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The realization of wide input voltage and high power density on the conventional current resonant converter such as LLC converter remarkably increases transformer winding loss and its design difficulty. Therefore, it is difficult for the conventional LLC converter to satisfy both requirements. In order to apply the LLC converter with both conditions, this paper investigates the mechanism of the transformer winding loss occurrence in the conventional LLC converter. Moreover, the solution for mentioned above problems is proposed which can removes the transformer design difficulty as well by only changing the resonant operation mode., Power Electronics and Applications (EPE'17 ECCE Europe), 2017 19th European Conference on, 11-14 Sept. 2017, Warsaw, Poland

In this study, integrated buck-boost converter with the Matrix-POL power supply system is proposed. From the simulation results, the validity of the Matrix-POL is revealed. The results revealed that the fast response to the load current and the voltage change can be done with duty and parallel number control by the proposed system., 2013 15th European Conference on Power Electronics and Applications, EPE 2013; Lille; France; 2 September 2013 through 6 September 2013, Power Electronics and Applications (EPE), 2013 15th European Conference on, pp.1-8; 2013

Output-inductor-less full-bridge converter for a High-Voltage Direct-Current power distribution system has been proposed. This proposed circuit topology suppresses the surge voltage due to the secondary-side diode's recovery, and miniaturizes the converter because the number of circuit components is reduced. On the other hand, some problems occur, such as the increasing switching-loss of primary switches and another high-frequency noise generation. This paper proposes a novel synchronous rectifier driving for the output-inductor-less full-bridge converter in order to solve these problems, and examines the noise reduction effect, and the relationship between ZVS operation conditions and circuit parameters. The proposed method does not need an external component, and then the smaller size is maintained. Furthermore, the experimental results confirm the power loss reduction of 20W in a wide load range, and also the noise reduction.

We propose a multi input voltage and multiple output voltage DC-DC converter using H-bridge converter for power supply on chip. We analyzed the operation mode of the H-bridge converter and also propose the suitable operation mode for power supply on chip. The proposed POLs realize stable output voltage and high efficiency over the wide range through digital control.

This paper proposes a PFM+PWM hybrid controlled soft-switching half-bridge converter which has both benefit of conventional half-bridge converter and LLC converter. Generally, conventional half-bridge converter has good constant current characteristic due to PWM control, however it has some drawbacks of (1) primary side switches and secondary side diodes operate under hard switching, (2) two magnetic components. Meanwhile, the LLC resonant converter has the benefit of achieving ZVS and ZCS, however it can't realize a constant current (CC) characteristic because of resonant fashion. In order to achieve soft-switching and CC characteristic using half-bridge converter, a DCM operation are employed, which can be controlled by PWM+PFM Hybrid Control. In this paper the operating characteristics of the proposed half-bridge converter are experimentally verified. The experimental results for 48Vin, 16Vo, 80W board achieves 90% efficiency and validated this method is useful practically.

This paper presents the high power density and high efficiency DC-DC converter for 400V-DC power distribution system. The full-bridge converter is used for typical topology. However, there are some problems such as surge voltage occurrence. Here, the miniaturization of isolated DC-DC converter using the LLC resonant converter which can achieve soft-switching operation without auxiliary circuit is considered. The prototype test circuit is evaluated by experimentally. As a result, the high power density of 12.5W/cm3 and high efficiency of over 95% is achieved.

So far, the operating characteristics of asymmetry type current resonant converter as LLC converter are discussed in detail. However, the detail operating characteristics discussions of symmetry type resonant converter have not been carried out. This paper investigates the AC characteristics of symmetry type bi-directional current resonant converter, and their soft-switching regions are also investigated.

Recently, the series resonant converter is widely used for various applications. Moreover, the synchronous rectifier technique has been investigated in low voltage application achieving higher efficiency. The bi-directional series resonant converter can be realized by establishing the synchronous rectifier technique. This paper investigates the ac equivalent model and operating characteristics of bi-directional series resonant converter.

This paper presents the power density developments of high-power isolated dc-dc converter to be utilized in a higher voltage direct-current (HVDC) power-supply system of a data center. This technique results in a prototype of dc-dc converter unit which is smaller by factor of ten when compared with the conventional one, and the area of power-supply system becomes much smaller than before. Consequently, the cooling power for this power-supply system is saved and both the energy and the space saving are available. In order to realize a prototype of the high-power isolated dc-dc converter, the switching power devices composed of a hybrid pair of Si-CoolMOS and SiC-SBD are utilized and operated in a driving pattern of hard switching with a frequency of 200kHz. As a result, an isolated dc-dc converter with the input/output voltage of 400V/400V, a rating power of 5kW, and a high power density of 10W/cm3 has been fabricated. The experimental confirmation was reported and the surge problems due to diode recovery difficulties mentioned before was solved.

Low-profile, high efficiency power supply is today's industry trend for Plasma Display Panel (PDP) application system. Transformer is the major challenge and bottleneck for achieving low-profile, high power density converter. Generally, it is necessary for low-profile converter to operate it at high switching frequency. However, it is very difficult to design converter using flat magnetic component because flat transformer temperature becomes high at high switching frequency. In this paper, the design and analysis of flat transformer in LLC resonant converter for the PDP TV is proposed to reduce temperature of the transformer. In this proposed converter, flat transformer is integrated into advanced power conversion application systems. Low-profile power module of profile of about 14mm is achieved. Temperature inside of transformer repressed to 71oC and an overall efficiency of about 96.6% was obtained.

In this paper, a power factor correction (PFC) based on active-clamped full-wave quasi-resonant (ZCS-QR) boost converter is presented. This circuit is characterized by zero-voltage-switched (ZVS) and zero-current-switched (ZCS) that results in higher efficiency, opens possibility to incorporate higher switching frequency, and has some potency to reduce converter's conducted EMI. The working principle and steady state performance of the proposed converter are presented. A 100 V dc input, 180 W maximum output, and 440 kHz resonant frequency experimental circuit has been built. Maximum efficiency of 93% and the proof of compliance to the IEC61000–3–2 class D have been confirmed by experiment.

This paper presents the design and implementation of LLC resonant converter using planar magnetic component. In the LLC resonant converter, ZVS turn-on and ZCS turn-off of MOSFETs and diode rectifiers can be achieved over the entire operating range, respectively. Therefore, the switching loss is reduced and we can operate the converter at higher switching frequency. At that frequency, planar magnetic component is a viable option. In this proposed converter, the magnetic component is integrated into advanced power conversion technique to implement a low-profile power supply for PDP application systems. An efficiency of about 96.7% was obtained.

This proposed boost converter utilizes active-clamp circuit to achieve zero-voltage-switched (ZVS) transition in a full-wave zero-current-switched quasi-resonant (ZCS-QR) converter. The ZCS-ZVS switching transition results in higher efficiency, better output voltage regulation, opens possibility to incorporate higher switching frequency, and has some potency to reduce converter's conducted EMI. It is important to note that the active-clamp circuit works under ZVS condition. Therefore, this switch will not cause excessive losses and extra EMI. In this paper, the working principle and steady state performance of the proposed boost converter are presented. A 100 V dc input, 300 W maximum output, and 430 kHz resonant frequency experimental circuit has been built. Maximum efficiency of 95.6% has been confirmed by experiment., 2009 IEEE 6th International Power Electronics and Motion Control Conference : Wuhan, 2009.05.17-2009.05.20, IPEMC '09, pp.556-560

Recently, the distributed power system consists of bus converter and POL is usually used for IT infrastructure equipment. The system may become unstable depending on the bus converter design even if each converter has stable operation. Then, the bus voltage is oscillated. Recently, stability problems in distributed power system become series. It is required to overcome these problems as soon as possible. This paper investigates, the improvement of the system stability by the control method. As a result, the full-regulated bus converter is the best as a control method of the bus converter because the full-regulated bus converter can reduce the bus voltage oscillation and correspond to the input voltage variation flexible by the regulation.

The bus architecture, consisting of bus converter and POLs (point of load), has become very popular since POL can respond to some demands of multi power supply voltage, low driving voltage and series sequence/tracking of LSI with more flexibility than isolated DC-DC solution. However, the customer suffers the system instability issue caused by impedance overlap between the bus converter and POL. Bus converter has three types i) un-regulated, ii) semi-regulated, iii) full-regulated, and each type has different output characteristic. This makes matter more complex to understand and difficult to resolve the instability phenomena. This paper investigates the comparison of the stability of three types of bus converter and POL using steady state average model. As a result, it has been found that "un-regulated bus converter+POL" is the most stable, "full-regulated bus converter+POL" is next due to dumping of the resonant peak of impedance by the loop feedback, "semi-regulated bus converter+POL" is the most un-stable, therefore a large capacitor at the intermediate bus is needed

This paper presents the improvement of the transient response and stability for a two-stage DC-DC converter by removing the output inductor. The conventional two-stage converter consists of a buck converter used as the first stage and a half-bridge converter used as the second stage. The proposed circuit topology removing the output inductor and the conventional topology are compared. Removing the output inductor results in the system-order reduction of the transfer function. As a result, the stability is improved, and the crossover frequency of the open-loop transfer function becomes higher. The effectiveness of the proposed circuit topology was experimentally confirmed.

The two-stage DC-DC converter is developed for power supply of telecommunication application. This converter consists of a buck topology in the first stage and a half-bridge topology in the second stage. In order to reduce the system order, the output inductor is removed form this topology, then this system can be treated as a second-order system in approximation. As a result, the stability and the transient response are improved. Further improvement is required. This paper presents the effect of current mode control on the transient response in an output-inductorless two-stage DC-DC converter. As a result, output voltage drop is reduced by around 25% and the settling time is reduced by around 36% when compared with the voltage feedback control, and the effectiveness of the current mode control is experimentally confirmed.

This paper presents the fast transient response improvement of two-stage DC-DC converter by using the current feedback control. The two-stage converter consists of a buck converter used as the first-stage and a half-bridge converter used as the second-stage. The proposed control system using the first-stage inductor current and the conventional voltage-feedback control system are analyzed and compared. As a result, it is analytically clarified that the crossover frequency becomes higher by adding the first-stage inductor current in the feedback control loop. The experimental confirmation was obtained with a good agreement, and the effectiveness of the proposed control strategy was verified.

This paper presents the fast transient response improvement of a two-stage DC-DC converter by using the current feedback control. The two-stage converter consists of a buck converter used as the first stage and a half-bridge converter used as the second stage. The proposed control system using the first-stage inductor current and the conventional voltage-feedback control system are analyzed and compared. As a result, it is analytically clarified that the crossover frequency becomes higher by adding the first-stage inductor current in the feedback control loop. The experimental confirmation was obtained with a good agreement, and the effectiveness of the proposed control strategy was verified.