JPH0642853A - Controller for power source of refrigerator - Google Patents

Abstract

PURPOSE:To reduce an electric device container and to decrease its cost by using two transformers commonly for one power source transformer. CONSTITUTION:PTC heaters 4, 5 and a microcomputer controller 14 through a rectifier 8 are connected to a secondary side of a power source transformer 7, and the controller 14 is connected to a load controller 18. A time t2 having an allowance in a time t1 (t1<t2) in which rush currents of the heaters, 4, 5 flow eliminates an erroneous operation of an automatic icemaker 6, etc., due to an insufficient operating voltage at a load side of a stabilizer 9 caused by a voltage drop of a secondary side of the transformer 7 by setting a program for inhibiting to operate a control load by a microcomputer 15 in the microcomputer 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply control device for a refrigerator, and provides a power supply control device which does not use a transformer for a PTC motor but also serves as a power supply transformer for an automatic ice maker or the like.

[0002]

2. Description of the Related Art FIG. 4 is an external perspective view showing a state in which a freezer compartment door of a conventional general refrigerator is opened. As shown in FIG. 4, a freezer compartment 1 is provided above the refrigerator, and the freezer compartment 1 is provided with double-opening doors 2 and 3.
When the double doors 2 and 3 are closed, heat retention for preventing the double doors 2 and 3 from freezing and opening due to frost that is generated at the portion where the open / close side end portions of the double doors 2 and 3 contact. PTC heaters 4 and 5 as heaters for the vehicle and an automatic ice making machine 6 for automatically producing ice are provided in the upper left portion.

FIG. 5 is a circuit diagram showing a conventional power supply control device for a refrigerator. As shown in FIG. 5, in a refrigerator equipped with an automatic ice maker, a large amount of DC power is used to drive the automatic ice maker 6, etc., and the transformer 21 for the PTC heater and the automatic ice maker 6 are used.
Power transformer 7 is separately provided, and PTC
The PTC heaters 4 and 5 are connected in parallel to the secondary side terminals of the heater transformer 21. The primary side terminal of the power transformer 7 is connected to an AC power source, and
The primary side terminal of the PTC heater transformer 21 is connected to connection points H and I between the secondary side terminal and the AC power source side. A rectifier circuit 8 for rectifying an AC voltage is connected to the secondary side terminal of the power transformer 7, the negative side of the rectifier circuit 8 is grounded, and the positive side is a load via the control circuit power source unit 22. It is connected to the control circuit 18. The load control circuit 18 controls driving of loads such as the compressor 19, the cold air circulation fan motor 20 in the refrigerator, and the automatic ice maker 6.

When the PTC heater transformer 21 is also used as the power transformer 7 in the refrigerator power control device having the above-described configuration, the resistance of the PTC heaters 4 and 5 is low when the power is turned on. Since a large inrush current flows to the load control circuit 18, the output voltage of the rectifier circuit 8 becomes low due to the influence of the voltage drop, and the load control circuit 18 malfunctions via the control circuit power supply unit 22. In order to prevent this malfunction, the transformers are provided independently.

[0005]

However, since the power source control device for the refrigerator requires two transformers, the electrical component storage section must be made large, and the cost is high. . The present invention has been made to solve such a problem, and an object of the present invention is to provide a power supply control device for a refrigerator in which two transformers can be shared by one transformer.

[0006]

According to another aspect of the present invention, there is provided a power supply control device for a refrigerator, comprising a power supply transformer and a power supply in a power supply control device for a refrigerator including a door freeze prevention heater in a freezer compartment of the refrigerator. A PTC heater connected to the secondary side of the transformer, a rectifier circuit that rectifies the AC voltage obtained through the power transformer, a stabilization circuit that stabilizes the output voltage of the rectifier circuit, a compressor and cold air inside the refrigerator. A load control circuit for controlling the drive of a load such as a circulation fan motor or an automatic ice maker, and a microcomputer control circuit for delaying the operation start of the load control circuit immediately after power-on are provided.

[0007]

In the above structure, by replacing the two transformers with one transformer, the electric component storage portion of the refrigerator can be made small, the effective internal volume can be widened, and the cost can be reduced.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments thereof. The same parts as those in the conventional example of the present invention are designated by the same reference numerals. FIG. 1 is a circuit diagram showing an embodiment of a power supply control device for a refrigerator according to the present invention. As shown in FIG. 1, an AC power supply is connected to the primary side terminal of the power supply transformer 7, and a rectifier circuit 8 for rectifying an AC voltage is connected to the secondary side terminal of the power supply transformer 7. Two PTC heaters 4, 5 are provided at connection points A, B between the power transformer 7 and the rectifier circuit 8.
Are connected in parallel. The minus side of the rectifying circuit 8 is grounded, and the stabilizing side 9 for stabilizing the output voltage of the rectifying circuit 8 is connected to the plus side.

In the stabilizing circuit 9, the transistor 1
0 is provided, and the base terminal 10a of the transistor 10 is grounded via the Zener diode 11. The collector terminal 10b of the transistor 10 in the stabilizing circuit 9 and the positive side of the rectifying circuit 8 are connected at a connection point C, and the other end of the electrolytic capacitor 12 whose one end in the stabilizing circuit 9 is grounded is connected to the other end. A connection point D connected to the connection point C and between the connection point C and the collector terminal 10b of the transistor 10, and a base terminal 1 of the transistor 10.
A resistor 13 for supplying a base power supply is connected between the connection point E between the 0a and the Zener diode 11.

A microcomputer control circuit 14 is connected to a connection point F between the rectifying circuit 8 and the stabilizing circuit 9, and a microcomputer 15 is provided in the microcomputer control circuit 14. A diode 16 is connected in the microcomputer control circuit 14 on the connection point F side, and an electrolytic capacitor 17 is connected to the diode. The microcomputer 15 is connected to a connection point G between the diode 16 and the electrolytic capacitor 17, and the signal line 15a of the microcomputer 15 is connected to the load control circuit 1
8 is connected. The stabilizing circuit 9 is also connected to the load control circuit 18, and the load control circuit 18 controls driving of the load of the compressor 19, the cold air circulation fan motor 20 in the refrigerator, the automatic ice maker 6, and the like.

FIG. 2 is a time chart of various waveforms after the power is turned on according to an embodiment of the power supply control device for the refrigerator of the present invention. FIG. 2A shows a waveform of the PTC heater current. Since the resistance value decreases due to the positive temperature characteristic of the PTC heater, an inrush current of about 3 amperes (hereinafter abbreviated as A) is generated immediately after the power is turned on. After a lapse of time t _{1, the} current decreases and reaches a stable current of about 0.15A.

FIG. 2B shows the waveform of the output voltage of the rectifier circuit. Since the inrush current of the PTC heaters 4 and 5 is large immediately after the power is turned on, the output voltage v of the rectifier circuit 8 is v due to this influence. _The voltage drops significantly to ₀ . Then, the power supply voltage v rises as the inrush current of the PTC heaters 4 and 5 decreases, and the power supply voltage is restored to v ₂ after the lapse of time t.
The stabilizing circuit 9 flows to the load control circuit 18 when the voltage is at least the minimum voltage v ₁ required for the operation of the load control circuit 18, and the load of the load control circuit 18 operates normally so that no malfunction occurs.

FIG. 2 (c) shows a waveform of the load operation of the load control circuit. After the lapse of t ₂ time after the power is turned on, the compressor 19, the cold air circulating fan heater 20,
The automatic ice maker 6 etc. are operated.

FIG. 2 (d) shows the waveform of the microcomputer power supply voltage of the microcomputer control circuit.
Even if the output voltage of the rectifier circuit 8 drops from about 12 V (hereinafter abbreviated as V) to about 6 V due to the rush current of, the microcomputer 15 of the microcomputer control circuit 14 secures the voltage V ₃ necessary for operation, for example, 5 V. Therefore, the microcomputer 15 can operate normally.

FIG. 3 is a flow chart of a program of a microcomputer showing an embodiment of a power supply control device for a refrigerator according to the present invention. As shown in FIG. 3, the refrigerator main body is turned on, the microcomputer is initialized in step S1, and the load is not controlled until t ₂ time has elapsed after the power is turned on in step S2. . And
In step S3, it is determined whether or not t ₂ time has elapsed since the power was turned on. If YES is determined, the process proceeds to step S4, and the control load is operated. In addition, NO in step S3
If it is determined that the control load is not present, the control load operation is not performed, and the control load is not performed until the time t _{2 has} elapsed after the power is turned on, returning to the step S2. This program is repeated many times until t ₂ hours have passed.

As described above, in the above-described embodiment, due to the positive temperature characteristic, the resistance of the PTC heater is low immediately after the power is turned on, and a large inrush current flows through the PTC heater, so that the output voltage of the rectifier circuit drops. In order to prevent malfunction of the load control circuit, the microcomputer sends a preset signal to the load control circuit, so that the load control circuit does not operate until the output voltage of the rectifier circuit becomes stable in the stabilization circuit. By setting in the microcomputer, one transformer can be installed.

[0017]

Since the power supply control device for the refrigerator of the present invention is configured as described above, it is possible to prevent malfunction of an automatic ice maker or the like due to the inrush current of the PTC heater.
In addition, by also being used as a power transformer, the electrical component storage section can be made smaller and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a power supply control device for a refrigerator according to the present invention.

FIG. 2 is a time chart of various waveforms after power-on according to an embodiment of a power supply control device for a refrigerator of the present invention,
(A) is a waveform diagram of the PTC heater current, (b) is a waveform diagram of the output voltage of the rectifier circuit, (c) is a waveform diagram of the load operation of the load control circuit, and (d) is a microcomputer power supply voltage of the microcomputer control circuit. It is a waveform diagram of.

FIG. 3 is a flowchart of a program of a microcomputer showing an embodiment of a power supply control device for a refrigerator according to the present invention.

FIG. 4 is an external perspective view showing a state in which a door of a freezer compartment of a power supply control device for a conventional general refrigerator is opened.

FIG. 5 is a circuit diagram showing a conventional power supply control device for a refrigerator.

[Explanation of symbols]

 4,5 PTC heater 7 Power transformer 9 Stabilization circuit 14 Microcomputer control circuit 18 Load control circuit

Claims (1)

[Claims] 1. A power supply control device for a refrigerator comprising a door freeze prevention heater in a freezer compartment of a refrigerator, wherein a power transformer and a positive temperature characteristic ceramic heater (hereinafter referred to as a PTC heater) connected to a secondary side of the power transformer. Abbreviated), a rectifier circuit for rectifying the AC voltage obtained through the power transformer, a stabilizing circuit for stabilizing the output voltage of the rectifier circuit, a compressor, a fan motor for circulating cold air in the refrigerator, and an automatic ice machine. And a load control circuit for controlling the driving of loads such as a microcomputer, and a microcomputer (hereinafter abbreviated as microcomputer) control circuit for delaying the start of the operation of the load control circuit immediately after the power is turned on. .