Direct Torque Control of Four-Switch Brushless DC Motor with Non-sinusoidal Back-EMF Conference Paper uri icon


  • This paper presents a direct torque control (DTC) technique for brushless dc (BLDC) motors with non-sinusoidal back-EMF using four-switch inverter in the constant torque region. This approach introduces a two-phase conduction mode as opposed to the conventional three-phase DTC drives. Unlike conventional six-step PWM current and voltage control schemes, by properly selecting the inverter voltage space vectors of the two-phase conduction mode from a simple look-up table at a predefined sampling time, the desired quasi-square wave current is obtained. Therefore, a much faster torque response is achieved compared to conventional PWM current and especially voltage control schemes. In addition, for effective torque control in two phase conduction mode, a novel switching pattern incorporating with the voltage vector look-up table is designed and implemented for four-switch inverter to produce the desired torque characteristics. Furthermore, to eliminate the low-frequency torque oscillations caused by the non-ideal trapezoidal shape of the actual back-EMF waveform of the BLDC motor, pre-stored back-EMF constant versus position lookup tables are designed and used in the torque estimation. As a result, it is possible to achieve two-phase conduction DTC of a BLDC motor drive using four-switch inverter with faster torque response due to the fact that the voltage space vectors are directly controlled. Therefore, the direct torque controlled four-switch three-phase BLDC motor drive could be a good alternative to the conventional six-switch counterpart with respect to low cost and high performance. A theoretical concept is developed and the validity and effectiveness of the proposed two phase conduction four-switch DTC scheme are verified through the simulations and experimental results. 2008 IEEE.

name of conference

  • 2008 IEEE Power Electronics Specialists Conference

published proceedings


author list (cited authors)

  • Ozturk, S. B., Alexander, W. C., & Toliyat, H. A.

citation count

  • 10

complete list of authors

  • Ozturk, Salih Baris||Alexander, William C||Toliyat, Hamid A

publication date

  • June 2008