JP5211006B2 - Refrigeration cycle equipment - Google Patents

Description

  The present invention relates to a refrigeration cycle apparatus that includes a compressor that is driven by being supplied with electric power from an AC power supply, and that has a refrigeration capacity that is variable by controlling the frequency of the compressor.

  As an inverter control device that controls a compressor that constitutes a conventional refrigeration cycle, for example, in an inverter control device that variably controls the frequency of a motor according to a load, a rotational speed detection means that detects the rotational speed of the motor, A controller for controlling the operating frequency based on a comparison between an output duty corresponding to the operating rotational speed detected by the number detecting means and a reference duty corresponding to the target rotational speed of the motor. Discloses a technique for obtaining a regulation duty corresponding to the target rotational speed when the engine speed is smaller than the target rotational speed, and executing a motor overload reduction process when the output duty is equal to or greater than the regulation duty.

JP 2009-17690 A

  By the way, in such a refrigeration cycle apparatus, when generating a command frequency after performing an overload protection operation, a new command frequency is generated based on the protection frequency generated for the overload protection operation. The new command frequency becomes a relatively small value, and there is a problem that it takes time to recover the frequency required for the required refrigeration capacity.

  Therefore, an object of the present invention is to provide a refrigeration cycle apparatus capable of minimizing temperature fluctuations of the refrigeration cycle when the compressor is decelerated when an overload is detected.

  The present invention includes a compressor that is driven by power supplied from an AC power source, and a refrigeration cycle apparatus configured to variably have a refrigeration capacity by controlling the frequency of the compressor. A required frequency generating unit that generates a required frequency of the compressor based on the above, an overload protection control unit that outputs a frequency-related command to perform an overload protection operation when the load of the compressor is greater than a predetermined value, A final target command frequency is determined based on the output from the overload protection control unit and the necessary frequency generated by the necessary frequency generation unit, and the frequency of the compressor is gradually changed to the final target command frequency. A plurality of intermediate target command frequencies to be generated step by step, and a frequency control execution unit that outputs the intermediate target command frequencies to a necessary frequency generation unit, the target frequency generation unit Determining the magnitude relationship between the current required frequency and the intermediate target command frequency input from the frequency control execution unit, and determining the change direction of the required frequency based on the required refrigeration capacity and the current refrigeration capacity When the current required frequency is the same as, greater than or greater than the intermediate target command frequency input from the frequency control execution unit, and the change direction of the necessary frequency is an increasing direction, Whether to increase the required frequency based on the presence or absence of an overload protection operation is determined.

  According to the present invention, the temperature fluctuation of the refrigeration cycle when the compressor is decelerated when an overload is detected can be minimized.

It is a control block diagram of the refrigerating cycle device concerning one embodiment of the present invention. It is a flowchart of the required frequency production | generation process of the refrigeration cycle apparatus which concerns on the same embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram schematically showing a control device for a refrigeration cycle apparatus according to the present invention. For example, this control device is provided in a refrigeration cycle device such as a heat pump type water heater (not shown).

  This refrigeration cycle apparatus includes a compressor that is driven by receiving power from an AC power supply, and the refrigeration capacity is variably configured by controlling the frequency of the compressor. In addition, the refrigeration cycle apparatus performs an overload protection operation when the required frequency generator 20 that generates the required frequency of the compressor based on the required refrigeration capacity and the load of the compressor is greater than a predetermined value. The final target command frequency is determined based on the overload protection control unit 21 that outputs a command related to the frequency, the output from the overload protection control unit 21 and the necessary frequency generated by the necessary frequency generation unit 20, In addition, a frequency control execution unit that generates a plurality of intermediate target command frequencies stepwise to change the frequency of the compressor stepwise to the final target command frequency, and outputs the intermediate target command frequencies to the necessary frequency generation unit 20 13.

  Specifically, the refrigeration cycle apparatus includes a converter 2 that converts the AC power of the commercial power source 1 into DC, a DC output from the converter 2 is converted into AC, and a motor 4 built in a compressor (not shown) is arbitrarily added. Inverter 3 for rotational control at frequency, refrigeration cycle temperature control means 19 for calculating the required frequency of the compressor so that the refrigeration cycle is in a desired temperature state, and the required frequency of the compressor calculated by the refrigeration cycle temperature control means 19 In addition to the input, the load state of the compressor is detected and calculated to generate the final target command frequency of the compressor in consideration of the overload protection of the compressor, and the AC current supplied from the commercial power supply 1 Input current detecting means 6 for detecting, and DC current detecting means 5 for detecting a direct current supplied from the converter 2 to the inverter 3 are provided.

  The refrigeration cycle temperature control means 19 includes a necessary temperature generation means 16 that generates a necessary temperature for a refrigeration cycle (not shown) to be in a desired temperature state, a control target temperature detection means 15 that detects a temperature state of a control target of the refrigeration cycle, The frequency at which the required temperature generated by the required temperature generating means 16 and the temperature of the controlled object detected by the controlled object temperature detecting means 15 are input and the manipulated variable for increasing or decreasing the frequency of the compressor is calculated. A compressor frequency operation amount calculated by the operation amount calculation means 17 and the frequency operation amount calculation means 17 is input, and the compressor is based on the current required frequency or the intermediate target command frequency input from the frequency control means 14. The required frequency calculating means 18 for calculating the new required frequency is provided.

  The refrigeration cycle temperature control means 19 uses temperature to generate the necessary frequency of the compressor based on the required refrigeration capacity. However, it is not limited to this, For example, you may utilize a pressure.

  The frequency control unit 14 includes the overload protection control unit 21 and the frequency control execution unit 13.

  The overload protection control unit 21 of the frequency control means 14 is an input current calculation means 7 for calculating the input current from the AC current detected by the input current detection means 6 for detecting the AC current supplied from the commercial power source 1. The motor current calculating means 11 for calculating the current flowing in the motor 4 from the DC current detected by the DC current detecting means 5 for detecting the DC current supplied from the converter 2 to the inverter 3 Load torque calculation means 9 for calculating the load torque applied to the motor 4 from the calculated motor current and various information for the inverter 3 to control the energization of the motor 4, the input current calculated by the input current calculation means 7 and the preset input Load current calculated by the input current protection control means 8 and load torque calculation means 9 for controlling the protection against the input current by comparing and calculating the current limit value And a load torque protection control means 10 for controlling the protection against the load torque by comparing and calculating a limit value of the preset load torque, a motor current calculated by the motor current calculation means 11 and a preset limit value of the motor current And a motor current protection control means 12 for controlling the protection against the motor current by comparing and calculating.

  The frequency control execution unit 13 of the frequency control unit 14 determines a final target command frequency based on the output from the overload protection control unit 21 and the necessary frequency input from the necessary frequency calculation unit 18, and A plurality of intermediate target command frequencies are generated stepwise to change the frequency of the compressor stepwise to the final target command frequency, and the intermediate target command frequencies are output to the necessary frequency generation unit 20. Specifically, the frequency control execution unit 13 sequentially outputs to the inverter 3 phase information for realizing a desired frequency with a period of minute time that is extremely small compared to 1 second, and the intermediate target command frequency. The value is fed back to the required frequency calculation means 18.

  As described above, the frequency control execution unit 13 includes the input current protection state detected by the input current protection control unit 8, the load torque protection state detected by the load torque protection control unit 10, and the motor current protection control unit. A final command frequency is generated from the motor current protection state detected at 12 and output to the inverter 3 and the necessary frequency calculation means 18.

  The frequency control means 14 is one in which the overload protection control unit 21 and the frequency control execution unit 13 are provided integrally. However, the present invention is not limited to this, and the overload protection control unit 21 and the frequency control execution unit 13 may be provided independently. In addition to the overload protection control unit 21 and the frequency control execution unit 13, the necessary frequency generation unit 20 may be provided integrally.

  Next, the contents of the frequency control execution unit 13 will be described in detail.

  First, the frequency control execution unit 13 normally requires the necessary frequency calculation means when the protection control for each load of the input current protection control means 8, the load torque protection control means 10, and the motor current protection control means 12 described above does not operate. The required frequency calculated in 18 (strictly, phase information corresponding to the frequency) is output to the inverter 3 as it is. Accordingly, the refrigeration cycle control device performs frequency control of the compressor so that the refrigeration cycle is in a desired temperature state.

  On the other hand, when the protection control means against overload operates, the following occurs. For example, when the input current calculated by the input current calculation means 7 reaches a predetermined limit value, the input current protection control means 8 outputs to the frequency control execution unit 13 so as to decrease the predetermined frequency decrease amount. The frequency control execution unit 13 generates a final target command frequency by subtracting the amount of frequency reduction from the necessary frequency input from the necessary frequency calculation means 18, and also generates a plurality of intermediate target command frequencies step by step. Then, the frequency control execution unit 13 sequentially outputs this intermediate target command frequency (strictly speaking, phase information corresponding to the frequency) to the inverter 3, thereby reducing the frequency of the compressor and reducing the load on the compressor. Here, the operation is performed so that the input current falls within a predetermined limit value. At the same time, the frequency control execution unit 13 feeds back the generated intermediate target command frequency value to the necessary frequency calculation means 18.

  Here, for the sake of explanation, the limit value of the input current is set to a predetermined value. However, the limit value of the input current may be a plurality of predetermined values according to the frequency of the compressor, for example, and the input current reaches the limit value. Needless to say, the frequency reduction amount in this case may be, for example, a continuous value or a plurality of deceleration amount values calculated according to the deviation between the limit value and the input current.

  Next, when the load torque calculated by the load torque calculation means 9 reaches a predetermined limit value, the load torque protection control means 10 outputs the predetermined frequency decrease amount to the frequency control execution unit 13 so as to decelerate. The frequency control execution unit 13 subtracts the amount of frequency deceleration from the necessary frequency input from the necessary frequency calculation means 18 to generate a final target command frequency, and generates a plurality of intermediate target command frequencies step by step. Then, the frequency control execution unit 13 sequentially outputs the intermediate target command frequency (strictly speaking, phase information corresponding to the frequency) to the inverter 3 to reduce the frequency of the compressor and reduce the load on the compressor. Here, the operation is performed so that the calculated load torque is within a predetermined limit value. At the same time, the frequency control execution unit 13 feeds back the generated intermediate target command frequency value to the necessary frequency calculation means 18.

  Here, for the sake of explanation, the limit value of the load torque is set to a predetermined value, but the limit value of the load torque may be a plurality of predetermined values according to the frequency of the compressor, for example, and the load torque reaches the limit value. Needless to say, the frequency deceleration amount in this case may be, for example, a continuous value or a plurality of deceleration amount values calculated according to the deviation between the limit value and the load torque.

  Next, when the motor current calculated by the motor current calculation unit 11 reaches a predetermined limit value, the motor current protection control unit 12 outputs the predetermined frequency decrease amount to the frequency control execution unit 13 so as to decelerate. The frequency control execution unit 13 decelerates the amount of frequency deceleration from the necessary frequency input from the necessary frequency calculation means 18 to generate a final target command frequency, and generates a plurality of intermediate target command frequencies step by step. Then, the frequency control execution unit 13 sequentially outputs the intermediate target command frequency (strictly speaking, phase information corresponding to the frequency) to the inverter 3 to reduce the frequency of the compressor and reduce the load on the compressor. Here, the operation is performed so that the motor current falls within a predetermined limit value. At the same time, the frequency control execution unit 13 feeds back the generated intermediate target command frequency value to the necessary frequency calculation means 18.

  Here, for the sake of explanation, the limit value of the motor current is set to a predetermined value. However, the limit value of the motor current may be a plurality of predetermined values according to the frequency of the compressor, for example, and the motor current reaches the limit value. Needless to say, the frequency deceleration amount in this case may be, for example, a continuous value calculated according to the deviation between the limit value and the motor current or a plurality of deceleration amount values.

  In FIG. 1, the DC current supplied from the converter 2 to the inverter 3 is detected by the DC current detection means 5 and the motor current is calculated by the motor current calculation means 11. A motor current may be detected by providing a current detection means on a line for outputting drive power to the motor.

  In the above description, the overload protection control unit 21 includes the input current protection control means 8, the compressor load torque protection control means 10, and the motor current protection control means 12. However, it is not limited to this, You may provide at least any one of these.

  In the above description, the frequency reduction amount is output in the event of an overload as a command related to the frequency output to perform the overload protection operation. However, the present invention is not limited to this, and a frequency value after reduction may be output.

  FIG. 2 is a control flow diagram showing an example of the operation of the refrigeration cycle temperature control means 19 of the refrigeration cycle control device of the present invention. An embodiment of the operation of the refrigeration cycle temperature control means 19 will be described with reference to FIGS. Such necessary frequency generation processing is periodically executed at relatively long time intervals such as several tens of seconds.

  First, in step S1, the control target temperature detected by the control target temperature detection means 15 and the refrigeration cycle target temperature set by the necessary temperature generation means 16 are input to the frequency manipulated variable calculation means 17, and the frequency manipulated variable calculation means 17 The amount of increase (acceleration amount) or the amount of decrease (deceleration amount) of the compressor frequency is calculated based on the detected magnitude relationship between the control target temperature and the target temperature and the temperature deviation. In step S1, the change direction of the necessary frequency is determined.

  Although the details of the method of calculating the increase or decrease are omitted, a method of simply calculating a predetermined amount of acceleration / deceleration from the magnitude relationship between the target temperature and the control target temperature, and calculating the deviation between the target temperature and the control target temperature This method calculates the acceleration / deceleration amount with multiple or continuous manipulated variables according to this deviation, and the difference between the deviation between the target temperature and control target temperature and the previous acceleration / deceleration amount calculation As the difference, there is a method of calculating the acceleration / deceleration amount by PI control, PID control, or fuzzy control from the deviation and the deviation difference. Hereinafter, the acceleration / deceleration amount calculated by the frequency operation amount calculation means 17 is set as the temperature control operation amount.

  In step S2, the required frequency calculation means 18 compares the currently output required frequency with the intermediate target command frequency input from the frequency control execution unit 13, and determines whether the required frequency value is the same as the intermediate target command frequency value. Otherwise, if it is smaller (ie, “below”; “≦”), the process proceeds to step S9.

  In step S9, the required frequency calculation means 18 determines the acceleration / deceleration operation direction of the frequency operation amount determined in step S1, and proceeds to step S6 in the case of the deceleration direction or no operation (operation amount is 0).

  In step S6, the operation amount (deceleration amount or 0) determined in step S1 is subtracted from the current necessary frequency, and the result is output to the frequency control execution unit 13 as a new necessary frequency, and the processing is terminated. On the other hand, when the frequency operation amount determined in step S1 is in the speed increasing direction, the process proceeds to step S5.

  In step S5, the required frequency calculation means 18 adds the frequency operation amount determined in step S1 to the current required frequency value, and outputs this result as a new required frequency to the frequency control execution unit 13 to finish the process.

  On the other hand, in step S2, if the currently output necessary frequency is larger than the value of the intermediate target command frequency (ie, “>”), the process proceeds to step S3.

  In step S3, the necessary frequency calculation means 18 determines the acceleration / deceleration operation direction of the frequency operation amount determined in step S1, and proceeds to step S6 when the deceleration direction or no operation (operation amount is 0).

  In step S6, the operation amount (deceleration amount or 0) determined in step S1 is subtracted from the current necessary frequency, and the result is output to the frequency control execution unit 13 as a new necessary frequency, and the processing is terminated.

  On the other hand, in step S3, if the frequency operation amount determined in step S1 is in the speed increasing direction, the process proceeds to step S4.

  In step S4, the required frequency calculation means 18 calculates a deviation by subtracting the intermediate target command frequency input from the frequency control execution unit 13 from the current required frequency, and this deviation is equal to or smaller than a predetermined value ( That is, if “below” or “≦”, the process proceeds to step S7.

  In step S7, the frequency operation amount (speed increase amount) determined in step S1 is added to the current required frequency, and this result is output to the frequency control execution unit 13 as a new required frequency, and the process is terminated.

  On the other hand, in step S4, when the deviation between the current required frequency and the intermediate target command frequency is larger (that is, in the case of “>”), that is, in the frequency control means 14, one or a plurality of protection control means sets a predetermined value. If a frequency reduction process equal to or greater than (ie, “more than”; “≧”) is performed, the process proceeds to step S8.

  In step S8, the required frequency calculation means 18 maintains the current required frequency and outputs the current required frequency to the frequency control execution unit 13 as it is. Here, an operation for reducing the load of the refrigeration cycle is performed, for example, by operating a predetermined amount of the opening degree of the electronic expansion valve constituting the refrigeration cycle (not shown) in the direction in which the refrigerant circulation amount in the refrigeration cycle increases.

  In step S2 and step S4, when one value to be compared is larger than the other value (that is, when “>”), it is determined as YES, and when it is as follows, it is determined as NO. However, the present invention is not limited to this, and when one value to be compared is equal to or larger than the other value (that is, “more than”; “≧”), YES is determined, and when it is smaller, NO is determined. You may do.

  As described above, in the present embodiment, the required frequency calculation means 18 performs temperature control based on the control target temperature and the required temperature of the refrigeration cycle, and at the same time, the frequency control means 14 decelerates the compressor by compressor protection control. Since the load protection operation can be detected by the feedback input of the intermediate target command frequency when the processing is performed, the necessary frequency calculation means 18 has the frequency operation direction by the temperature control, the current necessary frequency, and the intermediate target command. A necessary frequency corresponding to each state can be determined from the frequency.

  As a result, when the load of the refrigeration cycle has not reached the limit, the temperature control of the refrigeration cycle can be performed satisfactorily, and also when the load of the refrigeration cycle rises and load protection control of the compressor is performed. Since the operation of the frequency of the compressor can be performed according to the load state, the refrigeration cycle control capable of minimizing the influence on the temperature control of the refrigeration cycle is possible.

  In the refrigeration cycle apparatus of the present embodiment, the overload protection control unit 21 includes an input current protection control means 8, a compressor load torque protection control means 10, and a motor current protection control means 12. Here, since the input current, the load torque, and the motor current have different characteristics, it is possible to effectively overload by separately determining the overload state of the compressor based on the different factors. Protection can be achieved.

  That is, for example, in the above prior art, since the load is detected by the output duty for applying the voltage to the motor, for example, when the converter unit for converting the commercial AC power source to the DC voltage is not a method for controlling the DC voltage, When the supplied AC voltage fluctuates, the DC voltage output from the converter unit also fluctuates. As a result of fluctuation of the DC voltage, the relationship between the load on the compressor and the duty is not constant. In the prior art, there is no description of the standard regarding the fluctuation of the DC voltage, adjustment of the regulation duty, etc., so in this case, for example, when the voltage fluctuates higher, the load is monitored with the same duty than expected. There is a risk of causing an abnormality in the refrigeration cycle by applying a load, and when the voltage fluctuates to the lower side, it is determined that the load is overloaded, but the desired refrigeration There is a possibility that the capacity or temperature cannot be output.

  On the other hand, motor frequency control (so-called PAM control) using the output voltage of the converter unit, which has been widespread in recent years, and field-weakening control that controls the field phase using a vector control method as field control for the inverter unit motor is performed. In this case, it is generally known that the output duty becomes a characteristic that becomes almost constant when the motor is controlled at a frequency equal to or higher than a predetermined rotation speed. May not be detected.

  In this respect, according to the refrigeration cycle apparatus of the present embodiment, it is possible to accurately detect the overload of the compressor regardless of the change in the AC voltage of the commercial power supply or the inverter control method.

  In addition, when the refrigeration cycle control of the present embodiment is applied to a heat pump type hot water heater, in the hot water generation unit having a refrigeration cycle, the hot water generated when the load is properly controlled and the load protection control is performed. Temperature fluctuation can be minimized.

  Further, the refrigeration cycle control of the present embodiment can achieve the same effect when applied to a refrigeration cycle apparatus such as an air conditioner or a refrigerator-refrigerator other than a heat pump type hot water heater.

  In the refrigeration cycle apparatus of the present embodiment, a scroll compressor is used as the compressor. However, the present invention is not limited to this, and the same effect can be obtained by applying the refrigeration cycle control to a refrigeration cycle apparatus including a rotary compressor or a reciprocating compressor.

DESCRIPTION OF SYMBOLS 1 Commercial power supply 2 Converter 3 Inverter 4 Motor 5 DC current detection means 6 Input current detection means 7 Input current calculation means 8 Input current protection control means 9 Load torque calculation means 10 Load torque protection control means 11 Motor current calculation means 12 Motor current protection Control means 13 Frequency control execution unit 14 Frequency control means 15 Control target temperature detection means 16 Required temperature generation means 17 Frequency manipulated variable calculation means 18 Required frequency calculation means 19 Refrigerating cycle temperature control means 20 Required frequency generation part 21 Overload protection control part

Claims (5)

In a refrigeration cycle apparatus comprising a compressor that is driven by receiving power supply from an AC power source, and wherein the refrigeration capacity is variably configured by controlling the frequency of the compressor,
A required frequency generating unit that generates the required frequency of the compressor based on the required refrigeration capacity;
An overload protection control unit that outputs a frequency-related command to perform an overload protection operation when the load of the compressor is greater than a predetermined value;
A final target command frequency is determined based on the output from the overload protection control unit and the necessary frequency generated in the necessary frequency generation unit, and the frequency of the compressor is gradually increased to the final target command frequency. A plurality of intermediate target command frequencies to be changed in stages, and a frequency control execution unit that outputs the intermediate target command frequencies to a necessary frequency generation unit,
The target frequency generator determines the magnitude relationship between the current required frequency and the intermediate target command frequency input from the frequency control execution unit, and is necessary based on the required refrigeration capacity and the current refrigeration capacity Determine the direction of frequency change,
The overload when the current required frequency is equal to, greater than or greater than the intermediate target command frequency input from the frequency control execution unit, and the change direction of the required frequency is an increasing direction. A refrigeration cycle apparatus that determines whether or not to increase a required frequency based on the presence or absence of a protective operation. The refrigeration cycle apparatus according to claim 1,
When the change direction of the required frequency is an increase direction and the overload protection operation is performed, the required frequency generation unit maintains the current required frequency, and
A refrigeration cycle apparatus, wherein an opening degree of an electronic expansion valve that adjusts a circulation flow rate of a refrigerant constituting a refrigeration cycle is operated by a predetermined amount in a direction in which the circulation flow rate of the refrigerant increases. The refrigeration cycle apparatus according to claim 1,
The refrigeration cycle apparatus according to claim 1, wherein when the change direction of the necessary frequency is an increase direction and the overload protection operation is not performed, the necessary frequency generation unit increases the necessary frequency. The refrigeration cycle apparatus according to claim 1,
The frequency control execution unit subtracts a predetermined frequency corresponding to the compressor load from the necessary frequency generated by the necessary frequency generation unit when the load of the compressor is larger than a predetermined value, A refrigeration cycle apparatus that generates a frequency. In the refrigerating cycle device according to any one of claims 1 to 4,
The overload protection control unit compares the motor current calculated from the motor current detected in the motor of the compressor or the DC current flowing in the inverter with a predetermined motor current limit value, and determines the load state. The load torque calculated by the motor current protection control means for detecting and protecting the compressor, the load torque calculating means for calculating the load torque of the compressor from the motor current or the DC current of the inverter, and a predetermined load torque limit value And the load current protection control means for detecting the load state to protect the compressor, the input current calculated by the input current calculation means for detecting the AC current of the AC power supply and calculating the input current It comprises at least one of input current protection means for comparing the input current limit value determined in advance and detecting and protecting the load state Refrigeration cycle apparatus according to claim and.

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