Gabriel Chindris

Using DSP technology for true sine PWM generators for power inverters

This paper presents theoretical and experimental aspects related to the implementation of a DSP-based fully digital single phase true sine PWM inverter. The proposed digitally-controlled PWM inverter employs a single chip DSP to realize a double-loop voltage and current mode control scheme. The Motorola DSP56F80/spl times/ family is well-suited for digital inverter control, combining the DSPs calculation ability with the microcontrollers function on a single chip and is a fully versatile part for a high performance, low cost, single chip PWM generator with many additional features not found in other solutions. The conclusions of the paper allow an objective evaluation of using DSP in the generation of sinusoidal PWM signals and in inverter control schemes.

Power factor correction circuit with a new modified SEPIC converter

This paper presents a new topology for a SEPIC converter used in power factor correction circuits. The conventional SEPIC converter was primarily designed to provide a nonpulsating input current, operating with both inductors in continuous current mode and only DC-DC conversion was considered. The modified SEPIC converter is designed to operate as an AC-DC converter and can be viewed as a cascade of a modified boost converter and a buck-boost converter. The boost converter operates in discontinuous current mode, while the buck-boost converter operates in continuous current mode. Since a high power factor is naturally achieved in this way, a simple feedback control technique is needed in order to regulate the output voltage. The paper also presents a calculus method for the power factor and total harmonic distortion factor for the proposed converter.

Deploying Simulink Models into System-On-Chip Structures

Nowadays design of embedded systems for controlling industrial processes requires higher and higher integration of analog and digital features. In this way, the system-on-chip approach for designing such embedded systems seems to be the most competitive solution in terms of cost-effectiveness and performance (Chindris, 2002 and Pop and Chindris, 2003). The classical solution still holds some of the advantages: most of the software tooling required for designing an embedded controller will consist in a control algorithm simulator (as Matlab Simulink) and code generation software for deploying the algorithm into the embedded controller. For that solution, code generation templates and S-function compilers are widely spread and cover a large family of microcontrollers and microprocessor. The paper will present a new method for using control algorithm simulators along with code generation software in order to deploy applications inside programmable system-on-chip devices. Deployment tests and experimental results will be also covered for a simple PID algorithm as test reference.

New PSPICE model for power MOSFET devices

The common PSPICE model for the power MOSFET device is well known to CAD designers. This paper addresses the problem of how to correctly simulate a nonlinear device by modeling the nonlinear components of its PSPICE model: drain-to-source resistance vs. temperature, drain-to-source and gate-to-source capacitance vs. voltage. By comparing the simulation results of the common PSPICE MOSFET model with the manufacturers specifications, the drawbacks of the model are revealed. The paper explains the basic theory behind modeling linear and nonlinear capacitors and resistors and describes how to model nonlinear capacitors and resistors using the analog behavioral modeling (ABM) feature of PSPICE. Examples are provided that show the circuit diagrams for various nonlinear capacitors and resistors and PSPICE plots of the transient analysis results. Based on these principles, a new MOSFET model is generated and used in some examples.

Influence of power consumption over the input current harmonics pollution for a half-bridge power inverter

The intent of this presentation is to present the influence of power level delivered on a load over the total harmonic distorsion of input current for a power half-bridge inverter with resonant load. Half-bridge inverter is a configuration used for higher output power applications compared to single end quasi-resonant inverter. Even though it needs complicated control, half-bridge configuration has been winning popularity because it is relatively much more reliable and easier to build up higher power system.

Performances Evaluation of Frequency Measurement Techniques in Automotive Industry

Many automotive sensors have as output a square wave signal, whose frequency is related which measurement parameters. Such sensors are use for measuring the shafts rotation and wheels rotation. The measurement systems are developed basically based on a microcontroller, which timers capture feature is used for frequency measurement. The frequency measurement principle is the same for every microcontroller; the differences consist in peripherals settings. Three frequency measurement techniques were studied; the experimental results were made using a sixteen bits microcontroller - C167 from Infineon. Knowing the performances of each frequency measurement techniques is a step forward to reduce the design costs by choosing the appropriate technique according with design specification.

PSoC dual sensor for pressure and temperature using bipolar junction effects

This paper presents theoretical and experimental aspects of the methodology for embedded sensor design with PSoC controllers for measuring the pressure and temperature using two NPN transistors, enlightening the benefits of the method: a PSoC design reduces the time-to-market, increase flexibility, lower part count, provides in-system performance improvement, design security, and field upgrades. Also, another benefit of a PSoC controller is the dynamical re-configuration. The effect of pressure over an emitter-base junction makes a modification of the saturation current, that means a translation of the input characteristic of the emitter-base junction to higher values. The method consists in measuring the temperature and pressure using two transistors and compensates the dependencies between them. This is done by using the same PSoCs pins and an internal dynamic reconfiguration: one configuration for measuring pressure and one configuration for measuring temperature

Educational platform for modeling of zero-voltage switching quasi-resonant boost converters

This paper presents an educational platform for modeling of basic zero-voltage switching quasi-resonant boost converters using mathematical methods. In order to visualize the results of solving the equations that describe the converter operation, we used Matlab software modules. The advantages of this method of study are: (1) wider availability - it is possible to view the results over the Internet; (2) increased flexibility t is possible to modify any circuit component values, including parasitic components, and study their influence in converter operation, included the time periods affected; (3) it is possible to analyze both half-wave and full-wave operation mode; (4) it is possible to select which operating regimes are displayed, transient or steady-state. The conclusions of the paper allow an objective evaluation of the advantages described above vs. circuit-oriented simulators in the study of quasi-resonant switching mode power supplies. In addition, with an appropriate modeling of each circuit component, this platform allows analyses of component non-idealities (including package models) and their influence on circuit operation.

System on chip design for multiple output switching regulators

Nowadays electronics designs implies more and more elaborated solutions for power supplying circuits due to the increasing demands of designers: multiple voltages output, low EMI, increased thermal efficiency, etc. For current designs, multiple voltages output usually means multiple PWM controllers, enlarged PCB area and a complicated custom design of the power circuitry. The proposed SOC design implements a power management structure for multiple voltages output in a single chip, optimized for minimum PCB area and maximum configurability. A design example will show that the use of this design reduces PCB area with 80% for the power circuitry, increasing EMI and thermal performance and also allowing the re-use of the design for different production versions. The paper relies on previous work of authors in SOC and SMPS fields (design of a PWM SOC controller) and it brings a major contribution in implementing multiple outputs reconfigurable SMPS controllers by using common SOC programmable structures. The experimental results (for both SOC and non-SOC designs) underline the main advantages of the proposed solution and allows an objective evaluation of performances

Mathematical analysis to control power transfer in resonant power converters

This paper aims to present a mathematical analysis method for resonant power converter, in order to control the transfer of power which is transmitted to the load. Starting from the idea that most switching power converters are using the pulse width modulation (PWM) technique to control the switching elements, the paper presents an analysis of the control method that can be applied on such converters and a mathematical analysis of the resonant load that can be found at the output of the circuit. On the other hand, the paper proposes an interactive interface to design and simulate a resonant power converter. The tool can be used by experienced engineers in power converters domain, to properly configure such a circuit, but also by those who are starting to learn and understand how these circuits are working. The tool allows seeing, not just the final values for the components that make the circuit, but also the waveforms form the main components. By doing so, the converters area of operation can be observed, allowing to adjust the design in order to improve the design.