US 12,580,497 B2 · Prediction method for crosstalk spike in half-bridge of current source type inverter with silicon carbide devices

Abstract

A prediction method for a crosstalk voltage spike in a half bridge of current-source inverter with silicon carbide devices includes calculation of the crosstalk voltage spike in the circuit of current-source type double-pulse test and analysis of the effect of each parameter on the magnitude of the crosstalk voltage spike. The prediction method analyzes the horizontal conduction crosstalk mechanism between the gate-source junction of the MOSFET caused by the high-frequency switching action of the silicon carbide (SiC) MOSFET and the SiC Schottky diode connected in series, and derives the prediction model. Based on the equivalent circuit of the current-source-type double-pulse test and the crosstalk-induced mechanism, the extreme value of crosstalk voltage spike is accurately predicted, which is helpful to analyze the effects of the drive circuit and the parameters of the power circuit on the crosstalk voltage spike through the prediction model.

A prediction method for a crosstalk voltage spike in a half-bridge of a current-source inverter with silicon carbide devices, comprising:

calculating the crosstalk voltage spike in a circuit of current-source type double-pulse test and analyzing an effect of influencing factors on a magnitude of the crosstalk voltage spike;
in the circuit of the current-source type double-pulse test, connecting first and second reverse-voltage-blocking synthesis devices, the first consisting of a metal-oxide-semiconductor field-effect transistor (MOSFET) S1 and a Schottky diode D1 connected in series, and the second consisting of a MOSFET S3 and a Schottky diode D3 connected in series, to both ends of a capacitor, wherein the capacitor is equivalent to a filter capacitor on an AC side of a three-phase current-source inverter, forming an arm bridge of the current-source inverter, which is configured to simulate a switching process of the three-phase current-source inverter;
wherein in the calculation of the crosstalk voltage spike, a maximum value of the calculated crosstalk voltage spike in the half-bridge of the current-source inverter is calculated by:
Δ
⁢
V
gs
(
t
)
=
{
I
0
t
⁢
L
s
·
[
1
-
e
-
α
⁢
t
·
cos
⁡
(
ω
⁢
t
)
-
α
ω
·
e
-
α
⁢
t
·
sin
⁡
(
ω
⁢
t
)
]
,
R
g
2
<
4
⁢
(
L
s
+
L
g
)
C
iss
I
0
t
⁢
L
s
·
(
1
-
e
-
α
⁢
t
-
α
⁢
te
-
α
⁢
t
)
,
R
g
2
=
4
⁢
(
L
s
+
L
g
)
C
iss
I
0
t
⁢
L
s
·
(
1
-
e
-
α
⁢
t
·
cos
⁢
h
⁡
(
ω
⁢
t
)
-
α
ω
·
e
-
α
⁢
t
·
sin
⁢
h
⁡
(
ω
⁢
t
)
]
,
R
g
2
>
4
⁢
(
L
s
+
L
g
)
C
iss
where t is time when current rises and falls during the switching process, expressed as:
t
=
-
(
R
g
⁢
C
gs
+
g
m
x
⁢
L
s
)
⁢
ln
⁢
(
V
miller
-
V
cc
V
th
-
V
cc
)
,
ω
=
{
1
C
iss
·
(
L
s
+
L
g
)
-
R
g
2
4
⁢
(
L
s
+
L
g
)
2
,
R
g
2
<
4
⁢
(
L
s
+
L
g
)
C
iss
0
,
R
g
2
=
4
⁢
(
L
s
+
L
g
)
C
iss
R
g
2
4
⁢
(
L
s
+
L
g
)
2
-
1
C
iss
·
(
L
s
+
L
g
)
,
R
g
2
>
4
⁢
(
L
s
+
L
g
)
C
iss
,
α
=
R
g
2
⁢
(
L
g
+
L
s
)
,
I0 is load current flowing through the reverse-voltage-blocking synthesis devices, Cgs is a gate-source junction capacitance of the second reverse-voltage-blocking synthesis device affected by crosstalk, gm is transconductance of the second reverse-voltage-blocking synthesis device, x is a fitting coefficient in a transfer characteristic curve of the second reverse-voltage-blocking synthesis device, Vth is a threshold voltage of the second reverse-voltage-blocking synthesis device, Vmiller is a Miller plateau voltage, Vcc is a positive driving voltage, Rg and Lg are respectively a gate resistance of a disturbed device and a stray inductance of a drive loop in an equivalent circuit of the current-source type double-pulse test when crosstalk occurs, Ciss is an input capacitance of the second reverse-voltage-blocking synthesis device affected by crosstalk, which is a sum of a gate-drain junction capacitance and a gate-source junction capacitance, and Ls is a sum of an internal common source inductance of the second reverse-voltage-blocking synthesis device affected by the crosstalk and stray inductance of a printed circuit board (PCB);
wherein the influencing factors for the crosstalk voltage spike include a value of the gate resistance, a value of the internal common source inductance and a value of junction capacitance of the Schottky diode of the second reverse-voltage-blocking synthesis device;
when di/dt is constant, the smaller the gate resistance of a switching transistor of the second reverse-voltage-blocking synthesis device is, the larger the crosstalk voltage spike the device bears;
the larger the common source inductance is, the larger the crosstalk voltage spike the switching transistor of the second reverse-voltage-blocking synthesis device bears;
and the larger the junction capacitance of the Schottky diode is, the faster a change in the voltage on the diode in the switching transistor of the second reverse-voltage-blocking synthesis device is, the faster the turn-on of a switching transistor of the first reverse-voltage-blocking synthesis device is, and the larger a reverse recovery current generated by coupling with the junction capacitance is, so that the current flowing through the switching transistor of the second reverse-voltage-blocking synthesis device has a larger value of the reverse over-zero, and the more pronounced a reverse recovery process of the diode is, which results in the switching transistor of the second reverse-voltage-blocking synthesis device being subjected to a larger forward crosstalk voltage spike.

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Prediction method for crosstalk spike in half-bridge of current source type inverter with silicon carbide devices

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Prediction method for crosstalk spike in half-bridge of current source type inverter with silicon carbide devices

Life of this patent

Abstract

Claims6