POWER SUPPLY COMPRISING ACTIVE FILTER CIRCUIT

• Main Author: KUSAKA TOYOYASU
• Format: Patent
• Language: English
• Published: 23.08.2002
• Edition: 7
• Subjects: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC,OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWERSUPPLY SYSTEMS; CONTROL OR REGULATION THEREOF; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUTPOWER; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER; ELECTRICITY; GENERATION

PROBLEM TO BE SOLVED: To take a sufficient countermeasure against harmonic over a wide load range by performing stabilized operation where a sinusoidal input waveform can be sustained for not only a heavy load but also a light load. SOLUTION: A non-harmonic current countermeasure control circuit 14 controls a switching transistor 5 at such a timing as an input current becomes a sine wave current and energy is stored in a choke transformer 4 before being supplied to a load through a diode 7 and a smoothing capacitor 8. A current flowing through the switching transistor is detected by a current transformer 41 and converted into a voltage level being inputted to a comparison circuit 47. On the other hand, an output voltage level being fed to a load is detected and inputted to the comparison circuit. If the output voltage level increases when a detected current quantity is dropped, the non-harmonic current countermeasure control circuit detects the overvoltage of output and turns off the switching transistor forcibly before switching control thereof is stopped.