Method and apparatus for switching a motor between bipolar and unipolar mode
AssigneeSGS-Thomson Microelectronics S.A.
InventorsLi-Hsin D. Lu, Karl M. Schlager
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Abstract
A method and apparatus for switching a motor between bipolar and unipolar mode. During each phase of the bipolar mode, one of the coils floats and has a back emf. In the method, first, a mode change signal requesting a change between the bipolar mode and the unipolar mode is received. Second, the back emf across the floating coil is monitored. Third, a point in time when the back emf equals the center tap voltage is detected. Last, the motor is switched between the bipolar mode and the unipolar mode at a point away from point in time when the back emf across the floating coil equals the center tap voltage. Various circuitry is also disclosed for switching a motor between a bipolar mode and a unipolar mode.
Claims13
A method of switching a motor between a bipolar mode and a unipolar mode, wherein the motor comprises a center tap and a plurality of coils and wherein, during each phase of said bipolar mode, one of said coils comprises a floating coil having a back emf, the method comprising the steps of:
- first receiving a mode change signal requesting a change between the bipolar mode and the unipolar mode;
- second, monitoring said back emf across said floating coils;
- third, detecting a point in time when said back emf equals said center tap voltage;
- and
- fourth, switching between the bipolar mode and the unipolar mode at a point in time after said point in time but before a second point in time where said back emf equals said center tap voltage.
A method of switching a motor between a bipolar mode and a unipolar mode, comprising the steps of:
- first, receiving a mode change signal requesting a change between the bipolar mode and the unipolar mode;
- second, detecting a high to high commutation cycle;
- and
- third, switching between the bipolar mode and the unipolar mode in response to both said first and second steps.
A circuit for switching a motor between a bipolar mode and a unipolar mode, wherein said motor comprises a plurality of coils and wherein, during each phase of said bipolar mode, one of said coils comprises a floating coil having a back emf, said circuit for switching a motor comprising:
- an input for receiving a mode change signal requesting a change between the bipolar mode and the unipolar mode;
- circuitry for detecting a commutation cycle comprising slope circuitry for determining a slope of said back emf for said floating coil;
- and
- circuitry for switching between the bipolar mode and the unipolar mode in response to said mode change signal and said circuitry for detecting a commutation cycle.
A motor controller circuit comprising:
- a power circuit operable to output a plurality of voltage potentials to a respective plurality of coils of a motor;
- a sequence circuit coupled to said power circuit for controlling the sequence of operation of said power circuit;
- an input for receiving a mode change signal requesting a change between the bipolar mode and the unipolar mode;
- circuitry for detecting a high to high commutation cycle;
- and
- circuitry for switching between the bipolar mode and the unipolar mode in response to said mode change signal and said circuitry for detecting a high to high commutation cycle.
Dependencies are inferred from the claim text.