Injection Pulse Width Research Articles

Correction strategy of fuel injection quantity during pilot-main injection for common rail system

Common rail system is a key technology of energy saving and emission reduction for modern diesel engines. Multiple injection, as one of the most interesting features of common rail system, allows both optimal fuel consumption and exhaust emissions. In order to explore the method for controlling the fluctuation of fuel injection quantity during multiple injection, experiments have been carried out in this paper, focusing on pilot-main injection. The high pressure fuel circuits of the system have been equivalent to a spring-mass vibration system. Comparison with the experiment shows that the proposed fluctuation equation can reasonably predict the fluctuation characteristics of main injection quantity with pilot-main injection interval. The correction control strategy for the main injection quantity fluctuation has been proposed, in which the relative damping coefficient, rail pressure, pilot-main injection interval and main injection pulse width are chosen as the input variables. The experimental results with different rail pressure and main injection quantity show that the fluctuation of injection quantity during pilot-main injection can be controlled effectively by the proposed correction strategy. The maximum average fluctuation of main injection quantity decreases by as much as 44.66 %.

Fischer-Tropsch coal-to-liquid fuel negative temperature coefficient region (NTC) and low-temperature heat release (LTHR) in a constant volume combustion chamber (CVCC)

The purpose of the study was to investigate the correlation between thermal characteristics of neat Iso-Paraffinic Kerosene (IPK) in relation to Low Temperature Heat Release (LTHR), ignition delay, and combustion delay within the Negative Temperature Coefficient region (NTC), utilizing a Box-Behnken design matrix. There were 15 trials of 3 control input parameters which were strategic manipulations of ASTM standard D7668-14a. The standard parameters are: 1000 bar for injection pressure, a combustion chamber temperature of 595.5 °C, and an injection pulse width of 2.5 ms. It was observed that, at ASTM standard, the Derived Cetane Number of neat Ultra-Low Sulfur Diesel (ULSD) and IPK was 47.38 and 25.9, respectively. Results show that the LTHR duration and energy release were reduced when two parameters were simultaneously increased in ULSD operation. Meanwhile, for both fuels, the duration and energy release in LTHR has increased when two parameters were simultaneously reduced. It was found that the lower set wall temperature resulted in increased NTC region and LTHR increased to over 10% of the total energy release. The maximum combustion pressure for both ULSD and IPK where increased by 17.2% and 16.1% respectively from the standard due to the increase in injection pressure and pulse width.

Third harmonic injection pulse-width modulation technique for a five-phase voltage source inverter

<span>Nowadays application of advanced power electronic technology enables producing an AC supply with a phase number higher than three-phase. Five-phase voltage source inverters (5ph-VSI) have been used in advanced power electronic drives to improve the reliability of the drive system and to boost the power capability of the converter as well as to their other inherent merits. This paper shows the mathematical analysis and simulation of the third harmonic injection pulse width modulation (THI-PWM) 5ph-VSI connected with inductive load in three scenarios i.e. star, Pentagon and pentacle. The presented THI-PWM technique for 5ph-VSI aims to increase the inverter fundamental voltage and hence to maximize the utilization of the DC bus without causing over-modulation. The simulation results are compared with typical sinusoidal pulse width modulation (SPWM) and the 10-step mode operation. The proposed scheme may be considered as a compromise case between the two reference cases; as low harmonic components compared with 10-step mode operation and a high utilization factor compared with SPWM.</span>

Enhancing the Performance of Multilevel Inverters using Modified SVPWM Techniques

In this paper, two types seven-level multilevel inverters in three phase configuration, Cascaded H-bridge Multilevel Inverter (CMLI) and Diode Clamped Multilevel Inverter (DCMLI) are simulated and compared the results for three different carrier PWM techniques. Here, Carrier based Sinusoidal Pulse Width Modulation (SPWM), Third Harmonic Injected Pulse Width Modulation (THIPWM) and Modified Carrier-Based Space Vector Pulse Width Modulation (SVPWM) are used as modulation strategies. These modulation strategies include Phase Disposition technique (PD), Phase Opposition Disposition technique (POD), and Alternate Phase Opposition Disposition technique (APOD). In all the modulation strategies, triangular carrier and trapezoidal triangular carrier signals are compared with reference signal for generation of control pulses. The simulations have been carried out for seven-level CMLI and DCMLI using MATLAB/Simulink. The detailed analysis of results in terms of %THD and utilization of DC-link voltage has been presented in this paper. By increasing the performance of inverters the utilization of input energy is reduced, then the corresponding energy sources can be reduced.

Operation of grid‐connected DFIG using SPWM‐ and THIPWM‐based diode‐clamped multilevel inverters

This paper proposes a WECS based on a back to back diode-clamped multilevel inverter systems (DCMLI) fired comparatively by sinusoidal pulse width modulation (SPWM) and third harmonic injection pulse width modulation (THIPWM) techniques. DFIG performance is compared using these technologies for different wind speed under normal operation condition. The proposed approach shows that the DCMLI systems generate a nearly sinusoidal voltage with reduced total harmonic distortion (THD) thus upgrading the power quality of that produced by DFIG. As SPWM and THIPWM MLI are most common usage techniques in research, we applied them in the system to discuss a comparison of using those techniques to determine the number of levels that achieve the IEEE 519 criteria of THD which is less than 5% for both techniques (5th level for SPWM and 4th level for THIPWM) in all operation wind speed. Compared with simple PWM, and THIPWM have many advantages as lower THD, minimal number of switching to decrease switching losses and the output fundamental voltage is increased. Lastly, the paper investigates the variation of the frequency of induced rotor voltage and the active power flow due to the wind speed change when the rotor speed changes from super-synchronous to sub-synchronous speeds.

Impact of injector tip deposits on gasoline direct injection engine combustion, fuel economy and emissions

Gasoline direct injection (GDI) engine development is facing the great challenges in both fuel economy and particulate emissions. Trade-off is often required in GDI engines to sacrifice fuel economy in order to meet the strict emission regulations. GDI injector deposits have been identified as a potential cause of increased particulate emissions. In this work, a series of experimental tests was conducted on a 1.5 L turbocharged GDI engine to further understand the effect of injector deposits. The deposits formed on the injector tip surface were removed after the 55-hour fouling test and their effects on fuel consumption, in-cylinder combustion, thermal efficiency and engine out emissions were investigated before and after the removal. The spray characteristics of an identical injector under clean and fouled conditions were examined and the deposits inside the injector nozzle holes were observed by a scanning electron microscope. The test injectors were mildly fouled with an average of 1.5% flow rate loss and 1.84% injection pulse width increase. After removing the injector tip surface deposits, the engine combustion phase became advanced and the peak in-cylinder pressure increased. The combustion efficiency was close to 98% and showed no significant change. Although the indicated thermal efficiency was only slightly improved by 0.31–0.44% after removing the tip surface deposits, the particulate emissions were significantly affected and reduced by up to around 45%. At the meantime, NOx emissions moderately increased by approximately 12% after removal and no significant change occurred in the THC and CO emissions.

Comparative Study on Performance Improvement of SPWM/THIPWM based DCMLI Grid Connected DFIG

Multi-level voltage source converter is integrated in various fields in renewable energy power generation technologies such as wind and solar sources for applications that need higher voltage and higher power. In wind power generation market, doubly fed induction generator (DFIG) based on wind power generation is now the leading technology as they are economically feasible, they do offer a variable speed and efficient substitute to the fossil fuel. This paper proposes a DFIG based on a back to back diode clamped multilevel converter systems (DCMLI) fired comparatively by sinusoidal pulse width modulation (SPWM) and third harmonic injection pulse width modulation (THIPWM) techniques. By using these technologies, the DFIG performance is compared for different wind speeds under normal operation condition. The proposed approach shows that the DCMLI systems generate a near sinusoidal voltage with lower values in total harmonic distortion (THD) thus, upgrading the power quality that is produced by DFIG. Lastly, the variation of frequency of induced rotor voltage and the active power flow due to the wind speed changes when the rotor speed changes from super synchronous to sub synchronous speeds is investigated.

Reliability-Oriented Selection for Grid-Connected Converters: A Low Voltage Direct Current Microgrid Case Study

As the grid-connected AC-DC converter is the key equipment that links the low voltage direct current (LVDC) microgrids and the utility grid, the safe and stable operation of the converter is of great significance to improve the reliability of the LVDC microgirds. Since the converter's reliability is affected by the converter's topological structure and modulation strategy, a civil LVDC microgrid case study is analyzed, and the power losses, thermal stresses, lifetimes and reliability of components in the AC-DC converters with different topologies and modulation strategies are evaluated in this paper. The influence of these two factors on the reliability and efficiency of the converter is discussed, and the normalized weighted total harmonic distortion (NWTHD) with different modulation strategies is analytically determined and compared. The results show that when the converter operates with unity power factor in this application scenario, among the two-level converter, flying capacitor converter, neutral point clamped (NPC) converter and T-type converter, the T-type converter has the highest reliability. The effects of the converter's topology and modulation strategy on the capacitor reliability are relatively small. In view of reliability and power quality, third harmonic injection pulse width modulation (THIPWM) or space vector pulse width modulation (SVPWM) is more suitable for the converter in this microgrid.

Reduction of Total Harmonic Distortion in Nine Phase Induction Motor Drive with Third Harmonic Injection Pulse Width Modulation Technique

Industrial applications demands high torque and long life span motor drives. Three phase motor drives have limited torque density hence Multiphase motor drives are better solutions for high torque density and heavy loads. In this work a Nine Phase Inverter is designed to drive Nine Phase load. The loads used in the industries almost nonlinear loads like motors. Therefore,due to these nonlinear loads additional harmonics induced at the output of the nine phase Inverter Drive with fundamental frequency. These harmonics are higher than fundamental frequencies and cause Total Harmonics Distortion(THD) which increases the rms current and generates more heat in the load.Many techniques are used to suppress the harmonics to minimize the heat in the load. A new technique is employed in this work to minimize THD by constructing THIPWM (Third Harmonics Injection Pulse Width Modulation) technique to overcome the low performance of a conventional PWM (pulse width modulation) control. In this work, the desired output voltage is achieved by comparing the desired sinusoidal waveform (modulating signal) with a high frequency triangular waveform (carrier signal). The harmonics and THD obtained using PWM and THIPWM is compared using Matlab/Simulink

Investigation on the fuel injection stability of high pressure common rail system for diesel engines

High pressure common rail system is the state-of-the art technology for modern diesel engines to achieve energy conservation and emission reduction. The economy and emission performance of the diesel engines are influenced by the fuel injection stability of the high pressure common rail system. In this work, a high pressure common rail injector numerical model based on bond graph theory has been proposed. The comparisons between experimental results and numerical simulations show that the numerical model could reasonably predict the injection characteristics of the system. In order to reveal the essential rules and inherent characteristics of the fuel injection stability for high pressure common rail system, the rank variations of the state matrix at different injection pulse widths during fuel injection are obtained by means of a linear analysis. In addition, the distributions of eigenvalues for the state matrix in complex plane are investigated using Lyapunov method. The results show that the rank is influenced mainly by the movements of control valve and needle. Furthermore, the variation rule of the rank is independent of the injection pulse width before the needle is opened. The needle channel orifice of the injector plays a dominant role in transformation of the system from strong damping oscillation to underdamping oscillation. The opening and closing of control valve have significant effect on the stability of the system because its movement breaks the stability, and the movement of needle has remarkable effect on the oscillating characteristics of the system. High pressure common rail system is a complicated time-variant system with unstable pressure relief and strong oscillation injection.

Development and utilization of experimental device for gasoline engine fuel adjustment characteristics

The fuel injection pulse of the electronically controlled injection gasoline engine is fully solidified in the ECU. In addition, the engine injection control uses negative feedback control. It is difficult to control the injection quantity of the engine without an external electronically controlled development system.Therefore, universities that do not have the ability to develop electronically controlled ECU have stopped or canceled gasoline fuel adjustment characteristics tests. In view of the current problem, based on the STM32 library function, this study developed an experimental device, which can docking well with the engine in use, and can easily input the injection pulse width without changing the original ECU of the engine, thereby controlling the mixture concentration of the engine and completing the fuel adjustment characteristic experiment easily. The fuel adjustment characteristics experiment was completed on the engine test bench, which verified that the developed experimental device has good practicality.

Study of Fuel-Controlled Aircraft Engine for Fuel-Powered Unmanned Aerial Vehicle: Energy Conversion Analysis and Optimization

Recently, the cruising duration is a vital parameter of fuel-powered unmanned aerial vehicles (UAVs), and it is directly determined by the power characteristics of the aircraft engine in the UAV. In this study, to prolong the flight duration and enhance the power and efficiency of a UAV, an aircraft engine is analyzed based on the fuel injection control system and output power characteristics. First, the mathematical model of a fuel-controlled engine is constructed. In addition, the experimental stations of the aircraft engine are set up to verify the mathematical model. Furthermore, the effects of key parameters on the engine power characteristics are examined. By the experimental and simulation studies validity of the mathematical model is effectively verified which indicates that the increased rotating speed decreases the power efficiency of the aircraft engine, and reducing the fuel injection pulse width from 5 ms to 3.5 ms increases the power efficiency by 10%. Moreover, increasing the advance angle of ignition from 10° to 40° improves the power efficiency by 5%. In addition, when the fuel injection delay width increases from 0.5 mm to 1.5 mm at an engine speed between 3500 rpm and 4000 rpm, the power efficiency is improved by 6%. Finally, when the engine speed is higher than 4000 rpm, increasing the propeller rotor diameter from 650 mm to 800 mm enhances the power efficiency of the aircraft engine by approximately 5%. This research can be considered as the fuel injection system optimization and cruising duration improvement of a fuel-powered UAV.

Single-Phase Bridgeless Rectifier Based System With Enhanced Capability of Reactive Power Compensation

Aiming at enhancing reactive power compensation (RPC) capability of the traditional single-phase bridgeless rectifier, a 2.5kVA circuit topology composed of a single-phase bridgeless rectifier and a third-order tuned LC series branch in parallel connection is proposed. The corresponding control strategy using the third harmonic injection pulse width modulation (THIPWM) technique is also presented, which enables the proposed single-phase bridgeless rectifier to operate under varied power factor with the near-sinusoidal current at the point of common coupling (PCC). The principle of the proposed topology is discussed in detail and reactive power compensation capability of the proposed single-phase bridgeless rectifier under a certain amount of active power to be transmitted to the load is studied. Simulation and experiment results are given to validate the feasibility of the proposed circuit topology and the correctness of the theoretical analysis.

The Investigation of Geometric Parameters on the Injection Characteristic of the High Pressure Common-Rail Injector

According the actual structure and working principle of a fuel injector to build a model of the common-rail injector, including the control valve, the solenoid valve, and the needle valve of the injector. The model includes the leakage model for the control piston and needle valve that takes into account increasing leakage at high pressure. The performance of the fuel injector is investigated using a one-dimensional numerical model. Analyzing the effect of the system and structure parameters including common-rail pressure, injection pulse width, inlet and outlet hole diameter, and the injection nozzle on the injection characteristics of the fuel injector. Results show that the geometric parameter is the main property affecting the flow characteristic of the injector, which includes the flow rate of inlet and outlet hole, pressure waves in the control chamber and injection rate. The common-rail pressure, injection pulse width and the geometric parameters mainly affect the injection performance, such as the injection rate and injected volume. The investigation result can provide some useful information to improve the injection characteristic in follow-up studies.

Effect of split injection on particle number (PN) emissions in GDI engine at fast-idle through integrated analysis of optics and mechanics

To reduce toxic engine emissions and meet the strict regulations, split injection has been adopted to optimize engine performance and fast-idle has been selected as the researching condition. Two sets of experiments have been conducted to investigate the effect of split injection on particulate number (PN) emissions at fast-idle. The first set is conducted in a constant volume vessel to get detailed spray characteristics, while the second is conducted in engine bench analyzing the effect of split injection on real engine PN emissions. Establishing direct connection from spray characteristics and real engine PN emissions is the main objective of this paper. Higher ambient temperature can reduce spray angle, while spray tip penetration is insensitive to experimental parameters. Long injection pulse width combined with short height of damper (HOD) will increase the possibility to impingement. Total PN concentration of four injection modes all decreases at first and then increases with increasing coolant temperature, and split injection can obviously reduce total PN to 50% from single injection. With increasing coolant temperature, accumulation mode particles all decrease while nucleation mode particles show different trends under four injection modes. In addition, the last injection within split injection has obvious influence on PN emissions.

An improved harmonic injection PWM-frequency modulated triangular carrier method with multiobjective optimizations for inverters

This paper proposes a new optimized switching method to improve the output voltage quality of the inverter. This proposed method has called Improved Harmonic Injection Pulse Width Modulation-Frequency Modulated Triangular Carrier (IHIPWM-FMTC). The purpose of this study is to describe the features of the line-to-line output voltage in a three-phase three-level inverter. Some controllable parameters in both the reference and carrier waves are defined to improve the output voltage characteristics such as THD, LOH, and DF. To obtain better results, multiobjective optimizations are used. These algorithms lead to more controllability and conclude multiple responses with different properties. Optimizations are performed by four useful intelligent algorithms. The simulation results of the proposed method were compared with SPWM and the conventional HIPWM-FMTC methods in the output voltage characteristics, rotor speed, and torque ripple. The optimization results determine the desired magnitude of the reference and carrier wave parameters. Finally, the practicality of switching method was experimentally validated.

Implementation and performance analysis of cascaded multilevel inverter using modified SVPWM techniques

The space vector pulse width modulation (SVPWM), which is considered as an efficient PWM technology can also be used for multilevel inverters. This method is originally designed for two-level inverters. This paper introduces a modified SVPWM technique. The cascaded H-bridge multilevel inverter (CMLI) of 7-level, 9-level and 11-level are simulated for three different carrier PWM techniques. Here, carrier-based sinusoidal pulse width modulation (SPWM), third harmonic injected pulse width modulation (THIPWM), and modified carrier-based SVPWM are used as modulation strategies. These modulation strategies include phase disposition technique (PD), phase opposition disposition technique (POD), Alternate Phase Opposition Disposition technique (APOD), and Phase Shifted Carrier (PSC). These strategies have been implemented by using simulation and validated by experiment. The detailed examination of the simulation results has been presented and validated with experimental results of 11-level CMLI.

Implementation and performance analysis of cascaded multilevel inverter using modified SVPWM techniques

The space vector pulse width modulation (SVPWM), which is considered as an efficient PWM technology can also be used for multilevel inverters. This method is originally designed for two-level inverters. This paper introduces a modified SVPWM technique. The cascaded H-bridge multilevel inverter (CMLI) of 7-level, 9-level and 11-level are simulated for three different carrier PWM techniques. Here, carrier-based sinusoidal pulse width modulation (SPWM), third harmonic injected pulse width modulation (THIPWM), and modified carrier-based SVPWM are used as modulation strategies. These modulation strategies include phase disposition technique (PD), phase opposition disposition technique (POD), Alternate Phase Opposition Disposition technique (APOD), and Phase Shifted Carrier (PSC). These strategies have been implemented by using simulation and validated by experiment. The detailed examination of the simulation results has been presented and validated with experimental results of 11-level CMLI.

Design and Performance Analysis of 7-Level Diode Clamped Multilevel Inverter Using Modified Space Vector Pulse Width Modulation Techniques

In this paper, a 7-level Diode Clamped Multilevel Inverter (DCMLI) is simulated with three different carrier PWM techniques. Here, Carrier based Sinusoidal Pulse Width Modulation (SPWM), Third Harmonic Injected Pulse Width Modulation (THIPWM) and Modified Carrier-Based Space Vector Pulse Width Modulation (SVPWM) are used as modulation strategies. These modulation strategies include Phase Disposition technique (PD), Phase Opposition Disposition technique (POD), and Alternate Phase Opposition Disposition technique (APOD). In all the modulation strategies, triangular carrier and trapezoidal triangular carrier signals are compared with reference signal, then control pulses are generated. The detailed analysis of the results has been presented and compared with experimental results in terms of fundamental component of output voltage and percent of THD.

A Third Harmonic Injected PWM Scheme with Partial Feedback Linearizing Controller for Grid-Connected Ultracapacitor System

In this paper, a high-efficiency third harmonic injected pulse width modulation (PWM) scheme is presented for an ultracapacitor-based energy storage system (UCESS). Also, a nonlinear partial feedback linearizing controller is used with the proposed third harmonic injected PWM scheme where the main control objectives are to regulate the active and reactive power injection into the grid from the UCESS. The dynamical model of the grid-connected UCESS is developed from the electrical equivalent circuit, where the grid connection is accomplished through a three-phase voltage source converter (VSC). The grid current components corresponding to both active and reactive power are regulated through the proposed control action. Since the proposed control scheme reduces the order of the original UCESS, the stability of remaining dynamics (i.e., internal dynamics) is investigated before implementing the proposed controller. The implementation of the proposed control scheme also requires the injection of the third harmonic externally as the incorporation of this harmonic during the modeling does not affect the transient and steady-state characteristics of the system. A test distribution system is considered to justify the performance of the proposed scheme through the simulation results. The simulation results show the superiority of the proposed controller as compared to a finely-tuned proportion integral (PI) controller.