# High-power diode thyristor knowledge serialization-loss

Power diode thyristors are widely used in AC/DC converters, UPS, AC static switches, SVC and electrolytic hydrogen, etc. However, most engineers do not understand such bipolar devices as well as IGBTs. For this reason, we organized 6 Article serial, including forward characteristics, dynamic characteristics, control characteristics, protection, loss and thermal characteristics. Power diode thyristors are widely used in AC/DC converters, UPS, AC static switches, SVC and electrolytic hydrogen, etc. However, most engineers do not understand such bipolar devices as well as IGBTs. For this reason, we organized 6 Article serial, including forward characteristics, dynamic characteristics, control characteristics, protection, loss and thermal characteristics. The content is extracted from Infineon’s “Bipolar semiconductor Technology Information”.

3.5 Power dissipation (loss)

For thyristors and diodes, dissipation (or loss) is divided into off-state, ON-state, turn-on and turn-off losses. Thyristors also have control losses. Under specified cooling conditions, the sum of these losses determines the current-carrying capacity of the device.

When working at grid frequencies up to 60 Hz and with moderate dynamic requirements, only the on-state losses can be considered because the sum of other losses is relatively negligible.

For semiconductors with high blocking voltage (>2200V) or die Ф≥80mm, even if they work at the grid frequency, the turn-off loss should be considered in the calculation.

3.5.1 Total power dissipation Ptot

Ptot is the average value of the sum of various losses.

3.5.2 Off-state loss PD, PR

PD and PR are the losses caused by the off-state current and off-state voltage in the forward (PD) off-state and reverse (PR) off-state.

3.5.3 On-state loss PT, PF

PT and PF are electric energy converted into heat when only the forward conduction state is considered. According to the following formula, use the value of the equivalent straight line to calculate the average value of the on-state loss PTAV or PFAV:

PTAV=VT(TO)•ITAV+rT•I²TRMS=VT(TO)•ITAV+rT• I²TAV•F² (thyristor)

PFAV=VF(TO)•IFAV+rT•I²FRMS=VF(TO)•IFAV+rT• I²FAV•F² (diode)

For the form factor F, see Table 1

The graph in the data sheet shows the relationship between the average on-state dissipation power of various shapes of current and the on-state current.

The on-state Voltage can be calculated by a more accurate approximation through the following relationship, instead of using vT0, vF0 and rT to calculate the on-state loss. The coefficients A, B, C, and D are listed in the data sheet.

Exception: ABCD coefficients are not listed for PowerBLOCK module type. Table 1. Form factor corresponding to phase angle control

3.5.4 Switching loss PTT, PFT+PRQ

PTT, PFT+PRQ are part of the electrical energy that is converted into heat during turn-on (PTT corresponds to thyristor, PFT corresponds to diode) and turn-off (PRQ). The average switching loss increases with the rise and fall rates of the on-state current during turn-on and turn-off, and the increase in repetition frequency. For medium-sized thyristors and diodes with blocking voltage ≤ 2200V and applications up to 60Hz grid frequency, the switching loss is almost negligible compared to the on-state loss.

For semiconductors with blocking voltage >2200V or semiconductors with a die Ф≥80mm, even if it is working at the grid frequency, the turn-off loss should be considered in the calculation (if necessary, it can be provided on request).

But the turn-off loss of the diode is usually still negligible.

3.5.4.1 Turn-on loss PTT, PFT

PTT and PFT are the power dissipation that exceeds the on-state loss PT (thyristor) or PF (diode) during the turn-on period. It is caused by the carrier storage effect and the delayed transmission of the current-carrying area. In order to turn on the entire thyristor chip as quickly as possible, many thyristors have a trigger amplification function. This function contains one or several amplified gates (= auxiliary thyristors). For thyristors with large cross-sections, the magnification gate has a branched structure (finger structure). This structure enables a larger cross-section to be turned on when triggered, thereby reducing turn-on loss. The sum of turn-on and on-state losses, PTT, PFT+PT, PF, is very important for power consumption calculations. It can be obtained by integrating on-state current and on-state voltage during and after turn-on. In fact, the turn-on loss is usually negligible.

3.5.4.2 Turn-off loss PRQ

The turn-off loss is caused by the carrier storage effect. It depends on the reverse delay current, reverse off-state voltage amplitude and rate of rise, so it may be affected by the snubber circuit (see Figure 23). The time tint is used to integrate the turn-off loss.

The approximate calculation method of turn-off loss is as follows: Erq= Turn-off loss energy

f=frequency

Qr= Maximum recovery charge

VR= (Reverse voltage) excitation voltage after commutation

3.5.5 Gate power consumption PG

PGIt is electrical energy converted into heat due to the gate current flowing between the gate and the cathode. It is divided into gate peak power consumption PGM(The product of the gate current and the peak value of the gate voltage) and the average gate power consumption PGAV(Periodic average value of gate power consumption) Power diode thyristors are widely used in AC/DC converters, UPS, AC static switches, SVC and electrolytic hydrogen, etc. However, most engineers do not understand such bipolar devices as well as IGBTs. For this reason, we organized 6 Article serial, including forward characteristics, dynamic characteristics, control characteristics, protection, loss and thermal characteristics. The content is extracted from Infineon’s “Bipolar Semiconductor Technology Information”.

3.5 Power dissipation (loss)

For thyristors and diodes, dissipation (or loss) is divided into off-state, on-state, turn-on and turn-off losses. Thyristors also have control losses. Under specified cooling conditions, the sum of these losses determines the current-carrying capacity of the device.

When working at grid frequencies up to 60 Hz and with moderate dynamic requirements, only the on-state losses can be considered because the sum of other losses is relatively negligible.

For semiconductors with high blocking voltage (>2200V) or die Ф≥80mm, even if they work at the grid frequency, the turn-off loss should be considered in the calculation.

3.5.1 Total power dissipation Ptot

Ptot is the average value of the sum of various losses.

3.5.2 Off-state loss PD, PR

PD and PR are the losses caused by the off-state current and off-state voltage in the forward (PD) off-state and reverse (PR) off-state.

3.5.3 On-state loss PT, PF

PT and PF are electric energy converted into heat when only the forward conduction state is considered. According to the following formula, use the value of the equivalent straight line to calculate the average value of the on-state loss PTAV or PFAV:

PTAV=VT(TO)•ITAV+rT•I²TRMS=VT(TO)•ITAV+rT• I²TAV•F² (thyristor)

PFAV=VF(TO)•IFAV+rT•I²FRMS=VF(TO)•IFAV+rT• I²FAV•F² (diode)

For the form factor F, see Table 1

The graph in the data sheet shows the relationship between the average on-state dissipation power of various shapes of current and the on-state current.

The on-state voltage can be calculated by a more accurate approximation through the following relationship, instead of using vT0, vF0 and rT to calculate the on-state loss. The coefficients A, B, C, and D are listed in the data sheet.

Exception: ABCD coefficients are not listed for PowerBLOCK module type. Table 1. Form factor corresponding to phase angle control

3.5.4 Switching loss PTT, PFT+PRQ

PTT, PFT+PRQ are part of the electrical energy that is converted into heat during turn-on (PTT corresponds to thyristor, PFT corresponds to diode) and turn-off (PRQ). The average switching loss increases with the rise and fall rates of the on-state current during turn-on and turn-off, and the increase in repetition frequency. For medium-sized thyristors and diodes with blocking voltage ≤ 2200V and applications up to 60Hz grid frequency, the switching loss is almost negligible compared to the on-state loss.

For semiconductors with blocking voltage >2200V or semiconductors with a die Ф≥80mm, even if it is working at the grid frequency, the turn-off loss should be considered in the calculation (if necessary, it can be provided on request).

However, the turn-off loss of the diode is usually still negligible.

3.5.4.1 Turn-on loss PTT, PFT

PTT and PFT are the power dissipation that exceeds the on-state loss PT (thyristor) or PF (diode) during the turn-on period. It is caused by the carrier storage effect and the delayed transmission of the current-carrying area. In order to turn on the entire thyristor chip as quickly as possible, many thyristors have a trigger amplification function. This function contains one or several amplified gates (= auxiliary thyristors). For thyristors with large cross-sections, the magnification gate has a branched structure (finger structure). This structure enables a larger cross-section to be turned on when triggered, thereby reducing turn-on loss. The sum of turn-on and on-state losses, PTT, PFT+PT, PF, is very important for power consumption calculations. It can be obtained by integrating on-state current and on-state voltage during and after turn-on. In fact, the turn-on loss is usually negligible.

3.5.4.2 Turn-off loss PRQ

The turn-off loss is caused by the carrier storage effect. It depends on the reverse delay current, reverse off-state voltage amplitude and rate of rise, so it may be affected by the snubber circuit (see Figure 23). The time tint is used to integrate the turn-off loss.

The approximate calculation method of turn-off loss is as follows: Erq= Turn-off loss energy

f=frequency

Qr= Maximum recovery charge

VR= (Reverse voltage) excitation voltage after commutation

3.5.5 Gate power consumption PG

PGIt is electrical energy converted into heat due to the gate current flowing between the gate and the cathode. It is divided into gate peak power consumption PGM(The product of the gate current and the peak value of the gate voltage) and the average gate power consumption PGAV(Periodic average value of gate power consumption)

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