JP2868224B2 - Load control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load control device that outputs a high-frequency voltage with low low-frequency ripple using a commercial power supply as an input.

[Prior Art] FIG. 9 shows a conventional load control device (Japanese Patent Application Laid-Open No. 60-134776,
FIG. 2 is a circuit diagram of JP-A-60-139175). In the figure, the upper part shows the main circuit part, and the lower part shows the control circuit part,
The parts denoted by the symbols are connected to each other. In this load control device, a chopper circuit is provided on the DC input side of an inverter circuit that supplies a high-frequency current to the load, thereby improving the input power factor and reducing the input current harmonic distortion. The configuration of the main circuit section is simplified by also using the switching element.

First, the configuration of the main circuit unit will be described. The commercial AC power supply Vs is connected to an AC input terminal of the diode bridge DB via a filter circuit including capacitors C ₁ and C ₂ and a transformer T ₁ . Between the DC output terminals of the diode bridge DB, inductor L ₁ is connected via a switching element Q ₂ to which consisting power MOSFET. At both ends of the switching element Q _2, via the diode D ₁ smoothing capacitor
C ₃ is connected, thereby, the booster chopper circuit is constituted. That is, when the switching element Q ₂ is turned on, a current flows from the DC output terminals of the diode bridge DB in the inductor L _1, the electromagnetic energy in the inductor L ₁ is accumulated, the switching element Q ₂ is turned off, the inductor L ₁ solenoid electromotive force is generated in a direction to keep a current flows across the inductor L ₁ by the energy, the electromotive force is added to the DC output voltage of the diode bridge DB,
It is charged in the smoothing capacitor C ₃ through the diode D _1.
Therefore, the smoothing capacitor C ₃ diode bridge DB
Is charged by boosting the DC output voltage.

Next, the configuration of the inverter circuit will be described. A series circuit of switching elements Q ₁ and Q ₂ composed of power MOSFETs is connected in parallel to both ends of the smoothing capacitor C ₃ , and a diode is connected to each of the switching elements Q ₁ and Q _2.
D ₁ and D ₂ are connected in anti-parallel. At both ends of the switching element Q _2, the DC component capacitor C ₄ for cutting the power supply side terminal of the filament of the discharge lamp La via the inductor L ₂ of the current limiting is connected. Between the discharge lamp La of the non-power supply side terminal of the filament, the capacitor C ₅ for preheating current supply are connected in parallel, the capacitor C ₅ constitute the inductor L ₂ and the series resonance circuit. Capacitance of the capacitor C ₄ is sufficiently larger than the capacitance of the capacitor C _5, it does not contribute to the resonance. In a control circuit section described later, a drive signal for turning on and off the switching elements Q ₁ and Q ₂ alternately is generated,
Supply between terminals, between and between terminals. When the switching element Q ₁ is turned on, the switching element Q ₂ is turned off, the switching element Q ₁ from the smoothing capacitor C _3, the capacitor C _4, a current flows through the discharge lamp La via the inductor L _2, a capacitor C ₄ is charged . Next, when the switching element Q ₁ is off, the switching element Q ₂ is turned on, the capacitor C ₄ is a power supply, a current flows from the capacitor C ₄ via the switching element Q _2, the discharge lamp La, the inductor L _2, a capacitor C ₄ is discharged. The switching elements Q ₁ ,
Q ₂ is generally providing the dead-off time to turn off at the same time, this time, oscillating current in the load circuit will flow through the diode D _1, D _2. Switching element
The switching frequency of Q ₁ and Q ₂ depends on the discharge lamp La and the inductor.
L ₂ and be set slightly higher than the resonant frequency of the load circuit including the capacitor C ₅ is common, thereby a current delay phase flows through the load circuit, the switching element
Switching of Q ₁ and Q ₂ is performed stably. The high voltage is generated by resonance action at both ends of the capacitor C _5, which is applied to the discharge lamp La, the discharge lamp La is lighted.

Thus, in the circuit, since the diode D ₁ and the switching element Q ₂ is also used with the chopper circuit and the inverter circuit, the configuration of the main circuit portion is simplified, also, the inverter circuit drive signal of the chopper circuit Since it is not necessary to create the drive signal separately from the drive signal, the configuration of the control circuit unit is also simplified.

Hereinafter, the configuration of the control circuit unit will be described. This circuit consists of the oscillation circuit IC ₁ and the driver circuit IC ₂ Prefecture. First, the oscillation circuit IC ₁ is composed of a control IC for a switching regulator (μPC494C manufactured by NEC Corporation). As is well known, this control IC is used with a control power supply Vcc applied between a power supply terminal (pin 12) and a ground terminal (pin 7), and is used between a capacitor terminal (pin 5) and a ground terminal. The capacitor C ₁₁ connected to and the resistor terminal (Pin 6)
Has a built-in oscillator that oscillates at a frequency corresponding to the time constant of the resistor R ₁₁ connected between the ground terminal and. The first oscillation output is the first open collector terminal (8th pin)
And a first open emitter terminal (Pin 9) are obtained by alternating between a short-circuited state and an open state, and a second oscillation output is obtained by a second open collector terminal (Pin 11). It is obtained by alternating between a short-circuited state between the circuit and the second open emitter terminal (the 10th pin) and an open state. Here, when the output control terminal (the 13th pin) is dropped to the ground level, a single-ended operation for one stone is performed, and the first oscillation output coincides with the second oscillation output. When the control terminal is set to the level of the reference voltage Vref obtained from the reference voltage output terminal (the 14th pin), push-pull operation for two switches is performed, and the first oscillation output and the second oscillation output are set to a predetermined dead time. After the off-time, the opposite situation takes place. The dead-off time, and the level of the reference voltage Vref dividing by a variable resistor VR _11, by inputting the dead-off time control terminal (pin 4) can be set. The non-inverting input terminals (pins 1 and 16) and the inverting input terminals (pins 2 and 15) are input terminals of a comparator for pulse width control. Is to pull down the former to the ground level and pull up the latter to the level of the control power supply Vcc. The feedback terminal (3rd pin) is a feedback input terminal for pulse width control, and is left open when not used.

In this embodiment, first and second open emitter terminal (9 pin, 10 pin) is pulled down to ground level via the resistors R _13, R _12. Therefore,
The first open emitter terminal (Pin 9) is at “Low” level when not conducting with the first open collector terminal (Pin 8), and is “High” when conducting.
Level. Similarly, the second open emitter terminal (Pin 10) is at the “Low” level when not conducting with the second open collector terminal (Pin 11), and is at the “High” level when conducting. In this way, when one is at “High” level, the other is at “Low” level.
Level, and when the other is at the "High" level, the first and second control signals are obtained, one of which is at the "Low" level. Also, the dead-off time of the first and second control signal are both "Low" level is controlled by the voltage dividing ratio of the variable resistor VR _11.

Next, the driver circuit IC ₂ comprises a high-speed, high-voltage bridge driver IC (IR2110 manufactured by IR). In this circuit example, the output terminals (pins 10 and 9) of the oscillation circuit IC ₁ are connected to the input terminals (pins 10 and 12), respectively, and are the same as the first and second control signals described above. Waveform withstand voltage of 50
A drive signal of 0 V is output from the output terminals (pins 7 and 1). The capacitor C _12, resistor R _14, consisting of diodes D ₁₁ circuit is a bootstrap circuit,
The power of the drive signal obtained from the 7th pin is supplied.

FIG. 10 and FIG. 11 are operation waveform diagrams of the above circuit. No.
FIG. 10 shows a high-frequency operation, and FIG. 11 shows a low-frequency operation. In the figure, V _Q2 is the switching element Q ₂
, I _Q1 and I _Q2 are currents flowing through the switching elements Q ₁ and Q ₂ , I _D1 and I _D2 are currents flowing through the diodes D ₁ and D ₂ ,
_L1, I _L2 is the current flowing through the inductor L _1, L _2, V _AC instantaneous voltage of the commercial AC power source Vs, I _AC input current from the commercial AC power source Vs, V _C3 the voltage of the smoothing capacitor C _3, V _La Is the voltage across the discharge lamp La. Note that the direction of the arrow in FIG. 9 is positive for both the current waveform and the voltage waveform.

As apparent from the above figures, when the instantaneous voltage V _AC of the commercial AC power source Vs is high, the current I _L1, I _Q2 flowing through the chopper circuit, when I _D1 increases, the above instantaneous voltage V _AC is low, above Each of the currents I _L1 , I _Q2 , I _D1 decreases. Therefore, the input current I _AC from the commercial AC power supply Vs becomes substantially sinusoidal, the input power factor increases, and the input current harmonic distortion is reduced. On the other hand, the current flowing in the inverter circuit
The size of the I _Q1, I _D2, I _L2, the voltage V _C3 of the smoothing capacitor C ₃
Because it depends on, it is almost independent of the instantaneous voltage V _AC of the commercial AC power supply Vs. Therefore, the voltage between both ends of the discharge lamp La
Envelope of V _La is substantially coincident with the voltage V _C3 of the smoothing capacitor C _3, in which the high frequency output of the low ripple is obtained.

[Problems to be Solved by the Invention] In the above-described discharge lamp lighting device using the chopper-type inverter, when the discharge lamp is dimly lit, any of the dimming control methods is used as described below. Some problems arise even when used.

(A) Duty control method First, in the duty control method, the on-duty (1) of the switching elements Q ₁ and Q ₂ constituting the inverter circuit is set.
(The ratio of the ON time to the cycle) is reduced to dimming the discharge lamp La. However, in this method,
To become possible to reduce the on-duty of the switching element Q ₂ of the chopper circuit is also used as the inverter circuit, the output voltage V _C3 chopper circuit is reduced. Therefore, decreases the step-up ratio of the chopper circuit, since the period in which no current flows through the smoothing capacitor C ₃ is increased, improvement and the input power factor, tends to become insufficient reduction of the input current harmonic distortion, prevent this Therefore, there is a problem that the configuration of the control circuit and the filter circuit becomes complicated.

(B) Complementary pulse width modulation control method In this method, one switching element Q ₁ (or Q ₂ )
The on-duty of the other switching element Q ₂ (or Q ₁ ) is complementarily increased while the on-duty of the other switching element Q ₂ (or Q ₁ ) is complementarily increased. When reduced to dimming on-duty of the switching element Q ₂ is a similar problem in the case of basically the aforementioned duty control scheme occurs. Further, in the case of small and dimming on-duty of the switching element Q ₁ is, whereas the load power decreases as dimming, on the switching element Q ₂ of the chopper circuit also serves, Since the duty becomes large, the output voltage V _C3 of the chopper circuit _tends to increase. As a result, in accordance with the discharge lamp La to the dimming, this means that high voltage such as a smoothing capacitor C ₃ and the switching elements Q _1, Q ₂ is applied, it is difficult to dim in a wide range. In addition, there is a problem that a circuit element having a high withstand voltage is required, which leads to an increase in cost.

(C) Impedance control method In this method, dimming is performed by reducing the lamp current by inserting an impedance element in series with the discharge lamp La. In this case, the switching operation in the chopper circuit is constant irrespective of dimming, but the load power consumption decreases as the dimming is performed. As a result, the output voltage V _C3 of the chopper circuit increases, and the above-described complementary pulse similar to the case of dimming by reducing the on-duty of the switching element Q ₁ in the width control method, it is difficult to dimming over a wide range, the circuit elements of the high voltage is required, a problem that increases the cost There is.

(D) Phase control method In this method, dimming is performed by controlling the effective value of the input current by controlling the phase of a triac or the like. However, in the phase control method, input current harmonic distortion always occurs due to its nature, and the input power factor also decreases.
There is a problem that the advantage of using the chopper-combined inverter lighting device is lost.

(E) Frequency control method In this method, the discharge lamp La is dimmed by changing the switching frequency of the switching elements Q ₁ and Q ₂ . In general, dimming of the discharge lamp La is performed by increasing the switching frequency. In this case, as the load power consumption decreases due to dimming, the output voltage V _C3 of the chopper circuit also tends to decrease. . However, the decrease in load power consumption due to the frequency change is more remarkable than the decrease in the output voltage V _C3 of the chopper circuit, and as a result, the output voltage V _C3 of the chopper circuit _tends to increase. For this reason, it becomes difficult to dimming the discharge lamp La in a wide dimming range, and a high breakdown voltage circuit element is required, resulting in a problem that the cost is increased.

(F) Lamp current pause section control method In this method, the discharge lamp La is dimmed by intermittently stopping the lamp current at a low cycle. However, when the operation of the chopper-type inverter device is intermittently stopped in order to intermittently stop the lamp current, the input current is intermittently stopped, and distortion occurs in the input current. There is a problem. Also, without stopping the operation of the chopper-shared inverter,
When a pause section of the lamp current is provided, the output voltage V _C3 of the chopper circuit tends to increase, so that it becomes difficult to dim the discharge lamp La in a wide range, and an element with a high withstand voltage is required. However, there is a problem that the cost is increased.

(G) Input voltage amplitude control method In this method, the discharge lamp La is dimmed by changing the input voltage of the inverter circuit. In the circuit of Figure 9, but in which changing the voltage V _C3 of the smoothing capacitor C _3, it changes the (i) method to change the operating frequency, (ii) on-duty of the switching element Q ₂ method, but (iii) method to change the value of the inductor L ₁ and the like are considered, (i), a respective method is essentially a frequency control method and duty control method of the aforementioned same (ii), (iii method to change the value of the inductor L ₁ of) there is a problem that it is economically difficult to achieve.

In addition, the above-mentioned problem is a problem that similarly occurs even when the load is other than the discharge lamp when the power consumption of the load is reduced.

The present invention has been made in view of such a point,
The purpose is to provide a low-cost load control device having a high input power factor and low input current harmonic distortion even when the power consumption of the load is changed over a wide range. is there.

[Means for Solving the Problems] The present inventor has analyzed the problems of the various types of dimming means described above, and as a result of diligent studies, these dimming means are roughly classified into the following three types. Was found to be.

(I) The first dimming means is a dimming method in which the step-up ratio of the chopper rises as dimming is performed, and it is difficult to obtain a wide dimming range, and a device with a high withstand voltage is required. There is a problem of inviting. Specifically, the impedance control mode, the complementary pulse width control method to reduce to dimming on-duty of the switching element Q _1, a frequency control method, the lamp current pause interval control scheme without the operation of the inverter is stopped, the operation of the chopper There is an input voltage amplitude control method based on a frequency change.

(II) The second dimming means is a dimming method in which the step-up ratio of the chopper decreases as the dimming is performed, and there is a problem that input current harmonic distortion occurs and the input power factor decreases. Specifically, the lamp to stop duty control scheme, complementary pulse width control method to reduce to dimming on-duty of the switching element Q _2, the input voltage amplitude control scheme according to the on-duty control of the chopper, the operation of the inverter current rest period control method, the switching element Q ₂ on
There is an input voltage amplitude control method for dimming by reducing the duty.

(III) The third light control means is a light control method in which harmonic distortion essentially occurs in the input current, and specifically, a phase control method can be mentioned.

Of these, the third dimming means is a method which is essentially unavoidable in which harmonic distortion occurs in the input current.
Can not be adopted. Therefore, if the first dimming means in which the boosting ratio of the chopper increases as the dimming is performed and the second dimming means in which the boosting ratio of the chopper decreases as the dimming is used are combined, a wide dimming range can be obtained. It is considered that stable dimming control can be realized. Further, it is considered that this principle is generally applied even when the load is not a discharge lamp.

The present invention has been made based on such knowledge, and its basic configuration is shown in FIG. The load control device of the present invention includes a commercial AC power supply Vs, a chopper-type inverter device 3 including a smoothing capacitor C, a load such as a discharge lamp La fed by the inverter device 3, and a load power consumption. The voltage of the smoothing capacitor C according to the reduction
First load power consumption control means 1 for increasing Vc, and a voltage Vc of the smoothing capacitor C in accordance with a reduction in load power consumption.
And a second load power control means 2 for reducing the power consumption. Then, the load power consumption is controlled by the first load power consumption control means 1 and the second load power consumption control means 2 so that the fluctuation range of the voltage Vc of the smoothing capacitor C is kept within an appropriate range. It is assumed that. here,
The proper range of the voltage Vc of the capacitor C is such that the lower limit is a value at which the input power factor becomes a high power factor and the input current harmonic distortion is sufficiently reduced, and the upper limit is a circuit element to be used (for example, smoothing). For example, a withstand voltage of a capacitor or a switching element.

[Operation] According to the present invention, as described above, the first load power consumption control means in which the boosting ratio of the chopper increases as the load power consumption decreases, and the boosting ratio of the chopper increases as the load power consumption decreases. Since the second load power consumption control means, which decreases, is used in combination, the boost ratio of the chopper does not change much even if the load power consumption is changed as a whole. Therefore, the input power factor does not decrease and the input current harmonic distortion does not increase due to the decrease in the voltage Vc of the smoothing capacitor C.
It is not necessary to increase the withstand voltage of each circuit element with respect to the rise of the voltage.

Embodiment 1 FIG. 2 is a circuit diagram of a first embodiment of the present invention. The basic configuration of this embodiment is almost the same as that of the conventional example shown in FIG. 9, except that the voltage V _C3 of the smoothing capacitor C ₃ is detected by a voltage dividing circuit composed of resistors R ₁₆ and R ₁₅ and a diode is provided. via the D ₁₂ that is fed back to the resistor terminal of the oscillation circuit IC ₁ (6 pin) is different. With this configuration, the oscillation circuit IC ₁
Is to carry out an oscillation operation at a frequency determined by the value of resistor R ₁₁ and the voltage V _C3, in accordance with the value of the voltage V _C3 decreases, the oscillation frequency is intended to gradually becomes higher. In this embodiment, the oscillation control terminal (pin 13) is connected to the ground level to select the single-ended operation. Therefore, the output terminals (pins 9 and 10) output in-phase output signals. Is obtained. This output signal is input to one of the input terminals (pin 12) of the driver circuit IC ₂ (IR2110 manufactured by IR).
And inputs, to input logic inverted signal by inverting circuits G ₁ to the other input terminal (10 pin) is a. Oscillation circuit
The on-duty of the signal output from IC ₁ is a variable resistor V
It is determined by the voltage (input voltage Pin 4) obtained by dividing the reference voltage (output voltage of the pin 14) by R _11. Therefore, the output terminal of the driver circuit IC ₂ (Pin 1, Pin 7
Pin No.) has complementary on-duty changes,
A drive signal of so-called complementary pulse width modulation can be obtained.

Next, the configuration of the main circuit is substantially the same as the conventional example shown in FIG. 9, in the present embodiment, has a resistor R ₁ for energizing a weak direct current. Thus, the discharge lamp La can be stably lit even with a low luminous flux having a relative illuminance ratio of about 1%, for example. Capacitor C ₅ for resonance is connected in parallel to the power supply side of the discharge lamp La, is provided a capacitor C ₆ of the DC blocking, weak direct current from resistor R ₁ is configured so as not to affect the resonant circuit I have. In the conventional example of FIG. 9 is a capacitor C ₅ for resonance also serves as the impedance element for the filament current. In this embodiment, the power supply for energizing the preheating current to the filament f _1, f ₂ E ₁ , it is provided separately from the E _2.

FIG. 3 shows an operation waveform diagram of the control circuit unit in this embodiment. At the time of full lighting, as shown in FIGS. 3A and 3B, the on-duty of the switching elements Q ₁ and Q ₂ is substantially equal and the oscillation frequency is low. (d), the on-duty of the switching element Q ₂ is reduced, the oscillation frequency becomes higher.
Thus, in the present embodiment, adjustment and oscillation frequency becomes high light, a first light control means for the output voltage V _C3 chopper increases, dimming to the on-duty of the switching element Q ₂ is The chopper output voltage V _C3
In addition, the output voltage V _{C3 of the} chopper does not change much even if the light is adjusted as a whole, because the second light adjusting means for decreasing the light intensity is used together. Therefore, the input power factor decreases,
There is no need to increase the input current harmonic distortion and to increase the breakdown voltage of the circuit element.

FIG. 4 shows the waveforms of the input current I _AC and the output voltage V _C3 of the chopper in this embodiment. FIG.
Also at the time of full lighting shown in (b), FIGS.
Even at the time shown dimming, the input current I _AC is substantially sinusoidal, does not change significantly much even if the output voltage V _C3 chopper.

As an example, in the circuit of FIG. 2, L ₁ = 2.4 mH, L _{2
= 3.9mH, C 3 = 125μF,} C 4 = 0.68μF, C 5 = 10000pF, C
_{6 = 8900pF, R 1 = 100kΩ} , the commercial AC power source Vs is AC100V60Hz
FIG. 5 shows the experimental results in the case of. As shown in the figure, in accordance with dimming, ON duty of the switching element Q ₂ is decreased, the oscillation frequency becomes higher. At this time, the output voltage V _C3 chopper is varied from 160V～350V, harmonic distortion of the input current is ranged acceptable.

Embodiment 2 FIG. 6 is a circuit diagram of a second embodiment of the present invention. The basic configuration of this embodiment is almost the same as that of the conventional example shown in FIG. 9, except that an impedance element Z is inserted in series with the discharge lamp La in the main circuit portion, and the impedance is adjusted in parallel with the impedance element Z. connecting the light switch SW _1. Moreover, by inserting the control circuit unit, a variable resistor VR ₁₁ in series with resistor R _10,
Connecting the dimmer switch SW ₁₁ in parallel with the resistor R _10. It is linked to the dimmer switch SW ₁ and the SW _11, are both turned on at the time of full lighting, both turned off at the time of dimming lighting.

FIG. 7 is an operation waveform diagram of the present embodiment. FIG.
As shown in (b), the on-duty of the switching elements Q ₁ and Q ₂ is large during full lighting, and the on-duty of the switching elements Q ₁ and Q ₂ is small during dimming. As a result, step light control by so-called duty control becomes possible. This duty control, the dimming, the output voltage V _C3 chopper is reduced. Meanwhile, dimmer switch SW ₁ at the time of full lighting is turned on, dimming during dimmer switch SW ₁ is by turned off, the discharge lamp La in series with the impedance element Z only when dimming is to be inserted. As a result, step light control by so-called impedance control becomes possible. This impedance control, the dimming, the output voltage V _C3 chopper is increased. Therefore, also in the present embodiment, the output voltage V _C3 of the chopper does not fluctuate greatly between dimming and full lighting, and the input power factor is reduced and the input current harmonic distortion is increased. There is no need to increase the breakdown voltage of the circuit element.

Third Embodiment FIG. 8 is a circuit diagram of a third embodiment of the present invention. In the present embodiment, the configuration of the control circuit is the same as that of the first embodiment shown in FIG.
This is exactly the same as the first embodiment, but is different from the first embodiment in that the chopper circuit of the main circuit is not a step-up type chopper but a step-up / step-down type chopper. That is, the DC output ends of the diode bridge DB, a switching element Q ₁ and the inductor L ₁ is connected through a load circuit, at both ends of the inductor L ₁ has a smoothing capacitor C ₃ connected through a diode D ₃ Have been. The switching element Q ₁ from the positive output terminal of the diode bridge DB when the switching element Q ₁ is turned on, the load circuit (capacitor C _4, inductor L _2, the discharge lamp La and capacitor C _5), the diode bridge through the inductor L ₁ electromagnetic energy in the inductor L ₁ is accumulated current flows in a path leading to the negative output terminal of DB, the electromagnetic energy is released to the smoothing capacitor C ₃ via the diode D ₃ when the switching element Q ₁ is turned off,
Smoothing capacitor C ₃ is charged. That is, in the present embodiment, the switching element Q ₁ is being shared by an inverter circuit and a chopper circuit. The output voltage V _C3 of the smoothing capacitor C ₃ is applied to the DC input terminal of the inverter circuit via the diode D _4, that is, the series circuit of the switching elements Q ₁ and Q ₂ . The diode D ₄ is provided in order to prevent the output of the diode bridge DB flows directly to the smoothing capacitor C _3. The capacitor C ₈ is a high frequency bypass sufficiently capacity than the smoothing capacitor C ₃ is set to be small.

In the present embodiment, since the configuration of the control circuit unit is exactly the same as the first embodiment, the complementary pulse width on duty of the switching elements Q _1, Q ₂ are changed complementarily by the variable resistor VR ₁₁ and modulation control, a frequency control the oscillation frequency of the oscillation circuit IC ₁ is changed is performed by the voltage V _C3 of the smoothing capacitor C _3. Therefore, as in the case of the first embodiment,
Even when dimming control is performed over a wide range, the voltage V _C3 of the smoothing capacitor C ₃ does not greatly change.

In the above embodiments, a series resonance type inverter circuit has been described as an example. However, it is needless to say that a half-bridge type inverter circuit, a full-bridge type inverter circuit, a single-type inverter circuit, a push-pull type inverter circuit, or the like may be used.

[Effects of the Invention] According to the present invention, as described above, in a load control device that receives a commercial AC power supply and supplies high-frequency power with low low-frequency ripple components to a load using a chopper-type inverter device, A first load power consumption control means in which the step-up ratio of the chopper increases as the load power consumption decreases, and a second load power consumption control means in which the step-up ratio of the chopper decreases as the load power consumption decreases. Therefore, as a whole, even if the load power consumption is changed, the step-up ratio of the chopper does not change much, and therefore, the input power factor decreases and the input current harmonic distortion increases due to the voltage drop of the smoothing capacitor. And it is not necessary to increase the withstand voltage of each circuit element with respect to the voltage rise of the smoothing capacitor, and the load power consumption can be reduced over a wide range. There is an effect that can be controlled.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram showing a basic configuration of the present invention, and FIG.
FIG. 3 is a circuit diagram of the first embodiment of the present invention, FIGS. 3 and 4 are operation waveform diagrams of the same, FIG. 5 is an explanatory diagram of the operation of the same, and FIG. 6 is a circuit of the second embodiment of the present invention. FIG. 7, FIG. 7 is an operation waveform diagram of the above, FIG. 8 is a circuit diagram of a third embodiment of the present invention, FIG. 9 is a circuit diagram of a conventional example, and FIG. 10 and FIG. It is. 1 is a first load power consumption control means, 2 is a second load power consumption control means, and 3 is a chopper-type inverter device.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁶ , DB name) H05B 41/24-41/29 H05B 41/38-41/42 H02M 7/48

Claims (1)

(57) [Claims] An AC power supply, a rectifier circuit for rectifying the AC power supply, a switching element, a high-frequency conversion circuit for converting a DC input to a high-frequency output based on an on / off operation of the switching element, and a high-frequency conversion circuit A smoothing capacitor connected to the DC input side of the circuit, interposed between the output terminal of the rectifier circuit and the switching element, stores energy during the ON period of the switching element, and stores the energy when the switching element is OFF. And a load driven by a high-frequency output of the inverter device, and when the load power consumption is reduced, the oscillation frequency of the high-frequency conversion circuit increases to reduce the load power consumption. First load power consumption control means for increasing the voltage of the smoothing capacitor; A second load power control means for reducing the on-duty of the switching element on the chopper side of the high-frequency conversion circuit and reducing the voltage of the smoothing capacitor which is the chopper output voltage when the load power consumption is reduced. A load control device.