Conduction Angle Research Articles

Class iCGF–1 Mode Power Amplifier for Enhancing the Linearity of the Traditional Continuous Class F–1 Mode

ABSTRACTIn this paper, the iCGF−1 mode is proposed to compensate the amplitude‐to‐amplitude modulation (AM/AM) distortion of the traditional continuous class F−1 mode while maintaining the high efficiency. The AM/AM profile of the iCGF−1 mode is mathematically expressed simultaneously as a function of the input nonlinearity parameter and conduction angle , which makes the iCGF−1 mode more flexible in controlling the AM/AM profile. The first inflection point of the AM/AM profile can be moved to a higher output power level through theoretical deduction by adjusting the second harmonic source impedance and gate bias voltage to increase the values of and . This flattens the AM/AM profile while the efficiency profile remains almost the same as that of the traditional continuous class F−1 mode. The performance of the iCGF−1 mode is verified through simulation and experimental measurements. The iCGF−1 PA is fabricated with CGH40010F and has a frequency range of 2–2.6 GHz. The drain efficiency is 70.1%–77.9%, and the output power is 41.1–41.7 dBm. The linearity is tested with a 100 MHz 5G NR signal (the peak average power ratio (PAPR) is 8.5 dB) at 2.3 GHz. The worst adjacent channel power ratio (ACPR) is −32.3 dBc without digital predistortion (DPD) and −52.1 dBc with DPD. The results show that the iCGF−1 mode has successfully compensated the AM/AM distortion of the traditional continuous class F mode and maintaining high efficiency.

A novel direct instantaneous torque control strategy in permanent magnet-assisted switched reluctance motor based on optimization of conduction angle

A novel direct instantaneous torque control (DITC) strategy based on optimized conduction angle is proposed with the aim of reducing the torque ripple of permanent magnet-assisted switched reluctance motor (PMa-SRM) during the two-phase exchange (TpE) region in this paper. Firstly, according to the inductance characteristics, the TpE region is subdivided into TpE I and TpE II region where the turn-off angle is acted as the region separation point, and the corresponding torque hysteresis strategies are formulated in different regions. Secondly, K-fold extreme learning machine (ELM) method is used to optimize the turn-on angle in order that the current of incoming phase can quickly increase to maintain torque balance. In order to make full use of the ability of torque generation of two adjacent phases, the position where the torque of adjacent phases is equal is used as the turn-off angle of incoming phase. Finally, a 6/20 PMa-SRM prototype is simulated and verified. Compared with the conventional DITC strategy, the novel strategy not only diminish torque ripple and negative torque under different operating conditions, but also expands the operating range of the motor and improves the motor efficiency.

Ultra-Generalized Continuous Class F Power Amplifier with Finite Third-Harmonic Load Impedance

This paper proposes the ultra−generalized continuous class F (UCCF) mode, which combines the influences of the drain current conduction angle and overdriven transistor on the drain current waveform to achieve a broader finite third-harmonic load impedance space. The UCCF mode uses α to describe the magnitude of the drain current conduction angle and pcr to describe the drain current peak-clipped ratio. An analysis of the effects of pcr and α on the linearity and efficiency of the UCCF model is presented, establishing a robust theoretical foundation for achieving a balance between these two characteristics. Additionally, an examination of how pcr and α influence the load impedance design space is conducted, demonstrating that the UCCF mode not only offers a broader finite third-harmonic load impedance space but also expands the fundamental and second-harmonic load impedance design space. For practical validation, a PA with frequency of 2.05–2.65 GHz is designed based on CGH40010F. The test results show that S11 is less than −15 dB, the drain efficiency is 67.0–73.2%, and the output power is 40.1–41.0 dBm. The linearity is tested using a 5G NR (New Radio) signal with a bandwidth of 100 MHz and a peak-to-average power ratio of 8 dB at 2.35 GHz. The worst adjacent channel power ratio (ACPR) is −34.8 dBc without digital predistortion (DPD), and −57.8 dBc with DPD. An average output power (Pave) of around 32.4 dBm and an average DE (DEave) of 34.39% were obtained.

Design and Simulation of VCO for RF Transceivers with Low Power, Low Phase Noise and Wider Tuning Range using Silterra 130nm CMOS Technology

The performance of low-power transceivers is required to meet stringent specifications for an advanced wireless radio frequency (RF) application. The design topology in this paper is simulated to meet the specifications and operation of VCO for low power, low phase noise and wide tuning range in complementary metal oxide semiconductor (CMOS) 130nm technology for RF transceivers. The relationship between the phase noise, power consumption and frequency turning range is fully analyzed to further improve the performance of the voltage-controlled oscillator (VCO). The architecture of the VCO employs two sets of symmetrical cross-couple split NMOS and PMOS with biased current sources operating in the triode region, and a resonator tank that achieves the desired low phase noise performance of about -110 dB/Hz at a tuning range of 4.1 to 4.5 GHz with a supply of 0.9 V. The control of the DC bias point reduces the conduction angle, which improves the current efficiency, power consumption and phase noise. The topology generates sufficient –gm for the oscillator incorporation to mitigate the start-up issue of the VCO. At the center frequency of 4.38 GHz, the VCO serves as a promising solution for improving low power and low phase for wireless communication systems and RF transceiver applications. The design consumes a very low power of 0.138 mW, achieves a phase noise of -110.53 dBc/Hz at 1 MHz offset, and a figure of merit (FoM) of -191.90 dBc/Hz.

Examining the Thyristor-Controlled Reactor's (TCR) Performance to minimize Self-Generated Harmonics.

This work discusses the minimizing of self-generated harmonics in a Thyristor Controlled Reactor (TCR) used in a power distribution system. When a nonlinear load is connected to the system, power quality difficulties arise, including reactive power compensation, harmonics, voltage unbalance, poor power factor, and so on. These flaws degrade the power quality of the system. FACTS and electronics devices are most commonly employed for reactive power correction. A conventional Static VAR compensator is the best option for this application. The static VAR compensator consists of either a fixed capacitor-thyristor controlled reactor (FC-TCR) or a thyristor switched capacitor-thyristor controlled reactor (TSC-TCR). The reactive power demand objective can be met by controlling the conduction angle of TCR. However, the switching operation of the thyristor-controlled reactor reduces power quality by adding self-generated harmonics into the system. The proposed topology in this study outlines the usage of a delta-connected TCR to reduce self-generated harmonics rather than a thyristor controlled reactor (SCR).
 The work carried out in this paper has two major sections
 
 Determine (a) the firing angle range for reactive power adjustment, and (b) the mechanism to control inductive susceptibility. 2. A comparison of three presented methods: a) single delta connected TCR; b) Equally stepped delta connected TCR (ESTCR); and c) Binary stepped delta connected TCR (BTCR).

The Design and Dynamic Control of a Unified Power Flow Controller with a Novel Algorithm for Obtaining the Least Harmonic Distortion

This study investigates the control and dynamic operation of the Unified Power Flow Controller made of shunt and series converters, a Static Synchronous Compensator, and a Static Synchronous Series Compensator, respectively, connected back-to-back through a common DC-link capacitor. The model of a 48-pulse Voltage Source Converter is constructed from a three-level Neutral Point Clamped converter, which allows the total harmonic distortion to be reduced. An optimal conduction angle tracking system of the three-level inverter is designed to minimize distortion by detecting proper harmonic component elimination. Starting from the six-step modulation strategy, the dq decoupled control schemes of both compensators in open and closed loops are presented. Finally, the MATLAB-Simulink model of the power flow controller is implemented and analyzed. The results show that the controller can track the power changes and apply a suitable voltage to the power system so that the power flow can be controlled. This way, the power flow controller dynamically improves the voltage and power quality across the power network while simultaneously improving the transient stability of the system. It can eliminate all system disturbances resulting from oscillations and harmonics in voltage and current within a very short time. The procedural approach used to model and simulate the Unified Power Flow Controller, as well as the new algorithm used to obtain the harmonic number that minimizes the total harmonic distortion, can be applied to any AC power system.

A 12-pulse rectifier using coupled reactors for supplying three-inverters

The paper presents a proposal of an auspicious multi-pulse rectifier convenient for supplying three-level inverters. The rectifier consists of two three-phase bridges. Their outputs are connected in parallelwhile inputs are connected to the line by use of coupled reactors These reactors are connected and work in an exceptional variant 3CRλ. The application of 3CRλ makes that the diodes conduction angle in rectifiers achieves 180°. Simulation and experimental works prove that multi-pulse rectifier gives a worthy performance and has some respectable properties.

Intelligent Approach for Control Techniques Based on Complex Converter Structures

Hybrid frequency control strategies are used to eliminate the problem of current inversion in multilevel cascaded asymmetrical H-bridge inverters. Unfortunately, this technique results in unbalanced power at the inverter output. The improved hybrid PWM modulation strategy helps to regulate power balances within a reasonable range at high and low voltages, by adjusting the conduction angle of the cells in high frequencies. However, as the conduction angle of a high-voltage cell increases, the fundamental amplitude of the inverter output voltage decreases, since waveforms with absolute values greater than 2 E cannot be perfectly modulated. Based on mathematical models of the conduction time for each level synthesis method, a new modulation strategy is proposed to solve the problems associated with the two strategies mentioned above. This new high-frequency modulation strategy adopts a combination of pulse-width modulation (PWM) and step modulation to combine control of the high-voltage and low-voltage units. At given intervals, the control voltage signals of the low-voltage unit are exchanged. Finally, the power of each unit is balanced and the basic amplitude of the inverter output voltage is not affected. Finally, the MATLAB/Simulink simulation model and experimental platform verify the feasibility of this strategy.

Optimal Torque Sharing Function Control for Switched Reluctance Motors Based on Active Disturbance Rejection Controller

In this article, an optimal torque sharing function (TSF) control method incorporated with improved linear active disturbance rejection control (LADRC) and modified coyote optimization algorithm (MCOA) is introduced and applied in switched reluctance motors (SRMs). First, the piecewise TSF is employed to reduce the torque ripple, which exhibits little effects on the rate of current change and the current peak value. The improved linear extended state observer with the variable gain in speed controller using LADRC is designed to guarantee better antidisturbance ability and torque ripple reduction simultaneously. Then, the MCOA is introduced to automatically tune the parameters including the turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> angle, conduction angle, and coefficients for better comprehensive performances. Finally, comparisons among the conventional TSF with LADRC, the piecewise TSF with LADRC, and the proposed TSF with improved LADRC are conducted both in the simulations and experiments. The results indicate that the proposed method behaves best in aspects of torque ripple suppression and anti-interference ability among the three methods.

Design of a High–Efficient IPT System for Battery Charging Under CP-CV Charging Scenarios

Maintaining high efficiency and controlling output voltage with variable load is challenging for inductive power transfer (IPT) based battery charging systems. In addition, choosing the proper charging scenarios simultaneously with the battery's equivalent load variation significantly improves the charging rate. This paper proposes a semi-active rectifier (SAR) battery charging system on the basis of a series-series resonant IPT system using constant-power (CP) and constant-voltage (CV) charging modes. A novel control approach based on the adaptive selection of the operating frequency of IPT and the conduction angle of the SAR is used to achieve high efficiency in CP-CV modes. The inverter and the SAR are both capable of soft switching. Furthermore, considering the same maximum power in CP and constant-current (CC) modes, the CP mode offers more charging rate with less destructive effects. The proposed control strategy has been simulated, and a prototype system is implemented to show the high-efficiency performance of the system during CP-CV modes.

Extended Operation of Brushless DC Motors Beyond 120° Under Maximum Torque Per Ampere Control

Hall-sensor-controlled brushless dc (BLDC) motors are widely used in many electromechanical applications due to their simplicity and good torque-speed characteristics. The conventional commutation methods include the 120° and 180° switching logics that can be derived directly from the Hall sensor signals. The 120° switching method is the most common due to its natural approximation of the maximum torque per Ampere (MTPA) operation, while the 180° switching method offers a higher available phase voltage for the same dc voltage. Both methods are typically used with additional pulse-width modulation to control the motors from a fixed dc source. Recently, attention has been given to the operation of BLDC motors with conduction angles between 120° and 180° (e.g., 150°, 160°, etc.), where some benefits may be gained. This paper proposes a new methodology that continuously extends the operation from 120° to 180°, while maintaining the MTPA property. Simulations and experimental results based on a typical industrial BLDC motor demonstrate the proposed control methodology and its benefits over the conventional alternative methods.

A High-Power Capacity Transistor-Based Rectifier With Wide Input Power Range

This letter proposes a methodology for realizing the rectifier with a wide radio frequency (RF) input power range for large power capacity applications. The comprehensive analysis is given in this letter under the condition of class-F operation mode. The optimum conduction angle of the transistor corresponding to the maximum input power dynamic range is determined. Theoretical rectification efficiency of over 60% can be obtained in a 30 dB in-depth input power level. For validation, an RF-dc rectifier operating at 2.45 GHz is designed based on the GaN transistor. Measurements demonstrate that the rectification efficiency of between 60.4% and 82.1% is realized with a fixed dc load of 115 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega $</tex-math> </inline-formula> when the RF input power is from 18 to 43 dBm. To the best of the authors’ knowledge, it is the first realization of a transistor-based RF-dc rectifier with a large input dynamic range of over 25 dB. The proposed rectifier shows great potential to be used in future high-power wireless power transfer (WPT) applications.

Grid-Side Current Harmonic Suppression and Power Factor Improvement Using q – Axis Damping Current Injection for PMSM Drives Without Electrolytic Capacitor

The dc-link film capacitor with low-capacitance in permanent magnet synchronous motor (PMSM) drives without electrolytic capacitor will not only reduce the system stability, but also generate LC resonance with the grid-side filter inductor, which is the important reason for high grid side harmonic current and low power factor. In this paper, a grid side current harmonic suppression strategy using q-axis damping current injection is proposed to address these issues of PMSM drives without electrolytic capacitor. The analysis of the transfer function based on the simplified circuit of the drive shows the instability and LC resonance of the system. The feedforward modification method based on the difference between the quasi-dc-link voltage and the dc-link voltage is applied to improve the system performance. Meanwhile, the specific implementation of the proposed method by injecting damping current into the q-axis is introduced. In addition, a phase disturbance angle is introduced in the proposed control strategy to adjust the phase of quasi-dc-link voltage. By properly adjusting the phase disturbance angle, the conduction angle of the single-phase uncontrolled rectifier bridge can be effectively expanded, and the grid side power factor can be further improved. Experiments on a PMSM drive with the low-capacitance of dc-link film capacitor are carried out to verify the effectiveness of the proposed method.

Output Power Capacity Improvement Based on Three-Phase Current Balance Control for the Doubly Salient Electromagnetic Generator System

The doubly salient electromagnetic generator (DSEG) has the advantages of flexible control, high robustness, and low cost. Since multiple stator poles share a common set of field windings, the magnetic circuit of each phase is asymmetrical, which limits the output performance of the DSEG. The three-phase current balance control for the DSEG system was proposed. By investigating the current waveform under the angular position control (APC), a three-phase current prediction method was proposed. The conduction angle of the power switches in the active rectifier was predicted to make the three-phase current balanced. Based on the analysis and experiment, the current waveform was further analyzed, and the effectiveness of the three-phase current balance control was verified. Compared with the APC method, the output power capacity was improved using the three-phase current balance control under a limited winding current density. The maximum potential of the DSEG was explored, and the electromagnetic load capacity of the DSEG was fully released.

Effect of variable conduction angle on the losses of switched reluctance machine

Switched Reluctance Machine (SRM) is the advanced version of the stepper motor and since last decade, it is of high interest among researchers and industrial applications. Modelling an SRM relies on accurate data and proper selection of parameters. The next step is the performance analysis of the machine for which losses determination is indispensable. Previous studies have shown losses calculation only at a particular instant of switching of the machine (i.e., conduction angle). Therefore, the impact of losses in a motoring region cannot be justified. This paper investigates the impact of varying conduction angle on the performance of machines for a set of switch-on angle. Losses are calculated and predicted through simulating motor operating parameters carried out in MATLAB environment and accuracy of results are compared with experimental results.

A new series‐connected 36‐pulse rectifier with hybrid DC‐reinjection method for high power output

AbstractIn this study, a new 36‐pulse rectifier with a hybrid DC‐reinjection circuit is proposed. It multiplies the AC‐side input voltage steps from 12 to 36 using a hybrid auxiliary circuit for voltage and current modulation. Both the AC and DC side harmonics of the rectifier system are efficiently suppressed when combined with filter capacitors at DC side. Only 2 more diodes and an IGBT are used in the proposed approach for constituting the injection circuit. The cascaded structure of rectifier bridges allows for significant voltage gain, making it appropriate for high power output rectification applications. The proposed 12‐pulse rectifier's phase shifting structure and 36‐pulse rectifier's operational theory are introduced. The injection transformer's turn ratio and the IGBT's conduction angle are both designed to have the lowest possible harmonic distortion of the voltage at AC side. Analyses are done on the rectifier's impedance matching feature and energy loss of IGBT. The operating performance of the rectifier is assessed when the active switch fails. With the help of a 1.8 kW prototype and a HIL system based on Starsim, the theoretical portion is confirmed. The results of the simulation and experiments support the effectiveness of the hybrid voltage harmonic injection method studied.

Switched Reluctance Motor Design for a Light Sport Aircraft Application

This paper presents the design of a switched reluctance motor (SRM) for a direct-drive propulsion application for a light sport aircraft. The SRM is designed to replace a 70 kW permanent magnet synchronous motor used in aerospace application with similar dimensional constraints. As a means of achieving high torque density and efficiency, a multi-objective design framework is used to optimize the geometry parameters of the motor. In order to further reduce the weight, rotor cutouts are implemented. The conduction angles for the asymmetric bridge converter are selected by employing a multi-objective genetic algorithm to map the torque speed characteristics of the motor. The core losses are evaluated with the modified Bertotti method to calculate the motor efficiency and determine the steady-state and transient thermal performance at the base speed. The designed coil winding is wound on a spindle winder, and the coil fitting, fill factor, and the coil retention are validated experimentally.

Capacitor Voltage Balancing for Alternate Arm Converter Based on Conduction Angle and Zero-Sequence Voltage

The alternate arm converter (AAC) owns additional advantages over the traditional modular multilevel converter, such as reduced number and capacitance of submodules (SMs), and dc fault ride-through capability. The capacitor voltage balance of the AAC has always been a hot and difficult research topic. The balance performance of the conventional short-overlap control is limited by the maximum circulating currents, which may also lead to additional power losses. In this article, the conduction angle of the direction switches is employed to balance the SM capacitor voltage and a modified SM energy balance condition is developed. As the upper and lower arms are strictly alternatively conducted, the circulating currents no longer exist, leading to an improvement in system efficiency. The operation range of the AAC is also expanded under this method, so the AAC can operate far away from the sweet spot, such as grid voltage sags. A three-layer closed-loop control method based on conduction angle, zero-sequence voltage, and nearest-level modulation is further proposed, which enables the voltage balance of all SMs even under unbalanced conditions. Finally, the effectiveness of the proposed methods is verified by the simulation and hardware-in-the-loop tests.

Novel Modulation Scheme for Balancing Power Distribution Among Modules in Nine-Level Asymmetric Cascaded H-Bridge Inverter

When the conventional hybrid frequency (HF) modulation strategy applies to the asymmetric cascaded H-bridge (ACHB) inverter with dc voltage in a ratio of 1:1:2, there are uneven problems of switching loss in low-voltage cells and output power over all operating cells. Thus, a modified HF based on a dual-layer power balance (MHF-DPB) modulation strategy was presented. First, step modulation was still applied to a high-voltage cell on the basis of the conventional method, but improved level-shifted pulsewidth modulation (LS-PWM) was applied to two low-voltage cells. Subsequently, the power balance between high-voltage and low-voltage cells was controlled by adjusting the conduction angles of the power switch and then the carriers of the two low-voltage cells were rotated periodically in order to realize the two low-voltage cells’ power balance. The proposed method can not only realize the power balance of cascaded cells, but also distribute the switching loss of two low-voltage cells equally. In the meantime, it reduced the total switching loss of the inverter. Finally, it was validated by simulation and experimental results.

A Load Adaptive Hybrid DPS Control for DAB to Secure Minimum Current Stress and Full ZVS Operation Over Wide Load and Voltage Conversion Ratio

Wide variations in voltage conversion ratio and loading are the most important parameters to consider when designing off-board EV chargers to achieve high power density and efficiency. Dual phase shift (DPS) modulation provides a better way for dual active bridge (DAB) DC-DC converter operation when load side parameter variation is utmost important. To accomplish this, conventional DPS control is modified to ensure zero voltage switching (ZVS) across the entire load range despite wide variations in voltage conversion ratio. The designed control provides ZVS of all FETs as compared to the conventional DPS control over full loading range. For this, magnetizing inductance of HF isolation transformer is utilized and designed to shape the secondary side current for getting ZVS for both active legs. The light loading performance of the converter is improved with the bidirectional conduction angle control. The hybrid utilization of DPS control is incorporated with minimum peak current stress considerations. A Karush-Kuhn-Tucker (KKT) method based on Lagrange's multipliers is used for mathematical derivation of optimized solution of both control parameters. Performance of designed control is verified using experimental results for wide variation in battery terminal voltage. For validation, a 1250 W laboratory prototype is developed. A comparison of ZVS regions among the conventional and designed modulation technique, shows the effectiveness under wide voltage and loading scenarios.