Keep It Running: Benefits of Predictive Maintenance in IGBT Systems
By Thorsten Schmidt, Power Integrations
Predictive maintenance aims to minimize the frequency of maintenance by collecting and analyzing operational data to identify anomalies and behavior patterns which presage equipment failures. Using this methodology, a process can be implemented whereby repair actions can be taken before failures occur, thus avoiding unplanned downtime and unnecessary maintenance costs.
Whereas preventive maintenance is a fairly simplistic approach that is performed on a regular schedule based on usage and time, predictive maintenance only schedules interventions when data indicates that the condition of a specific machine is a cause for concern. Focussing on IGBTs, predictive maintenance is most likely to be employed in high value systems such as trains, power grids and large renewable installations such as wind turbines and solar farms.
Studies by Siemens Mobility on the use of predictive maintenance on railways have produced some startling conclusions:
“Real-time data collected from trains in operation enables precise maintenance planning, with depot stops only when they’re necessary – neither too early nor too late. This reduces unscheduled depot stops and interventions for corrective maintenance by up to 30%.”
“Data-triggered, condition-based maintenance extends intervals between maintenance, eliminates unnecessary work like premature part replacement, and reduces maintenance costs by up to 15%.”
“Automated measurements and condition-based maintenance intelligence consistently prevents unplanned downtime by enabling maintenance that’s scheduled based on actual need instead of fixed intervals. This ensures fleet availability rates of up to 100%.”
In 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, a leader in gate-driver technology for medium- and high-voltage inverter applications, includes temperature reporting along with other sensors in many of its gate drivers.
Power Integrations offers a single-channel, plug-and-play gate driver for 190 mm x 140 mm IHM and IHV IGBT modules up to 3300 V (Figure 1) used in rail, traction inverters, power grid and medium-voltage drives.
The 1SP0635 Digital combines the company’s proven SCALE-2™ switching performance and protection features with a configurable 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.
The serial status output protocol incorporates critical real-time measurements, facilitating advanced operational verification and dramatically increasing visibility of the inverter’s health, reliability and efficiency. Engineers may adapt monitoring and control systems to Power Integrations’ standard plug-and-play protocol or request custom adjustments by Power Integrations’ expert engineering team during the project’s development phase.
Telemetric data available from the 1SP0635 Digital gate driver includes accurate temperature measurement, which simplifies thermal management and eliminates the need for external temperature sensors. Data is delivered via Power Integrations’ proprietary programmable serial interface, 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 flexibility in reporting is important.
Although at present it is sectors such as rail, power grid and oil exploration in which customers expect a 20-year lifetime that are seriously demanding predictive maintenance solutions, it is only a matter of time before other industries catch on to the benefits that a data-based approach to maintenance can bring — avoiding downtime and emergency maintenance and not incurring excess costs due to unnecessary interventions.
And because Power Integrations integrated all the sensing circuits within its gate drivers, customers can have increased system confidence and MTBF ratings will increase.
