JP3400945B2 - Power supply - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device for microcomputer control equipment using a commercial power supply.

[0002]

2. Description of the Related Art There are many electric / electronic devices controlled by a microcomputer (hereinafter referred to as "microcomputer") using a commercial power supply (50/60 Hz). Examples thereof include microwave ovens and air conditioners. A microwave oven will be described below as an example.

The control unit of a conventional microcomputer type microwave oven is
A power supply circuit as shown in FIG. 4 is used, and this power supply circuit rectifies the voltage on the secondary side of the low voltage transformer 1 connected to an alternating current (AC 100 V) to drive the microcomputer 4. On the secondary side of the low-voltage transformer 1, a stepped-down voltage of about 10V is induced. This secondary voltage is applied to the rectifying diode D1, which is built in the bridge.
Full-wave rectification is performed at D2, D3, and D4, and the rectified voltage is smoothed at the capacitor C1. The smoothed DC voltage is used as a drive power source for the relay L and the like as VA.

The DC voltage VA is applied to the microcomputer 2 after being controlled to a constant voltage (for example, 5V) by a three-terminal regulator (IC). Of course, a constant voltage circuit combining a transistor and a Zener diode may be used.

When the start signal is generated by pressing the key 4 on the operation panel 3 to heat the microwave oven, the microcomputer 2 sends a signal (HIGH signal) to the transistor TR1.
H) is sent, the relay L is operated, and its contact T is closed. When the contact T of the relay L is closed and the commercial power source is maintained in the power transformer 5, a high voltage is applied to the magnetron 6 via the voltage doubler rectifier circuit, and the magnetron 6 oscillates to start a heating operation. When the predetermined heating time elapses, the microcomputer 2 finishes heating, and therefore, the symbol (LOW) for turning off the transistor TR1 is transmitted and the relay L is turned off.
Then, the contact T is opened, the power supply to the magnetron 6 is stopped, and the heating operation is ended.

In a normal microcomputer type microwave oven, a display tube is operated during standby, and sensors such as a weight sensor and a humidity sensor are in a standby state. In such a set, power consumption during standby is 10 W or more. . Even if the display tube and the sensor are stopped, a current constantly flows through the low-voltage transformer 1, so that power consumption of about several W is consumed.

[0007]

The above-mentioned prior art has the following problems. When the power plug of an electronic / electrical device is inserted into a power outlet, AC power is automatically applied to the control unit of the device. Therefore, an AC voltage (100V) is constantly applied to the low-voltage transformer, an exciting current flows through the low-voltage transformer, and power is consumed even during standby when the device is not used.

In order to configure an energy-saving circuit, a method has been proposed in which a relay or a switch is separately provided so that an AC power source is not applied to a low voltage transformer for a control unit. There are problems that parts are required, the number of production processes increases, and the cost increases.

Further, variations in the low voltage transformer for the control unit, differences due to the power supply frequency (50/60 Hz), or
The DC output voltage (VA) of the power supply circuit for the control unit changes due to voltage fluctuations or the like depending on the presence or absence of a load (relay ON / OFF). This makes circuit design difficult, requires a design (parts specification) with a margin, and causes a problem of high cost. In this case, there is no problem if the power supply circuit has a constant voltage, but the problem of cost increase cannot be avoided by the constant voltage.

[0010]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a power supply device according to claim 1 in which a series circuit of a power control element and a rectifier is provided for a commercial power source. And a snubber capacitor connected in parallel, a smoothing capacitor is provided on the output side of the rectifier, and a device control microcomputer that uses a DC voltage smoothed by the smoothing capacitor as a voltage source is provided. When the control element is in the cut-off state, the direct current voltage generated by the current flowing through the snubber capacitor is used as the supply voltage source of the microcomputer during standby.

According to another aspect of the power supply device of the present invention, a series circuit of a power control element and a rectifier is provided for a commercial power source, a snubber capacitor is connected in parallel with the power control element, and the output side of the rectifier is connected. Is equipped with a smoothing capacitor,
Provided is a device control microcomputer that uses a DC voltage smoothed by the smoothing capacitor as a voltage source, and control means that controls the opening and closing of the power supply circuit of the device body by the microcomputer. When both are in the cutoff state and the device body is in the standby state, the DC voltage generated by the current flowing through the snubber capacitor is used as the supply voltage source of the microcomputer in the standby state.

According to a third aspect of the present invention, there is provided a series circuit of a power control element and a rectifier which are connected in series to a commercial power source, and a snubber capacitor is connected in parallel with the power control element. A smoothing capacitor is provided on the output side of the rectifier, and a DC low-voltage power supply for a microcomputer is provided for supplying a DC voltage smoothed by the smoothing capacitor to a device controlling microcomputer. In a power supply device provided with control means for controlling
It is characterized in that opening / closing of the power control element is controlled in accordance with a control signal from the microcomputer to control a conduction angle of an AC power source to adjust a rectified DC output voltage supplied to the microcomputer. .

According to a fourth aspect of the present invention, in the power source apparatus according to the third aspect, a frequency discriminating means for discriminating the frequency of the commercial power source is provided, and the power source frequency is determined based on the power source frequency discriminated by the frequency discriminating means. Control means for controlling the conduction angle of the power control element by a microcomputer so that the DC power voltage becomes equal even if the above are different.

According to a fifth aspect of the present invention, in the power source apparatus according to the third or fourth aspect, there is provided detection means for detecting the DC output voltage of the DC low voltage circuit, and the DC output detected by the detection means. It is characterized in that control means for controlling the conduction angle of the power control element is provided so that the voltage becomes a predetermined value.

According to a sixth aspect of the present invention, in the power source apparatus according to any of the third to fifth aspects, the power source device is driven by the DC low voltage circuit when the main body of the equipment is changed from a standby state to an operating state. When the load is increased, a predetermined value set in advance in the microcomputer is increased to widen the conduction angle of the power control element, and the DC output voltage is increased.

(Operation) According to the power supply device of the first aspect, the power control element and the rectifier connected in series to the commercial power source are provided, the snubber capacitor is connected in parallel with the power control element, and the power control element is connected during standby. The power control element is turned off, and the microcomputer is driven by the voltage divided by the snubber capacitor and the smoothing capacitor. Therefore, since there is no transformer in the power supply circuit of the microcomputer during standby and power is not consumed by the exciting current, it is possible to obtain a power supply device with a simple configuration and with extremely low power consumption during standby.

According to another aspect of the power supply device of the present invention, the control means for opening and closing the power supply circuit of the equipment main body is provided by the microcomputer, so that the power supply circuit of the equipment main body is opened by the control means and the entire equipment is opened. Claim 1 when in a standby state
As in the case of (1), it is possible to obtain a power supply device with extremely low power consumption during standby.

According to the power supply device of the third aspect, since a series circuit of the power control element and the regulator is provided in series with the commercial power source, and the conduction angle of the power control element is controlled by the microcomputer, the output side of the rectifying diode. The DC output voltage obtained between both terminals of the smoothing capacitor provided in the above can be adjusted so that it increases with increasing conduction angle and decreases with decreasing conduction angle. The voltage can be adjusted to the desired value.

According to another aspect of the power supply device of the present invention, the frequency of the connected commercial power source is detected by the frequency detecting means, and the DC output voltage between both terminals of the smoothing capacitor is detected by the microcomputer based on the detected frequency. So that it becomes a predetermined value,
Since the conduction angle of the power control element is controlled, the value of the DC output voltage is always set to a predetermined value regardless of the frequency of the commercial power source to be connected even when there is a load fluctuation when connected to commercial power sources of different frequencies. Can be held.

According to another aspect of the power supply device of the present invention, the DC output voltage of the DC low voltage circuit of the microcomputer is detected by the detecting means, and the detected DC output voltage becomes a predetermined value preset in the microcomputer. Since the control means by the microcomputer controls the conduction angle of the power control element, the DC input voltage supplied to the microcomputer can always be kept at a predetermined value.

According to the power supply device of claim 6, when the main body of the equipment is to be shifted from the standby state to the operating state, the microcomputer extends the conduction angle of the power control element and the DC low voltage serves as the DC power source of the microcomputer. Increase the output voltage of the circuit. When the equipment main body shifts from the standby state to the operating state, a load requiring power such as a relay for connecting the power supply circuit of the equipment main body is connected to the DC low voltage circuit, and the load of the DC low voltage circuit increases. The increased load can be definitely driven by increasing the output voltage.

[0022]

FIG. 1 is a circuit diagram of an embodiment in which the present invention is used in a microwave oven. In FIG. 1, parts corresponding to those in the conventional example shown in FIG. In FIG. 1, SS is placed between both terminals of the AC power supply AC.
Power control element 7 such as R, and rectifying diodes D1 to D
4 are connected in series. In the present embodiment, the SSR is used as the power control element 7, but not limited to the SSR, a triac, a thyristor or the like may be used. The SSR (photothyristor coupler, phototriac coupler) has a structure in which the thyristor or triac on the output side is ignited by the signal of the LED (light emitting diode) 8 on the input side.

A snubber component consisting of a series circuit of a capacitor C2 and a resistor R3 is connected between both terminals of the power control element 7. The capacitor C2 and the resistor R3 of this snubber component may be separate components, or may be an integrated component. Further, the resistor R3 is omitted, and the capacitor C
You may comprise only two. This snubber component absorbs noise due to the switching operation of the power control element 7. Usually, this value is C2 = 0.2μF, R3 = 100
It is about Ω.

The rectifying diodes D1 to D4 connected in series to the power control element 7 constitute a bridge and full-wave rectify the input AC voltage. The voltage after rectification is the resistance R
It is divided by 1 and R2 and smoothed by the smoothing capacitor C1. This value is set to about C1 = 470 μF and R2 = 510Ω.

When the microwave oven is in a standby state, the microcomputer 2 turns off the transistor TR1 and the relay L
The contact T is opened to cut off the supply of commercial power to the high voltage power transformer 5 of the magnetron 6. At the same time, the microcomputer 2 turns off the transistor TR2 to turn off the LED 8 such as the photothyristor coupler, and the power control element 7 such as the SSR.
Is turned off. At this time, AC100 of commercial power supply
V is supplied in series to the capacitor C2, the resistor R3, the rectifying diodes D1 to D4, the resistor R1 and the capacitor C1 (actually, a combined impedance with a load connected in parallel with the capacitor C1), and the V of the capacitor C1 is supplied. A voltage VA substantially generated by the capacitors C2 and C1 is generated between the terminals. The resistors R1, R2,
When the values of R3 and the capacitors C1 and C2 are the values shown in this embodiment, the DC output voltage VA generated between both terminals of the capacitor C1 is about 30V.

The DC output voltage VA generated between both terminals of the capacitor C1 is applied to the relay L and is also supplied to the three-terminal regulator IC, and the DC voltage VC is converted into a constant voltage by the three-terminal regulator IC. Derive,
It is applied to the microcomputer 2. In this way, since only the microcomputer 2 is operating during standby of the microwave oven, its power consumption is a minute value of 100 mW or less.

On the other hand, a resistor R4 is connected in parallel with the rectifying diode D3 from the connection point of the rectifying diodes D2 and D3.
A series circuit of R5 and R5 is provided to keep the capacitor C3 in parallel with the resistor R5. As a result, the AC waveform V of the commercial power source
1 is double-wave rectified by the rectifying diodes D1 to D4, but the voltage at the connection point of the rectifying diodes D2 and D3 has a half-wave rectified voltage waveform V2 as shown in FIG. The voltage waveform V2 is shaped by the resistors R4 and R5 and the capacitor C3. Then, the rectangular-wave INT (power supply cycle) signal shown in FIG. 2 that is cycled to the power supply frequency is derived from between both terminals of the capacitor C3. The INT signal is supplied to the microcomputer 2 and is used as a control signal that serves as a reference for the timing of various controls of the microcomputer 2.

Next, the key 4 on the operation panel 3 is pressed,
When an instruction to put the microwave oven in the operating state is input to the microcomputer 2, the control circuit of the microwave oven shifts from the standby state to the operating state. In the standby state of the microwave oven, the power control element 7 is off as described above, and the relay L is only supplied with the DC output voltage VA divided by the capacitors C2 and C1. When the transistor TR1 is turned on by the microcomputer 2 and a current for turning on the relay L is passed through the relay L, the value of the DC output voltage VA is drastically reduced. This is because the power supply circuit including the capacitors C2 and C1 has a small power supply capacity.

Therefore, when the microcomputer 2 receives an instruction to turn on the microwave oven, it turns on the transistor TR2 before turning on the transistor TR1 for turning on the relay L. As a result, the LED 8 is turned on, the power control element 7 such as the SSR is turned on, the commercial power source is directly applied to the rectifier diodes D1 to D4, and sufficient electric charge is accumulated in the smoothing capacitor C1. It Therefore, when the transistor TR1 is turned on by the microcomputer 2 in this state, the contact T is turned on by the relay L,
Activate the microwave.

When the above-mentioned transistor TR2 is always conducting, the AC100V of the commercial power source is rectified by the rectifying diode D.
1 to D4 are directly rectified, so the above DC output voltage V
A becomes too high, about 141V. So the microcomputer 2
Is the transistor TR from the rising edge of the INT signal
The power control element 7 is controlled by controlling the time T1 until 2 is turned on.
The conduction angle θ is changed to obtain a predetermined voltage. This time T1 is suppressed within the range of 5 mS to 10 mS (in the case of 50 Hz). Usually, it is about 8 mS. This is the number of relays L to be used (usually the relays L are used to control parts other than the drive circuit of the magnetron 6, and several relays are used. The power consumption of the relay is often 0.2 W / piece or more) and sensor type. (Power consumption of gas sensor is 1
W, the power consumption of the humidity sensor is about 0.5 W), etc. The time T1 is shortened as the load becomes heavier.

FIG. 3 is a diagram showing the relationship between the output waveforms P1 and P2 of the transistor TR2 and the output waveforms Q1 and Q2 of the SSR used as the power control element 7 with respect to the INT signal A. When the load is large (small), the microcomputer 2
The time T1 is set short (long) and the transistor T
As shown in the output waveform P1 (P2), the ON time of R2 is
Make it long (short). As a result, the output of SSR is output waveform Q.
As shown in 1 (Q2), the conduction angle θ is large (small).
Therefore, the DC output voltage VA generated between both terminals of the capacitor C1 becomes high (low). That is, when the conduction angle θ of the power control element 7 is controlled according to the load, the DC output voltage VA can be changed according to the load. When the conduction degree θ is large, the DC output voltage VA is high and the conduction is If the angle is small, the DC output voltage VA can be set low.

The DC output voltage VA is divided by resistors R6 and R7 as shown in FIG. 1, and the voltage VO at the midpoint thereof is input to the microcomputer 2. The reference voltage VO ′ necessary for operating the load such as the relay L is stored in the microcomputer 2 in advance. The voltage VO at the midpoint of the resistors R6 and R7 is the reference voltage V stored in the microcomputer 2 in advance.
The time T from the rise of the INT signal A to the turn-on of the transistor TR2 is set to O ′ so that it becomes O ′.
1 is added or subtracted to set the DC output voltage VA to the reference voltage V
Control to a predetermined value corresponding to O '. During the heating operation of the microwave oven, the microcomputer 2 constantly reads the voltage VO at the midpoint and performs the above control, so that the fluctuation of the DC output voltage VA can be suppressed. Also, the DC output voltage V
When the load driven by A fluctuates, the reference voltage VO ′ previously stored in the microcomputer 2 can be changed according to the load. The output voltage VA can also be derived.

When the DC output voltage VA between both terminals of the capacitor C1 becomes a voltage required for operating the relay L by the microcomputer 2, then the transistor TR1 is turned on by the microcomputer 2 and the relay L is turned on to make the contact T. Closes. As a result, a commercial power supply is connected to the high-voltage power transformer 5 of the magnetron 6, a high voltage is applied to the magnetron 6, and the heating operation of the microwave oven is started. After that, when the heating time ends, the microcomputer 2 turns off the transistor TR1, shuts off the relay L, opens the contact T, and shuts off the supply of voltage to the power supply circuit of the magnetron 6. In this way, when the series of operations as the device is completed and the standby state is entered, the microcomputer 2 stops sending a signal to the transistor TR2 and turns off the power control element 7 such as SSR.
Returns to the original standby state with low power consumption.

Further, the microcomputer 2 can detect whether the frequency of the commercial power source being used is 50 Hz or 60 Hz by counting the number of INT signals A shown in FIG. Therefore, depending on the power supply frequency being used, the transistor T
By controlling the time T1 until R2 is turned on, in other words, the conduction angle θ of the voltage control element 7 is controlled by the microcomputer 2, it is possible to suppress the fluctuation of the DC voltage VA due to the difference in frequency.

In the case of a microwave oven, 50 Hz is required for use with both 50 Hz and 60 Hz commercial power sources.
At this time, it is necessary to change the capacity of the high voltage capacitor C4 connected to the magnetron 6 by using a relay (not shown). In this case, 0.5 W or more of electric power is required to drive the relay, and this electric power is extra as compared with the case of using a 60 Hz commercial power source. That is, 5
When the commercial power source of 0 Hz is used, the load driven by the DC voltage VA during the operation of the microwave oven becomes larger than when the commercial power source of 60 Hz is used. Therefore, in the present embodiment, when it is detected that the commercial power source of 50 Hz is connected, the microcomputer 2 causes the I
Transistor TR2 is turned on from the rise of NT signal A
The time T1 until it is controlled is controlled to be shorter in the case of 50 Hz than in the case of 60 Hz so that the DC voltage VA during operation in the case of 50 Hz becomes the same as that in the case of 60 Hz.

In the above embodiment, the case where the power supply device of the present invention is applied to the microwave oven is shown, but the present invention can be similarly applied to other electronic / electrical devices using a commercial power supply. Further, in the above-described embodiment, the snubber component including the capacitor and the resistor provided in parallel with the power control element absorbs noise generated by switching of the power control element during operation of the power control element, and the electronic circuit The effect of noise on the

[0037]

According to the present invention, the power supply circuit of the microcomputer is constituted by the series circuit of the snubber capacitor and the smoothing capacitor which are provided in parallel with the power control element when the apparatus body is in the standby state. Therefore, an exciting circuit such as a transformer in a standby state becomes unnecessary, and it is possible to provide a low power consumption power supply device in which power consumption due to an exciting current is reduced. In this case, the snubber capacitor also absorbs noise due to switching of the power control element at the same time, so that the capacitor can be efficiently used.

Further, since the conduction angle of the power control element is controlled by the microcomputer, the DC output voltage of the power supply circuit for the microcomputer can be freely changed according to the load controlled by the microcomputer.

Further, the microcomputer detects the power supply frequency, and based on the detected power supply frequency, the microcomputer controls the conduction angle of the power control element so that the DC output voltage, which is the DC current of the microcomputer, is different even when the power supply frequency is different. Since it is kept constant, the DC output voltage can be kept constant even when the load controlled by the microcomputer differs depending on the power supply frequency, providing a power supply device suitable for equipment commonly used at different power supply frequencies. can do.

Further, the DC output voltage of the DC low voltage power supply circuit for the microcomputer is detected, and the conduction angle of the power control element is controlled by the microcomputer so that the detected value becomes a predetermined value. It is possible to control the fluctuation of the DC output voltage and provide a power supply device including a stable power supply circuit for a microcomputer.

Further, when the equipment main body is shifted from the standby state to the operating state, a predetermined value preset in the microcomputer is increased to raise the DC output voltage. It is possible to provide a power supply circuit that reliably drives these loads even if the load for controlling the device body such as a relay is increased.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of the present invention.

FIG. 3 is an operation explanatory diagram of the present invention.

FIG. 4 is a circuit diagram of a conventional example.

[Explanation of symbols]

2 microcomputer 3 Operation panel 4 keys 5 High voltage power transformer 6 magnetron 7 Power control element 8 LED C1, C2, C3 capacitors R1, R2, R3, R4, R5, R6, R7 resistance D1, D2, D3, D4 Rectification diode IC 3 terminal regulator TR1 and TR2 transistors L relay T contact

Claims (6)

(57) [Claims] 1. A series circuit of a power control element and a rectifier is provided for a commercial power source, a snubber capacitor is connected in parallel with the power control element, and a smoothing capacitor is provided on the output side of the rectifier. A direct current generated by a current flowing through the snubber capacitor when a device control microcomputer that uses a direct current voltage smoothed by a smoothing capacitor as a voltage source is provided and the power control element is in a cutoff state. A power supply device characterized in that the voltage is used as a supply voltage source of a microcomputer during standby. 2. A series circuit of a power control element and a rectifier is provided for a commercial power source, a snubber capacitor is connected in parallel with the power control element, and a smoothing capacitor is provided on the output side of the rectifier. A device control microcomputer having a DC voltage smoothed by a smoothing capacitor as a voltage source is provided, and control means for controlling the opening and closing of a power supply circuit of the device main body by the microcomputer is provided, the control means and the power control element. Power supply device characterized in that when the device main body is put in a standby state by shutting off both of them, a DC voltage generated by a current flowing through the snubber capacitor is used as a supply voltage source of the microcomputer in the standby state. . 3. A series circuit of a power control element and a rectifier is provided for a commercial power source, a snubber capacitor is connected in parallel with the power control element, and a smoothing capacitor is provided on the output side of the rectifier, A power supply device provided with a DC low-voltage power supply for a microcomputer that supplies a DC voltage smoothed by a smoothing capacitor to a device control microcomputer, and provided with control means for controlling the power supply circuit of the device body by the microcomputer. In the above, the opening / closing of the power control element is controlled according to the control signal from the microcomputer, and the conduction angle of the AC power supply is controlled so that the rectified DC output voltage supplied to the microcomputer can be adjusted. Power supply device characterized by. 4. A frequency discriminating means for discriminating the frequency of the commercial power source is provided, and based on the power source frequency discriminated by the frequency discriminating means, even if the power source frequency is different, the DC output voltage of the power control element is made equal. The power supply device according to claim 3, further comprising control means for controlling a conduction angle by a microcomputer. 5. A conduction means for detecting the direct current output voltage of the direct current low voltage circuit, the conduction angle of the power control element so that the direct current output voltage detected by the detection means becomes a predetermined value. The power supply device according to claim 3 or 4, further comprising a control unit that controls the power supply. 6. A predetermined value preset in the microcomputer is increased when the load driven by the DC low-voltage circuit increases when the equipment main body shifts from the standby state to the operating state, and the predetermined value set in the microcomputer is increased. 6. The power supply device according to claim 3, wherein the conduction angle is widened to increase the DC output voltage.