CC BY
9Системы управления, космическая навигация и связь
УДК 621.31
N. N. Goryashin
Siberian State Aerospace University named after academician M. F. Reshetnev, Russia, Krasnoyarsk
SILICON CARBIDE SEMICONDUCTORS APPLICATION IN SOFT SWITCHING CONVERTER TOPOLOGIES
Conduction loss analysis and resonant tank design method for two soft switching types of high voltage boost converters with switches based on silicon carbide are proposed.
High frequency soft switching converters have perspectives in development of different power-supply systems. Applying soft switching modes in power converters, conversion frequency and power density can be increased with low switching losses on power transistors, and electromagnetic interference (EMI) level can be reduced significantly.
The fields of soft switching converters application can be off-line power systems and distributed power architectures where the requirements for power supplies are high power density, high efficiency and low electromagnetic noise.
On the other hand soft switching modes have more complex circuit design and control, additional passive and active components which can bring additional power loss. Also soft switching modes of active switches operation, as a rule, have voltage or current stress much higher than in the same topology under the hard switching (HS). Therefore efficiency advantage in comparison with hard switching mode depends on elements types and input-output voltages and currents.
Recently interest to widegap semiconductor devices as SiC, GaAs, GaN has increased. Silicon carbide (SiC) power electronic devices are expected to have better characteristics than their silicon counterparts. SiC devices have higher blocking voltage, lower on-state resistance and switching losses, higher thermal conductivity and operating temperatures [1-3]. In the first place it can be topical for high voltage and high-density applications. Low rise and fall time of the FETs based on SiC allow reducing the size and weight of the power electronics and cooling systems and increasing their efficiency without soft switching. But as a result of speed switching rising high-harmonic electro-magnetic radiation can be increased.
Therefore soft switching modes application in switch mode power supplies is the single way to reduce EMI and improve efficiency simultaneously.
The aim of the work is the search of ways to expand capability of DC/DC converters due to resonant mode of operations and SiC power electronic devices application, keeping main advantages of soft switching.
There are many ways to reach soft switching. But each of them has some drawbacks that limit its application, especially in high voltage converters.
In present paper analysis of high voltage boost converters where soft switching modes and widegap devices can be applied is shown. There are many different types of soft switching boost topologies. For analysis two types of step-up boost converter were taken: one of them is zero-current-switching (ZCS) converter [4] and the second one is zero-voltage-transition (ZVT) converter [5] with pulsed width modulation (PWM) control. Simplified circuit diagrams of these converters are shown in figure.
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b
ZCS PWM:
a - ZVT PWM; b - boost converter
The main theoretical waveforms and equations of ZVT PWM and ZCS PWM boost converters, which were used for research, are presented in original papers [4; 5].
Proposed analysis includes: comparative analysis of EMI level produced by switches action and conduction losses between hard and soft switching modes in the boost topology under equal conditions, research of the ways to optimize resonant tank parameters to provide minimum of circulating energy in switch cell.
To provide minimum conduction losses in both types of boost converters new design method was created. The main idea of this method is based on hypothesis that if resonant process uses compound tank which contains more than two elements as L and C, conduction losses during resonant cycle have extre-mum (minimum), which can be reached due to tank
Решетневские чтения
parameters variation. Therefore tank parameters can be optimized to provide minimum conduction losses under the soft switching saving.
Analysis of two soft switching modes in high voltage PWM boost converters with SiC devices application in comparison with hard switching mode has shown the following:
ZCS PWM boost topology has less first and high harmonics magnitude produced by switches action in comparison with ZVT and HS PWM converter, it provides reducing losses in the input choke (Lb) and EMI level, but ZVT PWM converter has less conduction losses. Analytical and numerical estimations have shown that ZCS PWM boost topology has total losses close to HS PWM boost converter with tank parameters that were calculated applying the new method under frequency 160 kHz, output voltage 400 V and output power up to 2,1 kW. As a result ZVT PWM boost converter has higher efficiency in comparison with classical HS PWM and ZCS PWM boost converters.
Also we can conclude that SiC switches application in proposed converter topologies allows reducing tank elements values due to lower turn-on and turnoff time in comparison with silicon analogs with blocking voltage higher than 400 V, under condition of soft switching mode keeping. Tank elements
values reduction provides little circulating energy and conduction losses as well. In this case high harmonic components will be increased, but not more than in hard switching mode.
References
1. McNutt, T. R. Silicon Carbide Power MOSFET Model and Parameter Extraction Sequence / T. R. McNutt, A.R. Hefner, Jr., H. A. Mantooth, et al. // IEEE Trans. on Power Electron. March. 2007. Vol. 22, № 2. P. 353-362.
2. Ong, A. A Comparison of Silicon and Silicon Carbide MOSFET Switching Characteristics / A. Ong, J. Carr, J. Balda, A. Mantooth // IEEE Region 5 Technical Conference (April 2007, Fayette-ville). P. 273-277.
3. Shen, Z. J. Power MOSFET Switching Loss Analysis: A New Insight / Z. J. Shen, Yali Xiong, Xu Cheng, Yue Fu, P. Kumar // IEEE Industry Applications Conference. Vol. 3. 2006. P. 1438-1442.
4. Carlos, A. Novel Zero-Current-Switching PWM Converters / A. Carlos, I. Barbi // IEEE Trans. Power Electron. Jun. 1997. Vol. 44, №. 3. P. 372-381.
5. Bodur, H. A New ZVT-PWM DC-DC Converter / H. Bodur, F.Bakan // IEEE Trans. Power Electron. Jan. 2002. Vol. 17, № 1. P. 40-47.
Н. Н. Горяшин
Сибирский государственный аэрокосмический университет имени академика М.Ф. Решетнева, Россия, Красноярск
ПРИМЕНЕНИЕ ПОЛУПРОВОДНИКОВЫХ ПРИБОРОВ НА ОСНОВЕ КАРБИДА КРЕМНИЯ В РЕЗОНАНСНЫХ ПРЕОБРАЗОВАТЕЛЯХ НАПРЯЖЕНИЯ
Рассмотрены два варианта преобразователей постоянного напряжения повышающего типа с резонансным переключением коммутирующих элементов и возможность применения в них силовых полупроводниковых приборов на основе карбида кремния.
© Горяшин Н. Н., 2009
УДК 621.39;621.391.82
А. Л. Дерябин, А. В. Кузовников
Сибирский государственный аэрокосмический университет имени академика М. Ф. Решетнева, Россия, Красноярск
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