Air conditioning device and corresponding power supply including a single buck converter with a SiC diode, an attenuator and a ferrite bead
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Solution Overview
Problem
Existing air conditioning devices using buck converters for auxiliary power supply face challenges with high cost, increased design complexity, and electromagnetic interference due to the need for multiple buck converters and bulky transformers.
Innovation Solution
The air conditioning device incorporates a buck converter with a SiC diode, an attenuator, and a ferrite bead, which reduces current spikes and allows for increased inductivity, thereby eliminating the need for multiple buck converters and reducing size and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If two high voltage buck converters are used in parallel to satisfy power demand, then sufficient output current is provided, but device complexity and cost increase
Solution Approach 1:
The patent changes the material parameter of the diode from conventional Si to SiC (silicon carbide), which has superior electrical characteristics including faster recovery time and lower on-resistance. This parameter change enables a single buck converter to handle higher power demands that previously required two converters, thereby reducing device complexity while maintaining sufficient output current capability
2Adaptability or versatility
If a flyback converter with transformer is used to step down high voltage, then different voltage levels are provided, but device size and cost increase
Solution Approach 1:
The patent extracts and eliminates the transformer component from the power conversion system by using a buck converter topology with SiC diode. This removal of the bulky transformer achieves the voltage stepping function through semiconductor switching and inductance, significantly reducing device volume while maintaining the capability to provide different voltage levels for various circuits
3Ease of manufacture
If conventional Si diode is used in buck converter, then device cost is lower, but current spikes occur during operation
Solution Approach 1:
The patent changes the material parameter of the diode from Si to SiC, which fundamentally alters the diode's recovery characteristics. SiC diodes have negligible reverse recovery time compared to Si diodes, eliminating the current spikes that occur during continuous current mode operation. This parameter change resolves the harmful effect while the overall system cost increase is offset by eliminating the need for multiple converters
4Temperature
If inductivity of inductor is increased to reduce ripple current, then thermal protection is avoided, but device size increases
Solution Approach 1:
The patent changes the diode material parameter to SiC, which eliminates current spikes and reduces ripple current. This allows the use of a smaller inductor with lower inductivity to achieve the same thermal management performance, as the SiC diode's superior characteristics compensate for the reduced inductance, thereby avoiding thermal protection triggers without increasing device size
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
The solution effectively reduces current spikes and ripple current, allowing the buck converter to operate efficiently in continuous current mode, thus avoiding thermal protection triggers and enabling a single buck converter to suffice for power supply, resulting in a smaller and less costly device.
Implementation Method 1
A SiC diode has a negligible recovery time, in contrast to Si diodes which are typically used in buck converters. Therefore, current spikes are eliminated or at least strongly reduced due to the SiC diode
Implementation Method 2
Since such current spikes could also occur due to a leakage capacitance between the switching device and ground, the ferrite bead associated to the switching device also contributes to suppressing current spikes during startup
Implementation Method 3
Due to the attenuator associated to the SiC diode, the occurrence of current spikes during a startup of the air conditioning device and the buck converter can be prevented
Implementation Method 4
Due to the possibility of increasing the inductivity, the ripple current of the buck converter can be reduced such that triggering the thermal protection can be avoided
Data Source
AI summary
An air conditioning device includes a buck converter which comprises a switching device, an inductor, a diode and at least one capacitor. The diode is a SiC diode, and the buck converter further includes an attenuator associated to the SiC diode and a ferrite bead associated to the switching device.