Inverter Neutral-Point Layout to Lower Switch Current Capacity
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Solution Overview
Problem
Existing power conversion devices require large current capacity switches due to current flowing between electric storage units, leading to increased switch size and cost.
Innovation Solution
The power conversion device configures connection paths to bypass switches on certain target paths, allowing electric storage devices to connect directly to electric equipment without interposing switches, thereby reducing switch current capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If switches are provided on all main paths (positive electrode side, negative electrode side, and neutral point) to control current flow between electric storage units, then power transmission control and voltage equalization are improved, but switch current capacity and device cost increase
Solution Approach 1:
The patent extracts the switch from the neutral point path, removing it from the system. The neutral point connection is made directly between the battery connection point and the winding wire neutral point without interposing a switch, thereby eliminating the need for the neutral point switch while maintaining voltage equalization functionality through the other switches on the positive and negative electrode sides.
Solution Approach 2:
The switches on the positive electrode side main path and negative electrode side main path serve dual functions: they control power transmission to the inverter and simultaneously enable voltage equalization between the first and second electric storage units through the neutral point path. This multi-functionality eliminates the need for a separate neutral point switch.
2Reliability
If switches with high current capacity are used to handle current between electric storage units, then voltage equalization and power transmission are maintained, but switch size and manufacturing cost increase
Solution Approach 1:
The patent removes the neutral point switch from the system, eliminating the need for high current capacity switches in the neutral point path. Voltage equalization is achieved through the existing switches on the positive and negative electrode sides, which can be designed with lower current capacity requirements.
Solution Approach 2:
By eliminating the neutral point switch, the patent reduces the overall switch count and current capacity requirements, leading to lower manufacturing costs. The design uses simpler, lower-specification switches that are more cost-effective while still achieving the required voltage equalization function.
Data Source
AI summary
A power conversion device includes an inverter, rotating electrical machine, positive and negative electrode side main paths, neutral point path, switches provided on positive electrode side main path, negative electrode side main path and neutral point path, a first connection path that connects a first target path that is one of the positive electrode side main path, negative electrode side main path and neutral point path, and a first connection terminal of electric equipment, and a second connection path that connects a second target path that is one of the positive electrode side main path, negative electrode side main path and neutral point path other than the first target path, and a second connection terminal of the electric equipment. In the power conversion device, for example, a configuration where the first connection path is connected on electric storage device side of the switch in the first target path, is used.