JPH0729751Y2 - Inverter device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an inverter device which supplies alternating current power such as high frequency to a load by turning on / off a switching element, and more particularly to an inverter device in which a regenerative current flows to a direct current power source during operation.

[Background technology]

2. Description of the Related Art Conventionally, there are inverter devices that are supplied with power unilaterally from a DC power supply during operation and those that flow regenerative current to the DC power supply during operation.

First, FIG. 5 shows an example of an inverter device which has no regenerative current to the DC power supply. 51, 52 are switching elements (transistors), 53 is an oscillation transformer, primary winding 55, secondary winding 5
7. Has a feedback winding 56. Reference numeral 54 is a resonance capacitor, 58 is a load, 59, 60, 61 are resistors, 62 is a choke coil, 63 is a smoothing capacitor, 64 is a rectifying bridge, 65 is a commercial power supply, and 66 is a DC power supply.

FIG. 6 is a waveform diagram of each part in FIG. 5, where (A) is the voltage V ₅₁ across the switching element 51, (B) is the voltage V ₅₂ across the switching element 52, and (C) is the switching element. 51
Shows the current I ₅₁ flowing through the switching element 52, (D) shows the current I ₅₂ flowing through the switching element 52, and (E) shows the current I ₆₂ flowing through the choke coil 62.

In this inverter device, the voltages V ₅₁ and V ₅₂ of the switching elements ₅₁ and ₅₂ have a resonance type due to the oscillation transformer 53 and the resonance capacitor 54, and the currents I ₅₁ and I ₅₂ have a constant-current rectangular wave shape due to the choke coil 62. Oscillation transformer 53 to load 58
Power is supplied from the secondary winding 57 of the. Choke coil 62
There is no regenerative current to the DC power supply 66,
No high frequency current flows through 63.

Next, FIG. 7 shows an example of an inverter device having a regenerative current to a DC power supply. 71 is a switching element (transistor), 72 is a resonance capacitor, 73 is an oscillation transformer,
It has a primary winding 74, a secondary winding 75, and a feedback winding 76. Reference numeral 82 is a damper diode, 77 is a load, and 78 and 79 are resistors. 80 is a smoothing capacitor, 81 is a rectifying bridge, 83 is a commercial power supply,
These form the DC power supply 84.

FIG. 8 is a waveform diagram of each part of FIG. 7, (A) shows voltage V ₇₁ across switching element 71, (B) shows current I ₇₁ flowing through switching element 71 and current I ₈₂ flowing through damper diode _82. Are shown respectively.

In this inverter device, when the switching element 71 is turned on, a linearly increasing current I ₇₁ flows through the primary winding 74 of the oscillation transformer 73. When the current I ₇₁ reaches a certain value and the switching 71 is turned off, the current that has been flowing in the primary winding 74 tries to continue flowing, and the resonance capacitor 72
Start charging in the opposite direction. When the voltage of the resonance capacitor 72 becomes maximum, that is, when the voltage V ₇₁ of the switching element ₇₁ becomes maximum, the resonance capacitor 72 begins to discharge,
When the voltage V ₇₁ tries to fall below zero due to resonance, the DC power source is passed through the smoothing capacitor 80 and the damper diode 82.
Regenerative current I ₈₂ flows to 84. Electric power is supplied to the load 77 from the secondary winding 75.

Each of the above two types of inverter devices obtains the base signal of the switching elements 51, 52, 71 directly from the oscillation transformers 53, 73, and the oscillation frequency is 5
3, 73, choke coil 62, resonance capacitors 54, 72, etc. are determined by the characteristics peculiar to the circuit.

Now, in these inverter devices, various attempts have conventionally been made to take out a part of the resonance output, smooth it with a capacitor, and use this as a control power supply for the switching element. When the inverter device shown in the figure) is used, there is a problem that the regenerative current adversely affects the control power supply. Hereinafter, this point will be described in more detail.

In FIG. 9, 1 is a switching element, 2 is a choke coil, 3 is its main winding, 4 is a base drive power supply winding,
Reference numeral 5 is a resonance capacitor, 6 is a damper diode, 7 is a rectifier such as a diode for supplying a base driving power, 8 is a load, 9 is a driving circuit, 10 is a smoothing capacitor, 11 is a starting capacitor, and 12 is a base driving power supply. Smoothing capacitor, 13 is a rectifying bridge, 28 is a commercial power supply, and 29 is a DC power supply.

FIG. 10 shows the waveform of each part of the inverter device shown in FIG. 9, (A) shows the base signal V ₉ applied to the switching element 1, (B) shows the current I ₁ flowing through the switching element 1, (C) shows the voltage V ₁ across the switching element 1,
(D) shows the current I ₆ flowing through the damper diode 6,
(E) is the current I ₅ flowing through the resonance capacitor 5, (F) is the current I ₈ flowing through the load 8, (G) is the current I ₁₂ flowing through the smoothing capacitor 12, and (H) is both ends of the smoothing capacitor 12. The voltage V ₁₂ is (I) is the current I ₁₁ flowing in the starting capacitor _11.
Are shown respectively.

In this inverter device, when power is supplied from the commercial power supply 28, a voltage is applied to the series circuit of the smoothing capacitor 10, the starting capacitor 11 and the smoothing capacitor 12. At this time,
The voltage V ₁₂ of the smoothing capacitor 12 becomes a voltage determined by the capacitance ratio between the starting capacitor 11 and the smoothing capacitor 12, and is supplied to the drive circuit 9. As a result, the switching element 1
The base signal V ₉ is applied to. When the base signal V ₉ becomes high level and the switching element 1 is turned on, a current I ₁ that linearly increases flows through the main winding 3 of the choke coil 2. When the switching element 1 is turned off after a predetermined time due to the time constant of the drive circuit 9, the current flowing in the main winding 3 tries to continue flowing, and the current I ₅ is passed through the resonance capacitor 5 to charge the resonance capacitor 5. Go. Eventually, the current I ₅
Becomes zero and the voltage V _{1 of the} switching element 1 becomes maximum. From here, a regenerative current flows through the main winding 3, the load 8, the smoothing capacitor 10, the starting capacitor 11, and the smoothing capacitor 12. When the voltage V ₁ further decreases and becomes negative, the damper diode 6 is turned on and the regenerative current continues to flow as the current I ₆ .

By repeating this, a high frequency alternating current is supplied to the load 8. Further, the base drive power supply winding 4 of the choke coil 2 and the rectifier 7 supply the base drive power supply from the resonance circuit (the choke coil 2 and the resonance capacitor 5) after the start-up, and the energy supply from the start-up capacitor 11 does not occur. There is a characteristic that the oscillating operation is stopped when there is no load due to the removal of the load 8 or the like.

Here, the regenerative current to the power supply described above mainly flows through the smoothing capacitor 10, but part of it also flows through the starting capacitor 11 and the smoothing capacitor 12. As a result, the voltage V _{12 serving} as the base driving power supply rises, and also falls when the energy is released. Therefore, the voltage V ₁₂ is changed by the regenerative current. As a result, the oscillation frequency of the drive circuit 9 changes or the base voltage V ₉ changes, so the switching operation changes, and the base current and collector current (I ₁ ) are affected by the voltage V ₁₂ and the base modulation The applied current is supplied to the load 8. Therefore, the frequency of the harmonic component of the oscillation frequency may change, or the AM
Since the component when received and demodulated by radio etc. also increases,
It also has a drawback that it is likely to interfere with other devices due to noise.

[Purpose of device]

An object of the present invention is to suppress fluctuations in a power supply for a base drive circuit due to a regenerative current flowing through a starting capacitor and suppress noise in an inverter device having a regenerative current.

[Disclosure of device]

An inverter device of the present invention comprises a DC power supply having a first smoothing capacitor at an output terminal, a resonance circuit which is fed from the DC power supply and which supplies a regenerative current to the DC power supply,
A switching element that is inserted between the DC power supply and the resonance circuit to perform an on / off operation, a diode connected in antiparallel with the switching element, a drive circuit that periodically turns on / off the switching element, and the resonance circuit. A load to be fed, a rectifier that rectifies a part of the output of the resonance circuit, a second smoothing capacitor that smoothes the output of the rectifier and supplies it to the drive circuit as an operating power supply,
A starting capacitor connected between the DC power source and the second smoothing capacitor, and between the DC power source and the second smoothing capacitor with a direction of a starting current flowing through the starting capacitor at the time of starting as a forward direction. And a unidirectional switch element inserted in series with the starting capacitor.

According to the configuration of this invention, since the series circuit of the starting capacitor and the unidirectional switch element is connected between the DC power supply and the second smoothing capacitor, the discharge of the starting capacitor is blocked by the unidirectional switch element. Therefore, when the starting capacitor is charged to the maximum value, no more current will flow. As a result, the regenerative current flowing from the resonant circuit through the diode connected in anti-parallel to the switching element only passes through the first smoothing capacitor, and the regenerative current flowing into the second smoothing capacitor is blocked, and the second smoothing capacitor is blocked. The voltage fluctuation can be suppressed (reduction of input ripple), and the switching element is not modulated by the regenerative current, so that noise reduction can be achieved.

Embodiment A first embodiment of the present invention will be described with reference to FIGS. 1 and 2. This inverter device includes, as shown in FIG. 1, a DC power supply 29, a resonance circuit 30 which is fed from the DC power supply 29 and flows a regenerative current to the DC power supply 29, and the DC power supply 29 and the resonance circuit 30. A switching element 1 which is interposed between the switching element 1 and on / off operation, a drive circuit 9 which periodically turns on / off the switching element 1, a load 8 fed from the resonance circuit 30, and a part of an output of the resonance circuit 30. A rectifier 7 such as a diode for rectifying the rectifier, a smoothing capacitor 12 that smoothes the output of the rectifier 7 and supplies it to the drive circuit 9 as an operating power source, and a starter connected between the DC power source 29 and the smoothing capacitor 12. Capacitor 11
And a unidirectional switch such as a diode inserted in series with the starting capacitor 11 between the DC power supply 29 and the smoothing capacitor 12 with the direction of the starting current flowing through the starting capacitor 11 at the time of starting as the forward direction. And element 14. In this case, the resonance circuit 30 is composed of the choke coil 2 and the resonance capacitor 5. In addition, the DC power supply 29
Are obtained by full-wave rectifying the commercial power supply 28 with the rectifying bridge 13 and smoothing it with the smoothing capacitor 10.

This inverter device is different from the circuit of FIG. 9 in that a unidirectional switch element 14 such as a diode is inserted in series with the starting capacitor 11. In this case, the unidirectional switching element 14 is connected so that the direction of the current flowing through the starting capacitor 11 at the time of starting is the forward direction. Thus, when the unidirectional switch element 14 is provided,
The regenerative current is the starting capacitor 11 (and smoothing capacitor
It is possible to prevent the electric charge accumulated in the starting capacitor 11 from being discharged by the inverter operation by flowing through 12) and suppress the high frequency component appearing in the voltage V ₁₂ across the smoothing capacitor 12.

Hereinafter, a detailed description will be given with reference to FIG. Figure 2 shows the first
In the waveform diagram of each part of the figure, (A) shows the base voltage V ₉ and (B) shows
Is the current I ₁ of the switching element 1, (C) is the voltage V ₁ across the switching element 1, (D) is the current I ₆ of the damper diode 6, and (E) is the current I ₅ of the resonant capacitor 5,
(F) is the current I _{8 of the} load 8, (G) is the starting capacitor
11 is the current I ₁₁ and (H) is the voltage V across the smoothing capacitor 12.
₁₂ are shown respectively.

In this inverter device, when the commercial power supply 28 is turned on, the smoothing capacitor 10 is charged, and the unidirectional switching element 14
The start-up capacitor 11 and the smoothing capacitor 12 are charged through, the voltage V ₁₂ is applied to the drive circuit 9, and the base voltage V ₉ is applied to the switching element 1.

Thereafter, the switching operation is performed similarly to the circuit shown in FIG. 9, and after the start-up, the base drive power supply winding 4 to the rectifier 7 are connected.
Power is supplied to the load 8 to obtain the voltage V ₁₂ and the high frequency power is supplied to the load 8.

In this case, the regenerative current generated in the resonance circuit 30 to the DC power supply 29 is maintained at the maximum value because the discharge of the charge stored in the starting capacitor 11 is blocked by the unidirectional switch element 14 and the maximum value is maintained. Since it does not flow into the smoothing capacitor 10 but into the smoothing capacitor 10, the fluctuation of the voltage V ₁₂ due to the regenerative current of the resonance circuit 30 is suppressed as compared with the conventional example, and a low noise characteristic with a low base modulation rate is obtained.

Since other operations are the same as those of the circuit shown in FIG. 9,
The description is omitted.

A second embodiment of this invention will be described with reference to FIG.
In this inverter device, the load 8 in FIG. 1 is replaced with a discharge lamp 8 ', such as a fluorescent lamp, and a voltage responsive switch element 16 and a diode 17 are provided between the non-power supply side electrode terminals of both filaments of the discharge lamp 8'. A preheating / starting circuit consisting of a series circuit is connected.

The drive circuit 9 includes a timer integrated circuit (for example, NE555 manufactured by Signetic Co., Ltd.) 27, resistors 22 and 24, a diode 23, a variable resistor 25, a capacitor 26, a capacitor 19, and a resistor 2.
It is composed of 0 and 21, and operates as an astable multivibrator, and when the variable resistor 25 is adjusted, the oscillation frequency changes.

Further, the resistor 15 connected in parallel to the starting capacitor 11 has a high resistance value, and the voltage V ₁₂ is slightly lower than the operable voltage of the timer integrated circuit 27 when the inverter device stops oscillation when there is no load. This is for holding the value and improving the restartability.

The resistor 18 is for limiting the current flowing into the base drive circuit 9 through the rectifier 7.

Other configurations and operations are similar to those of the circuit of FIG.
Also in this case, the regenerative current flowing through the starting capacitor 11 can be blocked, the fluctuation of the voltage V ₁₂ due to the regenerative current can be suppressed, and the voltage can be maintained at a substantially constant voltage, and noise can be reduced.

A third embodiment of the present invention will be described with reference to FIG.
This inverter device shows a two-stone type embodiment.
In FIG. 4, 31 and 32 are switching elements (transistors), 33 and 34 are damper diodes, 35 and 36 are drive transformers, and 37 is a choke coil, and the auxiliary winding supplies power to the drive circuit 46. 38 is a load, 39 is a capacitor,
Reference numerals 40 and 41 are smoothing capacitors, 42 is a unidirectional switch element such as a diode, 43 is a starting capacitor, 44 is a smoothing capacitor, 45 is a rectifying bridge, and 47 is a commercial power supply.

In this inverter device, when the commercial power source 47 is turned on, the smoothing capacitor 44 is charged through the unidirectional switch element 42 and the starting capacitor 43, and the drive circuit 46 starts operating by the charging voltage of the smoothing capacitor 44 to perform switching. The elements 31 and 32 are alternately turned on and off to supply AC power to the load 38. When the power supply to the load 38 is started, the power supply from the auxiliary winding of the choke coil 37 to the drive circuit 46 is started, whereby the drive circuit 46 continues to operate. The drive circuit 46 has a built-in rectifier that rectifies the voltage of the auxiliary winding of the choke coil 37, and this rectifier is connected to the smoothing capacitor 44.

Also in this case, the unidirectional switch element 42 can prevent the regenerative current from flowing through the starting capacitor 43, and the noise reduction can be realized as in the above-described embodiment.

Incidentally, in each of the above embodiments, the unidirectional switch elements 14, 42.
Although a diode is used as the element, any element may be used as long as it allows a current to flow only in the direction of the starting current and cuts off the current in the opposite direction. The power supply circuit that supplies power to the drive circuits 9 and 46 after the start-up is not limited to the circuit configuration of the above-described embodiment, and various types can be considered.

[Effect of device]

According to the inverter device of the present invention, since the series circuit of the starting capacitor and the unidirectional switching element is connected between the DC power supply and the second smoothing capacitor, the discharging of the starting capacitor is performed by the unidirectional switching element. If blocked, and thus the starting capacitor is charged to its maximum value, no more current will flow. As a result, the regenerative current flowing from the resonant circuit through the diode connected in anti-parallel to the switching element only passes through the first smoothing capacitor, and the regenerative current flowing into the second smoothing capacitor is blocked,
The voltage fluctuation of the second smoothing capacitor can be suppressed (reduction of input ripple), and the switching element is not modulated by the regenerative current, so that noise reduction can be achieved.

[Another conventional example]

Note that, as shown in FIG. 11, it is a conventional practice to provide smoothing capacitors 91, 92 on each of the two loads 94, 95 and separate the smoothing capacitors 91, 92 with a diode 93. However, such a power supply circuit is always supplied with power from the rectifying bridge 96 side, and as shown in FIG. 1, the starting capacitor 11 obtains the starting energy only at the time of starting, and the starting capacitor 11 It is completely different from the present invention, which itself functions as a switch during startup and during normal operation.

Further, Japanese Patent Application Nos. 57-148287 and 57-148288 propose inverter devices for the purpose of dimming using a self-excited L push-pull circuit as shown in FIG. But,
This is, so to speak, a type having no regenerative current, which is different from the present invention, as shown in FIG. That is, this inverter device changes the dimming ratio by stopping the start at the valley of the pulsating flow and adjusting the time constants of the resistors 115 and 116 and the capacitor 117 appropriately, and the capacitor 117 when the voltage V ₁₁₉ is high. so that if charged, in the valley of the voltage V _119, in which the oscillation transistor 118 with decreasing voltage V ₁₁₉ is reverse biased stopping requires pulsating signal, the transistor 11
Although there is a capacitor 117 in the power supply path of the base of 8, the problem itself of the adverse effect of the power supply regenerative current described above is lacking.

Note that FIG. 13 is a waveform diagram of each part in FIG. 12, (A) shows the output voltage V ₁₁₉ of the rectifying bridge 119, and (B) shows the capacitor 117.
Shows the voltage across V _117, respectively, in FIG. 13 (B), V _TH is the threshold voltage of the transistor 118, the oscillating operation period transistor 118 of the voltage V ₁₁₇ V _117> V _TH is turned on In the period T of V ₁₁₇ <V _TH , the transistor 118 is turned off and the oscillation operation is stopped. Further, in FIG. 13 (A), V _X shows the waveform of the oscillation output.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing the configuration of the first embodiment of the present invention,
FIG. 2 is a waveform diagram of each part of FIG. 1, FIG. 3 is a circuit diagram showing a configuration of a second embodiment of the present invention, and FIG. 4 is a circuit diagram showing a configuration of a third embodiment of the present invention. FIG. 5 is a circuit diagram showing the configuration of a conventional inverter device, FIG. 6 is a waveform diagram of each part of FIG. 5, FIG. 7 is a circuit diagram showing the configuration of another conventional inverter device, and FIG. FIG. 7 is a waveform diagram of each part of FIG. 7, FIG. 9 is a circuit diagram showing the configuration of still another conventional inverter device, and FIG.
10 is a waveform diagram of each part of FIG. 9, FIG. 11 is a circuit diagram of a power supply device, FIG. 12 is a circuit diagram of an inverter device, and FIG. 13 is a waveform diagram of each part of FIG. 1 ... Switching element, 7 ... Rectifier, 8 ... Load, 9 ... Drive circuit, 11 ... Starting capacitor, 12 ... Smoothing capacitor,
14 ... Unidirectional switch element, 29 ... DC power supply, 30 ... Resonance circuit

Claims (1)

[Scope of utility model registration request] 1. A direct current power supply having a first smoothing capacitor at an output end, a resonance circuit which is fed from the direct current power supply and supplies a regenerative current to the direct current power supply, and is inserted between the direct current power supply and the resonance circuit. A switching element that is turned on and off, a diode that is connected in antiparallel with the switching element, a drive circuit that periodically turns the switching element on and off, a load that is fed from the resonance circuit, and an output of the resonance circuit. A rectifier that rectifies a part of
A second smoothing capacitor that smoothes the output of the rectifier and supplies it to the drive circuit as an operating power supply, a starting capacitor connected between the DC power supply and the second smoothing capacitor, and the starting capacitor at the time of startup. An inverter device comprising a unidirectional switch element that is inserted in series with the starting capacitor between the DC power source and the second smoothing capacitor with the direction of the starting current flowing in the forward direction as the forward direction.