Conduction Angle Research Articles

A High-Efficiency High Power Driver Circuit for Joint Illumination and Communication System With Phase Shift Pre-Emphasis Technology

This paper presents an improved white light-emitting-diode (LED) wireless transmitter for the Joint Illumination and Communication (JIC) System, which consists of two parts: the driver circuit and the pre-emphasis circuit. The main purpose of the driver circuit part is to solve the problem of dissipated power when sweeping the remaining carriers during the signal modulation of the high-efficiency, high-power and high-speed white LED driver. A push-pull structure driver with a current conduction angle less than 180 degrees is proposed, which is analogous to a Class C power amplification driver, thus avoiding the simultaneous existence of voltage and current on the driver circuit when the remaining carriers are swept out, and improves the efficiency of the LED driver. On this basis, the pre-emphasis circuit part adopts the phase shift technology to improve the data transmission rate, and the system efficiency has also been improved. Then, an improved class C push-pull structure white LED driver with phase shift pre-emphasis technology is formed. This novel driver and pre-emphasis technology achieve a system efficiency of 95.73% with a 10 W LED. The test results show that the system communication -3 dB bandwidth expanded from the original 8.3 MHz to 13.67 MHz, and the best-obtained transceiver baud rate is 25 Mbps at a distance of 1.3 m with BER of 1.63 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-4</sup> . The test result verifies that the LED driver proposed in this paper is currently the highest figure of merit (FoM) for high power JIC systems.

Oscillator Flicker Phase Noise: A Tutorial

A deep understanding of how to reduce flicker phase noise (PN) in oscillators is critical in supporting ultra-low PN frequency generation for the advanced communications and other emerging high-speed applications. Unfortunately, the current literature is either full of conflicting theories and ambiguities or too complex in mathematics, hiding the physical insights. In this brief, we comprehensively review the evolution of flicker noise upconversion theories and clarify their controversial and confusing parts. Two classes of such upconversion mechanisms in voltage-biased LC-tank oscillators (nMOS-only and complementary) are specifically compared and numerically verified using a commercial simulation model of 28-nm CMOS. We identify that non-resistive terminations of both 2nd and 3rd harmonic currents contribute to oscillation waveform asymmetries that lead to the flicker noise upconversion. Further, we discuss three 1/f <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> PN reduction mechanisms: waveform shaping, narrowing of conduction angle, and gate-drain phase shift.

Series‐connected 36‐pulse rectifier using a hybrid harmonic injection method

This study proposes a hybrid voltage harmonic injection circuit at the DC link of the traditional series-connected 12-pulse rectifier to improve the harmonic suppression performance of the rectifier, which contains an injection transformer and the auxiliary circuit. The optimum turn ratio of the injection transformer and the optimal conduction angle of the switch are designed from the viewpoint of minimising the total harmonic distortion (THD) of the input voltage in the isolated transformer. Under the optimal design, the proposed series-connected rectifier operates as a 36-pulse rectifier. Experimental results indicate that the THD of input voltage reduces to ∼3.19% and that of the input current is only ∼2%.

Conduction Angle Control of Switched Reluctance Motor

This paper presents a microcontroller based closed loop speed control of Switched Reluctance Motor (SRM) drive powered through Asymmetric Half Bridge Converter (AHBC). Conduction angle control method is adopted for speed control and it is done by adjusting the duty cycle of PWM signal using a potentiometer. The performance comparison of speed control of SRM drive through single switch per phase converter and AHBC is performed with the help of soft chopping in conduction angle control method.

Design of a Self-Driving Transistor-Based RF-DC Converter Based on Optimized Harmonic-Tuned Rectification Waveforms

In order to apply the traditional power amplifier’s (PA) waveform engineering in an RF-dc rectifier design, a piecewise ON-resistance transistor model is introduced into the derived equations. In this proposed analysis method, the connection between the drain voltage and current is built in order to make the theoretical waveforms easily applied to a practical rectifier design with optimized parameters of the best efficiency. Continuous class-F/inverse class-F and continuous class-B/J waveforms are evaluated with numerical examples in this work. Thus, the rectification performance with different classes and parameters can be compared. This study shows that a continuous class-F and a continuous class-B/J rectifier can barely offer higher than 52% and 70% efficiencies with precise on-duty ratio ( $D$ ) of 0.5, respectively, except by reducing the conduction angle. However, a continuous inverse class-F shows the best rectification efficiency (easily higher than 85%) among all the studied cases for $D=0.5$ . A self-driving inverse class-F design example with optimized parameters is given to verify the theoretical analysis and demonstrate the high-efficiency performance. The rectification efficiencies of 74.9% and 80.7% are measured for 11.2- and 6 W-input powers at 1.9 GHz, respectively.

An X-Band Class-J Power Amplifier With Active Load Modulation to Boost Drain Efficiency

In this paper, the performance of the class-J mode power amplifier (PA) is studied when an auxiliary network performs active load modulation on the main transistor. Load modulation is realized by injecting an additional class-C like current with conduction angle of $\alpha $ to the drain node of the main transistor. The injected current employs a phase shift of $\phi $ with respect to the half-sinusoidal current of the main transistor, and its maximum value is tuned with the size of the transistor used in the auxiliary network. Detailed theoretical formulations are presented for the optimal load impedances of the PA at the fundamental and second-harmonic frequencies. Furthermore, the output power and drain efficiency of the PA are derived, and it is shown that the drain efficiency of the proposed PA can be as high as 96.8% in theory. The optimal values of $\alpha $ and $\phi $ for improving the drain efficiency of the load-modulated class-J PA are obtained, and a design methodology is also proposed to choose the optimal size of the transistor employed in the auxiliary network. To verify the theoretical derivations, a proof-of-concept 0.83 W class-J PA was designed and fabricated in a 0.25 $\mu \text{m}$ GaAs pHEMT process. The designed PA occupies 3.19 mm2 die area, and it achieves 71% drain-efficiency and 50% power-added-efficiency at 10 GHz.

Switched Reluctance Generator for Low Voltage DC Microgrid Operation: Experimental Validation

This paper presents the control of a Switched Reluctance Generator (SRG) for low voltage DC grid with the objective of efficiency maximizing. Analysis of the energy conversion, including electrical machine losses (Joule, magnetic, mechanical) and power converter losses (switching and conduction), has shown that there is an optimal combination of control variables (turn-on and conduction angles, phase current reference), which maximizes the drive efficiency. The control variables are derived from a Finite Element Analysis and parametric optimization algorithm for all of the operating points in the torque-speed plane and stored in lookup tables. The performances are evaluated with intensive numerical simulations and experimental tests with a 8/6 SRG feeding a DC resistive load for different rotational speeds. The results show good performances of the output DC voltage control with low ripples, even in the presence of speed and load variations. Thanks to the optimization, simulation results show that beyond 1500 rpm, drive efficiency is higher than 60 % and almost reaches 70 % at nominal speed. The experimental results show that, for light loads and beyond rated speed, the drive efficiency lies in the range between 60 % and 80 % .

Generalized Hybrid Continuous Mode for Designing Broadband Power Amplifiers

It has been widely validated that continuous working modes are powerful theories for designing broadband power amplifier (BPA). Theoretically, the conduction angle of all continuous-mode power amplifiers (PAs) is 180∘ (class-B-biased). However, in practice, these PAs are always biased in class-AB condition. Thus, continuous-mode PAs biased in class-AB condition should be researched. This paper generalizes the theory of hybrid continuous mode (HCM) for implementing broadband power amplifiers. The intrinsic drain current waveform of HCM biased above the pinch-off point (conduction angle is larger than 180∘) is first derived. Then, the impedance space of the generalized HCM (class-AB-biased) is explored and analyzed. The conclusion is that the generalized HCM possesses a shifted fundamental impedance space along with the enlargement of conduction angle. For validating the proposed theory, a broadband PA working over 1.6–3.0[Formula: see text]GHz is implemented. Experimental results indicate that the designed BPA achieves a saturation power of 40.3–42.7[Formula: see text]dBm and a drain efficiency of 64.3–74.4%.

Керування навантаженням асинхронного генератора з короткозамкненим ротором

The use of asynchronous generators as load devices for testing and running-in of power drives of new and refurbished equipment is the most efficient. Frequency converters with a direct current link are most often assumed to control the load. There are other methods of controlled loading of an asynchronous generator using a capacitor bank as a source of reactive power. Thyristor voltage regulators could become an alternative to the frequency converter with a link of a direct current. The purpose of the study is to study the possibility of increasing the reliability and efficiency of drive load systems and (or) generating systems when working on the network using asynchronous generators through the use of a three-phase choke in parallel with a thyristor voltage control module. A new way of the load control of an induction generator is being explored. The results of testing the physical model of the load stand of the asynchronous generator during its operation together with the thyristor voltage regulator and three-phase coil are given. The results of the study of the forms and magnitude of the stator current of an asynchronous generator at different modes and levels of its load are presented in the paper. A comparative analysis of the magnitude and phase of the sine wave offset with respect to the phase voltage of the network. The results show the increase of the active component of the stator current as the conduction angle of the thyristor modules of the voltage converter increases. The studies confirm the presence of recovery of part of the energy consumed from the network by the drive motor, when the opening angle of the thyristors exceeds about 1 rad. The oscillogram can be concluded that there is a significant distortion of the sinusoidal shape of the current, which can have a significant impact on the processes in the electric machine. Key words: induction generator, three-phase coil, voltage regulator, load control

An ON-Resistance Model for Silicon Carbide Merged p-i-n Schottky (MPS) Diodes

A novel resistance model of silicon-carbide-merged p-i-n Schottky diodes is presented in this article. With this model, the device characteristics and power dissipation can be predicted. The ON-resistance in the three operating modes, namely, unipolar, low-injection, and high-injection modes, is calculated. In the unipolar and low-injection modes, the effect of temperature on carrier mobility and conduction angle are added to the factors that need to be considered, whereas the influence of current density is considered in the high-injection mode. The carrier distribution in the high-injection mode is analyzed and applied to determine the resistance. And this resistance model is applied to the research of a forward characteristic model. The model is verified experimentally via the comparison of the calculated and measured characteristics. The experimental results prove that the model can not only predict the resistance in each working mode, but also accurately predict the forward current and voltage characteristics.

A Torque Control Method Based on I-MR Controller for IPMSM Drive With Small DC-Link Capacitor

In traditional motor drive system, large volume electrolytic capacitors are utilized to buffer energy and stabilize the dc-link voltage. However, these capacitors affect the reliability of the drives and narrow the conduction angle of diode-rectifier. As a result, the grid side current is distorted and the power factor is deteriorated. In order to settle these issues, small dc-link capacitors can replace the electrolytic capacitors. In this paper, a motor torque control method with dc-link voltage feed-forward compensation for an interior permanent magnet synchronous motor (IPMSM) drive system is proposed. Hence, an integration multi-resonant ( I-MR ) controller is established to regulate the motor torque to obtain high input power factor and low grid current harmonics. In addition, a voltage feed-forward compensation is used to diminish the error of motor torque control. The effectiveness of the proposed method is verified through simulation and experiments. Results indicate that the input power factor can reach about 99.4% and the grid current harmonics are considerably lower than the requirement of EN-61000-3-2 standard.

Analysis and Design of a Polar Digitally Modulated CMOS PA Based on Switched Constant-Current

Typical polar digital power amplifiers (DPAs) employ unit-cells operated in class-E or D−1, denoting a switched-resistance operation which degrades linearity. Besides introducing higher demand on digital predistortion (DPD), it also requires extra quantization bits, impacting the overall efficiency and system complexity. To address this, the present work makes use of an optimized constant-current cascode unit-cell which is combined with reduced conduction angle to achieve linear and efficient operation, while minimizing the effort on DPD and/or calibration. A design strategy is developed which focuses on the cascode bias voltage and transistor relative dimensions as design parameters, allowing cascode efficiency optimization without compromising linearity or reliability. A single-ended polar switched constant-current DPA is implemented in 180-nm standard CMOS. Continuous-wave measurements performed at 800 MHz demonstrate an output power of 24 dBm with a PAE of 47%. The DPA dynamic behavior was tested with a 64-QAM signal with 10 MS/s, achieving an average PAE of 20.9% with a peak-to-average power ratio (PAPR) of 8.7 dB and adjacent-channel leakage ratio (ACLR) = 40.34 dB. These results demonstrate comparable performance with the prior art while using only 6-bits clocked at 100 MHz baseband sampling frequency.

Intuitive Understanding of Flicker Noise Reduction via Narrowing of Conduction Angle in Voltage-Biased Oscillators

This brief aims to intuitively explain and numerically verify the observed phenomenon of flicker noise reduction in oscillators of reduced conduction angle (i.e., in class-C), which has been presented in literature but never properly explained. The flicker phase noise in a voltage-biased oscillator capable of operating in class-B and class-C is compared and numerically verified using a commercial simulation model of TSMC 28-nm CMOS. We illustrate how narrowing the conduction angle can suppress the $1/{f}$ noise up-conversion by decreasing $1/{f}$ noise exposure to the asymmetric rising and falling edges of oscillation waveform. The effects of implicit common-mode tank in the class-C operation is also discussed. We further clarify ambiguities among several simulation methods of impulse sensitivity function (ISF) based on periodic small-signal analysis [periodic AC or periodic transfer function (PXF)], which is a key tool in understanding the flicker noise up-conversion. A clearer ISF simulation method based on positive sidebands of PXF is proposed.

The On-Resistance Model of Silicon Carbide Merged PiN Schottky (MPS) Diodes

A novel resistance model of silicon carbide (SiC) merged PiN Schottky diodes (MPS) is presented in this study. With this model, the device characteristics and power dissipation can be predicted. The on-resistance in the three operating modes, namely, unipolar, low-injection and high-injection modes, is calculated. In the unipolar and low-injection modes, the effect of temperature on carrier mobility and conduction angle are added to the factors that need to be considered, whereas the influence of current density is considered in the high injection mode. The carrier distribution in the high injection mode is analyzed and applied to determine the resistance. The model is verified experimentally via comparison of the calculated and measured characteristics.

Harmonics and THD in Five Phase Inverters

Now-a-days most of the appliances and machine works on AC power. If AC power is unavailable for a short period of time, then during that period we need to supply AC power by converting the stored DC power. This can be possible using an Inverter. Inverters can be of multi-phase i.e. 3phase, 5phase, 6phase and so on. Since inverters have wide application in industries and HVDC transmission lines, the improvement in the output voltage and the reduction in harmonics are of utmost importance. In this paper a detailed analysis of harmonics and THD in a five phase inverter with different conduction angle along with the derived mathematical equations has been presented. A comparative study between three phase and five phase inverters at different conduction angle has been presented.

An Analytical Model for Hot Carrier Induced Long-Term Degradation in Power Amplifiers

Degradation of power amplifier (PA), being a main part of a transceiver chain, affects the overall performance of a transceiver. This article reports, for the first time, an analytical reliability model of the hot-carrier injection (HCI) induced degradation in silicon-based PAs. HCI causes substrate current which is used to develop the proposed model. This model fits very well the simulation results of RelXpert, which is a well-established reliability simulation tool. This model predicts circuit degradation as a function of conduction angle and is valid for the different classes of PAs. With this model, a new approach for “reliability aware design” for PA design is developed and a tradeoff between PA performance and reliability is introduced.

Optimum Hybrid Modulation for Improvement of Efficiency Over Wide Operating Range for Triple-Phase-Shift Dual-Active-Bridge Converter

Triple-phase-shift modulation of a dual-active-bridge converter allows soft switching over the complete power flow range due to additional degree of freedom control over the transformer current. Optimization of conduction angles and a phase shift between the primary and secondary bridges can allow minimized rms and peak current, which directly influence device stress and conduction and switching losses. However, the existing state of the art addresses this by using either an offline optimization-based controller or large offline data-based methods, which are expensive and require excessive resources. In this article, a piecewise model of the modulation scheme is developed, which allows analytical optimization. In addition, soft-switching conditions are included in the optimization framework allowing a complete solution, which reduces both conduction and switching losses. Finally, a hybrid controller has been proposed based on the generalized optimization results. It utilizes the optimum modulation for a given power and ensures the highest efficiency over a wide operating range. The model, the optimization framework, and the hybrid controller were developed theoretically and simulated in the MATLAB environment. A 200-W prototype was built as a proof of concept. The optimization results and the proposed controller were experimentally verified with good agreement to the theoretical analysis.

Simplified First-Pass Design of High-Efficiency Class-F−1 Power Amplifiers Based on Second-Harmonic Minima

This paper investigates the source and implication of efficiency minima that is typically observed during the second-harmonic load–pull of transistor amplifiers. The study starts with the theoretical derivation of time-domain voltage and current waveforms as a function of conduction angle ( $\alpha$ ) at the second-harmonic efficiency minima, where the output power and drain efficiency (DE) are at minimum. Thereafter, this paper unfolds a systematic re-engineering approach that is developed to recover the performance degradation and to exploit the region of efficiency minima in favor of design and implementation of high-efficiency inverse class-F power amplifiers (PAs). Interestingly, the inferences drawn from the in-depth analysis are shown to provide a simplified first-pass design approach that guarantees inverse class-F PA operation without an a priori knowledge of device parasitic elements. Theoretical postulations and simulation results are experimentally validated using an on-wafer active harmonic load–pull and a prototype design using 1.95-mm NXP gallium nitride die at a frequency of 2.6 GHz. The designed PA delivers an output power of 40 dBm with DE of 76% and gain of 12 dB at 3-dB gain compression. The measurement results confirm the theoretical framework reported in this paper.

Analysis and Experimentation on a New High Power Factor Off-Line LED Driver Based on Interleaved Integrated Buck Flyback Converter

This paper presents a high power factor (PF), low total harmonic distortion (THD) light-emitting diode (LED) driver with dimming capability. In addition, the proposed technique ensures a high PF and low THD at any dimming level. The driver is implemented by using an interleaved capacitor, which is placed between the rectifier and the integrated buck flyback converter (IBFC). In this way, the line current conduction angle is increased, which in return increases the PF and decreases the THD. The operation of the proposed converter ensures that one diode of the conventional IBFC will not conduct, so that it can be removed. Moreover, owing to the continuous power flow, the proposed technique makes a significant reduction of the converter output ripple. The paper presents a prototype of the proposed converter supplying an LED luminaire of 37 V/ 0.67 A. The prototype shows a high PF of 0.997, small THD of 2.5%, output current ripple of 6%, and an efficiency of 80%.

The Output Voltage Control Strategy for DSEG With Controlled Rectification Based on Conduction Angle Estimation

Owing to the merits of smaller voltage ripples, lower armature current and cost compared to full-control (FC), the angular position semicontrol (APSC) scheme is proposed in this paper for low-speed range of the doubly salient electromagnetic generator (DSEG) operating over wide speed range, which improve the output voltage without increasing the field current. In APSC, the energy is stored with positive current in the inductance rising area and negative current in the inductance falling area, by which the output power and voltage increase, and the excitation current reduces. Moreover, in order to improve the poor dynamic performance resulting from the large-storage capacitor required for APSC, first, an ideal output voltage model is established according to the ampere–second balance of the energy storage capacitor on the load side. Second, several correction methods are investigated to enhance the accuracy of the ideal model. Finally, based on the conduction angle estimation model, a novel output voltage control strategy is put forward. The feasibility and superior dynamic performance of the proposed strategy are validated by the experiment results.