This paper presents a current-mode adaptively hysteretic control (CMAHC) technique to achieve the... more This paper presents a current-mode adaptively hysteretic control (CMAHC) technique to achieve the fast transient response for DC-DC buck converters. A complementary full range current sensor comprising of chargingpath and discharging-path sensing transistors is proposed to track the inductor current seamlessly. With the proposed current-mode adaptively hysteretic topology, the inductor current is continuously monitored, and the adaptively hysteretic threshold is dynamically adjusted according to the feedback information comes from the output voltage level. Therefore, a fast load-transient response can be achieved. Besides, the output regulation performance is also improved by the proposed dynamic current-scaling circuitry (DCSC). Moreover, the proposed CMAHC topology can be used in a nearly zero RESR design configuration. The prototype fabricated using TSMC 0.25μm CMOS process occupies the area of 1.78mm2 including all bonding pads. Experimental results show that the output voltage ripple is smaller than 30mV over a wide loading current from 0 mA to 500 mA with maximum power conversion efficiency higher than 90%. The recovery time from light to heavy load (100 to 500 mA) is smaller than 5μs.
An optimal uniform-damping ratio controller is developed for the sequential design of a multivari... more An optimal uniform-damping ratio controller is developed for the sequential design of a multivariable control system so that the designed closed-loop poles of the respective multivariable system and reduced-order observer are exactly placed on the negative real axis and/or the boundaries of desired sectors with constant-damping ratios. The functions in the quadratic performance index to be minimized are chosen as a combination of the weighted outputs, reduced states and inputs. Also, the optimal uniform-damping ratio controller is a combination of optimal output-feedback and optimal reduced-order state-feedback controllers. A numerical example is given to demonstrate the design procedure.
The paper presents a methodology to make the load torque disturbance compensation based on the no... more The paper presents a methodology to make the load torque disturbance compensation based on the normal state observer. First, a state feedback controller is designed to achieve a satisfied speed command tracking performance. Then a multi-purpose state observer is constructed to observe the motor states (current and speed), as well as to provide the disturbance compensation. Since the variable of load torque is beyond the motor system state space model, some observation error will be inevitably existed in the observed states. Based on the demonstrated mathematics derivation, the state observation error feedback can be isolated from the exact state feedback. Such a state observation error feedback actually constructs some kind of feedforward compensation for the load disturbance. If the observer gain is picked up appropriately, then the effect of the load torque variation can be considerably compensated, such that the system performance deviation will be greatly attenuated. Both MATLAB/Simulink simulation and dSPACE DSP-based implementation have confirmed its effectiveness in the permanent magnetic synchronous motor (PMSM) drive system.
This paper presents an linear-quadratic-regulatorbased proportional-integral-differential equival... more This paper presents an linear-quadratic-regulatorbased proportional-integral-differential equivalent controller design method for a permanent-magnet synchronous motor. The disturbance rejection is achieved based on a multi-objective observer in which observation error is purposely retained and utilized in load disturbance compensation. This makes disturbance rejection tuning independent of the adjustment for speed command tracking; and the disturbance compensation is an integrated part of the controller output, which reduces the chance of input or state saturation. A robust stability analysis is also included for the modeling error. The proposed methodology is implemented through the dSPACE digital signal processor system, and the experimental result confirms its effectiveness.
This paper discusses the relationship among various recently developed constant state-feedback di... more This paper discusses the relationship among various recently developed constant state-feedback digital redesign methods. Then, for a unity-output feedback system with an analog plant in cascade with an analog controller, the best and simple Chebyshev quadrature digital redesign method is utilized to ®nd new pulse-amplitude-modulated (PAM) and pulse-width-modulated (PWM) digital controllers for eective digital control of the analog plant. The digital controllers are determined from existing or pre-designed analog controllers as in the case of PID controllers for industrial control processes and robotics, phase lead-lag compensators for servo-mechanisms and regulator systems and guidance-autopilots for aircraft and missiles etc. The proposed method provides an alternative methodology for indirect digital design of a continuous-time unity-output feedback system and enables us to accurately and eectively implement an existing or pre-designed cascaded analog controller via a digital controller.
In the models of piezoelectric actuator (PEA) systems, the hysteresis effects are often described... more In the models of piezoelectric actuator (PEA) systems, the hysteresis effects are often described by the concise Bouc–Wen models; however, these models are nonlinear and non-smooth because of the existence of terms which involve the absolute-value function. In particular, a challenging control problem is posed when, due to the properties of certain materials, such absolute-value terms are of high order. This control problem has been rarely studied. This article proposes the use of the approximated scalar sign function (ASSF), which is a numerically stable and differentiable nonlinear function, to represent the hysteresis function, with single-order or high-order absolute-value terms. This innovative step leads to a nonlinear but sufficiently smooth model. Then, a systematic digital design methodology is presented, which involves the following steps: (1) establish an optimal linear model based upon the resulting smooth model, (2) adopt a PI-based analogue controller and (3) apply the prediction-based digital redesign technique for digital implementation. A digital observer is also developed for state reconstruction, and to improve the input disturbance rejection. The positioning control of a PEA system with a high-order hysteretic Bouc–Wen model is implemented to demonstrate the effectiveness of the proposed ASSF based modelling and controller design approaches.
1850 Sheng-Guo Wang et al. and ß0 in (34), then the closed-loop system (7) is robust pole cluster... more 1850 Sheng-Guo Wang et al. and ß0 in (34), then the closed-loop system (7) is robust pole clustering within a vertical strip Cl in (8) for all admissible structured perturbations in (5). Moreover, the control ¡aw (14) is optimal for the matched uncertain linear system (I) with respect to the ...
IEEE TRANSACTIONS ON AUTOMATIC CONTROL^ VOL. AC-27. NO. I, FEBRUARY 1982 ... By using the specifi... more IEEE TRANSACTIONS ON AUTOMATIC CONTROL^ VOL. AC-27. NO. I, FEBRUARY 1982 ... By using the specifity of r and 6, a(A + TC + BF1r) can be rewritten as u(~tr~+~~a)=~(~~~+rc15 ) ... If we note that the observability of (C. A ) implies the one of (CIS, 51 A ! S ) it is clear ...
... pseudo-continuous-time quadratic regulators with pole placement in a specific region Prof. Le... more ... pseudo-continuous-time quadratic regulators with pole placement in a specific region Prof. LeangS. Shieh, PhD Hani M. Dib, MSc Sekar Ganesan, MSc Indexing terms: Computer-aided design, Optimal control, Control systems, Closed-loop systems, Matrix algebra ...
Based on the generalized continued-fraction method for finding the nth roots of real numbers, thi... more Based on the generalized continued-fraction method for finding the nth roots of real numbers, this paper presents a fast computation method for finding the principal nth roots of complex matrices. Computation algorithms with high convergence rates are developed, and their global convergence properties are investigated from the viewpoint of systems theory. *This work was supported in part by the U.S. Army Research Office, under contract DAAG 29-89Km37, and U.S. Army Missile Command, under contract DAAH 01.85C-Alll.
... MULTIVARIABLE CONTROL SYSTEMS TO BLOCK COMPANION FORMS LS SHIEH and S. GANESAN Department of ... more ... MULTIVARIABLE CONTROL SYSTEMS TO BLOCK COMPANION FORMS LS SHIEH and S. GANESAN Department of Electrical Engineering, University of Houston, Houston, TX 77004, USAJM NAVARRO Departamento de Ingenieria ... Holt (Rinehart Winston), New York (1984). ...
This paper presents a novel Lyapunov-based control approach which utilizes a Lyapunov function of... more This paper presents a novel Lyapunov-based control approach which utilizes a Lyapunov function of the nominal plant for robust tracking control of general multi-input uncertain nonlinear systems. The difficulty of constructing a control Lyapunov function is alleviated by means of predefining an optimal sliding mode. The conventional schemes for constructing sliding modes of nonlinear systems stipulate that the system of interest is canonical-transformable or feedback-linearizable. An innovative approach that exploits a chaotic optimizing algorithm is developed thereby obtaining the optimal sliding manifold for the control purpose. Simulations on the uncertain chaotic ChenÕs system illustrate the effectiveness of the proposed approach.
This paper presents a current-mode adaptively hysteretic control (CMAHC) technique to achieve the... more This paper presents a current-mode adaptively hysteretic control (CMAHC) technique to achieve the fast transient response for DC-DC buck converters. A complementary full range current sensor comprising of chargingpath and discharging-path sensing transistors is proposed to track the inductor current seamlessly. With the proposed current-mode adaptively hysteretic topology, the inductor current is continuously monitored, and the adaptively hysteretic threshold is dynamically adjusted according to the feedback information comes from the output voltage level. Therefore, a fast load-transient response can be achieved. Besides, the output regulation performance is also improved by the proposed dynamic current-scaling circuitry (DCSC). Moreover, the proposed CMAHC topology can be used in a nearly zero RESR design configuration. The prototype fabricated using TSMC 0.25μm CMOS process occupies the area of 1.78mm2 including all bonding pads. Experimental results show that the output voltage ripple is smaller than 30mV over a wide loading current from 0 mA to 500 mA with maximum power conversion efficiency higher than 90%. The recovery time from light to heavy load (100 to 500 mA) is smaller than 5μs.
An optimal uniform-damping ratio controller is developed for the sequential design of a multivari... more An optimal uniform-damping ratio controller is developed for the sequential design of a multivariable control system so that the designed closed-loop poles of the respective multivariable system and reduced-order observer are exactly placed on the negative real axis and/or the boundaries of desired sectors with constant-damping ratios. The functions in the quadratic performance index to be minimized are chosen as a combination of the weighted outputs, reduced states and inputs. Also, the optimal uniform-damping ratio controller is a combination of optimal output-feedback and optimal reduced-order state-feedback controllers. A numerical example is given to demonstrate the design procedure.
The paper presents a methodology to make the load torque disturbance compensation based on the no... more The paper presents a methodology to make the load torque disturbance compensation based on the normal state observer. First, a state feedback controller is designed to achieve a satisfied speed command tracking performance. Then a multi-purpose state observer is constructed to observe the motor states (current and speed), as well as to provide the disturbance compensation. Since the variable of load torque is beyond the motor system state space model, some observation error will be inevitably existed in the observed states. Based on the demonstrated mathematics derivation, the state observation error feedback can be isolated from the exact state feedback. Such a state observation error feedback actually constructs some kind of feedforward compensation for the load disturbance. If the observer gain is picked up appropriately, then the effect of the load torque variation can be considerably compensated, such that the system performance deviation will be greatly attenuated. Both MATLAB/Simulink simulation and dSPACE DSP-based implementation have confirmed its effectiveness in the permanent magnetic synchronous motor (PMSM) drive system.
This paper presents an linear-quadratic-regulatorbased proportional-integral-differential equival... more This paper presents an linear-quadratic-regulatorbased proportional-integral-differential equivalent controller design method for a permanent-magnet synchronous motor. The disturbance rejection is achieved based on a multi-objective observer in which observation error is purposely retained and utilized in load disturbance compensation. This makes disturbance rejection tuning independent of the adjustment for speed command tracking; and the disturbance compensation is an integrated part of the controller output, which reduces the chance of input or state saturation. A robust stability analysis is also included for the modeling error. The proposed methodology is implemented through the dSPACE digital signal processor system, and the experimental result confirms its effectiveness.
This paper discusses the relationship among various recently developed constant state-feedback di... more This paper discusses the relationship among various recently developed constant state-feedback digital redesign methods. Then, for a unity-output feedback system with an analog plant in cascade with an analog controller, the best and simple Chebyshev quadrature digital redesign method is utilized to ®nd new pulse-amplitude-modulated (PAM) and pulse-width-modulated (PWM) digital controllers for eective digital control of the analog plant. The digital controllers are determined from existing or pre-designed analog controllers as in the case of PID controllers for industrial control processes and robotics, phase lead-lag compensators for servo-mechanisms and regulator systems and guidance-autopilots for aircraft and missiles etc. The proposed method provides an alternative methodology for indirect digital design of a continuous-time unity-output feedback system and enables us to accurately and eectively implement an existing or pre-designed cascaded analog controller via a digital controller.
In the models of piezoelectric actuator (PEA) systems, the hysteresis effects are often described... more In the models of piezoelectric actuator (PEA) systems, the hysteresis effects are often described by the concise Bouc–Wen models; however, these models are nonlinear and non-smooth because of the existence of terms which involve the absolute-value function. In particular, a challenging control problem is posed when, due to the properties of certain materials, such absolute-value terms are of high order. This control problem has been rarely studied. This article proposes the use of the approximated scalar sign function (ASSF), which is a numerically stable and differentiable nonlinear function, to represent the hysteresis function, with single-order or high-order absolute-value terms. This innovative step leads to a nonlinear but sufficiently smooth model. Then, a systematic digital design methodology is presented, which involves the following steps: (1) establish an optimal linear model based upon the resulting smooth model, (2) adopt a PI-based analogue controller and (3) apply the prediction-based digital redesign technique for digital implementation. A digital observer is also developed for state reconstruction, and to improve the input disturbance rejection. The positioning control of a PEA system with a high-order hysteretic Bouc–Wen model is implemented to demonstrate the effectiveness of the proposed ASSF based modelling and controller design approaches.
1850 Sheng-Guo Wang et al. and ß0 in (34), then the closed-loop system (7) is robust pole cluster... more 1850 Sheng-Guo Wang et al. and ß0 in (34), then the closed-loop system (7) is robust pole clustering within a vertical strip Cl in (8) for all admissible structured perturbations in (5). Moreover, the control ¡aw (14) is optimal for the matched uncertain linear system (I) with respect to the ...
IEEE TRANSACTIONS ON AUTOMATIC CONTROL^ VOL. AC-27. NO. I, FEBRUARY 1982 ... By using the specifi... more IEEE TRANSACTIONS ON AUTOMATIC CONTROL^ VOL. AC-27. NO. I, FEBRUARY 1982 ... By using the specifity of r and 6, a(A + TC + BF1r) can be rewritten as u(~tr~+~~a)=~(~~~+rc15 ) ... If we note that the observability of (C. A ) implies the one of (CIS, 51 A ! S ) it is clear ...
... pseudo-continuous-time quadratic regulators with pole placement in a specific region Prof. Le... more ... pseudo-continuous-time quadratic regulators with pole placement in a specific region Prof. LeangS. Shieh, PhD Hani M. Dib, MSc Sekar Ganesan, MSc Indexing terms: Computer-aided design, Optimal control, Control systems, Closed-loop systems, Matrix algebra ...
Based on the generalized continued-fraction method for finding the nth roots of real numbers, thi... more Based on the generalized continued-fraction method for finding the nth roots of real numbers, this paper presents a fast computation method for finding the principal nth roots of complex matrices. Computation algorithms with high convergence rates are developed, and their global convergence properties are investigated from the viewpoint of systems theory. *This work was supported in part by the U.S. Army Research Office, under contract DAAG 29-89Km37, and U.S. Army Missile Command, under contract DAAH 01.85C-Alll.
... MULTIVARIABLE CONTROL SYSTEMS TO BLOCK COMPANION FORMS LS SHIEH and S. GANESAN Department of ... more ... MULTIVARIABLE CONTROL SYSTEMS TO BLOCK COMPANION FORMS LS SHIEH and S. GANESAN Department of Electrical Engineering, University of Houston, Houston, TX 77004, USAJM NAVARRO Departamento de Ingenieria ... Holt (Rinehart Winston), New York (1984). ...
This paper presents a novel Lyapunov-based control approach which utilizes a Lyapunov function of... more This paper presents a novel Lyapunov-based control approach which utilizes a Lyapunov function of the nominal plant for robust tracking control of general multi-input uncertain nonlinear systems. The difficulty of constructing a control Lyapunov function is alleviated by means of predefining an optimal sliding mode. The conventional schemes for constructing sliding modes of nonlinear systems stipulate that the system of interest is canonical-transformable or feedback-linearizable. An innovative approach that exploits a chaotic optimizing algorithm is developed thereby obtaining the optimal sliding manifold for the control purpose. Simulations on the uncertain chaotic ChenÕs system illustrate the effectiveness of the proposed approach.
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