Single Phase Motor Drive Circuit Dynamic Waveform Configuration
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Solution Overview
Problem
Single-phase brushless DC motor drivers face challenges in achieving linear speed control and reducing torque ripple and noise, particularly in applications requiring complex speed curves, due to their inherent design limitations and cost constraints.
Innovation Solution
A single-phase motor drive circuit that dynamically configures waveform parameters such as soft switching, lead angle, and off-time based on input signals, allowing for multi-segment speed curves that approximate linear target curves, while reducing noise and torque variation, and is implemented in a compact pin-count package without requiring a programmable processor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If single-phase brushless DC motor drivers use fixed waveform parameters, then device complexity is reduced and cost is lowered, but speed control linearity and torque ripple performance deteriorate
Solution Approach 1:
The patent implements dynamic configuration of waveform parameters (soft switching, lead angle, off-time) based on input signal levels. The motor driver transitions from fixed parameters to dynamically adjustable parameters, dividing the operating range into multiple segments with optimized parameters for each segment, thereby achieving linear speed control without requiring complex programmable processors
Solution Approach 2:
The patent changes physical parameters of the drive waveform (duration, timing, amplitude) based on operating conditions. By adjusting soft switching duration, lead angle, and off-time parameters across different input signal ranges, the system optimizes torque output and speed linearity while maintaining cost-effective implementation
2Manufacturing precision
If single-phase motor drivers use dynamic waveform configuration, then speed control linearity and torque performance are improved, but device complexity and silicon area increase
Solution Approach 1:
The patent divides the speed control range into multiple segments, each with optimized waveform parameters. This segmentation allows complex control characteristics to be achieved through simpler, dedicated control logic for each segment, reducing overall system complexity while maintaining high performance
Solution Approach 2:
The motor driver automatically selects and applies appropriate waveform parameters based on the input signal level without requiring external intervention or complex processing. The system self-configures its operation mode, eliminating the need for programmable processors while achieving adaptive optimization
3Ease of manufacture
If single-phase motor drivers minimize component count, then cost is reduced for high-volume markets, but capability to handle complex speed curves is limited
Solution Approach 1:
The patent creates a universal motor driver platform that can handle multiple speed curve requirements through dynamic parameter configuration. A single device design serves multiple applications by adapting waveform parameters, eliminating the need for different hardware variants while maintaining versatility
Solution Approach 2:
The motor driver transitions from static, application-specific designs to a dynamic, adaptive platform. By continuously adjusting waveform parameters based on operating conditions, the system achieves complex speed curve performance without requiring additional components or programmable logic
4Device complexity
If single-phase motor drivers use fixed soft switching settings, then device complexity is minimized, but noise and torque variation across different speeds cannot be optimized
Solution Approach 1:
The patent dynamically changes soft switching parameters (duration, timing) based on input signal levels and operating speed. This allows optimization of torque ripple and noise at different operating points without requiring complex processing, achieving quiet operation across the full speed range
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
The solution enables single-phase motor drivers to produce fan speed curves that fall within specified boundaries, optimizing noise and torque performance across varying motor speeds, and is cost-effective for high-volume markets by minimizing component count and silicon area.
Implementation Method 1
Brushless DC motors have the advantage that no brushes are needed, but they require a specific driving scheme, called 'electrical commutation' to change the direction of the current through the coil(s)
Implementation Method 2
The coil current is defined by the applied supply voltage VDD, minus the back EMF voltage (bemf) induced into the stator coil by the moving rotor magnet
Implementation Method 3
A first difference is that the torque of a single-phase or two-phase motor varies quite differently from that of a three phase motor
Data Source
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AI summary
A single phase motor drive circuit (600) for driving a single phase motor (690), comprising: a timer unit (701) for receiving a sensor signal indicative of an angular position of a rotor, and for providing a timing signal in phase with the sensor signal; a waveform generator (602) for generating a waveform for energizing the motor, the waveform generator being adapted for receiving the timing signal and a configurable setting, and for generating the waveform based thereon; a configuration unit (603) for receiving an input signal (691) indicative of a desired motor speed, the configuration unit being adapted for generating the configurable setting as a function of the input signal, and for providing the setting to the waveform generator to dynamically configure the waveform generator. A assembly and a cooling system comprising the single phase motor driver circuit (600). A method of driving a single phase motor (690).