Dana Corporation

Ramani R Kalpathi

Scott E Blackburn

Peter T Szymanski

Ning Liu

Sergei F Kolomeitsev

David C Reuter

A method for controlling a motor and a circuit for implementing the method are provided. The method includes the steps of providing a first current to a first phase coil of a motor and determining a characteristic of the first current in the first phase coil wherein the characteristic is indicative of the position of the motor's rotor. The measured characteristic may comprise a time period required for the current to move between two predetermined current levels. The method further includes the step of controlling the first current in the first phase coil of the motor and a second current in a second phase coil of the motor responsive to the measured characteristic in the first phase coil. By controlling the current in multiple phase coils responsive to a current characteristic measured in one phase coil, current sensing in all but one phase coil may be eliminated thereby conserving microprocessor resources, increasing motor efficiency, speed, and braking torque, and reducing acoustic noise.

Phase commutation of a switched reluctance motor by single phase sensing of inductance

A method for detecting a change in motor load and/or motor speed is provided. The method includes the step of measuring the number of transitions (i.e., state changes) of a phase control signal in a motor phase of the motor. The method also includes the step of comparing the number of transitions to a predetermined number that is indicative of a predetermined motor load and/or motor speed. The predetermined number may comprise the number of transitions in a prior phase control signal of the motor. A method for controlling a motor responsive to a change in motor load and/or motor speed is also provided. The method includes the above-described steps for detecting a change in motor load and/or motor speed and further includes the step of selecting one of a plurality of operating modes for the motor responsive to a comparison value obtained by comparing the measured transition number with the predetermined transition number.

Sensing load and/or speed changes in a switched reluctance motor through

A method for controlling a motor and a circuit for implementing the method are provided. The method includes the steps of providing current to a first phase coil of a motor and measuring the time for the current to rise between two predetermined levels. Because current rise time is proportional to phase inductance, and therefore, rotor position, the measured current rise time can be compared to a desired current rise time to determine whether conduction intervals in the motor phases are in-phase with the position of the rotor or are lagging or leading the position of the rotor. The method finally includes the step of supplying current to one of the first phase coil and a second phase coil responsive to the measured rise time in order to bring subsequent conduction intervals into phase with the position of the rotor.

Sensorless switched reluctance motor control

A circuit and method for controlling a switched reluctance motor are provided. The circuit includes a phase coil and a switch that controls a current in the phase coil responsive to a hysteresis control signal. The circuit also includes a current sensor that measures the level of current in the phase coil and a comparator that compares the measured current level to a predetermined upper hysteresis current level. The circuit further includes a hysteresis control signal generating circuit that generates the hysteresis control signal responsive to the comparison signal and a timing signal that comprises a series of timing pulses. The hysteresis control signal assumes a first logic level whenever the measured level of current in the phase coil exceeds the predetermined upper hysteresis current level, thereby opening the switch and allowing current to dissipate from the phase coil. The control signal subsequently assumes a second logic level on the rising edge of the next timing pulse in the timing signal, thereby closing the switch and allowing the level of current in the phase coil to increase.

C-dump switched reluctance hysteresis control

A method and circuit for detecting a locked rotor in a switched reluctance motor are provided. The method includes the step of measuring, at a predetermined frequency, the time required for a current in the motor to rise or fall between predetermined current levels to thereby obtain a plurality of sample rise or fall times. The method further includes the step of comparing first and second sample times of the plurality of sample times to obtain a time comparison value that is indicative of a change in position of the rotor. Because current rise and fall times are indicative of, and vary with, rotor position, a comparison of multiple rise or fall times may be used to indicate a change in position of the rotor and, therefore, whether the rotor is in motion or is locked. The method may finally include the step of comparing the time comparison value to a predetermined reference value that is indicative of a locked rotor.

Sensorless detection of a locked rotor in a switched reluctance motor

A switched reluctance motor drive includes a noise reduction circuit configured to control the decay of current when a motor phase is switched from active to inactive. The current decay is controlled to occur in two stages: a first portion and a second portion. The first portion is controlled by alternately activating and deactivating one of the two switches in the two switch drive topology to obtain a current profile conforming to a predetermined profile. The current decay in the second portion of the inactive interval occurs by keeping both switches off so that it decays naturally. The duration of the first portion of the inactive interval is different for each motor phase, as is the duty cycle of the switch gating signal driving the switch that is alternately activated and deactivated. The scheme reduces the acoustic noise generated during operation of the motor.

Method and apparatus of reducing acoustic noise in switched reluctance

A method and circuit are disclosed for commutating a conduction cycle of a motor phase of a switched reluctance motor having a rotor portion thereof. The circuit includes a first switching device and a second switching device connected in series with a phase coil. A microcontroller closes both switching devices to connect the coil across a power supply to thereby initiate a conduction cycle. When a current level in the phase coil reaches a threshold level, only one switching device is modulated to control the current level between a local minimum level and a local maximum level. Rise and fall times of the current level between the local minimum and maximum levels are measured and an active phase time ratio is calculated using the rise and fall times. When the ratio, which is indicative of an angular position of the rotor in the switched reluctance motor, reaches a predetermined threshold value, the conduction cycle is commutated.

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Ann Arbor, MI, United States of America

Ramani R Kalpathi