IGBT FF1200R12IE5P: Loss calculation in an SPWM voltage source converter topology

[Infineon_Team]

Calculate loss in an SPWM voltage source converter topology 

Note:  In conjunction with this article, you should refer to the following articles:

1. "IGBTs: Loss calculation and junction temperature estimation for an SPWM voltage source converter": Describes the Insulated Gate Bipolar Transistors (IGBTs) loss calculation and junction temperature estimation for an SPWM voltage source converter.
2. Calculate IGBT losses for a SPWM voltage source converter: Describes a simplified method to calculate IGBTs losses for an SPWM voltage source converter.

In this article, IGBT FF1200R12IE5P is considered for loss calculation; the worst-case loss calculation is done at full load and 125°C junction temperature.

Sine-triangle pulse width modulation (SPWM)

"One of the widely used inverter control methods covered in power electronics is the sine-triangle pulse width modulation (SPWM) control. With the SPWM control method, the switches of the inverter are controlled based on a comparison of sinusoidal control reference signals and a triangular carrier wave. The sinusoidal control waveform establishes the fundamental frequency of the inverter output, while the triangular waveform presents the switching frequency of the inverter. The ratio between the frequencies of the sinusoidal reference wave and the triangular wave is referred to as the modulation frequency ratio" (Chalmers University of Technology Gothenburg, 2015)

A 500 kVA SPWM voltage source inverter is considered with the design parameters shown in Table 1.

                                                                                               Table 1:   Inverter parameters

Parameter	Value
Inverter output (kVA)	500
DC link voltage (Vdc)	700 V
Output inverter voltage Vrms, out (L-L)	415 V
Switching frequency (Fsw)	1350 Hz
Dead time (td)	2 µs
Power factor (Փ)	0.8

Full load RMS line current is:

The maximum possible modulation index (m) is:

To calculate the conduction loss and switching loss, the average and RMS current of the IGBT and diode should be derived first.

From Equation 8 in Calculate IGBT losses for a SPWM voltage source converter , the IGBT average current is:

From Equation 9 in Calculate IGBT losses for a SPWM voltage source converter , the IGBT RMS current is:

Similarly, from Equation 11 in Calculate IGBT losses for a SPWM voltage source converter , the diode average current is:

From Equation 12 in Calculate IGBT losses for a SPWM voltage source converter , the diode RMS current is:

Figure 1:    IGBT output characteristics

Figure 2:   IGBT switching energy loss

IGBT at 125°C, Rg,on = Rg,off = 0.82 Ω, FF1200R12IE5P (Figure 1 and Figure 2).

                                                                                                          Table 2: IGBT parameters

Parameter	Value
VCEO	0.78 V
RT	1.09 mΩ
Eon	31 mJ
Eoff	35.6 mJ

On-state resistance R_T and threshold voltage V_CE0 are determined around the RMS current value from the IGBT output characteristics as shown in Figure 1.

Turn-on energy loss (E_On) and turn-off energy loss (E_Off) are deduced at the average current from the IGBT switching loss energy curve as shown in Figure 2.

Similarly, R_D and V_D0 are determined around the diode RMS current and recovery energy (E_rec) at the diode average current as shown in Figure 3 and Figure 4 respectively.

Figure 3:  Diode output characteristics

Figure 4:  Diode reverse recovery energy

Diode at 125°C, Rg = 0.82 Ω (Figure 3 and Figure 4).

                                                                                             Table 3:  Diode parameters

Parameter	Value
RD	1.17 mΩ
VD0	0.70 V
Erec	16.2 mJ

From Equation 7 in Calculate IGBT losses for a SPWM voltage source converter , the IGBT conduction loss is:

From Equation 16 in Calculate IGBT losses for a SPWM voltage source converter , the IGBT switching loss is:

Similarly, for diode:

From Equation 10 in Calculate IGBT losses for a SPWM voltage source converter , the diode conduction loss is:

From Equation 17 in Calculate IGBT losses for a SPWM voltage source converter , the diode reverse recovery loss is:

Table 4:  Per switch calculated loss for SPWM VSI

IGBT		Diode
I_igbt,avg	228.20 A	I_diode,avg	74.93 A
I_igbt,rms	434.95 A	I_diode,rms	229.67 A
IGBT cond loss	392.01 W	Diode cond loss	114.17 W
IGBT SW loss	104.90 W	Diode SW loss	25.52 W
IGBT total loss	496.90 W	Diode total loss	139.68 W

IGBT’s turn-on, turn-off losses, conduction loss, anti-parallel diode reverse recovery energy, and conduction loss can be calculated as shown in Table 4. Apart from that, there are other losses i.e., IGBT snubber circuit loss, gate driver loss, etc.

The conduction loss is independent of the converter operating frequency. However, switching losses are linearly dependent on the frequency.

                                                                            Table 5:   Switching loss versus frequency

SW frequency	1350 Hz	1950 Hz	2550 Hz
IGBT switching loss	105 W	151 W	198 W
Diode switching loss	26 W	37 W	48 W

Use lower to medium switching frequency in high-power applications. It could remarkably save a great deal of energy in high-power applications. In addition, with low di/dt and dV/dt, IGBTs can easily be connected in series or parallel for increased power capacity. Low di/dt and dV/dt will also lead to a simple inductive circuit design. Although the THD will be on the higher side, that can be mitigated by using a high-capacity filter.

Total loss for one single-phase module is:

Total three-phase inverter loss is:

Rise in junction temperature is:

Note:  The exact losses will always vary based on the variation in system parameters.

Community Translation: IGBT: Infineon IGBT FF1200R12IE5P に基づく SPWM 電圧源コンバータ トポロジでの損失計算 – KBA236569

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