Artikuluak-Ingeniaritzahttps://hdl.handle.net/20.500.11984/4782024-05-27T22:12:15Z2024-05-27T22:12:15ZError estimation in current noisy quantum computersAseginolaza, UnaiBorge, Juanhttps://hdl.handle.net/20.500.11984/64232024-05-24T11:17:34Z2024-01-01T00:00:00ZError estimation in current noisy quantum computers
Aseginolaza, Unai; Borge, Juan
One of the main important features of the noisy intermediate-scale quantum (NISQ) era is the correct evaluation and consideration of errors. In this paper, we analyse the main sources of errors in current (IBM) quantum computers and we present a useful tool (TED-qc) designed to facilitate the total error probability expected for any quantum circuit. We propose this total error probability as the best way to estimate a lower bound for the fidelity in the NISQ era, avoiding the necessity of comparing the quantum calculations with any classical one. In order to contrast the robustness of our tool we compute the total error probability that may occur in three different quantum models: 1) the Ising model, 2) the Quantum-Phase Estimation (QPE), and 3) the Groverâ€™s algorithm. For each model, the main quantities of interest are computed and benchmarked against the reference simulatorâ€™s results as a function of the error probability for a representative and statistically significant sample size. The analysis is satisfactory in more than the of the cases. In addition, we study how error mitigation techniques are able to eliminate the noise induced during the measurement. These results have been calculated for the IBM quantum computers, but both the tool and the analysis can be easily extended to any other quantum computer.
2024-01-01T00:00:00ZA Methodology to Determine the Effect of a Novel Modulation in the Reliability of an Automotive DC-Link CapacitorCABEZUELO ROMERO, DAVIDhttps://hdl.handle.net/20.500.11984/64152024-05-24T11:22:01Z2020-01-01T00:00:00ZA Methodology to Determine the Effect of a Novel Modulation in the Reliability of an Automotive DC-Link Capacitor
CABEZUELO ROMERO, DAVID
Switched Reluctance Machines (SRM) are considered promising rare-earth free candidates for the next generation electrified vehicles. One of the main drawback of this technology is the need of a large DC-link capacitor to balance the energy transferred back and forth between the DC source and the SRM. There are interesting novel modulations to reduce the current of the DC bus, focused on the capacitor size and cost reduction but leaving aside the thermal analysis and lifetime improvements. Carrying out the required dynamic multi-physics simulations for that purpose becomes highly time consuming and complex, especially when standardized or real driving conditions are needed to be taken into account. This article proposes a simulation methodology, simple to implement and with a relatively low computational cost, to estimate the lifetime of an automotive DC-link capacitor, with the current load it delivers as the starting point. The presented methodology has also been used to validate a novel SRM modulation technique and to compare it, in terms of reliability, with the conventional torque sharing function.
2020-01-01T00:00:00ZSynchronized Switching Modulation to Reduce the DC-Link Current in SRM DrivesCABEZUELO ROMERO, DAVIDhttps://hdl.handle.net/20.500.11984/64142024-05-24T11:22:00Z2020-01-01T00:00:00ZSynchronized Switching Modulation to Reduce the DC-Link Current in SRM Drives
CABEZUELO ROMERO, DAVID
Switched Reluctance Machines (SRM) are emerging as a possible alternative in terms of cost and supply stability to rare earth based electric vehicle traction systems. However, because of the huge amounts of energy stored and transferred back and forth between the DC source and the SRM, large DC-link capacitors must be used as buffers, which increases overall costs and size. This paper proposes a novel modulation technique which forces the exchange of energy between phases while decreasing the energy transfer between the DC bus and the SRM. This means lower DC bus currents (capacitor size and cost reduction) and lower Joule-effect conduction losses (better efficiency). The proposed modulation has been validated experimentally in a test bench and compared with the conventional torque-sharing function.
2020-01-01T00:00:00ZA method to extract lumped thermal networks of capacitors for reliability oriented designCABEZUELO ROMERO, DAVIDhttps://hdl.handle.net/20.500.11984/64132024-05-24T11:21:59Z2020-01-01T00:00:00ZA method to extract lumped thermal networks of capacitors for reliability oriented design
CABEZUELO ROMERO, DAVID
In this work we propose a procedure based on finite element simulations to compute a lumped-parameter thermal model of capacitors. The extracted Foster or Cauer network coupled to the electrical model can be useful to evaluate the temperature of capacitors in circuit simulators as SPICE or Simulink. In this way, it is possible to evaluate the expected maximum operative temperature of the capacitor embedded in a circuit before its real application, avoiding unexpected failures since the prototyping stage. Here, we describe the workflow of the method and, finally, the proposed approach will be used for designing snubber capacitors for medium power (60 kW) high frequency AC/AC converter.
2020-01-01T00:00:00Z