Harmonic Current Waveform for High-Torque Electric Machine Drive
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Solution Overview
Problem
Conventional electric motor systems for vehicles face challenges in achieving high-torque and high-efficiency characteristics over a wide operating range without increasing copper and iron losses or compromising space constraints, especially in four-wheel drive vehicles and diesel engine vehicles that require higher torque.
Innovation Solution
The system supplies a stator coil of a rotating electric machine with a specific harmonic electric current waveform, obtained by superimposing third-order and (3+6n)th-order harmonic waveforms on a first-order harmonic waveform, to increase q-axis inductance and d-axis magnetic reluctance, thereby enhancing total torque production in high-torque regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the amount of electric current supplied to rotating electric machines is increased to meet high-torque requirements, then torque output is improved, but copper and iron losses increase
Solution Approach 1:
The invention changes the waveform parameter of the supplied electric current by superimposing specific harmonic waveforms (third-order and (3+6n)th-order) on the fundamental waveform. This parameter change enables the motor to generate higher torque at reduced current levels, thereby decreasing copper and iron losses while maintaining or improving torque output in high-torque regions
2Force
If the sizes of rotating electric machines are increased to provide higher torque, then torque output is improved, but the machines become difficult to accommodate in limited engine compartment space
Solution Approach 1:
By changing the current waveform parameters through harmonic superposition, the invention enables existing-sized motors to produce higher torque outputs. This allows the vehicle to achieve required torque performance without increasing motor size, thereby maintaining compact installation in limited engine compartment space
3Force
If third-order and (3+6n)th-order harmonic waveforms are superimposed on the first-order harmonic waveform to increase torque, then total torque production is improved, but the complexity of the drive apparatus increases
Solution Approach 1:
The invention achieves enhanced torque production by modifying the current waveform parameters through harmonic superposition. The control apparatus generates composite waveforms by adding specific harmonic components to the fundamental waveform, enabling increased torque output without requiring fundamental changes to the motor structure or drive system architecture
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 increased total torque production, achieving high efficiency in high-torque regions while minimizing losses and accommodating space constraints, by optimizing magnet torque and reluctance torque production.
Implementation Method 1
the rotor produces both magnet torque and reluctance torque
Implementation Method 2
the rotor produces both magnet torque and reluctance torque
Data Source
AI summary
A rotating electric machine drive system includes a rotating electric machine and a drive apparatus. The rotating electric machine includes a Y-connected three-phase stator coil. The drive apparatus supplies electric current to the stator coil and thereby drives the rotating electric machine. In a predetermined high-torque region, the drive apparatus supplies the stator coil with the electric current which has a waveform obtained by superimposing a specific harmonic waveform on a first-order harmonic waveform. The specific harmonic waveform is one of third-order and (3+6n)th-order harmonic waveforms, or a harmonic waveform which is obtained by synthesizing at least two of the third-order and (3+6n)th-order harmonic waveforms, where n is a natural number not less than 1. The specific harmonic waveform takes a negative integral value for a positive half cycle of the first-order harmonic waveform and a positive integral value for a negative half cycle of the first-order harmonic waveform.