Neutral-Point Clamped Power Converter for Insulation Size Reduction
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Solution Overview
Problem
Existing power conversion apparatuses require an increased size to ensure adequate electrical insulation for rotating electrical machines, leading to inefficiencies and larger overall dimensions.
Innovation Solution
A power conversion apparatus comprising a rotating electrical machine with star-connected windings, an inverter with series-connected upper and lower arm switches, a connecting path that links the negative terminal of one electrical storage, the positive terminal of another electrical storage, and the neutral point of the windings, a connecting switch to control this path, and a controller to determine when to turn on the connecting switch to execute switching control operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electrical insulation distance between windings is increased to ensure adequate electrical insulation, then the reliability of the rotating electrical machine is improved, but the overall size of the rotating electrical machine increases
Solution Approach 1:
The patent introduces a neutral point clamp switch as an intermediary component connected between the neutral point of the star-connected windings and the negative terminal of the first electrical storage. This switch enables dynamic control of the electrical potential at the neutral point, effectively reducing voltage stress on windings without requiring increased physical insulation distances, thus resolving the contradiction between reliability and size.
Solution Approach 2:
The patent changes the electrical parameter (voltage potential) at the neutral point by controlling the neutral point clamp switch. By dynamically adjusting the neutral point voltage through switching operations, the system reduces the voltage difference across windings, allowing for reduced insulation requirements while maintaining electrical reliability, thereby solving the size-reliability contradiction.
2Reliability
If additional components are added to meet switching control requirements, then the functionality and reliability are improved, but the device complexity and overall size increase
Solution Approach 1:
The neutral point clamp switch serves multiple functions: it enables switching control operations, reduces voltage stress on windings, and provides a path for neutral point current. By making this single component multi-functional, the patent avoids adding multiple separate components, thus improving reliability without proportionally increasing device complexity.
Data Source
AI summary
A power conversion apparatus includes a rotating electrical machine equipped with star-connected windings and an inverter equipped with series-connected units made up of upper arm switches and lower arm switches. The power conversion apparatus also includes a connecting path which electrically connects a negative terminal of a first electrical storage, a positive terminal of a second electrical storage connected in series with the first electrical storage, and a neutral point of the windings together, a connecting switch which is disposed in the connecting path, and a determiner which works to determine whether the connecting switch is required to be turned on, and a controller which turns on the connecting switch when it is determined by the determiner that the connecting switch is required to be turned on to execute a switching control operation on the upper arm switches and the lower arm switches.