Parasitic Pulse Cancellation Circuit for Accurate Motor Ripple Counting
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Solution Overview
Problem
Conventional position measurement systems for DC motors in automotive components face inaccuracies due to parasitic pulses, which require expensive hardware modifications or CPU processing, and are inefficient at low voltages.
Innovation Solution
A motor control system incorporating an active filter circuit and a parasitic pulse cancellation circuit that adjusts a voltage threshold based on the rotational direction of the rotor to exclude parasitic pulses from the ripple count signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional position measurement systems use a Hall Effect Sensor to detect rotor speed, then the system can determine component position, but parasitic pulses contaminate the signal and reduce measurement precision
Solution Approach 1:
The patent extracts and removes parasitic pulses from the ripple signal by comparing the signal to a reference pattern. The microcontroller identifies and eliminates parasitic pulses that do not match the expected ripple pattern, extracting only the valid position information while discarding the harmful parasitic components.
Solution Approach 2:
The patent introduces a reference ripple pattern as an intermediary to mediate between the raw sensor signal and the final position calculation. This reference pattern serves as a template for comparing against the actual signal, allowing the system to distinguish valid ripple signals from parasitic pulses.
2Measurement precision
If expensive FPGAs are used to execute computations for obtaining ripple currents, then parasitic pulses can be eliminated, but the system cost increases significantly
Solution Approach 1:
The patent replaces expensive FPGAs with a low-cost microcontroller that uses software-based parasitic pulse elimination. The system uses affordable components including a standard microcontroller and Hall Effect sensor, achieving the same functional result without requiring high-end expensive hardware.
Solution Approach 2:
The patent substitutes hardware-based signal processing (FPGA) with software-based processing in a microcontroller. Instead of using complex electronic circuitry to filter and process signals, the system uses programmable logic to identify and eliminate parasitic pulses, reducing hardware complexity and cost.
3Measurement precision
If the motor assembly is structurally modified to generate a normalized ripple pattern, then parasitic pulses are eliminated, but the manufacturing cost and complexity increase
Solution Approach 1:
Instead of modifying the motor assembly to prevent parasitic pulses from being generated, the patent extracts and removes the parasitic pulses from the signal after they are generated. This approach leaves the motor assembly unchanged while still achieving clean position measurements.
Solution Approach 2:
The patent creates a software copy of the expected ripple signal pattern and uses it to compare against the actual sensor output. By copying the ideal signal pattern and comparing it with the real signal, the system can identify deviations caused by parasitic pulses without physically modifying the motor assembly.
4Measurement precision
If CPU processing is used to eliminate parasitic pulses, then signal accuracy improves, but processing time and power consumption increase
Solution Approach 1:
The patent performs preliminary action by pre-establishing a reference ripple pattern that represents the expected signal characteristics. This reference is created beforehand and stored in memory, allowing the microcontroller to quickly compare incoming signals against it without performing complex real-time calculations, thus reducing processing time.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach improves the accuracy of ripple count signals by effectively filtering out parasitic pulses, reducing CPU processing time and power consumption, and maintaining signal integrity at low voltages without costly hardware modifications.
Implementation Method 1
The active filter circuit is configured to filter the drive current and to generate a pulsed signal
Implementation Method 2
generates a ripple count signal that excludes parasitic pulses included in the pulsed signal having a parasitic voltage level that exceeds a voltage level of a voltage threshold
Implementation Method 3
The DC motor includes a rotor that rotates in response to a drive current. The rotation of the rotor generates a mechanical force that drives a component
Implementation Method 4
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
Data Source
AI summary
A motor control system includes a DC motor and a ripple count circuit. The DC motor includes a rotor that rotates in response to a drive current. The rotation of the rotor generates a mechanical force that drives a component. The ripple count circuit includes an active filter circuit and a parasitic pulse cancellation circuit. The active filter circuit is configured to filter the drive current and to generate a pulsed signal. The parasitic pulse cancelation circuit is in signal communication with the ripple count circuit to receive the pulsed signal and generates a ripple count signal that excludes parasitic pulses included in the pulsed signal having a parasitic voltage level that exceeds a voltage level of a voltage threshold. The parasitic pulse cancelation circuit actively adjusts the voltage level of the voltage threshold based at least in part on a rotational direction of the rotor.