Modular multilevel converter (MMC) is a proven technology for HVDC applications due to its salient features such as modularity and excellent power quality. To ensure best possible grid support, ...recent grid codes require incorporating fault ride-through (FRT) strategies so that HVDC converter stations remain connected and maintain reliable operation under various symmetrical and asymmetrical AC faults. In this paper, a communication-free enhanced fault ride-through technique without the need of DC chopper has been proposed. The proposed FRT strategy ensures quick post fault recovery operation and can effectively manage DC link and capacitor voltages within safe limits. Along with proposed FRT strategy, in order to avoid high circulating current (CC) inside an MMC, this paper has proposed an optimal circulating current control approach based on proportional resonant and PI controllers in an abc reference frame. The suggested technique lowers the ripple in capacitor voltages while reducing the magnitude of the CC. Under both balanced and unbalanced ac grid conditions, the ripple in the dc link voltage is also reduced without the use of dual synchronous reference frame or any additional controllers. Simulation results confirm the effectiveness of the proposed FRT and CC suppression techniques for a 580-kV, 850-MW MMC-based HVDC system.
This work introduces a novel non-isolated boost DC–DC converter with high-voltage gain and high efficiency. The magnetic coupling and voltage lift circuit technique has been utilised to enhance the ...voltage conversion ratio. In order to decrease the peak voltage across the active switch, the voltage lift circuit acts as a clamp circuit. The zero current switching in the OFF-state and the zero voltage switching in the ON-state of diodes are other advantages of the suggested converter which leads to approach high efficiency by decreasing the conduction losses. In addition, only one power metal–oxide–semiconductor field-effect transistor with lower ON-state resistance is employed, which can provide the simple control circuit of the proposed topology. For demonstrating the performance of the proposed structure, the principle of operation modes and comparison results with other previous works is carried out. Finally, experimental results with a 200 W power level at 25 kHz operating frequency are prepared, which validate the usefulness of the proposed converter.
The design of control circuit for a solar fed cascaded multilevel inverter to reduce the number of semiconductor switches is presented in this study. The design includes ‘binary’, ‘trinary’ and ...‘modified multilevel connection’ (MMC)-based topologies suitable for varying input sources from solar photovoltaic's (PV). In binary mode, 2Ns +1 − 1 output voltage levels are obtained where Ns is the number of individual inverters. This is achieved by digital logic functions which includes counters, flip-flops and logic gates. In trinary mode, 3Ns levels are achieved by corresponding look-up table. MMC intends design in both control and power circuits to provide corresponding output voltage levels by appropriate switching sequences. Hence to obtain a 15-level inverter, the conventional method requires 28 switches and in binary mode 12 switches are needed. In trinary mode with the same 12 switches, 27 levels can be obtained whereas in MMC only 7 switches are employed to achieve 15 levels. The advantage of these three designs is in the reduction of total harmonic distortion by increasing the levels. Simulations are carried out in MATLAB/Simulink and comparisons were made. All the three topologies are experimentally investigated for a 3 kWp solar PV plant and power quality indices were measured.
A self-excited induction generator (SEIG) can be a candidate for isolated applications because it does not require any external exciting power but can independently generate electricity. It is also a ...good candidate for auxiliary brakes in heavy vehicles for several reasons. First, the power efficiency in a brake system is not important as compared with motors or generators. Second, an SEIG can be controlled by a simple electrical circuit. Third, it can be used for regenerative braking. Finally, it is very robust. In this paper, an auxiliary brake for heavy vehicles is proposed by adapting an SEIG and its analog control circuit. The brake structure is the same as that in conventional eddy current brakes but operates as an SEIG. The suggested control circuit does not adopt an electric controller unit but only consists of simple electric devices. A miniature model was designed and manufactured, and the experimental results using the prototype verify that the proposed brake system, including the controller, is very useful.
Magnetorheological (MR) dampers are controlled energy-dissipating devices utilizing smart fluids. They operate in a fast and valveless manner by taking advantage of the rheological properties of MR ...fluids. The magnitude of the response of MR fluids, when subjected to magnetic fields, is of sufficient magnitude to employ them in various applications, namely, vibration damping, energy absorption, exoskeletons, etc. At the same time, predicting their response to arbitrary mechanical and electrical inputs is still a research challenge. Due to the non-linearities involved in material properties or the design of the solenoid used for activating the fluid modeling the relationships between the control circuit and the material’s response is complex. Modeling studies can be classified into two categories. The parametric approach requires the knowledge of the internal material’s properties and takes advantage of physics formulas to infer the I/O relationships present in the damper. For comparison, the non-parametric approach harnesses various data mapping techniques to describe the device’s behavior. While the latter is more suited for design studies, the former seems ideal for control algorithm prototyping and the like. In this study, based on the so-called Support Vector Method (SVM), the authors develop a non-parametric model of the control circuit of an exemplary rotary MR damper. To the best of the author’s knowledge, it is the first attempt at an SVM application for MR dampers’ control circuit modeling. Using the acquired experimental data, the I/O relationships are inferred using the SVM algorithm, and its performance is verified across a wide range of excitation frequencies. The obtained results are satisfactory, and the current response of the MR damper is well-predicted. The model performance shows the potential for incorporating it into model-based prototyping and designing of MR control systems.
The oscillation of the sense mode of the micro-machined Coriolis vibratory gyroscope (MCVG) with high quality factor (
) is analyzed in this study and the corresponding force feedback control scheme ...is presented to suppress this oscillation. The controller consists of integrator and some filters, instead of the common but complicated demodulation and remodulation modules. Compared with using no oscillation suppression scheme, the proposed simplified oscillation suppression control scheme can achieve an improvement of the sense mode of the MCVG. The inband spectrum ripple of the angular rate output are improved from 51.4 dB to 4.23 × 10
dB. Correspondingly, these two performance parameters are improved by 370.4 and 186.2 times, which are higher than two orders of magnitude, respectively. Bias stability is improved from 9.72 deg/h to 2.5 deg/h. Test results prove that the proposed control scheme is effective in suppressing the oscillation.
In this paper, an extended continuous class-F power amplifier (PA) is investigated, designed, and fabricated. The new auxiliary parameter
β
+
α
cos
2
θ
, is proposed to increase the efficiency in ...comparison with the old auxiliary parameter
1
+
δ
cos
θ
. A novel methodology based on the smith chart design space and the proposed auxiliary parameter is introduced and analyzed. The design methodology, by controlling harmonic interferences, expands the amplifier bandwidth to below 1 GHz (up to 200 MHz). The laterally diffused metal–oxide–semiconductor (LDMOS) is selected, and an optimal bias point for its best performance is considered. Also, microstrip feedback based on the low-impedance coupled line is designed to accomplish transistor unconditional stability. Then, a ladder network based on the radial lines is designed as a harmonic control circuit, which controls harmonics up to 5th into the proposed design space. To verify this design approach, an extended continuous class-F power amplifier is designed and fabricated to operate at 0.2–1.7 GHz frequency range. Measurement results of the implemented PA shown that the output power of 38–40.2 dBm and the power gain of 13–15.2 dB were obtained. In addition, the final PA achieved a remarkable 53–79% drain efficiency over the whole operation bandwidth.
The thermal flow sensors are widely accepted in semiconductor industry because they can measure the flow rate of various types of gases based on each reference flow data. However, it is difficult to ...obtain such data for some reactive gases because due to corrosion of the gas measurement system. To overcome such difficulties, this paper proposes a multi-domain physical model of the thermal based flow sensor taking account of both electrical and thermal characteristics. The proposed model is analyzable based on the physical properties of the target gas, and its validity is demonstrated through comparison with experimental data.
In this paper, a body and gate control circuit for PMOS switch that makes it low leakage for V DD =0V condition is presented. It is designed and implemented in CMOS technology and guarantees the pin ...leakage stays below 50uA when V PIN =0.5V in absence of supply voltage for all PVT condition with significant margin. It has been developed and implemented to guarantee one of the USB3.2 compliance test for signal conditioner to avoid misleading host from sending data to a dead device. The implemented body and gate control circuit uses a subthreshold based maximum voltage selector circuit to reduce the leakage of the PMOS switch for all supply/pin voltage combinations while not impacting its normal functionality of the switch. Control of gate and body of PMOS is the significance of this work which shows an Rin of larger than 10k-ohm to host to show that device is dead in V DD =0V condition.
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