International Journal of Circuit Theory and Applications最新文献

Magnetic core structure plays an important role in improving the efficiency of wireless power transfer (WPT) systems for unmanned aerial vehicles (UAVs). However, there are still few systematic studies on the effects of ferrite core structural parameters on coil performance. This paper systematically studies the influence mechanism of structural parameters such as ferrite area ratio, thickness, and spacing on coil performance. A prediction model between ferrite size parameters and coupler performance was established using a multilayer perceptron (MLP) neural network algorithm. The determination coefficient R² of the established model was as high as 0.98. The experimental results show that the prediction results of the established model are within 10% of the actual test results, underscoring its high accuracy and superior predictive capabilities. This paper provides valuable insights into the design, evaluation, and optimization of magnetic core structures, which is expected to improve UAV-WPT systems' efficiency.

This paper proposes an innovative design approach for multi-octave ultra-wideband (UWB) power amplifiers (PAs). The approach combines extended continuous-mode class-GF and GF⁻¹ modes to simplify the PA structure while achieving multi-octave bandwidth. This approach can simplify the design of power amplifiers while simultaneously achieving multi-octave capabilities. To validate the feasibility of this concept, the paper utilizes the traditional low-pass network to control the second and third harmonics of the two modes, finalizing the design of the PA's output network. The test results show that, within the frequency band of 0.4–3.2 GHz, with a bandwidth of 156%, the UWB PA achieves seamless conversion between extended continuous class-GF mode and extended continuous inverse class-GF mode. The PA has demonstrated remarkable performance metrics, including an efficiency exceeding 58.8%, a gain surpassing 9.2 dB, and an output power exceeding 39.2 dBm. Moreover, the size of the circuit is 66 mm × 30 mm.

This paper proposes a novel model predictive control (MPC) for five-phase fault-tolerant permanent magnet motor (FTPMM) using an improved vector selection. Unlike conventional MPC approaches, this method does not rely on the deadbeat control principle. It effectively reduces the computational burden of the algorithm while enhancing the motor drive performance. The scheme determines the optimal output vector and calculates the corresponding action times based on the concept of synthesizing two adjacent virtual vectors (VVs). Firstly, a VVs control set is adopted to improve the current control accuracy. Then, an improved vector selection method is introduced to obtain the reference vector directly by table lookup method without computational derivation. This eliminates the dependence on the deadbeat control principle found in traditional methods. Then, a two-step optimization method is used to obtain the optimal vector combination and to calculate the duty cycle. In the two-step optimization process, constraints are introduced to avoid duty cycle overflow. This optimization process is also independent of the deadbeat control principle. The feasibility and superiority of the proposed MPC method are demonstrated through theoretical analysis and experimental validation.

In view of the fact that the conventional proportional-resonant (PR) controller employed in the asymmetric-LCL (A-LCL) filter-based grid-connected inverter (GCI) faces some challenges in practice, such as complex state space equations, slow dynamic response, and poor robustness, this paper proposes a pulse width modulation (PWM) based improved sliding mode controller (SMC) control method using the Kalman filter estimation for three-phase GCI with A-LCL filter. First, a simplified model based on the A-LCL filter (called the S-A-LCL filter model) is proposed, which reduces the system order. Second, the SMC controller is designed based on the S-A-LCL model in the control system. Besides, this paper improves the conventional SMC controller on the basis of its design, which has a simple design of its sliding mode surface and a small amount of computation. This proposed SMC controller is called the P_SMC controller. Then, for the P_SMC controller that ought to acquire system state variable information, the Kalman filter estimator is employed to estimate them, reduce the sensor count, save costs, and improve the system's resistance to hardware failures. Finally, a three-phase/6 kW/380 V/50 Hz A-LCL filtered GCI with a step-up transformer experimental setup has been established. It is demonstrated that the control performance of the GCI system with the proposed control method is improved compared to the conventional PR controller employed in an A-LCL-based GCI system, and the practicability and excellence of the proposed control method in terms of robust performance, dynamic performance, and disturbance immunity are verified.

The use of coupled inductor (CI)-based high step-up gain topologies is increasing to handle a vast range load/input voltage disturbance. In CCM operation, the presence of right half plane (RHP) zero in control-to-output voltage transfer function is a major issue. This paper introduces a new two-phase interleaved tri-state CI-based high step-up gain converter that eliminates RHP zero. To achieve this, tri-state configuration in the proposed topology is implemented, enabling wide bandwidth and stable operation. The interleaved structure on input side reduces input current ripple and increases bandwidth. This helps to increase power density and improves the dynamic response of converter. The interleaved operation also reduces current stress on devices, minimizes core size and reduces losses, and improves efficiency. The claim of RHP zero free operation of the proposed converter is verified by deriving the small signal model. Simulation and experimental studies are presented to validate the theoretical findings. Experimental verification is conducted using a 200-W laboratory prototype of the converter, designed to boost a 24-V input to a 100-V output.

Various resonant gate driver circuits aim to recover gate drive losses and reduce switching losses, particularly in high-frequency applications, enhancing overall system efficiency. The LLC resonant converter is favored in high-frequency, high-power-density settings due to its soft-switching capabilities. However, existing gate driver circuits for LLC converters usually operate at fixed frequencies and duty cycles, failing to address the variable requirements of LLC voltage regulation. Most current variable frequency and duty cycle drivers focus on buck converters, targeting large current handling without optimization for LLC circuits. A dual-channel current-source gate driver for secondary-side MOSFETs in LLC-DCX is proposed in this paper. This circuit enables variable-frequency and duty-cycle control. Specifically for LLC-DCX applications, an optimized design utilizing current-source gate drivers to control the LLC secondary rectifier is presented. The loss mechanisms in current-source drive circuits are analyzed, and a comprehensive loss model for the LLC circuit is established. Key resonant parameters of the driver are optimized along with the dead-time adjustment of the LLC converter. A prototype LLC converter was developed, operating at a resonant frequency of 1.3 MHz. Testing results show that the LLC prototype driven by the current-source gate driver achieves a peak efficiency improvement of 0.67% compared with traditional drivers and recovers 82% of gate drive energy.

This paper introduces a non-isolated high step-up DC–DC converter with reduced voltage stress on semiconductors. The proposed structure is based on two boosting techniques: a switched capacitor (SC) cell and a quadratic cell (QC). The proposed converter uses the advantages of SC and QC simultaneously to increase the voltage gain. Consequently, the converter has a much higher voltage gain compared to similar structures. High voltage gain, low voltage stress across semiconductors, no limitation of duty cycle, continuity of its input current, and the existence of a common ground between input and output ports are the most substantial features of the proposed converter and make it suitable for renewable energy applications. Among the compared high-step-up DC–DC converters, the suggested topology provides higher voltage gains at lower duty cycles. The power density of the proposed converter is improved. So, the volume of the suggested converter is reduced. Moreover, to prove the superiority of the proposed converter, the operation principles, steady-state analysis, and comparison with other similar high step-up DC–DC converters are presented. Voltage gain and voltage stress across semiconductors are compared and analyzed. Finally, the experimental results are displayed to prove the effectiveness of the proposed converter.

To enhance misalignment tolerance and reduce compensated components, this paper proposes a detuned series–series (SS) topology with an improved quadruple-D quadrature (QDQP) pad. The circuit model at resonant and detuned states is built, and the output performance is thoroughly analyzed. Additionally, an improved QDQP pad is designed to strengthen the magnetic field intensity at the horizontal and vertical misalignments. Furthermore, particle swarm optimization (PSO) is employed to achieve wide misalignment tolerance. A prototype with an improved QDQP pad was built to validate the theoretical analysis, and the QDQP pad dimensions are 280 × 280 × 80 mm. Experimental results demonstrate that the proposed IPT system can maintain stable power output within ±140 mm (50%) lateral misalignment and ±10 mm (25%) vertical misalignment, with power fluctuations less than 5%. The maximum output efficiency can reach 91.5%.

In the paper, a four-way wideband filtering power divider (FPD) with an all-port-absorptive feature is presented to fill the gap of FPDs with simultaneous multiway, wideband filtering, good isolation, and all-port absorption features. It consists of two unequal-width three-coupled lines (TCLs), one T-shaped absorptive stub, two composite isolated networks, and two resistors. To obtain wideband filtering responses, the unequal-width TCLs are first utilized. Then, T-shaped absorptive stubs are inserted for obtaining both the input reflectionless and improved isolation between nonadjacent output ports. Composite isolation networks are shunt-connected between adjacent output ports to ensure port-to-port isolation and suppress reflected signals at the output terminals. The resistors are also served for good isolations between adjacent output ports. Theoretical analysis with rigorous closed-form equations is provided. For validation, the four-way prototype was fabricated. Measurements show that the designed FPD exhibits a 10-dB absorption bandwidth of 200% at both the input and output ports with a 3-dB passband bandwidth of 67.3% and out-of-band rejections of larger than 20 dB. Besides, the in-band adjacent and nonadjacent port isolations are 16.7 and 20 dB, respectively.