• Journal of Power Electronics
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• v.9 no.3
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• pp.481-490
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• 2009

This paper describes a SVPWM overmodulation scheme of NPC type three-level inverter for traction drives which extends the modulation index from MI=0.907 to unity. SVPWM strategy is organized by two operation modes of under-modulation and over-modulation. The switching states under the under-modulation modes are determined by dividing them with two linear regions and one hybrid region the same as the conventional three-level inverter. On the other hand, under the over-modulation mode, they are generated by doing it with two over-modulation regions the same as the conventional over-modulation strategy of a two level inverter. Following the description of over-modulation scheme of a three-level inverter, the system description of a vector controlled induction motor for traction drives has been discussed. Finally, the validity of the proposed modulation algorithm has been verified through simulation and experimental results.

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.820-823
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• 2003

In this paper, we describe a design procedure for cascade controller for induction motor drives based on Genetic Algorithms(GAs). Most electric drives have two separate controllers for current and speed control, which are in general designed in two consecutive steps(firstly the current controller and then the speed controller). We search simultaneously for the couple of discrete anti-windup controllers achieving the optimal compromise of weighted cost and performance indices related to both current and speed responses.

• Journal of Power Electronics
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• v.12 no.3
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• pp.477-486
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• 2012

This paper proposes a novel current control scheme for vector-controlled induction machine (IM) drives in the overmodulation (OVM) range, with which the voltage utilization of the voltage-source inverter (VSI) can be maximized. In the OVM region, the original voltage reference is modified by changing its magnitude and angle, which causes the motor current to be distorted, resulting in a deterioration of the current control performance. To meet with this situation, the harmonic components in the feedback currents should be eliminated before being input to the PI current controllers. For this, a composite observer is applied to extract the fundamental and harmonic components from the distorted currents, which gives a good performance without a delay and the effect of a fundamental frequency variation. In addition, through a detailed analysis of the response of the PI current controllers in the OVM range, the effectiveness of using the composite observer is demonstrated. Simulation and experimental results for a 3-kW induction motor drive are shown to verify the validity of the proposed method.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.3
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• pp.279-288
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• 2013

This paper proposes a improved speed control system for five-phase squirrel-cage induction motor(IM) injecting 3rd. current harmonic components with field oriented control (FOC) A five-phase IM drives present unique characteristics due to the additional degrees of freedom and also drives possess many others advantage compared with the traditional three-phase motor drive system, such as reducing a amplitude of torque pulsation at low frequency and increasing the reliability. In order to maximize the torque per ampere, the proposed motor has concentrated windings. The produced back-electromotive force is almost trapezoidal, and the motor is supplied with the combined sinusoidal plus third harmonic of currents. There is necessary to controlled 3rd harmonic current in order to high response characteristics. For presenting the superior performance of the proposed the speed control system, experimental results are presented using a 32-bit fixed point TMS320F2812 DSP with 1.5[kW] induction motor.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.804-805
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• 2006

Electric scroll-compressor drives are commonly used for e.g. home appliance cooling units. The recent development of hybrid cars with internal combustion engine in combination with electrical propulsion requires new solutions to be able to cool the passenger compartment of cars at stand-still. Both application areas demand efficient motor drives to reach good economy and efficient use of limited battery power as well as competitive volume/weight for a given output. The BLDC motor is a controllable and efficient solution. A major part of the motor is the soft-magnetic core. The powder based $Somaloy^{(R)}$ material shows high resistivity and induction as the result of engineered iron particles with in-organic coating. The unique features of compacted $Somaloy^{(R)}$ components can be utilized to enhance the shape and total volume of the BLDC motor with at least maintained efficiency compared to the use of traditional laminated steel sheet cores. A careful design of the $Somaloy^{(R)}$ components can also simplify assembly and positively influence the coil configuration. This study shows a comparison between a typical laminated BLDC motor and a redesigned, $Somaloy^{(R)}$ based version adapted for a scroll-compressor application.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.61 no.4
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• pp.206-213
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• 2012

This paper propose a improved speed control system for five-phase squirrel-cage induction motor(IM) considering effects of 3rd. harmonic current components with field oriented control(FOC) A five-phase IM drives present unique characteristics due to the additional degrees of freedom and also drives possess many others advantage compared with the traditional three-phase motor drive system, such as reducing a amplitude of torque pulsation at low frequency and increasing the reliability. In order to maximize the torque per ampere, the proposed motor has concentrated windings. The produced back-electromotive force is almost trapezoidal, and the motor is supplied with the combined sinusoidal plus third harmonic of currents. There is necessary to controlled 3rd harmonic current. For presenting the superior performance of the proposed the speed control system, experimental results are presented using a 32-bit fixed point TMS320F2812 DSP with 1.5[KW] induction motor.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.177-180
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• 2000

The accurate values of parameters of an induction motor are required for its high performance control. So far many methods using current sensors voltage sensors and speed sensor have been developed. This paper proposes an identification method of parameters of induction motor only using current sensors.

• Journal of Power Electronics
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• v.12 no.1
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• pp.75-82
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• 2012

Elimination of rotor position sensors mechanically coupled with the rotor shaft is attractive to variable speed drives primarily due to increased system reliability and cost reduction. In this regard, search for a simple and robust position sensorless control has been intensified in past few years specifically for low-cost, high-volume applications such as home appliances. This paper describes a new parameter insensitive position sensorless control for switched reluctance motor (SRM) drives satisfying such a need in this market segment. Two consecutive switch-on times of the controllable switch in hysteresis current control are compared to estimate the rotor position and speed. The proposed sensorless control algorithm is very simple to implement since it does not depend on extensive computation or any additional hardware. In addition, the proposed method is robust in that its dynamic performance is least affected by system parameter variations. The proposed approach is demonstrated on a single-controllable-switch-converter-driven SRM with two-phases that lends itself to a system with low cost and compact packaging which comes close to the intended applications. Analysis and simulation results followed by experimental verification are presented to demonstrate the feasibility of the proposed sensorless control method.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.4
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• pp.322-331
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• 2002

In this paper, a single-phase to three-phase PWM converter topology using a single-phase half-bridge PWM rectifier and a 2-leg inverter for low cost three-phase induction motor drives is proposed. In addition, the source voltage sensor is eliminated with a state observer which controls the deviation between the model current and the system current to be zero. The converter topology is of lower cost than the conventional one, which gives sinusoidal input current, unity power factor, dc output voltage control, bidirectional power flow and VVVF output voltage. The experimental results for V/F control of 3Hp induction motor drives have been shown.

• Journal of Electrical Engineering and Technology
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• v.1 no.1
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• pp.63-72
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• 2006

The purpose of this raper is to address the negative impedance instability in DC/DC converters. We present the negative impedance instability of PWM DC/DC converters loaded by constant power loads (CPLs). An approach to design digital controllers for DC/DC converters Is presented. The proposed method, called Power Alignment control technique, is applied to DC/DC step-down choppers operating in continuous conduction or discontinuous conduction modes with CPLs. This approach uses two predefined state variables instead of conventional pulse width modulation (PWM) to regulate the output voltage. A comparator compares actual output voltage with the reference and then switches between the appropriate states. It needs few logic gates and comparators to be implemented thus, making it extremely simple and easy to develop using a low-cost application specific integrated circuit (ASIC) for converters with CPLs. Furthermore, stability of the proposed controllers using the small signal analysis as well as the second theorem of Lyapunov is verified. Finally, simulation and analytical results are presented to describe and verify the proposed technique.