Commutation Torque Ripple Suppression Strategy of Brushless DC Motor Considering Back Electromotive Force Variation

Abstract

This paper presents a commutation torque ripple suppression strategy for brushless DC motor (BLDCM) in the high-speed region, which considers the back electromotive force (back-EMF) variation during the commutation process. In the paper, the influence of actual back-EMF variation on the torque and outgoing phase current during the commutation process is analyzed. A modified smooth torque mechanism is then reconstructed considering the back-EMF variation, based on which a novel torque ripple suppression strategy is further designed. Compared with the traditional strategy which controls the chopping duty cycle relatively smoothly in the commutation process, the proposed strategy dynamically regulates the chopping duty cycle, which makes it show a gradual decrease. This strategy can suppress the commutation torque ripple even in a long commutation process, and broaden the speed range of the commutation torque ripple reduction. Under the experimental conditions of this paper, the proposed strategy can effectively reduce the commutation torque ripple in the high-speed region, and avoid the outgoing phase current cannot be reduced to zero. The experimental results verify the correctness of the theoretical analysis and the feasibility of the proposed strategy.

Design of flux‐weakening space vector control algorithms for permanent magnet brushless DC machines on suitable synchronous reference frames

“…Hence, (16) reveals that the PMBDCM torque does not depend directly on ϑ pu further and it is proportional to just the t current component; this is the most important advantage of moving into the ft reference frame, in which the torque can be held constant at T e * simply by driving i t to the corresponding reference value i t * .…”

“…Both these considerations suggest that the φτ synchronous reference frame may be more suitable than the ft synchronous reference frame in terms of voltage saturation management and, thus, flux-weakening capability. However, these potential benefits come at the cost of restoring the dependence of T e on ϑ pu , as easy detectable by comparing (29) to (16); this means that unsuitable torque ripple occurs at steady-state operation (i φτ = i φτ * = const. ), which is assessable in about 15% in accordance with the evolution of (25) within each PMBDCM operating sector.…”

“…Based on (15) and (16) or, alternatively, on (28) and 31, it is possible to design a suitable FW-SVC for PMBDCM in the ft or φτ synchronous reference frame. In particular, two main stages can be identified and carried out sequentially: the first stage consists of setting the most suitable reference current profile (i f t * or i φτ * ) in accordance with PMBDCM operating constraints and torque demand (T e (re f ) ).…”

“…Denoting by pq the generic synchronous reference frame, in which pq corresponds to either ft or φτ alternatively, the reference current Fig. 4 The reference currents control block, in which (pq) denotes (ft) or (φτ) alternatively and k pq can be derived easily from either (16) or (31) vector must be synthesised properly by considering the influence of each PMBDCM operating constraint on i p * and i q * , as highlighted in Fig. 4.…”

Field Oriented Control-Based Reduction of the Vibration and Power Consumption of a Blood Pump

“…Vibration that exists in a motor may be due to (i) hydraulic sources (such as operating away from the best efficiency point and flow turbulence [3]); (ii) the mechanical sources (such as unbalanced impeller, bent shaft, eccentricity, cogging torque, and electro motive force (EMF) waveform imperfections [4][5][6]); or (iii) torque ripple resulting from ineffective motor commutation [7,8]. Motor commutation involves switching currents in the motor phases to develop motion and maximise torque.…”