Some of the highest power density motors in existence have been developed in motorsport, and now the advances made in this arena are beginning to trickle down to other industries. In the case of UK electrification experts Equipmake, which has its roots in Formula 1’s integration of hybrid systems into cars in 2009, to the marine market.
The company says its motors are the most power dense in global series production. The motors’ ‘spoke architecture’ was inspired by MD Ian Foley’s development of a flywheel-based hybrid system for the Williams F1 team, which was effectively a composite electric motor.
The interior permanent magnet motors use a spoke architecture (so-called because the magnets are arranged like the spokes of a wheel) to bring a major cooling advantage. The layout of the magnets within the rotor provides a much greater surface area for cooling, and as such, power density can be greatly increased over traditional architectures. The result is that either very high power density motors can be made, or less expensive materials used to achieve a given power density than other approaches.
The company has now launched two compact motors for marine applications, which both use the spoke architecture. The APM 120 has peak power of 125kW at 12,000rpm, continuous power of 75kW and peak torque of 130Nm. Weighing just 14kg, it has a power density of just under 9kW per kilogram. With an integrated gearbox, it measures 200mm in length and 170mm in diameter. The APM 200 has peak power of 220kW at 10,000rpm, continuous power of 110kW and peak torque of 450Nm. Weighing just 40kg, it has a power density of over 5kW per kilogram. With an integrated gearbox, this latter motor measures 247mm in length and 318mm in diameter.
Both motors can be specified with or without an integrated gearbox and can be mounted horizontally or vertically. Equipmake said it also makes all supporting power control electronics, including its own high-performance inverter which incorporates the latest silicon carbide diode technology to improve power capability and enable the inverter to run at high switching frequencies.