Open-loop electric drive with corrective controller

In an inductor-type synchronous motor having a magnetized moveable portion driven by an alternating signal having a fundamental frequency, a method of diminishing a harmonic sinusoidal perturbation in the force arising from the alternating signal heterodyning with sinusoidal flux waveforms, including the fundamental frequency and harmonics of the fundamental frequency, generated by the motion of the magnetized moveable portion, comprising the step of:

• driving the inductor-type synchronous motor with a complex waveform current having the fundamental frequency and a harmonic of the fundamental frequency, which harmonic is an adjacent harmonic to the harmonic in the motor force, such that the harmonic in the current heterodynes with the fundamental frequency in the periodic flux waveforms to generate beat frequencies in the motor force which diminish the magnitude of the harmonic in the motor force.

In an inductor-type synchronous motor having a magnetized rotor driven by an alternating signal having a fundamental frequency, a method of diminishing a harmonic sinusoidal perturbation in the torque arising from the alternating signal heterodyning with sinusoidal flux waveforms, including the fundamental frequency and harmonics of the fundamental frequency, generated by the rotation of the magnetized rotor, comprising the step of:

• driving the inductor-type synchronous motor with a complex waveform current having the fundamental frequency and a harmonic of the fundamental frequency, which harmonic is in adjacent harmonic to the harmonic in the motor torque, such that the harmonic in the current heterodynes with the fundamental frequency in the periodic flux waveforms to generate beat frequencies in the motor torque which diminish the magnitude of the harmonic in the motor torque.

In an inductor-type synchronous motor having a magnetized moveable portion driven by an alternating signal having a fundamental frequency, a method of diminishing force perturbations that occur in the motor at the fundamental frequency as a result of phase currents of the signal having a dc offset component, the method comprising the steps of:

• adjusting the fundamental frequency to substantially coincide with the lowest resonant frequency of the moveable portions;
• and
• adjusting the dc offset component of the phase currents to minimize resonant frequency vibrations of the moveable portion.

In an inductor-type synchronous motor having a magnetized moveable portion driven by an alternating signal having a fundamental frequency and bipolar phase currents, a method of diminishing force perturbations that occur in the motor at selected harmonics of the fundamental frequency, the method comprising the steps of:

• adjusting the phase currents until the lowest frequency harmonic substantially coincides with the lowest resonant frequency of the moveable portion;
• and
• adjusting the peak amplitude of the phase currents relative to each other until a null occurs in vibration of the moving portion.

In an inductor-type synchronous motor having a magnetized moveable portion driven by an alternating signal having a fundamental frequency and bipolar phase currents containing a third harmonic of the fundamental frequency, a method of diminishing force perturbations that occur in the motor at a fourth harmonic of the fundamental frequency, the method comprising the steps of:

• adjusting the phase currents until the fourth harmonic substantially coincides with the resonant frequency of the motor;
• and
• adjusting the peak amplitude of the third harmonic inherent in the phase currents until a null occurs in motor vibration.