Motor Driver ADC Back-EMF Detection at High BLDC Speeds
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Solution Overview
Problem
Conventional BLDC motor systems face challenges in detecting back electromotive force voltage accurately at high driving speeds, leading to increased power consumption and difficulty in controlling torque ripple.
Innovation Solution
A motor driver utilizing an analog-to-digital converter (ADC) to sample and convert voltage sensing signals into digital data, determining back electromotive force voltage based on multiple pieces of digital sampling data over N periods, minimizing the floating period and torque ripple.
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 existing hardware signals, the circuit complexity is significantly reduced while maintaining detection accuracy.
Solution Approach 2:
The phase voltage sensing signal serves multiple functions: it is used for both motor control and back electromotive force voltage detection. The ADC is utilized to convert both phase voltage signals and back electromotive force voltage signals. This multi-functionality eliminates the need for separate dedicated detection circuits, reducing overall system complexity.
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 extracts the detection function from power-hungry conventional circuits and implements it using the ADC with digital signal processing. This extraction replaces analog circuitry that consumes significant power at high speeds with a more efficient digital implementation, reducing power consumption while maintaining detection capability.
Solution Approach 2:
The system uses its own existing phase voltage sensing signals and ADC infrastructure to perform back electromotive force voltage detection without requiring additional dedicated detection circuits. This self-service approach eliminates the need for separate power-consuming detection hardware, as the existing components handle both motor control and detection functions.
3Measurement precision
If the floating period is extended to improve back electromotive force voltage detection, then detection accuracy improves, but torque ripple increases
Solution Approach 1:
The patent applies partial action by using only N periods (where N is a positive integer) of voltage sensing signals for back electromotive force voltage calculation, rather than requiring an extended floating period. This partial sampling approach achieves sufficient detection accuracy without extending the floating period, thereby avoiding increased torque ripple while still obtaining reliable detection data.
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
Accurate detection of back electromotive force voltage is achieved with reduced power consumption and minimized torque ripple, even at high driving speeds, without the need for complex circuits or additional noise cancellation.
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 a sampling point and converts the input 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 input for N periods
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 a sampling point and converts the input 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 input for N periods.