Model-based control of a dual active bridge for bidirectional feeding of DEAP transducers

Maas, Jürgen; Hoffstadt, Thorben

doi:10.1109/aim.2014.6878097

Cited by 7 publications

(6 citation statements)

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“…Due to the capacitive behavior of a DEAP transducer a current feeding is required. Amongst others, the dual active bridge [27] or the flyback converter [28,29] are advantageous topologies that provide voltage-fed current converter functionality. Assuming the series resistance R s to be almost constant, the averaged feeding power in (10) can be rewritten using Krichhoff's voltage law under consideration of the electrical circuit in figure 2:…”

Section: Mechanical Domainmentioning

confidence: 99%

Analytical modeling and optimization of DEAP-based multilayer stack-transducers

Hoffstadt

Maas

2015

Smart Mater. Struct.

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Transducers based on dielectric electroactive polymers (DEAP) use electrostatic pressure to convert electrical into mechanical energy or vice versa. To scale up the actuation or the energy gain, multilayer transducers like DEAP stack transducers are appropriate. Within this contribution, a model of such a stack transducer is derived and experimentally validated. The model is based on a multi-domain approach to describe the mechanical dynamics and the electrical behavior of the DEAP. Since these two domains influence each other they are coupled afterwards by a novel approach using interchanging power flows. To parametrize this model, tensile and compression tests for different polymer materials were performed under static and transient considerations. The results of these experiments show that the parameters obtained from the tensile test sufficiently describe the compression mode and can therefore be used for the model. Based on this transducer model the overall energy and the different parts of the multi-domain are analytically determined for arbitrary operating points. These expressions for the energies are finally used to optimize well-defined coupling coefficients, by which a maximum part of the electrical input energy is converted to mechanical energy, especially mechanical work.

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Section: Mechanical Domainmentioning

confidence: 99%

Analytical modeling and optimization of DEAP-based multilayer stack-transducers

Hoffstadt

Maas

2015

Smart Mater. Struct.

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“…The second unknown phase φ x l can be calculated as well, but is not relevant for the parameter identification. The polymer capacitance C p can be directly calculated by replacing the sinusoidal term in equation ( 6) by equation (17). In order to calculate the electrode and polymer resistance R e and R p , the arcsine function can be applied to equation (17), which allows a calculation of the phase φ x k .…”

Section: Identification Algorithmsmentioning

confidence: 99%

“…The resulting currents ′ i L and i DE can be fully described with the two characteristic values ′ i L,1 and ′ i L max , at the switching points in time t 0 and t 1 . They can be calculated on the basis of the fact that the current ′ i L has no mean value and the output voltage v DE is almost constant during one switching period T s [17]:…”

Section: Driving Power Electronicsmentioning

confidence: 99%

“…These higher harmonics can be used for the parameter identification instead of the additional voltage v sensor in figure 3(b). On calculating the mean value I DE,0 , it results as a function of the phase shift φ [17]:…”

Section: Driving Power Electronicsmentioning

confidence: 99%

“…Therefore, direct control of the mean value I DE,0 can be realized using the phase shift φ as the control variable [17]. The alternating components can be calculated as well, using the Fourier series in equation ( 27), considering the switching period T S :…”

Section: Driving Power Electronicsmentioning

confidence: 99%

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Online identification algorithms for integrated dielectric electroactive polymer sensors and self-sensing concepts

Hoffstadt¹,

Griese²,

Maas³

2014

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Transducers based on dielectric electroactive polymers (DEAP) use electrostatic pressure to convert electric energy into strain energy or vice versa. Besides this, they are also designed for sensor applications in monitoring the actual stretch state on the basis of the deformation dependent capacitive-resistive behavior of the DEAP. In order to enable an efficient and proper closed loop control operation of these transducers, e.g. in positioning or energy harvesting applications, on the one hand, sensors based on DEAP material can be integrated into the transducers and evaluated externally, and on the other hand, the transducer itself can be used as a sensor, also in terms of self-sensing. For this purpose the characteristic electrical behavior of the transducer has to be evaluated in order to determine the mechanical state. Also, adequate online identification algorithms with sufficient accuracy and dynamics are required, independent from the sensor concept utilized, in order to determine the electrical DEAP parameters in real time. Therefore, in this contribution, algorithms are developed in the frequency domain for identifications of the capacitance as well as the electrode and polymer resistance of a DEAP, which are validated by measurements. These algorithms are designed for self-sensing applications, especially if the power electronics utilized is operated at a constant switching frequency, and parasitic harmonic oscillations are induced besides the desired DC value. These oscillations can be used for the online identification, so an additional superimposed excitation is no longer necessary. For this purpose a dual active bridge (DAB) is introduced to drive the DEAP transducer. The capabilities of the real-time identification algorithm in combination with the DAB are presented in detail and discussed, finally.

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