Arwindra Rizqiawan

A new approach to synthesis of static power converters

A new approach to synthesis of static power converters is proposed in this paper. This new synthesis technique is based on combinational form of two-port networks. By using this synthesis technique we can utilize the advantage properties of existing static power converters to generate new static converters which meet our defined output characteristic. A new dc-dc converter which has a very high ratio between its output and input voltages is derived by using this technique. Several experimental results are included to show the basic characteristics of the proposed converter.

State of Charge estimation method for lithium battery using combination of Coulomb Counting and Adaptive System with considering the effect of temperature

The needs of good State of Charge (SOC) estimation method for lithium batteries are very high, not only useful for battery protection, preventing under-discharged, controlling the battery management system, and increasing the battery life, but also to increase the useable battery power. To make an SOC estimation method, second order Thevenin dynamic battery model is chosen, where the impedance values change in accordance with the SOC level. Hybrid method, which combine Coulomb Counting Method and Adaptive System Method, is chosen here. Coulomb Counting method suffers a weakness in term of initial SOC value determination, while Adaptive System Method with its ability to adjust with changes in the system will be a solution for the mentioned drawback. It can be shown that the proposed SOC estimation model is able to function properly and fairly represent the lithium battery characteristic. The method can be used not only on the specific lithium battery, but can be used in various lithium batteries by updating the its Look-up table block. Simulation and experiment have been done to verify the proposed method.

Comparison of maximum torque per Ampere and Constant Torque Angle control for 30kw Interior Interior Permanent Magnet Synchronous Motor

In this paper the comparison of Maximum Torque per Ampere (MTPA) and Constant Torque Angle (CTA) control for 30kW Interior Interior Permanent Magnet Synchronous Motor (IPMSM) is presented. MTPA is usually used for IPMSM which has a large saliency ratio for optimum torque in the machine. But for a small saliency ratio machine, MTPA control may be not produce significant result. In order to verify the analytical results, the same sample motor is verified by using Finite Element Analysis (FEA). This verification shows that MTPA and CTA gives results as expected. It also can be shown that for small saliency motor, MTPA control has not significant extra torque compare to CTA, thus the selection of MTPA for IPMSM can be re-considered. This method is quite useful in IPMSM drive application to choose the best control for IPMSM, especially when the motors have a small saliency.

Analysis and minimization of input current and voltage ripples of five-phase PWM inverters

Analysis and minimization of input current and voltage ripples of five-phase PWM inverters are presented in this paper. The analytical expressions for the RMS value of input current and voltage ripples as a function of the PWM reference signal are derived. Different to three-phase PWM inverters, it is shown that pure sinusoidal is the optimum reference signal that produces minimum input voltage ripple. Input current ripple does not depend on the employed reference signal so the ripple canpsilat be minimized by changing reference signal. Simulation and experimental results verify the analysis.

A hysteresis current controller for grid-connected inverter with reduced losses

In this paper, a hysteresis current controller with reduced losses for three-phase grid-connected inverter is proposed. In the proposed hysteresis current controller, one of the inverter phase is clamped to the positive or negative inverter buses depending on the polarity of the phase current. Totally, each inverter phase is clamped for the duration of one third of the fundamental output period. As the inverter phase is inactive when the current is the highest, the switching losses are reduced. Simulation and experimental results are included to show the effectiveness of the proposed controller.

Analysis of power converters for high frequency resonant inductive electric vehicle charging system

The concern for the supporting power converters is unavoidable in the development of inductive power charging system technology for electric vehicle application. In both the primary and secondary sides, power converters are needed to both generate and harvest the high frequency AC power which is transferred wirelessly in a resonant frequency. In his paper, we develop the power converters that are suitable for a given resonant circuit with a series-parallel compensating topology and a given operating frequency of 50,752 Hz. In the primary circuit, the need of high frequency switching requires the soft switching states for achieving better efficiency. AC-AC converter with DC link and direct AC-AC converter will be simulated, analysed and compared. In the secondary side, the high frequency power will be rectified and injected into the battery. The power converters are simulated,, modelled and analysed by using Simulink®. At the end of the project, the AC-AC converter with DC link is proposed for the primary circuit whereas full-bridge rectifier, Buck converter and Buck-Boost converter are combined and proposed for the secondary circuit. The AC-DC converter operates with two-steps charging scheme, comprising a hysteresis current control and a duty cycle-based voltage control.

Magnetic simulation comparation of 30 kW switched reluctance motor with 6/4 and 6/10 design configurations for electric vehicle

Comparation of switched-reluctance motor (SRM) with 6/4 and 6/10 design configurations are presented in this paper. Both configurations are calculated and designed in detail to obtain the flux and torque characteristics. The study also conduct analysis for both configurations. Simulation of SRM using 2D finite element model is presented to support the analysis, and used to predict the torque produced at various currents and rotor positions. The time stepped FEA, is the most accurate method available to obtain the magnetic characteristic in an electromagnetic device. In this paper torque and flux characteristic of the model 6/4 SRM and 6/10 SRM are evaluated and compared. The SRM 6/4 produced maximum torque at 102 Nm and for SRM 6/10 produced at 145.2 Nm, so SRM 6/10 produce 42.3% greater torque than 6/4 configuration, both configuration are suitable for electric vehicle application.

Analysis of bidirectional DC fast charging according to distribution transformer loading conditions

In this paper, a bidirectional dc fast charging system for electric vehicle is analysed by considering its impact on the distribution transformer. The proposed battery charger topology combines constant voltage and constant current strategy as the battery charging control techniques. Both of working mode works interchangeably depends on distribution transformer loading condition. The model is verified by simulation that is performed by using a Thevenin model of a battery. The calculation time of charging battery is also performed for each working mode. Moreover, the impact of the dc fast charging system to the harmonics of the distribution grid is also analysed. It can be shown that the total harmonic distortion impact of charging infrastructure is less than 5%.

Impact of double-loop controller on grid connected inverter input admittance using virtual resistor

Grid connected inverter offers better controllability and better operation, however, there is a risk for local instabilities due to particular control scheme. As long as the input admittance is positive at particular resonance frequency, the risk of local instability can be suppressed. In this paper, the virtual resistor concept is employed to obtain the positive input admittance. Impact of double-loop controller using virtual resistor on converter passivity is analyzed by observing the input admittance of the grid connected inverter. By numerical analysis, it can be shown that employment of virtual resistor gives better input admittance of grid connected inverter, particularly in low frequency region.

A study of combined system of capacitor bank and shunt active power filter

Combined system of capacitor bank and shunt active power filter is proposed. Mathematical model developed in this proposed combined system is based on direct power control theory using pq0 theory. Different with conventional shunt active power filter which reactive power is compensated, here only the ripple components of reactive power is compensated. The average components of reactive power will be provided by capacitor bank. Using this proposed compensation scheme, the rating of the shunt active power filter will be significantly reduced. Simulation results are shown to verify the proposed analysis.