JP2000106287A - Mosfet antiphase control dimmer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a MOSFET antiphase control dimmer capable of increasing the load rating of equipment through limitng of rush current. SOLUTION: A phase control dimmer, having a built-in MOSFET part 1 with two MOSFET parts connected in series with an AC power supply E in the opposite directions and a built-in drive power supply part 2 for driving the MOSFET part 1, and subjecting the AC power supply E to antiphase control by means of the MOSFET part 1 for controlling the power supplied to load, is provided with a current detection part 4 for detecting the current flowing in the MOSFET part 1, a comparison circuit part 5 for monitoring the output of the current detection part 4, a transistor 6 connected to the MOSFET part 1, and a timer circuit 7 for operating the transistor 6. When a rush current is detected, the MOSFET part 1 is turned off for a certain time and this action is repeated until the rush current is no longer detected, whereby the on width of a control signal is limited irrespective of the on width, so that the current flowing in the MOSFET part 1 becomes less than a predetermined value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase control dimmer for controlling light supplied to a lighting load by controlling the phase of an AC power supply.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 3, a phase control dimmer 1 that controls the phase of an AC power supply E to control the power supplied to an incandescent lamp load L to perform dimming includes a switching element that has a switching element. One that uses a thyristor element that can be held
Some devices use an arbitrarily extinguishable element such as T. When the current rises, it always becomes zero crossing, and the current surge is reduced compared to a normal phase control circuit.Therefore, the anti-phase control operation that is effective for reducing the electromagnetic noise generated by the phase control device and the humming of the lamp is performed. To do so, a thyristor element that can self-extinguish only with a current of 0 cannot be used.

Therefore, a conventional phase control dimmer using a MOSFET employs an element having a capacity capable of withstanding an inrush current which becomes the largest when the ignition phase is 90 degrees. Therefore, as shown in FIG. 4, the MOSFETs Q1, Q2 and the like are used as switching elements for controlling power and are connected in series and in the reverse direction, one is used for energizing in the positive direction of an AC waveform, and the other is used for energizing in the negative direction. A phase control dimmer 1 that controls a conduction mode and a non-conduction mode by controlling a gate voltage of a switching element using a gate power supply G1 has been a conventional example.

Since the filament of an incandescent lamp has a small resistance at room temperature, an inrush current of 10 times or more the rated value of the incandescent lamp flows at the moment when the current starts to flow to the load, and this state continues until the filament is heated.

In general, MOSFETs have a lower surge current rating than thyristor elements. In addition, since it takes time from the application of the AC power supply to the output voltage of the drive power supply sufficiently rising, when the MOSFET is turned on at the gate voltage just below the threshold, the on-resistance does not become sufficiently small and the current within the rating is not reached. Even if there is, the ON loss may exceed the rating and cause destruction. For this reason, the conventional MOSFET phase control dimmer has a disadvantage that the rated load capacity cannot be increased for the element rating.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a light control device which starts a dimmer regardless of the timing of a lighting signal. When the inrush current at startup exceeds the rating of the MOSFET, the timer circuit operates to turn off the MOSFET for a certain period of time, and this operation is repeated until the load current does not exceed the rating of the MOSFET, so that the filament of the incandescent lamp sufficiently warms up. Until the current stabilizes, the load rating of the dimmer is increased by performing an operation of limiting the ON width so that the current flowing through the MOSFET does not exceed a predetermined value regardless of the ON command width of the control signal. It is an object of the present invention to provide an excellent MOSFET anti-phase control dimmer.

[0007]

According to the first aspect of the present invention, M
A current detection section of the OSFET section, a comparison circuit section for determining whether a signal from the current detection section exceeds the rating of the MOSFET, and two MOSFETs of the MOSFET section;
A transistor connected to the GS terminal of T and a timer circuit for turning on the transistor for a certain period of time and short-circuiting the GS of the MOSFET by a signal of the comparison circuit unit are added to the conventional MOSFET phase control dimmer. When the start switch is turned on, an inrush current flows through the MOSFET section, and the inrush current is applied to the two MOSFETs.
When the rating of T is exceeded, the timer circuit operates to turn off the MOSFET section for a certain period of time, and the load current becomes 2
By repeating this operation until the ratings of the two MOSFETs are no longer exceeded, until the filament is sufficiently heated and the current is stabilized, M
It is characterized in that the current flowing through the OSFET is limited.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a MOSFET according to the present invention will be described.
One embodiment of an anti-phase control dimmer will be described with reference to FIGS.

FIG. 1 is a wiring diagram of a MOSFET anti-phase control dimmer, an AC power supply, and an incandescent lamp load, and FIG. 2 is a timing chart of circuit operation.

The dimmer shown in FIG. 1 has a MOSFET section 1 as a main switch, and a MOS of the MOSFET section 1.
A drive power supply unit 2 for applying a voltage between the GS of the FETs Q1 and Q2, and a MOSFET Q of the MOSFET unit 1;
1, a current detection unit 4 for detecting a drain current flowing through Q2 as a voltage, a comparison circuit unit 5 for monitoring the output of the current detection unit 4, and an overcurrent signal of the MOSFET unit 1 from the comparison circuit unit 5. And 2 of the MOSFET section for a certain period
The transistor Tr2 connected to the GS terminal of the two MOSFETs is turned on, and the MOSFET
A timer circuit for short-circuiting the GS of TQ1 and Q2 to turn off the MOSFET section 1;
A transistor Tr for turning on / off the SFET unit 1
1 is a main configuration.

When the start switch SW1 is turned on, the M
In order to drive the MOSFETs Q1 and Q2 of the OSFET section 1, the drive power supply section 2 requires a certain amount of time, and outputs a voltage sufficient to prevent ASO breakdown even when a rated drain current flows. However, since the start switch is turned on at an arbitrary timing, the time required to reach a predetermined voltage is not constant.

The MOSFETs Q1 and Q2, which are turned on at the time of 0V, supply an incandescent lamp load L with an on-current that rises in a sine curve according to a control signal.

At this time, since the filament of the incandescent lamp is not heated, the resistance value becomes small, and an inrush current is generated.

The value of the current flowing through the incandescent lamp load L is determined by the current detecting section 4 comprising a current transformer CA and a full-wave rectifier circuit DB, etc., so that the comparator CP2 of the comparing circuit section 5 If it is determined that this is the case, the signal is output to the timer circuit 7 immediately upon receiving the signal. When the timer circuit 7 receives a signal from the comparison circuit section 5, the timer circuit 7
The transistor Tr2 connected to the GS terminals of the two MOSFETs in the T section is turned on, and the GS of the MOSFETs Q1 and Q2 of the MOSFET section 1 is short-circuited.
The OSFET unit 1 is turned off.

The timer circuit 7 terminates its operation, turns off the transistor Tr2, and again receives a control signal from the transistor Tr1 so that the MOSFET Q
1, the GS of Q2 is short-circuited,
If the filament of the incandescent lamp is not sufficiently heated when turning on the lamp, an overcurrent will flow though not as much as at the beginning. This operation is performed by setting the inrush current to the MOSFET Q
The operation is continued until the current becomes equal to or less than the rated current of the first and second transistors Q2. The time during which the timer circuit 7 turns on the transistor Tr2 may be any time, and it is not particularly necessary to synchronize with the AC power supply E.

[0016]

As described above, the MO according to claim 1 is used.
In the SFET phase control dimmer, even if the 0V detection circuit and the power supply voltage comparison circuit are not provided, the inrush current
Of the conventional MOS
There is an effect that a load rating larger than that of the FET dimmer can be set.

[Brief description of the drawings]

FIG. 1 is a wiring diagram of an anti-phase control dimmer, an AC power supply, and an incandescent lamp load according to a first embodiment of the present invention.

FIG. 2 is a timing chart of a circuit operation of the anti-phase control dimmer.

FIG. 3 is a wiring diagram of a conventional phase control dimmer capable of performing an inverse phase control operation using a MOSFET or the like as a switch element, an AC power supply, and a load.

FIG. 4 is a detailed circuit diagram of a conventional phase control dimmer capable of performing an inverse phase control operation using a MOSFET or the like as a switch element.

[Explanation of symbols]

 Reference Signs List 1 MOSFET section 2 Drive power supply section 4 Current detection section 5 Comparison circuit section 6 Control section 7 Timer circuit E AC power supply Q1 MOSFET Q2 MOSFET L Incandescent lamp load Tr2 transistor CA Current transformer DB Full-wave rectifier circuit

Claims (1)

[Claims] A MOSFET section having two MOSFETs connected in series and in opposite directions to an AC power supply;
A phase control dimmer incorporating a power supply unit having a power supply for driving an OSFET unit and the like, and controlling the power supplied to an incandescent lamp load by controlling an AC power supply in an opposite phase by the MOSFET unit. Two MOs
A current detection unit for detecting a drain current flowing through the SFET as a voltage, a comparison circuit unit for monitoring the output of the current detection unit, and GS of two MOSFETs of the MOSFET unit
A transistor connected to a terminal; and a timer circuit for operating the transistor in accordance with a signal from the comparison circuit unit, wherein the inrush current at the time of startup is reduced by the two MOSFETs.
When the rating of T is exceeded, the timer circuit operates to turn off the MOSFET section for a certain period of time, and this operation is repeated until the rush current does not exceed the rating of the two MOSFETs. A MOSF, wherein the ON width is limited so that the current flowing through the MOSFET section does not exceed a predetermined value irrespective of the ON command width of the control signal until the current is stabilized.
ET antiphase control dimmer.