Ripple Noise Research Articles

Two-Segment Three-Phase PMSM Drive With Carrier Phase-Shift PWM for Torque Ripple and Vibration Reduction

This paper presents a two-segment motor system powered by two inverters with phase-shift pulsewidth modulation (PWM) to fulfill the purpose of low-torque ripple and vibration noise. Different from conventional multi-inverter structure, the inverters for this type of machine are electrically isolated between each other. First, the concept of multisegment machine is presented and the basic operation principle is analyzed with finite-element analysis (FEA) method. Then vibration caused by the switching device in machine is investigated and the control model of a two-segment motor is developed. Further, the principle of carrier phase-shift PWM is illustrated with the vibration analysis. Carrier phase shift can generate interleaved torque and force on the rotor for the two groups of windings in the machine and cancel each other for certain harmonics. Then simulation of control strategy for this type of machine has been done in MATLAB. Finally, based on the concept and principles mentioned before, a two-segment motor with its drive system is fabricated. Both the test of torque ripple and the vibration of the motor have been significantly improved. Compared with a normal three-phase motor driven by a paralleled inverter with interleaving, the proposed approach is with comparable vibration reduction but without using extra coupled inductors.

A 2.5-W 40-MHz-Bandwidth Hybrid Supply Modulator With 91% Peak Efficiency, 3-V Output Swing, and 4-mV Output Ripple at 3.6-V Supply

We describe a supply modulator comprising a proposed delay-based hysteresis controller, proposed wideband class-AB amplifier, and class-D amplifier for an envelope tracking (ET) power amplifier (PA). We investigate the power dissipation and optimization method of the supply modulator for wideband applications taking into consideration the propagation delay, and show that a controller with zero threshold current not only improves the bandwidth of the supply modulator but also reduces its power dissipation. Based on our investigations, we propose a delay-based hysteresis controller embodying a novel high-speed current comparator whose reference current (threshold current) is zero, thereby achieving higher power-efficiency and simpler hardware. We further propose a class-AB amplifier, which features a high bandwidth and accurately controlled quiescent current. The proposed supply modulator features simultaneously the wide bandwidth (40 MHz), high output power (2.5 W), high peak efficiency (91%), high output voltage swing (3 V), and low output ripple noise (4 mVrms) at 3.6-V supply. The ET PA embodying our proposed supply modulator achieves a high power-efficiency of 41.4% at 28.5-dBm peak output power and 34.4% at 3-dB backoff—a significant >1.6× improvement over the radio frequency PA without the supply modulator.

A Multi-objective Optimization of Switched Reluctance Motor using a Hybrid Analytic-ANFIS Model Considering the Vibrations

Switched reluctance motors have a rugged construction which makes them suitable for many applications. But, high torque ripple, vibration, and acoustic noise are the main drawbacks of them. In this paper, the vibration is considered in optimization besides the other desired considerations. The radial force is the main origin of vibration in switched reluctance motor, and a torque-to-force ratio is introduced for considering the low vibration in optimization. Also, modeling of switched reluctance motor is somehow challenging. In this paper, a hybrid method based on analytic and adaptive-neuro-fuzzy inference system methods is presented for modeling SRM and the obtained static characteristics are used in a dynamic simulation method. Discussion on simulation results is presented at the final part of the paper which shows the lower vibrations lead to bigger air gap length; so, to prevent the deterioration of other features, an optimization should be done. A multi-objective particle swarm optimization is used to find the dominant design, and the best design is obtained by means of weighted cost functions.

Analysis of operating noise characteristics and contribution for automotive seat backrest adjuster

Background/Objectives: This study involved basic research on operating noise in an automotive seat backrest adjuster through analysis of noise sources, noise source contributions, and seat pad noise reduction effects.Methods/Statistical analysis: The test product was a driver seat of 3300cc commercial sedan. First, basic data is obtained through analysis of driving mechanism of seat backrest adjuster. Based on this, vibration and noise characteristics were analyzed by operating test of backrest adjuster, and contribution analysis to noise sources was performed. Finally, by analyzing the effect of noise reduction on the seat pad, the effect of each noise source on the backrest operating noise was determined.Findings: First, it was confirmed that the low frequency fluctuation caused by the total noise is dependent on change in the load generated by eccentric rotation of the recliner gear. Therefore, it was found that the design of the recliner gear teeth was a decisive factor in controlling the motor load. Second, the 20th order (1,320Hz) of the DC geared motor was the main cause of operating noise, which was derived from friction noise of brush-commutator and torque ripple noise. This noise accounted for more than 55% of total operating noise. In addition, the 30th order amounted to approximately 18%. In other words, the harmonic components of the DC geared motor created most of the noise, and changing the brush material and reducing torque ripple is expected to significantly improve the overall operating noise. Lastly, as a result of the seat pad noise reduction effect, total power decreased by more than 11dB (A). In addition, it was confirmed that the 20th order cause of the main noise was reduced by about 45%p.Improvements/Applications: The noise contribution of the seat recliner adjuster derived from this study can be used as a basic data for noise reduction.

An Integrated DC–DC Boost Converter Having Low-Output Ripple Suitable for Analog Applications

This paper presents an integrated boost converter having very low output voltage ripple making it suitable for analog applications, which are sensitive to supply noise. Architecturally, the converter consists of a conventional boost converter followed by an L–C filter, which drastically reduces the output ripple. The L–C filter has been realized using 30-nH bondwire inductance and 0.54-nF on-chip capacitance. The converter switches at 118 MHz and produces a regulated 3.2-V output from an input voltage ranging from 1.0 to 2.7 V. The converter is able to deliver up to 65-mA current for input voltage $\geq$ 2.4 V. The prototype has been implemented in 0.18- $\mu$ m standard digital CMOS process and the entire design consumes only 0.52-mm $^2$ chip area resulting in a maximum power density of 0.387 W/mm $^2$ . Peak efficiency of the converter is 77.4% at 32.2-mA current for 2.7-V input supply. The measured maximum output ripple noise is 21 mV that is less than 0.65% of the regulated output voltage.

A pitch encoding model based on the intrinsic oscillation circuit: Effects of the time constant and input stimulus types

Many temporal models for pitch perception have adopted a configuration of delay-lines and coincidence detectors after the cochlear filtering. Autocorrelation functions are a usual way of its implementation. However, a series of experiments by the authors' group have revealed that the perceived pitch would shift upwards by the effect of aging. Because the autocorrelation simply represents the time intervals statistics in the physical domain, the aging cannot affect this statistics. Therefore, a further pitch encoding process where the physical (physiological) temporal intervals are mapped against any internal reference in the brain. We propose a model comprised of bank of self-oscillatory circuits and the coincidence detectors. The periods of oscillations are intrinsic characteristics of the neural circuit. The proposed model could pick up the fundamental periods of a various types of stimuli, i.e., pure tones, missing fundamentals and iterated ripple noises. To check an effect of aging, the changes in t...

Control Algorithm of Two-Phase Hybrid Stepper Motor Based on Three-State Hysteresis

When the drive system of two-phase hybrid stepper motor adopts the traditional hysteresis loop control mode, it has good dynamic response performance, but also has some disadvantages such as big current ripple and big noise. In view of the above problems, the given current within one period of the winding is divided into ascending area, flat area and descending area, and the different demands for the rate of change of current in each area are analyzed in this paper. Compared with the traditional hysteresis loop, the three-state hysteresis loop has more switch combinations, which can meet the requirement of switching multiple current change rate in the driving system of two-phase hybrid stepping motor. This control algorithm based on three-state hysteresis loop presented in this paper can not only guarantee the dynamic response performance, but also greatly reduce the current ripple. The relationship between current ripple and terminal voltage, inductance and control frequency is derived in this paper. The hardware platform was set up with Cyclone IV FPGA of Altera company as the core processing chip, and the two-phase hybrid stepping motor of Oriental motor company model PK299DB was taken as the control object for experimental verification. Simulation and experiment verify the effectiveness of the algorithm.

High Performance BCD Integrated Buck-Boost Converter in an AMOLED Display with Application of Self-Triggering Frequency Modulation

Feedback control for self-triggering frequency modulation is proposed for an integrated buck-boost DC-DC converter in an AMOLED display. The goal is to reduce the ripple noise and tran ...

Design of a charge pump for high voltage driver applications based on 0.35 μm BCD technology

Based on the switched capacitor system theory, a new charge pump is designed as the driver of the H-bridge power circuits. The proposed circuit is added with the output feedback control module to realize the steady output, lower the ripple and power noise, and improve the transforming efficiency. Simulation based on 0.35 [Formula: see text] BCD350GE process demonstrates that the circuit has a ripple voltage as low as 200 mV and reaches a high efficiency up to 70% with a load as much as 20 mA when the supply voltage changes from 8 V to 36 V.

Direct instantaneous torque and force control: a control approach for switched reluctance machines

Switched-reluctance technology is appealing to the automotive industry due to its low cost. Conventional research focuses on the two main issues, namely torque ripple and acoustic noise. However, control schemes usually only address one of these two issues at a time. This study unifies the approaches of direct instantaneous torque control and direct instantaneous force control to simultaneously eliminate two central drawbacks of switched reluctance machines (SRMs). A search algorithm was used to predict appropriate reference values for each phase to keep torque and overall radial force smooth at any time. Simulation and measurement results confirmed that the control objectives were met so that torque ripple was reduced and the acoustic behaviour of the investigated automotive traction drive was simultaneously improved. A comparison with conventional control methods investigating vibrations and efficiency is provided. The proposed control approach thus provides future engineers with a powerful tool for adapting SRMs to the requirements of the automotive sector.

Research for SVPWM Control Method of Brush-less DC Motor Using Z-source Converter

A novel brush-less DC motor SVPWM control method based on Z-source converter is proposed in this paper. The proposed method can increase speed range by utilizing the shoot-through state to boost the DC voltage and also has the advantage of high stability, small torque ripple, high efficiency and low noise, effectively solving the problem of small speed range, large torque ripple and poor stability of existing control system. A novel mathematical model is also derived for motor control. With the algorithm simulation advantage of MATLAB and the circuit structure simulation advantage of PSIM, The united simulation results of MATLAB and PSIM are analyzed in detail.

Effects of Long-Term Musical Training on Cortical Auditory Evoked Potentials.

Evidence suggests that musicians, as a group, have superior frequency resolution abilities when compared with nonmusicians. It is possible to assess auditory discrimination using either behavioral or electrophysiologic methods. The purpose of this study was to determine if the acoustic change complex (ACC) is sensitive enough to reflect the differences in spectral processing exhibited by musicians and nonmusicians. Twenty individuals (10 musicians and 10 nonmusicians) participated in this study. Pitch and spectral ripple discrimination were assessed using both behavioral and electrophysiologic methods. Behavioral measures were obtained using a standard three interval, forced choice procedure. The ACC was recorded and used as an objective (i.e., nonbehavioral) measure of discrimination between two auditory signals. The same stimuli were used for both psychophysical and electrophysiologic testing. As a group, musicians were able to detect smaller changes in pitch than nonmusician. They also were able to detect a shift in the position of the peaks and valleys in a ripple noise stimulus at higher ripple densities than non-musicians. ACC responses recorded from musicians were larger than those recorded from non-musicians when the amplitude of the ACC response was normalized to the amplitude of the onset response in each stimulus pair. Visual detection thresholds derived from the evoked potential data were better for musicians than non-musicians regardless of whether the task was discrimination of musical pitch or detection of a change in the frequency spectrum of the ripple noise stimuli. Behavioral measures of discrimination were generally more sensitive than the electrophysiologic measures; however, the two metrics were correlated. Perhaps as a result of extensive training, musicians are better able to discriminate spectrally complex acoustic signals than nonmusicians. Those differences are evident not only in perceptual/behavioral tests but also in electrophysiologic measures of neural response at the level of the auditory cortex. While these results are based on observations made from normal-hearing listeners, they suggest that the ACC may provide a non-behavioral method of assessing auditory discrimination and as a result might prove useful in future studies that explore the efficacy of participation in a musically based, auditory training program perhaps geared toward pediatric or hearing-impaired listeners.

Sensorless Control of Nonsinusoidal Permanent Magnet Brushless Motor Using Selective Torque Harmonic Elimination Control Method Based on Full-Order Sliding Mode Observer

Nowadays, due to excellent advantages of permanent magnet brushless (PMBL) motors such as high efficiency and high torque/power density, they are used in many industrial and variable-speed electrical drives applications. If the fabricated PMBL motor has neither ideal sinusoidal nor ideal trapezoidal back-EMF voltages, it is named nonideal (or nonsinusoidal) PMBL motor. Employing conventional control strategies of PMSMs and BLDCMs lowers the efficiency and leads to unwanted torque ripple, vibration, and acoustic noises. Moreover, in many applications to reduce the cost and enhance the reliability of drive, sensorless control techniques are used. This paper proposes a novel sensorless control for a nonsinusoidal PMBL motor with minimum torque ripple. To develop smooth torque, the selected torque harmonic elimination strategy is employed. Furthermore, to estimate the rotor position and speed, a novel full-order sliding mode observer is designed. Proposed observer estimates the position and speed of motor from standstill to final speed. The proposed observer is robust to uncertainty of harmonic contents in phase back-EMF voltage and able to run the motor from standstill with closed-loop control scheme. The capabilities of torque ripple minimization and sensorless strategies are demonstrated with some simulations.

Controlled Voltage Source Vector Control for Switched Reluctance Motors Using PWM Method

SUMMARYThis paper proposes controlled voltage source vector control for switched reluctance motors using the pulse width modulation method. This proposed technique can achieve high controllability for variable speed drives, low current ripple and low noise operation, and high motor efficiency at high speed. Moreover, its implementation is easy because the controller design does not require complicated offline data such as the magnetization characteristics. To verify the effectiveness, an experiment was conducted to compare the performances of the proposed technique and a conventional unipolar drive using the hysteresis comparator method.

Practical approach to power integrity‐driven design process for power‐delivery networks

The authors present a practical design process that considers the power noise problem in CPU blocks for application processors used in smart TVs. The target impedance is determined by modelling the RLC circuit of a system-on-chip power net. The target impedance of a power delivery network is then determined by applying the extracted chip current profile for finalising the design budget. The authors modelled the on-chip power net by combining vector network analyser measurements with an on-chip model for power integrity analysis. The authors demonstrated the optimisation and design strategy by using a ball grid array ball interconnection and case studies on the placement of multilayer ceramic capacitors. The simulation results showed good agreement with the measurement results. The error in the minimum value (negative direction) by voltage droop was less than 8.6%, while the difference in voltage noise ripple was 2.69% for a criterion of 1.1 V assuming a worst-case condition of 1.2 V.

Study on the fabrication of low-pass metal powder filters for use at cryogenic temperatures

We fabricated compact low-pass stainless-steel powder filters for use in low-noise measurements at cryogenic temperatures and investigated their attenuation characteristics for different wire lengths, shapes, and preparation methods up to 20 GHz. We used nominally 30-micrometer-sized SUS 304L powder and mixed with Stycast 2850FT by Emerson and Cumming with catalyst 23LV. A 0.1 mm insulated copper wire was wound on preformed powder-mixture spools in the shape of a right-circular cylinder, a flattened elliptic cylinder and a toroid, and the coils were encapsulated in metal tubes or boxes filled with the powder mixture. All the fabricated powder filters showed a large attenuation at high frequencies with a cut-off frequency near 1 GHz. However, the toroidal filter showed prominent ripples corresponding to resonance modes in the 0.5-m-long coil wire. A filter with a 2:1 powder/epoxy mixture mass rate and a wire length of 1.53 m showed an attenuation of -93 dB at 4 GHz and the attenuation was linearly proportional to the wire length. As the powder-to-epoxy ratio increased, the high-frequency attenuation increased. An equally-spaced single-layer coil structure was found to be more efficient in attenuation than a double-layer coil. Geometry of the metal filter-case affected noise ripples with the least noise in a circular-tube case.

An Improved Sideband Current Harmonic Model of Interior PMSM Drive by Considering Magnetic Saturation and Cross-Coupling Effects

The sideband current harmonics, as parasitic characteristics in permanent-magnet synchronous machine (PMSM) drives with space vector pulsewidth modulation technique, will increase the corresponding electromagnetic loss, torque ripple, vibration, and acoustic noises. Therefore, fast yet accurate evaluation of the resultant sideband current harmonic components is of particular importance during the design stage of the drive system. However, the inevitable magnetic saturation and cross-coupling effects in interior PMSM drives would have a significant impact on the current components, while the existing analytical sideband current harmonic model neglects those effects. This paper introduces a significant improvement on the analytical model by taking into account these effects with corresponding nonlinear factors. Experimental results are carried out to underpin the accuracy improvements of the predictions from the proposed model over the existing analytical one. The proposed model can offer a very detailed and insightful revelation of impacts of the magnetic saturation and cross-coupling effects on the corresponding sideband current harmonics.

Fundamental Study of Influence of Ripple Noise From DC–DC Converter on Spurious Noise of Wireless Portable Equipment

Power supply noise is a serious concern in noise-sensitive radio frequency or analog circuits. This paper presents an analysis of the influence of the synchronous rectification buck-type dc–dc converters for power amplifiers. An output ripple noise equation of the converter and a spurious noise equation of the carrier output voltage of the class-A amplifier powered by the converter are derived to analyze fundamental characteristics of these noise components theoretically. The amplifier's output spurious noise is calculated by these equations and measured by the evaluation circuit board. The spurious noise variation caused by the parameter variations of the amplifier or the converter is discussed based on these experimental and theoretical results. The spurious noise can be suppressed by decreasing the channel length modulation coefficient of the n-channel MOSFET constituting the amplifier and the natural frequency of the converter output LC filter. The spurious noise is reduced to low level below − 60 dB compared to the carrier signal by setting the channel length modulation coefficient below 0.1 V−1 and the natural frequency below 120 kHz. Furthermore, when the natural frequency is below 40 kHz, the spurious noise is − 80 dB below the carrier signal.

Circuit Performance Classification With Active Learning Guided Sampling for Support Vector Machines

Leveraging machine learning has been proven as a promising avenue for addressing many practical circuit design and verification challenges. We demonstrate a novel active learning guided machine learning approach for characterizing circuit performance. When employed under the context of support vector machines (SVMs), the proposed probabilistically weighted active learning approach is able to dramatically reduce the size of the training data, leading to significant reduction of the overall training cost. The proposed active learning approach is extended to the training of asymmetric SVM classifiers, which is further sped up by a global acceleration scheme. We demonstrate the excellent performance of the proposed techniques using four case studies: 1) dc/dc converter ripple noise analysis; 2) phase-locked loop lock-time verification; 3) reliability analysis of a ring oscillator with respect to process variations and initial conditions; and 4) prediction of chip peak temperature using a limited number of on-chip temperature sensors.

A digital predistortion assisted hybrid supply modulator for envelope tracking power amplifiers

In this paper, a novel digital predistortion assisted supply modulator is presented. The proposed modulator is suitable for envelope tracking power amplifiers. In this topology, a digitally controlled linear power amplifier is used to compensate the switching noise ripples of the switching modulator. The proposed structure is evaluated with a 0.18µm CMOS process technology. The results show up to 9% static efficiency improvement in comparison with previous one-phase and two-phase architectures. It is shown that for a 5MHz WiMAX signal with a 6.7dB PAPR at 26.8dBm output power, a maximum average efficiency of 73.5% is achieved in the proposed design.