Describing-function analysis of a ripple regulator with slew-rate limits and time delays

Wester, Gene W.

doi:10.1109/pesc.1990.131208

Cited by 15 publications

(7 citation statements)

References 1 publication

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“…Prior art has demonstrated several examples of this; a nonzero carrier average was used in [33] to assign a low-frequency gain to the hysteretic comparator, and it is well known [34] that a describing function can be used to find its gain at the switching/oscillation frequency of the control loop. These two methods can even be combined to yield an estimated, but still quite accurate, transfer function for the hysteretic comparator [35].…”

Section: Hysteresis-based So Controllersmentioning

confidence: 99%

“…Since the average of a perfectly triangular carrier oscillating within ±V hyst is zero, the dc gain of the hysteretic comparator could theoretically be infinite. In practice, time delay in the comparator (and power stage) ensures that this never happens [33], [35].…”

Section: Carrier Distortionmentioning

confidence: 99%

“…Since the switching frequency of a triangular-carrier hysteretic control system is a parabolic function of duty cycle [16], [33], [35], [37] given quite precisely by…”

Section: Example Prototype Amplifier Designmentioning

confidence: 99%

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Carrier Distortion in Hysteretic Self-Oscillating Class-D Audio Power Amplifiers: Analysis and Optimization

Hoyerby¹,

Andersen

2009

IEEE Trans. Power Electron.

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Abstract-An important distortion mechanism in hysteretic selfoscillating (SO) class-D (switch mode) power amplifiers--carrier distortion--is analyzed and an optimization method is proposed. This mechanism is an issue in any power amplifier application where a high degree of proportionality between input and output is required, such as in audio power amplifiers or xDSL drivers. From an average-mode point of view, carrier distortion is shown to be caused by nonlinear variation of the hysteretic comparator input average voltage with the output average voltage. This easily causes total harmonic distortion figures in excess of 0.1-0.2%, inadequate for high-quality audio applications. Carrier distortion is shown to be minimized when the feedback system is designed to provide a triangular carrier (sliding) signal at the input of a hysteretic comparator. The proposed optimization method is experimentally proven in an audio power amplifier leading to THD figures that are comparable to the state of the art. Experimental hardware is a hysteretic SO bandpass current-mode-controlled single-ended audio power amplifier capable of 45 W into 8 Ω or 80 W into 4 Ω from a ±34 V supply with less than 0.03% THD from 100 Hz to 6.7 kHz. Carrier distortion is shown to account for this limitation in THD performance.

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Section: Hysteresis-based So Controllersmentioning

confidence: 99%

Section: Carrier Distortionmentioning

confidence: 99%

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Carrier Distortion in Hysteretic Self-Oscillating Class-D Audio Power Amplifiers: Analysis and Optimization

Hoyerby¹,

Andersen

2009

IEEE Trans. Power Electron.

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“…Previous works have pioneered the understanding of SM controllers [16][17][18][19][20]. To analyze the closed-loop behavior of the SM controller, we will start with the assumption that the limit-cycle oscillation frequency ω is the product of a free running frequency ω o and a nonlinear function of the duty cycle f(D),…”

Section: A Free Running Frequencymentioning

confidence: 99%

Analysis of DC-DC Conversion for Energy Harvesting Systems Using a Mixed-Signal Sliding-Mode Controller

Guilar

Amirtharajah

Hurst

2007

2007 IEEE Power Electronics Specialists Conference

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Abstract-Increasing efficiencies in electronic devices have opened the door for energy harvesters to power wireless systems by scavenging energy from solar, thermal, or mechanical sources. The design of an efficient power supply that can regulate scavenged energy to produce stable voltages for multiple loads is presented here. To limit energy dissipation and increase the flexibility of the regulator, a discrete-time slidingmode controller is presented. The performance of sliding-mode controllers is hard to predict because their switching frequency and output voltage ripple are dependent on duty cycle and load conditions. An analytical approach for the closed-loop steadystate behavior of a discrete-time sliding-mode controller is presented here. The proposed analytical solution matches measured results to within 4% for duty cycles ranging between 0.1 and 0.9.

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“…A common approach is the "sliding mode" approximation [3] (error/carrier/sliding signal is always zero), which can work very well in some cases [4], but not in others [5]. More accurate, continuoustime approaches use describing function techniques [5], [6], but are only accurate below the switching frequency. While other prior art [8] also accounts for aliasing effects, DC-to-above-f sw accuracy has yet to be demonstrated.…”

Section: Introductionmentioning

confidence: 99%

A versatile discrete-time approach for modeling switch-mode controllers

Risbo

Hoyerby²,

Andersen

2008

2008 IEEE Power Electronics Specialists Conference

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Abstract-This paper presents a universal method for modeling the frequency response of comparators in switchmode controllers. As the main non-linearity in most switchmode controllers, understanding the comparator is the key to understanding the system. Based on discrete-time modeling, the proposed method is demonstrated to allow very precise predictions of comparator frequency response in a variety of control schemes. In the presented work, the modeling method is exemplified for the standard PWM and two different self-oscillating (a.k.a. sliding mode) control schemes. The proposed method is believed by the authors to be the first method that is able to handle these fundamentally different control schemes within a single modeling framework. Experimentally measured output impedance and comparator magnitude responses are compared to the model results. Great accuracy is achieved from DC to frequencies far beyond the switching frequency.

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Describing-function analysis of a ripple regulator with slew-rate limits and time delays

Cited by 15 publications

References 1 publication

Carrier Distortion in Hysteretic Self-Oscillating Class-D Audio Power Amplifiers: Analysis and Optimization

Carrier Distortion in Hysteretic Self-Oscillating Class-D Audio Power Amplifiers: Analysis and Optimization

Analysis of DC-DC Conversion for Energy Harvesting Systems Using a Mixed-Signal Sliding-Mode Controller

A versatile discrete-time approach for modeling switch-mode controllers

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