JPS614492A - Torque controller of motor - Google Patents

Abstract

PURPOSE:To enable to vary the rotating speed of a motor in a wide range by reading out a torque pattern in response to a rotor position to control the output torque of a motor, thereby preventing a vibration or a noise. CONSTITUTION:A load torque varying by the rotating angle of a compressor is stored in advance in a torque pattern memory 7-2b, the stored torque data is read out in response to the position of a rotor from a pole position detector 6, and a torque is output from a motor for a compressor on the basis of the torque data. Thus, the difference torque between a load torque TL applied to the motor of the compressor and the output torque TM of the motor decreases, with the result that the rotating pulsation occurred due to the difference torque can be reduced.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a torque control device for an electric motor, and is suitable for varying the rotational speed of an electric motor driven by an inverter and whose load is, for example, a compressor. The present invention relates to a torque control device for an electric motor.

[Background of the invention]

For example, in recent years, as a method for varying the cooling or heating capacity of a room air conditioner, a method has generally been used in which the rotational speed of a compressor motor is controlled using an inverter.

Therefore, the rotational speed control range of these electric motors is approximately 2000r to 6000r6000r.

If this rotation speed control range is further expanded, the capacity control range of the room air conditioner will be expanded, and heating capacity will be increased for high-speed rotation, and effects such as power saving and low noise will be obtained for low-speed rotation. It is something that can be done.

However, when lowering the rotation speed to about 1000r111 or less, conventional vibrations occur due to the following reasons.

This increased noise and made it difficult to put it into practical use.

In other words, compressors used in room air conditioners and refrigerators are generally sealed in a chamber together with a driving electric motor, and the load torque applied to the compressor electric motor is greater than that of a rotary compressor or Renpro compressor. In any case, it pulsates greatly with respect to the rotation angle', and the maximum load torque reaches approximately three times the average load torque.

Here, FIG. 6 shows changes in the load torque TL%, the output torque TM of the motor, and the rotational speed N with respect to the rotation angle of the motor.

The load torque TL is the output torque TM, J:,! l) In the rotational angle region between the dashed lines shown in the figure, where the rotational angle increases, angular acceleration occurs due to the deceleration of the rotational speed N, and rotational inertia torque expressed as the product of the moment of inertia J of the rotating shaft system of the electric motor is generated. and the output torque TM are matched with the load torque TL.

On the other hand, rotational inertia torque is generated due to the increase in rotational speed on both sides of the broken line shown in the figure, which is the rotational angle region of T and TM. That is, by generating rotational inertia torque according to the torque difference between Ty and TL, the electric motor on the output side and the compressor as the load side. Between a, f-tvp. equilibrium,
8k. In other words, in an electric compressor, rotational pulsation occurs during one rotation, which causes vibrations and further noise throughout the compressor chamber.

In particular, when operating an electric motor to a low speed range, as the rotational speed decreases, the amplitude of rotational pulsation increases for the same angular acceleration as at high speed, and the frequency of the rotational pulsation also decreases. . .

The vibrations caused by this also have a large amplitude and a low vibration frequency in accordance with the rotational pulsation.

Therefore, conventionally, in order to expand the rotational speed range of a compressor electric motor toward lower speeds, vibration and noise are louder and louder.
Due to the large size of soundproofing devices, it has been difficult to achieve this on a practical level.

[Purpose of the invention]

The present invention is applicable to a room air conditioner, a refrigerator, etc., in which cooling or heating capacity is controlled by varying the rotation speed of an electric compressor, and the capacity control range is set to the low capacity side.
In other words, it is possible to vary the rotation speed of the electric motor that is driven by the inverter to drive the load over a wide range, including making it possible to prevent the vibration and noise that were problems in the past even if the rotation speed is extended to the low rotation speed side. The object of the present invention is to provide a torque control device for an electric motor.

[Summary of the invention]

The configuration of the torque control device for an electric motor according to the present invention is such that the load driving device includes an electric motor that drives a load and an inverter that supplies AC power to the electric motor, and a rotor position that detects the position of the rotor of the electric motor. A detection circuit and a torque pattern storage section that stores a load torque pattern per revolution of the electric motor are provided, and the torque pattern storage section stores the load torque pattern in advance in the torque pattern storage section in response to an output signal from the rotor position detection circuit. A control circuit is provided which reads out the torque pattern of the electric motor and controls the output torque of the electric motor based on the read out torque pattern.

Further details are as follows.

In view of the mismatch between the load torque and the output torque with respect to the rotation angle, which is the cause of vibration and noise that becomes particularly large in the low-speed region, the present invention aims to adjust the output torque so that the output torque of the electric motor matches the load torque. The specific method is to read the load torque data according to the rotational position from a medium in which the load torque per revolution is stored in advance, and based on this read data. It is designed to output torque from an electric motor.

[Embodiments of the invention]

Embodiments of the torque control device for an electric motor according to the present invention will be described with reference to FIGS. 1 to 5.

FIG. 1 is a configuration diagram of a torque control device for an electric motor according to an embodiment of the present invention, and FIG. 2 is a detailed diagram of the torque control section thereof.
FIG. 3 is an explanatory diagram of its operation, FIG. 4 is a configuration diagram of main parts of a torque control device for an electric motor according to another embodiment of the present invention, and FIG.
The figure is an explanatory diagram of the operation.

Therefore, each of the embodiments is an embodiment in which the motor is applied to a brushless DC motor related to a compressor motor.

- That is, first of all, FIG. 1 shows the overall configuration of a torque control device for a brushless DC motor.

A DC voltage E is obtained from the illustrated AC power supply 1 through a rectifier circuit 2 and a smoothing capacitor 3, and is supplied to an inverter 4.

This inverter 4 is a 120° conduction type inverter composed of transistors TR1 to TR6 and free-wheeling diodes D1 to D6, and its AC output voltage is a DC voltage E.
, 120° of the positive potential side transistors T Rs to TR3
The conduction period of the filter is controlled by chopper operation under pulse width modulation.

Furthermore, a low resistance Rs is connected between the common emitter terminals of the transistors TR4 to TR6 and the common anode terminals of the freewheeling diodes D4 to D6.

5 relates to a brushless DC motor in the compressor section;
It consists of a synchronous motor 5-1 whose field is a two-pole permanent magnet, and a compressor 5-2 as its load. 7a 6゜
The winding current flowing through the armature winding of the synchronous motor 5-1 also flows through the low resistance R1, and the winding current IL can be detected as a voltage drop across the low resistance R1.

A control circuit configured to control the output torque of the synchronous motor 5-1 includes a microcomputer 7 and a synchronous motor 5-1.
The magnetic pole position detection circuit 6 is a rotor position detection circuit that detects the magnetic pole position of the rotor, and a torque control device driver 9 that controls the torque of the synchronous motor 5-1.

The magnetic pole position detection circuit 6 described above is disclosed in Japanese Patent Application Laid-Open No. 52-80415.
As disclosed in the publication, this is a circuit that uses a filter circuit to generate a position detection signal 6s corresponding to the rotor position from the line terminal voltages VA to Vc of the armature of the synchronous motor 5-1.

Mata, the microcomputer 7 mentioned above is the CPU7-1
．． It is composed of a ROM 7-2, a RAM 7-3, etc., and is connected to each other by an address bus, a data bus, and a control bus (not shown).

The ROM 7-2 is located at the rotor position of the synchronous motor 5-1 and the main memory 7-2a in which various processing programs necessary for driving the synchronous motor 5-1 related to the brushless DC motor are stored. and a torque pattern storage section 7-2b that stores corresponding torque data.

The torque control section 8 controls the winding current based on the torque data 11 outputted from the torque pattern storage section 7-2b of the micro convenience store according to the rotor position.

That is, in a brushless DC motor, the winding current flowing through the armature winding corresponds to the output torque of the motor, and by controlling the winding current, the output torque can be controlled.

FIG. 2 shows details of the torque control section 8 described above, including a D/A converter 12 as a current command circuit, an amplifier 13 as a current detection circuit, and a comparator as a comparison circuit having hysteresis characteristics. It consists of 14 parts.

Torque pattern storage section 7-2 of microcomputer 7
The 8-bit torque data 11 read from b is converted into an analog quantity by the D/A converter 12,
This is the current command value 11a shown in the figure.

The winding current IL obtained as a voltage drop across the low resistance R1 is amplified by the amplifier 13 to become the current detection value V r L shown in the figure, which is compared with the current command value 11a by the comparator 14, and 1
A chopper signal 10 is formed as an output of the inverter 4, and is used to switch the transistors TRI to TR3 forming the inverter 4.

FIG. 3 is a time chart from the position detection signal 6S to the creation of the chopper signal 10.

The position detection signal 6S indicating the magnetic pole position of the rotor in FIG.
ooa-r-0'' mode 0111/190° - From mode I to mode ■, it is divided into six modes with one rotation every 60 degrees.

For each of these modes, the torque pattern storage section 7-
The six 8-bit torque data stored in 2a are
It is read out according to each mode and outputted from the microcomputer 7.

The output torque data 11 is converted into a current command value 11a by the D/A converter 12, as shown in FIG. 3(2).

Then, as described above, the detected current value V I L and the current command value 11a are compared, the chopper signal 10 shown in (3) in the same figure is created, and the winding current IL corresponds to the current command value. It is controlled by the waveform.

The torque data to be stored in advance in the torque pattern storage section 7-2a is data that simulates the load torque T+ (see FIG. 6 above) that changes depending on the rotation angle of the compressor 5-2 every 60 degrees. Accordingly, in the embodiment of the present invention described above, the output torque TM of the synchronous motor 5-1 is produced in accordance with the load torque T of the compressor.
The synchronous electric motor has two poles, and the mechanical position of the rotor is determined from the terminal voltage V A " V c, and the output torque of the motor is changed according to this position according to the load torque of the compressor. With this configuration, an effect can be expected in which a sensor such as a Hall element inside the compressor section 5 is completely unnecessary to detect the mechanical position of the rotor.

However, when the synchronous motor is a four-pole machine, the rotor mechanically rotates only once for two periods of the position detection signal 6S of the magnetic pole position of the rotor, so the position detection signal 6S
does not correspond to the mechanical position of the rotor.

In this regard, another embodiment of the present invention will be described using FIGS. 4 and 5.

The difference from the above-mentioned embodiment described using FIGS. 1 to 3 is that the synchronous motor is a four-pole motor, and the reference position of the synchronous motor during one rotation can be detected. That's how it is.

Therefore, FIG. 4 mainly shows the main parts that are different from the embodiment shown in FIG.
-3 is a chamber of an electric compressor, 5A is a compressor section, and inside the chamber 5-3, a 4-pole interphase electric motor 15 is installed.
and the compressor 5-2 are hermetically sealed.

Reference numeral 17 denotes a position detection circuit, which includes a magnetic pole position detection circuit 17-1 for detecting the magnetic pole position of the rotor, and a reference position detection circuit 17-2 for detecting the reference position of the rotor. The circuit 17-1 has the same configuration as the magnetic pole position detection circuit 6 shown in FIG. 1 above.

The reference position detection circuit 17-2 includes a chamber 5-3.
The output signal 16S of the vibrating pick tap 16 attached to the chamber 5-3 to detect the vibration of the chamber 5-3 is input, and the reference position signal 17-28 is formed based on this output signal 16S and transmitted to the microcomputer 7. be.

RO that constitutes the microcomputer 7 explained earlier
Of the M7-2, the torque pattern storage section 7-2b includes:
Torque data consisting of 12 modes is stored in advance for each rotation of the rotor.

Figure 5 shows the magnetic pole position detection signal 17-ISC (1) in the same figure.
], the output signal 165 of the vibration pickup 16 [(
2)], the reference position signal 17-2S which is the output of the reference position detection circuit 17-2 [(3) in the same figure], and the current obtained by D/A converting the torque data output from the microcomputer 7. The command value 11a and the detected current value Vrt are shown [(4) in the figure].

The vibration of the chamber 5-3 occurs during the compression stroke of the compressor.
Since the compressed volume has the characteristic that it is maximum at the time when the compressed volume is minimum, or in other words, the load applied to the synchronous motor is maximum, the output signal 16S of the vibration pickup 16 is as shown in (2) in FIG. One peak value is expressed per revolution.

Based on this signal 163, the reference position detection circuit 17-2
Then, form the reference position signal 17-23 of the same figure (3),
This reference position signal 1 is input to the microcomputer 7.
At the time when the 7-28 pulse signal is generated, the torque de? - In the evening, the torque data of the maximum level is read out from the torque pattern storage section 7-2b and outputted from the microcomputer 7.

After that, the torque data is sent to the magnetic pole position detection signal 17-I.
By sequentially reading out from the torque pattern storage section 7-2b according to s, one torque putter /
is output from the microcomputer 7.

According to the embodiments described above, the present invention can be applied to a four-pole interphase motor, and the reference position of the rotor can still be detected using a vibration pickup located outside the chamber. By doing so, there is no need to provide a sensor inside the chamber, which is subject to high temperatures, and there is an effect that high reliability can be obtained.

According to each of the above embodiments, the load torque that changes depending on the rotation angle of the compressor is stored in the torque pattern storage section in advance, and the stored torque data is read out according to the position of the rotor. , this read hk'rivly'-
Based on IK, "ta1"' is configured to be output from the compressor motor, so the difference torque between the load torque T applied to the compressor motor and the output torque TM of the motor is As a result, the rotational pulsation caused by the differential torque is reduced.

This makes it possible to obtain an electric compressor with less vibration even if the compressor electric motor is expanded to a low rotation speed region of 1.000 rVm or less.

Although each of the above-mentioned embodiments describes a planless DC motor related to a compressor motor as an electric motor, the present invention is not limited to this. This is a general-purpose device that can be used as a torque control device for an electric motor that drives a load whose load torque changes during rotation, and whose change value can be known in advance.

〔Effect of the invention〕

According to the present invention, it is possible to obtain an electric motor torque control device that is suitable for changing the rotation speed of a load-driven electric motor driven by an inverter over a wide range, and is an invention that has excellent practical effects. I can do it.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a torque control device for an electric motor according to an embodiment of the present invention, and FIG. 2 is a detailed diagram of the torque control section thereof.
FIG. 3 is an explanatory diagram of its operation, FIG. 4 is a configuration diagram of a torque control device for an electric motor according to another embodiment of the present invention, FIG. 5 is an explanatory diagram of its operation, and FIG. FIG. 3 is an explanatory diagram showing changes in load torque, output torque of an electric motor, and rotation speed with respect to rotation angle. DESCRIPTION OF SYMBOLS 1... AC power supply, 2... Rectifier circuit, 3... Smoothing capacitor, 4... Inverter, 5.5A... Compressor section, 5-1=±mi... Synchronous motor, 5 -2...Compressor, 5-3...Chamber, 6...Magnetic pole position detection circuit, 7...Microcomputer, 7-1...CPU
, 7-2...ROM, 7-2a...main memory section, 7-
2b...Torque pattern storage section, 7-3...RAM
, 8... Torque control section 9... Pace driver 1
2...D/A converter, 13...amplifier, 14...
Comparator, 15...4-pole interphase motor, 16...
Vibration pickup, 17...Position detection circuit, 17-1
...Magnetic pole position detection circuit, 17-2...Reference position detection circuit. 1st mouth 3rd eye 4th eye, f-3

Claims (5)

[Claims] 1. In a load driving device consisting of an electric motor that drives a load and an inverter that supplies AC power to this electric motor,
A rotor position detection circuit that detects the position of the rotor of the electric motor, and a torque pattern storage section that stores a load torque pattern per rotation of the electric motor,
A torque pattern stored in advance in the torque pattern storage section is read in response to an output signal from the rotor position detection circuit, and the output torque of the electric motor is controlled based on the read torque pattern. 1. A torque control device for an electric motor, characterized in that a control circuit is provided. 2. In the motor set forth in claim 1, the motor is a synchronous motor having a permanent magnet in its rotor, and the rotor position detection circuit is a circuit for detecting the magnetic pole position of the permanent magnet of the rotor. A torque control device for an electric motor. 3. 3. A torque control device for a motor according to claim 2, wherein the rotor position detection circuit is a circuit that detects a magnetic pole position from an input terminal voltage of the motor. 4. In the device described in claim 1, the control circuit configured to control the output torque of the motor includes a current detection circuit for detecting a current flowing through the motor, a current command circuit, and a detected current and a command current. A torque control device for an electric motor, which is provided with a torque control section consisting of a comparison circuit for comparing. 5. A torque control device for an electric motor according to claim 1, wherein the rotor position detection circuit includes a reference position detection circuit for detecting a reference position of the rotor during one revolution.