Three-phase brushless motor state identification
AssigneeSemiconductor Components Industries, LLC
InventorFumio KUMAZAWA
Life of this patent
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Abstract
A method for determining the state of a brushless motor having first, second and third phases, in some embodiments, comprises: decoupling said motor from a power source; determining whether said motor is rotating or non-rotating; if the motor is rotating, determining a first phase voltage state relative to a common voltage and a second phase voltage state relative to the common voltage, said first phase and second phase voltage states determined when a third phase voltage is within a predetermined range of said common voltage; and if the first phase voltage state and the second phase voltage state are the same, repeating said determination as to whether the motor is rotating or non-rotating.
Claims20
A system for determining a state of a motor, comprising:
- a motor driving circuit operable to couple to and drive the motor associated with first, second and third phases;
- a control circuit coupled to the motor driving circuit;
- a first bias circuit coupled at a first input to a first node and coupled at a second input to the control circuit;
- a second bias circuit coupled at a first input to the first node and coupled at a second input to the control circuit;
- a first comparator coupled at a first input to a second node and coupled at a second input to an output of the first bias circuit;
- and
- a second comparator coupled at a first input to the second node and coupled at a second input to an output of the second bias circuit.
An apparatus for determining a state of a motor, comprising:
- a first comparator;
- a second comparator;
- and
- a control circuit coupled to the first comparator and the second comparator and operable to:
- determine that the motor is rotating when an output of the first comparator and an output of the second comparator are both positive or are both negative;
- determine a voltage of a first phase of the motor relative to a common voltage present at a common node of the motor when the motor is rotating and a voltage of a third phase of the motor is approximately equal to the common voltage;
- and
- determine a voltage of a second phase of the motor relative to the common voltage present at the common node when the motor is rotating and a voltage of the third phase of the motor is approximately equal to the common voltage.
A system, comprising:
- a motor driving circuit operable to couple to and drive a motor associated with first, second and third phases;
- a control circuit coupled to and operable to control the motor driving circuit;
- a first comparator operable to:
- receive a first biased version of a common voltage at one input and a first phase voltage, a second phase voltage, or a third phase voltage at another input;
- and
- provide an output of the first comparator to the control circuit;
- and
- a second comparator operable to:
- receive a second biased version of the common voltage at one input and the first phase voltage, the second phase voltage, or the third phase voltage at another input;
- and
- provide an output of the second comparator to the control circuit, wherein, the control circuit is further operable to:
- determine that the motor is rotating when the outputs of the first and second comparators are both positive or are both negative;
- determine a first phase voltage state relative to the common voltage when the motor is rotating and a third phase voltage is approximately equal to the common voltage;
- and
- determine a second phase voltage state relative to the common voltage when the motor is rotating and the third phase voltage is approximately equal to the common voltage.
Dependencies are inferred from the claim text.