JPH10136658A - Power unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide with simple constitution a power unit which can raise the power factor by improving the distortion of input current higher harmonic waves, and can prevent large stresses during abnormality times in a circuit from being exerted on a semiconductor element, etc., and also can reduce the stress on a filter. SOLUTION: A series circuit of switching elements Q1 and Q2 and a smoothing capacitor Co are connected in parallel to both ends of a capacitor C2, and an inverter load is connected between the output terminal of a rectifier DB and the junction between the switching elements Q1 and Q2. A parallel circuit A, consisting of a diode D2 and a capacitor C5, is connected between the junction between a diode D1 and a capacitor C3 and ground, and furthermore a diode D2 is connected in the direction where it can charge the smoothing capacitor Co from an AC power source Vs. Also the voltage across a circuit A is detected with a resistor R3, and a resistor R4 and is inputted into a Vo terminal of a control circuit 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply.

[0002]

2. Description of the Related Art As a conventional example of the present invention, there is Japanese Patent Application No. 7-310269 filed by the present applicant.

This conventional example has a rectifier for rectifying an AC power supply, a power supply circuit for smoothing the output of the rectifier to a DC voltage, and at least one switching element, and converts an output DC voltage of the power supply circuit to a high-frequency voltage. An inverter circuit for supplying the load, a high-frequency output feedback means for feeding back a part of the high-frequency output of the inverter circuit to the output terminal of the rectifier via the load, and at least a part of the load and a valley near the peak of the AC power supply. And an LC resonance circuit configured to include an impedance element whose resonance is strengthened, and when performing output control by varying the oscillation frequency of the inverter circuit, in a direction in which the input current from the AC power supply is substantially continuous. In a power supply device that varies the impedance value of an impedance element, the impedance element impedance is synchronized with the on / off of the switching element. It is characterized in that for varying the impedance value.

FIG. 14 shows a circuit example of the conventional example. This circuit includes a rectifier DB for rectifying the AC power supply Vs via a filter F, and a voltage V6 across an impedance element connected between the rectifier DB and the smoothing capacitor Co, that is, a field effect transistor (hereinafter, referred to as a switching element). .)) Three voltages: a voltage across a series-parallel circuit including Q13 and Q14, capacitors C15 and C16, a voltage Vdc across a smoothing capacitor Co, and a pulsating DC voltage VDB obtained by full-wave rectification of an AC power supply Vs by a rectifier DB. Relationship between
A high-frequency operation of an inverter circuit including field-effect transistors (hereinafter, referred to as switching elements) Q1 and Q2 causes a high-frequency pulse current to flow from the rectifier DB. In this circuit system, charging and discharging of the impedance element greatly contributes to rewriting input current harmonic distortion. Note that a capacitor C2 is connected in parallel to the output terminal of the rectifier DB, and a resistor R13, a field effect transistor (hereinafter, referred to as a switching element) Q14, and a first diode (hereinafter, referred to as a diode) are provided at both ends of the capacitor C2. .) Via D1 the switching element Q
1, a series circuit of Q2 and a smoothing capacitor Co are connected in parallel. An inverter load is connected between a negative output terminal of the rectifier DB and a connection point of the switching elements Q1 and Q2 via a diode D1, and an output terminal of the inverter circuit is connected to an output terminal of the rectifier DB via the inverter load. A part of the high frequency output is fed back. The inverter load is a capacitor C3, a discharge lamp La1, an inductance element L2.
And a capacitor C4 connected in parallel to both ends of the discharge lamp La1. A power supply circuit for smoothing the output of the rectifier DB to a DC voltage by the smoothing capacitor Co is configured. Further, the filter F includes a capacitor C1 and an inductance element L1, and the switching elements Q1, Q2, Q13, and Q14 are connected to a control power supply E.
and o is controlled by the control circuit 1.

In this circuit system, the switching element Q1,
There are six circuit operation modes during one cycle of turning on and off Q2. This circuit operation mode is changed to a pulsating DC voltage VDB.
In a certain circuit operation mode, an operation of flowing an input current from an AC power supply at a high frequency is performed while changing the operation ratio of the switching element in the peaks and valleys.

Next, the circuit operation will be briefly described.
First, the switching element Q1 is turned on and the switching element Q
When 2 is turned off, using the smoothing capacitor Co as a power supply, the resonance current changes from the smoothing capacitor Co → the switching element Q1 →
Inductance element L2 → capacitor C4, discharge lamp La
The current flows through the path of 1 → capacitor C3 → impedance element → smoothing capacitor Co to charge the impedance element. When the sum of the charging voltage V6 of the impedance element and the pulsating DC voltage VDB, which is the output voltage of the rectifier DB, becomes higher than the voltage Vdc across the smoothing capacitor Co, the input current changes from the AC power supply Vs to the rectifier DB to the switching element. Q1 → inductance element L2 → capacitor C
4. Discharge lamp La1 → capacitor C3 → diode D1 →
The current flows on the path from the rectifier DB to the AC power supply Vs, and the resonance operation is continued. Next, when the switching element Q1 is turned off and the switching element Q2 is turned on, the input current is changed by the regeneration of the switching element Q2 so that the input current is changed from the AC power supply Vs → the rectifier DB → the smoothing capacitor Co →
Resistance R13 → body diode of switching element Q2 → inductance element L2 → capacitor C4, discharge lamp L
a1 → Capacitor C3 → Diode D1 → Rectifier DB →
It continues to flow on the path of the AC power supply Vs, and continues the resonance operation.
Eventually, in the resonance operation using the capacitor C3 as a power source, the resonance current is changed from the capacitor C3 to the capacitor C4 and the discharge lamp L
a1 → Inductance element L2 → Switching element Q2
→ flows through the path of the resistor R13 → the impedance element → the capacitor C3, and discharges the charge of the impedance element. When the electric charge of the impedance element is exhausted, the resonance current is changed from the capacitor C3 to the capacitor C4 and the discharge lamp La1 to the discharge lamp La1.
Inductance element L2 → switching element Q2 → resistor R13 → body diode of switching element Q14 →
It flows through the path of the capacitor C3. When the switching element Q1 is turned on and the switching element Q2 is turned off, the resonance current continues to flow.
In the regeneration of 1, the resonance current continues to flow through the path of the capacitor C3 → the capacitor C4, the discharge lamp La1 → the inductance element L2 → the body diode of the switching element Q1 → the smoothing capacitor Co → the body diode of the switching element Q14 → the capacitor C3, Continue resonance operation.
The above operation is repeated.

In this operation, it can be seen that the charging and discharging of the impedance element greatly affects the waveform of the input current from the output terminal of the rectifier DB. That is, when the impedance element is immediately charged, the high-frequency current input from the rectifier DB increases, and the input current has a trapezoidal current waveform. On the other hand, if charging / discharging of the impedance element is delayed, the period of the high-frequency current flowing from the rectifier DB becomes short, and the input current becomes a current waveform with a pause.

Next, the operation of the present circuit will be briefly described for normal lighting, preceding preheating, dimming lighting, and abnormal load including no load.

During normal lighting, the switching element Q13
Is turned on and off in synchronization with the switching element Q1,
Switching element Q14 turns off. At the time of dimming lighting,
Switching elements Q13 and Q14 are turned off. here,
When shifting from normal lighting to dimming lighting, first, the oscillation frequency of the switching elements Q1 and Q2 is increased from f1 to f2, and then the switching element Q13 is turned off. In this case, the oscillation frequency of the switching elements Q1 and Q2 is reduced from f2 to f1, and at the same time, the switching element Q13 is turned on in synchronization with the switching element Q1.

At the time of load abnormality including no load, the resistance R13
A load abnormality is detected based on the voltage Vin detected in step (1). Even in the case of a load abnormality including no load, when switching from dimming lighting to normal lighting, the switching element Q14 is turned on in synchronization with the switching element Q1, so that an abrupt condenser to the switching element Q14 is provided. The discharge current of C15 stops flowing and the switching element Q
1. By changing the oscillation frequency of Q2 from f1 to f2 to the dimming lighting mode, the switching elements Q1,
Stress applied to Q2 can be reduced.

[0011]

However, the above-mentioned conventional example has the following problems.

When the capacitor C2 is connected, as described above, the magnitude of the pulsating DC voltage which is the output voltage of the rectifier DB, that is, the voltage VDB across the capacitor C2, the voltage V6 across the impedance element, and the voltage Vdc across the smoothing capacitor Co is large. According to the relationship, the input current was supplied from the AC power supply Vs, but when an abnormality occurred due to the opening of the capacitor C2, the absolute value Vc1 of the voltage across the capacitor C1, the voltage V6 across the impedance element, and the voltage Vdc across the smoothing capacitor Co. The input current flows from the AC power supply Vs depending on the magnitude relation of.

On the other hand, since the capacitor C1 is also a capacitor for charging and discharging a high-frequency current as the filter F, the voltage generated at both ends of the impedance element when the capacitor C2 is opened is smaller than when the capacitor C2 is connected. Alternatively, a high-frequency component is also likely to be applied to the charge / discharge current to the impedance element. This appears more prominently due to the electromotive force of the inductance component, for example, when an inductance component such as a no-march is inserted between the filter F and the rectifier DB.

In the above conventional example, it is possible to detect a load abnormality including no load, but even if the capacitor C2 is opened,
As described above, the operation as an inverter circuit does not cause any trouble, so that an abnormality in the circuit such as opening of the capacitor C2 cannot be detected by the resistor R13, and the discharge lamp La1 is turned on regardless of the abnormality. And the stress applied to the switching elements Q1, Q2, etc. increases, and the charging / discharging current to the capacitor C2 also flows into the capacitor C1, so that the stress on the filter F increases. Causes an increase in the self-temperature of the filter F and a reduction in the life of the filter F.

Further, when the capacitor C2 is opened, the abnormality cannot be detected by the resistor R13, but the input power is slightly increased, so that the temperature of the filter F and the like is increased as a result of the experiment. ing.

SUMMARY OF THE INVENTION The present invention has been made in view of all of the above problems, and it is an object of the present invention to improve the input current harmonic distortion and the power factor with a simple configuration and to improve the circuit. It is an object of the present invention to provide a power supply device capable of preventing a large stress due to an abnormal condition from being applied to a semiconductor element and the like and capable of reducing a stress on a filter.

[0017]

According to the first aspect of the present invention, there is provided a rectifier for rectifying an AC power supply, and a power supply circuit for smoothing an output of the rectifier to a DC voltage. An inverter circuit having a first switching element and converting an output DC voltage of a power supply circuit into a high-frequency voltage and supplying the high-frequency voltage to a load; An output feedback means, and an LC resonance circuit including at least a part of the load and an impedance element whose resonance is stronger near the valley than near the peak of the AC power supply, and the input current from the AC power supply is substantially reduced. In addition to being continuous, at least one of the voltage applied to the impedance element and the current flowing through the impedance element is detected to detect a circuit abnormality. To.

According to the second aspect of the present invention, there is provided a rectifier for rectifying an AC power supply, a power supply circuit for smoothing an output of the rectifier to a DC voltage, and at least a first switching element and for outputting an output DC voltage of the power supply circuit. An inverter circuit for converting to a high-frequency voltage and supplying the load to a load; high-frequency output feedback means for feeding back a part of the high-frequency output of the inverter circuit to the output terminal of the rectifier via the load; And an LC resonance circuit configured to include an impedance element whose resonance is stronger in the vicinity of the valley than in the vicinity of the part. The input current from the AC power supply is substantially continuous, and the voltage applied to the input terminal of the rectifier or the rectifier A circuit abnormality is detected by detecting at least one of the currents flowing to the input terminal.

According to a third aspect of the present invention, a circuit abnormality is detected during the conduction period of the rectifier.

According to a fourth aspect of the present invention, a circuit abnormality is detected at a frequency approximately twice that of an AC power supply.

According to the fifth aspect of the present invention, a circuit abnormality is detected at least near the zero crossing of the AC power supply.

According to a sixth aspect of the present invention, when the circuit is abnormal, the output of the inverter circuit is controlled to decrease.

According to the present invention, the inverter circuit includes a series circuit of two switching elements including the first switching element, and the two switching elements alternately turn on and off so that the load is changed. A half-bridge inverter circuit that supplies a high-frequency voltage to a connection point between a connection point of the two switching elements and one end of a rectifier output, wherein a series circuit of a resonance circuit including a load and a first diode is connected; A parallel circuit comprising a second diode and an impedance element is connected between a connection point of the first diode and the resonance circuit and one end of a series circuit of the two switching elements.

According to the present invention, the absolute value of the current waveform of the load current flowing through the load increases as the AC power source approaches the peak value, and the absolute value increases as the AC power source approaches the zero-cross value. Characterized by low frequency ripple.

According to a ninth aspect of the present invention, the impedance element includes at least a capacitor.

According to a tenth aspect of the present invention, the power supply circuit is a smoothing capacitor for smoothing the output of the rectifier.

According to the eleventh aspect of the present invention, the power supply circuit is a valley filling circuit for partially smoothing the output of the rectifier.

According to the twelfth aspect, the power supply circuit is a step-down chopper circuit.

According to a thirteenth aspect of the present invention, the load includes a discharge lamp.

According to the fourteenth aspect of the present invention, the detected value is turned off when the discharge lamp is preheated / started.

[0031]

Embodiment

(Embodiment 1) A circuit diagram of a first embodiment according to the present invention is shown in FIG. 1, and an operation waveform diagram thereof is shown in FIG.

The difference from the conventional example shown in FIG. 14 is that the switching elements Q13 and Q14, the capacitors C15 and C1
6, a parallel circuit A including a second diode (hereinafter referred to as a diode) D2 and a capacitor C5.
(Hereinafter, referred to as a circuit A) is connected between the connection point of the diode D1 and the capacitor C3 and the ground, and the diode D2 is connected in such a direction that the smoothing capacitor Co can be charged from the AC power supply Vs. A series circuit composed of a resistor R3 and a resistor R4 is connected in parallel to both ends of A, and the voltage across circuit A, that is, the voltage Vc5 across capacitor C5.
Is detected by the resistors R3 and R4 and input to the Vo terminal of the control circuit 1, and the resistor R13 shown in FIG. 14 is omitted. The description is omitted by attaching the reference numerals. In addition,
As in the conventional example, the ground of the control circuit 1 is a circuit ground.

Next, the operation of this circuit will be briefly described. When switching element Q1 is turned on and Q2 is turned off, smoothing capacitor Co → switching element Q1 → inductance element L2 → capacitor C4, discharge lamp La1 → capacitor C3.
→ A current flows through the path from the capacitor C5 to the smoothing capacitor Co to charge the capacitor C5. The voltage Vc5 across the capacitor C5 and the capacitor C1 forming the filter F
Is greater than the absolute value Vc1 of the voltage between both ends of the smoothing capacitor Co, the AC power supply Vs
→ Filter F → Rectifier DB → Switching element Q1 →
Inductance element L2 → capacitor C4, discharge lamp La
1 → Capacitor C3 → Diode D1 → Rectifier DB → Filter F → Input power flows through the path of AC power supply Vs, so that the input current flows in almost the entire area of one cycle of AC power supply Vs, and the input current distortion is improved. can do. Next, when the switching element Q1 is turned off and the switching element Q2 is turned on, the capacitor C3 is used as a power source, and the capacitor C3 → the capacitor C4, the discharge lamp La1 → the inductance element L2.
→ A current flows through the path of the switching element Q2 → the capacitor C5 → the capacitor C3, and when the charge of the capacitor C5 is exhausted, the capacitor C3 → the capacitor C4, the discharge lamp La1 → the inductance element L2 → the switching element Q
A current flows through a path of 2 → diode D2 → capacitor C3. As described above, the high frequency lighting of the discharge lamp La1 can be continued by alternately turning on and off the switching element Q1 and the switching element Q2 at a high frequency.

FIG. 2A shows the voltage waveform of the AC power supply Vs,
FIG. 2B shows the voltage waveform of the voltage Vc5 across the capacitor C5 during normal lighting, and FIG. 2C shows the voltage waveform of the voltage Vc5 across the capacitor C5 when the capacitor C2 is open. From FIG. 2, the voltage Vc5 across the capacitor C5 is higher when the capacitor C2 is open than when it is normally lit. By detecting this through the resistors R3 and R4, the control circuit 1 controls the switching elements Q1 and Q2. That is, when the capacitor C2 is opened, the control circuit 1
Stops the oscillation of the switching elements Q1 and Q2,
The dimming lighting is performed by increasing the frequency of the switching elements Q1 and Q2, and the switching elements Q1 and Q2 intermittently oscillate.

With the above-described configuration, it is possible to improve the input current harmonic distortion and improve the power factor with a simple configuration, and to prevent a large stress applied to a semiconductor element or the like due to an abnormal circuit. It is possible to reduce the stress on the filter.

In this embodiment, the load is a single discharge lamp. However, a plurality of discharge lamps may be used, or another load may be used. For example, in the case of parallel lighting of a plurality of lamps, when an abnormality is detected, it is possible to reduce the stress by performing thinning lighting.

(Embodiment 2) FIG. 3 shows a circuit diagram of a second embodiment according to the present invention.

The difference from the first embodiment shown in FIG. 1 is that one end of a series circuit consisting of a resistor R3 and a resistor R4 is
It is connected between the negative output terminal of the rectifier DB and the cathode terminal of the diode D1 so that the potential of the negative output terminal of the rectifier DB is detected by the resistors R3 and R4. The same components as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

(Embodiment 3) FIG. 4 shows a circuit diagram of a third embodiment according to the present invention.

The difference from the first embodiment shown in FIG. 1 resides in that one end of a series circuit consisting of a resistor R3 and a resistor R4 is connected.
The filter is connected to one output terminal of the filter F, and the potential of the one output terminal of the filter F is detected by the resistors R3 and R4. The description is omitted by attaching the same reference numerals.

(Embodiment 4) FIG. 5 shows a circuit diagram of a fourth embodiment according to the present invention.

The difference from the first embodiment shown in FIG. 1 is that one end of a series circuit consisting of a resistor R3 and a resistor R4 is
The filter is connected to one input terminal of the filter F, and the potential of the one input terminal of the filter F is detected by the resistors R3 and R4. The description is omitted by attaching the same reference numerals.

In the third and fourth embodiments, as shown in FIG. 6B, during the non-conduction period of the diode constituting the rectifier DB, the detection voltage inputted to the Vo terminal is always constant. However, during the conduction period of the diode constituting the rectifier DB, the detection voltage input to the Vo terminal becomes substantially zero during a certain period, so that only the conduction period of the diode constituting the rectifier DB is reduced by the resistors R3 and R4. The detection must be configured to work.

(Fifth Embodiment) FIG. 7 shows a circuit diagram of a fifth embodiment according to the present invention.

The difference from the first embodiment shown in FIG. 1 is that a current detection circuit 2 for detecting a current flowing through the circuit A is provided between the connection point of the diode D1 and the capacitor C3 and the circuit A. , And is configured to detect superposition of a high frequency on the circuit A. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. Note that the current detection circuit 2 may be configured with, for example, a current transformer or a shunt resistor.

In all of the above embodiments,
Instead of detecting the current or the voltage, the product of the current and the voltage, that is, the power amount may be detected.

(Embodiment 6) FIG. 8 is a circuit diagram of a sixth embodiment according to the present invention, and FIG. 9 is an operation waveform diagram thereof.

The difference from the first embodiment shown in FIG. 1 is that a switch element SW1 controlled by the control circuit 1 is provided between the connection point of the diode D1 and the capacitor C3 and the resistor R3, and The configuration is such that the detection section by R3 and R4 is controlled, and the same reference numerals are given to the same configuration as the other first embodiment, and the description is omitted.

Next, the operation will be briefly described with reference to FIG. The voltage Vc5 across the capacitor C5 is equal to the AC power supply Vs
Since the switching element SW1 is turned on and off at a frequency of 2fo since the frequency 2fo is twice the frequency fo of
When the switch element SW1 is turned on, a detection voltage as shown in FIG. 2 is input to the Vo terminal of the control circuit 1, that is, a certain detection voltage is applied to the V of the control circuit 1.
Input to the o terminal. Therefore, the on / off of the switch element SW1 may be synchronized with the positive / negative of the AC power supply Vs as shown in FIG. 9 (b), and the switching of the positive / negative of the AC power supply Vs as shown in FIG. 9 (d). The time may be shifted by an arbitrary period t1 from the time. Note that FIG.
In each case of (b) and FIG. 9 (d), a detection voltage as shown in FIG. 9 (c) and FIG. 9 (e) is input to the Vo terminal of the control circuit 1, respectively. Also, the switching element S
The on period of W1 is 1 / (2mfo) (where m is a positive integer), and the off period of switch element SW1 is 1 / (2mfo).
(2nfo) (where n is a positive integer).

Further, if the switching element SW1 is turned on during the period when the voltage Vc5 across the capacitor C5 is generated, it is not necessary to satisfy 1 / (2mfo) during the on period, and FIG. As shown in 1 / (2mfo)
It may be smaller, in which case the AC power supply V
It is desirable that the switching element SW1 is turned on near zero V of s. Further, when the switch element SW1 is turned off, no current flows through the resistors R3 and R4, so that the resistance R
3, the loss in R4 can be reduced, and by extending the OFF period of the switch element SW1, the resistance of the resistor R3,
The loss in R4 can be reduced.

Further, by turning off the switching element SW1 from the time when the power is turned on until the discharge lamp La1 is turned on, the discharge lamp La whose voltage at the Vo terminal slightly increases is turned off.
Since erroneous detection at the time of preheating / starting can be prevented, by setting the detection level at the time of normal lighting lower, it is possible to further increase the accuracy of detection at the time of normal lighting.

This embodiment may be applied to the circuits shown in the second to fifth embodiments.

(Embodiment 7) FIG. 10 shows a main part circuit diagram of a seventh embodiment according to the present invention.

This embodiment shows a specific circuit of the control circuit 1, and may be used in any of the first to sixth embodiments.

The circuit configuration of the control circuit 1 will be described below. In this circuit, the control power supply voltage Eo divided by the resistors R5 and R6 is input to the negative input terminal of the comparator Comp1, and the detection voltage divided by the resistors R3 and R4 and smoothed by the capacitor C6 is used as the positive voltage of the comparator Comp1. And input the comparison output of both to the drive circuit 3 via the latch circuit 4. (3) is for driving the switching elements Q1 and Q2.
The control power supply Eo supplies power to the comparator Comp1.

Then, the control power supply voltage Eo is changed to the resistances R5 and R5.
The voltage divided by 6 is a voltage V5, and the voltage across the capacitor C6 is a voltage Vc6. When the voltage Vc6 is higher than the voltage V5, the output of the comparator Comp1 becomes a high level (H level) and is latched by (4). Then, it is input to (3) as an abnormal signal, and an abnormal state can be detected.

(Eighth Embodiment) FIG. 11 shows a circuit diagram of an eighth embodiment according to the present invention.

The difference from the seventh embodiment shown in FIG. 10 is that the switch element SW2 is connected in parallel to both ends of the resistor R5, and the switch element SW2 is turned on from the time when the power is turned on until the discharge lamp is turned on. Thus, the configuration is such that erroneous detection at the time of preheating and starting the discharge lamp La1 can be prevented, and the description of the same components as those of the seventh embodiment is omitted by attaching the same reference numerals. I do. After the discharge lamp is turned on, the switch element SW2 is turned off. This embodiment may be used in any of the first to sixth embodiments.

Ninth Embodiment FIG. 12 is a circuit diagram of a ninth embodiment according to the present invention.

The difference from the eighth embodiment shown in FIG. 11 is that instead of the switching element SW2, a capacitor C7 is connected in parallel to both ends of a resistor R5 to preheat and discharge the discharge lamp La1.
The configuration is such that erroneous detection at the time of starting can be prevented, and the description of the same components as those of the other eighth embodiment will be omitted by retaining the same reference numerals. In addition,
This embodiment may be used in any of the first to sixth embodiments.

(Embodiment 10) FIG. 13 shows a circuit diagram of a tenth embodiment according to the present invention.

The difference from the second embodiment shown in FIG. 3 is that instead of the smoothing capacitor Co, a capacitor C8 connected in parallel to both ends of a series circuit of switching elements Q1 and Q2, and a capacitor C8 connected to both ends of the capacitor C8 A so-called so-called parallel circuit comprising a series circuit including a smoothing capacitor C9, an inductance element L3, and a diode D4, a diode D3 connected between a cathode terminal of the diode D4 and a drain terminal of the switching element Q2, and a switching element Q2. Since the step-down chopper circuit is used, the same components as those of the second embodiment are denoted by the same reference numerals, and description thereof is omitted. Note that this embodiment may be used in any of the first to ninth embodiments.

In the first to ninth embodiments, a valley filling circuit for partially smoothing the output of the rectifier DB may be used instead of the smoothing capacitor Co.

[0064]

According to the first to twelfth aspects of the present invention, the input current harmonic distortion can be improved and the power factor can be improved with a simple configuration, and a large stress due to abnormalities in the circuit can be obtained. Can be prevented from being applied to a semiconductor element and the like, and a power supply device capable of reducing stress on a filter can be provided.

According to the thirteenth aspect of the present invention, the first aspect is provided.
In addition to the effects of the twelfth aspect of the present invention, a power supply device capable of stably lighting a discharge lamp can be provided.

According to the invention of claim 14, according to claim 1,
In addition to the effects of the invention described in claim 13, the malfunction of the discharge lamp at the time of preheating and starting is prevented, and the detection level at the time of normal lighting is set lower, so that the accuracy of detection at the time of normal lighting is reduced. Can be provided.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment according to the present invention.

FIG. 2 shows an operation waveform diagram according to the embodiment.

FIG. 3 is a circuit diagram showing a second embodiment according to the present invention.

FIG. 4 is a circuit diagram showing a third embodiment according to the present invention.

FIG. 5 is a circuit diagram showing a fourth embodiment according to the present invention.

FIG. 6 is an operation waveform diagram according to the embodiment.

FIG. 7 is a circuit diagram showing a fifth embodiment according to the present invention.

FIG. 8 is a circuit diagram showing a sixth embodiment according to the present invention.

FIG. 9 shows an operation waveform diagram according to the above embodiment.

FIG. 10 is a circuit diagram showing a seventh embodiment according to the present invention.

FIG. 11 is a circuit diagram showing an eighth embodiment according to the present invention.

FIG. 12 is a circuit diagram showing a ninth embodiment according to the present invention.

FIG. 13 is a circuit diagram showing a tenth embodiment according to the present invention.

FIG. 14 is a circuit diagram showing a conventional example according to the present invention.

[Explanation of symbols]

 C capacitor D diode DB rectifier L inductance element La discharge lamp Q switching element Vs AC power supply

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H02M 7/538 H02M 7/538 A H05B 41/24 H05B 41/24 L 41/29 41/29 C

Claims (14)

[Claims] 1. A rectifier for rectifying an AC power supply, a power supply circuit for smoothing an output of the rectifier to a DC voltage, and at least a first switching element, and converting an output DC voltage of the power supply circuit to a high-frequency voltage. An inverter circuit that supplies a load, a high-frequency output feedback unit that feeds back a part of the high-frequency output of the inverter circuit to the output terminal of the rectifier via the load, and at least a part of the load and a crest of the AC power supply An LC resonance circuit including an impedance element whose resonance is stronger in the vicinity of the valley than in the vicinity thereof, wherein the input current from the AC power supply is substantially continuous. Alternatively, a power supply device detects at least one of a current flowing through the impedance element and detects a circuit abnormality. 2. A rectifier for rectifying an AC power supply, a power supply circuit for smoothing an output of the rectifier to a DC voltage, and at least a first switching element, and converting an output DC voltage of the power supply circuit into a high-frequency voltage. An inverter circuit that supplies a load, a high-frequency output feedback unit that feeds back a part of the high-frequency output of the inverter circuit to the output terminal of the rectifier via the load, and at least a part of the load and a crest of the AC power supply An LC resonance circuit including an impedance element whose resonance is stronger in the vicinity of the valley than in the vicinity thereof, wherein the input current from the AC power supply is substantially continuous. A power supply device that detects at least one of such a voltage or a current flowing through an input terminal of the rectifier, and detects a circuit abnormality. 3. The power supply device according to claim 2, wherein a circuit abnormality is detected during a conduction period of the rectifier. 4. A circuit abnormality is detected at a frequency approximately twice as high as that of the AC power supply.
The power supply device according to any one of the above. 5. The power supply device according to claim 1, wherein a circuit abnormality is detected at least near a zero cross of the AC power supply. 6. The power supply device according to claim 1, wherein the output of the inverter circuit is controlled to decrease when the circuit is abnormal. 7. The inverter circuit includes a series circuit of two switching elements including the first switching element, and applies a high-frequency voltage to the load by alternately turning on and off the two switching elements. A half-bridge inverter circuit for supplying, between the connection point of the two switching elements and one end of the rectifier output, a resonance circuit including the load;
And a parallel circuit including a second diode and the impedance element between a connection point of the first diode and the resonance circuit and one end of the series circuit of the two switching elements. The power supply device according to claim 1, wherein the power supply device is connected. 8. A current waveform of a load current flowing through the load includes a low-frequency ripple whose absolute value increases as the AC power supply approaches a peak value and whose absolute value increases as the AC power supply approaches a zero-cross value. The power supply device according to any one of claims 1 to 7, wherein the power supply device includes: 9. The power supply device according to claim 1, wherein the impedance element includes at least a capacitor. 10. The power supply device according to claim 1, wherein the power supply circuit is a smoothing capacitor for smoothing an output of the rectifier. 11. The power supply device according to claim 1, wherein the power supply circuit is a valley filling circuit that partially smoothes an output of the rectifier. 12. The power supply device according to claim 1, wherein the power supply circuit is a step-down chopper circuit. 13. The power supply device according to claim 1, wherein the load includes a discharge lamp. 14. The discharge lamp according to claim 13, wherein the detection value is turned off when the discharge lamp is preheated / started.
The power supply as described.