Revisiting motor control in electric and hybrid vehicles

BY MAJEED AHMAD

The fuel efficiency demands are pushing carmakers to produce more electric, hybrid, and plug-in hybrid electric vehicles (PHEVs). That, among other things, will require a major design overhaul of vehicle’s electronic building blocks such as ECUs and MCUs.

Both ECUs and microcontrollers driving these ECUs need to minimize heat to ensure reliability and energy efficiency. And that means preserving CPU load while electric and hybrid vehicles incorporate advanced functions and complex control software.

Here, one of the key areas demanding attention amid the continued electrification of vehicles is motor control. The motor current and angle values acquired for each control period lead to a considerable amount of static processing. And that, according to some industry estimates, consumes up to 90 percent of the CPU load of a microcontroller.

Renesas solution: build a dedicated motor control circuit inside the MCU for carrying out static operations like the acquisition of sensor data and thus preserve CPU load for running advanced motor control algorithms. The chipmaker is currently testing the dedicated motor control technology in its 40nm microcontrollers.

Renesas claims that the Intelligent Motor Timer System (IMTS) circuit block integrated into its automotive MCUs runs autonomously while it performs field-oriented control operations in mere 0.8µs. And it’s 1/10 the processing time of running this control operation via software implementation on a CPU.

The recent addition to the NXP’s family of MagniV microcontrollers marks another notable initiative for simplifying motor control in automotive systems. The MCU platform streamlines the hardware and software reuse in applications such as fluid pumps and cooling fans with a motor control toolbox and development kits.

Then there is Automotive Math and Motor Control Library (AMMCLib) that includes advanced motor control algorithms for sensor-less operations in both single and dual-shunt configuration for current sensing.