error; correcting the reference current vector by transforming the reference current vector into a corrected reference current vector by the position error, wherein a rotating coordinate system of the corrected reference current vector is aligned with the estimated rotor position; determining switching signals for the electrical energy converter from the reference stator voltages and applying the switching signals to the electrical energy converter.

A control system may include a processor that may receive a first dataset associated with a current received at a load device coupled to a relay device. The processor may also determine harmonics data associated with the current and determine a switching profile to control moving a first armature of three armatures in the relay device based on the harmonics data. The switching profile is configured to control movement of the first armature between a first position and a second position, and wherein the switching profile comprises a firing angle for moving the first armature with respect to an electrical waveform, a second armature, and a third armature. The processor may then control a current provided to a relay coil of the relay device based on the switching profile, such that the relay coil causes the first armature to move.

Assisted racking of digital resistance includes detecting a state of a cable. A motor is mechanically coupled to the cable to provide resistance during an exercise by tensioning the cable. It further includes determining completion of the exercise based at least in part on the detected state of the cable. It further includes selectively removing resistance from the cable based at least in part on the determination that the user has completed the exercise.

Assisted racking of digital resistance includes detecting a state of a cable. A motor is mechanically coupled to the cable to provide resistance during an exercise by tensioning the cable. It further includes determining completion of the exercise based at least in part on the detected state of the cable. It further includes selectively removing resistance from the cable based at least in part on the determination that the user has completed the exercise.

A method for controlling a variable speed drive arranged for powering an electric motor, the variable speed drive comprising a power part and a control part. The method comprises a preliminary phase of storing a set of predetermined levels of flux of the electric motor. Then, during a current phase, the method comprises selecting a level of flux from among the set of predetermined levels of flux and controlling the power part of the variable speed drive based on the selected level of flux as reference value.

A motor driver system. Implementations may include: a motor driver configured to couple with a motor where the motor driver comprises a multipurpose pin. A controller may be included coupled with the motor driver through at least the multipurpose pin. The motor driver during an enable mode, may be configured to receive serial data from the controller and to send serial data to the controller using the multipurpose pin during a normal operation mode of the motor driver. The motor driver may be configured to output a frequency generator (FG) signal to the controller using the multipurpose pin during the normal operation mode of the motor driver.

A motor driver system. Implementations may include: a motor driver configured to couple with a motor where the motor driver comprises a multipurpose pin. A controller may be included coupled with the motor driver through at least the multipurpose pin. The motor driver during an enable mode, may be configured to receive serial data from the controller and to send serial data to the controller using the multipurpose pin during a normal operation mode of the motor driver. The motor driver may be configured to output a frequency generator (FG) signal to the controller using the multipurpose pin during the normal operation mode of the motor driver.