Tahyun Kang

Comparison of voltage source and current source based Converter in 5MW PMSG wind turbine systems

This paper provides a comparison of power converter loss and thermal description for voltage source and current source type 5MW-class medium voltage topologies of wind turbines. Neutral-point clamped three-level converter is adopted for voltage source type topology while two-level converter is employed for current source type topology considering the popularity in the industry. In order to match the required voltage level of 4160V with the same switching device of IGCT as in voltage source converter, two active switches are connected in series for the case of current source converter. Transient thermal modeling of a four-layer Foster network for heat transfer is done to better estimate the transient junction and case temperature of power semiconductors during various operating conditions in wind turbines. The loss analysis is confirmed through PLECS simulations. The comparison result shows that VSC-based wind turbine system has a higher efficiency than that of CSC under the rated operating conditions.

Comparison of Efficiency for Voltage Source and Current Source Based Converters in 5MW PMSG Wind Turbine Systems

This paper provides a comparison of power converter loss and thermal description for voltage source and current source type 5 MW-class medium-voltage topologies of wind turbines. Neutral-point clamped three-level converter is adopted for a voltage source type topology, whereas a two-level converter is employed for current source type topology, considering the popularity in the industry. To match the required voltage level of 4160 V with the same switching device of IGCT as in the voltage source converter, two active switches are connected in series for the case of current source converter. Transient thermal modeling of a four-layer Foster network for heat transfer is done to better estimate the transient junction and case temperature of power semiconductors during various operating conditions in wind turbines. The loss analysis is confirmed through PLECS simulations. Comparison result shows that the VSC-based wind turbine system has higher efficiency than the CSC under the rated operating conditions.

Loss analysis of current source converter for 10kV IGCT in 7MW PMSG wind turbine systems

This paper provides a power converter loss and thermal description for current source type 7MW-class medium voltage wind turbines. The target current source type converter system employs 10kV IGCT as a main power semiconductor platform which has been recently developed and has the potential to push wind turbine systems to higher power and voltage rating. Transient thermal modelling of a four-layer Foster network for heat transfer is utilized to better estimate the transient junction and case temperature of power semiconductors during various operating conditions in wind turbines. The loss analysis is confirmed through PLECS simulations. The simulation result shows that the largest total losses of CSC is generated under the power factor of 0.9 leading condition. 10kV IGCT and diodes have the potential to improve the power density and reliability of large scaled wind turbine systems.

Optimized coupling factor of multi-winding coupled inductor for minimum inductor current ripple in rapid traction battery charger system

This paper investigates the design of 3-winding coupled inductor for minimum inductor current ripple in rapid traction battery charger systems. Based on the general circuit model of 3-winding coupled inductor together with the operating principles of dc-dc converter, the relationship between the ripple size of inductor current and the coupling factor for a 3-winding coupled inductor is derived under the different duty ratio. The optimal coupling factor which corresponds to a minimum inductor ripple current becomes -0.5, i.e. a complete inverse coupling without leakage inductance, as the steady-state duty ratio operating point approaches 1/3 or 2/3. In an opposite manner, the optimal coupling factor value of zero, i.e. zero mutual inductance, is required when the steady-state duty ratio operating point approaches either zero or one. Coupled inductors having optimal coupling factor can minimize the ripple current of inductor and battery ripple current resulting in a reliable and efficient operation of battery chargers.

Carrier based PWM for three-phase three-switch buck-type rectifier in EV rapid charging system

This paper investigates an economic and highly efficient power converter topology and its modulation scheme for 60kW rapid EV charger system. The target system consists of three-phase three-switch buck-type rectifier topology. A new Carrier Based PWM scheme along with its simple implementation using logic gates is introduced in this paper. This PWM scheme replaces the diode rectifier equivalent switching state with an active switching state producing the effectively same current flowing path. As a result, the distortion of input current during the polarity reversal of capacitor line voltage can be mitigated. The proposed modulation technique is confirmed through simulation verification. The proposed modulation technique and its implementation scheme can expand the operation range of the three-phase three-switch buck-type rectifier having ac input and capacitor ripple current of high quality.

Reduced Current Distortion of Three-Phase Three-Switch Buck-Type Rectifier using Carrier Based PWM in EV Traction Battery Charging Systems

This study investigates an economic and highly efficient power-converter topology and its modulation scheme for 60 kW rapid EV charger system. The target system is a three-phase three-switch buck-type rectifier topology. A new carrier-based PWM scheme, which is characterized by simple implementation using logic gates, is introduced in this paper. This PWM scheme replaces the diode rectifier equivalent switching state with an active switching state to produce the same effective current flowing path. As a result, the distortion of input current during the polarity reversal of capacitor line voltage can be mitigated. The proposed modulation technique is confirmed through simulation verification. The proposed modulation technique and its implementation scheme can expand the operation range of the three-phase three-switch buck-type rectifier with high-quality AC input and capacitor ripple current.

Design of coupled inductor for minimum inductor current ripple in rapid traction battery charger systems

This paper investigates the design of coupled inductor for minimum inductor current ripple in rapid traction battery charger systems. Based on the general circuit model of coupled inductor together with the operating principles of dc-dc converter, the relationship between the ripple size of inductor current and the coupling factor is derived under the different duty ratio. The optimal coupling factor which corresponds to a minimum inductor ripple current becomes -1, i.e. a complete inverse coupling without leakage inductance, as the steady-state duty ratio operating point approaches 0.5. In an opposite manner, the optimal coupling factor value of zero, i.e. zero mutual inductance, is required when the steady-state duty ratio operating point approaches either zero or one. Coupled inductors having optimal coupling factor can minimize the ripple current of inductor and battery current resulting in a reliable and efficient operation of battery chargers.