Digital Signal Controllers Research Articles

Real-Time Filtering and ECG Signal Processing Based on Dual-Core Digital Signal Controller System

ECG devices are increasingly used in the monitoring and timely detection of cardiovascular abnormalities. One of the biggest challenges for ECG device designers is to eliminate noise from the surrounding environment to obtain high-quality and real-time ECG signals. A microcontroller usually has low processing speed, so it is not appropriate for real-time processing of ECG signals with high sampling frequency. Processing continuous signals requires a high processing speed or processor that can be used with many partial processing hierarchies. In 2018, Microchip Technology Inc. launched a new family of 16-bit digital signal controllers (DSCs) with two cores: the master core can be operated at 180 MHz and the slave core can be operated at 200 MHz. The new DSC family is suitable for mobile application systems, such as ECG devices, which can collect and process data in real time with a process hierarchy. In this paper, we present an application of the two cores of DSCs in collecting and processing ECG signals in real time. In addition, we implement an infinite impulse response (IIR) filter to eliminate noise from the surrounding environment. Specifically, the master core collects and implements a high-pass IIR filter with five poles, and the slave core implements the low-pass IIR filter with seven poles and sampling frequency of ECG signals up to 400 Hz.

Low-cost didactic platform for real-time adaptive filtering: Application on noise cancellation

Didactic platforms, used in real-time digital signal processing courses, are generally dedicated digital signal processors or field-programmable gate arrays. These devices are expensive and difficult to program, preventing their widespread use in signal processing courses. On the other hand, the new technology of digital signal controllers, microcontrollers with floating point and mathematical operations, can reduce the cost of dedicated platforms for real-time digital signal processors, facilitating the development of digital signal processors projects and educational applications, such as teaching adaptive filters. Here, we present a low-cost didactic platform for developing real-time adaptive filters using the digital signal processors hardware based on the ARM Cortex-M7 processor. We present the theoretical aspects of the least mean squares and normalized least mean squares algorithms and an experimental script to help students learn real-time adaptive filters. We also describe the platform structure and the performance measurement, in terms of mean square error, signal-to-noise ratio, and computational efficiency. Finally, we present a brief discussion on the use of this platform in classes and the improvement in the student engagement and attendance.

Electric vehicle technology impacts on energy

The CO<sub>2</sub> emission level is becoming a serious issue worldwide. The continuous increase in gasoline price forms the essential base of development of electric vehicle (EV) drives. Moreover, economic and environmental issues relate to fabrication and operation of traditional powered vehicles. The basic considerations and development perspectives of EVs are presented in this paper. The development of an efficiently designed motor and drive satisfy the need of efficient characteristics that enable EVs to perform as part of the propulsion unit. The use of digital signal controllers compared with conventional control systems minimizes the motor’s total harmonic distortion, lowers operating temperatures, and produces high efficiency and power factor ratings. This paper addresses the view of EV technology as well its advantages over other technologies.

DSCBlocks: An Open-Source Platform for Learning Embedded Systems Based on Algorithm Visualizations and Digital Signal Controllers

DSCBlocks is an open-source platform in hardware and software developed in JavaFX, which is focused on learning embedded systems through Digital Signal Controllers (DSCs). These devices are employed in industrial and educational sectors due to their robustness, number of peripherals, processing speed, scalability and versatility. The platform uses graphical blocks designed in Google’s tool Blockly that can be used to build different Algorithm Visualizations (AVs). Afterwards, the algorithms are converted in real-time to C language, according to the specifications of the compiler for the DSCs (XC16) and they can be downloaded in one of the two models of development board for the dsPIC 33FJ128GP804 and dsPIC 33FJ128MC802. The main aim of the platform is to provide a flexible environment, drawing on the educational advantages of the AVs with different aspects concerning the embedded systems, such as declaration of variables and functions, configuration of ports and peripherals, handling of Real-Time Operating System (RTOS), interrupts, among others, that are employed in several fields such as robotics, control, instrumentation, etc. In addition, some experiments that were designed in the platform are presented in the manuscript. The educational methodology and the assessment provided by the students (n = 30) suggest that the platform is suitable and reliable to learn concepts relating to embedded systems.

Real-time control in single-phase power inverters

The analysis of usability of selected digital signal controllers (DSC) in off-grid power inverters is presented in this paper. The digital signal controller’s task was to control the H-bridge through dedicated driver for power MosFET transistors and measurement of higher harmonics. NexFET power transistors with small channel resistance and small FOM coefficient were used for this purpose. Regular modulation with symmetrical triangle carrier signal was used as a modulation method. The main aim was to show the capabilities of Delfino digital signal controllers in real-time control of the power inverter and analysis of the possible implementations of voltage and harmonic measurements. These measurements can be used for regulation of the output voltage and reduction of the total harmonic distortion.

A portable embedded system for point-to-point secure signals transmission

In this work, an embedded system for point- to-point secure transmission of encrypted signals was developed. This portable system, which is also experimentally analyzed includes, includes a pair of digital signal controllers dsPIC33FJ128MC802 and the algorithm is based on the Rössler oscillator with constant and chaotic parameters. Therefore, the synchronization between both devices was analyzed via the measurement of the synchronization error and the transient time. The viability of the complete system was experimentally studied, by sending encrypted signals by wired and wireless methods from the master device to the slave, where these are decrypted. As the originally acquired signals show some contamination of white noise, the transmitted and decoded signals are filtered through a Kalman filter embedded in the same algorithm, reaching -8 dB of noise diminution approximately. Afterwards, the decoded signals are compared with the initial ones by the Pearson correlation coefficient. When a synchronization error is fixed at 1 × 10−5, the experimental results exhibit transient times of 4.45 s and 2.69 min for the wired and wireless transmitting methods, respectively. However, as the estimated correlation coefficients are ranging in the interval 0.99963 < R < to 0.999999. Hence, the initial encrypted signal is entirely received by the slave device. The system is able to works in real-time, nevertheless, the determined sampling frequency is drastically diminished when the point-to-point communication is carried out via wireless

Cascaded Bidirectional Converter Topology for 700 W Transformerless High Frequency Inverter

Home inverter is an important system which provides uninterrupted power supply for domestic requirements. Most of the existing systems use line frequency transformers to generate the desired sinusoidal voltage and exhibit poor load regulation and efficiency. Under spurious conditions, reliable and stable operation of the inverter is a primary requirement. In this paper, 3-stage bidirectional (boost and buck) cascaded converter topology is proposed to boost an input battery voltage from 12 to 375 V and vice-versa. DC link is connected to H-bridge converter to obtain a desired sinusoidal output voltage. In the topology, first and third stages are non-isolated boost converters and second stage is a buck derived push–pull converter. Push–pull configuration of the 2nd stage provides electrical isolation to source from high voltage DC bus. Cascaded DC–DC converter outputs are regulated by designing an average current mode control and instantaneous voltage control is designed for H-bridge inverter. Hardware is designed and developed using digital signal controllers to supply 700 W domestic load. Experiments are conducted for different linear, nonlinear and dynamic load variations.

Real time compensation algorithm for air-gapped current transformers saturation effects

A platform implemented with digital signal controllers (DSCs) developed for real time studies of the dynamic behavior of the air-gapped current transformers (CTs) used in power grid protection and measurement systems is presented. The implemented algorithms simulate the fault current in an electric power system as well as the transient response of the current transformer. A method for correcting the CT secondary current distortion is presented in the case of gapped core where residual flux is negligible. To estimate the flux, a tertiary winding must be available. The ratio and phase errors, as well as the distortions in secondary current due the core saturation in fault situations are properly corrected by the method. Several cases were tested and the results indicate that the proposed method is very effective in improving the performance of protection schemes based on the current measurement.

Hysteretic Transition Method for Avoiding the Dead-Zone Effect and Subharmonics in a Noninverting Buck–Boost Converter

A new hysteresis window method is proposed as a solution for avoiding the operational dead zone that exists at the transition between buck and boost operating modes in all noninverting buck-boost converters. In addition, this method also eliminates the discontinuities in the converter's steady-state output voltage transfer characteristic, which is a function of the duty cycle. The converter's output voltage function is surjective and, therefore, smooth mode transitions are achieved. The negative effects of operating within the dead zone are shown by the presence of subharmonics in the output voltage, increased output voltage ripple, poor regulation, and the instability of the converter during the transition between buck and boost operating modes. The dead-zone avoidance technique proposed in this paper eliminates all these issues while at the same time ensures highly efficient operation of the converter. An additional advantage of the technique is its simplicity, which allows for implementation into low-cost digital signal controllers, as well as into analog control circuits. The advantageous features of the proposed approach were evaluated on the basis of comparisons with three other dead-zone avoidance approaches and the initial case, which does not utilize any dead-zone avoidance technique. All the experiments were carried out on a purpose-built prototype of a noninverting buck-boost converter with magnetically coupled inductors.

Nuevas tecnologías en los controladores digitales de señales, estudio y aplicaciones.

En el presente trabajo se abordan las nuevas tecnologías de los controladores digitales de señales (DSC), se hace una referencia general de las diferentes compañías fabricantes de este tipo de dispositivo, con el propósito que el lector tenga una idea generalizada de los diferentes productos existentes en el mercado, resaltando en ello las diferencias existentes con sus antecesores, de tal forma que sea posible identificar de una manera clara y precisa tales diferencias. El presente trabajo fue concebido con la finalidad de facilitar al usuario, una transición en el manejo de microncontroladores PICs® de proposito general, hacia el manejo de los microcontroladores avanzados como son los dsPIC., mismos que se pueden encontrar desde los uso de propósito general, hasta los que cuentan características especiales encaminadas hacia aplicaciones mas especializadas.

Teaching DSP in Digital Control

The paper describes an approach to introduce digital signal processors (DSPs) in teaching digital control for undergraduates in electrical engineering. The article focuses first on the increasing demand for computational power from new mathematical approaches to digital control techniques, such as digital power supply, digital motor control, photovoltaic inverters, inverters for solar arrays and LED illuminating. The challenge for educators is to provide both a basic understanding of hardware and software modules on processor technology and a reasonable mathematical background to the underlying theory. Over the last decade the author has developed a set of teaching modules based on the C2000 family of digital signal controllers. As an example of students' work, the paper also describes a project based on an autonomous driving car.

Temperature compensation of hot wire mass air flow sensor by using fuzzy temperature compensation scheme

Mass air flow sensors are increasingly used in the automotive industry to measure the mass air flow intake into the internal combustion engine. A problem occurred with the basic circuit for bridge type mass air flow sensor is the measurement accuracy of the sensor is affected by the temperature variation in the air. This paper presents the development of an open loop Fuzzy Temperature Compensation Scheme (FTCS) for hot wire mass air flow sensor. In order to verify the performance of the proposed scheme, first a simulation model was developed using Matlab/Simulink. Then, based on the Matlab/Simulink simulation, the FTCS has been implemented in hardware based real-time using Digital Signal Controllers, (dsPIC) with the Programming C Language. The effectiveness of the proposed fuzzy compensation scheme was verified with the estimation error within only 1% over the full-scale value. Key words: Hot wire, mass air flow sensor, temperature compensation, fuzzy logic.

Optimization of Hot Wire Mass Airflow Sensor by Using Fuzzy Logic Controller

Recently, there has been a growing demand for flow-temperature sensors for industrial, automotive, domestic and medical applications. A quick response and low power consumption. Hot Wire Mass Airflow Sensors are used in automotive industry to measure the mass air flow intake into the internal combustion engine according to heat transfer principles. As the heat transfer process is sensitive both to the velocity and temperature of the air, any changes in temperature must be compensated for in order to achieve accurate mass flow measurements. In this paper, the development of a Fuzzy Temperature Compensation Scheme (FTCS) for Hot Wire Mass Airflow (MAF) Sensor is presented. This FTCS used to compensate the measurement error occurred by using Sugeno type FIS for temperature of 60¡C-100¡C. In order to verify the performance of the proposed Hot Wire MAF Sensor temperature compensation scheme, first a simulation model is developed using Matlab/Simulink. Then, the algorithm for FTCS has been developed using Programming C Language and been implemented in hardware based real-time using Digital Signal Controllers, (dsPIC). The effectiveness of the proposed fuzzy compensation scheme is verified with the estimation error within only ±1% over full-scale value.

Design and Application of Full Digital Control System for LLC Multiresonant Converter

With use of microprocessors and digital signal controllers as a control systems in power semiconductor converters, the new approaches for design of digital control must be implemented. Designing a digital control system requires use of control to output transfer function. For new, frequency controlled resonant converters, like LLC converter, new simulation based, numerical methods must be employed. This paper deals with new method for revealing the transfer function. For proposal of optimal controller, the direct digital design was used. Verification of designed digital control system is shown at the end of paper.