one Power transistor GTR
1. The difference between transistor and triode
I. Triode and transistor have: cutoff zone, amplification zone, saturation zone;
II. Triode working in amplification area;
III. Transistors in the switching process, mainly work in the saturated region and cut-off region;
2. Dynamic characteristics of transistors
I. GTR uses base current to control collector current;
II. GTR has time delay when it is on and off, which is mainly the emitter junction barrier capacitance and collector junction barrier capacitance
Produced by charging and discharging;
III. Increasing the base current can shorten the delay time;
two Power field effect transistor MOSFET
1. Working principle of power MOSFET
Power MOSFET is a voltage-controlled current type (control drain current by adding positive voltage between the control gate source)
I. Cut-off: positive power supply is added between drain and source poles (drain is connected to the positive power supply pole, source is connected to the negative power supply pole), and the voltage between gate and source poles is zero
The PN junction J1 formed between the P-base region and the N drift region is counter-biased, and no current flows between the drain and source.
II. Conduction: positive power supply is added between drain and source poles (drain is connected to the positive power supply pole, source is connected to the negative power supply pole), and positive voltage Ugs is added between gate and source poles
- When Ugs is greater than Ut, p-type semiconductor inverts into n-type and forms an invert layer, which forms an N-channel and eliminates PN junction J1
Loss, drain and source conduction;
2. Transfer characteristics of power MOSFET
The relation between drain current Id and gate source voltage Ugs becomes the transfer characteristic of MOS
3. Output characteristics of power MOSFET
I. Working in the switching state, i.e. switching between cut-off zone and unsaturated zone;
II. There are parasitic diodes between drain and source, and when drain and source add reverse voltage, MOS is on;
III. MOSFET switching speed is very fast, frequency up to 100kHz, is the highest power electronic devices;
IV. MOSFET is a field-controlled device that requires little input current at a static state. But in the switching process need to be on capacitance
Charge and discharge, need a certain drive.
3. Insulated gate bipolar transistor IGBT
1. Working principle of insulated gate bipolar transistor
I. GTO and GTR are bipolar current driving devices with conductive modulation effect, so they have strong conductivity (opening voltage is reduced),
Low switching speed (due to the memory effect of fewer particles);
II. MOSFET is a monopole type voltage driver, high switching speed, high input impedance;
III. IGBT open: When the voltage Uge between the gate and the emitter is greater than the open voltage Uge(TH), groove is formed in the MOSFET
Channel, and provide base current Id for the transistor to promote IGBT conduction;
Iv. IGBT off: When reverse voltage is applied or no voltage is applied between the gate and emitter, the channel in the MOSFET disappears and the crystal
The base current of the body tube is cut off and IGBT is turned off.
2. Summary of IGBT characteristics
I. IGBT switching speed, switching loss is small;
II. IGBT has a large security working area;
III. The on-state pressure drop of IGBT is lower than MOSFET;