POWER


Delivering predictive maintenance in high value IGBT systems for rail applications


By Thorsten Schmidt, Power Integrations


Figure 1: Power Integrations’ New 3300 V IGBT Module Gate Driver Reports Telemetry Data for Observability, Predictive Maintenance and Lifetime Modelling


Figure 2: System level benefi ts of Power Integrations’ Gate Driver Technology with Integrated Sensors


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n rail systems, the IGBT module and driver are critical to the lifetime of the power converter. Some suppliers provide lifetime modelling based on IGBT junction temperature. Power Integrations includes temperature reporting along with other sensors in many of its gate drivers. The method mainly preferred by the company is to measure gate voltage; if the gate voltage drops, this provides clear evidence of aging. One advantage of this technique is that real data is provided, rather than models. With measured gate voltages, systems designers can model junction temperatures if they want, as well as inferring the status of the aging of the IGBT. The approach also provides design fl exibility, meaning that many more IGBT modules can be monitored, and customers do not have to disclose potentially sensitive system information. Finally, since all systems vary, the accuracy and applicability of external modelling may also vary, calling into question the equipment status information provided. Recently, Power Integrations announced a new, single-channel, plug-and-play gate driver for 190 mm x 140 mm IHM and IHV IGBT modules up to 3300 V (Figure 1). The 1SP0635V2A0D combines the company’s proven SCALE-2 switching performance and protection features with a confi gurable isolated serial output interface, which augments driver programmability and provides comprehensive telemetry reporting for accurate lifetime estimation. Multiple sensing circuits including thermal, device and bus condition information are incorporated, simplifying system design and enhancing


observability, control and reliability. Application areas are rail traction inverters, power grid and medium-voltage drives. The serial status output protocol


incorporates critical real-time measurements, facilitating advanced operational verifi cation and dramatically increases visibility of the inverter’s health, reliability and effi ciency. Engineers may adapt monitoring and control systems to Power Integrations’ standard plug-and-play protocol or request custom adjustments by Power Integrations’ engineers during the project’s development phase. Telemetric data available from the 1SP0635V2A0D gate driver includes accurate temperature measurement, which simplifi es thermal management and eliminates the need for external temperature sensors. DC link voltage measurement is also incorporated, minimising external circuitry, reducing system complexity and cost. Closed-loop gate voltage, gate status and short-circuit monitoring ensure that modules are operated within set limits, improving effi ciency and avoiding catastrophic failures. Other features include a status monitor for the fi bre-optic interface to ensure that switching commands are received correctly. Similarly, gate monitoring ensures switching commands have been executed correctly and that the power module is in the appropriate operating condition. Short-circuit monitoring provides accurate control, directing the gate driver to respond appropriately in the event of a short circuit. Data is delivered via Power Integrations’ proprietary programmable serial interface,


44 OCTOBER 2024 | ELECTRONICS FOR ENGINEERS


which can be programmed according to customer requirements. The large players who dominate the rail market have their own proprietary protocols which have been developed over several years, therefore fl exibility in reporting is important.


System Level Benefi ts


Sensing Circuits gather system data • •


Reduce complexity and cost


Identify stress/aging of system components


• Predict maintenance requirement


Status Monitoring enhances safety and reliability • • •


Optical data bus Gate status


Protocol integrity self-check Conclusion


Although at present it is sectors such as rail, power grid and oil exploration where customers expect 20 years lifetime that are seriously demanding predictive maintenance solutions, it is only a matter of time before other industries catch on to the benefi ts that a data-based approach to maintenance can bring, avoiding downtime and emergency maintenance and not incurring excess costs due to unnecessary interventions. Because Power Integrations integrated all the sensing circuits within its gate drivers, customers can have increased system confi dence and MTBF ratings will increase.


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