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In this article, a shielding scheme based on ferrite magnetic antennas (SS-FMA) is proposed. The scheme can effectively provide a path for the magnetic field lines of three-dimensional couplers to be concentrated and conducted. The SS-FMA is considered to be applied for long range inductive power transfer (IPT) systems of post insulators to powering smart grid sensors and improve the efficiency under the influence of metal components. The negative influence of the aluminum flanges on the magnetic field distribution is analyzed. The suppression effects of the shielding scheme on the abovementioned influence have been analyzed. Parameters of the SS-FMA are optimized. The equivalent circuit model is established, and the abovementioned process is explained from the perspective of the circuit model. A prototype of a post insulator that includes IPT system and SS-FMA has been built. When the coils of the IPT system are attached to the flanges, the efficiency can still reach 47.8% under the influence of SS-FMA, which is an increase of 13.7% compared with no shielding scheme. When the coils are slightly away from the flanges, efficiency of the system including SS-FMA can be quickly improved to 54.3%. [ABSTRACT FROM AUTHOR]

Based on the unipolar-duty-cycle (UDC) modulation technique, this article presents a hybrid control strategy for a series–series compensated inductive power transfer (IPT) system. By adjusting the duty cycle and the operating frequency, zero-voltage switching (ZVS) and constant-current output (CCO) can be achieved with varying coupling coefficients and load. Furthermore, as the proposed strategy enables the IPT system to lower the frequency of operation, it provides higher efficiency in the overall output power range than the conventional variable-frequency control methods. The basic principle of the UDC control strategy and its characteristics are introduced, and the system performance under UDC is analyzed and compared with the performance achieved by conventional control methods. Based on this, the UDC closed-loop control scheme, which combines PI control and hysteresis control, is proposed for the dynamic tracking of the ZVS and the CCO under a wide range of coupling coefficients and load. To validate the practicability of the proposed control strategy, a 500-W experimental prototype is configured. The simulation and experimental results indicate that the proposed scheme can stably and accurately track the ZVS and the CCO under varying parameter conditions, and it significantly improves the system efficiency. Especially, the system efficiency is improved by approximately 1.75% under light-load conditions as compared with that of the conventional control method. In addition, since the proposed method employs only one control loop, the cost and complexity of the IPT system are reduced. [ABSTRACT FROM AUTHOR]

In this article, an efficiency-oriented control strategy is proposed for LCC–LCC-compensated wireless power transfer (WPT) system to achieve zero-voltage-switching (ZVS) operation over a wide current regulation range, in which full-bridge (FB) and half-bridge (HB) modes are combined and switchable based on requirements from load. The harmonic-considered time-domain models for FB and HB modes are first built to calculate current through the switches at the turn-off moment accurately. Then, focused on the constant voltage charge stage with variable output current, the ZVS boundaries are identified in HB and FB modes as the preferable control trajectories, which determines the desired current output with joint considerations of frequency, phase-shift angle, and duty ratio. Next, a least squares optimization method is introduced to fit the theoretical control trajectories into a smooth curve that is practical for implementation on microcontrollers. Finally, a 4.4-kW WPT prototype is built to verify the feasibility and validity of the proposed control strategy. Results show that a high system efficiency can be achieved over a wide output current range, with an efficiency of 94.68% even at 20% rated power. [ABSTRACT FROM AUTHOR]

Adaptive synchronous rectification (SR) is a good solution to solve duty cycle loss for LLC resonant converter. Usually, whether the synchronous rectifier is turned off prematurely or late can be detected by whether the body diode is conducted on or not. However, when the switching frequency is below the resonant frequency, both SR turning-off prematurely and late may generate body diode conduction (BDC), which will cause logic errors in the conventional adaptive SR strategy. Then, a large reverse current from load to source will occur, which damages the efficiency. To solve the problem, the time-domain modeling of the SR drain-to-source voltage is established to analyze the mechanism of BDC caused by SR turning-off late. Moreover, an improved adaptive SR driving scheme is proposed, which can identify the two different types of BDC and tune SR to be turned off exactly. Finally, a 280 W LLC prototype is built to verify the established model and the proposed SR method. The prototype proves that both the duty cycle loss and the reverse current are eliminated and efficiency improvement of 0.54% is achieved. [ABSTRACT FROM AUTHOR]

This article presents a two-stage automotive LED driver architecture delivering independently regulated output currents to multiple LED strings. The system consists of a multiphase noninverting buck–boost front-end stage, which allows for a wide battery voltage range, followed by high-frequency immittance-network-based LCL-T resonant converters, which operate as current sources over wide output voltage ranges. The two-stage buck–boost + resonant (BB+resonant) architecture takes advantage of the buck and boost capability of both stages, and the flexibility in setting the intermediate bus voltage to minimize losses. Advantages of the BB+resonant architecture include the use of lower voltage rated devices and soft switching in the resonant stage, leading to reduced losses and size. Experimental results are provided for a prototype consisting of a 250-kHz two-phase front-end stage and 2-MHz LCL-T resonant stages delivering independently regulated 1 A currents to four LED strings with $N = 1$ $-$ 18 LEDs. The measured system efficiency is greater than 88% over wide input (8 $-$ 18 V) and output (3–50 V) voltage ranges, with a peak efficiency of 93%. [ABSTRACT FROM AUTHOR]

In this article, a parameter design method is proposed to improve the dc–dc efficiency of the capacitive power transfer (CPT) system. Similar to the inductive power transfer (IPT) system, the capacitive coupler is analyzed by using a T-type model, giving direct insight into the impedance refracted from the secondary side. Compared to the IPT system, the external capacitor of the capacitive coupler introduces extra design freedom, making it easy to realize the optimal load condition by adjusting the external capacitance. To quantify the relationship between the optimal load and the external capacitance, the impedance characteristic of the rectifier is discussed. Then, the efficiency analysis is conducted in detail. Considering the impact of the resonant frequency, and the external capacitance that determines the coupling coefficient, a parameter design method is proposed to improve the dc–dc efficiency. Although the design example is conducted with the double-sided LC compensated CPT system, the analysis and design process can be extended to other compensation networks easily. The effectiveness of the proposed design method is verified with a 100-W output CPT system. The experimental results show that the dc–dc efficiency can reach 89.39% with 10-W output, and reach 93.02% with 100-W output. [ABSTRACT FROM AUTHOR]

The use of wireless power transfer technology in unmanned aerial vehicle (UAV) systems is rapidly improving in different application areas. The main limitations of electric-powered UAVs are their charging range and stability in dynamic conditions. To solve these, this article proposes a hybrid control method based on dc-link and switched capacitor control with a fixed operating frequency. The dc-link voltage is regulated by the boost power factor correction converter to smoothen the output voltage, and the switched capacitor is used to dynamically compensate for self-inductance variations under dynamic coupling conditions. The output voltage stabilization and near-unity power factor of the input impedance can be achieved by applying the hybrid control method. Therefore, efficiency improvement can be achieved. Furthermore, the proposed control method can also be applied to systems with large coupling variations. To verify the proposed control method, a 500-W prototype was set up in the laboratory, and the experimental results proved that the control method could ensure a stable output voltage with horizontal and vertical offsets of 200 and 62 mm. respectively. Additionally, the results show that the maximum efficiency of the proposed control method is 91.9%, demonstrating that the proposed method effectively improves the efficiency. [ABSTRACT FROM AUTHOR]

In order to get rid of plug-in/out actions for container terminals and to save space, a power-relay inductive power transfer system is employed for reefer container wireless charging. Besides, a load-power-based efficiency model is proposed to analyze system efficiency. The function of efficiency against the input voltage and the load power distributions of the system is analyzed in detail. Then, system efficiency can be improved by regulating the input voltage according to the input-voltage-lookup table, which is generated as per various power distributions of loads. Finally, a prototype with three loads is built to validate the performance of the proposed approach. The experimental results show that the efficiency is greater than 94.29% with an improvement by 7.6%, 7.2%, and 6.0%, compared with those without optimization (fixed input voltage 213 V) at one load (@80 W), two loads (@80 and 80 W), and three loads (@80, 80, and 80 W), respectively. [ABSTRACT FROM AUTHOR]

To get rid of plug-in/out actions for automatic wharves, a switchable-LCL-circuit (SLC) based inductive power transfer system is proposed to improve efficiency for reefer container wireless charging. As we knew, the power requirement of a reefer container only hits a few operation points, and each operation point is in corresponding to an individual resistance point (IRP). Therefore, the system efficiency can be improved by altering the IRPs into the optimal load resistance (OLR). The idea of this letter is to use the SLC to create multiple efficiency-load curves, then to regulate the peak points of the curves approaching the IRPs by reconfiguring the compensation parameters. Finally, a prototype was built to validate the performance of the proposed approach. The experimental results show that with the SLC, both the IRPs 20 and 160 Ω can be transformed into the OLR 55 Ω; the proposed system can gain the system efficiency >92.4% at the IRPs (20 Ω, 259.2 W) and (160 Ω, 32.4 W). [ABSTRACT FROM AUTHOR]

Compensation topologies play an essential role in wireless power transfer systems for electric vehicles. Specifically, the double-sided LCC compensated (DS-LCC) topology has been widely adopted, owing to its inherent advantages, such as load-independent constant current (CC) output, low sensitivity to load variation, and high freedom in parameter design. However, large resonant devices in the DS-LCC topology lower the system efficiency and increase the complexity of optimal parameter tuning. Therefore, in this article, the parameters of the DS-LCC compensation topology are reconfigured by adjusting the ratios of its two compensation inductances without changing the specified system-level parameters, such as the loosely coupled transformer, operating frequency, and specified CC outputs. The system performance under each case is analyzed and compared in detail, based on which, an asymmetric parameter-design method is proposed to optimize the system efficiency. To verify the reasonability of the proposed tuning method, a 6.6-kW experimental prototype is configured, and comparative experiments are conducted. The experimental results indicate that, compared with the conventional method, the proposed parameter-tuning method improves the system efficiency under overall load conditions, especially under light loads. [ABSTRACT FROM AUTHOR]

In inductive power transfer systems, impedance matching is critical in obtaining high efficiency. However, since the load impedance is subject to variations in most applications, especially wireless charging, maintaining impedance matching is a challenge. One valid solution is to maintain the equivalent load impedance at the optimal value against load variations by controlling a load-side power converter. Nonetheless, the system overall cost, size, and complexity can be increased. In this article, based on a proper selection between full-bridge and half-bridge modes of the inverter and rectifier, an operation mode selection method is proposed that can achieve semi-impedance-matching with large load variations. In general, with the proposed method, high overall efficiency can be obtained while neither additional power converters nor complicated control is required. A 1-kW prototype has been developed and the experimental results have verified the proposed method. [ABSTRACT FROM AUTHOR]

This article proposes a novel wireless power transfer (WPT) system with switch-controlled capacitor (SCC) where variable capacitance and efficiency optimization are realized. The optimum asymmetrical voltage cancellation (OAVC) control is applied to realize wide-ranging soft-switching operation for the active bridge converters. The pulsewidth of the active bridge inverter regulates the output voltage, and the pulsewidth of the active bridge rectifier optimizes power delivery efficiency. The SCCs in the transmitter and the receiver sides are regulated for the zero-voltage switching operation and the resonant condition, respectively. The online estimation of mutual inductance is carried out to adapt the coupling deviations of the WPT system in real time. A 650-W prototype is built to verify the feasibility of the proposed WPT system and the effectiveness of the OAVC control. The experimental results show quite good performance and efficiency improvement for the WPT system at various loads. [ABSTRACT FROM AUTHOR]

The loss model of an induction motor based on the electric circuit is known as the more comfortable model to be identified compared to the magnetic model. This model is commonly used for field-oriented control rather than direct torque control (DTC). In the recent research for applying the electric loss model for flux optimization, the core loss resistance current is ignored, since it will reduce the robustness and accuracy of the model. In this article, it is analytically proved that considering that current will reduce the sensitivity significantly. Thus, a robust loss model based on a complete electric circuit is proposed for flux optimization in predictive torque and flux control. The predictive method had been chosen because of the fast dynamic response. In order to avoid computation increase, the predictive direct voltage control is used. The validity of the proposed method is studied via experimental results. [ABSTRACT FROM AUTHOR]

An inductive power transfer (IPT) converter usually has an optimum efficiency only at a matched load. Because of wide load range variation during battery charging, it is challenging for an IPT converter to achieve the required output and maintain high efficiency throughout the charging process. In this paper, a series–series compensated IPT converter with an active rectifier is analyzed and implemented for battery charging. Appropriate operations are employed for constant-current charging and constant-voltage (CV) charging. A novel operation approach is proposed to achieve constant output voltage and to ensure load impedance matching during CV charging without the help of an extra dc–dc converter, which incurs loss. Both a frequency modulated primary inverter and a phase-angle modulated secondary active rectifier can achieve soft switching. High efficiency can be maintained during the whole battery-charging profile. [ABSTRACT FROM AUTHOR]

This paper develops a 6.78 MHz multiple-receiver wireless power transfer system driven by a Class E power amplifier. Constant output voltage is achieved for each receiver with optimized overall efficiency. A novel one-receiver model is built to analyze the overall power-efficiency characteristics. The loads and input voltage are then designed as two control variables. Through tuning the loads, constant output voltage is achieved by independent controllers at the receiver side. Then, the efficiency is optimized by tuning the input voltage at the transmitter side. Finally, the theoretical analysis and control scheme are validated using a three-receiver system. It shows that different constant output voltages, 5, 9, and 12 V can be achieved independently for different receivers. When the load resistance, real coupling, and number of receivers change, the voltage can be quickly regulated, and the overall optimum system efficiency is 66.6%. [ABSTRACT FROM AUTHOR]

This paper presents the framework for the applications of double-source wireless systems in charging for movable electronic devices. To acquire the real-time mutual inductances between the receiving coil and the transmitting coils, a detection strategy on the basis of primary parameters (currents and voltages) is introduced, which can replace the wireless communications between the receiving side and the transmitting side. Coordinated control of two source voltages is employed to deal with the power fluctuation of load, which is caused by load position variations. In specific, the constraint of two source voltages, which can maintain the output power stable, is derived. Based on these feasible combinations of source voltages, numerical calculations are further carried out to identify the optimized voltage combination, which can achieve high power transfer efficiency. Finally, an experimental prototype is built up and the results show that the proposed coordinated control strategy can minimize power fluctuation and maintain relative high efficiency at the same time. [ABSTRACT FROM PUBLISHER]

Wireless dynamic charging is one of the most promising power supply methods for electric vehicles (EVs), which can reduce battery volume and extend EVs’ range. Stable output power and high system efficiency are two of the most important features for practical applications of wireless dynamic charging. For the low-speed application scenarios of dynamic charging, an efficiency optimization method is proposed to improve the system efficiency while regulating the output voltage. Two overlapped DD coils are employed to generate an enhanced magnetic field without dead points. An optimized current control method is proposed to adjust the direction and the ratio of the two transmitter currents as the receiver moves along the track, dynamically. By applying this method, the efficiency of dynamic charging system can be optimized while the output power can be regulated to the desired value at the same time. A 600 W prototype is established to validate the performance of the proposed method. The experimental results show that the system efficiency for dynamic charging reaches 88.3%–90.4% with the proposed method. The maximum efficiency improvement of proposed algorithm is 2.3% compared to that with the same energized currents for both DD coils. [ABSTRACT FROM PUBLISHER]

The operation of wireless power transfer systems (WPT) with a single relay, which could charge one or multiple receivers simultaneously, is investigated. Besides, a new method for ensuring the optimized transfer efficiency and the output power by configuring the operating frequency is presented, even when the coupling coefficients between all the coils are very small. An issue of concern is that the couplings between receivers cannot be ignored due to limited operating space, which adds to the complexity of both the system design and the control method. The contribution of the research presented here is to propose an optimized strategy which can charge each receiver with identical power and simplify the coupling complexity thereof. Specifically, the efficiencies and outputs of the introduced WPT systems are discussed. In addition, the distribution design according to different numbers of receivers is proposed to guarantee that both the system operating frequency and the output power remain stable. The theoretical analysis is confirmed by both simulation and experimental results. [ABSTRACT FROM PUBLISHER]

This paper presents a control method for efficiency improvement of the LLC resonant converter operating with a wide input-voltage and/or output-voltage range by means of topology morphing, i.e., changing of power converter's topology to that which is the most optimal for given input-voltage and/or output-voltage conditions. The proposed on-the-fly topology-morphing control maintains a tight regulation of the output during the topology transitions so that topology transitions are made without noticeable output-voltage transients. The performance of the proposed topology morphing method is verified experimentally on an 800-W LLC dc/dc converter prototype designed for a 100-V to 400-V input-voltage range. [ABSTRACT FROM PUBLISHER]

Self-powered wireless sensors require power delivery systems capable of harvesting from very low input voltage while consuming minimal bias current. This paper presents a multistage boost regulator capable of generating 3 V to supply RF blocks in self-powered wireless sensors from 10 mV input voltage. The bias power consumption is minimized using automated bias gating. The efficiency of the multistage conversion at a high conversion ratio is enhanced through the regulation and control of the intermediate-node voltage. A test chip, fabricated in 130 nm CMOS, demonstrates functional operation from as low as 10 mV input and consumes 190 nA bias current. Single-stage boost regulator demonstrates Peak efficiency of 89%, while the cascaded two stage peaks at 72%. In the cascaded system, the variable intermediate-node voltage operation shows up to 9% efficiency improvement over fixed intermediate-node voltage when operating at high conversion ratio. [ABSTRACT FROM PUBLISHER]

Intermediate couplers have been shown to increase the coupling from primary to secondary pads in inductive power transfer (IPT) systems. This paper investigates embedding a coplanar intermediate coupler coil with the primary coil inside the primary pad to boost the coupling to the secondary pad and improve the efficiency of the system. Several coil designs are simulated and a mathematical model is developed to evaluate the efficiency of parallel–parallel and series–series tuned systems. As shown a coplanar, independently tuned intermediate coupler coil improves the efficiency of a series–series-tuned system since it reduces source losses. However, there appears to be no benefit to having an intermediate coupler with a parallel–parallel-tuned system. Furthermore, boosts in coupling are a result of adding extra current carrying windings to the primary pad and simulations show that operating the system as a traditional two coil IPT system may be simpler and more effective based on tuning topology. An experimental system was constructed to validate the simulations. [ABSTRACT FROM AUTHOR]

This paper presents a wide-speed-range-operation dual stator-winding induction generator (DWIG) dc generating system for wind power applications. In this system, the dc bus on the control-winding side and the dc bus on the power-winding side are connected in parallel to further widen the speed range of the constant dc voltage output, especially at low speeds. Based on the control mechanism of the DWIG and the instantaneous power theory, a control-winding-flux-orientation control strategy is employed. In order to improve the wind energy conversion efficiency at low wind speeds, the generator efficiency optimization method is investigated. The experimental results from a 20 kW/600 V prototype show that the proposed generating system can output the constant dc voltage in a speed range of 1:4, and the generator efficiency in the low speed range is improved, which both bring the advantages for wind power applications, such as expanding the scope of the wind energy utilization and capturing much more wind energy. [ABSTRACT FROM AUTHOR]

This paper presents a unified control method for the combined permanent magnet generator (PMG) and active rectifier that can be used in autonomous power systems such as more-electric aircraft requiring high power density and efficiency. With the proposed control, the system can function well without additional boost inductors and rotor position sensors. The design procedure for the control is presented, including current loops, a voltage loop, and a rotor position estimator loop. Simulation and experimental results show that both the dc-link voltage and the reactive power could be controlled effectively. A system efficiency optimization technique is proposed by selecting the permanent magnet flux linkage and determining the operating points at various load and speed conditions. The power density and efficiency of the PMG and active rectifier system are improved with the unified control. [ABSTRACT FROM AUTHOR]

This paper proposes a flux control strategy for a consequent-pole permanent-magnet (CPPM) machine that increases torque capability over a wide speed range and enhances efficiency with a fast convergence. After a brief analysis of the parameters of the CPPM machine, a new flux-weakening algorithm is proposed to achieve maximum torque output over the entire speed range. The optimal flux reference is determined by the preset output flux generated by the 1/ω method and compensated by the voltage closed-loop controller to improve dynamics response. A variable structure voltage controller incorporated with a limiter is designed to generate the antiwindup control. Furthermore, the loss model of the CPPM machine is derived to demonstrate that a 1-D search is suitable for optimizing the machine's efficiency. Then, an adaptive flux step search algorithm, which calculates the flux step proportional to the derivative of the input power with respect to the q-axis voltage, is proposed to minimize the power losses online. The experimental results are compared with the traditional flux control strategy on a CPPM prototype machine, which confirmed the robustness of the presented flux control strategy to obtain the maximum torque output over the entire flux-weakening speed range. The convergence speed is also increased in the efficiency optimization process. [ABSTRACT FROM AUTHOR]

In this paper, the concept of the adaptive current source drivers (CSDs) is proposed for the high-frequency synchronous buck converters. Compared to the previous CSD circuits, the adaptive CSD can achieve adjustable drive current and drive voltage according to different load condition. The benefit is that higher drive current and voltage lead to lower switching loss and conduction loss when the load current increases. Therefore, the adaptive CSD is able to realize optimal design to reduce the switching loss, the gate drive loss, and the conduction loss in a wide load range. It should be noted that the adaptive concept is suitable for both the continuous and discontinuous CSDs regardless the drive circuit topologies. Through investigating the CSD circuits, one simple method to achieve the adaptive drive current based on the adaptive voltage is proposed. A 12 V input, 1.3 V output, and 1-MHz synchronous buck converter with the continuous and discontinuous CSDs was built, respectively, to verify the advantages of the proposed adaptive concept and efficiency improvement. [ABSTRACT FROM AUTHOR]

In this paper, a flux search controller is proposed to improve the efficiency of direct torque control of a six-phase induction machine. The proposed flux search controller is based on adaptive gradient descent of motor flux value with fast response and easy implementation. A proper loss model of six-phase induction motor in conjunction with the proposed method has been presented. Stator frequency variation with respect to flux reduction is considered as a new aspect of fast flux search control. Reduction of the flux in the search control technique leads to an increase in stator frequency, and an error in core loss calculation occurs if the frequency variation is ignored. The proposed search controller greatly improves efficiency by reducing core loss as well as harmonics loss. The approach not only is easy to implement and adaptive with regard to parameter variations but also requires no additional hardware for practical implementation. The simulation and experimental results presented in this paper verify the effectiveness of the proposed method in improving efficiency of direct torque control of six-phase induction motor drive. [ABSTRACT FROM AUTHOR]

A key feature of microgrid concept is the ability to operate in islanding mode. Under such operating scenario, the distributed generators within microgrid should form a high-quality voltage supply for the load to sustain its normal operation. Power converters, the interface of renewable sources and energy storage systems, are important components of microgrids. The size and the number of the power converters required will depend on the fluctuating power flow within the microgrid. In this paper, we propose a hybrid control architecture to balance the power shared among the multiple interfacing inverters and optimize the system-operating efficiency. Simulation and real-time test results are provided to validate the proposed hybrid control scheme. [ABSTRACT FROM PUBLISHER]

In this paper, a method of maintaining high powerconversion efficiency across the entire load range and its circuit implementations are described. The proposed method substantially increases the conversion efficiency at light loads by minimizing switching and driving losses of semiconductor switches, as well as core losses of magnetic components. These losses are minimized by periodically turning off and on the power converter, and by controlling the converter so that when the converter is ON, it operates at the power level that exhibits the maximum efficiency. The performance of the proposed method was evaluated on a 500-W, 400-V/12-V dc-dc converter and a 1-kW ac-dc boost power-factorcorrection front-end. [ABSTRACT FROM AUTHOR]

The recent rising of oil prices and global warming crises increasingly support the ongoing practice of loss minimization control of electric motors including single-phase induction ones as the most used motors. Therefore, the tendency toward using variable-speed drives (VSDs) to save energy by adjusting motor speed is seen, but on account of increasing motor loss in nonrated conditions, an efficiency control system can improve energy saving even more. In this paper, after carrying out a detailed motor efficiency analysis, an appropriate method for motor efficiency maximization control, combined with a VSD, is presented and implemented. Experimental results of the implemented system validate the proposed method. [ABSTRACT FROM AUTHOR]

This paper presents a novel technique and system for increasing the efficiency of dc-dc converters that supply dynamic electronic loads, such as modern audio and video equipment and other devices whose power consumption largely depends on the digital data they process. The optimization does not require a current-measurement circuit and is well-suited to portable applications. It is based on a real-time prediction of the dc-dc converter output current from easily accessible digital data streams present in the targeted loads. The result of the prediction is used for dynamic adjustment of the power-stage transistor size and/or for switching into pulse-frequency-mode of output voltage regulation, in order to maximize the instantaneous converter efficiency on-the-fly. The use of a segmented power-stage allows the effective power-transistor size to be changed on-the-fly, and the tradeoff between the gate-drive and rms conduction losses is continuously optimized over the full range of operation. The effectiveness of the optimization is demonstrated on an experimental system, including a 1-W digitally controlled 4-MHz, 3.6 V-1.8 V buck converter with an integrated segmented power-stage and a digital high-fidelity class-D audio amplifier acting as the digital load. The results show a good agreement between the digitally predicted and actual dc-dc converter load current, as well as a reduction in total energy consumption of up to 38%. [ABSTRACT FROM AUTHOR]

This paper presents a new loss-model-based controller for an induction motor drive. Among the many loss minimization algorithms (LMA) for an induction motor, a loss-model- based approach has the advantages of fast response and high accuracy. However, the performance of the loss-model controller (LMC) depends on the accuracy of the modeling of the motor drive and losses. In the development of the loss model, there is always a tradeoff between accuracy and complexity. This paper presents a new LMC to determine an optimum flux level for the efficiency optimization of the vector-controlled induction motor drive. An induction motor (IM) model in d-q coordinates is referenced to the rotor magnetizing current. This transformation results in no leakage inductance on the rotor side, thus the decomposition into d-q components in the steady-state motor model can be utilized in deriving the motor loss model. The suggested LMC is simple, but leakage inductances are not omitted. The complete closed loop vector control of the proposed LMC-based IM drive is successfully implemented in real-time using digital signal processor board DS 1104 for a laboratory 1/3 hp motor. The effectiveness of the proposed scheme is demonstrated through simulation and experimental results. [ABSTRACT FROM AUTHOR]