Digital Signal Processor Control Research Articles

Energy-management system for a hybrid electric vehicle, using ultracapacitors and neural networks

A very efficient energy-management system for hybrid electric vehicles (HEVs), using neural networks (NNs), was developed and tested. The system minimizes the energy requirement of the vehicle and can work with different primary power sources like fuel cells, microturbines, zinc-air batteries, or other power supplies with a poor ability to recover energy from a regenerative braking, or with a scarce power capacity for a fast acceleration. The experimental HEV uses lead-acid batteries, an ultracapacitor (UCAP) bank, and a brushless dc motor with nominal power of 32 kW, and a peak power of 53 kW. The digital signal processor (DSP) control system measures and stores the following parameters: primary-source voltage, car speed, instantaneous currents in both terminals (primary source and UCAP), and actual voltage of the UCAP. When UCAPs were installed on the vehicle, the increase in range was around 5.3% in city tests. However, when optimal control with NN was used, this figure increased to 8.9%. The car used for this experiment is a Chevrolet light utility vehicle (LUV) truck, similar in shape and size to Chevrolet S-10, which was converted to an electric vehicle (EV) at the Universidad Catolica de Chile. Numerous experimental tests under different conditions are compared and discussed.

Implementation and Performance Evaluation of DSP-Based Control for Constant-Frequency Discontinuous-Conduction-Mode Boost PFC Front End

A digital signal processor (DSP) implementation of digital control for constant-frequency, discontinuous-conduction-mode boost power-factor-correction converter for universal line-voltage (90-264 V/sub rms/) applications is presented. A step-by-step design procedure based on digital redesign technique is also provided. The performance evaluation of the proposed DSP control is performed on a 400-W prototype. It was shown that the implemented DSP-based control can achieve a power factor higher than 0.99 in the entire line range.

Simplified Fuzzy-Logic-Based MTPA Speed Control of IPMSM Drive

This paper presents a simplified fuzzy logic based speed controller of an interior permanent synchronous motor (IPMSM) drive for maximum torque per ampere (MTPA) of stator current with inherent nonlinearities of the motor. The fundamentals of fuzzy logic algorithms as related to motor control applications are illustrated. A simplified fuzzy speed controller for the IPMSM drive has been found to maintain high performance standards with a much simpler and less computation intensive implementation than a nonsimplified fuzzy based algorithm. Contrary to the conventional control of IPMSM with d-axis current equal to zero, a nonlinear expression of d-axis current has been derived and subsequently incorporated in the control algorithm for maximum torque operation. The efficacy of the proposed simplified fuzzy logic controller based IPMSM drive with MTPA is verified by simulation as well as experimentally at dynamic operating conditions. The simplified FLC with MTPA is found to be robust for application in the IPMSM drive. The complete vector control scheme is implemented in real-time using a digital signal processor (DSP) controller board DS 1102 in a laboratory 1 hp interior permanent magnet synchronous motor.

A Sensorless Hybrid DTC Drive for High-Volume Low-Cost Applications

A sensorless hybrid direct torque control (DTC) drive for high-volume low-cost industrial, domestic, and automotive applications has been developed using the inexpensive TMS329F243 digital signal processor controller. Under transient operating conditions, the drive is controlled using the classic bang-bang DTC. In the steady state, using linear torque and flux controllers, the control system generates a reference voltage vector for the inverter feeding the induction motor. The vector is then realized using the well-known space-vector pulsewidth modulation (SVPWM) technique. As a result, the irregular switching pattern typical for the classic DTC strategy is replaced with a quasi-optimal one, typical for the SVPWM. Description of the drive, including a novel motor state observer, is followed by selected experimental results confirming its excellent operating characteristics.

Flexible Control of Small Wind Turbines With Grid Failure Detection Operating in Stand-Alone and Grid-Connected Mode

This paper presents the development and test of a flexible control strategy for an 11-kW wind turbine with a back-to-back power converter capable of working in both stand-alone and grid-connection mode. The stand-alone control is featured with a complex output voltage controller capable of handling nonlinear load and excess or deficit of generated power. Grid-connection mode with current control is also enabled for the case of isolated local grid involving other dispersed power generators such as other wind turbines or diesel generators. A novel automatic mode switch method based on a phase-locked loop controller is developed in order to detect the grid failure or recovery and switch the operation mode accordingly. A flexible digital signal processor (DSP) system that allows user-friendly code development and online tuning is used to implement and test the different control strategies. The back-to-back power conversion configuration is chosen where the generator converter uses a built-in standard flux vector control to control the speed of the turbine shaft while the grid-side converter uses a standard pulse-width modulation active rectifier control strategy implemented in a DSP controller. The design of the longitudinal conversion loss filter and of the involved PI-controllers are described in detail. Test results show the proposed methods works properly.

Rapid Prototyping Tools for Power Electronic Systems: Demonstration With Shunt Active Power Filters

This paper presents three new rapid prototyping tools to develop power electronic systems. The effectiveness of these tools is demonstrated by designing and building a shunt active power filter. First, a digital signal processor (DSP) model to embed complex control algorithms has been created for detailed offline simulations with PSpice. This DSP model emulates the discrete behavior of digital control circuits. The control algorithms in the DSP model are implemented in C-code. Secondly, the control C-code can be downloaded to the ISEADSP for real-time execution. The ISEADSP is a universal DSP control board based on two 80 SHARC processors which execute control algorithms of various nature and highest complexity at 80 MFLOP per second. Thirdly, power electronic building blocks (PEBBs) based on IGBT devices were developed to build and analyze quickly different converter topologies. Combining these three rapid prototyping tools led to a significant reduction of development time of power electronic applications.

A high-speed adaptive antenna array with simultaneous multibeam-forming capability

A new type of adaptive beamforming antenna system architecture is proposed for multichannel wireless communications. Multibeam communication with high data throughput is accomplished using the proposed beamformer architecture. The system consists of analog mixers, a multitone direct digital synthesizer (DDS), and a digital signal processor (DSP) controller. The essential idea of multibeam forming is based on a multitone weighting scheme combined with analog-digital hybrid signal processing. While the real-time multibeam construction is realized by the analog mixer circuits and a DDS, the complicated adaptive beamforming and direction-of-arrival estimation algorithms are carried out by the DSP. In this architecture, only one beamformer circuit is required to handle multiple beams, leading to significant reduction in hardware counts. A 5.8-GHz eight-element adaptive beamforming array successfully demonstrates two-beam simultaneous beamforming with less than three degrees of peak and null steering errors and more than 20-dB interference suppression. The test-bed exhibits successful two-channel data recovery at 25-Mb/s data throughput in each channel with binary phase-shift keying modulation, for simultaneous dual-beam reception. The bit-error-rate measurement validates the robustness of the communication quality under strong interferences.

An approach to reduce common-mode voltage in matrix converter

In this paper, an approach to reduce common-mode voltage at the output of a matrix converter is discussed. A new modulation strategy which reduces the common-mode voltage at the output is presented. The proposed method maintains the active voltage vector and distributes zero vector equally within a sampling period and reduces square RMS of ripple components of input current. Advantages of the scheme include: 34% reduction in the common-mode voltage (peak value); improved harmonic spectrum; reduced switching losses and no more additional switching instants over one sampling period; and simplified implementation via software. Further, the voltage transfer ratio is unaffected by the proposed scheme. Simulation results are shown to demonstrate the advantages of the new pulsewidth modulation approach. Experimental results on a 230-V 3-kVA matrix converter-fed adjustable-speed drive based on a digital signal processor controller are presented.

Active magnetic shielding for biomagnetic measurement using spatial gradient fields

Biomagnetic measurement performed outside a magnetically shielded room is subject to distortion by strong magnetic fields. Reducing such disturbances can enhance and stabilize biomagnetic measurement conditions in the absence of passive shielding. We have developed an active magnetic shielding system that produces both homogeneous and spatial gradient magnetic fields. The system is composed of anisotropic magnetoresistive sensors, a digital signal processor controller and two different coil systems. In order to improve the measurement environment for a first-order gradient coil SQUID system, the disturbing vertical magnetic fields and vertical field gradients are reduced, thus achieving a shielding factor of approximately 6 at 100 Hz. Our system provides a more flexible and less costly alternative to magnetically shielded rooms.

A method of tracking the peak power points for a variable speed wind energy conversion system

In this paper, a method of tracking the peak power in a wind energy conversion system (WECS) is proposed, which is independent of the turbine parameters and air density. The algorithm searches for the peak power by varying the speed in the desired direction. The generator is operated in the speed control mode with the speed reference being dynamically modified in accordance with the magnitude and direction of change of active power. The peak power points in the P-/spl omega/ curve correspond to dP/d/spl omega/=0. This fact is made use of in the optimum point search algorithm. The generator considered is a wound rotor induction machine whose stator is connected directly to the grid and the rotor is fed through back-to-back pulse-width-modulation (PWM) converters. Stator flux-oriented vector control is applied to control the active and reactive current loops independently. The turbine characteristics are generated by a DC motor fed from a commercial DC drive. All of the control loops are executed by a single-chip digital signal processor (DSP) controller TMS320F240. Experimental results show that the performance of the control algorithm compares well with the conventional torque control method.

An on-line MPPT algorithm for rapidly changing illuminations of solar arrays

Maximum power point tracking (MPPT) is usually used for a solar power system. Many maximum power tracking techniques have been considered in the past. The microprocessors with appropriate MPPT algorithms are favored because of their flexibility and compatibility with different solar arrays. Although the efficiency of MPPT algorithms is usually high, it drops noticeably in case of rapidly changing illumination conditions. The authors have proposed an improved MPPT algorithm based on the fact that the maximum power point (MPP) of solar arrays can be tracked accurately. The principle of energy conservation is used to develop the large- and small-signal model and transfer function for the solar power system. The work was carried out by both simulation and experiment on a current converter, by the digital signal processor (DSP) control, in MPPT mode under different illuminations. The results show that the proposed MPPT algorithm has successfully tracked the MPP in rapidly changing illumination conditions.

A multilevel inverter approach providing DC-link balancing, ride-through enhancement, and common-mode voltage elimination

This paper presents a simple control method for balancing the DC-link voltage of three-level neutral-point-clamped inverters, while providing enhanced ride-through and common-mode voltage (CMV) elimination. The method uses DC-DC power converter technology on the DC link for balancing and ride-through enhancement, and a modified pulsewidth-modulation switching algorithm for CMV elimination. Simulation and experimental results are supplied to confirm the validity of the proposed method, which includes full digital signal processor control.

Linear servo motor control using adaptive neural networks

A novel approach for designing and realizing a wavelet basis function network learning controller for a linear motor control system is considered. A new condition ensuring stability robustness of a closed-loop system including a neuro controller is derived. The proposed controller deals mainly with non-linear disturbances, especially viscous friction and force ripples that occur in motion control of linear synchronous motors. It consists of two parts: the feedback controller is designed on the basis of a simple linear model, and the learning feedback component is a wavelet neuro controller. A real-time simulation scheme on a recently developed high speed, multiple input-output, digital signal processing control board is constructed to realize and evaluate the proposed design. Mathematical and real-time simulations and an experimental study are performed to validate the proposed approach.

Performance of interior permanent magnet motor drive over wide speed range

This paper investigates the performance of an interior permanent magnet synchronous motor (IPMSM) drive over wide speed range for high precision industrial applications. The scheme incorporates the maximum torque per ampere (MTPA) operation in constant torque region and the flux-weakening operation in constant power region in order to expand the operating limits for an IPMSM. Improved mathematical expressions are derived to analyze the performances of the IPMSM. The power ratings of the motor and the inverter are considered. The effects of motor parameters particularly, the saliency ratio (X/sub q//X/sub d/) on the voltage limit constraint and the power capability of the inverter are also investigated. The efficacy of the above mentioned drive system and the improved steady-state analysis are evaluated by both experimental and computer simulation results. The complete drive is implemented in real-time using digital signal processor (DSP) controller board DS 1102 on a laboratory 1 hp interior permanent magnet synchronous motor.

Performance of Interior Permanent Magnet Motor Drive over Wide Speed Range

This paper investigates the performance of an interior permanent magnet synchronous motor (IPMSM) drive over wide speed range for high precision industrial applications. The scheme incorporates the maximum torque per ampere (MTPA) operation in constant torque region and the flux-weakening operation in constant power region in order to expand the operating limits for an IPMSM. Improved mathematical expressions are derived to analyze the performances of the IPMSM. The power ratings of the motor and the inverter are considered. The effects of motor parameters particularly, the saliency ratio (X/sub q//X/sub d/) on the voltage limit constraint and the power capability of the inverter are also investigated. The efficacy of the above mentioned drive system and the improved steady-state analysis are evaluated by both experimental and computer simulation results. The complete drive is implemented in real-time using digital signal processor (DSP) controller board DS 1102 on a laboratory 1 hp interior permanent magnet synchronous motor.

Vibration-compensated interferometer for surface metrology

An advanced interferometer was built for surface metrology in environments with severe vibration. This instrument uses active control to compensate for effects of vibration to allow surface measurement with high-resolution phase-shifting interferometry. A digital signal processor and high-speed phase control from an electro-optic modulator allows phase measurements at 4000 Hz. These measurements are fed back into a real-time servo in the digital signal processor that provides a vibration-corrected phase ramp for the surface measurements taken at video rates. Unlike fringe locking, which compensates vibration to keep the phase constant, we show a true phase servo that allows the phase to be stabilized while it is ramped, enabling surface measurements using phase-shifting interferometry that requires multiple images with controlled phase shifts.

Synergistic design of DSP and power amplifiers for wireless communications

Co-design of digital signal-processing (DSP) algorithms and power-amplifier characteristics can lead to improved efficiency and linearity through a variety of strategies including: predistortion, DSP control over bias conditions, particularly the power supply voltage, and DSP generation of digital input signals for switching amplifiers. This paper discusses several amplifier architectures that exemplify these approaches, including: bias-controlled linear amplification with nonlinear component and class-S amplifiers. We envision for the future a generation of smart power amplifiers, in which DSP optimization of amplifier parameters is carried out for changing environments.

Solar Spectral Irradiance Monitor (SIM)

The Spectral Irradiance Monitor (SIM) will measure the solar spectral irradiance between 0.2 µm to 2.0 µm to a relative standard uncertainty of 3 × 10−4 (1 s) and with a noise level of <1 × 10−4. The instrument will be launched in 2002 on the SORCE mission of the Earth Observing System (EOS). Sunlight passes through a 0.3 mm × 7 mm entrance slit and is modulated by a shutter at 0.1 Hz. Light then travels 400 mm to a Fery prism that disperses and focuses the light at the focal plane containing five separate exit slits, with an electrical-substitution radiometer (ESR) and four photodiode detectors. The ESR consists of two back-to-back 1 mm × 10 mm diamond bolometers blackened with nickel phosphorus. The bolometer bridge, electrical power replacement, ESR temperature regulation, and prism rotation are under digital signal processor control. The measurement equation and the uncertainty budget for the SIM instrument are presented along with plans for the pre-flight characterization of the instrument.

Application of DSP Controller on X-Y Table Servo Control

A digital signal processor (DSP) servo control card comprises a TMS320C50 DSP accompanied by appropriate encoder interfaces, digital/analogue output interfaces and other peripheral circuits. In this study, it was plugged in a vacant slot of a PC to act as a high-performance servo controller for monitoring the control of a dual axis X-Y table. The basic planning of the memory, the initial assignment of the registers, the peripheral interface operation mode specification and the program flowchart are introduced. A fuzzy logic control scheme is employed to improve the control accuracy of the X-Y table positioning and tracking. Experimental results are used to verify the control performance of this fuzzy logic DSP controller and the experimental results from the fuzzy control scheme are compared with those of a PID controller.

Adaptive sliding-mode observer for speed-sensorless control of induction motors

This paper presents an adaptive sliding-mode observer for the speed-sensorless field-oriented control of induction motors. The observer detects the rotor flux components in the two-phase stationary reference frame by the motor electrical equations. The motor speed is estimated by an additional relation obtained by a Lyapunov function. The analytical development of the sliding observer and the speed estimation algorithm is fully explained. Experimental results are presented, based on a TMS320F240 digital signal processor controller implementation. The system performance with different observer gains and the influence of the motor parameters deviations are shown and discussed.