Fuel Cell Converter Frequency Control for Noise Inhibition
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Solution Overview
Problem
Fuel cell vehicle systems face noise generation and increased switching element temperature due to overlapping frequency bands in high load regions, particularly with multiple-phase converters, which existing techniques fail to adequately address.
Innovation Solution
Implementing a fuel cell system with frequency setting means to ensure non-overlapping driving frequency bands for the fuel cell converter, battery converter, and inverter, and using multiple-phase converters with distinct median frequencies to inhibit noise and maintain temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the switching frequency of the converter is increased to reduce magnetic noise, then magnetic noise is reduced, but the temperature of the switching element increases
Solution Approach 1:
The patent dynamically adjusts the switching frequency based on load conditions. At high loads, the switching frequency is set to a higher value (e.g., 10 kHz) to reduce magnetic noise, while at low loads, it is reduced to a lower value (e.g., 2 kHz) to decrease switching element temperature and improve efficiency. This dynamic adaptation resolves the contradiction between noise reduction and temperature control.
Solution Approach 2:
The patent changes the operating parameters (switching frequency) of the converter based on load conditions. By varying the switching frequency parameter from 2 kHz to 10 kHz depending on the load, the system optimizes both magnetic noise reduction and switching element temperature, resolving the technical contradiction between these two opposing requirements.
2Device complexity
If the driving frequency bands of the fuel cell converter and battery converter are set to overlap, then device complexity is reduced, but noise is generated due to resonance
Solution Approach 1:
The patent implements dynamic frequency band assignment where the fuel cell converter and battery converter operate with non-overlapping frequency bands (e.g., fuel cell converter at 2-5 kHz, battery converter at 7-10 kHz) when both are operating simultaneously. This dynamic frequency separation eliminates resonance noise while maintaining manageable device complexity through coordinated control.
Solution Approach 2:
The patent changes the operating frequency parameters of the converters based on which device is operating. When both fuel cell and battery are connected to the load, the system assigns distinct frequency bands to each converter to prevent resonance. This parameter adjustment resolves the contradiction between simplified device complexity and noise generation.
3Object-affected harmful factors
If the switching frequency is set higher than audible range to reduce noise, then audible noise is reduced, but the temperature of switching elements increases significantly
Solution Approach 1:
The patent dynamically adjusts switching frequency based on load conditions rather than maintaining a fixed high frequency. At high loads where cooling is effective, higher frequencies (10 kHz) reduce audible noise. At low loads where cooling is less effective, lower frequencies (2 kHz) prevent excessive temperature rise. This dynamic approach resolves the contradiction between noise reduction and temperature control.
Solution Approach 2:
The patent changes the switching frequency parameter from a fixed high value to a variable parameter that adapts to load conditions. This allows the system to achieve audible noise reduction at high loads while preventing temperature excessive increase at low loads, resolving the technical contradiction between these two opposing effects.
Data Source
AI summary
In a fuel cell system which includes a fuel cell converter and a battery converter, noise generated in a high load region in particular is effectively inhibited, and silence is improved. A fuel cell system includes a fuel cell converter provided between a fuel cell and a load device, and a battery converter provided between a battery and the load device. The fuel cell system includes frequency setting means for setting a driving frequency band of the fuel cell converter and a driving frequency band of the battery converter so that these driving frequency bands do not overlap when a load of the load device is more than a predetermined threshold.