KR20130106291A - Motor drive device, air conditioner comprising motor drive device, and motor drive method - Google Patents

Abstract

PURPOSE: A motor driving device, an air conditioner including the same, and a motor driving method are provided to properly suppress the demagnetization of a permanent magnet in a motor while stably driving the motor. CONSTITUTION: A current threshold setting unit (45) sets an acceleration rate limit threshold by corresponding to a motor temperature which is detected by a motor winding temperature detector (50). An acceleration rate setting unit (46) compares a motor current corresponding to a current value which is detected by a current detector (20) with the acceleration rate limit threshold. The acceleration rate setting unit sets the acceleration rate of a motor according to a comparison result. A driving signal generating unit (44) outputs a driving signal to an inverter (11) according to the acceleration rate which is set by the acceleration rate setting unit. A converter (300) converts an AC voltage from an AC power source (200) into a DC voltage. [Reference numerals] (10) Power module; (100) Motor operating device; (11) Inverter; (12) Device short-circuit protecting means; (13) Inverter operating motor; (20) Current detector; (30) Amplifier; (300) Converter; (40) Inverter control means; (41) Motor current replaying u nit; (42) Speed ordering unit; (44) Driving signal generating unit; (45) Current threshold setting unit; (46) Acceleration rate setting unit; (50) Motor winding temperature detector; (AA) PWM signal

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a motor driving apparatus, an air conditioner having the same,

The present invention relates to a motor driving apparatus, an air conditioner having the same, and a motor driving method.

In recent years, inexpensive ferrite magnets have been used as permanent magnets provided in motors of compressors, but ferrite magnets have characteristics (low temperature potato characteristics) that are easily demagnetized in a low temperature environment.

Here, the term " potato " means that the magnetic moment of the entire magnet is reduced by a temperature rise caused by an eddy current loss of the magnet, or a reverse system caused by an electric current.

As a technique for preventing such permanent magnet magnetization, the following is known.

For example, in Patent Document 1, a motor phase current is calculated in a phase current calculation section (current reproduction section) based on the output of a DC current detection circuit (current detector), and when the motor phase current becomes a predetermined threshold value or more Discloses a brushless motor drive apparatus for a compressor having a current limiting function for lowering the frequency of a brushless motor (motor).

In the technique described in Patent Document 1, the overcurrent protection stop threshold value determined by the voltage comparison circuit is changed to a predetermined value less than the potato current, thereby preventing the permanent magnet from being demagnetized.

Patent Document 2 describes an air conditioner that switches the overcurrent detection level of the motor in accordance with the temperature detected by the compressor temperature detection means. When the detected motor current exceeds the overcurrent detection level, the rotational speed of the motor is limited to prevent the permanent magnet of the motor from being demagnetized.

Japanese Patent Application Laid-Open No. 2009-198139 Japanese Patent Application Laid-Open No. 2005-308233

In the technologies described in Patent Documents 1 and 2, when the motor current exceeds a predetermined current limit threshold value, a command signal for lowering the frequency of the motor from the microcomputer (that is, decelerating the motor) is output to the inverter. Further, when the motor current exceeds a predetermined overcurrent protection threshold, a command signal for stopping the driving of the motor from the microcomputer is outputted to the inverter.

If, for example, the motor is to be rotated at a high speed when the air conditioner performs the heating operation, deceleration control or stop control of the motor is performed, so that it takes a long time to reach the target rotation speed. In such a case, there is a high possibility that the deceleration and acceleration of the motor will be repeated, and the driving of the motor becomes unstable.

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 apparatus comprising a current threshold setting section for setting an acceleration rate limiting threshold value, which is a current threshold value for limiting an acceleration rate of a motor, An acceleration rate setting unit that compares the motor current corresponding to the current value detected by the detecting unit with the acceleration rate limiting threshold inputted from the current threshold setting unit and sets the acceleration rate of the motor according to the comparison result, And a drive signal generator for outputting a drive signal to the inverter according to the acceleration rate set by the acceleration rate setting unit.

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 system configuration diagram of an air conditioner using a motor control apparatus according to a first embodiment of the present invention;
2 is a configuration diagram including a motor drive device for driving a motor installed in a compressor.
Fig. 3 is a map showing the relationship between the motor potato current and the motor potato protection threshold value for the motor winding temperature in a motor using permanent magnets having low-temperature potato characteristics. Fig.
4 is a map showing the relationship between the device short-circuit protection threshold, the motor potato current, the motor potato protection threshold, and the acceleration rate limiting threshold and the motor temperature.
5 is a flowchart showing the flow of processing performed by the inverter control means;
6 is an explanatory diagram showing a temporal change in the rotational speed of the motor;
7 is an explanatory diagram showing a temporal change in the rotational speed of the motor;
8 is a map showing the relationship between the element short-circuit protection threshold, the motor potato current, the motor potato protection threshold, and the acceleration rate limiting threshold and the motor temperature in the motor driving apparatus according to the second embodiment of the present invention.
9 is a flowchart showing the flow of processing performed by the inverter control means.
Fig. 10 is a graph showing the relationship between the rotational speed and the motor phase current when the acceleration rate limit value of the compressor driving motor is Omin- ¹ / sec in the air conditioner using the motor driving apparatus according to the third embodiment of the present invention Degree.
11 is a flowchart showing the flow of processing performed by the control means of the air conditioner.
Fig. 12A is an explanatory diagram showing the motor current characteristics when the pressure of the compressor is changed when the torque disturbance suppression control is performed, Fig. 12B is a graph showing the relationship between the region T for executing the torque fluctuation suppression control, Fig. 5 is a diagram showing a phase current waveform in a region I in which the current fluctuation suppressing control is executed. Fig.
13 is an explanatory diagram showing an example of a motor current characteristic and an actual load when a pressure of a compressor is changed when torque disturbance suppression control is performed;

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 system configuration diagram of an air conditioner using a motor control apparatus according to the present embodiment. The indoor unit Iu and the outdoor unit Ou of the air conditioner A are connected to each other by a refrigerant pipe L so as to perform a predetermined air conditioning operation in accordance with an infrared signal input from the remote control unit Re .

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.

A four-way valve (2) is connected to the compressor (1) for switching the flow of the refrigerant during cooling and heating. One side of the four-way valve 2 is connected to an outdoor heat exchanger 3 which functions as a condenser during cooling operation and functions as an evaporator during heating operation through a refrigerant pipe L. On the other side of the four-way valve 2, an indoor heat exchanger 5 which functions as an evaporator during cooling operation and functions as a condenser during heating operation is connected via a refrigerant pipe L.

An expansion valve 4 as a decompression device is connected between the outdoor heat exchanger 3 and the indoor heat exchanger 5. Incidentally, a pressure sensor (not shown) for detecting the pressure of the refrigerant discharged from the compressor 1 to the four-way valve 2 is provided.

As described above, 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, Cycle.

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, it is assumed that the control device (outdoor control device 100b) for controlling the driving of the motor M provided in the compressor 1 is described as "motor driving device 100" .

<System Configuration Including Motor Drive Device>

2 is a configuration diagram including a motor driving device for driving a motor installed in the compressor.

The AC power supply 200 shows a power source of AC power transmitted from a power plant (not shown) or the like.

The converter 300 is a circuit for converting an AC voltage input from the AC power source 200 into a DC voltage and includes a diode bridge in which diodes D1 and D3 are connected in series in a forward direction and their interconnection points are used as a converter input terminal . The same applies to the diodes D2 and D4. Further, a smoothing capacitor C for smoothing pulsation components included in the DC voltage is connected in parallel with the diode bridge described above.

Therefore, the converter 300 connected to the AC power supply 200 constitutes a &quot; DC power supply &quot;.

The motor driving apparatus 100 converts the DC voltage input from the DC power supply into a predetermined AC voltage by inverter control and outputs the DC voltage to the motor M. [ On the other hand, details of the motor driving apparatus 100 will be described later.

The motor M is, for example, a permanent magnet type synchronous motor. The motor M is connected to the inverter 11 through a three-phase winding. The permanent magnet M is connected to the inverter 11 via a rotating magnetic field generated by an alternating- (Not shown). On the other hand, the rotary shaft of the motor M is fixed to the main shaft of the compressor 1 (see Fig. 1) as a load, and the compressor 1 is driven by the rotation of the motor M.

In this embodiment, a ferrite magnet having low-temperature potato characteristics, which is easy to potentiate at a low temperature, is used as a permanent magnet of the motor M. [

&Lt; Configuration of Motor Drive Apparatus >

2, the motor drive apparatus 100 includes a power module 10, a current detector 20, an amplifier 30, and an inverter control means 40. [

The power module 10 includes an inverter 11 including a plurality of switching elements (not shown) for outputting a predetermined AC voltage to the motor M, element short-circuit protection means 12 for protecting the switching element, And an inverter driving circuit 13 for driving the switching elements are integrated intensively.

The current detector (current detecting means) 20 is connected in series to a bus line between the converter 300 and the inverter 11 to detect the current supplied to the inverter 11, And outputs it to the short-circuit protection means 12 momentarily.

The amplifier 30 has, for example, a transistor (not shown), amplifies the detection signal input from the current detector 20, and outputs the amplified detection signal to the motor current reproducing unit 41 of the inverter controlling means 40.

The inverter control means (control means) 40 calculates an AC voltage to be applied to the motor M on the basis of the detection signal input from the amplifier 30 and the rotation speed instruction value? Of the motor M , And outputs the drive signal.

On the other hand, the rotational speed command value? Is set to a value that is determined on the basis of the set temperature information inputted from the remote control Re (see Fig. 1), the indoor temperature detected by the thermistor (not shown) to be. For example, when the set temperature inputted from the remote control Re rises during the heating operation, the temperature control microcomputer (not shown) of the air conditioner increases the rotation speed command value?.

The motor winding temperature detector (motor temperature detecting means) 50 detects the winding temperature of the motor M and outputs it to the current threshold setting section 45 at a time instant.

(1. Power module)

The power module 10 includes an inverter 11, an element short-circuit protection means 12, and an inverter driving circuit 13. [

The inverter 11 has a plurality of switching elements (not shown), switches ON / OFF of each switching element in accordance with the PWM signal input from the inverter driving circuit 13, and supplies a predetermined three- (M). Then, the three-phase alternating current according to the three-phase AC voltage flows into the motor M to generate the rotating magnetic field.

On the other hand, for example, an IGBT (Insulated Gate Bipolar Transistor) can be used as a plurality of switching elements of the inverter 11. [

The device short-circuit protection means 12 compares the current detection value input from the current detector 20 with a predetermined device short-circuit protection threshold value and outputs a stop command signal when the current detection value exceeds the device short- And outputs it to the inverter drive circuit 13 to stop the drive of the inverter 11. [

On the other hand, the processing of the element short circuit protection means 12 is executed without interposing a microcomputer. This makes it possible to stop the drive of the inverter 11 for a very short time (several microseconds) when the switching element is short-circuited.

The inverter drive circuit 13 outputs a PWM signal (Pulse Width Modulation: pulse width modulated wave signal) to each switching element (not shown) of the inverter 11 in accordance with a drive signal input from the drive signal generator 44, ). Further, when the stop command signal is inputted from the element short-circuit protection means 12, the inverter drive circuit 13 stops the output of the PWM signal.

(2. inverter control means)

The inverter control means (control means) 40 includes a motor current reproducing section 41, a speed command section 42, a drive signal generating section 44, a current threshold setting section 45, (46).

On the other hand, the processing of the inverter control means 40 is executed by a microcomputer (not shown). The microcomputer includes an electronic circuit (not shown) such as a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory) and various interfaces, reads a program stored in the ROM, And the CPU executes various processes.

The motor current reproducing section 41 reproduces a current flowing through the motor M (hereinafter referred to as a motor current) based on the detection signal detected by the current detector 20 and amplified by the amplifier 30 And outputs it to the acceleration rate setting unit 46.

Based on the motor current input from the motor current regenerating section 41 and the rotation speed instruction value? Inputted from the above-mentioned temperature controlling microcomputer (not shown), the speed instruction section 42 applies The three-phase AC command voltage to be set, and the PWM frequency command value, and outputs it to the drive signal generating section 44.

The current threshold setting unit 45 sets an acceleration rate limiting threshold value which is a current threshold value for limiting the acceleration rate of the motor M in accordance with the motor temperature detected by the motor winding temperature detector 50 4). The current threshold value setting unit 45 sets a motor potato protection threshold value (potato protection threshold value) for preventing the permanent magnet from being demagnetized in accordance with the motor winding temperature inputted from the motor winding temperature detector 50 Reference). Incidentally, it is assumed that the above-mentioned "acceleration threshold" and "motor potato protection threshold" are referred to as "current threshold".

The current threshold setting unit 45 outputs the set plurality of current threshold values to the acceleration rate setting unit 46. [

The acceleration rate setting section 46 compares the motor current inputted from the motor current reproducing section 41 with the acceleration rate limiting threshold inputted from the current threshold setting section 45 and outputs And outputs the determined acceleration rate to the drive signal generation unit 44.

The acceleration rate setting section 46 compares the motor current inputted from the motor current reproducing section 41 with the acceleration rate limiting threshold inputted from the current threshold setting section 45 and outputs the motor current M Is set. That is, the acceleration rate setting unit 46 specifies which one of the acceleration rate regions (see the region A and the region B in FIG. 4) that is preset between the above-mentioned plurality of current thresholds, And outputs the acceleration rate corresponding to the area to the drive signal generation unit 44. [

On the other hand, when the motor current exceeds the motor potato protection threshold, the acceleration rate setting section 46 outputs a stop command signal to stop the drive of the inverter 11 to the drive signal generating section 44.

The drive signal generating section 44 drives the inverter drive circuit 13 in accordance with the rotation speed instruction value ω input from the speed instruction section 42 and the acceleration rate information input from the acceleration rate setting section 46 And outputs a signal. When the stop command signal for stopping the drive of the inverter 11 is inputted from the current threshold value setting unit 45, the drive signal generating unit 44 outputs the rotation speed command value (&quot; and outputs a stop command signal to the inverter drive circuit 13,

(Potato protection treatment)

3 is a map showing the relationship between the motor potentiometer current and the motor potentiometer protection threshold value for the motor winding temperature in the motor using the permanent magnet having the low-temperature potato characteristic. As shown in Fig. 3, the permanent magnet (for example, ferrite magnet) having a low-temperature potato characteristic has a smaller motor potato current value (that is, it becomes easier to potentiate) as its temperature is lowered. The &quot; motor potato current &quot; is a motor current value at the time when the potato starts to be generated when the motor current is increased at a predetermined temperature.

The motor potato protection threshold value shown in Fig. 4 is set to be smaller than the value of the motor potato current at any motor winding temperature. Here, the &quot; motor potato protection threshold value &quot; is a preset current threshold value for preventing the permanent magnet of the motor M from being demagnetized. Incidentally, the motor potato protection threshold value is set to a value that is different from the detection error of the motor winding temperature detector 50 or the current detector 20, the irregularity of the electrical characteristics of the components of the power module 10, (Reaction time), and the like, the current value is set to a slightly lower value than the characteristic of the motor potato current.

These pieces of information are stored in storage means (not shown) provided in advance in the microcomputer.

As described above, the potato characteristics with a relatively large time constant are subjected to determination processing with high accuracy under the control of the microcomputer, and the motor winding temperature inputted from the motor winding temperature detector 50, The acceleration rate of the motor M is appropriately set in accordance with the motor winding temperature inputted from the motor 41. [

(2. short-circuit protection process)

The element short-circuit protection means 12 sets the element short-circuit protection threshold for preventing short-circuiting of the switching element (not shown) of the inverter 11 to a predetermined value lower than the absolute value of the element (see Fig. 5). In addition, the absolute value of the element is a value preset as a current value at which the motor current should not exceed a moment.

The device short-circuit protection means 12 executes processing without interposing a microcomputer, and stops the drive of the inverter 11 for a very short time (for example, several microseconds) when the motor current exceeds the short-circuit protection threshold value.

In this way, the potato protection process by the microcomputer and the device short-circuit protection process without the microcomputer are executed independently, thereby preventing the permanent magnet of the motor M from being demagnetized, The switching element can be suitably protected.

(3. Acceleration Rate Limiting Process)

4 is a map showing the relationship between the element short-circuit protection threshold, the motor potato current, the motor potato protection threshold, and the acceleration rate limiting threshold and the motor temperature.

In the following description, the case where the motor M has a ferrite magnet (not shown) having a low-temperature potato characteristic will be described.

As shown in Fig. 4, the motor currents of predetermined ranges are previously associated with the motor winding temperature, and the acceleration rate regions (regions A and B) in which the acceleration currents are associated with the motor currents of the ranges are set in advance have. On the other hand, the acceleration rate (min ^-1 / sec (rotation / second)) is the rotation speed of the motor M that increases per unit time.

4, an area from the acceleration rate limiting threshold value I1 to the acceleration rate limiting threshold value I2 is set as the area A, and an area from the acceleration rate limiting threshold value I2 to the motor potato protection threshold value is set as the area B . Therefore, the area A, for example in the acceleration rate 32min ^-1 / sec, the area B, for example the acceleration rate as that 14min ^-1 / sec, a high current level region (B region) has a current level Is reduced to 1/3 to 1/10 of the lower area (area A), and the area B having the higher current level is set to be lower than the area A having the smaller current level. Incidentally, the acceleration rate in the normal region is, for example, 96 min ^-1 / sec.

That is, as in the case of the normal region? The region A? The region B, the value of the acceleration rate is set to be smaller as the threshold value approaches the potato protection threshold. These pieces of information are stored in advance in the storage means (not shown) of the microcomputer.

The acceleration rate setting section 46 specifies an acceleration rate region to which (the peak value of) the motor current inputted from the motor current reproducing section 41 belongs and sets the acceleration rate corresponding to the acceleration rate region to the drive signal generating section 44.

This makes it possible to widen the range of the motor current that can be operated by using the characteristic that the ripple width (peak value of the motor current) of the load current when the acceleration rate is low is smaller than the ripple width when the acceleration rate is high. As a result, it is possible to prevent the motor M from accidentally stopping the protection of the potato, and at the same time to reach the target rotation speed smoothly and quickly.

5 is a flowchart showing the flow of processing performed by the inverter control means.

In step S101, the inverter control means 40 determines whether or not a predetermined time? T1 has elapsed from the drive start time of the motor M. [ The predetermined time? T1 is a preset value (for example, a cycle time of the microcomputer), and is stored in a storage means (not shown).

When the predetermined time? T1 has elapsed from the drive start time of the motor M (S101? Yes), the process of the inverter control means 40 proceeds to Step S102. On the other hand, when the predetermined time? T1 has not elapsed from the drive start time of the motor M (S101? No), the inverter control means 40 repeats the processing of the step S101.

In step S102, the inverter control means 40 sets the current threshold value (i.e., the potato current protection threshold value and the two acceleration rate limiting threshold values I1 and I2) corresponding to the winding temperature T input from the motor winding temperature detector 50, I2) is updated (set). The acceleration rate limiting threshold value I1 is the lower limit value of the area A shown in Fig. 4, and the acceleration rate limiting threshold value I2 is the lower limit value of the area B shown in Fig. For example, when the winding temperature of the motor M is 60 占 폚, the inverter control means 40 refers to the diagram shown in Fig. 4 to calculate the acceleration rate limiting thresholds I1 (about 15A) and I2 17A) is updated (set).

In step S103, the inverter control means 40 determines whether or not the motor current Im is equal to or greater than the acceleration rate limiting threshold value I2. When the motor current Im is equal to or greater than the acceleration rate limiting threshold value I2 (S103? Yes), the process of the inverter control means 40 proceeds to step S104. On the other hand, when the motor current Im is less than the acceleration rate limiting threshold value I2 (S103? No), the process of the inverter control means 40 proceeds to step S105.

In step S104, the inverter control means 40 sets the acceleration command value of the motor M to a predetermined value (?) (For example, 14 min ^-1 / sec) and outputs it to the inverter drive circuit 13 as a drive signal . On the other hand, the predetermined value? Is a predetermined acceleration of zero or more.

In step S105, the inverter control means 40 determines whether or not the motor current Im is equal to or greater than the acceleration rate limiting threshold value I1. If the motor current Im is equal to or greater than the acceleration rate limiting threshold value I1 (Yes in S105), the process of the inverter control device proceeds to step S106. On the other hand, when the motor current Im is less than the first acceleration rate limiting threshold value I1 (S105? No), the process of the inverter control means 40 proceeds to step S107.

In step S106, the inverter control means 40 sets the acceleration command value of the motor M to a predetermined value (for example, 32 ^min-1 / sec) and outputs it to the inverter drive circuit 13 as a drive signal . On the other hand, the predetermined value? Is a predetermined acceleration equal to or higher than the predetermined value?. In this manner, the inverter control means 40 sets a large acceleration rate as the peak value of the motor current moves away from the motor potato protection threshold value.

That is, even when the peak value of the motor current is in the region A or the region B close to the motor potato protection threshold value, the inverter control means 40 maintains the rotation speed of the motor M or the motor rotation speed rises , And controls the acceleration rate of the motor (M) to be lowered.

Accordingly, the motor M can be quickly driven to reach the target rotation speed while avoiding the potato of the permanent magnet of the motor M.

In step S107, the inverter control means 40 maintains the normal acceleration command value? (E.g., 96 min- ¹ / sec). On the other hand, the predetermined value? Is a preset acceleration equal to or higher than the predetermined value?. In this case, the inverter control means 40 drives the motor M by performing normal operation.

6 is an explanatory diagram showing a temporal change in the rotational speed of the motor. The horizontal axis of FIG. 6 shows the operation time of the motor from the start of driving of the motor M, and the vertical axis shows the rotation speed of the motor. A solid line shown in Fig. 6 shows a case in which the motor driving apparatus 100 according to the present embodiment is used, and a broken line shows a comparative example.

In the case of the comparative example shown by the broken line in Fig. 6 (when the acceleration rate limitation is not provided), when the motor M is started at the time 0 and the rotational speed of the motor M rises, Reaches the potato threshold value (see Fig. 4), and the motor M is stopped and restarted. In this manner, when the operation and the restart are repeated, the driving of the motor M becomes unstable, and it takes a long time to reach the target rotation speed.

On the other hand, in the case of the present embodiment shown by the solid line in Fig. 6, after the rotational speed of the motor M is raised to a relatively high acceleration? In the steady region, the motor current becomes I1 The control is shifted from the time t1 to the area A (see Fig. 4), and the rotational speed of the motor M is raised to an acceleration? Lower than the acceleration?.

4) at time t3 at which the motor current becomes I2 (≥I1: see Fig. 4) or more, and the rotation speed of the motor M is changed to the acceleration .

Then, the rotational speed of the motor M reaches the target rotational speed at time t4.

In this manner, the target rotational speed can be quickly reached without stopping the motor M by raising the rotational speed while stepwise reducing the acceleration of the motor M as the motor potentiometer protection threshold is approached. That is, by executing the acceleration rate limiting process, the motor M can stably drive without stopping the operation and restarting, and can reach the target rotation speed quickly.

Fig. 7 is an explanatory diagram showing a temporal change in the rotational speed of the motor. Fig. In Fig. 7, the horizontal axis represents the operating time of the motor from the start of driving, and the vertical axis represents the rotational speed of the motor. 7 shows a case where the motor driving apparatus 100 according to the present embodiment is used, and the broken line shows a comparative example.

A comparison example (broken line) shown in Fig. 7 is a case where the motor M is forcibly decelerated when the motor rotation speed exceeds a predetermined threshold value. In this case, the motor M is decelerated when the motor current reaches the predetermined current threshold at time t5 shown in FIG. 7, and the motor is accelerated when the current becomes lower than the current threshold. Therefore, when the forced deceleration control is performed, not only the time is taken to reach the target rotation speed but also the current pulsation occurs due to the load fluctuation caused by acceleration / deceleration of the motor M itself, The risk is higher. In addition, there is a possibility that noise may be generated along with acceleration / deceleration of the motor M.

On the other hand, in the case of this embodiment shown by the solid line in Fig. 7, the acceleration (A) is applied to the region A (see Fig. 4) between time t5 and t6 to set the acceleration (See Fig. 4), an acceleration (?) (??) Is obtained.

Therefore, the target rotation speed can be quickly reached, and the operation / stop of the motor M is not repeated. Thus, the motor M can be stably driven to suppress noise.

<Effect>

The motor driving apparatus 100 according to the present embodiment performs control to raise the rotation speed while gradually reducing the acceleration of the motor M as the motor potato protection threshold is approached. Thereby, the rotation speed of the motor M can be raised by maximizing the motor current without stopping the motor M. As a result, the target rotation speed can be quickly reached from the start of operation.

When the air conditioner A using the compressor 1 equipped with the motor driving apparatus 100 according to the present embodiment is operated, for example, the heating operation is performed in a low temperature environment to rotate the motor M at a high speed Even in this case, the target rotation speed can be reached quickly and stably. Therefore, it is possible to provide the air conditioner (A) having excellent comfort.

It is also possible to avoid the situation where the operation stop and restart are repeated by raising the rotation speed of the motor M continuously while changing the acceleration rate in accordance with the motor current and the motor temperature by providing an acceleration rate limiting threshold value. Therefore, it is possible to stably drive the motor M while preventing the permanent magnet of the motor M from being demagnetized.

Further, in the motor control including the conventional ferrite magnet, the difference between the potato current threshold value of the motor M and the rated load current value becomes small, and there is a high possibility that the motor M is stopped. In other words, accidental stoppage of operation frequently occurs due to the pulsation of the motor current (i.e., the peak value of the motor current) at the sudden change of ambient environmental load.

On the other hand, in the motor driving apparatus 100 according to the present embodiment, the acceleration rate limiting threshold is provided at a current level slightly lower than the potato starting current value, thereby raising the rotation speed of the motor M and gradually reducing the acceleration rate. As a result, the motor M is protected against the potato, and the target rotational speed can be reached more smoothly and quickly.

&Quot; Second Embodiment &

Next, 2nd Embodiment is described. In the above-described first embodiment, a plurality of regions (region A and region B) are provided and the acceleration rate is limited in accordance with the state of the motor M (motor temperature and motor current) To control the state of the motor M so as to change along the boundary line of the area.

On the other hand, since the configuration of the motor driving apparatus 100 is the same as that of the first embodiment, a description thereof will be omitted.

8 is a diagram showing the relationship between the short-circuit protection threshold value, the motor potato current, the motor potato protection threshold, the acceleration rate limiting threshold, and the motor temperature in the motor driving apparatus according to the present embodiment. 8, the axis of abscissas indicates the motor temperature, and the axis of ordinates indicates the motor current and the circuit current of the inverter 11. [

In the present embodiment, the motor potato protection threshold and the acceleration rate limiting threshold I3 (see Fig. 9), which is set to be a value smaller than the motor potato protection threshold value for any motor current, It is remembered.

When the motor current exceeds the acceleration rate limit threshold value I3 and enters the area C shown in Fig. 8, the acceleration command value of the motor M is set to a predetermined value? (? 0). Incidentally, in the following, the case where the predetermined value (? = 0) is described will be described, but the present invention is not limited thereto.

In the present embodiment, when the motor winding temperature inputted from the motor winding temperature detector 50 and the state of the motor M corresponding to the motor current input from the motor current reproducing portion 41 enter the region C, The rate setting section 46 outputs to the drive signal generating section 44 a command signal for setting the acceleration of the motor M to zero. That is, the acceleration rate setting unit 46 sets the acceleration rate of the motor M when the acceleration rate limiting threshold increases as the temperature of the motor M increases, .

Then, since the motor M is driven at a substantially constant rated speed, the peak value of the motor current is also substantially constant (see the K portion enlarged portion in Fig. 8). Further, since the motor winding temperature rises as the motor current flows, there is a margin between the acceleration rate limiting threshold value corresponding to the motor winding temperature.

If the motor current becomes equal to or greater than the acceleration rate limit threshold value I3 after changing the acceleration to zero, the acceleration rate setting section 46 sets the predetermined value And outputs a command signal to the drive signal generating section 44. The inverter control means 40 executes such processing for each cycle time of the microcomputer.

8, the state of the motor M is gradually moved to the right side of the drawing along the straight line (or curve) of the acceleration rate limiting threshold value which becomes the boundary line of the area C. Therefore, as shown in Fig.

9 is a flow chart showing the flow of processing performed by the inverter control means. The processes in steps S201 and S202 shown in FIG. 9 are the same as the processes in steps S101 and 102 shown in FIG. 5 in the first embodiment, respectively, and the description will be omitted.

In step S203, the inverter control means 40 determines whether or not the motor current Im is equal to or greater than the acceleration rate limiting threshold value I3. If the motor current Im is equal to or greater than the acceleration rate limiting threshold value I3 (S203? Yes), the process of the inverter control means 40 proceeds to step S204. On the other hand, when the motor current Im is less than the acceleration rate limiting threshold value I3 (S203? No), the process of the inverter control means 40 proceeds to step S205.

In step S204, the inverter control means 40 sets the acceleration command value of the motor M to the predetermined value (?) And outputs the drive signal to the drive signal generation unit 44. [ As described above, the predetermined value? Is a preset value of zero or more. In step S205, the inverter control means 40 holds the normal acceleration command value?. The command value? Is a preset value equal to or greater than the predetermined value?. In this case, the inverter control means 40 drives the motor M by performing normal operation.

10 is a characteristic diagram showing the relationship between the rotational speed and the motor phase current when the acceleration rate limit value of the compressor driving motor is ⁰ min ^-1 / sec in the air conditioner using the motor driving apparatus according to the present embodiment. On the other hand, the horizontal axis in Fig. 10 represents the rotational speed of the motor M, and the vertical axis represents the peak value of the motor current.

10, the peak value of the motor current increases in proportion to the rotational speed of the motor M and also changes under the condition of the same rotational speed in accordance with the change of the discharge pressure (compressor pressure) of the compressor 1. That is, even when the motor M is driven at a predetermined rotational speed, the discharge pressure of the compressor 1 (see FIG. 1) also increases as the value of the motor current increases.

For example, when the rotational speed of the motor M and the state of the motor current are the point P shown in Fig. 10, the motor current also increases as the rotational speed of the motor M increases. Further, since the temperature of the motor M is raised by the motor current, the motor potato protection threshold value also rises. That is, as the state of the point P moves toward the upper right of FIG. 10, the motor potato protection threshold rises as well.

Here, by limiting the acceleration rate of the motor M (for example,? = 0) as described above, the state in which the motor potentiometer protection threshold is always above the motor current corresponding to the point P continues . It is possible to reliably avoid the demagnetization of the motor M while increasing the rotational speed of the motor M while adjusting the acceleration rate.

<Effect>

The motor drive apparatus 100 according to the present embodiment sets the state of the motor M to the state of the motor M by setting the acceleration rate? (? 0) in the region between the motor potato protection threshold and the acceleration rate limiting threshold value I3 Can be changed to follow the acceleration rate limiting threshold value (I3) which is the boundary of the area C.

Therefore, as shown in Fig. 8, the rotational speed of the motor M can be raised while reliably preventing the motor current from reaching the motor potato protection threshold value. That is, the motor M can be quickly moved to the target rotation speed while avoiding the potato of the permanent magnet of the motor M.

Even when the acceleration rate limit value in the area B shown in Fig. 10 is set to 0 min ^-1 / sec (i.e., not accelerated), the motor winding temperature rises (e.g., from -20 캜 to + 80 캜) Potato current increases. Therefore, since the motor potentiometer protection threshold is also raised, the motor M can be smoothly reached at the target rotation speed while avoiding the potato of the permanent magnet of the motor M. [

&Quot; Third Embodiment &

Next, 3rd Embodiment is described. In each of the above embodiments, the acceleration rate is changed corresponding to the winding temperature of the motor M and the motor current value. In the third embodiment, by adjusting the opening degree of the expansion valve 4, Will be described. On the other hand, in the compressor 1 (see Fig. 1), the pressure is changed by controlling the rotational speed of the motor M provided in the compressor 1. [

For example, when performing the heating operation, the high-temperature high-pressure gas refrigerant discharged from the compressor 1 (see FIG. 1) is discharged to the indoor heat exchanger 5 through the four-way valve 2 and condensed, do. This high-pressure liquid refrigerant is decompressed by the expansion valve 4 as a decompression device, and is evaporated and absorbed in the outdoor heat exchanger 3 to become a gasified state. Then, the refrigerant returns to the compressor 1 through the four-way valve 2 and is compressed.

In this embodiment, appropriate air control capability is obtained by using such a heat pump cycle, and the opening degree of the expansion valve 4 is adjusted in accordance with the rotation speed of the compressor 1.

The air conditioner A according to the present embodiment includes a current threshold value setting unit 45 (not shown) and an expansion valve opening degree changing unit (not shown).

The current threshold setting unit 45 sets the current threshold value when the opening degree of the expansion valve 4 is changed corresponding to the motor temperature detected by the motor temperature detection means. The expansion valve opening degree changing section compares the motor current corresponding to the current value detected by the current detector 20 with the current threshold value inputted from the current threshold value setting section 45 and controls the expansion valve 4) is changed. Incidentally, the process performed by the current threshold value setting unit 45 and the process performed by the expansion valve opening degree varying unit are executed by the microcomputer in conjunction with the inverter control unit 40.

11 is a flow chart showing the flow of processing performed by the control means of the air conditioner.

The processes in steps S301 and S302 shown in FIG. 11 are the same as the processes in steps S101 and 102 in FIG. 5 in the first embodiment, respectively, and therefore the description thereof will be omitted.

In step S303, the inverter control means 40 determines whether or not the motor current Im is equal to or greater than the current threshold value I4. When the motor current Im is equal to or larger than the current threshold value I4 (Yes in S303), the process of the inverter control means 40 proceeds to step S304. On the other hand, when the motor current Im is less than the current threshold value I4 (S303? No), the process of the inverter control means 40 proceeds to step S305.

In step S304, the inverter control means 40 opens the opening degree of the expansion valve 4 by the predetermined value DELTA epsilon. In step S305, the inverter control means 40 operates the expansion valve 4 in accordance with the target opening degree (step S305).

For example, when the motor M is driven at a predetermined rotational speed and the motor current reaches a predetermined current threshold value or more, the opening degree of the expansion valve 4 is increased to reduce the discharge pressure of the compressor 1 do. Thus, the acceleration can be suppressed while increasing the rotation speed of the motor M, thereby preventing the motor current from exceeding the motor potentiometer protection threshold value. Therefore, desired heating can be realized even when the air conditioner A is in the ascending operation, without stopping the driving of the motor M (i.e., driving the compressor 1).

FIG. 12A is an explanatory diagram showing a change in the motor current characteristic when the pressure of the compressor is changed when the torque disturbance suppression control is performed, FIG. 12B shows the torque fluctuation suppression control executed Fig. 2 is an explanatory diagram showing a phase current waveform in the region 1 in which the current fluctuation suppressing control is performed and the region 2 in which the current fluctuation suppressing control is executed.

On the other hand, Fig. 12 (a) shows a compressor (1) used in the air conditioner (A), which is a rotary type or a reciprocating type, 1) is used as the motor current characteristic. In such a case, torque disturbance suppression control (torque fluctuation suppression control and current fluctuation suppression control) is performed to suppress torque disturbance.

Since the region T shown in FIG. 12 (b) is in the low-speed rotation region, a large torque fluctuation easily occurs in the compressor 1, and the larger the compressor pressure, the larger the vibration. In this low-speed rotation region, torque fluctuation suppression control is executed. Incidentally, the torque fluctuation suppression control is a control for controlling the duty ratio of the PWM signal to obtain the necessary torque in accordance with the rotational angular velocity of the compression process.

On the other hand, since the region I shown in Fig. 12B is a high-speed rotation region, the current fluctuation suppressing control is performed so as to suppress the fluctuation of the motor current to be close to the sinusoidal wave although the torque fluctuation is comparatively small.

That is, as shown by the characteristic of the compressor pressure in Fig. 12, even in the condition of the same compressor pressure (for example, the compressor load standard (solid line)), the peak current of the motor M becomes larger . Then, in the deceleration protection by the conventional potato protection control, particularly when the motor current reaches the motor potato protection threshold immediately before the transition from the T area to the I area, the phenomenon that the motor M repeats the operation / do. In the process of increasing the rotation speed, a phenomenon of operation / stopping appears at a rotation speed of about 3500 min &lt; ^-1 &gt;

13 is an explanatory diagram showing changes in the motor current characteristic when the pressure of the compressor 1 is changed when the torque disturbance suppression control is performed, and the bold line shows an example of the actual load. On the other hand, the horizontal axis in Fig. 13 indicates the rotational speed of the motor M, and the vertical axis indicates the motor current.

In the present embodiment, as shown in the example of the actual load shown by the solid line in Fig. 13, when the rotational speed reaches the acceleration rate limit threshold value, the motor current is suppressed by increasing the opening degree of the expansion valve 4 by a predetermined value. As a result, the rotation speed of the motor M is gradually increased while the peak value of the motor current is reduced, and smooth transition from the torque fluctuation suppression control to the current fluctuation suppression control can be achieved. Therefore, the stopping risk of the motor (M) driving the compressor (1) is reduced, and the compressor (1) can be driven stably even during the rising operation of the air conditioner (A) at low temperature.

<Effect>

Further, according to the air conditioner (A) according to the embodiment of the present invention, the pressure of the compressor (1) in the heat pump cycle is adjusted by controlling the opening degree of the expansion valve (4). Thus, the air conditioner A can be stably and continuously operated by gradually increasing the rotational speed of the motor M while reducing the peak value of the motor current.

Further, when shifting from the torque fluctuation suppression control to the current fluctuation suppression control, the peak current of the motor M becomes small, so that the motor M can be accelerated while maintaining a high acceleration rate.

Further, by increasing the opening degree of the expansion valve 4 while maintaining or increasing the rotational speed of the motor M, the peak current can be reduced. Thus, it is possible to quickly reach the target rotation speed of the motor M while suppressing the magnetization of the permanent magnet of the motor M.

"Variations"

As described above, the motor driving apparatus 100 according to the present invention has been described with reference to each embodiment. However, the embodiment of the present invention is not limited to these descriptions, and various modifications can be made.

For example, in the first embodiment, the case where two acceleration rate regions (region A and region B) are set is described. In the second embodiment, when one acceleration rate region (region C) is set But the present invention is not limited to this. That is, there may be three or more regions in which the acceleration rate is set. In this case, it is preferable that the value of the acceleration rate of each region be made smaller as the value of the motor current approaches the motor potato protection threshold value described above.

Thus, as the motor current approaches the motor potentiometer protection threshold value, the acceleration rate can be reduced stepwise while increasing the rotation speed of the motor M. [

In the first embodiment, the case where the acceleration rates set in correspondence with the two areas are all positive values is described, but the present invention is not limited to this. For example, in a case where there is no allowance of the rated current and the motor potato current, the acceleration rate of the region closest to the motor potato protection threshold may be zero (that is, a constant rotation speed is maintained without accelerating) . In this case, by rotating the motor M at a constant speed, the motor current is kept at a substantially constant value, and the motor winding temperature is also raised. Therefore, it is possible to reliably prevent the motor current from exceeding the motor potato protection threshold.

In the above-described embodiments, the motor winding temperature detector 50 detects the motor winding temperature, but the present invention is not limited to this. For example, the temperature of the winding of the motor M may be indirectly detected by an outer temperature detection means (not shown) for detecting the temperature of the outer periphery of the compressor 1 (not shown).

This protects the motor potentiometer based on the correlation between the temperature of the outer periphery of the compressor 1 and the motor potentiometer protection threshold value, thereby protecting the motor M appropriately. Further, as compared with the case where the temperature detector is provided inside the compressor 1 which becomes a high pressure, the attachment structure of the temperature detector (outer temperature detection means) and the lead-out structure of the signal line are simplified, and the manufacturing cost can be reduced.

The winding temperature of the motor M may indirectly be obtained by the discharge pipe temperature detecting means (not shown) for detecting the discharge pipe temperature of the compressor 1. [

In each of the above-described embodiments, the permanent magnet type synchronous motor is used as the motor M. However, the present invention is not limited to this. That is, the above-described embodiments can be similarly applied to other synchronous motors such as a wire-wound synchronous motor and a reluctance motor.

Further, in each of the above-described embodiments, when the alternating-current voltage input from the alternating-current power supply 200 is converted into the direct-current voltage by the converter 300 and further converted into the predetermined alternating-current voltage by the switching element of the inverter 11 being driven The present invention is not limited to this. For example, a DC voltage may be input to the inverter 11 from a battery (DC power source: not shown).

In the above-described embodiments, the case where the motor M having the permanent magnet with the low-temperature potato characteristic is used is described, but the present invention is not limited to this. That is, even when permanent magnets of high-temperature potato characteristics (for example, rare-earth magnets including neodymium magnets) that are easy to potentiate in a high-temperature environment are used, the driving of the motor M is controlled in the same manner as in the above- can do.

A: Air conditioner Iu: Indoor unit
Ou: outdoor unit 1: compressor
2: Four-way valve 3: Outdoor heat exchanger
4: expansion valve 5: indoor heat exchanger
L: refrigerant piping 100: motor driving device
11: inverter 12: element short-circuit protection means
13: inverter drive circuit 20: current detector (current detection means)
30: Amplifier 40: Inverter control means (control means)
44: driving signal generating unit 45: current threshold setting unit
46: Acceleration rate setting unit
50: Motor winding temperature detector (motor temperature detecting means)
M: Motor

Claims (11)

An inverter for converting a DC voltage input from a DC power source into an AC voltage; current detecting means provided on a DC side of the inverter; motor temperature detecting means for detecting a temperature of a motor connected to the inverter; And a motor drive device for driving the motor by AC power from the inverter,
Wherein,
A current threshold setting unit for setting an acceleration rate limiting threshold value, which is a current threshold value for limiting the acceleration rate of the motor, in accordance with the motor temperature detected by the motor temperature detecting unit;
An acceleration rate setting unit that compares the motor current corresponding to the current value detected by the current detection unit with the acceleration rate limiting threshold input from the current threshold setting unit and sets the acceleration rate of the motor according to the comparison result, Wow,
And a drive signal generator for outputting a drive signal to the inverter according to the acceleration rate set by the acceleration rate setting unit. The method of claim 1,
And storage means for storing information on an acceleration rate region in which the motor current of a predetermined range is previously associated with the motor temperature and the acceleration rate is associated with the motor current in the range,
Wherein the boundary of the acceleration rate region includes a potato protection threshold that is a current threshold for demagnetizing protection of the motor and the acceleration rate limiting threshold that is set as a current threshold less than the potato protection threshold,
Wherein one or a plurality of the acceleration rate regions are provided, and the acceleration rate is set to be smaller as the acceleration threshold value is approached,
Wherein the acceleration rate setting section specifies the acceleration rate region to which the motor current belongs and outputs the acceleration rate corresponding to the acceleration rate region to the drive signal generation section. 3. The method of claim 2,
Wherein the acceleration rate corresponding to each of the acceleration rate regions is zero or more. The method of claim 3,
Wherein the acceleration rate setting unit increases the acceleration rate of the motor when the acceleration rate limiting threshold is greater than the motor current when the acceleration rate limiting threshold increases with temperature rise of the motor Motor drive device. 5. The method of claim 4,
Wherein the acceleration rate setting unit outputs a predetermined acceleration rate to the drive signal generating unit when the motor current is lower than the respective acceleration rate limiting threshold values. The method of claim 5,
Wherein the acceleration rate setting section outputs a command signal to the drive signal generating section to stop driving the inverter when the motor current reaches the potato protection threshold. The method according to claim 6,
Wherein the motor has a permanent magnet having a low-temperature potato characteristic that is easy to potentiate at a low temperature. The method of claim 7, wherein
Wherein the permanent magnet is a ferrite magnet. An air conditioner comprising: a compressor provided with a motor drive apparatus according to any one of claims 1 to 8, in which a motor driven by the motor drive apparatus is installed; an outdoor heat exchanger; an expansion valve; an indoor heat exchanger; And connected by a refrigerant pipe to constitute a heat pump cycle. 10. The method of claim 9,
Wherein,
A current threshold setting unit for setting a current threshold when changing the opening degree of the expansion valve in accordance with a motor temperature detected by the motor temperature detecting unit;
And an expansion valve opening degree changing section for comparing the motor current corresponding to the current value detected by the current detection section with the current threshold value inputted from the current threshold value setting section and changing the opening degree of the expansion valve in accordance with the comparison result The air conditioner comprising: A motor drive method for converting a DC voltage input to an inverter from a DC power supply to an AC voltage and driving a motor connected to the inverter,
A current threshold setting processing for setting an acceleration rate limiting threshold value, which is a current threshold value for limiting the acceleration rate of the motor, in accordance with the motor temperature detected by the motor temperature detecting means;
A motor current to be reproduced corresponding to a current value detected by the current detecting means is compared with the acceleration rate limiting threshold value set by the current threshold value setting process and an acceleration rate setting for setting the acceleration rate of the motor in accordance with the comparison result Processing,
And a drive signal generating process for outputting a drive signal to the inverter according to the acceleration rate set by the acceleration rate setting process.

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