Control of Open-Loop PWM Delta-Connected Motor-Drive Systems under One Phase Failure Condition

Abstract

A new fault-tolerant control topology for open-loop motor-drive systems with Delta-connected stator windings is introduced in this paper. This new control topology enables the operation of a three-phase induction machine as a two-phase machine fed by a three-phase inverter upon a failure in one of the motor phases. This topology utilizes the "open-Delta" configuration to independently control the current in each of the two remaining healthy phases. This new control technique leads to the alleviation of any torque pulsations resulting from the consequences of the asymmetrical conditions associated with this class of faults.

An optimized vector control strategy for induction machines duringopen‐phasefailure condition usingparticle swarm optimizationalgorithm

“…Using (13, the oscillating terms are removed in the electromagnetic torque equation of the faulty 3ϕ IM, and the torque equation of the faulty 3ϕ IM can be obtained in the same way as the torque equation of a healthy 3ϕ IM. 15 To sum up, RFOC equations of the faulty 3ϕ IM using (13 can be written as (14) to (17). 15 Λ r j j= ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi…”

“…where, the superscript "e" indicates the rotational frame. Based on (14) to (17), the vector control equations of the 3ϕ IM during OPF are obtained in the same way as the vector control equations of a healthy 3ϕ IM. The only difference is that M srd is used instead of ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi M srd M srq p in the FOC equations of a healthy 3ϕ IM.…”

“…Based on (22) and 24, the stator d-q voltages of the 3ϕ IM during OPF in the rotational frame can be written as (25: (14) to (17) and (25), Figure 3 can be presented for IRFOC of star-connected 3ϕ IM drives during OPF.…”

“…16 Different methods based on open-loop scalar control, closed-loop scalar control, and vector control for delta-connected 3ϕ IM drives during OPF condition were presented. [17][18][19] The results indicated that the magneto motive force (MMF) of a 2ϕ IM (a 3ϕ IM during OPF) is equal to the sum of the components of the forward MMF and the backward MMF. The backward MMF component causes torque ripples and unbalances in the 3ϕ IM currents.…”

“…The presented vector control methods in Liu et al, 14 and Zhao and Lipo, 15 were based on current control systems, which are not accurate during mechanical loads 16 . Different methods based on open‐loop scalar control, closed‐loop scalar control, and vector control for delta‐connected 3ϕ IM drives during OPF condition were presented 17‐19 . The results indicated that the magneto motive force (MMF) of a 2ϕ IM (a 3ϕ IM during OPF) is equal to the sum of the components of the forward MMF and the backward MMF.…”