JP2008164267A - Refrigerating cycle device using expander - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a refrigerating cycle device using an efficient and reliable expander. <P>SOLUTION: The refrigerating cycle device is provided with: a refrigerating cycle comprised of a compressor 501 compressing a coolant, a radiator 502 cooling the compressed coolant, the expander 503 expanding the coolant, and an evaporator 504 evaporating the expanded coolant; and a control circuit comprised of a generator 507 connected to the expander 503, and a variable speed converter 508 converting AC power output by the generator 507, outputting DC power, and carrying out driving control of the generator 507. Abnormal rising of a voltage value of a direct current power part when generator power exceeds motor power, is suppressed by setting a rotational frequency of a blow fan 522 high, and the reliable and efficient refrigerating cycle device without breaking in components is provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a power recovery apparatus using an expander that uses an expansion force such as a refrigerant, and more particularly to an expander control apparatus for improving the efficiency of a vapor compression refrigeration apparatus using carbon dioxide as a refrigerant.

  As a conventional general vapor compression refrigeration apparatus, there is a structure shown in FIG. The vapor compression refrigeration apparatus in FIG. 17 includes a compressor 301, a radiator 302, an expansion valve 303, and an evaporator 304. These elements are connected by piping, and the refrigerant moves as indicated by the outlined arrows.

  The operating principle of the vapor compression refrigeration system is as follows. The pressure and temperature of the refrigerant vapor is increased by the compressor 301, which then enters the radiator 302 where it is cooled. Thereafter, the high-pressure refrigerant is throttled to the evaporating pressure by the expansion valve 303, vaporizes in the evaporator 304, and absorbs heat from the surroundings. Then, the refrigerant vapor returns to the compressor 301 through the outlet of the evaporator 304. For this refrigerant, carbon dioxide that does not destroy the ozone layer and has a very low global warming potential is used.

  However, a vapor compression refrigeration apparatus using carbon dioxide as a refrigerant has a lower coefficient of performance (COP), which is energy efficiency, than refrigeration apparatuses using chlorofluorocarbon as a refrigerant. Furthermore, when considering an equivalent refrigeration capacity, more electric power is required than a refrigeration apparatus using chlorofluorocarbon as a refrigerant. As a result, a lot of fossil fuel is required as energy, so that a large amount of carbon dioxide is discharged as a result even if the global warming potential of the refrigerant itself is small. Therefore, it is necessary to improve the COP of the vapor compression refrigeration system using carbon dioxide as a refrigerant, and various methods have already been proposed.

  As an example of the above proposal, there is a refrigeration apparatus (see Patent Document 1) using a conventional expander shown in FIG. In this refrigeration apparatus, the compressed refrigerant is cooled by the radiator 402 by the compressor 401 driven by the prime mover 405, and then the generator 404 attached to the expander 403 is passed when passing through the expander 403. Generate electricity and generate electricity. The refrigerant expanded in the expander 403 absorbs heat from the outside in the evaporator 406 and vaporizes, and then returns to the compressor 401 again. At this time, based on the information of the pressure sensor 410 and the temperature sensor 411, the power generation amount of the generator 404, that is, the rotation speed of the expander 403 is controlled by the rotation speed control means 412 so that the optimum high pressure value calculated by the calculation means 409 is obtained. Is controlled. Further, an oil separator 407 and an accumulator 408 are installed before and after the compressor 401 in order to improve performance and reliability.

  With the refrigeration system using the expander having such a configuration, electric power is generated by rotating the generator with the force of expansion of the refrigerant, and the total amount of energy used is reduced by effectively using the electric power. It is possible to improve the COP.

  FIG. 19 is a block diagram showing a power recovery apparatus using a conventional expander. In FIG. 19, a DC voltage obtained by rectifying an input from an AC power source 601 into DC by a rectifier circuit 602 is smoothed by a smoothing capacitor 603 and then converted into a three-phase AC voltage by an inverter 604. 606 is driven. The compressor 607 performs a compression function by driving the electric motor 606.

The inverter 604 includes a switching element group 605 for converting a DC voltage into an AC.
Arbitrary alternating current can be output by turning on and off the switching element group 605 so as to realize a predetermined alternating current frequency by a PWM (Pulse Width Modulation) method.

  On the other hand, a variable speed converter 608 for converting three-phase AC power generated by the generator 610 into DC is connected to a generator 610 installed for recovering power by the expander 611. The variable speed converter 608 converts AC power generated by the generator 610 into DC and switches the switching element group 609 formed therein by the PWM method, thereby generating the generator 610 at a given target rotational speed. It has a function to rotate.

  The function of controlling the rotational speed of the generator 610 makes it possible to control the rotational speed of the expander 611 via the generator 610, and thus in the refrigeration cycle apparatus using the expander 611, the expander 611 can be driven at an optimum rotational speed.

The DC output line from the variable speed converter 608 is connected in parallel to a DC power line obtained from the rectifier circuit 602 through the smoothing capacitor 603. As a result, the electric power regenerated from the variable speed converter 608 is consumed by the drive energy of the electric motor 606 via the inverter 604. Accordingly, during normal operation, the motor power Wm consumed by the compressor 607 is greater than the generator power Wg regenerated by the expander 611, so the input power Win from the AC power source 601 is a positive value. It becomes. Here, when the power input from the AC power source 601 through the rectifier circuit 602 is Win, the motor power consumed by the inverter 604 is Wm, and the generator power regenerated by the variable speed converter 608 is Wg, the following formula Holds.
Win = Wm-Wg (1)
In addition, when the system is started, stopped, when the compressor is decelerated, or when the state of the heat exchanger is suddenly changed, there is a period in which the generator power Wg is larger than the motor power Wg. There is a case. In this case, there is a possibility that the voltage of the DC power unit abnormally rises and damages the smoothing capacitor 603 that is a component part. Further, the protection function of the variable speed converter 608 is activated by the rise of the voltage of the DC power section, and the variable speed converter 608 stops the control of the generator 610 so that the expander 611 is free-runned due to the residual pressure of the refrigeration cycle. There was a risk that the machine 611 was destroyed. In order to solve this problem, in Patent Document 2, the power generation efficiency of the A generator is lowered. Reduce the drive efficiency of the B motor. C Store or consume the power supplied to the DC power line. D Increase the motor speed. E Reduce the generator speed. It is described that the voltage rise of the DC power unit is suppressed by performing the above operations.
Japanese Patent Laid-Open No. 2000-241033 International Publication No. 2006/075742 Pamphlet

  However, the refrigeration cycle apparatus using the expander in FIG. 19 has the following problems. When the input side DC voltage of the inverter 604 increases, when the primary side power supply stops, the input side DC voltage decreases, and when the input current to the motor exceeds the overcurrent set value, other protection functions of the inverter 604 work. The inverter 604 stops the driving of the electric motor 606, for example. However, the expander 611 continues to collect the generator power Wg due to the residual pressure of the refrigeration cycle. That is, the electric motor power Wm shown in the equation (1) is zero. The solutions A, B, D, and E shown in Patent Document 2 cannot absorb and consume surplus power in the DC power unit. In Solution C, it is necessary to newly install a regenerative brake resistor and the like, leading to an increase in the number of components.

Therefore, the present invention solves the above-described problem, and when the motor power Wm becomes larger than the collected generator power Wg, for example, even when the driving of the motor 606 is stopped by the protection function of the inverter 604, the present invention is newly A refrigerating cycle that uses a highly reliable expander without a regenerative brake resistor, etc., but even if it is installed, the regenerative brake resistor can be reduced in size and a system that does not destroy components is realized. An object is to provide an apparatus.

In order to solve the above problems, a refrigeration cycle apparatus of the present invention includes a compressor that compresses a working fluid,
A radiator for cooling the refrigerant compressed by the compressor;
An expander that expands the refrigerant that has passed through the radiator;
An evaporator for evaporating the refrigerant expanded by the expander;
A refrigerant pipe for sequentially connecting the compressor, the radiator, the expander, and the evaporator, and circulating the refrigerant;
A blower fan for blowing air to at least one of the radiator and the evaporator;
A generator that is connected to the expander and generates AC power according to the rotation of the expander;
A variable speed converter that controls the drive of the generator and outputs the DC power by converting the AC generator power output by the generator;
An electric motor connected to the compressor;
An inverter that converts a DC voltage into an AC voltage having a predetermined frequency and controls the driving of the motor;
Fan rotation speed control for controlling to increase the rotation speed of the blower fan when the generator power output from the generator exceeds the motor power input to the motor and surplus power is generated in the DC voltage unit Means are provided.

  With this configuration, even if surplus power is generated in the DC power section on the input side of the inverter, the surplus power is consumed by the blower fan by increasing the rotation speed of the blower fan, and the voltage of the DC power section is increased. Does not fluctuate more than a predetermined voltage, and there is no destruction of the component parts, and the reliability can be improved.

  Further, the refrigeration cycle apparatus may be configured such that the blower fan is provided on the evaporator side and promotes heat exchange with air.

  Thereby, in a heat pump water heater, the evaporator which is an air heat exchanger will be installed in the outdoor side, and can be installed close to a compressor and an expander.

  Furthermore, the refrigeration cycle apparatus of the present invention includes voltage detection means connected in parallel to the DC voltage unit that is the input terminal of the inverter, and when the voltage information obtained by the voltage detection means exceeds a set value. You may control to increase the rotation speed of the said ventilation fan.

  Thereby, by using the voltage detection means for detecting the voltage in the DC voltage section, it is possible to detect surplus power as an increase in voltage and consume surplus power by increasing the number of rotations of the blower fan. Therefore, the rise of the DC voltage section voltage can be suppressed and the reliability of the component equipment can be increased.

  In addition, the refrigeration cycle apparatus includes voltage detection means connected in parallel to the DC voltage unit that is an input terminal of the inverter, and when the voltage information obtained by the voltage detection means falls below a certain set value, You may control to increase the rotation speed of the fan.

As a result, when the primary power supply voltage, which is the input power, is detected by the voltage detection means, the surplus power can be reduced by increasing the rotational speed of the blower fan when the inverter stops driving the motor. Since it can be consumed, it is possible to suppress an increase in the voltage of the DC voltage section and increase the reliability of the constituent devices.

  The refrigeration cycle apparatus includes a shunt resistor connected to the DC voltage unit N bus line that is an input terminal of the inverter, and there is a current information obtained by detecting a voltage across the shunt resistor. It may be controlled to increase the number of rotations of the blower fan when the value exceeds the value.

  As a result, when the current detecting means detects that the motor input current has risen above a certain set value, excess power is consumed by increasing the rotational speed of the blower fan when the inverter stops driving the motor. Therefore, it is possible to suppress an increase in the DC voltage section voltage and increase the reliability of the constituent devices.

  Further, the refrigeration cycle apparatus includes a temperature detection unit in the refrigerant pipe between the compressor and the radiator, and when the temperature information obtained by the temperature detection unit exceeds a set value, the rotation of the blower fan You may control to increase a number.

  Thus, when the temperature detecting means detects that the temperature of the refrigerant pipe between the compressor and the radiator has risen above a certain set value, the rotation speed of the blower fan when the inverter stops driving the motor By increasing the power consumption, surplus power can be consumed, so that an increase in the DC voltage section voltage can be suppressed and the reliability of the component equipment can be increased.

  The refrigeration cycle apparatus may be controlled to increase the rotational speed of the blower fan by outputting an inverter protection signal generated by the inverter.

  As a result, when the inverter protection signal is output and the inverter stops driving the electric motor, surplus power can be consumed by increasing the rotational speed of the blower fan. The reliability of the component equipment can be increased.

  According to the refrigeration cycle apparatus using the expander of the present invention, when the inverter protection function is activated due to a decrease in the primary side input power supply voltage or an overcurrent, and the driving of the motor is forcibly stopped, the motor input power is reduced. The increase in the voltage of the DC power unit itself caused by surplus power collected by the generator because it becomes zero can be avoided by consuming surplus power by increasing the rotation speed of the blower fan. Since there is no shutdown of the variable speed converter that occurs due to exceeding the voltage limit value of the DC power unit, it is possible to guarantee a stable operation at all times and realize a highly reliable system without destruction of components. .

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram showing a refrigeration cycle apparatus according to a first embodiment of the present invention.

The refrigeration cycle apparatus according to this embodiment includes a compressor 501 that compresses refrigerant, a radiator 502 that cools the refrigerant compressed by the compressor 501, an expander 503 that expands the refrigerant that has passed through the radiator 502, and an expansion. An evaporator 504 that evaporates the refrigerant expanded by the machine 503, a refrigerant pipe 518 that circulates the refrigerant between the above-described element devices, and a permanent magnet type synchronous generator 507 (hereinafter referred to as a generator 507) connected to the expander 503. ) And a variable speed converter 508 having a function of converting the AC power output from the generator 507 to output DC power and controlling the driving of the generator 507. The function of controlling the drive of the generator 507 is, for example, controlling the rotational speed or current value of the generator 507 to a predetermined value.

  As will be described later, the variable speed converter 508 has a function of driving and controlling the generator 507 by the variable speed converter 508 so that the refrigeration cycle has an optimum efficiency pressure.

  Furthermore, the refrigeration cycle apparatus according to the present embodiment converts an electric motor 505 (in this case, using an IPMSM (Interior Permanent Magnet Synchronous Motor)) that drives a compressor 501, a direct current into an alternating current of a predetermined frequency, and the rotation of the electric motor 505. Inverter device 506 (hereinafter referred to as inverter 506) for controlling the number or current value to a predetermined value, expander rotation speed determining means 509, temperature sensor 516 for detecting the outlet temperature of radiator 502, and outlet of radiator 502 A pressure sensor 517 that detects pressure, a blower fan 522 that is connected to the DC power unit and blows air to the evaporator, and a fan rotation speed control unit 521 that controls the rotation speed of the blower fan 522 are provided.

  Further, a DC power unit as a part of the control circuit is provided with a converter including a rectifier circuit 511 and a smoothing capacitor 512. This converter converts the alternating current input from the alternating current power supply 510 into a direct current by the rectifier circuit 511 and smoothes the voltage by the smoothing capacitor 512. That is, the DC power unit connects the DC output of the variable speed converter 508 to the DC output terminal of the converter and the DC input terminal of the inverter 506, supplies power from the AC power supply 510 and the generator 507 to the inverter 506, and the expander The electric power obtained by the expansion force at 503 can be used as the driving force of the compressor 501.

  Further, the DC power unit is provided with a voltage detection sensor 520 for detecting the voltage of the DC power unit (hereinafter referred to as DC voltage).

  The operation of the refrigeration cycle of the refrigeration cycle apparatus will be described.

  In FIG. 1, a compressor 501 is driven by an electric motor 505 controlled by an inverter 506, and the refrigerant is compressed by the compressor 501. The compressed refrigerant is cooled by the radiator 502 and then passes through the expander 503 connected to the generator 507 controlled by the variable speed converter 508. At this time, the refrigerant expands in the expander 503, absorbs heat from the outside in the evaporator 504 and vaporizes, and then returns to the compressor 501 again.

  Next, the operation of the control circuit of the refrigeration cycle apparatus will be described.

  In FIG. 1, the DC power obtained by rectifying the AC power supply 510 with the rectifier circuit 511 is smoothed by the smoothing capacitor 512, and then converted into three-phase AC power by the inverter 506. To be supplied. Thereby, the electric motor 505 is driven and the compressor 501 performs the compression function.

  Further, the torque of the expander 503 generated by the expansion force of the refrigerant becomes the rotational force of the generator 507, and power is generated. The AC power generated by the generator 507 is converted into DC power by the variable speed converter 508 and then supplied to both ends of the smoothing capacitor 512. Thereby, the electric power generated by the expander 503 is used as auxiliary power for driving the motor of the compressor 501.

Here, the rotational speeds of the expander 503 and the generator 507 are controlled by the variable speed converter 508. Further, the rotation speeds of the compressor 501 and the electric motor 505 are controlled by an inverter 506. The variable speed converter 508 is given a target rotational speed from the expander rotational speed determining means 509. The expander rotation speed determining means 509 determines the optimum expander rotation speed of the target rotation speed based on the value of the radiator outlet temperature from the temperature sensor 516 and the value of the radiator outlet pressure from the pressure sensor 517.

  The optimum expander rotational speed is determined by data of the efficiency of the refrigeration cycle with respect to the radiator outlet pressure and the radiator outlet temperature shown in FIG. As shown in this figure, the efficiency of the refrigeration cycle of this refrigeration cycle apparatus differs in that it becomes the maximum depending on the outlet pressure and temperature of the radiator 502, and the line connecting the maximum points is the optimum efficiency pressure line in the figure. is there. By measuring the radiator outlet temperature using this pressure line, the optimum pressure is obtained as the radiator outlet pressure at that time.

  Next, the operation of the expander rotation speed determination means 509 will be described.

  FIG. 3 is a flowchart for determining the expander rotation speed in the refrigeration cycle apparatus of the present embodiment, and shows a procedure for determining the optimum value of the expander rotation speed that maximizes the cycle efficiency in the expander rotation speed determination means 509.

  First, in step 101, the values of the measured radiator outlet pressure and temperature are input. Then, the optimum pressure value that maximizes the efficiency is calculated in accordance with the optimum pressure data shown in FIG. 2 (step 102). Next, it is determined in step 103 whether the measured current outlet pressure is greater than the optimum pressure. If the outlet pressure is larger than the optimum pressure, the target rotational speed of the expander 503 is increased so as to lower the outlet pressure (step 104). That is, the expander rotation speed determination means 509 outputs the target rotation speed for decreasing the outlet pressure to the variable speed converter 508. Thereby, the pressure difference between the inlet and the outlet in the expander 503 is reduced, and as a result, the high pressure in the refrigeration cycle is lowered (step 105).

  If the outlet pressure is lower than the optimum pressure, the target rotational speed of the expander 503 is decreased so as to increase the outlet pressure (step 106). That is, the expander rotational speed determination means 509 outputs a target rotational speed for increasing the outlet pressure to the variable speed converter 508. As a result, the pressure difference between the inlet and outlet of the expander increases, and as a result, the high pressure in the refrigeration cycle increases (step 107). With these controls, the pressure at the radiator outlet is controlled to maximize the efficiency of the refrigeration cycle. As described above, since the coefficient of performance (COP) can be increased in the refrigeration cycle apparatus of the present embodiment, carbon dioxide having a small global warming potential can be used as the refrigerant.

  In FIG. 1, the blower fan 522 installed in the evaporator 504 is connected in parallel with the DC voltage unit, and promotes heat exchange between the refrigerant and the air inside the evaporator 504. Further, the rotational speed of the blower fan 522 is controlled by the fan rotational speed control means 521. Next, the operation of the fan rotation speed control means 521 during normal operation will be described. As disclosed in Japanese Patent Application Laid-Open No. 2003-161545 (heat pump type hot water supply device: Daikin Industries, Ltd.), the rotational speed of the fan rotational speed control means 521 is determined in accordance with the rotational frequency of the compressor 501 obtained from the inverter 506. (Table 1). For example, when the frequency of the compressor 501 is 86 Hz, the fan rotation speed of the blower fan 522 of the evaporator 504 is 550 rpm, when the frequency of the compressor 501 is 74 Hz, the fan rotation speed is 500 rpm, and the frequency of the compressor 501 is The fan rotation speed is 500 rpm when the frequency is 58 Hz, the fan rotation speed is 500 rpm when the frequency of the compressor 501 is 44 Hz, and the fan rotation speed is 450 rpm when the frequency of the compressor 501 is 40 Hz.

  Next, the operation in which the fan rotation speed control means 521 important in the present invention controls the voltage of the DC power unit will be described in detail. FIG. 4 is a diagram for explaining the operation of the fan speed control means 521 in the method for controlling the voltage unit of the DC power unit according to the present configuration. When the voltage of the DC power unit is 280 V (reference value) +20 V = 300 V or less, the fan rotation speed control means 521 controls the blower fan 522 to have a predetermined rotation speed as shown in Table 1. However, a generator directly connected to the expander 503 rather than the motor power Wm due to a rapid decrease in the motor power Wm to the motor 505 directly connected to the compressor 501 at the time of emergency stop of the compressor 501 or transition of the refrigeration cycle. The generator power Wg of 507 may be larger (Wm <Wg). As an example of this, FIG. 4 illustrates a case where the compressor 501 has stopped in an emergency. When the compressor 501 stops, the motor power Wm to the motor 505 suddenly becomes zero (Wm = 0), the generator power Wg recovered by the generator 507 becomes surplus power in the DC power unit, and the voltage of the DC power unit Vdc begins to rise rapidly. At this time, when the voltage Vdc of the DC power unit obtained by the voltage detection sensor 520 exceeds 300 V, the fan rotation speed control means 521 instructs the fan fan 522 to increase the rotation speed, and surplus power in the DC power unit. Minutes can be consumed by the blower fan 522. As a result, the voltage Vdc of the DC power unit can be kept within a predetermined range. Thereafter, since the differential pressure between the high pressure side and the low pressure side remaining in the refrigeration cycle is gradually equalized by the expander 503, the generator power Wg of the expander converges to zero.

  FIG. 5 is a flowchart of the fan rotation speed control means 521 by the above control, and shows a control procedure for suppressing the voltage Vdc of the DC power unit within a predetermined range. First, in step 201, the voltage detection sensor 520 detects the current voltage Vdc of the DC power unit, and determines whether it is equal to or less than the above-described voltage limit value of 300V (step 202). If the result determined in step 202 is 300 V or less, the current frequency of the compressor 501 is read (step 203), the number of rotations of the blower fan 522 is determined according to Table 1 (step 204), and the blower fan 522 is designated. (Step 205). Further, when the voltage Vdc of the DC power unit detected in step 202 exceeds 300 V, control is performed so as to increase the rotational speed of the blower fan 522 in step 206. Thus, even when the generator power Wg recovered by the generator 507 directly connected to the expander 503 is larger than the motor power Wm to the motor 505, the surplus power is reliably consumed by the blower fan 522. Since the voltage Vdc of the DC power unit can be controlled within a predetermined range, the safety and reliability of the device are dramatically improved.

  Although specific embodiments of the present invention have been described above, the present invention is not limited to the above embodiments.

  Here, although the control is performed so that the efficiency of the refrigeration cycle is optimized, the temperature is determined by temperature information of a temperature sensor (not shown) attached to the refrigerant pipe 518 between the compressor 501 and the radiator 502. The rotational speed of the expander 503 may be determined so that is constant.

  Further, the voltage limit value (300 V) in the fan rotation speed control means 521 used in the above embodiment was set to a value lower than the upper limit value Vmax of the DC voltage, which is a protection function that the inverter 506 originally has, The limit value of the voltage in the fan rotation speed control means 521 and the upper limit value Vmax of the DC voltage, which is a protection function that the inverter 506 originally has, may be set to the same value. Here, the upper limit value Vmax of the DC voltage is a threshold voltage at which the driving of the inverter 506 is stopped for the purpose of protecting the inverter 506 when the voltage of the DC power unit exceeds the upper limit value Vmax. FIG. 6 is a diagram for explaining the operation of the fan rotation speed control means 521 when the voltage limit value in the fan rotation speed control means 521 and the upper limit value Vmax of the DC voltage of the inverter 506 are set to the same value. It is. As a result, the fan rotational speed control means 521 controls the rotational speed of the blower fan 522 to increase at the same time as the inverter 506 stops, so that the surplus power can be reliably consumed by the blower fan 522.

  Moreover, you may control so that the rotation speed of the said fan for ventilation may be increased with the output of the said inverter protection signal produced | generated by the inverter.

(Second Embodiment)
Hereinafter, a second embodiment of the refrigeration cycle apparatus using the expander of the present invention will be described.

  The configuration of the second embodiment is the same as the block configuration diagram of the first embodiment shown in FIG. 1, but only the operation of the fan rotation speed control means 521 is different from that of the first embodiment.

  FIG. 7 is a diagram for explaining the operation of the fan speed control means 521 in the method for controlling the voltage unit of the DC power unit according to this embodiment. Originally, the inverter 506 sets the lower limit value Vmin of the voltage of the DC power unit. That is, when the voltage of the DC power unit becomes equal to or lower than Vmin, the inverter 506 stops its operation for the purpose of protecting the inverter 506. The operation of the fan rotation speed control means 521 will be described below. When the voltage of the DC power unit is equal to or higher than Vmin, the fan rotation speed control means 521 controls the blower fan 522 so as to have a predetermined rotation speed as shown in Table 1 as in the first embodiment. Yes. However, the inverter 506 stops its operation when the voltage of the DC power section drops due to an instantaneous stop of the primary side input power source or the like and becomes lower than Vmin. As a result, the electric motor power Wm to the electric motor 505 directly connected to 501 becomes zero, and the generator electric power Wg recovered by the electric generator 507 directly connected to the expander 503 is more than the electric motor electric power Wm as in the first embodiment. Becomes larger (Wm <Wg). At this time, as shown in FIG. 11, when the voltage of the DC power unit falls below Vmin, the fan rotation speed control means 521 controls to increase the rotation speed of the blower fan 522, and the surplus power is reduced by the blower fan 522. Consume. This makes it possible to keep the voltage of the DC power unit within a predetermined range. Thereafter, since the differential pressure between the high pressure side and the low pressure side in the refrigeration cycle is equalized by the expander, the generator power Wg of the expander converges to zero. FIG. 8 is a flowchart of the fan rotation speed control means 521 by the above control, and shows a control procedure for suppressing the voltage of the DC power unit within a predetermined range.

First, in step 301, the voltage detection sensor 520 detects the current voltage Vdc of the DC power unit, and determines whether it is equal to or higher than the above-described lower limit value Vmin of the DC voltage (step 302). If the result determined in step 302 is equal to or higher than Vmin, the current frequency of the compressor 501 is read (step 303), the number of rotations of the blower fan 522 is determined from table 1 (step 304), and the blower fan 522 is designated. (Step 305). Further, when the voltage Vdc of the DC power unit is equal to or lower than the lower limit value Vmin of the DC voltage at step 303, control is performed to increase the rotational speed of the blower fan 522 at step 306. Thus, even when the generator power Wg of the generator 507 directly connected to the expander 503 is larger than the motor power Wm to the motor 505, the surplus power is surely consumed by the blower fan 522, and the DC power Since the voltage of the unit can be controlled within a predetermined range, the safety and reliability of the device are greatly improved.

  Although specific embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. For example, although the DC voltage lower limit value in the fan rotation speed control means 521 used in this embodiment is set to be the same as the DC voltage lower limit value Vmin, which is a protection function that the inverter 506 originally has, The DC voltage lower limit value in the fan rotation speed control means 521 may be set different from the DC voltage lower limit value Vmin which is a protection function inherent to the inverter 506. For example, by setting the lower limit value of the DC voltage in the fan rotation speed control means 521 to be larger than the lower limit value Vmin of the DC voltage, which is a protection function inherent to the inverter 506, before the inverter 506 stops. The fan rotational speed control means 521 can control the rotational speed of the blower fan 522 to increase.

  Moreover, you may control so that the rotation speed of the said fan for ventilation may be increased with the output of the said inverter protection signal produced | generated by the inverter.

(Third embodiment)
Hereinafter, a third embodiment of the refrigeration cycle apparatus using the expander of the present invention will be described.

  FIG. 9 is a block diagram showing the refrigeration cycle apparatus according to the first embodiment of the present invention.

  The configuration of the third embodiment is almost the same as the block configuration diagram of the first embodiment shown in FIG. 1, but the input information to the fan rotation speed control means 521 is not the DC voltage of the DC power unit. Thus, the portion of the inverter current value flowing through the inverter 506 is different from that of the first embodiment. Other operations are the same as those in the first embodiment of the present invention.

  FIG. 10 is a configuration diagram of the inverter 506 of FIG. 7 in the third embodiment according to the present invention.

  The inverter 506 includes an electric motor 505, a driving unit 104, two current sensors 105a and 105b, a biaxial current conversion unit 106, a rotor position rotational speed estimation unit 107, a sine wave voltage output unit 109, a current control unit 110, a current The electronic circuit is composed of a command creating unit 111 and a rotation speed control unit 112. The electric motor 505 generates a current command (torque command) by the rotation speed control means 112 based on the information on the target rotation speed given from the outside, and outputs a current command (iγ *, iδ *) in the γδ axis by the current command generation means 111. create. According to the γδ axis current (iγ, iδ) obtained by converting the phase currents Iu and Iv obtained by the current sensors 105a and 105b into the γδ coordinate by the biaxial current conversion means 106 and the current command (iγ *, iδ *) on the γδ axis. The current control means 110 creates voltage commands (vγ *, vδ *). The three-phase AC input to the electric motor 505 is based on the voltage commands vγ and vδ created by the current control means 110, the sine wave voltage means 109 determines the output duty, and the driving means 104 determines the voltage based on the output duty. Is output to the electric motor 505. In this way, the electric motor 505 is controlled so that the rotational speed becomes the target rotational speed.

FIG. 11 is a block diagram of the driving means 104 of the control device of the electric motor 505 shown in FIG. This driving means 104 includes a conversion circuit in which switching elements 113a, 113b, 113c, 113d, 113e, 113f and free-wheeling diodes 114a, 114b, 114c, 114d, 114e, 114f are paired, a base driver 116, a smoothing capacitor 117, A DC power supply 118 and a shunt resistor 120 are included. The three-phase AC motor input of the driving means 104 is connected to be supplied from, for example, the DC power supply 118 side via a switching element. Here, the DC power supply 118 corresponds to an output rectified by a diode bridge or the like. The switching pattern signal created by the sine wave voltage output means 109 is converted into a drive signal for electrically driving the switching elements 113a to 113f by the base driver 116, and each of the switching elements 113a to 113f is according to these drive signals. Is configured to operate. Further, the shunt voltage detected at both ends of the shunt resistor 120 is connected to the fan rotation speed control means 521.

  FIG. 12 is a diagram for explaining the operation of the fan rotation speed control means 521 in the method for controlling the voltage unit of the DC power unit according to this embodiment. The fan rotation speed control means 521 calculates the inverter current Iinv flowing through the inverter 506 sequentially from the shunt voltage applied to the shunt resistor 120 using the relationship of V = I × R. Originally, the inverter 506 sets the upper limit value Imax of the inverter current Iinv in order to prevent the current from flowing excessively. That is, when a current greater than or equal to the upper limit value Imax of the inverter current Iinv flows to the inverter 506, the inverter 506 stops its operation. Hereinafter, the operation of the fan rotation speed control means 521 will be described in detail. When the inverter current Iinv is equal to or less than Imax, the fan rotation speed control means 521 controls the blower fan 522 so as to have a predetermined rotation speed as shown in Table 1, as in the first embodiment. . However, when an excessive inverter current Iinv flows and becomes larger than the upper limit value Imax of the inverter current Iinv when the refrigeration cycle is overloaded, the inverter 506 stops its operation. As a result, the motor power Wm to the motor 505 directly connected to the motor 501 becomes zero, and the generator power Wg of the generator 507 directly connected to the expander 503 is larger than the motor power Wm as in the first embodiment. (Wm <Wg). At this time, as shown in FIG. 12, when the inverter current Iinv exceeds the upper limit value Imax of the inverter current Iinv, the fan rotation speed control means 521 controls the rotation speed of the blower fan 522 to be increased. The surplus power is consumed. This makes it possible to keep the voltage of the DC power unit within a predetermined range. Thereafter, since the differential pressure between the high pressure side and the low pressure side in the refrigeration cycle is equalized by the expander, the generator power Wg of the expander converges to zero. FIG. 13 is a flowchart of the fan rotation speed control means 521 by the above control, and shows a control procedure for suppressing the voltage of the DC power unit within a predetermined range.

  First, in step 401, the fan rotation speed control means 521 detects the inverter current Iinv from the current shunt voltage, and determines whether it is equal to or lower than the upper limit value Imax of the inverter current Iinv (step 402). If the result determined in step 402 is equal to or less than Imax, the current frequency of the compressor 501 is read (step 403), the number of rotations of the blower fan 522 is determined from table 1 (step 404), and the blower fan 522 is designated. (Step 405). When the inverter current Iinv exceeds Imax in step 402, control is performed so that the rotational speed of the blower fan 522 is increased in step 406. Thus, even when the generator power Wg of the generator 507 directly connected to the expander 503 is larger than the motor power Wm to the motor 505, the surplus power is surely consumed by the blower fan 522, and the DC power Since the voltage of the unit can be controlled within a predetermined range, the safety and reliability of the device are greatly improved.

  Although specific embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. Although the upper limit value of the current in the fan rotation speed control means 521 used in this embodiment is the same value as the upper limit value Imax of the current which is a protection function inherent to the inverter 506, it may be set differently. Good. For example, by setting the upper limit value of the current in the fan rotation speed control means 521 smaller than the upper limit value Imax of the inverter 506, the fan rotation speed control means 521 causes the rotation speed of the blower fan 522 before the inverter 506 stops. Can be controlled to rise.

  Moreover, you may control so that the rotation speed of the said fan for ventilation may be increased with the output of the said inverter protection signal produced | generated by the inverter.

(Fourth embodiment)
Hereinafter, a fourth embodiment of the refrigeration cycle apparatus using the expander of the present invention will be described.

  FIG. 14 is a block diagram showing a refrigeration cycle apparatus according to a fourth embodiment of the present invention.

  The configuration of the fourth embodiment is almost the same as the block configuration diagram of the first embodiment shown in FIG. 1, but a discharge temperature sensor 523 is installed between the compressor 501 and the radiator 502, and the fan The input information to the rotation speed control means 521 is not the DC voltage of the DC power unit, but is a part obtained by the temperature obtained by the discharge temperature sensor 523, which is different from the first embodiment.

FIG. 15 is a diagram for explaining the operation of the fan speed control means 521 in the method for controlling the voltage unit of the DC power unit according to this embodiment. The fan rotation speed control means 521 acquires the discharge temperature from the discharge temperature sensor 523. Originally, the inverter 506 sets a limit value Tmax for the discharge temperature Tout in order to prevent the discharge temperature Tout from becoming excessive. That is, when it becomes Tmax or more, the inverter 506 stops its operation. The operation of the fan rotation speed control means 521 will be described below. When the discharge temperature Tout is equal to or lower than Tmax, the fan rotation speed control means 521 controls the blower fan 522 so as to have a predetermined rotation speed as shown in Table 1, as in the first embodiment. . However, the inverter 506 stops its operation when the discharge temperature Tout becomes high and becomes higher than Tmax at the end of boiling or when the incoming water temperature is high. As a result, the motor power Wm to the motor 505 directly connected to the motor 501 becomes zero, and the generator power Wg of the generator 507 directly connected to the expander 503 is larger than the motor power Wm as in the first embodiment. (Wm <Wg). At this time,
As shown in FIG. 14, when the discharge temperature Tout exceeds Tmax, the fan rotation speed control means 521 controls the rotation speed of the blower fan 522 to increase, and the blower fan 522 consumes the surplus power. This makes it possible to keep the voltage of the DC power unit within a predetermined range. Thereafter, since the differential pressure between the high pressure side and the low pressure side in the refrigeration cycle is equalized by the expander, the generator power Wg of the expander converges to zero. FIG. 15 is a flowchart of the fan rotation speed control means 521 based on the above control, and shows a control procedure for suppressing the voltage of the DC power unit within a predetermined range.

  First, in step 501, the discharge temperature Tout is detected by the current discharge temperature sensor 523, and it is determined whether it is within Tmax which is the discharge temperature limit value described above (step 502). If the result determined in step 502 is within Tmax, the current frequency of the compressor 501 is read (step 503), the rotational speed of the blower fan 522 is determined from Table 1 (step 504), and the blower fan 522 is designated. (Step 505). If the discharge temperature Tout exceeds Tmax in step 502, control is performed so that the rotational speed of the blower fan 522 is increased in step 506. Thus, even when the generator power Wg of the generator 507 directly connected to the expander 503 is larger than the motor power Wm to the motor 505, the surplus power is surely consumed by the blower fan 522, and the DC power Since the voltage of the unit can be controlled within a predetermined range, the safety and reliability of the device are greatly improved.

  Although specific embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. The discharge temperature limit value Tmax in the fan rotation speed control means 521 used in this embodiment is the same value as the upper limit value of the discharge temperature, which is a protection function inherent in the inverter 506, but the upper limit temperature Tmax of the discharge temperature. May be set differently. For example, by setting the fan air volume rotational speed means 509 smaller than the discharge temperature limit value Tmax, the fan rotational speed control means 521 increases the rotational speed of the blower fan 522 before the inverter 506 stops. You may control.

  Although specific embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. The upper limit value of the discharge temperature in the fan rotation speed control means 521 used in this embodiment is the same value as the upper limit value Tmax of the discharge temperature, which is a protection function inherent to the inverter 506, but is set differently. May be. For example, by setting the upper limit value of the discharge temperature in the fan rotation speed control means 521 to be smaller than the discharge temperature limit value Tmax of the inverter 506, the fan rotation speed control means 521 allows the fan rotation speed of the blower fan 522 before the inverter 506 stops. It can be controlled to increase the rotational speed.

  Moreover, you may control so that the rotation speed of the said fan for ventilation may be increased with the output of the said inverter protection signal produced | generated by the inverter.

  As described above, the refrigeration cycle apparatus using the expander according to the present invention has an effect of improving reliability without destruction of components, and is useful for a heat pump refrigeration apparatus such as an air conditioner or a water heater.

The block block diagram which shows the refrigerating-cycle apparatus of 1st Embodiment by this invention. The figure which shows an example of the efficiency of the refrigerating cycle with respect to radiator outlet pressure and temperature Flowchart of expansion machine rotation speed determination in the refrigeration cycle apparatus of the first embodiment Characteristic diagram showing transition of voltage Vdc of DC power section and FAN rotation speed in refrigeration cycle apparatus of first embodiment Flowchart of fan rotation speed control means 521 in the refrigeration cycle apparatus of the first embodiment. The characteristic view showing transition of the voltage of a direct-current power part and FAN rotation speed when Vmax = 300V in the refrigerating cycle device of a 1st embodiment Characteristic diagram showing transition of voltage Vdc of DC power section and FAN rotation speed in refrigeration cycle apparatus of second embodiment Flowchart of fan rotation speed control means 521 in the refrigeration cycle apparatus of the second embodiment. The block block diagram which shows the refrigerating-cycle apparatus of 3rd Embodiment by this invention. The block diagram of the inverter 506 in the refrigerating-cycle apparatus of 3rd Embodiment. The block diagram of the drive means 104 of the control apparatus of the electric motor 505 in the refrigerating-cycle apparatus of 3rd Embodiment. The characteristic view showing change of inverter current Iinv and FAN rotation speed in the refrigerating cycle device of a 3rd embodiment Flowchart of fan rotation speed control means 521 in the refrigeration cycle apparatus of the third embodiment. The block block diagram which shows the refrigerating-cycle apparatus of 4th Embodiment by this invention. The characteristic diagram showing change of discharge temperature Tout and FAN rotation speed in the refrigerating cycle device of a 4th embodiment Flowchart of fan rotation speed control means 521 in the refrigeration cycle apparatus of the fourth embodiment. Configuration diagram of a general refrigeration cycle system using an expansion valve Configuration diagram of a general refrigeration cycle system using an expander Block diagram showing a power recovery device using an expander

Explanation of symbols

104 Driving means 105a, 105b Current sensor 106 Two-axis current conversion means 107 Rotor position / rotor speed estimation means 109 Sine wave voltage output means 110 Current control means 111 Current command generation means 112 Rotation speed control means 501 Compressor 502 Radiator 503 Expander 504 Evaporator 505 Electric motor 506 Inverter 507 Generator 508 Variable speed converter 509 Expander rotation speed determining means 510 AC power supply 511 Rectifier circuit 512 Smoothing capacitor 513 Switching element 514 Load resistance 515 Voltage processing means 516 Temperature sensor 517 Pressure sensor 518 Refrigerant piping 520 Voltage detection sensor 521 Fan rotation speed control means 522 Blower fan 523 Discharge temperature sensor 803a-803f Switching element 804a-804f Reflux diode 80 5a, 805b Current sensor 806 Biaxial current conversion means 807 Rotor position rotation speed estimation means 808 Base driver 809 Sine wave voltage output means 810 Current control means 811 Current command creation means 812 Rotation speed control means

Claims (7)

A compressor for compressing the working fluid;
A radiator for cooling the refrigerant compressed by the compressor;
An expander that expands the refrigerant that has passed through the radiator;
An evaporator for evaporating the refrigerant expanded by the expander;
A refrigerant pipe for sequentially connecting the compressor, the radiator, the expander, and the evaporator, and circulating the refrigerant;
A blower fan for blowing air to at least one of the radiator and the evaporator;
A generator that is connected to the expander and generates AC power according to the rotation of the expander;
A variable speed converter that converts the AC generator power output by the generator to output DC power and controls the driving of the generator;
An electric motor connected to the compressor;
An inverter that converts a DC voltage into an AC voltage having a predetermined frequency and controls the driving of the motor;
Fan rotational speed control for controlling the rotational speed of the blower fan to increase when the generator power output by the generator exceeds the motor power input to the motor and surplus power is generated in the DC voltage unit Refrigeration cycle apparatus having means   The refrigeration cycle apparatus according to claim 1, wherein the refrigeration cycle apparatus is provided with the blower fan on the evaporator side to promote heat exchange with air.   The refrigeration cycle apparatus includes voltage detection means connected in parallel to the DC voltage unit, which is an input terminal of the inverter, and the fan for blowing air when the voltage information obtained by the voltage detection means exceeds a set value. The refrigeration cycle apparatus according to any one of claims 1 to 2, wherein the refrigeration cycle apparatus is controlled so as to increase a rotation speed of the refrigeration.   The refrigeration cycle apparatus includes voltage detection means connected in parallel to the DC voltage unit, which is an input terminal of the inverter, and the fan for blowing when the voltage information obtained by the voltage detection means falls below a set value. The refrigeration cycle apparatus according to any one of claims 1 to 2, wherein the refrigeration cycle apparatus is controlled so as to increase a rotation speed of the refrigeration.   The refrigeration cycle apparatus includes a shunt resistor connected to the DC voltage unit N bus line that is an input end of the inverter, and current information obtained by detecting a voltage across the shunt resistor is greater than a certain set value. The refrigeration cycle apparatus according to any one of claims 1 to 2, wherein the refrigeration cycle device is controlled so as to increase a rotational speed of the blower fan.   The refrigeration cycle apparatus includes a temperature detection unit in the refrigerant pipe between the compressor and the radiator, and when the temperature information obtained by the temperature detection unit exceeds a set value, the rotation speed of the blower fan is set. The refrigeration cycle apparatus according to any one of claims 1 to 2, wherein the refrigeration cycle apparatus is controlled to increase.   The refrigeration cycle apparatus according to any one of claims 1 and 2, wherein the refrigeration cycle apparatus controls the rotation speed of the blower fan to be increased by an output of an inverter protection signal generated by the inverter.

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