High stability dynamic force motor

A method of controlling a VR motor that is operable at a plurality of operating frequencies, comprising:

• receiving a signal that includes a plurality of discrete frequencies, as a command input to the VR motor;
• precompensating the command input in accordance with a 1/ω characteristic of the VR motor;
• and
• generating a low-distortion force representative of the command input,
• wherein the VR motor is one of a one-sided motor and a two-sided motor.

A method of controlling a VR motor, comprising:

• providing, via an open-loop active circuit, a dynamic voltage to a coil of said motor to result in a substantially unipolar current flowing in the coil, said periodic voltage being applied so as to maintain control of said motor irrespective of instantaneous motor gap and driven load characteristics;
• generating a voltage by one of a linear and switching unipolar voltage amplifier;
• and
• offsetting the generated voltage so to minimize an amount of time when zero current is flowing from the unipolar voltage amplifier to said coil of said motor,
• wherein the VR motor has an armature and a core with a linearly varying gap between the armature and the core, and
• wherein said offset voltage is determined as an open-loop value not derived from any feedback source.

A method of controlling a VR motor, comprising:

• providing, via an open-loop active circuit, a dynamic voltage to a coil of said motor to result in a substantially unipolar current flowing in the coil, said periodic voltage being applied so as to maintain control of said motor irrespective of instantaneous motor gap and driven load characteristics,
• wherein the VR motor has an armature and a core with a linearly varying gap between the armature and the core,
• wherein said dynamic voltage follows a waveform:
• v(t)≈Vdc, 0≦t<t1 (Phase 1)
• v(t)≈0, t1≦t<t2 (Phase 2)
• v(t)≈−Vdc, t2≦t<t3 (Phase 3)
• v(t)≈0, t3≦t<T (Phase 4)
• with period T, and
• wherein said time t2 is equal to T/2+ε, said time period ε being introduced to compensate for asymmetries in the slewing properties of said core circuit.

A method of controlling a VR motor, comprising:

• providing, via an open-loop active circuit, a dynamic voltage to a coil of said motor to result in a substantially unipolar current flowing in the coil, said periodic voltage being applied so as to maintain control of said motor irrespective of instantaneous motor gap and driven load characteristics,
• wherein the VR motor has an armature and a core with a linearly varying gap between the armature and the core,
• wherein said dynamic voltage follows a waveform:
• v(t)≈+Vdc, 0≦t<t1 (Phase 1)
• v(t)≈0, t1≦t<t2 (Phase 2)
• v(t)≈−Vdc, t2≦t<t3 (Phase 3)
• v(t)≈0, t3≦t<T (Phase 4)
• with period T, and
• wherein during said Phase 1 said v(t) is applied to said core conductive winding via two actively switched electrical devices, during said Phase 2 said v(t) is applied to said core conductive winding via one actively switched electrical device and one passive electrical device, during said Phase 3 said v(t) is applied to a core conductive winding of said VR motor via two passive electrical devices, and during said Phase 4 said v(t) is obtained by virtue of all active and passive electrical devices comprising an amplifier means for outputting said v(t) being in a non-conductive state.

A method of controlling a VR motor, comprising:

• providing a dynamic voltage to a coil of said motor so that a substantially unipolar coil current flows in the coil, said periodic voltage being applied so as to maintain control of said motor irrespective of instantaneous motor gap and driven load characteristics;
• measuring the current in a core conductive winding of said VR motor;
• and
• generating a DC offset voltage that is summed with said applied dynamic voltage such that a time duration and magnitude of excursions of said measured current are minimized.

A method of generating a substantially sinusoidal flux waveform for a variable reluctance (VR) motor, comprising:

• applying a voltage waveform to a coil of the motor, the voltage waveform having a substantially zero mean, the voltage waveform being maintained irrespective as to a change in a size of the gap,
• wherein no current control with respect to the coil is utilized during operation of the motor,
• wherein the VR motor has an armature and a core in which the gap linearly varies in size between the armature and the core,
• wherein the voltage waveform is a periodic signal, and
• wherein the substantially sinusoidal flux waveform returns to a zero flux value between a cycle time t1 and a cycle time t2 with respect to a start time of each cycle of the substantially sinusoidal flux waveform, wherein t1 corresponds to a time that is just prior to one full cycle of the substantially sinusoidal flux waveform, and t2 corresponds to an end time of the one full cycle, wherein the substantially sinusoidal flux waveform maintains a zero voltage value for at least a fixed portion of each cycle of the substantially sinusoidal flux waveform.

A method of generating a substantially sinusoidal flux waveform for a variable reluctance (VR) motor, comprising:

• applying a voltage waveform to a coil of the motor, the voltage waveform having a substantially zero mean, the voltage waveform being maintained irrespective as to a change in a size of the gap,
• wherein no current control with respect to the coil is utilized during operation of the motor,
• wherein the VR motor has an armature and a core in which the gap linearly varies in size between the armature and the core, and
• wherein the coil has a fixed resistance value and a fixed voltage value associated therewith, and wherein the voltage waveform has a mean value that is equal to the fixed voltage value.

A method of generating a substantially sinusoidal flux waveform for a variable reluctance (VR) motor, comprising:

• applying a voltage waveform to a coil of the motor, the voltage waveform having a substantially zero mean, the voltage waveform being maintained irrespective as to a change in a size of the gap,
• wherein no current control with respect to the coil is utilized during operation of the motor,
• wherein the VR motor has an armature and a core in which the gap linearly varies in size between the armature and the core, and
• wherein the coil has a fixed resistance value,
• the method further comprising:
• measuring a current flowing through the coil;
• calculating an offset voltage value that is equal to the fixed resistance value multiplied by a value corresponding to the measured current;
• and
• offsetting the voltage waveform by the offset voltage value.

A method of controlling a variable reluctance (VR) motor, comprising:

• applying a substantially zero-mean voltage waveform to a coil of the motor,
• wherein each cycle of the substantially zero-mean voltage waveform includes:
• a first time period in which a first positive voltage value is provided;
• a second time period in which a zero voltage value is applied;
• and
• a third time period in which a second negative voltage value is applied,
• wherein an absolute value of the first and second voltage values is substantially equal to each other, and
• wherein a substantially trapezoidal flux waveform that represents a flux within the gap is obtained as a result.

A method of controlling a variable reluctance (VR) motor, comprising:

• applying a substantially zero-mean voltage waveform to a coil of the motor,
• wherein each cycle of the substantially zero-mean voltage waveform includes:
• a first time period in which a first positive voltage value is provided;
• a second time period in which a zero voltage value is applied;
• and
• a third time period in which a second negative voltage value is applied,
• wherein an absolute value of the first and second voltage values is substantially equal to each other, and
• wherein the first, second and third time periods are unequal in time duration for said each cycle.

A control apparatus for a two-sided variable reluctance motor that has an armature and a stationary part with a first coil on the core and a second coil on the core, and with a first air gap between the first coil and the armature and a second air gap between the second coil and the armature, the control apparatus comprising:

• a voltage source that provides a voltage waveform to the first and second coils;
• a first diode that is provided between the voltage source and the first coil;
• and
• a second diode that is provided between the voltage source and the second coil,
• wherein an anode of the first diode and a cathode of the second diode are directly connected to the first and second coils, respectively.

A control apparatus for a variable reluctance motor that has a core with a coil and an armature, comprising:

• an offset voltage source for providing a DC offset voltage;
• a voltage source for outputting a sinusoidal voltage to the coil that is offset by the DC offset voltage;
• a current sensing unit for sensing current presently passing through the coil;
• a rectifying circuit that removes all portions of the sensed current except for negative current pulses;
• and
• a low-pass filter that filters and output of the rectifying circuit,
• wherein an output of the low-pass filter is provided to the offset voltage source to provide an adjustment signal to either increase, decrease or maintain a current value of the DC offset voltage.

A method of controlling a VR motor, comprising:

• providing, via an open-loop active circuit, a dynamic voltage to a coil of said motor to result in a substantially unipolar current flowing in the coil, said periodic voltage being applied so as to maintain control of said motor irrespective of instantaneous motor gap and driven load characteristics,
• wherein the VR motor has an armature and a core with a linearly varying gap between the armature and the core,
• wherein a first diode and a first switch are connected in series to each other on a first path,
• wherein a second diode and a second switch are connected in series to each other on a second path,
• wherein the first and second paths are connected in parallel to each other, and
• wherein the dynamic voltage is provided across the first and second paths.

A method of controlling a variable reluctance (VR) motor, comprising:

• applying a substantially zero-mean voltage waveform to a coil of the motor,
• wherein each cycle of the substantially zero-mean voltage waveform includes:
• a first time period in which a first positive voltage value is provided;
• a second time period in which a zero voltage value is applied;
• and
• a third time period in which a second negative voltage value is applied,
• wherein an absolute value of the first and second voltage values is substantially equal to each other,
• wherein the VR motor has an armature and a core with a linearly varying gap between the armature and the core, and
• wherein the third time period occurs between the first time period and the second time period.