JPH02202372A - Inverter cooling controller - Google Patents

Abstract

PURPOSE:To enable continuous operation of plant by detecting malfunction of cooling facility for inverter and lowering output frequency. CONSTITUTION:An inverter inverts DC power fed from a rectifier 3 into AC power having predetermined frequency which is fed through an output transformer 6 to a load motor 7. A control circuit comprises a speed command converter 15, a voltage command controller 16, and the like, and further comprises a lowest speed setter 12 and a command switcher 13 as well as a cooling facility stop judging unit 31 and a time limit operation instantaneous reset relay 32. Upon stoppage of the cooling facility, a speed command is switched from the side of host controller 21 to the side of the lowest speed setter 12. Consequently, output frequency of inverter is lowered to the waiting operation frequency of a motor 7 and abrupt trip is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inverter cooling control device that enables continued operation of a plant or the like even when cooling equipment fails.

[Conventional technology]

In conventional inverter devices, for example, Japanese Patent Application Laid-Open No. 59-139
As disclosed in Publication No. 891.

The electric motor, which is the load, is variably controlled by controlling the output voltage and output frequency of the inverter in accordance with a rotational speed command from a host control device.

By the way, in an inverter, frequency conversion is performed by a power semiconductor element, and cooling is required to keep this semiconductor element at an operable temperature.

When the capacity of the inverter is large, the amount of heat generated in the semiconductor elements is also large due to switching loss, etc.
It must be cooled by forced air cooling, and cooling fans and coolers are installed. These cooling facilities may be provided exclusively for each inverter, but if there are multiple inverters.

It is common to use a single cooling facility in order to reduce the number of facilities.

[Problem to be solved by the invention]

However, in the above-mentioned conventional technology, if the cooling equipment fails and stops, there is a risk that the inverter will trip due to the temperature rise and the load will stop.

In particular, when multiple loads are controlled by multiple inverters, the cooling equipment of these inverters is shared, so a failure can cause multiple loads to trip almost simultaneously.
This may lead to plant shutdown.

An object of the present invention is to provide an inverter cooling control device that allows plant operation to continue even when cooling equipment fails.

[Means to solve the problem]

In order to achieve the above object, the present invention provides i! An inverter cooling control device that cools an inverter device that controls the rotational speed of an electric motor with cooling air from a cooling facility, comprising a detection means for detecting a stop when the cooling facility has stopped, and a detection signal from the detection means. , and control means for lowering the output frequency of the inverter device to the standby operating frequency of the electric motor.

The present invention also provides an inverter cooling control device that cools an inverter device that controls the rotational speed of an electric motor by changing one frequency using cooling air from a cooling facility, and detects when the cooling facility stops. a detection means and a detection signal from the detection means;
A control means for lowering the output frequency of the inverter device to a standby operating frequency of the electric motor is provided, and the control means is incorporated in a host control device that outputs a rotational speed command to the electric motor.

Furthermore, the present invention provides an inverter cooling control device that cools an inverter device that controls the rotational speed of an electric motor by changing the frequency using cooling air from a cooling facility, including a detection means for detecting a stoppage of the cooling facility;
a control means that receives a detection signal from the detection means and lowers the output frequency of the inverter device to a standby operating frequency of the electric motor; an alarm device that issues an alarm when the cooling equipment stops; and a control device that issues an alarm when the cooling equipment stops; A standby cooling fan that is manually activated to air-cool the inverter device is provided.

Furthermore, the present invention provides an inverter cooling control device that cools an inverter device that controls the rotational speed of an electric motor by changing the frequency using cooling air from a cooling facility, including a detection means for detecting a stoppage of the cooling facility;
a control means that receives a detection signal from the detection means and lowers the output frequency of the inverter device to a standby operating frequency of the motor; a standby cooling fan that air-cools the inverter device; The cooling fan control device automatically starts the fan.

[Effect]

According to the above configuration, when the cooling equipment fails and stops, the detection means detects and detects the stoppage, and the detection signal is transmitted to the control means. The control means lowers the output frequency of the inverter device to the standby operating frequency of the electric motor based on the detection signal from the detection means, so that the electric motor is operated at the lowest speed. This can prevent sudden tripping of the inverter.

Furthermore, in the case of a so-called pump load in which the pump is rotated by an electric motor, the load output is proportional to the cube of the rotational speed, so the inverter output is significantly reduced due to a decrease in the output frequency. For this reason, the cooling requirement is also reduced, making it possible to continue operation for a while within the inverter's thermal margin. Therefore, if a spare cooling fan is operated to cool the inverter during that time, tripping of the inverter can be further prevented.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the control circuit configuration of the inverter. In the figure, the power supplied from the power supply bus 1 via the circuit breaker 2 is
After the input transformer 3 transforms the voltage to a voltage suitable for the inverter elements, the rectifier 4 converts the voltage into direct current. The inverter 5 converts direct current back into alternating current at a predetermined frequency. The output transformer 6 transforms the output voltage of the inverter 5 to a voltage suitable for the load motor 7.

Furthermore, the inverter is controlled as follows. The speed command issued from the host controller 21 is sent to the command switch 13.
After passing through the rate-of-change limiter 14, the command converter 15 converts it into a voltage command and a frequency command inside the inverter. The voltage command is transmitted to the rectifier 4 via the voltage controller 16, phase adjuster 17, and pulse amplifier 18, and the DC output voltage of the rectifier 4 is controlled by controlling the phase angle. on the other hand.

The frequency command is given by the ring counter 19. pulse amplifier 20
The signal is transmitted to the inverter 5 via the inverter 5, and the output frequency is controlled by controlling the switching period of the inverter. Here, when the cooling equipment is stopped, the cooling equipment stop determination device 31
The stoppage is determined by the time-limited instantaneous return relay 32.
After confirming that the judgment signal continues for a predetermined time, the result is transmitted to the command switch 13, and the speed command is sent from the host controller 21 to the lowest speed setter 1.
It can be switched to the 2nd side. As a result, the speed command is set to the lowest speed, but because of the change rate limiter 14, the actual output frequency does not fall immediately, but instead falls in a ramp-like manner as shown in FIG.

Note that in FIG. 1, the inverter panel 11 corresponds to an inverter device. Further, the minimum speed setting device 12, the command switching device 13, the cooling equipment stop determination device 31, and the time-limited operation instant return relay 32 constitute a control means.

FIG. 3 is a diagram in which the cooling equipment stop determination device 31 in FIG. 1 is incorporated into a cooling system. The high-temperature air generated by the inverter panel 11 is sucked out by a cooling fan 42 through an air conditioning duct 41 that is directly connected to it, and then cooled by a cooler 43 to the room where the inverter panel 11 is installed. will be returned to. Here, the cooling fan 42 and the cooler 43
constitutes the cooling equipment. A temperature detector 33 is provided within the inverter panel 11 as a detection means.

The cooling equipment stop determination device 31 compares the temperature detection value from the temperature detector 33 with a preset value, and determines that the cooling equipment has stopped when the detected value exceeds the set value.

According to this embodiment, the temperature inside the panel, which is directly related to the operation of the inverter elements, can be detected, so detection can be performed reliably, and since control is performed for each individual panel, even if the panel malfunctions, the temperature inside the panel can be detected. This has the effect of only having a negative impact.

Although the cooling equipment stop determination device 31 is depicted outside the inverter panel 11 in FIG. 3, it can also be incorporated into the inverter g111.

FIGS. 4 and 5 show an embodiment of the detection means for detecting a failure of the cooling equipment.

In FIG. 4, an air volume detector 34 is installed above the inverter panel 11 in the air conditioning duct 41 as a detection means.

The detected value from the airflow detector 34 is sent to the cooling equipment stop determination device 31
If the air volume drops below a certain level, it is determined that the cooling equipment has stopped.

According to this embodiment, since the air flow rate is directly detected, it is possible to reliably detect the stoppage of the cooling equipment. Also, each panel has an airflow detector 34.
By providing a cooling equipment stop determination device 31, control can be performed within each panel.

FIG. 5 shows an example in which the stoppage of a cooling fan is detected from the power supply side, and this is a case where multiple cooling fans are provided. In the figure, a cooling fan 42a.

42b is connected to the circuit breaker 4 from the power supply buses 45a and 45b, respectively.
It is operated by receiving power supply through 4a and 44b.

The circuit breaker open detectors 35a and 35b are connected to the circuit breaker 44a, respectively.
, 44b is detected and transmitted to the cooling equipment stop determination device 31. The cooling equipment stop determination device 31 includes circuit breakers 44a and 44b.
If both of the cooling fans 42a and 42b are opened, it is assumed that both the cooling fans 42a and 42b have stopped, and it is determined that the cooling equipment has stopped.

According to this embodiment, since stopping of the cooling fan can be directly detected, there is an effect that the time until detection is short.

FIG. 6 shows another embodiment of FIG. 1.

In the embodiment of FIG. 6, the command switch 23. Rate of change limiter 2
4. The minimum speed setter 22 is incorporated together with the system controller 26 into the host control device M21. The runback controller 25 receives a signal from the cooling equipment stop determination device 31 via the time-limited operation instantaneous return relay 32, but also receives a signal from the detector 61, which is a runback element, and stops the cooling equipment. command switch 2 when a runback is requested.
3 to the minimum speed setting device 22 side and inverter panel 1
A runback pattern as shown in FIG. 2 is directly output to the command converter 15 of No. 1.

According to this embodiment, the runback function can be concentrated in the upper control system and can be shared with other runback elements, so that equipment can be reduced.

FIGS. 7 and 8 are examples in which the output frequency of the inverter is run back when the cooling equipment is stopped, and at the same time, the preliminary cooling equipment is operated.

In FIG. 7, in addition to the normal cooling system, a small cooling fan 51 that is normally on standby is provided inside the panel. When the cooling equipment stop determination device 31 detects that the cooling equipment has stopped, the alarm device 39 generates an alarm. The manual damper 52 and the preliminary cooling fan 51 can be started manually, and the operator who has been notified by the alarm can start the cooling fan starter 53.
Start it manually. This cooling fan 51 only needs to have a capacity necessary for operating the inverter at the lowest speed.

It can be significantly smaller than the cooling fan 42 for normal use.

Note that the run-back of the inverter output frequency is the same as that described above, so a description thereof will be omitted.

According to this embodiment, the preliminary cooling fan 51 discharges the air inside the panel into the room, but since the indoor heat capacity is large, there is an advantage that the inverter in the standby state can continue to operate at the lowest speed for a considerable period of time. be.

FIG. 8 shows an example in which the preliminary cooling equipment is automatically operated. In FIG.
5. Both the damper drive device 55 and the preliminary cooling fan 51 are controlled by the preliminary cooling fan control device 54. The pre-cooling fan control device 54 drives the damper drive device 55 to open the damper 56 and starts the pre-cooling fan 51 when the cooling facility stop determiner 31 determines that the cooling facility is stopped.

According to this embodiment, since the preliminary cooling equipment can be operated automatically, there is an effect that no operation by an operator is required.

〔Effect of the invention〕

As explained above, according to the present invention, even if the inverter cooling equipment fails and stops, the inverter does not trip immediately, making it possible to continue operating the electric motor, improving the operating rate of the plant. It has the effect of being able to

[Brief explanation of the drawing]

Figure 1 is an inverter control circuit configuration diagram, Figure 2 is a diagram showing how the inverter output frequency changes over time, Figure 3 is a schematic diagram of a cooling equipment stop judge incorporated into the cooling system, Figure 4 and FIG. 5 is a configuration diagram showing another embodiment of FIG. 3;
FIG. 6 is a block diagram of an inverter control circuit showing another embodiment of the embodiment shown in FIG. 1, and FIGS. 7 and 8 are schematic diagrams in which a preliminary cooling facility is added to the cooling system. 1... Power bus, 2... Power breaker, 3... Input transformer, 4... Rectifier, 5... Inverter, 6...
・Output transformer, 7...Load motor, 11...Inverter panel, 12...Minimum speed setter, 13...Command switcher, 14...Change rate limiter, 21...Upper Control device, 31... Cooling equipment stop determination device, 32... Time-limited operation instantaneous return relay. 33... Temperature detector, 34... Air volume detector, 35.
...Breaker open detector, 41...Air conditioning duct, 42...
- Cooling fan, 43... Cooler, 44... Cooling fan power supply circuit breaker, 45... Cooling fan power supply bus, 51.
... Pre-cooling fan, 52... Manual damper, 53...
- Preliminary cooling fan starter, 54... Preliminary cooling fan control device, 55... Damper drive device, 56... Damper.

Claims (7)

[Claims] 1. In an inverter cooling control device that cools an inverter device that controls the rotational speed of an electric motor by changing the frequency using cooling air from a cooling facility, a detection means for detecting a stop when the cooling facility stops; An inverter cooling control device comprising: a control device that receives a detection signal from the device and lowers the output frequency of the inverter device to a standby operating frequency of the electric motor. 2. The inverter cooling control device according to claim 1,
An inverter cooling control device, wherein the detection means is a temperature detector that detects an ambient temperature near the inverter device. 3. The inverter cooling control device according to claim 1,
An inverter cooling control device characterized in that the detection means is an air volume detector that detects an air volume near the inverter device. 4. The inverter cooling control device according to claim 1,
The inverter cooling control device is characterized in that the detection means is a detector that detects connection and disconnection of a power source that drives a cooling fan of the cooling equipment. 5. In an inverter cooling control device that cools an inverter device that controls the rotational speed of an electric motor by changing the frequency using cooling air from a cooling facility, a detection means for detecting a stop when the cooling facility stops; and a control means that receives a detection signal from the means and lowers the output frequency of the inverter device to a standby operating frequency of the electric motor, and the control means is incorporated into a host control device that outputs a rotational speed command to the electric motor. An inverter cooling control device featuring: 6. In an inverter cooling control device that cools an inverter device that controls the rotational speed of an electric motor by changing the frequency using cooling air from a cooling facility, a detection means for detecting a stoppage of the cooling facility, and a detection means for detecting a stoppage of the cooling facility. a control means that receives a signal and lowers the output frequency of the inverter device to a standby operating frequency of the electric motor; an alarm device that issues an alarm when the cooling equipment stops; and a control device that is manually activated based on the alarm of the alarm device; An inverter cooling control device comprising: a spare cooling fan that air-cools the inverter device. 7. In an inverter cooling control device that cools an inverter device that controls the rotational speed of an electric motor by changing the frequency using cooling air from a cooling facility, a detection means for detecting a stoppage of the cooling facility, and a detection means for detecting a stoppage of the cooling facility. a control means that receives a signal and lowers the output frequency of the inverter device to a standby operating frequency of the electric motor; and a backup cooling fan that air-cools the inverter device;
An inverter cooling control device comprising: a cooling fan control device that automatically starts the cooling fan when the cooling equipment stops.