Power Control Unit Mounting Structure Thermal Management
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Solution Overview
Problem
In vehicles with integrated rotary electric machines, the power control unit (PCU) faces overheating issues due to inadequate cooling, particularly in heavy-duty operating states, where the boost converter, inverter, and control board temperatures rise, leading to reduced efficiency and increased manufacturing costs.
Innovation Solution
A power control unit mounting structure with an anchoring pedestal made of resin, a cooler with a heat-conductive board mounting base, and a thin metal cover that restricts heat transfer from the motor case, along with a heat-insulating chamber to prevent temperature increases, ensuring effective cooling of the control board using a separate coolant system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the power control unit is integrated into the motor case with shared cooling, then the device complexity is reduced, but the control board temperature rises due to heat from the boost converter and inverter
Solution Approach 1:
The patent divides the power control unit into separate mounting areas: the boost converter and inverter are mounted on the motor case, while the control board is mounted on a separate bracket attached to the motor case. This spatial segmentation allows independent thermal management for each component, preventing heat from the power electronics from directly affecting the control board.
Solution Approach 2:
The patent introduces a heat insulating plate between the motor case and the control board bracket. This intermediary component blocks heat transfer from the motor case (which contains hot power electronics) to the control board, thereby protecting the control board from thermal effects while maintaining the integrated structure.
2Temperature
If a separate cooling system is provided for the power control unit, then the control board cooling is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent makes the motor case serve multiple functions: it acts as both the housing for the motor and as the mounting base for the power control unit components. The motor case's existing cooling capabilities are extended to also cool the power electronics, eliminating the need for a completely separate cooling system while maintaining effective thermal management.
Solution Approach 2:
The patent combines the cooling functions for the motor and power control unit into a single integrated system. The motor case serves as a common thermal management platform, with heat dissipation paths that serve both the motor and the mounted power electronics components, thereby simplifying the overall cooling system structure.
3Temperature
If heat insulating measures are added to protect the control board, then the temperature control is improved, but the manufacturing cost increases
Solution Approach 1:
The patent uses a thin heat insulating plate to block heat transfer to the control board. This thin film approach provides effective thermal insulation while adding minimal weight, complexity, and manufacturing cost compared to bulk insulation materials or complex thermal management systems.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively cools the control board, reducing temperature rises and maintaining efficiency while minimizing manufacturing costs by using a lightweight, cost-effective design that suppresses heat transfer and convection.
Implementation Method 1
a cooler (27) having the power module (13)
Implementation Method 2
a heat-conductive board mounting base (14) connected to a top of the cooler (27)
Implementation Method 3
a transfer of heat from the motor case to the power control unit is restricted by the anchoring pedestal (22) and the cover (43)
Data Source
AI summary
A PCU (20) comprises an anchoring pedestal (22) that is attached to the opening of a transaxle and that has been molded from resin so as to be formed integrally with a terminal block (21); a cooler (27) that is disposed on top of the anchoring pedestal (22) and that has a power module; a heat-conductive board stay (14) connected to the top of the cooler (27); and a control board (29) connected to the top of the board stay (14). This mounting structure is configured such that by disposing the board stay (14) near a cooling tube (17a) for introducing coolant cooled by a radiator and by attaching the stay to the cooler (27) via a heat-dissipating sheet (61a) for actively conducting heat from the control board, the control board (29) is cooled by the coolant before the coolant has absorbed heat. Thus, the pressure elevation converter and inverter that form the power control unit and the motor are housed as a single component inside one case and the coolability of the control board disposed at the top of the power control unit can be ensured.