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This study presents a computationally efficient model predictive torque control (MPTC) method for permanent magnet synchronous machines (PMSMs). The existing MPTC methods require solving complex optimization problems in iterations; this approach is computationally demanding. In contrast, the proposed MPTC transforms the optimization problem into two subproblems and derives the corresponding solutions explicitly using numerical techniques, which entail linearization of the torque function and current constraint; the proposed approach can significantly reduce the computational burden. Additionally, the proposed MPTC does not involve any control gains and weighting factors; hence, gain tuning is not required for the proposed MPTC. These features are advantageous when implementing torque control. Using a 4-kW PMSM drive, the effectiveness of the proposed MPTC is demonstrated both numerically and experimentally in terms of dynamic performance and computational efficiency. This is realized by comparing the proposed method with the existing methods.

This study solves the attitude stabilization problem of 2-degree-of-freedom (2-DOF) helicopters by robustly assigning the variable-performance to the closed-loop system in the presence of the model-plant mismatches and load variations. The proposed approach re-formulates the original problem to a surface stabilization one which yields three contributions: a) the proposed attitude velocity observer forms a conventional Luenberger-type observer incorporating the parameter-independence and estimation gains specifically designed for causing the pole-zero cancellation, b) the pole-zero cancellation velocity control loop makes it possible to accomplish the surface stabilization task with the first-order closed-loop order, and c) the closed-loop analysis results demonstrate the attractive properties of the exponential performance recovery and convergence. The effectiveness of the proposed technique is verified using the experimental platform provided by the Quanser AERO.

This paper exhibits a novel solution to the speed tracking problem of permanent magnet synchronous motors (PMSMs) subject to parameter and load uncertainties. The resultant cascade structured solution is designed to give the speed tracking capability to the closed-loop system, which depends on only the nominal PMSM parameter information. This study provides two novel contributions: a) a variable performance target system describing the desired perfect tracking nature with boosting feedback gains, and b) a robust control law forcing the target tracking system to be invariant through the utilization of active-damping pole-zero cancellation and disturbance observer techniques. The prototype 1-kW PMSM experimental set confirms the practical advantages of the proposed system compared to the recent auto-tuning controller.

This study suggests an intelligent position-tracking control algorithm for rover vehicles considering actuator (DC motor) dynamics. The parameter and load uncertainties in the vehicle and DC motor dynamics are explicitly handled by modifying the original open-loop system dynamics. The proposed controller forms the conventional multi-loop structure including disturbance observers (DOBs) for each loop. The features of this study fall into three parts: first, the learning part from the real-time feedback gain mechanism (named the self-tuner) in the closed-form for outer loop; second, the adaptation part from the online wheel radius estimation securing the outer-loop control accuracy; and third, the parameter-independent angular acceleration observer-based pole-zero cancellation DC motor speed controller without current feedback considering the inner- and outer-loop vehicle control algorithms. Experimental evidence is also provided to demonstrate the practical merits of the proposed technique with the use of the TETRIX, myRIO-1900, and LabVIEW.

This study aims to accomplish the output voltage tracking task for buck converters without current feedback, diminishing the performance degradation from model-plant mismatches and load variations. The following contributions overcome these difficulties: a) the combination of Luenberger and disturbance observer (DOB) techniques for a parameter-independent voltage-derivative observer, b) the pole-zero cancellation control incorporating the DOB and active-damping injection techniques, and c) the exponential convergence guarantee to the target tracking system subject to the variable convergence rate mechanism. Convincing experimental evidence confirms the effectiveness of proposed tracking control using a prototype 3-kW buck converter control system.

This study suggests a dynamic current cut‐off frequency‐based pole‐zero cancellation speed controller for permanent magnet synchronous motors (PMSMs). The proposed self‐tuning algorithm automatically increases the current cut‐off frequency during only the transient periods and restores it as approaching the steady‐state operation. The outer loop control injects the active damping effect, resulting in a closed‐loop order reduction by pole‐zero cancellation from the particularly structured feedback gain. These two benefits contribute to the following advantages: (a) lowering the steady‐state current cut‐off frequency to improve the relative stability margin and (b) securing the capability of assigning the desired cut‐off frequency to both the inner and outer loops in the first‐order low‐pass filter form. A 500‐W PMSM experimental prototype platform confirms the effectiveness of the proposed controller.

This article briefs on an advanced observer-based proportional-type control scheme that stabilizes the attitude and regulates the position of two-wheeled mobile balancing robots. The robot parameter and load uncertainties are under consideration. There are three main differences from previous results: (a) the development of coordinate transformation for securing the applicability of the proposed nonlinear controller design technique, (b) the pole-zero cancellation parameter-independent observers for estimating the wheel and yaw angular velocities, and (c) the guarantees of performance recovery and offset-free properties through the replacement of integrators via observer-based disturbance observers. The practical merits of the closed-loop analysis are confirmed by performing experiments with a LEGO Mindstorms EV3 operated by MATLAB/Simulink.

This article presents an advanced parameter-free velocity observer-based nonlinear decentralized tension control scheme for roll-to-roll systems governed by nonlinear dynamics. The system parameter uncertainties and nonlinear dynamics yield the second-order perturbed nominal open-loop systems, which are used for devising the web velocity and tension control law for each station. The features of this result are summarized as follows: (a) the tension-derivative observers including the disturbance observer mechanism as a subsystem, (b) the observer-based active-damping pole–zero cancellation velocity error stabilizer for each tension loop, and (c) the closed-form nonlinear feedback gain boosters and exponential surface stabilizers to secure the improved transient performance and robustness for web velocity and each tension loop. The various simulation results based on MATLAB/Simulink show both the qualitative and quantitative advantages of the proposed technique.

This brief gives an advanced observer-based attitude stabilization mechanism for quadcopter applications subject to parameter and load uncertainties. The results show two features: first, a parameter-independent pole-zero cancellation angular velocity observer for reducing the number of sensors, and second, state and disturbance observer-based pole-zero cancellation control for improving the robustness by guaranteeing the performance recovery property. Numerical evidence from realistic simulations confirms the effectiveness of the resultant closed-loop system.

With the proposed technique, a controlled brushless DC motor can robustly track the desired trajectory, while estimating angular acceleration, to remove current feedback. The controller design task does not require true motor parameters and load information using the standard disturbance observer design approach. The first feature is that a parameter-independent angular acceleration observer is devised to avoid direct differentiation of the speed measurement. The second one is that active-damping pole-zero cancellation control stabilizes the surface, thereby describing the desired first-order tracking system dynamics. The prototype 50-W BLDCM control system experimentally evaluates the speed-tracking and positioning performances.

In this article, the position-tracking problem for magnetic levitation (MAGLEV) systems is addressed by handling the model nonlinearities and uncertainties of parameters and loads. The first feature is devising a variable cut-off frequency algorithm enhancing the transient tracking performance by updating the feedback gain accordingly. The second is introducing the disturbance observer (DOB) improving the disturbance attenuation performance with the offset-free property, which corresponds to the replacement of tracking error integrators. The simulation results numerically demonstrate the effectiveness of the proposed technique considering model-plant mismatches and load variations.

This study proposes an advanced current and position sensor fault diagnosis mechanism for permanent magnet synchronous motor (PMSM) applications. Machine nonlinear dynamics as well as parameter and load uncertainties are addressed. The features of the results of this study are summarized as follows: 1) a proportional-type full-state observer is combined with a disturbance observer to deal with the model uncertainties, 2) a partial optimal process is introduced for determining the observer gain, 3) the concept of normalized residuals is introduced for fault diagnosis criteria, and 4) a closed-loop analysis of the convergence, performance recovery, and offset-free guarantee is provided. The performance recovery property makes the proposed algorithm robust to parameter uncertainties and load variations, and sensitive only to sensor faults. In addition, the location and type of sensor faults can be identified by the fault diagnosis criteria using the normalized residuals. The performance of the sensor fault diagnosis algorithm was experimentally verified under several credible scenarios using a 7.5-kW PMSM.

This brief proposes an advanced positioning law for hybrid-type stepper motors with two main features: a) a combination of pole-zero cancellation-based proportional-integral control with disturbance observers and b) a variable manifold forced to be exponentially convergent by the proposed control law. The parameter and load uncertainties are also explicitly handled in the controller design task. The practical improvement is confirmed with experimental evidence using a 10-W stepper motor controlled by two dual half-bridge drivers and a 32-bit digital signal processor.

This paper suggests a novel model-based nonlinear DC motor speed regulator without the use of a current sensor. The current dynamics, machine parameters and mismatched load variations are considered. The proposed controller is designed to include an active damping term that regulates the motor speed in accordance with the first-order low-pass filter dynamics through the pole-zero cancellation. Meanwhile, the angular acceleration and its reference are obtained from simple first-order estimators using only the speed information. The effectiveness is experimentally verified using hardware comprising the QUBE-Servo2, myRIO-1900, and LabVIEW.

This paper suggests a position-tracking algorithm for the outer-loop through the invariant dynamic surface approach for balancing robot applications. The main feature is to devise a dynamic surface representing the target position-tracking performance with variable cut-off frequency. The proposed controller makes the dynamic surface invariant while updating the closed-loop cut-off frequency accordingly with the self-tuner. The closed-loop properties are rigorously analyzed. The experimental verification result shows that the proposed controller establishes the 48% enhancement of the circular tracking performance in comparison with the feedback linearization method, where the LEGO Mindstorms EV3 is used.

This brief presents an advanced proportional-derivative (PD) voltage control mechanism for DC/DC boost converters suffering from the parameter and load variations. The proposed controller eliminates the requirement for current feedback by designing the first-order observer estimating the voltage derivative without the use of converter parameters, which corresponds to the first contribution. As another contribution, a specific feedback gain structure for PD-loop and the active damping component guarantees the first-order closed-loop transfer function from the reference to the output voltage by the stable pole-zero cancellation. A prototype bi-directional 3-kW boost converter experimentally validates the closed-loop performance of the proposed technique.

This brief presents a novel energy-shaping technique-based speed controller for permanent-magnet synchronous motors (PMSMs) considering machine nonlinearities and load and parameter changes. There are three features: The time-varying damping term is injected into the speed loop, which is automatically updated by the proposed self-tuner. The disturbance observers are designed for both the speed and current loops to achieve better disturbance rejection performance with removal of offset errors without the use of tracking error integral actions. Furthermore, the closed-loop analysis result is provided to demonstrate its beneficial closed-loop properties. The practical advantages are experimentally verified in several convincing scenarios with a prototype 500-W PMSM driven by a three-phase inverter.

This paper develops an observer-based positioning scheme for ball-beam systems considering actuator dynamics. The practical constraints are handled systematically, including the mechanical dynamical nonlinearities, mismatched load disturbances, and parameter uncertainties. This result provides contributions as follows. First, parameter-independent observers exponentially estimate the ball velocity, motor speed, and its acceleration to remove the velocity, motor speed, and current feedback. Second, the auto-tuner automatically adjusts the desired closed-loop input-output behaviors to update its cut-off frequency in the transient operations. Third, observer-based active damping injection reduces the closed-loop ball position and actuator speed dynamics to 1 by pole-zero cancellation. Finally, disturbance observers act as a dynamic compensator by estimating the disturbances from model-plant mismatches such as dynamic nonlinearities, mismatched load disturbances, and parameter variations. The experimental study verifies the applicability of the proposed technique using the Quanser Ball-Beam hardware driven by an SRV02 servomotor.

This brief proposes a proportional-type angle filter with the variable feedback gain mechanism for motor drives using the encoder for angle feedback. In this case, the angle measurement suffers from discontinuity that has to be made continuous through low-pass filters and observers. There are three features. The first designs a real-time feedback gain update rule to improve the closed-loop filtering performance by magnifying the feedback gain in transient periods. The second introduces the disturbance observer (DOB) in the resultant proportional-type feedback filter for enhanced disturbance attenuation against the speed variations. The third proves the useful properties of the filtering error convergence and performance recovery by investigating the filtering error dynamics. A prototype 500-W permanent-magnet synchronous motor (PMSM) drive system validates the practical advantages of the proposed technique.

The proposed observer-based control mechanism solves the trajectory tracking problem in the presence of external disturbances with the reduction in sensor numbers. This systematically considers the quadcopter nonlinear dynamics and parameter and load variations by adopting the standard controller design approach based on a disturbance observer (DOB). The first feature is designing first-order observers for estimating the velocity and angular velocity error, with their parameter independence obtained from the DOB design technique. As the second feature, the resultant velocity observer-based control action including active damping and DOBs secures first-order tracking behavior for the position and attitude (angle) loops through pole zero cancellation, thereby forming a proportional–derivative control structure. Closed-loop analysis results reveal the performance recovery and steady-state error removal properties in the absence of tracking error integrators. The numerical verification confirms the effectiveness of the proposed mechanism using MATLAB/Simulink.

This article proposes intelligent nonlinear web tension and velocity controllers for roll-to-roll printing systems. The introduction of the perturbed machine model makes it easy to handle machine nonlinearities and parameter variations, simultaneously, with the simple static and first-order dynamic compensator. The feedback gains of web tension and velocity are automatically updated by the proposed self-tuner, which corresponds with the first feature of this article. As the second feature, the introduction of disturbance observers in place of the regulation error integrators provides an improved disturbance rejection performance and offset-free property, which is rigorously analyzed based on the Lyapunov stability criterion. The closed-loop performance improvement is numerically demonstrated under various scenarios using MATLAB/Simulink.

This study devises a variable-performance control law for rover vehicles servoing velocity and pitch angle commands. This considers both vehicle and actuator dynamics as well as load and parameter variations. The main merits are summarized as follows. First, the proposed auto-tuning law magnifies the feedback gain for desired systems to achieve transient performance improvement with the convergence property guarantee. Second, the collaboration of pole-zero cancellation controller and disturbance observers eliminates over/undershoots through closed-loop order reduction by a special form of feedback gain. Beneficial closed-loop properties are also derived from the closed-loop analysis. The prototype rover vehicle built with TETRIX and MyRIO-1900 experimentally validates the closed-loop performance and robustness improvement.

This study presents a solution to the position stabilisation problem for non-linear magnetic levitation systems using the only position measurement. This considers parameter and load variations without the use of current and velocity feedback. The features are given as follows: (i) the removal of current and velocity feedback by the proposed first-order state estimators without system parameters, (ii) securing of improved closed-loop robustness from the combination of active damping and specified feedback gain with the closed-loop system order reduced to 1 and (iii) proof of performance recovery and offset-free in the absence of regulation error integral actions. The numerical simulations verify the performance and robustness improvements through realistic scenarios.

This study addresses the position-tracking problem for hybrid-type stepper motors in the rotational $d-q$ coordinate system. The proposed controller aims to govern position behavior with the desired low-pass filter from the reference (input) to the position (output). A perturbed form of machine dynamics is adopted to handle both parameter variations and load uncertainties and the control law has two main advantages. First, the real-time auto-tuner increases the closed-loop cut-off frequency during transient periods and restores it to its nominal value as it approaches the steady state. Second, disturbance observers improve the closed-loop robustness against high-frequency disturbances and ensure the offset-free property without additional integral actions. The experimental results validate the practical advantages from the proposed controller with a 10-W prototype stepper motor control system.

This brief exhibits a nonlinear self-tuning position stabilization algorithm for ball-beam system applications under the consideration of parameter uncertainties and actuator dynamics.; there are two major contributions. First, a first-order ball velocity estimator is proposed using only the ball position feedback without dependence on system parameters. Second, the resulting nonlinear controller incorporates the time-varying feedback gain driven by the proposed self-tuner. Third, a first-order disturbance observer (DOB) is introduced to remove the high-frequency disturbance attenuation performance. The various simulation results-based-on MATLAB/Simulink validate the practical merits of the proposed scheme.

This study presents an advanced algorithm for controlling the web longitude and tension of nonlinear roll-to-roll systems in the form of a cascade structure. Parameter variation and disturbance attenuation problems are addressed systematically. The features of this article are divided into two parts. First, active damping terms are injected to stabilize the system nonlinear dynamics so that the first-order closed-loop transfer functions are obtained for each loop via pole-zero cancelation. Second, disturbance observers are introduced to ensure the performance recovery property by attenuating the disturbances from the model-plant mismatches. The closed-loop system is numerically emulated using MATLAB/Simulink to show the effectiveness of the proposed technique.

In this article, we deal with the one-step time-delay problem in power converter and motor drive system applications implemented by the digital signal processor. For these wide applications, a novel one-step time-delay compensation algorithm is proposed, comprising a standard Luenberger-type observer including a learning algorithm and disturbance observer (DOB). The first novelty is to suggest the learning algorithm automatically determining the observer feedback gains according to the estimation error magnitude. The second is to introduce DOBs with estimation error integrators for removing the steady-state estimation errors, removing the additional adaptive and nonlinear damping compensation terms. The closed-loop observer behaviors are rigorously analyzed to present useful properties. The experimental data obtained using a 3-kW prototype dc–dc boost converter validates the effectiveness of the proposed algorithm.

This brief proposes an auto-tuning proportional-type synchronization controller for dc motor speed applications with consideration of parameter and load variations. The proposed algorithm is comprised of two parts: a proportional-type speed tracking controller with a disturbance observer (DOB) and second a synchronizer driven by an auto-tuning algorithm. The first feature is to propose an auto-tuning synchronizer to reduce synchronization error during transient operations. The second is to introduce a DOB so that the proportional-type controller guarantees tracking and synchronization performance recovery without offset error. Experimental data is provided to convincingly show the effectiveness of the suggested scheme using a 50-W dual dc motor drive system.

This paper presents a nonlinear tracking controller including the cutoff frequency adaptation algorithm for quadcopters without the use of true plant parameters. This study makes two contributions. First, an adaptation algorithm automatically updates the closed-loop cutoff frequency by updating the feedback gains. Second, a nonlinear control law renders the closed-loop system to guarantee the exponential performance recovery and offset-free properties, while only using the proportional component of tracking errors. The numerical verifications are performed to verify the closed-loop performance improvement from the proposed controller with MATLAB/Simulink.

This letter devises a novel signal-filtering technique subject to the feedback structure without the exact source signal dynamics information. The main idea of this result is comprised of two parts: first, the combination of the Luenberger and disturbance observer design techniques to improve the disturbance rejection capability in the feedback structure; second, the closed-form filtering gain-boosting mechanism updating the gain into the direction of the filtering error reduction. It is experimentally confirmed that the proposed filter contributes to lowering the current regulation performance degradation level from the filtering performance improvement using a 500-W permanent-magnet synchronous motor driven by the three-phase inverter.

This paper presents a velocity-sensorless decentralized tension control scheme without true machine parameter dependence for roll-to-roll printing machines. Both the nonlinear nature and parameter uncertainties are taken into account the development task. As the first merit, the proposed observer eliminates the requirement of velocity feedback without any plant information even the nominal parameters. The introduction of the active-damping with the estimated state reduces the closed-loop system order to 1 by the pole-zero cancellation using the specified feedback gains. Finally, the disturbance observer (DOB) replaces the regulation error integrators with the closed-loop robustness improvement against the high-frequency disturbances. The MATLAB/Simulink-based simulations validate the effectiveness of the proposed decentralized scheme.

In this brief, a novel nonlinear tracking control law is presented for dc/dc boost converter voltage control applications through the energy-shaping approach. The first feature is to devise a self-tuner to update the invariant surface according to the output voltage-tracking error. The second is to prove that the exponential convergence and performance recovery properties without steady-state errors under the use of the nominal parameter information of converters. A 3-kW prototype dc/dc boost converter is adopted for experimental verifications of the proposed controller.

This study suggests a non-linear output voltage tracking controller for DC/DC boost converters in the form of a classical cascade control structure. Non-linearities in the converter dynamics as well as parameter uncertainties and load variations are considered. The first contribution of this study is the design of an auto-tuner, which automatically adjusts the control gain according to the output voltage error to enhance transient performance. The second contribution involves proving that the closed-loop system ensures the performance recovery without any steady-state errors in the presence of parameter and load variations. The effectiveness of the proposed algorithm was verified through experimental investigations using a 5 kW prototype DC/DC boost converter.

This paper exhibits a robust speed controller equipped with a self-tuner for permanent magnet synchronous motors (PMSMs), taking nonlinearity and model-plant mismatches into account. The first contribution of the proposed technique is designing a self-tuner for updating the cutoff frequency of target speed dynamics. The second one is rendering the closed-loop system to recover the target tracking performance and remove the offset errors in the absence of integrators. A 5-kW prototype interior PMSM is used to experimentally verify the effectiveness of the proposed technique.

This study suggests a non-linear control algorithm for the exciter controlling a single-machine infinite-bus system, considering the non-linear dynamics with parameter and sudden input power variations. This study provides three contributions: (i) an estimation algorithm is designed to estimate the power angle operating point for the terminal voltage to be regulated to its desired value, incorporating the disturbance observer (DOB); (ii) a DOB-based proportional-type non-linear stabilising algorithm is systematically derived using the estimated power angle operating point; and (iii) it is rigorously shown that the proposed proportional-type non-linear controller always removes the steady-state errors without integral actions for error variables. The simulation results confirm the effectiveness of the proposed technique under several transmission line fault scenarios.

In this paper, a robust position tracking controller is proposed using an invariant dynamic surface approach in a cascade control system structure. There are two main contributions. The first is to design a dynamic surface giving the desired tracking-performance with a time-varying cutoff frequency automatically adjusted by the proposed auto-tuner, which can enhance the reliability of the resulting control system. The second is to derive the inner- and outer-loop control laws driving the closed-loop trajectories to the dynamic surface, incorporating a disturbance observer with the use of only nominal plant parameters. A reduction of plant parameter dependence can be accomplished by the second contribution. The realistic simulation results confirm the advantages of the proposed technique.

This brief proposes an outer-loop control mechanism for two-wheeled mobile balancing robot position-tracking control system applications. The proposed outer-loop controller is comprised of two parts: 1) a simple proportional-type feedback controller and 2) the self-tuning algorithm. The cut-off frequency of closed-loop system is increased by the self-tuning algorithm to enhance the position-tracking performance in transient periods, which is the main contribution of this brief. Moreover, it is rigorously shown that the closed-loop system exponentially recovers the desired position-tracking performance. The closed-loop performance improvement is experimentally verified using the LEGO Mindstorms EV3 with MATLAB/Simulink software.

This brief proposes an output voltage-tracking controller for dc/dc boost converters, ensuring the target closed-loop performance recovery property. The proposed method is designed via a multivariable approach, not a cascade method, accounting for the nonlinearity in the converter dynamics and plant-model mismatches. A nonlinear observer is constructed to exponentially identify the disturbances caused by the plant-model mismatches without using the true parameters of the converter. The resulting observer acts to recover the target closed-loop performance by estimating and canceling the disturbances, besides removing steady-state errors. Simulations and experiments are performed to verify the effectiveness of the proposed method by using a 3-kW dc/dc boost converter.

This article exhibits an output voltage-tracking control algorithm incorporating a self-tuning algorithm and disturbance observers (DOBs) for dc–dc boost converters without tracking error integrators, considering model nonlinearities, parameter variations, and load uncertainties. The proposed algorithm is designed such that it forces the output voltage to track its target trajectory driven by a time-varying low-pass filter (LPF), despite model-plant mismatches. This paper makes two main contributions. First, it constructs the self-tuning algorithm by updating the closed-loop cut-off frequency in the time-varying LPF to improve the transient tracking performance. Second, it embeds first-order DOBs in the proportional-type nonlinear controller to achieve both performance recovery and the offset-free properties. The experimental verifications are carried out to illustrate the effectiveness of the closed-loop system driven by the proposed technique with a 3-kW prototype dc–dc boost converter; the 46% improvement of the tracking performance is observed, compared with the conventional feedback-linearization controller.

This study suggests a proportional-type output-voltage control algorithm of a three-phase inverter for uninterruptible power supply applications with performance-recovery and offset-free properties. It makes the two contributions. The first one is to introduce first-order disturbance observers (DOBs) so as to exponentially estimate disturbances originating from model-plant mismatches. The second one is to rigorously prove that the proposed proportional-type feedback-linearising controller equipped with DOBs guarantees performance-recovery and offset-free properties. The experimental results conducted in this study, which uses a 10 kW three-phase inverter with an output capacitor, confirm that the closed-loop performance is satisfactory in both transient and steady-state periods.

In this paper, a robust output voltage-tracking algorithm is proposed for dc/dc boost power conversion systems based on a variable invariant manifold. A systematic multivariable approach, considering not only nonlinearity but also the parametric uncertainties, is used for deriving the control law. The proposed method has two features. First, a variable cut-off frequency algorithm is constructed to automatically adjust the invariant manifold, improving the transient output voltage-tracking performance. Second, nonlinear disturbance observers are introduced to enable the control law to exponentially recover the desirable tracking performance without any offset errors in the variable invariant manifold. The performance of the proposed technique is experimentally confirmed with a 3-kW dc/dc boost power conversion system.

This paper deals with the reduction of torque ripple in a PMSM (permanent magnet synchronous motor) drive using disturbance observer based control. The current ripple is periodically synchronized to the position of the rotor in the form of distorted back-EMF voltage. Therefore, the current ripple is concentrated on the rotation frequency and integral multiples in the frequency domain. In this paper, a method is introduced to reduce the current ripple while maintaining reference tracking performance without a significant change of the controller by intensively increasing the disturbance suppression performance of the frequency band corresponding to the current ripple. The proposed method is verified that a steady-state 58% ripple reduction in 500W SPMSM in the experiments.

In this paper, a new method is proposed for the real-time estimation of the full parameters of a permanent magnet synchronous motor (PMSM) that is based on the stator current ripple model. By introducing the stator current ripple model together with the known two state equations for the $d$ - and $q$ -axes currents, we resolve the rank deficiency problem, thus enabling real-time full parameter estimation even in the steady state. A signal processing technique for removing adverse effects from noises and uncertainties existing in the stator current ripple measurement is also presented. The efficacy of the proposed method is verified by simulation on a 15-kW PMSM, and both the proposed and conventional methods are compared.

This study presents an advanced current control of permanent magnet synchronous motor (PMSM) aiming for improved transient performance over a wide speed range. While the conventional current control scheme based on proportional-integral controllers often shows a degraded transient performance in high-speed operation where the control inputs are almost saturated, the proposed scheme uses a proportional current controller in combination with a disturbance observer, by which the current error converges to zero in an exponential way. This desirable property preserves the transient performance even under the input constraint. A systematic way to determine the optimal control gain considering parameter uncertainties is also provided. A simulation study verifies the efficacy of the proposed scheme using a 20 kW PMSM model in comparison with the conventional current control scheme.

This paper presents an offset-free global tracking control algorithm for the input-constrained plants modeled as controllable and open-loop strictly stable linear time invariant (LTI) systems. The contribution of this study is two-fold: First, a global tracking control law is devised in such a way that it not only leads to offset-free reference tracking but also handles the input constraints using the invariance property of a projection operator embedded in the proposed disturbance observer (DOB). Second, the offset-free tracking property is guaranteed against uncertainties caused by plant-model mismatch using the DOB’s integral action for the state estimation error. Simulation results are given in order to demonstrate the effectiveness of the proposed method by applying it to a DC/DC buck converter.