BLDC Motor Driver Back-EMF Detection Using Multi-Point ADC Sampling
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Solution Overview
Problem
Conventional BLDC motor systems face challenges in detecting back electromotive force voltage accurately at high driving speeds due to complex detection circuits, leading to increased power consumption.
Innovation Solution
A motor driver with an analog-to-digital converter (ADC) that samples voltage sensing signals at multiple points and converts them into digital data, allowing for accurate back electromotive force voltage determination, even at high speeds, using a back electromotive force voltage determination unit that calculates averages and compares digital data to determine phase alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional back electromotive force voltage detection circuit is used, then the circuit can detect back electromotive force voltage, but the circuit complexity increases and power consumption increases as driving speed increases
Solution Approach 1:
The patent extracts the back electromotive force voltage detection function from the complex conventional detection circuit and implements it using only the ADC and existing phase voltage sensing signals. By taking out the detection function and implementing it through software processing of sampled voltage data during floating periods, the hardware circuit complexity is significantly reduced while maintaining detection accuracy even at high driving speeds
Solution Approach 2:
The patent replaces the conventional hardware-based back electromotive force voltage detection circuit with a software-based processing approach. Instead of using dedicated detection hardware, the system uses the ADC to sample phase voltage signals and processes the digital data through algorithms to determine back electromotive force voltage, thereby simplifying the physical circuit structure
2Measurement precision
If a conventional back electromotive force voltage detection circuit is used, then the circuit can detect back electromotive force voltage, but power consumption increases as driving speed increases
Solution Approach 1:
The patent makes the ADC serve multiple functions: it not only performs its standard conversion function but also simultaneously samples phase voltage signals during floating periods to enable back electromotive force voltage detection. This self-service approach eliminates the need for separate dedicated detection circuits, thereby reducing overall power consumption while maintaining detection capability
Solution Approach 2:
The patent merges the back electromotive force voltage detection function with the existing ADC and phase voltage sensing infrastructure. By combining multiple functions into existing hardware components rather than adding separate dedicated circuits, the total power consumption is reduced while achieving accurate detection across all driving speeds
3Speed
If the driving speed of the BLDC motor increases, then the motor performance improves, but the ability to accurately detect back electromotive force voltage deteriorates
Solution Approach 1:
The patent performs preliminary sampling of phase voltage signals during the floating period before the back electromotive force voltage becomes difficult to detect at high speeds. By capturing and storing digital voltage sampling data during this window opportunity, the system preserves detection capability even when the motor operates at high driving speeds where conventional methods fail
Solution Approach 2:
The patent implements a dynamic detection approach that adapts to varying driving speeds. The system determines whether to detect back electromotive force voltage based on the current operating conditions, using the ADC to sample at appropriate times during floating periods regardless of speed, thereby maintaining detection accuracy across the full speed range from low to high driving speeds
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 solution simplifies the back electromotive force voltage detection circuit, reduces power consumption, and enables accurate detection and speed control of BLDC motors at increased driving speeds, minimizing noise effects and torque ripple.
Implementation Method 1
an analog-to-digital converter (ADC) which, when a voltage sensing signal detected at a phase voltage of a specific coil in a floating period is input, samples the input voltage sensing signal at each of a plurality of sampling points and converts the voltage sensing signal into digital voltage sampling data
Implementation Method 2
a back electromotive force voltage determination unit which determines a back electromotive force voltage of the specific coil on the basis of a plurality of pieces of the digital voltage sampling data
Data Source
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AI summary
A motor driver according to one embodiment of the present disclosure includes an analog-to-digital converter (ADC) which, when a voltage sensing signal detected at a phase voltage of a specific coil in a floating period is input, samples the input voltage sensing signal at each of a plurality of sampling points and converts the voltage sensing signal into digital voltage sampling data and a back electromotive force voltage determination unit which determines a back electromotive force voltage of the specific coil on the basis of a plurality of pieces of the digital voltage sampling data.