# US 11,307,239 B2 · Power transistor junction temperature determination using a desaturation voltage sensing circuit

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- Number: US 11,307,239 B2
- Document ID: US11307239B2
- Status: Granted
- Kind: B2
- Application number: 16/557,746
- Filed: 2019-08-30
- Published: 2021-03-04
- Granted: 2022-04-19
- Earliest claimed: 2019-08-30
- Assignees: NIO USA, Inc.
- Applicants: NIO USA, Inc.
- Inventors: Todd J. Kazmirski; Miaosen Shen
- Web page: https://patentgrep.com/patent/US11307239B2

## CPC

- G01R 31/2621: {for testing field effect transistors, i.e. FET's}
- B60L 3/0084: {relating to control modules}
- B60L 53/20: characterised by converters located in the vehicle
- G01R 31/007: {using microprocessors or computers}
- G01R 31/2619: {for measuring thermal properties thereof}
- G01R 31/2628: {for measuring thermal properties thereof}
- G01R 31/2632: {for testing diodes}
- H03K 17/08142: {in field-effect transistor switches}
- H03K 17/145: {in field-effect transistor switches}
- H03M 1/1295: {Clamping, i.e. adjusting the DC level of the input signal to a predetermined value}
- H03K 2017/0806: {against excessive temperature}
- Y02T 10/70: Energy storage systems for electromobility, e.g. batteries
- Y02T 10/7072: Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
- Y02T 90/14: Plug-in electric vehicles
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- B60L: PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES (arrangements or mounting of electrical propulsion units or of plural diverse prime-movers for mutual or common propulsion in vehicles B60K1/00, B60K6/20; arrangements or mounting of electrical gearing in vehicles B60K17/12, B60K17/14; preventing wheel slip by reducing power in rail vehicles B61C15/08; dynamo-electric machines H02K; control or regulation of electric motors H02P); SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES (electric coupling devices combined with mechanical couplings of vehicles B60D1/64; electric heating for vehicles B60H1/00); ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL (control or regulation of electric motors H02P); MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M)
- H03M: CODING; DECODING; CODE CONVERSION IN GENERAL (using fluidic means F15C4/00; optical analogue/digital converters G02F7/00; coding, decoding or code conversion, specially adapted for particular applications, see the relevant subclasses, e.g. G01D, G01R, G06F, G06T, G09G, G10L, G11B, G11C, H04B, H04L, H04M, H04N; ciphering or deciphering for cryptography or other purposes involving the need for secrecy G09C)
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

A measurement circuit device for a vehicle includes a power transistor and a voltage measurement circuit coupled to the power transistor that measures a voltage across the power transistor. The measurement circuit device also includes a microcontroller that determines a junction temperature using the measured voltage and adjusts a capacity of the power transistor based on the determined junction temperature. In some embodiments, the measurement circuit device may include a clamping device that clamps the voltage across the transistor when the transistor is off. The measurement circuit device may also include an analog-to-digital converter that converts the measured voltage from an analog value to a digital value.

## Claims

### Claim 1

A measurement circuit device for a vehicle, comprising:
a power transistor;
a voltage measurement circuit coupled to the power transistor that measures a voltage across the power transistor; and
a microcontroller configured to:
subtract a diode voltage associated with a diode from the measured voltage across the power transistor to calculate an adjusted measured voltage;
monitor a transistor current and a gate voltage;
determine a junction temperature using the transistor current, the gate voltage, and the adjusted measured voltage; and
adjust a capacity of the power transistor based on the junction temperature.

### Claim 2 (depends on 1)

The measurement circuit device of claim 1, further comprising:
an analog to digital converter that converts the measured voltage from an analog value to a digital value; and wherein the microcontroller determines the junction temperature using the digital value.

### Claim 3 (depends on 1)

The measurement circuit device of claim 1, further comprising:
the voltage measurement circuit configured to clamp the measured voltage when the power transistor is turned off or is switching from an off state to an on state.

### Claim 4 (depends on 1)

The measurement circuit device of claim 1, wherein the voltage measurement circuit comprises a Desaturation Voltage Sensing Circuit.

### Claim 5 (depends on 1)

The measurement circuit device of claim 1, wherein the junction temperature comprises an increase in a previous junction temperature and the microcontroller is configured to decrease the capacity of the power transistor.

### Claim 6 (depends on 1)

The measurement circuit device of claim 1, wherein the junction temperature comprises a decrease in a previous junction temperature and the microcontroller is configured to increase the capacity of the power transistor.

### Claim 7 (depends on 1)

The measurement circuit device of claim 1, wherein the microcontroller is further configured to:
adjust a diode voltage drop before subtracting the diode voltage from the measured voltage.

### Claim 8 (depends on 7)

The measurement circuit device of claim 7, wherein the microcontroller is figured configured to determine a temperature of the diode.

### Claim 9 (depends on 8)

The measurement circuit device of claim 8, wherein the temperature of the diode is set to an internal ambient temperature.

### Claim 10

A method of operating a power supply device for a vehicle, the method comprising:
a voltage measurement circuit coupled to a power transistor measuring a voltage across the power transistor;
a microcontroller subtracting a diode voltage associated with a diode from the measured voltage across the power transistor to calculate an adjusted measured voltage;
the microcontroller monitoring a transistor current and a gate voltage, and
determining a junction temperature using the transistor current, the gate voltage, and the adjusted measured voltage; and
the microcontroller adjusting a capacity of the power transistor based on the junction temperature.

### Claim 11 (depends on 10)

The method of claim 10, further comprising:
an analog to digital converter converting the measured voltage from an analog value to a digital value; and wherein the microcontroller determining the junction temperature using the measured voltage value comprises the microcontroller determining the junction temperature using the digital value.

### Claim 12 (depends on 10)

The method of claim 10, further comprising:
the voltage measurement circuit clamping the measured voltage when the power transistor is turned off or is switching from an off state to an on state.

### Claim 13 (depends on 10)

The method of claim 10, wherein the voltage measurement circuit comprises a Desaturation Voltage Sensing Circuit.

### Claim 14 (depends on 10)

The method of claim 10, wherein the junction temperature comprises an increase in a previous junction temperature, and wherein the microcontroller adjusting the capacity of the power transistor based on the junction temperature comprises the microcontroller decreasing the capacity of the power transistor.

### Claim 15 (depends on 10)

The method of claim 10, wherein the junction temperature comprises a decrease in a previous junction temperature, and wherein the microcontroller adjusting the capacity of the power transistor based on the junction temperature comprises the microcontroller increasing the capacity of the power transistor.

### Claim 16 (depends on 10)

The method of claim 10, further comprising: adjusting a diode voltage drop before subtracting the diode voltage from the measured voltage.

### Claim 17 (depends on 16)

The method of claim 16 further comprising: determining a temperature of the diode.

### Claim 18 (depends on 17)

The method of claim 17, wherein the temperature of the diode is set to an internal ambient temperature.