Power Supply Apparatus Noise Reduction via Dynamic Switching
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Solution Overview
Problem
Conventional power supply systems with frequency converters cause switching frequency fluctuations in electric motors, leading to noise disturbances, particularly in noise-sensitive environments like elevator systems without machine rooms, where existing noise filters are insufficient to reduce noise effectively.
Innovation Solution
A power supply apparatus with a controllable solid-state switch topology that adjusts switching frequencies based on load conditions to minimize noise, using a network bridge with diodes and controllable switches to manage power loss and select optimal switching frequencies for reduced noise levels without additional filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If separate noise filters are added to the supply cables between the electric motor and the frequency converter, then noise reduction is achieved, but device complexity increases
Solution Approach 1:
The invention extracts the noise filtering function from separate external filters and integrates it into the frequency converter's control system. The control unit processes motor current signals internally to generate compensating signals that cancel noise, eliminating the need for separate noise filters in the supply cables while maintaining noise reduction effectiveness.
Solution Approach 2:
The frequency converter's control unit is given multiple functions: it not only controls the switching of power semiconductor devices for motor drive but also performs noise filtering by processing current signals and generating compensating signals. This multi-functionality integrates noise reduction capability into the existing control system without adding separate dedicated noise filter components.
2Power
If switching frequency is increased to improve power conversion performance, then power loss in solid-state switches increases, but noise generation also increases
Solution Approach 1:
The control unit continuously monitors motor current signals and uses this feedback to determine optimal switching frequencies. Based on the feedback from current measurements, the system adjusts switching frequency to balance power conversion performance with power loss and noise considerations, selecting lower frequencies when appropriate to reduce power loss while maintaining adequate performance.
Solution Approach 2:
The switching frequency is made dynamic rather than fixed. The control unit adjusts switching frequency based on operating conditions, load requirements, and noise considerations. This dynamic adjustment allows the system to optimize the balance between power conversion performance and power loss by selecting appropriate frequencies for different operating scenarios.
Data Source
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AI summary
The invention relates to a power supply apparatus (1) and also to a power supply arrangement. The power supply apparatus comprises an interface to the load (2). The power supply apparatus also comprises at least one controllable solid-state switch (3), for supplying power between the aforementioned load and the power supply apparatus. The power supply apparatus comprises a control (7), which is fitted to control the aforementioned at least one controllable solid-state switch (3) at the selected switching frequency. The switching frequency is selected such that the noise of the load corresponding to the selected switching frequency meets the selection criterion.