Mutual inductance voltage offset compensation for brushless DC sensorless motors
First Claim
1. A control circuit for controlling operation of a brushless DC (BLDC) sensorless motor having a first terminal connected to a first winding, a second terminal connected to a second winding and a third terminal connected to a third winding, comprising:
- a drive control circuit configured to control the generation of drive signals for controlling application of pulses of a drive current through the motor between the first and second terminals and place the third terminal in a high-impedance state;
wherein each pulse of the drive current is applied to include a first portion of said pulse with a first current magnitude and a second portion of said pulse with a second current magnitude different from the first current magnitude;
a differencing circuit configured to sense within each pulse a first mutual inductance voltage at the third terminal in response to the first portion of said pulse of drive current at the first current magnitude and a second mutual inductance voltage at the third terminal in response to the second portion of said pulse of drive current at the second current magnitude, said differencing circuit further configured to determine a difference between the first and second mutual inductance voltages and produce a difference signal; and
a zero-crossing detection circuit configured to receive the difference signal and detect a zero-crossing condition of the difference signal that is indicative of a position of the rotor.
1 Assignment
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Accused Products
Abstract
A control circuit controls the operation of a brushless DC (BLDC) sensorless motor having a first terminal connected to a first winding, a second terminal connected to a second winding and a third terminal connected to a third winding. A driver circuit applies drive signals to the first and second terminals and places the third terminal in a high-impedance state. The drive signals include first drive signals at a first current amplitude and second drive signals at a second current amplitude different from the first current amplitude. A differencing circuit senses a first mutual inductance voltage at the third terminal in response to the first drive signals and senses a second mutual inductance voltage at the third terminal in response to the second drive signals. The differencing circuit further determines a difference between the first and second mutual inductance voltages and produces a difference signal that is used for zero-crossing detection and rotor position sensing.
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Citations
33 Claims
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1. A control circuit for controlling operation of a brushless DC (BLDC) sensorless motor having a first terminal connected to a first winding, a second terminal connected to a second winding and a third terminal connected to a third winding, comprising:
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a drive control circuit configured to control the generation of drive signals for controlling application of pulses of a drive current through the motor between the first and second terminals and place the third terminal in a high-impedance state; wherein each pulse of the drive current is applied to include a first portion of said pulse with a first current magnitude and a second portion of said pulse with a second current magnitude different from the first current magnitude; a differencing circuit configured to sense within each pulse a first mutual inductance voltage at the third terminal in response to the first portion of said pulse of drive current at the first current magnitude and a second mutual inductance voltage at the third terminal in response to the second portion of said pulse of drive current at the second current magnitude, said differencing circuit further configured to determine a difference between the first and second mutual inductance voltages and produce a difference signal; and a zero-crossing detection circuit configured to receive the difference signal and detect a zero-crossing condition of the difference signal that is indicative of a position of the rotor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A control circuit for controlling operation of a brushless DC (BLDC) sensorless motor having a first terminal connected to a first winding, a second terminal connected to a second winding and a third terminal connected to a third winding, comprising:
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a logic circuit configured to control the generation of drive signals for application for controlling application of pulses of a drive current through the motor between the first and second terminals and place the third terminal in a high-impedance state, wherein each pulse of the drive current is applied with a first portion of said pulse at a first current magnitude and a second portion of said pulse at a second current magnitude different from the first current magnitude; an analog-to-digital converter configured to sense within each pulse a first mutual inductance voltage at the third terminal in response to the drive current in said first portion of the pulse at the first current magnitude to generate a first digital signal and a second mutual inductance voltage at the third terminal in response to the drive current in said second portion of the pulse at the second current magnitude to generate a second digital signal; said logic circuit further configured to determine a difference between the first and second digital signals and produce a difference signal indicative of a difference between the first and second mutual inductance voltages; and a zero-crossing detection circuit configured to receive the difference signal and detect a zero-crossing condition of the difference signal that is indicative of rotor position. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33)
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Specification