Contactless power-feed equipment

Contactless power-feed equipment comprising an induction line placed along a travel path of a movable body and fed with an AC current, or an induction coil that is disposed at a predetermined position for holding a device and fed with an AC current,

• the movable body including a power-receiving coil on which an electromotive force is induced by a magnetic flux generated on the induction line, or the device including a power-receiving coil on which an electromotive force is induced by a magnetic flux generated on the induction coil,
• the contactless power-feed equipment comprising:
• a DC power-supply device that supplies a DC current;
• a DC choke having one end connected to a positive output terminal of the DC power-supply device;
• an insulating transformer including a center-tapped primary coil having a center tap connected to another end of the DC choke and a secondary coil connected to one of the induction line and the induction coil;
• a resonance capacitor that is connected in parallel with the secondary coil and forms a resonance circuit with one of the induction line and the induction coil at a predetermined frequency;
• a first switching element including a transistor connected between one end of the center-tapped primary coil and a negative output terminal of the DC power-supply device;
• a second switching element including a transistor connected between another end of the center-tapped primary coil and the negative output terminal of the DC power-supply device;
• a first constant current diode having an anode connected to the one end of the center-tapped primary coil;
• a first Zener diode having a cathode connected to a cathode of the first constant current diode and a base of the transistor forming the second switching element and an anode connected to the negative output terminal of the DC power-supply device;
• a second constant current diode having an anode connected to the other end of the center-tapped primary coil;
• and
• a second Zener diode having a cathode connected to a cathode of the second constant current diode and a base of the transistor forming the first switching element and an anode connected to the negative output terminal of the DC power-supply device,
• wherein a current passing through the first constant current diode and the first Zener diode from the one end of the center-tapped primary coil drives the transistor forming the second switching element, a charge of the base of the second transistor at this point is discharged to the one end of the primary coil, the second transistor is completely placed into a non-conducting state, a current passing through the second constant current diode and the second Zener diode from the other end of the center-tapped primary coil drives the transistor forming the first switching element, a charge of the base of the first transistor at this point is discharged to the other end of the primary coil, and the first transistor is placed into a non-conducting state.