SCM1261MF datasheet(32/60 Pages) SANKEN

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SCM1200MF Series

SCM1200MF-DSJ Rev.1.1

SANKEN ELECTRIC CO.,LTD.

Feb. 19, 2016

http://www.sanken-ele.co.jp/en

phase, and Figure 13-4 shows the low-side transistor

(Q1L) in U phase. And all the pins that are not

represented in these figures are open.

Before conducting a measurement, be sure to isolate

the ground of a measurement phase from those of other

two phases. Then, in each of the two separated phases,

connect the LSx and COMx pins each other at the same

potential, and leave them unused and floated.

MIC1

COM1

VBB

LS3

LS2

LS1

COM2

COM3

MIC2

MIC3

Q1H

Q1L

Q2H

Q2L

Q3H

Q3L

Figure 13-3.

Typical measurement circuit of high-side

transistor (Q1H) in U phase

MIC1

COM1

VBB

LS3

LS2

LS1

COM2

COM3

MIC2

MIC3

Q1H

Q1L

Q2H

Q2L

Q3H

Q3L

Figure 13-4.

Typical measurement circuit of low-side

transistor (Q1L) in U phase

14. Calculating

Power

Losses

and

Estimating Junction Temperatures

This section describes the procedures to: calculate

power losses in a switching transistor; and estimate

junction

temperatures.

Note

that

the

following

descriptions are applicable to the SCM1200MF series,

which is controlled by a three-phase sine-wave PWM

driving strategy.

The total power losses in an IGBT can be obtained by

taking the sum of steady-state loss, PON, and switching

loss, PSW.

The following subsections contain the mathematical

procedures to calculate power losses in an IGBT and its

junction temperature.

14.1. IGBT Steady-State Loss, PON

The steady-state loss in an IGBT can be computed by

using the VCE(SAT) vs. IC curves, shown in Section 15.3.1.

As shown

in Figure

14-1,

the

following linear

approximate equation can be obtained from the curves:

VCE(SAT) = α × IC + β. The slope and intercept of the

linear approximate equation are used in Formula (4).

Table 14-1 lists the reference slopes and intercepts of

the linear approximate equation at a half of output

current, 0 to 0.5 × IO.

The values calculated with the linear approximation

greatly differ at the point where IC is near zero. But in

dissipation calculation, the difference is regarded as an

error tolerance. Hence, the equation for the steady-state

loss, PON, is:

(4)

Where:

VCE(SAT) is the collector-to-emitter saturation

voltage of the IGBT in V,

IC is the collector current of the IGBT in A, and

DT is the on-time duty cycle.

M is the modulation index (0 to 1),

cosθ is the motor power factor (0 to 1),

IM is the effective motor current in A,

α is the slope of the linear approximate equation in the

VCE(SAT) vs. IC curve, and

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