Apparatus for non-contacting feeding of high frequency power

• US 5,592,367 A
• Filed: 10/06/1994
• Issued: 01/07/1997
• Est. Priority Date: 06/06/1994
• Status: Expired due to Term

• Current Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Original Assignee: Nippon Electric Industry Company Limited
• Inventors: Sakamoto, Hiroshi, Sugimori, Katsunori
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): Riley, Shawn
• Application Number:
  US08/319,368
• Time in Patent Office: 824 Days
• Field of Search: 363/17, 363/136, 363/22, 363/139, 363/24, 363/25, 363/91, 363/98, 323/310
• US Class Current: 363/17
• CPC Class Codes: H02M 7/53832 in a push-pull arrangement

Abstract

The apparatus for non-contacting feeding of a high frequency power according to the present invention comprises a double voltage full-wave rectifier circuit which converts an AC input into a DC output, Royer oscillation circuit consisting of FETs and which receives the DC output from the voltage double full-wave rectifier circuit and provides a high frequency oscillation, the gate windings ofhe FETs being the second winding of a saturable circuit, a starting gate bias stabilization circuit for the Royer oscillation circuit, and a main transformer which delivers a high frequency power produced in the Royer oscillation circuit, through the primary winding of the oscillation-use saturable transformer.

Claims

1. An apparatus for wireless feeding of a high frequency power, the apparatus comprising:

a voltage doubler full-wave rectifier circuit including a bridge circuit having;

a series circuit of two diodes (11) and (12), a first series circuit of two capacitors (13) and (14) and a second series circuit of two capacitors (15) and (16) all connected in parallel with one another, and

a resistor (17) connecting a first series junction of said first series circuit of two capacitors with a second series junction of said second series circuit of two capacitors;

a main transformer having a primary winding (1);

a saturable transformer having a primary winding (2) connected in series to a resistor, the series connection of the primary winding (2) and the resistor being connected in parallel with the primary winding (1) of the main transformer, and the saturable transformer further having first and second secondary windings (3) and (4);

a Royer oscillation circuit having first and second FETs (6) and (7) having respective first and second gate circuits, respectively, connected to first and second ends of the first and second secondary windings (3) and (4), respectively, of the saturable transformer through first and second parallel circuits composed of a resistor and a diode, a second end of said first secondary winding (3) being connected to a source terminal of the first FET (6), the source terminal of the first FET (6) further being connected to a drain terminal of the second FET (7) while a drain terminal of the first FET (6) and a source terminal of the second FET (7) are respectively connected to positive and negative output terminals of the voltage doubler full-wave rectifier circuit, said first and second FETs (6) and (7) respectively having first and second channel capacitors (25) and (26) connected in parallel with channels of said first and second FETs (6) and (7);

a starting gate bias stabilization circuit having a series circuit composed of a resistor (8) and a capacitor (10) connected across the positive and negative output terminals of the voltage doubler full-wave rectifier circuit, a diode (18) connecting a junction of the resistor (8) and the capacitor (10) to the junction of the source terminal of the first FET (6) and the drain terminal of the second FET (7), a diode (20) connected in parallel with the capacitor (10), and a second end of said second secondary winding (4) being connected to the junction of said resistor (8) and the capacitor (10); and

the main transformer having the primary winding (1) connected at a first end to the second series junction of said second series circuit of two capacitors of the voltage doubler full-wave rectifier circuit and at a second end to the junction of the source terminal of the first FET (6) and the drain terminal of the second FET (7), the primary winding (1) of the main transformer having a high frequency power signal driven therethrough by the Royer oscillation circuit and coupled to the primary winding (2) of the saturable transformer to provide feedback for the Royer oscillation circuit.

2. An apparatus according to claim 1, wherein the main transformer is provided with a tertiary winding (5) having a resistor provided at one end thereof, the primary winding (2) of the saturable transformer being connected in parallel across the resistor and the other end of the tertiary winding (5).

3. An apparatus according to claim 1, wherein the first and second FETs are replaced by one of UJTs or IGBTs.

4. A switching apparatus comprising:

first and second FETs serially connected at a junction of a source terminal of the first FET and a drain terminal of the second FET to form a switched terminal;

said first and second FETs having respective drains and sources respectively connected to positive and negative potentials and first and second commutation capacitors connected in parallel across respective ones of said first and second FETs;

a main transformer having a primary winding connected between said switched terminal and a neutral potential for receiving a high frequency power signal from said positive and negative potentials as switched by said first and second FETs; and

feedback means for coupling a signal from said primary winding to gates of said first and second FETs to alternately switch on and off said first and second FETs such that a dead time exists when neither said first nor said second FET is in a conductive state and during which said first and second commutation capacitors conduct current to said switched terminal.

5. The apparatus according to claim 4 wherein said feedback means comprises:

a saturable transformer having a primary winding coupled to said primary winding of said main transformer and first and second secondary windings;

said first secondary winding having a first end coupled to a gate of said first FET via a first parallel combination of a resistor and a diode and a second end coupled to said source terminal of said first FET, said first secondary winding having an impedance during saturation of said saturable transformer and said first FET having a gate-source capacitance creating a resonance facilitating rapid discharge of said gate of said first FET;

said second secondary winding having a second end coupled to a gate of said second FET via a second parallel combination of a resistor and diode and a first end coupled to said source terminal of said second FET, said second secondary winding having an impedance during saturation of said saturable transformer and said first FET having a gate-source capacitance creating a resonance facilitating rapid discharge of said gate of said first FET; and

said first and second secondary windings being coupled to said gates of said first and second FETs in opposite polarities to facilitate positive feedback from said primary winding of said main transformer.

6. The apparatus according to claim 5 further comprising:

a voltage doubler rectifier circuit having a rectifying portion with positive and negative outputs for supplying said positive and negative potentials;

a first pair of serially connected capacitors connected across said positive and negative outputs;

a second pair of serially connected capacitors connected across said positive and negative outputs;

an equalizing resistor connecting a junction of the first pair of serially connected capacitors with a junction of the second pair of serially connected capacitors to equalize voltages as said junctions of said first and second pairs of serially connected capacitors; and

said junction of the second pair of serially connected capacitors providing said neutral potential to said primary winding of said main transformer.

an oscillator circuit having a power transformer with a primary winding, first and second FETs serially connected at a junction of a source terminal of the first FET and a drain terminal of the second FET to form a switched terminal of said oscillator circuit, and feedback means for applying positive feedback to first and second gates of said first and second FETs; and

said first and second FETs having respective drains and sources connected to respective ones of said positive and negative outputs of said voltage doubler rectifier circuit, said primary winding being connected between said junction of said second pair of serially connected capacitors and said switched terminal of said oscillator circuit for receiving a high frequency power signal switched by said first and second FETs, and said feedback means being coupled to said primary winding and first and second gates of said first and second FETs to apply positive feedback from said primary winding to maintain oscillation of said oscillator circuit.

7. The apparatus according to claim 4 further comprising:

a voltage doubler rectifier circuit having a rectifying portion with positive and negative outputs for supplying said positive and negative potentials;

a first pair of serially connected capacitors connected across said positive and negative outputs;

a second pair of serially connected capacitors connected across said positive and negative outputs;

an equalizing resistor connecting a junction of the first pair of serially connected capacitors with a junction of the second pair of serially connected capacitors to equalize voltages as said junctions of said first and second pairs of serially connected capacitors; and

said junction of the second pair of serially connected capacitors providing said neutral potential to said primary winding of said main transformer.

8. A switching apparatus comprising:

first and second FETs serially connected at a junction of a source terminal of the first FET and a drain terminal of the second FET to form a switched terminal;

said first and second FETs having respective drains and sources respectively connected to positive and negative potentials;

a main transformer having a primary winding connected between said switched terminal and a neutral potential for receiving a high frequency power signal from said positive and negative potentials as switched by said first and second FETs;

feedback means for coupling a signal from said primary winding to gates of said first and second FETs to alternately switch on and off said first and second FETs such that a dead time exists when neither said first nor said second FET is in a conductive state and during which said first and second commutation capacitors conduct current to said switched terminal;

said feedback means including a saturable transformer having a primary winding coupled to said primary winding of said main transformer and first and second secondary windings;

said first secondary winding having a first end coupled to a gate of said first FET via a first parallel combination of a resistor and diode and a second end coupled to said source terminal of said first FET, said first secondary winding having an impedance during saturation of said saturable transformer and said first FET having a gate-source capacitance creating a resonance facilitating rapid discharge of said gate of said first FET;

said second secondary winding having a second end coupled to a gate of said second FET via a second parallel combination of a resistor and a diode and a first end coupled to said source terminal of said second FET, said second secondary winding having an impedance during saturation of said saturable transformer and said first FET having a gate-source capacitance creating a resonance facilitating rapid discharge of said gate of said first FET; and

said first and second secondary windings being coupled to said gates of said first and second FETs in opposite polarities to facilitate positive feedback from said primary winding of said main transformer.

9. A switching apparatus comprising:

first and second FETs serially connected at a junction of a source terminal of the first FET and a drain terminal of the second FET to form a switched terminal;

said first and second FETs having respective drains and sources respectively connected to positive and negative potentials;

a main transformer having a primary winding connected between said switched terminal and a neutral potential for receiving a high frequency power signal from said positive and negative potentials as switched by said first and second FETs;

feedback means for coupling a signal from said primary winding to gates of said first and second FETs to alternately switch on and off said first and second FETs such that a dead time exists when neither said first nor said second FET is in a conductive state;

a voltage doubler rectifier circuit having a rectifying portion with positive and negative outputs for supplying said positive and negative potentials;

a first pair of serially connected capacitors connected across said positive and negative outputs;

a second pair of serially connected capacitors connected across said positive and negative outputs;

an equalizing resistor connecting a junction of the first pair of serially connected capacitors with a junction of the second pair of serially connected capacitors to equalize voltages said junctions of said first and second pairs of serially connected capacitors; and

said junction of the second pair of serially connected capacitors providing said neutral potential to said primary winding of said main transformer.