Performance Evaluation of a Permanent Magnet Electric-Drive- Reconfigured Onboard Charger with Active Power Factor Correction

This paper presents a comprehensive charging operation for an electric-drive-reconfigured onboard charger(EDROC)with active power factor correction(APFC).The charging topology exclusively utilizes the three-phase permanent magnet synchronous motor(PMSM)propulsion system as a three-channel boost-type converter in which only a contactor and a small diode bridge are added.First,the operation scenario of the EDROC is introduced.Second,the relationship between electromagnetic torque and rotor position is investigated.Third,the current ripple cancellation of the EDROC is discussed in detail.Moreover,to implement the single-phase APFC along with charging voltage/current regulation of propulsion battery,control strategies including current balancing and synchronous/interleaving PWM strategies are incorporated.Finally,200W proof-of-concept prototype-based tests are conducted under different operation scenarios.

Generalized multilevel current source inverter topology with self-balancing current

A generalized single-phase multilevel current source inverter (MCSI) topology with self-balancing current is proposed, which uses the duality transformation from the generalized multilevel voltage source inverter (MVSI) topology. The existing single-phase 8-and 6-switch 5-level current source inverters (CSIs) can be derived from this generalized MCSI topology. In the proposed topology, each intermediate DC-link current level can be balanced automatically without adding any external circuits; thus, a true multilevel structure is provided. Moreover, owing to the dual relationship, many research results relating to the op- eration, modulation, and control strategies of MVSIs can be applied directly to the MCSIs. Some simulation results are presented to verify the proposed MCSI topology.

ANALYSIS OF EDL EFFECTS ON THE FLOW AND FLOW STABILITY IN MICROCHANNELS

The effects of the Electrical Double Layer （EDL） on the liquid mean flow and the flow stability in microchannels are investigated by solving the Poisson-Boltzmann equation. The models of the traditional streaming Electrical Current Balance （ECB） and the newly introduced streaming Electrical Current Density Balance （ECDB） are applied to determine the electrical streaming current. The numerical results show that the electrical streaming current backflow in the ECB model near the wall can be removed by using the ECDB model, which is suitable to study the effects of the EDL on the mean flow and the flow stability in microchannels. The flow is found more unstable if the ECDB model is applied.

China's Large and Rising Net Foreign Asset Position

China＇s emergence as a major player in world trade is well known, but its growing role in global finance might have been underappreciated. China is the second largest creditor in the world today, with a net creditorposition of 30 percent of GDP in 2008. We test the importance of the growth differential, demographics, government debt, financial depth and the exchange rate in shaping China＇s net foreign asset position. Our empirical results highlight the sharp fall in the young-age dependence as one key driver behind China ＇s puzzlingly large net lender position and also confirm the neoclassical prediction that faster growth attracts more capital inflows. Looking ahead, our findings suggest that China will unlikely turn into a meaningful net debtor nation over the next two decades.

A Double Input-parallel-output-series Hybrid Switched-capacitor Boost Converter

A double input-parallel-output-series hybrid switched-capacitor boost(DIPOS-HSCB)converter is proposed which consists of two different kinds of input-parallel-output-series(IPOS)circuits,i.e.,inner IPOS circuit and outer IPOS circuit.Two boost modules and one switched-capacitor network build an inner IPOS circuit based IPOS-HSCB converter and two IPOS-HSCB converters develop the outer IPOS circuit based DIPOS-HSCB converter.With the proposed DIPOS-HSCB converter,a high voltage-gain with low component stress and small input current ripple are achieved.Furthermore,an automatic current balancing function for all input inductor currents can be also achieved using a special carrier phase-shifted modulation scheme.A prototype rated at 200 V/120 W has been developed and the maximum efficiency of the proposed DIPOS-HSCB converter is 95% at 120 W.Both steady and dynamic results are presented to validate the effectiveness of the proposed DIPOS-HSCB converter.