Motor Driver ADC Sampling for High-Speed Back-EMF Detection
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Solution Overview
Problem
Conventional BLDC motor systems face challenges in accurately detecting back electromotive force voltage at high driving speeds due to complex detection circuits, leading to increased power consumption.
Innovation Solution
A motor driver utilizing an analog-to-digital converter (ADC) to sample voltage sensing signals at multiple points and convert them into digital data, followed by a back electromotive force voltage determination unit to determine the voltage based on this data, without the need for a comparator, thus simplifying the detection process.
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 the voltage, but the circuit complexity increases and power consumption increases
Solution Approach 1:
The patent extracts and eliminates the comparator component from the conventional detection circuit. By using only the ADC to sample and convert the back electromotive force voltage during the floating period, the circuit removes unnecessary elements while maintaining detection functionality, thus reducing circuit complexity without sacrificing measurement precision
Solution Approach 2:
The ADC is made to serve multiple functions: it samples the phase voltage during the floating period to detect the back electromotive force voltage, and also performs normal voltage sampling for motor control. This multi-functional use of the ADC eliminates the need for separate detection circuitry, reducing overall circuit complexity while maintaining accurate voltage detection
2Measurement precision
If a conventional back electromotive force voltage detection circuit is used, then the circuit can detect the voltage, but power consumption increases
Solution Approach 1:
By removing the comparator from the detection circuit, the patent eliminates the continuous power consumption associated with comparator operation. The ADC-only approach consumes power only during sampling periods, significantly reducing overall power consumption while maintaining the ability to accurately detect back electromotive force voltage
Solution Approach 2:
The detection is performed periodically during the floating period rather than continuously. The ADC samples the voltage only when the coil is floating, which occurs at specific intervals during motor operation. This periodic sampling approach reduces power consumption compared to continuous monitoring while still providing accurate voltage detection data for motor control
3Speed
If the driving speed of the BLDC motor increases, then the motor performance improves, but the back electromotive force voltage becomes difficult to detect
Solution Approach 1:
The patent performs voltage sampling during the floating period, which occurs before the coil is actively driven. By capturing the back electromotive force voltage signal during this preliminary floating phase, the system can accurately detect the voltage even at high speeds where the signal might otherwise be lost or obscured during active switching periods
Solution Approach 2:
The patent replaces the mechanical/physical limitation of high-speed signal detection with a digital sampling approach. By using the ADC to capture voltage samples during the floating period and processing these digitally, the system overcomes the limitations of analog detection at high frequencies, enabling accurate back electromotive force voltage detection even when the motor operates at high 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 approach allows for accurate and efficient detection of back electromotive force voltage even at high speeds, reducing power consumption and minimizing noise interference, while maintaining low circuit complexity.
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
AI summary
A motor driver 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.