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Torque ripples are usually found in brushless DC (BLDC) motor control applications. This article presents the design of non-sinusoidal back electromotive forces (BEMF) observer for a BLDC motor in order to reduce electromechanical torque ripples. For their robustness quality, a high order sliding mode observer is used to observe the non-sinusoidal BEMF which allows to determine magnetic field angular relative position leading to a so-called extended Park’s transformation. Using this extended transformation, speed and torque vector control can be made with better performances than the classical Park’s transformation. Simulation results are performed to show the effectiveness of the proposed approach.

International audience; Energy storage elements such as supercapacitors are widely used in high-power applications. However, due to single cell voltage limitation, an energy storage system with a large number of supercapacitors is often employed. Energy management systems are associated to energy storage systems in order to assure user and equipment safety. Balancing circuits, which enable the equalization of the voltage of each element in series, are a part of the energy management system device. The work presented in this paper aims to enhance the lifetime of energy storage systems. It relies on better controlling balancing circuits on the terminals of the storage system elements. With the conventional function of balancing circuit, the energy storage system is limited by its weakest element that may fail prematurely. Thus, a new balancing approach is presented, discussed, and analyzed. It is based on the elements degradation level prediction. The model predictive control used with the new approach aims to equalize aging speed between elements of a module and ensures a maximum lifetime to the energy storage system. A comparison with the conventional control shows that adopting this new approach, with the same equipment, can enhance the storage system's lifetime by dozens percent.

International audience; Electrical traction using induction machine sensorless control requires high observer performance for all speed ranges, even for low speed or regenerative braking conditions which appear frequently during long time. It is well known that the speed of induction motors is unobservable at very low stator frequencies. This paper uses an observability index to continuously analyze speed observability for sensorless control of induction machines. The correlation between observability-index and observer performance is illustrated in a Hardware in the Loop (HIL) experimental test-bench combining the well-known vector control with an extended Kalman filter. Thanks to the observability-index information, an optimal strategy is proposed to design controllers to guide the system away from undesirable behavior and avoid the weak observability-index region by taking into account all working constraints. A simplified case is presented to improve the speed observer performance, which was tested in the same conditions with the same HIL test-bench to experimentally validate the proposed sensorless control for traction applications.

International audience; This paper focuses on the observer-based methods for induction machine sensorless drive. It is well known that the use of speed observer is limited at a very low stator frequency due to speed unobservability. Some existing methods propose to avoid the zero-stator-frequency working points. These methods are nonetheless limited to high-torque operations. The first contribution of this paper is to analyze finely the speed observability, which leads to the definition of an observability index. The correlation between this index and the observer performance is analyzed and illustrated. The second contribution is to propose a control strategy that maximizes the observability index and improves the observer performance. The proposed strategy is tested first in open loop to evaluate the speed observer performance, and then, in closed loop to illustrate its pertinence for induction machine sensorless drive. All these results are validated by an experiment. The performed experimentation shows that the proposed control strategy gives better results than the existing method that avoid the zero-frequency working points. It offers a new path for induction machine sensorless drives.

As capacitor voltages are necessary for the three-cell DC-DC chopper control, the estimation of such voltages by an observer is attractive solution in terms of cost. However, due to the hybrid behavior of this structure, the capacitor voltages may be partially or even not observable for a given switching configuration. In other words, the observability matrix associated to the capacitor voltages never has a full rank. In order to make the observer conceivable, this paper proposes a new design by establishing sufficient conditions under which the capacitor voltages can be reconstructed within appropriate specific switching sequence and not necessarily instantly. An interconnected high gain observer is then designed for the considered structure. Furthermore, the analysis of convergence is given according to specific switching sequence, and the bounds of the observer tuning parameters are numerically verified. A significant load current benchmark including a three-cell chopper is used as prototype to show the performance and the effectiveness of the proposed observer.

International audience; This paper focuses on an effective method for both stator and rotor resistance on-line observation of induction machine driven without mechanical speed sensor. These resistances change over a large range with both the temperature and the flux frequency, making on-line adaptation of these parameters necessary to reach a precise speed observer. To do so, the sensitivity of the speed observation with respect to each resistance and the observability of the resistances are analysed in order to define an observation strategy for the stator and rotor resistances for which the resistances are updated only when necessary. HIL experimentations show that the observation precision on the resistances is good and that the speed observation remains precise and stable despite electrical parameter variation.

International audience; This paper presents an averaged model and nonlinear observer for an on/off pneumatic actuator. The actuator is composed of two chambers and four on/off solenoid valves. The proposed averaged model has the advantage of using only one continuous input instead of four binary inputs. Based on this new model, a sliding mode observer is designed using the piston position and the pressure measurements in one of the chambers in order to estimate the piston velocity and the pressure in the other chamber. The observation errors converge towards zero in finite time and the performance of this observer is validated in closed loop on an experimental benchmark.

International audience; Despite their alias-free operation, continuous time ADCs can have their power consumption overwhelmed when presented out-of-band, high frequency, high amplitude signals. A new continuous time ADC architecture which, thanks to its embedded low-pass filter transfer function is proposed, enables a power efficient quantisation in the presence of such signals. Moreover, the half-digital nature of this approach simplifies the implementation of the proposed system compared to a standard filter-first solution.

International audience; This paper presents a novel digital controller for the high switching frequency buck converter based on the principle of predictive control. Compared to traditional current-mode predictive controller, the prediction of the inductor current and the output voltage are performed at the same time by adding a control variable to the DPWM signal that can dynamically adjust the time of voltage jump. It accelerates the convergence rate during transient states, while inherently preserving the rejection of power and reference perturbations. The analysis of controllers operation illustrates the dual-state-variable predictive attributes that lead to the digital implementation. To further enhance the power efficiency of the controller, an 1-1 MASH - DPWM with a feasible dither generation module is proposed to restrain the idle-tone effects without deteriorating the closed-loop stability as well as to preserve reasonable cost in silicon area. Experimental results verify closed-loop operations at switching frequency up to 4 MHz only limited by the discrete buck converter. The converter is well regulated over a large output range with excellent dynamic performances.

Plein texte disponible sur http://scialert.net/qredirect.php?doi=ajaps.2011.202.210&linkid=pdf; International audience; The aim of this study is to present a high dynamic current control and speed estimation strategy for Permanent Magnet Synchronous Motor (PMSM) drives without a speed transducer. The strategy is based on the exact linearization methodology and Extended Sliding Mode Observer (ESMO) algorithm. The performances of the proposed control strategy are analysed by simulations for a 1.6 kW PMSM. The obtained results show the effectiveness of the proposed robust current control approach and speed observation algorithm under load torque and stator resistance variation.

International audience; Digital control technique is becoming an attractive alternative for high-frequency switching mode power supply (SMPS). This paper introduces a fully synthesizable digital sliding-mode (SM) controller for high-frequency dc/dc SMPS. The proposed SM controller is associated with a digital pulsewidth modulation (DPWM) block to operate at constant and high switching frequency compared to already published approaches. The digital SM controller is experimentally validated by means of field-programmable gate array in a 4-MHz step-down converter with 10-bit analog-to-digital conversion (ADC) and 11-bit DPWM. Measured dynamic performances are superior to conventional digital controllers for dc/dc SMPS.

Plein texte disponible sur http://scialert.net/qredirect.php?doi=ajaps.2011.202.210&linkid=pdf; International audience; In this study, a reduced-order discrete-time Extended Sliding Mode Observer (ESMO) is introduced for on-line estimation of rotor fluxes and rotor time constant. The satisfying simulations and experimental results carried out on a 5.5 kW induction motor demonstrate the excellent performance and high robustness of the proposed ESMO against parameter variations, modeling uncertainty and measurement noise. It is concluded that the implementation in real-time of this reduced-order ESMO in the industrial applications, compared with the full-order ESMO, permit on the one hand to overcome the heavy computational effort, complexity and hard tuning of the estimation algorithm and on the other hand, to reduce the execution time of the observation with a good accuracy and considerable rapidity.

This paper models a low-power high-frequency digitally controlled synchronous rectifier (SR) buck converter. The converter is a hybrid system with three operation modes. Digital PID controler is used. Key problems such as quantization resolution of digital pulse-width modulation (DPWM) and steady-state limit cycles of digital control switching model power supply (SMPS) are discussed, with corresponding solutions presented. Simulation of a digital control synchronous buck is performed with a fixed-point algorithm. The results show that the described approach enables high-speed dynamic performance.

International audience; This paper presents a new predictive current control (PCC) for permanent magnet synchronous machines (PMSM) drivers. Based on a hybrid model including an inverter model and a PMSM model, the proposed scheme selects more than one inverter configuration and allows to reach exactly the reference state vector. It appears attractive when compared to conventional direct torque control (DTC). Hysteresis comparators are not used. The switching frequency is fixed and it does not have to be very high. The control scheme has been verified experimentally with a 1.6 kW PMSM drive. Comparative studies with DTC control are performed with the same test bench. The results show that the proposed control obtains the same fast torque dynamics if not better than DTC control schemes but with smaller ripples. (C) 2007 Elsevier B.V. All rights reserved.

International audience; The use of Electro-Mechanical Actuator to impact an environment is often criticized because of its presumably higher wear. This is due to the naturally high stiffness of the mechanical transmission, that leads to a hard-to-hard impact with the environment. This paper proposes a position-based impedance control using a Finite Control Set Model Predictive Control (FCS-MPC) controller to solve this problem. In comparison to a standard impedance controller, it can achieve the same impedance behavior in steady state, but the reduction of the mechanical losses and of the compression of the transmission are better during the transient. Furthermore, the trade-off between the mechanical losses and the transient time can be modified easily by changing the weighting factors of a cost function.

International audience; In order to actively control the power flow in a Dual Active Bridge (DAB) converter, different modulation strategies such as Single Phase Shift (SPS), Triangular Modulation (TRM), Extended Single Phase Shift (ESPS) have been proposed. Each modulation is more suitable for a given range of load power level and has difficulties in working with a wide range of load power level. As these strategies are complementary and their combination can improve the DAB converter yield, in this paper, Finite Control Set Model Predictive Control is used to choose the best modulation strategy at the best moment in order to improve the efficiency of the DAB converter in real time. This choice will be made according to a cost function taking a trade-off of the current across the leakage inductance, the power error and the switching losses.

International audience; This paper focuses on speed-sensorless drive of induction machine without signal injection. To ensure good performances of the speed observer without the disruptive effects of signal injection, it is possible to avoid the unobservable working points which lead to poor speed observation. To do so, the existing methods aim at avoiding the low stator frequencies. They are nonetheless difficult to use for real applications since they lack flexibility and do not take into account some industrial constraints. The approach presented in this paper consists in formulating all the working constraints in order to build a cost function. By minimizing this cost function, the proposed optimal avoidance strategy is more flexible and can be applied for any industrial application.

International audience; In this paper, an original technique for monitoring the aging of supercapacitor energy storage system is proposed. The aging of supercapacitor is represented by the degradation of its internal parameters as the loss of capacitance and the increase of the Equivalent Series Resistance (ESR). This degradation is continuous until reaching the end of life criteria. The proposed approach is based on estimating the current ESR, of each storage system element with a fast control of the balancing circuit present at the terminal of each storage element. The fast control is applied for a short moment and could be applied at any storage system state with no incidence on the system. The information about this current parameter makes the state of health monitoring possible. The analysis is performed using simulation with realistic storage system models in order to demonstrate and validate the effectiveness and the accuracy of the proposed technique. The results presented covers storage system such as supercapacitor but could be also applied to batteries.

International audience; The development of systems-on-chip requires embedded power management solutions due to the large number of power domains. The switched-capacitor voltage regulator is a suitable candidate as capacitors may be integrated whereas inductors still suffer limitations in that respect. Literature covers proposals of optimized power stages and several dedicated controllers for switched-capacitor DC-DC converters. Unfortunately the results do not cover systematic stability analyses. The paper proposes an original and systematic approach for the stability analysis of a switched-capacitor voltage regulator using sampled-data modeling. An application is given for a one-phase converter with a frequency-modulation based controller. The stability of the open-loop and closed-loop model is proposed and can be extended to multi-phase configurations.

International audience; Hybrid Pulse Width Modulation (PWM) techniques select the appropriate PWM sequence that induces either less current distortion or less switching losses or both. The sequence selection is usually based on an off-line sector partitioning. This simple solution freezes unfortunately the design and prevents any on-line evolution. In this article the improved hybrid PWM technique based on Finite Control Set Model Predictive Control (FCS-MPC) enables a sequence selection based on FCS-MPC theory at each sample time. The choice on the finite set of PWM sequences is made through a user-defined trade-off between the minimization of the load current distortion and the switching losses. Simulation and experimental results are presented to support the developed technique and demonstrate appreciable reduction of the losses.

International audience; This paper presents a new control method applied to the electro-pneumatic field. This strategy originates from the hybrid control theory recently developed for the control of asynchronous or synchronous electrical motors, e.g. Retif (2004). The interest of this strategy concerns the possibility of using standard on/off distributors instead of the usual servodistributors (components issued from proportional technology) for the force control of a pneumatic cylinder. Distributor components have less performance but are cheaper than a servodistributor. The aim is to obtain, with a distributor, the same performances as servodistributors on the global system. Based on both cylinder and distributor models, the hybrid control presented here chooses the best state for each on/off distributor to reach the desired force value. Experimental results are presented and discussed.

International audience; The Finite Control Set Model Predictive Control (FCS-MPC) technique is worldwide recognized due to its adaptability and capacity to take into account the discrete characteristics of control systems. However, it shows some limitations when directly used to control power converters, as its variable frequency spectrum, its limited current quality and its low-voltage precision for a given sample time. Therefore this paper presents an improved hybrid Pulse Width Modulation (PWM) technique based on FCS-MPC, that uses the FCS-MPC theory to select the PWM sequence applied on an inverter at each sample time. The choice on the finite set of PWM sequences is made through a trade-off between the minimization of the switching losses and load current distortion. Simulation results are presented to support the developed technique and show some promising results with appreciable reduction of the switching losses.

International audience; A novel integrated digital controller for buck converter based on the direct system-variable calculation is presented. Compared with linear compensators, the discrete-time direct controller is conceived to generate an additional control variable during each switching period that increases the convergence rate when system states change. An all-digital current estimator is adopted to eliminate the use of current sensor. Experimental results verify closed-loop operation at switching frequency up to 4MHz. The dynamic response time for a load current step-up from 0.3A to 0.45A is 23.8μs, and 21.4μs for a step-down from 0.45A to 0.3A. An efficiency of over 75% is maintained over a power range from 29.3mW to 1.12W in which the maximum efficiency of 93.2% is achieved at 1.88V output.

International audience; Power management of mobile digital systems-on-chip necessitates large voltage regulation performances. DC/DC converters used to supply digital cores are facing stringent constraints with respect to load transients, reference tracking and accuracy. The fast transient response offered by sliding-mode control is well suited to DC/DC converters with fast varying load. Fixed switching-frequency is also mandatory for EMI and noise related issues. Fixed-switching frequency sliding-mode control has been experimented as a multi-loop system. There is a necessity to investigate the stability when multi-loops interact and the parameter set for each loop is quite large. The paper details a methodology for the stability analysis of a frequency-controlled sliding-mode DC/DC converter. The proposed stability analysis takes the possible cross-interactions into account and can be used to optimise the DC/DC controller without the limitations of a non-interaction criterion. As a verification a DC/DC converter is implemented in CMOS 130 nm. Experimental results agree with the analysis main recommendations.

For control design of motor driving, to take into account the converter influence, it is necessary to have a converter model with a reasonable simulation cost. This paper presents a three phase static inverter averaged model which takes into account the non-linearities of semiconductor devices. A comparison between simulation and experimental results enables to judge the validity of the averaged model. Current distortion compensation is carried out to show how to improve the control performance by taking into account the dead-time. Our global approach renders possible to yield automatically an analytical averaged model of any converter. Moreover, the averaged model provides analytical compensation of converter imperfections for improving on-line control quality.

International audience; The good performances of model predictive control for power converters were demonstrated for multi-objective control. A relevant example is the multilevel flying capacitor electronic converter in which both capacitor voltages and output current have to be controlled. Moreover, the efficiency is an essential factor in electrical converter design but few papers focused on it in the control point of view. This paper presents a predictive control scheme for a multilevel converter which minimizes a cost function including a loss related term. The inclusion of a large number of elements into the cost function requires the tuning of many parameters. Normalization of the cost function is introduced in order to help the control designer to choose suitable parameters. Simulation and experimental tests prove that a trade-off between efficiency and accuracy can be achieved by controller adjustment.

International audience; Listening music with a headset is now a classical feature of mobile phones. A linear amplifier is still employed to drive the headset as the audio quality must challenge dedicated audio players with somewhat 100 dB of signal-to-noise ratio. This feature must also have the lowest impact on the platform autonomy, size, and cost. A symmetrical power supply is required by such audio amplifiers due to the standard jack connector of headsets. Using an inductive switch mode power supply (SMPS) is the most energy efficient solution to supply audio amplifiers from a battery. Classically, two dc/dc converters are employed to generate the required two symmetrical supply rails from a standard Lithium-Ion battery. It is at the cost of numerous bulky and expensive external components. A solution to reduce the number of external passive components is to consider a single-inductor, bipolar-outputs, (SIBO) dc/dc converter. An early prototype of such a converter has been realized on a 130-nm silicon process and offers primary results, nonoptimal but promising. The feedback control structure is studied based on a small signal model that serves to define the pairing of the loops for designing a decentralized controller. A set of controllers is designed by a pole placement technique and transient performances are demonstrated on audio patterns thanks to a piecewise linear model of the converter. Eighty percent peak efficiency is measured with the primary demonstrator but latter simulation results yield an expected improvement to 90%. The audio specifications appear very constraintful and the proposed SMPS does not meet entirely the latter figures. Limitations are detailed. However, many other applications can benefit from the proposed SIBO dc/dc converter

International audience; Mobile applications necessitate nowadays huge digital resources. Power management of a digital systems-on-chip is based on dynamic voltage scaling. DC/DC converters used to supply the digital system-on-a-chips are facing stringent constraints with respect to load transients, line transients, and reference tracking. Hysteretic control is known as the most convenient control scheme with a fair tradeoff between transient performances, analog implementation and power consumption. Fixed-switching frequency hysteretic control has been experimented as well as full sliding-mode control. Transient performances are reduced due to latencies introduced in the switching frequency control. A new analog implementation of the sliding-mode control is presented here with switching frequency control using a particular analog phase-locked loop but preserve transient performances. The dc/dc converter is implemented in CMOS 130 nm. The switching frequency range has been voluntarily limited and excludes the possible integration of passive components. A hybrid demonstrator is presented with peak efficiency of 89% at 2-W output power.

International audience; This paper proposes a position, speed and load torque observation technique for position control of a non-salient Permanent Magnet Synchronous Motor (PMSM). Unlike the speed control, the position control implies that the motor is often in low speed and standstill conditions. Observability analyze is done to show that the motor is not observable in standstill condition. A high-frequency signal injection is introduced to get round this unobservability. An Extended Kalman Filter is then used to observe the rotor position, speed and load torque by taking into account the injected signal into the observation model. Position tracking and load torque influence are studied on a test bench. Experimental results are provided to confirm the performance and efficiency of the proposed solution.

Mobile applications necessitate nowadays huge digital resources. Power management of digital circuits is based on dynamic strategies to preserve energy. DC/DC converters used to supply the digital core face stringent constraints with respect to load transients. Sliding-mode control is well suited to control buck converters that are subject to high dynamic load and line transients. Fixed frequency sliding-mode control has been experimented. Transient performances or silicon area are negatively affected. A new analog implementation of the sliding-mode control with switching frequency control is presented here. The proposed synchronization scheme does not degrade the intrinsic asynchronous transient performances and is not affected by a significant silicon area penalty. The proposed DC/DC converter is implemented in CMOS 130 nm. The switching frequency is kept constant thanks to the frequency regulation loop. The demonstrator achieves more than 80% efficiency from 3mW to 840mW.

International audience; Power-aware design of digital controller for step-down converter is discussed and compared to a standard analog counterpart so as to verify the feasibility in System-on-Chip. A tri-mode digital controller IC in 0.35 μm CMOS process is presented to demonstrate such a solution including a PID, a so-called quarter PID and a robust RST compensator. The compensators respectively address the steady-state, stand-by and transient modes according to the operating conditions of the step-down converter. An idle-tone free condition for the Σ - Δ DPWM is considered to reduce the inherent tone noise under DC-excitation while generating a quasi-pure modulation signal compared to a traditional approach. Experimental results verify closed-loop performances and lead to a power assessment model suggesting feasible applications.

A digital current and voltage predictive controller (CVP) is proposed for high switching frequency, low power SMPS. The predictions of the inductor current and capacitor output voltage are performed simultaneously by adopting a flexible PWM pattern that enables dynamic adjustment of the time of the voltage events. The CVP controller preserves the merits of predictive current-mode control and allows to further improve the dynamic performances. With the knowledge of the inductor current, the performances of the CVP controller are analyzed compared to a deadbeat controller. Experimental results of a current sensorless implementation verify better closed-loop performances than those of PID, RST and sliding-mode controllers. The lab-scale prototype implemented in an FPGA supports a switching frequency up to 4 MHz only limited by the discrete buck converter.

This paper presents the application of predictive deadbeat control to the high switching frequency DC/DC Single-Ended Primary Inductor Converter (SEPIC). An extended Kalman observer with load variation estimation is designed to achieve current sensorless operation of the controller. A hybrid Delta-Sigma (Δ-Σ) Digital Pulse Width Modulation (DPWM) is used to effectively achieve 11-bit resolution at high-frequency and reduce the system clock frequency. The proposed DPWM along with the predictive deadbeat control algorithm is validated by using a Virtex-II FPGA. Experimental studies are conducted for a laboratory prototype with switching frequency of 500kHz. Simulation and experimental results prove the performance of the proposed solution.

International audience; A single inductor, double symmetrical outputs, integrated DC-DC converter with analog control has been designed for supply of low power, output-capacitor-less audio amplifiers. Such amplifiers require positive/negative symmetrical voltage supply for driving headphones without common mode on their output voltages. The power stage of the converter use a single external inductor, 3 external capacitors and five integrated power switches to produce two symmetrical bipolar outputs. This circuit permits to make the economy of using a combination of two separate converters for generating both the positive and the negative output voltage. The benefits are a low number of external components and IOs, and reduced silicon area. The control of the output voltages is accomplished by two feedback loops operating in PWM. A primary prototype has been fabricated in CMOS 130nm process for Continuous Conduction Mode (CCM) and achieves 80% peak efficiency at 360 mW output power and 1.6 MHz switching frequency. This prototype validates the simulation results about the analog control strategy and the integration of the whole power stage and control. Improvements are presented in order to increase the efficiency up to 90% at full load. The operation in Discontinuous Conduction Mode (DCM) and Pulse Skipping (PSK) are introduced to improve the efficiency for low output power. The electrical implementation of DCM and some simulation results are presented. Light-load efficiency is improved to around 60%

International audience; The paper deals with the dynamic identification in noisy environment of a class of nonlinear systems whose parameters depend linearly on the unknown parameters. The identification algorithm is based on an extended sliding modes observer and a least square estimation using an instrumental variable technique. The study of the measurement noise effect on the measured signals shows that the proposed solution is consistent. An application on a permanent magnet synchronous machine highlights the efficiency of the technique.

This paper presents the application of fixed frequency (or indirect) Sliding Mode Control (SMC) to the DC-DC Single-Ended Primary Inductor Converter (SEPIC) where the switching frequency is in the range of hundreds of kHz and consequently a FPGA is required. Due to the constraint of FPGA, only the output voltage is measured. As the proposed SMC requires the knowledge of all the states, an extended Kalman observer is introduced to estimate the state vector and the load variation. A multi-bit second-order Δ-Σ modulator is used to effectively achieve 11-bit resolution at high-frequency through only a 8-bit hardware Core Digital Pulse - Width - Modulator (DPWM). Simulation and experimental studies are conducted for a laboratory prototype with switching frequency of 500 kHz. Results proved the performance of the proposed solution.

Taking advantage of FPGA's attractive features, this paper presents an improved digital pulse-width-modulator (DPWM) based sliding-mode controller (SMC) for boost con- verter that effectively alleviates the quantization effects. The dithering Multi-stAge-noise-SHaping (MASH) DPWM is intro- duced exhibiting a better idle tone suppression effect that achieves relatively higher effective number of bit (ENOB). The Linear Feedback Shift Register (LFSR) replaces the cumbersome pseudo-random generator as the dither generation module that is proven to be more effective. The SMC with the proper sliding coefficients aiming at a better dynamic response than the traditional PID controller cooperates with our proposed DPWM. Two individual boards, an analog-to-digital converter (ADC) and a boost converter, connecting to a Virtex-II FPGA platform compose a close-loop test environment. Experimental results verify the switching-mode-power-supply (SMPS) close-loop operation at 1MHz switching frequency with an 11-bit effective DPWM resolution.

International audience; This study presents a feedback linearization strategy and a robust controller to permit a decoupling and regulation of the motor states in order to assure a good dynamic performance and stability of the global system. As the control required the knowledge of the instantaneous flux of the rotor and the rotor parameter estimation can improve the control quality, a six-dimensional discrete-time extended sliding mode observer is proposed for on-line estimation of rotor fluxes and rotor time constant. The simulation results for a 1.8 kW induction motor are presented to illustrate the validity and the high robustness of the proposed approach against parameter variations and disturbances.

In this paper, the application of the Sliding Mode Theory, in terms of observer and control design, to the DC-DC Single-Ended Primary Inductor Converter (SEPIC) is investigated. The choice and influence of the sliding surface regarding the state vector is presented. Usual sliding surfaces chosen to control other high order DC-DC converters are found not to work on the SEPIC. Thus, other surfaces are proposed here and which require the presence of more than one state variable. Also, an extended sliding mode observer is proposed to estimate the state vector. Results are experimentally validated.

International audience; This paper presents a theoretical study with experimental validation carried out on a DC-DC SEPIC converter operating in continuous conduction mode (CCM). Two dynamic modeling techniques are adopted and various aspects of the converter's operating modes are analyzed. Simulations of transient and frequency responses are verified with experimental results. A PI control law is used to validate responses to load and reference voltage variations with parasitic losses taken into account. An in-depth analysis of the effects of unstable zeros of the transfer function, from the duty cycle to the output voltage, on the implementation of control laws is also presented. The frequency behavior of the converter along with the stability margins are found to be widely influenced by load resistance and duty cycle variations.

International audience; A sliding mode control (SMC) algorithm dedicated to switching mode power supply (SMPS) is validated experimentally in a FPGA. A constant high switching frequency is obtained using an hybrid digital pulse width modulator (DPWM). The proposed SMC strategy cooperates with an off-chip ADC and the hybrid DPWM takes advantage of a digital clock manager (DCM) and a counter-comparator based DPWM with a Multi-stAage-noise-SHaping (MASH) ¿-¿ modulator. Experimental results verify closed-loop operation at switching frequency up to 4 MHz only limited by the discrete SMPS and its dynamic response less than 30 ¿s. Simulation results show that the complete digital controller chip in 0.35 ¿m CMOS process takes 0.72 mm2 of silicon area and the current consumption is roughly 100 ¿A/MHz for a dynamic response of 16 ¿s.

International audience; This paper presents a fully synthesizable digital controller for high-frequency low-power DC-DC switching mode power supply (SMPS). Key module of the digital controller is a Hybrid digital pulse-width modulator (DPWM), which takes advantage of Digital Clock Manager (DCM) phase-shift characteristics available in FPGA resource and combines a counter-comparator with multi-bit Delta-Sigma (Delta-Sigma) Multi-stAge-noise-SHaping (MASH) modulator. A digital controller which includes the proposed Hybrid Delta-Sigma DPWM and a digital PID algorithm is experimentally verified using an FPGA on a high-frequency low-power discrete synchronous buck converter. Experimental results with constant switching frequency up to 4 MHz validate the functionality of the proposed digital controller. In addition, the digital controller is implemented in a 0.35 mum standard CMOS.

This paper presents a control scheme for a multilevel multi-cell converter. For this type of converters, load current and capacitor voltages must be jointly controlled. Moreover the real-time constraint is important. This constraint leads us to propose a control based on a simplified state-space model. The model allows predicting the state vector evolution for every converter configuration. The control algorithm directly determines the converter switching state which minimizes a simple cost function. A normalization of the state variables is proposed for the cost function calculation in order to ensure a trade-off between the tracking of the load current and the tracking of the capacitor voltages. The proposed control scheme is detailed and compared with a classical control scheme with simulations. Finally, experimental results are presented to show the effectiveness of the proposed method.

This paper presents the experimental results-based comparison of two predictive current controls (PCC) for permanent magnet synchronous machines (PMSM) drives. The first tested control scheme is based on a model including the inverter and the PMSM and taking into account the discrete nature of the inverter leg states. It predicts the future evolution of the currents for each possible configuration of the inverter. The switching state which minimizes a given cost function is selected. The selected inverter state is applied during the next sampling time. The second tested control scheme uses a model of the PMSM to predict the output voltages which allow to reach desired currents after one modulation period. A new algebraic method is presented to directly compute the duty cycle of each leg. Then a modulator generates the corresponding gate drive pulses of the inverter. These two control schemes are tested with a 1.6 kW PMSM drive at several operating points during steady state and transient operation. A detailed comparison of results is given. Advantages and drawbacks of each method are discussed.

This paper presents a predictive current control (PCC) strategy applied to an induction motor (IM) drive. In contrast to conventional vector control, where the inverter is not taken into account by the controller, the PCC considers the state of the inverter as a discrete control variable. Based on a simplified state space model of the IM and the inverter, the proposed control scheme calculates the state vector evolution direction in the d- and q-reference frame for all possible switching states of the inverter. The switching state which minimizes a given cost function is selected and is applied during an adapted duration which is calculated for each computation cycle. As the control requires the knowledge of the instantaneous rotor fluxes and in order to improve the control robustness, a reduced-order extended high gain observer is proposed for estimation of rotor fluxes and inverse rotor time constant. The simulation results validate the observer. The controller is implemented on a 5.5 kW IM drive with a digital-signal-processor (DSP) on a DSpace1103 board. Experimental results show the effectiveness and the performances of the proposed control.

Nos remerciements à IEEE pour l'autorisation de mise à disposition du papier complet. © IEEE Copyright Notice : Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.; International audience; This paper presents the implementation of a hybrid-control strategy applied to a permanent-magnet synchronous-motor (PMSM) drive. Hybrid control is a general approach for control of a switching-based hybrid system (HS). This class of HS includes a continuous process controlled by a discrete controller with a finite number of states. In the case of ac motor drives, in contrast to conventional vector control like proportional-integral control or predictive control, where the inverter is not taken into account by the controller, hybrid control integrates the inverter model and considers the state of the inverter as a control variable. It allows to obtain faster torque dynamics than vector-control algorithms. The hybrid control algorithm requires both computing velocity for real-time implementation and code flexibility for management of low-performance functions and analog-digital interfaces. Codesign appears as a promising methodology for partitioning hybrid-control algorithm between software (flexible) and hardware (velocity) while taking care of overall time constrains. In this paper, the implementation of hybrid-control algorithm for a PMSM drive is performed through a codesign approach on an Excalibur board, embedding a CPU-core (Nios-2 by Altera) inside an APEX20KE200EFC484-2X field-programmable gate array. The partitioning of software and hardware parts is explained. Experimental results show the effectiveness of the implementation. Performances, advantages, and limitations are discussed.

Analogue control of monolithic DC/DC converters is technologically coming to a limit due to high switching frequency and a request for large regulation bandwidth. Digital control is now experimented for low-power low-voltage switch-mode power supply. Digital implementation of analogue solutions does not prove real performances. This paper compares a classical digital controller to a candidate alternative strategy. Sensitivity functions are used to compare controller performances. An off-line approach using fuzzy logic to quantify controller performances and a genetic algorithm to obtain an optimal controller is presented. A so-called RST algorithm optimized with this approach shows better performances.

Les systèmes électrotechniques et plus particulièrement l'association d'un convertisseur statique avec une charge constitue un système dynamique hybride pour lequel la commande est sujette à des contraintes de calcul en temps réel sévères (quelques centaines de microsecondes). La spécificité de ces systèmes hybrides nous a conduits à proposer un modèle simplifié dont la validité est restreinte à l'horizon de décision et une commande pouvant satisfaire à ces contraintes. Diverses stratégies de commande ont été testées et validées sur des démonstrateurs en temps réel sur les applications suivantes : convertisseur multicellulaire, machine synchrone, machine asynchrone et vérin électropneumatique. Electrotechnical systems and specially the association of a static converter to a load constitute a dynamic hybrid system. Real-time constraints are important for the control of these systems (a few hundreds of microseconds). Specificities of these hybrid systems lead us to propose a simplified model with validity limited to the calculation occurrence and control approach which can fulfil these constraints. Different control strategies were established, tested and validated on real-time experimental equipments such as multi-cell converter, synchronous and asynchronous machine and pneumatic cylinder.

International audience; Analogue control of monolithic DC/DC converters is coming to a limit due to high switching frequency and a request for large regulation bandwidth. Digital control is now experimented for low-power low-voltage switch-mode power supply. Digital implementation of analogue solutions does not prove real performances. Other digital controllers have been experimented but applied to discrete converters. This paper compares a classical digital controller to a possible alternative strategy. Sensitivity functions are used to compare controller performances. RST algorithm determined by robust pole assignment shows better performances