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Proposal of Potted Inductor with Enhanced Thermal Transfer for High Power Boost Converter in HEVs

  • You, Bong-Gi ;
  • Ko, Jeong-Min ;
  • Kim, Jun-Hyung ;
  • Lee, Byoung-Kuk
  • Received : 2014.07.22
  • Accepted : 2015.01.29
  • Published : 2015.05.01

Abstract

A hybrid electric vehicle (HEV) powertrain has more than one energy source including a high-voltage electric battery. However, for a high voltage electric battery, the average current is relatively low for a given power level. Introduced to increase the voltage of a HEV battery, a compact, high-efficiency boost converter, sometimes called a step-up converter, is a dc-dc converter with an output voltage greater than its input voltage. The inductor occupies more than 30% of the total converter volume making it difficult to get high power density. The inductor should have the characteristics of good thermal stability, low weight, low losses and low EMI. In this paper, Mega Flux® was selected as the core material among potential core candidates. Different structured inductors with Mega Flux® were fabricated to compare the performance between the conventional air cooled and proposed potting structure. The proposed inductor has reduced the weight by 75% from 8.8kg to 2.18kg and the power density was increased from 15.6W/cc to 56.4W/cc compared with conventional inductor. To optimize the performance of proposed inductor, the potting materials with various thermal conductivities were investigated. Silicone with alumina was chosen as potting materials due to the high thermo-stable properties. The proposed inductors used potting material with thermal conductivities of 0.7W/m·K, 1.0W/m·K and 1.6W/m·K to analyze the thermal performance. Simulations of the proposed inductor were fulfilled in terms of magnetic flux saturation, leakage flux and temperature rise. The temperature rise and power efficiency were measured with the 40kW boost converter. Experimental results show that the proposed inductor reached the temperature saturation of 107℃ in 20 minutes. On the other hand, the temperature of conventional inductor rose by 138℃ without saturation. And the effect of thermal conductivity was verified as the highest thermal conductivity of potting materials leads to the lowest temperature saturations.

Keywords

Mega Flux®;Potted structure inductor;Boost converter of HEV;High current inductor;Potting material.

References

  1. T. E. Salem, D. P. Urciuoli, V. Lubomirsky, G. K. Ovrebo, “Design considerations for high power inductors in dc-dc converters,” 22nd Annual IEEE Applied Power Electronics Conference and Exposition, pp. 1258-1263, Feb/Mar 2007.
  2. Ali Emadi et.al, “Topological overview of hybrid electric and fuel cell vehicular power system archiectures and configurations”, IEEE Trans. on Vehicular Technology, vol. 54, no. 3, May 2005, pp. 763-770. https://doi.org/10.1109/TVT.2005.847445
  3. A. W. Lotfi and M. A. Wilkowski, “Issues and advances in high-frequency magnetics for switching power supplies,” Proc. IEEE, vol. 89, pp. 833-845, June 2001. https://doi.org/10.1109/5.931473
  4. B.G. You, J.S. Kim, B.K. Lee, G.B. Choi, D.W. Yoo, “Optimization of powder core inductors of buck-boost converters for Hybrid Electric Vehicles: VPPC, 2009, p.730-735.
  5. A.W. Lotfi and M.A. Wilkowski, “Issues and advances in high-frequency magnetics for switching power supplies,” Proc. IEEE, vol. 89, pp. 833-845, June 2001. https://doi.org/10.1109/5.931473
  6. S. Mulder, “Power ferrite loss formulas for transformer design”, Power Conversion & Intelligent Motion, vol. 21, no. 7, pp. 22-31, July 1995.
  7. Ali Emadi et al., “Topological overview of hybrid electric and fuel cell vehicular power system architectures and configurations”, IEEE Trans. on Vehicular Technology, vol. 54, no. 3, pp. 763-770, May 2005. https://doi.org/10.1109/TVT.2005.847445
  8. F. Liffran, “A procedure to optimize the inductor design in boost PFC applications,” 13th Power Electronics and Motion Control Conference, pp. 409-416, Sept., 2008.

Cited by

  1. Design and Implementation of Modified Current Source Based Hybrid DC - DC Converters for Electric Vehicle Applications vol.17, pp.2, 2016, https://doi.org/10.4313/TEEM.2016.17.2.57