Jongwon Shin

In this paper, a cell balancing circuit for the Lithium-ion battery string based on the Flyback topology is proposed. The proposed circuit draws the charge out of the high voltage cell and recovers it to the overall battery pack. With the selectivity of the target cell, the proposed circuit uses the minimized power path to simplify the circuit and optimize the balancing efficiency. The circuit also employs the peak current mode control scheme to accelerate the balancing speed and reduce the bala

This paper proposes and analyzes a new bridgeless flyback power factor correction rectifier for ac-dc power conversion. By eliminating four bridge diodes and adding a few circuit elements, the proposed rectifier reduces the primary side conduction loss and improves efficiency. The addition of the new elements has minimal effect on the circuit simplicity because it does not need any additional gate driver and magnetic elements. The losses in the semiconductor devices of the proposed circuit are a

H-bridge converter with additional switch legs (HA converter) and its offspring circuit are proposed in this paper with the intent to reduce the common mode noise. The proposed topology connects grounds of the input and output terminals, which gives zero common mode current in the ideal case. The operation of the proposed circuit is flexible and allows for the circuit to be capable of both ac–dc and dc–ac conversions. The proposed topology is especially advantageous when it is applied to the pho

This paper proposes a digital average current-mode control method in discontinuous conduction mode (DCM) power factor correction rectifier. The proposed control technique does not estimate, but directly senses the average value of the inductor current in each switching cycle. It is implemented by means of a conventional current sensing circuit and a microcontroller. The calculation burden of the microcontroller is the same with that of conventional two-loop-controlled converter because the addit

The layout of a low-permittivity material is designed in a power semiconductor module to reduce parasitic common-mode (CM) capacitance and hence attenuate the CM current. Without sacrificing the thermal performance between the semiconductor devices and heat sink, a portion of the bottom copper of a direct-bond-copper substrate is replaced by air to decrease capacitance. The proposed power module is verified in a 1-kW 100-kHz buck converter. The CM current is decreased by 8 dB in the frequency do

The process parameters of an inductively coupled thermal plasma used for nanopowder synthesis are experimentally investigated using various plasma diagnostics and <I>in situ</I> powder monitoring methods. An enthalpy probe technique is applied to characterize the plasma properties under particle-free conditions. The nanoparticle synthesis from microscale alumina precursors is monitored <I>in situ</I> by optical emission spectroscopy and laser light extinction measurements

The stress response during Pb underpotential deposition on (111)-textured Au has been examined on a cantilever beam electrode in perchloric acid supporting electrolyte. We observe a sweep rate dependence for both the individual voltammetric waves and the stress response that we attribute to kinetically controlled surface alloying [(√3×√3) R30°], which occurs only at low coverage. At high coverage, a hexagonal close-packed (hcp) Pb monolayer is formed while the surface alloy is removed. The stres

The stress behavior of hydrogen adsorption/absorption into Pd layers electrodeposited on (111)-textured gold has been examined in alkaline solution. Although the kinetics are much slower than in acidic solution, the stress induced by H adsorption and absorption is very similar. Hydrogen adsorption causes a −0.46 N/m change in the surface stress. Compressive stress generation is consistent with first principle calculations as well as experimental data for hydrogen on Pt. Hydrogen absorption cause

In this paper, a family of bridgeless power factor correction (PFC) rectifier which configures isolated single-stage is proposed. The proposed PFC rectifiers utilize bidirectional switch to handle both positive and negative input voltage without bridge diodes. Dual output windings of transformer enable the rectifiers dispense with any additional magnetic component. As a member of the proposed rectifier family, a bridgeless flyback PFC rectifier is analyzed and experimented to verify its higher e

In this paper, a digital control method for open-loop interleaving technique for two-phase critical conduction mode (CRM) boost power factor correction (PFC) rectifier is proposed. The proposed control method guarantees the exact phase shift between master and slave module, as well as proper soft switching of slave MOSFET. The phase shift between the modules is maintained in any time including the transient operation, but slight time deviation of turn-on instant of slave MOSFET may occur as a tr

The surface stress associated with the underpotential deposition (upd) of thallium (Tl) on (111)-textured Au is examined, using the wafer curvature method in acidic perchlorate supporting electrolyte. The process is also examined by independent nanogravimetric measurements using an electrochemical quartz crystal nanobalance (EQCN). We observe a sweep rate dependence for both the individual voltammetric waves and stress response, which we attribute to kinetically controlled surface alloying that

Stress generation was examined during the electrodeposition of NixPt1−x alloys from 0.5 M NaCl + 3 mM K2PtCl4 + 0.1 M NiCl2 (pH = 2.5), using the wafer curvature method, in films measuring less than 50 nm in thickness. Steady state tensile stress, ranging from 0.5 to 1.4 GPa, developed in the NixPt1−x films and showed a strong dependence on electrode potential. Deposit grain size, measured by XRD line broadening, appears to be independent of deposition potential, suggesting that nuclei coalescen

This paper proposes a digital average current mode control method in discontinuous conduction mode (DCM) power factor correction (PFC) rectifier. The proposed control technique can directly sense the average value of the inductor current in each switching cycle digitally by employing a conventional current sensing circuit. Thanks to the current control loop, high speed analog-to-digital converters (ADC's) or high performance digital IC's are not needed. The technique achieves lower total harmoni

Voltage of a bus capacitor in a cascaded buck-boost power amplifier is controlled to shape current in an inductive load. Switch-mode converter and inverter output higher power with higher efficiency than linear amplifiers. However, controlling current in the inductive load with low damping is not straightforward due to its inherent instability. Voltage-mode control of a front-end buck converter adjusts the envelope of the load current through a downstream resonant boost inverter and stabilizes t