JP2000223284A - Phase control light modulation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the increase of a surge voltage from occurring due to multiple connection of phase control light modulation devices by shifting the off-timing of each of the phase control light modulation devices when a lot of the devices are used by connecting them to the same power source. SOLUTION: This device is so structured that a phase control operation is performed to semiconductor switch elements with control signals synchronized with an A.C. power source E from the outside, and thereby, light modulation is carried out by controlling the phase of the power applied to incandescent lamp loads L (L1-Ln) from the A.C. power source E. In this case, when the multiple phase control light modulation devices and incandescent lamp loads L are connected to the same power source, and the switch elements are controlled with the control signals having the same timing, a protection unit B having a current detection circuit S, a determination circuit CP and a control signal conversion circuit X2 is formed, and the off-timing of each of the phase control light modulation devices is shifted regardless of the control signal when the current flowing through the phase control light modulation device from the A.C. power source E is equal to or more 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 a phase of an AC power supply to control power supplied to a lighting load to perform dimming.

[0002]

2. Description of the Related Art In a phase control light control device that performs light control by controlling the phase of power applied to an incandescent lamp load from an AC power supply in synchronization with an external control signal by using a switch element, which is a semiconductor, at the time of turn-off, The back electromotive force L is determined by the leakage inductance L of the wiring length and di / dt.
Di / dt is generated and applied as a surge voltage to the switch element. Therefore, the surge voltage must be considered when selecting the switch element of the dimmer.

When n dimmers and incandescent lamp loads are connected to the same power supply and they are controlled at the same off-timing, di / dt and the resulting back electromotive force are also multiplied by n, resulting in a surge. Voltage is 1 for dimmer and incandescent lamp load
It increases from the case of pieces.

[0004] In particular, in the case of an apparatus in which overcurrent control is performed by turning off the switch element for an inrush current of 10 times or more of the switch element rating at the time of starting the apparatus, surge voltage due to connection of a large number of apparatuses is reduced. The impact of the increase is very large.

In consideration of this, in the prior art, when a large number of devices are connected, the number of connected light control devices is limited, or a device having a larger withstand voltage of the switch element is used.

[0006]

In order to prevent the elements of the dimmer from being thermally destroyed by the surge voltage caused by the multiple connections, the conventional technology requires a large number of connections.
The number of connected dimmers is limited, and the device withstand voltage is larger than that when only one dimmer and one incandescent lamp load are used. There was a problem that would lead to an increase in the size.

[0007] The present invention has been made in view of this point, and when a plurality of phase control dimmers are connected to the same power supply and used, when a load current is detected and a certain amount of current flows. Regardless of the control signal, shift the turn-off timing of the switch element of each phase control dimmer,
An object of the present invention is to provide an excellent phase control dimmer that does not cause an increase in surge voltage due to multiple connections.

[0008]

In order to achieve the above object, according to the first aspect of the present invention, a dimmer is provided by providing a protection unit having a current detection circuit, a determination circuit, and a control signal conversion circuit. If a large number of power supplies are connected to the same power supply and the load current exceeds the set value (the surge voltage generated by the back electromotive force when off may exceed the withstand voltage of the switch element), It is characterized in that the turn-off timing of each switch element is shifted regardless of the control signal.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a phase control dimmer according to the present invention will be described below with reference to FIGS.

FIG. 1 is a wiring diagram in which an AC power supply, a phase control dimmer and an incandescent lamp load are connected, and FIG. 2 is a detailed view of a switch element and a drive circuit peripheral of each phase control dimmer. . FIG. 3 is a circuit example of a constant power supply circuit of the control signal conversion circuit, and FIG. 4 is a circuit example of a current detection circuit and a determination circuit. FIG. 5 is a timing chart of the circuit operation at the time of lighting.

FIG. 1 shows a phase control dimmer according to the present embodiment.
As shown in FIG.
2,..., An (referred to as A when collectively referred to)
, Ln (collectively referred to as L) are connected, and these are connected to a current detection circuit S, a determination circuit CP, and a control signal conversion circuit. X2 and the protection unit B.

Each of the phase control dimmers A turns on and off the internal switch elements Q1 and Q2 according to a control signal from the control signal conversion circuit X2. The current value flowing from the AC power supply E to the incandescent lamp loads L1, L2,..., Ln is detected by a current detection circuit S, and a determination circuit CP determines whether or not the current value is equal to or greater than a set value. The output H from the determination circuit CP is
Connected to the control signal conversion circuit X2, when the current value is equal to or less than the set value, the same signal as the output of the external control signal generation circuit X1 is output. It is sent to the drive section b of the switch element of the control dimmer A.

In the figure, one control signal (dimming signal) controls a large number of phase control dimming devices, but the control signal (dimming signal) is also controlled for each phase controlling dimming device. May be entered separately.

FIG. 2 is a detailed view of the periphery of the switch element and the drive circuit of the phase control dimmer A. Switch element Q1,
Q2, an element driving power source a for generating driving power for the switching elements Q1 and Q2 from the AC power E, and resistors R1, R2 and R
3 and a photocoupler PC, and has a drive unit b that is turned on / off by an external control signal. The switch element is connected to the output (H) of the control signal conversion circuit X2.
off when the photocoupler PC receives the high signal).
It is turned on when it receives the w signal, and supplies power to the incandescent lamp load L from the AC power supply E when it is turned on.

The switch element of the light control device is selected so as not to cause breakdown even by an inrush current.
A thyristor element such as an IGBT, a bipolar transistor, or a triac may be selected instead of the illustrated MOSFET.

The control signal conversion circuit X2 shown in FIG.
C1, added to the internal monostable multivibrator
, Cn and the constants of R1,..., Rn are set to different values in advance, and generate pulses of different lengths.

The relay RY has one contact connected to the photocoupler PC of the switch element driving unit b, and the other contact connected to a control signal input unit from an external control signal generation circuit X1 and an output of the monostable multivibrator. The switching is performed according to a signal from the determination circuit CP.

With respect to the current detection circuit and the judgment circuit shown in FIG. 4, the current detection circuit is composed of a current transformer CT, a diode bridge DB and a resistor R. Are set in advance assuming whether the switching element will be destroyed by the surge.

The operation during lighting will be specifically described with reference to the timing chart of FIG. As described above, when a large number of dimmers are connected to an incandescent lamp load and the filament of the incandescent lamp load is turned on in a cold state, the inrush current is larger than in the case of a single unit. Therefore, the judgment circuit CP is controlled by the control signal conversion circuit X
2 is switched, and the drive unit b of the switch element of each light control device is turned off by the monostable multivibrator of the control signal conversion circuit X2 as shown in (c) and (d) of FIG. A switch element control signal whose timing is shifted is sent.

As a result, even if a large number of dimmers and incandescent lamp loads are connected, they are simultaneously turned off.
i / dt can be prevented from increasing, and VDS (drain-source voltage) of the switch element as shown in FIG.
The surge voltages 1 and 2 are greatly reduced as shown in FIGS. 6B and 1 when the protection unit B is not provided.

Therefore, it is not necessary to limit the number of dimmers to be connected as in the prior art, or to use a device having a higher breakdown voltage than that of a dimmer and a load used alone. Further, when the filament of the incandescent lamp load warms up and the rush current does not flow, the current detection circuit S stops operating, the contact of the relay RY of the control signal conversion circuit X2 is returned to the original state, and FIG. As shown in (c) and (d), since the control signal (dimming signal) input from the outside is directly input to the drive unit b of the switch element of each dimmer, the actual dimming characteristics are obtained. Is the same as when the dimmer and the load are used alone.

[0022]

As described above, according to the first aspect of the present invention, when a plurality of power supplies are connected to the same power supply, the AC power supply detected by the current detection circuit of the protection unit is applied to the incandescent lamp load. If the current flowing exceeds the set value, the timing of turning off the switch element of each dimmer is shifted regardless of the control signal, so that it is possible to suppress an increase in surge voltage due to the connection of many dimmers. And it is not necessary to use a switch element having a larger voltage rating than the conventional one.

Also, the problem of surge voltage is di /
Since the inrush current in which dt increases becomes a short time at the time of lighting, the control signal conversion circuit does not operate in the steady energized state where the filament of the incandescent lamp load is warmed up. This has the same effect as using a load alone.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a transmission / reception circuit of an ultrasonic sensor according to a first embodiment of the present invention.

FIG. 2 is a detailed view around a drive circuit of a switch element of the phase control dimmer.

FIG. 3 is a circuit example of a constant power supply circuit of the control signal conversion circuit.

FIG. 4 is a circuit example of a current detection circuit and a determination circuit.

FIG. 5 is a timing chart of a circuit operation during lighting.

FIG. 6 is a diagram illustrating a difference in VDS of a switch element between when a protection unit is used and when it is not used.

[Explanation of symbols]

 An phase control dimmer CP determination circuit E AC power supply Ln incandescent lamp load S current detection circuit Q1 switch element Q2 switch element X2 control signal conversion circuit X1 control signal generation circuit RY relay a element drive power supply b driver

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference)

Claims (1)

[Claims] A phase control operation is performed on a switch element, which is a semiconductor, by a control signal synchronized with an external AC power supply,
In a phase control dimmer that performs phase control of power applied to an incandescent lamp load from an AC power supply and performs dimming, a large number of phase control dimmers and incandescent lamp loads are connected to the same power supply, and the same off timing is applied. When the switch element is controlled by the control signal, a protection unit having a current detection circuit, a determination circuit and a control signal conversion circuit is provided, and a current flowing from the AC power supply to the phase control dimmer is equal to or greater than a predetermined value. A phase control dimmer, which shifts off timings of the respective phase control dimmers regardless of the control signal.