Patent ID: 6754090
Filing Date: 2004-06-22
Classification: H02M

Abstract:
A power supply apparatus, comprising:an input-side rectifier adapted for rectifying commercial AC power; a DC-to-high-frequency converter for converting an output of said input-side rectifier to a high-frequency signal; a transformer for transforming a high-frequency signal from said DC-to-high-frequency converter and developing a high-frequency transformer output signal; a first output-side rectifier connected between said transformer and a load for so rectifying said high-frequency transformer output signal as to cause a positive current to flow in said load when said high-frequency transformer output signal is of positive polarity; a second output-side rectifier connected in parallel with said first output-side rectifier for so rectifying said high-frequency transformer output signal as to cause a negative current to flow in said load when said high-frequency transformer output signal is of negative polarity; a first semiconductor switching device connected in series with said first output-side rectifier; a second semiconductor switching device connected in series with said second output-side rectifier; and a switching device controller for supplying said first and second semiconductor switching devices with such semiconductor switching device control signals as to render said first semiconductor switching device alternately conductive and nonconductive at a frequency lower than that of said high-frequency signal and to render said second semiconductor switching device alternately conductive and nonconductive in a complementary manner to said first semiconductor switching device; said DC-to-high-frequency converter comprising converter semiconductor switching means, conversion control means for rendering said converter semiconductor switching means alternately conductive and nonconductive, and a reference signal source providing a reference signal assuming, in synchronization with said semiconductor switching device control signals, reference values for positive and negative currents when said first and second semiconductor switching devices are conductive, respectively, said reference value of said reference signal for negative current being larger than said reference value for positive current; said conversion control means supplying said converter semiconductor switching means with such a conversion control signal as to make a difference between said positive current flowing through said load and said reference value for positive current zero and to make a difference between said negative current flowing through said load and said reference value for negative current zero.