• Journal of Power Electronics
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• v.9 no.2
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• pp.308-319
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• 2009

An increasing number of power electronic applications require high power density. Therefore, the switching frequency and switching speed have to be raised considerably. However, the very fast switching transients induce a strong voltage and current ringing. In this work, a novel damping concept is introduced where the parasitic wiring inductances are advantageously magnetically coupled with a damping layer for attenuating these unwanted oscillations. The proposed damping layer can be implemented using standard materials and printed circuit board manufacturing processes. The system behavior is analyzed in detail and design guidelines for a damping layer with optimized RC termination network are given. The effectiveness of the introduced layer is determined by layout parasitics which are calculated by application of the Partial Element Equivalent Circuit (PEEC) simulation method. Finally, simulations and measurements on a laboratory prototype demonstrate the good performance of the proposed damping approach.

• Journal of Power Electronics
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• v.15 no.5
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• pp.1286-1294
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• 2015

Capacitor current feedback active damping is extensively used in grid-connected converters with an LCL filter. However, systems tends to become unstable when the digital control delay is taken into account, especially in low switching frequencies. This paper discusses this issue by deriving a discrete model with a digital control delay and by presenting the stable region of an active damping loop from high to low switching frequencies. In order to overcome the disadvantage of capacitor current feedback active damping, this paper proposes a modified approach using grid current and converter current for feedback. This can expand the stable region and provide sufficient active damping whether in high or low switching frequencies. By applying the modified approach, the active damping loop can be simplified from fourth-order into second-order, and the design of the grid current loop can be simplified. The modified approach can work well when the grid impedance varies. Both the active damping performance and the dynamic performance of the current loop are verified by simulations and experimental results.

• Journal of information and communication convergence engineering
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• v.14 no.4
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• pp.268-271
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• 2016

An efficient inductive switching noise suppression technique for mixed-signal integrated circuits (ICs) using standard CMOS digital technology is proposed. The proposed design technique uses a parallel RC circuit, which provides a damping path for the switching noise. The proposed design technique is used for designing a mixed-signal circuit composed of a ring oscillator, a digital output buffer, and an analog noise sensor node for $0.13-{\mu}m$ CMOS digital IC technology. Simulation results show a 47% reduction in the on-chip inductive switching noise coupling from the noisy digital to the analog blocks in the same substrate without an additional propagation delay. The increased power consumption due to the damping resistor is only 67% of that of the conventional source damping technique. This design can be widely used for any kind of analog and high frequency digital mixed-signal circuits in CMOS technology

• Proceedings of the KIEE Conference
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• 2004.05a
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• pp.33-37
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• 2004

To meet an increasing demand for high performance in gun dynamic plant, both a precise and a fast response positioning are strongly required for the gun servomechanism control. A mode switching control(MSC) system, which includes a fine stabilizing controller, fast positioning one and a switching function, is widely used to meet this requirement. Stabilization is performed through PID controller, while proximate time optimal servo(PTOS) is used for target designation. Because gun dynamic have large damping comparing to acceleration, PTOS algorithm with damping is newly derived. This paper adopts the initial value compensation method that improve the transient response after switching. Some simulation results are given to show the effectiveness of our scheme.

• Journal of Astronomy and Space Sciences
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• v.11 no.2
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• pp.281-295
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• 1994

In this paper, the Variable Structure System(VSS) theory with new continuous switching dynamic equation is used to design an automatic controller for the active nutation damping in momentum bias stabilized spacecraft. In the application of VSS theory to a linearized multivariable system with the nutation damping systems, there exist some disadvantages such as how to determine the switching gains and how to reduce the chattering phenomina and reaching phase in input and state trajectories. To solve these drawbacks, this paper presents the continuous switching dynamic equation instead of the discontinuous switching logics to obtain the sliding mode. The new design approach is much simpler than the VSS theory. And there do not exist chattering phenomina in this method because the obtained control inputs are continuous. Simultaneously the reaching phase is reduced by a suitable choice of design factor.

• Journal of Power Electronics
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• v.19 no.4
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• pp.1034-1044
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• 2019

In medium-voltage and high-voltage high-power converters, the switching devices need to operate at a low switching frequency to reduce power loss and increase the power capacity. This increases the delay of the signal sampling and PWM. It also makes the cross-couplings of the d-q current components more severe. In addition, the LCL filter has three cross-coupling loops and is prone to resonance. In order to solve these problems, this paper establishes a complex vector model of an LCL type grid-connected converter. Based on this model, two multiple decoupling current control strategies with passive damping / notch damping are proposed for the LCL type grid-connected converter. The proposed strategies can effectively eliminate the cross-couplings of the converter, achieve independent control of the d-q current components, expand the stable region and suppress the resonance of the LCL filter. Simulation and experimental results verify the correctness of the theoretical analysis and the feasibility of the proposed strategies.

• Proceedings of the KIEE Conference
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• 1987.11a
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• pp.45-48
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• 1987

In applications of step-motor, the requirements of small-size and strong-power gave birth to feed-back drive to the maximum efficiency and complete damping. In this paper, a new scheme that determines switching times from sensed values of position and speed is presented for simple bang-bang type drive circuit. The optimal values of each phase switching times are obtained using conjugate gradient method.

• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.1
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• pp.64-70
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• 2014

In this paper, the new LLCL filter is proposed for grid connected three-phase PWM inverter for passive damping. LLCL filter inserts a small inductor in the branch of the capacitor of the traditional LCL filter to compose a series resonant circuit to reduce the switching-frequency component on grid current. Using LLCL filter, the switching-frequency current ripple components can be attenuated much better than the LCL filter, leading to a decrease in the total inductance. However, the resonance phenomena caused by zero impedance from the addition of LC branch in LLCL filter can be a big problem. Resonance phenomena of LLCL filter can be a source of grid system instability, so proper damping methods are required. However, it is difficult to apply a passive damping method in the conventional LLCL filter, because the damping resistor increase impedance of the LC branch. Therefore, switching frequency component of grid current can not much attenuated by low Q of LC series resonance effect. In this paper, a new LLCL filter is proposed to overcome the conventional LLCL filter with passive damping. The validity of the proposed method is proven by simulation and experimental result.

• Journal of Power Electronics
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• v.12 no.2
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• pp.326-332
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• 2012

This paper proposes a simple active damping algorithm for small-scale wind power systems with an LCL filter. Compared to an L filter or an LC filter, an LCL filter can decrease the harmonics induced by low switching frequencies and produce a satisfactory grid-side current using a comparatively low inductance. Additional active damping of the filter resonance is necessary when an LCL filter is used. This paper introduces an active damping method using a Discrete Fourier Transform (DFT) filter to improve performance without additional sensors or complexity. Experimental results are shown to verify the validity of the proposed algorithm as an active damping method.

• International Journal of Aeronautical and Space Sciences
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• v.17 no.4
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• pp.501-517
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• 2016

Synchronized switch damping (SSD) is a structural vibration control technique in which a piezoelectric patch attached to or embedded into the structure is connected to or disconnected from the shunt circuit in order to dissipate the vibration energy of the host structure. The switching process is performed by a digital signal processor (DSP) which detects the displacement extrema and generates a command to operate the switch in synchronous with the structure motion. Recently, autonomous SSD techniques have emerged in which the work of DSP is taken up by a low pass filter, thus making the whole system autonomous or self-powered. The control performance of the previous autonomous SSD techniques heavily relied on the electrical quality factor of the shunt circuit which limited their damping performance. Thus in order to reduce the influence of the electrical quality factor on the damping performance, a new autonomous SSD technique is proposed in this paper in which a negative capacitor is used along with the inductor in the shunt circuit. Only a negative capacitor could also be used instead of inductor but it caused saturation of negative capacitor in the absence of an inductor due to high current generated during the switching process. The presence of inductor in the shunt circuit of negative capacitor limits the amount of current supplied by the negative capacitance, thus improving the damping performance. In order to judge the control performance of proposed autonomous SSDNCI, a comparison is made between the autonomous SSDI, autonomous SSDNC and autonomous SSDNCI techniques for the control of an aluminum cantilever beam subjected to both single mode and multimode excitation. A value of negative capacitance slightly greater than the piezoelectric patch capacitance gave the optimum damping results. Experiment results confirmed the effectiveness of the proposed autonomous SSDNCI technique as compared to the previous techniques. Some limitations and drawbacks of the proposed technique are also discussed.