Microprocessor-based modified discrete integral variable-structurecontrol for UPS

This paper presents a digital signal processor microprocessor-based high-performance uninterruptible power system (UPS). It also modifies the integral variable-structure control (IVSC) approach to be more suitable for the UPS, which is tracking a sinusoidal AC voltage with specified frequency and amplitude. Since the implementation of the control laws has tended to the digital microprocessor, the paper extends the modified IVSC to the discrete time domain. Procedures are developed for determining the control function, the switching plane and the integral control gain, so that the system has desired properties. Simulation and experimental results show that the proposed scheme can supply a high-quality voltage power source in the presence of load disturbance and parameter variation     

A digital power factor correction (PFC) control strategy optimized for DSP

A predictive algorithm for digital control power factor correction (PFC) is presented in this paper. Based on this algorithm, all of the duty cycles required to achieve unity power factor in one half line period are calculated in advance by digital signal processors (DSP). A boost converter controlled by these precalculated duty cycles can achieve sinusoidal current waveform. One main advantage is that the digital control PFC implementation based on this control strategy can operate at a high switching frequency which is not directly dependent on the processing speed of DSP. Input voltage feed-forward compensation makes the output voltage insensitive to the input voltage variation and guarantees sinusoidal input current even if the input voltage is distorted. A prototype of boost PFC controlled by a DSP evaluation board was set up to implement the proposed predictive control strategy. Both the simulation and experimental results show that the proposed predictive strategy for PFC achieves near unity power factor.     

Smooth profile generation for a tile printing machine

In this paper a digital filter is proposed for the generation of smooth set points for motion control systems. The proposed nonlinear filter produces profiles with bounded velocity and acceleration starting from rough reference signals (steps and ramps). An actual implementation of the filter for a tile printing machine is presented and experimental results are reported.     

Experimental Comparison of Digital Implementations of Single-Phase PFC Controllers

This paper presents the design and the digital implementation of three controllers for a single-phase power factor corrector (PFC). Based on an averaged system model, an adaptive nonlinear control strategy is first designed, followed by a digital redesign of the standard cascaded linear controller and a notch-filter-based variant. All three controllers have been verified via simulation in Simulink using a continuous time plant model and a discrete time controller. Real-time implementation is performed on an experimental testbed utilizing a rapid prototyping tool. The three controllers are experimentally compared for steady-state performance and transient response. It is shown that the nonlinear controller gives a better steady-state performance, whereas the linear strategy and the notch-filter-based variant have a faster dynamic response. Furthermore, although the notch-filter-based linear design shows promise in simulation, practical difficulties degrade its experimental performance. Performance metrics are tabulated for easy comparison.     

A novel converter topology for multiple individually regulated outputs

Power supply voltages in digital systems have reduced considerably in recent years, and often digital components requiring different voltages are present on the same board. This has increased the demand for multiple output power distribution systems with tight individual load voltage regulation. This paper presents a power distribution system having a central power supply that acts as a controlled current source whose output is connected to individual loads on a time shared basis. All the magnetics are concentrated in the converter acting as the current source. The current source can be realized by a current controlled buck, buck-boost, or single-ended primary inductance converter (SEPIC). First, a comparative analysis of buck, buck-boost, and SEPIC based implementation of the current source is carried out. Next, a buck-based current source implementation with constant frequency pulse-width modulation control for the output voltages is described. Detailed component and control design, simulations, and experimental results for a 100-W prototype are presented.     

Repetitive-based control for selective harmonic compensation in active power filters

This paper proposes a repetitive-based controller for active power filters, which compensates selected current harmonics produced by distorting loads. The approach is based on the measurement of line currents and performs the compensation of selected harmonics using a closed-loop repetitive-based control scheme based on a finite-impulse response digital filter. Compared to conventional solutions based on stationary-frame current control, this approach allows full compensation of selected frequencies, even if the active filter has limited bandwidth. Compared to synchronous-frame harmonic regulations on line currents, the complexity of the proposed algorithm is independent of the number of compensated harmonics. Moreover, it is more appropriate for digital signal processor implementation and less sensitive to rounding and quantization errors when finite word length or fixed-point implementation is considered. Experimental results on a 5-kVA prototype confirm the theoretical expectations.     

Offset-free combined neural network/switching control for nonlinearservomechanisms with DSP-based implementation

In this paper, we present a combined neural network/switching controller which is shown to provide offset-free regulation and control in the presence of disturbances. The controller is applicable to nonlinear servomechanisms of the type commonly encountered in motion control. In the paper, the properties of the controller are discussed and the implementation of the overall control system using a microcomputer host with a digital signal processor (DSP) accelerator is described. The paper also includes the results of real-time experiments in applying the proposed controller for position control of a nonlinear servomechanism which provides experimental verification of the effectiveness of the proposed method     

Low-order continuous-time robust repetitive control: Application in nanopositioning

A low-order repetitive control (RC) design in continuous-time for nanopositioning applications is presented. It focuses on achieving high performance and sufficient robustness to uncertainties. The design is mainly applicable to analog implementation, but due to the exceptionally low order, it also results in a fast and efficient digital implementation. Experimental results for an analog implementation using a bucket brigade device (BBD), as well as a digital implementation, is presented. RC can provide fast and accurate tracking of periodic reference signals, which is useful in many scanning probe microscopy and nanofabrication applications.     

Characteristic Analysis for Multisampled Digital Implementation of Fixed-Switching-Frequency Closed-Loop Modulation of Voltage-Source Inverter

In this paper, a fixed-switching-frequency closed-loop modulation of a voltage-source inverter (VSI), upon the digital implementation of the modulation process, is analyzed and characterized. The sampling frequency of the digital processor is considered as an integer multiple of the modulation switching frequency. An expression for the determination of the modulation design parameter is developed for smooth modulation at a fixed switching frequency. The variation of the sampling frequency, switching frequency, and modulation index has been analyzed for the determination of the switching condition under closed loop. It is shown that the switching condition determined based on the continuous-time analysis of the closed-loop modulation will ensure smooth modulation upon the digital implementation of the modulation process. However, the stability properties need to be tested prior to digital implementation as they get deteriorated at smaller sampling frequencies. The closed-loop modulation index needs to be considered maximum while determining the design parameters for smooth modulation. In particular, a detailed analysis has been carried out by varying the control gain in the sliding-mode control of a two-level VSI. The proposed analysis of the closed-loop modulation of the VSI has been verified for the operation of a distribution static compensator. The theoretical results are validated experimentally on both single- and three-phase systems.      

数字Costas环的设计与实现

针对扩频系统的载波同步,研究了数字Costas环的设计和实现方法。介绍了数字Costas环的结构、实现载波同步的基本方法。以二阶环为例,分析了数字锁相环的环路滤波器的参数设计方法,为数字Costas环的设计提供了参考。提出了在高速信号处理板(以FPGA和DSP为基础)中数字Costas环的实现方案,经工程验证,能够实现载波同步,解调出所需信号。     

A digitally controlled DC/DC converter for an RF power amplifier

This paper describes design and implementation of a digitally controlled dc/dc converter that provides a dynamically adjustable supply voltage for a radio frequency power amplifier (RFPA). The techniques employed in the design include a combination of constant-frequency continuous conduction mode (CCM) and a variable-frequency discontinuous conduction mode to achieve very high converter efficiency over a wide range of output power levels. The variable-frequency converter control is accomplished using a current-estimator circuit, which eliminates the need for current sensing. A field-programmable gate array (FPGA)-based digital controller implementation allows programmability of the mode transition and other controller parameters. In the complete experimental system, which consists of the digitally controlled dc/dc converter and a class-E RFPA operating at 10GHz, experimental results show that the overall system efficiency is significantly improved over a wide range of RFPA output power levels.     

Design of a real-time digital Simulator for a D-STATCOM system

Real-time digital simulation of power electronic systems requires significant computational resources due to increasingly complex system configurations, control algorithms, and higher switching frequency. Consequently, it is prudent to exploit various computer resources for optimizing the design of simulators/controllers for such systems. This paper presents the design and implementation details of a real-time digital simulator for a Voltage-Source-Converter-based Distribution STATic COMpensator (D-STATCOM) power system. The design process adopts a modular approach utilizing distributed digital signal processor/field-programmable gate array resources of a digital processing platform. The design has been validated by using an experimental setup of a 5-kVA D-STATCOM system.     

Microprocessors and digital ICs for motion control

This paper reviews the developments in microprocessors and digital ICs with a special attention to applications to motion control. First, the use of microprocessors and digital ICs in the control of electric motor drives is considered. General-purpose microprocessors and microcontrollers are then presented with emphasis on features that are necessary for the implementation of real-time control systems. High-performance advanced processors such as digital signal processors (DSPs), reduced-instruction-set computing (RISC) processors, and parallel processors are studied. Development and debugging tools required for developing sophisticated microprocessor-based control systems are considered. The capabilities of application-specific integrated circuits (ASICs) in motion control and their design process are examined. Typical application examples illustrating research work in digital motion control using microprocessors and digital ICs are presented. The potentials of new devices are considered for application to high-performance drive systems. Trends for future development of the microprocessor technology for motion control applications are projected     

A New Duty Cycle Control Strategy for Power Factor Correction and FPGA Implementation

The bottleneck of digital control for power factor correction (PFC) implementations is mainly due to three aspects: high calculation requirements, high cost, and limited switching frequency compared with analog implementations. A new duty cycle control strategy for boost PFC implementations is proposed in this paper. The duty cycle is determined based on the input voltage, reference output voltage, inductor current, and reference current. The duty cycle determination algorithm includes two terms, the current term and the voltage term, which can be calculated in parallel and requires only one multiplication and three additions (subtractions) operations in digital implementation. A 400-kHz switching frequency boost PFC based on field programmable gate array implementation and its test results show that the proposed new duty cycle control strategy has great potential in the next generation of high switching frequency PFC implementations, due to its lower calculation requirement, lower cost, and better performance than the conventional PFC control methods     

QPSK全数字接收机定时同步环路

将三阶立方拉格朗日多项式内插算法和Gardner定时误差检测算法应用于QPSK全数字接收机定时同步环路,并对构成环路的其他部分,环路滤波器以及数控振荡器进行分析并提出实现方法。通过仿真,证明上述算法具有良好的性能,可以很好的解决定时同步问题,并在FPGA上实现整个环路设计方案,使得数字解调的硬件实现具有良好的灵活性和可移植性。     

数字多波束技术信号处理算法研究

介绍了数字多波束技术的应用。重点分析了目前较为常用的3种数字多波束技术信号处理的自适应算法并对各种算法进行了比较。自适应算法的选择决定了在环境变化时，波束自适应控制能力和反应速度，以及实现算法所需硬件的复杂性。     

基于FPGA的OFDM系统数字中频设计

主要讨论了OFDM(正交频分复用)系统中使用数字中频的优点、在发射机和接收机中的实现方案.重点叙述了数字中频中两个关键模块NcO(数控振荡器)和成型滤波器在FPGA(现场可编程门阵列)中的设计.在NCO的设计过程中采用有效、简便的方法一查表法;成型滤波器使用了固定系数的有限冲击响应滤波器.介绍了使用分布式运算法和CSD(典范带符号)方法设计成型滤波器的原理,分析了数字量化误差.     

Digital implementation of a line current shaping algorithm for three phase high power factor boost rectifier without input voltage sensing

In this paper the implementation of a simple yet high performance digital current mode controller that achieves high power factor operation for three phase boost rectifier is described. The indicated objective is achieved without input voltage sensing and without transformation of the control variables into rotating reference frame. The controller uses the concept of resistance emulation for shaping of input current like input voltage in digital implementation. Two decoupled fixed frequency current mode controllers calculate the switching instants for equivalent single phase boost rectifiers. A combined switching strategy is developed in the form of space vectors to simultaneously satisfy the timing requirements of both the current mode controllers in a switching period. Conventional phase locked loop (PLL) is not required as converter switching is self-synchronized with the input voltage. Analytical formula is derived to obtain the steady state stability condition of the converter. A linear, low frequency, small signal model of the three phase boost rectifier is developed and verified by measurement of the voltage control transfer function. In implementation Texas Instruments's DSP TMS320F240F is used as the digital controller. The algorithm is tested on a 10-kW, 700-V dc, three phase boost rectifier.     

Implementation of self-tuning algorithms for reference tracking ofa DC drive using a DSP chip

This paper describes the implementation of two self-tuning control algorithms for the speed control of a permanent magnet DC motor. The algorithms minimize a cost function incorporating system input, output, and set-point variation for reference tracking. Variable forgetting factor using data normalization with constant trace has been utilized. Self-tuning controllers have been implemented using a single-chip digital signal processor (DSP). It results in reduction of system hardware, cost, and calculation time     

Implementing a /spl Sigma/ /spl Delta/ DAC in Fixed Point Arithmetic

This paper describes a simple sigma delta (SigmaDelta) digital to analog converter (DAC) that is suitable for use on the simplest of microprocessors to generate constant level or slowly varying control voltages by taking advantage of a SigmaDelta network's intrinsic limit cycle behavior. The paper describes the properties of the converter, and shows that it is inherently stable. It also explains how the user can control the dc level of the DAC's analog output, and discusses the implementation of such a DAC on an industry standard microprocessor