TMS320F28335 Digital Signal Processor Research Articles

An Improved Sensorless Control of IPMSM Based On Pulsating High-Frequency Signal Injection With Less Filtering for Rail Transit Applications

A pulsating high-frequency signal injection-based low-speed sensorless control of interior permanent magnet synchronous motor (IPMSM) using a conventional stationary reference frame low-pass filter (LPF) may experience a phase delay. Similarly, the heterodyning process may exhibit time delay and bandwidth restriction. Thus, an improved approach with a single high-pass filter in a stationary reference frame is proposed. The rotor position error is extracted from the high-frequency current using the sign of sine of the injected signal considering the phase shift. Consequently, the estimated reference frame LPF in the heterodyning process and the delay compensator for a stationary reference frame LPF-based approach are discarded. A phase-shift tracking observer (PSTO) independent of position error is included. Meanwhile, an online d-axis high-frequency current amplitude estimation is adopted to normalize the effect of d-axis inductance variation. The comparative study with a stationary reference frame LPF and the heterodyning process has shown that the proposed self-sensing strategy delivers an excellent speed sensorless control performance. Thanks to the online d-axis current amplitude estimation, the impact of d-axis inductance variation on speed-position identification has been improved. The proposed self-sensing strategy has been validated using MATLAB simulation and Hardware-in-the-loop (HIL) with TMS320F28335 digital signal processor considering rail transit applications.

DYNAMIC PERFORMANCES OF THE SHUNT ACTIVE POWER FILTER CONTROL SYSTEM

Harmonic pollution of the electrical mains is well known and well-studied phenomena. Active power filter being a powerful tool to meet the requirements of regulatory documents regulating the electricity quality. Despite this fact, practical implementation of the active power filter is still connected with significant difficulties. In particular, existing systems typically use fast Fourier transform methods or instantaneous power theory to estimate the harmonic composition of the mains current. However, the use of fast Fourier transform requires high computing power of the control system, and the implementation of the theory of instantaneous power significantly increases the requirements for the power part of the active filter. The application of another approach -selective compensation of harmonics, makes it possible to reduce computational requirements and significantly simplify the technical implementation of the active filter and at the same time to achieve an acceptable level of distortion compensation. In this paper, the shunt active power filter control system is designed and investigated. Proposed control system consist of selective harmonics observer, feedback-linearizingcurrent controller, dc-link controller and mains voltage observer. Harmonics observer is tuned according to simplified approach,provides selective estimation of the load current harmonics and produce the compensation current reference for the current controller.Nonlinear dc-link voltage controller guarantees decoupled from current compensation process asymptotic regulation of the average dc-link voltage. Mains voltage vector adaptive observer provides magnitude, angular position and frequency estimation. Proposed control system is implemented on digital signal processor TMS320F28335 end verified experimentally. Results of experimental investigations together with results of simulations confirm effectiveness of proposed solution. Developed control system can be used for shunt active filters implementation.

Model predictive control of a modified five‐level inverter with decreased device counts

SummaryIn this paper, a modified single‐phase five‐level inverter is proposed with a single DC source and six switches. Comparing with the presented converters, the proposed topology has the advantage of reduced device count and the fundamental switching frequency for high blocking voltage switches. The proposed converter implements without clamping diodes and transformers, which reducing the volume, moreover mass of the inverter. In order to achieve the optimum output voltage, the model predictive controller is proposed as a rapid dynamic and semi‐low‐computation digital control system. This closed‐loop system is implemented in TMS320f28335 digital signal processor to assess the performance of the proposed converter under nonlinear and linear loads. Analytical investigation, including simulation and an experimental result, shows compliance with IEC 62040‐3 for inverters in standalone applications.

Investigation of Regenerative Braking Performance of Brushless Direct Current Machine Drive System

The brushless direct current (BLDC) machines which are preferred in light electric vehicles (LEVs) come forward as high regenerative braking capability machines due to their permanent magnet excitation and relatively simple operation. In this paper, the regenerative braking capability limits of BLDC machines and their drive circuits are examined by taking into account nonlinear circuit parameters and battery internal resistance variation. During energy recovery from mechanical port to electrical port, the inverter of BLDC machine is operated as a boost converter which enables power flow to a battery. However, the regeneration performance is also heavily dependant on the battery condition, particularly the temperature. By means of the developed detailed circuit model including the non-ideal effects of the boosting converter and the increase of the internal resistance variation which is caused by the temperature variation of the battery and ambient temperature, the specific duty cycle can be determined. The specific duty ratio is then applied in a proposed approach for various operation scenarios. The experimental tests are implemented by a 400 W BLDC machine drive system controlled via a TMS320F28335 digital signal processor. The experimental results show that the proposed comprehensive model presents a proper performance estimation of regenerative braking system under varying battery temperature.

An Online Torque Ripple Minimization Technique for IPMSM Drives: Fuzzy System-Based d-Axis Current Design Approach

This article proposes an online torque ripple minimization (TRM) technique using a fuzzy system (FS)-based d-axis current design for interior permanent magnet synchronous motor (IPMSM) drives. Existing control-based TRM techniques generally employ optimization algorithms to design the dq-axis currents that attenuate the torque ripples. However, complex iterations applied for the optimization algorithms increase computational complexity, which limits the applicability of such TRM techniques under transient state of the IPMSM drives. Unlike with existing methods, the proposed TRM technique designs reference d-axis current using a computationally efficient algorithm and remarkably minimizes the torque ripples. Moreover, the reference d-axis current is designed online based on an FS to keep the stator current of the IPMSM inside the rated value, especially at the transient state. The proposed TRM strategy is validated through simulation and experimental investigations by using a MATLAB/Simulink software and a prototype IPMSM drive with TI TMS320F28335 digital signal processor. Comparative theoretical and experimental investigations prove that the proposed TRM technique is computationally efficient and ensures more reduced ripples in the electromagnetic torque and dq-axis currents with d-axis current significantly close to zero than conventional maximum torque per ampere based technique without TRM and conventional current control-based TRM technique under critical load conditions.

Design of an Isolated Bidirectional Symmetric Resonant Converter

An isolated type bidirectional resonant converter is presented in this paper. Using a dual active bridge as the main topology and integrating symmetric resonant mechanism, the developed converter features an isolated type bidirectional resonant converter with bidirectional power conversion and electrical isolation capabilities to ensure working security and stability. The application of a symmetric resonant scheme enables the control range of input and output voltages to be widened and achieves soft switching during bidirectional power conversion. A converter design process covering all the bases is exhibited in this work. With the digital signal processor (DSP) TMS320F28335 being employed as the control core, the developed isolated bidirectional resonant converter can effectively handle the power conversion between the simulated 400 V DC grid and the energy storage battery ranging from 280 to 403 V. Based on a 1 kW capacity design, the test data reveal that the forward conversion efficiency from grid to battery can reach 93.25%, and the reverse conversion efficiency from battery to grid is as high as 94.60%.

Design and control aspect of segmented proportional integral‐repetitive controller parameter optimization of the three‐phase boost power factor correction rectifier

SummaryThis paper presented a modeling and control aspect with an offline‐based parameter optimization algorithm for effectively tuning the controller parameters of the three‐phase boost power factor correction (PFC) rectifier system. While analyzing the shortcomings of the traditional PI control with complex control transfer functions from small‐signal models and investigating the limitations of PI control on harmonic suppression from the internal model principle, a simplified form of control transfer functions based on the small‐signal model has been proposed with segmented control action. Consequently, the methodology has the advantages of both simplified control strategies and segmented PI‐repetitive control so as to achieve the performance of high‐power factor and to reduce total harmonic distortion in a broad range of load conditions. However, the segmented PI‐repetitive control contains many control parameters. Thus, the solution and optimization for tuning the controller parameters based on heuristic offline optimization technique have been used to speed up the design of control system parameters. The validity and feasibility of the proposed design and optimization are verified using a 5‐kW three‐phase PFC rectifier with digital signal processor (DSP) TMS320F28335 prototype hardware. The results were then compared with those of traditional controller designs, which show the improvements and effectiveness of rectifier performance after adopting the proposed design and optimization technique.

Error minimization based on multi-objective finite control set model predictive control for matrix converter in DFIG

Matrix Converter (MC) has many advantages such as capability of bi-directional energy conversion, no need for DC bus and high value filters. However, modulation methods are very difficult and require high computational effort. Therefore, Multi-objective Finite Control Set Model Predictive Control (MFCS-MPC) has been implemented to simplify the complexity of this topology. However, the weakness of this control method is using mathematical model and affected by parameter mismatches due to the external disturbances, frequency and temperature variations. In this study, past errors of rotor current are added to the cost function and the weighting factors are adjusted with the Fuzzy Decision Making (FDM) approach. Due to the combination of these two methods, a robust system is obtained that can operate even in model-plant mismatch. The proposed algorithm is implemented using the TMS320F28335 Digital Signal Processor (DSP), a 32-bit floating-point processor operating at 150 MHz. Results obtained from simulation and experimental setup are compared with the current literature studies and the performance of the proposed method is confirmed.

A Power Flow Control Strategy for Hybrid Control Architecture of DC Microgrid under Unreliable Grid Connection Considering Electricity Price Constraint

This paper presents a power flow control strategy for a hybrid control architecture of the DC microgrid (DCMG) system under an unreliable grid connection considering the constraint of electricity price. To overcome the limitation of the existing schemes, a hybrid control architecture which combines the centralized control and distributed control is applied to control DCMG. By using the hybrid control approach, a more optimal and reliable DCMG system can be constructed even though a fault occurs in the grid or a central controller (CC). The power flow control strategy for the hybrid DCMG control architecture also takes the constraint of electricity price into account for the purpose of minimizing the electricity cost. In the proposed hybrid control, the high bandwidth communication (HBC) link is used in the centralized control to connect the CC with DCMG power agents. On the other hand, the low bandwidth communication (LBC) link is employed to constitute the distributed control. A small size of data is used to exchange the information fast between the agents and CC, or between each agent and its neighbors, which increases the reliability and robustness of the DCMG system in case of a fault in the communication link of the centralized control. A DCMG system with 400-V rated DC-link voltage which consists of a wind power agent, a battery agent, a grid agent, a load agent, and a CC is constructed in this study by using three power converters based on 32-bit floating point digital signal processor (DSP) TMS320F28335 controller. Various simulation and experimental results prove that the proposed scheme improves the system stability and robustness even in the presence of a fault in the communication link of the centralized control. In addition, the proposed scheme is capable of maintaining the DC-link voltage stably at the nominal value without severe transients both in the centralized control and distributed control, as well as both in the grid-connected case and islanded case. Finally, the scalability of the DCMG system is tested by adding and removing additional wind power agent and battery agent during a certain period.

A New Carrier-Based Pulse Width Modulation Scheme with Reduced Output Voltage Total Harmonic Distortion for Multi-Level Inverters

This paper proposes a novel Pulse Width Modulation (PWM) switching technique based on Optimized Carrier Peaks-PWM (OCP-PWM) which can be used to control both single phase and three-phase multilevel inverters. The proposed PWM scheme is designed according to multi-peak selection on carriers a way to define the optimum values for carrier peaks and then minimizing the output voltage Total Harmonic Distortion (), switching frequency (f s), and also switching losses, in comparing with the other carrier-based PWM methods. To examine the performance of the presented PWM scheme, a five-level converter has been employed including six power MOSFETs to produce five level in the output. In comparison with typical PWM switching methods for single-phase inverters, the presented PWM scheme produces low harmonic components in the output voltage. To investigate the reliability of the presented PWM scheme for single-phase five-level converters a 2.5kVA/400 V prototype is carried out by applying a TMS320F28335 digital signal processor.

LMC-based DTC for efficiency improvement of IM drives and their electric vehicle applications

Electric vehicles (EVs) with induction motor (IM) drives require energy optimization due to their limited energy storage capacity. Among the energy optimization methods currently available, a loss model-based controller (LMC) is a satisfactory technique, since it converges rapidly to an optimal operating point. Some of the simplifications applied to LMCs, such as neglecting the core loss and leakage inductances, affect IM drive performance negatively in terms of loss minimization. To overcome this problem, this paper presents an efficient LMC combined with direct torque control (DTC). The proposed method is based on the idea that the magnetizing current is much higher than the core loss current. Using the sum of the stator current and the rotor current instead of the magnetizing current, modelling the losses is simplified and the optimal stator flux is determined easily. A simulation study is carried out to evaluate the performance of the proposed scheme with an EV application during an FTP-75 urban driving cycle. A prototype 3 kW IM drive with a TMS320F28335 digital signal processor (DSP) is built to validate the simulation results. A significant efficiency improvement is obtained at low loads. Both simulation and experimental results demonstrate that the proposed DTC improves efficiency and decreases torque ripple.

Control Implementation of Squirrel Cage Induction Generator based Wind Energy Conversion System</p>

Trends towards PC-based computing platforms have given a path to innovate advanced, model-based control algorithms for the control of wind energy conversion systems. These advanced models allow us to gain increased reliability and improved efficiency. This work is focused on the digital signal processor based implementation aspects of a variable speed, grid connected; squirrel cage induction generator based wind energy conversion systems. Control design using a voltage source converter at the machine side have been described, designed, modeled and analyzed. A comprehensive analysis of the designed system is performed in terms of the active power harnessed, power quality and reactive power control. Optimal power point operation has been implemented so that highest available power is harnessed for varying wind velocities. A 2.2kW prototype with back to back connected voltage source converter has been implemented in hardware using TMS320F2812 digital signal processor. The experimental results illustrate the excellent performance of the system.

Cloud Computing and Local Chip-Based Dynamic Economic Dispatch for Microgrids

Dynamic economic dispatch in microgrids is usually realized in a centralized energy management system (EMS). However, centralized systems are subject to single-point failure problems. In rural areas and islands, a failed EMS cannot be recovered in a timely manner due to lack of technical support. In this paper, we propose a cloud and edge computing-based framework to realize dynamic economic dispatch, which is conducted on a local Digital Signal Processor (DSP) chip and a remote cloud computing platform (CCP). Based on the multi-parametric programming algorithm, the dispatch process is divided into two parts: offline calculation and real-time decision making. These calculation tasks can be conducted on the remote cloud computing platform and the DSP chip of the inverter in an arbitrary renewable generator, respectively. The tests are carried out on the Amazon Web Service (AWS) EC2 instance and an autonomous microgrid with DSP TMS320F28335 chip. The results show that the proposed method can obtain the same results as the conventional method, with significantly improved reliability.

DSP‐based comparison of PFC control techniques applied on bridgeless converter

A comparison of fuzzy self-tuning (FST), sliding mode control (SMC) and conventional proportional-integral (PI) control methods is performed under unbalanced grid conditions using a bridgeless power factor correction (PFC) converter. The bridgeless PFC converter operates the correction of AC line current to obtain a DC output voltage without full bridge rectifier based on these control methods. These control methods generate the duty cycles to provide higher unity power factor and lower total harmonic distortion of input current, even if AC line voltage is distorted. This study focuses on the performance analysis of FST and SMC methods adaptation to the input current for the bridgeless PFC converter and comparing with the conventional PI controller. Although the SMC method is only used in the current control loop, the FST method is used in both current and voltage control loops for eliminating harmonics of input current and regulating of output voltage. The performance of control methods is evaluated with a TMS320F2812 digital signal processor. The simulation and experimental results are compatible with the limits for harmonic current emissions, IEC 61000-3-2 and show that the FST and SMC are better than the conventional PI control method and FST is superior to the SMC.

DSP in the Loop Implementation of Sliding Mode and Super Twisting Sliding Mode Controllers Combined with an Extended Kalman Observer for Wind Energy System Involving a DFIG

This paper presents the conception and the implementation of a robust non-linear control technique on a TMS320F28335 Digital Signal Processor as Hardware in the Loop (HIL). The control law is a sliding mode controller (SMC), synthesized in order to optimize, via back-to-back power converters, the output power of a grid-connected doubly fed induction generator. Besides, the Maximum Power Point Tracking strategy to extract the optimal electromagnetic torque is designed by combining an extended Kalman observer, in order to estimate the mechanical torque, and a super twisting sliding mode controller (STSMC). The performance of the proposed strategy is compared to the one of the conventional Proportional-Integral (PI) controller under the same scenario. The results of the DSP in the Loop implementation present the best performances in terms of setpoint tracking, speed response, and robustness concerning sudden variations in the generator parameters.

New control method for VSC-MTDC stations in the abnormal conditions of power system

Low complexity, insensitivity on the system parameters, lesser number of electrical sensors, fast and accurate dynamic response, the ability of connection to weak AC system and high power quality are some of the major criterions for selection of control method of the voltage source converters (VSC). Considering these issues, in this paper, a new control method is presented for application in the VSC stations. This control method is based on recursive least squares with variable forgetting factor (VFF-RLS) which is a numerical estimator. Estimation of fundamental components of distorted AC grid voltage and their symmetric positive components are done by VFF-RLS estimators. Desired power injection by the proposed control method is done with corresponding to estimated signals. Simulation results in the MATLAB/SIMULINK platform and experimental results using TMS320F2812 digital signal processor validate the superiority of the proposed control method.

Improved Iterative Learning Control Strategy for Surface-Mounted Permanent Magnet Synchronous Motor Drives

In this article, an improved iterative learning control (ILC), which significantly enhances the speed tracking performance in the transient and steady state for a surface-mounted permanent magnet synchronous motor (SPMSM) drive, is proposed. The proposed ILC encapsulates two control terms: the feedback linearization control terms force the speed error to approach zero, and the iterative learning control terms (ILCTs) improve the performance of the control inputs based on the stored data such as previous speed error and previous control input. Unlike the conventional feedback linearization control (FLC), the proposed ILC does not require the exact information of the SPMSM parameters, significantly rejects the periodic and nonperiodic disturbances, and efficiently provides an enhanced speed tracking performance owing to the included ILCTs. Besides, its stability is proven by showing that the speed tracking error asymptotically goes to zero. In comparative studies, the proposed method offers the better transient performance (e.g., faster transient response and smaller overshoot) and steady-state performance (i.e., smaller steady-state error) than the conventional FLC under load and speed step changes. To prove the practicability of the proposed scheme, the proposed ILC is simulated and implemented on a MATLAB/Simulink software and a prototype SPMSM test-bed using TI TMS320F28335 digital signal processor, respectively.

Evaluation of Predictive Current Control Techniques for PM BLDC Motor in Stationary Plane

In general, PM BLDC motors are injected with square wave phase currents through PI-PWM control in a-b-c reference plane to ensure maximum torque-per-ampere. The operation of PM BLDC motor in a stationary plane has shown considerable simplification in design, and analysis in the control techniques. The present paper considers the injection of square wave phase current through predictive current control strategies in the stationary plane. For the evaluation of performance, cases of deadbeat predictive control, hysteresis based predictive control, and finite control-set model predictive control (FCS-MPC) methods are considered. Control schemes have been designed for 48V, 660W PM BLDC motor. Comparative evaluation is carried out in terms of the harmonic components available in the current and torque, tracking of the current trajectory in the stationary plane in the low and high-speed region, and execution time of all the control methods. Considered predictive methods are tested on an experimental prototype, and control is implemented through digital Signal Processor (DSP) TMS320F28335. Evaluation leads to the conclusion that predictive control performs better than PI-PWM for reducing commutation torque ripple, keeping current harmonics under control. It is observed that predictive control strategies in the stationary plane, improve the torque-speed characteristic to the wider utilization of constant torque zone of operation as compared to conventional strategies.

Improved Torque Ripple Minimization Technique With Enhanced Efficiency for Surface- Mounted PMSM Drives

This paper proposes an improved torque ripple minimization (TRM) method using model-based loss minimization (LM) control to reduce the torque ripples and enhance the efficiency for surface-mounted permanent magnet synchronous motor (SPMSM) drives. The conventional SPMSM drives usually achieve the maximum torque per ampere (MTPA) control by applying the zero d-axis current (ZDC) and ignore an actual core loss resistance in the controller design. Unlike the conventional MTPA method, the proposed TRM selects the appropriate d-axis current value by making the derivative of the electromagnetic torque equal to zero in the SPMSM drives. Consequently, the proposed method can improve the torque ripples and efficiency compared to the conventional MTPA. Using the proportional-integral (PI) controllers, comparative experimental verifications between the proposed model-based TRM, the conventional model-based MTPA, and the conventional model-based LM are performed through a prototype SPMSM drive with a TI TMS320F28335 digital signal processor (DSP).

Disturbance Attenuation for Surface-Mounted PMSM Drives Using Nonlinear Disturbance Observer-Based Sliding Mode Control

This paper proposes a nonlinear disturbance observer (NDO)-based sliding mode speed controller (SMSC) to guarantee the superior control performance in terms of robustness, fast transient response, and small steady-state error for a surface-mounted permanent magnet synchronous motor (SPMSM) drive. Generally, the control performance of the SPMSM drives can be degraded by disturbances, so an NDO with a proper disturbance rejection capability is proposed to appropriately improve the tracking performance of the SMSC designed for the SPMSM drives. Unlike the linear disturbance observers (LDOs), the proposed NDO can efficiently estimate the lumped disturbance such as uncertainties parameters and unmodeled dynamics by using the nonlinear design function. The proposed NDO rejects the complex disturbances as well as self-regulates the observer gains to increase the convergence rate. The feasibility of the proposed NDO-based SMSC is verified by using a MATLAB/Simulink software program and a prototype SPMSM drive system with a TI TMS320F28335 digital signal processor (DSP). The comparative results with a conventional LDO-based SMSC are analyzed under load torque disturbances and model uncertainties to prove the excellent performance of the proposed NDO-based SMSC.