Microsemi – SmartFusion2 SoC: Sensor-Less Motor Control Solutions for Safety Critical Applications

For safety critical applications, the implementation of motor control using micro-controllers is not satisfactory because of the lack of determinism due to interrupts and the associated service routines.

Additionally, microcontroller-based implementations cannot handle more than a single motor and have serious limitations to reach high performance (tens of thousands of RPMs with sampling time less than 10μs and switching frequency higher than 100kHz). Figure 1 provides a summary of most of the challenges facing motor control engineers using microcontrollers today and what the SmartFusion2 SoC FPGAs-based solution brings as value to design engineers.

With Microsemi SmartFusion2 SoC FPGAs, the user has access to various alternatives:
1. Pure software based solution with tight control on interrupts masking
2. Partitioned hardware and software solution where the hardware is used to handle the critical parts of the motor control algorithm
3. Pure hardware solution that ensures faster and deterministic implementation

All these options are scalable to control a single or multiple (up to six) motors with a variety of algorithms in a very small density and a small form factor device. The following algorithms are available today: Sensor-less FOC of PMSM/ BLDC, FOC with hall, FOC with encoder, VFD for induction motor.

For pure hardware implementations, the user has access through Libero SoC to a complete vault of IP blocks covering Clarke and Inverse Clarke, Park and Inverse Park, advanced PI controller, rotor position GUI controls are available to configure a motor to achieve 30KRPM single motor, or allowing the configuration of 6 motors running in parallel on a single device using Time Division Multiplexed Algorithm. The GUI is also capable of displaying the real time signals from FPGA which will be very useful for debugging.

In conclusion, Microsemi’s ruggedized SoC SmartFusion2 and Igloo2 FPGAs offer larger densities allowing designers to combine their motor control implementation with additional functions implemented today in ASSPs, CPLDs, or other discrete devices. This integration will further save BoM cost, reduce board space, improve the overall reliability of the system, and simplify the procurement process.