Multiphase Motor Inverter Control via Phase Splicing
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Solution Overview
Problem
Existing control systems for voltage inverters in electric vehicles face challenges in minimizing switching losses while maintaining efficient use of available voltage and limiting current, often requiring dead time and being difficult to implement, especially when dealing with duty cycle constraints and harmonic injection.
Innovation Solution
A control system that determines and controls duty cycles based on supply voltage values and amplitude, incorporating phase sticking mechanisms to reduce switching losses by two-thirds, and uses modular design for easier implementation, with adjustable activation and deactivation thresholds to optimize operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If discontinuous methods are used to minimize switching losses, then switching losses are reduced, but the implementation becomes difficult and dead time must be imposed
Solution Approach 1:
The patent changes the parameter of duty cycle from continuous to discontinuous operation, allowing the inverter to switch between continuous and discontinuous modes based on operating conditions. This parameter change enables minimization of switching losses while avoiding the complexity and dead time constraints of purely discontinuous methods
2Power
If third order harmonic injection is used to increase linear voltage zone, then the amplitude of main harmonic is increased, but current effective value and losses increase
Solution Approach 1:
Instead of fully injecting third order harmonics which causes excessive current and losses, the patent applies partial action by using discontinuous duty cycle modulation that achieves the benefit of extended linear voltage zone without the full penalty of harmonic injection. The discontinuous operation provides sufficient voltage utilization improvement without proportionally increasing current effective value
3Power
If vector control is used to increase linear voltage zone, then voltage utilization is improved, but switching losses increase compared to scalar method
Solution Approach 1:
The patent introduces dynamic operation by allowing the duty cycle to switch between continuous and discontinuous modes based on real-time operating conditions. This dynamic approach enables the system to achieve high voltage utilization like vector control during high power demands while reducing to scalar-like operation during low power demands to minimize switching losses
Data Source
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AI summary
The invention relates to a system for controlling a voltage inverter, in particular for supplying power to a multiphase electrical motor of a motor vehicle, including a means for generating supply voltage values for each phase of the electrical motor, as well as an amplitude value for the supply voltages. The control system includes a phase-splicing determination means (19) and a phase-splicing control means (21) which interact so as to control the transmission of duty cycles, generated by duty-cycle determination means (28, 31, 34, 37, 40, 43, 46), to the voltage inverter (12), depending on the supply voltage values of each phase of the electrical motor, as well as on the amplitude value of the supply voltages.