EV Propulsion Drive Converter SiC Power Device Over-Temperature Protection under Low Motor Speed Operation Ford Motor Company

Format:

Book

Conference/Event

Author/Creator:

Thongam, Jogendra Singh, author.

Ge, Baoming, author.

Bradford, Steven, author.

Kulkarni, Milind, author.

Conference Name:

WCX SAE World Congress Experience (2026-04-14 : Detroit, Michigan, United States)

Language:

English

Subjects (All):

Electric motors.

Electric drives.

Electric vehicles.

High voltage systems.

Sensors and actuators.

Switches.

Failure analysis.

Simulation and modeling.

Local Subjects:

Electric motors.

Electric drives.

Electric vehicles.

High voltage systems.

Sensors and actuators.

Switches.

Failure analysis.

Simulation and modeling.

Physical Description:

1 online resource

Place of Publication:

Warrendale, PA SAE International 2026

Summary:

Monitoring power device temperature in an electric vehicle propulsion drive converter is extremely important to achieve full power delivery within the maximum power capability envelope. Usually, on-die temperature sensors are installed on Si-IGBT power devices in electric vehicle propulsion drive converters to enable monitoring device temperature and achieve over-temperature protection. Currently, SiC MOSFET is a promising power device in power converters of electric drives because of its lower loss, higher switching speed, higher voltage capability, and higher junction temperature limit in comparison with the widely used Si-IGBT. However, SiC MOSFET is a more expensive device, installation of an on-die temperature sensor on SiC MOSFET will significantly increase its cost and complexity. So presently, there is no junction temperature sensor installed in SiC MOSFET due to which there is great difficulty protecting SiC MOSFET from over temperature. When a junction temperature estimation method is used to monitor SiC MOSFET temperature, the power loss computation of SiC MOSFET is a key factor. However, the existing loss calculation method assumes electric motors operate at high speed and power loss is computed/estimated with rms current. When the motor operates at low speed, the existing method is not practical because of a long fundamental period of phase current. The instantaneous power losses and hence the junction temperatures of the six power converter switches are not the same under such operating conditions. Hence, the junction temperature obtained with the loss computed from the rms current value does not reflect the actual device junction temperature, which may result in a failure of power device over-temperature (OT). This paper proposes a converter power device OT protection method under low motor speed to solve the above issues. The proposed method allows system cost and complexity reduction. It computes/estimates instantaneous loss and junction temperature for each individual power device of the power converter, which enables the OT detection at the motor low speed and/or imbalance phase operation. The paper presents the technical principle of the proposed instantaneous power loss and junction temperature estimation method, and OT protection for SiC MOSFET. Its model details, simulation, and experimental test results verify the new method

Notes:

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