JPWO2019146037A1 - Motor drive device and air conditioner - Google Patents

Abstract

The motor drive device (200) uses a power generation unit (2) for converting electric power supplied from the commercial power supply (1) into DC power and a modulation method for driving the motor (13) into two-phase modulation or three-phase modulation. A motor drive control unit (7) that can be switched and an inverter output unit (6) that is controlled by the motor drive control unit (7) and that supplies the motor (13) with the AC power obtained by converting the DC power according to the modulation method. A temperature detection unit (10) for detecting the temperature of the inverter output unit (6) or the temperature of the motor drive control unit (7), and the current supplied from the inverter output unit (6) to the motor (13). And a current detection section (11) for controlling the motor drive control section (7) from three-phase modulation to two-phase modulation when the current is smaller than the current threshold value and the temperature is equal to or higher than the first temperature threshold value. And a control unit (4) for changing.

Description

The present invention relates to a motor drive device and an air conditioner for driving and controlling a motor of an indoor unit.

In equipment equipped with a motor, drive control of the motor is performed using a three-phase inverter circuit that converts DC power into three-phase AC power from the viewpoint of energy efficiency and economy.

In Patent Document 1, a series of IGBT (Insulated Gate Bipolar Transistor) and MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) series circuits, which are switching elements, are provided for three phases, and two series circuits of each series circuit are provided. Each IGBT turns on and off and the remaining one MOSFET in the series circuit turns on, and each IGBT in each series circuit turns on and off at different phases, and each MOSFET turns on at the opposite phase. The energy conversion efficiency is improved by selectively executing the three-phase energization to turn off the power depending on the level of the load.

JP, 2008-104282, A

In the conventional technique as disclosed in Patent Document 1, the modulation method is changed based on the load situation. However, in such a conventional technique, when the ambient temperature of the inverter circuit is high, the inverter element of the inverter circuit becomes high temperature even when the load is low, and the fan motor stops operating due to the overheat protection function of the inverter element. In addition, the inverter element may be destroyed.

Even if there is no problem with the temperature of the inverter element, the motor drive control is performed when the temperature of the motor drive control unit that outputs a signal to drive the motor to the inverter circuit and controls the motor exceeds the guaranteed operating temperature range. It may not work properly and the fan motor drive may stop.

The present invention is made in view of the above, and an object of the present invention is to obtain a motor drive device which can control stop of a motor.

In order to solve the above-mentioned problems and to achieve the object, the present invention provides a power supply generation unit that converts electric power supplied from a commercial power supply into DC power, and a modulation method that drives a motor using two-phase modulation or three-phase modulation. A motor drive control unit that can be switched to and an inverter output unit that is controlled by the motor drive control unit and that supplies the motor with AC power obtained by converting DC power according to a modulation method. Further, according to the present invention, a temperature detection unit that detects the temperature of the inverter output unit or the temperature of the motor drive control unit, a current detection unit that detects the current supplied from the inverter output unit to the motor, and a current threshold The motor drive control unit includes a control unit that changes the modulation method from three-phase modulation to two-phase modulation when the temperature is smaller than the value and the temperature is equal to or higher than the first temperature threshold.

The motor drive device according to the present invention has an effect that it is possible to suppress the stop of the motor.

The figure which shows the structure of the air conditioner concerning Embodiment 1 of this invention. The flowchart explaining operation|movement of the air conditioner concerning Embodiment 1. The figure which shows the time threshold of the electric current threshold value, demagnetization electric current value, and electric current concerning Embodiment 1. FIG. 3 is a diagram showing the first and second temperature threshold values, the overheat protection threshold value, and the time change of the current according to the first embodiment. The flowchart including the operation of changing the modulation method of the motor according to the first embodiment from two-phase modulation to three-phase modulation. FIG. 3 is a diagram showing the first, second, and third temperature threshold values, the overheat protection threshold value, and the time change of the current according to the first embodiment. The figure which shows the structure of another air conditioner concerning Embodiment 1. The figure which shows the structure of the air conditioner concerning Embodiment 2 of this invention. Block diagram showing the configuration of the microcomputer according to the first and second embodiments

Hereinafter, a motor drive device and an air conditioner according to an embodiment of the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment.

Embodiment 1.
FIG. 1 is a diagram showing a configuration of an air conditioner 100 according to the first embodiment of the present invention. The air conditioner 100 includes a motor drive device 200 and a motor 13. The motor drive device 200 includes a power supply generation unit 2, a power supply circuit unit 3, a main body control unit 4, a drive power supply unit 5, an inverter output unit 6 which is a switching circuit having an inverter element, and a motor drive control unit 7. The temperature detector 10, the current detector 11, and the voltage detector 12 are provided.

The input side of the power supply generation unit 2 is connected to the commercial power supply 1, and the output side is connected to the power supply circuit unit 3 and the inverter output unit 6. The power supply generation unit 2 converts the first AC power supplied from the commercial power supply 1 into DC power and supplies the DC power to the power supply circuit unit 3 and the inverter output unit 6. The motor drive control unit 7 outputs a signal for driving the motor 13 to the inverter output unit 6 to control the inverter output unit 6.

A specific example of the inverter output unit 6 is a circuit in which three series circuits in which two switching elements which are inverter elements are connected in series are connected in parallel corresponding to each of the three phases. When the modulation method is three-phase modulation, the inverter output section 6 outputs three-phase AC power whose phases are shifted by 120° C., and when the modulation method is two-phase modulation, the inverter output section 6 outputs 90 phases. Two-phase AC power that is deviated by ℃ is output. Switching between the three-phase modulation and the two-phase modulation is performed by changing the switching pattern of the switching element of the above circuit.

The motor drive control unit 7 can switch the modulation method in which the inverter output unit 6 drives the motor 13 to two-phase modulation or three-phase modulation by changing the switching pattern. The inverter output unit 6 supplies to the motor 13 second AC power obtained by converting the DC power supplied from the power supply generation unit 2 according to the above-described modulation method.

The power supply circuit unit 3 is connected to each of the main body control unit 4, the drive power supply unit 5, and the temperature detection unit 10, and supplies power to each. The drive power supply unit 5 is connected to each of the inverter output unit 6 and the motor drive control unit 7, and supplies electric power to each.

The main body control unit 4 is a control unit of the entire air conditioner 100, and is connected to the motor drive control unit 7. The main body control unit 4 and the motor drive control unit 7 can bidirectionally communicate with each other. Mutual communication between the main body control unit 4 and the motor drive control unit 7 can be performed periodically. The main body control unit 4 is also connected to the drive power supply unit 5 so that the drive power supply unit 5 can be controlled to either an ON state in which power is supplied or an OFF state in which power is not supplied. The main body control unit 4 turns on or off the drive power supply unit 5 as necessary to control whether or not the drive power supply unit 5 supplies power to the inverter output unit 6 and the motor drive control unit 7. In FIG. 1, the main body control unit 4 is connected to the drive power supply unit 5 so as to control the drive power supply unit 5, but the main body control unit 4 does not control the drive power supply unit 5 and The power supply unit 5 may be configured to constantly supply power. Further, a control unit in which the main body control unit 4 and the motor drive control unit 7 are integrated may be provided in the motor drive device 200, and the integrated control unit controls the entire air conditioner 100. It may be provided, or the integrated control unit may be configured to control the entire motor drive device 200.

The drive power supply unit 5 starts power supply to the inverter output unit 6 and the motor drive control unit 7 when turned on, and stops power supply to the inverter output unit 6 and the motor drive control unit 7 when turned off. The temperature detection unit 10 is a temperature detection unit of the motor drive circuit that detects the temperature around the drive circuit of the motor 13, such as the temperature of the inverter output unit 6 or the temperature of the motor drive control unit 7. The temperature detection unit 10 may include a plurality of detection units that detect the respective temperatures, such as a detection unit that detects the temperature of the inverter output unit 6 and a detection unit that detects the temperature of the motor drive control unit 7. Absent. The temperature detection unit 10 transmits the detected temperature to the main body control unit 4. The current detection unit 11 detects the current supplied from the inverter output unit 6 to the motor 13 and sends the detected current value to the motor drive control unit 7. The current value transmitted to the motor drive control unit 7 is transmitted to the main body control unit 4 by the motor drive control unit 7. The voltage detection unit 12 detects the voltage supplied from the power supply generation unit 2 to the inverter output unit 6, and transmits the detected voltage value to the motor drive control unit 7. The motor drive control unit 7 or the main body control unit 4 can control the inverter output unit 6 using the above voltage value in addition to the current value detected by the current detection unit 11.

Next, the operation of the air conditioner 100 according to the first embodiment will be described. When the commercial power supply 1 is connected to the power supply generation unit 2, DC power is generated, and the generated DC power is supplied to the power supply circuit unit 3 and the inverter output unit 6. When the DC power is supplied, the power supply circuit unit 3 supplies power to each of the main body control unit 4, the drive power supply unit 5, and the temperature detection unit 10. The operation after the supply of electric power to the main body control unit 4, the driving power supply unit 5, and the temperature detection unit 10 is started will be described below with reference to FIG. FIG. 2 is a flowchart illustrating the operation of the air conditioner 100 according to the first embodiment.

First, the main body control unit 4 turns on the drive power supply unit 5 (step S1). As a result, power supply to the motor drive control unit 7 is started and the motor drive control unit 7 starts up. When the main body control unit 4 does not control the drive power supply unit 5 and the drive power supply unit 5 is always on, the operation of step S1 is omitted.

After step S1, communication is started between the main body controller 4 and the motor drive controller 7 (step S2). When the motor drive control unit 7 receives the motor drive command from the main body control unit 4, the motor drive control unit 7 outputs a signal for driving the motor 13 to the inverter output unit 6 (step S3), and the motor 13 drives (step S3). S4). It is assumed that the motor driving modulation method here is three-phase modulation. After the motor 13 starts driving, the temperature detection unit 10 and the current detection unit 11 each start detection and transmit the detection result to the main body control unit 4 (step S5). The temperature detection unit 10 directly transmits the temperature that is the detection result to the main body control unit 4, and the current detection unit 11 transmits the current value that is the detection result to the main body control unit 4 once via the motor drive control unit 7. ..

The storage unit of the main body control unit 4 holds a current threshold value for the current value detected by the current detection unit 11. The current threshold value is set to a current value that does not damage the driven motor 13. FIG. 3 is a diagram showing the current threshold value, the demagnetization current value, and the time change of the current according to the first embodiment. As shown in FIG. 3, there is a demagnetization current value as a value of the current that causes the magnet of the motor 13 to be demagnetized. When the load of the motor 13, which is a fan motor, increases due to the accumulation of dust and the like in the air passage of the air conditioner 100, the current value supplied to the motor 13 increases, and when the demagnetization current value is reached, the motor 13 Destruction may occur. Therefore, the current threshold value is set to a current value lower than the demagnetization current value so that the motor 13 is not destroyed.

Further, the storage unit of the main body control unit 4 holds the first and second temperature threshold values for the temperature detected by the temperature detection unit 10. The first and second temperature threshold values are set to values such that the drive circuit is not destroyed by the temperature rise or the driving of the motor 13 is not stopped. FIG. 4 is a diagram showing the first and second temperature threshold values, the overheat protection threshold value, and the time change of the current according to the first embodiment. To set the first and second temperature thresholds to a temperature at which the drive circuit is not destroyed or the drive of the motor 13 is not stopped, the threshold for overheat protection of the inverter element of the inverter output unit 6 is set. It may be set so as not to exceed the limit, or may be set so as not to exceed the operation guarantee temperature range of the motor drive control unit 7 that controls the motor drive. In FIG. 4, the threshold for overheat protection of the inverter element is shown as an example of the temperature that the first and second temperature thresholds should not exceed. Then, the first temperature threshold value is set at a temperature lower than the threshold value for this overheat protection. Further, the second temperature threshold value is provided at a temperature lower than the overheat protection threshold value and higher than the first temperature threshold value. That is, the second temperature threshold is greater than the first temperature threshold. As a specific example, the first temperature threshold is 90°C and the second temperature threshold is 100°C.

After step S5, the body control unit 4 determines whether or not the current value detected by the current detection unit 11 is greater than or equal to the set current threshold value (step S6). When the detected current value is equal to or higher than the current threshold value (step S6: Yes), the main body control unit 4 transmits a command to decrease the target rotation speed of the motor 13 to the motor drive control unit 7 to drive the motor. The control unit 7 controls the inverter output unit 6 so as to reduce the target rotation speed (step S7). In this way, the target rotation speed of the motor 13 is reduced and the current value detected by the current detection unit 11 is lowered as shown in FIG. 3, so that the current value does not reach the demagnetization current value. After step S7, the process returns to step S5.

When the detected current value is smaller than the current threshold value (step S6: No), the body control unit 4 determines whether the temperature detected by the temperature detection unit 10 is equal to or higher than the set first temperature threshold value. It is determined whether or not (step S8). When the detected temperature is lower than the set first temperature threshold value (step S8: No), the main body control unit 4 continues the current motor control (step S9). After step S9, the process returns to step S5.

When the detected temperature is equal to or higher than the set first temperature threshold value (step S8: Yes), the main body control unit 4 issues a command to change the motor drive modulation method from three-phase modulation to two-phase modulation. The signal is transmitted to the motor drive control unit 7, and the motor drive control unit 7 is made to control the inverter output unit 6 so as to change the modulation method to the two-phase modulation (step S10). By changing the modulation method to two-phase modulation, the frequency of switching is reduced compared to three-phase modulation, so the switching loss during motor driving is reduced, so the temperature rise of the inverter element can be suppressed more than in three-phase modulation. ..

After changing to the two-phase modulation, the temperature detection unit 10 and the current detection unit 11 again transmit the detection results to the main body control unit 4 (step S11). The temperature detection unit 10 directly transmits the detected temperature to the main body control unit 4, and the current detection unit 11 transmits the detected current value to the main body control unit 4 via the motor drive control unit 7.

After step S11, the body control unit 4 determines whether or not the current value detected by the current detection unit 11 is equal to or more than the set current threshold value (step S12). When the detected current value is equal to or higher than the current threshold value (step S12: Yes), the main body control unit 4 reduces the target rotation speed of the motor 13 (step S13). By reducing the target rotation speed of the motor 13 and lowering the current value detected by the current detection unit 11, the current value does not reach the demagnetization current value. After step S13, the process returns to step S11.

When the detected current value is smaller than the current threshold value (step S12: No), the body control unit 4 determines whether the temperature detected by the temperature detection unit 10 is equal to or higher than the set second temperature threshold value. It is determined whether or not (step S14). When the detected temperature is lower than the set second temperature threshold value (step S14: No), the main body control unit 4 continues the current motor control (step S15). After step S15, the process returns to step S11.

When the detected temperature is equal to or higher than the set second temperature threshold value (step S14: Yes), the main body control unit 4 decreases the target rotation speed of the motor 13 as shown in FIG. 4 (step S13). ). In other words, even if the motor drive modulation method was two-phase modulation, the temperature rise could not be suppressed, so the temperature rise was suppressed by reducing the target rotation speed, and overheating stopped the drive of the motor 13 or destroyed the drive circuit. Try not to do it. After step S13, the process returns to step S11.

By operating the motor 13 as described above, the motor drive device 200 according to the first embodiment can keep driving the motor 13 as much as possible and suppress the stop regardless of the temperature around the motor drive circuit. become. That is, it is possible to reduce the frequency at which the driving of the motor 13 is stopped to break or protect the drive circuit of the motor 13. Then, by continuing to drive the motor 13, comfort can be maintained.

In the flowchart of FIG. 2 described above, if the modulation method is changed to the two-phase modulation in order to suppress the temperature rise in step S10, then the three-phase modulation is not resumed. However, the three-phase modulation has an advantage that the carrier sound is smaller than that of the two-phase modulation. Therefore, if the temperature detected by the temperature detection unit 10 of the motor drive device 200 becomes lower than another threshold value lower than the first temperature threshold value after suppressing the temperature rise by the two-phase modulation, By changing the modulation method back to three-phase modulation, it is possible to reduce the carrier sound and further improve the comfort of the user.

FIG. 5 is a flowchart including an operation of changing the modulation method of the motor 13 according to the first embodiment from two-phase modulation to three-phase modulation. FIG. 6 is a diagram showing the first, second, and third temperature threshold values, the overheat protection threshold value, and the time change of the current according to the first embodiment. In addition to FIG. 4, FIG. 6 shows a third temperature threshold value with respect to the temperature detected by the temperature detection unit 10. The third temperature threshold value is set to a temperature lower than the first temperature threshold value, that is, a value smaller than the first temperature threshold value, and the storage unit of the main body control unit 4 adds to the first and second temperature threshold values. Holds the third temperature threshold. As a specific example, the first temperature threshold is 90°C, the second temperature threshold is 100°C, and the third temperature threshold is 80°C.

In the flowchart of FIG. 5, first, the motor 13 is driven by two-phase modulation (step S10'). Subsequent steps S11, S12, S13 and S14 are the same operations as steps S11, S12, S13 and S14 of FIG. Hereinafter, in order to return the modulation method to the three-phase modulation, the points different from step S14 onward in FIG. 2 will be described.

When the detected temperature is lower than the set second temperature threshold value (step S14: No), the body control unit 4 sets the third temperature threshold value at which the temperature detected by the temperature detection unit 10 is set. It is determined whether the value is less than or equal to the value (step S16). When the detected temperature is higher than the set third temperature threshold value (step S16: No), the main body control unit 4 continues the current motor control (step S17). After step S17, the process returns to step S11.

When the detected temperature is equal to or lower than the set third temperature threshold value (step S16: Yes), the main body control unit 4 issues an instruction to change the motor driving modulation method from two-phase modulation to three-phase modulation. The signal is transmitted to the motor drive control unit 7, and the motor drive control unit 7 controls the inverter output unit 6 so as to change the modulation method to three-phase modulation (step S18). After step S18, the process may proceed to step S5 of FIG. That is, if the steps S11 to S15 in FIG. 2 are replaced with steps S11 to S18 in FIG. 5 and after step S18, the process proceeds to step S5 in FIG. It is also possible to perform control for appropriately switching between the two-phase modulation and the two-phase modulation.

In the motor drive device 200 according to the first embodiment, by operating the motor 13 as described above, the drive of the motor 13 can be continued as much as possible and the stop can be suppressed regardless of the temperature around the motor drive circuit. Since the carrier sound of the motor 13 can be reduced as much as possible, the comfort can be further maintained.

FIG. 7 is a diagram showing the configuration of another air conditioner 101 according to the first embodiment. The air conditioner 101 includes a motor drive device 201 and a motor 13. The motor drive device 201 has a configuration in which the voltage detection unit 12 is removed from the motor drive device 200 of FIG. The air conditioner 101 of FIG. 7 having a simpler configuration than the air conditioner 100 can also perform the operations of FIGS.

Embodiment 2.
FIG. 8: is a figure which shows the structure of the air conditioner 102 concerning Embodiment 2 of this invention. The air conditioner 102 of FIG. 8 includes a motor drive device 202 and a motor 13. In the motor drive device 202, unlike the motor drive device 200 of FIG. 1 according to the first embodiment, the power supply circuit unit 3 is connected to each of the main body control unit 4 and the drive power supply unit 5, and supplies power to each. doing. The drive power supply unit 5 of the motor drive device 202 is connected to each of the inverter output unit 6, the motor drive control unit 7, and the temperature detection unit 10, and supplies electric power to each. Then, the temperature detection unit 10 of the motor drive device 202 transmits the temperature that is the detection result to the main body control unit 4 via the motor drive control unit 7 similarly to the current detection unit 11. The main body control unit 4 can control the drive power supply unit 5 to an on state or an off state. The drive power supply unit 5 starts supplying power to the inverter output unit 6, the motor drive control unit 7, and the temperature detection unit 10 when it is in the ON state, and when it is in the OFF state, the inverter output unit 6, the motor drive control unit 7, and the temperature detection unit. The power supply to the unit 10 is stopped. The configuration and operation of the air conditioner 102 other than this are the same as those of the air conditioner 100 of FIG. 1, so description thereof will be omitted.

When the drive of the motor 13 is stopped, the temperature detection unit 10 does not need to detect the temperature around the motor drive circuit. In the motor drive device 202 of FIG. 8, when the drive of the motor 13 is stopped, the main body control unit 4 turns off the drive power supply unit 5 and the power supply to the temperature detection unit 10 is stopped. .. As a result, energy can be saved compared to the motor drive device 200 according to the first embodiment.

It is needless to say that also in the air conditioner 102 according to the second embodiment, the operations of FIGS. 2 and 5 can be performed in the same manner as in the first embodiment, and the same effect as that of the first embodiment can be obtained. It is also possible to remove the voltage detection unit 12 from the motor driving device 202 like the motor driving device 201 of FIG. 7.

FIG. 9 is a block diagram showing the configuration of the microcomputer 50 according to the first and second embodiments. The main body control unit 4 according to the first and second embodiments can be realized by the microcomputer 50. The microcomputer 50 includes a CPU (Central Processing Unit) 51 that executes calculation and control, a RAM (Random Access Memory) 52 used by the CPU 51 in a work area, and a ROM (Read Only Memory) 53 that stores programs and data. An I/O (Input/Output) 54, which is hardware for exchanging signals with the outside, and a peripheral device 55 including an oscillator that generates a clock are provided. The control executed by the main body control unit 4 which is the microcomputer 50 according to the flowcharts shown in FIGS. 2 and 5 is realized by the CPU 51 executing a program which is software stored in the ROM 53. The ROM 53 may be a non-volatile memory such as a rewritable flash memory. Therefore, the storage unit of the main body control unit 4 that stores the current threshold value and the first, second, and third temperature threshold values is realized by the ROM 53 or the like.

The configurations described in the above embodiments are examples of the content of the present invention, and can be combined with other known techniques, and the configurations of the configurations are not departing from the scope of the present invention. It is also possible to omit or change parts.

DESCRIPTION OF SYMBOLS 1 commercial power supply, 2 power supply generation part, 3 power supply circuit part, 4 main body control part, 5 drive power supply part, 6 inverter output part, 7 motor drive control part, 10 temperature detection part, 11 current detection part, 12 voltage detection part , 13 motor, 50 microcomputer, 51 CPU, 52 RAM, 53 ROM, 54 I/O, 55 peripheral device, 100, 101, 102 air conditioner, 200, 201, 202 motor drive device.

Claims (8)

A power supply generation unit that converts the electric power supplied from the commercial power supply into DC power,
A motor drive control unit capable of switching the modulation method for driving the motor to two-phase modulation or three-phase modulation,
An inverter output unit that is controlled by the motor drive control unit and supplies AC power obtained by converting the DC power according to the modulation method to the motor.
A temperature detection unit that detects the temperature of the inverter output unit or the temperature of the motor drive control unit;
A current detection unit that detects a current supplied from the inverter output unit to the motor,
A controller that causes the motor drive controller to change the modulation method from three-phase modulation to two-phase modulation when the current is less than a current threshold and the temperature is equal to or higher than a first temperature threshold;
And a motor drive device. The motor drive device according to claim 1, wherein the control unit causes the motor drive control unit to reduce the target rotation speed of the motor when the current is equal to or higher than a current threshold value. When the current is lower than a current threshold and the temperature is equal to or higher than a second temperature threshold which is higher than the first temperature threshold, the controller controls the motor drive controller to target the motor. The motor drive device according to claim 1, wherein the rotation speed is reduced. When the current is less than a current threshold value and the temperature is less than or equal to a third temperature threshold value that is less than the first temperature threshold value, the control section controls the motor drive control section to apply the modulation method. The motor drive device according to claim 1, wherein the two-phase modulation is changed to the three-phase modulation. A drive power supply unit that supplies electric power to the inverter output unit and the motor drive control unit;
Power is supplied from the power generation unit, and a power supply circuit unit that supplies power to the control unit, the drive power supply unit, and the temperature detection unit,
Further equipped with,
The motor drive device according to claim 1, wherein the control unit controls whether or not power is supplied from the drive power supply unit. A drive power supply unit that supplies electric power to the inverter output unit, the motor drive control unit, and the temperature detection unit;
Power is supplied from the power generation unit, and a power supply circuit unit that supplies power to the control unit and the drive power supply unit,
Further equipped with,
The motor drive device according to claim 1, wherein the control unit controls whether or not power is supplied from the drive power supply unit. The motor drive device according to claim 1, further comprising a voltage detection unit that detects a voltage supplied from the power generation unit to the inverter output unit. An air conditioner comprising the motor drive device according to any one of claims 1 to 7 and the motor.

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