Thenmozhi Murthi
Thenmozhi Murthi
Home Appliance Marketing Specialist (Motor)
Published: June 2, 2021

Trapezoidal/120-degree is a simple control with back EMF as the feedback for the motor position. Back EMF-based control minimizes the need for HALL/Encoder and saves cost (with sensor installation and maintenance). Some of the requirements for small appliances (ceiling fan/vacuum cleaner/power tools) are high-speed operation, high startup torque control, position detection, and locked rotor condition. With rich peripherals and built-in PGA, RX13T serves as the best cost-optimized 32-bit MCU for small appliance motor control.

Three key takeaways from this RX13T-based 120-degree motor solution:

  1. Motor evaluation platform (48V/5A Inverter + RX13T CPU card) with demo motor
  2. Software with peripheral configuration and trapezoidal control algorithm
  3. Renesas Motor Workbench (free graphical visualization tool) to monitor or adjust motor control parameters

Although Trapezoidal/120-deg is relatively straightforward, Motor experts still need to take care of a few things: starting up current, zero crossing detection, six commutation steps, and closed-loop speed control. A sample project with the control blocks would simplify the development process and time. Also, a tailor-made code for peripheral configuration would be handy for motor experts to get started with motor solution development. In addition, customers can evaluate the trapezoidal algorithm within minutes using Renesas' real-time visualization tool (Renesas Motor Workbench).

Reflecting on our customer's voice, this solution aims to address two major challenges: Faster development/time to market and system BOM cost reduction. With a floating point unit and high-level language (C) coding, RX13T is a viable 32-bit MCU to realize 120-deg (even capable of driving field oriented control). With fast ADC + built-in PGA, BOM cost reduction would be seamless for the next-generation motor control design

In summary, a 32-bit MCU for small appliances is practical/affordable today. RX13T is the best-in-class and cost-effective 32-bit MCU for motor control for small appliances. RX13T feature highlights: 32MHz (3.37 CoreMark/MHz) with FPU, ADC with 3-channel simultaneous sample and hold circuit and built-in PGA, and 3-phase complementary PWM. Customers can easily evaluate the Renesas RX13T MCU with this solution which offers a motor evaluation platform, sample software, and Renesas Motor Workbench tool. Lastly, the RX13T 32-bit MCU for motor control was launched on our RX 10th-anniversary milestone.

Feel free to check out this solution with the Sensorless 120-degree conducting control for permanent magnetic synchronous motor (Implementation) - RX13T with “Evaluation System for BLDC Motor” application note and available sample code with our Evaluation System for BLDC Motor platform.


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