Motor Controller Introduction:
The three powers of new energy vehicles include motors, motor controllers and batteries. The DC power from the battery pack is modulated by the inverter bridge to output a sine wave to drive the motor. The power of the motor controller is designed according to the needs of the motor. The main power unit is the IGBT. The IGBT is the core of the motor controller. Thermal management is a very important part of the development of motor controllers.
The design of the whole vehicle will consider many road conditions, but most parts manufacturers generally only consider the working conditions of rated current and peak current when dissipating the motor or motor controller. The peak current is about the rated current. However, the loss of IGBT is more than 3 times, so the working condition of IGBT under peak current is also the thermal management of new energy vehicles must be considered.
New IGBT introduction:
Conventional IGBT modules have a large number of internal wafers and their prices remain high. In order to reduce costs, try to reduce the number of wafers. In the case of taking into account the internal wafer heat dissipation, many domestic and foreign manufacturers have tried double-sided cooling IGBT modules. The number of wafers used has been reduced by 2/3, which can reduce costs. Moreover, the power tube has the following advantages:
1. The heat dissipation channel can be attached to both sides of the power tube, and the external thermal resistance can be greatly reduced;
2. The inner part of the power tube is welded with a DBC layer, and the outer part can be directly coated with thermally conductive silicone grease and attached to the water channel;
3. The maximum temperature resistance of the power tube can reach 175℃, and the power density can also be improved to a certain extent.
Processing technology introduction:
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The shell of the motor controller generally adopts the molding process of die-casting (the process of turning and milling in the early proofing), but on the one hand, as the power density of the motor controller increases, on the other hand, the cost requirements are becoming more and more demanding ( The cost is mainly in the IGBT module), the combined process is becoming more and more common in the design of the motor controller water channel. The shells are joined together, and so on.
Waterway structure and materials: ADC12
Loss data
Power Supply 350.85W
Boundary conditions:
Refrigerant: 50% ethylene glycol aqueous solution by volume;
Refrigerant temperature: 65℃
Volume flow: 8L/min
Design requirements:
Flow resistance <80Kpa;
IGBT junction temperature (rated working condition) <110
CIGBT junction temperature (peak condition) <160℃
Cloud map of flow field distribution
The waterway resistance is about 65Kpa, which is less than 80Kpa, which can meet the requirements.
Temperature field distribution cloud map
Under the rated current, the junction temperature of IGBT is 103.4℃, and the junction temperature of diode is 87.2℃, both of which are lower than 110℃, which can meet the requirements.
Under peak current, the junction temperature of IGBT is 150.8℃, and the junction temperature of diode is 120℃, both of which are lower than 160℃
In conclusion
1.Through simulation, it can be found that the waterway resistance is about 65Kpa, which is lower than the requirement of 80Kpa.
2. Under the working condition of rated current, the junction temperature of IGBT is 103.4℃, and the junction temperature of diode is 87.2℃, which is lower than 110℃, which can meet the requirements.
3. Under peak current conditions, the junction temperature of IGBT is 150.8°C, and the junction temperature of diode is 120℃, which is lower than 160℃, which can meet the requirements.
