JP3270573B2 - Air conditioner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner having a control device for controlling a compressor by inverter control by vector control.

[0002]

2. Description of the Related Art In recent years, an air conditioner that controls the capacity by increasing or decreasing the number of revolutions of a compressor using an inverter device that varies the frequency of a power supply has been used.

As an inverter control method for a general-purpose inverter, vector control is often employed because excellent responsiveness and power saving can be obtained. Therefore, in recent years, vector control has also been applied to a variable speed control method for a compressor of an air conditioner.

The vector control method includes a magnetic flux detection type vector control method that detects a secondary magnetic flux as a vector amount and uses the primary magnetic flux as a control signal of a primary current, and a slip frequency type vector that calculates and controls a magnetic flux vector based on a motor constant. Control schemes are known.

As a conventional technique, for example, Japanese Patent Laid-Open No.
There is one disclosed in Japanese Patent No. 202387.

Referring to the drawings, an example of the operation of the prior art will be described with reference to FIGS. 7, 8, 9, 10, and 11. FIG.

FIG. 7 is a configuration diagram of a conventional air conditioner. FIG. 8 is a block diagram of a slip frequency type vector control device which is an inverter device of a conventional air conditioner.

FIG. 9 is a block diagram showing the configuration of the torque current calculator of FIG. FIG. 10 is a block diagram showing the configuration of the slip frequency calculator of FIG.

FIG. 11 is a block diagram of a magnetic flux detection type vector control device which is an inverter device of a conventional air conditioner.

In FIG. 7, 1 is a compressor, 2 is a four-way valve,
Reference numeral 3 denotes an indoor heat exchanger, 4 denotes a decompression device, and 5 denotes an outdoor heat exchanger, which are connected in a ring to form a refrigeration circuit.

Reference numeral 6 denotes an indoor fan, and 7 denotes an outdoor fan.
Reference numeral 8 denotes an inverter control device for controlling the rotation speed of the compressor 1, and reference numeral 9 denotes a three-phase AC power supply. That is, 10 is an indoor unit, and 11 is an outdoor unit.

Hereinafter, two types of inverter control devices will be described with reference to FIG. 8, FIG. 9, FIG. 10, and FIG.

FIG. 8 shows a conventional slip frequency type vector control device. The compressor 1 is supplied with AC power of a variable frequency by the power converter 12, and receives a primary current ia of the compressor 1.
1, ib1 and ic1 are detected by the current detectors 13, 14, and 15, and the rotation frequency ωR is picked up by the speed detector 16 that calculates the speed.

The secondary magnetic flux command φ2 * is supplied to the exciting current calculator 17
, The torque command τ * is converted into the torque current command iq1 * by the torque current calculator 18 and the secondary resistance R2 * of the motor inputted thereto.
The excitation current command id1 * and the torque current command iq1 * are converted by the vector rotator 19 into a current value i1 * and a phase angle θ * on the rotating magnetic flux coordinate axes (d, q axes).

On the other hand, using a torque current command iq1 *, a secondary magnetic flux command φ2 *, and a secondary resistance R2 * of the motor, a slip frequency calculator 20 generates a slip frequency command ωs *. The sum of the slip frequency commands ωs *, that is, the primary frequency ω1 is created. Further, the primary frequency ω1 is integrated by the integrator 22 to obtain the phase angle φ1 * of the rotating coordinate axis, and the adder 23 calculates the sum θ1 * with the phase angle θ * on the dq axis.

Here, the adder 23 performs an operation according to (Equation 1).

[0017]

(Equation 1)

[0018] θ1 * obtained by (Equation 1) is the position of the current as viewed on the stationary axis. The absolute value i1 * of the primary current is a combined current of the exciting current component and the torque current component, and the phase angle θ
1 * indicates the position on the two stationary axes. Therefore, 2 phase-3
The phase converter 24 converts the absolute value i1 * of the primary current and the phase angle θ1 * of the primary current into two-phase and three-phase, and three-phase current command ia
1 *, ib1 *, ic1 *, and comparators 25, 26, 2
7, the output currents ia1, ib1, ic of the power converter
Compare with 1.

In the subsequent current control, the controller is controlled by a normal proportional-type controller or a controller that uses both proportional and integral functions so that the actual current matches the command current.

Vector control becomes possible by the above method. The slip frequency command ωs * is calculated by the slip frequency calculator according to (Equation 2).

[0021]

(Equation 2)

In equation (2), R2 * is a secondary resistance, L
2 * indicates a secondary inductance, and M * indicates a mutual inductance.

FIG. 9 shows the configuration of the torque current calculator 18. A signal output through the coefficient units 25 and 26 and the differentiator 27 and a signal output only through the coefficient unit 25 are generated from the torque command τ *, and these signals are added by the adder 28 to generate the torque current command iq1 *. Is output.

FIG. 10 shows the configuration of the slip frequency calculator 20. The signal outputted from the torque current command iq1 * through the coefficient units 29 and 30 is divided by the divider 31 into the secondary magnetic flux command φ2 *.
, And passes through the coefficient unit 32, and the slip frequency command ωs *
Is output.

When the torque current command iq1 * and the slip frequency command ωs * are calculated as described above, the secondary resistance R2 * is directly involved, but in the conventional vector control method, the secondary resistance R2 * is fixed. Control was performed as.

FIG. 11 shows an example of the vector control system of the magnetic flux detection type, in which the magnetic flux is applied to the voltages va1 and vb applied to the compressor 1.
1, vc1 and the primary currents ia1, ib1, ic1 detected by the current detectors 13, 14, 15 are calculated by the magnetic flux calculator 33.

The outputs of the magnetic flux calculator 33 are the stationary biaxial components φα1 and φβ1 of the secondary magnetic flux vector, and the vector analyzer 34 outputs the absolute value component | φ2 |
are converted to φ and cos φ.

On the other hand, the secondary magnetic flux command φ2 * and the generated torque command τ * are processed by the exciting current calculator 17 and the torque current calculator 18, and the exciting current command id1 in the rotating coordinate system considering the rotating magnetic flux on the d axis. *, The torque current command iq1 *, and the vector rotator 35 outputs the excitation current command id1.
*, Converts the torque current command iq1 * into current commands iα1 *, iβ1 * in the stator coordinate system based on the phase angle φ.

That is, the output iα1 of the vector rotator 35
*, Iβ1 * are currents for producing the secondary magnetic flux components φα1, φβ1, and are converted by the two-phase to three-phase converter 36 to perform primary current commands ia1 *, ib1 *, ic1 * of the power converter 12.
And the comparison is performed by the comparators 25, 26, and 27, and the output current of the power converter 12 is controlled.

In the magnetic flux detection type vector control system, since the magnetic flux is directly controlled by giving a current command, there is no need for the secondary side inductance or resistance which has the most uncertain elements in the motor constant.

Therefore, even if the constants of the primary circuit and the secondary circuit of the motor inside the compressor 1 change, the input primary voltages va1, vb1, vc1 of the magnetic flux calculator 33 and the input primary current ia
1, ib1, ic1, and the calculation result of the magnetic flux changes accordingly. Therefore, the deterioration of the vector control characteristics due to the change of the parameter is small.

However, estimating the magnetic flux by the magnetic flux calculator 33 and the vector analyzer 34 has many problems in the accuracy and resolution of the sensor, and in particular, there is a problem in the calculation accuracy due to the voltage distortion at low speed, and cannot be performed. Is the actual situation.

[0033]

In the slip frequency type vector control configured as described above, if the secondary resistance changes with temperature, a large error occurs in the calculation of the slip frequency command ωs *, and the compressor is optimized. It deviates from the operation state with high efficiency, and the efficiency deteriorates.

Therefore, it is necessary to optimize the efficiency by some means. The present invention has been made in view of the above problems, and provides an air conditioner that can always maintain optimum efficiency by calculating efficiency and correcting a primary voltage and a phase angle of a compressor in slip frequency vector control. Aim.

[0035]

In order to achieve this object, an air conditioner according to the present invention comprises a compressor whose rotation speed is controlled by a power converter, and a current detector for detecting a primary current of the compressor. An exciting current calculator for calculating an exciting current from a secondary magnetic flux command; a torque current calculator for calculating a torque current from a primary current of the current detector and an exciting current of the exciting current calculator; 1 to output to the compressor from the exciting current of the computing unit and the torque current of the torque current computing unit
A vector rotator that calculates a secondary voltage and a phase angle, a slip frequency calculator that calculates a slip angle frequency from the secondary magnetic flux command and the torque current of the torque current calculator, and a slip angle frequency of the slip frequency calculator. An adder that calculates an actual rotation angle frequency that is the current rotation number of the compressor from a rotation angle frequency set value that is a desired rotation number; and an output of a shell discharge temperature detector that detects a shell discharge temperature of the compressor. A signal, an output signal of a shell discharge pressure detector for detecting a shell discharge pressure of the compressor, an output signal of a shell suction temperature detector for detecting a shell suction temperature of the compressor, and the shell discharge pressure detector. An enthalpy calculator for calculating compressor work from output signals of the shell suction temperature detector and the shell discharge temperature detector; and an output signal from the enthalpy calculator. A torque estimator for calculating a torque estimated value of the compressor; a primary current of the current detector, an actual rotation angular frequency of the adder, a primary voltage of the vector rotator, and a torque estimated value of the torque estimator. Calculates the efficiency by the output signal of, and comprises an efficiency checker that outputs an excitation current correction value to the excitation current calculator, and calculates the efficiency with the efficiency checker so that the optimum efficiency is obtained. It is characterized in that the primary voltage and the phase angle are corrected.

[0036]

According to the present invention, with the above-described structure, the secondary resistance that changes with temperature and the like and the efficiency that degrades due to the accuracy and resolution of the sensor are calculated inside the control, and the primary voltage and the phase are adjusted so that the optimum efficiency is obtained. An air conditioner that corrects the angle and can always operate efficiently can be realized.

[0037]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An air conditioner according to an embodiment of the present invention will be described below with reference to the drawings. Components having the same configuration as the conventional example are denoted by the same reference numerals, and description thereof is omitted.

FIG. 1, FIG. 2, FIG. 3, FIG. 4, FIG.
1 shows a first embodiment of the present invention. FIG. 1 is a schematic configuration diagram of an air conditioner according to a first embodiment of the present invention, FIG. 2 is a block diagram of an inverter control device of the air conditioner according to the first embodiment of the present invention, and FIG. FIG. 4 is a characteristic diagram showing the relationship between compressor work AW and estimated torque value τ ** in the first embodiment of the present invention, and FIG. 5 is a first embodiment of the present invention. FIG. 6 is an internal block diagram of the efficiency checker in the first embodiment of the present invention.

In FIG. 1, reference numeral 37 denotes an accumulator for feeding the gas discharged from the compressor 1 in a completely gaseous state. 38 is a shell discharge pressure detector for detecting the shell discharge pressure of the compressor 1, 39 is a shell discharge pressure detector for detecting the pressure in the shell suction pipe of the compressor 1, 40
Is a shell suction temperature detector for detecting the temperature of the shell suction pipe of the compressor 1. The shell discharge temperature detector 38, the shell discharge pressure detector 39, and the shell suction temperature detector 40 are connected to an enthalpy calculator 41. , Enthalpy calculator 4
1 is connected to the torque estimator 42.

The torque estimator 42 is connected to a vector control command operation circuit 43. Current detector 13, 1
Reference numerals 4 and 15 are connected to a vector control command operation circuit 43 via a current detection circuit 44.

In FIG. 2, reference numeral 43 denotes an exciting current calculator.
From FIG. 5, the self-secondary inductance L, which is the motor constant, is shown.
An exciting current id * is output from the divider 45 from the secondary magnetic flux command value φ2 * and the secondary magnetic flux command value φ2 *.
d1 * is output.

Numeral 47 denotes a torque current calculator which outputs the torque current iq1 * by calculating the primary current from the current detection circuit 12 according to (Equation 3) and (Equation 4).

[0043]

(Equation 3)

[0044]

(Equation 4)

Iu: Primary current of current detector 13 Iw:
The primary current 48 of the current detector 15 is obtained by calculating the exciting current command value id1 * of the exciting current calculator 43 and the torque current iq1 * of the torque current calculator 47 by (Equation 5) and (Equation 6). Voltage command value V
This is a vector rotator that outputs 1 *.

[0046]

(Equation 5)

[0047]

(Equation 6)

L1: Self-primary inductance L2: Self-secondary inductance E: Induced electromotive force The output primary voltage command value V1 * and the phase angle θ1 of the adder 23 are obtained through a two-phase to three-phase converter. It is connected to the power converter 12.

Numeral 50 denotes a slip frequency calculator and an exciting current command value id1 * of the exciting current calculator 43 and the torque current calculator 4
The slip angular frequency ωs * is output to the adder 51 by calculating the torque current iq1 * of No. 7 by (Equation 2).

The adder 51 adds the slip angular frequency ωs * and the rotational angular frequency set value ωo to obtain the actual rotational angular frequency ω1.
Is output to the integrator 22 and the efficiency checker 52.

The efficiency checker 52 calculates the actual rotation angular frequency ω1 of the adder 51 and the estimated torque value τ ** of the torque estimator 42 from the multiplier 53 in FIG. When the primary voltage I of the current detection circuit 12 is calculated by the divider 54, the efficiency value ν is calculated. When the efficiency value ν is stored in the storage 55, the efficiency value ν ′ calculated last time is output from the storage 55. The output efficiency values ν and ν ′ are compared by the comparator 56 and ν
If −ν ′ <0, the excitation current correction value id1 ** is + α, ν
If −ν ′> = 0, a value obtained by −α of the excitation current correction value id1 ** is output.

The flow of control for calculating the efficiency and correcting the primary voltage and the phase angle will be described below with reference to FIGS. 3, 4, 5 and 6.

FIG. 3 is a Mollier diagram, in which the vertical axis represents pressure and the horizontal axis represents enthalpy. In FIG. 1, the degree of superheat is 0 ° C. due to the presence of the accumulator 37, and the Mollier diagram shown in FIG. 3 is obtained. From the Mollier diagram of FIG.
The enthalpy E2 can be calculated from the shell discharge pressure P1 and the shell discharge temperature T2, and the intersection of the isoenthalpy line starting from this intersection with the shell suction temperature T1 becomes the enthalpy E1, that is, the compressor has a relationship of AW = E2-E1. Work load AW can be calculated.

The shell discharge temperature T2 of the compressor 1 detected by the shell discharge temperature detector 38 and the shell discharge pressure detector 39
And the shell suction temperature T1 detected by the shell suction temperature detector 40 are input to the enthalpy calculator 41.

The enthalpy calculator 41 calculates the compressor work AW from the Mollier diagram of FIG. 3 and inputs the result to the torque estimator 42. The torque estimator 42 estimates the torque τ1 ** from the relationship between the compressor work AW and the torque τ ** of FIG. Output.

The operation of the efficiency checker 52 will be described below with reference to FIG. Actual rotation frequency ω added by the adder 51
1 and τ1 ** estimated by the torque estimator 42 are input to the multiplier 53, and the obtained operation result is input to the divider 54. The divider 54 performs a division operation on the input from the multiplier 53, the primary voltage V1 * from the vector rotator 48, and the primary current I from the current detection circuit 12, and calculates the current efficiency τ of the compressor 1 Calculate. When the efficiency value ν is stored in the storage 55, the efficiency value ν ′ calculated last time is output from the storage 55.

The output efficiency values ν and ν ′ are compared by the comparator 56, and if ν−ν ′ <0, the excitation current correction value i
If d1 ** is + α, and ν−ν ′> = 0, a value obtained by subtracting the excitation current correction value id1 ** from −α is output.

The output excitation current correction value id1 ** is input to a torque current calculator 47, and is input to a comparator 46 shown in FIG. 5 to correct the value of the excitation current id * from the divider 46 by soil α. In addition, an exciting current command id1 * is output.

The corrected excitation current command id1 * is input to the vector rotator 48, where the primary voltage V1 * and the phase angle θ *
Is output. The output primary voltage V1 * and phase angle θ * are values corrected by the excitation current correction value id1 ** from the efficiency τ ′ calculated by the efficiency checker 52 last time, and thus are higher than the efficiency τ ′. The primary voltage V1 * of the value efficiency τ,
The phase angle becomes θ *. Thereafter, the values of the primary voltage V1 * and the phase angle θ * are transmitted through the two-phase to three-phase converter 49 to the power converter 12.
And the compressor 1 is operated.

As described above, according to the present embodiment, the secondary resistance that changes depending on the temperature and the like, and the efficiency that degrades due to the accuracy and resolution of the sensor are calculated inside the control, and the primary resistance is calculated so as to obtain the optimum efficiency. The voltage and the phase angle are corrected, and efficient operation is always possible. Further, since the torque is not estimated based on the internal torque current and is estimated from the pressure and temperature of the outdoor unit system, even if the control system shifts, it is possible to quickly return to a stable state. Further, since it is also used as a sensor used for controlling the outdoor unit, it can be configured at a low cost and can be easily realized.

[0061]

As described above, the present invention provides a compressor whose rotation speed is controlled by a power converter, a current detector for detecting a primary current of the compressor, and an excitation current calculated from a secondary magnetic flux command. Exciting current calculator, a torque current calculator for calculating a torque current from a primary current of the current detector and an exciting current of the exciting current calculator, an exciting current of the exciting current calculator and the torque current calculator A vector rotator for calculating a primary voltage and a phase angle to be output to the compressor from the torque current, and a slip frequency calculator for calculating a slip angular frequency from the secondary magnetic flux command and the torque current of the torque current calculator. An adder that calculates an actual rotation angle frequency that is the current rotation number of the compressor from a slip angle frequency of the slip frequency calculator and a rotation angle frequency set value that is a desired rotation number; and a shell discharger of the compressor. An output signal of a shell discharge temperature detector for detecting a temperature, an output signal of a shell discharge pressure detector for detecting a shell discharge pressure of the compressor, and a shell suction temperature detector for detecting a shell suction temperature of the compressor. An output signal, an enthalpy calculator for calculating compressor work from output signals of the shell discharge pressure detector, the shell suction temperature detector, and the shell discharge temperature detector, and an output signal from the enthalpy calculator. A torque estimator for calculating a torque estimated value of the compressor; a primary current of the current detector, an actual rotation angular frequency of the adder, a primary voltage of the vector rotator, and a torque estimated value of the torque estimator. Efficiency is calculated based on an output signal, and an efficiency checker that outputs an excitation current correction value to the excitation current calculator is provided. The efficiency that degrades due to the accuracy, resolution, etc. of the air conditioner is calculated inside the control, the primary voltage and the phase angle are corrected to achieve the optimum efficiency, and an air conditioner that can always operate efficiently can be realized. The practical effects are significant.

Since the discharge pressure, suction temperature and discharge temperature of the compressor are used for system control of the air conditioner,
The present invention can also be used, and can be easily realized.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an air conditioner according to a first embodiment of the present invention.

FIG. 2 is a block diagram of an inverter control device of the air conditioner according to the first embodiment of the present invention.

FIG. 3 is a Mollier diagram of the air conditioner according to the first embodiment of the present invention.

FIG. 4 shows the compressor work AW in the first embodiment of the present invention.
Graph showing the relationship between the torque and the estimated torque value τ **

FIG. 5 is an internal block diagram of an exciting current calculator according to the first embodiment of the present invention;

FIG. 6 is an internal block diagram of an efficiency checker according to the first embodiment of the present invention.

FIG. 7 is a schematic configuration diagram of an air conditioner in a conventional example.

FIG. 8 is a block diagram of a slip frequency type vector control inverter device of an air conditioner in a conventional example.

FIG. 9 is a block diagram of a torque current calculator of a slip frequency type vector control inverter device of an air conditioner in a conventional example.

FIG. 10 is a block diagram of a slip frequency calculator of a slip frequency type vector control inverter device of an air conditioner in a conventional example.

FIG. 11 is a block diagram of a magnetic flux detection type vector control inverter device of an air conditioner in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 12 Power converter 38 Shell discharge temperature detector 39 Shell discharge pressure detector 40 Shell suction temperature detector 41 Enthalpy calculator 42 Torque estimator 43 Excitation current calculator 44 Current detector 47 Torque current calculator 48 Vector rotation 50 Slip frequency calculator 51 Adder 52 Efficiency checker

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F25B 1/00 F24F 11/02 102 F04B 49/06 341

Claims (1)

(57) [Claims] 1. A compressor whose rotation speed is controlled by a power converter, a current detector for detecting a primary current of the compressor,
An exciting current calculator for calculating an exciting current from a secondary magnetic flux command; a torque current calculator for calculating a torque current from a primary current of the current detector and an exciting current of the exciting current calculator; and an exciting current calculator A vector rotator for calculating a primary voltage and a phase angle to be output to the compressor from the exciting current of the torque current of the torque current calculator and a slip angle based on the secondary magnetic flux command and the torque current of the torque current calculator. A slip frequency calculator for calculating a frequency, and an addition for calculating an actual rotation angle frequency that is the current rotation speed of the compressor from the slip angle frequency of the slip frequency calculator and a rotation angle frequency set value that is a desired rotation speed. An output signal of a shell discharge temperature detector for detecting a shell discharge temperature of the compressor, an output signal of a shell discharge pressure detector for detecting a shell discharge pressure of the compressor, Calculate compressor work from an output signal of a shell suction temperature detector that detects a shell suction temperature of the compressor, and output signals of the shell discharge pressure detector, the shell suction temperature detector, and the shell discharge temperature detector. An enthalpy calculator, a torque estimator that calculates an estimated torque value of the compressor based on an output signal from the enthalpy calculator, a primary current of the current detector, an actual rotation angular frequency of the adder, and the vector rotation. An efficiency checker for calculating efficiency based on a primary voltage of the motor and an output signal of a torque estimation value of the torque estimator, and outputting an excitation current correction value to the excitation current calculator. An air conditioner characterized in that the efficiency is calculated by an air conditioner and the primary voltage and the phase angle are corrected so as to obtain the optimum efficiency.