Power Conversion Device Ground Wiring Separation for Noise Reduction
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Solution Overview
Problem
In harmonic restraint devices, noise interference from inverter circuits and voltage detectors leads to decreased precision in detecting harmonic components and bus voltage, causing reduced harmonic restraint performance due to potential differences between reference potentials.
Innovation Solution
A power conversion device with a DC power supply, power converter, control device, and separation device, where the separation device separates ground wirings between high-voltage and low-voltage system circuit groups, and a single node connects these ground wirings to maintain consistent ground potentials, preventing noise propagation and ensuring accurate voltage detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the inverter circuit and voltage detector are electrically isolated using a separation device, then noise introduction from the inverter circuit to the voltage detector is restrained, but a potential difference may occur between the reference potentials of the inverter circuit and controller
Solution Approach 1:
A separation device (isolation amplifier or transformer) is introduced as an intermediary between the inverter circuit and voltage detector. This mediator transfers voltage information while providing electrical isolation, thereby restraining noise from the inverter circuit from reaching the voltage detector while maintaining reference potential consistency through controlled connection points
Solution Approach 2:
The system establishes equipotential connections at specific points between the high-voltage inverter circuit ground and the low-voltage controller ground. By creating designated equipotential points, the reference potentials are kept consistent where needed while maintaining isolation elsewhere, preventing potential differences that would compromise system reliability
2Measurement precision
If noise is introduced into the current detector for detecting load current, then precision in extracting the harmonic component is decreased, but the harmonic restraint performance cannot be maintained
Solution Approach 1:
A separation device is placed between the inverter circuit and the control device to act as a mediator. This intermediary blocks noise from propagating to the control device while allowing necessary signal transmission, thereby preserving the precision of harmonic component extraction and maintaining harmonic restraint performance
3Measurement precision
If the bus voltage is required to be accurately detected to maintain voltage higher than system voltage, then detection precision must be high, but noise from the inverter circuit decreases detection precision
Solution Approach 1:
The separation device serves as a mediator between the noisy inverter circuit and the voltage detector. It allows accurate bus voltage detection by blocking noise from the inverter circuit while transmitting voltage information, thereby maintaining high detection precision despite the presence of harmful noise factors
Solution Approach 2:
The separation device extracts and isolates the voltage detection function from the noisy inverter circuit environment. By separating the detection function into an electrically isolated domain, the system achieves accurate voltage measurement free from inverter circuit noise interference
Data Source
AI summary
A power converter is configured to convert, into an AC voltage, a DC voltage supplied from a DC power supply connected between a first power supply wiring and a first ground wiring. A control device is connected between a second power supply wiring and a second ground wiring. The second power supply wiring is configured to supply a second power supply voltage lower than the first power supply voltage. The control device is configured to control the power converter. A separation device is configured to separate the first ground wiring and the second ground wiring from each other. The first ground wiring and the second ground wiring are electrically connected to each other at a single node.