JP2005327607A - Phase control type light modulation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate trouble of becoming impossible to modulate light when an inverter circuit such as an electronic transformer is connected, instead of an incandescent lamp, as a load to a phase control type light modulation device. <P>SOLUTION: This light modulation system is so structured that the phase control type light modulation device connected to a commercial power source is combined with an inverter operated by an A.C. voltage phase-controlled by the light modulation device. A capacitive circuit, a full-wave rectification circuit and a trigger circuit connected to the output of the full-wave rectification circuit are incorporated in the inverter; the trigger circuit has a structure which is operated to start oscillation of the inverter when the input voltage of the inverter is set at a predetermined voltage Vt; and, when it is assumed that the instantaneous voltage of the commercial power source at the minimum conduction angle in the phase control of the light modulation device is Vp, Vp>Vt is satisfied. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a phase control type dimming system that controls output by phase control.

  A conventional phase control type dimming system includes a commercial power source 1, a dimming device 2, and a load 3, as shown in FIGS. 6 (a), 6 (b), and 6 (c). The commercial power source 1 is an AC 100V of 50 Hz or 60 Hz, and is a power source supplied by two lines. The dimmer 2 is connected to the commercial power source 1 and the load 3. The load 3 is generally an incandescent bulb. There are basically three ways of connection of the light control device 2 as shown in FIGS. 6 (a), 6 (b) and 6 (c).

  The light control device 2 is a phase control type light control device, and performs phase control by a switching element such as a triac. More specifically, for example, a circuit as shown in FIG. The light control device 2 operates according to the phase angle of the power supply voltage. When the power supply voltage reaches a set phase angle, a trigger signal is applied from the phase detection circuit to the switch element Q, and the switch element is turned on (conductive). Once the switch element Q is turned on and a current flows, the switch element Q is kept on while the current flows. However, when the power supply phase advances and the current flowing through the switch element Q becomes equal to or less than the holding current, the switch element Q is turned off. When the power supply phase further advances and reaches a preset phase angle, the trigger signal Tp is applied to the switch element Q, and the switch element Q is turned on. By such an operation, the voltage between the terminals B and B 'becomes as shown by Vb in FIG. Va represents the waveform of the commercial power source 1 between the terminals A and A ′. By changing a certain set phase angle, the effective value of the voltage Vb applied to the load changes, and dimming can be performed.

There are two types of trigger signal waveforms: a pulse trigger method indicated by Tp in FIG. 8 and a solid trigger method indicated by Tb in FIG. In general, the connection type dimming device shown in FIG. 6A using an incandescent lamp as a load uses a pulse trigger method. However, the dimming device using an electronic transformer as a load, as shown in FIGS. 6B and 6C, or FIG. A solid trigger method is used for the light control device of the connection method.
JP 2001-126879 A

  The conventional phase control dimming system uses a solid trigger method when an inverter circuit such as an electronic transformer is used as a load. However, due to the characteristics of the triac used for the phase control switch element, the dimming is limited. Depending on the size of the load connected to the electronic transformer, there may be a problem that the light cannot be dimmed.

  The present invention has been made for the purpose of eliminating problems that occur when an inverter circuit such as an electronic transformer is connected as a load in place of an incandescent bulb to a phase control type dimmer using a triac or the like. It is.

  In the phase control type dimming system of the present invention, in order to solve the above problems, a phase control type dimming device connected to a commercial power source and an AC voltage phase-controlled by the dimming device. In a dimming system combined with an operating inverter, the inverter includes a capacitive circuit, a full-wave rectifier circuit, and a trigger circuit connected to the output of the full-wave rectifier circuit. When the input voltage of the power source becomes the predetermined voltage Vt and starts oscillating the inverter, the instantaneous voltage of the commercial power supply at the minimum conduction angle in the phase control of the dimmer is Vp> Vp> It is characterized by being Vt.

  According to the first aspect of the present invention, the peak voltage of the minimum dimming level of the phase control type dimming device is configured to be higher than the starting voltage of the inverter serving as a load, so that it becomes capacitive at light load. It has become possible to provide a dimming system capable of dimming even with an inverter circuit as a load. In addition, according to the invention of claim 3, it is possible to provide a dimming system capable of dimming even when an inverter circuit that becomes capacitive at light load is used as a load by increasing the timing at which the solid trigger is turned off. It was. Further, according to the inventions of claims 2 and 4, it is possible to provide a dimming system capable of dimming with either an incandescent bulb that is always a resistive load or an inverter circuit that is capacitive at light load as a load. became.

(Embodiment 1)
FIG. 1 shows Embodiment 1 of the present invention. The light control device 2 includes a commercial power source 1, a light control device 2, and a load 3. The light control device 2 uses a triac as a switch element Q and further includes a choke coil L and a capacitor C to form a filter circuit. Further, the lower limit level of dimming can be switched by the switch SW1. The load 3 is an electronic transformer, and includes a power supply filter 4, a rectifier 5, a trigger circuit 6, an oscillation circuit 7, and a lamp 8. The oscillation circuit 7 oscillates at several tens of KHz and supplies power to the lamp 8 via the output transformer Tf. Although the load 3 constitutes an inverter but does not have a smoothing circuit, oscillation stops every cycle (a time half the cycle of the commercial power supply). Then, the oscillation is started by the trigger circuit 6 every cycle. The trigger circuit 6 is configured to instantly generate a trigger pulse when the input voltage exceeds a certain voltage Vt, thereby starting the oscillation of the inverter.

  The configuration of the trigger circuit 6 is not limited to the illustrated one, but when the output voltage of the rectifier 5 (voltage between terminals CC ′) becomes substantially zero, the charge of the capacitor Ct is discharged through the diode D3. . When the output voltage of the rectifier 5 (voltage between terminals CC ′) rises from this state, the trigger element Qt breaks over when the predetermined voltage Vt is reached, and the capacitor Ct and the trigger element Qt are connected. A trigger pulse is applied to the control electrode of the switching element Q2 of the oscillation circuit 7. Thereby, the oscillation circuit 7 starts a self-excited oscillation operation.

  In the present embodiment, a half-bridge inverter circuit is used as the oscillation circuit 7. The output voltage of the rectifier 5 (voltage between terminals CC ′) is applied to the series circuit of the capacitors C1 and C2 and the series circuit of the switching elements Q1 and Q2, and the connection point between the capacitors C1 and C2 and the switching element Q1. , Q2 is connected between the primary windings of the output transformer Tf. A lamp 8 is connected to the secondary winding of the output transformer Tf. The switching elements Q1 and Q2 are driven to self-oscillate so as to be alternately turned on by a current feedback circuit (for example, a current feedback transformer) (not shown). That is, when a trigger pulse is applied to the control electrode of the switching element Q2 by the trigger circuit 6, the switching element Q2 is turned on, and thereafter, the switching elements Q1 and Q2 are turned on alternately. When the output voltage of the rectifier 5 (voltage between terminals C and C ′) becomes equal to or lower than the oscillation maintaining voltage, the self-excited oscillation operation of the oscillation circuit 7 is stopped. Here, a half-bridge type inverter circuit is illustrated as the oscillation circuit 7, but an inverter circuit having another configuration, for example, a push-pull type inverter circuit may be used.

  Since the operation of the phase control is the same as that of the conventional example, the description is omitted, but the waveforms of the respective parts when the light is normally adjusted are shown in FIG. Va represents the waveform of the commercial power supply. Vb represents a phase-controlled voltage waveform. Ib is a current flowing through the dimmer 2. In this embodiment, the current vibrates by the power filter 4 of the load 3 and the choke coil L of the dimmer 2, and the current is below the zero level and reversed. It is shown. If the triac Q gate trigger is not applied, the triac Q is turned off. However, as shown by Vg in FIG. Triac Q remains ON. Vc represents a voltage waveform in which the phase-controlled voltage is full-wave rectified through the rectifier 5 of the load 3. Assuming that the instantaneous value of the voltage applied when the triac Q of the dimmer 2 is turned on is Vp, the trigger circuit 6 operates when Vp is greater than Vt, the trigger signal is applied to the oscillation circuit 7 and oscillation starts. The Vd represents the output voltage of the oscillation circuit 7.

  Now, if the effective value of the voltage applied to the load 3 is reduced by adjusting the dimming phase angle, there is a point where Vp becomes smaller than Vt. The waveform of each part in this case is as shown in FIG. Va represents the waveform of the commercial power supply. Vb is a phase-controlled voltage waveform, and the triac Q gate trigger signal Vg is applied at the set phase, and the triac Q is turned ON. However, since Vp is less than Vt, as indicated by Vd, the oscillation circuit 7 of the load 3 does not oscillate at this time. When the oscillation circuit 7 of the load 3 does not oscillate, the load 3 becomes a capacitive load when viewed from the dimming device 2, and a phase advance current flows through the current Ib. Accordingly, as indicated by Ib in FIG. 3, a current having the same phase as the voltage once flows, but since the oscillation of the load 3 does not start, a phase-advancing current is generated and a current in the reverse direction flows. During this time, since the gate trigger signal indicated by Vg is applied, the triac Q is kept ON. Here, when a reverse current flows, the phase advance current becomes the holding current of the triac Q in the next half cycle, and the triac Q is kept ON. As a result, since the voltage exceeding Vt is applied to the load 3 in the next half cycle, the oscillation starts and the lamp 8 is lit.

  However, once the lamp is turned on, the load 3 becomes a resistive load this time, so that the oscillation is stopped in the half cycle. Thus, if dimming is reduced and Vp becomes smaller than Vt, a half-wave lighting state may occur. Therefore, when an electronic transformer is used as a load, the switch SW1 is switched so that Vp does not become lower than Vt even when dimming is reduced. Then, the above problem of half-wave lighting is eliminated.

  According to the present invention, when an electronic transformer is used as a load, the switch SW1 that limits the dimming level of the dimmer 2 is switched and set so that Vp does not become smaller than Vt. Even in this case, it is possible to provide a dimming system that does not light half a wave. When an incandescent lamp is used as a load, the output can be reduced to a sufficiently small level by not returning the switch SW1 to the original state and limiting the dimming level of the dimming device 2. The same effect can be obtained by setting Vt on the electronic transformer side as a load lower than Vp.

(Embodiment 2)
A second embodiment of the present invention is shown in FIG. Although the basic configuration is the same as that of the circuit of FIG. 1, in this embodiment, a current detection circuit 9 is provided, and the switch SW1 for switching the lower limit level of dimming can be automatically switched. ing. Since the phase control operation is the same as that of the conventional example, description thereof is omitted. Moreover, the waveform of each part at the time of normal light control is the same as Embodiment 1, and is as showing in FIG.

  Now, if the power consumption of the lamp 8 connected to the electronic transformer is changed to a small one, the resistance of the electronic transformer becomes small, and it approaches a relatively capacitive load. When the lamp 8 connected to the electronic transformer falls below a certain power consumption, the waveform of each part becomes as shown in FIG. This is because when the load 3 approaches the capacitive load, the phase of the current Ib advances with respect to the voltage Vb, and as a result, the zero cross point of the current becomes earlier than the zero cross of the voltage.

  In the case of the solid-trigger type light control device, the gate trigger signal Vg is applied to a position close to the zero cross of the voltage Va (about 500 μsec before the zero cross point). As shown in FIG. 3, the current Ib passes through the zero cross while the gate trigger signal Vg is still applied. Then, the triac Q cannot be turned off, and the next half cycle is kept on. For this reason, the electronic transformer oscillates and the lamp 8 is also lit, but since the power consumption of the load 3 is small, the current Ib is also a phase advance current, and the triac Q cannot be turned off at zero crossing. Therefore, regardless of the dimming level, in this case, all lighting is maintained, and dimming cannot be performed.

  Therefore, when a peak current characteristic of the electronic transformer is detected by the detection circuit 9 and the electronic transformer is connected as the load 3, the timing for turning off the output of the solid trigger is cut earlier than usual (for example, 1 ms at the zero cross point). Cut more than about). Then, the problem of being in a fully lit state as described above is solved.

  According to the present invention, the peak current characteristic of an electronic transformer combining a self-excited oscillation circuit and a high-frequency transformer is detected, and the timing for turning off the solid trigger of the dimmer is made earlier than usual. It has become possible to provide a dimming system that does not cause a malfunction that would result in full lighting.

It is a circuit diagram of Embodiment 1 of the present invention. It is a wave form diagram for operation | movement description of Embodiment 1 of this invention. It is a wave form diagram for operation | movement description of Embodiment 1 of this invention. It is a circuit diagram of Embodiment 2 of the present invention. It is a wave form diagram for explanation of operation of Embodiment 2 of the present invention. It is a block circuit diagram which shows the structure of the light control system of a prior art example. It is a circuit diagram of the light modulation apparatus used for a prior art example. It is a wave form diagram for operation | movement description of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC power supply 2 Light control device 3 Load 4 Power supply filter 5 Rectifier 6 Trigger circuit 7 Oscillation circuit 8 Lamp 9 Detection circuit

Claims (6)

In a dimming system in which a phase control type dimming device connected to a commercial power source and an inverter operated by an AC voltage phase-controlled by the dimming device are combined, the inverter includes a capacitive circuit and A trigger circuit connected to the full-wave rectifier circuit and the output of the full-wave rectifier circuit is built in, and the trigger circuit operates when the input voltage of the inverter reaches a predetermined voltage Vt and starts oscillation of the inverter. A phase-controlled dimming system characterized in that Vp> Vt, where Vp is the instantaneous voltage of the commercial power supply at the minimum conduction angle in the phase control of the dimming device. 2. The phase control type adjusting device according to claim 1, wherein when the load connected to the dimming device is an incandescent lamp, the dimming device includes a changeover switch that switches a minimum conduction angle so that Vp <Vt. Light system. In a dimming system in which a phase control type dimming device connected to a commercial power source and an inverter operated by an AC voltage phase-controlled by the dimming device are combined, the gate of the phase control type dimming device The trigger is a solid trigger method in which a time trigger voltage is output while the light control device is on. The inverter has a built-in capacitive circuit, and multiple types of loads can be connected to the inverter. The timing at which the trigger voltage does not appear even when the deviation between the zero cross point of the voltage applied to the light control device side and the zero cross point of the current is maximized is configured not to be later than the zero cross point of the current. A phase control dimming system characterized by the above. 4. The phase control type dimming system according to claim 3, wherein the phase control type dimming device is provided with a changeover switch for switching the timing on the power supply phase angle at which the gate trigger voltage is not generated. 5. The electronic transformer according to claim 2 or 4, wherein an electronic transformer combining a self-excited oscillation circuit and a high-frequency transformer is used as an inverter that operates with an AC voltage phase-controlled by the dimmer, and the peak current peculiar to the electronic transformer is detected. A phase control dimming system provided with a detection circuit for automatically switching a changeover switch. 5. The phase control type dimming system according to claim 4, wherein the timing on the power supply phase angle at which the gate trigger voltage is not generated differs according to the connected load.

Images