JPS61189174A - Inverter - Google Patents

Abstract

PURPOSE:To reduce the power consumption of an inverter by providing a relay for shortcircuiting an impedance by an output produced after the time limit of a timer is finished and disconnecting a starting resistor. CONSTITUTION:An inverter is composed of a diode bridge 3 of a rectifier of an AC power source 1, a smoothing condenser 4, an inverter 23, a drive circuit 24, a timer 17 and a relay 6. The relay 6 has two contacts, the normal-open contact NO is connected across the condenser 4, and a normal-closed contact NC is connected between the resistor 8 and the bridge 3. Thus, even if a power source switch 2 is turned ON, the relay 6 is not operated, and its contact is shifted to NC side. Thus, a starting voltage is applied from the resistor 8 to switching transistors 11, 12, and after starting, a load 19 is driven by the secondary winding N2 of a transformer 14. The timer 17 is operated by the tertiary winding N3 voltage, and after the prescribed time, the contact of the relay 6 is switched to ON side to shortcircuit the resistor 5, thereby disconnecting the resistor 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field 1] The present invention relates to an inverter device that rectifies and smoothes an AC power supply and converts a DC voltage created by the rectification and smoothing into a high-frequency voltage.

[Background Art] Conventionally, there is an inverter device of this type as shown in FIG. 7, which inputs an AC power source 1 through a power switch 2 to a rectifier circuit 3 and a smoothing capacitor 4, and also performs rectification and smoothing. The inverter circuit 23 converts the DC voltage into a high-frequency voltage to drive a load 19 such as a discharge lamp. Here, the inverter circuit 23 is configured as follows. Rectifier circuit 3, smoothing capacitor 4
The DC voltage created by rectification and smoothing is input to the intermediate tap of the primary winding N of the oscillation transformer 14 via the current-limiting choke coil 7, and is input to the intermediate tap of the primary winding N of the oscillation transformer 14.
12 is alternately switched to induce a high frequency voltage in the secondary winding N2 of the oscillation transformer 14, and the load 19 is driven by this induced voltage.

Here, switching of the switching transistor 11.12 is performed by applying positive feedback to the base of the switching transistor 11.12 using the feedback winding Nb of the oscillation transformer 14.
A starting resistor 8 is connected to the base of 2. Further, a resistor 5 is connected in series with the smoothing capacitor 4, and this resistor 5 reduces the rush current flowing into the power supply circuit consisting of the rectifier circuit 3 and the smoothing capacitor 4.

However, this resistor 5 is not needed once the power supply circuit has stabilized and causes a large power loss. Therefore, when the power supply circuit is stable, the relay 6, transistor 18, and timer are removed so that the resistor 5 is removed from the circuit. A circuit 17, a tertiary winding N3 of the transformer 14, a diode 15, and a capacitor 16 are provided. As described above, when the DC power is applied to the inverter circuit 23 and the inverter circuit 23 starts operating, an induced voltage is also generated in the tertiary winding N3 of the transformer 14. This induced voltage is rectified and smoothed by a diode 15 and a capacitor 16, and a timer circuit 17 operates with this rectified and smoothed DC voltage.

Then, for example, after 100m5ec has elapsed, the timer circuit 1
7 produces an output and drives transistor 18 to relay 6
make it work. When relay 6 operates in this way,
Since the normally open contacts 6a of the relay 6 are connected to both ends of the resistor 5, the resistor 5 is short-circuited.

In this way, when the inverter circuit 23 is stable, the resistance 5
This reduces power loss due to

Here, the starting resistor 8 is essential for the switching transistors 1.1.12 of the inverter circuit 23 to start switching, and the resistance value is determined by the amplification factor of the switching transistor 11.12, the impedance of the load 19, etc. Appropriately selected by. For example, the amplification factor of switching transistors 11 and 12 is small.
In cases such as when the ambient temperature is low or the load impedance is small (heavy load), the inverter circuit 23 may not be able to shift to a steady state unless the value of the starting resistor 8 is sufficiently small, or the inverter circuit 23 may be in a long This took a long time and sometimes caused abnormal oscillation. Therefore, if the resistance value of the starting resistor 8 is set low in consideration of the above, the power consumption will increase in inverse proportion to the resistance value, so the resistor 8 will become large, which is disadvantageous in terms of mounting, and at the same time This is the main cause of reducing circuit efficiency during operation.

Moreover, if the voltage rectified and smoothed by the diode 15 and the capacitor 16 is applied to the switching transistor 11.12 by the bias resistor 9.10 as in the circuit described above, then during the steady operation of the inverter circuit 23, the starting resistor 8 is completely unnecessary, and all the power consumed by the starting resistor 8 can be considered as power loss. Here, a diode 15, a capacitor 16, and a bias resistor 9.10 form a drive circuit. For this reason, conventionally, as shown in FIG. 8, a positive characteristic thermistor Rth is used as the starting resistor 8, and after the switching transistors 11 and 12 are started, the positive characteristic thermistor Rth increases its resistance value due to self-heating. , one that reduces power consumption in the starting resistor 8, or a resistor R as the starting resistor 8 as shown in FIG.
1. Using R2, connect a capacitor CI across the resistor R2, and at startup, the resistor R is charged by charging the capacitor C1.
2 becomes almost short-circuited, the starting resistance value becomes small, and in the steady state of the inverter circuit 23, the capacitor C1 is sufficiently charged and the resistance value 8 increases.
In some cases, the resistor R1 and the resistor R2 are connected in series, increasing the starting resistance value and reducing power consumption in the starting resistor. However, in the former case, when restarting an inverter device that has been operating for a long time, the resistance value of the positive temperature coefficient thermistor Rth does not decrease in a short period of time due to the thermal inertia of the positive temperature coefficient thermistor Rth, which has the disadvantage of restarting the inverter device. In the latter case, in order to obtain sufficient starting characteristics, it is necessary to increase the capacitance of the capacitor C1, and although it is expensive, there is still a loss due to the starting resistor 8, and there are problems with restarting. had.

[Objective of the Invention 1 The present invention has been made in view of the above-mentioned points, and its object is to provide an inverter device that can reduce power consumption due to starting resistance.

[Disclosure of the Invention 1 (Embodiment 1) Fig. 1 shows an embodiment of the present invention, which, like the conventional example, includes an AC power supply 1, a diode bridge 3 as a rectifier circuit, a smoothing capacitor 4, and an inverter circuit. 23, a drive circuit 24, a timer circuit 17, and a relay 6. The relay 6 of this embodiment has two contacts; the normally closed contact NO of the relay 6 is connected to both ends of the smoothing capacitor 4, and the normally closed contact NC is connected between the starting resistor 8 and the diode bridge 3. It is.

The operation of this embodiment described above is as follows. First, when the power switch 2 is turned on and the AC power supply 1 is turned on, a DC voltage is applied to the intermediate tap of the primary winding N of the transformer 14 of the inverter circuit 23.

At this time, since voltage has not yet been generated in the drive circuit 24, the relay 6 is also not operating, and the contact of the leaf relay 6 has been switched to the normally closed contact NC side.

Therefore, the switching transistor 1 is lower than the starting resistor 8.
A starting voltage is applied to 1.12, and either switching transistor 11 or 12 is turned on due to variations in base-emitter resistance, etc. Then, transformer 1
Volume 4 #! A current flows through N1, a voltage is induced in the feedback winding Nb connected to the bases of the switching transistors 11 and 12, and this voltage applies positive feedback to the bases of the switching transistors 11 and 12. .12 alternately switching to transformer 14. A high frequency voltage is induced in the secondary winding N2, and this voltage drives the load 19 connected to the secondary winding N2. In this way, when a voltage is induced in the secondary winding N2 of the transformer 14, a voltage is also induced in the tertiary winding N3. Therefore, this voltage is rectified and smoothed by a diode 15 and a capacitor 16, and the timer circuit 17 is operated with this rectified and smoothed DC voltage, and the output of the timer circuit 17 that occurs after the time-limited operation turns on the transistor 18 to trigger the relay. 6 and relay 6
Switch the contact to the normally closed contact No side. Then, resistance 5
are short-circuited and the starting resistor 8 is disconnected. After the starting resistor 8 is disconnected in this way, the bias resistor 9.1
At 0, a voltage rectified and smoothed by the drive circuit 24 is applied to the switching transistors 11 and 12. Therefore, when the AC power supply 1 is turned on, the inrush current can be suppressed by the resistor 5, and the switching transistor 1 can be suppressed by the starting resistor 8.
1.12 can be started, and when the inverter circuit 23 operates and shifts to a steady state, the contact operation of the relay 6 short-circuits the resistor 5 and disconnects the starting resistor 8.
This eliminates the power consumption of the resistor 5 and the starting resistor 8, thereby reducing the power consumption of the inverter device.

(Embodiment 2) FIG. 2 is a diagram showing another embodiment of the present invention. In this embodiment, a resistor 5 for suppressing rush current of the power supply circuit is inserted into the output of the diode bridge 3, and an inverter is connected to the inverter. circuit 2
A voltage is applied to 3 via this resistor 5. The other aspects are the same as those in the first embodiment, so the explanation will be omitted.

(Third Embodiment) FIG. 3 is a diagram showing still another embodiment of the present invention, and like the second embodiment, the insertion position of the resistor 5 for suppressing rush current is different from the first and second embodiments. In this embodiment, it is inserted between the power switch 2 and the diode bridge 3.

(Embodiment 4) FIG. 4 is a diagram showing still another embodiment of the present invention, in which a starting resistor 8 serves also as the inrush current suppressing resistor 5 of the first embodiment. A feature of this embodiment is that the normally open contact No. of the relay 6 is connected in series with the smoothing capacitor 4 to both ends of the output of the diode bridge 3.

The operation of this embodiment having the above configuration is as follows.

When the power switch 2 is turned on and the AC power supply 1 is turned on,
As explained in the first embodiment, the contact of the relay 6 is on the normally closed contact NC side, and the voltage rectified by the diode bridge 3 is sent to the smoothing capacitor 4, the starting resistor 8, and the switching transistor 11 or 12. applied. For this reason, the switching transistor 11 with the starting resistor 8
．． The input resistance value of No. 12 when turned off suppresses inrush current. After that, the relay 6 is driven by the same operation as in Example 1, the contact of the relay 6 is switched to the normally open contact No side, the smoothing capacitor 4 is connected between both ends of the output of the diode bridge 3, and the start-up is performed. Disconnect resistor 8. therefore,
As in the first embodiment, the power consumption of the inverter device can be reduced, and in this embodiment, the starting resistor 8 also serves as the resistor 5, thereby reducing the number of parts.

(Embodiment 5) FIG. 5 is a diagram showing still another embodiment of the present invention. In the above-mentioned embodiments 1 to 4, the relay 6 had two contacts, but In this embodiment, the contact of the relay 6 is made into one contact. For this reason,
In the fourth embodiment, the normally closed contact NC was connected to the starting resistor 8, but in this embodiment, the starting resistor 8 is connected from the common terminal C through the diode 21.

The operation of this embodiment having the above configuration is as follows.

When the AC power supply 1 is turned on, the voltage rectified by the diode bridge 3 is transferred to the smoothing capacitor 4 and the diode 21.
, a switching transistor 11 . through a starting resistor 8 .
12. Therefore, the rush current is suppressed by the starting resistor 8 in the same manner as in the fourth embodiment. Next, when the inverter operates and the relay 6 is driven, the contacts of the relay 6 are closed and the smoothing capacitor 4 is connected to the diode bridge 3.
connected to the output of At this time, the diode 21 is reverse biased and turned off, so that the starting resistor 8 is disconnected.

(Embodiment 6) FIG. 6 is a diagram showing still another embodiment of the present invention. In this embodiment, the starting resistor 8 of Embodiment 5 is replaced with a switching transistor when the inverter circuit 23 is operating in a steady state. 1. The resistors 9 and 10 that bias i and 12 also serve as the starting resistor 8. Therefore, a reverse current blocking diode 22 is inserted so that the voltage when the AC power supply 1 is turned on does not affect the timer circuit or the like. Since the other circuit operations are the same as those described above, the explanation will be omitted.

Although the timer circuit 17 is used in the first to sixth embodiments described above, if the delay time of the voltage induced in the secondary winding #lN3 is longer than the predetermined time-limited operation time of the timer circuit 17, The timer circuit 17 can be omitted. Furthermore, in the first to fifth embodiments, a positive temperature coefficient thermistor, a temperature fuse, or the like may be used as the starting resistor 8 to further reduce the power consumption at the time of starting the inverter circuit 23.

[Effects of the Invention] As described above, the present invention is provided with a relay that performs a contact operation to short-circuit the impedance and disconnect the starting resistance at the output generated after the timed operation of the timer circuit ends. When the power is turned on, the inrush current can be suppressed by inserting an impedance in series with the rectifier circuit or smoothing capacitor, and during normal operation of the inverter circuit, the above impedance can be shorted and the starting resistor can be disconnected. By doing so, it is possible to reduce the power consumption of the inverter device.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing one embodiment of the present invention, Fig. 2 is a circuit diagram showing another embodiment of the invention, and Figs.
FIG. 7 is a circuit configuration diagram showing still another embodiment of the present invention, FIG. 7 is a circuit configuration diagram showing a conventional example, and FIGS. 8 and 9 are partial circuit configuration diagrams of other conventional examples. 1 is an AC power supply, 3 is a diode bridge, 4 is a smoothing capacitor, 5 is a resistor, 6 is a relay, 8 is a starting resistor, 14
is an oscillation transformer, 23 is an inverter circuit, 24 is a drive circuit, N5, N2, and N3 are windings, and NC5No is a contact.

Claims (6)

[Claims] (1) A rectifier circuit that rectifies an AC power source, a smoothing capacitor that smoothes the output of the rectifier circuit, an impedance that is inserted in series with the rectifier circuit or the smoothing capacitor and suppresses inrush current, and a rectifier circuit that suppresses inrush current. An inverter circuit that converts a DC voltage output into a high-frequency voltage by alternately switching switching transistors and is equipped with a starting resistor that starts the switching transistor, and an inverter circuit that rectifies and smoothes a part of the output voltage of the inverter circuit. A drive circuit that drives the switching transistor of the above with a bias resistor, a timer circuit that starts a timed operation from the start of the operation of the drive circuit, and an output generated after the timed operation of the timer circuit shorts the impedance. An inverter device comprising a relay that performs contact operation to disconnect the starting resistor. (2) The impedance that suppresses the rush current mentioned above is also used as a starting resistor, and the smoothing capacitor that is connected to both ends of the rectifier circuit output during steady operation of the inverter circuit is connected in series to the starting resistor when the AC power is turned on. The inverter device according to claim 1, further comprising a contact-operated relay. (3) A diode connected between the starting resistor and the smoothing capacitor performs the contact switching operation of the relay that connects the smoothing capacitor in series with the starting resistor when the AC power is turned on. The inverter device described. (4) The inverter device according to claim 3, wherein the starting resistor is also used as a bias resistor of the drive circuit. (5) The inverter device according to any one of claims 1 to 4, wherein the relay is driven directly using the output voltage of the drive circuit without using the timer circuit. (6) Claim 1, wherein an element whose resistance value increases with time, such as a positive temperature coefficient thermistor, is used as the starting resistor.
The inverter device according to items 1 to 3.