An Adaptive Variable-Frequency ZVS Control Strategy for Four-Switch Buck-Boost Converter in Low-Voltage and High-Current Applications

In this paper, a four switch Buck-Boost converter with soft-switching circuit is proposed (S-FSBB converter). The zero-current turn-on and zero-voltage turn-off at buck mode and boost mode are realized in the four-switch Buck-Boost (FSBB) converter by adding some additional passive components, which reduces switching losses. The circuit loss of S-FSBB converter and FSBB converter are calculated. Simulation and experiment result shows that, comparing with FSBB converter, S-FSBB converter can reduce switching noise and voltage stress, and achieve higher conversion efficiency.

This paper presents a dynamic modeling method for a 3-phase mutually coupled switched reluctance machine (MCSRM) considering spatial harmonics, and saturation. The conventional modeling methods of MCSRMs are based on 3D look-up tables (LUTs), where the phase flux linkages are considered as state variables. These 3D LUTs describe the phase currents with respect to phase flux linkages, and rotor position. The 3D LUTs represent two $dq$ quadrants, and are obtained from finite element analysis (FEA) by multi-phase excitation where the excitation currents cover two quadrants in the $dq$ synchronous reference frame. The LUTs used in the proposed method represent the phase current, and electro-magnetic torque as vectors. The magnitude, and the angle of these vectors are represented by the sine, and cosine Fourier coefficients. Hence, rotor position is not an input to the LUTs, and the proposed method uses 2D LUTs. Additionally, the flux linkages in the four $dq$ quadrants possess symmetry for MCSRMs. Therefore, LUTs corresponding to only one $dq$ quadrant are required. The single-quadrant based LUTs reduces the number of FEA steps, and the size of the LUTs by 50% compared to the two-quadrant LUT based models. Finally, the proposed method is validated using FEA, and experiments for a 12/8 MCSRM.

A constant frequency zero-voltage-switching (ZVS) control strategy with a minimum root mean square (rms) value of inductor current is proposed in this letter for the four-switch buck-boost (FSBB) dc-dc converter that is used as a 48 V intermediate bus pre-regulator in distributed power systems. The quadrilateral inductor current modulation is adopted to achieve ZVS operation. The four control time intervals are optimally selected such that the inductor current rms value is minimized, thus reducing the conduction loss. The proposed closed-loop ZVS control scheme can be implemented without sensing the load current, although the rms minimum current algorithm needs the input and output voltages and load current at given a steady-state condition. The control scheme is verified in a 300 W dc-dc prototype of the ZVS FSBB converter. The input voltage and load transition tests are provided to verify the closed-loop characteristics without sensing load current.

Full-bridge phase-shifting zero voltage switching (ZVS) pulse width modulation (PWM) circuit adopts phase control and by resonance, the circuit can realize zero voltage conduct of switch device, eliminate conduct loss. However, the lagging legs of full-bridge circuit is difficult to realize ZVS in a little current. The main circuit topological structure of full-bridge phase-shifting ZVS high frequency power supply based on adaptive delay control technology is applied in this paper. By adaptive delay control technology, it can detect voltage of power grid and bridge arm midpoint in real time, and expand the ZVS operating range by adjusting the triggered time of switch devices. The main transformer and resonance inductance parameters are designed in this paper. The experimental results proved that adaptive delay control technology can expand the ZVS operating range, and improve the efficiency of the power supply.

Four-switch buck-boost (FSBB) converter has the capability of bidirectional voltage step-down and step-up, which has attracted attentions in the fields of energy storage and solar energy. However, it faces the challenges in multimode operation and smooth mode transition, which rely on the complex mode detection scheme and cumbersome parameter tuning. In this article, the inherent limitation is analyzed through inconsistent frequency response and noncontinuous duty cycle operation region aspects. Then, a model predictive control (MPC) method characterized by tuning-free cost function is presented to achieve multimode control and smooth transition simultaneously. With the goal of ensuring the reference current tracking under inconsistent frequency response, a duty cycle and current ripples prediction are presented for all switching combinations. Then, a tuning-free cost function is utilized to overcome the gaps in noncontinuous duty cycle operation region and a smooth mode transition is achieved. Further, the robustness of the current tracking capability is analyzed mathematically considering the inductance variation and stray resistance variation. Finally, a comparative experiment proves the effectiveness. And it shows that the method can improve the efficiency by 0.4% compared with the traditional four-mode control.

DC-DC Dual Active Bridge (DAB) converters can potentially be used as an interface between DC micro-grids and battery packs of PHEVs/EVs. This paper focuses on presenting a new method to achieve Zero Voltage Switching (ZVS) for all the switches in DAB converters. This is done by initially extracting the ZVS criteria, which corresponds to different operating conditions (bus voltage and power level). Then, a Look-Up-Table (LUT) is created that is compliant with the derived ZVS region. The LUT can be used in the control system of DAB converters to achieve ZVS for a wide range of operating conditions. Simulation and Experimental results are provided to validate the effectiveness of the proposed method.

In this paper we focus on the adaptive control of structural acoustics using intelligent structures with embedded piezoelectric (PZT) patches and low cost digital signal processor systems. After a discussion on the adaptive feedforward control scheme, a hybrid adaptive control scheme is proposed, which takes advantage of both feedback control and adaptive feedforward control. The two schemes are realized on a low-cost, small volume, convenient and universal digital signal processing (DSP) board. A carbon fiber reinforced polymer plate with two embedded PZT patches is developed and used in two experiments. The first experiment is adaptive interior noise control using the intelligent plate, in which the adaptive feedforward control scheme is employed. Obvious noise reduction is obtained for constant frequency, swept frequency and varying amplitude harmonic disturbances. The second experiment is adaptive control of sound-induced vibration of the plate, where two embedded PZT patches are used as an actuator and a sensor, respectively, and the hybrid adaptive controller is applied. The full vibration reduction for various harmonic excitations is obtained, verifying the advantage of the hybrid adaptive control. It is demonstrated that active control of structural acoustics can be efficiently achieved by employing intelligent structures, advanced adaptive control schemes and the low-cost DSP board.

The four-switch buck-boost (FSBB) converter effectively reduces the average inductance current of FSBB when the input and output voltage is close to each other by using the four-mode operation, which alleviates the problem of limited duty cycle and low efficiency in the traditional control modes. However, the steady-state duty cycle mutation of FSBB with four-mode control will occur during mode switching, resulting in output voltage fluctuation. We analyzed the mechanism of duty cycle sudden change of four-mode control FSBB during mode switching, explored its influencing factors and governing laws, and proposed to use input voltage feedforward control to improve the smoothness of four-mode switching, so as to improve the response speed of output voltage when input voltage changes suddenly. The simulation results showed that after the input voltage feedforward control method was adopted, the four working modes can be switched smoothly in a wide input voltage range, the output voltage can be adjusted quickly, and the full load peak efficiency can reach 98%.

A control method to achieve the minimum freewheeling current of the four-switch buck-boost (FSBB) converter is presented in this paper. Compared with the conventional method, the proposed method can make the best use of the energy stored in the junction capacitance of the boost stage to realize ZVS of the buck stage. Therefore, the soft-switching can be realized under the condition of the minimum freewheeling current and the efficiency is further improved. Based on the ZVS analysis, the minimum freewheeling current and the dead-time under different input conditions are determined. Moreover, the sampling circuit and the control parameter of the proposed method are also illustrated in this paper. Finally, the proposed method is verified on a 1MHz FSBB prototype.

In this paper, we focus on the 2D LUT (2-dimension look-up table) techniques for the mitigation of HPAs' (high power amplifiers') memory effects when transmitting WCDMA wideband signal. On the basis of the previous method, an improved two-dimensional LUT indexing method for HPA predistortion with memory is proposed. Simulation and experimental results show that the proposed method has more effective predistortion capabilities compared with the previous method.

This paper proposes a new adaptive fuzzy nonlinear control strategy that allows designers to systematically construct fuzzy control. The control strategy proposes the use of fuzzy logic systems within a well understood control structure that is called nonlinear internal model control (NIMC) structure. The attractive feature of the NIMC structure is that the relations between some designed parameters and the performance of the control system can be found explicitly. Thus, this control structure allows designers to systematically construct fuzzy control. In addition to using fuzzy logic systems within a well understood control structure, an adaptive control strategy is also proposed in this paper. The control strategy is applied to control the inverted pendulum model. The results show that the proposed strategy can maintain the system stability and give a good control performance.

Researchers have applied 3D Lookup Tables (LUTs) in cameras, offering new possibilities for enhancing image quality and achieving various tonal effects. However, these approaches often overlook the non-uniformity of color distribution in the original images, which limits the performance of learnable LUTs. To address this issue, we introduce a lightweight end-to-end image enhancement method called Simulated Infrared Fusion Guided Image-adaptive 3D Lookup Tables (SIRLUT). SIRLUT enhances the adaptability of 3D LUTs by reorganizing the color distribution of images through the integration of simulated infrared imagery. Specifically, SIRLUT consists of an efficient Simulated Infrared Fusion (SIF) module and a Simulated Infrared Guided (SIG) refinement module. The SIF module leverages a cross-modal channel attention mechanism to perceive global information and generate dynamic 3D LUTs, while the SIG refinement module blends simulated infrared images to match image consistency features from both structural and color aspects, achieving local feature fusion. Experimental results demonstrate that SIRLUT outperforms state-of-the-art methods on different tasks by up to 0.88 ~ 2.25dB while reducing the number of parameters. Code is available at https://github.com/riversky2025/SIRLUT.git .

Nonlinear Adaptive Control for Turning Processes

Recently, transformable Unmanned Aerial Vehicles (UAVs) have become a subject of great interest in the field of flying systems, due to their maneuverability, agility and morphological capacities. They can be used for specific missions and in more congested spaces. Moreover, this novel class of UAVs is considered as a viable solution for providing flying robots with specific and versatile functionalities. In this paper, we propose (i) a new design of a transformable quadrotor with (ii) generic modeling and (iii) adaptive control strategy. The proposed UAV is able to change its flight configuration by rotating its four arms independently around a central body, thanks to its adaptive geometry. To simplify and lighten the prototype, a simple mechanism with a light mechanical structure is proposed. Since the Center of Gravity (CoG) of the UAV moves according to the desired morphology of the system, a variation of the inertia and the allocation matrix occurs instantly. These dynamics parameters play an important role in the system control and its stability, representing a key difference compared with the classic quadrotor. Thus, a new generic model is developed, taking into account all these variations together with aerodynamic effects. To validate this model and ensure the stability of the designed UAV, an adaptive backstepping control strategy based on the change in the flight configuration is applied. MATLAB simulations are provided to evaluate and illustrate the performance and efficiency of the proposed controller. Finally, some experimental tests are presented.

A modified extended-phase-shift (EPS) control is proposed to decrease the control complexity and achieve full load range zero-voltage-switching (ZVS) for dual-active-bridge dc-dc converters. In the proposed solution, a fixed duty cycle is added, and the magnetizing current is utilized to achieve full load range ZVS. In addition, two control variables are decoupled, because the control of duty cycle is only determined by the voltage conversion ratio, which is not affected by the phase shift angle. The ZVS models considering junction capacitors and magnetizing inductance, ZVS regions under full load range, and derivation of control law are analyzed in detail. Finally, the effectiveness of the proposed solution is verified by experimental results from a 500W, 250kHz GaN-Based prototype.