Patent ID: 6067243
Filing Date: 2000-05-23
Classification: H02M

Abstract:
An AC/AC-DC converter, comprising:a) a first pair of AC switches including first and second AC switches that are connected in series with each other;b) a second pair of AC switches including third and fourth AC switches that are connected in series with each other;c) an AC input across which the first and second pair of AC switches are connected in parallel with each other;d) a third pair of AC switches including fifth and sixth AC switches that are connected in series with each other;e) a first output formed by connecting ends of the fifth and sixth AC switches;f) a transformer having:1) a primary winding connected between (i) a connecting point between the first and second AC switches and (ii) a connecting point between the third and fourth AC switches; and2) a secondary winding across which the third pair of AC switches is connected, the secondary winding having a center point constituting a second output;g) control means for causing alternate operation of (i) the first, third and fifth AC switches and (ii) the second, fourth and sixth AC switches, at a frequency higher than an input waveform;h) first and second capacitors that are connected in series across the AC input, closer to the AC input than are the pairs of AC switches; andi) switching means for switching connection of a terminal of the primary winding between (i) the connecting point between the first and second AC switches and (ii) a connecting point between the first and second capacitors;wherein, when an AC input having a positive phase and a negative phase is applied, an output AC voltage is controlled to have a value in a range from a maximum value of the positive phase, passing through zero, to a maximum value of the negative phase by using pulse phase modulation between the first and second pairs of AC switches and the third pair of AC switches; andwherein, when a DC input is applied, an output DC voltage can be continuously varied to have a value in a range from a maximum value of positive polarity, passing through zero, to a maximum value of negative polarity, by phase controlling a driving pulse phase of the first, second and third pairs of AC switches between 0 and 180 degrees.