This solution aims to help customers implement the low-speed sensorless control function for IPM motor, which is difficult to develop, into their various equipment easily.
Suitable for applications that require torque and high efficiency at zero/low speeds.
In addition to the conventional high-voltage version (AC200V), a low-voltage version (DC24V) has been newly released. Please use according to the voltage of your motor.

Benefits of Adopting Whole Speed Range Sensorless Solution

Torque Output at Zero/Low-Speed Range

By adopting position estimation with pulse voltage*1, it can output the rated torque at zero to low speeds (around hundreds of rpm), which conventional sensorless vector control*2 could not support.

*1: At zero/low speeds. At high speeds, drives by switching to position detection with BEMF observer.
*2: Renesas sample software “Sensorless Vector Control for Permanent Magnet Synchronous Motor (R01AN6307)”

Waveforms of current and actual angle at 1 r/min @8-pole IPM,rated load (3.7Arms)
Waveforms of current and actual angle at 1 r/min
@8-pole IPM, rated load (3.7Arms)

Improving Magnetic Pole Position Estimation Error and Reducing Estimation Time

Having the initial magnetic pole position estimation function, this solution enables quick position estimation within 0.2 seconds regardless of the motor position.
In addition, achieves magnetic pole position estimation errors under ±10deg (equivalent to GP INV).
⇒Enables quick startup and smooth motor control.

Example of magnetic position estimation (starting from standstill)
Example of magnetic position estimation
(starting from standstill)

Optimizing Current Consumption

Since motor positions can be estimated even at the low-speed range, this solution enables motor drive with minimum necessary current according to the load at low-speed range, which the conventional sensorless vector control*1 didn’t support.
⇒Can improve energy efficiency and reduce current consumption, suitable for battery applications.

*1: Renesas sample software “Sensorless Vector Control for Permanent Magnet Synchronous Motor (R01AN6307)”

Optimizing Current Consumption

Control Algorithm

  • Low-speed range: By injecting a high-frequency pulse voltage (around 1/2 of carrier frequency), the magnetic pole position and speed are estimated from the variation of the motor current.
  • Mid to high-speed range: Stops injecting a high-frequency pulse voltage and switches estimation method of the magnetic pole position and speed to the method using inductive voltage, which is proportional to the rotation speed.
Control Algorithm

Function and Specification

Function and specification of the sample program

Configuration of Whole Speed Range Sensorless Motor Solution

  • Provide software and development support tools required for sensorless control for IPM motor over the whole speed range.
  • Evaluation of 3-phase IPM motors with positive polarity and high-voltage versions can be performed by providing an IPM motor and a high-voltage inverter board.
Development support tools


High Voltage Version (AC220V, RX66T)

Low Voltage Version (DC24V, RX26T)


  • This solution achieves sensorless control over the whole speed range for salient-pole IPM motor (IPMSM).
  • Can output the rated torque over the ranges from zero(startup)/low to mid/high speeds.
    *In general sensorless motor control, it is difficult to output rated torque at zero/low speeds.
  • Since a position/speed sensor is not required, benefits cost/environment resistance/durability/miniaturization.
  • Realizes sensorless vector control by detecting position with pulse voltage using saliency of IPM motor at startup and low-speed range, and with BEMF observer at mid/high-speed range.
    ⇒Suitable for 1) applications with load torque at zero(startup)/low speeds, and 2) applications with requirement for energy efficiency at low-speed range.




Software Downloads

Type Title Date
Sample Code Log in to Download ZIP 17.14 MB 日本語
Sample Code
[Software=RX Smart Configurator|v2.15.0],[Toolchains=CC-RX|v3.04.00]
Log in to Download ZIP 15.65 MB 日本語
Application: Industrial, Renewable Energy & Grid
Compiler: CC-RX Function: Application Example IDE: CS+ for CC, e2 studio
2 items


Type Title Date
Application Note PDF 2.98 MB 日本語
Application Note Log in to Download PDF 2.73 MB 日本語
2 items