JPS63283492A - Motor controller for compressor - Google Patents

Abstract

PURPOSE:To obtain a high correcting effect at all times in the whole operating area of a compressor including stopping condition, by correcting the constant of an induction motor based on the delivery pipe temperature or the delivery gas temperature of the compressor. CONSTITUTION:A temperature sensor 23 is provided on the delivery pipe 24 of a compressor 1 and detects the temperature of delivery gas or the delivery pipe of the compressor 1. A control circuit 24 corrects the constant of an induction motor based on the delivery gas temperature or the delivery pipe temperature, which keeps a given temperature relation with the secondary rotor temperature of the induction motor, and controls the induction motor 2 in accordance with the corrected value of the constant. According to this method, the effect of the change of the resistance of a secondary windings due to the temperature change of the induction motor may be corrected correctly at all times.

Description

Detailed Description of the Invention [Field of Industrial Application] This invention provides a compressor motor that controls the rotational speed and torque of the induction motor in an electric compressor by controlling the current and frequency of the induction motor. The present invention relates to a control device.

(Prior Art) Conventionally, a 1ljfl device for this type of compressor term conduction motor is shown in Fig. 6.
is the electric compressor, 2 is its induction motor, and 3 is the induction motor 2.
4 is a current detector for detecting the primary current of the induction motor Ja2; 5 is a current detector for detecting the primary current of the induction motor Ja2;
is a variable frequency power converter that drives the induction motor 2 at a variable frequency; 6 is a torque command generator for generating the torque command TH; and 7 is a torque generator that inputs the torque command TN◆ and has a predetermined correspondence relationship therewith. A generation circuit that generates the current component command It◆, 8 a magnetic flux command generator that generates the secondary magnetic flux command Φ2$, and 9 an exciting current component command that inputs the secondary magnetic flux command Φ2 and has a predetermined correspondence relationship therewith. A generating circuit 10 that generates IE- inputs the torque current component command 1t''& excitation current component command IEI, and calculates an amplitude command II+.1 and a phase command θt.of the primary current to be supplied to the induction motor 2 through calculations described later. and a current vector calculation circuit that generates the slip angular frequency command ωS°; 11 is a current command generation circuit that inputs the output of the current vector calculation circuit 10 and the rotational speed ω and calculates a command for the primary current to be supplied to the induction motor 2; circuit, 1
Reference numeral 2 denotes a current control circuit that generates a control signal to the variable frequency power converter 5 from the output of the current command generation circuit 11 and the output of the current detector 4.

The current vector calculation circuit 10 includes a circuit 10a for each phase.
~10c, +f? The arithmetic processing described in f is performed.

It, "l=, /i"Tπ" --------(1) θ
? "= tan-'(It"/Ig") --
-1--(2) However, T2 = L2/R2--
-------(4) (R2 and L2 are the secondary winding resistance and secondary winding inductance of the induction motor 2, respectively.

) Further, the current command generating circuit 11 performs the calculation process shown by the following equation, and generates the primary current commands tus' and ivs' to be supplied to the U-phase winding and V-phase winding of the induction motor 2.

t us' =l I l"l・cos (ω.t+θ
-C1)1 vg” = l I l'l・cos (
ω. t+θ, -1π) However, ω. =ω, +ω! ! '
−−−−−−−−−−−−(fi) and current −1
In the #4 circuit 12, the above-mentioned −・next current command 1 us”
+ 1 vs” is compared with the actual primary current jLIIl+lVs obtained from the current detector 4, and a control signal to the variable frequency power converter 5 is sent so that the current command waveform matches the actual current waveform. Calculated.

At this time, regarding the primary current flowing through the W-phase winding, the primary current command t is determined using the following relational expression in the current control circuit 12.
ws” + iws is calculated, and the −order current 1u*+I
It is controlled in the same way as Vj.

Iws' = (1us" + lv++')
----------(7) 1 ws ” (j 1ll
l+ j vs) −−−−−−−−−−(8) Primary current command according to the relational expressions (1) to (7) above!
um' + f vll and I Wm'', and calculate the actual primary current I Lllll+ 1 v11+
A control method in which control is performed so that 5- and 5- coincide with the corresponding commands is usually called a vector control method. In particular, when the excitation current component command 11 is constant, the torque of the induction motor 2 is equal to the torque current component command 111. It is known that variable speed control of the induction motor 2 that changes in proportion to and is stable and has a high speed response can be realized.

By the way, since this control method calculates the primary current command, the induction motor a2
The values of the secondary winding resistance R2 and the secondary winding inductance L2, which are constants, are required. However, the secondary winding resistance R2
changes with temperature, so current vector calculation circuit 1
If the value of R2 or T2=L2/R2 in 0 is not corrected by some means, the linearity of the torque with respect to the torque current component command It° will be lost, and the torque and secondary magnetic flux of the induction motor 2 will not match the respective commands. It becomes impossible to control the

As a correction circuit for temperature changes in the value of the secondary winding resistance R2, for example, there is a circuit shown in FIG. 7 (IEEE
Trans, IA Vol, IA-16, No.
, 2 PP173-178.1980), in the figure,
13 is a first power calculation which inputs the primary voltages V, , V, and the negative current 111s+IVs of the induction motor 2 and detects the amount of power FO related to the reactive power generated in the induction motor 2 by a calculation described later. circuit, 14 is the secondary magnetic flux command Φ2-
Torque current component command X1・, slip angle frequency command ωS
A second power calculation circuit 15 is a correction circuit which inputs the rotational speed ωr of the induction motor 2 and calculates a power amount Fo corresponding to the power amount FO by a calculation described later.

Next, the calculation formula and correction method for the above-mentioned powers iFo and Fo. will be explained. In the following explanation, the stone chips with a book mark are constants of the induction motor 2 in the control circuit such as the current vector calculation circuit 10.

As is well known, the voltage equation on the stator side (-next side) of the induction motor 2 on the stator coordinate axis (d-q coordinate axis) is given by the following equation.

Vd5= (R+ +PL1 σ)ids+-PΦ2d
■qs= (R+ +PLl σ)iqs+ P
Φ21---------- (9) Vds l vqs ;-d-axis and q-axis components ld of the -order voltage
s, lqs; - d-axis of the next current, qM component Φ2d, Φ2q
; d-axis and q-axis components of secondary magnetic flux However, R, , L, , M, L
2 are the primary winding resistance, -order winding inductance, -order, secondary mutual winding inductance, and secondary winding inductance of the induction motor 2, respectively. Further, a is a leakage coefficient and is given by the following equation.

From the above equation (9), the reactive power Q is expressed by the following equation.

Q = Vds" lqs "Vqs" ldsυ +L, σ(iq,・Plds jds・Piq,
) --------(I I) By the way, when controlling the primary current of the induction motor 2 according to the above-mentioned relational expressions (1) to (7), the following relationship is known as well-known. There is.

i ds” = [B”CO3ω. t-1z”*sin
0g ti qs' = I F, "sin ωo
t+1℃"・cos ω.t-1---(12) Φ2d'"Φ2"CO3(1).tΦ,q'=Φ2
'sin ωot ---1---(13) However, j ds" + lqs' + Φ2d", Φ2
J is respectively j ds+ 1 q$+Φ2c++
This is a 2Q directive. Moreover, ω0 is given by the above equation (6).

In addition, the relational expression of the above-mentioned equation (12) can be calculated from the above-mentioned (1) to (5) 2 and the below-mentioned equation (17) to obtain the primary current command j un' +
It can also be obtained by eliminating iv,,'.

Then, from equations (12) and (13), the following relationship is obtained.

--------(+4) The relational expression corresponding to this equation (14) becomes the following equation from equation (11).

(iqsPΦ2d tdsPΦ29)=Q-L1
σ (tqsφP ids Lds” P 1qs
) Here, since the secondary winding resistance R2 is not included in the above equation (15), the value of R2 is not affected by temperature changes, and moreover, it can be easily calculated using the primary voltage and negative current of the induction motor 2. can be calculated. On the other hand, although the value of the secondary winding resistance R2 is not directly included in equation (14), IE◆+I? ”
+Φ2 are all command values, so if the value of R2I does not match the actual value of R2, the exciting current I in the induction motor
[, the torque current any secondary magnetic flux Φ2 no longer matches the respective commands. Therefore, a deviation occurs between the value calculated using equation (14) and the value calculated using equation (15). Therefore, the value of R2° or T2· in the current vector calculation circuit IO can be corrected so that this deviation becomes zero. In the circuit shown in FIG. 7, the value of T2- is corrected based on this principle.

By the way, the d-axis and q-axis components of the negative voltage Vds.

■Q3 and primary 'company pressure Vlls+V VM and -next'
+TE m (7) d axis, q component 1ds+Iv+
As is well known, the relational expression between + is given by the following equation.

Substitute into the right-hand side of equations (16), (17), and (15) to obtain the d-axis and 9 components of the primary voltage, V. .

V qs, d-axis of -order current, q component 1ds + 1.1g
By erasing the electric motor F. The calculation formula is as follows.

Fo = J"""J (Vusl vs Vv, t
1111Ll (71vsP i um+ LI Q
l usP 1 vj” ””■((vus L +
Cj P 1 us) 1 v++ (Vv++-
Lr OP j vs) 1 usl---(18)
Further, the calculation formula for the power amount Fo- is the right side of the formula (14), that is, the following formula.

Next, the operation of the correction circuit shown in FIG. 7 will be explained. First, the first power calculation circuit 13 and the second calculation circuit 1
As the output of 4, the electric energy FO is obtained from the calculations of equations (18) and (19), respectively.

Fo fist is required. Then, in the subtracter 15a, the electric energy F
Obtain the deviation ΔFO of the same FO as o゛, and integrate this deviation as 15
By integrating with b, the correction amount Δ of the constant setting value T2
T2 medium is obtained. During this correction amount ΔT2 and constant setting value T
By adding the setting amount T 20◆ of reference z with the adder 15c, the corrected setting value T2· is obtained. As a result, T2 in the current vector calculation circuit 10 in FIG.
Since the value of ° is corrected, even if the value of the secondary winding resistance R2 changes due to a temperature change, the linearity between the torque current component command 11 and the torque is maintained.

[Problem that the invention seeks to solve]

Conventional compressor motor control devices are configured as described above, and in order to cope with temperature changes in the secondary winding resistance of the induction motor during operation, the secondary winding resistance in the current control circuit is adjusted. However, all calculations in the electric energy Fo used in the correction circuit use the excitation current component specification IE-) torque current component command I
A command value such as C is used. However, due to the characteristics of the current control circuit for controlling the actual primary currents ius+ivs+ and iws to match their respective commands, a deviation may occur between the actual value of the -order current and the command value, or the variable frequency power If the control system becomes saturated depending on the operating condition due to limitations in the current and voltage withstand capacity of the converter, the excitation current component IE and torque may not match the command even if the secondary winding resistance value has been correctly corrected. Current component It
cannot be supplied to the induction motor. In such a case, even though the secondary winding resistance value has been correctly corrected, a deviation will occur between the electric energy Fo'' and the electric power I Fo, and the correction circuit will output an incorrect correction result. There was a problem.

Moreover, the amount of electric power F for correcting the secondary winding resistance R2
In order to calculate O, it is necessary to measure the negative current 1us+ivs, and there is a problem that the calculation formula becomes complicated.

This invention was made in order to solve these problems, and is based on the characteristics of the current control circuit.The present invention is based on the characteristics of the current control circuit.The present invention is based on the characteristics of the current control circuit. The present invention aims to provide a control device for a compressor motor that is not affected by saturation and can always accurately correct the influence of changes in resistance of a secondary winding due to temperature changes.

[Means for solving problems]

The compressor motor control device of the present invention includes a temperature sensor that detects the discharge gas temperature or discharge pipe temperature of the compressor, and a variable frequency power converter that drives an induction motor connected to the compressor at a variable frequency. , calculating the primary current supplied to the induction motor as a vector quantity with a functional relationship based on a constant of the induction motor according to a torque command value and a magnetic flux command value, and outputting at least either a shear frequency or a slip angle. A current vector calculation circuit, a detection stage for detecting the rotational speed or slip frequency of the induction motor, and a current for calculating a command value of the primary current to be supplied to the induction motor from the output of the current vector calculation circuit and detection means described in +fff. A correction circuit is provided for correcting the constant of the induction motor used for calculation by the current vector calculation circuit, detection means, etc. based on the discharge gas temperature or discharge pipe temperature.

(Function) In the compressor motor control device of the present invention, the temperature of the discharge gas or discharge pipe of the compressor maintains a constant temperature relationship with the rotor temperature on the secondary side of the induction motor. The constant of the induction motor is corrected, and the induction motor is controlled according to the corrected value. As a result, the influence of changes in the resistance of the secondary winding due to changes in temperature of the induction motor is always accurately corrected.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the same reference numerals are given to the same components as those of the conventional device described above. FIG. 1 is a schematic diagram of an air conditioner using an electric compressor, and in the figure, l is the electric compressor,
2 is an induction motor, 5 is a variable frequency power converter, 16.
17 is an indoor heat exchanger and an outdoor heat exchanger, 18.19
are the fans installed in these heat exchangers 16 and 17, 2
0 is a four-way valve that is a switching valve for heating and cooling, 21 is an expansion valve, 22
A pipe 22 connects the NIi components of each refrigeration cycle, and a refrigerant (for example, fluorocarbon) that absorbs heat (hot and cold) from the outside air and water flows through the pipe 22. 2
3 is a temperature sensor installed in the discharge pipe 24 of the compressor 1;
The discharge gas or discharge pipe temperature of the compressor 1 is detected. 24 is a control circuit that controls the drive system of the compressor l.

FIG. 2 is a block diagram showing details of the variable frequency power converter 5 and control circuit 25 of FIG. 1.

In the figure, 26 is an AC power supply, 27 is a rectifier consisting of a diode bridge connected to the AC power supply 26, and 28 is a rectifier 2.
7 is a smoothing capacitor for smoothing the output voltage, 29 is a DC voltage detector for detecting the DC voltage smoothed by the smoothing capacitor 28, and 30 is a DC voltage detector for detecting the DC current flowing through the smoothing capacitor 28 and the variable frequency power converter 'a5. A current detector; 31 is a fundamental wave voltage detector that detects the fundamental wave amplitude of the output voltage 1 of the variable frequency power converter 215; 32 is a DC voltage VDC1 detected by the DC voltage detector 28; a DC current detector 30; 33 is an induction motor 5 which calculates and detects the rotational speed or slip frequency ω$ of the induction motor 2 from the detected DC current IDC1 and the fundamental wave amplitude IV+l of the negative voltage; command rotation speed ω
- and the rotation speed ωr; 34 is the adder 3;
A speed controller that proportionally and integrally integrates the output from 3.
35 is a slip frequency command calculator for calculating slip frequency commands ω and ω from the output from the speed controller 34;
36 is the above slip frequency command 05 and slip frequency ωS
37 is a slip frequency controller, 38 is an adder that adds the output from the Suberi frequency controller 37 and the speed command ωre, and 39 is an adder that also adds the slip frequency command ωJ and the rotation speed ω. 40 is an integrator that integrates the primary frequency ω1 to obtain the rotation angle θ0;
41 is the output from the speed controller 34 and the rotation angle θ from the integrator 40; Primary current command 1+”
A current vector calculation circuit that calculates at least a fraction of the slip frequency or slip angle. 42 is a current controller that outputs a pressure command V+'' based on the error between the primary current command t from the adder 43 and the -h-th order current 11, and constitutes the current command generation circuit 44. 45 uses PWM (Pulse Width Modulation) to control the primary voltage command.
A PWM conversion circuit that converts into a signal, 46 is a temperature sensor 23
This is a correction circuit that corrects constants such as the secondary resistance R2 mentioned above in response to the IPA code.

Next, the operation of the control device configured as described above will be explained.

First, the heating operation in the refrigerant circuit shown in FIG. 1 will be explained. The refrigerant compressed by compressor 1 is sent to the indoor heat exchanger at high temperature and pressure! It flows to 6.

Here, the fan 8 on the indoor side sends cold indoor air to the heat exchanger 16 to take away the temperature of the refrigerant. This heats the inside of the ``.At this time, the refrigerant is cooled and becomes a low-temperature liquid.The cooled refrigerant is expanded by the expansion valve ``21'' and becomes a low-temperature, low-pressure liquid. The liquid refrigerant is sent to the outdoor heat exchanger 17.The temperature of the refrigerant at this time is one minute lower than the outside air temperature, such as 0°C, so it can absorb heat from the outside air. fan 19
plays the role of imparting heat from the outside air to the refrigerant. and,
The liquid refrigerant absorbs heat, becomes gaseous again, returns to the compressor 1, and is compressed again. Here, the induction motor 2 is connected to a compressor 1, and its rotation operation is converted into compression operation. The above operation heats the room. The variable frequency power converter 5 performs the same operation as described in FIG. 6 above. On the other hand, the temperature sensor 2 installed in the discharge pipe 24
The detection signal No. 3 is input to the variable frequency power converter 5 for overheating protection of the compressor 1 and temperature control of the air conditioner. At this time, the discharge gas temperature (discharge pipe temperature) changes in correlation with the rotor temperature of the induction motor 2.

When trying to control the speed of the induction motor 2 connected to the compressor 1, the DC voltage VDC from the DC pressure detection base 29, the DC current Idc from the DC current detector 30, and the fundamental wave voltage detector 31 Fundamental wave amplitude of primary voltage lV
+l, the estimated slip frequency value 32 is calculated by calculating the estimated slip frequency value 32 using the following equation.

Pc= Ioc Loss, etc. W+: Primary copper loss, iron loss, etc. iq: Internal effective current eq: Internal effective voltage ωow Primary frequency Frequency: Secondary magnetic flux R1, R2: 1, Secondary resistance ωS: Slip frequency M: Mutual inductance L: Self Inductance Here, the symbol on the upper right of each numerical value (for example, ωS indicates a command value, and the symbol directly above (for example, KA) indicates an estimated value, respectively.

Then, the estimated value of the speed is determined from the estimated slip frequency value obtained by the above equation and the speed command ω', and the speed is controlled by the speed controller 34.The output of the speed controller 34 is the amplitude of the primary current. command iqs'
◆ / id s '” is the excitation current command value ids”
The current vector is also applied to the current vector calculation circuit 41. As shown in FIGS. 3 and 4, this vector calculation circuit 41 calculates the primary frequency rotation angle phase θO given from the integrator 40, the primary current amplitude command iqs'/i d s', and the exciting current. From the command, as shown in the following formula, ius” = Eds” Co! +00”-iqs
” srnθOims 琐 =i4.・cos (
Og $−−π) −ims” = lus”
+vs' AC primary current command value (fuq"+Ivs"
.

ins”).

Then, according to these current command values, a predetermined current of the induction motor 2 is caused to flow by the current controller 42 using the PWM conversion circuit 45 and the variable frequency power converter 5.
Figure t53 is a circuit configuration diagram showing an example of the current vector calculation circuit 41, in which a calculation unit 47a calculates a command value for the rotation angle phase.
~47d, adders 48a, 48b, other arithmetic units 49
It is composed of a to 49d. FIG. 4 is a circuit configuration diagram showing an example of the current command generation circuit 44, in which adders 43a to 43c for each phase are connected to an adder 50 in the stage, and speed controllers 42a to 42 are connected to the adder 50 in the subsequent stage.
c is connected.

On the other hand, when calculating the slip frequency from the −th order 'It flow amplitude command iqs''/ids'', if the secondary resistance R2 changes due to an increase in the rotation r of the induction motor 2, the 1-edge frequency command value becomes It is not calculated correctly.

Therefore, in this embodiment, the discharge gas temperature (discharge pipe temperature) tc
Utilizing the fact that there is a correlation with the rotor temperature tr of the induction motor 2, a secondary resistance correction i51 as shown in FIG. seek. Here, R,, R2 are obtained from the following equation.

ta: R,, R21i1 Regular temperature tc': Discharge gas temperature (discharge pipe temperature) tPl・j P2: Supplementary temperature The primary element 52 in FIG. If there is a difference in heat capacity with the rotor, a first-order lag is set in the discharge gas temperature tc, and the time constant aT can be freely set depending on the difference in heat capacity. In addition, correction circuit 4
6 is also applied to the slip frequency calculator 32 at the same time, and performs calculations that are free from errors due to temperature changes in the -water resistance R5 and secondary resistance R2. Therefore, the obtained slip frequency order value ω2 and the estimated slip frequency value ω are controlled by the slip frequency controller 37 so that ω2 and ω always match - the next layer wave number ω. is controlled.

Although the detection signal of the temperature sensor 23 input to the correction circuit 46 may be directly input as in the above embodiment, it is preferable to input it through a high frequency removal filter. Alternatively, a temperature bias may be applied to the temperature detected by the temperature sensor 23, and the resulting signal may be input.

[Effects of the Invention] As explained above, according to the present invention, the temperature correction of the primary and secondary A-line resistances of the electric compressor is performed by adjusting the rotation of the induction motor to maintain a constant correlation with the temperature. The configuration is such that the constant of the induction motor is corrected based on the discharge pipe temperature or discharge gas temperature, so a high correction effect can always be obtained in the entire operating range, including when the compressor is stopped. The secondary winding is not affected by saturation of the control system caused by the current control deviation based on the characteristics of the current control circuit, the current withstand capacity of the variable frequency power converter, the voltage withstand limit, etc. This has the advantage that the influence of resistance changes can always be accurately corrected.

[Brief explanation of drawings]

FIG. 1 is a refrigerant circuit diagram of an air conditioner using an electric compressor according to an embodiment of the present invention, and FIG. 2 is a block diagram showing details of the variable frequency power converter and control circuit of FIG. 1.
3 is a circuit configuration diagram showing an example of the current vector calculation circuit in FIG. 2, FIG. 4 is a circuit configuration diagram showing an example of the current command generation circuit in FIG. 2, and FIG. 5 is a modified circuit in FIG. 2. FIG. 6 is a block diagram showing a conventional control device for an induction motor for a compressor. FIG. 7 is a block diagram of a conventional correction circuit for temperature changes in the secondary winding resistance of an induction motor. It is. l...Compressor 2...Induction motor 5...Variable frequency power converter 23...Temperature sensor 24...Discharge pipe 32...Slip frequency calculator (detection means) 41...
Current vector calculation circuit 44...Current command generation circuit 46...Modification circuit Note that the same reference numerals in the drawings indicate the same or equivalent parts.

Claims (3)

[Claims] (1) A temperature sensor that detects the discharge gas temperature or discharge pipe temperature of the compressor, a variable frequency power converter that drives an induction motor connected to the compressor at a variable frequency, and a primary current that supplies the induction motor. a current vector calculation circuit that calculates as a vector quantity with a functional relationship based on a constant of the induction motor according to a torque command value and a magnetic flux command value, and outputs at least either a slip frequency or a slip angle, and a rotation of the induction motor. The present invention includes a detection means for detecting a speed or a slip frequency, and a current command generation circuit for calculating a command value of a primary current to be supplied to an induction motor from the output of the current vector calculation circuit and the detection means. A control device for a compressor motor, comprising a correction circuit for correcting a constant of the induction motor used for calculation by the current vector calculation circuit, detection means, etc. based on the discharge pipe temperature. (2) The control device for a compressor motor according to claim 1, wherein the correction circuit inputs the detection signal of the temperature sensor through a high frequency removal filter. (3) The control device for a compressor motor according to claim 1 or 2, wherein the correction circuit inputs a signal obtained by applying a temperature bias to the temperature detected by the temperature sensor.