Evaluation of losses in a bidirectional wireless power transfer system for electric vehicles

Triviño-Cabrera, Alicia; Cabello-González, José Manuel; Aguado-Sánchez, José Antonio

Evaluation of losses in a bidirectional wireless power transfer system for electric vehicles

Triviño-Cabrera, Alicia,Cabello-González, José Manuel,Aguado-Sánchez, José Antonio

Published: 2017-06-01
Repository: riuma.uma.es
Language: en

Abstract

Inductively power transfer systems are becoming increasingly popular in modern applications like electric vehicles. In order to make this technology attractive, its transfer efficiency must be considerably high. Most works in the literature define the efficiency of the wireless charger as the one associated to the inverter, the coupled coils and the compensation networks. Therefore, they usually omit the study of the losses occurring in other parts of the system such as in the secondary rectifier. This paper evaluates the losses in a complete wireless charger, built and designed to provide V2G functionalities. The experimental evaluation based on the waveform analysis is contrasted with a theoretical model, which relies on the non-idealities of the components. The evaluation reveals that measurement error greatly impact on the power losses derived by the two approaches

Full text

Losses computation Model based on nonidealities Analysis of waveforms It is important to characterize the efficiency of aCOMPLETE BIDIRECTIONAL wireless charger for Electric Vehicles (EV) operating at 85 kHz. We propose an ANALYTILICAL MODEL to predict LOSSES based on the NON-IDEALITIES of the components. INTRODUCTION BIDIRECTIONAL WIRELESS CHARGER EXPERIMENTAL VALIDATION Coils Matching Inverter Rectifier CONCLUSIONS This paper presents a model to predict the losses in a bidirectional ICPT wireless charger for EV: 1. Supported by the non-idealities of the components. 2. Verified with the analysis of waveforms. For the comparison, a prototype according to the SAE TIR J2954 has been built. The results present small differences between both approaches, which are assumed to be due to measurement errors. Scheme Department of Electrical Engineering Universidad de Málaga, Spain A. Triviño, J. M. González-González, J. A. Aguado at[email protected] Evaluation of Losses in a Bidirectional Wireless Power Transfer System for Electric Vehicles Prototype The switching frequency is 85 kHz as recommended by SAE TIR J2954. Supported by square coils separated 20 cm. The power converters are composed of CREE C2M0080120D SiC MOSFETs. Specifications and parameters: Electrical signals measured in the prototype: Losses computation (waveform analysis and model): Comparison between both methods: total losses Charger specifications TX-RX parameters (prototype values) Output 3.7 kW 300 V L1[µH] 240.5 fs [kHz] 85 L2[µH] 230.6 Coils geometry C1[nF] 14.3 Primary coil [m2]0.75 x 0.75 C2[nF] 15.6 Secondary coil [m2]0.5 x 0.5 RL1 [mΩ] 196 C2M0080120D SiC MOSFET RL2 [mΩ] 143 𝑅𝑑[mΩ] 40 RC1 [mΩ] 67 𝑉𝑡ℎ [V] 0.98 RC2 [mΩ] 52 𝐶𝑜𝑠𝑠 [pF] 80 M [µH] 54.5 𝑅𝑑𝑠 [mΩ] 80 K=M (L 1L2)1/2 0.231 Electrical signals Charge mode Discharge mode 𝑉𝑖𝑛𝑣_𝑖𝑛𝑝𝑢𝑡 [V] 288 298 𝑉𝑖𝑛𝑣_𝑜𝑢𝑡𝑝𝑢𝑡 [V] 290 293 𝐼𝑖𝑛𝑣_𝑖𝑛𝑝𝑢𝑡 [A] 12.56 4.56 𝐼𝑖𝑛𝑣_𝑜𝑢𝑡𝑝𝑢𝑡 [A] 13.78 5.14 𝑉𝑟𝑒𝑐_𝑖𝑛𝑝𝑢𝑡 [V] 285 247 𝑉𝑟𝑒𝑐_𝑜𝑢𝑡𝑝𝑢𝑡 [V] 288 250 𝐼𝑟𝑒𝑐_𝑖𝑛𝑝𝑢𝑡 [A] 13.74 6.02 𝐼𝑟𝑒𝑐_𝑜𝑢𝑡𝑝𝑢𝑡 [A] 12.16 5.3 Electrical signals Charge mode Discharge mode 𝑳𝒊𝒏𝒗 𝒄𝒉 [W] 20 𝑳𝒊𝒏𝒗 𝒅𝒊𝒔 [W] 7 𝑳𝒓𝒆𝒄 𝒄𝒉 [W] 23 𝑳𝒓𝒆𝒄 𝒅𝒊𝒔 [W] 27 𝑳𝒄𝒐𝒏,𝒊𝒏𝒗 [W] 25 𝑳𝒄𝒐𝒏,𝒊𝒏𝒗 [W] 3.3 𝑳𝒔𝒘,𝒊𝒏𝒗 [W] 1𝑳𝒔𝒘,𝒊𝒏𝒗 [W] 1 𝑳𝒄𝒐𝒏,𝒓𝒆𝒄 [W] 34 𝑳𝒄𝒐𝒏,𝒓𝒆𝒄 [W] 15 𝑳𝒄𝒐𝒊𝒍𝒔 [W] 64 𝑳𝒄𝒐𝒊𝒍𝒔 [W] 11 𝑳𝒎𝒂𝒕𝒄𝒉 [W] 23 𝑳𝒎𝒂𝒕𝒄𝒉 [W] 4 THEORETICAL COMPUTATION OF LOSSES Waveform analysis Model based on non-idealities 𝐂𝐡𝐚𝐫𝐠𝐢𝐧𝐠 130 W 147 W 𝐃𝐢𝐬𝐜𝐡𝐚𝐫𝐠𝐢𝐧𝐠 49 W 34 W 𝐿𝑐𝑜𝑖𝑙𝑠 = 𝑅𝐿1 ∙መ 𝐼1 2+ 𝑅𝐿2 ∙መ 𝐼2 2 𝐿𝑚𝑎𝑡𝑐ℎ = 𝑅𝐶1 ∗መ 𝐼1 2+ 𝑅𝐶2 ∗መ 𝐼2 2 𝐿𝑐𝑜𝑛,𝑟𝑒𝑐 = 2 · 𝑅𝑑መ 𝐼𝑟𝑒𝑐 2+ 2 · 𝑉𝑡ℎ ·መ 𝐼𝑟𝑒𝑐 𝐿𝑐𝑜𝑛,𝑖𝑛𝑣 = 2 · 𝑅𝑑𝑠 ∙መ 𝐼1 2 𝐿𝑠𝑤,𝑖𝑛𝑣 ≅𝐿𝐶𝑜𝑠𝑠 =1 2𝑓 𝑠𝐶𝑜𝑠𝑠𝑉𝑑𝑠 2 Non-idealitiesWaveform analysis 𝐿𝑖𝑛𝑣 𝑐ℎ = 𝑃𝑖𝑛𝑣_𝑖𝑛𝑝𝑢𝑡 𝑐ℎ − 𝑃𝑖𝑛𝑣_𝑜𝑢𝑡𝑝𝑢𝑡 𝑐ℎ 𝐿𝑟𝑒𝑐 𝑐ℎ = 𝑃𝑟𝑒𝑐_𝑖𝑛𝑝𝑢𝑡 𝑐ℎ − 𝑃𝑟𝑒𝑐_𝑜𝑢𝑡𝑝𝑢𝑡 𝑐ℎ 𝐿𝑐𝑜𝑖𝑙𝑠 𝑐ℎ + 𝐿𝑚𝑎𝑡𝑐ℎ 𝑐ℎ = =𝑃𝑖𝑛𝑣_𝑜𝑢𝑡𝑝𝑢𝑡 𝑐ℎ − 𝑃rec_𝑖𝑛𝑝𝑢𝑡 𝑐ℎ