JPH10106856A - Dc power unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To constitute a power transformer type DC power unit used for 200V AC in an inexpensive small-sized unit by using a small-sized power transformer for 100V AC because the power transformer for 200V AC becomes larger in size and higher in cost as compared with the power transformer for 100V AC. SOLUTION: A DC power unit is provided with a power transformer 21 and a fixed resistor 22 connected in series with one end of the primary winding of the transformer 21 and an AC power source 23 is connected between the other end of the primary winding of the transformer 21 and the other end of the resistor 22 so as to drop the voltage from the power source 23 to the rated voltage of the primary winding of the transformer 21 by means of the resistor 22. Therefore, the voltage applied across the primary winding of the transformer 21 becomes 100V even when the power source 23 supplies 200V AC.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC power supply used for household appliances such as a vacuum cleaner and an air cleaner, and comprises a DC power supply unit using a power transformer from a general household AC power supply. It is.

[0002]

2. Description of the Related Art Household electric appliances have many control circuits built therein, and the control circuits are generally constituted by various electronic components such as a microcomputer. Such a control circuit is operated by a DC power supply, and generally operates at a voltage lower than the voltage of a general household AC power supply. Therefore, as a DC power supply for operating this control circuit, a DC power supply shown in FIG. 10 is generally used because a DC power supply needs to be produced by lowering an AC power supply voltage as necessary.

FIG. 10 (a) shows a DC power supply of a power transformer type, in which a primary winding of a power transformer is connected to an AC power supply, and a diode of a rectifier circuit is connected to a secondary winding side of the power transformer. The power supply transformer reduces the voltage of the AC power supply, rectifies the voltage with a diode, and supplies DC power to the control circuit.

FIG. 10 (b) shows a resistance type DC power supply device in which a fixed resistor and a diode are connected in series between an AC power supply and a control circuit, and the voltage of the AC power supply is reduced by the fixed resistor. And rectify by a diode to supply DC power to the control circuit.

FIG. 10C shows a capacitor type DC power supply device, in which a full-wave rectification circuit composed of a group of diodes is connected between an AC power supply and a control circuit, and a capacitor is provided on the AC power supply side of the full-wave rectification circuit. And a fixed resistor connected thereto, the AC power supply voltage is reduced by using the impedance of a capacitor through which AC flows, and the AC power supply voltage is rectified by the full-wave rectifier circuit and supplied to the control circuit.

FIG. 10D shows a switching power supply type DC power supply. In this DC power supply, a full-wave rectifier circuit composed of a group of diodes is connected to an AC power supply, a series circuit of a diode and a transistor is connected to the output side, and a primary winding of a power transformer is connected to both ends of the diode of the series circuit. A smoothing circuit composed of a diode and a capacitor is connected to the secondary winding of the power transformer. In this configuration, current is periodically passed through the primary winding of the power transformer by switching the transistor, and the voltage generated on the secondary winding side of the power transformer is controlled by the on / off time of the transistor in the secondary winding. , The supply voltage is reduced to the operation voltage of the control circuit.

In order to operate a control circuit and the like,
The supply capacity of the DC power supply is required to be about several tens mA.

The DC power supply shown in FIGS. 10A to 10D has the following features. (A) The power transformer method is the most common method and is low-cost, and can be used in a range from small to large depending on the input / output specifications.

(B) The resistance method is the lowest cost and space saving if the output capacity is small, but since the fixed resistor itself generates a large amount of heat, it is necessary to secure the parts securely and to consider the influence on surrounding parts. is required.

(C) The capacitor method has no heat generation, so the mounting design is easy, but the power supply frequency (50/60 Hz)
, The supply current differs. Also, a large output capacitor requires a large capacitor.

(D) The switching power supply system can use a lighter and smaller power supply transformer than the power supply transformer system, but the circuit configuration is complicated, and high frequency noise is generated by switching noise of the transistor. Also, the cost is significantly higher.

When the AC power supply is 100 V, it can be handled by a resistance method or a capacitor method.
00V compatible equipment or AC power supply 220V ~
In a DC power supply device to be incorporated in a 240V-compatible device, heat generation is excessively large (approximately tens of watts) in the resistance method, and the capacitor capacitance is excessively large (several tens of μF) in the capacitor method. Because of the large space and high cost, a power transformer method had to be adopted.

[0013]

However, if an attempt is made to obtain the same output capacity between a DC power supply corresponding to 100 V AC power supply and a DC power supply corresponding to 200 V AC power supply,
In the case of the AC power supply of 200 V, the primary winding of the power supply transformer must be considerably involved, which is large compared to the power supply transformer of the AC power supply of 100 V, and the cost increases when the production quantity is small. .

For example, in the case of a power supply transformer having an output capacity of 2 VA, the power supply transformer is E28 type (32 mm in length, 32 mm in width and 28 mm in height) in the AC 100 V specification, whereas E35 is in the E35 type in the AC power supply 200 V specification. Type (External dimensions 3
(5mm, 37mm in width, 30mm in height).

It is an object of the present invention to solve such a problem and to provide a DC power supply having a small and inexpensive power supply circuit section.

[0016]

According to the present invention, a fixed resistor is connected in series with one end of a primary winding of a power transformer, and a voltage applied to the primary winding of the power transformer is controlled by the power transformer. It is possible to use a small-sized AC power supply 100V power transformer even if the equipment is compatible with AC power supply 200V.
A small and inexpensive configuration is possible.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION
A power transformer, and a fixed resistor connected in series with one end of a primary winding of the power transformer, wherein an AC power supply is connected between the other end of the primary winding of the power transformer and the other end of the fixed resistor. By setting the value of the fixed resistor so that the voltage applied to the primary winding of the power transformer becomes equal to the rated voltage of the power transformer, the voltage is reduced by the fixed resistor even in the case of 200 V AC power supply. An AC voltage equal to the rated voltage can be applied to the transformer.

The second aspect of the present invention is the first aspect of the present invention.
A capacitor is connected in parallel between both ends of the primary winding of the power transformer described above, and the voltage waveform applied to the primary side of the power transformer can be made in phase with the AC voltage waveform by the action of the capacitor.

The third aspect of the present invention provides the first aspect.
Or a configuration in which a capacitor is connected in parallel between both ends of the secondary winding of the power transformer described in 2, and the voltage waveform applied to the secondary side of the power transformer can be made in phase with the AC voltage waveform by the action of the capacitor. .

According to a fourth aspect of the present invention, a varistor is connected in parallel between both ends of the primary winding of the power transformer according to the first, second or third aspect, and a current fuse is provided on the AC power supply side from the fixed resistor. It is configured to be connected in series, and when an abnormal voltage is applied to the varistor, the action blows the current fuse.

The fifth aspect of the present invention is the first aspect of the present invention.
4. A power transformer primary winding, wherein a portion of the circuit connected to the secondary winding side of the power transformer described in any one of (1) to (4) and one end of the AC power supply are connected by a fixed resistor having a high resistance value. The fixed resistor connected to the AC power supply is connected to the other end of the AC power supply.The high-resistance fixed resistor connects the low-impedance AC power supply while the circuit on the secondary winding is insulated. Is done.

[0022]

【Example】

(Embodiment 1) FIG. 1 shows a circuit diagram of a first embodiment of the present invention, which will be described below.

In FIG. 1, reference numeral 21 denotes a power transformer whose primary rated voltage is 100 V AC. Reference numeral 22 denotes a fixed resistor connected in series with one end of the primary winding of the power transformer 21. An AC power source 23 of 200 V AC is connected between the other end of the primary winding of the power transformer 21 and the other end of the fixed resistor 22. doing.

Between the primary windings of the power transformer 21, an AC voltage dropped by the fixed resistor 22 from the AC power supply 23 is applied, and the voltage is 100 V AC equal to the rated voltage of the power transformer 21. In addition, the power transformer 21
Is connected to a rectifying diode 24 on the secondary winding side, and a DC rectified by the diode 24 is supplied to a control circuit 25.

The operation of the DC power supply device having the above configuration will be described with reference to FIG. The curve A in FIG.
4 is a graph showing a relationship between an AC voltage V applied to one primary winding and an exciting current I thereof, and an operating point when an AC voltage of 100 V is applied is a point P;

The point Q on the horizontal axis (AC voltage 200 V, current 0
If A) is connected to the operating point P by a straight line B and the reciprocal of the slope is obtained, it is the resistance value of the fixed resistor 22 suitable for the power transformer 21.

That is, an AC power supply 2 having an AC voltage of 200 V
3 is shared between the power transformer 21 and the fixed resistor 22 by 100 V AC voltage.
Since a rated voltage of 100 V is applied to one primary winding, the power transformer 21 and the control circuit 25 connected to the secondary winding thereof can operate reliably.

If the value of the fixed resistor 22 is changed, the power transformer 21 can be operated at any operating point other than the rated voltage point P. That is, the fixed resistor 22
If the resistance value R of is increased, the straight line is inclined in the direction of the large arrow R,
Conversely, if the resistance value R of the fixed resistor 22 is reduced, the straight line is inclined in the small direction of the arrow R, so that the power transformer 21 can be operated at any operating point.

Some home electric appliances use a phase control method to energize loads such as motors and heaters contained therein. In this method, the control circuit 25 detects the AC 0 V of the AC power supply 23 and determines the timing to start energizing the load based on the 0 V. For example,
The control circuit 25 supplies an ON signal to the gate of the triac that controls the energization of the load connected to the AC power supply 23. The timing of the ON signal is determined based on 0V of the AC power supply 23. The control circuit 25 sets the 0
Since it is common to detect the V voltage on the secondary winding side of the power transformer 21, that is, on the AC voltage whose voltage has dropped, the voltage phase difference between the primary winding side and the secondary winding side of the power transformer 21 is detected. The power transformer 21 and the control circuit 25 are designed so as to minimize.

Here, it is generally widely known that in the configuration of the fixed resistor R and the coil L, the voltage phase of the coil L is advanced from the voltage phase of the power supply. The relationship when the power transformer 21 and the fixed resistor 22 are connected as in the present embodiment is the same, and the voltage phase of the primary winding of the power transformer 21 is advanced from the voltage phase of the AC power supply 23, so that the secondary The voltage phase of the winding always leads the voltage phase of the AC power supply 23 (see FIG. 3). Therefore, it is desired to reliably detect the voltage phase of the AC power supply 23 without causing such a voltage phase difference.

(Embodiment 2) Next, a second embodiment of the present invention in which the above-described voltage phase difference is suppressed will be described with reference to FIG. Note that the same parts as those in the above embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 4, reference numeral 26 denotes a capacitor connected in parallel between both ends of the primary winding of the power transformer 21. In this embodiment, a capacitor having a rated voltage of 125 V AC is used.

It is generally well known that in the case of the configuration of the fixed resistor R and the capacitor C, the voltage phase of the capacitor C lags behind the voltage phase of the power supply. That is, according to the present embodiment, the voltage phase advanced by the power transformer 21 and the fixed resistor 22 can be delayed by the action of the capacitor 24, and by appropriately setting the value of the capacitor 24, The voltage waveform applied to the primary winding 21 and the voltage phase of the secondary winding thereof can be made the same as the voltage waveform of the AC power supply 23 (see FIG. 5).

Therefore, by connecting the capacitor 26 as shown in FIG. 5C, the control circuit 25 connected to the secondary winding side, in particular, in the case of a phase control circuit for controlling the phase, the AC power supply 23 AC power supply 23 in synchronization with the voltage waveform
0V can be detected, and the energization of the load connected to the AC power supply 23 is normally operated by a switching element such as a triac.

By appropriately setting the value of the capacitor 24, the phase relationship between the voltage phase of the secondary winding of the power transformer 21 and the voltage phase of the AC power source 23 can be changed to an arbitrary value of the leading phase or the lagging phase. Can also be set to

(Embodiment 3) Next, a third embodiment of the present invention will be described with reference to FIG. Note that the same parts as those in the above embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 6, reference numeral 27 denotes a capacitor connected in parallel between both ends of the secondary winding of the power transformer 21.

It is widely known that the voltage phase of the capacitor C lags behind the voltage phase applied to it. That is, according to the present embodiment, the power transformer 21
The phase of the voltage, which has been advanced by the fixed resistor 22, can be delayed by the action of the capacitor 27. By appropriately setting the value of the capacitor 27, the power transformer 2
The voltage waveform applied to one primary winding and the voltage phase of the secondary winding can be made the same as the voltage waveform of the AC power supply 23.

Therefore, similarly to the second embodiment, the phase control circuit formed on the secondary side can operate normally in synchronization with the power supply voltage waveform, and the value of the capacitor 27 must be set appropriately. Accordingly, the phase relationship between the voltage phase of the secondary winding of the power transformer 21 and the voltage phase of the AC power supply 23 can be set to an arbitrary value of the leading phase or the lagging phase.

In this embodiment, the capacitor 27 is connected only to the secondary winding of the power transformer 21.
The capacitor 26 may also be connected to the primary winding side of the power transformer 21 as described above to match the voltage phase of the secondary winding with the voltage phase of the AC power supply 23.

(Embodiment 4) Next, a fourth embodiment of the present invention will be described with reference to FIG. Note that the same parts as those in the above embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In the figure, reference numeral 28 denotes a varistor connected in parallel between both ends of the primary winding of the power transformer 21. As shown in FIG. 8, when the voltage exceeds V1 and V2, a current suddenly flows. Reference numeral 29 denotes a current fuse, which is located closer to the AC power supply 23 than the fixed resistor 22 and is connected in series with the primary winding of the power transformer 21. As described above, the voltages V1 and V2 or higher are supplied to the varistor 28. When the voltage is applied, an overcurrent flows through the varistor 28, so that the current fuse 29 is instantaneously blown.

Therefore, even if an abnormally high voltage (for example, 200 V AC) is applied to the power transformer 21 due to a short circuit at both ends of the fixed resistor 22, the varistor 28 enters the short-circuit mode and the current fuse 29 instantaneously operates. Therefore, the power transformer 21 and the capacitor 26 connected in parallel thereto can be protected from abnormal voltage in a very short time.

(Embodiment 5) Next, a fifth embodiment of the present invention will be described with reference to FIG. Note that the same parts as those in the above embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 9, reference numeral 30 denotes a circuit on the secondary winding side of the power transformer 21, for example, a GND (a portion where the potential does not fluctuate in AC) of the control circuit 25 is connected to one end of the AC power supply 23 to fix a high resistance. 3MΩ in this embodiment.
Fixed resistors are used.

Here, the fixed resistor 22 connected in series with the primary winding of the power transformer 21 is connected to the other end of the AC power supply 23. In the configuration of the present embodiment, the fixed resistor 30 having a high resistance value is used. The control circuit 25 on the secondary winding side of the power transformer 21 is insulated while the
3 is connected.

As is well known, one end of a household outlet is grounded and an AC voltage is output between the other end, so that all lines are in a very low impedance state. (In Japan, an AC 200 V outlet is provided with a ground terminal.) Therefore, according to the present embodiment, static electricity is applied or charged to the control circuit 25 configured on the secondary winding side of the power transformer 21. Even in this case, the ground line can be reliably discharged to the ground via the low impedance AC power supply 23.

In this embodiment, the GND line is connected to one end of the AC power supply 23, but the potential fluctuates in an alternating manner like the Vdd line of the control circuit 25 (after the output of the DC power supply is made constant). A similar operation can be performed by connecting a line not to be connected to one end of the AC power supply 23.

[0049]

As is clear from the above embodiment, according to the first aspect of the present invention, since the fixed resistor is connected to the primary winding of the power transformer, the AC voltage is 200V.
A power supply transformer having an AC 100 V specification can be used even for a system device, and a DC power supply device having a small and inexpensive power supply circuit unit can be configured.

According to the second or third aspect of the present invention, since the capacitor is connected to at least one of the primary winding and the secondary winding of the power transformer, the capacitor is connected to the secondary winding of the power transformer. The voltage waveform can be set to the same phase as the voltage waveform of the AC power supply, and even if a phase control circuit is connected to the secondary winding side, phase control of the load connected to the AC power supply can be reliably performed. .

According to the fourth aspect of the present invention, since the varistor and the current fuse are connected to one winding of the power supply transformer, the power supply may fail due to failure of the fixed resistor itself or tracking short-circuit at both ends thereof. Even if an abnormally high voltage is applied to the transformer, the varistor enters the short-circuit mode and the current fuse blows instantaneously, so the abnormal voltage is applied only for a very short time, and the power transformer and the capacitor connected in parallel with it Components connected to the secondary winding of the power transformer can be protected from abnormal voltages.

Further, according to the fifth aspect of the present invention, the portion of the circuit connected to the secondary winding side of the power transformer which does not fluctuate in AC and one end of the AC power source are connected to a fixed resistor having a high resistance value. Even if static electricity is applied or charged to the circuit connected to the secondary winding side of the power transformer, it can be reliably discharged from the GND line to a low impedance AC power supply. The components connected to the next winding can be protected from electrostatic breakdown.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a DC power supply device showing a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of the operation of the DC power supply device.

FIG. 3 is a diagram showing a voltage waveform of a secondary winding side of a power transformer and a voltage waveform of an AC power supply used in the device.

FIG. 4 is a circuit diagram of a DC power supply device according to a second embodiment of the present invention.

FIG. 5 is a diagram illustrating the operation of the DC power supply device.

FIG. 6 is a circuit diagram of a DC power supply according to a third embodiment of the present invention.

FIG. 7 is a circuit diagram of a DC power supply device according to a fourth embodiment of the present invention.

FIG. 8 is an explanatory diagram of the operation of the DC power supply device.

FIG. 9 is a circuit diagram of a DC power supply device according to a fifth embodiment of the present invention.

FIG. 10 is a circuit diagram of a conventional DC power supply of each system.

[Explanation of symbols]

 Reference Signs List 21 power transformer 22 fixed resistor 23 AC power supply 26 capacitor 27 capacitor 28 varistor 29 current fuse 30 fixed resistor with high resistance value

Claims (5)

[Claims] 1. A power supply, comprising: a power transformer; and a fixed resistor connected in series with one end of a primary winding of the power transformer.
An AC power supply is connected between the other end of the primary winding of the power transformer and the other end of the fixed resistor, and the voltage applied to the primary winding of the power transformer is equal to the rated voltage of the power transformer. DC power supply with a value of. 2. The DC power supply according to claim 1, wherein a capacitor is connected in parallel between both ends of the primary winding of the power transformer. 3. The DC power supply according to claim 1, wherein a capacitor is connected in parallel between both ends of the secondary winding of the power transformer. 4. The DC power supply according to claim 1, wherein a varistor is connected in parallel between both ends of the primary winding of the power transformer, and a current fuse is connected in series from the fixed resistor to the AC power supply side. apparatus. 5. A high-resistance fixed resistor connects one end of an AC power supply to a portion of a circuit connected to the secondary winding of the power transformer where the potential does not fluctuate in an AC manner. The DC power supply according to any one of claims 1 to 4, wherein the connected fixed resistor is connected to the other end of the AC power supply.