JP2001016863A - Electric power unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten a time required for releasing of stopping of circuit opera tion by temporary off operation of a power switch after stopping of operation of an electric power unit by detection of abnormality, by additionally providing a means shortening a prescribed time in a power off detection means. SOLUTION: Reference voltage Vcc, by dividing it with resistors R3, R4, R5, gives a prescribed voltage for comparing with voltage Vc1 of a capacitor C1 to a + input terminal of a comparator CMP1. A switch Qs is on/off turned by an output Q' of a flip flop FF1, the prescribed voltage for comparing with the voltage Vc1 of the capacitor C1 is switched. A means for shortening a prescribed time generates a high value in the point of stop time of circuit operation, to decrease the voltage Vc1 of the capacitor C1 by off operation of a power switch S1, and changes the value to a low value at the time, when it is re-operation is decided as re-actuatable. In this way, the time for re-actuation by on/off operation of the power switch after stopping of circuit operation by abnormality detection can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device for supplying power to a load, and is applicable to, for example, a discharge lamp lighting device using a discharge lamp as a load.

[0002]

2. Description of the Related Art FIG. 12 shows a circuit diagram of a conventional power supply device. This power supply device is a discharge lamp lighting device that converts a DC power supply E into a voltage, converts it into a rectangular wave voltage, and supplies the voltage to a discharge lamp Lp. In the figure, E is a DC power supply, S1 is a power switch, C1
Is a capacitor of the power input unit, and R2 is a charge discharging resistor of the capacitor C1. A series circuit of the high-frequency switching element Q0 and the primary winding of the transformer T1 is connected to both ends of the capacitor C1. A capacitor C2 is connected to a secondary winding of the transformer T1 via a rectifying diode D1. The negative electrode of the capacitor C2 is the capacitor C1
To the ground potential GND. The high-frequency switching element Q0, the transformer T1, and the diode D1 constitute a DC-DC converter, and convert the voltage of the capacitor C1 to charge the capacitor C2. The voltage of the capacitor C2 is supplied to the discharge lamp Lp via an output alternating full-bridge inverter including low-frequency switching elements Q1 to Q4. R1 is a load current detection resistor, and L1 is a current limiting inductor. Starting circuit 2
Generates a high-voltage pulse and causes dielectric breakdown of the discharge lamp Lp. The control circuit 1 detects a voltage Vc2 corresponding to the load voltage from both ends of the capacitor C2, detects a current corresponding to the load current I1 from both ends of the resistor R1, and further detects the voltage Vc1 of the capacitor C1 of the input unit. Based on the values, the switching elements Q0 and Q
1 to Q4 are controlled.

The operation of the above circuit will be described with reference to FIG.
When the power supply switch S1 is turned on, the power supply smoothing capacitor C1 is charged by the DC power supply E. When the voltage of the power supply smoothing capacitor C1 becomes equal to or higher than a predetermined value, the high frequency switching element Q0 becomes high frequency (several tens of kHz to several tens of kHz). The switching operation starts at 100 kHz). The capacitor C2 is charged with the DC voltage Vc2 boosted to a predetermined voltage. The switching elements Q1 to Q4 have low frequencies (Equation 10).
Hz to several hundreds Hz), the starting circuit 2 operates in response to the output, and generates a high-voltage pulse. The discharge lamp Lp is broken down by application of a high-voltage pulse, and is turned on.
After lighting, an appropriate output is applied to the discharge lamp Lp.
The control circuit 1 causes the switching elements Q0 and Q1 to Q4 to perform a switching operation based on the detected values of the input voltage Vc1, the output voltage Vc2, and the output current I1. As a result, a rectangular wave-like current alternating at a low frequency flows through the discharge lamp Lp.

[0004] The above operation is a normal operation when the discharge lamp is lit. For example, when the power switch S1 is turned on while the discharge lamp Lp is not connected, there is no load.
Generates a high voltage pulse. A predetermined time (for example, 0.7
If the discharge lamp Lp does not turn on even after elapse of (sec), for example, it is detected that the voltage Vc2 of the capacitor C2 does not fall below a predetermined value, and the abnormality detection function of the control circuit 1 operates for safety, and the circuit Stop the operation. This is the discharge lamp Lp
Is connected, for example, even if the discharge lamp Lp is abnormal and cannot be turned on. As described above, when the circuit operation is stopped due to the abnormality detection, the power switch S1 needs to be once turned off and then turned on again to operate the circuit again. This is because when the operation is stopped due to abnormality detection, the power switch S1 is provided for safety.
Is turned off once, and the circuit operation is not permitted again unless the voltage of the capacitor C1 falls below a predetermined value.

FIG. 14 shows an example of a conventional circuit for generating a circuit operation prohibition signal due to abnormality detection and canceling the circuit operation prohibition signal when the power switch S1 is turned off.
The abnormality detection circuit 3 detects the abnormality and detects the
When a high rising signal is applied to the set input terminal S of No. 2, the output Q of the flip-flop FF2 becomes high,
Outputs the circuit operation prohibition signal. The power switch S1 is turned off, and the voltage Vc1 of the capacitor C1 becomes the predetermined value Vre.
When the voltage falls below f3, a high rising signal is input to the reset input terminal R of the flip-flop FF2, whereby the circuit operation prohibition signal becomes low, and the circuit operation prohibition is released.

FIG. 15 shows a voltage waveform of the capacitor C1 when the power switch S1 is turned off and on after the circuit operation is stopped due to abnormality detection. When the power switch S1 is turned on after the lapse of time t1 after the power switch S1 is turned off, the circuit does not operate because the voltage Vc1 of the capacitor C1 does not fall below a predetermined value (the above-mentioned Vref3: for example, 5 V). . Power switch S
1 is turned off, and after a lapse of time t2, the power switch S
When 1 is turned on, the voltage Vc1 of the capacitor C1 becomes equal to or lower than a predetermined value, so that the circuit starts lighting again when the power switch S1 is turned on.

In this case, the predetermined time required for restarting operation is t3. Note that t3 changes depending on the voltage of the power supply E or the like. In order to make the above-mentioned t3 a value that does not cause a problem with the turning on and off of the power switch S1, it is conceivable to reduce the capacitance of the capacitor C1 or the resistance value of the resistor R2. The capacity cannot be easily reduced because of restrictions such as back-up (maintaining lighting) at the moment of a power failure. In addition, if the resistance value of the resistor R2 is reduced, a problem such as a large increase in circuit loss at normal time occurs, so that this cannot be easily reduced.

Next, consider a case where an overvoltage is applied to the input in the conventional example. For example, when an automobile battery is used as the power source E, an overvoltage, which is a battery dump surge, may actually occur. In this case, the applied voltage instantaneously rises to about 60 V and the energy is large. Is charged to 30 V or more. In order to protect the circuit, the circuit operation is stopped, and when the electric charge of the capacitor C1 is gradually released and the voltage Vc1 of the capacitor C1 is within the operable voltage range, the circuit starts the lighting operation and the discharge lamp Lp is lit.

FIG. 16 shows a change in the voltage Vc1 of the capacitor C1 at this time. In the figure, during t4, the discharge lamp Lp maintains the extinguished state. It is not preferable that the discharge lamp Lp be turned off for a long time, and as described above, the reduction of the capacitance of the capacitor C1, the reduction of the resistance value of the resistor R2, and the like are effective for shortening the time t4. However, these cannot be easily reduced.

[0010]

As described above, in the conventional example, in order to restart the circuit after the operation is stopped due to abnormality detection, the power switch must be turned off for a relatively long time in order to turn off and on the power switch. In some cases, even when the power switch is once turned off, it may not operate again when it is turned on again. In addition, when the circuit operation is temporarily stopped to protect the circuit when a high-voltage surge is applied, it takes a long time before the circuit can be restarted. It was a problem.

An object of the present invention is to solve these problems, and an object of the present invention is to release the suspension of the circuit operation by temporarily turning off a power switch after the operation of the power supply is stopped due to abnormality detection. It is an object of the present invention to reduce the time or to shorten a period during which a circuit operation is temporarily stopped when an overvoltage is applied.

[0012]

According to the first aspect of the present invention, in order to solve the above-mentioned problems, a power supply device in which an input section is connected to a power supply via a power switch and a load is connected to an output section. A power supply comprising: abnormality detection means for maintaining a circuit operation in a stopped state when an abnormality is detected; and power-off detection means for canceling the suspension of the circuit operation by the abnormality detection means when a power switch is turned off for a predetermined time or more. In the apparatus, a means for shortening the predetermined time is added.

According to a fifth aspect of the present invention, there is provided a power supply device in which an input unit is connected to a power supply via a power switch, and a load is connected to an output unit.
An overvoltage protection unit for maintaining a circuit operation in a stopped state when an overvoltage is input, and a stop of the circuit operation by the overvoltage protection unit when a voltage of a capacitance component provided at an input unit of the power supply device falls to a predetermined reference voltage or less. And a voltage comparing means for canceling the operation.In the power supply device, when the circuit operation is stopped by the overvoltage protection means at the time of overvoltage input, a charge releasing means for forcibly releasing the charge of the capacitance component is added. I do.

[0014]

(Embodiment 1) FIG. 1 shows a main part circuit configuration of Embodiment 1 of the present invention. The basic circuit configuration of the present embodiment is the same as the conventional example shown in FIG. The basic circuit operation is the same as that of the conventional example shown in FIG.
In FIG. 1, when a high signal is input to the set input terminal S, the flip-flop FF1 changes the output Q 'to low at the rising edge, and when the high signal is input to the reset terminal R, the output Q' changes to the rising edge. High. Vcc is a reference voltage, and resistors R3, R4, R5
, A predetermined voltage for comparison with the voltage Vc1 of the capacitor C1, for example, 5V and 8V is applied to the + input terminal of the comparator CMP1. The switch Qs is turned on / off by the output Q ′ of the flip-flop FF1,
A predetermined voltage for comparison with the voltage Vc1 of the capacitor C1 is switched. An operation stop signal due to abnormality detection is input to the set input terminal S of the flip-flop FF1, and the output Q 'of the flip-flop FF1 is a circuit operation enable signal. When the output Q 'of the flip-flop FF1 is high, the circuit operation becomes possible by turning on the power switch SW again.
Circuit operation is prohibited.

The difference between this embodiment and the conventional example is that the capacitor C1 is used to determine that the power switch S1 has been turned off.
Is to temporarily raise (set to a high value) a predetermined voltage for determining that the voltage Vc1 has dropped after the operation is stopped due to abnormality detection. FIG. 2 shows the operation of this embodiment. The operation of the predetermined voltage is set to a high value (for example, 8 V) when the circuit operation is stopped due to abnormality detection, and when the power switch S1 is turned off, the voltage Vc1 of the capacitor C1 decreases, and when it is determined that re-operation is possible, When the time t5 has elapsed since the switch S1 was turned off, the voltage is changed to a low value (for example, 5 V). As a result, the circuit can be restarted even during the off-time of the power switch S1 which required the time t3 in the conventional example, but also in the time t5 in the present embodiment.

At time t5 when it is determined that the circuit can be restarted.
At the time of switching the predetermined voltage to a lower value,
This is because if the predetermined voltage remains high, a malfunction may occur. In other words, in the circuit operating state, the input voltage Vc1 to the power supply device drops due to the impedance component of the connection line between the power supply E and the power supply device when the circuit operates, and drops below a predetermined high voltage. This is because there are cases where

(Embodiment 2) FIG. 3 shows a main circuit configuration of Embodiment 2 of the present invention. The basic circuit configuration of this embodiment is the same as that of the conventional example shown in FIG. 12, except that a series circuit of a resistor R6 and a switch means S2 for discharging charges is connected in parallel to a resistor R2 connected in parallel to a capacitor C1. different. When the circuit operation is stopped due to the abnormality detection, the charge discharging switch means S2 is turned on. As a result, when the power switch S1 is turned off, the electric charge of the capacitor C1 is quickly released via the resistor R6. As a result, as shown in FIG.
Where the time of t3 is necessary to restart the circuit, the time is greatly reduced to the time of t6.

This embodiment is different from the first embodiment in that the predetermined voltage for determining the decrease of the voltage Vc1 of the capacitor C1 is not temporarily switched to a high value. Even in the case where the voltage falls below a predetermined voltage (for example, 8 V) which is set higher in the first embodiment, it is not determined that the switch S1 is turned off, and a more reliable operation of determining whether the switch S1 is off can be performed. . Further, the switch means S2 for discharging electric charge is turned on only when the circuit operation is stopped due to the abnormality detection, so that there is no increase in loss during the normal circuit operation and the problem of the present invention can be solved.

(Embodiment 3) FIG. 5 shows a main circuit configuration of Embodiment 3 of the present invention. The basic circuit configuration of the present embodiment is the same as the conventional example shown in FIG. 12, except that a constant current circuit Ix is connected in parallel to a resistor R2 connected in parallel to a capacitor C1. When the circuit operation is stopped due to abnormality detection, the constant current circuit Ix is operated. As a result, when the power switch S1 is turned off, the electric charge of the capacitor C1 is released with a substantially constant current, and the off time of the power switch S1 required for the operation of the circuit is changed from the conventional time t3 to t7 as shown in FIG. It can be shortened.

In this embodiment, when the power switch S1 is turned off and the constant is set so that the circuit can be operated again in the same required time (t7 = t6), the circuit operation is stopped due to abnormality detection. After that, when the power switch S1 is on, there is an advantage that the energy (input current to the power supply) consumed from the power supply E can be reduced.

(Embodiment 4) FIG. 7 shows a circuit configuration of a main part of Embodiment 4 of the present invention. The basic circuit configuration of this embodiment is the same as that of the conventional example shown in FIG. 12, except that a series circuit of a resistor R6 and a switch means S2 for discharging charges is connected in parallel to a resistor R2 connected in parallel to a capacitor C1. different. The circuit configuration of FIG. 7 is the same as that of the second embodiment shown in FIG. 3, but is different from the second embodiment in that the charge discharging switch means S2 is turned on by a stop signal of the circuit operation due to a high voltage input. .

FIG. 8 shows an operation waveform diagram of the present embodiment. When a high voltage surge occurs in the power supply E, the voltage Vc1 of the capacitor C1 increases and exceeds a predetermined voltage (for example, 20V). When the voltage Vc1 of the capacitor C1 exceeds the predetermined voltage, a circuit operation stop signal due to a high voltage input is generated for circuit protection, and the circuit operation is stopped. At this time,
By turning on the charge releasing switch S2, it is possible to expedite the release of the charge stored in the capacitor C1, and the time required for the voltage Vc1 of the capacitor C1 to gradually decrease and the circuit to operate again is reduced. Conventional t4 to t
8 can be shortened.

Since this configuration is basically the same as that of the second embodiment, two detection signals, that is, a circuit operation stop signal due to abnormality detection and a circuit operation stop signal due to high voltage input, are used. By driving the switch means S2 for discharging electric charges, both problems can be solved simultaneously.

(Embodiment 5) FIG. 9 shows a main part circuit configuration of Embodiment 5 of the present invention. The basic circuit configuration of the present embodiment is the same as the conventional example shown in FIG. 12, except that a constant current circuit Ix is connected in parallel to a resistor R2 connected in parallel to a capacitor C1. The circuit configuration of FIG. 9 is the same as that of the third embodiment shown in FIG. 5, but is different from the third embodiment in that the constant current circuit Ix is operated by the stop signal of the circuit operation due to the high voltage input.

FIG. 10 shows an operation waveform diagram of this embodiment. When a high voltage surge occurs in the power supply E, the voltage Vc1 of the capacitor C1 increases and exceeds a predetermined voltage (for example, 20V). When the voltage Vc1 of the capacitor C1 exceeds the predetermined voltage, a circuit operation stop signal due to a high voltage input is generated for circuit protection, and the circuit operation is stopped. At this time,
By operating the constant current circuit Ix, it is possible to expedite the release of the electric charge accumulated in the capacitor C1, and the voltage Vc1 of the capacitor C1 gradually decreases, and the time until the circuit is restarted from the conventional time t4. This can be shortened to t9.

Since this configuration is basically the same as that of the third embodiment, two detection signals, that is, a circuit operation stop signal due to abnormality detection and a circuit operation stop signal due to high voltage input, are used. By operating the constant current circuit Ix, both problems can be solved simultaneously.

FIG. 11 shows a specific configuration example of a no-load detection circuit as an example of the abnormality detection circuit. Vc2 in FIG.
This is a detection value obtained by dividing the voltage of the capacitor C2 in the basic circuit configuration shown in FIG. The detected value Vc2 of the voltage of the capacitor C2 is input to the comparator CMP2 of the voltage comparator 4, and is compared with the reference voltage Vref1. On the other hand, the timer circuit 5 includes a current source Is, a capacitor Cs, a comparator CMP3, and a reference voltage Vref2, and charges the capacitor Cs with the current source Is. When the charged voltage exceeds the reference voltage Vref2, the output becomes high. .
Here, the timer circuit 5 operates for a predetermined time (for example, 0.7
The output goes high after the elapse of seconds). Comparator C
The outputs of MP2 and CMP3 are input to the AND circuit 6,
The logical product signal becomes the abnormality detection signal.

The operation of the circuit shown in FIG. 11 will be described below. When the detected value Vc2 of the voltage of the capacitor C2 is higher than the predetermined reference voltage Vref1, a signal indicating that the discharge lamp Lp is not lit or no load is output from the comparator CMP2 as a high signal. The output of the comparator CMP3 becomes high after a predetermined time elapses after the power is turned on. Therefore, the output of the AND circuit 6 becomes high when the load is not loaded or not lit at the time when the predetermined time has elapsed, and an abnormal state of the load can be detected.

By the way, in FIG. 12 of the conventional example, a current limiting inductor L1 is provided as a countermeasure against a current surge at the time of low frequency output reversal. For example, this is performed by driving the switching elements Q1 to Q4 slowly. That is,
It may be omitted by using an active area or the like. Further, at the time of low frequency output reversal in a no-load state where a current surge is a problem, the switching elements Q1 to Q4
There is also a method of reducing the loss due to switching by slowing the driving of the gate of the FET constituting the device, using the active region, and performing the gate driving quickly in the steady state.

Further, for example, during the period when a large current flows when the light flux of the discharge lamp Lp rises, the switching elements Q1 to Q4
A drive method for reducing the loss, such as reducing the loss due to the FET on-resistance in the large current region by increasing the drive voltage to the gate of the transistor above normal, can be considered.

[0031]

According to the first to fourth aspects of the present invention, there is provided a power supply device in which an input section is connected to a power supply via a power switch and a load is connected to an output section. In a power supply device comprising: abnormality detecting means for maintaining the state, and power-off detecting means for canceling the stop of the circuit operation by the abnormality detecting means when the power switch is turned off for a predetermined time or more. With the addition, it is possible to shorten the re-operable time by turning off and on the power switch after the circuit operation is stopped due to the abnormality detection.

According to the fifth and sixth aspects of the present invention, there is provided a power supply device in which an input unit is connected to a power supply via a power switch, and a load is connected to an output unit. Overvoltage protection means for maintaining a state, and voltage comparison means for releasing the suspension of the circuit operation by the overvoltage protection means when the voltage of the capacitance component provided at the input unit of the power supply device falls below a predetermined reference voltage. In the power supply device having the above structure, when the circuit operation is stopped by the overvoltage protection means at the time of overvoltage input, charge discharging means for forcibly releasing the charge of the capacitance component is added, so that the circuit in the case where an overvoltage surge is applied Operation stop time can be shortened.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a main part circuit configuration of a first embodiment of the present invention.

FIG. 2 is a waveform chart for explaining the operation of the first embodiment of the present invention.

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

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

FIG. 5 is a circuit diagram showing a main part circuit configuration of a third embodiment of the present invention.

FIG. 6 is a waveform chart for explaining the operation of the third embodiment of the present invention.

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

FIG. 8 is a waveform chart for explaining the operation of the fourth embodiment of the present invention.

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

FIG. 10 is a waveform chart for explaining the operation of the fifth embodiment of the present invention.

FIG. 11 is a circuit diagram showing a configuration of a no-load detection circuit as an example of an abnormality detection circuit used in the present invention.

FIG. 12 is a circuit diagram showing a circuit configuration of a conventional power supply device.

FIG. 13 is a waveform chart for explaining the operation of the conventional power supply device.

FIG. 14 is a circuit diagram showing a circuit configuration for prohibiting and releasing a circuit operation due to abnormality detection in a conventional example.

FIG. 15 is a waveform chart for explaining a recovery operation after a circuit operation is stopped due to abnormality detection in a conventional example.

FIG. 16 is a waveform diagram for explaining a circuit operation stop when an overvoltage is applied in a conventional example.

[Explanation of symbols]

 C1 Capacitor at power input S1 Power switch S2 Charge release switch R6 Charge release resistor

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H007 AA17 BB03 CA02 CB05 CC01 DB01 DC05 FA01 FA12 GA08 5H730 AS11 BB23 DD03 DD16 EE07 FD11 FG01 XX02 XX12 XX22 XX32 XX44 5H740 BA12 BB05 BB08 BB10 BC01 BC02 MM01

Claims (6)

[Claims] 1. A power supply device having an input unit connected to a power supply via a power switch and a load connected to an output unit, wherein abnormality detection means for maintaining circuit operation in a stopped state when an abnormality is detected, and a power switch. A power supply device comprising: a power-off detection means for canceling a stop of a circuit operation by an abnormality detection means when the power supply is turned off for a predetermined time or more, wherein a means for shortening the predetermined time is added. 2. The power supply off detection means determines that a power supply switch is turned off for a predetermined time or more when a voltage of a capacitance component provided at an input unit of the power supply device drops to a predetermined reference voltage or less. 2. The power supply device according to claim 1, further comprising a comparing unit, wherein the unit for shortening the predetermined time is a unit for raising a reference voltage of the voltage comparing unit when the circuit operation is stopped by the abnormality detecting unit. 3. The power-off detecting means determines that a power switch has been turned off for a predetermined time or more when a voltage of a capacitance component provided at an input unit of the power supply device has dropped to a predetermined reference voltage or less. 2. The power supply according to claim 1, further comprising a comparing unit, wherein the unit for shortening the predetermined time is a charge releasing unit for forcibly releasing the charge of the capacitance component when the circuit operation is stopped by the abnormality detecting unit. apparatus. 4. The power supply device according to claim 3, wherein said charge discharging means comprises means for discharging a charge of said capacitance component at a substantially constant current. 5. A power supply device having an input section connected to a power supply via a power switch and a load connected to an output section, wherein overvoltage protection means for maintaining a circuit operation in a stopped state when an overvoltage is input, and said power supply A voltage comparing means for canceling the suspension of the circuit operation by the overvoltage protection means when the voltage of the capacitance component provided at the input part of the apparatus drops to a predetermined reference voltage or less. A power supply device, further comprising a charge discharging means for forcibly releasing the charge of the capacitance component when the circuit operation is stopped by the means. 6. The power supply device according to claim 5, wherein said charge discharging means comprises means for discharging a charge of said capacitance component at a substantially constant current.