This paper addresses the H 2 performance problem for singularly perturbed switched linear systems in continuous-time. We propose a new and unified approach for stability analysis and norm computation for singularly perturbed LTI systems and generalize it to the case of singularly perturbed switched linear systems to obtain numerically well conditioned conditions for the design of a state-switching control. Such a switching strategy guarantees that the closed-loop switched system is globally asymptotically stable for sufficiently small values of the perturbation parameter and provides an upper bound to an H 2 performance index. We provide a comparison with existing methods. © 2012 IFAC. 228233IFAC Technical Committee on Discrete Event and Hybrid Systems,Netherlands Organization for Scientific Research (NWO),ASML,DEMCONBoyd, S.P., El Ghaoui, L., Feron, E., Balakrishnan, V., (1994) LMI in System and Control Theory, , SIAM, PhiladelphiaCao, L., Schwartz, H.M., Complementary results on the stability bounds of singularly perturbed systems (2004) IEEE Trans. Automat. Control, 49, pp. 2017-2021Chow, J., Kokotovic, P., A decomposition of nearoptimum regulators for systems with slow and fast modes (1976) IEEE Trans. on Automat. Control, 21 (5), pp. 701-705El Hachemi, F., Sigalotti, M., Daafouz, J., Stability of singularly perturbed switched systems (2011) Proceedings of IEEE American Control Conference, pp. 4061-4066. , San Francisco, USAGarcia, G., Daafouz, J., Bernussou, J., The infinite time near optimal decentralized regulator problem for singularly perturbed systems: A convex optimization approach (2002) Automatica, 38 (8), pp. 1397-1406Geromel, J.C., Colaneri, P., Stability and stabilization of continuous-time switched linear systems (2006) SIAM J. Contr. Optim., 45 (5), pp. 1915-1930Geromel, J.C., Colaneri, P., Bolzern, P., Dynamic output feedback feedback control of switched linear systems (2008) IEEE Trans. Automat. Control, 53, pp. 720-733Heck, B.S., Haddad, A.H., Singular perturbation in piecewise-linear systems (1989) IEEE Trans. Automat. Control, 34 (1), pp. 87-90Kokotovic, P.V., Khalil, H.K., O'reilly, J., (1986) Singular Perturbation Methods in Control: Analysis and Design, , Academic Press Inc., LondonLiberzon, D., (2003) Switching in Systems and Control, , Birkhäuser Boston Inc., Boston, MAMalloci, I., Daafouz, J., Iung, C., Bonidal, R., Szczepanski, P., Switched system modeling and robust steering control of the tail end phase in a hot strip mill (2009) Nonlinear Analysis: Hybrid Systems, 3 (3), pp. 239-250. , AugustMalloci, I., Daafouz, J., Iung, C., Stabilization of continuous-time singularly perturbed switched systems (2009) 48th IEEE Conference on Decision and Control, pp. 6371-6376. , Shanghai, ChinaMalloci, I., Daafouz, J., Iung, C., Stability and stabilization of two time scale switched systems in discrete time (2010) IEEE Trans. Automat. Control, 55 (6), pp. 1434-1438Naidu, D.S., Singular perturbations and time scales in control theory and applications: An overview (2002) Dynamics of Continuous, Discrete and Impulsive Systems. Series B: Applciations and Algorithms, 9, pp. 223-278Sanfelice, R.G., Teel, A.R., On singular perturbations due to fast actuators in hybrid control systems (2011) Automatica, 47 (4), pp. 692-701Shorten, R., Wirth, F., Mason, O., Wulff, K., King, C., Stability criteria for switched and hybrid systems (2007) SIAM Review, 49 (4), pp. 545-592