Delta-sigma modulators for modular multilevel converters

Jiang, Hao; Venkataramanan, G.

doi:10.1109/ecce.2017.8095964

Cited by 3 publications

(3 citation statements)

References 12 publications

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“…Proper choice of the carrier sequence can furthermore exploit the opportunities of the parallel mode for charge balancing across modules as well as to reduce conduction loss [150,152]. Other modulation techniques are possible and described in the literature but are designed for the typically notably slower switching rates and output bandwidth (typically < 1,000 Hz) as common in power conversion applications and therefore often generate a substantially higher computational burden or lower-frequency distortion [153][154][155][156][157][158][159].…”

Section: + +mentioning

confidence: 99%

Transcranial Magnetic Stimulation Tech-nology with Freely Adjustable Pulse Shape and Sequence

Li¹,

Zhang²,

Peterchev³

et al. 2023

Preprint

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The temporal shape of a pulse in transcranial magnetic stimulation (TMS) influences which neuron populations are activated preferentially as well as the strength and even direction of neuromodulation effects. Furthermore, various pulse shapes differ in their efﬁciency, coil heating, sensory perception, and clicking sound. However, the available TMS pulse shape repertoire is still very limited to a few biphasic, monophasic, and polyphasic pulses with sinusoidal or near-rectangular shapes. Monophasic pulses, though found to be more selective and stronger in neuromodulation, are generated inefﬁciently and therefore only available in simple low-frequency repetitive protocols. Despite a strong interest to exploit the temporal effects of TMS pulse shapes and pulse sequences, waveform control is relatively inflexible and only possible parametrically within certain limits. Previously proposed approaches for flexible pulse shape control, such as through power electronic inverters, have signiﬁcant limitations: The semiconductor switches can fail under the immense electrical stress associated with free pulse shaping, and most conventional power inverter topologies are incapable of generating smooth electric ﬁelds or existing pulse shapes. Leveraging intensive preliminary work on modular power electronics, we present a modular pulse synthesizer (MPS) technology that can, for the ﬁrst time, flexibly generate high-power TMS pulses (one-side peak ~ 4,000 V, ~ 8,000 A) with user-deﬁned electric ﬁeld shape as well as rapid sequences of pulses with high output quality. The circuit topology breaks the problem of simultaneous high power and switching speed into smaller, manageable portions, distributed across several identical modules. In consequence, MPS TMS can use semiconductor devices with voltage and current ratings lower than the overall pulse voltage and distribute the overall switching of several hundred kilohertz among multiple transistors. MPS TMS can synthesize practically any pulse shape, including conventional ones, with ﬁne quantization of the induced electric ﬁeld (≤ 17% granularity without modulation and ~300 kHz bandwidth). Moreover, the technology allows optional symmetric differential coil driving so that the average electric potential of the coil, in contrast to conventional TMS devices, stays constant to prevent capacitive artifacts in sensitive recording ampliﬁers, such as electroencephalography (EEG). MPS TMS can enable the optimization of stimulation paradigms for more sophisticated probing of brain function as well as stronger and more selective neuromodulation, further expanding the parameter space available to users.

show abstract

Section: + +mentioning

confidence: 99%

Transcranial Magnetic Stimulation Tech-nology with Freely Adjustable Pulse Shape and Sequence

Li¹,

Zhang²,

Peterchev³

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

“…Proper choice of the carrier sequence can furthermore exploit the opportunities of the parallel mode for charge balancing across modules as well as to reduce conduction loss [147,149]. Other modulation techniques are possible and described in the literature but are designed for the typically notably slower switching rates and output bandwidth (typically <1000 Hz) as common in power conversion applications and therefore often generate a substantially higher computational burden or lower-frequency distortion [150][151][152][153][154][155][156].…”

Section: Control and Balancingmentioning

confidence: 99%

Modular pulse synthesizer for transcranial magnetic stimulation with fully adjustable pulse shape and sequence

Zhang

Peterchev

et al. 2022

J. Neural Eng.

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The temporal shape of a pulse in transcranial magnetic stimulation (TMS) influences which neuron populations are activated preferentially as well as the strength and even direction of neuromodulation effects. Furthermore, various pulse shapes differ in their efﬁciency, coil heating, sensory perception, and clicking sound. However, the available TMS pulse shape repertoire is still very limited to a few biphasic, monophasic, and polyphasic pulses with sinusoidal or near-rectangular shapes. Monophasic pulses, though found to be more selective and stronger in neuromodulation, are generated inefﬁciently and therefore only available in simple low-frequency repetitive protocols. Despite a strong interest to exploit the temporal effects of TMS pulse shapes and pulse sequences, waveform control is relatively inflexible and only possible parametrically within certain limits. Previously proposed approaches for flexible pulse shape control, such as through power electronic inverters, have signiﬁcant limitations: Existing semiconductor switches can fail under the immense electrical stress associated with free pulse shaping, and most conventional power inverter topologies are incapable of generating smooth electric ﬁelds or existing pulse shapes. Leveraging intensive preliminary work on modular power electronics, we present a modular pulse synthesizer (MPS) technology that can, for the ﬁrst time, flexibly generate high-power TMS pulses (~ 4,000 V, ~ 8,000 A) with user-deﬁned electric ﬁeld shape as well as rapid sequences of pulses with high output quality. The circuit topology breaks the problem of simultaneous high power and switching speed into smaller, manageable portions, distributed across several identical modules. In consequence, MPS TMS can use semiconductor devices with voltage and current ratings lower than the overall pulse voltage and distribute the overall switching of several hundred kilohertz among multiple transistors. MPS TMS can synthesize practically any pulse shape, including conventional ones, with ﬁne quantization of the induced electric ﬁeld. Moreover, the technology allows optional symmetric differential coil driving so that the average electric potential of the coil, in contrast to conventional TMS devices, stays constant to prevent capacitive artifacts in sensitive recording ampliﬁers, such as electroencephalography (EEG). MPS TMS can enable the optimization of stimulation paradigms for more sophisticated probing of brain function as well as stronger and more selective neuromodulation, further expanding the parameter space available to users.

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“…Because all the SM are identical, increasing the number of levels does not increase the power electronics by very much, but it does increase the complexity of the control due to the high number of control signals to be handled. Systems to reduce the complexity of the communications are currently still under study [11].…”

Section: Introductionmentioning

confidence: 99%

Calculation of the number of modules and the switching frequency of a modular multilevel converter using near level control

Martinez-Rodrigo

Lucas

Pablo

et al. 2018

Electric Power Systems Research

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Delta-sigma modulators for modular multilevel converters

Cited by 3 publications

References 12 publications

Transcranial Magnetic Stimulation Tech-nology with Freely Adjustable Pulse Shape and Sequence

Transcranial Magnetic Stimulation Tech-nology with Freely Adjustable Pulse Shape and Sequence

Modular pulse synthesizer for transcranial magnetic stimulation with fully adjustable pulse shape and sequence

Calculation of the number of modules and the switching frequency of a modular multilevel converter using near level control

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