JPH069439B2 - Electric motor torque control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a torque control device for an electric motor, which is suitable for widely changing the rotational speed of an electric motor driven by an inverter and which loads a compressor. The present invention relates to a torque control device for an electric motor.

BACKGROUND OF THE INVENTION For example, as a method for varying the cooling or heating capacity of a room air conditioner, in recent years, a method in which the rotation speed of a motor for a compressor is controlled and changed by an inverter has been generally used.

Therefore, the speed control range of these electric motors is about
It is about 2000 rpm to 6000 rpm.

If this speed control range is further expanded, the capacity control range of the room air conditioner will be expanded, and the heating capacity will be increased for high speed rotation, or power saving, low noise and low speed rotation effects will be obtained. Is obtained.

However, with respect to the low speed rotation of about 1000 rpm or less, conventionally, due to the following reasons, noise and noise increased, and it was difficult to put into practical use.

That is, a compressor used in a room air conditioner or a refrigerator is generally of a structure in which it is sealed in a chamber together with a driving electric motor, and the load torque applied to the electric motor of the compressor is the same as that of a rotary compressor or a reciprocating compressor. Regardless of which one, there is a large pulsation 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 T _L , the output torque T _M of the electric motor, and the rotation speed N with respect to the rotation angle of the electric motor.

In the rotation angle region between the broken lines in the figure in which the load torque T _L becomes larger than the output torque T _M , angular acceleration is generated by deceleration of the rotation speed N, and is represented by the product of the inertia moment J of the rotating shaft system of the electric motor. The generated rotational inertia torque is generated, and this and the output torque T _M are balanced with the load torque T _L.

On the other hand, on the both sides of the broken line in the drawing, which is the rotation angle region of T _L <T _M , the rotational inertia torque based on the increase in the rotation speed is generated. That is, torque inertia is maintained between the electric motor on the output side and the compressor on the load side by generating the rotational inertia torque according to the Tokule difference of T _M -T _L.

In other words, in the electric compressor, rotation pulsation occurs during one rotation, which causes vibration and noise in the entire compressor chamber. In particular, when the electric motor is driven to a low speed range, the rotational pulsation amplitude decreases as the rotational speed decreases, and the rotational pulsation frequency decreases for the same angular acceleration as at high speed. .

Then, the vibration caused by this also has a large amplitude according to the rotation pulsation, and the vibration frequency also decreases.

Therefore, conventionally, in order to expand the rotation speed range of the compressor electric motor in the low speed direction, vibration and noise were violent, and the vibration proof and sound proof measures became large in size, which was difficult to achieve at a practical level. .

[Object of the Invention]

The present invention, for example, a room air conditioner, a refrigerator, or the like, which controls the capacity related to cooling or heating capacity by varying the rotation speed of an electric compressor, has a capacity control range on the low capacity side,
In other words, even if it is expanded to the low rotation speed side, it is possible to change the rotation speed of the electric motor driven by the inverter to drive the load in a wide range, including the prevention of vibration and noise, which has been a problem in the past. It is an object of the present invention to provide a Luc control device for an electric motor.

[Outline of Invention]

The present invention includes a synchronous motor that uses a permanent magnet as a field for driving a compressor load device, and an inverter that supplies AC power to the synchronous motor, and a torque pattern that stores a load pattern per one rotation of the electric motor. In a torque control device for an electric motor having a storage unit, a timing generation unit for inputting an input terminal voltage of the electric motor and outputting a timing signal for every 60 degrees in electrical angle, and a current detection unit for detecting a current flowing through the electric motor. And a current control unit that matches the detected current with a current command, the torque pattern storage unit is configured by the same number of storage elements as the number of rotations of the timing signal, and according to the switching timing of the timing signal. , A circuit configuration that sequentially calls the data of the storage element and creates a current command from the called data. It is an butterfly.

Example of Invention

Each embodiment 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 a torque control unit thereof.
FIG. 3 is an operation explanatory view thereof, and FIG. 4 is a main part configuration diagram of a torque control device for an electric motor according to another embodiment of the present invention.
The figure is a diagram for explaining the operation.

Therefore, each of the embodiments relates to an embodiment applied to a brushless DC electric motor related to a compressor electric motor as an electric motor.

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

A DC voltage _Ed is obtained from the rectifier circuit 2 and the smoothing capacitor 3 from the AC power supply 1 shown in the figure, and is supplied to the inverter 4.

The inverter 4 is a 120 ° energization inverter comprising the transistors _TR 1 to Tr ₆ and the reflux diode _D 1 to D ₆ Tokyo, the AC output voltage is a DC voltage _{E d}
The 120 ° conduction period of the positive potential side transistors TR _{1 to} TR ₃ is controlled by the pulse width modulation and the chipper operation.

Moreover, in which low resistance _{R 1} is connected between the common anode terminal of the common emitter terminal of the transistor _TR 4 to Tr ₆ and the reflux diode _D 4 to D _6.

5 is a compressor section, which relates to a brushless DC electric motor,
It is composed of a synchronous motor 5-1 having a two-pole permanent magnet as a field and a compressor 5-2 having a load thereof.

Winding current flowing through the armature winding of the synchronous motor 5-1, wherein the well flow to a low resistance R _1, the voltage drop of the low-resistance R _1, in which the winding current I _L can be detected.

The control circuit for controlling the output torque of the synchronous motor 5-1 includes a microcomputer 7 and a synchronous motor 5-1.
Magnetic pole position detection circuit 6 related to the rotor position detection circuit for detecting the magnetic pole position of the rotor, the torque control unit 8 for controlling the torque of the synchronous motor 5-1 and the transistors TR _{1 to} TR _6.
The base driver 9 for

The magnetic pole position detection circuit 6 is rotated by using a filter circuit from the armature winding terminal voltages V _{A to} V _C of the synchronous motor 5-1 as disclosed in Japanese Patent Application Laid-Open No. 52-80415. It is a circuit that forms a position detection signal 6S corresponding to the child position.

The microcomputer 7 is composed of a CPU 7-1, a ROM 7-2, a RAM 7-3, etc., which are respectively connected by an address bus, a data bus and a control bus (not shown).

The ROM 7-2 is provided at the rotor position of the main motor 7-2a and the synchronous motor 5-1 in which various processing programs required to drive the synchronous motor 5-1 related to the brushless DC motor are stored. The torque pattern storage unit 7-2b stores corresponding torque data.

The torque control unit 8 controls the winding current based on the torque data 11 output from the torque pattern storage unit 7-2b of the microcomputer 7 according to the rotor position.

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

FIG. 2 shows the details of the torque control unit 8 described above, which has a D / A converter 12 as a current command circuit, an amplifier 13 as a current detection circuit, and a hysteresis characteristic.
It is composed of a comparator 14 as a comparison circuit.

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

Then, the winding current I _L obtained as the voltage drop of the low resistance R ₁ is amplified by the amplifier 13 and becomes the illustrated current detection value V _IL , which is compared by the comparator 14 with the current designated value 11a, A checker signal 10 is formed as an output of the comparator 14 and switches the transistors TR ₁ to TR ₃ forming the inverter 4.

FIG. 3 is a time chart from the position detection signal 6S to the production of the above-mentioned checker signal 10.

Position detection signal 6 representing the rotor magnetic pole position in FIG.
S represents the mechanical position of the rotor because the synchronous motor 5-1 is a two-pole machine.
It is divided into 6 modes by rotating once every 60 °.

For each of these modes, the torque pattern storage unit 7-
The six 8-bit torque data stored in 2a are
It is read according to each mode and is output 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 _IL and the current command value 11a are compared with each other to generate the checker signal 10 shown in FIG. 3C, and the winding current I _L corresponds to the current command value. It is controlled by the waveform.

As the torque data stored in advance in the torque pattern storage unit 7-2a, the load torque _TL (FIG. 6 above) which changes depending on the rotation angle of the compressor 5-2 is simulated every 60 °. Thus, the output torque T _M of the synchronous motor 5-1 is output in correspondence with the load torque T _L of the compressor.

In the embodiment of the present invention described above, the synchronous motor has two poles, and the mechanical position of the rotor is set to the terminal voltages V _{A to} V _C.
The output torque of the electric motor is changed according to the load torque of the compressor in accordance with this position. Therefore, in order to detect the mechanical position of the rotor, there is a hole inside the compressor unit 5. It is possible to expect an effect that a sensor such as an element is completely unnecessary.

If the synchronous motor is a four-pole machine, the rotor mechanically makes only one rotation for two cycles of the position detection signal 6S of the magnetic pole position of the rotor.
Does not correspond to the mechanical position of the rotor.

In connection with this point, another embodiment of the present invention will be described with reference to FIGS.

The difference from the above-described embodiment described with reference to FIGS. 1 to 3 is that the synchronous motor is a four-pole machine, and the reference position can be detected during one revolution of the synchronous motor. It was done like this.

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

A position detection circuit 17 is composed of 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 detection circuit 17-1 has the same configuration as the magnetic pole position detection circuit 6 shown in FIG.

The reference position detection circuit 17-2 includes a chamber 5-3.
The output signal 16S of the vibration pick-up 16 which is attached to the sensor 5-3 and detects the vibration of the chamber 5-3 is input, and the reference position signal 17-2S is formed based on the output signal 16S and is transmitted to the microcomputer 7. .

RO that constitutes the microcomputer 7 described above
Of the M7-2, the torque pattern storage unit 7-2b has
Tokru data consisting of 12 modes is stored in advance for each rotation of the rotor.

FIG. 5 shows the magnetic pole position detection signal 17-1S [of FIG.
(1)], the output signal 16S of the vibration pick-up 16 [(2) in the figure], the reference position signal 17-2S output from the reference position detection circuit 17-2 [(3) in the figure], and the microcomputer 7 Current command value 11a and current detection value V _IL obtained by D / A converting the torque data output from
(4)] is shown.

The vibration of the chamber 5-3 is due to the compression stroke of the compressor.
The output signal 16S of the vibration pick-up 16 has a characteristic that the load applied to the synchronous motor becomes maximum when the compression volume becomes the minimum, in other words, as shown in (2) of FIG. One peak value is represented per revolution.

Based on this signal 16S, the reference position detection circuit 17-2
Then, the reference position signal 17-2S shown in FIG. 3C is formed and input to the microcomputer 7.
-At the time point when the -2S pulse signal is generated, of the torque data having 12 modes, the maximum level torque data is read from the torque pattern storage unit 7-2b,
It is output from the microcomputer 7.

After that, the torque data is sent to the magnetic pole position detection signal 17-1.
According to S, one torque pattern is output from the microcomputer 7 per one rotation by sequentially reading from the torque pattern storage unit 7-2b.

According to the embodiments described above, the present invention can be applied to the four-station synchronous motor, and the reference position of the rotor can be detected by using the vibration pick-up from the outside of the chamber. As a result, there is no need to provide a sensor inside the chamber that becomes hot, and there is an effect that high reliability can be obtained.

According to each of the above-described embodiments, the load torque that changes depending on the rotation angle of the compressor is stored in the torque pattern storage unit in advance, the stored torque data is read out according to the position of the rotor, and this reading is performed. Since the torque based on the output torque data is output from the compressor electric motor, the difference torque between the load torque T _L applied to the electric motor of the compressor and the output torque T _M of the electric motor is reduced. However, as a result, there is an effect that the rotational pulsation generated by the differential torque is reduced.

As a result, even if the compressor motor is expanded to a low speed rotation range of 1,000 rpm or less, an electric compressor with less vibration can be obtained.

Although the above-mentioned embodiments relate to the brushless DC electric motor related to the electric motor for the compressor as the electric motor, the present invention is not limited to this. The load torque changes, and moreover,
It can be used as a torque control device for an inverter drive motor that drives a load whose change value can be known in advance.

〔The invention's effect〕

According to the present invention, it is possible to obtain a torque control device for an electric motor, which 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 with excellent practical effects. You can

[Brief description 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 a torque control unit thereof.
FIG. 3 is an operation explanatory view thereof, 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 operation explanatory view thereof, and FIG. It is explanatory drawing which shows the load torque, the output torque of an electric motor, and the change of rotation speed with respect to a rotation angle. 1 ... AC power supply, 2 ... rectifier circuit, 3 ... smoothing capacitor, 4
... Inverter, 5, 5A ... Compressor section, 5-1 ... Synchronous electric motor, 5-2 ... Compressor, 5-3 ... Chamber, 6 ... Magnetic pole position detection circuit, 7 ... Microcomputer, 7-1 ... CPU, 7 -2 ... ROM, 7
-2a ... main storage unit, 7-2b ... torque pattern storage unit,
7-3 RAM, 8 torque controller, 9 base driver, 12 D / A converter, 13 amplifier, 14 comparator, 15 4-pole synchronous motor, 16 vibration pickup, 17 position detection circuit , 17-1 ... Magnetic pole position detection circuit, 17-2 ... Reference position detection circuit.

Claims (2)

[Claims] 1. A torque for storing a load pattern per revolution of the electric motor, which comprises a synchronous electric motor having a permanent magnet as a field for driving a compressor load device and an inverter for supplying AC electric power to the synchronous electric motor. In a motor torque control device including a pattern storage unit, a timing generation unit that inputs a voltage of an input terminal of the motor and outputs a timing signal every 60 degrees in electrical angle, and a current detection unit that detects a current flowing through the motor. And a current control unit that matches the detected current with a current command, the torque pattern storage unit is configured by the same number of storage elements as the number of rotations of the timing signal, and the torque pattern storage unit is configured according to the switching timing of the timing signal. And sequentially calling the data in the storage element, and creating a current command from the called data. Torque control device for an electric motor, characterized. 2. A torque control device for an electric motor according to claim 1, further comprising: a position detection unit for generating a reference signal for one pulse of one rotation of the rotor, and a signal generation timing of this position detection unit. And a torque control device for an electric motor having a circuit configuration for creating a current command from data of one specific storage element of the torque pattern storage section.