JP2000166245A - Power supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply which detects and controls the output voltage of a chopper circuit and the output voltage of an inverter circuit through simple circuitry in case of an anomaly. SOLUTION: The power supply comprises a chopper circuit 1 containing at least one switching element which receives the voltage of an alternating- current power supply Vs and outputs direct currents, a capacitor C1 for smoothing parallel-connected with the output ends of the chopper circuit 1, an inverter circuit 2 containing at least one switching element which converts the voltage VDC of the capacitor into a high frequency and supplies it to a load La, a first detecting means 3 which detects the voltage VDC of the capacitor C1, a second detecting means 4 which detects the voltage V1a across the load La, an adding means 5 which adds up the output of the first detecting means 3 and the output of the second detecting means 4, and a controlling means 6 which controls the switching elements in the chopper circuit 1 and the inverter circuit 2 so that the added value obtained by the adding means 5 is almost constant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device for converting a DC voltage obtained by rectifying and smoothing an AC power supply to a high frequency and supplying it to a load.

[0002]

2. Description of the Related Art FIG. 14 shows a circuit diagram of a conventional example. In this circuit, the chopper circuit 1 is connected to the AC power supply Vs, the smoothing capacitor C1 is connected to the output of the chopper circuit 1, and the inverter circuit 2 is further connected to the smoothing capacitor C1.
This is a power supply device that supplies power to the load La. In FIG. 14, a step-up chopper circuit including an inductor L1 and a diode D1, a switching element Q3, a rectifier DB and a filter circuit FT is used as a chopper circuit 1, and switching elements Q1 and Q2 and a resonance inductor L2 are used as an inverter circuit 2. 1 shows a half-bridge inverter circuit including a capacitor C2 for resonance and a capacitor C3 for resonance.

In this circuit, as shown in FIG. 15, a _VDC detection circuit 3, as shown in FIG. 15, is provided to suppress over-boosting of the voltage _VDC of the capacitor C1 due to power supply fluctuations and over-boosting of the lamp voltage Vla due to load fluctuations. The voltage V _DC of the capacitor C1 and the lamp voltage Vla are respectively detected by the Vla detection circuit 4, and the chopper control circuit 61
In addition, the switching elements Q1 to Q3 of the chopper circuit 1 and the inverter circuit 2 are controlled by the inverter control circuit 62 to reduce or stop the output. This reduces stress on the element.

[0004]

However, control means for detecting an abnormal increase in the voltage _VDC of the capacitor C1, which is the output of the chopper circuit 1, and controlling the voltage _{VDC of the} capacitor C1, Since the control means for detecting the abnormal increase of the lamp voltage Vla as the output and controlling the lamp voltage Vla is provided separately,
There are drawbacks in that the number of circuit components increases and the circuit becomes complicated, and the cost increases.

[0005] An object of the present invention is to provide a power supply device which realizes detection control of an output voltage of a chopper circuit and an output voltage of an inverter circuit with a simple circuit configuration at the time of abnormality.

[0006]

According to the present invention, in order to solve the above-mentioned problems, as shown in FIG.
At least one chopper circuit 1 having a switching element for receiving a voltage of s and outputting a direct current, a first capacitor C1 for smoothing connected in parallel to an output terminal of the chopper circuit 1, and a first capacitor At least one of which converts the voltage _VDC into a high frequency and supplies it to the load La, an inverter circuit 2 having a switching element, first detecting means 3 for detecting the voltage _VDC of the first capacitor C1, and a load La. Detecting means 4 for detecting the voltage Vla across the terminals
Addition means 5 for adding the output of the first detection means 3 and the output of the second detection means 4; and the chopper circuit 1 and the inverter circuit 2 so that the addition value obtained by the addition means 5 is substantially constant. And control means 6 for controlling the switching element.

[0007]

(Embodiment 1) FIG. 1 shows a circuit diagram of a first embodiment of the present invention. The circuit shown in FIG. 1 shows the basic configuration of the present invention. At least one chopper circuit 1 having a switching element for receiving a voltage of an AC power supply Vs and outputting a DC is connected in parallel to an output terminal of the chopper circuit 1. , A first capacitor C1 for smoothing, an inverter circuit 2 having a switching element, at least one of which converts a voltage of the first capacitor C1 into a high frequency and supplies the high frequency to the load La; and a first capacitor C1. and V _DC detection circuit 3 for detecting the voltage V _DC, the voltage across the load La Vla
Detecting circuit 4, an output of the _VDC detecting circuit 3, and an adding circuit 5 for adding the output of the Vla detecting circuit 4 respectively.
And a control circuit 6 for controlling the switching elements of the chopper circuit 1 and the inverter circuit 2 in response to the output of the added value in the addition circuit 5.

Hereinafter, the circuit operation of this embodiment will be described. A case where a discharge lamp is connected as the load La will be described. When the circuit is in a steady state, the control circuit 6 shown is controlled to have a predetermined DC voltage _VDC and a predetermined lamp voltage Vla. When the circuit is abnormal, the voltage V _DC of the first capacitor C1 is detected by the V _DC detection circuit 3,
The Vla detection circuit 4 detects the voltage Vla across the load La. Here, the DC voltage _VDC is, for example, 300
(V), assuming that the lamp voltage Vla is 100 (V), a voltage corresponding to 400 (V) appears at the output of the adding circuit 5. Actually, each detection voltage is set to be smaller than the voltage of the control power supply used in the control circuit 6 by resistance division.

[0009] If the load La is lost and there is no load, the lamp voltage Vla becomes higher than the voltage at the time of steady lighting due to the action of the resonance circuit. Further, in the no-load state, the DC voltage _VDC sharply increases due to the lightening of the load. Then, the output of the adding circuit 5 becomes 4
00 (V). In the control circuit 6, when the voltage exceeds 400 (V) set in advance, the switching frequency of the inverter circuit 2 is increased to weaken or stop the output, so that no extra stress is applied to the element. I'm done. In addition, even when the load La is in a state like Emiless at the end of life, both the lamp voltage Vla and the DC voltage _VDC are increased, so that the control is performed in the same manner and the element does not need to be stressed.

Next, consider the case where the DC voltage _VDC fluctuates due to, for example, power fluctuation. If the value of the DC voltage _VDC increases due to power supply fluctuations, more current flows through the load La, and the lamp voltage Vla decreases on the contrary due to the negative characteristics of the lamp load La. However,
Since the fluctuation width of the ramp voltage Vla is not as large as the fluctuation width of the DC voltage _VDC , the output of the adder circuit 5 eventually increases. Therefore, also in this case, similarly to the above, the addition circuit 5 is applied from the preset voltage.
Of the inverter circuit 2
By increasing the switching frequency of the chopper circuit 1 or making the duty unbalanced to weaken the output or stop the oscillation, it is not necessary to apply stress to the element.

Conversely, the DC voltage V_DCof
When the value decreases, the current does not flow through the load La more.
And the negative characteristic of the lamp load La
The pressure Vla increases on the contrary. However, the lamp voltage
Vla has a fluctuation range of DC voltage V _DCIs as large as
Therefore, as a result, the output of the adder circuit 5 becomes smaller.
Transition to. Therefore, in this case, the preset power
Detecting that the output of the adding circuit 5 has become smaller than the pressure,
Switching frequency of inverter circuit 2 and chopper circuit 1
Lower the number or make the duty closer to 50%
Control to increase the output. By doing so
As a result, the load La can always be driven with a substantially constant output.
You. If the output of the adding circuit 5 becomes too small,
Is provided with a separate reference level, and the chopper circuit 1 and the
Stop the oscillation of the inverter circuit 2 and do not put stress on the element
It can also be configured so that only

According to the circuit configuration of the present embodiment, the two detection controls of the DC voltage _VDC of the capacitor C1 and the lamp voltage Vla can be performed by one control circuit, so that the number of components can be reduced. In addition, it is possible to suppress the application of excessive stress to the element at various abnormalities such as no load, Emiless, and power supply fluctuation.

(Embodiment 2) FIG. 2 shows a circuit diagram of a second embodiment of the present invention. This circuit differs from FIG. 1 in that the output of the adder circuit 5 is compared with a substantially constant reference voltage Vk by a comparator COMP1, and the output is input to a control circuit 6. Other configurations are the same as those in FIG. This circuit has an advantage that, for example, when the output of the load La is adjusted by a dimmer or the like, a substantially constant reference voltage Vk is sufficient in the dimming range.

The detection method according to this embodiment will be described with reference to FIG. FIG. 3 shows the _VDC detection circuit 3 in a steady state.
The detection voltage V _DC, the detection voltage of the Vla detection circuit 4 Vla
Are shown with the dimming ratio on the horizontal axis. The left side of the figure shows the rated lighting time, and the right side shows the dimming lower limit time. In the drawing, the reference voltage Vk is indicated by a dashed line. In FIG. 3, the reason why the lamp voltage Vla ′ at the lower limit of dimming is higher than the lamp voltage Vla at the time of rated lighting is due to the dimming characteristics of the load, and the change width varies depending on the load and the range of dimming. On the other hand, the reason why the DC voltage V _DC ′ at the lower limit of dimming is lower than the DC voltage _VDC at the time of rated lighting and the output of the adding circuit 5 is slightly lower than the reference voltage Vk over the entire range of dimming is that This is realized by appropriately selecting the switching frequency and duty of the circuit 1 and the inverter circuit 2 in advance. FIG. 4 shows the relationship between the switching frequency and the duty.

FIG. 4A shows switching signals of the chopper circuit 1 and the inverter circuit 2 near the time of rated lighting. In the case of the chopper circuit 1, a period indicated by τ1 is obtained by short-circuiting a power supply via an inductor or the like. It is a period that is. When the inverter circuit 2 is, for example, two stones,
The control signal of one of the switching elements of the inverter circuit 2 has the illustrated waveform, and the control signal of the other switching element has an inverted waveform of the illustrated waveform. T1 corresponds to one cycle of switching, and the switching frequency f
(= 1 / T1) is several kHz to several tens kHz.

FIG. 4B shows a switching waveform at the time of the dimming lower limit. 4A, only the duty is unbalanced while the frequency is kept constant. By doing so, the ON time τ2 of the chopper circuit 1 becomes shorter than τ1, so that the output voltage _VDC of the chopper circuit 1 becomes as shown in FIG.
Lower than in the case of At the same time, the inverter circuit 2
Since the switching signal becomes unbalanced in the case of, the output is narrowed down more than in the case of FIG. By increasing the frequency at the same time as shown in FIG. 4C, the output of the inverter circuit 2 is further reduced.

Therefore, FIG.
(A) As the dimming is made deeper, by shifting to FIG. 4 (b) or FIG. 4 (c), the DC voltage V _DC
And the detected value of the lamp voltage Vla is substantially constant and can be continuously changed at a voltage lower than the reference voltage Vk.

DC voltage V output from chopper circuit 1
_{If the DC} can be changed as shown in FIG. 3, it is easy to detect an abnormal state in almost the entire range of dimming. That is,
As in the first embodiment, even if one of the DC voltage _VDC and the lamp voltage Vla causes an abnormal boost, one comparator COMP1
Can be detected.

Although the reference voltage Vk is set to a value larger than the sum of the detected values of the DC voltage _VDC and the lamp voltage Vla, the reference voltage Vk is smaller than the sum of the detected values of the DC voltage _VDC and the lamp voltage Vla. When set, detection control can be performed even when the DC voltage _VDC becomes extremely small.

In the circuit of FIG. 2, a boost chopper is applied to the chopper circuit 1 and a half-bridge inverter is applied to the inverter circuit 2 in FIG. 5 includes an AC power supply Vs, a filter circuit FT connected in parallel to the AC power supply Vs, a diode bridge DB having an AC input terminal connected to the filter circuit FT, and a DC output terminal of the diode bridge DB. A switching element connected between a series circuit of an inductor L1, a diode D1, and a capacitor C1, a connection point between the inductor L1 and the diode D1, and a DC output terminal of the diode bridge DB that is not connected to the inductor L1. Q3 and switching elements Q1, Q connected in parallel with the capacitor C1.
2, a series circuit of an ingot L2 and capacitors C2 and C3 connected to both ends of the switching element Q2, and a load La connected in parallel to the capacitor C3.

FIG. 6 shows the control circuit 6 and the detection circuits 3 and 4 of FIG. 5 in further detail. First, the control circuit 6
Are an astable multi-CN1 whose frequency is determined by the variable resistor R _T1 and the capacitor C _T1 , a monostable multi-CN2 whose output is output from the astable multi-CN 1 and whose duty is determined by the variable resistor R _T2 and the capacitor C _T2 , and a monostable multi-CN. CN
And a driving circuit D1 that receives the output of the monostable multi-CN2 and drives the switching elements Q1 and Q2.
R2. Although not shown, the switching signal to the switching elements Q1 and Q2 is output by the drive circuit DR2 as a signal that alternately repeats on and off.

The detection circuit comprises resistors R1, R2, R3
, A _VDC detection circuit 3 including transistors Tr1 and Tr2, resistors R4, R5, R6, R7, and a capacitor Cf.
If, the transistors Tr3, Tr4, the Vla detection circuit 4 consisting of a diode Df, and the V _DC detection circuit 3 V
a resistor R8 for adding the outputs of the la detection circuit 4;
R9 and R10, an addition circuit 5 including transistors Tr5 and Tr6, and a comparison circuit including resistors R11, R12 and R13 and a comparator COMP1 for comparing the output of the addition circuit 5 with the reference voltage Vk. I have.
The output of the comparison circuit is connected to the base of the transistor Q4.
2, the signal output from the monostable multi-CN2 to the drive circuits DR1 and DR2 can be forcibly set to 0 by turning on / off the transistor Q4.

In the present circuit, dimming is performed by controlling the frequency by changing the variable resistor R _T1 or by controlling the variable resistor R _T2.
Is performed by changing the duty. The variable resistors R _T1 and R _T2 are adjusted so that the dimming characteristics have the characteristics shown in the graph of FIG. The _VDC detection circuit 3 detects a current i1 proportional to the DC voltage _VDC through the resistor R2 as a current value of the current mirror circuit. Vla
Similarly, in the case of the detection circuit 4, a current i2 proportional to the lamp voltage Vla is supplied to the resistor R6 to detect the current as a current value of the current mirror circuit. Diode Df and capacitor C
f is provided for rectifying and smoothing the high-frequency lamp voltage Vla to detect an amplitude component. Since the addition circuit 5 supplies the current (i1 + i2) obtained by adding the respective currents to the resistor R10, a voltage corresponding to R10 × (i1 + i2) appears at a point e which is an input terminal of the comparator COMP1, and this voltage is proportional to V _DC + Vla. Will be shown. The reference voltage Vk is used to connect the control power supply Vcc to the resistor R11.
And R12.

If the circuit operation is normal (voltage at point e) <
Since it is Vk, the output of the comparator COMP1 is at L level, and the transistor Q4 is always off.
For this reason, the output of the monostable multi-CN2 is
1, input to DR2 continues, and the circuit continues to operate. On the other hand, when an abnormality such as no load occurs, the DC voltage _VDC or the lamp voltage Vla increases significantly, so that i1, i
2, the voltage at point e also increases proportionally. Then, when (voltage at point e)> Vk, the output of the comparator COMP1 switches from the L level to the H level, and the transistor Q4 is turned on. As a result, the output of the monostable multi-CN2 becomes 0, so that there is no input signal to the drive circuits DR1 and DR2, and the circuit stops.

In this embodiment, the example in which the circuit operation is stopped when an abnormality is detected has been described. However, the control after the detection is not limited to the stop, but the frequency may be increased or the duty may be unbalanced. Therefore, it is needless to say that the stress on the element can be reduced even if the output is reduced or the oscillation is intermittently repeated.

The chopper circuit 1 is not limited to a step-up chopper, but may be a step-up / step-down chopper or a step-down chopper.
The inverter circuit 2 is not limited to the half bridge,
It may be a single stone type or a full bridge type. The load does not need to be one, but may be two or more.

According to this embodiment, in the entire range of dimming,
Since two detections can be performed by one detection circuit, the number of components can be reduced. Further, since the setting of the reference value for detection can be substantially constant, the reference value can be set with a simple circuit. Further, since the difference between the reference value for normal lighting and the reference value for abnormality detection can be reduced in the entire range of dimming, it is possible to suppress the application of excessive stress to the element at the time of abnormality.

(Embodiment 3) FIG. 7 shows a circuit diagram of a third embodiment of the present invention. The circuit of this embodiment includes an AC power supply Vs,
Filter circuit FT connected in parallel to AC power supply Vs
, A diode bridge DB having an AC input terminal connected to the filter circuit FT, a smoothing capacitor C1, and a switching element Q connected in parallel to the smoothing capacitor C1.
1 and a series circuit of Q2, an inductor L connected between a + (plus) side terminal of the DC output terminals of the diode bridge DB and a connection point of the switching elements Q1 and Q2.
1 and a series circuit of a diode D1 and a switching element Q
L2 and capacitor C2 connected to both ends of
And a series circuit of a capacitor C3, a load La connected in parallel with the capacitor C3, and a voltage V _{DC of the} capacitor C1.
And V _DC detection circuit 3 for detecting the voltage across the load La V
the Vla detection circuit 4 for detecting a la, addition circuit for adding outputs of V _DC detection circuit 3 and the output of the Vla detection circuit 4 5
And a comparator COMP1 for comparing the output of the adder circuit 5 with a substantially constant reference voltage Vk, and a control circuit 6 for receiving the output of the comparator COMP1 and controlling the switching elements Q1, Q2. The diode bridge DB
Of the DC output terminals is connected to a connection point between the switching element Q2 and the smoothing capacitor C1.

This circuit is of a type in which the switching element of the chopper circuit 1 and the switching element of the inverter circuit 2 in FIG. The control method in this circuit is the same as that in the previous embodiments, and a description thereof will be omitted. The control signal waveform of the switching element Q2 that is shared by the chopper circuit 1 and the inverter circuit 2 corresponds to the period indicated by τ in FIG.

This circuit differs from the above-described embodiment in that the switching element of the chopper circuit 1 and the switching element of the inverter circuit 2 are also used, so that the number of drive circuits can be reduced and the circuit configuration can be further simplified. is there. However, since the number of switching elements is reduced by one as compared with the previous embodiments, the degree of freedom of control is reduced. To change the voltage _{VDC of the} capacitor C1 as shown in FIG. The duty is determined almost uniquely.

(Embodiment 4) FIG. 8 shows a circuit diagram of a fourth embodiment of the present invention. This circuit includes an AC power supply Vs, a filter circuit FT connected in parallel to the AC power supply Vs, a series circuit of smoothing capacitors C1 and C2, and switching elements Q1 and Q2 connected in parallel to the series circuit. A series circuit, a series circuit of diodes D1 and D2 also connected in parallel to the series circuit, an inductor L1 connected between one output terminal of the filter circuit FT, and a connection point of the diodes D1 and D2. A series circuit of an inductor L2 and capacitors C2 and C3 connected between a connection point of the switching elements Q1 and Q2 connected to the other output terminal of the filter circuit FT and a connection point of the smoothing capacitors C1 and C2; Load La connected in parallel with capacitor C3
And the voltage V across the series circuit of the smoothing capacitors C1 and C2.
V _DC detection circuit 3 for detecting _DC and voltage V across load La
the Vla detection circuit 4 for detecting a la, addition circuit for adding outputs of V _DC detection circuit 3 and the output of the Vla detection circuit 4 5
And a comparator COMP1 for comparing the output of the adder circuit 5 with a substantially constant reference voltage Vk, and a control circuit 6 for receiving the output of the comparator COMP1 and controlling the switching elements Q1, Q2.

This circuit is a type of circuit in which the switching element of the chopper circuit 1 and the switching element of the inverter circuit 2 in FIG. The control method in this circuit is the same as that in the previous embodiments, and a description thereof will be omitted. However, in the half cycle of the power supply in which the AC power supply Vs generates a voltage in the direction indicated by the arrow in the figure, the control signal waveform of the switching element Q1 of the switching elements that are shared also corresponds to the period indicated by τ in FIG. , The control signal waveform of the switching element Q2 becomes an inverted waveform thereof. On the other hand, the remaining half cycle in which the voltage polarity of the AC power supply Vs is inverted corresponds to the period in which the control signal waveform of the switching element Q2 is indicated by τ in FIG. 4, and the control signal waveform of the switching element Q1 has the inverted waveform. Becomes This circuit differs from the above-described embodiment in that the switching element of the chopper circuit 1 and the switching element of the inverter circuit 2 are used in common, so that the number of drive circuits can be reduced and the control circuit can be further simplified. is there. Further, as compared with the third embodiment, the operation of the chopper circuit is switched between the switching elements Q1 and Q2 every half cycle of the power supply, so that the stress of the switching element can be reduced.

(Embodiment 5) FIG. 9 shows a circuit diagram of a fifth embodiment of the present invention. This circuit includes an AC power supply Vs, a rectifier DB for rectifying an AC voltage of the AC power supply Vs, and a capacitor C
5 and a series circuit of switching elements Q1, Q2 alternately turned on and off at a high frequency connected in parallel to the capacitor C5, and a series of an inductor L1, a smoothing capacitor C1, and a diode D2 connected in parallel to the capacitor C5. Circuit, a diode D connected between a connection point between the capacitor C1 and the diode D2 and a connection point between the switching elements Q1 and Q2, and an anode terminal connected to the capacitor C1.
1 and-(minus) of the DC output terminals of the rectifier DB
A capacitor C4 connected between the side terminal and a terminal on the switching element Q2 side of the series circuit of the switching elements Q1 and Q2, and a direction in which current can flow from the DC output terminal of the rectifier DB in parallel with the capacitor C4. A capacitor C2 and a transformer T1, which are connected between the diode D3 to be connected, the-(minus) terminal of the DC output terminals of the rectifier DB, and the connection point of the switching elements Q1 and Q2.
, A series circuit with the primary winding, a load La connected to the secondary side of the transformer T1, a capacitor C3 connected in parallel to a non-power supply side terminal of the load La, and a secondary circuit of the transformer T1. A Vla detection circuit 4 provided with a series circuit of a diode DT and a resistor RT, one end of which is connected to the ground of the circuit, and a resistor R _DC for detecting a voltage across the capacitor C5.
V _DC detection circuit 3, and the output of V _DC detection circuit 3 and V
la, an addition circuit 5 for adding the output of the detection circuit 4, a comparator COMP1 for comparing the output of the addition circuit 5 with a substantially constant reference voltage Vk, and a switching element of the inverter circuit receiving the output of the comparator COMP1. And a control circuit 6 for controlling. The + (plus) side terminal of the DC output terminals of the rectifier DB is connected to the switching element Q.
1, Q2 is connected to the terminal on the switching element Q1 side of the series circuit.

FIG. 2 shows a circuit in which two step-down choppers are used as the chopper circuit and a half-bridge inverter is used as the inverter circuit. The control method in this circuit is the same as that in the previous embodiments, and a description thereof will be omitted. In the present embodiment, since the step-down chopper configuration includes the inductor L1, the smoothing capacitor C1, and the diodes D1 and D2, the input current distortion can be reduced during the period when the voltage across the capacitor C5 is equal to or less than the peak value of the power supply. Further, since the drive circuit of the chopper circuit can be omitted, the circuit can be configured with a smaller number of components.

(Embodiment 6) FIG. 10 is a circuit diagram of a sixth embodiment of the present invention. This circuit comprises a rectifier DB for rectifying the AC output of the AC power supply Vs, and a first capacitor C for smoothing.
1, a series circuit of a pair of first and second switching elements Q1 and Q2 connected in parallel with the first capacitor C1 and alternately turned on and off at a high frequency, and the switching elements Q1 and Q2, respectively. A first and a second diode (parasitic diode in the reverse direction built in the MOSFET) connected in parallel;
1, +2 of the connection point of Q2 and the DC output terminal of the rectifier DB.
Transformer T whose primary winding is connected to the (plus) side
1 and a discharge lamp La connected to the secondary winding of the transformer T1.
A resonance capacitor C3 connected to the non-power-supply-side terminal of the discharge lamp La; a primary winding of the transformer T1;
One end is connected to a connection point between the DC output terminal of B and the + (plus) terminal, and the other end is connected to the negative terminal of the capacitor C1.
(Tin) terminal connected to the (negative) side terminal and connected to the transformer T1 according to the on / off of the switching elements Q1 and Q2.
Capacitor C2 forming a resonance circuit with the primary winding of
And a negative terminal of the DC output terminal of the rectifier DB is connected to a negative terminal of the capacitor C1. The switching elements Q1 and Q2 are each driven by a signal from the control circuit 6. Tertiary winding provided in the transformer T1;
The output of the Vla detection circuit 4 including the diode DT and the resistor RT, and the resistor R connected to the + (plus) side terminal of the capacitor C1.
The output of the V _DC detection circuit 3 connected with _DC is added by the addition circuit 5, and the output of the addition circuit 5 and the substantially constant DC power supply Vk are each + (plus) of the comparator COMP1. And the minus (−) input terminal, and the output of the comparator COMP1 is connected to the control circuit 6.

FIG. 2 shows a circuit in which a boost chopper is used as a chopper circuit and a half-bridge inverter is used as an inverter circuit in FIG. The control method in this circuit is the same as that in the third embodiment, and thus the description is omitted. The difference from the third embodiment is that the lamp voltage Vl
The point is that instead of directly detecting a, a voltage proportional to the lamp voltage Vla can be detected using the transformer T1. In this case, since the detection can be performed while being insulated, the control circuit is safe. Further, since the drive circuit of the chopper circuit can be omitted, the circuit can be configured with a smaller number of components.

(Embodiment 7) FIG. 11 is a circuit diagram of a seventh embodiment of the present invention. This circuit comprises an AC power supply Vs, and diodes D3 and D4 each having a middle point connected to one end of the AC power supply Vs.
And a capacitor C2 connected between the other end of the AC power supply Vs and the anode terminal of the diode D4.
A smoothing capacitor C1 connected in parallel with the series circuit of the diodes D3 and D4, and a series circuit of a pair of switching elements Q1 and Q2 connected in parallel with the capacitor C1 and alternately turned on and off at a high frequency; , Switching elements Q1, Q2, respectively, a first and a second diode (parasitic diode in the reverse direction built into the MOSFET) connected in antiparallel, a connection point between the switching elements Q1, Q2, and the AC power supply Vs A primary winding is connected between the connection point of the capacitor C2 and the transformer T
1 and a discharge lamp La connected to the secondary winding of the transformer T1.
And a resonance capacitor C3 connected to the non-power supply side terminal of the discharge lamp La, the switching elements Q1 and Q2 are connected so as to be controlled by a signal from the control circuit 6, respectively, and are connected to the transformer T1. The output of the provided tertiary winding, the output of the Vla detection circuit 4 including the diode DT and the resistor RT, and the output of the _VDC detection circuit 3 provided by connecting the resistor R _DC to both ends of the capacitor C1 are added. Circuit 5
And the output of the addition circuit 5 and the reference voltage V
k is connected to the + (plus) and-(minus) input terminals of the comparator COMP1, and the output of the comparator COMP1 is connected to the control circuit 6.

The operation of this circuit is different from that of the sixth embodiment in that the switching element operating as a chopper circuit switches every half cycle of the power supply. Therefore, the stress of each switching element can be reduced. Other operations are the same as in the sixth embodiment. Also in this embodiment, similarly to the sixth embodiment,
Since the detection can be performed with the insulation, the control circuit is safe. Further, since the switching element is also used in the inverter circuit and the chopper circuit, the number of elements in the main circuit can be reduced. Further, since the control circuit and the drive circuit of the chopper circuit can be omitted, the circuit can be configured with a smaller number of parts.

(Embodiment 8) FIG. 12 is a circuit diagram of an eighth embodiment of the present invention. The circuit configuration differs from that of FIG. 11 in that a comparator COMP2 for comparing the output of the adder circuit 5 with another reference voltage Vk ′ is newly provided and the output is input to the control circuit 6. The present circuit is a circuit that separately controls a mode in which circuit operation such as power supply fluctuation or load fluctuation is desired to be continued and a mode in which circuit operation such as no load is desired to be weakened or stopped. This will be described with reference to FIG.

FIG. 13 shows a new reference voltage V in the graph of FIG.
k ′ is provided. In the above embodiments, the reference voltage V
If the voltage exceeds k, the circuit is judged to be abnormal, and the circuit is stopped or the output is reduced. However, besides no load, Emiless, etc., power supply fluctuations and load fluctuations are considered as causes that exceed the reference voltage Vk. Can be However, if the power supply fluctuation or the load fluctuation is plus or minus several percent, it is desirable to compensate the output and continue the operation. Now, consider a case where the power supply voltage increases or a case where the load output decreases. When the power supply voltage increases, the DC voltage _VDC increases, and when the load output decreases, the lamp voltage Vla increases. At this time, even if any of the voltages increases, the voltage exceeds the first reference value Vk. Here, if the sum Va of the detection voltages is in the range of Vk <Va <Vk ′, the frequency of the inverter circuit is lowered, or the duty of the switching signal is brought close to 50 (%).
I will compensate for the increase in output. If Vk '<
If it is Va, it may be determined that the circuit is abnormal, such as no load, and the circuit operation may be weakened or stopped.

The control according to the present embodiment can be performed not only when the power supply voltage increases and the load output decreases, but also when the power supply voltage decreases and the load output increases. In that case, a reference voltage Vk "lower than the reference voltage Vk is newly set, output compensation is performed in the range of Vk"<Va<Vk, and circuit operation is stopped when Va <Vk "is satisfied. good.

[0042]

According to the first aspect of the present invention, since two detection controls of the output voltage of the chopper circuit and the output voltage of the inverter circuit can be performed by one control circuit, there is an advantage that the number of components can be reduced. It is possible to suppress the application of excessive stress to the element at the time of abnormality such as no load, Emiless, or power supply fluctuation. Further, when the detection voltage becomes low, the circuit can be stopped immediately, and flickering, jump phenomenon, or over output can be suppressed.

According to the second aspect of the present invention, since the load voltage is inversely proportional to the output of the inverter circuit, detection control in which the sum of the output voltage of the chopper circuit and the detection voltage of the output voltage of the inverter circuit becomes substantially constant can be easily performed. Become. According to the third aspect of the present invention, the output voltage of the chopper circuit and the output voltage of the inverter circuit can be detected by one detection circuit in the entire range of dimming, so that the number of components can be reduced. Further, since the setting of the reference value for detection can be substantially constant, the reference value can be set with a simple circuit. Further, since the difference between the reference value for normal lighting and the reference value for abnormality detection can be reduced in the entire range of dimming, it is possible to suppress the application of excessive stress to the element at the time of abnormality.

According to the fourth aspect of the present invention, since the drive circuit of the chopper circuit can be omitted, the circuit can be configured with a smaller number of parts. According to the fifth aspect of the present invention, since the drive circuit of the chopper circuit can be omitted, the circuit can be configured with a smaller number of components. Further, since the switching element that performs the chopper operation switches every half cycle of the power supply, the stress of each switching element can be reduced.

According to the sixth aspect of the present invention, since the step-down chopper is configured, the output voltage of the chopper circuit can be set low, and the stress can be reduced. Further, since the drive circuit of the chopper circuit can be omitted, the circuit can be configured with a smaller number of components. According to the invention of claim 7, the chopper inductor can be used also as the inductor of the inverter circuit, so that the number of circuit components can be reduced. According to the invention of claim 8, since only two diodes are required for the rectifier, the number of components can be further reduced.

According to the ninth aspect of the present invention, since the control can be performed in accordance with the magnitude of the abnormally boosted voltage, it is possible to distinguish between a power supply fluctuation for continuing the operation and no load or Emiless. According to the tenth aspect, the detection can be performed while being insulated from the load, so that the control circuit is safe. Further, since the drive circuit of the chopper circuit can be omitted, the circuit can be configured with a smaller number of components.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a first embodiment of the present invention.

FIG. 2 is a circuit diagram according to a second embodiment of the present invention.

FIG. 3 is an operation explanatory diagram of a second embodiment of the present invention.

FIG. 4 is a waveform chart for explaining a switching operation according to a second embodiment of the present invention.

FIG. 5 is a circuit diagram specifically illustrating a chopper circuit and an inverter circuit according to a second embodiment of the present invention.

FIG. 6 is a circuit diagram specifically illustrating a detection circuit and a control circuit according to a second embodiment of the present invention.

FIG. 7 is a circuit diagram of a third embodiment of the present invention.

FIG. 8 is a circuit diagram of a fourth embodiment of the present invention.

FIG. 9 is a circuit diagram of a fifth embodiment of the present invention.

FIG. 10 is a circuit diagram of a sixth embodiment of the present invention.

FIG. 11 is a circuit diagram of a seventh embodiment of the present invention.

FIG. 12 is a circuit diagram of an eighth embodiment of the present invention.

FIG. 13 is an operation explanatory diagram of the eighth embodiment of the present invention.

FIG. 14 is a circuit diagram of a conventional example.

FIG. 15 is a circuit diagram for explaining a conventional detection circuit and control circuit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Chopper circuit 2 Inverter circuit 3 _VDC detection circuit 4 Vla detection circuit 5 Addition circuit 6 Control circuit Vs AC power supply C1 Capacitor La Load

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) AA17 BB03 CA02 CB04 CB12 CB22 DC05 EA08 EA09 FA01 FA13 FA14

Claims (8)

[Claims] 1. A chopper circuit having at least one switching element for receiving a voltage of an AC power supply and outputting a direct current, a first capacitor for smoothing connected in parallel to an output terminal of the chopper circuit, At least one of: an inverter circuit having a switching element for converting a voltage of the first capacitor to a high frequency and supplying the converted voltage to a load; first detecting means for detecting a voltage of the first capacitor; and detecting a voltage across the load. A second detecting means, an adding means for adding an output of the first detecting means and an output of the second detecting means, a chopper circuit and an inverter circuit such that an added value obtained by the adding means becomes substantially constant. And a control unit for controlling the switching element. 2. The load according to claim 1, wherein the load is a discharge lamp, and a means for arbitrarily adjusting the output of the load is provided.
The power supply as described. 3. A series of a rectifier for rectifying an AC power supply, a first capacitor for smoothing a DC output of the rectifier, and a pair of switching elements connected in parallel to the first capacitor and alternately turned on and off at a high frequency. A circuit, a diode connected in anti-parallel to each of the pair of switching elements, and a load circuit including a resonance inductor, a resonance capacitor, and a load connected to both ends of one of the pair of switching elements. A chopper inductor connected between the DC output terminal of the rectifier and one of the pair of switching elements; first detecting means for detecting a voltage of a first capacitor; Second detecting means for detecting the voltage of the first detecting means, adding means for adding the output of the first detecting means and the output of the second detecting means, 3. The power supply device according to claim 1, further comprising control means for controlling the switching element so that the obtained addition value becomes substantially constant. 4. A circuit in which first and second diodes are connected in series so that their forward directions match, and a circuit in which third and fourth diodes are connected in series so that their forward directions match, in the same direction. A full-wave rectifier comprising a diode bridge circuit is connected in parallel, and first and second switching elements are connected in anti-parallel with the third and fourth diodes, respectively, between the AC input terminals of the full-wave rectifier. An AC power supply is connected via a chopper inductor, a series circuit of first and second smoothing capacitors is connected between the DC output terminals of the full-wave rectifier, and a connection point of the first and second smoothing capacitors is connected. , A load circuit including a resonance inductor, a resonance capacitor and a load connected between a connection point of the first and second switching elements. First detecting means for detecting the voltage between both ends of the series circuit of the sensor, second detecting means for detecting the voltage between both ends of the load, and adding the output of the first detecting means and the output of the second detecting means. The power supply device according to claim 1, further comprising: an adding unit; and a control unit that controls the switching element such that an addition value obtained by the adding unit is substantially constant. 5. A rectifier for rectifying an AC power supply, a first capacitor receiving a rectified output of the rectifier and charging a DC voltage, and a rectified output between the rectified output of the rectifier and the first capacitor. A first diode connected in series in the direction, a second capacitor connected in parallel to the first diode, and a pair of alternatingly turned on and off at a high frequency connected in parallel to the first capacitor. A series circuit of switching elements, second and third diodes respectively connected in anti-parallel to the pair of switching elements, a connection point between the rectifier and the first diode, and a connection point between the pair of switching elements. A load circuit including a resonance inductor, a resonance capacitor, and a load connected via a DC cut capacitor between the first capacitor and the load circuit; A connected partial smoothing circuit, first detection means for detecting the voltage of the first capacitor, second detection means for detecting the voltage across the load, and the output of the first detection means 3. The power supply according to claim 1, further comprising: an adding unit that adds an output of the detecting unit; and a control unit that controls a switching element so that an addition value obtained by the adding unit is substantially constant. apparatus. 6. A rectifier for rectifying an AC output of an AC power supply, a first capacitor for smoothing, and a pair of switching elements connected in parallel with the first capacitor and alternately turned on and off at a high frequency. A series circuit, first and second diodes respectively connected in anti-parallel with the pair of switching elements, and a primary circuit between a connection point of the pair of switching elements and one DC output terminal of the rectifier. One end is connected to a connection point between the primary winding of the transformer and the DC output terminal of the rectifier, and the other end is connected to the transformer to which the winding is connected, the load circuit connected to the secondary winding of the transformer, A second capacitor connected to one terminal of the first capacitor and forming a resonance circuit with a primary winding of the transformer according to ON / OFF of the switching element; A DC output terminal of the rectifier forms a path through which a current flows from an AC power source among the terminals of the first capacitor, through the transformer, one of the first and second diodes, and the first capacitor. A first detecting means for detecting the voltage of the first capacitor; a second detecting means for detecting the voltage across the load; and a first detecting means for detecting the voltage across the load. 2. An adding means for adding an output and an output of a second detecting means, and a controlling means for controlling a switching element such that an added value obtained by the adding means is substantially constant. 3. The power supply device according to 2. 7. A circuit in which first and second diodes are connected in series so that their forward directions match, and a circuit in which third and fourth diodes are connected in series so that their forward directions match are connected in the same direction. A full-wave rectifier consisting of a diode bridge circuit is connected in parallel, and first and second switching elements are connected in anti-parallel with the first and second diodes, respectively, between the AC input terminals of the full-wave rectifier. A series circuit of an AC power supply and a load circuit is connected, a first capacitor for smoothing is connected between the DC output terminals of the full-wave rectifier, and a connection point between the AC power supply and the load and one DC output terminal of the full-wave rectifier. And a second detection means for detecting the voltage of the first capacitor; a second detection means for detecting the voltage across the load; Output of the detecting means 1 3. An apparatus according to claim 1, further comprising an adder for adding an output of the second detector, and a controller for controlling the switching element such that an addition value obtained by the adder is substantially constant. The power supply as described. 8. A method according to claim 1, further comprising comparing means for comparing an added value of said adding means with an arbitrary reference voltage, wherein an abnormality is detected when an output of the comparing means is different from an output in a normal state. Item 8. The power supply device according to any one of Items 1 to 7.