Ripple count circuit
地域：
Sully sur Loire
摘要
A motor control system includes a variable voltage supply in signal communication with a direct current (DC) motor. The DC motor includes a rotor induced to rotate in response to a drive current generated by a variable supply voltage delivered by the voltage supply. The rotation of the rotor generates a mechanical force that drives a component. A ripple count circuit is configured to filter the drive current based on a rotational speed (ω) of the rotor, and to generate a pulsed output signal indicative of the rotational speed (ω) of the rotor and a rotational position (θ) of the rotor.
說(shuō)明書
This application is a National Stage of International Application No. PCT/EP2019/050394, filed Jan. 9, 2019, which claims benefit of French Application No. 18/50169, filed Jan. 9, 2018, the disclosures of which are incorporated by reference herein in their entirety.
Exemplary embodiments of the present disclosure are related to direct current (DC) motors, and more particularly, to DC motors for operating electrically operated automotive components.
Automobile vehicles are increasingly equipped with electrically operated components. For example, vehicles typically include sliding roofs, window glass regulators, or rear view mirrors driven by electric DC motors. Information indicating the rotor speed of the motor can be utilized to determine a position of the component (e.g., the window). Conventional position measurement systems utilize a sensor in conjunction with a magnetic ring to determine the rotor speed of the motor. For example, a Hall Effect Sensor (HES) detects movements of a magnetic ring integrated with the rotor. The magnet ring generates a magnetic flux of varying strength towards the HES depending on the relative axial position of the magnetic ring and sensor. The magnetic flux induces a current, and variations in magnetic flux result in variations in the induced currents. Accordingly, the frequency of the current measured by the HES is indicative of the rotor speed of the DC motor.
權(quán)利要求
What is claimed is:1. A motor control system comprising:a controller configured to generate a variable supply voltage; a direct current (DC) motor configured to operate according to a drive current that is induced in response to receive the variable supply voltage, the DC motor including a rotor induced to rotate in response to the drive current generated by the variable supply voltage, the rotation of the rotor generating a mechanical force that drives a component; and a ripple count circuit in signal communication with the controller, the ripple count circuit configured to filter the drive current based on a rotational speed (ω) of the rotor to generate at least one filtered drive current, and to generate a pulsed output signal indicative of the rotational speed (ω) of the rotor and a rotational position (θ) of the rotor based on the at least one filtered drive current, wherein the ripple count circuit includes a bandwidth filter having variable center frequency (fo) that is actively set according to the rotational speed (ω) of the rotor so as to filter the drive current based on the rotational speed (ω) of the rotor. 2. The motor control system of claim 1 , wherein the ripple count circuit compares the at least one filtered drive current to a reference voltage potential, outputs the pulsed output signal having a first output voltage level when a voltage level of the at least one filtered drive current is greater than or equal to the reference voltage potential, and outputs the pulsed output signal having a second output voltage level when the voltage level of the at least one filtered drive current is less than the reference voltage potential. 3. The motor control system of claim 1 , wherein the ripple count circuit includes a downstream low pass filter disposed downstream from the bandwidth filter, the downstream low pass filter configured to eliminate harmonics from the filtered drive current. 4. The motor control system of claim 3 , wherein the downstream low pass filter has varying frequency cutoff that is actively set according to the rotational speed (ω) of the rotor. 5. The motor control system of claim 1 , wherein the controller varies a voltage level of the variable supply voltage based on at least one of the rotational speed (ω) and the rotational position (θ) indicated by the pulsed output signal. 6. A ripple count circuit comprising:an amplifier configured to amplify a drive current that drives rotation of a rotor included in a direct current (DC) motor; a current differential circuit configured generate a derivative current signal that indicates an instantaneous rate of current change (d(i)/dt)) of the drive current; a bandwidth filter configured to filter the derivative current signal based on a rotational speed (ω) of the rotor so as to output a first filtered signal; a downstream low pass filter configured to filter the first filtered signal based on the rotational speed (ω) of the rotor so as to output a second filtered signal that eliminates harmonics from the first filtered signal; and a comparator circuit configured to compare the second filtered signal to a reference voltage potential, and generate a pulsed output signal having a first output voltage level when a voltage level of the second filtered signal is greater than or equal to the reference voltage potential, and a second output voltage level when the voltage level of the second filtered signal is less than the reference voltage potential, wherein the pulsed output signal indicates the rotational speed (ω) of the rotor and a rotational position (θ) of the rotor. 7. The ripple count circuit of claim 6 , wherein the bandwidth filter has variable center frequency (fo) that is actively set according to the rotational speed (ω) of the rotor so as to filter the derivative current signal based on the rotational speed (ω) of the rotor. 8. The ripple count circuit of claim 6 , wherein the downstream low pass filter filters the first filtered signal according to a varying frequency cutoff that is actively set according to the rotational speed (ω) of the rotor. 9. A method of determining a rotor speed of a direct current (DC) motor, the method comprising:generating a variable supply voltage; applying the variable supply voltage to the DC motor to induce a drive current, and rotating a rotor included in the DC motor based on the drive current; generating a mechanical force in response to rotating the rotor to drive a component; filtering the drive current based on a rotational speed of the rotor to generate at least one filtered drive current; and based on the at least one filtered drive current, generating a pulsed output signal indicative of the rotational speed (ω) of the rotor and a rotational position (θ) of the rotor, wherein filtering the drive current comprises:delivering the drive current to a bandwidth filter having variable center frequency (fo) that is actively set according to the rotational speed (ω) of the rotor; and outputting the at least one filtered drive current from the bandwidth filter according to the variable center frequency (fo). 10. The method of claim 9 , wherein generating the pulsed output signal comprises:comparing the at least one filtered drive current to a reference voltage potential; outputting the pulsed output signal having a first output voltage level when a voltage level of the at least one filtered drive current is greater than or equal to the reference voltage potential; and outputting the pulsed output signal having a second output voltage level when a voltage level of the at least one filtered drive current is less than the reference voltage potential. 11. The method of claim 9 , wherein filtering the drive current comprises performing, by the bandwidth filter, a first filtering operation on the drive current, the first filtering operating including a bandwidth filtering operation that filters the drive current based on a varying center frequency that is actively set based on the rotational speed (ω) of the rotor. 12. The method of claim 11 , wherein filtering the drive current further comprises performing, by the bandwidth filter, a second filtering operation following the first filter operation to eliminate harmonics from the at least one filtered drive current. 13. The method of claim 12 , wherein the second filtering operation includes performing a low pass filtering operation based on a frequency cutoff that is actively set according to the rotational speed (ω) of the rotor. 14. The method of claim 9 , further comprising actively adjusting a voltage level of the variable supply voltage based on at least one of the rotational speed (ω) and the rotational position (θ) indicated by the pulsed output signal.
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