JP3047313B2 - Inverter monitoring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter monitoring device for monitoring a half-wave output from an inverter.

[0002]

2. Description of the Related Art A voltage output type inverter for converting a DC voltage into an AC voltage having a desired frequency and outputting the converted AC voltage is well known. Such an inverter normally outputs an alternating waveform having the desired frequency. For example, when some switching elements malfunction, a half-wave waveform may be output due to the malfunction.

[0003]

However, when such a half-wave waveform is output from the inverter, if the motor is driven by the inverter as a power source, the motor cannot be started properly or its abnormal waveform is generated. Of the stator coil. Also, if an inverter with an inductive load such as a motor or transformer is connected to the inverter, an excessive short-circuit current will flow through the inductive load due to the half-wave waveform from the inverter, and in the worst case,
In some cases, the winding was burned. The present invention has been proposed in view of the above, and an object of the present invention is to provide an inverter monitoring device capable of monitoring an operation failure of an inverter and stopping power supply to a load when the operation failure is detected.

[0004]

In order to achieve the above object, an inverter monitoring apparatus according to the present invention comprises a rectangular wave output from an inverter, the direction of which changes after a pause.
A rectified waveform output means for outputting the AC output waveform by full wave rectification, when Lo level of the output waveform of the rectified waveform output means
From the width, it becomes a synchronization signal for the AC output waveform at the inverter.
H of the inverted base waveform generated by inverting the base waveform
Lo level only for the time obtained by subtracting the i-level time width
Abnormality detecting means for outputting an abnormal waveform detection signal, abnormality determining means for determining that the AC output waveform from the inverter is abnormal based on the abnormality detection signal and outputting an abnormality determination signal, and receiving the abnormality determination signal To operate the inverter
And an inverter operation stopping means for stopping the operation .

[0005]

As described above, in the inverter monitoring apparatus according to the present invention, the rectified waveform output means performs full-wave rectification on the AC output waveform output from the inverter as a rectangular wave whose direction changes after a pause period and outputs the rectified waveform. , The abnormality detection means is a rectified wave
From the Lo level time width of the output waveform of the
The base waveform, which is the synchronization signal for the AC output waveform at the
The Hi level time width of the inverted base waveform generated by
Abnormal waveform detection signal that becomes Lo level only for the subtracted time
To output. Then, based on the abnormal waveform detection signal, the abnormality determining means determines that the AC output waveform from the inverter is abnormal, outputs an abnormality determination signal, and outputs the abnormality determination signal.
In response to this, the inverter operation stop means operates the inverter.
Stop .

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing the overall configuration of the inverter monitoring device of the present invention. In the figure, an inverter 2 is used in a generator 1 for a vehicle which has already been commercialized by the applicant, and once rectifies a three-phase AC supplied from the generator 1 into DC and then converts it into an AC voltage of a predetermined frequency. I do. The AC voltage is output as a power supply voltage to a load (not shown) via two power supply lines 21a and 21b. Further, the power is output to the inverter monitoring device 3 through the two power supply lines 21a and 21b as shown in the figure.

The inverter monitoring device 3 receives the AC output from the inverter 2 and monitors the operation of the inverter 2. The inverter monitoring device 3 performs full-wave rectification on the AC output waveform output from the inverter 2 and outputs the rectified waveform. Means 4, an abnormality detection means 5 for detecting an abnormal waveform generated due to an abnormality in the AC output waveform of the inverter 2 among the output waveforms from the rectified waveform output means 4, and outputting the detected abnormal waveform as an abnormal waveform detection signal; Abnormality determining means 6 for determining that the AC output waveform from the inverter 2 is abnormal based on the abnormal waveform detection signal and outputting an abnormality determination signal.

The abnormality detecting means 5 detects an abnormal waveform based on the output waveform (full-wave rectified waveform) of the rectified waveform output means 4 and the inverted base waveform. Here, the inverted base waveform is a synchronizing signal of the AC output waveform in the inverter 2 and is generated by inverting the base waveform output from the base waveform generating means 23 in the inverter 2.

An abnormality determination signal output from the abnormality detecting means 5 is input to the inverter operation stopping means 22.
The inverter operation stopping means 22 stops the operation of the inverter 2 upon receiving the abnormality determination signal.

FIG. 2 is a schematic circuit diagram showing a specific example when the inverter monitoring device 3 is assembled as an electronic circuit. In the figure, the rectified waveform output means 4 of the inverter monitoring device 3
Is composed of a rectifier 41 formed by coupling four switching elements in a bridge shape, and a photocoupler 42. An AC voltage of 100 V AC as shown in FIG. 3 is applied to the rectifier 41 from the inverter 2. The rectifier 41 performs full-wave rectification on the AC voltage waveform and applies the rectified waveform to the light emitting diode of the photocoupler 42. A forward voltage is sequentially applied to the light emitting diode in accordance with the full-wave rectified waveform, and a signal S2 (FIG. 3) having a pulse waveform is output from the phototransistor of the photocoupler 42 in response thereto. The signal S2 is sent to the abnormality detecting means 5.

Note that the AC output of the inverter 2 and the signal S2 do not rise immediately after the power switch of the inverter 2 is turned on, but a certain period of time elapses before it rises.

FIG. 3 shows the AC output from the inverter 2.
When a half-wave as shown in (1) is generated, the signal S2 is maintained at 0 V (Lo level) in a portion corresponding to the half-wave under the influence of the half-wave, and does not have a pulse waveform.

The abnormality detecting means 5 includes an OR circuit 52 and its O
And a NOT circuit 54 connected in series to the R circuit 52. The OR circuit 52 receives the above-described signal S2, a base inversion signal S3, and a power-on reset signal S1. The base inversion signal S3 is a signal generated by inverting the base signal S7, which is a synchronization signal of the AC output waveform in the inverter 2, by the NOT circuit 51, and Hi and Lo appear exactly opposite to the signal S2. It has become.

The power-on reset signal S1 is a signal for securing time until the AC output from the inverter 2 rises when the power switch of the inverter 2 is turned on.

When the AC output from the inverter 2 is normal and these three signals S1, S2 and S3 are input to the OR circuit 52, the OR circuit 52 continuously outputs H
The signal S4 having the i level is output. The reason why the signal S4 is held at the Hi level at the same time when the power switch of the inverter 2 is turned on is that the power-on reset signal S1 is continuously input until the AC output from the inverter 2 rises, and during that time, the base is turned on. This is because the pulse of the inverted signal S3 is not output from the OR circuit 52 as it is.

On the other hand, if a half-wave is included in the AC output from inverter 2, signal S4 output from OR circuit 52 is output.
Is a pulse wave that becomes Lo level for a time obtained by subtracting the time width during which the base inverted signal S3 is at Hi level from the time width during which the signal S2 is at Lo level.

The signal S4 from the OR circuit 52 is then inverted by the NOT circuit 54, so that the signal S4 becomes H corresponding to only a portion where a half wave appears in the AC output of the inverter 2.
The half-wave detection signal S5 at the i level is sent to the abnormality determination means 6. The signal S4 output from the OR circuit 52 includes a beard-like signal of about 70 μsec in order to prevent a bridge arm short circuit in the rectifier 41.
7, the OR circuit 52 and the NOT circuit 5
4 and a CR circuit 53 is provided between them, and the CR circuit 52 removes the CR circuit.

The abnormality determining means 6 comprises a count circuit 61 and a NOT circuit 62 connected in series to the count circuit 61. When the above-described half-wave detection signal S5 is input to the count circuit 61, the count circuit 61 counts the number of pulses of the half-wave detection signal S5, and counts a predetermined number of pulses or more, for example, 20 or more pulses. At this time, via the NOT circuit 62, the abnormality determination signal S6
Is output.

That is, if the AC output of the inverter 2 is normal, the half-wave detection signal S5 is continuously at the Lo level, so that the count circuit 61 does not count and does not output the abnormality determination signal S6. On the other hand, when a half-wave appears in the AC output of the inverter 2, a half-wave detection signal S5 is output as a clock pulse corresponding to the half-wave.
The count circuit 61 counts the clock pulse,
When counting is performed for 20 pulses or more, the NOT circuit 62 outputs the abnormality determination signal S6.

The count circuit 61 receives a count reset signal S8 from the count circuit 7. That is, the count circuit 7 receives the base signal S7 (synchronous signal of the AC output waveform in the inverter 2) and counts the pulses, and counts 99 pulses corresponding to about 1 second (when the output frequency is 50 Hz). When counting
The count reset signal S8 is output to the count circuit 61. The count circuit 61 counts the above-described half-wave detection signal S5 for about one second after receiving the count reset signal S8 until the next count reset signal S8 arrives, and counts 20 pulses or more during that time. At this time, the abnormality determination signal S6 is output.

The reason why the count of the half-wave detection signal S5 is reset when the predetermined time exceeds about one second is that even if the half-wave detection signal S5 is output, 20 pulses are output within the predetermined time. If the frequency of occurrence is such that minutes are not counted, there is no problem even if the inverter 2 is used as a power supply.

The reason why the abnormality determination signal S6 is not output unless 20 or more pulses are counted is that, depending on the use condition when the power switch of the inverter 2 is turned on, the inverter 2 is not completely turned on until the inverter 2 completely starts up. In some cases, it takes more time than the power-on reset signal S1 secures. In this case, since the AC output waveform is still at the rising edge, it is detected that the AC output waveform is about one.
Three pulses are output as the half-wave detection signal S5. Therefore, 20 pulses that have sufficiently cleared the 13 pulses are counted to avoid an erroneous determination that a normal rise is regarded as a half-wave output.

The inverter 2 is normally turned on by a power switch, but may be turned on by a reset switch when the AC output trips for some reason during operation. In such a case, the power-on reset signal S1
Is not output, the power-on reset signal S1
Instead of the reset switch signal S9
To enter. Reset switch signal S9 is power ON
Like the reset signal S1, the signal holds the Hi level for a time sufficient to secure the rise of the inverter 2, and the count circuit 61 disables the count mode while the reset switch signal S9 is output. As a result, it is possible to avoid erroneous determination at the time of startup by the reset switch.

As described above, the abnormality determination signal S6 is output from the inverter operation stopping means 22 provided in the inverter 2.
The inverter operation stopping means 22 receives the abnormality determination signal S6 and cuts off the operation of the inverter 2. The inverter operation stopping means 22 includes, for example, the inverter 2
Is configured to input an abnormality determination signal S6 to each switching element forming the H-bridge and turn off each switching element. In addition, the inverter monitoring device 3
The photocoupler 42, the count circuit 61, and the count circuit 7 have a control voltage of 5 V as shown in FIG.
Is supplied.

As described above, in this embodiment, the AC output waveform output from the inverter 2 is full-wave rectified, and an abnormal waveform in the full-wave rectified waveform is detected to determine that the AC output waveform is abnormal. Since the determination is made and the abnormality determination signal is output, even if the switching element of the inverter 2 causes a malfunction and a half-wave waveform is output, the occurrence of the half-wave waveform can be accurately detected. In response to the detection of the half-wave waveform, the operation of the inverter 2 can be stopped, thereby preventing a situation such as a start-up failure of a load such as a motor or a burn-out of a stator coil caused by being restrained by an abnormal power supply. be able to.

The main part of the inverter monitoring device 3 is
Since it was composed of a rectifier, OR circuit and count circuit,
The inverter monitoring device 3 can be simply configured with a small number of components and a small number of components, and does not require much space. Therefore, the inverter monitoring device 3 can be housed in an inverter system without externally attaching the inverter monitoring device 3, and the inverter system itself can be constructed in a small space. In addition, the user can save time and effort for external attachment and can use the device easily.

Further, when the AC output waveform from the inverter 2 is normal, the signal S2 and the inverted base signal S3, which are full-wave rectified waveforms, are such that Hi and Lo appear exactly opposite to each other. If any abnormal part occurs in the AC output waveform from 2, the abnormality appears in the output signal S4 of the OR circuit 52. Therefore, for example, even if a pseudo AC waveform is generated by a back electromotive voltage generated when a half-wave output enters a transformer winding or the like, the pseudo AC waveform can be accurately detected, and the half-wave waveform can be detected with high accuracy. become.

In the above description, the pulse count up to the abnormality detection is set to 20 pulses, but this pulse count can be set arbitrarily as needed.

[0029]

As described above, according to the inverter monitoring apparatus of the present invention, the AC output waveform output from the inverter is full-wave rectified, and an abnormal waveform in the full-wave rectified waveform is detected to output the AC output. Since the waveform is determined to be abnormal and an abnormality determination signal is output, even if the switching element of the inverter causes a malfunction and a half-wave waveform is output, it is necessary to accurately detect the occurrence of the half-wave waveform. Can be
In addition, the operation of the inverter can be stopped in response to the detection of this half-wave waveform, preventing the start-up failure of the load of the motor and the like, and the situation where the stator coil is burned out due to being restrained by the abnormal power supply. can do. Further, since the main part of the inverter monitoring device is constituted by the rectifier, the OR circuit, and the counting circuit, the inverter monitoring device can be simply configured with a small number of components and component types, and does not require much space. For this reason, it is possible to store it on a printed circuit board, and it is possible to use it built in the inverter system without externally installing an inverter monitoring device. Also, the user can save time and effort for external attachment, which makes it easy to use.
Furthermore, if any abnormal part occurs in the AC output waveform from the inverter, the abnormality appears as an abnormal waveform detection signal. For example, a pseudo AC waveform is generated by a back electromotive voltage generated when a half-wave output enters a transformer winding or the like. Is generated, the pseudo AC waveform can be accurately detected, and the half-wave waveform can be detected with high accuracy.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of an inverter monitoring device according to the present invention.

FIG. 2 is a schematic circuit diagram as a specific example of an inverter monitoring device.

FIG. 3 is a time chart showing signals at each point of the inverter monitoring device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Generator 2 Inverter 3 Inverter monitoring apparatus 4 Rectification waveform output means 5 Abnormality detection means 6 Abnormality determination means 7 Count circuit 22 Inverter operation stop means 23 Base waveform generation means 41 Rectifier 42 Photocoupler 52 OR circuit 61 Count circuit

Claims (1)

(57) [Claims] 1. An idle period output from an inverter is defined as
A rectified waveform output means for performing full-wave rectification on an AC output waveform as a rectangular wave whose direction changes through the output, and a Lo level time width of the output waveform of the rectified waveform output means .
The base that becomes the synchronization signal of the AC output waveform in the inverter
Hi level of the inverted base waveform generated by inverting the base waveform
Abnormal wave which becomes Lo level only for the time which deducted the time span
Abnormality detection means for outputting a shape detection signal; abnormality determination means for determining that the AC output waveform from the inverter is abnormal based on the abnormality detection signal and outputting an abnormality determination signal; and receiving the abnormality determination signal. Stop the operation of the inverter
An inverter monitoring device comprising: an inverter operation stopping unit .