Automotive Inverter Active Discharge Cooling via DC Link Capacitor
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Solution Overview
Problem
Automotive inverters face space constraints and thermal management challenges due to active discharge circuits, which generate significant heat and require external heat sinks, increasing costs.
Innovation Solution
A thermal management system integrates active discharge circuits on a separate board, using a thermal interface material to transfer heat to a DC link capacitor's metallic housing, connected to a coolant channel for heat dissipation without external heat sinks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an active discharge circuit is implemented in automotive inverters, then safety is improved by quickly discharging the DC link capacitor, but the circuit takes up considerable space on the main PCB
Solution Approach 1:
The active discharge circuit is extracted from the main PCB and integrated into a separate evaluation board that connects to the DC link capacitor through a breakout box. This separation removes the space-consuming discharge circuitry from the main PCB while preserving the safety function of rapid capacitor discharge.
2Speed
If an active discharge circuit is implemented, then discharge speed is improved, but the circuit generates considerable heat requiring external heat sinks
Solution Approach 1:
The active discharge circuit is merged with the DC link capacitor assembly by integrating it into the same physical housing. The capacitor's metallic housing and attached heat sink serve dual purposes: containing the capacitor and dissipating heat from the discharge circuit, eliminating the need for separate external heat sinks.
Solution Approach 2:
The heat generated by the active discharge circuit during rapid discharge is converted into a beneficial thermal management solution. The DC link capacitor's existing cooling infrastructure is utilized to dissipate this harmful heat, transforming a potential problem into an integrated thermal management feature.
3Temperature
If external heat sinks are used to dissipate heat from the active discharge circuit, then thermal management is improved, but the cost of the automotive inverter increases
Solution Approach 1:
The DC link capacitor assembly is designed to serve multiple functions: energy storage, heat dissipation for the discharge circuit, and structural housing. By making the capacitor assembly multi-functional, the patent eliminates the need for additional dedicated heat sink components, thereby reducing overall system cost while maintaining effective thermal management.
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
This approach saves space and improves thermal performance by effectively dissipating heat through the existing DC link capacitor, maintaining optimal operating temperatures without additional components.
Implementation Method 1
a thermal interface material positioned between the active discharge circuit and the DC link capacitor such that heat generated from the active discharge circuit is transferred to the DC link capacitor by the thermal interface material
Implementation Method 2
a coolant channel for a cooling fluid extending between the DC link capacitor and a base plate of the automotive inverter, wherein the heat generated from the active discharge circuit of the automotive inverter is transferred from the DC link capacitor to the cooling fluid to dissipate the heat
Data Source
AI summary
A thermal management system for an automotive inverter includes an active discharge circuit in thermal communication with a DC link capacitor, a thermal interface material positioned between the active discharge circuit and the DC link capacitor such that heat generated from the active discharge circuit is transferred to the DC link capacitor, and a coolant channel for a cooling fluid extending between the DC link capacitor and a base plate of the automotive inverter, wherein the heat generated from the active discharge circuit of the automotive inverter is transferred from the DC link capacitor to dissipate the heat. A method to thermally manage heat dissipated from automotive inverter is also provided.