A Novel Sensorless Control Strategy for Brushless Direct Current Motor Based on the Estimation of Line Back Electro-Motive Force

Abstract

Abstract:In this paper, a novel sensorless control strategy based on the estimation of line back electro-motive force (BEMF) is proposed. According to the phase relationship between the ideal commutation points of the brushless direct current motor (BLDCM) and the zero-crossing points (ZCPs) of the line BEMF, the calculation formula of line BEMF is simplified properly and the commutation rule for different positions of the rotor is presented. The estimation error of line BEMF caused by the freewheeling current of silent phase is analyzed, and the solution is given. With the phase shift of the low-pass filter considered, a compensation method using "60 • -α" and "120 • -α" is studied in this paper to eliminate the error. Finally, the simulation and experimental results show that the rotor-position-detection error is reduced effectively and the motor driven by the accurate commutation signal can work well at low and high speed.

Development and Implementation of a Low Cost μC- Based Brushless DC Motor Sensorless Controller: A Practical Analysis of Hardware and Software Aspects

“…The method which has been implemented in this paper utilizes the difference in back EMF of two phases instead of using phase back-EMF. The waveform of the back-EMF difference is shown in Accordingly f b (θ e ) and f c (θ e ) can be calculated [9]. From Equation (1) for each phase we have:…”

“…The term back-EMF method usually refers to the ZCP method [7]. Direct back-EMF control strategies have presented in [8,9], yet these methods suffer from poor, low-speed performance and require filters to suppress high frequency noise, which may induce large phase shifts to the commutation signals at high speed. Meanwhile, the terminal voltage distortion caused by the diode freewheeling current can make the position detection signal phase advance, deviating from the ideal commutation instant, especially in heavy-load conditions [10].…”

“…Then problem of smooth operation of sensorless BLDCM from stand still o high speed conditions has been addressed in [16,17]. Other problem faced during these motors operation include torque ripple minimization (which is an inherent operational feature) and several commutation techniques have also been proposed e.g., [18][19][20].Additionally, many efforts in BLDCM sensorless controller development have been conducted and introduced in the recent literature, either by use of simulation such as [21][22][23], or in experimental form, e.g., [9,24,25]. The former approaches, although useful to prove the conceptual design, are far from real operation, whereas in the latter, the fact is that most of these studies employ ready-made solutions like FPGA development, expensive industrial controllers, etc, which are not very convenient either in hardware or software parameterization in prototyping terms.Generally speaking, in some applications where the controller itself is not of actual interest, a readymade one may be purchased and used, depending on its characteristics and cost, but there are many situations where a custom, low cost and fully parameterized prototype should be built.…”

“…Additionally, many efforts in BLDCM sensorless controller development have been conducted and introduced in the recent literature, either by use of simulation such as [21][22][23], or in experimental form, e.g., [9,24,25]. The former approaches, although useful to prove the conceptual design, are far from real operation, whereas in the latter, the fact is that most of these studies employ ready-made solutions like FPGA development, expensive industrial controllers, etc, which are not very convenient either in hardware or software parameterization in prototyping terms.…”

New sensorless commutation method for BLDC motors based on the line‐to‐line flux linkage theory

“…One of the methods for sensorless BLDC motor control is to use the zero-cross points of back electromotive force [7][8][9][10][11][12][13]. Since the back electromotive force signal is not available, the zero-cross points are detected by the filtered voltages of the motor terminal.…”