Space Vector Modulation Minimum Dwell Time Multi-Phase Machine Control
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Solution Overview
Problem
Existing methods for controlling multi-phase electric machines using space vector modulation often result in increased line-to-ground voltages and insulation requirements, leading to inefficient use of materials and potential electrical stress.
Innovation Solution
Implementing a minimum dwell time for switching states and using substitute space vectors to prevent simultaneous switching of half-bridges, thereby reducing line-to-ground voltage loads and allowing for lower insulation strength, while adjusting switching states to maintain desired voltage profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If space vector modulation is used to control multi-phase electric machines, then effective voltage control is achieved, but increased line-to-ground voltages occur when half-bridges are switched simultaneously or almost simultaneously
Solution Approach 1:
The patent applies preliminary action by determining a minimum dwell time in advance before executing switching operations. This minimum dwell time is calculated based on signal propagation delays and switching times, ensuring that switching states are maintained long enough to prevent simultaneous switching of half-bridges, thereby avoiding voltage spikes before they can occur.
Solution Approach 2:
The patent implements preliminary anti-action by proactively preventing harmful voltage spikes through substitute space vectors. When a switching state would cause simultaneous half-bridge switching, the control device replaces it with a substitute space vector that maintains the desired voltage profile while avoiding the harmful voltage increase, thus counteracting the potential harm before it manifests.
2Reliability
If higher insulation strength is used to withstand increased line-to-ground voltages, then electrical stress is reduced, but the electric machine cannot be better utilized and insulation material space is wasted
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the minimum dwell time parameter based on operating conditions such as signal propagation delay and switching time. This optimization ensures the dwell time is long enough to prevent voltage spikes but not excessively long to waste switching opportunities, thereby achieving both electrical stress reduction and efficient machine utilization without over-engineering insulation requirements.
3Object-affected harmful factors
If switching states are maintained for minimum dwell time to prevent simultaneous switching, then line-to-ground voltage loads are reduced, but switching flexibility is constrained
Solution Approach 1:
The patent implements feedback by continuously monitoring the actual switching states and voltage profiles, then using this information to determine appropriate minimum dwell times and substitute space vectors. The control device adjusts switching strategies based on real-time conditions, maintaining voltage control while adapting to different operating scenarios and preserving switching flexibility where safe to do so.
Solution Approach 2:
The patent applies dynamics by making the minimum dwell time adaptive rather than fixed. The dwell time is dynamically determined based on signal propagation delay, switching time, and current operating conditions. This dynamic approach allows the system to maintain voltage control when necessary while preserving switching flexibility when conditions permit, optimizing both safety and performance.
Data Source
AI summary
A method and a converter for controlling a multi-phase electric machine are disclosed. Each phase voltage of the electric machine is generated with two electronic switches interconnected to form a half bridge. The switching statuses of the half bridges are controlled with space vector modulation. A minimum dwell time is predefined, and each switching status, represented by an active basic voltage space vector, of the half bridges is maintained at least for the minimum dwell time.