Patent ID: 6172882
Filing Date: 2001-01-09
Classification: H02M

Abstract:
In a partial resonance PWM converter including: a main switch circuit composed of first and second main switch devices, said main switch circuit being connected in parallel with a DC power supply; diodes respectively connected in parallel with each of said main switch devices in the opposite direction of a polarity of said DC power supply; an output circuit located at a juncture of said main switch devices;an auxiliary switch circuit composed of first and second auxiliary switch devices, said auxiliary switch circuit being connected in parallel with said DC power supply; diodes respectively connected in parallel with each of said auxiliary switch devices in the opposite direction of the polarity of said DC power supply; anda series resonance circuit composed of a capacitor and an inductor, said series resonance circuit being inserted between the juncture of said first and second main switch devices and a juncture of said first and second auxiliary switch devices;wherein said first and second main switches are alternatively switched to output AC or DC power, said converter comprising,control means for controlling a switching timing to make said auxiliary switch device turn on just before said main switch device is switched, and, at least in the main switch devices, to make said main switch device turn off when said diode connected in parallel with each of said main switch devices is turned nearly to ON condition or during ON condition of said diode, whereby said main switch device can be turned off at zero current, and to make one of said main switch devices turn on during said first and second main switch devices is in OFF condition and a load current passes through said series resonance circuit, whereby a current passing through said main switch device is increased from zero with having a particular inclination so that said main switch device can be turned on at zero current.