JP2003224980A - Power supply - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply which has a resonance circuit as a load, detects a capacitive operation securely when a resonance current is capacitive in an abnormal load state, and avoids malfunctionings caused by transient hair-shaped currents produced by a switching operation in a normal load state. <P>SOLUTION: An abnormality detecting control unit 42 of a control circuit 4 comprises a switch current detection circuit 42a, which detects the state of a resonance current according to a voltage between both ends of an impedance device Z, an oscillation synchronization circuit 42c which outputs an oscillation synchronization signal synchronized with a driving timing of a switching device Q2, a detection timer 42b which sets a detection region where an abnormality is detected, and an abnormality detection circuit 42d which detects abnormality in the detection region. A period, starting from the time when a regenerative current generated immediately after the switching device Q2 is turned on in a normal state, till the time when the drive of the switching device Q2 is turned off, is used as the abnormality detection region and the abnormality is detected, by deciding the polarity of the current applied to the switching device Q2. <P>COPYRIGHT: (C)2003,JPO

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 which converts a DC voltage into a high frequency voltage and supplies it to a load.

[0002]

2. Description of the Related Art FIG. 13 shows a circuit configuration of a discharge lamp lighting device as a conventional power supply device. This discharge lamp lighting device has an AC power source Vs, a full-wave rectifier DB that rectifies the output of the AC power source Vs, and a full-wave rectifier DB that has a smoothing capacitor.
Power supply circuit 1 that smoothes the pulsating current voltage output by the power supply circuit and outputs a DC voltage, an inverter circuit 2 that converts the DC voltage output by the power supply circuit 1 into a high frequency voltage, and a resonance that is supplied with high frequency power from the inverter circuit 2. It is composed of a load circuit 3 and a control circuit 4 for controlling the operation of the inverter circuit 2, and the full-wave rectifier DB and the power supply circuit 1 form a DC power supply.

The inverter circuit 2 includes a series circuit of a high-voltage side switching element Q1, a low-voltage side switching element Q2, and a resistor R1 connected between output terminals of the power supply circuit 1, and a series circuit of a switching element Q2 and a resistor R1. It is composed of a half-bridge type inverter circuit including a snubber capacitor C4 that is connected in parallel with the DC voltage output from the power supply circuit 1 and is converted into a high frequency voltage by alternately turning on and off the switching elements Q1 and Q2. is doing. Specifically, the switching elements Q1 and Q2 are FET elements each having a parasitic diode reversely connected in parallel, the drain of the high voltage side switching element Q1 is connected to the high voltage side output of the power supply circuit 1, and the low voltage side switching element Q2 is connected. Of the resistor R1 is connected to the source of the high-voltage side switching element Q1, one end of the resistor R1 is connected to the source of the low-voltage side switching element Q2, and the other end is connected to the low-voltage side output of the power supply circuit 1. Furthermore, the low voltage side output of the power supply circuit 1 is connected to the ground. Further, the snubber capacitor C4 slows down the fall and rise of the connection midpoint voltage of the switching elements Q1 and Q2 when the switching element Q2 is on / off to reduce switching loss and noise generated by switching. Has an aim.

The resonant load circuit 3 is connected between the discharge lamps La1 and La2 in which the power supply side terminals of one filament electrode are connected to the drain of the switching element Q1 and the non-power supply side terminals of both filament electrodes of the discharge lamp La1. The resonance capacitor C2a and the resonance capacitor C2 connected between the non-power supply side terminals of both filament electrodes of the discharge lamp La2.
b and a balancer BR1 for stabilizing the output of the discharge lamps La1 and La2 by having windings n1 and n2 each having one end connected to the power supply side terminal of the other filament electrode of the discharge lamps La1 and La2, From the resonance inductor L1 having one end connected to the other ends of the lines n1 and n2, and the DC cut capacitor C3 connected between the other end of the resonance inductor L1 and the connection midpoint of the switching elements Q1 and Q2. Composed. Here, the inductor L1 and the capacitors C2a and C2
b and C3 form a resonance circuit, and a capacitor C2
a and C2b have a function of preheating the filament electrodes of the discharge lamps La1 and La2.

The control circuit 4 outputs an oscillation control circuit 40 which outputs a signal for controlling ON / OFF of the switching elements Q1 and Q2 by changing the switching frequency, and an output signal of the oscillation control circuit 40 from the switching elements Q1 and Q2. Driver circuit 41 for converting into a drive signal of the discharge lamp La
Abnormality detection unit 49 for detecting the end of life state of La1 and La2
And an oscillation stop control circuit 43 that outputs an oscillation stop signal to the oscillation control circuit 40 to stop switching of the switching elements Q1 and Q2 when the abnormality detection unit 49 detects the end-of-life state of the discharge lamps La1 and La2. When the end-of-life state of the discharge lamps La1 and La2 is detected, switching of the switching elements Q1 and Q2 is stopped to prevent stress on the constituent elements of the inverter circuit 2.

The abnormality detecting section 49 compares the voltage across the resistor R1 with a reference value so that the waveform of the current (resonance current) flowing through the resonance circuit of the resonance load circuit 3 leads the switching frequency of the switching element Q2. A diode D4 having a phase-advancing current detection circuit for detecting that the anode is connected to the connection midpoint between the source of the low-voltage side switching element Q2 and the resistor R1, and the cathode of the diode D4 and the ground. Resistor R connected between
A series circuit of R2 and R3 and resistors R2 and R on the non-inverting input terminal
And a comparator CP2 in which a predetermined reference voltage Vref2 is connected to the inverting input terminal.

Next, the operation for detecting the advance current of the abnormality detecting section 49 will be described. The discharge lamps La1 and La2 are extinguished at the end of life, the resonance operation of the resonance load circuit 3 shifts to the phase advance side, and the resonance current flowing in the resonance load circuit leads the switching frequency of the switching element Q2 (advance phase). ), The peak value of the resonance current flowing through the resonance load circuit 3 increases as compared with the case where the peak value shifts to the lag side. The increase in the resonance current due to the shift of the resonance operation to the phase advance side can be detected by the voltage across the resistor R1 connected in series with the source of the switching element Q2.

The voltage across the resistor R1 for detecting the resonance current is
After being rectified by the diode D4 and divided by the resistors R2 and R3, the comparator CP compares the magnitude with the reference voltage Vref2.
Two compare. When the discharge lamps La1 and La2 are extinguished at the end of their life, the resonance current flowing through the resonance load circuit 3 increases, so that the voltage across the resistor R3 increases and the reference voltage V increases.
When it becomes larger than ref2, the output of the comparator CP2 is inverted from low level to high level.

The oscillation stop control circuit 43, to which a high level signal is input from the comparator CP2, outputs an oscillation stop signal to the oscillation control circuit 40 to stop switching of the switching elements Q1 and Q2.

As described above, a method of detecting the current of the switching element Q2 by the resistor R1 connected in series to the source and comparing the detected value with the reference voltage has been conventionally used as the means for detecting the phase advance operation due to the load abnormality.

[0011]

14 (a) to 14 (d) are time charts for explaining the operation of the conventional example.
The drive signal of the switching element Q2 shown in FIG. 14A turns on the switching element Q2 when it is at high level, and turns off the switching element Q2 when it is at low level. FIG. 14B shows a current flowing through the switching element Q2 in a normal state (without discharging current of the capacitor C4), which is a lag phase with respect to the switching frequency of the switching element Q2, and is regenerated immediately after the switching element Q2 is turned on. The current has a negative amplitude, but gradually increases to a positive amplitude. FIG. 14D is a waveform in which the discharge current of the capacitor C4 is superimposed on the waveform of FIG. 14B, and a whisker-like waveform having a positive amplitude immediately after the switching element Q2 is turned on by this discharge current. Is occurring. FIG. 14C shows the current flowing through the switching element Q2 at the time of abnormality, which is a lead phase with respect to the switching frequency of the switching element Q2. Immediately after the switching element Q2 is turned on, a positive amplitude due to the regenerative current It is a positive amplitude in which a whisker-like waveform due to the discharge current of C4 is superimposed, and its peak value is larger than the peak value of the amplitude in the normal state shown in FIG. 14 (d), and thereafter gradually decreases. Has a negative amplitude.

In the case where the inverter circuit 2 is a dimming inverter, the switching frequency is changed over a wide range, so that the change in the resonance state is also large and the drive signal of the switching element Q2 shown in FIG. Figure 15
FIG. 15B shows a current flowing through the switching element Q2 during dimming (when a discharge current of the capacitor C4 is added), and FIG. 15C shows a current flowing through the switching element Q2 at a full lighting output (when a discharge current of the capacitor C4 is added). . Particularly, at the full lighting output in which the negative amplitude of the regenerative current immediately after the switching element Q2 is turned on becomes small, the discharge current of the capacitor C4 appears remarkably as shown in FIG. 15 (c), and its peak value is shown in FIG. 15 (b). ) It becomes larger than the peak value of the current at the time of dimming. Therefore, at the time of full lighting output, there is a risk of erroneously recognizing that it is in an abnormal state by recognizing it as a phase advance, although it is in a normal state and the current flowing through the switching element Q2 is in a lag phase. Was the cause of.

The present invention has been made in view of the above circumstances, and an object of the present invention is to reliably detect a phase-advancing operation when a resonance circuit has a phase advance when a load abnormality occurs by using a resonance circuit as a load. It is an object of the present invention to provide a power supply device that operates protection control and prevents malfunction due to a transient whisker-like current during switching under normal load.

[0014]

According to a first aspect of the present invention, there is provided a direct current power source for outputting a direct current voltage and at least one switching element, and the switching element is turned on / off to output the direct current power source. An inverter circuit that converts a direct-current voltage to a high-frequency voltage, an inductor, a capacitor, a load, a resonance load circuit that is supplied with high-frequency power from the inverter circuit, and a control circuit that controls the operation of the inverter circuit, The inverter circuit includes a resonance current detection unit that detects a resonance current flowing through the resonance load circuit, and the control circuit includes an oscillation drive unit that controls driving of at least a switching element of the inverter circuit. A predetermined period after a predetermined delay time from the time when the oscillation drive unit turns on the switching element of the inverter circuit It said resonant current detecting unit and having an abnormality detection control unit for detecting an abnormality of the resonant load circuit by the polarity of the resonant current detected at.

According to a second aspect of the present invention, a DC power source for outputting a DC voltage, a high voltage side switching element having one end connected to the high voltage side output of the DC power source, and one end connected to the other end of the high voltage side switching element. Low voltage side switching element, an impedance element having one end connected to the other end of the low voltage side switching element and the other end connected to the low voltage side output of the DC power supply, and one end of the low voltage side switching element and the impedance element An inverter circuit that has at least one snubber capacitor inserted between the other switching element and the other switching element, and that turns on and off the two switching elements alternately to convert the DC voltage output from the DC power supply into a high-frequency voltage. A resonance load circuit including high frequency power from the inverter circuit, the resonance load circuit including an inductor, a capacitor, and a load; A control circuit for controlling the operation of the inverter circuit, wherein the control circuit controls the on / off of at least the switching element of the inverter circuit, and the oscillation drive section controls the switching element of the inverter circuit. An abnormality detection control unit that detects an abnormality of the resonant load circuit according to the polarity of the voltage across the impedance element in a predetermined region after a predetermined delay time from the time of turning on.

According to a third aspect of the present invention, in the first or second aspect, in the predetermined region after the predetermined delay time, a drive signal for turning on the switching element is output from the oscillation drive section, and the switching element is turned on. It is characterized in that the period is set between the time point when the regenerative current generated by turning on turns off and the time point when the drive signal for turning off the switching element is output.

According to a fourth aspect of the present invention, in the first or second aspect, a drive signal for turning off the switching element is output in a predetermined area after the predetermined delay time from a time point substantially half of an ON section of the switching element. It is characterized in that the period is set up to the point before.

According to a fifth aspect of the present invention, in the first or second aspect, the predetermined region after the predetermined delay time is a time point at which a drive signal for turning off the switching element is output.

According to a sixth aspect of the present invention, in the second aspect, a drive signal for turning on the switching element on the low voltage side is output from the oscillation drive section in the predetermined area after the predetermined delay time, and the snubber capacitor outputs the drive signal. The accumulated charge is discharged through the series circuit of the low-voltage side switching element and the impedance element, and the point at which the regenerative current generated by turning on the low-voltage side switching element ends from the point at which the discharge ends It is characterized in that the period is set up to.

According to a seventh aspect of the present invention, a DC power source for outputting a DC voltage, a high voltage side switching element having one end connected to the high voltage side output of the DC power source, and one end connected to the other end of the high voltage side switching element. Low voltage side switching element, an impedance element having one end connected to the other end of the low voltage side switching element and the other end connected to the low voltage side output of the DC power supply, and one end of the low voltage side switching element and the impedance element An inverter circuit for converting a DC voltage output from the DC power supply into a high frequency voltage by having a snubber capacitor inserted between the other end of the DC power supply and the other switching element being alternately turned on / off. A resonant load circuit including a capacitor and a load, and being supplied with high frequency power from the inverter circuit;
A control circuit that controls the operation of the inverter circuit, wherein the control circuit includes an oscillation drive unit that controls ON / OFF of a switching element of the inverter circuit, and the oscillation drive unit includes a switching element of the inverter circuit. The peak value of the voltage across the impedance element at the time of turning on is the charge accumulated in the snubber capacitor when the low-voltage side switching element is turned on, via the series circuit of the switching element and the impedance element. An abnormality detection control unit that detects an abnormality of the resonant load circuit when the voltage is larger than the peak value of the voltage generated in the impedance element due to the flowing current.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 shows a circuit configuration of a power supply device of this embodiment. This power supply device is an AC power supply Vs
And a full-wave rectifier DB that rectifies the output of the AC power supply Vs,
A power supply circuit 1 having a smoothing capacitor to smooth the pulsating current voltage output from the full-wave rectifier DB and output a DC voltage;
It is composed of an inverter circuit 2 for converting the DC voltage output from the power supply circuit 1 into a high frequency voltage, a resonant load circuit 3 to which high frequency power is supplied from the inverter circuit 2, and a control circuit 4 for controlling the operation of the inverter circuit 2. , Full-wave rectifier D
B and the power supply circuit 1 form a DC power supply.

The inverter circuit 2 includes a series circuit of a switching element Q1 on the high voltage side, a switching element Q2 on the low voltage side, and an impedance element Z connected between the output terminals of the power supply circuit 1, and a switching element Q2 and an impedance element Z. Snubber capacitor C4 connected in parallel in series circuit
And a DC voltage output from the power supply circuit 1 is converted into a high frequency voltage by alternately turning on and off the switching elements Q1 and Q2. Specifically, the switching element Q
1, Q2 is F having a parasitic diode reversely connected in parallel
An ET element, the drain of the high-voltage side switching element Q1 is connected to the high-voltage side output of the power supply circuit 1, the drain of the low-voltage side switching element Q2 is connected to the source of the high-voltage side switching element Q1, and the impedance element Z One end of is connected to the source of the switching element Q2 on the low voltage side,
The other end is connected to the low voltage side output of the power supply circuit 1. Furthermore, the low voltage side output of the power supply circuit 1 is connected to the ground. Further, the snubber capacitor C4 slows down the fall and rise of the connection midpoint voltage of the switching elements Q1 and Q2 when the switching element Q2 is on / off to reduce switching loss and noise generated by switching. Has an aim.

The resonant load circuit 3 is connected between the discharge lamps La1 and La2 each having the power supply side terminal of one filament electrode connected to the drain of the switching element Q1 and the non-power supply side terminals of both filament electrodes of the discharge lamp La1. The resonance capacitor C2a and the resonance capacitor C2 connected between the non-power supply side terminals of both filament electrodes of the discharge lamp La2.
b and a balancer BR1 for stabilizing the output of the discharge lamps La1 and La2 by having windings n1 and n2 each having one end connected to the power supply side terminal of the other filament electrode of the discharge lamps La1 and La2, From the resonance inductor L1 having one end connected to the other ends of the lines n1 and n2, and the DC cut capacitor C3 connected between the other end of the resonance inductor L1 and the connection midpoint of the switching elements Q1 and Q2. Composed. Here, the inductor L1 and the capacitors C2a and C2
b and C3 form a resonance circuit, and a capacitor C2
a and C2b have a function of preheating the filament electrodes of the discharge lamps La1 and La2.

The resonance current flowing through the resonance circuit of the resonance load circuit 3 can be detected by extracting the voltage generated across the impedance element Z by the current flowing through the switching element Q2, and the impedance element Z resonates. It forms a resonance current detection unit that detects a current.

The control circuit 4 includes switching elements Q1 and Q.
2 and the discharge lamps La1 and L.
An abnormality detection control unit 42 that detects an abnormality of the resonant load circuit 3 such as the end of life of a2, the discharge lamps La1 and La2 coming off, the discharge lamps La1 and La2 extinguished, and outputs an abnormality signal.
And an oscillation stop control circuit 43 that outputs an oscillation stop signal to the oscillation drive section 46 to stop switching of the switching elements Q1 and Q2 when the abnormality detection control section 42 outputs an abnormal signal.

The oscillation driver 46 turns on the switching elements Q1 and Q2 by changing the switching frequency.
An oscillation control circuit 40 that outputs a signal for controlling the off state and an output signal of the oscillation control circuit 40 are used as switching elements Q1 and Q.
And a driver circuit 41 for converting the driving signal into two driving signals.

The abnormality detection control section 42 receives the voltage across the impedance element Z (current waveform flowing through the switching element Q2) and detects the state of the resonance current, and the oscillation control circuit 40 switches the switching element. An oscillation synchronization circuit 42c that receives a signal corresponding to the drive timing of Q2 and outputs an oscillation synchronization signal synchronized with the drive timing of the switching element Q2, and a detection signal output from the switch current detection circuit 42a A detection timer 42b for setting a detection area for detecting an abnormality in synchronization with an oscillation synchronization signal, and a detection area for detecting an abnormality in the detection signal output from the switch current detection circuit 42a by the detection timer 42b. And the abnormality detection circuit 42d.

Next, the specific operation of this embodiment will be described with reference to the time charts shown in FIGS. The relationship between the waveforms of the currents flowing through the switching element Q2 in the normal state and the abnormal state is similar to that in the conventional example with respect to the drive signal of the switching element Q2 shown in FIG.
Current flowing through the switching element Q2 during normal operation (hereinafter,
The current waveform when the discharge current of the capacitor C4 is added is shown)
Then, the current flows through the switching element Q2 at the time of an abnormality in which the phase advancing operation of FIG.

Therefore, in the present embodiment, the switch current detection circuit 42a determines whether the polarity of the voltage across the impedance element Z (current waveform flowing through the switching element Q2) is positive or negative and outputs a detection signal corresponding to the determination result. Then, the detection timer 42b regenerates a detection region for detecting an abnormality in synchronization with the oscillation synchronization signal with respect to the detection signal output from the switch current detection circuit 42a, which is generated immediately after the switching element Q2 is normally turned on. The period from the time when the current ends to the time when the driving of the switching element Q2 is turned off is set, and as shown in FIG. 2D, a high level detection region signal is output during that period.

Next, the abnormality detection circuit 42d performs an abnormality detection operation only while the detection area signal is at a high level (detection area), and based on the detection signal output from the switch current detection circuit 42a, the switching element Q2. When the polarity of the current flowing through is positive, it is judged to be normal, and when it is negative, it is judged to be abnormal, and an abnormal signal is output when abnormal.

When the oscillation stop control circuit 43 receives the abnormal signal, it outputs an oscillation stop signal to the oscillation drive section 46 to stop the switching of the switching elements Q1 and Q2.

As described above, the abnormality detection region is defined as the period from the end of the regenerative current generated immediately after the switching element Q2 is normally turned on to the time when the driving of the switching element Q2 is turned off. Q
By performing the abnormality detection by discriminating the positive / negative of the current flowing through 2, it is possible to surely detect the phase advance operation at the time of abnormality without causing the erroneous detection at the time of normal which was a problem in the conventional example. it can.

(Second Embodiment) The circuit configuration of the power supply device of the present embodiment shown in FIG. 3 is substantially the same as that of FIG. 1 of the first embodiment, and the resonance load circuit 3 corresponds to only one discharge lamp La1. However, the difference is that the balancer BR1 is not provided.

Specific operation of this embodiment is shown in FIG.
This will be described using the time charts shown in (a) to (e). The relationship between the waveforms of the currents flowing through the switching element Q2 in the normal state and the abnormal state is similar to that in the conventional example with respect to the drive signal of the switching element Q2 shown in FIG.
Of the current flowing through the switching element Q2 in the normal state of FIG.
Switching element Q2 at the time of an abnormality in which the phase advancing operation of (c) is performed
Like the current flowing through.

In the present embodiment, when the discharge lamp La1 comes off, the capacitor C2 is disconnected from the resonance circuit,
As shown in (d), only the discharging current of the snubber capacitor C4 flows through the switching element Q2.

Therefore, in the present embodiment, the switch current detection circuit 42a determines that the voltage across the impedance element Z (current waveform flowing through the switching element Q2) has positive and negative polarities.
0 is detected and a detection signal corresponding to the judgment result is output, and the detection timer 42b causes the switch current detection circuit 4
The detection area for detecting an abnormality in synchronization with the oscillation synchronization signal with respect to the detection signal output from 2a is switched from the time when the regenerative current generated immediately after the switching element Q2 is normally turned on to the end of the switching element Q2. It is set to a period until the driving is turned off, and a high-level detection region signal is output during that period as shown in FIG.

Next, the abnormality detection circuit 42d performs an abnormality detection operation only while the detection area signal is at a high level (detection area), and the switching element Q2 is output based on the detection signal output from the switch current detection circuit 42a. When the polarity of the current flowing through is positive, it is determined to be normal, and when it is zero or negative (zero or less), it is determined to be abnormal, and an abnormal signal is output when abnormal.

When the oscillation stop control circuit 43 receives the abnormal signal, it outputs an oscillation stop signal to the oscillation drive section 46 to stop the switching of the switching elements Q1 and Q2.

As described above, the abnormality detection region is defined as the period from the end of the regenerative current generated immediately after the switching element Q2 is turned on to the time when the driving of the switching element Q2 is turned off in the normal state. By detecting whether the current flowing through the switching element Q2 is positive, negative, or zero, and performing anomaly detection, it is possible to ensure a phase advance operation during anomalies without causing erroneous detection during normal times, which was a problem in the conventional example. It is also possible to detect the load off state.

(Third Embodiment) FIG. 5 shows a circuit configuration of a power supply device according to the present embodiment. The same components as those in FIG. 3 of the second embodiment are designated by the same reference numerals and the description thereof will be omitted. The power supply circuit 1 is
Inductor L2 connected to high voltage side output of full wave rectifier DB
And a diode D1 in a series circuit, a switching element Q3 including an FET connected between the output terminals of the full-wave rectifier DB via the inductor L1, and a smoothing capacitor connected in parallel to the switching element Q3 via the diode D1. It is composed of a step-up chopper circuit composed of C1 and a full-wave rectifier D by turning on / off the switching element Q3.
The pulsating current voltage output by B is boosted, and the DC voltage smoothed by the capacitor C1 is output.

In the inverter circuit 2, a resistor R1 as an impedance element for detecting a resonance current is connected in series to the source of the switching element Q2. Also, a series circuit of a snubber capacitor C4 and a diode D2 having its cathode connected to the snubber capacitor C4 and its anode connected to the low-voltage side output of the power supply circuit 1 is connected in parallel to the series circuit of the switching element Q2 and the resistor R1. Further, a diode D3 having an anode connected to the cathode of the diode D2 and a cathode connected to the control voltage Vcc of the control circuit 4 is provided. This is because the power supply circuit 1 supplies control power to the control circuit 4 via the switching element Q1, the snubber capacitor C4, and the diode D3 when the switching element Q1 is turned on, and when the switching element Q2 is turned on, The electric charge accumulated in the snubber capacitor C4 is discharged through the path of the switching element Q2, the resistor R1, the diode D2, and the snubber capacitor C4, so that the fall and rise of the connection midpoint voltage of the switching elements Q1 and Q2 are blunted. It has a role of reducing switching loss and a noise of switching.

The resonant load circuit 3 includes a switching element Q.
A capacitor C3 for direct current cutting, one end of which is connected to the connection midpoint of 1, Q2, a resonance inductor L1 whose one end is connected to the other end of the capacitor C3, the other end of the inductor L1 and the resistor R1, and the power supply circuit 1 The discharge lamp La1 is connected between the low-voltage side output and the midpoint of connection, and the resonance capacitor C2 is connected to the non-power source side terminal of the discharge lamp La1.
Here, the inductor L1 and the capacitor C2 form a resonance circuit.

The control circuit 4 is a chopper control circuit 44 for controlling ON / OFF of the switching element Q3 of the power supply circuit 1.
And the oscillation control circuit 40 in response to the dimming signal of the discharge lamp La1.
A dimming signal processing circuit 45 for transmitting a variable signal of the switching frequency and duty of the switching elements Q1 and Q2 to
Is equipped with.

The switch current detection circuit 42a of the abnormality detection control section 42 receives the voltage across the resistor R1 (current waveform flowing through the switching element Q2) at its inverting input terminal and the reference voltage Vref1 at its non-inverting input terminal. The abnormality detection circuit 42d is configured by the CP1. The abnormality detection circuit 42d is configured by the AND element IC1 to which the output of the comparator CP1 and the detection area signal output by the detection timer 42b are input.

Specific operation of the present embodiment is shown in FIG.
This will be described using the time charts shown in (a) to (d). The relationship between the waveforms of the currents flowing through the switching element Q2 in the normal state and the abnormal state is similar to that in the conventional example with respect to the drive signal of the switching element Q2 shown in FIG.
Of the current flowing through the switching element Q2 in the normal state of FIG.
Switching element Q2 at the time of an abnormality in which the phase advancing operation of (c) is performed
Like the current flowing through.

In the present embodiment, when the discharge lamp La1 comes off, the capacitor C2 is disconnected from the resonance circuit,
As shown in (d), only the discharging current of the snubber capacitor C4 flows through the switching element Q2.

Therefore, in the present embodiment, the switch current detection circuit 42a determines whether the polarity of the voltage across the resistor R1 (current waveform flowing through the switching element Q2) is positive, negative, or zero, and responds to the determination result. The detection timer 42b outputs a detection signal, and the detection timer 42b detects a detection area in which an abnormality is detected in synchronization with the oscillation synchronization signal with respect to the detection signal output from the switch current detection circuit 42a.
In the period from the end of the regenerative current generated immediately after the switching element 2 is turned on to the time when the driving of the switching element Q2 is turned off, approximately half of the section in which the drive signal of the switching element Q2 is at high level ( 50%) to 90%
, And outputs a high-level detection area signal during that period.

The abnormality detection circuit 42d outputs the detection signal output from the switch current detection circuit 42a as it is only while the detection area signal is at the high level (detection area), and performs the abnormality detection operation. At this time, when the polarity of the current flowing through the switching element Q2 is positive, it is normal, when it is zero or negative (when it is less than zero), it is abnormal, and when it is abnormal, an abnormal signal is output.

When the oscillation stop control circuit 43 receives the abnormal signal, it outputs an oscillation stop signal to the oscillation drive section 46 to stop the switching of the switching elements Q1 and Q2.

Next, the detailed operation of this embodiment will be described with reference to the time charts shown in FIGS. 6A is a drive signal of the switching element Q2, FIG. 6B is a signal input to the comparator CP1 of the switch current detection circuit 42a, FIG. 6C is an output of the switch current detection circuit 42a, and FIG. d) is a detection timer 42b
Detection area signal output by the abnormality detection circuit 4 shown in FIG.
The oscillation stop signals output by 2d are shown respectively, and from the left, respective time charts are shown at the time of normal (slow phase operation), abnormal (advance phase operation), and abnormal (no load). Comparator CP1
The reference voltage Vref1 input to the non-inverting input terminal of
In order to detect the zero level of the current waveform flowing through the switching element Q2 that is input to the inverting input terminal when there is no load abnormality, the offset is slightly offset to the positive side.

First, in the normal state, the switching element Q2
With respect to the drive signal (S1), the detection waveform (S4) of the current of the switching element Q2 has a negative amplitude due to the regenerative current immediately after the switching element Q2 is turned on, but gradually increases to a positive amplitude. . The comparator CP1 compares the detected waveform with the reference voltage Vref1 and outputs a low level signal when the detected waveform is larger than the reference voltage Vref and outputs a high level signal when the detected waveform is smaller than the reference voltage Vref. (S7). Then, the AND element IC1 sets the detection area signal (S10) set in the area of approximately half (50%) or more to 90% or more of the section in which the output of the comparator CP1 (S7) and the drive signal of the switching element Q2 are at high level. AND operation with
Output of AND element IC1 (output of abnormality detection circuit 42d)
Becomes low level in all areas (S13). Therefore, the abnormal signal (high-level signal) is not input to the oscillation stop control circuit 43, and the oscillation stop control does not operate.

Next, during the phase advance operation due to an abnormality, the detected waveform (S5) of the current of the switching element Q2 has a positive amplitude immediately after the switching element Q2 is turned on, with respect to the drive signal (S2) of the switching element Q2. However, it gradually decreases to a negative amplitude. The comparator CP1 compares the detected waveform with the reference voltage Vref1 and outputs a low level signal when the detected waveform is larger than the reference voltage Vref and outputs a high level signal when the detected waveform is smaller than the reference voltage Vref. (S8). Then, the AND element IC1 sets the detection area signal (S11) set in the area of approximately half (50%) to 90% of the section in which the output of the comparator CP1 (S8) and the drive signal of the switching element Q2 are at high level. AND operation with
Output of AND element IC1 (output of abnormality detection circuit 42d)
Goes high in the detection area. Therefore, the oscillation stop control circuit 43, to which the high-level abnormal signal is input, outputs the oscillation stop signal to the oscillation drive section 46 to stop the switching of the switching elements Q1 and Q2.

When there is no load abnormality, the detected waveform (S6) of the current of the switching element Q2 is the switching element Q with respect to the drive signal (S3) of the switching element Q2.
Only the whisker-shaped waveform due to the discharge current of the snubber capacitor C4 immediately after the 2 is turned on. The comparator CP1 compares the detected waveform with the reference voltage Vref1 and outputs a low level signal when the detected waveform is larger than the reference voltage Vref and outputs a high level signal when the detected waveform is smaller than the reference voltage Vref. (S9). And AN
The D element IC1 includes the output of the comparator CP1 (S9) and the detection area signal (S12) set in the area of approximately half (50%) to 90% of the section where the drive signal of the switching element Q2 is at high level. An AND operation is performed, and as a result, the output of the AND element IC1 (output of the abnormality detection circuit 42d) becomes high level in the detection area. Therefore, the oscillation stop control circuit 43, to which the high-level abnormal signal is input, outputs the oscillation stop signal to the oscillation drive section 46 to stop the switching of the switching elements Q1 and Q2.

As described above, the abnormality detection region is within a period from the time when the regenerative current generated immediately after the switching element Q2 is normally turned on to the time when the driving of the switching element Q2 is turned off. , About half of the section in which the drive signal of the switching element Q2 is at high level (50
%) From the above to 90%, the switching element Q
By detecting anomaly by distinguishing between positive, negative, and zero of the current flowing through 2, it is possible to reliably detect the phase advance operation at the time of abnormality without causing the false detection at the time of normality which was a problem in the conventional example. It is also possible to detect the load off state.

(Embodiment 4) FIG. 7 shows a circuit configuration of a power supply device of this embodiment. The same components as those in FIG. 3 of the second embodiment are designated by the same reference numerals and the description thereof will be omitted. The inverter circuit 2 has a resistor R1 as an impedance element for detecting a resonance current connected in series to the source of the switching element Q2.

The resonance load circuit 3 includes a switching element Q.
A capacitor C3 for direct current cutting, one end of which is connected to the connection midpoint of 1, Q2, a resonance inductor L1 whose one end is connected to the other end of the capacitor C3, the other end of the inductor L1 and the resistor R1, and the power supply circuit 1 The load 30 is connected between the low-voltage side output and the midpoint of the connection, and the resonance capacitor C2 is connected to the non-power source side terminal of the load 30. here,
A resonant circuit is composed of the inductor L1 and the capacitor C2.

The abnormality detection control section 42 of the control circuit 4 receives the voltage across the resistor R1 (current waveform flowing through the switching element Q2) and detects the state of the resonance current, and the oscillation control circuit 40. From the switch current detecting circuit 42a and an oscillation synchronizing circuit 42c that receives a signal corresponding to the driving timing of the switching element Q2 from the device and outputs an oscillation synchronizing signal synchronized with the driving timing of the switching element Q2. An abnormality detection circuit 42d that detects an abnormality in a signal within the detection area set by the oscillation synchronization circuit 42c.

Specific operation of this embodiment is shown in FIG.
This will be described using the time charts shown in (a) to (d). Similar to the conventional example, the relationship between the waveforms of the currents flowing through the switching element Q2 in the normal state and the abnormal state is similar to that of the drive signal of the switching element Q2 shown in FIG.
Of the current flowing through the switching element Q2 during normal operation of FIG.
Switching element Q2 at the time of an abnormality in which the phase advancing operation of (c) is performed
Like the current flowing through.

Further, in the present embodiment, when the load 30 is removed, the capacitor C2 is disconnected from the resonance circuit, and FIG.
As shown in (d), only the discharging current of the snubber capacitor C4 flows through the switching element Q2.

Therefore, in the present embodiment, the switch current detection circuit 42a determines whether the polarity of the voltage across the resistor R1 (current waveform flowing through the switching element Q2) is positive, negative, or 0, and responds to the determination result. The detection signal is output, and the oscillation synchronization circuit 42c turns off the drive of the switching element Q2 in the detection region in which an abnormality is detected in synchronization with the detection signal output from the switch current detection circuit 42a in synchronization with the oscillation synchronization signal. Is set at the time (when the drive signal falls).

Next, the abnormality detection circuit 42d performs an abnormality detection operation only in the detection area at the time of the fall of the drive signal, and switches the switching element Q2 based on the detection signal output from the switch current detection circuit 42a. When the polarity of the flowing current is positive, it is determined to be normal, and when it is zero or negative (when it is less than zero), it is determined to be abnormal, and an abnormal signal is output when abnormal.

When the oscillation stop control circuit 43 receives the abnormal signal, it outputs an oscillation stop signal to the oscillation drive section 46 to stop the switching of the switching elements Q1 and Q2.

As described above, the abnormality detection region is determined as the time when the driving of the switching element Q2 is turned off (at the time of the fall of the driving signal), and the current flowing through the switching element Q2 is discriminated between positive, negative and zero. By performing anomaly detection,
It is possible to surely detect the phase advance operation at the time of abnormality without causing the erroneous detection at the time of normality, which was a problem in the conventional example, and it is also possible to detect the off-load state. further,
In this embodiment, the detection timer 42b, which was necessary in the first to third embodiments, is unnecessary.

(Embodiment 5) FIG. 9 shows a circuit configuration of a power supply device of this embodiment. The same components as those in FIG. 3 of the second embodiment are designated by the same reference numerals and the description thereof will be omitted. The inverter circuit 2 has a circuit S, which constitutes a resonance current detector for detecting a resonance current, connected in series to the source of the switching element Q2.

The resonance load circuit 3 has a resonance capacitor C connected between a load 30 having one end connected to the drain of the switching element Q1 and a non-power supply side terminal of the load 30.
2, a resonance inductor L1 having one end connected to the other end of the load 30, and a DC cut capacitor C3 connected between the other end of the resonance inductor L1 and the connection midpoint of the switching elements Q1 and Q2. Composed of. Here, the inductor L1 and the capacitor C2 form a resonance circuit.

Specific operation of this embodiment is shown in FIG.
This will be described using the time charts shown in (a) to (e). Similar to the conventional example, the relationship between the waveforms of the currents flowing through the switching element Q2 in the normal state and the abnormal state is similar to that of the drive signal of the switching element Q2 shown in FIG.
It becomes like the current flowing through the switching element Q2 in the normal state of FIG. 10B and the current flowing through the switching element Q2 in the abnormal state of performing the phase advance operation of FIG.

Further, in the present embodiment, when the load 30 is removed, the capacitor C2 is disconnected from the resonance circuit, and FIG.
As shown in (d), only the discharging current of the snubber capacitor C4 flows through the switching element Q2.

Therefore, in the present embodiment, the switch current detection circuit 42a includes the switching element Q2 output by the circuit S.
The polarity of the current waveform flowing through the positive / negative, 0, and outputs a detection signal corresponding to the determination result, and the detection timer 42b oscillates with respect to the detection signal output from the switch current detection circuit 42a. The charge accumulated in the snubber capacitor C4 is discharged through the series circuit of the switching element Q2 on the low voltage side and the circuit S in the detection region in which the abnormality is detected in synchronization with the synchronization signal, and from the time when the discharge ends, It is set by the time when the regenerative current generated when the switching element Q2 is turned on at the normal time ends.

Next, the abnormality detection circuit 42d performs the abnormality detection operation only while the detection area signal is at the high level (detection area), and the switching element Q2 is output based on the detection signal output from the switch current detection circuit 42a. When the polarity of the current flowing through is positive, it is determined to be normal, and when it is zero or negative (zero or less), it is determined to be abnormal, and an abnormal signal is output when abnormal.

When the oscillation stop control circuit 43 receives the abnormal signal, it outputs an oscillation stop signal to the oscillation drive section 46 to stop the switching of the switching elements Q1 and Q2.

In this way, the charge accumulated in the snubber capacitor C4 is discharged through the series circuit of the switching element Q2 on the low voltage side and the circuit S in the abnormal detection region, and from the time when the discharge ends to the normal time. By detecting whether the current flowing through the switching element Q2 is positive, negative, or zero until the end of the regenerative current generated by turning on the switching element Q2, and performing abnormality detection,
It is possible to surely detect the phase advance operation at the time of abnormality without causing the erroneous detection at the time of normality, which was a problem in the conventional example, and it is also possible to detect the off-load state.

(Sixth Embodiment) FIG. 11 shows a circuit configuration of a power supply device according to the present embodiment. This power supply device is an AC power supply Vs
And a full-wave rectifier DB that rectifies the output of the AC power supply Vs,
Operation of the power supply circuit 1 including a step-up chopper circuit, an inverter circuit 2 for converting a DC voltage output from the power supply circuit 1 into a high frequency voltage, a resonant load circuit 3 supplied with high frequency power from the inverter circuit 2, and an inverter circuit 2. And a control circuit 4 for controlling the power supply. The full-wave rectifier DB and the power supply circuit 1 form a DC power supply.

The power supply circuit 1 is composed of a series circuit of an inductor L2 and a diode D1 connected to the high-voltage side output of the full-wave rectifier DB, and a switching circuit composed of an FET connected between the output terminals of the full-wave rectifier DB via the inductor L1. Element Q3
And a smoothing capacitor C1 connected in parallel with the switching element Q3 via a diode D1 to turn on the switching element Q3.
By turning off, the pulsating voltage output from the full-wave rectifier DB is boosted, and the DC voltage smoothed by the capacitor C1 is output.

The inverter circuit 2 includes a series circuit of a high-voltage side switching element Q1, a low-voltage side switching element Q2, and a resistor R1 connected between output terminals of the power supply circuit 1, and a series circuit of a switching element Q2 and a resistor R1. A series circuit of a snubber capacitor C4 connected in parallel with the snubber capacitor C4, a cathode connected to the snubber capacitor C4 and an anode connected to the low-voltage side output of the power supply circuit 1, and an anode connected to the cathode of the diode D2 to control the cathode. A half bridge type inverter circuit including a diode D3 connected to the control voltage Vcc of the circuit 4 is provided.
By turning Q2 on and off alternately, it is converted into a high frequency voltage. Specifically, the switching elements Q1 and Q2
Is a FET element having a parasitic diode reversely connected in parallel, the drain of the high-voltage side switching element Q1 is connected to the high-voltage side output of the power supply circuit 1, and the drain of the low-voltage side switching element Q2 is the high-voltage side switching element Q1. Of the switching element Q2 on the low voltage side, and the other end is connected to the low voltage side output of the power supply circuit 1. Furthermore, the low voltage side output of the power supply circuit 1 is connected to the ground. The snubber capacitor C4 and the diodes D2 and D3 serve to supply control power from the power supply circuit 1 to the control circuit 4 via the switching element Q1, the snubber capacitor C4 and the diode D3 when the switching element Q1 is turned on. , When the switching element Q2 is turned on, the snubber capacitor C4
The charge accumulated in the switching element Q2, the resistor R1,
By discharging in the path of the diode D2 and the snubber capacitor C4, the fall and rise of the connection midpoint voltage of the switching elements Q1 and Q2 are blunted to reduce switching loss and noise generated by switching. have.

The resonant load circuit 3 includes a switching element Q.
A capacitor C3 for direct current cut, one end of which is connected to the connection midpoint of 1, Q2, an inductor L1 for resonance whose one end is connected to the other end of the capacitor C3, the other end of the inductor L1 and the other end of the resistor R1. Resonance capacitor C connected between
2 and discharge lamps La1 and La in which the power supply side terminals a and e of one filament electrode are respectively connected to the other end of the inductor L1.
2 and windings n1 and n, one ends of which are connected to the power supply side terminals d and h of the other filament electrodes of the discharge lamps La1 and La2, respectively.
2, a balancer BR1 for connecting the other ends of the windings n1 and n2 to the other end of the resistor R1 to stabilize the outputs of the discharge lamps La1 and La2, and the auxiliary winding L11 to the inductor L1.
L14 and capacitors C5 to C8 each having one end connected in series to each end of the auxiliary windings L11 to L14,
The other end of the auxiliary winding L11 is connected to the power supply side terminal a of one filament electrode of the discharge lamp La1, and the other end of the capacitor C5 is connected to the non-power supply side terminal b of one filament electrode of the discharge lamp La1. The other end of the winding L12 is the discharge lamp La1.
Connected to the non-power supply side terminal c of the other filament electrode of
The other end of the capacitor C6 is connected to the power supply side terminal d of the other filament electrode of the discharge lamp La1, the other end of the auxiliary winding L13 is connected to the power supply side terminal e of one filament electrode of the discharge lamp La2, and the capacitor C7 is connected. Is connected to the non-power supply side terminal f of one filament electrode of the discharge lamp La2, the other end of the auxiliary winding L14 is connected to the non-power supply side terminal g of the other filament electrode of the discharge lamp La2, and the capacitor C8 is connected. The other end of is connected to the power supply side terminal h of the other filament electrode of the discharge lamp La2. Here, the auxiliary windings L11 to L1
4 and the capacitors C5 to C8 are discharge lamps La1 and La2.
It has the function of preheating the filament electrode.

The resonance current flowing through the resonance circuit of the resonance load circuit 3 can be detected by extracting the voltage generated across the resistor R1 by the current flowing through the switching element Q2, and the resistor R1 detects the resonance current. It constitutes a resonance current detection unit for detection.

The control circuit 4 includes switching elements Q1 and Q
2 and the discharge lamps La1 and L.
An abnormality detection control unit 42 that detects an abnormality of the resonant load circuit 3 such as the end of life of a2, the discharge lamps La1 and La2 coming off, the discharge lamps La1 and La2 extinguished, and outputs an abnormality signal.
When the abnormality detection control section 42 outputs an abnormality signal, an oscillation stop control circuit 43 that outputs an oscillation stop signal to the oscillation drive section 46 to stop switching of the switching elements Q1 and Q2, and a switching element Q3 of the power supply circuit 1 On
And a chopper control circuit 44 for controlling the off state.

The oscillation driver 46 turns on the switching elements Q1 and Q2 by changing the switching frequency.
An oscillation control circuit 40 that outputs a signal for controlling the off state and an output signal of the oscillation control circuit 40 are used as switching elements Q1 and Q.
And a driver circuit 41 for converting the driving signal into two driving signals.

The abnormality detection controller 42 receives the voltage across the resistor R1 (current waveform flowing through the switching element Q2) and detects the state of the resonance current.
2a, an oscillation synchronization circuit 42c which receives a signal corresponding to the drive timing of the switching element Q2 from the oscillation control circuit 40, and outputs an oscillation synchronization signal synchronized with the drive timing of the switching element Q2, and a switch current detection An abnormality detection circuit 42d for detecting an abnormality in the detection signal output from the circuit 42a in synchronization with the oscillation synchronization signal from the oscillation synchronization circuit 42c.

Specific operation of this embodiment is shown in FIG.
This will be described using the time charts shown in (a) to (d). The relationship between the waveforms of the currents flowing through the switching element Q2 in the normal state and the abnormal state is similar to that in the conventional example with respect to the drive signal of the switching element Q2 shown in FIG.
It becomes the current flowing through the switching element Q2 in the normal state of FIG. 12B and the current flowing through the switching element Q2 in the abnormal state of performing the phase advance operation of FIG.

Further, in the present embodiment, the discharge lamps La1 and La are
When 2 is removed, the capacitor C2 is disconnected from the resonance circuit, and only the discharging current of the snubber capacitor C4 flows in the switching element Q2 as shown in FIG. 12 (d).

Therefore, in the present embodiment, the switch current detection circuit 42a discriminates between the voltage across the resistor R1 (current waveform flowing through the switching element Q2) and the reference voltage (detection threshold value), and the discrimination result. The oscillation synchronization circuit 42c outputs a detection signal corresponding to the above, and the oscillation synchronization circuit 42c drives the switching element Q2 in a detection region in which an abnormality is detected in synchronization with the oscillation synchronization signal with respect to the detection signal output from the switch current detection circuit 42a. Start timing (when the drive signal rises)
Set to.

At this time, the detection threshold value is set to be equal to or higher than the peak value of the voltage generated across the resistor R1 when only the discharge current of the snubber capacitor C4 flows into the switching element Q2.

Next, the abnormality detection circuit 42d performs an abnormality detection operation only at the timing of starting the driving of the switching element Q2, and the current flowing through the switching element Q2 is detected based on the detection signal output from the switch current detection circuit 42a. Normal if the detection threshold or less, switching element Q
When the current flowing through 2 is equal to or higher than the detection threshold value, it is determined to be abnormal, and when abnormal, an abnormal signal is output.

When the oscillation stop control circuit 43 receives the abnormal signal, it outputs an oscillation stop signal to the oscillation drive section 46 to stop the switching of the switching elements Q1 and Q2.

As described above, the abnormality detection region is set to the timing of starting the driving of the switching element Q2 (at the rising edge of the driving signal), and the detection threshold is that only the discharge current of the snubber capacitor C4 flows to the switching element Q2. By setting the voltage to be equal to or higher than the peak value of the voltage generated across the resistor R1 at any time, it is possible to reliably detect the phase advance operation at the time of abnormality without causing the erroneous detection at the time of normality, which was a problem in the conventional example. It is also possible to detect the off-load state. Furthermore, in the present embodiment, the detection timer 42b, which was necessary in the first to third embodiments, is unnecessary.

[0088]

According to the invention of claim 1, it has a direct current power source for outputting a direct current voltage and at least one switching element, and when the switching element is turned on and off, the direct current voltage output by the direct current power source is changed. An inverter circuit for converting into a high frequency voltage, a resonance load circuit including an inductor, a capacitor, and a load, to which high frequency power is supplied from the inverter circuit, and a control circuit for controlling the operation of the inverter circuit are provided. A resonance current detection unit that detects a resonance current flowing through the resonance load circuit, wherein the control circuit includes at least an oscillation drive unit that controls the on / off of a switching element of the inverter circuit, and the oscillation drive unit. In a predetermined region after a predetermined delay time from the time when the switching element of the inverter circuit is turned on, Since it has an abnormality detection control unit that detects an abnormality in the resonance load circuit based on the polarity of the resonance current detected by the oscillating current detection unit, the phase advance operation can be reliably detected when the resonance current becomes a phase advance during a load abnormality. As a result, it is possible to operate the protection control and prevent an erroneous operation due to a transient whisker-like current during switching under normal load.

According to a second aspect of the present invention, a DC power source for outputting a DC voltage, a high voltage side switching element having one end connected to the high voltage side output of the DC power source, and one end connected to the other end of the high voltage side switching element Low voltage side switching element, an impedance element having one end connected to the other end of the low voltage side switching element and the other end connected to the low voltage side output of the DC power supply, and one end of the low voltage side switching element and the impedance element An inverter circuit that has at least one snubber capacitor inserted between the other switching element and the other switching element, and that turns on and off the two switching elements alternately to convert the DC voltage output from the DC power supply into a high-frequency voltage. A resonance load circuit including high frequency power from the inverter circuit, the resonance load circuit including an inductor, a capacitor, and a load; A control circuit for controlling the operation of the inverter circuit, wherein the control circuit controls the on / off of at least the switching element of the inverter circuit, and the oscillation drive section controls the switching element of the inverter circuit. When the snubber capacitor discharge current is generated, since the snubber capacitor has an abnormality detection control unit that detects an abnormality of the resonant load circuit according to the polarity of the voltage across the impedance element in a predetermined region after a predetermined delay time from the time of turning on. However, the same effect as that of claim 1 can be obtained.

According to a third aspect of the present invention, in the first or second aspect, in the predetermined area after the predetermined delay time, a drive signal for turning on the switching element is output from the oscillation drive section, and the switching element is turned on. Since the period is set between the end of the regenerative current generated by turning on and the output of the drive signal for turning off the switching element, the same effect as in claim 1 or 2 can be obtained. You can

According to a fourth aspect of the present invention, in the first or second aspect, a drive signal for turning off the switching element is output from a time point substantially half the ON period of the switching element in the predetermined area after the predetermined delay time. Since the period is set up to the point before the execution, the same effect as that of claim 1 or 2 can be obtained.

According to a fifth aspect of the present invention, in the first or second aspect, the predetermined area after the predetermined delay time is a time point at which the drive signal for turning off the switching element is output. The same effect as can be obtained.

According to a sixth aspect of the present invention, in the second aspect, a drive signal for turning on the switching element on the low voltage side is output from the oscillation drive section in the predetermined area after the predetermined delay time, and the snubber capacitor outputs the drive signal. The accumulated charge is discharged through the series circuit of the low-voltage side switching element and the impedance element, and the point at which the regenerative current generated by turning on the low-voltage side switching element ends from the point at which the discharge ends Since the period is set up to, it is possible to obtain the same effect as that of claim 1 or 2.

According to a seventh aspect of the present invention, a DC power source for outputting a DC voltage, a high voltage side switching element having one end connected to the high voltage side output of the DC power source, and one end connected to the other end of the high voltage side switching element Low-voltage side switching element, an impedance element having one end connected to the other end of the low-voltage side switching element and the other end connected to the low-voltage side output of the DC power supply, and one end of the low-voltage side switching element and the impedance element An inverter circuit for converting a DC voltage output from the DC power supply into a high frequency voltage by having a snubber capacitor inserted between the other end of the DC power supply and the other switching element being alternately turned on / off. A resonant load circuit including a capacitor and a load, and being supplied with high frequency power from the inverter circuit;
A control circuit that controls the operation of the inverter circuit, wherein the control circuit includes an oscillation drive unit that controls ON / OFF of a switching element of the inverter circuit, and the oscillation drive unit includes a switching element of the inverter circuit. The peak value of the voltage across the impedance element at the time of turning on is the charge accumulated in the snubber capacitor when the switching element on the low voltage side is turned on, via the series circuit of the switching element and the impedance element. Since the abnormality detection control unit detects an abnormality of the resonant load circuit when the voltage peak value generated in the impedance element due to the flowing current is larger than the peak value, the same effect as that of claim 1 or 2 can be obtained.

[Brief description of drawings]

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

2A to 2D are time charts showing the operation of the first embodiment of the present invention.

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

4 (a) to (e) are diagrams showing a time chart of the operation of the second and third embodiments of the present invention.

FIG. 5 is a diagram showing a circuit configuration according to a third embodiment of the present invention.

6A to 6E are diagrams showing a time chart of the operation of the third embodiment of the present invention.

FIG. 7 is a diagram showing a circuit configuration according to a fourth embodiment of the present invention.

8A to 8D are diagrams showing a time chart of the operation of the fourth embodiment of the present invention.

FIG. 9 is a diagram showing a circuit configuration according to a fifth embodiment of the present invention.

10 (a) to (e) are diagrams showing a time chart of the operation of the fifth embodiment of the present invention.

FIG. 11 is a diagram showing a circuit configuration according to a sixth embodiment of the present invention.

12A to 12D are time charts showing the operation of the sixth embodiment of the present invention.

FIG. 13 is a diagram showing a circuit configuration of a conventional example.

FIG. 14A is a diagram showing a time chart of the operation of the conventional example.

15 (a) to 15 (c) are diagrams showing a time chart during the light control operation of the conventional example.

[Explanation of symbols]

1 power supply circuit 2 Inverter circuit 3 resonant load circuit 4 control circuit 40 Oscillation control circuit 41 Driver circuit 42 Abnormality detection control unit

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Katsunobu Hamamoto             1048, Kadoma, Kadoma-shi, Osaka Matsushita Electric Works Co., Ltd.             Inside the company (72) Inventor Kei Mitsuyasu             1048, Kadoma, Kadoma-shi, Osaka Matsushita Electric Works Co., Ltd.             Inside the company (72) Inventor Toshikazu Hongo             Ikeda Electric Co., Ltd. No. 404-1, Nishinosue, Himeji City, Hyogo Prefecture             Within the corporation (72) Inventor Hiroshi Yamamoto             Ikeda Electric Co., Ltd. No. 404-1, Nishinosue, Himeji City, Hyogo Prefecture             Within the corporation (72) Inventor Kazushige Ito             Ikeda Electric Co., Ltd. No. 404-1, Nishinosue, Himeji City, Hyogo Prefecture             Within the corporation F term (reference) 3K072 AA02 AB02 AC02 AC11 BA05                       BB01 BC01 DB01 DB03 DB09                       DC07 DC08 DD04 EA02 EB01                       EB05 EB06 EB09 GA02 GB03                       GB12 GC04 HA05 HA06 HA10                       HB01                 5H007 BB03 CA02 CB12 CB23 CC01                       CC07 CC09 DB01 DB02 DC02                       FA00 FA03 FA13 FA14 FA19                       FA20

Claims (7)

[Claims] 1. An inverter circuit having a direct current power source for outputting a direct current voltage and at least one switching element, wherein the switching element is turned on and off to convert the direct current voltage output by the direct current power source into a high frequency voltage. A resonant load circuit including an inductor, a capacitor, and a load, to which high-frequency power is supplied from the inverter circuit,
A control circuit that controls the operation of the inverter circuit, wherein the inverter circuit has a resonance current detection unit that detects a resonance current flowing through the resonance load circuit, and the control circuit is at least a switching element of the inverter circuit. Of the resonance current detected by the resonance current detection unit in a predetermined area after a predetermined delay time from the time when the oscillation drive unit turns on the switching element of the inverter circuit. An abnormality detection control unit that detects an abnormality of the resonant load circuit based on a polarity, the power supply device. 2. A DC power source for outputting a DC voltage, a high voltage side switching element having one end connected to the high voltage side output of the DC power source, and a low voltage side switching element having one end connected to the other end of the high voltage side switching element. Element, an impedance element having one end connected to the other end of the low-voltage side switching element and the other end connected to the low-voltage side output of the DC power supply, and one end of the low-voltage side switching element and the other end of the impedance element An inverter circuit which has at least one snubber capacitor inserted between and which converts the DC voltage output from the DC power supply into a high frequency voltage by alternately turning on and off the two switching elements;
A resonance load circuit including an inductor, a capacitor, and a load, to which high-frequency power is supplied from the inverter circuit, and a control circuit that controls the operation of the inverter circuit, the control circuit including at least a switching element of the inverter circuit. An oscillation drive unit that controls ON / OFF,
An abnormality detection control unit that detects an abnormality of the resonant load circuit by the polarity of the voltage across the impedance element in a predetermined region after a predetermined delay time from the time when the oscillation drive unit turns on the switching element of the inverter circuit. A power supply device having. 3. The predetermined region after the predetermined delay time is a time point when a drive signal for turning on the switching element is output from the oscillation drive unit and the regenerative current generated by turning on the switching element ends. 3. The power supply device according to claim 1, wherein the power supply device is set to a time period from when the drive signal for turning off the switching element is output to when the drive signal is output. 4. The predetermined area after the predetermined delay time is set from a time point of about half of an ON period of the switching element to a time point before a drive signal for turning off the switching element is output. The power supply device according to claim 1 or 2, wherein the power supply device is a period. 5. The power supply device according to claim 1, wherein the predetermined region after the predetermined delay time is a time point when a drive signal for turning off the switching element is output. 6. A drive signal for turning on the switching device on the low voltage side is output from the oscillation drive unit in a predetermined region after the predetermined delay time, and electric charges accumulated in the snubber capacitor are switched on the low voltage side. Discharged through a series circuit of an element and the impedance element, and a period set between the end of the discharge and the end of the regenerative current generated by turning on the low-voltage side switching element The power supply device according to claim 2, wherein 7. A DC power source for outputting a DC voltage, a high voltage side switching element having one end connected to the high voltage side output of the DC power source, and a low voltage side switching element having one end connected to the other end of the high voltage side switching element. Element, an impedance element having one end connected to the other end of the low-voltage side switching element and the other end connected to the low-voltage side output of the DC power supply, and one end of the low-voltage side switching element and the other end of the impedance element An inverter circuit that has a snubber capacitor inserted between the two switching elements and turns on / off the two switching elements alternately to convert a DC voltage output from the DC power supply into a high frequency voltage; and an inductor, a capacitor, and a load. A resonant load circuit supplied with high-frequency power from the inverter circuit, and control for controlling the operation of the inverter circuit And a circuit, the control circuit,
An oscillation drive unit that controls the ON / OFF of a switching element of the inverter circuit, and a peak value of a voltage across the impedance element when the oscillation drive unit turns on the switching element of the inverter circuit has a peak value of the low voltage side. When the charge accumulated in the snubber capacitor when the switching element is turned on is larger than the voltage peak value generated in the impedance element due to the current flowing through the series circuit of the switching element and the impedance element, the resonance An abnormality detection control unit that detects an abnormality in a load circuit, the power supply device.