Fig 1 - uploaded by Daniel Zammit
Content may be subject to copyright.
Source publication
This paper presents compensation techniques for component non-linearities in H-Bridge Inverters as those used in Grid-Connected Photovoltaic (PV) Inverters. Novel compensation techniques depending on the switching device current were formulated to compensate for the non-linearities in inverter circuits caused by the voltage drops on the switching d...
Contexts in source publication
Context 1
... compensate the harmonics in the inverter output current and voltage caused by the distortion created by the component non-linearities like the voltage drops on the switching components. This type of compensation will be dealt with in this paper, in addition to dead time compensation, by considering a single phase H-bridge inverter as shown in Fig. ...
Context 2
... voltage V ref of 10 V peak, switching frequency f s of 10 kHz and dead time T d of 0.5 s. The inverter modeled in Plecs is shown in Fig. 9. The characteristics considered in the models for the IGBTs and diodes were V ce0 = 1.15 V, r ce = 112.05 m, V f0 = 1.15 V and r d = 70.49 m. In these simulations the inverter was operated in open loop. Fig. 10 shows the inverter with the compensation modeled in Simulink and Plecs, including both the dead time and the device drop compensations. This model obtains the compensation voltage by using the average inverter current. Fig. 11(a) shows the filtered load voltage V loadf and the load current I load without compensation. As can be clearly ...
Context 3
... = 1.15 V, r ce = 112.05 m, V f0 = 1.15 V and r d = 70.49 m. In these simulations the inverter was operated in open loop. Fig. 10 shows the inverter with the compensation modeled in Simulink and Plecs, including both the dead time and the device drop compensations. This model obtains the compensation voltage by using the average inverter current. Fig. 11(a) shows the filtered load voltage V loadf and the load current I load without compensation. As can be clearly observed the resulting load voltage and load current are far from being sinusoidal which indicates a high amount of harmonics, caused by the inverter non-linearities. Fig. 11(b) and (c) shows the filtered load voltage V loadf , ...
Context 4
... compensation voltage by using the average inverter current. Fig. 11(a) shows the filtered load voltage V loadf and the load current I load without compensation. As can be clearly observed the resulting load voltage and load current are far from being sinusoidal which indicates a high amount of harmonics, caused by the inverter non-linearities. Fig. 11(b) and (c) shows the filtered load voltage V loadf , the load current I load and the compensation voltage V tcomp which includes both the dead time and the device drop compensations. In the result of Fig. 11(b) the simulation was performed with the compensation calculated using the average load current and not the instantaneous current, ...
Context 5
... voltage and load current are far from being sinusoidal which indicates a high amount of harmonics, caused by the inverter non-linearities. Fig. 11(b) and (c) shows the filtered load voltage V loadf , the load current I load and the compensation voltage V tcomp which includes both the dead time and the device drop compensations. In the result of Fig. 11(b) the simulation was performed with the compensation calculated using the average load current and not the instantaneous current, which leads to a small inaccuracy in the compensation, resulting in waveforms where distortion is still present but reduced. In the result of Fig. 11(c) the simulation was performed with the compensation ...
Context 6
... the dead time and the device drop compensations. In the result of Fig. 11(b) the simulation was performed with the compensation calculated using the average load current and not the instantaneous current, which leads to a small inaccuracy in the compensation, resulting in waveforms where distortion is still present but reduced. In the result of Fig. 11(c) the simulation was performed with the compensation calculated using the instantaneous load current. As can be noted, the load voltage and load current are practically sinusoidal, which clearly demonstrates the effectiveness of the compensation ...
Context 7
... tests with the inverter were carried out to test the compensation techniques. Figs. 12 and 13 show a block diagram of the test setup with the inverter connected to a load and the inverter test rig, respectively. The inverter was operated under open loop control with a resistive load R L of 0.5 and an inductor L i of 1.2 mH. The inverter was controlled by the dsPIC30F4011 microcontroller from Microchip. Through the use of the ...
Context 8
... and current waveforms, thus resulting in more harmonic content. The compensation should be correctly applied according to the direction of the current. Therefore, accurate sensing of the current direction is required. This becomes problematic if the current being sensed is distorted, especially if it exhibits crossover distortion as shown in Fig. ...
Context 9
... as stated earlier. The timing was obtained by observing the phase shift between the output voltage and the output load current, and observing also the moment any applied compensation takes place, by analyzing the data obtained from the oscilloscope. The data for the inverter voltage and the load current were plotted in Matlab as can be seen in Fig. ...
Context 10
... inverter waveforms shown in Fig. 15 represent the low order harmonic content of the inverter output waveforms. The inverter output voltage and current were sampled at high frequency and an FFT was performed in Matlab on the sampled data. The waveforms shown are the reconstruction of the first 13 harmonics from the FFT results for the inverter voltage (V invr ) and load ...
Context 11
... load current (I load ) is also shown. The requested voltage in the test was 10 V peak with the inverter connected to a 0.5 load without compensation. One can note the drop in the voltage waveform when the load current crosses zero, after which the voltage will start to gain its magnitude slowly but never reaches the requested voltage output. Fig. 16(a) shows the inverter voltage V invr and the fundamental component of the inverter voltage V invfund when compensation is applied with a delay. When the current crosses zero the inverter voltage experiences a drop in the magnitude, and then recovers fast when compensation kicks in. Fig. 16(b) shows the inverter voltage V invr and the ...
Context 12
... slowly but never reaches the requested voltage output. Fig. 16(a) shows the inverter voltage V invr and the fundamental component of the inverter voltage V invfund when compensation is applied with a delay. When the current crosses zero the inverter voltage experiences a drop in the magnitude, and then recovers fast when compensation kicks in. Fig. 16(b) shows the inverter voltage V invr and the fundamental component of the inverter voltage V invfund when the compensation timing is applied ...
Context 13
... voltage correctly is to, calculate the phase difference between the inverter voltage and current according the load, and apply this phase shift to the current reference. Fine tuning of the shift can then be performed by observing the moment the compensation voltage is really being applied, by analyzing the inverter voltage waveform as shown in Fig. 16(a) and ...
Context 14
... obtain a plot of the device drop compensation (without dead time compensation) the device drops for the IGBTs and diodes were modeled as piece-wise current dependent models and calculated using Matlab. Fig. 17 shows the voltage errors for the two legs of the inverter (V error1 and V error2 ), with a load current of 15.3 A peak. Fig. 18 shows the output voltage error, and therefore the output voltage compensation required for a load current of 15.3 A ...
Context 15
... obtain a plot of the device drop compensation (without dead time compensation) the device drops for the IGBTs and diodes were modeled as piece-wise current dependent models and calculated using Matlab. Fig. 17 shows the voltage errors for the two legs of the inverter (V error1 and V error2 ), with a load current of 15.3 A peak. Fig. 18 shows the output voltage error, and therefore the output voltage compensation required for a load current of 15.3 A ...
Similar publications
A novel direct ac-ac converter based on the switched-capacitor and series resonant principle, featuring with soft switching characteristic and bidirectional power flow, is proposed in this paper. The converter consists of a LC resonant tank, switched-capacitors and reverse blocking IGBTs (RBIGBT), resulting in small size and light weight; high effi...
Citations
... H-bridge inverters with LC (inductor-capacitor) filters output have found wider application in solar photovoltaic, wind, as well as fuel cell power generation systems [1][2][3][4][5][6]. High-performance H-bridge inverters with LC filters output must provide high-quality AC (alternating current) output voltage, fast dynamic characteristics, and low levels of total harmonic distortion (THD), even under high non-linear loads. ...
An H-bridge inverter with LC (inductor-capacitor) filter output allows the conversion of DC (direct current) power to AC (alternating current) power that has been used in a variety of applications, such as uninterruptible power supplies, AC motor drives, and renewable energy source systems. The fast finite-time sliding mode control (FFTSMC) features acceleration of the system state towards the equilibrium position as well as conserving insensitivity against internal parameter fluctuations as well as external load disturbances falling within the predetermined bounds. However, the FFTSMC would potentially witness chattering or steady-state errors as indefinite margins come to be exaggerated or underestimated. The chattering in the sliding mode control practice is oscillatory defective behavior. It induces inefficient operation, higher switching power losses in the transistor circuits, as well as saturated actuators, thus impairing the inverter’s output energy efficiency and raising harmonic distortion. Therefore, this paper presents the H-bridge inverter with LC filter output, which is controlled by a grey prediction fast finite-time sliding mode trajectory tracking. A more highly accurate grey prediction model based on the centered approximation methodology is deployed to vanish the chattering as well as steady-state errors. Taking into account the union of grey prediction and FFTSMC, a feedback-controlled H-bridge inverter with LC filter output allows attaining a highly efficient as well as quality sine-wave output voltage. The presented state-feedback control strategy is robust, less complex, attains more rapid convergence, and is highly accurate. The design process, computer simulation, as well as experimental results of the proposed state-feedback control strategy established that the H-bridge inverter with LC filter output has the capability to exhibit fast dynamic response time as well as good steady-state tracking behavior of the output voltage under step-loading changes and nonlinear loading conditions.
... There have also been many studies dealing with various control methods for the inverter to smooth the output responses of the converter. Converter control methods for improving output response stability without regard to whether there is any influence on the harmonics produced level [10], [11]. Moreover, most of these studies are simulations under standard conditions without outside physical effects like the natural environment, application for energy backup sour. ...
... Otherwise, m a > 1 is considered nonlinear control region. Current control methods all give control wave values in the linear region [10] with the amplitude of the fundamental sine component of the phase voltage V AC in the output waveform proportional to the modulation factor according to the formula ...
... Another important factor related to the quality of the inverter is the frequency modulation factor which is the ratio of the f c to f r . The m f value is designed to have an even positive value [10]- [12]. Suppose m f is a non-integer value, subharmonic components in the output waveform. ...
Bài viết tìm hiểu việc triển khai các kỹ thuật điều khiển chế độ rộng xung hình sin (SPWM) để giảm thiểu sóng hài trong bộ biến tần quang điện. Các nhà nghiên cứu đã sử dụng kết hợp các đánh giá mô phỏng và thử nghiệm để đánh giá hiệu quả của các phương pháp này trong các hệ thống quang điện. Nghiên cứu nhấn mạnh tầm quan trọng của việc giảm sóng hài trong bộ nghịch lưu quang điện, vì biến dạng sóng hài có thể dẫn đến các vấn đề về chất lượng điện năng và ảnh hưởng đến hiệu suất tổng thể của hệ thống quang điện. Các phương pháp điều khiển SPWM được coi là một cách tiếp cận hiệu quả để giảm thiểu những biến dạng này. Để đánh giá hiệu suất của các kỹ thuật điều khiển SPWM, các nhà nghiên cứu đã sử dụng cả thí nghiệm dựa trên mô phỏng và thí nghiệm trong thế giới thực với các hệ thống quang điện thực tế. Cách tiếp cận dựa trên mô phỏng cho phép họ lập mô hình các kịch bản khác nhau và tối ưu hóa các phương pháp điều khiển trong các điều kiện khác nhau, trong khi các thử nghiệm trong thế giới thực cung cấp những hiểu biết có giá trị về khả năng ứng dụng thực tế của các kỹ thuật này. Kết quả thực nghiệm quan sát được cho thấy phương pháp đề xuất có mức méo hài đầu ra thấp hơn so với phương pháp điều khiển trước đây, đồng thời giá trị thực tế bám sát giá trị tham chiếu và tuân thủ các tiêu chuẩn vận hành của IEC và IEEE.
... An H-bridge is used to drive a load in both directions, such as a brushed DC motor. It also regulates the flow of electricity to a load [22]. An H-bridge is made up of four switches that control the flow of electricity to a load. ...
Easy modular I action is one of the benefits of a cascaded H-bridge (CHB) inverter. This study proposes an only one multilevel inverter comes with a unique H-bridge unit. The structure of the proposed topology is then enhanced in order to make use of switching devices and DC-link voltage inputs while creating a massive number of voltage steps. A cooperative active and reactive power control strategy is offered to earn a better real and reactive power management for every DC voltage source of a photovoltaic (PV) module, as well as boost systems power quality and reliability. A unique control approach and proportional pulse width modulation (PWM) modulation are described for the cascaded H-bridge multilevel inverters for grid-connected systems. Each H-bridge module can give different power levels thanks to this control. To supply the DC source, use the system's proportional, integral and derivative (PID) controller. The functionality and achievements of the proposed scheme with its associated algorithms in production of all operating voltage have been proven using experimental data from a nine-level single-phase inverter. Finally, to construct a cascaded H-bridge nine-level inverter, the proposed control strategy is developed and implemented in MATLAB software. © 2023 Institute of Advanced Engineering and Science. All rights reserved.
... The waveforms distortion caused by dead time is affected by its length, given the switching frequency and the input DC voltage. The reduction of dead time enabled by advanced GaN FETs as a switching solution improves the shape of the waveforms without the use of dedicated software resources to compensate for the waveform distortion drawbacks [11]. ...
... In the inverter leg shown in Figure 15a, the gate commands V g1 , V g2 are obtained by comparing the triangular carrier signal v tr with the modulation control voltage v mod , as shown in Figure 15b. The dead time is necessary to avoid cross conduction of the switching devices, but introduces a nonlinear effect that influences the output waveform quality [11,33]. This leads to an output phase voltage error v dt , which can be expressed as follows [33]: ...
... These algorithms require the reconstruction of the voltage applied to the inverter and must also, therefore, consider its nonideal behavior to avoid introducing orientation errors [33,35]. The nonlinearity of the average voltage output waveforms related to the abovementioned dead time distortions is usually compensated by implementing various openloop and closed-loop algorithms [11,[36][37][38], which also include self-commissioning techniques to identify the magnitude of these voltage drops [35]. ...
The efficiency and power density improvement of power switching converters play a crucial role in energy conversion. In the field of motor control, this requires an increase in the converter switching frequency together with a reduction in the switching legs’ dead time. This target turns out to be complex when using pure silicon switch technologies. Gallium Nitride (GaN) devices have appeared in the switching device arena in recent years and feature much more favorable static and dynamic characteristics compared to pure silicon devices. In the field of motion control, there is a growing use of GaN devices, especially in low voltage applications. This paper provides guidelines for designers on the optimal use of GaN FETs in motor control applications, identifying the advantages and discussing the main issues. In this work, primarily an experimental evaluation of GaN FETs in a low voltage electrical drive is carried out. The experimental investigation is obtained through two different experimental boards to highlight the switching legs’ behavior in several operative conditions and different implementations. In this evaluative approach, the main GaN FETs’ technological aspects and issues are recalled and consequently linked to motion control requirements. The device’s fast switching transients combined with reduced direct resistance contribute to decreased power losses. Thus, in GaN FETs, a high switching frequency with a strong decrease in dead time is achievable. The reduced dead time impact on power loss management and improvement of output waveforms quality is analyzed and discussed in this paper. Furthermore, input filter capacitor design matters correlated with increasing switching frequency are pointed out. Finally, the voltage transients slope effect (dv/dt) is considered and correlated with low voltage motor drives requirements.
... In the inverter leg shown in Fig. 4a, the gate commands 1 , 2 are obtained by comparing the triangular carrier signal with the modulation control voltage , as reported in Fig. 4b. The dead time is necessary to avoid the cross conduction of the switching devices, but it introduces a non-linear effect that influences the output waveforms quality [14], [15]. This leads to an output phase voltage error , which can be expressed as follows [15]: ...
... These algorithms require the reconstruction of the voltage applied to the inverter, and must, therefore, consider also its non-ideal behavior to avoid introducing orientation errors [15], [17]. The non-linearity on the average voltage output waveforms related to the above mentioned dead time distortions is usually compensated implementing various open-loop and closed-loop algorithms [14], [18]- [21], which also include self-commissioning techniques to identify the magnitude of these voltage drops [16]. In this paper, a simple and straightforward open loop compensation algorithm has been considered. ...
... Those processes require a so called dead time or blanking time during which the signal to the gate of the switch is set to zero to reach the complete on or off condition. In other words the switching devices have finite turn-on and turn-off delays (Zammit et al., 2016). This is necessary because if we consider the leg of the halfbridge converter, as in this paper, if one switch has not yet completed the turn-off process and, at the same time, the other switch is turned-on then a shoot-through failure (short-circuit current through the leg) can happen damaging the converter (De Doncker et al., 2010). ...
... This is necessary because if we consider the leg of the halfbridge converter, as in this paper, if one switch has not yet completed the turn-off process and, at the same time, the other switch is turned-on then a shoot-through failure (short-circuit current through the leg) can happen damaging the converter (De Doncker et al., 2010). The dead time introduces a non-linearity which causes distortion in the output voltage and current (Zammit et al., 2016). Another example of half bridge converter implementation using Modelica is given in (Winter et al., 2015) where a DC/DC converter, extensively used in the automotive industry, is considered. ...
... With evolution and development in power electronic devices, Z-Source Inverter family has been a research hot spot since its discovery, several topologies has been discussed in [1], with their proper circuitry and boost factor capability. Also their employability has been justified in [2] with various applications such as but not limited to Photo voltaic inverter, wind energy systems, Dynamic voltage support, Distributed generations, inverter drives, uninterrupted power supplies, fuel cells etc. Their single stage DC-AC conversion capability proves its dominance over voltage source inverters as they do not need blanking time compensation which as a consequence reduces voltage stress across switches and also the harmonics due to non linearties introduced because of blanking time are avoided as explained in [3]. Also in [4] the non linearities due to blanking time or shoot through delay causes errors in estimated rotor flux position in high frequency ac drives which is inherently absent in ZSIs due to their structural X-shaped LC network advantages. ...
... These topologies have the drawbacks of limited switching frequency, high voltage stress and transformer losses. Single stage DC-AC conversion capability proves its dominance over voltage source inverters as they do not need blanking time compensation which as a consequence reduces voltage stress across switches and also the harmonics due to non linearties introduced because of blanking time are avoided as explained in [3]. Also in [4] the non linearities due to blanking time or shoot through delay causes errors in estimated rotor flux position in high frequency ac drives which is inherently absent in ZSIs due to their structural X-shaped LC network advantages [5]. ...
... The remaining difference to reach 100% is due to voltage drops on the switching devices and any discrepancies / variations in the load resistance. Other compensation techniques can be used to compensate for non-linearities created by the voltage drops on the switching devices, as those presented in [14]. ...
This paper presents the procedure to apply compensation for the distortion created by
the dead time/blanking time in H-bridge inverters, as those used in grid-connected photovoltaic
(PV) inverters. It also deals with the selection of an appropriate value of dead time, by measuring
the turn-on and turn-off times of the switching devices. Dead time/blanking time is needed in
H-bridge inverters to prevent ‘shoot through’ or cross-conduction current through the inverter leg
due to the non-ideal nature of the switching devices. The distortion effect of the dead time is
analysed by practical experimentation, showing the importance of selecting the most appropriate
value of dead time. This is then followed by a procedure to apply compensation to decrease the
distortion and thus decrease harmonics caused by the dead time. Both simulation and
experimental results will be presented. Testing was carried out on a grid-connected PV inverter
which was designed and constructed for this research.
... The remaining difference to reach 100% is due to voltage drops on the switching devices and any discrepancies/variations in the load resistance. Other compensation techniques can be used to compensate for nonlinearities created by the voltage drops on the switching devices, as those presented in Zammit et al. (2016). ...
