JP3667903B2 - Control device for motor for compressor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device for a compressor motor that controls torque of a motor that drives a compressor.
[0002]
[Prior art]
In recent years, inverters have been used for variable speed control of compressors for air conditioners and refrigerators. Furthermore, in the air conditioner, a DC brushless motor has been adopted for the electric motor of the compressor for the purpose of energy saving.
[0003]
On the other hand, in a hermetic rotary compressor used for an air conditioner or the like, it is known that the load torque fluctuates due to a change in refrigerant gas pressure in each of the suction, compression, and discharge strokes. It is also known that the load torque due to the gas pressure fluctuates in synchronization with the rotation of the compressor, and accordingly, the rotation speed of the compressor fluctuates periodically to cause vibration of the compressor itself. As means for suppressing the vibration, there has been proposed a method (hereinafter referred to as torque control) in which the output torque of the electric motor is changed in synchronization with the load torque of the compressor to suppress the rotational speed fluctuation.
[0004]
Conventionally, as a control method using a DC brushless motor, for example, a control device as shown in FIG. 9 has been proposed. This is a control device provided with torque control for generating electric motor output torque according to load torque so as to suppress vibration of the compressor.
[0005]
9, the control device includes a voltage inverter 1 to mark pressurizing the brushless motor 3 of the compressor 2 by switching the DC power supply, the terminal voltage U of the armature winding of the brushless motor 3, V, and W Based on voltage detection means 4 to detect, voltage information of each phase output from the voltage detection means 4, position detection means 5 for calculating the position of the rotor of the brushless motor 3, its position detection signal, and externally in the voltage control means 7 for creating a switch driving signal of the inverter 1 based on the operation frequency command signal given, and the load torque pattern storage unit 15 for storing the pulsation pattern in the load torque in one rotational period (see 0 Figure 1) Composed.
[0006]
The voltage control unit 7 includes a speed control unit 8 that determines an average output voltage command based on an operation frequency command f ^* given from the outside, an average voltage command value output from the speed control unit 8, and a position detection unit 5. Is generated based on the rotor position signal output from the motor, and a drive signal generation unit 9 generates six control signals for PWM driving the six switches in the inverter 1 from the voltage command. And a driver unit 10 that converts the control signal into a voltage that can drive the switch in the inverter 1.
[0007]
The drive signal generation unit 9 includes a torque control unit 12 that outputs an output voltage correction amount corresponding to the load torque pulsation of the compressor 2 depending on the rotation angle phase of the compressor 2, a speed control unit 8, and a torque The PWM signal generator 11 is configured to generate a PWM signal in response to the output of the controller 12.
[0008]
Next, the operation of the conventional control device will be described. Given a rotation frequency command for the compressor 2 to the speed control unit 8, the instruction value of the corresponding output voltage of the inverter 1 to the rotational speed V ^* is created, from the PWM signal generator 11, for example, FIG. 1 1 A signal as shown in FIG.
[0009]
The PWM signal generator 11 changes the pulse width of the chopping switch (for example, Sup, Svp, Swp) at each time based on the given voltage command, and outputs it. When the voltage from the inverter 1 is applied, the DC brushless motor 3 starts rotating in synchronization with the voltage frequency. In this case the U-phase switch control signals Sup, Sun and the phase voltage waveform has a waveform as shown in FIG. 1 2 (a) ~ (c ). The position detection means 5 extracts only the zero-cross information of the induced voltage from this waveform, and uses this as a trigger to create and output rotational position information. The torque control unit 12 outputs a correction voltage value such that the motor output torque τm is substantially equal to τ1 based on the current load torque value τ1 read from the load torque pattern storage unit 15. Further, the PWM signal generation unit 11 generates a PWM control signal for each phase based on the voltage command value, the correction voltage value, and the rotational position information. Thereby generating a current waveform corresponding to the load torque pulsation of the compressor (see Figure 1 3) Suppressing Differences minimize rotational speed variation and vibration of the load torque and motor output torque.
[0010]
[Problems to be solved by the invention]
Since the conventional compressor motor control device is configured as described above, the vibration generated by the compressor 2 equipped with the DC brushless motor 3 includes the vibration of the rotational frequency component of the compressor 2 and the motor. There is vibration of the component of the frequency of phase switching (in the case of a three-phase four-pole motor, a frequency 12 times the compressor rotation frequency).
[0011]
The former is roughly due to load torque fluctuations of the compressor 2 and can be suppressed by open-loop torque control as shown in the conventional example.
But the latter is applied to the motor current decreases during energization phase switching timing of the DC brushless motor (Fig. 1 4 (a), (b )) is due to effectively suppress the vibration in the conventional method of compensating for only the load torque pulsation Could not be done (see FIG. 15 ).
Many methods have been proposed for suppressing only the latter vibration, but the former vibration cannot be suppressed at the same time.
[0012]
In addition, torque control of the conventional device controls the output current so as to cancel the load torque pulsation, so that current pulsation is generated in synchronization with the mechanical rotation cycle. However, when the current pulsates, the circuit resistance loss that is proportional to the square of the current increases. Therefore, the circuit efficiency deteriorates. Depending on the usage environment of the device, power efficiency may be required rather than vibration, but the conventional apparatus cannot meet such a requirement.
[0013]
The present invention has been made to solve the above-described problems, and is a control device for a compressor motor that can suppress vibration due to load torque and vibration due to output torque ripple without adding a new device. The purpose is to obtain.
[0014]
It is another object of the present invention to provide a compressor motor control device that can suppress both vibration due to load torque and vibration due to output torque ripple without adding a new device.
[0015]
It is another object of the present invention to obtain a compressor motor control device that meets two different user demands for energy saving and noise reduction.
[0016]
[Means for Solving the Problems]
Control device of a compressor for a motor according to this invention includes an inverter for driving the DC brushless motor built in the compressor, and a voltage detecting means for detecting the terminal voltage of the armature winding of the DC brushless motor, Based on the voltage information output from the voltage detection means, the inverter average output is based on the rotational position detection means for calculating the rotational position of the DC brushless motor and outputting the rotational position information, and the rotational position information and the rotational speed command information given from the outside. A speed control unit that creates a voltage command value or an average output current command value , a current conversion value IL (θ) for the pulsation of the compression load torque for each compressor rotation phase θ, and a pulsation compensation amount for the DC brushless motor output torque A pulsation torque pattern storage unit storing addition data IL (θ) + Ima (θ) with the current converted value Ima (θ), and a rotational position detection means The current compressor rotational phase θ is input from the rotational position information, the value of IL (θ) + Ima (θ) at the rotational phase θ is read from the pulsation torque pattern storage unit, and a value obtained by multiplying this value by a constant is corrected current value or The torque control unit that outputs the correction voltage value, and the instantaneous current command value or instantaneous voltage command value obtained by adding the average output voltage command or average output current command calculated by the speed control unit to the correction current value or correction voltage value A PWM signal generating unit that calculates a PWM control signal based on the input instantaneous current command value or instantaneous voltage command value and the rotation phase θ; and a driver unit that controls the inverter based on the PWM control signal. Features.
[0017]
The compressor motor control device according to the present invention includes a man-machine interface unit that commands torque control ON / OFF, and the torque control unit outputs a torque control ON / OFF signal of the man-machine interface unit. When the signal is ON, the correction current value or the correction voltage value is output.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
A compressor motor control apparatus according to Embodiment 1 of the present invention will be described below with reference to the drawings. 1 is a configuration diagram of a control device for an electric motor for a compressor according to Embodiment 1 of the present invention. The same or corresponding parts as those of the conventional apparatus are denoted by the same reference numerals, and description thereof is omitted.
[0019]
In FIG. 1, reference numeral 6 denotes a pulsation torque pattern storage means, which is a current conversion value IL (θ) of a pulsation component τ1 (θ) of a compression load torque for each compressor rotation phase and a pulsation compensation component τma (θ) of a motor output torque. Is stored as addition data IL (θ) + Ima (θ) of the current conversion value Ima (θ). The current drop at the time of phase switching is determined by the inductance value L, resistance value R, and (bus voltage-induced voltage) value E of the motor, so that current data Ima (θ) for motor output torque correction (FIG. 2A) ) Is a value that compensates for the amount of current drop.
[0020]
That is, the rising portion Ir * in FIG. 2 ^(a), the time T switch to state falls from partial If ^* and rising states Falling becomes the following relationship between the phase-change-time and t = 0.
Ir ^* = E / R * exp (−R * t / L)
If ^* = E / R * exp (−R * t / L)
T = L / R * 1n (2)
[0021]
An example of data stored in the pulsating torque pattern storage means 6 is shown in FIG. A torque control unit 12 outputs a current correction value that outputs an output torque τm corresponding to the load torque τ1 in the current phase.
[0022]
Next, the operation will be described. The torque controller 12 first inputs the current rotational phase θ, and reads the value of IL (θ) + Ima (θ) at the phase θ from the pulsating torque storage means 6. A value obtained by multiplying this value by a constant is output as a correction current value or a correction voltage value. The correction value is added to the average output voltage command or the average output current command calculated in the speed control unit 8 and input to the PWM signal generation unit 11 as an instantaneous current command value or an instantaneous voltage command value.
[0023]
The PWM signal generator 11 creates a PWM signal from the instantaneous current command value or instantaneous voltage command value and the current rotational phase θ. By the above operation, the output torque of the inverter in each rotation phase becomes equal to the compressor load torque, and the speed fluctuation during one rotation due to the load torque pulsation and the output torque pulsation is suppressed . FIG. 3 shows a speed fluctuation waveform during one rotation in the present embodiment and the conventional control device.
[0024]
In the figure, (1) is the load torque fluctuation of the compressor, (2) is the rotational speed fluctuation when torque control is not applied, (3) is the rotational speed fluctuation in this embodiment, and (4) is the rotation in the conventional apparatus. It is speed fluctuation. As shown in the figure, the speed fluctuation caused by the output torque ripple generated in the conventional method is suppressed in this method, so that the vibration due to this is also reduced. Moreover, since it can adapt by the update of the memory content of a torque pattern memory | storage part as a change point from the past, it is realizable easily from a conventional apparatus.
[0025]
Embodiment 2. FIG.
A compressor motor control apparatus according to Embodiment 2 of the present invention will be described below with reference to the drawings. FIG. 4 is a block diagram of a compressor motor control apparatus according to Embodiment 2 of the present invention. In the figure, reference numeral 14 denotes an overlap PWM signal creation unit for creating an inverter control signal at a conduction angle exceeding 120 degrees.
[0026]
Next, the operation 5, 6 will be described with reference to FIG. FIG. 7 is a table showing the operation of the overlap PWM signal generator 14 when the overlap (phase in which all phases are energized) angle is 30 electrical degrees, for example. And phase information overlap PWM signal generator 14 supplied from the position detection means 5, an electrical angle of Figure 7 with a built - determining a control pattern of the inverter each switch based on the switching pattern corresponding information. In FIG. 7, the section where current is applied to all six U, V, and W phases at an electrical angle of 30 degrees per point (the thick frame in FIG. 7 ) is an overlap to compensate for the current drop during phase switching. It is an energized section.
[0027]
An example of the pattern of the PWM signal based on a sequence of FIG. 5 is shown in FIG. In the above example, the overlap portion is an angle (electrical angle 30 degrees), but the overlap is preferably a time value. In the case of the conventional PWM system (turn-on and turn-off timing are simultaneous, dotted line portion in FIG. 5 ), the timing at which the total current at the time of phase switching is minimized is a predetermined time T (= L / R * 1n (2), L : Motor winding inductance, R : Motor winding resistance) The elapsed time. Therefore, a suitable setting value for the overlap angle is a phase angle corresponding to a time obtained by multiplying the predetermined time T by approximately ½.
[0028]
FIG. 5 shows PWM control signals, phase currents, and output torque waveforms in the conventional system and the present system. The dotted line indicates the conventional energization (conduction angle of 120 degrees), and the solid line indicates the case of the overlap energization. . In this method, a drop in the output torque can be avoided by delaying the turn-off phase due to the influence of the turn-off current delay at the time of phase switching.
[0029]
On the other hand, the correction of the output torque with respect to the load torque pulsation is performed by the correction output of the torque control unit 12 as in the conventional example. The speed fluctuation waveform when the control of this embodiment is performed is as shown in FIG. 3 as in the first embodiment, and the speed fluctuation is suppressed and the vibration is reduced.
[0030]
Embodiment 3 FIG.
A compressor motor control apparatus according to Embodiment 3 of the present invention will be described below with reference to the drawings. FIG. 8 is a block diagram of a compressor motor control apparatus according to Embodiment 3 of the present invention. In the figure, reference numeral 13 denotes a man-machine interface unit such as a remote controller. The man-machine interface unit 13 has a switch for switching between the energy saving mode and the silent mode, and commands the torque control unit 12 to turn off the torque control in the energy saving mode and to turn on the torque control in the silent mode. The torque control unit 12 receives an ON / OFF signal for torque control from the man-machine interface 13, and generates an output torque that cancels out load torque fluctuation during one rotation of the compressor when the signal is ON. Output voltage or current command.
[0031]
On the other hand, when the signal is OFF, the torque control unit 12 sets the correction output to 0, operates so as not to generate current pulsation due to torque control, and operates with high efficiency. By adopting the above-described method, it becomes possible to perform compressor control corresponding to two different demands on the user, such as energy saving and silent operation.
[0032]
【The invention's effect】
Control device of a compressor for a motor according to the invention this is because it has data, such as torque ripple pattern storage unit corrects the ripple component of the ripple component and the output torque of the load torque at the same time, without adding a new device The vibration due to the load torque and the vibration due to the output torque ripple can be effectively suppressed.
[0033]
In addition, the compressor motor control apparatus according to the present invention can control the compressor motor in response to two different user demands for energy saving and noise reduction.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a compressor motor control apparatus according to Embodiment 1 of the present invention;
FIG. 2 is a diagram showing stored data in a pulsation torque pattern storage unit of the compressor motor control apparatus according to Embodiment 1 of the present invention;
FIG. 3 is a diagram showing fluctuations in load torque speed of the compressor motor control apparatus according to Embodiment 1 of the present invention;
FIG. 4 is a configuration diagram of a compressor motor control apparatus according to Embodiment 2 of the present invention;
FIG. 5 is a diagram showing an overlap PWM signal and output torque of a compressor motor control apparatus according to Embodiment 2 of the present invention;
FIG. 6 is a time chart of output signals and phase currents of overlap PWM means of a compressor motor control apparatus according to Embodiment 2 of the present invention;
FIG. 7 is a diagram showing a conversion table between an electrical angle θ and a PWM signal of an overlap PWM signal creation unit of a control device for a compressor motor according to Embodiment 2 of the present invention;
FIG. 8 is a configuration diagram of a compressor motor control device according to Embodiment 3 of the present invention;
FIG. 9 is a block diagram of a conventional compressor motor control device.
FIG. 10 is a diagram showing data stored in torque pattern storage means of a conventional compressor motor control device.
FIG. 11 is a diagram showing a PWM signal of a control device for a conventional compressor motor.
FIG. 12 is a diagram showing a phase voltage waveform of an inverter of a conventional compressor motor control device.
FIG. 13 is a phase current waveform diagram in torque control of a conventional compressor motor control device.
FIG. 14 is a time chart of output signals, phase currents and phase currents of overlap PWM means of a conventional compressor motor control device.
FIG. 15 is a diagram showing load torque and output torque of a conventional compressor motor control device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Inverter, 2 Compressor, 3 DC brushless motor, 4 Voltage detection means, 5 Position detection means, 6 Pulsation torque pattern memory | storage part, 7 Voltage control means, 8 Speed control part, 9 Drive signal generation part, 10 Driver part, 11 PWM signal creation unit, 12 torque control unit, 13 man-machine interface unit, 14 overlap PWM signal creation unit, 15 load torque pattern storage unit.

Claims (2)

An inverter for driving a DC brushless motor built in the compressor;
Voltage detecting means for detecting a terminal voltage of the armature winding of the DC brushless motor;
Based on the voltage information output from the voltage detection means, the rotation position detection means for calculating the rotation position of the DC brushless motor and outputting the rotation position information;
A speed control unit that creates an inverter average output voltage command value or an average output current command value based on the rotational position information and the rotational speed command information given from outside;
Addition data IL (θ) between the current conversion value IL (θ) for the pulsation of the compression load torque for each compressor rotational phase θ and the current conversion value Ima (θ) for the pulsation compensation of the DC brushless motor output torque. A pulsation torque pattern storage unit storing + Ima (θ);
The present compressor rotational phase θ is input from the rotational position information from the rotational position detecting means, and the value of IL (θ) + Ima (θ) at the rotational phase θ is read from the pulsation torque pattern storage unit, and this value is obtained. A torque control unit that outputs a value multiplied by a constant as a correction current value or a correction voltage value;
An instantaneous current command value or an instantaneous voltage command value obtained by adding an average output voltage command or an average output current command calculated in the speed control unit to the corrected current value or the corrected voltage value is input, and this instantaneous current command value or A PWM signal generating unit that calculates a PWM control signal based on the instantaneous voltage command value and the rotational phase θ;
A driver unit for controlling the inverter based on the PWM control signal;
A control device for an electric motor for a compressor, comprising: A man-machine interface unit for instructing ON / OFF of torque control, wherein the torque control unit receives an ON / OFF signal of torque control of the man-machine interface unit, and when the signal is ON, the correction current value or correction 2. The compressor motor control device according to claim 1, which outputs a voltage value.

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