Trends in Motor Control
Comply with stricter energy and motor efficiency regulations; even products in the moderate price range require highly precise and highly efficient inverter control. Sensorless vector control is taking the limelight because it can be highly efficient while keeping costs relatively down.
Device size is also shrinking, so available board space is becoming smaller.
In the office automation and small appliance fields, the switch from stepper motors or brushed DC motors to brushless DC motors is accelerating.
Challenges for Motor Control
- Challenge 1: Sensorless vector control requires heavy computing, and existing CPUs are insufficient [solved by Feature 1]
- Challenge 2: Would like to control multiple motors without increasing board space [solved by Feature 1]
- Challenge 3: No experience with brushless motor control or resources for speeding up development [solved by Feature 2]
Solve issues with processing speed when controlling multiple inverters and other issues with a single stroke
Use of an FPU (floating point unit) vastly improves computing performance, code efficiency, and maintainability of source code
- Motor control is more precise, and processing time is vastly reduced (Figure 1).
- Code size is reduced, so can operate on small ROM capacity (Figure 1).
- No need for the complicated scaling that is required with fixed-point calculations (Figure 2). Source code is more readable and easier to maintain, and development time is greatly shortened.
* Compared by Renesas (compared operation of Renesas motor control software with and without FPU)
Double the performance and functionality of RX23T single-motor control, and multi-motor control using a single chip
- Maximum CPU operating frequency is doubled: from 40 MHz to 80 MHz. Computing performance per megahertz is of the top level in the embedded industry; performance up to 160 DMIPS and 340 CoreMark.
- ROM size is doubled: from 128 KB to 256 KB.
- At least twice as many peripheral functions for motor control (timers, A/D converters, and analog circuits). Allows highly efficient control of multiple brushless DC motors.
A development environment that allows you to start sensorless vector control in a single day
Resources such as a 24V motor control evaluation kit that contains everything necessary for development allow you to operate a highly-efficient motor immediately
- The 24V motor control evaluation kit contains a 24V inverter evaluation board, an RX23T CPU card (RX24T CPU card is sold separately), and a brushless DC motor
- CPU cards mounted with the RX23T or the RX24T are available
- Driver software, sample programs, and other software and tools for sensorless vector control are available for download from the website
ICS (In-Circuit Scope), a tool that displays RAM variable waveforms, helps to improve debugging efficiency and ensure safety
- Display waveforms of internal program variables while the motor is rotating, to graphically check the behavior of the control
- Displaying waveforms of internal variables not only improves debugging efficiency, but also makes it easier to detect anomalous behavior, helping to ensure safety (necessity of safety has been increasing in recent years)