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The bidirectional isolated AC/DC converter is widely used in the past decades. Most of the topologies are based on voltage source converter. However, the performance of the voltage source based converter is significantly limited by the bulky energy storage element, the range of soft switching, the leakage inductance of the transformer and so forth. A current fed isolated AC/DC converter is studied...
This paper presents a single stage, bi-directional multi-level converter topology with a multi-winding medium frequency transformer (MFT) isolation to interface a low voltage DC with a 3-phase high voltage grid. The proposed topology can be used for integrating 3-ph utility grid with various low voltage renewables like solar photovoltaic, fuel cells etc. The transformer secondary windings in each...
A way to describe the LLC ballast in tranconductance Gm mode for current conversion to drive LED streetlight is proposed. On Gm description, the load response can be clearly observed in Region 2 since the transfer curves can be expanded outward as per the increase of the quality factor, and no curves huddled; in contrast, it is difficult to obviously view the load behavior in that region by using...
Indirect field oriented control of induction machine has been widely applied in industry applications. This control scheme is relatively simple but strongly relies on the parameters of the machine, such as the rotor time constant and mutual inductance. The parameter deviation could result in the decrease of control performance, and this is vital especially for the torque control mode. In this paper,...
Highly distributed, low-power photovoltaic-based energy systems require high-efficient and compact DC-DC converters. In the microgeneration field, the connection of a single panel to a high-voltage DC-bus, required for direct connection to the grid can be made using an isolated converter. However, non-isolated solutions have some advantages but require a high voltage gain, which only a small set of...
This paper presents the precise measurement of the stator inductance as well as the stator resistance, using an inverter. Precise measurement results are created, although the actual output voltage of the inverter is not known exactly. This paper analyzes the different effects of an output power stage, and how they degrade the quality of the output voltage. This knowledge is used to cancel out this...
This paper presents a comprehensive methodology for topology evaluation of bidirectional boost converters in electrified vehicle applications for higher power density. Based on the given specifications, major components in the converters are designed and sized, including the boost inductor, power module, and DC-link capacitor. 3D Finite Element Analysis (FEA) simulations are conducted to evaluate...
This paper proposes an improved cell balancing circuit for fast equalization among the lithium ion (Li-ion) batteries. Usually, the battery cell balancing circuit uses the sensor to estimate the accurate SOC (state of charge) of each battery cell and to operate the switch selectively [1], but it makes the system bulky and expensive. A simple voltage sensorless charge balancing circuit has been proposed...
A switching control strategy is proposed for single inductor current-fed push-pull converter with a secondary side active voltage doubler rectifier or a voltage rectifier used in photovoltaic (PV) grid interfacing. The proposed switching control strategy helps to turn-on and turn-off the primary side power switches with zero-voltage and zero-current switching. The operation of the push-pull converter...
The conventional PSFB converter has received considerable attentions for medium- or high-power applications, which is because it features high conversion efficiency and high power density. However, the hold-up-time requirement limits its operating duty ratio in nominal state and it increases the conduction loss caused by circulating current. Therefore, by introducing an auxiliary coupled inductor...
This paper deals with the switching behavior of a SiC MOSFET in a TO-247 package. Based on simulations, critical parasitic inductances in the circuit layout are analyzed and their effect on the switching losses highlighted. Especially the common source inductance, a critical parameter in a TO-247 package, has a major influence on the switching energy. Crucial design guidelines for an improved double...
This paper presents a comprehensive analysis and discussion of how to design a high resolution and low thermal drift eddy current sensor (ECS). A simple transformer based equivalent model was presented to explain the influence of target conductivity and working frequency to the ECS's sensitivity and stability. The relationships between the ECS's performances and target conditions were also obtained...
Sensorless position estimation based on signal-injection methods always requires a resistance- or inductance-based anisotropy. One way to influence the differential inductances of an electrical machine is the use of a short-circuited electrical winding on the rotor surface. This method is applied to an interior permanent magnet (TPM) machine in this paper. In order to investigate the suitability of...
This paper proposes a new adaptive control technique of the auxiliary branch of the resonant snubber inverter for photovoltaic (PV) applications. By varying the turn-on time of the auxiliary branch based on the load current, the auxiliary resonant current is reduced without the need for any additional components, decreasing the circulating losses and improving system efficiency. An analysis of the...
An optimized modulation is proposed for the bidirectional DC-DC converter based on the full-bridge/push-pull circuit. With the proposed strategy, the zero-voltage-switching (ZVS) range of the lagging-leg switches in the conventional full-bridge topology can be extended. Moreover, severe voltage overshoots across main switches caused by the leakage inductance of the transformer in the current push-pull...
Wide band gap semiconductor devices have a promising future in various power converter applications due to their higher performance characteristics such as high frequency, high voltage and high operating temperature. For power switching applications, wide band gap materials mainly Silicon Carbide (SiC), Gallium Nitride (GaN) and Diamond are attractive. In this paper, the detailed design analysis for...
An isolated medium frequency zero voltage zero current switching (ZVZCS) DC/DC converter for HVDC transmission system is proposed. Soft switching is achieved over the entire load range, via resonance between transformer leakage inductance and capacitance across primary switches. Since transformer leakage inductance is utilized in the resonant circuit, its design procedure is elaborated as well. Finite...
The power losses of three-level neutral-point-clamped (NPC) converters and their AC-filters with iron and amorphous core inductors designed for a bipolar low voltage direct current (LVDC) distribution network are evaluated. The main objectives of the LVDC distribution network are improved energy efficiency, power quality and reliability and higher power transmission capacity and integration of ICT...
While permanent magnet motors are increasingly being utilized in high performance and high power-dense drives, the induction motor is still almost universal for new electric train drives and gaining popularity in vehicular drives. This is on top of their traditional role as an industrial drive motor for pumps and fans and also their use in servos. The key to good control of these motors is accurate...
The Switched Reluctance Machine (SRM) is known for being one of the oldest electric machine designs. Unfortunately, it is usually assumed that this implies that the machine is outdated. However with the advent of microprocessors, the SRM has become a suitable option for a number of applications because the shortcomings of the machine can be mitigated with control. Compared to other machines, the SRM...
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