Motor control reference platform eases development of sensorless motor control designs

The platform comprises two microcontroller boards that are used to drive an inverter. One MCU board uses an SH7125 in a 48-pin package. This is ideal for developing low cost, low power motor controls aimed at consumer appliances. The other MCU board uses an SH7286 that is capable of delivering 200MIPS. More suited to high power industrial designs, it features many connectivity options including CAN 2.0, USB, five SCI, one SSU and one I²C channel.

Both MCU boards provide motor control specific safety mechanisms. For example, the Port Output Enable (POE) pins provide a fast and deterministic response time to ensure the safe and quick shutdown of the six driving signals. In addition, the MTU2 can detect any wrong PWM commands that may generate shortcuts ensuring that the bridge is always protected. Also, twenty-two registers are write access protected to prevent any wrong software manipulation. Finally, an “output read-back feature” is available to detect any short circuit on external loads or circuit. The user is able to read back the value of the output pins and rapidly trigger the internal watch dog circuit if any unexpected value is read back.

A serial communications interface makes it possible to calibrate the motor using an attached PC. The following key control parameters are easily tuned; rotor constant, stator phase resistance & inductance, and transient inductance. Also, the proportional integral module coefficients and the acceleration & deceleration ramps can be tuned to suit the application requirements.

The MCRP06 offers a board connector for the E10A-USB on-chip debugging emulator to develop, simulate & debug any software running on the SH MCU. The on-live debugging is possible during motor rotation.
High voltage AC motors can be calibrated and driven by the MCRP06 and have their operating parameters modified in real-time.

The MCRP06 uses advanced modulation techniques to reduce the switching losses by 33%. In addition, the MTU2 includes a dead-time compensation circuit to enable higher inverter efficiency. Typically, the efficiency is improved by 15%.