JPH0762811B2 - Power supply circuit - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply circuit that keeps the amount of heat generated by a load constant regardless of the magnitude of the power supply voltage.

Conventional technology Conventionally, for example, when using heat equipment such as iron and hand steamer in Japan, 100 V power supply, when using in Europe etc. 220 V power supply When using the same set in Europe etc. As described in Japanese Patent Application Laid-Open No. 60-194787, all the voltages are applied when the voltage of the commercial AC power supply is low, and when the voltage is high, a selection switch is used by the relay of the voltage determination circuit. There is a type which automatically opens and closes, or a type which switches between full voltage application and a phase control system by a semiconductor switching element as described in JP-A-58-207117.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In such a conventional power supply device, when the commercial AC power supply voltage is high, the commercial AC power supply does not turn on and off at the zero volt phase, so that large noise occurs, and as a countermeasure against this, a large choke coil is used. It required a condenser, etc., and was very bulky and heavy.

The present invention solves the above-mentioned problems of the related art, and it is possible to obtain specified power even when the power supply voltage is different, in particular, when the power supply voltage is high, generate no noise, and can be configured in a small scale. It can be installed in the inside and is easy to carry.

Means for Solving the Problems In order to solve the above problems, the present invention includes a voltage detection unit that detects a voltage of a commercial AC power supply, a timer unit that outputs a high level voltage and a low level voltage at a constant cycle, A zero volt detector for detecting zero volt of the commercial AC power supply, a first switching unit for inputting the outputs of the voltage detector and the zero volt detector, and an output of the timer unit, and an input for the first switching unit A second switching unit that controls the voltage applied to the load, wherein the first switching unit outputs the output of the zero volt detection unit to the second when the voltage of the commercial AC power source is lower than a predetermined voltage. Output to the switching section of the commercial AC power supply, when the voltage of the commercial AC power supply is higher than a predetermined voltage, the voltage of the output of the zero volt detection section is controlled by the output of the timer section. It is configured to output to the second switching unit.

Effect of the Invention With the above-described configuration, when the commercial AC power supply voltage is lower than the predetermined voltage, the second switching section is turned on for the entire period, and when it is higher than the predetermined voltage, the non-conduction period is provided according to the voltage. The power supply to the load is controlled to be constant, and the on / off points are controlled by the output of the zero volt detection unit so that the second switching unit can be turned on / off at the zero volt phase of the commercial AC power supply.

Embodiment FIG. 1 is a block diagram showing an embodiment of the power supply circuit of the present invention.

In FIG. 1, 1 is a commercial AC power supply, 2 is a voltage detection unit that detects the voltage of the commercial AC power supply 1, 3 is a timer unit, which has a high level at a constant cycle according to the voltage of the commercial AC power supply 1,
Outputs low level voltage. Reference numeral 4 is a second switching unit that controls energization of the load 5. Reference numeral 6 denotes a zero volt detection unit that detects zero volt of the commercial AC power supply 1. Ten
Is a first switching unit which inputs the outputs of the voltage detection unit 2 and the zero volt detection unit 6 and the output of the timer unit 3, and outputs the output of the zero volt detection unit 6 when the voltage of the commercial AC power supply 1 is lower than a predetermined voltage. Is output to the second switching unit 4, and when the voltage is higher than a predetermined voltage, the voltage obtained by controlling the output of the zero volt detection unit 6 with the output of the timer unit 3 is output to the second switch unit 4. The timer unit 3 is a commercial AC power supply 1
When the voltage of 2 is doubled, the conduction period 1 is changed to the non-conduction period 4. The load 5 is a heater in this embodiment.

In FIG. 2, (A) is the output voltage of the timer unit 3,
(B) is a voltage waveform across the load 5. In FIG. 2A, the output of the timer unit 3 is at a high level during the time t ₁ , the second switching unit 4 is turned on, and a current is passed through the load 5. During the time t _2, the output of the timer unit 3 is the low level and the second
The switching unit 4 is off, and no current flows through the load 5. The times t ₁ and t ₂ are set according to the magnitude of the power supply voltage (120V, 220V, etc.).

FIG. 3 shows a specific circuit example of the present invention. In FIG. 3, the same parts as those in FIG. 1 are designated by the same reference numerals, and the description of the configuration is omitted, and the operation will be mainly described below. The voltage detection unit 2 divides the power supply voltage V _AC into resistors R ₃ and R ₄ , and
DC voltage e ₁ is obtained by D ₆ , resistor R ₅ , and capacitor C ₁ . The DC voltage e ₁ is input to the comparator composed of IC ₁ , and the resistance R ₁₀ ,
It is compared with the reference voltage e _ref composed of the Zener diode ZD ₁ . When the power supply voltage V _AC is low (for example, 100 V), the DC voltage e ₁ is also low and becomes lower than the reference voltage e _ref , and the output of the comparator IC ₁ is at a high level. On the contrary, if the power supply voltage V _AC is high (for example, 220 V), the output of IC ₁ is low level. Then, the output of IC ₁ is input to the first switching unit 10. Then the timer unit 3 is not progressed in the capacitor C _2, when the terminal voltage of the capacitor C ₂ is low, the output voltage of the IC ₂ is a high level, the output voltage of the IC _2, the diode D
₈ , the capacitor C ₂ is charged through the resistor R ₁₂ , and the time is determined by C ₂ × R ₁₂ . The terminal voltage of capacitor C ₂ is I
IC determined by output voltage of C ₂ and resistors R ₁₅ , R ₁₄ and resistor R _11
When the + terminal voltage of ₂ is exceeded, the output of IC ₂ is inverted to the low level, the + terminal voltage of IC ₂ becomes small, and the capacitor C ₂
The charge of is discharged until the voltage of the terminal of C ₂ becomes equal to the voltage of the + terminal of IC ₂ , which has become lower. Discharge current is a capacitor
It flows through C ₂ , resistor R ₁₃ , and diode D ₉ , and the discharge time is C
It is determined by ₂ × R ₁₃ . As described above, the high level time of the output of IC ₂ is determined by R ₁₂ × C ₂ and the low level time is determined by R ₁₃ × C ₂ . Then, the output of IC ₂ is input to the first switching unit 10. In addition, the diode D ₁ ~
D ₄ , the transistors Q ₁ and Q ₂ , the resistors R ₁ and R _{6 to} R ₉ constitute the zero-volt detection unit 6 of the commercial AC power supply 1, and generate a pulse voltage when the commercial AC power supply 1 is at zero voltage. The pulse voltage is output to the first switching unit 10.

The output voltage e ₂ of the first switching unit 10 is the voltage detection unit 2
When the output voltage of is high level (when the power supply voltage V _AC is low), it is high level regardless of the output of the timer unit 3, and when the output voltage of the voltage detection unit 2 is low level (the power supply voltage V AC
_{When AC} is high, it becomes the output of the timer unit 3 and high-level and low-level voltages appear at a constant cycle according to its size. The second switching unit 4 includes a bidirectional SCRQ ₄ and a bidirectional SRQ _4.
It is composed of a resistor R ₁₈ for flowing a gate current of CRQ ₄ , a transistor Q ₃ , a diode D ₁₃ , and resistors R ₁₆ , R ₁₇ for flowing a base current to the transistor Q ₃ . Therefore, when the input voltage e ₂ is high level, the transistor Q ₃ turns on and the bidirectional SCRQ
₄ turns on and flows to load 5. Q when e ₂ is low
₃ is off, Q ₄ is off, and no current flows through load 5.

With the above configuration, when the power supply voltage V _AC is low, the bidirectional SCRQ ₄
Is always on, and when the power supply voltage V _AC is high, the output of the timer unit 3 is at high level, the bidirectional SCRQ ₄ is on, and at low level, the bidirectional SCRQ ₄ is off. Further, the zero volt detection unit 6 detects the zero-cross point of the power supply voltage V _AC , and only at that time, the gate current is supplied to the bidirectional SCRQ ₄ , and the bidirectional SCR is detected.
On the Q _4, off performed at zero level near the V _AC, which makes it possible to reduce the suppressed and consumption current generation of noise. The resistor R ₂ and diode D ₅ are connected to the AC power supply V _AC.
Of the electrolytic capacitor C ₃ is for smoothing, and the Zener diode ZD ₂ is for making the voltage constant, and forms a DC power supply for driving the electronic circuit section. .

FIG. 4 shows a diagram in which a hand steamer is connected to the output terminals P1 and P2 of the bidirectional SCRQ ₄ . 7 is a hand steamer. 8
Is a temperature control thermo-switch for controlling the load 5 which is a heater, and 9 is a neon lamp connected in parallel with the load 5.
It lights up when a voltage is applied to the load 5. In the case of FIG. 4, when the power supply voltage is low and the bidirectional SCRQ ₄ is turned on, the neon lamp 9 is continuously turned on when the thermoswitch 8 is turned on, and when the power supply voltage is high, the neon lamp 9 responds to the output cycle of the timer unit 3. The neon lamp 9 blinks, and it is possible to determine whether the power supply voltage is low or high.

As mentioned above, the circuit effective for two kinds of power supply when the power supply voltage is high and when the power supply voltage is low has been described. However, the number of circuit parts that detect the magnitude of the power supply voltage is further increased, and the timer part also has the number of detection stages of the power supply voltage. By increasing the number accordingly, the circuit becomes effective for three or more types of power supply voltage.

As described above, according to the present invention, when the commercial AC power supply voltage is lower than the predetermined voltage, the output of the zero volt detection unit is output to the second switching unit that controls the voltage applied to the load. When the voltage is higher than a predetermined voltage, the voltage obtained by controlling the output of the zero volt detection unit with the output of the timer unit is used as the second voltage.
When the commercial AC power supply voltage is lower than a predetermined voltage, the second switching unit is turned on for the entire period, and when it is higher than the predetermined voltage, a non-conduction period is provided according to the voltage. The power supply to the load can be controlled at a constant level, and the second switching unit can be turned on and off at the zero volt phase of the commercial AC power supply, so noise can be prevented, and a power supply with different power supply voltages can be used with an extremely simple circuit configuration. Even in this case, a constant energization control can be obtained, which is extremely useful in practice.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a waveform diagram showing an output voltage waveform of a timer circuit section and a voltage waveform applied to a load, and FIG. 3 is a specific example of the present invention. FIG. 4 is a circuit diagram of a hand steamer. 1 ... Power supply voltage, 2 ... Voltage detection section, 3 ... Timer section, 4 ... Second switching section, 5 ... Load, 6 ...
Zero-volt detector, 10 ... First switching unit.

Claims (1)

[Claims] 1. A voltage detection unit for detecting a voltage of a commercial AC power supply, a timer unit for outputting a high level voltage and a low level voltage at a constant cycle according to the voltage of the commercial AC power supply, and a commercial AC power supply. A zero volt detection unit that detects zero volt, a first switching unit that inputs the outputs of the voltage detection unit and the zero volt detection unit, and an output of the timer unit, and an output of the first switching unit that is input and applied to a load. A second switching unit for controlling the voltage,
The first switching unit outputs the output of the zero-volt detection unit to the second switching unit when the voltage of the commercial AC power supply is lower than a predetermined voltage, and the voltage of the commercial AC power supply is lower than the predetermined voltage. A power supply circuit configured to output a voltage obtained by controlling the output of the zero volt detection unit by the output of the timer unit to the second switching unit when the voltage is high.