KR101550751B1 - Motor control device, motor drive device using the same, compressor, refrigeration device, air conditioner, and motor control method - Google Patents

Abstract

An object of the present invention is to appropriately suppress demagnetization of a permanent magnet of a motor while stably driving the motor.
As a means for solving such a problem, a motor control device (not shown) for converting the DC voltage input to the inverter 300 from the DC power supply 200 to an AC voltage and controlling the driving of the motor M connected to the inverter 300 The temperature of the motor M detected by the motor temperature detector 500 is lower than the temperature of the potato of the motor M. [ Current fluctuation suppressing control for suppressing current fluctuation of the motor (M) is performed when the first predetermined value is equal to or smaller than the first predetermined value determined based on the characteristic of the motor (M).

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control apparatus, a motor driving apparatus, a compressor, a refrigerating apparatus, an air conditioner, and a motor control method using the motor control apparatus,

The present invention relates to a motor control apparatus, a motor drive apparatus using the same, a compressor, a refrigerating apparatus, an air conditioner, and a motor control method.

It is known that when the motor installed in the compressor rotates, a torque fluctuation occurs periodically in the motor in accordance with the natural frequency of the compressor. When such torque fluctuation occurs, vibration or noise is generated in the compressor, and therefore it is required to suppress the torque fluctuation.

As a technology for coping with the above problem, for example, Patent Document 1 discloses a technique of performing torque fluctuation suppression control when the load variation is large during low-speed rotation and current fluctuation suppression control during normal operation .

Incidentally, the torque fluctuation suppression control is a control for calculating the variation of the load torque of the motor and correcting the current command value so as to cancel the variation. The current fluctuation suppression control is a control for calculating the variation of the motor current flowing through the motor and correcting the current command value so as to cancel the variation.

Japanese Patent Application Laid-Open No. 2007-166690

By the way, the permanent magnet used for the motor may be demagnetized by the operating temperature and the current flowing through the motor (hereinafter referred to as the motor current). On the other hand, "potato" is a phenomenon in which the magnetic moment of the entire magnet decreases due to temperature rise due to the eddy current loss of the magnet and inverse magnetic field caused by the current flowing in the coil.

For example, ferrite permanent magnets have characteristics that are easy to potato (i.e., low-temperature potato characteristics) under a low-temperature environment. Therefore, if a large current is caused to flow in a motor having such permanent magnets in a low-temperature environment, potatoes may occur and the motor may deteriorate.

Incidentally, in recent years, it has become difficult to supply rare metals in a stable manner, and inexpensive ferrite magnets are attracting attention.

The technique described in the above-mentioned Patent Document 1 does not consider the possibility that the motor potato occurs. In addition, when the motor is rotated at a low speed, the torque fluctuation suppression control is performed, but the peak value of the current flowing through the motor (hereinafter, referred to as peak current) is increased.

Then, in the technique described in Patent Document 1, when the motor having the ferrite permanent magnet is used in a low-temperature environment and the motor is continuously driven at low-speed rotation, there is a high possibility that the permanent magnet of the motor will be demagnetized.

Further, in the technique described in Patent Document 1, the following problems arise even when the permanent magnet of the ferrite system is used in the motor to suppress the potato of the motor. In other words, when the potato current protection threshold value is set to prevent the motor from being demagnetized, the peak current of the motor is increased by performing the above-described torque fluctuation suppression control when the torque fluctuation during the low-speed rotation is large. Then, the motor current exceeds the above-described potato current protection threshold value, causing the problem that the motor is stopped.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to appropriately suppress potatoes of a permanent magnet of a motor while stably driving the motor.

In order to achieve the above object, the present invention provides a motor control device for converting a DC voltage input to an inverter from a DC power supply to an AC voltage and controlling driving of a motor connected to the inverter, When the temperature of the motor detected by the motor temperature detecting means is equal to or smaller than a first predetermined value determined based on the potato characteristics of the motor, the current fluctuation of the motor is suppressed And the current fluctuation suppressing control is executed.

Other aspects of the present invention will be described in the later embodiments.

According to the present invention, it is possible to appropriately suppress the demagnetization of the permanent magnet of the motor while stably driving the motor.

1 is a front view of an indoor unit, an outdoor unit, and a remote control of an air conditioner using a motor control device according to a first embodiment of the present invention.
2 is a system configuration diagram of an air conditioner.
3 is a configuration diagram including a motor driving device for driving a motor installed in a compressor.
4 is a characteristic diagram showing changes in motor potato current and motor potato protection threshold value with respect to motor winding temperature in a motor using permanent magnets having low-temperature potato characteristics.
5 is a flowchart showing the flow of processing of the motor potentiometer protection section.
Fig. 6 is an explanatory view showing a temporal change of the actual rotation speed of the motor controlled by the motor control device, Fig. 6 (a) is a case where the command rotation speed of the motor is smaller than the lower limit of the rotation speed, This is the case where the command rotation speed is higher than the lower limit of the rotation speed.
7 is an explanatory diagram showing the relationship between the rotational speed of the motor and the peak current when the torque disturbance suppression control (I control) is not executed and when the torque disturbance suppression control (I control) is executed.
Fig. 8 is a waveform chart showing a temporal change of the motor current. Fig. 8A shows a case where torque disturbance suppression control (I control) is not executed, and Fig. 8B shows a case where torque disturbance suppression control .
9 is a flowchart showing the flow of processing of the motor potentiometer protection unit in the motor control apparatus according to the second embodiment of the present invention.
10 is a flowchart showing the flow of processing of the motor potentiometer protection unit in the motor control apparatus according to the third embodiment of the present invention.
11 is a system configuration diagram of a refrigeration apparatus using a motor control apparatus according to a fourth embodiment of the present invention.

Best Mode for Carrying Out the Invention Hereinafter, embodiments of the present invention will be described in detail with reference to appropriate drawings. In the drawings, the same reference numerals are given to common parts in the drawings, and a duplicate description is omitted.

&Quot; First embodiment "

<Configuration of the air conditioner>

1 is a front view of an indoor unit, an outdoor unit, and a remote control of an air conditioner using the motor control device according to the first embodiment of the present invention.

The air conditioner A includes an indoor unit Iu, an outdoor unit Ou, and a remote control unit Re. The indoor unit Iu and the outdoor unit Ou are connected to each other by a refrigerant pipe L (see FIG. 2) and transmit and receive information to each other through a communication cable (not shown).

The remote control Re is operated by the user and transmits an infrared signal to the remote control receiver K of the indoor unit Iu. The content of the signal is a command such as an operation request, a change of a set temperature, a change of a timer, an operation mode, and a stop request. The air conditioner A performs air conditioning operations such as a cooling mode, a heating mode, and a dehumidification mode on the basis of these signals.

2 is a system configuration diagram of an air conditioner. The indoor unit Iu includes an expansion valve 4, an indoor heat exchanger 5, an indoor fan 5a, and an indoor control device 100a. The outdoor unit Ou includes a compressor 1, a four-way valve 2, an outdoor heat exchanger 3, an outdoor fan 3a, and an outdoor control device 100b.

The compressor 1, the four-way valve 2, the outdoor heat exchanger 3, the expansion valve 4 and the indoor heat exchanger 5 are connected by the refrigerant pipe L, .

On the other hand, the compressor 1 installed in the outdoor unit Ou is, for example, a single rotary type and is driven by the rotation of the motor M (see Fig. 3). The indoor control device 100a receives the infrared signal from the remote control unit Re through the remote control receiver K (see Fig. 1), communicates with the outdoor control unit 100b, (Cooling operation, cooling operation, and the like) corresponding to the operation mode (operation mode).

For example, upon receiving a command signal of the cooling operation from the remote control Re by the user's operation, the command signal is inputted from the indoor control device 100a through the communication line to the outdoor control device 100b via the communication line, The motor M (see Fig. 3) provided in the compressor 1 is rotated at a predetermined rotation speed (see the broken line in Fig. 2). The indoor control device 100a rotates the motor (not shown) of the indoor fan 5a and the outdoor control device 100b rotates the motor (not shown) of the outdoor fan 3a.

When performing the cooling operation, the outdoor control device 100b switches the four-way valve 2 so that the outdoor heat exchanger 3 functions as a condenser and the indoor heat exchanger 5 functions as an evaporator, The indoor control device 100a controls the opening degree (throttle) of the expansion valve 4 so that the refrigerant flows in the direction indicated by the solid line arrow. In this way, the air conditioner A performs the cooling operation using the heat pump cycle.

On the other hand, when performing the heating operation, the outdoor control device 100b performs the heating operation by switching the four-way valve 2 so as to flow the refrigerant in the direction opposite to the direction indicated by the solid line arrow in the drawing. On the other hand, the functions of the respective devices in the heating operation and the cooling operation are well known, and detailed description thereof will be omitted.

In the following description, the control device (outdoor control device 100b) for driving the motor M of the compressor 1 is sometimes referred to as &quot; motor control device 100 &quot;.

&Lt; Configuration of Motor Drive Apparatus >

3 is a configuration diagram including a motor driving device for controlling the driving of a motor installed in the compressor.

The motor driving apparatus S shown in Fig. 3 includes an inverter 300 for converting a DC voltage inputted from the DC power supply 200 into an AC voltage, and a motor driver 300 for detecting the temperature of the motor M connected to the inverter 300 A motor temperature detector 500 (motor temperature detecting means), and a motor control device 100 (control means) for controlling the drive of the inverter 300. [

The DC power supply 200 includes a converter 202 for converting an AC voltage input from the AC power supply 201 into a DC voltage and a DC power supply unit 202 connected in parallel to the output side of the converter 202, And a smoothing capacitor (C) for smoothing pulsation components.

An inverter 300 is connected to the output side of the DC power supply 200. The inverter 300 has a plurality of switching elements (not shown) and switches ON / OFF of each switching element in accordance with a PWM (Pulse Width Modulation) signal input from the driving signal generating section 105, Phase alternating-current voltage of the motor M to the motor M. Then, by introducing the three-phase AC current in accordance with the art three-phase AC voltage (I _u, I _v, I _w) to the armature (not shown) of the motor (M), it generates a rotating magnetic field.

As the switching element of the inverter 300, for example, an IGBT (Insulated Gate Bipolar Transistor) can be used.

The motor M is, for example, a permanent magnet type synchronous motor and is connected to the inverter 300 through a three-phase winding. That is, the motor M rotates by sucking a permanent magnet (not shown) by a rotating magnetic field generated by an alternating current flowing into the three-phase windings.

The rotary shaft of the motor M is fixed to the main shaft of the compressor 1 as a load. The compressor 1 is also driven by the driving of the motor M. Incidentally, as the compressor 1, in addition to the rotary compressor for rotating the piston, a scroll compressor for circularly moving one of the two vortex bodies, a reciprocating compressor for reciprocating the piston, and the like can be used.

In the present embodiment, a ferrite magnet having a low-temperature potato characteristic that is easy to potentiate at a low temperature is used as the permanent magnet of the motor M. [ Details of low-temperature potato characteristics will be described later.

The current detector 400 is connected in series to a bus line between the converter 202 and the inverter 300 and detects the current Io from the inverter 300 and outputs it to the motor current regenerating unit 101 in a clockwise direction do.

A motor temperature detector 500 (motor temperature detecting means) is provided in the motor M for detecting the coil temperature of the motor M and outputting it to the motor potentiometer 103 momentarily.

<Configuration of Motor Control Device>

The motor control apparatus 100 controls the drive of the motor M connected to the inverter 300 by converting the DC voltage input from the DC power supply 200 to the inverter 300 into an AC voltage .

The motor control apparatus 100 includes a motor current regenerating section 101, a torque disturbance suppressing section 102, a motor potato protecting section 103, a rotational speed instruction section 104, and a drive signal generating section 105 Respectively. The processing of the motor control apparatus 100 is executed by, for example, a microcomputer (not shown). That is, the motor control apparatus 100 includes an electronic circuit (not shown) such as a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory) The program is read out and expanded in the RAM, and the CPU executes various processes.

The motor current regenerating unit 101 reproduces the motor current flowing through the motor M based on the detection signal input from the current detector 400 and outputs the same to the torque disturbance suppression unit 102. [

The torque disturbance suppression unit 102 generates the torque fluctuation caused by the torque disturbance based on the motor current input from the motor current reproduction unit 101 and the correction command rotation speed? 2 input from the rotation speed instruction unit 104, And outputs a correction signal for suppressing the fluctuation to the drive signal generation section 105. [ On the other hand, details of the processing performed by the torque disturbance suppression unit 102 will be described later.

The motor potentiometer protection unit 103 is configured to control the motor potentiometer 103 based on the temperature information inputted from the motor temperature detector 500 and the command rotation speed? 1). Then, the motor potentiometer protection section 103 outputs the calculated correction command rotation speed? 1 to the rotation speed instruction section 104. [

Incidentally, the command rotational speed? Input from the outside is inputted to the indoor control device ((1)) based on the set temperature and the operation mode input from the remote control Re (see Fig. 1), the outdoor temperature input from various sensors, The temperature control microcomputer provided in the temperature control microcomputer 100a. For example, when a command signal for raising the set temperature is received by the remote control Re at the time of heating, the indoor control device 100a increases the value of the command rotation speed?.

The details of the processing performed by the motor potentiometer protection unit 103 will be described later.

The rotation speed instruction unit 104 corrects the correction instruction rotation speed omega 1 inputted from the motor potato protector 103 on the basis of the motor current inputted from the motor current reproduction unit 101 and outputs the correction instruction rotation speed omega 2 And outputs them to the switching section 102c and the drive signal generating section 105, respectively. On the other hand, the rotational speed instruction unit 104 estimates an axial error which is an error between the magnetic flux position of the permanent magnet of the motor M and the magnetic flux position assumed in the motor control device 100, The above-described correction command rotational speed? 2 is calculated.

The drive signal generating section 105 generates the PWM signal based on the correction command rotational speed omega 2 input from the rotational speed instruction section 104 and the control signal input from the torque disturbance suppression section 102, 300.

The torque disturbance suppression unit 102 has a torque fluctuation suppression control unit 102a (hereinafter referred to as a T control unit) and a current fluctuation suppression control unit 102b (hereinafter referred to as an I control unit).

T control section 102a calculates the torque variation (torque pulsation component) from the motor current reproduced by the motor current reproduction section 101 to suppress the load torque of the motor M which fluctuates periodically, And generates a correction signal for suppressing the noise. Then, the T control unit 102a outputs the correction signal to the drive signal generation unit 105 via the switching unit 102c.

By performing the torque fluctuation suppression control in this manner, it is possible to prevent vibration and detuning due to torque disturbance when the motor M is rotating at a low speed.

I control section 102b calculates a variation (current pulsation) of the motor current reproduced by the motor current reproduction section 101 and generates a correction signal for canceling the variation. Then, the I control unit 102b outputs the correction signal to the drive signal generation unit 105 via the switching unit 102c.

By performing the current fluctuation suppressing control in this way, the motor current can be brought close to the sinusoidal current, thereby suppressing current fluctuation and increasing the effective current.

The switching section 102c switches the actual rotation speed? Of the motor M based on the correction command rotation speed? 2 input from the rotation speed instruction section 104 and the current information input from the motor current representation section 101, _r ). The switching section 102c switches either one of the correction signal input from the T control section 102a and the correction signal input from the I control section 102b on the basis of the estimated rotational speed of the motor M And outputs it to the drive signal generation unit 105. [

That is, the actual rotation speed of the motor (ω _r) is a predetermined range: if (K1≤ωr <K2, see Fig. 6), the switching unit (102c), the drive signal a correction signal from the control unit T (102a) generating unit ( 105).

On the other hand, when the actual rotation speed of the motor is not less than the predetermined rotation speed K2 (K2? R: see Fig. 6), the switching unit 102c outputs the correction signal from the I control unit 102b to the drive signal generation unit 105 Output. That is, the switching section 102c switches to the contact A (see Fig. 3) when the motor M is driven at low speed rotation. When the motor M is driven at a high speed, 3).

&Lt; Setting of potato characteristics and temperature threshold value of permanent magnet &

4 is a characteristic diagram showing changes in motor potato current and motor potato protection threshold value with respect to the winding temperature of the motor in a motor using permanent magnets having low-temperature potato characteristics.

When permanent magnets are exposed to an excessive inverse magnetic field, they cause potatoes to weaken the magnetism, deteriorating the characteristics of the magnets. That is, when an excessive current flows through the coil used in the motor M, the potato occurs due to the influence of the inverse magnetic field generated by the current. Therefore, it is necessary to prevent the overcurrent from flowing into the motor M.

On the other hand, &quot; motor potato current &quot; is a motor current value when a potentiometer is generated in the permanent magnet of the motor M when the motor current is gradually increased at a predetermined temperature. As shown in Fig. 4, the value of the motor potato current becomes smaller (that is, becomes easier to demagnetize) as the temperature of the permanent magnet having the low-temperature potato characteristic is lowered.

Incidentally, as a permanent magnet having a low-temperature potato characteristic, for example, a ferrite magnet can be mentioned.

The &quot; motor potato current protection threshold value &quot; is a current threshold value set so as to be smaller than the motor potato current so as to prevent the permanent magnet magnetization, so that the motor potentiometer current protection threshold value becomes smaller as the motor winding temperature becomes lower Is set. Incidentally, in the example shown in Fig. 4, in order to simplify the microcomputer processing, the temperature characteristic of the motor potato protection threshold value is represented by a plurality of line segments.

The motor current I _th shown in Fig. 4 is a current peak value generated when the motor M is driven in the torque fluctuation suppression control, and is a value acquired in advance by experiments or the like.

In the motor control apparatus 100 according to the present embodiment, in the environment where the motor winding temperature inputted from the motor temperature detector 500 is lower than the temperature threshold T _th (10 ° C in FIG. 4), the motor potentiometer protection threshold The motor current of I _th (15 A in Fig. 4) or more does not flow, thereby preventing the permanent magnet from being demagnetized. That is, the temperature threshold value T _th is a predetermined value (first predetermined value) determined based on the potato characteristic of the motor M.

For example, when the torque fluctuation suppressing control with a large current fluctuation is continuously performed under an environment where the motor winding temperature is 10 DEG C or lower, there is a high possibility that the motor current exceeds the motor potentiometer protection threshold 15A 4). This is because, when the permanent magnet having the low-temperature potato characteristic is used for the motor M, the value of the motor potato current in the low-temperature environment becomes small, and the threshold value of the motor potato protection is also set correspondingly.

On the other hand, when the motor current exceeds the motor potentiometer protection threshold I _th , the motor control device 100 stops the driving of the motor M, so that the driving of the compressor 1 is also stopped. Therefore, the comfort of the air conditioner A may be impaired.

In order to avoid such a situation, in the present embodiment, when the winding temperature of the motor M falls below the temperature threshold T _th (first predetermined value) corresponding to the predetermined motor current I _th , The control immediately shifts to the I control to raise the temperature of the motor M to suppress the potatoes.

<Treatment of Motor Potato Protector>

Next, the processing flow of the motor potentiometer protection unit 103 will be described using the flowchart shown in Fig.

In step S101, the motor potentiometer protection unit 103 judges whether or not the command rotational speed? Is inputted from the outside (that is, the temperature controlling microcomputer). When the command rotation speed? Is not input from the outside (S101? No), the process of the motor potentiometer protection section 103 proceeds to step S102. Incidentally, when the command rotational speed? Is not inputted, the operation of the air conditioner A is stopped and the command signal (including the reserved operation) is transmitted from the remote control unit Re to the indoor control unit 100a Is not inputted. On the other hand, when the command rotation speed? Is inputted from the outside (S101? Yes), the process of the motor potentiometer protection unit 103 proceeds to step S103.

In step S102, the motor potentiometer protection unit 103 clears the elapsed time from the start of driving of the motor M. [

In step S103, the motor potentiometer protection unit 103 determines whether motor potentiometer protection is in progress. The state of "protecting the motor potato" is a state in which the motor M is driven with the correction command rotational speed? 1 as the target value to suppress the demagnetization of the motor M, Thereby increasing the temperature of the motor.

If motor potato protection is being protected (S103? Yes), the process of the motor potentiometer protection unit 103 proceeds to step S106. On the other hand, when the motor potato protection is not being performed (S103? No), the process of the motor potentiometer protection section 103 proceeds to step S104.

In step S104, the motor potentiometer protection unit 103 judges whether or not the motor winding temperature inputted from the motor temperature detector 500 is equal to or lower than the motor winding temperature threshold _Tth (first predetermined value: see Fig. 4) do.

If the motor winding temperature threshold temperature (T _th) or less (S104 → Yes), the processing of potatoes motor protection unit 103 proceeds to step S105. On the other hand, when the motor winding temperature is higher than the temperature threshold value T _th (S104? No), the process of the motor potentiometer protection section 103 proceeds to step S107.

In step S105, the motor potentiometer protection unit 103 sets a flag indicating that the motor potentiometer is being protected (i.e., sets the motor potentiometer while it is protected).

Next, it is judged whether the motor potato protection unit 103 in step S106 is reached in the elapsed time is, the rotational speed correction threshold time (t _th) from the driving start of the motor (M). On the other hand, as the rotational speed threshold value correction time (t _th) field, a current flow to the motor (M), the predetermined time is the winding temperature of the motor (M) is a temperature threshold value or more (T _th) (see Fig. 4).

If to the time elapsed from the start of driving the motor (M) reaches a rotational speed correction threshold time (t _th) (S106 → No), the processing of potatoes motor protection unit 103 proceeds to step S107. On the other hand, when the elapsed time from the start of the operation does not reach the threshold, the rotational speed correction time _{(t th) (S106 → Yes} ), potato protection processing unit proceeds to step S108.

In step S107, the motor potato protector 103 clears (releases) the flag for protecting the motor potato.

In step S108, the motor potentiometer protection unit 103 updates the elapsed time from the start of driving of the motor M. [

In step S109, the motor potentiometer protection unit 103 determines whether the command rotational speed? Input from the outside is smaller than the lower rotational speed limit? _L. On the other hand, the rotation speed lower limit value? _L is a range in which the I control can be performed (that is, the region 2 over the motor rotation speed K2 in which the I control can be performed; see Figs. 6A and 6B) ), Which is a preset predetermined rotational speed.

If the command rotational speed? Is smaller than the lower limit rotational speed? _L (YES in S109), the process of the motor potentiometer protection unit 103 proceeds to step S110. On the other hand, when the command rotational speed? Is not less than the lower limit rotational speed? _L (S109? No), the process of the motor potentiometer 103 proceeds to step S111.

In step S110, the motor potentiometer protection unit 103 sets the correction command rotational speed omega 1 to the lower rotational speed limit omega _L described above. In step S111, the motor potentiometer protection unit 103 sets the correction command rotational speed omega 1 to the command rotational speed omega input from the outside.

In this way, the motor potentiometer 103 performs the processing shown in Fig. 5 at a predetermined cycle, and outputs the correction command rotational speed omega 1 to the rotational speed commander 104 momentarily.

6A and 6B are explanatory diagrams showing the temporal change of the actual rotational speed of the motor M whose drive is controlled by the motor control device 100. [ On the other hand, also the area 1 shown in Fig. 6 (a), (b) (the actual rotation speed of the motor (M) (ω _r) is, K1≤ω _r <K2-in area) is, T the control unit (102a) (Fig. 3 (See FIG. 4). On the other hand, the region 2 (the region where the actual rotational speed? _R of the motor is equal to or greater than K2) is a region for performing the current fluctuation suppression control by the I control portion 102b.

6A is a case in which the command rotational speed of the motor is smaller than the lower rotational speed limit (that is, step S109 in Fig. 5 becomes &quot; Yes &quot;).

6A, the motor control device 100 accelerates the motor M at the target rotation speed from the start of driving of the motor M (lower limit value? _L ) (time 0 ~ T1). Incidentally, the motor M is accelerated by the forced operation until the rotational speed K1 at which the position sensorless control by the detection of the induced voltage of the motor M becomes possible.

As described above, the lower limit rotational speed? _L is a predetermined rotational speed preset in the region 2 where I control is possible. 6 (a), when the command rotational speed? Is lower than the lower rotational speed limit value? _L , the motor control device 100 sets the correction command rotational speed? (? _L ) to accelerate the motor M (see S110 in Fig. 5).

On the other hand, it is preferable that the rotation speed lower limit value? _L is close to the value of the rotation speed K2. This is because the current fluctuation suppressing control can be performed at a smaller rotational speed.

The control of the motor M is quickly shifted to the current fluctuation suppression control (I control: region 2) via the torque fluctuation suppression control (T control: region 1). That is, when the motor M is driven (started) in a low temperature environment, the correction command rotational speed omega 1 is forcibly changed to the current fluctuation suppressing control promptly to suppress current fluctuation. Thus, it is possible to avoid the situation where the motor current exceeds the potato current protection threshold (see Fig. 4) and the motor M is stopped.

6 (a), when the rotational speed of the motor M reaches the rotational speed lower limit value? _L (time t1), the motor control device 100 sets the rotational speed lower limit value? _L ) and drives the motor M continuously (time t1 to t2).

In addition, the temperature of the permanent magnet of the motor M is raised by the motor current between the time 0 and the time t2 shown in FIG. 6 (a). Then, the motor potato protection threshold value shown in Fig. 4 also increases. As described above, the rotational speed correction time threshold t _th shown in Fig. 6A is a predetermined time (tth) in which the winding temperature of the motor M is estimated to exceed the temperature threshold T _th shown in Fig. 4 to be.

Therefore, even after the time t2, even if the torque fluctuation suppressing control is performed in which the current fluctuation is relatively large, there is a margin between the motor potentiometer protection threshold value. As a result, it is possible to avoid the drive stop of the motor M accompanying the motor current exceeding the potato protection threshold.

Then, the motor (M) when the rotational speed correction time threshold (t _th) has elapsed (S106 → No in Fig. 5), the motor control device 100 shown in Fig. 6 from the start of driving of is, the flag "of the potato protection" (S107) and corrects the correction command rotational speed omega 1 to the command rotational speed omega (S111).

6 (b), when the command rotational speed [omega] of the motor M is equal to or greater than the rotational speed lower limit value [omega] _L (S109 → No in Fig. 5), the motor potato protector 103 , The value of the command rotational speed? Is adopted as the correction command rotational speed? 1 (S111 in FIG. 5). In other words, the rotational speed of the motor (M) after the motor potato protection section 103, the rotational speed correction threshold time (t _th) passed to the command rotational speed (ω), it maintains the current fluctuation suppression control.

In this case, since the current variation suppressing control by the I control section 102b is continued, there is no possibility that the motor current exceeds the potato current protection threshold (see Fig. 4).

6 (a), the motor control device 100 can control the motor M at a relatively high speed (lower limit rotational speed? _L ) in Fig. 6 (a) The command rotation speed? In Fig. 10 (b)). When the elapsed time from the start of driving reaches the rotation speed correction time threshold t _th , the motor control device 100 estimates that the motor winding temperature has increased to the temperature threshold value T _th or higher, The motor M is driven by the T control or the rated operation by the I control with the speed? As the target rotation speed.

<Effect>

The motor control apparatus 100 according to the present embodiment accelerates the motor M to the relatively high rotational speed of the rotational speed lower limit value ω _L or more at the start of the motor M and quickly shifts to the I control do. Then, the from the rotation start continue the I control until the rotational speed correction time threshold (t _th) has passed while keeping the current variation, it is possible to increase the winding temperature of the motor (M) so that the condition T controllable. Therefore, even when a ferrite permanent magnet having low-temperature potato characteristics is used, the threshold value for protecting the motor potentiometer can be increased with an increase in the winding temperature of the motor M. Therefore, by the T control (or I control) (M) is driven at the command rotational speed (?), And the compressor (1) can be continuously driven.

That is, according to the motor control apparatus 100 according to the present embodiment, the motor M can be continuously and stably driven while suppressing the potatoes of the permanent magnets used in the motor M. As a result, it is possible to provide the air conditioner (A) which is excellent in comfort.

7 is an explanatory diagram showing the relationship between the rotational speed of the motor M and the peak current when the torque disturbance suppression control (I control) is not executed and when the torque disturbance suppression control (I control) is executed .

As shown by the broken line (comparative example) in FIG. 7, the disturbance torque suppression control when the acceleration sikyeoteul (I control), the motor (M) not subjected to, when the rotation speed of 1500min ^-1 is the peak current 15A of the motor (M) , Which may exceed the motor potato protection threshold (refer to reference character Q). That is, since the temperature rise of the motor M does not reach the rotational speed of the motor M, there is a possibility that the motor M (that is, the compressor 1) is stopped to perform the potato protection.

On the other hand, in the motor control apparatus according to the present embodiment, when the rotational speed of the motor M rises to around 1250 min &lt; ^-1 &gt; as shown by the solid line in Fig. 7, ) (See FIG. 6) by T control (region 1: see FIG. 6). Thus, the fluctuation (pulsation) of the motor current can be suppressed, and the peak current when the rotation speed of the motor M is 1500 min &lt; ^-1 &gt; can be suppressed to about 7A (see the symbol P). Therefore, there is no fear that the peak current of the motor M exceeds the motor potato protection threshold (see Fig. 4), and the motor M can be steadily and continuously driven.

8A is a waveform diagram (comparative example) showing the temporal change of the motor current when the torque fluctuation suppression control (I control) is not executed. 8 (a) shows the temporal change of the motor current when the motor M is driven at a rotation speed of 1500 min ^-1 (the same applies to FIG. 8 (b)).

7, when the motor M is accelerated without current fluctuation suppression control (I control), when the rotation speed of the motor M becomes 1500 min ^-1 , the peak current exceeds 15 A, 8 (a).

8 (b) is a waveform diagram showing the temporal change of the motor current when the torque fluctuation suppression control (I control) according to the present embodiment is executed.

In the present embodiment, at the time of starting the motor M using the permanent magnet having the low-temperature potato characteristic, the motor M is controlled to rotate at a relatively high speed to perform I control. Therefore, as shown in Fig. 8B, the fluctuation (pulsation) of the motor current can be suppressed and the peak current can be suppressed to about 7A (see Fig. 7). As a result, there is a margin between the peak current and the motor potato protection threshold.

Further, the motor potentiometer protection threshold can be increased by raising the temperature of the motor M by continuing the high-speed rotation. Therefore, the motor M and the compressor 1 can be continuously operated with high efficiency, and the comfort of the air conditioner A can be maintained.

&Quot; Second Embodiment &

Next, the second embodiment will be described. In the above-described first embodiment, and to raise the motor winding temperature to a predetermined value, execution of potatoes protection process until the motor control device 100, the rotational speed correction time threshold (t _th) has elapsed from the start of driving . On the contrary, the second embodiment differs from the second embodiment in that the potato protecting process is performed by monitoring the winding temperature of the motor M. The other points are the same as those of the first embodiment, and a description thereof will be omitted.

Fig. 9 is a flow chart showing the flow of processing of the motor potentiometer protection section. Fig. The steps other than steps S206 and S208 shown in Fig. 9 are the same as those shown in the flowchart of Fig. 5 described in the first embodiment, and a description thereof will be omitted.

If the motor potentiometer is being protected (S203? Yes, or S205), the process of the motor control device 100 proceeds to step S206. In step S206, the motor control device 100 determines whether the winding temperature of the motor M input from the motor temperature detector 500 is smaller than the temperature threshold _Tth2 (second predetermined value) . The temperature threshold value T _th2 is a predetermined value (for example, 10 占 폚: see Fig. 4) and is stored in a storage means (not shown).

On the other hand, it may be a threshold temperature (T _th 1) and, at the step S206 threshold temperature (T _th 2) in step S204 to the same value.

If the winding temperature of the motor (M) is less than the threshold temperature _{(T th 2) (S206 →} Yes), processing of the motor control device 100 advances to step S208. On the other hand, the process of the motor winding temperature threshold temperature (T _th 2) or more when (S206 → No), the motor controller 100 proceeds to step S207.

In step S208, the motor control device 100 updates the motor winding temperature.

As described above, the winding temperature of the motor M inputted at a momentary angle by the motor temperature detector 500 is directly monitored and the winding temperature of the motor M is controlled to a predetermined temperature threshold _Tth (for example, 10 ° C: see Fig. 4) (S206 in Fig. 9), the motor potentiometer protection process may be canceled (S207).

<Effect>

According to the air conditioner A of the present embodiment, the correction command rotational speed is set to a predetermined value (? _L ) or more (that is, the motor M ) At a high speed), thereby performing I control for suppressing current fluctuation. By increasing the temperature of the motor M by driving the motor M in accordance with the I control, the motor M is continuously driven while suppressing the potato of the motor M having the permanent magnet of the low temperature potato characteristic .

In the first embodiment, it is estimated that the winding temperature of the motor M has risen to a predetermined value with the lapse of time from the start of operation. In the present embodiment, however, the winding temperature of the motor M is directly monitored. Therefore, the change of the winding temperature of the motor M can be grasped more accurately, and the potato of the motor M can be suitably prevented.

&Quot; Third Embodiment &

Next, the third embodiment will be described. In the first embodiment described above, the time from the start of rotation to the end of the potato protection process (that is, the rotation speed correction time threshold value t _th ) was a preset fixed value, whereas in the third embodiment, And the rotation speed correction time threshold t _th is set in accordance with the winding temperature of the motor M input from the detector 500. [ Therefore, the different parts will be described, and the description of the parts overlapping with those of the first embodiment will be omitted.

Fig. 10 is a flowchart showing the flow of processing of the motor potentiometer protection unit. Fig. The flowchart shown in Fig. 10 is obtained by adding step S304a to the flowchart of Fig. 5 described in the first embodiment.

Motor control device 100 in step S304 is, in a case where the winding temperature of the motor (M) which is input from the motor temperature sensor 500 is higher than temperature threshold value (T _th) (S304 → Yes), the motor control device 100 The process proceeds to step S304a.

The motor control device 100 sets the rotation speed correction time threshold t _th in accordance with the winding temperature of the motor M input from the motor temperature detector 500 in step S304a.

For example, the rotational speed correction time threshold (t _th) is progressively the value of the rotational speed correction time threshold (t _th) as the winding temperature of the motor (M) detected at the start of driving of the motor (M) higher It may be set appropriately by using a predetermined function.

In this way, the motor (M) set a value of the flexibility in rotation speed correction time threshold (t _th) depending on the winding temperature, and when the start of driving of the motor (M) rapidly predetermined rotational speed (ω _L (or of ?), thereby performing the current fluctuation suppressing control to suppress the demagnetization of the motor M.

<Effect>

The motor control apparatus 100 according to the present embodiment can set an appropriate rotation speed correction time threshold t _th in accordance with the winding temperature of the motor M detected at the start of driving. For example, when the outside temperature is low, the rotation speed correction time threshold t _th is set to be slightly longer to raise the motor M to a predetermined temperature, and when the outside temperature is relatively high, the rotation speed correction time threshold t _th ) can be set to be slightly shorter. That is, the potato protecting process of the motor M can be suitably performed, and the time for performing the potato protecting process can be set to the minimum necessary.

Therefore, even when the value of the command rotation speed? Input from the outside is smaller than the lower limit rotation speed? _L , the motor potato protection processing is terminated quickly, and the normal rotation operation in which the command rotation speed? . Therefore, it is possible to provide an air conditioner (A) that can reduce power consumed in driving the motor (M) (i.e., the compressor (1)) and is excellent in comfort.

&Quot; Fourth Embodiment &

Next, the fourth embodiment will be described. In each of the above-described embodiments, the air conditioner A having the compressor 1 installed in the motor M is controlled by controlling the motor M by the motor control device 100 , And the refrigerating device B provided with the compressor 1 will be described in the fourth embodiment.

In the meantime, the description of the parts overlapping with the above-described air conditioner A is omitted.

11 is a system configuration diagram of a refrigeration apparatus using a motor control apparatus. The freezing device B includes an indoor unit Iu and an outdoor unit Ou.

The indoor unit Iu includes an expansion valve 4, an indoor heat exchanger 5, an indoor fan 5a, an input / output means 6, and an indoor control device 100a. The outdoor unit Ou includes a compressor 1, an outdoor heat exchanger 3, an outdoor fan 3a, and an outdoor control device 100b.

The compressor 1, the outdoor heat exchanger 3, the expansion valve 4 and the indoor heat exchanger 5 are connected by a refrigerant pipe L in an annular shape, .

For example, the outdoor control device 100b rotates the motor M installed in the compressor 1 at a predetermined rotational speed when the user turns on the input / output means 6 through the input / output means 6, The refrigerant flows in the direction indicated by the solid line arrow (see the broken line in Fig. 1).

The indoor control device 100a rotates the indoor fan 5a at a predetermined rotational speed and the outdoor control device 100b rotates the outdoor fan 3a at a predetermined rotational speed. The outdoor control device 100b also controls the opening degree (throttle) of the expansion valve 4. [ Thus, the indoor heat exchanger (5) functions as an evaporator, and the outdoor heat exchanger (3) functions as a condenser.

On the other hand, the control of the motor M provided in the compressor 1 shown in Fig. 11 is the same as that of each of the above-described embodiments, and a description thereof will be omitted.

<Effect>

According to the present embodiment, the motor M can be continuously and stably driven while suppressing the potatoes of the permanent magnets used in the motor M. [ Therefore, it is possible to provide the refrigeration apparatus B having excellent reliability.

"Variations"

The motor control apparatus according to the present invention has been described above with reference to the embodiments. However, the embodiments of the present invention are not limited to these descriptions, and various modifications can be made.

For example, in each of the above embodiments, an example of detecting the winding temperature of the motor M by the motor temperature detector 500 is shown, but this is not limitative. That is, the outside temperature of the compressor 1 or the discharge pipe temperature of the compressor 1 may be detected as the temperature of the motor M and input to the motor potentiometer protection unit 103.

Further, in addition to the motor temperature detector 500, it may be further provided with an outside air temperature detector (outside air temperature detecting means) for detecting the outside air temperature. For example, the motor control apparatus 100 is configured to determine whether the outside air temperature input from the outside air temperature detector is equal to or lower than a predetermined value (third predetermined value) If the temperature threshold (T _th) (first predetermined value) or less, may be running on a potato protection process.

Whether or not the motor control apparatus 100 performs the potato protection process is determined according to the difference between the outside air temperature input from the outside air temperature detector and the winding temperature of the motor M input from the motor temperature detector 500 You can.

5, it is determined whether or not the operation mode of the air conditioner A is a heating operation as a process before determining whether or not the motor winding temperature is equal to or lower than the temperature threshold value T _th May be added. In the case of the heating operation, the process of the motor control device proceeds to step S104. On the other hand, if it is not the heating operation, the process of the motor control device proceeds to step S107.

It is possible to more appropriately determine whether or not the motor potentiometer protection process should be performed by inputting the judgment process of the operation mode.

On the other hand, the above determination processing may be applied to the flowchart shown in Fig. 9 or Fig.

In the above embodiments, the air conditioner A or the refrigerating device B including the compressor 1 driven by the motor M has been described. However, the present invention is not limited to this. In addition, the present invention can be applied to various devices using a heat pump cycle.

A: Air conditioner B: Freezer
L: refrigerant piping (piping) 1: compressor
2: Four way valve
3: outdoor heat exchanger (condenser, evaporator) 3a: outdoor fan
4: expansion valve 5: indoor heat exchanger
100: motor control device (control means) 101: motor current reproduction section
102: torque disturbance suppression unit
102a: T control section (torque fluctuation suppression control section)
102b: I control section (current fluctuation suppression control section)
102c: switching portion 103: motor potato protecting portion
104: rotation speed instruction unit 105: drive signal generation unit
200: DC power supply 300: Inverter
400: current detector
500: motor temperature detector (motor temperature detecting means)
S: Motor drive device M: Motor

Claims (20)

A motor control device for converting a DC voltage input to an inverter from a DC power supply to an AC voltage and controlling driving of a motor connected to the inverter,
The motor has a permanent magnet having a low-temperature potato characteristic that is easily demagnetized at a low temperature,
The motor control device includes:
A torque fluctuation suppression control section for suppressing torque fluctuation of the motor;
Wherein the control unit calculates a variation of the current flowing through the motor when the temperature of the motor detected by the motor temperature detection unit is equal to or smaller than a first predetermined value determined based on the potato characteristics of the motor, A current fluctuation suppression control section for executing suppression control,
By setting the command rotation speed of the motor to a correction command rotation speed capable of executing the current fluctuation suppression control when the temperature of the motor detected by the motor temperature detection means is equal to or smaller than the first predetermined value, A motor potato protector for executing,
And a switching section that switches between the processing by the torque fluctuation suppression control section and the processing by the current fluctuation suppression control in accordance with the rotation speed of the motor. delete The method according to claim 1,
The motor potentiometer may include:
Wherein the potato protection processing is executed for a predetermined time from the start of driving the motor. The method of claim 3,
The motor potentiometer may include:
And sets the predetermined time for executing the potato protecting process in accordance with the temperature of the motor detected by the motor temperature detecting means. The method according to claim 1,
The motor potentiometer may include:
And terminates the potato protecting process when the operating temperature of the motor input from the motor temperature detecting means becomes equal to or greater than a second predetermined value which is higher than the first predetermined value. 6. The method of claim 5,
And after the potato protection process is completed, drives the motor in accordance with a command rotational speed inputted from the outside. 7. The method according to any one of claims 1 to 6,
Wherein the permanent magnet is a ferrite magnet. A motor temperature detection means for detecting a temperature of a motor connected to the inverter; and a control means for controlling the drive of the inverter, wherein the control means controls the drive of the inverter A motor drive apparatus for driving the motor by AC power,
The motor has a permanent magnet having a low-temperature potato characteristic that is easy to potentiate at a low temperature,
Wherein,
A torque fluctuation suppression control section for suppressing torque fluctuation of the motor;
Wherein when the temperature of the motor detected by the motor temperature detecting means is equal to or less than a first predetermined value determined based on the potato characteristics of the motor, the variation of the current flowing through the motor is calculated, A current fluctuation suppression control section for performing fluctuation suppression control,
By setting the command rotation speed of the motor to a correction command rotation speed capable of executing the current fluctuation suppression control when the temperature of the motor detected by the motor temperature detection means is equal to or less than the first predetermined value, A motor potato protector for executing,
And a switching section for switching between the processing by the torque fluctuation suppression control section and the processing by the current fluctuation suppression control in accordance with the rotation speed of the motor. 9. The method of claim 8,
Further comprising an outdoor air temperature detecting means for detecting outdoor air temperature,
Wherein,
When the outside air temperature detected by the outside air temperature detecting means is not more than a third predetermined value and the temperature of the motor detected by the motor temperature detecting means is not more than the first predetermined value, The motor driving apparatus comprising: A compressor comprising the motor drive device according to claim 9, further comprising a compression mechanism that drives the motor by the motor drive device and compresses the fluid by the drive. 11. The method of claim 10,
Wherein the motor temperature detecting means detects the temperature of the windings of the motor, the outside temperature of the compressor, or the discharge pipe temperature of the compressor as the temperature of the motor. 12. The method of claim 11,
Wherein the compression mechanism is a rotary type, reciprocating type, or scroll type. An outdoor unit comprising a compressor according to any one of claims 10 to 12, an outdoor heat exchanger, an expansion valve, and an indoor heat exchanger connected annularly by piping to constitute a heat pump cycle. Device. An air conditioner comprising: the compressor according to any one of claims 10 to 12; an outdoor heat exchanger; an expansion valve; an indoor heat exchanger; and a four-way valve connected by piping to constitute a heat pump cycle . A motor control method for converting a DC voltage input to an inverter from a DC power supply to an AC voltage and controlling driving of a motor connected to the inverter,
The motor has a permanent magnet having a low-temperature potato characteristic that is easy to potentiate at a low temperature,
A torque fluctuation suppression control for suppressing torque fluctuation of the motor and a variation in current flowing through the motor when the temperature of the motor is equal to or lower than a first predetermined value determined based on the potato characteristics of the motor, A motor control process for switching the current fluctuation suppression control for canceling the variation according to the rotation speed of the motor,
Wherein the controller executes a potato protection process of setting the command rotation speed of the motor to a predetermined rotation speed or higher at which the current fluctuation suppression control is possible when the operating temperature of the motor is lower than the first predetermined value Way. delete 16. The method of claim 15,
And the potato protection process is executed for a predetermined time from the start of driving of the motor. 18. The method of claim 17,
And the predetermined time for executing the potato protection process is set according to the temperature of the motor. 19. The method of claim 18,
And the potato protection processing is terminated when the operating temperature of the motor becomes equal to or higher than a second predetermined value which is higher than the first predetermined value. 20. The method according to any one of claims 15 to 17,
And after the potato protection process is completed, the motor is driven in accordance with a command rotational speed inputted from the outside.

Images