2.8
2.6
2.4
2.2
2.0
1.8
1.6
1.4
1.2
1.0
TJ = 150°C
VCE
(V)
TJ =25°C
10
20
30
40
50
60
70
80
IC (A)
FIGURE 4 - IGBT COLLECTOR-TO-EMITTER VOLTAGE VS. COLLECTOR CURRENT
Based upon this voltage drop and the conduction duty cycle a conduction power loss may be calculated
as:
Pc = δS ⋅ δPWM ⋅ VCE ⋅ IC
where:
pc =
Conduction IGBT Power Dissipation
δs =
Switch Duty Cycle, (.33 for brushless drives in run condition, 1 in stall)
PWM on/off ratio
δPWM
=
VCE
IC =
=
Collector Emitter voltage from Figure 4 for a particular collector current
Collector current
Switching losses are dependent upon the operating frequency, collector current and again duty cycle as:
IC
Ps = δS ⋅ [Eon + Eoff] ⋅ fo ⋅ -----
40
where:
Ps =
Eon
Eoff
Switching IGBT Power Dissipation
Turn on energy loss from Table 2
Turn off energy loss from Table 2
Pulse width modulation frequency
Collector current
=
=
fo =
IC =
Commutation diode losses are calculated as:
Pd = δs ⋅ [1 – δPWM] ⋅ Vf ⋅ If
7
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