JP6847273B2 - Motor drive and air conditioner - Google Patents

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, the 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 circuit of an IGBT (Insulated Gate Bipolar Transistor) and a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), which are switching elements, is provided for three phases, and two series circuits of each series circuit are provided. Two-phase energization in which each IGBT is turned on and off and the MOSFET of the remaining one series circuit is turned on, and each IGBT of each series circuit is turned on and off in different phases and each MOSFET is turned on in the opposite phase. The efficiency of energy conversion is improved by selectively executing the three-phase energization, which is turned off, according to the height of the load.

Japanese Unexamined Patent Publication No. 2008-104282

In the prior art as in Patent Document 1, the modulation method is changed based on the load condition. 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 drive is stopped by the overheat protection function of the inverter element. Furthermore, it may lead to the destruction of the inverter element.

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 controls the motor by outputting a signal to drive the motor to the inverter circuit exceeds the guaranteed operating temperature range. It may not work properly, leading to a fan motor drive stop.

The present invention has been made in view of the above, and an object of the present invention is to obtain a motor drive device capable of suppressing a stop of a motor.

In order to solve the above-mentioned problems and achieve the object, the present invention uses a power generation unit that converts power supplied from a commercial power source into DC power, and a two-phase modulation or three-phase modulation method for driving a motor. It is provided with a motor drive control unit capable of switching to, and an inverter output unit that is controlled by the motor drive control unit and supplies AC power obtained by converting DC power according to a modulation method to the motor. Further, the present invention has 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. When the value is smaller than the value and the temperature is equal to or higher than the first temperature threshold value, the motor drive control unit is provided with a control unit for changing the modulation method from three-phase modulation to two-phase modulation.

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

The figure which shows the structure of the air conditioner which concerns on Embodiment 1 of this invention. A flowchart illustrating the operation of the air conditioner according to the first embodiment. The figure which shows the current threshold value, the demagnetizing current value and the time change of a current which concerns on Embodiment 1. The figure which shows the 1st and 2nd temperature threshold value, the threshold value of overheat protection and the time change of a current concerning Embodiment 1. FIG. A flowchart including an operation of changing the modulation method of the motor according to the first embodiment from two-phase modulation to three-phase modulation. The figure which shows the 1st, 2nd and 3rd temperature thresholds, the threshold value of overheat protection and the time change of a current concerning Embodiment 1. FIG. The figure which shows the structure of another air conditioner which concerns on Embodiment 1. The figure which shows the structure of the air conditioner which concerns on Embodiment 2 of this invention. The block diagram which shows the structure of the microcomputer which concerns on Embodiments 1 and 2.

Hereinafter, the motor drive device and the air conditioner according to the 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 a 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. A temperature detection unit 10, a current detection unit 11, and a voltage detection unit 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 generation unit 2 converts the first AC power supplied from the commercial power source 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, three-phase AC power whose phase is shifted by 120 ° C. is output from the inverter output unit 6, and when the modulation method is two-phase modulation, the phases are 90 each other from the inverter output unit 6. Two-phase AC power shifted by ° C is output. Switching between three-phase modulation and two-phase modulation is performed by changing the switching pattern of the switching element of the circuit.

By changing the switching pattern, 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. The inverter output unit 6 supplies the motor 13 with a second AC power obtained by converting the DC power supplied from the power generation unit 2 according to the above-mentioned 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 electric power to each of them. 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 of them.

The main body control unit 4 is a control unit for 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 communicate with each other in both directions. 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 in 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 controls whether or not power is supplied from the drive power supply unit 5 to the inverter output unit 6 and the motor drive control unit 7 by turning the drive power supply unit 5 on or off as needed. In FIG. 1, the main body control unit 4 is connected to the drive power supply unit 5 to control the drive power supply unit 5, but the main body control unit 4 drives the drive power supply unit 5 without controlling the drive power supply unit 5. The power supply unit 5 may be configured to constantly supply power. Further, the motor drive device 200 may be provided with a control unit in which the main body control unit 4 and the motor drive control unit 7 are integrated, and the integrated control unit controls the entire air conditioner 100. It may be present, or the integrated control unit may be configured to control the entire motor drive device 200.

When the drive power supply unit 5 is turned on, the power supply to the inverter output unit 6 and the motor drive control unit 7 is started, and when the drive power supply unit 5 is turned off, the power supply to the inverter output unit 6 and the motor drive control unit 7 is stopped. 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 for detecting each temperature, such as a detection unit for detecting the temperature of the inverter output unit 6 and a detection unit for detecting 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 transmits 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 by using the 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 power supply to the main body control unit 4, the drive 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. If 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 control unit 4 and the motor drive control unit 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 is driven (step S3). S4). It is assumed that the motor-driven 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, which is the detection result, to the main body control unit 4, and the current detection unit 11 once transmits the current value, which is the detection result, to the main body control unit 4 via the motor drive control unit 7. ..

The storage unit of the main body control unit 4 holds a current threshold value with respect to the current value detected by the current detection unit 11. The current threshold value is set to a current value so that the driven motor 13 is not destroyed. FIG. 3 is a diagram showing a current threshold value, a demagnetizing current value, and a time change of the current according to the first embodiment. As shown in FIG. 3, the demagnetization current value exists as the value of the current at which the magnet of the motor 13 is demagnetized. When the load of the motor 13 which is a fan motor rises due to the accumulation of dust or the like in the air passage of the air conditioner 100, the current value supplied to the motor 13 rises, and when the demagnetization current value is reached, the motor 13 Destruction can 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 with respect to the temperature detected by the temperature detection unit 10. The first and second temperature threshold values are set to a value such that the drive circuit is not destroyed by the temperature rise or the drive of the motor 13 is not stopped. FIG. 4 is a diagram showing the time variation of the first and second temperature threshold values, the overheat protection threshold value, and the current according to the first embodiment. Setting the first and second temperature thresholds to a temperature that does not destroy the drive circuit or a temperature that does not stop the drive of the motor 13 means that the threshold for overheat protection of the inverter element of the inverter output unit 6 is set. It is possible to set the temperature so as not to exceed the guaranteed operating temperature range of the motor drive control unit 7 that controls the motor drive. FIG. 4 shows the threshold value for overheat protection of the inverter element as an example of the temperature at which the first and second temperature threshold values should not be exceeded. Then, a first temperature threshold value is set at a temperature lower than the threshold value of this overheat protection. Further, a second temperature threshold is set at a temperature lower than the threshold for overheat protection and higher than the first temperature threshold. That is, the second temperature threshold is larger 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 main body control unit 4 determines whether or not the current value detected by the current detection unit 11 is equal to or greater than 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 reduce 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). By reducing the target rotation speed of the motor 13 in this way and lowering the current value detected by the current detection unit 11 as shown in FIG. 3, the current value does not reach the demagnetizing 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), does the main body control unit 4 check 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 smaller 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-driven modulation method from three-phase modulation to two-phase modulation. It is transmitted to the motor drive control unit 7 to cause the motor drive control unit 7 to control the inverter output unit 6 so as to change the modulation method to two-phase modulation (step S10). By using two-phase modulation as the modulation method, the frequency of switching is reduced compared to three-phase modulation, so that the switching loss during motor drive is reduced, so that the temperature rise of the inverter element can be suppressed compared to three-phase modulation. ..

After changing to two-phase modulation, the temperature detection unit 10 and the current detection unit 11 again transmit the detection result 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 main body control unit 4 determines whether or not the current value detected by the current detection unit 11 is equal to or greater than the set current threshold value (step S12). When the detected current value is equal to or greater 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 demagnetizing 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), does the main body control unit 4 check 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 smaller 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 reduces the target rotation speed of the motor 13 as shown in FIG. 4 (step S13). ). That is, since the temperature rise could not be suppressed even if the motor drive modulation method was two-phase modulation, the temperature rise was suppressed by reducing the target rotation speed, and the drive of the motor 13 was stopped or the drive circuit was destroyed due to overheating. 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 continue the drive of the motor 13 as much as possible regardless of the temperature around the motor drive circuit and suppress the stoppage. become. That is, it is possible to reduce the frequency with which the drive of the motor 13 is stopped due to the destruction or protection of 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 two-phase modulation in order to suppress the temperature rise in step S10, it does not return to three-phase modulation thereafter. However, three-phase modulation has the advantage that the carrier sound is smaller than that of two-phase modulation. Therefore, when the temperature detected by the temperature detection unit 10 of the motor drive device 200 becomes lower than another threshold value of a temperature lower than the first temperature threshold value after suppressing the temperature rise by two-phase modulation. , It is possible to return the modulation method to three-phase modulation to reduce the carrier sound and further improve the user's comfort.

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 smaller value, and the storage unit of the main body control unit 4 is added to the first and second temperature threshold values. It also holds a 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 have the same operations as steps S11, S12, S13, and S14 in FIG. 2, and thus description thereof will be omitted. Hereinafter, in order to return the modulation method to three-phase modulation, the points different from those after step S14 in FIG. 2 will be described.

When the detected temperature is smaller than the set second temperature threshold value (step S14: No), the main 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 or not it is equal to or less than the value (step S16). When the detected temperature is larger 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 a command to change the motor-driven modulation method from two-phase modulation to three-phase modulation. It is transmitted to the motor drive control unit 7 to cause the motor drive control unit 7 to control 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 parts of steps S11 to S15 in FIG. 2 are replaced with steps S11 to S18 in FIG. 5 and the process proceeds to step S5 in FIG. 2 after step S18, the motor-driven modulation method is three-phase modulated. It is also possible to control switching between and two-phase modulation as appropriate.

In addition to being able to continue driving the motor 13 as much as possible and suppress the stoppage of the motor driving device 200 according to the first embodiment by operating the motor 13 as described above, regardless of the temperature around the motor driving circuit. Since the carrier noise of the motor 13 can be reduced as much as possible, the comfort can be further maintained.

FIG. 7 is a diagram showing a 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 deleted from the motor drive device 200 of FIG. Even in the air conditioner 101 of FIG. 7 having a simpler configuration than the air conditioner 100, the operations of FIGS. 2 and 5 can be performed in the same manner as described above, and the same effect as described above can be obtained.

Embodiment 2.
FIG. 8 is a diagram showing the configuration of the air conditioner 102 according to the second embodiment of the present 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 to supply electric power to each of them. are 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 of them. Then, the temperature detection unit 10 of the motor drive device 202 transmits the temperature, which is the detection result, to the main body control unit 4 via the motor drive control unit 7 in the same manner as 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 starts supplying power to the inverter output unit 6, the motor drive control unit 7, and the temperature detection unit when it is in the OFF state. The power supply to the unit 10 is stopped. Since 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, the 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 saving can be achieved as compared with the motor driving device 200 according to the first embodiment.

It goes without saying that 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 drive device 202 as in the motor drive device 201 of FIG.

FIG. 9 is a block diagram showing the configuration of the microprocessor 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 microprocessor 50. The microcomputer 50 includes a CPU (Central Processing Unit) 51 that executes arithmetic and control, a RAM (Random Access Memory) 52 that the CPU 51 uses for a work area, and a ROM (Read Only Memory) 53 that stores programs and data. It includes 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. The control executed by the main body control unit 4 of 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, the first, second, and third temperature threshold values is realized by the ROM 53 or the like.

The configuration shown in the above-described embodiment shows an example of the content of the present invention, can be combined with another known technique, and is one of the configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

1 Commercial power supply, 2 Power supply generator, 3 Power supply circuit, 4 Main unit control, 5 Drive power supply, 6 Inverter output, 7 Motor drive control, 10 Temperature detector, 11 Current detector, 12 Voltage detector , 13 motors, 50 microcomputers, 51 CPUs, 52 RAMs, 53 ROMs, 54 I / O, 55 peripherals, 100, 101, 102 air conditioners, 200, 201, 202 motor drives.

Claims (7)

A power generator that converts the power supplied from a commercial power source into DC power,
A motor drive control unit that can switch the modulation method that drives 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, and
A current detection unit that detects the current supplied from the inverter output unit to the motor, and
When the current is smaller than the current threshold value and the temperature is equal to or higher than the first temperature threshold value, the motor drive control unit is made to change the modulation method from three-phase modulation to two-phase modulation, and the current is current. When the temperature is smaller than the threshold value and the temperature is greater than or equal to the second temperature threshold value, the motor drive control unit is provided with a control unit that reduces the target rotation speed of the motor.
Motor drive device. The motor drive device according to claim 1, wherein the control unit reduces the target rotation speed of the motor to the motor drive control unit when the current is equal to or higher than a current threshold value. When the current is smaller than the current threshold value and the temperature is equal to or less than a third temperature threshold value smaller than the first temperature threshold value, the control unit applies the modulation method to the motor drive control unit. 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,
A power supply circuit unit that is supplied with electric power from the power generation unit to supply electric power to the control unit, the drive power supply unit, and the temperature detection unit.
With more
The motor drive device according to any one of claims 1 to 3 , wherein the control unit controls the presence or absence of power supply 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.
A power supply circuit unit that is supplied with electric power from the power generation unit and supplies electric power to the control unit and the drive power supply unit.
With more
The motor drive device according to any one of claims 1 to 3 , wherein the control unit controls the presence or absence of power supply from the drive power supply unit. The motor drive device according to any one of claims 1 to 5 , further comprising a voltage detection unit that detects a voltage supplied from the power generation unit to the inverter output unit. An air conditioner including the motor driving device according to any one of claims 1 to 6 and the motor.

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