• Journal of Power Electronics
• /
• v.8 no.3
• /
• pp.275-279
• /
• 2008

An LLC series resonant converter has many unique characteristics and improvements over PWM topologies. However, many output capacitors are needed in parallel to satisfy output voltage ripple and the rated ripple current of the capacitors. This paper deals with a novel two phase interleaved LLC resonant converter using a phase of the resonant capacitor. The proposed converter can satisfy output voltage ripple and a rated ripple current of capacitors with few output capacitors, relatively. The operation and features are considered in detail and a prototype with a 12V-100A output is investigated.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.65 no.11
• /
• pp.1925-1930
• /
• 2016

Fuel cell power generation system, unlike conventional energy sources, converts chemical energy into electrical energy through electrochemical reaction of hydrogen and oxygen. This paper presents the control of interleaved multi-phase boost converter as the feasibility study on small-scale prototype electric railway vehicle application using fuel cell generation system. PSIM simulation program is to be used to implement the modeling of the electrical fuelcell as well as traction motor control with interleaved multi-phase boost converter. Comparing the input current ripple rate, two-phase interleaved boost converter is less than the boost converter. But the more multi-phase not less proportional to the ripple factor. we confirmed that the amplitude of the input current ripple rate of converter depend on duty ratio.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.3 no.3
• /
• pp.256-262
• /
• 1998

The torque of SRM depends on phase current and the derivative of inductance. But the inductance of SRM is nonlinearly changed according to rotor position angle and phase current because of saturation in magnetic circuit, and it is difficult to control the desired torque. This paper proposes inductance modeling method using ANN(Artificial Neural Network) that is used to simulate the inductance which is nonlinearly varied with rotor position and current. The torque ripple is analyzed and input voltage and current condition to reduce torque ripple is simulated by inductance model.

• Proceedings of the KIPE Conference
• /
• 2008.06a
• /
• pp.526-528
• /
• 2008

LLC series resonant converter has many unique characteristics and improvement over PWM topologies. However, many output capacitors should be needed in parallel to satisfy an output voltage ripple and a rated ripple current of the capacitors. This paper is deal with a novel two phase interleaved LLC resonant converter using a phase of the resonant capacitor. The proposed converter can satisfy output voltage ripple and a rated ripple current of capacitors with few output capacitors, relatively. The operation and features is considered in detail and a prototype with a 12V-100A output is investigated.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.9 no.2
• /
• pp.126-133
• /
• 2004

In this paper, a new current control algorithm is proposed for four-switch three-phase brushless DC(BLDC) motor drives, which are suitable for low cost applications. A current reference generation scheme is developed and implemented to obtain high performance characteristics in the four-switch system, such as small torque ripple and fast dynamic speed/torque response. Especially, the proposed scheme can successfully reduce the torque ripple during commutations, so that it can be expected that the four-switch system can be much more practically applied for the industrial application areas.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.22 no.5
• /
• pp.449-456
• /
• 2017

This study proposes a method for compensating for the commutation torque ripple of delta-connected brushless DC motors with low inductance based on a current predictions. At the commutation instant, a phase current at the next sampling period is predicted and compared with the reference phase current to determine whether torque ripples will occur or not. If the predicted current cannot reach the reference phase current, the reference current is modified and the relevant voltage reference is produced to reduce the torque ripple. The validity of the proposed method has been verified by simulation and experimental results. The commutation torque ripple has been decreased by 17.7% at 1,000 rpm and 80% load conditions.

• ETRI Journal
• /
• v.42 no.5
• /
• pp.790-798
• /
• 2020

Herein, a low-ripple coarse-fine digital low-dropout regulator (D-LDO) without ringing in the transient state is proposed. Conventional D-LDO suffers from a ringing problem when settling the output voltage at a large load transition, which increases the settling time. The proposed D-LDO removes the ringing and reduces the settling time using an auxiliary power stage which adjusts its output current to a load current in the transient state. It also achieves a low output ripple voltage using a comparator with a complete comparison signal. The proposed D-LDO was fabricated using a 65-nm CMOS process with an area of 0.0056 μ㎡. The undershoot and overshoot were 47 mV and 23 mV, respectively, when the load current was changed from 10 mA to 100 mA within an edge time of 20 ns. The settling time decreased from 2.1 ㎲ to 130 ns and the ripple voltage was 3 mV with a quiescent current of 75 ㎂.

• Proceedings of the KIPE Conference
• /
• 2001.07a
• /
• pp.223-226
• /
• 2001

In this paper, dc link ripple currents for three-phase ac/dc/ac PWM converters are analyzed in a frequency domain. The expression of the harmonic currents is developed by using switching functions and exponential Fourier series expansion. The dc link ripple currents with regard to power factor and modulation index are investigated. In addition, the effect of the displacement angle between the switching periods of line-side converters and load-side inverters on the do link ripple current is studied. The result of the do link current analysis is helpful in specifying the dc link capacitor size and its life time estimation.

• Journal of Power Electronics
• /
• v.17 no.4
• /
• pp.963-971
• /
• 2017

Torque ripple is one of the major sources inducing vibration and noise in brushless DC motors. This is especially true in applications such as the spindle motors used in hard disk drives. However, the relationship between torque ripple and acoustic noise/vibration is quite complicated. This paper presents a way to investigate this relationship with acoustic noise measurement and analysis. Results obtained with three different drive modes are used in the analysis. The results show that the acoustic noise analysis is very helpful in designing a high-performance drive strategy for BLDC motors.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.19 no.1
• /
• pp.91-97
• /
• 2014

Recently, the LED(Light Emitting Diode) is expected to replace conventional lamps including incandescent, halogen and fluorescent lamps for some general illumination application, due to some obvious features such as high luminous efficiency, safety, long life, environment-friendly characteristics and so on. To drive the LED, a single stage PFC(Power Factor Correction) flyback converter has been adopted to satisfy the isolation, PFC and low cost. The conventional flyback LED driver has the serious disadvantage of high 120Hz output current ripple caused by the PFC operation. To overcome this drawback, a new PFC flyback with low 120Hz output current ripple is proposed in this paper. It is composed of 2 power stages, the DCM(Discontinuous Conduction Mode) flyback converter for PFC and BCM(Boundary Conduction Mode) boost converter for tightly regulated LED current. Since the link capacitor is located in the secondary side, its voltage stress is small. Moreover, since the driver is composed of 2 power stages, small output filter and link capacitor can be used. Especially, since the flyback is operated at DCM, the PFC can be automatically obtained and thus, an additional PFC IC is not necessary. Therefore, only one control IC for BCM boost converter is required. To confirm the validity of the proposed converter, theoretical analysis and experimental results from a prototype of 24W LED driver are presented.