JPS60257737A - Cooler of fully-closed electric device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a cooling device for a completely enclosed electric machine that includes a built-in heat exchanger for cooling air inside the machine that is forced to circulate by a fan having a drive motor. This type of cooling system is designed to handle not only temperature rises in various parts of the electric machine based on load characteristics, but also local temperature rises in the coils of the stator or rotor caused by the operating conditions of the electric machine. It is desirable that optimal cooling can be achieved by circulating the cooling air inside the machine, and that the power consumption or noise of the fan be as low as possible.

[Prior art and its problems]

Conventionally, a general totally enclosed electric machine uses a fan with a drive motor to forcefully circulate the air inside the machine to cool each part of the electric machine, and the air, whose temperature has risen as a result, is cooled by a heat exchanger placed at an appropriate place inside the machine. In machines,
Normally, during rated load operation of the electric machine, the amount of air circulation inside the machine and the capacity of the heat exchanger are determined so as to obtain sufficient cooling to suppress the temperature rise in each part of the machine to below a predetermined value. It has been common practice to determine the capacity of the fan and thus the output and rotational speed of its drive motor on the basis of the amount of circulation. Moreover, in the past, once the rotation speed of the fan was determined, the fan would be operated at the specified rotation speed without adjustment, regardless of the load characteristics of the electrical machine or the operating conditions.
Even when the electric machine is operated at a load much lighter than the rated load, the capacity of the fan is 100 cm, and the amount of air circulated is less than the amount required for cooling at that time, resulting in wasted power. Not only is it uneconomical, but the noise generated by the fan cannot be ignored.

Further, in the case where the electric machine is a variable speed DC motor that performs field control, when the field of the motor is strengthened and controlled to a low speed operation, the copper loss of the field coil increases significantly. While the temperature of the coil increases slightly, if the field is controlled to a weak field and the motor is operated at bird speed, the load current of the motor, that is, the armature current, may increase depending on the characteristics of the driven load. The temperature of the armature coil increases significantly, while the current in the field coil decreases, causing its temperature to decrease. However, when operating this type of motor, heat loss in the armature coil and field coil increases or decreases depending on the load characteristics and rotation speed throughout the speed control range of the motor, so it is necessary to cool this type of motor satisfactorily. The amount of air circulation is determined so that sufficient cooling can be obtained to suppress the temperature rise of each part such as the armature coil and field coil to a predetermined value or less under conditions where the temperature rise of each part such as the armature coil and field coil is maximum. The output and rotational speed of the drive motor are determined according to the fan capacity corresponding to the fan capacity. Therefore, the output of the drive motor is large, corresponding to the maximum loss of the drive motor, and the size of the drive motor is large, and in this case also, the fan is operated at a constant speed at a predetermined rotation speed. The air circulation ability of the fan remains unchanged even with the changing load or operating conditions of the electric motor, and the problems of uneconomical power consumption and noise are similar to the above-mentioned "mixing".

[Purpose of the invention]

The present invention has been developed in view of the above-mentioned drawbacks of a conventional cooling system in which a completely enclosed electric machine with a built-in heat exchanger is forced to circulate cooling air inside the machine by a fan having a drive motor and cooled by the heat exchanger. The system constantly provides optimal cooling in response to not only the overall temperature rise during rated operation of the electric machine, but also local temperature rise fluctuations of the rotor coil or stator coil that occur depending on the load characteristics and operating conditions of the electric machine. It is an object of the present invention to provide a cooling device for a completely enclosed electric machine, which can control the operation of the fan according to the present invention, thereby reducing power consumption of the drive motor and noise.

C. Summary of the Invention] In order to achieve the above object, the present invention provides the above-mentioned cooling device, which includes cooling air inlet and outlet sides of a heat exchanger disposed inside the electric machine, a rotor coil, and a stator. Temperature detection means are provided at appropriate locations on each of the coils, means for converting the temperatures detected by the temperature detection means provided at the cooling air inlet and outlet sides of the heat exchanger into air signals, and a means for converting the output signals of the conversion means into air signals. a first circuit comprising differential increasing means for calculating the difference value, means for comparing the output signal of the amplifying means with a preset value, and means for amplifying the output signal of the comparing means as necessary; , means for individually converting the temperatures detected by the temperature detecting means of the rotor coil and stator coil into electrical signals via appropriate receiving means as needed; It consists of a means for comparing with a set value 1 and a second circuit for the stator coil, which has a zero-hold amplification means that is turned on and off by the output signal of the comparison means, and a completely similar third circuit for the rotor coil. , the output signals of the first circuit, the second circuit, and the third circuit are input to the control circuit of the variable voltage variable frequency inverter via one adding means, and the output signals of the inverter corresponding to the input signals are inputted to the control circuit of the variable voltage variable frequency inverter through one adding means. By operating the drive motor of the fan at variable speed according to the output, the amount of circulating cooling air is controlled so that optimal cooling of each part of the electrical equipment is always obtained regardless of the load characteristics or operating conditions of the electrical machine. It is something.

[Embodiments of the invention]

Next, the present invention will be explained in detail based on the embodiments shown in the drawings.

A heat exchanger 4 is disposed at an appropriate location inside the fully enclosed electric machine 1 shown in FIG. It is then cooled down.

The fan 5 is driven by a drive motor 5a located at a suitable location outside the electric machine 1.

First, temperature detectors 7 and 8 are placed on the inlet and outlet sides of the heat exchanger 4 for the cooling air 6, and the detected value of the temperature detector 7 is transmitted through the temperature converter 12a. The detected values are each converted into an electric signal via the temperature converter 12b, and then input to the differential amplifier 13 to obtain a signal corresponding to the difference value between the two signals. The output signal of the differential amplifier 13 is compared with the set value of the setter 14a, and the resulting distorted output signal is amplified by the amplifier 15 as necessary and inputted to the amplifier 18.

On the other hand, electric machine 10 rotor coil 2 and stator coil 3
As mentioned above, in the case of a variable speed DC motor, the temperature rise does not necessarily fluctuate depending on the load characteristics and operating conditions;
Generally, the thermal time constants of the rotor coil 2 and stator coil 3 are significantly smaller than the thermal time constant of the cooling air 6. Cooling air 6 reduces the temperature rise of child coil 3.
It is difficult to ascertain the temperature increase due to the temperature rise of Temperature detectors 9 and 11 are provided in the rotor coil 2 and stator coil 3, respectively, to detect the temperatures of the rotor coil 2 and stator coil 3, and are provided to prevent overheating of the respective coils. In this case, it is preferable to arrange a signal receiver 10 on the stator side of the electric machine 1 so that the temperature detector 9 of the rotor coil 2 can receive the detected value of the temperature detector 9 during operation.

At this time, the detected value of the temperature detector 9 of the rotor coil 2 is sent to the temperature converter 12C via the receiver 10.
The output signal of C is sent to the setter 14 in the comparator 16a.
The output signal of the comparator 16a turns on and off the amplifier 17a held at zero, and the output signal of the amplifier 17a is input to the adder 18.

In the same shuttle, the detected value of the temperature detector 11 of the stator coil 3 is sent to the temperature detector 12d, and the output signal of the converter 12d is compared with the set value of the setting device 14C in the comparator 16b. The amplifier 17b whose output signal is held at zero is turned on and the amplifier 17b is turned on.
The output signal of is input to the adder 18.

As mentioned above, the above signal regarding the difference between the inlet side temperature and the outlet side temperature of the heat exchanger 4 of the cooling air 6, the above signal regarding the temperature of the rotor coil 2, and the above signal regarding the temperature of the stator coil 3, respectively. The inputs are individually input to an adder 18, and the output of the adder is input to a control device for an inverter 19, which is a power source for the fan motor 5a. When operating under load, the temperature difference between the inlet side temperature and the outlet side temperature of the heat exchanger of the cooling air 6 is small, so the temperature detectors 7 and 8
, and the value of the signal related to the temperature difference obtained from the differential amplifier 13 via the temperature converters 12a and 12b is lower than the setting value of the setting device 14a, and no output signal is obtained to the amplifier 15. Furthermore, in general, the currents in the rotor coil 2 and stator coil at this time are much lower than the rated values, and the temperatures of the coils 2 and 3 are also below a predetermined value, so the amplifier 1
Since no output signal is obtained at either 7a or 17b, the input signal to the control device for inverter 19 via adder 18 is zero, and inverter 19 does not operate, so fan 5 is in a stopped state.

Next, when the load on the electric machine 1 increases from the above-mentioned state, the loss in each part of the machine increases, and therefore the temperature difference between the inlet side and the outlet side of the heat exchanger 4 of the cooling air 6 increases.

As a result, the output signal of the differential amplifier 13 related to the temperature difference exceeds the set value of the setter 14, and a signal is output from the amplifier 15 and inputted to the control circuit of the inverter 19 via the adder 18. Therefore, the output voltage and frequency of the inverter 19 are controlled in accordance with the input signal, and power is supplied to the fan motor 5a, so that the fan 5 can control the temperature of the cooling air 6 at the inlet side and the outlet side of the heat exchanger 4. It rotates at a rotational speed commensurate with the difference, circulates cooling air, and cools each part of the machine. At that time, if the temperature of the rotor coil 2 and stator coil 3 is low and no output signal is obtained from the comparator 16a or 16b, the fan 5 only controls the temperature of the cooling air 6 at the inlet side and outlet side of the heat exchanger 40. Operation continues with the output of inverter 19 matching only the signal relating to the difference.

Next, when the load increases and the temperature of the rotor coil 2 or stator coil 3 exceeds a predetermined value in the fan operating state as described above, the comparator 16a or 16b automatically resets the amplifier 17a or 17b, or the like. Signals are output from both of them, and both of these signals are sent to the adder 18 and sent to the cooling air 6.
The fan motor 5a is added to a signal regarding the temperature difference between the inlet side and the outlet side of the heat exchanger 4 and is inputted to the control circuit of the inverter 19, and the output voltage and frequency of the inverter 19 that correspond to the added signal are used to control the fan motor 5a. is driven, and the amount of circulating cooling air is controlled so that the temperature rise in each part of the electric machine 1 is suppressed to a predetermined value or less.

Finally, in a special case, when the electric machine is under a light load, the fan motor is operated with an output of the inverter 19 corresponding to the signal due to the slight temperature difference between the inlet side and the outlet side of the heat exchanger 4 of the cooling air 6. If the temperature of the rotor coil 2 or stator coil 3 suddenly rises and exceeds a predetermined temperature for some reason, the comparator 16a or 16b
When a signal is output to the amplifier 17a6 or 17b, the output signal of the amplifier 17a or 17b controls the inverter 19 by controlling the inverter 19 over the signal corresponding to the slight temperature difference of the cooling air. The Jinoan motor 5a is operated at the output voltage and frequency of the inverter 19 that corresponds to the output signal of the amplifier 17a or 17b until the temperature rise of the stator coil A-3 becomes below a predetermined value.

〔Effect of the invention〕

As explained above, the present invention provides a cooling system for a totally enclosed electric machine that includes a built-in heat exchanger for cooling the air inside the machine that is forcibly circulated by a fan having a driving motor. Nine temperature detection means are provided at suitable locations on the air inlet and outlet sides and the rotor coil and stator coil of the electric machine, respectively, and the temperature detection means are provided on the cooling air inlet and outlet sides of the heat exchanger, respectively. means for converting the detected temperature into an electrical signal; differential amplification means for calculating the difference between the output signals of the conversion means; means for comparing the output signal of the amplification means with a specific set value; A first circuit having means for amplifying the output signal of the comparing means as necessary, and temperature detecting means provided for each of the rotor coil and the stator coil individually and appropriately as necessary. A means for converting the output signal of the converting means into an electrical signal through a receiving means, and a zero hold which is turned on and off by the output signal of the rgf dazama samehansetsu at a specific dead value VF+-Same size, respectively. a second circuit for the rotor coil having an amplification means and a third completely similar circuit for the stator coil, said first circuit;
The output signals of the second circuit and the third circuit are inputted to the control circuit of the variable voltage variable frequency inverter through one adding means, and the output of the inverter corresponding to the input signal is applied to the control circuit of the variable voltage variable frequency inverter. By operating the fan drive motor at variable speed, the output of the inverter that serves as the power source for the fan motor can be controlled according to the load characteristics of the electric machine or the imbalance in temperature rise in various parts of the machine based on its operating conditions. Since the fan speed can be adjusted and the amount of cooling air circulated inside the machine can be adjusted to always provide optimal cooling, fan drive power can be significantly reduced compared to conventional fans that operate at a constant speed, and noise can be reduced. This has the effect of reducing the

In addition, in the present invention, when the cooling medium is forcibly supplied to the heat exchanger from the outside, the same effect as in the above embodiment can be obtained by varying the supply amount of the cooling medium depending on the temperature. can.

[Brief explanation of the drawing]

FIG. 1 is a schematic circuit diagram showing a fan rotation speed control system for controlling the amount of cooling air circulated in a cooling system for a totally enclosed electric machine according to the present invention. 1... Totally enclosed electric machine, 2... Rotor coil, 3...
...Stator coil, 4...Heat exchanger, 5...Fan, 5a...Fan motor, 6...Cooling air, 7,8
,9゜11...Temperature detector, 10...Rotor coil temperature detection signal receiver, 12a, 12b, 12C, 12d
...Temperature converter, 13...Differential amplifier, 14a, 1
4b. 14 C-...setting device, 15...amplifier, 16a,
16b... Comparator, 17a, 17b... Zero hold amplifier, 18... Adder, 19... Variable voltage variable frequency inverter. Figure 1

Claims (1)

[Scope of Claims] 1) A heat exchanger for cooling the air in the totally enclosed container in a completely enclosed electrical device in which the electrical device is housed in a totally enclosed container, and an electric motor for forcibly circulating the air inside the device to the heat exchanger. Detecting the temperature of at least one of the circulation means or the electric supply means for forcibly supplying the cooling medium to the heat exchanger, and at least one of the electric equipment or the internal air circulated to the heat exchanger or the supplied cooling medium. 1. A cooling device for a completely enclosed electrical appliance, comprising a temperature detector and means for varying the speed of the electric circulation means or the electric supply means according to the output of the temperature detector. 2. A cooling device for a totally enclosed electric appliance according to claim 1, wherein the electric circulation means or the electric power supply means includes an AC motor, and the means for varying the speed is an inverter.