• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.409-413
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• 2001

This paper presents a comprehensive study result on reducing commutation torque ripples generated in brushless dc motor drives with only a single dc-link current sensor provided. In brushless dc motor drives with only a single current sensor, the commutation torque ripple suppression that is practically effective in low speed as well as high speed regions has not been reported. A proposed commutation compensation technique based on deadbeat dc-link current controller takes a closed loop control scheme and a parameter insensitive property. The proposed control method is verified through simulations and experiments.

• Journal of Power Electronics
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• v.9 no.2
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• pp.232-242
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• 2009

In this paper, a matrix converter with improved low frequency output performance is proposed by achieving a one-step commutation owing to a general commutation circuit applicable to n-phase to m-phase matrix converters. The commutation circuit consists of simple resister and capacitor components, leading to a very stable, reliable and robust operation. Also, it requires no extra sensing information to achieve commutation, allowing for a one-step commutation like a conventional dead time commutation. With the dead time commutation strategy applied, the distortion caused by commutation delay is analyzed and compensated, therefore leading to better output linear behavior. In this paper, detailed commutation procedures of the R-C commutation circuit are analyzed. A selection of specific semiconductor switches and commutation circuit components is also provided. Finally, the effectiveness of the proposed commutation method is verified through a two-phase to single-phase matrix converter and the feasibility of the compensation approach is shown by an open loop space vector modulated three-phase matrix converter with a passive load.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.3
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• pp.191-198
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• 1998

This paper presents a new current control method to reduce the torque ripple due to phase commutation, when the unipolar PWM method is applied for the phase current control of brushless DC motor. Phase commutation bring about an instantaneous change in the average voltage of conducting phase so that current undulates, and this undulating current generates torque ripple. In this paper, we analyze average voltage variations of conducting phase in commutation period with PWM pattern and design current controller to compensate average variations. In addition, we prove the validity of proposed method by experimental results.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.974-976
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• 2001

This paper presents a method to reduce commutation torque ripples occurred during commutation in brushless do motor drives using a single DC-link current sensor. In brushless dc motor drives with a single dc current sensor instead of 3-phase line current sensors, it is noted that dc-link current sensor cannot give any information corresponding to the motor currents during line current commutation intervals. A new technique to resolve such a problem is dealt with based on a deadbeat current control in which motor armature voltage command is computed from a dc-link current reference, an actual current and counter emf voltage. The simulation results show that the proposed method reduces the torque ripple significantly.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.5
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• pp.449-456
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• 2017

This study proposes a method for compensating for the commutation torque ripple of delta-connected brushless DC motors with low inductance based on a current predictions. At the commutation instant, a phase current at the next sampling period is predicted and compared with the reference phase current to determine whether torque ripples will occur or not. If the predicted current cannot reach the reference phase current, the reference current is modified and the relevant voltage reference is produced to reduce the torque ripple. The validity of the proposed method has been verified by simulation and experimental results. The commutation torque ripple has been decreased by 17.7% at 1,000 rpm and 80% load conditions.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.591-595
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• 1991

The load commutated current source inverter(LCCSI) with GTO-DC source forced commutation is described in this Paper. GTO-DC source forced commutation assures the stability of commutation below critical frequency determined by output capcaitor and it also gives the oppotunity of PWM operation for reducing resonant harmonic components. he simulation results clearly show hat the proposed commutation circuit works well in the resonance phenomenon between output capacitor and machine leakage inductance.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.388-391
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• 2000

In this paper a modified ZVZCS(zero-voltage/zero-current switching) commutation cell with minimum additional components which provides soft switching at both turn-on and turn-off of main and auxiliary switches as well as diodes in PWM converters is presented. The proposed soft-switching technique is suitable for not only minority but also majority carrier semiconductor devices. The auxiliary switch of the proposed ZVZCS commutation cell is in parallel with the main switch and therefore there is no current stress on the main switch and diode. The operation principles of the proposed ZVZCS commutation cell are theoretically analyzed using the PWM boost converter topology as an example. Theoretical analysis simulation and experimental results verify the validity of the PWM boost converter topology with the proposed ZVZCS commutatioin cell.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.685-688
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• 1992

This paper studies the commutation phenomenon in the Brushless DC Motor with the trapezoidal BEMF waveform. It is shown that the torque ripple am the speed ripple due to the phase commutation depend on driving sytem, operating speed am load condition. The effects of resistance and BEMF flat width on torque ripple are considered. Speed - torque characteristics of the motor is presented considering the phase commutation. Uncommutating current control method can attenuate the torque ripple in the low speed region, and also minimize the switching loss am switching frequency. In this paper, the commutation phenomena are verified by analytical formulation and simulation.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.52 no.2
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• pp.49-55
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• 2003

This paper presents a novel three-phase current-fed Pulse Width Modulation converter with switched capacitor type resonant DC link commutation circuit operating PWM pattern strategy under a design consideration of low-pass filter, which can operate on the basis of the principle of zero current soft switching commutation. In the first place, the steady state operating principle of this converter with a new resonant DC link snubber circuit is described in connection with the equivalent operation circuit, together with the practical design procedure of the switched-capacitor type resonant DC link circuit is discussed from a theoretical viewpoint on the basis of a design example for high-power applications. The actively delayed time correction method to compensate distorted currents due to a relatively long resonant commutation time is newly implemented in the open loop control scheme so as to acquire the new optimum PWM pattern. Finally, the experiment of set-up in laboratory system of this converter is concretely demonstrated herein to confirm a zero current soft-switching commutation of this converter. The comparative evaluations between current-fed hard switching PWM and soft-switching PWM converters are carried out from a viewpoint of their PWM converter characteristics.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.3
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• pp.195-202
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• 2004

This paper presents a current control strategy to reduce torque ripple of Brushless DC Motor during con)mutation. The torque ripple is mainly caused by the inequality in the rate of change between rising current and decaying one during commutation. And also it is influenced by the shape of real back EMF Therefore, in the proposed control strategy, considering real back EMF a compensation voltage is generated to equalize the rate of change in these commutating currents. And then, by providing the compensation voltage during commutation, the torque ripple can be reduced. The simulation md experimental results verify that the proposed method can reduce the torque and the current ripples significantly.