EPE Association: EPE 2018 - LS5a: Advanced Control Techniques for Power Converters

EPE 2018 - LS5a: Advanced Control Techniques for Power Converters
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2018 ECCE Europe - Conference > EPE 2018 - Topic 03: Measurement and Control > EPE 2018 - LS5a: Advanced Control Techniques for Power Converters

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   An application of flower pollination algorithm to auto-tuning of linear-quadratic regulator for DC-DC power converter
By Tomasz TARCZEWSKI [View]
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Abstract: In this paper, novel auto-tuning method of linear-quadratic regulator (LQR) for DC-DC power converter is presented and experimentally verified. The novelty of proposed approach lies in application of nature-inspired flower pollination algorithm (FPA) to automatic selection of penalty matrices needed for calculation of optimal LQR. The main advantages of the employed optimization algorithm are: reduced number of control parameters, and the ability to implementation of constraint-handling method (CHM). The latter merit ensure limitation of selected state-space and control variables what is crucial for safe operation of the DC-DC power converter. Proposed solution overcomes the main disadvantage of LQR synthesis process related to time-consuming trial-and-error tuning procedure. Simulation and experimental tests illustrate suitable selection of LQR coefficients and proper operation of DC-DC power converter.

   DC-Gain Measurement of the Frequency-to-Output Power Transfer Function based on sidebands for Domestic Induction Heating Applications
By Jorge VILLA [View]
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Abstract: This paper analyzes different alternatives to obtain the dc gain of the frequency-to-output power transfer function of a series half-bridge resonant inverter for domestic induction heating. In this application, a full-wave rectified bus voltage usually feeds the inverter, and a constant switching frequency is applied during each half-period of the mains voltage. This dc gain is the derivative of the output power with respect to the frequency. A finite difference approximation to the derivative can be obtained measuring the output power during two consecutive half-periods of the mains voltage by injecting a small frequency increment in the second one. This paper compares five alternatives to estimate the gain in only one half-period of the mains, what would allow to increase the controller bandwidth. The alternatives are based on the computation of the DTFS of the sidebands. They are off-line implemented and experimentally verified. The proposed method can also be implemented in real time into a digital controller.

   Efficiency Evaluation of Three-phase SiC Power Factor Correction Rectifier with Different Controllers
By Alireza KOUCHAKI [View]
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Abstract: This paper presents a comprehensive design of a 5 kW silicon-carbide (SiC) based three-phase powerfactor correction (PFC) to achieve high conversion efficiency. It evaluates the efficiency of theconverter by comparing two controllers: a controller without harmonic compensation (HC) in therotational reference frame and a controller with HC in the stationary reference frame. SiC switches, byexhibiting a low capacitive switching loss compared to Si switches, help increasing the switchingfrequency and reducing the size of the line filter. To achieve a very high efficiency converter, thecontroller has an impact on the efficiency, especially at low load. Normally, the current quality of gridconnectedconverter at low load reduces due to the non-linearity of the converter. This reductioninfluences the efficiency. In this paper, two methods are presented to improve the current quality atlow loads: either increasing the converter-side inductance to yield lower current ripple or improvingthe controller to mitigate the low frequency current harmonics. Both methods are investigated in thiswork and it is proved that using a proper controller can help reducing the converter-side inductor to 2/3which has a great impact on the efficiency. An optimized 5 kW SiC based PFC is designed. Maximummeasured efficiency of 99\% at full load is achieved.

   Full-wave Rectified Waveform Generation Using Dead-beat Voltage Control for DC-DC Buck Converters to Realize High Efficiency Inverter
By Sakahisa NAGAI [View]
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Abstract: This study aims to realize a high efficiency inverter by combining a DC-DC buck converter and unfolding circuit. The DC-DC converter generates a full-wave rectified waveform. The unfolding circuit changes the waveform to an AC sinusoidal waveform. In order to generate a pure AC voltage waveform, the output of the DC-DC converter should be accurately controlled. In this paper, dead-beat voltage control (DBVC) for the accurate full-wave rectified waveform generation is proposed. Simulations and experiments were conducted to validate the proposed method. As a result, it was verified that the proposed DBVC was effective for the accurate full-wave rectified waveform generation. A voltage distortion was observed when the voltage reference was close to zero. In order to suppress the distortion, only the duty after the voltage reference turns to increase is decreased. As the improved results, the distortion can be reduced by setting the decrease ratio of the duty at 0.6. Finally, the AC output waveform with low harmonics was achieved by combining the DC-DC converter and the unfolding circuit.

EPE 2018 - LS5a: Advanced Control Techniques for Power Converters
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2018 ECCE Europe - Conference > EPE 2018 - Topic 03: Measurement and Control > EPE 2018 - LS5a: Advanced Control Techniques for Power Converters
	[return to parent folder]

	An application of flower pollination algorithm to auto-tuning of linear-quadratic regulator for DC-DC power converter By Tomasz TARCZEWSKI	[View] [Download]
Abstract: In this paper, novel auto-tuning method of linear-quadratic regulator (LQR) for DC-DC power converter is presented and experimentally verified. The novelty of proposed approach lies in application of nature-inspired flower pollination algorithm (FPA) to automatic selection of penalty matrices needed for calculation of optimal LQR. The main advantages of the employed optimization algorithm are: reduced number of control parameters, and the ability to implementation of constraint-handling method (CHM). The latter merit ensure limitation of selected state-space and control variables what is crucial for safe operation of the DC-DC power converter. Proposed solution overcomes the main disadvantage of LQR synthesis process related to time-consuming trial-and-error tuning procedure. Simulation and experimental tests illustrate suitable selection of LQR coefficients and proper operation of DC-DC power converter.

	DC-Gain Measurement of the Frequency-to-Output Power Transfer Function based on sidebands for Domestic Induction Heating Applications By Jorge VILLA	[View] [Download]
Abstract: This paper analyzes different alternatives to obtain the dc gain of the frequency-to-output power transfer function of a series half-bridge resonant inverter for domestic induction heating. In this application, a full-wave rectified bus voltage usually feeds the inverter, and a constant switching frequency is applied during each half-period of the mains voltage. This dc gain is the derivative of the output power with respect to the frequency. A finite difference approximation to the derivative can be obtained measuring the output power during two consecutive half-periods of the mains voltage by injecting a small frequency increment in the second one. This paper compares five alternatives to estimate the gain in only one half-period of the mains, what would allow to increase the controller bandwidth. The alternatives are based on the computation of the DTFS of the sidebands. They are off-line implemented and experimentally verified. The proposed method can also be implemented in real time into a digital controller.

	Efficiency Evaluation of Three-phase SiC Power Factor Correction Rectifier with Different Controllers By Alireza KOUCHAKI	[View] [Download]
Abstract: This paper presents a comprehensive design of a 5 kW silicon-carbide (SiC) based three-phase powerfactor correction (PFC) to achieve high conversion efficiency. It evaluates the efficiency of theconverter by comparing two controllers: a controller without harmonic compensation (HC) in therotational reference frame and a controller with HC in the stationary reference frame. SiC switches, byexhibiting a low capacitive switching loss compared to Si switches, help increasing the switchingfrequency and reducing the size of the line filter. To achieve a very high efficiency converter, thecontroller has an impact on the efficiency, especially at low load. Normally, the current quality of gridconnectedconverter at low load reduces due to the non-linearity of the converter. This reductioninfluences the efficiency. In this paper, two methods are presented to improve the current quality atlow loads: either increasing the converter-side inductance to yield lower current ripple or improvingthe controller to mitigate the low frequency current harmonics. Both methods are investigated in thiswork and it is proved that using a proper controller can help reducing the converter-side inductor to 2/3which has a great impact on the efficiency. An optimized 5 kW SiC based PFC is designed. Maximummeasured efficiency of 99\% at full load is achieved.

	Full-wave Rectified Waveform Generation Using Dead-beat Voltage Control for DC-DC Buck Converters to Realize High Efficiency Inverter By Sakahisa NAGAI	[View] [Download]
Abstract: This study aims to realize a high efficiency inverter by combining a DC-DC buck converter and unfolding circuit. The DC-DC converter generates a full-wave rectified waveform. The unfolding circuit changes the waveform to an AC sinusoidal waveform. In order to generate a pure AC voltage waveform, the output of the DC-DC converter should be accurately controlled. In this paper, dead-beat voltage control (DBVC) for the accurate full-wave rectified waveform generation is proposed. Simulations and experiments were conducted to validate the proposed method. As a result, it was verified that the proposed DBVC was effective for the accurate full-wave rectified waveform generation. A voltage distortion was observed when the voltage reference was close to zero. In order to suppress the distortion, only the duty after the voltage reference turns to increase is decreased. As the improved results, the distortion can be reduced by setting the decrease ratio of the duty at 0.6. Finally, the AC output waveform with low harmonics was achieved by combining the DC-DC converter and the unfolding circuit.