Method and apparatus for windowless bemf detection
AssigneeMarvell World Trade Ltd.
InventorRavishanker Krishnamoorthy
Life of this patent
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Abstract
A zero crossing of a motor current waveform at the terminal of a brushless sensor-less multi-phase DC motor is determined without opening a non-drive period while the motor is continuously driven. A voltage level at a first threshold at the terminal of a motor is detected. At a first time, a current flow switch connected to the terminal is switched. At a second time, a voltage level at a second threshold is detected at the terminal of the motor. The zero crossing is determined between the first time and the second time and used to synchronize the driving of the motor.
Claims20
A circuit with logic for windowless motor current waveform detection in a sensor-less motor, the logic configured to:
- detect a voltage level at a first threshold at a terminal of the sensor-less motor;
- at a first time, in response to detecting the voltage level at the first threshold, switch at least one current flow switch of the circuit;
- at a second time, detect a voltage level at a second threshold at the terminal of the sensor-less motor;
- and
- determine a zero crossing of the motor current waveform at the terminal of the sensor-less motor between the first time and the second time.
A method comprising:
- driving a terminal of a sensor-less motor;
- detecting a voltage level at a first threshold at the terminal of the sensor-less motor;
- at a first time, switching at least one current flow switch connected to the terminal of the sensor-less motor;
- at a second time, detecting a voltage level at a second threshold at the terminal of the sensor-less motor;
- and
- determining a zero crossing of a motor current waveform at the terminal of the sensor-less motor between the first time and the second time.
A system comprising:
- comparators configured to detect a voltage level at (i) a first threshold at a terminal of a motor and (ii) a second threshold at the terminal of the motor;
- a circuit having current flow switches connected to the terminal of the motor;
- and
- control logic configured to:
- determine that at least one of the comparators has detected a voltage level at the first threshold;
- switch at least one of the current flow switches at a first time;
- determine that at least one of the comparators has detected a voltage level at the second threshold at a second time;
- determine a zero crossing of a motor current waveform at the terminal of the motor between the first time and the second time;
- and
- based at least in part on the determined zero crossing, synchronize driving of the motor.
Dependencies are inferred from the claim text.