BLDC Inverter Switch Thermal Management
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Solution Overview
Problem
The power loss in BLDC motor circuit systems, caused by heating of inverter components, limits the maximum power that can be supplied to BLDC motors, necessitating a method to enhance energy delivery while minimizing heat generation and system size.
Innovation Solution
A circuit system with at least three control stages for a three-phase BLDC motor, where high-side and low-side switches are selectively grouped and controlled during freewheeling phases to distribute heat dissipation efficiently, allowing only one group to be loaded and heated, thereby reducing overall heating and enabling increased energy supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If all switches are loaded during freewheeling phases, then the circuit system can supply more power, but the heating of switches increases and limits maximum power
Solution Approach 1:
The patent divides the six switches into two separate groups (first group: three switches, second group: three switches) and assigns them to different freewheeling phases. This segmentation allows selective loading of switch groups, preventing all switches from being heated simultaneously and enabling higher overall power delivery.
Solution Approach 2:
The patent implements periodic alternation between loading the first group of switches during first freewheeling phases and loading the second group of switches during second freewheeling phases. This periodic switching distributes thermal load over time, allowing the circuit system to sustain higher power levels without exceeding thermal limits of individual switches.
2Power
If the circuit system is dimensioned larger to supply more power, then more energy can be delivered, but the constructive space requirement and costs increase
Solution Approach 1:
The patent employs dynamic control of switch groups based on thermal conditions. By monitoring temperature or temperature-influencing quantities and adaptively selecting which switch group to load during freewheeling phases, the system optimizes power delivery without requiring oversized components, thereby reducing space requirements while maintaining high power capability.
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 energy delivery to BLDC motors by optimizing heat dissipation, reducing the constructive requirements and costs of the circuit system, while ensuring that switches do not overheat, thus enhancing the maximum power level and operational efficiency.
Implementation Method 1
the selected high-side switches or low-side switches are controlled in a freewheeling phase in such a way that the selected high-side switches or low-side switches form a freewheel during the freewheeling phase
Implementation Method 2
during the freewheeling phases either only the high-side switches or only the low-side switches are loaded, and thus heated
Data Source
AI summary
A method for operating a circuit system having at least three control stages for at least three phases, each of the control stages having a high-side switch and a low-side switch, each of the high-side switches and each of the low-side switches being capable of being brought into an electrically conductive state and into an electrically non-conductive state, a quantity being determined that influences the temperature of the high-side switches and/or of the low-side switches, either the high-side switches or the low-side switches being selected in a group as a function of the quantity influencing the temperature, and the selected high-side switches or low-side switches being controlled in a freewheeling phase in such a way that the selected high-side switches or low-side switches form a freewheel during the freewheeling phase.