Multi-Level Inverter Switching for Harmonic and Loss Reduction
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Solution Overview
Problem
Current electric drive systems in motor vehicles primarily use two-level inverters, which do not leverage the benefits of three-level or multi-level inverters due to higher costs, despite these topologies offering advantages like lower harmonics and higher voltage processing, limiting their adoption in electric vehicle applications.
Innovation Solution
A controllable three-level or multi-level inverter circuit that can switch between three-level and two-level operation based on overall efficiency, utilizing a novel operating mode setting device that considers phase current and other parameters to optimize efficiency, reducing losses and harmonics, particularly in double-rotor electric machines with solid flux-carrying material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If three-level or multi-level inverter topology is used, then harmonics are reduced and voltage processing capability is improved, but device complexity and cost increase
Solution Approach 1:
The inverter circuit is designed to dynamically switch between three-level operation mode and two-level operation mode based on real-time efficiency evaluation. The operating mode setting device continuously monitors system efficiency and adjusts the inverter topology accordingly, making the system adaptable rather than static. This resolves the contradiction by allowing the system to use the more complex three-level topology only when it provides harmonic reduction benefits, while falling back to the simpler two-level topology when complexity is not justified.
Solution Approach 2:
The invention changes the operational parameters of the inverter by introducing multiple voltage levels (three-level or multi-level) instead of the traditional two levels. This parameter change enables reduced harmonics and improved voltage processing capability. The system can adjust the voltage level parameter dynamically based on operating conditions, resolving the contradiction between harmonic reduction and complexity by making the parameter change conditional rather than fixed.
2Loss of energy
If three-level or multi-level inverter is used, then efficiency is improved through reduced harmonics and switching losses, but cost increases
Solution Approach 1:
The system dynamically evaluates overall efficiency considering phase current and other parameters, and switches between three-level and two-level operation modes accordingly. This dynamic adaptation ensures that the more complex three-level topology is used only when it provides measurable efficiency benefits in terms of reduced switching losses and harmonics, while avoiding unnecessary complexity when the simpler two-level topology suffices.
Solution Approach 2:
The invention introduces the ability to change the voltage level parameter from two levels to three or more levels based on operating conditions. By making this parameter change conditional and dynamic rather than fixed, the system achieves reduced switching losses and harmonics only when the complexity increase is justified by the efficiency gains under specific operating conditions.
3Productivity
If operating mode switching between three-level and two-level is implemented, then overall efficiency is optimized, but control complexity increases
Solution Approach 1:
The operating mode setting device implements dynamic switching between three-level and two-level operation modes based on real-time efficiency evaluation. The system continuously monitors phase current and other parameters, and adjusts the inverter operating mode dynamically to optimize overall efficiency. This dynamic control approach resolves the contradiction by automating the mode selection process rather than requiring complex manual or predetermined control strategies.
Solution Approach 2:
The invention incorporates feedback mechanisms where the operating mode setting device evaluates overall efficiency based on detected phase current and other parameters, then adjusts the inverter operating mode accordingly. This closed-loop feedback control optimizes productivity by continuously adapting to changing operating conditions, while the automated feedback process manages control complexity more effectively than open-loop or manually-controlled systems.
Data Source
AI summary
A three-level or multi-level inverter circuit for activation of a multiphase electric machine for an electric drive system, with two supply connections couplable to first and second supply potential of voltage supplies, a load output comprising a load output connection for each phase of the electric machine, a controllable three-level or multi-level inverter between the supply connections and the load output designed to convert a direct voltage received on the supply side into an alternating voltage for driving an electric machine, with an operating mode setting device designed to change the inverter between three-level or multi-level operation and two-level operation in dependence upon overall efficiency of the electric drive system, wherein the overall efficiency is a function of the detected phase current of the electric machine and at least one further parameter and/or property of the electric machine which influence the overall efficiency.