Granted Patent B2

US 12,500,586 · App. 19/047,758 · Granted Dec 16, 2025

Inventors: Wensheng Song (Chengdu, CN); Haoyang Tan (Chengdu, CN); Kexin Yang (Chengdu, CN); Jian Chen (Chengdu, CN); Tao Tang (Chengdu, CN); Pengcheng Xu (Chengdu, CN); Chenwei Ma (Chengdu, CN); Xinglai Ge (Chengdu, CN)

Assignee: Southwest Jiaotong University

H03K17/18H02M1/0009H02M1/32H03K2217/0027

Abstract

Claims (193)

1 . A resistor voltage-bearing type on-state voltage drop measurement circuit for junction temperature monitoring, comprising: a high-resistance series high-voltage resistor, a first switching diode, a second switching diode, a low-voltage MOSFET, an inverter, a three-state gate, an RC delay circuit consisting of a resistor and a capacitor, a current-limiting resistor, an additional current-limiting resistor, auxiliary voltage sources VDD and VCC, an operational amplifier, and an isolation operational amplifier;

wherein one end of the high-resistance series high-voltage resistor is connected to a collector of an IGBT, the other end of the high-resistance series high-voltage resistor is connected to a positive electrode of the first switching diode, a negative electrode of the first switching diode is connected to a drain of the low-voltage MOSFET, and a source of the low-voltage MOSFET is connected to an emitter of the IGBT;

a connection between the positive electrode of the first switching diode and the high-resistance series high-voltage resistor is a test point and is connected to an input end of the operational amplifier of an isolation part,

a negative electrode of the second switching diode is connected to the test point, and a positive electrode of the second switching diode is connected to power reference ground; and the auxiliary voltage source VDD is connected to the negative electrode of the first switching diode by the additional current-limiting resistor;

in a circuit of a logic part, an input signal of the circuit is obtained by inverting a first signal of the IGBT that is sent by a controller, by the inverter, and then the input signal is input to an input end of the three-state gate by the series RC delay circuit, and an input signal of a control end of the three-state gate is the first signal of the IGBT sent by a controller; after passing through the three-state gate, input signal of the IGBT becomes a signal with a delay added to a falling edge after inversion, and the input signal is finally used for switching control of the low-voltage MOSFET;

in a circuit of the isolation part, an input signal of the isolation part is from a test point voltage of a measurement part, and the operational amplifier is connected as a voltage follower, and a voltage of the voltage follower is finally used for on-state voltage drop detection by the isolation operational amplifier; and

the measurement circuit also has an output parasitic capacitance from the low-voltage MOSFET, a junction capacitance of the first switching diode and the second switching diode, an input capacitance of the operational amplifier and a PCB parasitic capacitance, which are connected to the test point.

2 . The resistor voltage-bearing type on-state voltage drop measurement circuit for junction temperature monitoring according to claim 1 , wherein when the IGBT is on-state, the low-voltage MOSFET is turned off according to the second signal, the first switching diode is in a reverse bias state, and the test point voltage is equivalent on-state voltage drop;

when the IGBT is turned off, the low-voltage MOSFET is turned on and turned off according to the second signal, the first switching diode is in a forward bias state, high voltage between the collector and the emitter of the IGBT is born by the high-resistance series high-voltage resistor, and the test point voltage is clamped to the on-state voltage drop of the second switching diode; and during a process of turning on and turning off of the IGBT, the high-resistance series high-voltage resistor bears high voltage only in a IGBT turn-off process and does not bear high voltage in other periods; and a control signal of the low-voltage MOSFET is formed by the second signal of the IGBT after conditioning of the logic part.

3 . An IGBT junction temperature online monitoring method based on the resistor voltage-bearing type on-state voltage drop measurement circuit according to claim 1 , comprising the following steps:

step 1: designing an on-state voltage drop sampling circuit based on the high-resistance series high-voltage resistor and selecting parameters according to an actual application scenario;

according to a power rating of an actual device, high-resistance series high-voltage resistors with different resistances are selected to limit a power dissipation on the high-voltage resistors to a constant value, a resistance of the high-resistance series high-voltage resistor is calculated using the power dissipation combined with an isolation voltage, specifically:

R

=

V

CE

P

wherein P is an allowed power dissipation on the high-voltage resistors, and V CE is a voltage between the collector and the emitter of the IGBT;

for the first switching diode and the second switching diode, any switching diode with a withstand voltage of about 90 V and a rated current level of mA meets requirements;

the operational amplifier requires a bandwidth of more than 1 MHZ, an input impedance greater than 1000 MΩ, an input capacitance of less than 4 PF, and an input bias current level of nA; and the isolation operational amplifier only needs to meet a requirement of a system on isolation voltage;

for parameter selection of the RC delay circuit, a delay is added to the low-voltage MOSFET when the IGBT is turned on, and a delay time of the RC delay circuit is represented as:

T

D

=

R

⁢

C

specific values of parameters of the capacitor and the resistor may be calculated according to a formula;

step 2: measuring a collector current and an on-state voltage drop model at different junction temperatures under an offline condition, and providing a calculation model for online monitoring;

when IGBT operates in a saturation region, the on-state voltage drop is represented as:

v

CE

-

ON

=

mkT

j

q

⁢

ln

⁡

(

i

C

i

S

+

1

)

+

i

C

(

R

N

+

R

CH

)

wherein m is an injection coefficient, k is a Boltzmann constant, T j is a junction temperature, q is a charge, i C is the collector current, i S is a reverse saturation current, R N is a module package resistance of an IGBT, and R CH is an internal on-resistance of the IGBT;

a partial derivative of the collector current is calculated for the on-state voltage drop, wherein a change rate of the on-state voltage drop to the collector current is represented as:

k

CE

=

∂

v

CE

-

ON

∂

i

C

=

nkT

j

qi

S

⁢

1

i

C

+

i

S

+

(

R

N

+

R

CH

)

wherein the change rate of the on-state voltage drop to the collector current is changed with the collector current; when the collector current is within a small change range, the change rate is regarded as a constant, and the on-state voltage drop is represented by piecewise linearization based on the collector current as follows:

v

CE

-

ON

(

i

C

)

=

k

n

⁢

i

C

+

V

INT

-

n

⁢

n

=

1

,

2

⁢

…

⁢

n

wherein k n is the change rate of on-state voltage drop to the collector current within different collector current ranges, which is a specific value of k CE in a certain collector current region, and n represents different current ranges; V INT-n is a constant term of an expression in each collector current range; k n and V INT-n are different in different collector current ranges; for k n , when the collector current is within a small change range, k n is considered to be a constant independent of the collector current but related to the T j according to k CE expression;

k n is calculated using a least square method by sampling the on-state voltage drop and the collector current multiple times within a certain current range and is represented as:

k

n

=

v

CE

-

ON

⁢

i

C

_

-

v

CE

-

ON

⁢

i

C

_

i

C

2

_

-

(

i

C

_

)

2

a fitting coefficient R n 2 is represented as:

R

n

2

=

1

-

∑

(

v

CE

-

ON

-

v

CE

-

ON

_

)

2

∑

(

v

CE

-

ON

-

f

⁡

(

i

C

)

)

2

step 3: performing online monitoring on the junction temperature under online conditions based on the collector current and the on-state voltage drop model obtained from offline condition testing;

in an online monitoring experiment, a power cycle experiment based on a Buck circuit is used to verify an online monitoring effect of a proposed monitoring circuit and monitoring method on the junction temperature, the Buck power cycle test bench dissipates heat from the IGBT by a heat sink, and a temperature of the IGBT is increased or decreased when the IGBT is running continuously by changing a power of the heat sink.

Priority Claims (1)

Continuity (2)

References Cited (17)