Output Phase Shift Research Articles

POWER PROCESSING AND CONTROL UNIT OF THE EECTRIC PROPULSION SYSTEM

Abstract. The report presents the results of the development of the PPU-500, which is part of the SPS-500 electric propulsion system based on the ST-40 Hall thruster. PPU-500 contains all power supplies necessary for the operation of the propulsion system: discharge; electromagnet; cathode heater and keeper; power supplies for valves and heaters of the storage and feeding working substance, as well as a standby power supply that ensures the standby mode of PPU operation.The converter of the discharge power supply is built using a bridge topology with a phase-shifted output power control circuit. The remaining power supplies are built according to the topology of a step-down synchronous converter with current or voltage stabilization. The discharge power supply is a controlled power supply. The power supplies for the cathode heater and electromagnet current sources are. The accuracy of power supplies output parameters in not worse than 1.5%. The valves of the feeding system are controlled in order to stabilize the pressure in the receiver by periodically turning on/turning off the high- and low-pressure valves. For control the valves, signals taken from pressure sensors installed in the receiver are used. The PPU control unit ensures an accuracy of maintaining pressure in the receiver no worse than 2.5%. The control unit of the PPU is built using a microcontroller with an ARM core. It implements the functions of monitoring the condition of the program, restoring the program firmware if an integrity violation is detected, and the ability to remotely flash a new version. To communicate the SPS-500 with the on-board control system, a galvanically isolated CAN interface is used. It can be also the RS485/RS42 interface.During operation of the propulsion system, operating parameters are measured using multi-channel ADCs and DACs. The obtained data, on the one hand, is used to assess the current state of the propulsion system and control Hall thruster operating modes. On the other hand, they are transmitted as telemetry signals reflecting the current state of the SPS-500, operating mode and emerging emergency conditions of the equipment. PPU is possible to alternately control two thrusters. Solid-state switches are used to switch the corresponding power sources.Testing of the PPU-500 as part of the SPS-500 propulsion system with the ST-40 Hall thruster and a flight prototype of the working substance feeding system confirmed the technical solutions adopted. The operating efficiency of PPU-500 for the nominal operating mode of the propulsion system is 94%.

Design and Analysis of Misalignment Insensitive Wireless Power Transfer System Based on Multitransmitter for Constant Power

This paper proposes a multiple transmitting array wireless power transfer (MTA-WPT) system with constant output power charging for consumer electronics, such as tablets and mobile phones. Compared to conventional WPT systems, this proposed system can achieve constant output power by controlling the current phase shift of the transmitting (Tx) coils when the receive (Rx) coil is located at different positions and directions. The detailed circuit topology of the proposed system is modeled and analyzed to obtain the correspondence between the current phase shift and load output power. Furthermore, the excitation current distribution strategies for a system of three and four Tx coils at optimized efficiency are theoretically analyzed. The simulation demonstrates that the proposed system can achieve constant output power with modulating the phase shift at various Rx sites. Finally, an experimental prototype with four Tx coils is designed and carried out to prove the effectiveness of the phase shift modulation method and current distribution strategy. Besides, the superiority of the proposed MTA-WPT system is verified by comparison with other methodologies. The experimental results show that the output power of Rx at different positions is kept at roughly 41W with the transmission efficiency over 80% by the Tx current phase shift modulation.

Output Phase and Amplitude Analysis of GaN-Based HEMT at Cryogenic Temperatures

We report both output phase and amplitude performance for gallium nitride (GaN)-based high-electron-mobility transistor (HEMT), operating in RF small- and large-signal modes from 270 K to cryogenic 70 K. Intrinsic elements of the device were extracted employing a small-signal equivalent circuit model. Temperature dependences of maximum available power gain, short-circuit current gain, and open-circuit voltage gain indicated performance improvement as lowering the ambient temperature. Meanwhile, the output phase of small RF signal measurement was found to be decreased linearly with decreasing the temperature. In RF large-signal operations, power and phase nonlinearity induced by AM-to-AM and AM-to-PM conversion were characterized via gain and phase compression, respectively. Measured <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$P_{\mathrm {1\,dB}}/P_{\mathrm {3\,dB}}/P_{\mathrm {5\,dB}}$ </tex-math></inline-formula> was decreased monotonously for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$T &gt; 150$ </tex-math></inline-formula> K, whereas it showed little temperature sensitivity under 150 K. Output phase shift was expanded as increasing the input power level and was all greatly suppressed as dropping the temperature.

Conditional π-Phase Shift of Single-Photon-Level Pulses at Room Temperature.

The development of useful photon-photon interactions can trigger numerous breakthroughs in quantum information science, however, this has remained a considerable challenge spanning several decades. Here, we demonstrate the first room-temperature implementation of large phase shifts (≈π) on a single-photon level probe pulse (1.5 μs) triggered by a simultaneously propagating few-photon-level signal field. This process is mediated by Rb^{87} vapor in a double-Λ atomic configuration. We use homodyne tomography to obtain the quadrature statistics of the phase-shifted quantum fields and perform maximum-likelihood estimation to reconstruct their quantum state in the Fock state basis. For the probe field, we have observed input-output fidelities higher than 90% for phase-shifted output states, and high overlap (over 90%) with a theoretically perfect coherent state. Our noise-free, four-wave-mixing-mediated photon-photon interface is a key milestone toward developing quantum logic and nondemolition photon detection using schemes such as coherent photon conversion.

Transient DC bias suppression of three‐port isolated DC–DC converter

Three-port isolated dc–dc converter, as an active exploration and trial of photovoltaic access to dc distribution system, has the advantages of superior control flexibility and high reliability. Due to the changes in the phase-shift (PS) angle, the conventional PS control method cause transient dc bias in inductor current and magnetisation current, further increasing the current stress of switches and threatening the safe operation of the converter. Based on superposition theorem analysis, this study discusses the formation mechanism of transient dc bias, constructs a mathematical model of drive signals, and proposes two typical combination strategies of drive signals. The proposed method can simultaneously suppress the dc bias of port inductor and transformer magnetisation inductor in one switching cycle by changing the duty ratio of square wave voltage or adding the zero-voltage phase related to the PS angle. By simulating the PS angle change and output power fluctuation, the dynamic characteristics under conventional PS control and the proposed strategy are compared and discussed. The simulation and experimental waveforms show that the proposed method is not only suitable for the multi-step step change of PS angle, but also sufficient for the continuous evolution of the PS angle.

Highly Efficient Single-Switch-Regulated Resonant Wireless Power Receiver With Hybrid Modulation

In this paper, a highly-efficient single-switch-regulated resonant wireless power receiver with hybrid modulation is proposed. To achieve both high efficiency and good output voltage regulation, phase shift and pulse width hybrid modulation are simultaneously applied. The soft switching operation in this topology is achieved by the cycle-by-cycle phase shift adjustment between the input current and the gate drive signal and also attributed to the reactive components such as the series-compensated secondary coil and the parasitic capacitor of the active switch . The soft switching operation also leads to high efficiency and low EMI. By adjusting the duty ratio of the switch, tight regulation of the output voltage can be attained. The steady-state and dynamic models of the resonant receiver with hybrid modulation are analytically derived in order to properly design the feedback controller. An experimental setup of a two-coil wireless power transfer system, including the hardware prototype of the proposed receiver, is constructed for experimental verification. The experimental results show the effectiveness of the soft-switching operation in the receiver with high efficiency while maintaining good regulation of the output voltage, regardless of line and load variations.

Practical Adaptation of a Low-Cost Voltage Transducer with an Open Feedback Loop for Precise Measurement of Distorted Voltages.

This paper presents the project proposal of a low-cost transducer with a Hall-effect sensor placed in a ferromagnetic core’s air gap, which enables the measurement of the distorted voltage instantaneous values without the feedback loop used for measurements in electrical machines. The presented transducer allows for electrical separation between the measured voltage and the voltage at the output. Moreover, the influences of frequency, additional resistance, and the reactance of the winding circuit on the voltage phase shift caused by winding inductance with ferrite core and amplitude are discussed. The result of simulating leakage inductance of measuring winding with ferrite core with an air gap is calculated using finite element analysis. Experimental investigations of the voltage phase shift angle and output voltage amplitude drop for the voltage transducers with an open feedback loop are carried out, taking into account the linear core magnetization characteristic.

Analysis and Test of Time Difference Measurement IP Based on FIB

With the development of semiconductor technology, how to locate and verify the problems found in chip testing becomes the key of the chip design. In the test of time difference measurement IP chip, test results find that the phase shift output does not correspond with the design requirements. After analyzing the circuit, the leakage current of refresh circuit is found. The FIB (Focused Ion Beam) technology is adopted to modify the physical circuit. The circuit is tested after FIB. The result shows that the judgement and analysis of the crux of the problem is correct. Through FIB, not only the problem is found, but also the function and performance of the chip are tested rapidly. The purpose of rapid verification is achieved, and the modification time is saved. Using FIB can help to reduce the cost of chip design sometimes.

Analysis and Study of the Duty Ratio Effects on the Class-EM Power Amplifier Including MOSFET Nonlinear Gate-to-Drain and Drain-to-Source Capacitances

In this paper, the effects of the duty ratio variation on the class-EM power amplifier are studied and analyzed, including nonlinear gate-to-drain and drain-to-source parasitic capacitances. The duty ratio is one of the important parameters in class-EM power amplifiers, which has high effects on the switch voltage and current waveforms, output power, efficiency, power loss, and output phase shift. To achieve a better agreement between theoretical and experimental results, the nonlinear gate-to-drain and drain-to-source parasitic capacitances are included in theoretical analysis. To demonstrate the validity of the presented analysis, five class-EM power amplifiers are designed, simulated, fabricated, and tested using IRF510 mosfet with the duty ratio equal to 0.5, 0.6, and 0.7 and IRFZ24N mosfet with the duty ratio equal to 0.5 with and without considering mosfet nonlinear capacitances. It is shown that the amplifier with IRFZ24N mosfet has higher efficiency than that with IRF510 mosfet . This is because of the lower drain-to-source on-state resistance of the IRFZ24N mosfet . The obtained efficiency with IRFZ24N mosfet considering nonlinear capacitances at the operating frequency of 3.5 MHz was 95.7%. The obtained output power for IRF510 and IRFZ24N mosfet s at the duty ratio equal to 0.5 was 14.41 and 17.82 W, respectively. Simulation and theoretical results are performed using PSpice and MATLAB, respectively. The theoretical results and PSpice simulations agreed with experimental results.

Capacitive Phase Shift Detection for Measuring Water Holdup in Horizontal Oil⁻Water Two-Phase Flow.

In this paper, a phase shift detection system of flow impedance is designed based on a concave capacitance sensor (CCS). The flow impedance of oil–water stratified flow is investigated by establishing an equivalent circuit model and a finite element model. The influence of exciting frequency and sensor geometric parameters on the phase shift output of the CCS is studied to access an optimal phase shift measurement system. An experiment of horizontal oil–water two-phase flows was conducted during which four flow patterns are observed, i.e., stratified flow (ST), stratified wavy flow (SW), dual continuous flow (DC), and dispersed oil-in-water and water flow (DO/W&W). The phase shift responses of the CCS to the water holdup variation are collected. The results indicate that the phase shift response of the CCS presents satisfied sensitivity for ST and SW flow patterns, which is consistent with the predictions of the equivalent circuit model and the finite element model. Although the flow structures of DC and DO/W&W flows are extremely nonuniform, the phase shift response of the CCS still shows better linearity and sensitivity to the water holdup variation. In general, the capacitive phase shift detection technology exhibits advantages for water holdup measurement in horizontal oil–water two-phase flow with nonuniform phase distributions and conductive water.

Design of real-time data acquisition system for POlarimeter- INTerferometer diagnostic

The real-time data acquisition system is designed for providing POlarimeter-INTerferometer (POINT) diagnostic data to P-EFIT in real-time. The digital phase detector of POINT can provide real-time Faraday rotation angle data and density phase shift output which can be used in plasma control. P-EFIT, a code based on parallel computation in Graphic Processing Unit and the EFIT framework, is developed for EAST plasma control. Now P-EFIT includes a new algorithm for real-time plasma current profile reconstruction with POINT diagnostic data. The new real-time data acquisition system has been designed based on a reflective memory (RFM) network and the LabVIEW real-time operating system. It can be divided into three modules: data acquisition, data pre-processing and real-time data transmission. The data acquisition module receives a message containing the plasma shot information from the data acquisition console (according to the rules of the EAST data acquisition system) and then acquires the POINT diagnostic data after signal conditioning. The data pre-processing module primarily converts the raw data into a valid physical signal thus reducing the workload of P-EFIT. The EAST Plasma Control System has a well-established RFM network from which P-EFIT is able to get all the data it needs. This means that the data transmission module must first choose the RFM network to transfer processed data in real-time, and then P-EFIT can perform a new equilibrium reconstruction iteration with the most recent data from the data transmission module and the last equilibrium result. The data transmission frequency is 20 kHz, which satisfies the requirements of the P-EFIT real-time plasma current profile reconstruction.

Frequency independent 180° phase shifter based on UWB coupled sections

AbstractIn this article, a novel Ultra‐Wideband (UWB) 180° planar phase shifter is designed and fabricated. The proposed design is mainly based on coupled sections which are realized by inserting slots into the common ground plane of the multilayer circuit. Two identical structures, leading to discard parameters that disturb the output phase shift, are introduced in the design. To get 180° phase difference shift, via holes are used to perform a short circuit in one of the two coupled sections. Theoretical analysis based on four port network is presented to explain the characteristics of the proposed design. Further, experimental measurements are performed and compared with simulation results to validate the proposed approach. Hence, a good simulated to measured agreement is obtained.

A Power Regulation and Harmonic Current Elimination Approach for Parallel Multi-Inverter Supplying IPT Systems

The single resonant inverter is widely employed in typical inductive power transfer (IPT) systems to generate a high-frequency current in the primary side. However, the power capacity of a single resonant inverter is limited by the constraints of power electronic devices and the relevant cost. Consequently, IPT systems fail to meet high-power application requirements, such as those in rail applications. Total harmonic distortion (THD) may also violate the standard electromagnetic interference requirements with phase shift control under light load conditions. A power regulation approach with selective harmonic elimination is proposed on the basis of a parallel multi-inverter to upgrade the power levels of IPT systems and suppress THD under light load conditions by changing the output voltage pulse width and phase shift angle among parallel multi-inverters. The validity of the proposed control approach is verified by using a 1,412.3 W prototype system, which achieves a maximum transfer efficiency of 90.602%. Output power levels can be dramatically improved with the same semiconductor capacity, and distortion can be effectively suppressed under various load conditions.

Design of a Broadband HEMT Mixer for UWB Applications

Background/Objectives: Microwave mixer is a crucial element in virtually all transmits and receives systems. Methods/Statistical analysis: In this paper, a novel distributed HEMT mixer with three layers is designed for Ultrawide-Band (UWB) receivers. We employ external capacitors in the proposed circuit to adjust the output phase shift between stages to equal the input phase shift. Findings: The simulation results show that the proposed structure, achieves vary broadband performances in Converstion Gain, Power Consumption and LO-RF Isolation, comparable to the recent reported cascode or dual-gate distributed mixers. With a local oscillator power of 12 dBm and RF power of -20 dBm, our mixer has a Conversion Gain of 0 ~ 4 dB (without IF signal amplification), LO-to-RF isolation better than 32 dB and 130 mW DC power consumption over bandwith 5-25 GHz. Applications/Improvements: In our scheme, an intermediate layer is considered to increase LO-RF Isolation and improve the Converstion Gain criterion. Moreover, Microstrip lines are used to form the artificial gate and drain transmission lines as well as phase equalization of the signal on drain transmission line.

Internal magnetic field measurements by laser-based POlarimeter-INTerferometer (POINT) system on EAST

A multi-channel far-infrared laser-based POlarimeter-INTerferometer (POINT) system utilizing the three-wave technique has been implemented for fully diagnosing the internal magnetic field in the EAST tokamak. Double-pass, horizontal, radially-viewing chords access the plasma via an equatorial port. The laser source consists of three CW formic acid (HCOOH) FIR lasers at nominal wavelength 432.5 μm which are optically pumped by independent infrared CO2 lasers. Output power is more than 30 mW of per cavity. Novel molybdenum retro-reflectors, can with withstand baking temperature up to 350°C and discharge duration more than 1000 s, are mounted in the inside wall for the double-pass optical arrangement. A Digital Phase Detector with 250 kHz bandwidth, which provide real-time Faraday rotation angle and density phase shift output for plasma control, have been developed for the POINT system. Reliability of both polarimetric and interferometric measurement are obtained in 22 s long pulse H mode discharge and 8 s NBI H mode discharge, indicating the POINT system works for any heating scheme on EAST so far. The electron line-integrated density resolution of POINT is less than 1 × 1016 m−2 (< 1°), and the Faraday rotation angle rms phase noise is < 0.1°. With the high temporal (∼ 1 μsec) and phase resolution (< 0.1°), perturbations associated with the sawtooth cycle and MHD activity have been observed. The current profile, density profile and safety factor (q) profile are reconstructed by using EFIT code from the external magnetic and the validation POINT data. Realtime EFIT with Faraday angle and density phase shift constraints will be implemented in the plasma control system in the future.

Faraday-effect polarimeter-interferometer system for current density measurement on EAST.

A multichannel far-infrared laser-based POlarimeter-INTerferometer (POINT) system utilizing the three-wave technique is under development for current density and electron density profile measurements in the EAST tokamak. Novel molybdenum retro-reflectors are mounted in the inside wall for the double-pass optical arrangement. A Digital Phase Detector with 250 kHz bandwidth, which will provide real-time Faraday rotation angle and density phase shift output, have been developed for use on the POINT system. Initial calibration indicates the electron line-integrated density resolution is less than 5 × 10(16) m(-2) (∼2°), and the Faraday rotation angle rms phase noise is <0.1°.

Low Phase Noise Wide Tuning Range N-Push Cyclic-Coupled Ring Oscillators

Cyclic-coupled ring oscillators (CCRO) provide several unique features over regular ring oscillators such as availability of multiple sets of phase-shifted outputs and reduced phase noise. Furthermore, when combined with N-push frequency multiplication low phase noise, wide tuning ranges and millimeter-wave (mm-wave) frequencies can be realized. In this work, we propose two N-push CCROs fabricated in a 90 nm digital CMOS process. First, a wideband N-Push/M-Push CCRO is presented which achieves an output frequency range of 3.16-12.8 GHz using a unit cell ring oscillator operating at 1-2.56 GHz. The measured phase noise at 1 MHz offset is -103.4 dBc/Hz and -101.6 dBc/Hz at 3.16 GHz and 12.8 GHz, respectively. Second, an mm-wave N-Push CCRO is presented. It generates an output frequency of 13-25 GHz with a low phase noise performance of -95 dBc/Hz at 1 MHz offset over the output frequency range. The proposed oscillators achieve superior phase noise performance as well as competitive figure-of-merit compared with the state-of-the-art ring oscillators. In addition, the operation of the CCRO and its phase noise is analyzed. We confirm, analytically and experimentally, that the phase noise of an M-stage CCRO improves by 10 M over that of a single ring oscillator. We also show that the phase noise improvement bandwidth is a function of the coupling strength.

Study on the Driving Circuit for Ultrasonic Motor Using LLCC Resonant Technique

High driven voltage is required for ultrasonic motor, so the driving circuit needs transformer to boost voltage. Since the USM is a nonlinear capacitive load, a matching circuit is needed to keep the output voltage and the phase shift constant. For the switching circuit with push-pull topology, the switching loss is less under inductive load rather than capacitive load, which will increase its efficiency and reliability. A novel LLCC resonant network was proposed and its parameters were given. Theoretical analysis and simulation were presented, which demonstrated that the output voltage and phase shift of the resonant network was independent of driving conditions, such as driving frequency and load, and the load characteristics can be changed from capacitive to inductive. This novel driver is applied to the TRUM-60 type ultrasonic motor, and the experimental results are presented to verify the effectiveness of the proposed circuit.

Extended Operation of Cascade Multicell Converters Under Fault Condition

Multilevel converters are an interesting alternative for high power drives, due to their good quality output signals. Despite their advantages, the large number of components required increases the fault probability. Among the multilevel topologies, the cascade multicell converter presents advantages when operating under internal fault conditions, due to its high modularity. Previous works proposed to compensate the unbalanced operation due to a fault by changing the canonical fundamental output phase shift to precalculated angles, depending on the fault condition. This solution assumes that, if the maximum output phase voltage on each leg is used, the maximum line-to-line voltage will be at a maximum as well. This paper shows how this assumption is not always valid and presents the optimum angles and modulation indexes that must be used in order to obtain the maximum balanced load voltages.

Dynamic modeling of tunable analog integrated filters for a stability study of on-chip automatic tuning loops

Continuous-time filters with automatic tuning loops are nonlinear feedback systems that are potentially unstable. To ensure stability, particularly if the design of the loop controllers is to be improved, the appropriate linear dynamic modeling of the tunable filter, including control inputs, should be attained. This work aims to present a general dynamic modeling of continuous-time analog filters with automatic tuning capability. The general analysis leads to an equivalent small-signal linearized incremental model, from which transfer functions between output variables and control voltages are obtained. Subsequent to the analysis, it is possible to design compensated loops with enhanced stability and dynamic performance. By way of example, the modeling of a particular band-pass CMOS continuous-time analog filter is presented in this paper. Two transfer functions are derived: the transfer function between the output phase shift and the central frequency control voltage, and that between the output amplitude and the quality factor control voltage. These functions are required to properly tune the central frequency and quality factor parameters. This modeling makes it possible to propose an adaptive controller with improved stability and a possible implementation for such a controller. Finally, experimental results are shown for a CMOS 0.8 μm technology.