Dynamoelectric Machine Control for Carrier Harmonic Reduction
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Solution Overview
Problem
Existing dynamoelectric machines with multiple three-phase windings struggle to effectively reduce carrier harmonics, leading to reduced efficiency due to unaddressed harmonic components, depending on the machine's characteristics and operating point.
Innovation Solution
A control method for a dynamoelectric machine that adjusts the time phase difference of electric currents and carrier frequencies between three-phase inverters to satisfy specific relationships based on the comparison of current amplitudes of primary and secondary carrier harmonic components, allowing for targeted reduction of harmonic components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If harmonics are shifted in phase between the two inverters to cancel harmonic components, then some harmonic components are reduced, but other components cannot be reduced or may be increased
Solution Approach 1:
The patent applies dynamics by making the phase shift amount variable rather than fixed. The control device dynamically adjusts the phase shift amount of carrier frequencies based on operating conditions (rotational speed, torque command value) to optimally reduce different harmonic components. This resolves the contradiction by adapting the harmonic reduction strategy to specific operating points, preventing efficiency degradation while reducing harmonics.
Solution Approach 2:
The patent changes the parameter of carrier frequency phase shift amount based on operating conditions. By varying this parameter according to rotational speed and torque requirements, the system can target different harmonic components for reduction without compromising efficiency. This parameter adaptation allows the system to maintain reliability while reducing harmful harmonic effects.
2Ease of operation
If a fixed phase shift method is used to reduce carrier harmonics, then the control method is simple, but it cannot adapt to different operating points and machine characteristics
Solution Approach 1:
The control system transitions from static to dynamic operation by continuously adjusting the phase shift amount based on real-time operating conditions. The control device monitors rotational speed and torque command values, then adapts the carrier frequency phase shift accordingly. This maintains ease of operation through automated control while achieving adaptability to various operating points and machine characteristics.
Solution Approach 2:
The patent implements feedback control by using detected rotational speed and torque command values to determine the optimal phase shift amount. This feedback mechanism allows the system to automatically adapt to different operating conditions without complex manual intervention, balancing control simplicity with operating point versatility.
Data Source
AI summary
A control method includes setting, when a space phase difference of in-phase coils of the respective groups is represented by α, a time phase difference of electric currents to be supplied to the in-phase coils of the respective groups is represented by β, and a time phase difference of carrier frequencies with which the three-phase inverters are PWM-controlled, respectively, is represented by γ, values of β and γ so that any one or both of the following relationships are satisfied: γ=±(α+2β), and γ=±(α−β)/2, based on a result of comparison between a current amplitude of a primary component and a current amplitude of a secondary component of a carrier harmonic current, to control the dynamoelectric machine.