Magnetron feeding apparatus and method of controlling the same

• US 4,900,989 A
• Filed: 05/02/1988
• Issued: 02/13/1990
• Est. Priority Date: 04/30/1987
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited 1006 OAZA Kadoma-Shi Osaka Japan
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Niwa, Takashi, Bessyo, Daisuke, Suenaga, Haruo, Matsumoto, Takahiro, Sakamoto, Kazuho, Maehara, Naoyoshi
• Primary Examiner(s): Mis, David
• Application Number:
  US07/189,166
• Time in Patent Office: 652 Days
• Field of Search: 315/101, 315/105, 315/106, 315/107, 315/209, 315/219, 315/224, 315/308
• US Class Current: 315/224
• CPC Class Codes: H02M 3/33507 with automatic control of the output voltage or current, e.g. flyback converters H02M3/33561, H02M3/33569 take precedence
• CPC Class Codes: H02M 3/33523 with galvanic isolation between input and output of both the power stage and the feedback loop
• CPC Class Codes: H02M 7/537 using semiconductor devices only, e.g. single switched pulse inverters
• CPC Class Codes: H03B 9/10 using a magnetron
• CPC Class Codes: H05B 6/666 Safety circuits emergency protective circuits in general H02H

Abstract

A magnetron feeding apparatus includes an inverter circuit for converting DC power into high-frequency power; a high-tension transformer for converting the high-frequency power into high-tension power to be supplied to the magnetron; an output voltage detector for detecting the output voltage of the high-tension transformer; an input current detector for detecting the input current into the inverter circuit; a power controller for controlling the operation of the inverter circuit in response to the output voltage detected by the output voltage detector and the input current detected by the input current detector.

Claims

1. A magnetron feeding apparatus comprising a power-supply for feeding a DC current, an inverter circuit for converting the DC current into high-frequency power through the switching operation of a semiconductor switch, a high-tension transformer which converts the high-frequency power into high-tension power to be supplied to a magnetron, an output voltage detector for detecting the output voltage of the high-tension transformer, an input current detector for detecting the input current into the inverter circuit, and a power controlling means for controlling the switching operation of the semiconductor switch using the output voltage information of the output voltage detector and the input current information of the input current detector.

2. A magnetron feeding apparatus described in claim 1, further comprising said power controlling means for controlling so that the value of the larger of the output voltage information and input current information may become a first given value.

3. A magnetron feeding apparatus described in claim 1, wherein said power controlling means comprises an output voltage controlling means for controlling so that the output voltage information may become a second given value, an input current controlling means for controlling so that the input current information may become a third given value and a selecting means for selecting a controlling means of the smaller of the output voltage controlling means and the input current controlling means in a required input current into the inverter circuit.

4. A magnetron feeding apparatus described in claim 1, wherein said power-supply is adapted to rectify the commercial power-supply to obtain the DC power supply.

5. A magnetron feeding apparatus described in claim 1, wherein said power-supply is composed of a battery.

6. A magnetron feeding apparatus described in claim 1, wherein said input current detector is adapted to detect the input current from the power-supply portion.

7. A magnetron feeding apparatus described in claim 1, wherein said output voltage detector is adapted to detect the output voltage of an exclusive detection winding provided on the high-tension transformer.

8. A magnetron feeding apparatus described in claim 1, wherein said output voltage detector uses one portion of an output winding of the high-tension transformer as a detection winding so as to detect the output voltage.

9. A magnetron feeding apparatus described in claim 2, further comprising a first gradual increasing means for controlling so that the output voltage information or the input current information is gradually increased to the power controlling means.

10. A magnetron feeding apparatus described in claim 3, further comprising a second gradual increasing means for controlling so that the output voltage information or the input current information may be gradually increased to the power controlling means.

11. A magnetron feeding apparatus described in claim 1, further comprising a third comparing means for comparing the output voltage information with a sixth given value, a third gradual increasing means for controlling so that the input current information is gradually increased to a seventh given value when the output voltage information is small with respect to the sixth given value, a first gradual decreasing means for controlling so that a preselected current information may be gradually decreasing when the output voltage information is large with respect to the sixth given value.

12. A magnetron feeding apparatus described in claim 4, wherein said input current detector is adapted to detect the input current from the commercial power supply.

13. A magnetron feeding apparatus described in claim 1, further comprising a rectification circuit connected between the high-tension transformer and the magnetron.

14. A magnetron feeding apparatus comprising a power-supply for feeding a DC current, an inverter circuit for converting the DC current into high-frequency power through the switching operation of a semiconductor switch, a high-tension transformer which converts the high-frequency power into high-tension power to be supplied to a magnetron, an output voltage detector for detecting the output voltage of the high-tension transformer, an input current detector for detecting the input current into the inverter circuit, and a software processor for forming the driving pulses of the semiconductor switch using the output voltage information of the output voltage detector and the input current information of the input current detector.

15. A method of controlling said magnetron feeding apparatus described in claim 14, having in said software processor a program flow comprising the steps of performing an initial setting of inner data after the power supply has been put into operation, and thereafter repeating the inputting operation of the output voltage information and the input current information, the data forming operation for setting an on time to form, using the inputted output voltage and input current information, the data for setting the on time of the semiconductor switch, and a driving pulse outputting operation for setting the pulse width of the driving pulse which turns the semiconductor switch on and off using the data used for the on time setting.

16. A method of controlling said magnetron feeding apparatus described in claim 15, having in said software processor a program flow comprising the steps of starting a timer on for setting the timer time at the value of the on time setting data, outputting driving pulses for turning on the semiconductor switch, detecting the completion of the timer on to output driving pulses for turning off the semiconductor, starting the timer off of the timer time of the given value, and returning to the start of the timer on through the detection of the complection of the timer off.

17. A method of controlling said magnetic feeding apparatus described in claim 15, having in said software processor a program flow comprising the steps of inputting the output voltage information and the input voltage information, selecting the information of the larger value through the comparison between said output and input voltage information, comparing the information of the larger value and a first given value to decrease the data for the on time setting use when the information is larger than the first given value, and increasing the data for on time setting use when it is smaller than the first given value.

18. A method of controlling said magnetron feeding apparatus described in claim 15, having in said software processor program flow comprising the steps of inputting output voltage information, comparing the output voltage information with a second given value to decrease a predetermined data V for the on time setting use when it is larger than the second given value, increasing the data V for the on time setting use when it is smaller than the second given value, a program flow comprising the steps of inputting the input current information, comparing the input current information with a third given value to decrease a predetermined data I for the on time setting use when it is larger than the third given value, increasing the data I for the on time setting use when it is smaller than the third given value and a program flow comprising the steps of comparing the data V for on time setting use with the data I for the on time setting use, having the data of smaller value as the data for the on time setting use.

19. A method of controlling said magnetron feeding apparatus described in claim 15, having in said software processor a program flow comprising the steps of inputting the output voltage information, comparing the output voltage information with a fourth given value to decrease the current reference information when it is larger than the fourth given value, to increase the current reference information when it is smaller than the fourth given value, and restricting to a fifth given value the largest of the increased current reference information, a program flow comprising the steps of inputting the input current information, comparing the input current information with the current reference information to decrease the data for the on time setting use when it is larger than the current reference information, to increase the data for the on time setting use when it is smaller than the current reference information.