Semi-bridgeless Active Rectifier Research Articles

A Minimum ZVS Current Control Strategy of Semi Bridgeless Active Rectifier for Wide Operation Range Based on LCC-S Compensated WPT System

To meet the requirement of the battery charging characteristics and electric vehicle interoperability, wide power range and wide voltage range are important for the wireless electric vehicle (EV) charging system. Hence, ensuring zero voltage switching (ZVS) and high efficiency over the wide operating range is a hot issue but not well resolved. To address the current state of research, an efficiency-oriented control strategy is proposed for LCC-S compensated Wireless Power Transfer (WPT) system to achieve minimum ZVS current over a wide voltage and power regulation range. Based on the accurate harmonic-considered time-domain model, a universal design method for system parameters under the worst ZVS current conditions within wide operation range is proposed. Then, the universal explicit expression at the unit voltage gain point is given. Moreover, based on the simplified fitting method of piecewise bi-quadratic interpolation (PBQI), minimum ZVS current and minimum non-active current can be ensured over the full output voltage and output power range. A 3.3 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> W prototype has been built to verify that the converter can realize ZVS within the whole voltage range, the measured peak efficiency is about 95.2%.

Load Independent Constant Current and Constant Voltage Control of LCC-Series Compensated Wireless EV Charger

In this article, load-independent constant current/voltage control operations of an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCC</i> -Series compensated wireless electrical vehicle (EV) chargers are presented. The parameters of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCC</i> -Series compensation topology are designed based on load-independent zero phase angle and soft switching operation in the constant current charging operation. Then, the load independent soft switching conditions are achieved for constant voltage charging operation with a semibridgeless active rectifier using pulse density modulation control. Thus, high efficiency power transfer to the load is performed during the entire charging period. The wireless communication is not needed to achieve the output voltage regulation in the proposed EV charging system. The soft switching operations of the switches on the primary and the secondary side are achieved in a wide load range. The performance of the proposed charging system is validated by a prototype. At the full load condition, the output voltage of the system is regulated at 210 V while the output current is 5 A. The maximum efficiency is measured 93.8% at 1 kW output power with 150 mm air gap. The efficiency performance of the system is also evaluated based on the misalignment conditions.

Duty Cycle Control Strategy for Dual-Side LCC Resonant Converter in Wireless Power Transfer Systems

The dual-side inductor–capacitor–capacitor (LCC) topology circuit has been widely adopted in wireless power transfer (WPT) systems due to its constant output current characteristic. However, most conventional control methods need specific synchronization techniques between the primary and secondary sides to avoid the oscillation in the system, which increases the cost and control complexity. To solve this issue, this article proposes a new duty cycle control (DCC) strategy for a dual-side LCC resonant converter with a semibridgeless active rectifier (SAR). With such a control strategy, gate signals of the primary- and secondary-side circuits do not need to be synchronized, which could reduce the complexity and the cost of the WPT system. Besides, the switching frequency of the secondary side can be decreased significantly. This article first presents the modal analysis of phase shift control (PSC) and DCC. Then, generalized state-space averaging (GSSA) modeling with PSC and the hybrid average modeling with DCC are performed. In addition, controllers’ design for both strategies is conducted to achieve the constant output voltage. Finally, the eigenvalues’ analysis is used to determine the stability region of the WPT system. The theoretical analysis has been validated by both simulation and experimental results.

High efficiency constant voltage control of LC/S compensated wireless power transfer converter based on pulse density modulation control

ABSTRACT In this work, the secondary side controlled wireless power transfer (WPT) converter using a LC/S compensation topology is proposed. The constant voltage charging control mode of the proposed converter is evaluated based on high efficiency. In the secondary side, a semi-bridgeless active rectifier (SBAR) is used for the output voltage regulation. In order to improve the efficiency performance of the converter, the pulse density modulation (PDM) control method is applied to the switches of the SBAR. The primary switches operate at the constant operation frequency as independent of the secondary side. There is no communication needed between primary and secondary sides of the proposed converter. Besides, the switches of the SBAR operate with soft switching. The basic principles of the LC/S compensation network and SBAR topology are presented with steady state analysis. The PDM control strategy applied to the switches of the SBAR is discussed. In order to validate the performance of the proposed converter, a prototype is built with 8 cm air gap coreless coupling coils. The input voltage of the converter is 30 V, and its maximum output power is 60 W. The maximum efficiency is achieved as 85.26% at full load condition during CV regulation.

A Dual-Sided Control Strategy Based on Mode Switching for Efficiency Optimization in Wireless Power Transfer System

Transfer efficiency of a wireless power transfer (WPT) system is tightly related to the load, which varies greatly in a wide range during the charging process. Generally speaking, dual-sided control strategies are commonly applied to overcome the load variation and improve system efficiency. However, the system may suffer from hard switching, high control complexity, and auxiliary dc/dc converters. In this article, a dual-sided control strategy based on mode switching is proposed to approach an optimal load impedance, zero-voltage switching of all mosfets in WPT system, and a required output. In this control strategy, the output voltage of the inverter is adjusted in a wide range by switching the operation mode of the inverter to approach the optimal load impedance. The output current/voltage is regulated by the active rectifier control. Besides, a novel phase-locked method is proposed for the semi-bridgeless active rectifier control, which is simpler compared with the traditional phase-locked method. Finally, a 500-W prototype is built to verify the theoretical analysis, and the peak system efficiency of 93.9% is gained with k = 0.23.

Analysis of Impedance Tuning Control and Synchronous Switching Technique for a Semibridgeless Active Rectifier in Inductive Power Transfer Systems for Electric Vehicles

In inductive power transfer (IPT) systems, load, and magnetic coupling variations cause an impedance mismatch. Impedance mismatch is one of the most serious problems in IPT systems for electric vehicles (EVs) because an EV is not always parked in the same location. Therefore, an impedance tuning control for semibridgeless active rectifiers (SBARs) is proposed in this article to compensate for this mismatch. The proposed impedance tuning control is achieved by adjusting the turn-on point and duty of the SBAR without using any additional component. Moreover, a technique for detecting the voltage-rising edge of the SBAR switch is proposed to extract the switching frequency and to synchronize the SBAR with the primary system. A 3.3-kW prototype of the IPT system with the SBAR is manufactured, and the proposed impedance tuning control is verified through experimental results according to the coupling coefficient. The proposed control can achieve an efficiency improvement of 6.4% under the impedance mismatch.

Quasi-Independent Bidirectional Communication Methods for Simultaneous Wireless Power and Information Transmission

Simultaneous wireless power and information transmission (SWPIT) is essential for power regulation, load detection, and maximum efficiency tracking in wireless power transfer (WPT) systems. To eliminate the interaction between power and information transmission, this paper proposes a novel bidirectional communication method based on differential phase shift keying (DPSK). First, the steady-state and transient models of the series–series compensated WPT system are established to analyze the characteristics of power transmission and the behavior of shared power/information channel. Second, regarding the stability of power transmission, principles of the forward and backward communication that integrated with power modulation through the full-bridge inverter and the semi-bridgeless active rectifier are elaborated. Then, the demodulator and half-duplex communication protocol are designed. Finally, the simulation is carried out and the experimental prototype is established, which shows that the proposed DPSK method is effective and the transmission of power and information is quasi-independent. Owing to the integration of power and information transmission, the complexity, cost, and volume of the SWPIT system are reduced significantly.

Modeling and Control of Double-Sided LCC Compensation Topology with Semi-Bridgeless Active Rectifier for Inductive Power Transfer System

This paper proposes the modeling and design of a controller for an inductive power transfer (IPT) system with a semi-bridgeless active rectifier (S-BAR). This system consists of a double-sided Inductor-Capacitor-Capacitor (LCC) compensation network and an S-BAR, and maintains a constant output voltage under load variation through the operation of the rectifier switches. Accurate modeling is essential to design a controller with good performance. However, most of the researches on S-BAR have focused on the control scheme for the rectifier switches and steady-state analysis. Therefore, modeling based on the extended describing function is proposed for an accurate dynamic analysis of an IPT system with an S-BAR. Detailed mathematical analyses of the large-signal model, steady-state operating solution, and small-signal model are provided. Nonlinear large-signal equivalent circuit and linearized small-signal equivalent circuit are presented for intuitive understanding. In addition, worst case condition is selected under various load conditions and a controller design process is provided. To demonstrate the effectiveness of the proposed modeling, experimental results using a 100 W prototype are presented.

Improved Pulse Density Modulation for Semi-bridgeless Active Rectifier in Inductive Power Transfer System

This paper proposes an improved pulse density modulation (IPDM) power control method for semi-bridgeless active rectifier (SBAR) in inductive power transfer (IPT) system. In this method, the input voltage pulse sequences of the SBAR can be distributed more evenly compared with the traditional PDM, so the output voltage ripple can be reduced effectively. Besides, for multiple paralleled pickups, the interleaved IPDM is developed to further suppress the output voltage ripple. In addition, the characteristics of zero-voltage switching and zero current-switching for the SBAR's switches can also be achieved in the proposed IPDM method by synchronization control for the gate signals of the SBARs. The experimental results on a 30 kW IPT prototype with four paralleled pickups verified the proposed method.

A novel pulse density modulation with semi-bridgeless active rectifier in inductive power transfer system for rail vehicle

In this paper, a novel pulse density modulation (PDM) with semi-bridgeless active rectifier (S-BAR) in inductive power transfer (IPT) system for rail vehicle is proposed. It is to reduce switching losses of the active rectifier in pickups. In the control method, the insulated-gate bipolar transistors (IGBTs) in the S-BAR are controlled by synchronous PDM signals, so that zero-voltage switching (ZVS) and zero-current switching (ZCS) can be achieved in the whole output power range. The output power is regulated by changing the pulse density (PD) of the S-BAR since the it is almost linear proportional with the PD in high quality factor of pickup side. The communication device between the primary side and pickup side is not necessary anymore. The detailed theoretical analyses of the PDM method are provided, and its advantages are shown in a 7.5kW IPT prototype for rail vehicle. The experimental results are presented to verify the analysis and demonstrate the performance. The overall efficiency of the system by PDM control is 74.2% which is improved by 4% compared with phase shift (PS) control at light load.

Analysis of a CLL Resonant Converter With Semi-Bridgeless Active Rectifier and Hybrid Control

A novel CLL resonant converter with a semi-bridgeless active rectifier (S-BAR) is analyzed, and its hybrid control strategy is proposed in this paper. This topology is developed by replacing rectifier lower diodes with synchronous switches and regulation by a phase-shifted pulsewidth-modulation signal. Theoretical and simulation results show that the performance of the proposed S-BAR is appropriate for resonant converters and secondary-side controlled infrastructure requiring a wide voltage range control at the secondary side. The hybrid control algorithm is obtained with the phase-shift and frequency tuning considering the voltage at the load terminal. High efficiency can be maintained by this proposed control, reducing conduction losses and providing zero-voltage switching soft-switching condition with a wide output voltage range. To confirm the performance of the proposed converter, experimental results are provided for which the output voltage/current range from 0 to 80 V/0 to 8.75 A with an input of 120 V and an average efficiency value of 93%.

A Novel Phase-Shift Control of Semibridgeless Active Rectifier for Wireless Power Transfer

A novel phase-shift control of a semibridgeless active rectifier (S-BAR) is investigated in order to utilize the S-BAR in wireless energy transfer applications. The standard receiver-side rectifier topology is developed by replacing rectifier lower diodes with synchronous switches controlled by a phase-shifted PWM signal. Theoretical and simulation results show that with the proposed control technique, the output quantities can be regulated without communication between the receiver and transmitter. To confirm the performance of the proposed converter and control, experimental results are provided using 8-, 15-, and 23-cm air gap coreless transformer which has dimension of 76 cm × 76 cm, with 120-V input and the output power range of 0 to 1kW with a maximum efficiency of 94.4%.