Systems and methods for motor position sensing
A system includes a controller, a magnetic field sensor, and a signal conditioning circuit. The magnetic field sensor is configured to sense a position of a motor and provide an output signal. The signal conditioning circuit is configured to produce an AC-coupled output signal from the output signal. The AC-coupled output signal is an input to the controller. The controller is configured to process the AC-coupled output signal.
1 . A system comprising:
a controller;
a magnetic field sensor configured to sense a position of a motor and provide an output signal; and
a signal conditioning circuit including a high-pass filter, wherein:
the signal conditioning circuit is configured to produce an AC-coupled output signal from the output signal,
the AC-coupled output signal is an input to the controller,
the signal conditioning circuit includes a first diode configured to limit voltages in the AC-coupled output signal to a lower limit, and a second diode configured to limit voltages in AC-coupled output signal to an upper limit, and
the controller is configured to process the AC-coupled output signal by counting a number of pulses in the AC-coupled output signal to determine a position of the motor.
2 . The system of claim 1 wherein the first diode and the second diode are integral to the controller.
3 . The system of claim 1 further comprising:
a plurality of magnetic field sensors; and
a plurality of signal conditioning circuits, wherein:
each magnetic field sensor is configured to sense the position of a corresponding motor, and
each of the signal conditioning circuits is configured to produce an AC-coupled output signal from the output signal of a corresponding magnetic field sensor.
4 . The system of claim 1 wherein the controller is configured to:
operate in an active mode or an inactive mode;
in response to being in the active mode, store a current state of each magnetic field sensor sensed at a respective controller input; and
in response to entering the active mode from the inactive mode, initialize each respective controller input to the stored state of the respective magnetic field sensor.
5 . The system of claim 4 wherein the controller is further configured to, in response to entering the inactive mode from the active mode, set each controller input in a logic high state or logic low state according to the current stored state of the respective magnetic field sensor.
6 . The system of claim 1 wherein each magnetic field sensor includes a hall effect sensor.
7 . The system of claim 1 wherein each motor is a DC motor.
8 . The system of claim 1 wherein each magnetic field sensor and corresponding motor includes an actuator.
9 . A vehicle comprising:
a motor;
a controller;
a magnetic field sensor configured to sense a position of the motor and provide an output signal; and
a signal conditioning circuit including a high-pass filter, wherein:
the signal conditioning circuit is configured to produce an AC-coupled output signal from the output signal,
the AC-coupled output signal is an input to the controller,
the signal conditioning circuit includes a first diode configured to limit voltages in the AC-coupled output signal to a lower limit, and a second diode configured to limit voltages in AC-coupled output signal to an upper limit, and
the controller is configured to process the AC-coupled output signal by counting a number of pulses in the AC-coupled output signal to determine a position of the motor.
10 . A method comprising:
configuring a magnetic field sensor to sense a position of a motor and provide an output signal;
conditioning the output signal by a signal conditioning circuit including a high-pass filter, wherein the signal conditioning circuit is configured to produce an AC-coupled output signal, and wherein the AC-coupled output signal is input to a controller; and
processing, by the controller, the AC-coupled output signal by counting a number of pulses in the AC-coupled output signal to determine a position of the motor, wherein the signal conditioning circuit includes a first diode configured to limit voltages in the AC-coupled output signal to a lower limit, and a second diode configured to limit voltages in AC-coupled output signal to an upper limit.
11 . The method of claim 10 , wherein the processing includes:
storing, in a controller, a current state of the magnetic field sensor; and
in response to the controller entering an active mode from an inactive mode, initializing an input of the controller that receives the AC-coupled output signal at a logic high state or logic low state according to the stored state of the magnetic field sensor.