Electronics takes the blame for Mercedes F1 team’s Canadian stumble

June 10, 2014 // By Graham Prophet
Formula One team Mercedes cited a power-electronics system failure as the cause of a power loss that affected both of the team’s cars within moments of each other in their most recent race, put the car of driver Lewis Hamilton out of the race, and left his fellow team driver Nico Rosberg struggling to finish and having to settle for 2nd place, having led for much of the race.

The Canadian Grand Prix, run on Sunday 8th June in Montreal, was expected to place heavy demands on braking systems and was run in hot weather, with high track temperatures. According to team officials, the failures occurred in the high-voltage power electronics package switching power between the on-board battery pack and the axle-mounted motor-generator.

What makes the incident particularly interesting from the electronic systems point of view is the remarkable consistency between two race cars – despite all the other variables in the equation, both units failed within seconds of each other.

This season's F1 cars are, effectively, assisted hybrids – previously known as KERS (kinetic energy recovery system), a regenerative braking generates power that is stored in a battery pack and is available to boost the 600-plus-HP of the internal combustion engine by around a further 160HP for short durations. This year, the system is called ERS-K, with a separate acronym for MGU-K – the kinetic motor-generator unit.

To minimise weight, with the contribution of the regenerative braking taken into account, designers have reduced the conventional disc brakes on the cars’ rear axles; with the ERS-K offline, extra stress was placed on the regular braking. One of the factors that got Rosberg to the finish line was that the teams adjusted the brake balance from rear to front – not only would Rosberg have had to cope with losing his 160-HP boost-on-demand facility, but the car’s handling would also have been different.

The team’s website commented; “At almost exactly the same time on both cars, we had a failure of the MGU-K control system. Both drivers has the same power units, were racing at the same pace and running at the same temperatures. These temperatures, around the power supply to the MGU-K in particular, were higher than expected. What we didn’t expect is that it would have such a significant impact. The MGU-K shut down on both cars and