Reference design for BLDC motor operation and Diagnostics




  • Bldc motor generally has a High initial torque which decreases as Speed increases.
  • The design deals with the independent control of all the phases in the BLDC motor.


The reference design is based on the design of a bldc motor controller based on a Mosfet driver which can operate in a range of 6V of 54 Volts. The design is based on ST Microelectronics design of EVAL-L9907


The BLDC motor’s electronic commutator sequentially energizes the stator coils generating a rotating electric field that drags the rotor around with it. All electric motors generate a voltage potential due to the movement of the windings through the associated magnetic field. It helps in the generation of a field which helps in the rotary movement of the motor. The motor is controlled through an electronic speed Controller which helps in controlling the phases of the motor inducing the current required to run the motor.

The key parameters to design a BLDC motor controller are :

  • The operating Voltage for Controller as it defines the operating Voltage of motors which are compatible with the controller.
  • The current capacity of the controller which deals with the continuous and peak current which can be provided to the motor. The motor should give optimum efficiency when the controller provides it with the required current.
  • Device Support to Communications buses. The controller should be able to establish a communication link with the computer or any other device which can help in the reconfiguration of the controller. Generally, the communciation methods are SPI, I2C, UART and JTAG.
  • The controller should follow IP66 standards designed for automotive and hazard protection and should be compatible with different standard connecters for BLDC motors.
  • The controller should be easy in debugging and repairable in terms of replacing MOSFETs or gate drivers.
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The features provided by the design are :

  • The operating voltage is 6 Volts to 54 Volts.
  • The rated continuous current is 20 amperes.
  • The communication support is SPI communication with an integrated USB port.
  • The design can be integrated with SMD and through-hole Power Mosfets.
  • The design is aligned with a Smart battery Voltage meter with 3-LED indicators.

The reference design includes all the necessary documentation including schematics, Circuit diagram, BOM etc. All the necessary documents can be downloaded here.




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