JP2000306687A - Control method for high pressure discharge lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control current through a high pressure discharge lamp just after turned on, use the high pressure discharge lamp most efficiently, electrically detect a fact that it reaches the end of the life after a long use, and sound an alarm. SOLUTION: This method is a control method of a high pressure discharge lamp 35 such as a high pressure mercury lamp, a metal halide lamp, or a high pressure sodium lamp. A circuit 36 for detecting load voltage and current is provided, constant current control is performed just after the high pressure discharge lamp 35 is turned on, and changeover to constant current control is performed when load voltage (lamp voltage) of the high pressure discharge lamp 35 reaches a predetermined voltage or load power of the high pressure discharge lamp 35 reaches a predetermined power value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a high-pressure mercury lamp,
The present invention relates to a control method for efficiently lighting a high-pressure discharge lamp such as a metal halide lamp and a high-pressure sodium lamp.

[0002]

2. Description of the Related Art High-intensity discharge lamps such as high-pressure mercury lamps, high-pressure sodium lamps, and metal halide lamps are used as various light sources in streets, factories, and the like. Conventionally, as a lighting device for such a high-pressure discharge lamp, there is a method in which a normal AC power supply is used as a power supply and a high voltage is generated by using a reactor and a thyristor to light the lamp, but the efficiency is poor and the lamp life is short. There are drawbacks. Therefore, the present applicant has previously set the alternating current to a direct current in Japanese Patent Application Laid-Open No. 9-245975,
A power supply device for lighting a high-pressure discharge lamp using an inverter that converts this into a high-frequency alternating current again was proposed.

[0003]

However, in the power supply device for a high-pressure discharge lamp described in the above-mentioned publication, since the load voltage is low immediately after lighting, an excessive current flows, thereby shortening the life of the electrode. there were. Further, the high-pressure discharge lamp gradually deteriorates and its illuminance decreases when used for a long period of time, but there is a problem that no countermeasure is taken against this. The present invention has been made in view of such circumstances, and controls the current flowing through the high-pressure discharge lamp even immediately after lighting, to use the high-pressure discharge lamp as efficiently as possible, and to use the high-pressure discharge lamp for a long period of time. An object of the present invention is to provide a control method for a high-pressure discharge lamp that can electrically detect this and generate an alarm.

[0004]

According to the present invention, there is provided a method for controlling a high-pressure discharge lamp such as a high-pressure mercury lamp, a metal halide lamp, a high-pressure sodium lamp, and the like. A circuit for detecting a load voltage and a load current of the electric lamp; and a constant current control is performed immediately after the high-pressure discharge lamp is turned on, so that a load voltage of the high-pressure discharge lamp (that is, a lamp voltage) is a predetermined voltage or the high voltage. When the load power of the discharge lamp reaches a predetermined power value, the control is switched to constant power control. In the method for controlling a high-pressure discharge lamp according to the present invention, it is preferable that the high-pressure discharge lamp uses a high frequency that is PWM-controlled using an inverter, so that a high-efficiency high-pressure discharge lamp can be lit. In the method for controlling a high-pressure discharge lamp according to the present invention, when the high-pressure discharge lamp reaches or exceeds a predetermined voltage during the constant power control of the high-pressure discharge lamp, the lamp life may be over. It is preferable to generate an alarm signal for notifying that the life of the high-pressure discharge lamp can be managed. Then, after the high-pressure discharge lamp emits the alarm signal, when the high-pressure discharge lamp is lit for a further predetermined time, it is more preferable to stop energizing the high-pressure discharge lamp. Lights can be turned off during use or accidents can be prevented.

In the control method for a high-pressure discharge lamp according to the present invention, it is preferable that the following relational expression is provided, where the frequency of the PWM modulated carrier wave is fc and the output frequency of the inverter circuit is fp. . fc / fp = 4 · n (where n: an integer) (A) Thereby, the following (1) to (3) are satisfied, the waveform flowing through the discharge lamp is stabilized, and No flashing variation or the like will occur. (1) There is no positive or negative imbalance in the output waveform. (2) There is a waveform of the maximum width of the PWM modulated carrier wave at a phase angle position of 90 degrees and 270 degrees of the output waveform.
As a result, the output waveform is not distorted. (3) 0 of output waveform
The output of the carrier wave of PWM modulation is always 0 at the positions of degrees, 180 degrees and 360 degrees. Here, it is preferable to use fp at least 4 times and at most 40 times the commercial frequency in terms of efficiency, wiring loss, and the like, but the present invention is not limited to this range. In the high-pressure discharge lamp power supply device to which the control method of the high-pressure discharge lamp according to the present invention is applied, it is preferable that the resonance capacitor is selected so as to resonate at twice the frequency of the PWM modulated carrier wave. Thereby, the connected individual high-pressure discharge lamps can be turned on at an appropriate ignition angle.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention. FIG. 1 is a circuit diagram of a high-pressure discharge lamp power supply device to which a high-pressure discharge lamp control method according to an embodiment of the present invention is applied, and FIGS. 2 (A), (B), and FIG.
(A) and (B) are output waveform diagrams for the PWM modulation output, respectively, and FIG. 4 is an operation flow chart of the control method of the high pressure discharge lamp.

As shown in FIG. 1, a power supply device 10 for a high-pressure discharge lamp to which a method for controlling a high-pressure discharge lamp (for example, a metal halide lamp) according to an embodiment of the present invention is applied. The following three-phase AC bridge type rectifier 11 and an inverter circuit 12 using the output thereof as a power supply
And a transformer 13 connected to the output side. Hereinafter, these will be described in detail.

The power switch 11a, which is a magnet switch in this embodiment, is closed when an exciting coil (not shown) is energized, and is closed.
1 three-phase AC power supply. Bridge type rectifier 11 connected to this power switch 11a
In front of the reactors 14-16 and capacitors 17-1
9 are provided to prevent radio frequency noise (high frequency) from being supplied to the power supply side from the power supply device, and include reactors 14 to 16 having a small inductance and capacitors 17 to 19. I have.
The capacitor 20 provided on the output side of the bridge type rectifier 11 having six rectifying elements (diodes or thyristors) is a capacitor having a very small capacity, and is a capacitor for absorbing radio noise. A smoothing circuit is provided on the output side of the bridge rectifier 11, and the smoothing circuit includes reactors 21 and 22 and a capacitor 23 having a large capacity. The reactors 21 and 22 also serve to improve the power factor of three-phase alternating current.

The DC (approximately 280 V), which has become substantially uniform through the smoothing circuit, is input to the next inverter circuit 12. The inverter circuit 12 has four FETs 24 to 27, similar to a normal PWM modulation circuit.
By alternately turning on the FETs 4 and 27 and the FETs 25 and 26 at the same time, as shown in FIGS. 2 and 3, a high-frequency alternating current having a relatively high frequency is generated on the output side. PW
The frequency fc of the carrier wave (carrier wave) of M modulation is 8 kHz.
And the output frequency fp under load is 333 Hz. As shown in FIG. 3 (A), the output waveform of the PWM has a positive and negative output half cycle (T / 2) such that its effective value becomes a sine wave like a normal AC.
At first, the pulse width is narrow and gradually widens, the pulse width reaches the maximum width around 90 degrees, and thereafter the pulse width gradually decreases. The control of the four FETs 24 to 27 constituting the inverter circuit 12 is performed by a program recorded in advance by a computer 28 which is a control device having a CPU, and the output signal is set to a predetermined power by a base drive circuit 29. Later, each FET 24-2
7 is being driven.

The output of the inverter circuit 12 is provided with small-capacity reactors 30 and 31 and a small-capacity capacitor 32 for removing the radio nozzle, and the output is input to the primary side of the transformer 13. This transformer 13 is composed of a leakage transformer and has a primary: secondary winding ratio of 1:
1.5. Thereby, the inverter circuit 1
2, the voltage of 190 V at the time of load is boosted to about 300 V. On the output side of the transformer 13, a stabilizer capacitor (20 μF) 33 is connected in series, and a resonance capacitor (in this embodiment, 2 μF) is connected.
(500 pF) 34 are connected in parallel. The capacitance of the resonance capacitor 34 is Cx, the reactance when the transformer 13 is viewed from the secondary side is L, and the frequency of the PWM modulated carrier wave is fc (8 kHz in this embodiment).
z), the value of Cx is determined so as to satisfy the following equation (B). 2 · fc = 1 / (2πL ^1/2 · Cx ^1/2 ) (B) Accordingly, the frequency fc of the PWM modulated carrier wave is output to the output side.
A high voltage having a frequency of 16 kHz which is twice as high as that of FIG.

This situation is shown in FIGS. FIG. 3 (A)
FIG. 3B shows a waveform on the secondary side when the voltage on the primary side of the transformer 13 is set to 170 V in FIG.
-P) It can be seen that a high voltage of 1800 V is generated. This is because the on / off duty of the carrier wave of the PWM modulation becomes 50% just in the vicinity of this, so that the transformer 13
This is because the conversion efficiency at 16 kHz becomes maximum. On the other hand, FIGS. 2A and 2B show transmission waveforms when the voltage on the primary side of the transformer 13 is set to 70 V.
It can be seen that when the voltage of the WM modulation wave is low, the transmission voltage is also relatively low. Therefore, the secondary voltage is adjusted so that the high-pressure discharge lamp 35 is turned on at a position where the no-load voltage is around 60 degrees.

The load voltage (lamp voltage) of the high-pressure discharge lamp 35
And a detection circuit 36 for measuring the load current
3 is provided on the secondary side. The circuit for detecting the load current includes a CT (current transformer or a Hall element), and the circuit for detecting the load voltage includes a PT (voltage converter) or a shunt resistor. As a result, the load condition is detected and A / D-converted by the feedback circuit 37, input to the computer (CPU) 28, and perform PWM modulation constant current and / or constant power control. The computer 28 includes a ROM that stores a control program for the high-pressure discharge lamp power supply device 10, and further includes a RAM and an IF (interface) necessary for the operation of the computer 28. In FIG. 1, reference numeral 38 denotes a power supply circuit, 39 denotes an operation panel (display) having lamps connected to the computer 28, and 40 denotes a coil of the power switch 11a connected to the computer 28.

Next, a control method of the high pressure discharge lamp according to one embodiment of the present invention will be described with reference to FIG. When a power switch (not shown) provided on the operation panel 39 is turned on, the power switch 11a is turned on,
The three-phase alternating current is rectified by the bridge-type rectifier 11 to be a direct current, and the inverter circuit 12 generates a PWM-modulated high frequency. At this time, the high-pressure discharge lamp 35 is not lit, so that there is no load, and the output side is shown in FIG.
A high voltage having a frequency twice as high as that of the carrier wave of the PWM modulation as shown in (B) is generated (step 1s). When the phase angle of the sine wave a is about 60 degrees, an arc is generated between the electrodes of the high-pressure discharge lamp 35 at about 60 degrees of the 333 Hz alternating current, and the current that increases thereafter increases the main current. Flows. When the main current flows, the generation of the high voltage stops, the power supply voltage is about 300 V, and the frequency is 333 H
The current z flows through the high-pressure discharge lamp 35. Thus, the high-pressure discharge lamp 35 is turned on to maintain the discharge state (step 2s).

When the high-pressure discharge lamp 35 starts lighting, a constant current control is first performed (step 3s). The reason is that the internal resistance of the high-pressure discharge lamp 35 is relatively small at the time of lighting, and an excessive current flows when a rated voltage of the high-pressure discharge lamp 35 or a voltage near the rated voltage is applied. This is because it occurs. Here, in the conventional system using a ballast such as a reactor or a capacitor as a constant voltage power supply, the starting current at the time of discharging is relatively small, and it takes time for the high-pressure discharge lamp 35 to be in a stable state. Then, a normal discharge state is reached in a relatively short time. The value of the current is a rated current of the high-pressure discharge lamp 35 or a current close to the rated current. When the high-pressure discharge lamp 35 is turned on, the voltage gradually increases. This voltage is detected by the above-described voltage detecting means such as the PT and the shunt resistor (step 4s), and it is detected that the voltage has become equal to or higher than the predetermined voltage Vs. (Step 5s)
Switch to constant power control (step 6s).

As a result, the load on the high-pressure discharge lamp 35 becomes constant, so that the high-pressure discharge lamp 35 is stably lit. Note that the predetermined voltage Vs in this case is the high voltage discharge lamp 3
Set to the rated voltage of 5 or its vicinity. Here, when the internal resistance of the high-pressure discharge lamp 35 at the time of lighting increases, the load voltage increases, and when the power supply voltage changes, the load voltage also changes accordingly. The load voltage (lamp voltage) of the high-pressure discharge lamp 35 is detected, and P is set so that the measured voltage V × the measured current I becomes constant.
The WM modulation wave width is controlled. Since the high-pressure discharge lamp 35 is driven at a high frequency of 333 Hz, the power efficiency increases and the power factor becomes approximately 1 as compared with a high-pressure discharge lamp that is lit at a normal commercial frequency.

While maintaining this state, the high pressure discharge lamp 35
Performs a lighting operation, and turns off when the power switch is turned off (steps 8s and 9s). However, when the life of the high-pressure discharge lamp 35 approaches, the internal resistance of the high-pressure discharge lamp 35 at the time of lighting increases, and the constant power control is performed. Then, the lamp voltage V increases. Therefore, when the lamp voltage V exceeds the specified voltage Vm, which is, for example, 1.15 times the rated voltage (step 7s), an alarm signal is sent to notify that the lamp life has come (step 10s). This alarm signal may be a lamp display, a buzzer, or the like. If the lighting operation of the high-pressure discharge lamp 35 is performed even after this alarm signal is issued, it is confirmed that a predetermined time (for example, 2 to 10 hours) has elapsed (step 11s).
The light is turned off (step 9s). If constant power control is performed in the lighting operation of the high-pressure discharge lamp 35 after the generation of the alarm signal, the voltage may suddenly rise and may be dangerous. Therefore, the constant current control is performed by stopping at a specific voltage (for example, Vm). May be performed.

In the above-described embodiment, the resonance capacitor is transmitted at twice the frequency of the PWM modulation wave. However, the capacitor is resonated at the fundamental wave of the PWM modulation wave or at an integral multiple of twice the fundamental wave. The present invention is also applied to the case of selection. In the above embodiment, the case where a high pressure discharge lamp is used as a load has been described. However, the present invention is also applicable to a high pressure discharge lamp such as a normal high pressure mercury lamp and a high pressure sodium lamp. Further, in the above embodiment, the phase advance capacitor is used as the stabilizer, but it may be a reactor. Further, in the above-described embodiment, the frequency fc of the PWM modulated carrier wave is set to 8 kHz and the output frequency is set to 333 Hz. However, a frequency satisfying the expression (A) (for example, fc = 16 kHz)
If z, fp = 444 Hz, etc.), other frequencies can be applied. In the above embodiment, the power is turned on and off by providing a power switch (magnet switch) 11a on the primary side of the bridge type rectifier and turning it on and off. It can be performed by controlling the voltage (current), or by providing a magnet switch on the secondary side of the inverter circuit 12. In the above-described embodiment, the control is switched to the constant power control when the load voltage of the high-pressure discharge lamp reaches a predetermined voltage, but when the load power of the high-pressure discharge lamp reaches a predetermined power value. The control may be switched to constant power control.

[0018]

The method for controlling a high-pressure discharge lamp according to any one of claims 1 to 4 includes a circuit for detecting a voltage and a current of a load, and performs a constant current control immediately after the high-pressure discharge lamp is turned on, so that the load voltage is controlled in advance. At the time when the predetermined voltage or load power reaches the predetermined power value, the operation is switched to the constant power control, so that the lighting operation is performed without flowing an excessive current that causes the electrodes of the high-pressure discharge lamp to wear, The life of the high pressure discharge lamp is prolonged. Also,
Since the current immediately after lighting of the high-pressure discharge lamp is secured, the high-pressure discharge lamp shifts to the normal lighting operation within a short time as compared with the current control method using the conventional ballast. In particular, claim 2
In the control method for a high-pressure discharge lamp described above, the high-pressure discharge lamp uses a high frequency controlled by PWM using an inverter, so that the lighting efficiency is improved as compared with a case where a commercial frequency is used. In the control method of the high-pressure discharge lamp according to the third aspect, when the high-pressure discharge lamp reaches or exceeds a predetermined voltage during the constant power control of the high-pressure discharge lamp, it is notified that the lamp life has expired. Since the alarm signal is issued, the life of the high-pressure discharge lamp can be surely known, so that the high-pressure discharge lamp can be properly replaced. And in the control method of the high pressure discharge lamp of Claim 4,
If the high-pressure discharge lamp emits an alarm signal and remains lit for a predetermined period of time, the power supply to the high-pressure discharge lamp is stopped, preventing explosions and accidents due to the high voltage of the high-pressure discharge lamp. it can.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a high-pressure discharge lamp power supply device to which a high-pressure discharge lamp control method according to an embodiment of the present invention is applied.

FIGS. 2A and 2B are output waveform diagrams with respect to a PWM output.

FIGS. 3A and 3B are output waveform diagrams with respect to a PWM output.

FIG. 4 is a flowchart of a method for controlling a high-pressure discharge lamp according to one embodiment of the present invention.

[Explanation of symbols]

10: High pressure discharge lamp power supply device, 11: Bridge type rectifier, 11a: Power switch, 12: Inverter circuit, 1
3: transformer, 14-16: reactor, 17-19:
Capacitor, 20: Capacitor, 21, 22: Reactor, 23: Capacitor, 24-27: FET, 28: Computer, 29: Base drive circuit, 30, 31:
Reactor, 32: condenser, 33: condenser, 3
4: resonance capacitor, 35: high-pressure discharge lamp, 36: detection circuit, 37: feedback circuit, 38: power supply circuit, 3
9: operation panel (display), 40: coil

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3K072 AA12 AA13 AA14 BA03 BB01 BC02 BC03 DD05 EB05 EB07 GA02 GB18 GC04 HA10 HB03 3K082 AA22 AA32 BA05 BA24 BA33 BD03 BD04 BD26 BD32 CA33 DA01

Claims (4)

[Claims] 1. A method for controlling a high pressure discharge lamp such as a high pressure mercury lamp, a metal halide lamp, a high pressure sodium lamp, etc., comprising a circuit for detecting a load voltage and a load current of the high pressure discharge lamp, wherein the high pressure discharge lamp is turned on. Immediately after performing the constant current control, when the load voltage of the high-pressure discharge lamp reaches a predetermined voltage or the load power of the high-pressure discharge lamp reaches a predetermined power value, switching to the constant power control. To control high pressure discharge lamps. 2. The method for controlling a high-pressure discharge lamp according to claim 1, wherein the high-pressure discharge lamp includes a PWM using an inverter.
A method for controlling a high pressure discharge lamp, characterized by using a controlled high frequency. 3. The method for controlling a high-pressure discharge lamp according to claim 1, wherein the constant-power control of the high-pressure discharge lamp is performed when the high-pressure discharge lamp reaches or exceeds a predetermined specified voltage. A method for controlling a high-pressure discharge lamp, comprising issuing an alarm signal indicating that the lamp life has expired. 4. The method of controlling a high-pressure discharge lamp according to claim 3, wherein the high-pressure discharge lamp is lit for a predetermined time after the high-pressure discharge lamp issues the alarm signal. A method for controlling a high-pressure discharge lamp, characterized by stopping energization.