This article was originally published by The Manufacturer
As the global shift towards sustainability accelerates, electric vehicles (EVs) are hailed as a key pillar in transforming the future of transportation. Dr Stuart Bradley, Principal Engineer for Power Electronics, Machines and Drives, WMG, University of Warwick explains.
Power electronics play a pivotal role in the electric vehicle transition, serving as the technical backbone that enables efficient control and conversion of electricity from the battery to propulsion motor and back again, which will be critical for the widespread adoption and functionality of EVs.
To meet the 2035 ambition for 100% zero emission car sales set out by the previous government, the reliability of these systems is crucial. The manufacture of a power module involves up to 150 process steps, with traditional methods potentially leaving 40-60 defects undetected. Hand-assembled inverters depend heavily on the skill and attention of operators, leading to risks of missed defects, such as improper leak testing when pressurising a cooling circuit to check for leaks.
The ability to detect and address manufacturing defects early in the production cycle ensures product quality, reduces waste, and shortens time-to-market. Innovative solutions to take advantage of these benefits are emerging, but many are out of reach to low-volume makers and SMEs due to cost. The consequence of this is that innovation is stunted due to inaccessibility and perception of high risk. A more accessible route that is making waves is the Power Electronics Reliable Manufacturing In-process Testing (PERMIT) facility at WMG, part of the University of Warwick.
Part of the Driving the Electric Revolution Industrialisation Centres (DER-IC), a network which provides open access to expertise and state-of-the-art manufacturing, test and validation equipment to democratise the process of innovation, to support the growth of power electronics, machines and drives (PEMD) UK manufacturing
Cutting the cost and impact of catastrophic failure
One of the most significant challenges in power electronics manufacturing is the detection of defects. This is because defects may not manifest during initial product operation but emerge later, potentially leading to catastrophic failures. Defects on customer vehicles are unacceptable and can lead to expensive and damaging recalls or rectification work in the field, far better to prevent them during the manufacturing process.
Catching defects such as press-fit misalignments, leakages and geometrical positioning errors during the manufacturing process is invaluable. These defects, while seemingly minor, can lead to severe operational failures, if undetected. For instance, a vehicle might operate perfectly for several months before a sudden and complete failure occurs. Electronics, by nature, either work or fail abruptly, often with little warning, making early detection essential for ensuring reliability.
Validating the manufacturing process to ensure it aligns with the design intent not only reduces the risk of such failures, but also enables the identification of affected vehicles, minimising the cost of large-scale recalls.
Reducing time-to-market and enhancing reliability
One of the key benefits of in-process testing is the reduction in time-to-market for new power electronics products. By identifying and addressing defects during the prototype stage, manufacturers can mitigate the risks associated with introducing new technologies. Giving manufacturers early insights into production performance allows them to address potential issues before they become major problems. This proactive approach is particularly important in industries like car manufacturing (electric vehicles) and renewable energy, where the pace of innovation is rapid, and the margin for error is slim.
By utilising the facility’s testing capabilities, manufacturers can ensure that these components meet stringent quality standards, improving their reliability and reducing the likelihood of costly failures down the line.
PERMIT: Accessible in-process testing
PERMIT is a significant advancement in this area, and its impact is expected to ripple across several sectors.
PERMIT, a facility funded by Innovate UK and supported by DER-IC enables manufacturers to conduct thorough, real-time testing during the production of power electronics components, such as inverters, on-board chargers and DC-DC converters. The focus is on catching manufacturing defects early, enabling manufacturers to minimise costly recalls, reduce risk and enhance product reliability and safety. Through its innovative approach, PERMIT is facilitating access to state-of-the-art in-process testing for both large manufacturers and small and medium-sized enterprises (SMEs).
The equipment consists of a flexible production line, in-process testing and end-of-line test for production process research, validation and optimisation for typical assembly operations. This includes:
- Press-fit (force and deflection) to validate correct power module fit
- Fasteners (torque and angle) to ensure correct fastener conditions
- Leak tests (pressure decay curves, helium seeker etc.)
- Connector tests (push-fit force and deflection) to ensure engagement of
connector clasps - Temperatures – powered first-time operation, ramp-up and down for electrical connections and component operation
- Vibration, noise and order track for power module check
- Electrical (voltage, current, resistance, inductances etc.) for communications system operation
- Alignment and presence detection for geometrical errors and missing components
The PERMIT facility is designed to help PEMD manufacturers prevent high-volume recalls by ensuring that as much manufacturing process data is collected as possible during production, making it easier to pinpoint issues early on.
Data-driven, cost-effective production
The data collected during in-process testing at the PERMIT facility is extensive and multifaceted, covering three main categories: metadata, waveforms and operational data.
Metadata includes essential information like serial numbers and part configurations, ensuring traceability throughout the product’s lifecycle.
Waveform data collected via sensors, provides a detailed picture of how components are behaving during the assembly process, such as measuring the force required to fit an O-ring or the geometry of the component in place.
Operational data focuses on the efficiency of the manufacturing process, recording metrics like energy usage, operation time and resources consumed.
This data collection process serves two critical purposes. First, it allows manufacturers to make real-time adjustments during production, improving efficiency and reliability. Second, it creates a robust data set that can be used for post-process analysis, allowing for continuous improvement of both the manufacturing process and product design. By fine-tuning the in-process testing protocols, manufacturers can reduce the time and energy required for testing, contributing to more efficient and cost-effective production.
Advancing power electronics manufacturing for the future, and for all
For us to truly embrace the opportunity presented by electric vehicles, we need to ensure that innovation is accessible at every level, which includes in-process testing. Supporting SMEs also means that emerging players in the industry will have access to the same high-quality testing capabilities as larger manufacturers, further driving innovation and competitiveness across the sector.
For more information on how DER-IC support in-process testing in the automotive and aerospace sectors, please contact Stuart and the team at DER-IC Midlands at midlands@der-ic.org.uk.