Delivering accurate predictions that align with physical measurements to improve inverter thermal management

About the customer

Myway Plus Corporation (Myway), headquartered in Yokohama, Kanagawa, Japan, is a global leader in power electronics and electrical energy solutions. The company specializes in innovative, eco-friendly technologies across various industries, focusing on motor evaluation, power electronics and energy management systems. By offering tailored hardware and software solutions, Myway enables its clients to adopt more sustainable, more efficient practices. Myway continues to push boundaries in technology development for renewable electrical energy applications

Their challenge

Myway faced the challenge of comparing its Simcenter™ software thermal management simulation results with real-world data for a silicon carbide (SiC) inverter. The goal was to validate the accuracy of its Simcenter simulation solution against Myway’s physical test data and measurements.

Inverters are critical components for electric vehicle (EV) charging and energy management. They require proper thermal management to avoid heat related issues, such as thermal runaway, that can jeopardize vehicle components, batteries and safety.

Successful thermal management must address two major hurdles:

• Heat loss calculation: Accurately calculating heat losses in power modules, which are temperature dependent
• Thermal path and airflow management: Managing the airflow and thermal paths surrounding the inverter’s complex geometry to ensure adequate heat dissipation

If Siemens Digital Industries Software’s solution addressed these hurdles – producing simulation results that matched Myway’s physical data – Myway could validate its accuracy. Myway would then look forward to adopting the solution into its next-gen inverter development programs to avoid costly over-designs and prevent system failures early in the design cycle.

Our solution

Siemens engineers used the Simcenter advanced thermal management and power electronics simulation solution to analyze a SiC inverter model. The approach involved creating a high-fidelity model of the inverter system, running detailed simulations on it and comparing the results to physical data.

Specifically, the team used Simcenter Simlab™ software and Simcenter PSIM™ software to calculate power losses and temperature distributions within the inverter. This workflow addressed heat dissipation in the SiC modules as well as heat variations based on the surrounding temperature, which makes predicting thermal behavior difficult (figure 1). Siemens’ two-way workflow tackled the issues as follows:

• Simcenter PSIM calculated heat dissipation in the SiC modules, factoring the component temperature
• Simcenter Simlab simulated air flow, heat transfer and temperatures based on the Simcenter PSIM-calculated heat dissipations

For real-world validation, Myway engineers attached thermocouples to the heat sink, close to the SiC modules, and measured temperature rises (figure 2). Full computational fluid dynamics (CFD) analysis was used to capture the air flow around the heat sink and conjugate heat transfer.

Since accurate heat loss was unknown, the engineers used Simcenter PSIM to simulate and extract actual losses of the devices, considering in this case a frequency of 40 kilohertz (kHz) and a voltage of 800 volts (V). A case temperature of 60 degrees Celsius (°C) was assumed for the first iteration. The heat dissipation calculated by Simcenter PSIM was fed into Simcenter Simlab to predict temperature distribution. This iterative process ensured a close match between simulation and real-world results.

Results

Using the Siemens’ high-fidelity thermal management solution provided Myway with precise calculations for the inverter, including the power losses and temperature profile. The coupled Simcenter PSIM and Simcenter Simlab workflow delivered accurate predictions that aligned with real-life measurements, providing insights for streamlining development time.

“Using the Simcenter PSIM and Simcenter Simlab workflow significantly increases the fidelity of simulations, providing organizations with an optimal inverter design that addresses performance, cost, development time and safety,” says Kan Yamagishi, systems department director at Myway Plus. “Moreover, this intuitive, easily deployable solution can be used by both power electronics engineers and thermal analysis engineers.”

Unlike traditional methods where rough heat loss estimations lead to temperature prediction errors that result in either expensive overdesigning or thermal failures, Myway found that Siemens’ solution offered exceptional accuracy that could eliminate costly overdesigns and reduce the need for physical prototyping in the inverter design cycle.

The results are clear; leveraging Simcenter PSIM and Simcenter Simlab offer an effective thermal management solution for developing complex inverter systems. With Siemens’ approach, organizations can detect issues like overheating early in the design phase and thereby shorten design cycle time, improve product safety and prevent downstream manufacturing issues.