a-c/d-c microwave oven
AssigneeSawafuji Electric Co., Ltd.
InventorsNaoki Akazawa, Makoto Gezima
Life of this patent
Estimating the term…
Abstract
An a-c/d-c microwave oven adapted to be connected to an a-c and/or d-c power source. The oven has an inverter for converting d-c power to a-c power to feed power to a magnetron generating high-frequency energy via a transformer. Input from the d-c and a-c power sources is selectively fed to the magnetron. A first primary winding is fed commercial a-c power. A second primary winding is fed on a-c voltage from the inverter. A secondary winding connecting to the magnetron is wound on the transformer. A predetermined voltage is adjusted in the secondary winding of the transformer by adjusting the frequency of the a-c voltage from the inverter at a higher level than the commercial a-c power, which is fed to the second primary winding.
Claims6
A microwave oven operatable on either AC or DC power sources, the oven comprises:
- a transformer having a primary side and a secondary side, said primary side having a first primary winding and a second primary winding, said secondary side having a first secondary winding and a second secondary winding, said first primary winding being connectable to the AC power source;
- a magnetron receiving heater current from said first secondary winding and receiving load current from said second secondary winding;
- invertor means for transforming power from the DC power source into inverter AC power, said invertor means delivering said inverter AC power to said second primary winding;
- frequency control means for increasing a frequency of said invertor AC power to a frequency larger than a frequency of the AC power source in order to compensate for a change in voltage in said secondary winding due to different power characteristics between said AC power source and said invertor AC power;
- current sensor means for sensing current in said second secondary winding;
- frequency control means for controlling said frequency of said invertor AC power in accordance with said current sense by said current sensor means;
- phase control means for adjusting phase characteristics of said invertor AC power in accordance with said current sensor means;
- input voltage phase means for adjusting said duty cycle of said invertor AC power in accordance with a voltage of the DC power source.
Dependencies are inferred from the claim text.