Brushless Motor Voltage Utilization via 5th Order Harmonic Superposition
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Solution Overview
Problem
Brushless motors face limitations in increasing torque and output due to restricted current flow and voltage utilization ratios when using trapezoidal waveforms for phase currents, as the peak current value is difficult to suppress, leading to inhibited motor performance.
Innovation Solution
A brushless motor design that superimposes a 5th or 7th order harmonic component on the 1st order fundamental wave of the voltage, with specific phase differences and amplitude ratios, to increase the 1st order fundamental wave peak and enhance voltage utilization ratios, thereby increasing torque and output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a trapezoidal waveform is used for phase current to increase torque, then torque increases, but peak current value becomes difficult to suppress and current flow is restricted
Solution Approach 1:
The patent changes the waveform parameters by superimposing a 5th order harmonic component on the 1st order fundamental wave of the applied voltage. This transforms the voltage waveform to achieve a trapezoidal phase current waveform while controlling the peak current value through specific harmonic amplitude ratios (2%-12%), thereby resolving the contradiction between increasing torque and suppressing peak current.
2Force
If a trapezoidal waveform is used for phase current to increase torque, then torque increases, but voltage utilization ratio decreases
Solution Approach 1:
The patent optimizes the voltage waveform parameters by superimposing a 5th order harmonic component with specific amplitude ratio (2%-12%) and phase difference (150°-210°) on the 1st order fundamental wave. This parameter optimization increases the 1st order fundamental wave peak relative to the total voltage peak, thereby improving voltage utilization ratio while maintaining the torque-enhancing trapezoidal current waveform.
3Use of energy by moving object
If the 1st order fundamental wave peak is increased over the voltage peak to improve voltage utilization, then voltage utilization ratio increases, but voltage harmonic components are generated in armature windings
Solution Approach 1:
The patent converts the potentially harmful voltage harmonic component into a beneficial element by deliberately superimposing a controlled 5th order harmonic on the applied voltage. Instead of trying to eliminate harmonics, the invention uses the 5th order harmonic to shape the phase current into a trapezoidal waveform that increases torque, while controlling the harmonic amplitude to maintain high voltage utilization ratio.
4Reliability
If external AC voltage source is limited in peak voltage, then safety and stability are maintained, but torque and output are restricted
Solution Approach 1:
The patent changes the voltage waveform parameters by adding a 5th order harmonic component with specific amplitude ratio (2%-12%) and phase difference (150°-210°). This transforms the voltage waveform to increase the 1st order fundamental wave peak within the existing voltage peak limit, thereby extracting more torque and power from the same voltage source without compromising stability.
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 proposed solution effectively increases the voltage utilization ratio and motor output by enhancing the 1st order fundamental wave peak, leading to improved torque and reduced torque ripples and circulating currents, while maintaining efficient operation within existing voltage constraints.
Implementation Method 1
A brushless motor includes an armature constituted by an armature core having armature windings of a plurality of phases, and a field pole constituted by a field pole core having a plurality of permanent magnets
Data Source
AI summary
The present invention provides a brushless motor in which the voltage utilization ratio can be increased and the torque and output of the motor can thereby be increased, and also provides a drive method for a brushless motor. The brushless motor includes an armature constituted by an armature core having armature windings of a plurality of phases, and a field pole constituted by a field pole core having a plurality of permanent magnets. A voltage, in which at least a 5th order harmonic component is superimposed on a 1st order fundamental wave of a voltage under predetermined phase difference condition and amplitude condition in order to increase a 1st order fundamental wave peak of the applied voltage over an applied voltage peak, is applied to the armature windings.