JP2607736B2 - Automotive microwave oven - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to a microwave oven driven by a DC power supply.

[Prior art]

Recently, there has been a demand for a microwave oven that can be driven by a DC power supply provided in an automobile or the like. Conventionally, there is a microwave oven driven by this type of DC power supply as shown in FIG. This microwave oven includes a microwave oven body 22 including an inverter circuit 24, a high-frequency high-voltage transformer 25, a half-wave voltage doubler circuit 29, and a magnetron 28, and a power cord 23 connected to the inverter circuit 24.
And a connector 23a.
21 (for example, a car battery and a car generator). The above inverter circuit 24
Is connected to the primary winding of the high-frequency high-voltage transformer 25.
The secondary winding of the high-frequency high-voltage transformer 25 includes a capacitor 26
And a diode 27, and is connected to a magnetron 28 via a half-wave voltage doubler 29. Another secondary winding of the high-frequency high-voltage transformer 25 is directly connected to the magnetron. In the above configuration, the DC power supply 21 supplies the DC power to the inverter circuit 24 via the connector 23a and the power cord 23.
To supply. The inverter circuit 24 exchanges the DC power for high-frequency AC power. The high-frequency high-voltage transformer 25
The voltage of the high-frequency AC power is increased, and the magnetron is passed through a half-wave voltage doubler circuit 29 that rectifies the high-frequency AC power.
A DC voltage is applied to the magnetron 28, and a high-frequency AC voltage is transformed and applied to the magnetron 28. Then the magnetron
28 oscillates and generates microwaves to heat the food.

[Problems to be solved by the invention]

By the way, an inverter circuit for converting DC power into AC power is usually constituted by a circuit using a semiconductor. Since this circuit has a voltage loss of about 2 V, the higher the DC power voltage input to the inverter circuit, the higher the power conversion efficiency of the inverter circuit. However, in the above-mentioned conventional microwave oven, since a DC voltage of an automobile generator and an automobile battery whose generated voltage is about 12 V is mainly applied to the inverter circuit, voltage loss in the inverter circuit is reduced. However, there is a problem that the power conversion efficiency is poor because it reaches nearly 20% of the input voltage. In addition, the inverter circuit is operated at a low voltage of 12
Since it is driven at about V, large input current (for example, 50A
Above), the connectors, power cords, switches, and the like must be increased in size, and the microwave oven becomes expensive. Therefore, an object of the present invention is to provide a microwave oven which has good power conversion efficiency and can use a normal connector or power cord.

[Means for Solving the Problems]

In order to achieve the above object, an automotive microwave oven according to the present invention includes an inverter, wherein the automotive microwave oven is driven by a DC current from an automotive generator or an automotive battery. An output terminal and an input terminal from the vehicle generator or the vehicle battery, during operation, while connecting the storage battery in series, while connecting the storage battery connected in series to the output terminal, When the storage battery is charged, the storage battery is connected in parallel, and a switching device for connecting the storage battery connected in parallel to the input terminal is provided. Further, it is desirable to provide an overdischarge prevention device for the storage battery.

[Action]

During operation, the plurality of storage batteries are connected in series by the switching device, and the storage batteries connected in series are
Since the inverter is connected to the inverter via the output terminal of the switching device, the inverter is driven by a high voltage and a small current, so that the power conversion efficiency is good. At the time of charging the plurality of storage batteries, the plurality of storage batteries are connected in parallel by the switching device to be able to be charged at a lower voltage than during operation, and the storage battery connected in parallel is connected to the input of the switching device. Connected to a DC power supply via a terminal. Then, the plurality of storage batteries are charged at a low voltage. When the overdischarge prevention device for a storage battery is provided, overdischarge of the storage battery is prevented.

【Example】

Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. As shown in FIG. 1, the microwave oven according to the present embodiment comprises an inverter circuit 6, a high-frequency high-voltage transformer 7, a half-wave voltage doubler circuit.
Microwave oven body 2 including 11, magnetron 9 and 12 V storage batteries (hereinafter referred to as “batteries”) 4 and 5, switching device 12 and overdischarge prevention device 13, and input terminal of switching device 12
A power cord 3 connected to 12a, an over-discharge prevention device 14,
A connector 3a is provided, and a DC power source 1 such as a battery mounted on an automobile and generating a DC voltage of 12V is connected to the connector 3a so that the batteries 4 and 5 can be charged from the DC power source 1. ing. Switching device 12
Are connected to the batteries 4 and 5, and the switching device 12
The output terminal 12b is connected to the inverter circuit 6 via an overdischarge prevention device 13. The switching device includes a plurality of switches (not shown), as shown in FIGS.
The batteries 4 and 5 are connected in series or in parallel and can be connected to an output terminal or an input terminal. The inverter circuit 6 is connected to a primary winding of a high-frequency high-voltage transformer 7. The secondary winding of the high-frequency high-voltage transformer 7 is connected to a magnetron 9 via a half-wave voltage doubler circuit 11 including a capacitor 8 and a diode 10. Another secondary winding of the high-frequency high-voltage transformer 7 is directly connected to the magnetron 9. In the above configuration, during operation, as shown in FIG. 2, the switching device 12 opens the input terminals 12a, 12a, disconnects the batteries 4, 5 from the DC power supply 1,
The batteries 4, 5 are connected in series, and the batteries 4, 5 connected in series are connected to output terminals 12b, 12b.
Then, the batteries 4 and 5 connected in series supply a DC voltage of 24 V to the inverter circuit 6 via the output terminal 12b and the overdischarge prevention device 13. Therefore, it is possible to prevent the batteries 4 and 5 from being over-discharged. Further, the power conversion loss value of the inverter circuit 6 is such that the value of the voltage loss 2V in the inverter circuit 6 is a ratio to the DC voltage value of 24 V input to the inverter circuit 6, that is, approximately 8%, and is 12 V as in the related art. 17% which is the ratio of the power exchange loss value when applying the DC voltage of the inverter circuit to the inverter circuit, that is, the voltage loss value 2V in the inverter circuit with respect to the DC voltage 12V.
, The power conversion loss value can be reduced by about 9%. As described above, the inverter circuit 6 efficiently converts DC power into high-frequency AC power. Then, the high-frequency high-voltage transformer 7 boosts the high-frequency AC power by its secondary winding, and applies a DC voltage to the magnetron 9 via a half-wave voltage doubler circuit 11 that rectifies the high-frequency AC power. At the same time, the high frequency AC voltage is transformed by another secondary winding and applied to the magnetron 9. Then, the magnetron 9 oscillates, generates microwaves, and heats the food. When charging the batteries 4 and 5, as shown in FIG. 3, the switching device 12 opens the output terminals 12b and 12b, disconnects the batteries 4 and 5 from the inverter circuit 6, and disconnects the batteries 4 and 5 from each other. Are connected in parallel, and the batteries 4, 5 connected in parallel are connected to the input terminals 12a, 12a. Then, the DC power supply 1 can charge the batteries 4 and 5 at about 12V via the connector 3a, the overdischarge prevention device 14 and the power cord 3. At this time, since the current flowing when charging the batteries 4 and 5 is a small current of about 10 A, the connector 3a
In addition, the power cord 3 does not need to be particularly large. In addition, the DC power source 1 is
Can be prevented from being over-discharged. The DC power supply 1 is, for example, a battery mounted on an automobile and has only a certain electric capacity (for example, 60 AH).
While charging the generator with the DC power source 1, the batteries 4,5
It is desirable to charge. In the above embodiment, the batteries 4 and 5 are built in the microwave oven main body, but may be provided near the microwave oven main body.

【The invention's effect】

As is apparent from the above description, in the automotive microwave oven of the present invention, during operation, the switching device connects a plurality of storage batteries in series, and connects the storage batteries connected in series via the output terminal of the switching device. Since the inverter is connected to the inverter, the inverter can be driven with a high voltage and a small current without using a special large-sized DC power supply, and the power exchange efficiency of the inverter is good. When the plurality of storage batteries are charged, the switching device connects the plurality of storage batteries in parallel, so that the plurality of storage batteries can be charged at a low voltage using a normal power cord and connector. When the overdischarge prevention device for the plurality of storage batteries is provided, overdischarge of the plurality of storage batteries can be prevented.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of one embodiment of a microwave oven for an automobile of the present invention, FIG. 2 is a circuit diagram of the above embodiment during operation, FIG. 3 is a circuit diagram of the above embodiment during charging, and FIG. Is a circuit diagram of a conventional microwave oven. 1,21 …… DC power supply, 2,22 …… Microwave oven body, 3,23 ……
Power cord, 4,5… Battery, 6,24 …… Inverter circuit, 7,25 …… High frequency high voltage transformer, 8,26 …… Capacitor, 9,28 …… Magnetron, 10,27 …… Diode, 11,
29: Half-wave voltage doubler, 12: Switching device, 13, 14: Overdischarge prevention device.

Claims (2)

(57) [Claims] An automotive microwave oven comprising an inverter and driven by a DC current from a vehicle generator or a vehicle battery, comprising: a plurality of storage batteries; an output terminal to the inverter; An input terminal from an automobile battery is provided, and during operation, the storage batteries are connected in series, and the storage battery connected in series is connected to an output terminal.On the other hand, when the storage battery is charged, the storage battery is connected. A microwave oven for an automobile, comprising: a switching device connected in parallel and connecting the storage battery connected in parallel to an input terminal. 2. An automotive microwave oven according to claim 1, further comprising an over-discharge prevention device for said storage battery.