Expert Talk: What is the difference between a MOSFET and an IGBT?

Open online SPICE simulator circuit link: power_learn_220V_mosfet_igbt_difference.TSC

Expert Talk: What is the difference between a MOSFET and an IGBT?

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MOSFET Circuit

In this expert talk you will learn about the difference between MOSFETs and IGBTs. Both are used as "solid state switches"
in combination with passive components for controlling the energy transfer from a source (battery or grid) to a energy sink (e.g., motor).
- MOSFET stands for: Metal Oxide Semiconductor Field-Effect Transistor
- IGBT stands for: Insulated Gate Bipolar Transistor

1) Switching Control
Not much difference here: both devices are controlled by applying a voltage to the Gate pin
- Zero or negative voltage at Gate pin: Switch is OFF (no current flows)
- Positive Gate voltage: Switch turns ON (current flows)

2) Switch is OFF: Voltage Class says how much stress switch can take
Big difference here:
- IGBT can stay much higher voltage until the switch breaks through (up to a few 1000 V)
- MOSFETs usually can stand voltages below 1000 V

3) Switch is ON: Current flows through the switch
Big difference here: IGBT can carry more current than MOSFETs
- MOSFET use either electrons (n) or holes (p) carriers for the current flow
- IGBTs use both carriers in parallel: n and p. There for the term "bipolar"

4) Frequency of Switching
Big difference here: MOSFET can switch faster since they use only n or p carriers
- MOSFET can switch up 1000 kHz or higher
- IGBT can switch up to 100 kHz

5) Losses (Energy Efficiency)
Two main contributors make up the overall losses:
- Conduction Loss (Switch is ON): MOSFET loss scales square like with current while IGBT does so linearly
P_loss_c_mosfet = \e(I,2) * \i(R,ds_on) P_loss_c_igbt = I * \i(V,ce_on)
- Switching Loss (OFF->ON->OFF): MOSFET is far better than IGBTs at a given frequency

Conclusion:
- Use MOSFET: high switching frequency applications and highest efficiency with small size (e.g., Switched mode Power Supply)
- Use IGBT: low switching frequency but high current and voltage applications (e.g., Industrial Motor Control & Drives)

IGBT Circuit

{1. click here to set application parameters}
{2. click on Run to calculate components}
{3. click Simulate Transient }

fs:= 20k {switching frequency}
T:=1/fs
T=[50u]
Duty:=0.2 {duty cycle}

T_ON:= Duty*T {on time}
T_ON=[10u]
T_OFF:=T-T_ON
T_OFF=[40u]
{==============================}
SwitchingControlT2:=T_ON
SwitchingControlT6:=T_OFF