Converter circuit and motor drive control apparatus, air-conditioner, refrigerator, and induction heating cooker provided with the circuit

摘要

A converter circuit comprises: a first step-up converter (3a) including a rectifier (2), a step-up reactor (4a), a switching element (5a), and a reverse current prevention element (6a); a second step-up converter (3b) having a step-up reactor (4b), a switching element (5b), and a reverse current prevention element (6b) and being connected in parallel with the first step-up converter (3a); switching control means (7) configured to control switching elements (5a) and (5b); and a smoothing capacitor (8) that is provided at the output of the step-up converters (3a) and (3b). The switching control means (7) switches the current mode of the current flowing through the step-up reactors (4a) and (4b) into a critical mode and a discontinuous mode based on the switching frequencies of the switching elements (5a) and (5b).