JPH0787746A - Inverter apparatus - Google Patents

Abstract

PURPOSE:To provide an inverter apparatus which is small and low-cost and has a high efficiency in the inverter apparatus which is used for control of an electric motor, for a decentralized-powersupply-line linkage system or the like. CONSTITUTION:A resonant coil 9 is connected in series with a DC power supply 10, and it is connected in parallel with a resonant capacitor 14. A switching element 11 is connected to a detection means 15 and oscillation drive means 20, a DC removal means 18 is connected to the detection means 15, and a waveform command means 21 is connected to the oscillation drive means 20. The detection means 15 is constituted of a rectifier diode and a smoothing capacitor 17, and the DC removal means 18 is composed of a coupling capacitor 19. The oscillation drive means 20 periodically sets the switching element 11 to continuity or cuts it off, and the waveform command means 21 command the continuity time of the switching element 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter device used in, for example, motor control and distributed power system cooperation system.

[0002]

2. Description of the Related Art In recent years, there has been a demand for miniaturization, cost reduction and high efficiency of this type of inverter device.

Below, a conventional inverter device is shown in FIG.
It will be described based on. In FIG. 8, E is a DC power source, 1,
Switching elements 2, 3 and 4 constitute so-called full bridge inverters. A control circuit 5 periodically controls conduction / interruption of the switching elements 1, 2, 3, and 4. Reference numeral 6 is a transformer connected to the outputs Va and Vb of the full bridge inverter. A low-pass filter composed of a choke coil 7 and a capacitor 8 is connected to the output of the transformer 6 and outputs both ends of the capacitor 8. And FIG. 9 is an operation waveform diagram for explaining the operation of the conventional example of FIG. In FIG. 9, VO is the input voltage of the transformer 6,
VAC is the output voltage. The control circuit 5 controls conduction / interruption of the switching elements 1, 2, 3, 4 so that the input voltage Vo of the transformer 6, that is, Va-Vb, becomes a pseudo sine wave whose pulse width is modulated as shown in FIG. To do. The pseudo sine wave Vo is stepped up or down by the transformer 6 according to the purpose, and a low frequency AC voltage as shown in FIG. 9 VAC is obtained by the low pass filter composed of the choke coil 7 and the capacitor 8.

[0004]

However, in the above-mentioned conventional configuration, since four switching elements are required, the apparatus becomes expensive and, as can be seen from VO in FIG. 9, the switching elements 1, 2, 3, In No. 4, a so-called hard switching operation is performed and the voltage thereof changes abruptly, so that there is a problem that switching loss becomes large and efficiency becomes low, and a cooling mechanism of the apparatus becomes large.

The present invention solves the above-mentioned conventional problems, and an object thereof is to provide a small-sized, inexpensive and highly efficient inverter device.

[0006]

To achieve the above object, the present invention provides, as a first means, a resonance coil and a switching element connected in series to a DC power source, and a resonance coil or a switching element connected in parallel. Resonant capacitor, detecting means connected to the resonant coil or the switching element, direct current removing means connected to the detecting means, oscillation / driving means for periodically connecting / disconnecting the switching element, and the oscillation / driving It has a waveform command means connected to the means for instructing the conduction time of the switching element, and controlling the conduction time so that the output voltage of the DC removing means has an AC waveform.

The present invention also provides, as a second means, a resonance coil and a switching element connected in series to a DC power supply,
A resonance capacitor connected in parallel to the resonance coil or the switching element; a transformer connected to the resonance coil or the switching element; a detector connected to the transformer; and a DC remover connected to the detector. An oscillation / driving means for periodically connecting / disconnecting the switching element, and a waveform command means connected to the oscillation / driving means for instructing a conduction time of the switching element, and an output voltage of the direct current removing means is an alternating current. The conduction time is controlled so as to form a waveform.

Further, the present invention provides, as a third means, a high frequency transformer and a switching element connected in series to a DC power supply, a resonance capacitor connected in parallel to the high frequency transformer or the switching element, and a secondary of the high frequency transformer. The detecting means connected to the side, the direct current removing means connected to the detecting means, the oscillation / driving means for periodically connecting / disconnecting the switching element, and the conduction time of the switching element connected to the oscillation / driving means. It has a waveform commanding means for commanding, and controls the conduction time so that the output voltage of the DC removing means has an AC waveform.

The present invention, as a fourth means, is an error voltage detecting means for detecting an error between the output voltage and an intended AC waveform in the first means, the second means and the third means. It is connected to a waveform command means to control the conduction time so that the output voltage approaches an intended AC waveform.

[0010]

According to the above-mentioned first means, the desired AC waveform can be obtained with a simple structure composed of only one switching element, and the switching element performs so-called soft switching operation, so that the switching loss is reduced. The efficiency is high and the cooling mechanism of the device can be small. Therefore, it is possible to provide a compact, inexpensive, and highly efficient inverter device.

According to the second means, in addition to the effect of the first means, an extremely high voltage or a low voltage can be easily obtained by the transformer, and since it is inserted in the high frequency portion, it is compatible with high frequencies. A small transformer can be used. Therefore, it is possible to provide a compact, inexpensive, and highly efficient inverter device for a wide range of output voltages.
Moreover, since the DC power supply and the output can be easily insulated even when the step-up / down is not performed, the inverter device can be easily used.

According to the third means, the high-frequency transformer also serves as the resonance coil as compared with the second means, so that the number of parts can be reduced. Therefore, it is possible to provide a more compact, inexpensive and highly efficient inverter device for a wide range of output voltages. Moreover, since the DC power supply and the output can be easily insulated even when the step-up / down is not performed, the inverter device can be easily used.

According to the fourth means, since the output voltage is feedback-controlled, the target AC waveform can be accurately obtained regardless of changes in circuit constants due to temperature, changes over time, and changes in the load connected to the output. You can Therefore, it is possible to provide a compact, inexpensive, highly efficient inverter device with stable output and high accuracy.

[0014]

(Embodiment 1) A first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a circuit of an inverter device according to the present embodiment. Reference numeral 9 is a resonance coil connected in series to a DC power source 10 of voltage E, 11 is a switching element, which is composed of a bipolar transistor 12 and an antiparallel diode 13. To do. 1
Reference numeral 4 is a resonance capacitor connected in parallel to the resonance coil 9, and reference numeral 15 is a detection means connected to the collector-emitter of the switching element 11, which is composed of a rectifying diode 16 and a smoothing capacitor 17. Reference numeral 18 is a direct current removing means connected to the detecting means 15 and comprises a coupling capacitor 19. Reference numeral 20 is an oscillating / driving means for periodically connecting / disconnecting the switching element 11, and 21 is a waveform commanding means connected to the oscillating / driving means 20 for instructing a conductive time of the switching element 11. FIG. 2 is an operation waveform diagram for explaining the operation of the inverter device of this embodiment. Figure 2 (a)
Is a switching element 11 operating at several tens of kHz in FIG.
Shows the collector-emitter voltage V0 of the. When the switching element 11 is turned on at time t0, a current flows through the resonance coil 9 and increases. When the switching element 11 is cut off at the time t1 after the conduction time TON, the current of the resonance coil 9 flows into the resonance capacitor 14 and enters the LC resonance state. Voltage VO
Goes up and down in an arc of resonance, reaches zero again at time t2, and the anti-parallel diode 13 naturally conducts at time t0.
The state returns to and the oscillation continues. Switching element 11
2 performs a so-called soft switching operation in which the voltage at the time of interruption / conduction rises gently due to resonance and naturally reaches zero as shown by VO in Fig. 2 (a), so the voltage / current duty at the time of state transition is small and there is no loss. small. The peak voltage VOP of the switching element 11 increases as the conduction time TON increases and decreases as the conduction time TON decreases. Therefore, the peak voltage VOP can be controlled by the conduction time TON. 2B, TON is a conduction time of the switching element 11 which is periodically controlled by the waveform command means 21 at several tens to hundreds of Hz, and VO is a voltage VO of the switching element 11 which appears in response to the change of the conduction time. Shows the waveform of. TON is applied so that the VO peak value normal line becomes a sine wave as shown in FIG. Since the average value of the voltage of the resonance coil 9 becomes zero, the average value of VO is 10
Equal to the voltage E of. Since the detection means 15 in FIG. 1 detects VO by the normal line detection, its output V1 becomes a DC superimposed sine wave as shown in FIG. 2 (b). When the DC component of V1 is removed by the DC removing means 18, an AC sine wave as shown in FIG. 2B is obtained as the output VAC.

The inverter device of the present embodiment having the above-described structure has a simple structure including only one switching element and can obtain a desired AC waveform, and the switching element performs so-called soft switching operation. Therefore, the switching loss is reduced, the efficiency is high, and the cooling mechanism of the device is small. Therefore, it is possible to obtain a target AC waveform with a compact and inexpensive structure and high efficiency.

Although the detecting means is connected to the switching element in this embodiment, the same effect can be obtained by connecting the detecting means to the resonance coil.

(Embodiment 2) Next, a second embodiment of the present invention will be described with reference to the drawings.

FIG. 3 shows a circuit of the inverter device of the present embodiment. Reference numeral 22 is a resonance coil connected in series to a DC power source 23 of voltage E, 24 is a switching element, which is composed of a bipolar transistor 25 and an antiparallel diode 26. To do.
Reference numeral 27 is a resonance capacitor connected in parallel to the resonance coil 22, 28 is a transformation means connected to the collector-emitter of the switching element 24, and a high frequency transformer 29 and a capacitor 30 excluding a direct current component in order to prevent bias magnetization of the high frequency transformer 29. Become. Reference numeral 31 is a detecting means connected to the transforming means 28 and is composed of a rectifying diode 32, a choke coil 33 and a smoothing capacitor 34. Here choke coil 3
Although the device operates without any trouble even without 3, there is a smoothing capacitor 34 when the choke coil 33 is connected as in the embodiment.
Since it is possible to suppress the inrush current to the smoothing capacitor 34, it is possible to reduce the heat generation of the smoothing capacitor 34. Reference numeral 35 is a direct current removing means connected to the detecting means 31 and comprises a coupling capacitor 36. Reference numeral 63 is an oscillating / driving means for periodically connecting / disconnecting the switching element 24, and 64 is a waveform commanding means for connecting to the oscillating / driving means 35 and for instructing a conductive time of the switching element 24. In this embodiment, the voltage E of the DC power supply 23 is set to about 100 V, and the output voltage VAC
As an example, an extremely high voltage of about 5 kV is obtained.
The collector-emitter voltage VO of the switching element 24 operating at several tens of kHz is the same as that shown in FIG. 2A, and the switching element 24 is a so-called soft switching in which the voltage at the time of interruption / conduction gently rises due to resonance and naturally reaches zero. Since it operates, the voltage / current duty at the time of state selection is small and the loss is small. Further, the peak voltage of the switching element 24 becomes higher as the conduction time TON becomes longer and becomes lower as the conduction time TON becomes shorter, so that it can be controlled by the conduction time TON. FIG. 4 is an operation waveform diagram for explaining the operation of the inverter device of this embodiment. TON represents the conduction time of the switching element 24 which is periodically controlled by the waveform command means 64 at several tens to several hundreds Hz, and VO represents the waveform of the voltage VO of the switching element 24 which appears in response to the change in the conduction time. TON is given so that the VO peak value normal line becomes a sine wave as shown in FIG. Since the average value of the voltage of the resonance coil 22 becomes zero, the average value of VO is equal to the voltage E of the DC power supply 23. The maximum value of VO is set to about 800V because the withstand voltage of a switching element which can be obtained at a low cost is up to about 1000V.
A high pressure with an average value of zero can be obtained. Since the detection means 31 substantially detects the normal-tangential line of VO, its output V2 becomes a sine wave as shown in FIG. 4, but the negative portion of V1 disappears due to the detection, so that it has a DC superimposed waveform. When the DC component of V2 is removed by the DC removing means 35, an AC sine wave as shown in FIG. 4 is obtained as the output VAC.

In addition to the effects of the first embodiment, the inverter device of the present embodiment configured as described above can easily obtain extremely high voltage and low voltage by the transformer, and further, in the high frequency part. Since it is inserted, it is possible to obtain the effect that a small transformer compatible with high frequencies can be used. . Therefore, it is possible to obtain a desired AC waveform for a wide range of output voltages with a small and inexpensive structure and high efficiency. Even if the buck-boost is not performed, the DC power supply 2
Since the insulation of 3 and the output VAC can be easily obtained, it is easy to use the inverter device.

In the present embodiment, the detecting means is connected to the switching element, but the same effect can be obtained by connecting it to the resonance coil. In this case, since the voltage of the resonance coil does not include the direct current component, the capacitor 30 is not necessary. Good.

(Embodiment 3) Next, a third embodiment of the present invention will be described with reference to the drawings.

FIG. 5 shows a circuit of the inverter device of the present embodiment. 37 is a high frequency transformer in which the primary side is connected in series to a DC power source 47, 38 is a switching element and is composed of a bipolar transistor 39 and an antiparallel diode 40. To do. 41 is a resonance capacitor connected in parallel to the primary side of the high frequency transformer 37, and 42 is the high frequency transformer 37.
The rectifying diode 43 and the smoothing capacitor 44 are the detecting means connected to the secondary side of the. 45 is the detection means 42
DC coupling means connected to the coupling capacitor 46
Consists of Reference numeral 47 is an oscillating / driving means for periodically connecting / disconnecting the switching element 38, and 48 is a waveform commanding means connected to the oscillating / driving means 47 for instructing a conductive time of the switching element 38. In this embodiment, the voltage E of the DC power supply 47 is set to about 100 V, and an extremely high voltage of about 5 kV is obtained as the output voltage VAC. Number 10
The collector-emitter voltage VO of the switching element 38 operating at kHz is the same as that in FIG. 2A, and the switching element 38 has a so-called soft switching operation in which the voltage during cutoff / conduction gently rises due to resonance and naturally reaches zero. Therefore, the voltage / current duty at the time of state selection is small and the loss is small. Further, since the peak voltage of the switching element 38 increases as the conduction time TON increases and decreases as the conduction time TON decreases, the primary side voltage VL of the high frequency transformer 37 can be controlled by the conduction time TON. FIG. 5 is an operation waveform diagram for explaining the operation of the inverter device of this embodiment. T
ON is a conduction time of the switching element 38 which is periodically controlled by the waveform command means 48 at several tens to several hundreds Hz,
VO represents the waveform of the primary side voltage VL of the high frequency transformer 37 which appears in response to the change of the conduction time. TON is given so that the VL peak value normal line becomes a sine wave as shown in FIG. The maximum breakdown voltage of switching elements that can be obtained at low cost is 1
The maximum value of VL is about 700V because it is up to about 000V, but VL is set to 5k by the high frequency transformer 37 here.
When the voltage is increased to about V, a high voltage is obtained as the secondary side output voltage V1 of the high frequency transformer 37 as shown in FIG. Since the detecting means 43 detects the Vo by the normal line, its output V2 is shown in FIG.
Although it becomes a sine wave as shown by the above, the negative part of V1 disappears by the detection, so that it becomes a DC superimposed waveform. When the DC component of V2 is removed by the DC removing means 46, an AC sine wave as shown in FIG. 6 is obtained as the output VAC.

In the inverter device of the present embodiment constructed as described above, since the high frequency transformer 37 also serves as a resonance coil, in addition to the effect of the second embodiment, the number of parts can be reduced. Is obtained. Therefore, it is possible to provide a more compact, inexpensive and highly efficient inverter device for a wide range of output voltages. Moreover, since the DC power supply and the output can be easily insulated even when the step-up / down is not performed, the inverter device can be easily used.

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described with reference to the drawings.

FIG. 7 shows the circuit of the inverter device of this embodiment. The output voltage VAC and the desired AC waveform are supplied to the waveform command means 64 of the inverter device of the second embodiment of the present invention shown in FIG. Error voltage detecting means 65 for detecting an error of Vs
Is connected. The error voltage detecting means 65 comprises an AC waveform generating means 66 for generating a target AC waveform Vs and an error amplifier 67. Reference numeral 48 is a resonance coil connected in series to a DC power source 49 of voltage E, and reference numeral 50 is a switching element which is composed of a bipolar transistor 51 and an anti-parallel diode 52. Reference numeral 53 is a resonance capacitor connected in parallel with the resonance coil 48, and 54 is a transformation means connected to the collector-emitter of the switching element 50, which is a high frequency transformer 55.
And a capacitor 56 for removing the direct current component in order to prevent the high-frequency transformer 55 from being demagnetized. Reference numeral 57 is a detection means connected to the transformation means 54 and is a rectifying diode 58 and a choke coil 5.
9 and the smoothing capacitor 60. Reference numeral 61 is a direct current removing means connected to the detecting means 57, and comprises a coupling capacitor 62. Reference numeral 63 is an oscillating / driving means for periodically connecting / disconnecting the switching element 51. Similar to FIG. 3, an AC sine wave is obtained as the output VAC, but in the case of FIG. 5, the conduction time TON of the switching element 51 is compared so that the output voltage VAC is compared with the target AC waveform VS to reduce the error. To control.

Since the inverter device of the present embodiment configured as described above feedback-controls the output voltage, it is possible to accurately target the output voltage regardless of changes in circuit constants due to temperature, changes over time, and changes in the load connected to the output. The AC waveform of can be obtained. Therefore, it is possible to provide a compact, inexpensive, highly efficient inverter device with stable output and high accuracy.

In this embodiment, the case where the feedback control is performed by adding the error voltage detecting means to the inverter device of the second embodiment of the present invention has been described, but the first means and the third means of the present invention are used. It is obvious that the same effect can be obtained when the feedback control is performed by adding the error detecting means.

In the above embodiments, the resonance capacitor is connected to the primary side of the resonance coil or the high frequency transformer in parallel. However, the second resonance capacitor may be connected to the switching element, and only the switching element is connected. The resonance capacitors may be connected in parallel. Further, as the DC power supply, any power supply such as a rectified AC power supply can be used. The detecting means may have any configuration as long as it can detect a substantially normal line. The DC removing means may be another method such as superimposing a DC voltage for canceling the DC component without using the coupling capacitor. As a switching element, a bipolar transistor has been explained, but a MOSF
Any switching element such as ET, IGBT, GTO thyristor may be used. The error voltage detecting means has been described as the combination of the AC generating means and the error amplifier, but other methods such as calculation using a microcomputer may be used. Although the output voltage has been described as a sine wave, an arbitrary AC waveform can be obtained as a trapezoidal wave or a triangular wave. In addition, in the second and third embodiments, the case where a high voltage is obtained by boosting has been described, but it is also possible to lower the voltage or to raise or lower the voltage.

[0030]

As described above, according to the present invention, a resonance coil and a switching element connected in series to a DC power source, a resonance capacitor connected in parallel to the resonance coil or the switching element, and the resonance coil or the switching element are provided. Connected detection means, direct current removal means connected to the detection means, oscillation / driving means for periodically connecting / disconnecting the switching element, and connecting to the oscillation / driving means to instruct the conduction time of the switching element. By having the waveform command means and controlling the conduction time so that the output voltage of the direct current removing means has an alternating current waveform, a desired alternating current waveform can be obtained with a simple configuration including only one switching element. In addition, the switching element performs so-called soft switching operation, which reduces switching loss and improves efficiency. Cooling mechanism Ku device requires also small.
Therefore, it is possible to provide a compact, inexpensive, and highly efficient inverter device.

The present invention also provides a resonance coil and a switching element connected in series to a DC power source, a resonance capacitor connected in parallel to the resonance coil or the switching element, and a transformer means connected to the resonance coil or the switching element. A detecting means connected to the transforming means, a direct current removing means connected to the detecting means, an oscillating / driving means for periodically connecting / disconnecting the switching element, and a switching element connected to the oscillating / driving means. It is possible to easily obtain an extremely high voltage or a low voltage by the transformer by controlling the conduction time so that the output voltage of the direct current removing means has an AC waveform. Moreover, since it is inserted in the high frequency part, a small transformer compatible with high frequencies can be used. Therefore, it is possible to provide a compact, inexpensive, and highly efficient inverter device for a wide range of output voltages. Moreover, since the DC power supply and the output can be easily insulated even when the step-up / down is not performed, the inverter device can be easily used.

Further, according to the present invention, a high frequency transformer and a switching element connected in series to a DC power source, a resonance capacitor connected in parallel to the high frequency transformer or the switching element, and a detection means connected to the secondary side of the high frequency transformer. A direct current removing means connected to the detecting means, an oscillating / driving means for periodically connecting / disconnecting the switching element, and a waveform instructing means for connecting to the oscillating / driving means to instruct a conduction time of the switching element. Have,
By controlling the conduction time so that the output voltage of the DC removing means has an AC waveform, the high frequency transformer also serves as a resonance coil, so that the number of parts can be reduced. Therefore, it is possible to provide a more compact, inexpensive and highly efficient inverter device for a wide range of output voltages. Moreover, since the DC power supply and the output can be easily insulated even when the step-up / down is not performed, the inverter device can be easily used.

According to the present invention, an error voltage detecting means for detecting an error between the output voltage and a target AC waveform is connected to the waveform command means, and the conduction time is set so that the output voltage approaches the target AC waveform. By controlling the output voltage by feedback control, the circuit constant changes with temperature and time,
Further, the target AC waveform can be accurately obtained regardless of the fluctuation of the load connected to the output. Therefore, it is possible to provide a compact, inexpensive, highly efficient inverter device with stable output and high accuracy.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an inverter device according to a first embodiment of the present invention.

FIG. 2 is an operation waveform diagram for explaining the operation of the device.

FIG. 3 is a schematic configuration diagram of an inverter device according to a second embodiment of the present invention.

FIG. 4 is an operation waveform diagram for explaining the operation of the device.

FIG. 5 is a schematic configuration diagram of an inverter device according to a third embodiment of the present invention.

FIG. 6 is an operation waveform diagram explaining the operation of the device.

FIG. 7 is a schematic configuration diagram of an inverter device according to a fourth embodiment of the present invention.

FIG. 8 is a schematic configuration diagram of a conventional inverter device.

FIG. 9 is an operation waveform diagram illustrating the operation of the device.

[Explanation of symbols]

 9, 14, 22 Resonance coil 10, 23, 47 DC power supply 11, 24, 38 Switching element 14, 27, 41 Resonance capacitor 15, 31, 42 Detection means 18, 35, 45 DC removal means 20, 47, 63 Oscillation / Drive means 21, 48, 64 Waveform command means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideyuki Konan 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (4)

[Claims] 1. A resonance coil and a switching element connected in series to a DC power source, a resonance capacitor connected in parallel to the resonance coil or the switching element, a detecting means and a DC removing means connected to the resonance coil or the switching element. And the switching element is periodically conducted.
An inverter device comprising an oscillating / driving means for shutting off, and a waveform command means for instructing a conduction time of the switching element, wherein the output voltage of the direct current removing means is an AC waveform by controlling the conduction time. 2. A resonance coil and a switching element connected in series to a DC power source, a resonance capacitor connected in parallel to the resonance coil or the switching element, a transformer means connected to the resonance coil or the switching element, The detecting means and the direct current removing means connected to the transforming means, the oscillating / driving means for periodically connecting / disconnecting the switching element, and the waveform commanding means for instructing the conductive time of the switching element are provided. An inverter device for controlling the output voltage of the DC removing means to have an AC waveform. 3. A high frequency transformer and a switching element connected in series to a DC power source, and a resonance capacitor connected in parallel to the high frequency transformer or the switching element.
A detection means and a direct current removal means connected to the secondary side of the high frequency transformer; an oscillating / driving means for periodically connecting / disconnecting the switching element; and a waveform commanding means for instructing a conduction time of the switching element, An inverter device in which the output voltage of the direct-current removing means has an alternating-current waveform by controlling the conduction time. 4. An error voltage detecting means, which is connected to the waveform commanding means and detects an error between the output voltage of the direct current removing means and the target AC waveform, controls the conduction time of the switching element to control the output voltage to the target AC. The inverter device according to any one of claims 1, 2, and 3, which is close to a waveform.