High-voltage, 3-phase Power Modules Reduce Size, Weight, Design Time in MEA Apps
Three-phase bridge power modules from Microchip use high-voltage SiC and IGBT switches to power More Electric Aircraft applications.
Microchip has announced a new, highly integrated, hybrid power drive module designed to help reduce motor drive circuits' size, weight, and development time in More Electric Aircraft (MEA). MEAs are aviation platforms that use electric power to replace hydraulics in flight control and other systems to save weight and reduce complexity.
Aircraft landing gear. Image used courtesy of Microchip
The new power module will be the first of 12 modules constructed with either high-voltage silicon carbide (SiC) MOSFET or insulated-gate bipolar transistors (IGBT) power switches.
The module will be configured in a three-bridge topology, well-suited for electric motor drive applications. The high level of integration means a smaller and more compact solution that saves space and weight in aircraft applications. With fewer components, the solution will also reduce design complexity.
The modules offer a high power density level and can accommodate voltages from 650 V to 1200 V, with custom options available up to 1700 V. The high voltage withstands of the internal switches are well suited to the energy-dense batteries or other power sources that drive MEA electric motors.
In addition to pure three-phase power conversion, the modules incorporate a range of protection and auxiliary functions, including inrush current limiting, soft start, and thermal sensors for external monitoring.
Along with supporting higher voltages, the use of wide bandgap materials, like silicon carbide, capitalizes on the ability of these switches to operate at higher frequencies, enabling smaller passive components and more compact circuits.
Hybrid power drive module for MEA. Image used courtesy of Microchip
Three-phase, Half-bridge Motor Control
A three-bridge topology is an inverter circuit that uses three sets of power switches (6 total) to convert DC voltage from a battery, or other DC source, to three-phase AC to drive the windings of an electric motor.
In addition to MEA applications, similar three-phase inverter topologies are used in traction inverters to power EV motors and in solar power generators to convert DC power from solar cells to grid-usable AC power. The voltage levels supported by the new Microchip modules are similar to those found in the latest EV fast charge and traction inverter circuits.
Coordination of the power switching sequence is provided by a microcontroller, typically in the form of a PWM signal. The digital signals from the MCU are passed to isolated gate driver circuits that convert the commands into analog gate drive signals that turn the FET switches on and off.
Wide bandgap devices, like silicon carbide, support higher voltages, faster switching speeds, and better thermal properties, but the wider bandgap does require more energy and higher gate voltages to induce the conduction channel that turns the switch on.
Three-phase, half-bridge inverter for motor control. Image used courtesy of Microchip
More Electric Aircraft
The goal of MEA, or hybrid electric, is to use electric power in aircraft designs to optimize performance, reduce operating and maintenance costs and ultimately reduce carbon emissions.
The current scope of MEA is for non-propulsion systems only, but the long-term vision is fully electric aircraft, including propulsion.
For now, the availability of higher-density power electronics, enabled in large part through innovation in wide bandgap technologies, offers the opportunity to use electricity and electric motors to improve aviation control systems that have traditionally relied on hydraulic, pneumatic, or mechanical designs. Rethinking system design based on electric power has shown the potential to reduce key aviation systems' size, weight, and complexity.