JP2003031388A - Discharge lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device of high safety that detects the ground positively. SOLUTION: A control part 5 changes the output of a DC-DC converter 6 into an arbitrary value and outputs a control signal for turning on switching elements Q1, Q3 out of switching elements Q1-Q4 of a full bridge circuit of the DC-AC converter 7 to detect the ground through a detecting part 4. Or the control part outputs a control signal for turning on two switching elements Q1, Q2 or Q3, Q4 out of the switching elements Q1-Q4 of the full bridge circuit so as to short-circuit the output of the DC-DC converter 6 through the detecting part 4, to detect the ground through the detecting part 4.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a discharge lamp lighting device,
In particular, the present invention relates to a discharge lamp lighting device mounted on a vehicle and used.

[0002]

2. Description of the Related Art Conventionally, in a vehicle such as an automobile, a voltage from a DC power source such as a battery is boosted by a DC-DC converter, and the boosted voltage is converted into a rectangular wave voltage by a switching element of a full bridge circuit. A discharge lamp lighting device is used that applies a high-voltage pulse to the discharge lamp, short-circuits the discharge lamp with an igniter, and supplies appropriate AC power with a rectangular wave voltage to the discharge lamp to maintain its lighting. There is.

Japanese Laid-Open Patent Publication No. 5-328739 discloses a power converter capable of detecting a ground fault without adding a current detector for ground fault detection and a ground fault detection method therefor.

[0004]

By the way, in the above discharge lamp lighting device for a vehicle, when the discharge lamp is abnormal, for example, when a ground fault occurs, the discharge lamp does not turn on, and depending on the state of the ground fault, The output may continue. But,
It is easy to detect such a ground fault because the load state of the discharge lamp during normal lighting varies from infinity to a state close to a short circuit, and various modes are provided for lighting control. is not.

A conventional method for detecting a ground fault is as follows:
Often the method of detection in normal operation is used,
In many cases, there is no active detection method.

In a normal operation, the control unit of the discharge lamp lighting device detects, when a voltage capable of lighting is input from the input power source, starts the DC-DC converter, and circuitally configures the full bridge circuit. The DC-AC converter is operated so as to apply the rectangular wave voltage (the output voltage having the opposite polarity) to the two inputs of the central discharge lamp.

Further, there is a case where the control unit is required to have a function of relighting the discharge lamp and maintaining the lighting again when the lamp becomes unlit during lighting of the discharge lamp. In this case, it is not detected whether the discharge lamp is abnormal. In such a normal operation, when the cause of the non-lighting is a ground fault, electric power is continuously supplied to the discharge lamp having the ground fault.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a highly safe discharge lamp lighting device that positively detects a ground fault.

[0009]

The invention according to claim 1 for solving the above-mentioned problems is a DC power supply, a discharge lamp, a detecting section for detecting a voltage and a current to the discharge lamp, and a detecting section. A control unit that outputs a control signal using the detected voltage and current, and a switching element that is turned on / off according to the control signal from the control unit are provided. It is composed of a DC-DC converter that boosts a voltage and a switching element of a full bridge circuit that turns on / off according to a control signal from the control unit, and the voltage is boosted by the DC-DC converter by turning on / off these switching elements. A DC-AC converter that converts a voltage into a rectangular wave voltage and applies the voltage to the discharge lamp, and discharges the discharge lamp. A discharge lamp lighting device for a vehicle having an igniter, the control unit, the DC-AC
A ground fault is detected by changing an output of the converter to an arbitrary value and outputting a control signal for turning on one or two switching elements of the switching elements of the full bridge circuit.

According to a second aspect of the present invention, a direct current power source, a discharge lamp, a detector for detecting a voltage and a current for the discharge lamp, and a control signal using the voltage and the current detected by the detector are provided. A control unit that outputs, a DC-DC converter that has a switching element that turns on / off according to a control signal from the control unit, and that turns on / off the switching element to boost the voltage from the DC power supply; and the control unit. Composed of a switching element of a full bridge circuit that turns on / off according to a control signal from
By turning on / off these switching elements, the DC
A discharge lamp lighting device for a vehicle, comprising: a DC-AC converter for converting a voltage boosted by a DC converter into a rectangular wave voltage and applying it to the discharge lamp; and an igniter for discharging the discharge lamp. , The control unit outputs a control signal for turning on two switching elements of the switching elements of the full bridge circuit so that the output of the DC-DC converter is short-circuited via the detection section. It is characterized by detecting a fault.

The invention according to claim 3 is the invention according to claim 1 or 2.
In the discharge lamp lighting device described above, the ground fault is detected at the time of starting.

The invention according to claim 4 is the invention according to claim 1 or 2.
The discharge lamp lighting device described above is characterized in that the ground fault is detected when the light goes out.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 is a configuration diagram of a discharge lamp lighting device according to a first embodiment of the present invention, and FIG. 2 is an explanatory diagram of ground fault detection by the discharge lamp lighting device of FIG. Is.

The discharge lamp lighting device shown in FIG. 1 is used by being mounted on a vehicle, and includes a DC power supply 1 such as a battery.
A discharge lamp 2 such as a high-intensity discharge lamp; and an igniter 3 for applying a high-voltage pulse to the discharge lamp 2 at the time of starting to discharge (start) the discharge lamp 2, a detector 4, and a controller. 5, a DC-DC converter 6, and a DC-AC converter 7. Although not shown in FIG. 1, the igniter 3 has a configuration in which the voltage is boosted in two steps by a no-load voltage and the polarity is inverted without a load. Further, in FIG. 1, the negative terminal side of the DC power supply 1 is the circuit GND.
It has become.

The detector 4 includes a DC-DC converter 6 and a D
It is interposed between the C-AC converter 7 and detects a voltage (lamp voltage) and a current (lamp current) for the discharge lamp 2. In the circuit of FIG. 1, a resistor R41 for detecting a lamp current, and For detecting lamp voltage, resistor R4
1 and the resistors R42 and R43 connected in series between both output terminals of the DC-DC converter 6.

The control unit 5 controls the entire discharge lamp lighting device. For example, in the no-load mode and the lighting mode, the control unit 5 uses the voltage and current detected by the detection unit 4 to generate a DC- DC converter 6 and DC-A
The control for generating and outputting the control signal to the C converter 7 is performed in the same manner as the conventional one, and as a feature of the first embodiment, the control for actively detecting the ground fault in the ground fault detection mode is performed. The control for detecting the ground fault will be described later.

The DC-DC converter 6 is composed of a so-called flyback type circuit including a switching element (FET in FIG. 1) Q6, a transformer T6, a diode D6 and a capacitor C6, and the switching element is operated in accordance with a control signal from the control section 5. When Q6 is turned on / off, the voltage from the DC power supply 1 is boosted and output to the DC-AC converter 7 side. For example (see FIG. 2), in the no-load mode until the discharge lamp 2 starts to light up, the DC-DC is controlled according to the control signal from the control unit 5.
Switching element Q6 is turned on / off so that output voltage V6 of converter 6 is boosted to a voltage of about 360 V or higher. Further, in the lighting mode, the switching element Q is configured to boost the output voltage V6 to a voltage of a predetermined level lower than that in the no-load mode according to the control signal from the control unit 5.
6 turns on / off.

The DC-AC converter 7 is connected in series with the discharge lamp 2 on the output side and switching elements Q1 to Q4 of the full bridge circuit which are connected to the output of the DC-DC converter 6 via the detection section 4. The inductor L1 and the drivers 71 and 72 for the switching elements Q1 to Q4, and the switching elements Q1 to Q through the drivers 71 and 72 according to the control signal from the control unit 5.
4 is switched on / off to operate in various modes. For example (see FIG. 2), in the no-load mode, according to the control signal from the control unit 5, the switching element Q
Switching Q2 and Q3 are turned on while 1,1 and Q4 are turned off, whereby the voltage boosted by the DC-DC converter 6 (about 360 V or higher) is applied to the discharge lamp 2. In the lighting mode, the switching elements Q1 and Q4 and the switching elements Q2 and Q3 are alternately turned on / off according to the control signal from the control unit 5, whereby the voltage boosted by the DC-DC converter 6 is rectangular. It is converted into a wave voltage and applied to the discharge lamp 2.

Here, the control for detecting the ground fault will be described. The control unit 5 changes the output of the DC-AC converter 7 to an arbitrary value (for example, about 100 V), and the switching elements Q1 to Q4 of the full bridge circuit. Among them, a ground fault is detected by outputting a control signal for turning on the switching elements Q1 and Q3.

In the example of FIG. 2, when power is supplied from the DC power supply 1 (t1), the control unit 5 which detects the power and starts the operation turns on the switching element Q6 before controlling the no-load mode. / OFF, the output voltage V6 of the DC-DC converter 6 is boosted to an arbitrary value (for example, about 100V), and at time t2 when the output voltage V6 is boosted to an arbitrary value, the earth fault detection mode is entered and the ground fault detection mode is started. The control for detecting the fault is executed.

When the ground fault detection mode is entered (t2), the switching element Q1 is turned on during the ground fault detection mode with the switching elements Q2 to Q4 kept off, and when a predetermined period T1 has elapsed (t3), the switching element is turned on. Control for turning on Q3 for a predetermined period T2 is executed.

In the predetermined period T1, if a ground fault occurs on the A end side of both ends A and B of the discharge lamp 2 shown in FIG. 1, the resistor R42 of the voltage dividing circuit for detecting the lamp voltage, R
Since the positive electrode side of 43 is connected to the A end side of the discharge lamp 2 in which a ground fault occurs via the switching element Q1, the resistors R42 and R43 that also indicate the output voltage V6 of the DC-DC converter 6 are used. The partial pressure value becomes lower than the partial pressure value indicating the above arbitrary value. Therefore, the voltage division value by the resistors R42 and R43 for lamp voltage detection is monitored, and when the predetermined period T1 is entered, the resistors R42 and R43 are detected.
If the partial pressure value due to is lower than the partial pressure value indicating the above arbitrary value, it is possible to detect that the ground fault has occurred on the A end side of the discharge lamp 2.

In the predetermined period T2, the output voltage V6 of the DC-DC converter 6 is the switching elements Q1 and Q3.
Since the voltage is applied to the A and B ends via the resistor, if a ground fault occurs at the A and B ends, the voltage division value due to the resistors R42 and R43 is less than the voltage division value indicating the above arbitrary value. Also decreases. Therefore, the resistors R42 and R4 for detecting the lamp voltage are
If the voltage divided by the resistors R42 and R43 becomes lower than the voltage divided by the resistors R42 and R43 when the predetermined time period T2 is entered, the ground voltage at the end A of the discharge lamp 2 is monitored. It is possible to detect that a ground fault has occurred and also to detect that a ground fault has occurred on the B end side of the discharge lamp 2. For example, no ground fault has occurred on the A end side,
If a ground fault occurs on the B end side, this predetermined period T
In 2, the ground fault on the B end side is detected.

As described above, according to the first embodiment, the ground fault detection mode is positively provided before the control of the no-load mode to detect the ground fault. It is possible to realize a highly safe discharge lamp lighting device by taking various measures such as the notification of the above, the stop of the operation, or the notification after the operation is stopped. In this case, it is possible to detect the ground fault by using the detecting unit 4 which has been conventionally used, without separately providing an element for detecting the ground fault.

Further, in the case of a circuit configuration in which the igniter generates a high voltage pulse in conjunction with a voltage of about 360 V or more applied to the discharge lamp 2 in the no-load mode, D in the ground fault detection mode.
If the output voltage V6 of the C-DC converter 6 is boosted to a voltage of about 360 V or higher, the igniter will generate a high-voltage pulse. However, in the first embodiment, the DC-DC in the ground fault detection mode is generated. Output voltage V6 of converter 6
Is a voltage of, for example, about 100 V that does not operate the igniter, it is possible to prevent the igniter from operating in the ground fault detection mode. The point is that the ground fault detection mode should be maintained until the igniter generates a pulse.

Further, if the igniter has a structure for storing energy of a pulse (high-voltage pulse) at the time of starting when the output of the full bridge circuit outputs a no-load voltage,
When the initial two switching elements Q1 and Q3 are on,
Since a high voltage of the same potential is applied to both ends A and B of the discharge lamp 1, a high voltage pulse is not generated.

(Second Embodiment) FIG. 3 shows a second embodiment according to the present invention.
FIG. 4 is a configuration diagram of the discharge lamp lighting device of the embodiment, and FIG. 4 is an explanatory diagram of ground fault detection by the discharge lamp lighting device of FIG.

The discharge lamp lighting device shown in FIG.
, The discharge lamp 2, the igniter 3, the detector 4, and the DC-
The DC converter 6 and the DC-AC converter 7 are first
In addition to having the same configuration as that of the embodiment, only the control in the ground fault detection mode is provided with the control unit 5a having a configuration different from that of the first embodiment.

That is, in the example of FIG. 4, when power is supplied from the DC power supply 1 (t11), the control unit 5a, which detects the power and starts the operation, detects it before the control in the no-load mode. When the output of the DC-DC converter 6 is short-circuited (considering the on-resistance of the switching element) via the (resistor R41), the switching element Q6 is turned on / off so that the output current I6 is, for example, about 0.5 A. Then
At time t12 when the output voltage V6 is boosted to that level, control for shifting to the ground fault detection mode and detecting a ground fault is executed.

When shifting to the ground fault detection mode (t12),
Control for turning on the switching elements Q1 and Q2 is executed while keeping the switching elements Q3 and Q4 off for a predetermined period T1. As a result, assuming that a ground fault occurs on the A-end side, all or part of the current flowing out from the positive output terminal of the DC-DC converter 6 causes a ground fault via the switching element Q1. The current flowing through the resistor R41 changes, and the current flowing through the resistor R41 changes.
It is possible to detect that a ground fault has occurred on the A end side of the discharge lamp 2 by monitoring the current value due to.

After this, when a predetermined period T1 has elapsed (t1
3) The control for turning on the switching elements Q3, Q4 is executed while keeping the switching elements Q1, Q2 off for a predetermined period T2. With this, if there is no problem, the resistance R
If a current of 0.5 A flows through 41, but a ground fault occurs on the B end side, the current flowing through the resistor R41 changes, so that the lamp current detection resistor R41 is used at the elapse of a predetermined period T1. If the current value is monitored, B of the discharge lamp 2
It is possible to detect that a ground fault has occurred on the edge side. Further, it is possible to detect whether or not a ground fault has occurred at both the A and B ends during this predetermined period T2.

By the way, as for the detection time, it is possible to sufficiently judge the rising time under no load if it is several ms. DC-
The output of the DC converter 6 will be output at normal power or less. The switching element of the full bridge circuit is F
In the case of ET, the ON resistance of one switching element is about 1Ω, so if 0.5 A is output, an output of several W or less is sufficient. If this is 20
It is possible to detect a ground fault of 0Ω or less.

As described above, according to the second embodiment, the ground fault detection mode is positively provided before the control of the no-load mode to detect the ground fault. Therefore, when the ground fault is detected, for example, to that effect. It is possible to realize a highly safe discharge lamp lighting device by taking various measures such as the notification of the above, the stop of the operation, or the notification after the operation is stopped. In this case, it is possible to detect the ground fault by using the detecting unit 4 which has been conventionally used, without separately providing an element for detecting the ground fault.

(Third Embodiment) FIG. 5 shows a third embodiment of the present invention.
FIG. 6 is a configuration diagram of the discharge lamp lighting device of the embodiment, and FIG. 6 is a configuration diagram of a control unit in the discharge lamp lighting device of FIG.

The discharge lamp lighting device shown in FIG.
, The discharge lamp 2, the igniter 3, the detector 4, and the DC-
The DC converter 6 is provided in the same manner as in the first embodiment, and as a difference from the first embodiment, a D formed by the switching elements Q1 to Q4 and the inductor L1.
The C-AC converter 7a and the control part 5b are provided.

When the control section 5b executes the control in the ground fault detection mode at the time of starting, the initial control 5 is performed as shown in FIG.
It is configured to incorporate one function. There are three modes in the initial control, and in FIG. 6, the LF control 52 includes each mode of ground fault detection, no load (control), and lighting. A ground fault detection unit and a lighting determination unit are provided in a predetermined circuit. In FIG. 6, reference numeral 50 denotes a power supply monitoring function, and 53 denotes a power control function.

When electric power is supplied from the DC power supply 1, the control unit 5b which detects the electric power by the function of the power supply monitor 50 and starts the operation detects the ground fault detection mode → no load (control) mode →
It operates in the order of lighting mode. In the ground fault detection mode, LF
Control 52 turns on one or two switching elements of the full bridge circuit. DC-DC converter 6
Output level of the voltage V6 detected by the detector 4.
And the function of the power control 53 utilizing the current I6.

From the initial control 51 to the power control 53, DC
-The limit of the power command value of the DC converter 6 is passed. This depends on the control method of the DC-DC converter 6, but in a state where there is almost no load, the command value is limited by a normal output command. For example, in the case of PWM control, the output of the DC-DC converter 6 can be applied to the ground fault control even if the output is not large. Therefore, the target should be a value (duty of 50% or less) that does not burden the DC-DC converter 6. Will be possible.

For the initial control, each control time may be set by the frequency counter by the microcomputer and each mode may be switched.

(Fourth Embodiment) The discharge lamp lighting device according to the fourth embodiment of the present invention is
A retry function for shifting to initial control (ground fault detection, no load, lighting) is added to the configuration of the third embodiment.

As a feature of the fourth embodiment, by providing the ground fault detection mode, the ground fault is detected by the ground fault detection mode without being discriminated by the extinction state.
It is not necessary to judge whether or not the discharge lamp 2 is started after the lamp goes out. This occasionally occurs when the vehicle is in the extinguished state due to the vibration of the discharge tube. In that case, the output voltage V6 of the DC-DC converter 6 is increased.
Becomes higher, and it is detected that there is an abnormality, and the discharge lamp lighting device stops. Therefore, if there is a retry function, it is only necessary to set the number of times to retry. For the initial control, it is sufficient to clearly set how many times the initial start control is performed with the power supply voltage kept at the lighting enable voltage. For example, if the number of initial controls after the power is turned on is set to 2 times, the retry will be performed once.

[0042]

As is apparent from the above, the invention according to claim 1 is a DC power supply, a discharge lamp, a detection section for detecting a voltage and a current to the discharge lamp, and a detection section for detecting the voltage and current. And a switching element that turns on / off according to the control signal from the control section, and the voltage from the DC power supply is turned on / off by turning on / off the switching element. It is composed of a DC-DC converter that boosts voltage and a switching element of a full-bridge circuit that turns on / off according to a control signal from the control unit. The voltage boosted by the DC-DC converter is turned on / off by these switching elements. A DC-AC converter for converting into a rectangular wave voltage and applying it to the discharge lamp, and an ignition device for discharging the discharge lamp. A discharge lamp lighting device for a vehicle, comprising: a controller for changing the output of the DC-AC converter to an arbitrary value, and switching one or two of the switching elements of the full bridge circuit. Since the ground fault is detected by outputting the control signal for turning on the element, it is possible to provide a highly safe discharge lamp lighting device that positively detects the ground fault. Here, in the unloaded state at the time of starting, a voltage of, for example, about 360 V or more is applied to the discharge lamp. At this time, the DC-DC converter generates a high voltage of about 360V or higher. During operation of the full-bridge circuit, the four switching elements apply a high potential that is not the circuit GND to the two inputs of the discharge lamp in the center of the full-bridge circuit, and at this time, if there is a ground fault, the potential is increased. Rises below the normal level or does not reach the predetermined voltage, and it is possible to detect that there is an abnormality on the discharge lamp side before lighting. Further, according to the invention described in claim 1, the ground fault can be detected through the detection unit without separately providing a unit for detecting the ground fault.

According to a second aspect of the present invention, a DC power source, a discharge lamp, a detection section for detecting a voltage and a current for the discharge lamp, and a control signal using the voltage and the current detected by the detection section. A control unit that outputs, a DC-DC converter that has a switching element that turns on / off according to a control signal from the control unit, and that turns on / off the switching element to boost the voltage from the DC power supply; and the control unit. Composed of a switching element of a full bridge circuit that turns on / off according to a control signal from
By turning on / off these switching elements, the DC
A discharge lamp lighting device for a vehicle, comprising: a DC-AC converter for converting a voltage boosted by a DC converter into a rectangular wave voltage and applying it to the discharge lamp; and an igniter for discharging the discharge lamp. , The control unit outputs a control signal for turning on two switching elements of the switching elements of the full bridge circuit so that the output of the DC-DC converter is short-circuited via the detection section. Since the fault is detected, it is possible to provide a highly safe discharge lamp lighting device that positively detects the ground fault. Here, even in the normal operation, even when the no-load voltage reaches a predetermined voltage of 360 V or higher,
The operation of the full bridge circuit is changed to a mode in which the output of the DC-DC converter is short-circuited via the detection unit, and the voltage thereof is detected, whereby the abnormality of the ground fault can be detected.
According to the second aspect of the invention, the ground fault can be detected through the detection unit without separately providing a unit for detecting the ground fault.

The invention according to claim 3 is the invention according to claim 1 or 2.
In the discharge lamp lighting device described above, since the ground fault is detected at the time of starting, it is possible to detect the ground fault in the no-load mode and stop the operation, for example.

The invention according to claim 4 is the invention according to claim 1 or 2.
In the discharge lamp lighting device described, since the ground fault is detected at the time of extinguishing, even when the input condition is lighting even in the lighting state, even when the discharge lamp is abnormally turned off and restarted, no load state Since the starting of the discharge lamp starts from, the ground fault can be detected by the no-load mode, and the operation can be stopped, for example.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a discharge lamp lighting device according to a first embodiment of the present invention.

2 is an explanatory diagram of ground fault detection by the discharge lamp lighting device of FIG. 1. FIG.

FIG. 3 is a configuration diagram of a discharge lamp lighting device according to a second embodiment of the present invention.

FIG. 4 is an explanatory diagram of ground fault detection by the discharge lamp lighting device of FIG. 3.

FIG. 5 is a configuration diagram of a discharge lamp lighting device according to a third embodiment of the present invention.

6 is a configuration diagram of a control unit in the discharge lamp lighting device of FIG.

[Explanation of symbols]

1 DC power supply 2 discharge lamp 3 igniter 4 detector 5, 5a, 5b control unit 6 DC-DC converter 7,7a DC-AC converter

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Claims (4)

[Claims] 1. A direct current power supply, a discharge lamp, a detection unit that detects a voltage and a current for the discharge lamp, and a control unit that outputs a control signal using the voltage and the current detected by the detection unit, A DC-DC converter that has a switching element that turns on / off according to a control signal from the control unit, and that turns on / off according to a control signal from the DC-DC converter that boosts the voltage from the DC power supply by turning on / off the switching element. A DC-AC converter configured by switching elements of a full-bridge circuit that turns on / off, and converts the voltage boosted by the DC-DC converter into a rectangular wave voltage by turning on / off these switching elements and applies the rectangular wave voltage to the discharge lamp. And a igniter for discharging the discharge lamp, the discharge lamp lighting device for a vehicle, comprising: The control unit detects the ground fault by changing the output of the DC-AC converter to an arbitrary value and outputting a control signal for turning on one or two switching elements of the switching elements of the full bridge circuit. Discharge lamp lighting device characterized by being. 2. A direct current power supply, a discharge lamp, a detection unit that detects a voltage and a current for the discharge lamp, and a control unit that outputs a control signal by using the voltage and the current detected by the detection unit, A DC-DC converter that has a switching element that turns on / off according to a control signal from the control unit, and that turns on / off according to a control signal from the DC-DC converter that boosts the voltage from the DC power supply by turning on / off the switching element. A DC-AC converter configured by switching elements of a full-bridge circuit that turns on / off, and converts the voltage boosted by the DC-DC converter into a rectangular wave voltage by turning on / off these switching elements and applies the rectangular wave voltage to the discharge lamp. And a igniter for discharging the discharge lamp, the discharge lamp lighting device for a vehicle, comprising: The control section outputs a control signal for turning on two switching elements of the switching elements of the full bridge circuit so that the output of the DC-DC converter is short-circuited via the detection section, thereby causing a ground fault. Discharge lamp lighting device characterized by detecting. 3. The discharge lamp lighting device according to claim 1, wherein the ground fault is detected at the time of starting. 4. The discharge lamp lighting device according to claim 1, wherein the ground fault is detected when the ground fault disappears.