JPH10199691A - Discharge lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device of a high power factor and high efficiency type. SOLUTION: A device is provided with a rectifier power source 10 to rectify a commercial power supply 11. It is provided with a circuit 20 including a pair of switching transistors 21, 22 connected in normal series to be mutually continuos, and flywheel diodes 23, 24 in inverse parallel connection to the transistors 21, 22, a first and a second inverter circuits 30, 40 to use the circuit 20 in common, and capacitors 31, 32, 41, 42 for respective arms. The first and second load circuit 39 and 40 are connected between the connection medium points 29 of a pair of transistor and respective arm capacitors. The power source 10 is connected to charge the capacitor 31 or 32 through at least one transistor 21 or 22 and through a first load circuit 39. Feedback prohibiting diodes 37, 38 are connected to a connection point of the capacitor 31 or 32 to the circuit 20 for preventing the capacitor 31 or 32 from being charged with electromagnetic energy immediately after turning off of the transistor 21 or 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a discharge lamp lighting device of an inverter operation type. In particular, the present invention relates to a discharge lamp lighting device of a type having both a chopper-operated first inverter circuit that also serves as a power supply function for a discharge lamp and a second inverter circuit dedicated to power supply to the discharge lamp.

[0002]

2. Description of the Related Art There is known a discharge lamp lighting device of a type in which an inverter circuit which operates by receiving the output thereof is disposed at a subsequent stage of a chopper operation type circuit and a discharge lamp is lit by an output of the inverter circuit.

[0003]

The conventional device is a chopper-operated type high power factor device. However, conversion is performed by the chopper operation type circuit, and conversion is performed by the inverter circuit. For this reason, there are many losses associated with each conversion, resulting in low efficiency. High power factor but low efficiency.
SUMMARY OF THE INVENTION It is an object of the present invention to provide a high power factor and high efficiency type discharge lamp lighting device which solves the difficulty of low efficiency.

[0004]

SUMMARY OF THE INVENTION The present invention comprises a rectified power supply for rectifying a commercial AC power supply voltage. A switching circuit includes a pair of switching transistors that are connected in series and that are alternately conductive, and includes a flywheel diode connected in anti-parallel with each of the transistors.
A first inverter circuit sharing the switching circuit;
A second inverter circuit; The first inverter circuit includes at least one first arm capacitor.
The second inverter circuit includes at least one second arm capacitor. A first load circuit serving as an AC load of the first inverter circuit is connected between a connection midpoint of the pair of transistors and one end of the first arm capacitor. A second load circuit serving as an AC load of the second inverter circuit is connected between the connection midpoint and the pair of second arm capacitors. The first load circuit is a discharge lamp.
It is a series circuit including a first inductor. The second load circuit is a series circuit including the discharge lamp and the second inductor. The rectified power supply is connected so as to charge the first arm capacitor via at least one of the switching transistors and the first load circuit. A feedback of a polarity at a connection point between the first arm capacitor and the switching circuit, which prevents electromagnetic energy of the first inductor from being supplied to the first arm capacitor and charged immediately after the switching transistor is turned off. Connect a blocking diode. The present invention is as described above. The basis is to supply a part of the output of the first inverter circuit that performs the chopper operation to the discharge lamp, reduce the output of the second inverter circuit by that amount, and thereby increase the efficiency.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. The illustrated device of the present invention is a commercial AC power supply 11.
A rectifying power supply 10 for rectifying a source voltage is provided. A flywheel diode 23.2 including a pair of switching transistors 21 and 22 connected in series and connected alternately, and connected in anti-parallel with each of the transistors 21 and 22.
4 is provided. A first inverter circuit 30 and a second inverter circuit 40 sharing the switching circuit 20 are provided. The first inverter circuit 30 includes at least one first arm capacitor 31 or 32
Is provided. The second inverter circuit 40 includes at least one second arm capacitor 41 or 42. A first load circuit 39 serving as an AC load of the first inverter circuit 30 is connected between a connection midpoint 29 between the pair of transistors 21 and 22 and one end of the first arm capacitor 31 or 32. Connection midpoint 29 and a pair of second arm capacitors 4
A second load circuit 49 serving as an AC load of the second inverter circuit 40 is connected between the first load circuit and the second load circuit 49. First load circuit 3
9 is a series circuit including the discharge lamp 91 and the first inductor 390. The second load circuit 49 is a series circuit including the discharge lamp 91 and the second inductor 490. The rectified power supply 10 is connected to charge the first arm capacitor 31 or 32 via at least one of the switching transistors 21 or 22 and the first load circuit 39. The electromagnetic energy of the first inductor 390 immediately after the switching transistor 21 or 22 is turned off is applied to the connection point between the first arm capacitor 31 or 32 and the switching circuit 20.
Or 32 is connected to a feedback blocking diode 37 or 38 having a polarity for blocking charging. FIG. 1 is supplemented. The commercial AC power supply 11 is, for example, 50H
z: Power supply of 100V. A rectifying power supply 10 includes a commercial AC power supply 11 and rectifying diodes 12 to 15 for full-wave rectification of the commercial AC power supply 11.
including. The illustration of the control circuit (base control circuit) for the switching transistors 21 and 22 has been omitted. One of the first arm capacitors 31 and 32, for example, 32 can be omitted. When the circuit 32 is omitted, the circuit is open. In that case, the feedback blocking diode 38 is unnecessary, and the circuit is short-circuited. The second arm capacitors 41 and 42 function as a sufficiently large smoothing capacitor. One of the capacitors 41 and 42 for the second arm can be omitted, and a single smoothing capacitor can be used. The discharge lamp 91 is a fluorescent lamp, and has a preheating condenser 93 in parallel with the fluorescent lamp. Discharge lamp 91
Requires a ballast inductor in series with it for stable lighting of the first inductor 3
90—second inductor 490. 92 is a discharge lamp 91
And an adjustment capacitor in series. When the first arm capacitor 31 is discharged via the switching transistor 21, the adjustment capacitor 92 is charged to the left polarity, and when the first arm capacitor 32 is discharged via the switching transistor 22, the adjustment is performed. Although the adjusting capacitor 92 is charged to the right polarity and promotes the AC operation, the insertion of the adjusting capacitor 92 is not essential. The discharge lamp 91 is connected to the first load circuit 39 of the first inverter circuit 30.
And a part of the second load circuit 49 of the second inverter circuit 40. Power is supplied to the discharge lamp 91 from both the first inverter circuit 30 and the second inverter circuit 40. For example, the rectified power supply 10 charges the first arm capacitor 32 through the switching transistor 21 and the first load circuit 39 when the switching transistor 21 is on. When the switching transistor 22 is on, the first arm capacitor 31 is charged. The operation of the circuit in FIG. 1 will be described. The rectified power supply 10 includes a first arm capacitor 31.
Charge 32. Also, the second arm capacitor 41.
42 is charged. In such a situation, the inverter operation proceeds. In the following, the description of the operation of the second inverter circuit 40 will be omitted, and the operation of the first inverter circuit 30 will be mainly described. Switching transistor 21
When turned on: The rectified power supply 10 serves as a power supply, and 10-37-21-91 (93) -92-390-.
Current flows through the closed circuit of 32-10. The first arm capacitor 31 is used as a power source, and the first arm capacitor 31-37-21-91 (9
3) A current flows through the closed circuit of -92-390-31. This is a power supply operation from the rectified power supply 10 to the discharge lamp 91. In addition, a power supply (energy storage) operation from the rectified power supply 10 to the first arm capacitor 32 and the first inductor 390 is performed. When the switching transistor 21 is turned off, the following occurs. First inductor 3
90 (where a leftward current is flowing) serves as a power supply, and the rectified power supply 10 serves as a power supply.
A current flows through the closed circuit of 41-42-24-91 (93) -92-390. This is a power supply operation from the first inductor 390 and the rectified power supply 10 to the discharge lamp 91, and a charging operation to the second arm capacitors 31 and 32. Assuming that there is no feedback blocking diode 38 and that it is short-circuited, the closed circuit breaks down and 390-32- (38) -2491 (93) -92 replaces it.
Current flows through the closed circuit at -390. In this case, the charging operation for the second arm capacitors 31 and 32 is not performed. In this case, the voltage of the second arm capacitors 31 and 32 decreases, and the operation mode is such that the rectified power supply 10 directly charges the second arm capacitors 31 and 32, and the power factor decreases. When the switching transistor 22 is turned on, an operation symmetrical to the above proceeds. The operation after the switching transistor 22 is turned off is also symmetric. Through these operations, power is supplied directly from the rectified power supply 10 or to the subsequent stage via the first inductor 390. Thereby, a part of the power consumed by the discharge lamp 91 is covered, and the capacitors 31 and 32 for the second arm are charged. Part of the power supplied from the rectified power supply 10 is a discharge lamp 9
1 and the remainder is the second arm capacitor 31.3
2 is stored. The power stored in the second arm capacitors 31 and 32 is also consumed by the discharge lamp 91 through the operation of the second inverter circuit 40. The power consumption of the discharge lamp 91 which is directly supplied from the rectified power supply 10 is supplied to the second inverter circuit 4.
This is power that does not pass through 0, and is efficient. The first inverter circuit 30 performs a chopper operation using the first inductor 390 as a chopper inductor to charge the capacitors 31 and 32 for the second arm, but supplies a part of the capacitors to the discharge lamp 91 for direct consumption. For this reason, efficiency is increased.

[0006]

According to the present invention, a part of the output of the first inverter circuit that performs chopper operation is supplied to the discharge lamp, and the output of the second inverter circuit is reduced by that amount. According to this, a high power factor and high efficiency type discharge lamp lighting device can be obtained.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a discharge lamp lighting device according to the present invention.

[Explanation of symbols]

10: rectified power supply, 11: commercial AC power, 20: switching circuit, 21: switching transistor, 22: switching transistor, 23: flywheel diode, 24: flywheel diode, 29:
Connection midpoint, 30: first inverter circuit, 31: capacitor for first arm, 32: capacitor for first arm, 3
7: feedback blocking diode, 38: feedback blocking diode, 39: first load circuit, 390: first inductor, 4
0: second inverter circuit, 41: capacitor for second arm, 42: capacitor for second arm, 49: second load circuit, 490: second inductor, 91: discharge lamp, 92: capacitor for adjustment, 93: preheating Capacitors

Claims (1)

[Claims] A rectifying power supply for rectifying a commercial AC power supply voltage, comprising a pair of switching transistors connected in series and alternately conducting, and a flywheel diode connected in antiparallel with each of the transistors. A first inverter circuit and a second inverter circuit that share the switching circuit, the first inverter circuit includes at least one first arm capacitor, and the second inverter circuit includes at least one first arm capacitor. A first load circuit serving as an AC load of the first inverter circuit between a connection midpoint of the pair of transistors and one end of the first arm capacitor; An AC load of the second inverter circuit between a connection midpoint and the pair of second arm capacitors. Two load circuits are connected, the first load circuit is a series circuit including a discharge lamp and a first inductor, the second load circuit is a series circuit including the discharge lamp and a second inductor, The first arm capacitor is connected via at least one of the switching transistors and the first load circuit so as to be charged, and a connection point between the first arm capacitor and the switching circuit is connected to the first arm capacitor. A discharge lamp lighting device, comprising a feedback blocking diode having a polarity for preventing the electromagnetic energy of the first inductor from being supplied to the first arm capacitor and charged therefrom immediately after the switching transistor is turned off.