SiC DC-DC Converter for High Power Density
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Solution Overview
Problem
Current DC-DC converters face inefficiencies and size constraints in high-power applications, particularly in achieving high power density and efficiency at high switching frequencies, which limits their performance in electric vehicle chargers and alternative energy conversion devices.
Innovation Solution
A DC-DC converter design incorporating a converter bridge with high-voltage silicon carbide MOSFETs, tank circuitry with resonant components, and rectifier circuitry, operating at zero voltage switching (ZVS) with a 2-level architecture, enabling high power levels and efficiency up to 99% and power density of 35-45 watts per cubic inch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional DC-DC converters are used, then they can provide power conversion functionality, but they achieve low power density and low efficiency at high switching frequencies
Solution Approach 1:
The patent changes the material parameter of the semiconductor switches from conventional silicon to silicon carbide (SiC). This material parameter change enables the converter to operate at high switching frequencies (above 225 kHz) with low losses, achieving both high power density (35-45 watts per cubic inch) and high efficiency (97.5-99.0%) simultaneously, which was not possible with conventional silicon-based converters
Solution Approach 2:
The patent implements zero voltage switching (ZVS) periodic operation mode, where the converter operates in discrete switching cycles with controlled on/off timing. This periodic action at high frequencies enables continuous power conversion while maintaining low switching losses, contributing to both high power density and high efficiency
2Volume of stationary object
If switching frequency is increased to reduce component size, then power density improves, but conventional converters cannot maintain efficiency
Solution Approach 1:
The patent changes the material parameter to silicon carbide, which has superior high-frequency characteristics compared to conventional silicon. This enables the converter to operate above 225 kHz with minimal switching losses, allowing significant reduction in component size while maintaining 97.5-99.0% efficiency
Solution Approach 2:
The high-frequency periodic switching operation (above 225 kHz) enables smaller inductors and capacitors to be used, reducing overall converter volume. The ZVS technique ensures that these high-frequency switches operate with minimal losses, resolving the contradiction between size reduction and efficiency maintenance
3Power
If high power levels are achieved, then output power increases, but converter efficiency and power density are compromised
Solution Approach 1:
The patent uses silicon carbide MOSFETs with high breakdown voltage capability to handle high power levels (5-20 kilowatts output). The SiC material's high electron saturation velocity and low on-resistance enable high current handling with minimal conduction losses, maintaining high power density (35-45 watts per cubic inch) even at elevated power levels
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 achieves high efficiency and power density, allowing the converter to operate at frequencies up to 500 kHz, significantly smaller component sizes, and sustained output power of 5-20 kilowatts with input voltages between 650-850 volts, surpassing silicon-based counterparts.
Implementation Method 1
The resonant frequency of the tank circuitry is greater than about 225 kilohertz as essentially defined by the magnetizing inductance, the resonant capacitance, and the resonant inductance
Implementation Method 2
The converter bridge may use a 2-level architecture that provides zero voltage switching (ZVS) and operates at high power levels
Implementation Method 3
The tank circuitry includes a resonant capacitance, a resonant inductance, and a transformer with a primary, a first secondary, and a second secondary
Data Source
AI summary
Disclosed is a DC-DC converter with a converter bridge, tank circuitry, and rectifier circuitry. In one embodiment, the converter bridge includes multiple switch circuits, which are formed with silicon carbide MOSFETs (metal on semiconductor field effect transistors), and are configured to provide a primary current. The tank circuitry includes a resonant capacitance, a resonant inductance, and a transformer with a primary, a first secondary, and a second secondary. The tank circuitry is configured to receive the primary current, and the transformer is associated with a magnetizing inductance. The resonant frequency of the tank circuitry is greater than about 225 kilohertz as essentially defined by the magnetizing inductance, the resonant capacitance, and the resonant inductance. The rectifier circuitry is coupled to the first secondary and the second secondary coil, and is adapted to provide a rectified output current.