Isolated Three-Phase Inverter Circuits for Unbalanced Load Control
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Solution Overview
Problem
Inverter systems regulating line to line voltage face challenges with unbalanced loads, requiring high-voltage DC buses, large and costly capacitors, and high-voltage switches, which complicate voltage control and increase system complexity and inefficiency.
Innovation Solution
Implementing a line to neutral regulation scheme with isolated inverter circuits, each supplied by a dedicated isolated bus, allowing for individual phase current control and reduced DC bus voltage, using switches rated for lower voltages and smaller capacitors, and employing isolation devices like transformers or DC-DC converters to maintain electrical isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If line to line voltage regulation is used, then voltage control capability is improved, but system complexity and cost increase due to high-voltage DC buses, large capacitors, and high-voltage switches
Solution Approach 1:
The patent divides the three-phase inverter system into three separate single-phase inverter circuits, each with its own isolated DC bus. This segmentation allows each phase to be controlled independently with lower voltage components, reducing overall system complexity while maintaining voltage control capability through individual phase regulation.
Solution Approach 2:
The patent introduces isolation devices (transformers or DC-DC converters) as intermediaries between the isolated DC buses and the AC output. These intermediaries enable voltage regulation and electrical isolation without requiring high-voltage switches or large capacitors directly in the inverter circuit, thereby reducing system complexity.
2Ease of operation
If line to line voltage regulation is used, then voltage control capability is improved, but component costs increase due to high-voltage DC buses, large capacitors, and high-voltage switches
Solution Approach 1:
By segmenting the inverter into three independent single-phase circuits with isolated DC buses, the patent enables the use of lower-voltage switches and smaller capacitors in each circuit. This segmentation directly reduces component costs while preserving voltage control capability through independent phase regulation.
Solution Approach 2:
The patent changes the voltage parameter from high-voltage line-to-line regulation to lower-voltage line-to-neutral regulation with isolated buses. This parameter change allows the use of lower-voltage rated switches and smaller capacitors, significantly reducing component costs while maintaining effective voltage control.
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 simplifies voltage regulation, reduces component costs and size, enhances efficiency, and provides improved electromagnetic immunity and fault detection, while maintaining isolation and preventing electrostatic discharge.
Implementation Method 1
employing isolation devices like transformers or DC-DC converters to maintain electrical isolation
Implementation Method 2
maintaining isolation and preventing electrostatic discharge
Data Source
AI summary
In one embodiment, an inverter system is disclosed. The system includes a plurality of inverter circuits, each inverter circuit configured to provide a respective alternating current (AC) signal to an output. The system further includes a plurality of rectifier circuits configured to supply respective direct current (DC) signals to the plurality of inverter circuits, and an alternator comprising inductively-coupled windings and configured to provide respective AC power to the plurality of rectifier circuits. The plurality of rectifier circuits are synchronous rectifier circuits configured to drive the alternator in reverse to transfer power to another one of the plurality of rectifier circuits via the respective windings.