PWM Motor Driver Carrier Tuning for Lower Torque Ripple
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Solution Overview
Problem
Existing motor drivers face challenges in reducing torque ripple while avoiding increased processing time and load, particularly due to harmonics generated by pulse width modulation (PWM) control of inverters.
Innovation Solution
A motor driver with a stator core having slots arranged at equal intervals, utilizing an inverter, DC voltage detector, voltage command generator, and gate signal generator, where the number of slots per magnetic pole is a natural number multiple of three, and the relationship between carrier and modulated wave frequencies follows Fc=6n+3, to reduce torque ripple through optimized PWM control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If current detection and estimation methods are used to reduce torque ripple, then torque ripple is reduced, but processing time and processing load increase
Solution Approach 1:
The invention extracts and eliminates the root cause of torque ripple by carefully selecting carrier frequency values (Fc=6n+3) that avoid harmonic overlap with slot harmonics, rather than using complex detection and estimation methods. This approach removes the harmful factor directly from the control parameter selection.
Solution Approach 2:
The invention changes the carrier frequency parameter to specific discrete values (Fc=6n+3 where n is a natural number) to avoid harmonic resonance with slot harmonics. This parameter optimization reduces torque ripple without requiring additional processing or detection mechanisms.
2Object-generated harmful factors
If complex calculation processing is used to reduce torque ripple, then torque ripple is reduced, but processing load increases
Solution Approach 1:
The invention extracts and eliminates the root cause of torque ripple by carefully selecting carrier frequency values (Fc=6n+3) that avoid harmonic overlap with slot harmonics, rather than using complex detection and estimation methods. This approach removes the harmful factor directly from the control parameter selection.
Solution Approach 2:
The invention changes the carrier frequency parameter to specific discrete values (Fc=6n+3 where n is a natural number) to avoid harmonic resonance with slot harmonics. This parameter optimization reduces torque ripple without requiring additional processing or detection mechanisms.
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 effectively reduces torque ripple while minimizing processing time and load, applicable to various AC motors including reluctance, permanent magnet, and induction motors, without requiring structural modifications.
Implementation Method 1
pulse width modulation (PWM) control of an inverter that drives an AC motor
Data Source
AI summary
A motor driver includes an inverter that converts a DC voltage into an AC voltage and applies the AC voltage to an AC motor, a DC voltage detector that detects the DC voltage applied to the inverter, a voltage command generator that generates a voltage command based on a torque command and a detection value of the DC voltage, and a gate signal generator that generates a gate signal for performing pulse width modulation control of the inverter. The number of slots per magnetic pole in the stator core of the AC motor is a natural number multiple of three, and there is a relationship of Fc=6n+3 between Fc and n, where Fc represents a numerical value as a carrier order obtained by normalizing the frequency of the carrier wave with the frequency of the modulated wave, and n is natural number.