Xinhui Wu

Design of a Plug-In Repetitive Control Scheme for Eliminating Supply-Side Current Harmonics of Three-Phase PWM Boost Rectifiers Under Generalized Supply Voltage Conditions

This paper presents a digital repetitive control (RC) scheme to minimize the even-order harmonics at the dc link voltage and odd-order harmonics in the line-side currents under distorted and unbalanced supply voltage conditions. The proposed current control scheme consists of a conventional PI and a plug-in repetitive controller. On the basis of the mathematical model of the three-phase pulsewidth-modulated (PWM) boost rectifier under the generalized supply voltage conditions, the control task is divided into: 1) dc-link voltage harmonics control and 2) line-side current harmonics control . In the voltage harmonics control scheme, a reference current calculation algorithm has been derived accordingly to ensure that the dc link voltage is maintained constant at the demanded value and the supply-side power factor is kept close to unity. In the line-side current harmonics control scheme, a plug-in repetitive controller is designed to achieve low total harmonic distortion (THD) line-side currents of the three-phase PWM boost rectifier. The experimental test results obtained from a 1.6-kVA laboratory-based PWM rectifier confirm that the proposed control scheme can reduce the line-side current THD from 16.63% to 4.70%, and improve the dc-link voltage tracking accuracy substantially over the conventional PI-based controller.

Analysis of the Instantaneous Power Flow for Three-Phase PWM Boost Rectifier Under Unbalanced Supply Voltage Conditions

This paper proposes the analysis of the instantaneous power flow of three-phase pulse-width modulation (PWM) boost rectifier under unbalanced supply voltage conditions. An analytical expression for the instantaneous output power has been derived, which provides the link between the output dc link voltage and the instantaneous output power. A direct relationship between the dc link voltage ripples and the second harmonic component in the instantaneous output power has been established. Based on the input and output instantaneous power analytical expressions provided, the presence of the odd order harmonic components in the ac line currents can be explained. A simple cascaded PI control scheme has been developed for the dc output voltage control. The controller ensures that the dc link voltage is maintained constant and the supply side power factor is kept close to unity under the unbalanced supply voltage operating conditions. Simulation and experimental test results are provided on a 1.6-kVA laboratory-based PWM rectifier to validate the proposed analysis and control scheme.

DC Link Voltage and Supply-Side Current HarmonicsMinimization of Three Phase PWM BoostRectifiers Using Frequency Domain BasedRepetitive Current Controllers

This paper presents a digital plug-in frequency domain based repetitive control scheme for minimizing the odd order harmonics in the supply line side currents of the three phase pulsewidth modulation (PWM) boost rectifier under the distorted and unbalanced supply voltage conditions. Based on the mathematical model of the three-phase PWM boost rectifier under the generalized supply voltage conditions, the control task is divided into: (a) dc-link voltage harmonics control and (b)supply line side current harmonics control. The proposed plug-in repetitive controller together with the conventional PI controller is designed to achieve supply line side currents with low total harmonic distortion (THD) for the three phase PWM boost rectifier. The repetitive control learning algorithm is implemented in the frequency domain by means of Fourier series approximation, instead of commonly used time domain based scheme, and provides the flexibility of choosing different learning gains and phase angle delay compensations individually for each harmonic component. The experimental test results obtained from a 1.6 kVA laboratory based PWM rectifier confirm that the THD of the supply line side currents can be reduced from 21.09% to 4.12% with the plug-in frequency domain based repetitive current controllers.

Development of a New Mathematical Model of Three Phase PWM Boost Rectifier Under Unbalanced Supply Voltage Operating Conditions

This paper proposes a new mathematical model of the three-phase PWM boost rectifier in the positive and negative synchronous rotating frames under the unbalanced operating conditions. A detailed analytical expression for dc link voltage has been presented, from which the presence of the even harmonic components in the dc output voltage and odd harmonic components in the ac input current can be deduced. A simple algorithm for the reference current calculation is proposed from the analytical point of view. The dual frame PI control scheme developed based on this model can maintain the dc output voltage almost constant and keep the supply side power factor close to unity under the unbalanced operating conditions. The feasibility of this dual rotating d-q frame control scheme is verified by experimental results on a 1.6 kVA three-phase PWM rectifier. The test results demonstrate that the control scheme based on the new mathematical model can reduce the even-order harmonics at the dc link voltage and the odd-order harmonics in the ac input current.

Efficient solar energy harvester for wireless sensor nodes

An efficient solar energy harvester for low power wireless sensor node is proposed in this paper. In the proposed harvester, maximum power point tracking (MPPT) is achieved by using constant voltage tracking principle. The implementation of the MPPT control circuit is carried out using analog discrete components. This is to minimize the energy consumption in the electronic circuits. Experimental test results obtained from a Polycrystalline solar panel of 45 mm × 76 mm in the laboratory environment shows an average power harvesting of 400 mW under 1 sun solar insolation. The proposed harvester is used to power a battery which subsequently feeds a sensor node. The harvester system provides an overall efficiency of around 93%. The efficiency calculation takes care of power losses in the power management circuit. The solar energy harvester is also tested with a crossbow wireless sensor node (WSN) to monitor temperature in the actual outdoor field environment. The harvester is able to extend the lifetime of the wireless sensor node to almost indefinite period whereas the battery powered WSN becomes inactive after 150 hours of operation.

Supply-side Current Harmonics Control of Three Phase PWM Boost Rectifiers Under Distorted and Unbalanced Supply Voltage Conditions

This paper presents a hybrid current control scheme to minimize the even order harmonics at the dc link voltage and odd order harmonics in the line currents under the distorted and unbalanced supply voltage conditions. The hybrid current control scheme consists of a conventional PI and a repetitive controller (RC). Based on the mathematical model of the three-phase PWM boost rectifier in the positive and negative synchronous rotating frames, the influence of the distorted supply voltages on the line side currents has been investigated from the analytical point of view. The control task is divided into: (a) dc-link voltage harmonics control and (b) line side current harmonics control. In voltage harmonics control, a reference current calculation algorithm has been derived accordingly to ensure that the dc link voltage is maintained constant and the supply side power factor is kept close to unity. In current harmonics control, a plug-in repetitive controller is designed to achieve low THD line currents of the three phase PWM boost rectifier. The proposed analysis and hybrid current control scheme have been validated by experimental test results on a 1.6 kVA laboratory based PWM rectifier. Test results obtained confirm that the proposed control scheme enhances the performance of the PWM rectifier over the conventional one.

Analysis and Control of the Output Instantaneous Power for Three Phase PWM Boost Rectifier Under Unbalanced Supply Voltage Conditions

This paper proposes a new method to analyze the output instantaneous power of the three phase PWM boost rectifier under unbalanced supply voltage conditions. An analytical expression for the output instantaneous power has been derived and presented, which provides the link between the output dc linkage voltage and the instantaneous output power. Based on the mathematical model of the three phase PWM rectifier in the rotating synchronous frame, the physical concept of the output instantaneous power has been explained from the analytical point of view. A direct relationship between the dc link voltage ripples and the second harmonic component in the instantaneous output power has been derived. A simple cascaded PI control scheme has been developed for the dc output voltage control. The controller ensures that the dc link voltage is maintained constant and the supply side power factor is kept close to unity under the unbalanced supply voltage operating conditions. Simulation and experimental test results are provided on a 1.6 kVA laboratory based PWM rectifier to validate the proposed analysis and control scheme

Effect of Pulse-Width Modulation Schemes on the Performance of Three-Phase Voltage Source Converter

This paper investigates the direct effect of different pulse-width modulation schemes on the performance of three phase voltage source PWM converter. Two different modulation schemes, namely, the sinusoidal PWM (SPWM) scheme and the space vector PWM (SVPWM) scheme have been evaluated and the analytical expressions for the average PWM duty cycles for the different modulation schemes have been derived. With the proposed converter model, the transfer functions between the control inputs and the output dc voltage have also been obtained. It has been shown analytically that the SVPWM scheme provides a 33.3% higher gain as compared to the SPWM scheme. Thus, the PWM converter with the SVPWM scheme shows better dynamic performances. For the same ac input voltage, the converter using the SVPWM scheme can provide 13.4% lower output voltage than that using the SPWM scheme. It shows that the SVPWM scheme provides a wider operating range for the PWM converter. In steady state, THD of the input ac current with the SVPWM scheme is smaller than that with the SPWM scheme. The experimental test results obtained confirm that improved transient and steady state performances can be achieved using the SVPWM scheme.

Analysis and Experimental Validation of the Output Voltage and Input Current Performances in Three Phase PWM Boost Rectifiers Under Unbalanced and Distorted Supply Voltage Conditions

This paper analyzes the dc output voltage and line side currents of the three phase PWM boost rectifier under unbalanced and distorted supply voltage conditions. Based on the mathematical model of the three-phase PWM boost rectifier in the positive and negative synchronous rotating frames, a detailed analytical expression for the dc link voltage has been derived and presented. It shows the presence of even order harmonic components in the dc output voltage caused by the negative sequence component of the supply voltages. The effect of the distorted supply voltage on the line side currents has been investigated from the analytical point of view and discussed in this paper. A simple cascaded PI current control scheme in the positive and negative synchronous rotating reference frames has been designed to ensure that the dc link voltage is maintained constant and the supply side power factor is kept close to unity under the unbalanced and distorted supply voltage operating conditions. Experimental test results with the proposed controller are provided on a 1.6 kVA laboratory based PWM rectifier. Test results obtained confirm that the performance of the proposed control scheme enhances the performance of the PWM rectifier over the conventional single reference frame based controller.

Dual frame control scheme with a plug-in frequency domain based repetitive controller for three phase PWM boost rectifier under distorted and unbalanced supply voltages

This paper presents a dual frame control scheme with a digital plug-in frequency domain based repetitive controller (FDRC) for minimizing the even order harmonics at the output dc link voltage and odd order harmonics in the line currents under the distorted and unbalanced supply voltage conditions. The proposed current controller consists of a conventional PI controller and a frequency domain based plug-in repetitive controller. Based on the mathematical model of the three-phase PWM boost rectifier under the generalized supply voltage conditions, the control task is divided into: (a) dc-link voltage harmonics control and (b) line side current harmonics control. The algorithm of the reference current calculation is based on voltage harmonics control to make sure that the dc link voltage is maintained constant and the supply side power factor is kept close to unity. The plug-in repetitive controller is designed to achieve line side currents with low THD for the three phase PWM boost rectifier. The experimental test results obtained from a 1.6 kVA laboratory based PWM rectifier confirm that the ripple at the dc link voltage can be reduced from 2.5% with the single frame controller to 1.0% with a dual rotating frame controller. Further, with the insertion of the proposed plug-in FDRC controller, the ripple at the dc link is reduced to 0.5%. Also, the THD of the line side current is improved from 29.03% to 5.93% by using the proposed control scheme.