Recently I've bee studying Robert W. Erickson's Fundamentals of Power Electronics. At the chapter of resonant conversion, the book says that "The circulating tank currents are independent, or weakly dependent on, the load current, and lead to poor efficiency at light load, which is confusing for me. According to my understanding, the effective resistance Re of the dc-dc converter increases at light load. Therefore, the peak magnitude of the tank current would decrease, which conflicts to what the author states. Could someone tell me where I'm wrong?