Comparative efficiency analysis for silicon, silicon carbide MOSFETs and IGBT device for DC–DC boost converter
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In present study, a comparative efficiency analysis for silicon (Si), silicon carbide (SiC) metal oxide semiconductor field effect transistors (MOSFETs) and insulated gate bipolar transistor (IGBT) device based DC–DC boost converter is performed. Due to different gate-drive characteristics of power semiconductor devices such as Si, SiC MOSFETs and IGBT device, different voltage levels are required to drive aforementioned devices. A 500 W boost converter for wide input voltage range (30–72 V) and 110 V output voltage is designed having a single gate driver circuit for Si, SiC MOSFETs and IGBT. A single gate driver provides the gate-source (or base-emitter in case of IGBT) signal for all the devices which eliminates the use of separate gate driver circuit. Si MOSFET and IGBT are driven by 12 V gate-source voltage whereas SiC MOSFET is operated by 18 V gate-source voltage using the gate driver circuit. An experimental study is performed for the comparative efficiency analysis for Si, SiC MOSFETs and IGBT device based converter for 20 and 50 kHz switching frequencies. It is found that SiC based converter provides highest efficiency ≈ 97.8%, whereas the lowest efficiency ≈ 94% is found for IGBT based converter at 20 kHz switching frequency. SiC based converter gives higher efficiency because lower conduction loss owning to lower on-state resistance as compared to Si MOSFET. Besides this, SiC application has another advantage such as low switching loss at higher frequency resulting compact size of converter. However, use of IGBT at higher switching frequency results in higher switching losses, hence lower efficiency of the converter.
KeywordsDC–DC boost converter Efficiency comparison IGBT Silicon (Si) Silicon carbide (SiC)
List of symbols
IGBT on state energy loss (J)
IGBT off state energy loss (J)
MOSFET on state energy loss (J)
MOSFET off state energy loss (J)
Effective series resistance (Ω)
Switching frequency (kHz)
Collector current (A)
Average collector current (A)
Collector rms current (A)
Drain current (A)
Drain rms current (A)
Inductor rms current (A)
Output current (A)
Diode conduction loss (W)
MOSFET conduction loss (W)
IGBT conduction loss (W)
IGBT switching loss (W)
MOSFET switching loss (W)
Schottky diode junction charge (C)
Collector resistance (Ω)
Inductor DC resistance (Ω)
Drain to source on resistance (Ω)
Switching period (s)
Instantaneous collector to emitter voltage (V)
Collector to emitter voltage (V)
Instantaneous drain to source voltage (V)
Drain to source voltage in off condition (V)
Diode on state voltage drop (V)
Output DC voltage (V)
Electrical and thermal properties for Si, SiC MOSFET
Band gap (eV)
Breakdown electric field (MV/cm)
Thermal conductivity(W/cm K)
Electron mobility (cm2/V s)
Hole mobility (cm2/V s)
Intrinsic carrier concentration (per cm3) at 300 K
1.5 × 1010
5 × 10–9
Electron saturation velocity (× 107 cm/s)
Relative dielectric constant
Several studies have been carried out for efficiency comparison of Si and SiC MOSFETs based DC–DC converter. Masich et al. have performed the efficiency comparison between the Si and SiC MOSFETs based DC–DC boost converter. A high voltage gain boost converter was designed for low power application (≈ 20 W) which is suitable for light emitting diode (LED). DC–DC converter efficiency was improved from 76 to 89% and 68 to 81% with variation in the switching frequency from the 120 kHz to 20 kHz at 600 V and 900 V output voltage, respectively . Han et al. have performed the comparative study on the efficiency, weight and volume of SiC and Si based bidirectional DC–DC converter for the hybrid electrical vehicle. They studied the three configurations such as IGBT device with silicon diode, IGBT with SiC Schottky diode and SiC MOSFET with SiC Schottky diode. A comparative efficiency analysis was carried out at 20 kHz switching frequency. The highest efficiency ≈ 99% was achieved with the use of SiC MOSFET with SiC Schottky diode at full load condition, whereas the efficiency for IGBT with SiC Schottky diode was 98.2%. The efficiency for the IGBT and silicon PN diode configuration was found to be 97.6%. There was significant reduction in weight of the converter from 8 to 3 kg with switching frequency of 20 kHz to 200 kHz, respectively. It was also observed that only the SiC based converter have efficiency higher than 90% at 200 kHz switching frequency . Shi et al. have studied the SiC based on-board plug-in-electric vehicle (PEV) charger using single-ended primary-inductor converter (SEPIC) based power factor correction (PFC) converter followed by an isolated LLC resonant converter. It was found that the SEPIC-PFC converter achieved unity power factor, 2.72% total harmonic distortion, and 95.3% peak efficiency. The LLC converter achieved 97.1% peak efficiency. The overall efficiency of the PEV charger increased from 88.5 to 93.5% with increase in the load from 20% to full load . Schrittwieser et al.  have done study on a three-phase buck PFC rectifier with integrated active filter for 380 V DC distribution systems that showed a peak efficiency ≈ 99% is achieved with SiC devices. Zhao et al. have performed comparative theoretical and experimental analysis for the isolated bidirectional DC–DC converter using Si and SiC devices. The SiC devices based converter showed the higher efficiency as compared to the Si based converter . Rizzoli et al. have carried out a study on the performance evaluation of an inverter based on the soft and hard-switching SiC devices. It was found that hard-switching SiC inverter showed higher efficiency at lower output and also it was more economical as it eliminated the complex circuitry to drive the SiC MOSFET . Anthon et al. have demonstrated the use of the SiC devices in multilevel grid-tied inverter. The use of the SiC devices reduced the semiconductor losses by more than 50% for similar rated capacity, load and frequency as compared to Si-IGBT device. In the application of the SiC device based inverter, the switching frequency was increased by 12 times while semiconductor losses were similar as in case of Si-IGBT inverter . Ho et al. have done the performance comparison of interleaved boost converter based on the of Si and SiC diodes for photovoltaic applications. The use of SiC diode reduced the heat sink size (from 1031 to 388 cm3) and increased the converter efficiency by 0.6% . In another study, Wang et al. have demonstrated the efficiency improvement in the 10 kW bidirectional electric vehicle charger using the variable DC bus voltage. It was found that efficiency increased by 0.7–1.25% using the variable DC bus voltage as compared to constant 600 V DC bus voltage . Similar types of study for efficiency comparison of Si and SiC devices for DC–DC interleaved, bidirectional converter and inverter have been done [21, 22, 23, 24, 25, 26, 27, 28, 29]. The thermal performance of the converter using Si and SiC MOSFETs has been studied in order to estimate the junction temperature, heat losses and temperature distribution [21, 30, 31, 32].
In present study, a comparative analysis of efficiency and losses for DC–DC converter is performed for different devices applications such as Si, SiC and IGBT. A 500 W power and 110 V output voltage DC–DC converter which have single gate driver circuit for all devices was developed in the laboratory. A theoretical prediction methodology is given which provides a details insight of conduction, switching losses for different devices along with inductor and capacitor losses. Three cases are studied to estimate the losses in the converter using theoretical prediction and experimental analysis such as (1) Si MOSFET + SiC diode, (2) SiC MOSFET + SiC diode, and (3) IGBT device + SiC diode.
Out of the three conventional DC/DC converter topologies i.e. buck, boost and buck-boost, boost topology is selected for the efficiency comparison. The reasons for choosing this topology are: (a) The input current of the boost converter is continuous which make it suitable to use with renewable power generators , (b) The gate driver circuit is not complex as it uses the low side driving circuitry. A single driver circuit is suitable to drive all types of power semiconductor devices namely Si, SiC MOSFET and IGBT, (c) With change in the duty cycle there is approximately no change in the efficiency whereas for other topologies the efficiency changes significantly. This characteristics is utilized for further enhancement in the efficiency .
2 Material and methodology
2.1 Gate driver circuit
2.2 Converter losses theoretical calculation
There are several losses occur in DC–DC boost converter such as MOSFET switching and conduction losses, diode conduction losses, inductor and capacitor losses. All of these losses can be calculated theoretically. The methodology used in calculation of different losses are given as following.
2.2.1 MOSFET losses
The losses in the MOSFET can be calculated as follows:
18.104.22.168 Conduction loss
22.214.171.124 Switching loss
Switching loss of MOSFET majorly depends on the ON and OFF states energy losses of MOSFET. The MOSFET switching loss is calculated with considering the loss associated with ON and OFF states of the MOSFET. The ON-state energy loss is calculated without considering the loss associated with reverse recovery process of MOSFET. However, loss associated with the reverse recovery process with anti-parallel diode is considered for calculating the ON-state loss.
2.2.2 IGBT losses
The IGBT conduction and switching losses are calculated in similar way as the conduction and switching losses are calculated for the MOSFET. The drain, source and gate for MOSFET are similar to the collector, emitter and base of IGBT, respectively. The conduction loss in IGBT is given by:
126.96.36.199 IGBT conduction loss
188.8.131.52 IGBT switching loss
The values of parameters used in theoretical calculation of conduction and switching losses are taken from the IGBT datasheet .
2.2.3 Diode losses
The boost converter diode also has two types of losses such as conduction and switching losses. These losses can be explained as below:
184.108.40.206 Diode conduction loss
220.127.116.11 Diode switching loss
The values of parameters used in theoretical calculation of conduction and switching losses are taken from the Schottky diode datasheet .
2.2.4 Inductor and capacitor losses
2.3 Experimental setup
Details of devices used in experimental study
Reverse voltage rating (V)
Forward current rating @ 25 °C (A)
Drain-to-source on resistance (mΩ)
3 Results and discussion
3.1 Theoretical prediction of losses in DC–DC converter
Conduction loss majorly depends on the load current, junction temperature, duty cycle while switching loss is function of switching speed, load voltage, load current and junction temperature. The conduction loss in the SiC is less than its counterparts because the on-state resistance is low. The resistance of SiC device is dependent on the applied voltage, its off-state resistance is high. SiC on-state resistance decreases significantly until a threshold voltage is applied to it and maintains this resistance until applied voltage is below threshold voltage. The on-state resistance is majorly depends on the thickness of drift layer. In SiC, the thickness of drift layer is reduced 10 times as compared to Si while the concentration of doping is kept in magnitude of same order in case of Si. Therefore, the SiC offers almost 10 times lesser on-state resistance as compared to Si. In contrast of SiC, Si MOSFET on-state resistance increases with increase in the gate-source voltage. The increment in the on-state resistance of Si MOSFET is proportional to square of voltage to gate to source voltage. The switching losses in IGBT are higher than the SiC MOSFET, because due to inherent bipolar characteristic of IGBT. Being as bipolar device the conduction in the IGBT happens due to both electrons and holes. Therefore, during the transition from on-state to off-state, there are some electrons and holes are trapped in the channel. Therefore, IGBT will not be fully turned off until all electrons and holes are recombined. During this transition time, miller capacitance holds some gate voltage, therefore some losses happens during this period. SiC device has unipolar conduction which happens due to electrons flow only. During the transition from the on state to off state, only electrons flow is inhibited by closing the channel. Therefore, there is no delay in the turning off completely in the SiC MOSFET.
3.2 Experimental efficiency analysis of the converter
This section explains the experimental analysis of efficiency in the DC–DC converter.
The converter efficiency increases with increase in the load power (as power output increases while switching loss does not vary much). Nonetheless, efficiency further decreases with increase in the output power (further increase in the load power, conduction loss dominates more). Therefore, efficiency comes lower for further increase in the load power.
3.3 Comparison between experimental and theoretical predicted efficiencies
Measured and calculated efficiency differences for 250 W load at 20 kHz
Calculated efficiency (%)
Measured efficiency (%)
Measured and calculated efficiency difference for 250 W load at 50 kHz
Calculated efficiency (%)
Measured efficiency (%)
Measured and calculated efficiency difference for 500 W rating at 20 kHz
Calculated efficiency (%)
Measured efficiency (%)
Measured and calculated efficiency difference for 500 W rating at 50 kHz
Calculated efficiency (%)
Measured efficiency (%)
The theoretical prediction is also given for the conduction and switching losses in power transistor devices and inductor and capacitor losses. Tables 3 and 4 give the difference in the measured and theoretical efficiencies for 250 W power at 20 kHz and 50 kHz switching frequency, respectively. Tables 5 and 6 provide the difference in theoretical and measured values of efficiency for 500 W at 20 kHz and 50 kHz switching frequency, respectively. There is slight difference between the theoretical and experimentally measured values. There is reason which can causes the difference between the theoretical and measured values such as (1) Leakage losses in the parasitic resistance, capacitance and inductor in the converter circuit layout which are not considered in the theoretical prediction, (2) Parameter values for different devices Si, SiC and IGBT in theoretical prediction are taken from the respective datasheet provided by the manufacturer which were obtained at the standard test condition and may be different in actual working condition, (3) Variable nature of switching frequency which is sensitive to unincorporated parasitic elements in the theoretical prediction.
In this study, the comparison in the efficiency of the DC–DC boost converter using the Si and SiC MOSFETs and IGBT device has been studied on the basis of theoretical predictions and experimental analysis. Three cases such as (1) Si MOSFET + SiC diode, (2) SiC MOSFET + SiC diode, and (3) Si IGBT + SiC diode are compared to evaluate the comparative efficiency and losses for given power output at different operating frequency such as 20 kHz and 50 kHz. It was found that at lower frequency (20 kHz), the efficiency of DC–DC converter is maximum 97.8% and followed by Si and IGBT. However, the converter efficiency drops for all three aforementioned cases with increase in the switching frequency. The SiC MOSFET + SiC diode based converter gives maximum efficiency because of low conduction and switching losses. Conduction loss in SiC is lowest due to lower on-state resistance as compared to Si MOSFET and IGBT. Switching loss is also lowest in case of SiC MOSFET + SiC diode application due to the low miller capacitance (parasitic capacitance). The details comparative analysis of conduction, switching loss, inductor loss and capacitor loss are also given for Si, SiC and IGBT devices in the converter. Conduction loss is maximum for IGBT followed by the Si and SiC. It is concluded that the application of the combination of power semiconductor devices (SiC MOSFET + SiC Schottky diode) in DC–DC converter provides the highest efficiency as compared to Si and IGBT devices.
Compliance with ethical standards
Conflict of interest
On behalf of all authors, the corresponding author states that there is no conflict of interest.
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