JPH07337081A - Inverter and air-conditioner - Google Patents

Abstract

PURPOSE:To obtain an inverter for controlling a motor in which the load torque is detected and an abnormality is detected based on the magnitude of the load torque and the fluctuation thereof. CONSTITUTION:At the time of commutation, conduction time of diode D1-D6 is detected thus detecting the commutation time. Since the fluctuation of commutation time is correlated with the fluctuation of load torque of a brushless motor 15, the conduction time is measured by comparing the terminal voltage Vu, Vv, Vw of winding 15u-15w with a reference voltage thereby detecting the conduction state of the diode D1-D6. Since the load torque increase when the commutation time is long and decreases when the commutation time is short, the magnitude of load torque and the fluctuation thereof are determined based on the length of the commutation time thus determining an abnormality.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a switching circuit for sequentially energizing each winding of a motor having a plurality of windings such as a brushless motor at commutation timing corresponding to a predetermined rotation position of a rotor. The present invention relates to an inverter device and an air conditioner controlled by the inverter device.

[0002]

2. Description of the Related Art In recent years, in air conditioners and refrigerators, a brushless motor, which is a kind of DC motor, has been adopted and can be driven by an inverter device in order to change the compressor capacity and save power consumption. It is being appreciated. In the case of a brushless motor, the rotor rotation position signal is usually required to determine the energized phase of the winding, but the motor is exposed to refrigerant such as an air conditioner or refrigerator compressor. Depending on the situation, it may be difficult to arrange the position detection sensor. Therefore, the inventors of the present application have developed a technique for obtaining a rotational position signal by detecting an induced voltage in a winding of a motor and electrically processing the induced voltage, which is disclosed in Japanese Patent Application No. 62-1626.
Filed as No. 54.

A case where the invention of the application is implemented by a pulse width modulation (hereinafter, simply referred to as PWM) system will be described below as an example of a conventional technique with reference to FIGS. In the inverter device shown in FIG. 20, the DC power supply circuit 2 connected to the AC power supply 1 includes a full-wave rectifier circuit 3, a reactor 4a, and a smoothing capacitor 4b.
And a switching element such as switching transistors 7 to 1 as a switching circuit between the positive side DC power supply line 5 and the negative side DC power supply line 6 of the DC power supply circuit 2.
The three-phase bridge circuit 13 consisting of two is connected, and the terminals of the windings 15u, 15v, 15w of the brushless motor 15 are connected to the output terminals 14u, 14v, 14w thereof.

In the three-phase bridge circuit 13, the three transistors 7, 9, 11 connected between the positive side DC power supply line 5 and the output terminals 14u, 14v, 14w correspond to the positive side switching elements, The three transistors 8, 10, 12 connected between the negative side DC power supply line 6 and the output terminals 14u, 14v, 14w correspond to negative side switching elements. When the transistors 7 to 12 are on / off controlled in a predetermined order, the brushless motor 15 has windings 15u to 15w of 120 degrees (electrical angle, the same applies hereinafter).
It is rotationally driven by successively energizing with a phase difference of. In this case, one transistor is 120
The duty is controlled by the PWM signal P1 shown in FIG. 21 during the ON / OFF cycle of 1 degree on and 240 degrees off, and therefore the terminal voltages Vu, Vv, Vw of the windings 15u to 15w of the brushless motor 15 are controlled. Has the waveform shown in FIG.

FIG. 22 shows the waveforms of the terminal voltage Vu and the current Iu of the winding 15u when the PWM control is not performed. In this waveform, a sloped portion extending over a section of about 60 degrees (period Ta) is an induced voltage of the winding 15u, and elongated positive and negative pulses are diodes D1 to D6 connected in parallel with the respective transistors 7 to 12 of the three-phase bridge circuit 13. Is a pulse voltage, and V0 is a reference voltage formed by the resistance voltage dividing circuit 16 connected between the DC power supply lines 5 and 6. Here, the reference voltage V0 is set to one half of the voltage of the DC power supply circuit 2 of the three-phase bridge circuit 13. From FIG. 22, the commutation timing is about 30 from the time when the induced voltage crosses the reference voltage V0 (hereinafter simply referred to as the zero crossing time).
It is understood that it is late.

The terminal voltages Vu, Vv, Vw are compared with the reference voltage V0 by the comparators 18 to 20 provided in the position signal circuit 17 as position detecting means, whereby the position information of the rotor of the brushless motor 15 is obtained. 1 of the terminal voltages Vu to Vw as shown in FIG.
Fundamental wave signals Vu ', Vv', Vw 'for 80-degree section recognition
Is converted to. Further, these fundamental wave signals Vu ′, Vv ′,
Vw 'is applied to the waveform synthesizing circuit 21 as the energizing signal forming means, and by comparison with the PWM signal P1, it consists of continuous square waves with a time width of 180 degrees and a phase difference of 120 degrees from each other. Recognition waveform signals Ua, V having
a, Wa. This recognition waveform signal Ua, Va,
The starting point (starting point) and ending point (falling point) of Wa coincide with the zero-cross point.

Further, in the waveform synthesizing circuit 21, of the first and second timer functions held therein, the first
The three recognition waveform signals Ua,
Six first phase division patterns X1 to X6 each having a time width Tb of 60 degrees are formed from Va and Wa, and further the first phase division patterns X1 to X6 are formed by the second timer function.
Six second phase division patterns Y1 to Y6 each having a time width of 30 degrees from the end point of X6 are formed. Then, the waveform synthesizing circuit 21 finally conducts the energization signal U shown in FIG. 21 from the second phase section Y1 to Y6 signals as described above.
p, Un, Vp, Vn, Wp, Wn are combined.

Here, energization signals Up, Un, Vp, V
The starting points of n, Wp, and Wn are the second phase division pattern Y.
Since it coincides with the end points of 1 to Y6, it is a point delayed by 30 degrees from the zero cross point.
The phase pattern of p, Un, Vp, Vn, Wp, Wn is
This corresponds to the commutation timing pattern required for the transistors 7 to 12 of the three-phase bridge circuit 13.

On the other hand, the speed judgment circuit 22 as speed detection means judges the speed deviation from the energization signal Wn and the speed command signal Sc given as the rotation speed detection signal of the brushless motor 15 from the waveform synthesizing circuit 21, and the speed deviation is determined. The duty signal Sd corresponding to the speed deviation is output and given to the pulse width modulation circuit 23. This pulse width modulation circuit 23 has P
The duty of the WM signal P1 is controlled according to the magnitude of the duty signal Sd. The PWM signal P1 whose duty is controlled in this way is combined with the energizing signals Up, Vp, Wp by the respective gate parts 25, 27, 29 of the gate circuit 24 which constitutes the driving means, and, for example, is logically ANDed into three phases. Positive side transistors 7, 9 of the bridge circuit 13,
The base control signal 11 is supplied to the base 11 to be on / off controlled in the on / off mode of the PWM signal P1. Further, only the energization signals Un, Vn, Wn are applied to the gates 26,
It is supplied via 28 and 30, and ON / OFF control without PWM mode is performed. As a result, the transistors 7 to
12 is controlled by the energization signals Up to Wn in the pattern shown in FIG.
5 continues to drive, and its speed is controlled by the duty control by the PWM signal P1 shown in FIG.

Here, the ON mode of the PWM signal P1 is one of the high level and the low level of the pulse signal.
A mode in which the transistor is turned on (set to high level in FIG. 21) is referred to, and an off mode is a mode in which the transistor is turned off (set to the same low level).

[0011]

In the air conditioner, the causes of the failure are as follows: refrigerant leakage such as refrigerant leakage and four-way valve failure; defective blower for indoor and outdoor heat exchangers; defective compressor; Various failures are possible.
It is difficult for the user to find these failures, and they are usually operated as they are, consuming wasteful power and inducing failures in other parts. Further, even if the user notices an abnormality and calls the service person, it takes time for the service person to find the abnormal portion.

On the other hand, as a method for judging the abnormality of the air conditioner, it is possible to judge the abnormality from the relation between the operation progress and the room temperature, but this is low in terms of finding the abnormal portion. . In the air conditioner, when an abnormality occurs, the load torque of the brushless motor deviates from the normal range, and in the brushless motor, there is a certain relationship between the current and the load torque. It is possible to provide a current detection circuit and calculate a load torque based on the detected current to determine an abnormality. However, this requires a current detection circuit, resulting in high cost.

The present invention has been made in view of the above circumstances. An object of the present invention is to obtain load torque information corresponding to the rotational position of a motor, and determine an abnormality depending on the magnitude of the load torque and the magnitude of the fluctuation of the load torque. By making a determination, when an abnormality occurs, this can be detected early, and load torque information can be obtained without providing a current detection circuit, and an abnormal location can be accurately determined. To provide air conditioner.

[0014]

In order to achieve the above object, the inverter device of the present invention is a switching device having a plurality of switching elements having diodes in parallel for sequentially energizing windings of a plurality of phases of a motor. Circuit,
Position detecting means for obtaining position information of the rotor of the motor, energization signal forming means for obtaining energization signal corresponding to a predetermined commutation timing based on the position information, and driving the switching element based on the energization signal Drive means for, and during the commutation of the switching element, to detect the energization time of the diode due to the release of the stored energy of the winding, the commutation time detection means for the detection time as the commutation time of the switching element, Torque detection means for obtaining load torque information corresponding to the rotational position of the rotor based on the position information and commutation time, and abnormality determination means for determining abnormality based on the load torque information are provided. .

In this case, the position detecting means may be configured so as to compare the terminal voltage of the winding with the reference voltage and obtain position information based on the comparison result. Can be detected by comparing the terminal voltage of the winding with a reference voltage. Further, it is preferable to provide a means for stopping energization of the motor when the abnormality determining means determines that the abnormality has occurred.

The air conditioner of the present invention comprises a heat pump in which a compressor, an outdoor heat exchanger, a pressure reducing device, and an indoor heat exchanger are connected by a refrigerant passage, and the motor of the compressor is controlled by the above inverter device. It is a feature.

In this case, the abnormality judging means judges the magnitude of the load torque and the magnitude of the fluctuation of the load torque from the load torque information, and when the load torque is small and the fluctuation of the load torque is small, it is judged that the refrigerant passage is abnormal. However, when the load torque is small and the fluctuation of the load torque is small, it can be judged that the refrigerant passage is abnormal, and when the load torque is large and the fluctuation of the load torque is large, it can be judged that the compressor is abnormal. Further, the air conditioner of the present invention can be provided with means for informing the abnormality determination result of the abnormality determination means.

[0018]

When the rotor rotates at a constant speed and the load torque of the motor increases, the winding current increases and the energy stored in the winding increases. Therefore, when commutating the switching element, the time required to release the energy accumulated in the winding becomes long. At this time, the current flowing due to the release of the accumulated energy in the winding returns to the winding through the diode, so that the energization time of the diode and the load torque have a constant relationship.

Therefore, according to the inverter device of the present invention which employs the above means, the energization time of the diode at the time of commutation, that is, the commutation time is detected, and the rotational position of the rotor is detected from this commutation time and the position information of the rotor. Since the load torque information according to is obtained, when an abnormality occurs, the abnormality can be detected early based on the load torque information.

In this case, by comparing the terminal voltage of the winding with the reference voltage and obtaining the position information of the rotor based on the comparison result, it is not necessary to provide a position detection sensor. Further, when the diode energization state is detected by comparing the terminal voltage of the winding with the reference voltage, the diode energization state can be detected without providing a current detection circuit. Furthermore, when the abnormality determining means determines that there is an abnormality, the power supply to the motor is stopped so that
The motor will not continue to operate in an abnormal state.

Therefore, in the air conditioner of the present invention in which the compressor motor is controlled by the above-described inverter device, when an abnormality occurs, it can be detected early and the cooling / heating operation can be stopped. Also, from the magnitude of the load torque and the magnitude of the fluctuation of the load torque,
If it is determined that the refrigerant passage, the blower of the indoor / outdoor heat exchanger are defective, or the compressor is defective, it is easy to find the abnormal portion.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an air conditioner will be described below with reference to FIGS. 1 to 16. The same parts as those in FIG. 20 are designated by the same reference numerals and only different parts will be described. . FIG. 3 shows an air conditioner that employs a brushless motor as a compressor motor. In the figure, the compressor 32 of the heat pump 31 includes a compression unit 33 and a brushless motor 15.
Are housed in the same iron airtight container 34, and the rotor shaft of the brushless motor 15 is connected to the compression portion 33. The compressor 32, the four-way valve 35, the indoor heat exchanger 36, the pressure reducing device 37, and the outdoor heat exchanger 38 are connected by a pipe serving as a refrigerant passage so as to form a closed loop. In this embodiment, the rotor of the brushless motor 15 has a four-pole field magnet.

At the time of heating, the four-way valve 35 is in the state shown by the solid line, and the high-temperature refrigerant compressed by the compression section 33 of the compressor 32 is supplied from the four-way valve 35 to the indoor heat exchanger 36 and condensed, and thereafter, It is decompressed by the decompression device 37, becomes a low temperature, flows to the outdoor heat exchanger 38, evaporates there, and returns to the compressor 32. At the time of cooling, the four-way valve 35 is switched to the state shown by the broken line. Therefore, the high-temperature refrigerant compressed by the compression unit 33 of the compressor 32 is
Is supplied to the outdoor heat exchanger 38 to condense and then
It is decompressed by the decompression device 37, becomes a low temperature, flows into the indoor heat exchanger 36, evaporates there, and returns to the compressor 32. Air is blown from the air blowers 39 and 40 to the heat exchangers 36 and 38 on the indoor side and the outdoor side, respectively, and the heat blows from the heat exchangers 39 and 40 to the indoor air and the outdoor air, respectively. Is configured so that the heat exchange can be efficiently performed.

Here, the compressor 32, the four-way valve 35,
Pressure reducing device 37, outdoor heat exchanger 38, and air blower 40
Is configured as an outdoor unit 41, and the indoor heat exchanger 36 and the air blower 39 are configured as an indoor unit 42. The indoor unit 42 has a microcomputer 43 for overall control of the air conditioner, an operation unit 44 for selecting operations such as cooling, heating, dehumidification, etc., temperature setting, etc., selected operations, set temperatures, etc. A display unit 45 for displaying is displayed. The outdoor unit 42 and the indoor unit 41 are connected by a communication line 46.

The brushless motor 15 of such an air conditioner is controlled by the inverter device 47 shown in FIG. In addition, this inverter device 47 is used for the outdoor unit 41.
It is provided in. The microcomputer 48 of the inverter device functions as energizing means forming means, has an energizing signal forming function equivalent to that of the waveform synthesizing circuit 21 of the conventional inverter device shown in FIG. 20, and also functions as selection signal forming means. As shown in FIG. 2, the energization signals Up, Un,
A selection signal Sp that changes at the time of switching between Vp, Vn, Wp, and Wn, that is, the level relationship between high (H) and low (L) is inverted is formed.

The selection signal Sp is the positive side transistors 7, 9,
When commutation occurs between 11 and 11, the negative side transistor in the ON period at that time is controlled to be turned on and off according to the ON / OFF mode of the PWM signal P1, and commutation occurs between the negative side transistors 8, 10 and 12. In this case, the positive side transistor in the ON period at that time is controlled to be turned on / off in accordance with the ON / OFF mode of the PWM signal P1. When commutation occurs between the positive side transistors 7, 9 and 11, the low level is changed from the low level. When it is inverted to the high level and commutation occurs between the negative side transistors 8, 10 and 12, it is inverted from the high level to the low level.

As shown in FIG. 1, the selection signal Sp is given to the OR circuit 50 of the gate circuit 49 as a driving means, inverted by the NOT circuit 51 and given to the OR circuit 52. The signals are applied to the respective gate sections 25 to 30 while being ORed with the PWM signal P1 by the circuits 50 and 52. In addition, energization signals Up, Un,
Vp, Vn, Wp, and Wn are given to the respective gate parts 25 to 30. Here, each of the transistors 7 of the three-phase bridge circuit 13 is logically ANDed with the output signals of the OR circuits 50 and 52.
It is given as a base control signal to the bases of ~ 12.

Here, when the selection signal Sp is at the low level, the OR circuit 50 corresponding to the positive side transistors 7, 9 and 11 repeatedly outputs both the high level signal and the low level signal in the same mode as the PWM signal P1. Since the OR circuit 52 corresponding to the side transistors 8, 10 and 12 always outputs a high level signal, the positive side transistors 7, 9 and 11 are substantially the PWM signal P1 and the energization signal U.
On / off control is performed by p, Vp, Wp, and the negative side transistors 8, 10, 12 are on / off controlled by energization signals Un, Vn, Wn.

When the selection signal Sp is at the high level, the OR circuits 50 and 52 are in the output state opposite to the above, so that the positive side transistors 7, 9 and 11 are substantially driven by the energization signals Up, Vp and Wp. On / off control is performed, and the negative side transistors 8, 10 and 12 are on / off controlled by the PWM signal P1 and the energization signals Un, Vn and Wn. In this way, the positive side transistors 7, 9, 11 and the negative side transistors 8, 10, 12 are alternately on / off controlled by the on / off mode of the PWM signal P1, as a result, the terminal voltages Vu, Vv, Vw, and the fundamental wave signal Vu.
′, Vv ′, and Vw ′ have the waveforms shown in FIG.

Further, the microcomputer 48 detects the commutation time of the switching transistors 7 to 12 during commutation, and from the commutation time, the brushless motor 15 is detected.
Is configured to obtain the load torque information of In this embodiment, the commutation time is detected by measuring the energization time of the diodes D1 to D6 connected in parallel with the switching transistors 7 to 12. In this way, the commutation time can be detected by measuring the energization time of the diodes D1 to D6, and the change in the load torque can be detected from the change in the commutation time for the following reason.

That is, when the brushless motor 15 is rotating at a constant speed and the load torque fluctuates to change the rotation speed of the rotor, the current flowing through the windings 15u, 15v, 15w changes and the stored energy is changed. Change.
Therefore, the time (commutation time) required to release the energy accumulated in the windings 15u, 15v, and 15w changes during the commutation of the switching transistors 7 to 12. At this time, the current flowing due to the release of the accumulated energy in the windings 15u, 15v, 15w is the diodes D1 to D6.
Since it is returned to the winding through the winding, the commutation time of the switching transistors 7 to 12 can be detected by detecting the energization time of the diodes D1 to D6, and the commutation time and the load torque are constant. Therefore, the load torque fluctuation can be detected by the change in commutation time.

By the way, the relationship between the rotation speed of the brushless motor 15, the voltage applied to the windings 15u, 15v, 15w, the energization time (commutation time) of the diodes D1 to D6, and the load torque is shown in FIGS. The results obtained are shown below. The applied voltage depends on the output voltage of the DC power supply circuit 2 and PW.
It is the product of the M signal P1 and the duty. It is understood from FIGS. 4 and 5 that the commutation time and the load torque have a constant relationship. Also, under the condition that the rotation speed is constant,
It is understood that the magnitude of the load torque can be determined by detecting the commutation time.

In this embodiment, it is recognized that the diodes D1 to D6 are energized by the windings 15u, 15v, 15w.
The terminal voltages Vu, Vv, and Vw are compared with the reference voltage V0. Here, the diodes D1 to D
Winding 15u, 15v, 15w that 6 is energized
The reason why it can be recognized by the fundamental wave signals Vu ′, Vv ′, Vw ′, which are the comparison results of the terminal voltages Vu, Vv, Vw and the reference voltage V0, will be described.

The levels of the fundamental wave signals Vu ', Vv' and Vw 'when the diodes D1 to D6 are energized differ depending on the commutated transistors. 11 to 13 show a case where commutation is performed between two transistors of the positive side transistors 7, 9 and 11 when any of the negative side transistors 8, 10 and 12 is in the ON period (see FIG. 2). 2) of the phase division patterns Y1, Y3, Y5), the commutation at the end of the second phase division pattern Y3, that is, when the negative side transistor 12 is in the ON period, 12 shows an example in which the ON period ends (the OFF period starts) and the ON period of the positive side transistor 9 starts, and FIG.
Shows during commutation, and FIG. 13 shows after commutation.

Before commutation in FIG. 11 (transistor 7 is PWM
(ON / OFF control is performed by the signal P1 and the transistor 12 remains ON). When the transistor 7 is turned on by the PWM signal P1, the positive side DC power supply line 5 → transistor 7 → winding 15u → winding 15w as shown by an arrow A1. → Current flows through the path of the transistor 12 → the negative side DC power supply line 6. When the transistor 7 is turned off by the PWM signal P1, as shown by an arrow A2, the current due to the discharge of the stored energy in the windings 15u and 15w is changed from the winding 15u to the winding 15w.
→ Transistor 12 → Negative side DC power supply line 6 → Diode D
2 → It flows in the route of winding 15u.

When the transistor 7 enters the off period and the transistor 9 enters the on period to start commutation (the transistor 12 is on / off controlled by the PWM signal P1 and the transistor 9 remains in the on state), the PWM
When the transistor 12 is turned on by the signal P1, the DC power supply circuit 2 applies a voltage to the positive DC power supply line 5 → transistor 9 → winding 15v → winding 15w → transistor as shown by an arrow A3 in FIG. 12-> A new current starts to flow in the path of the negative side DC power supply line 6, and the current due to the release of the stored energy of the winding 15u that was in the energization period immediately before the start of this commutation is the path shown by the arrow A2 in FIG. It flows in the same route as.

When the transistor 12 is turned off by the PWM signal P1, as shown by an arrow A4 in FIG. 12 (b), the current due to the release of the accumulated energy in the windings 15v and 15w is winding 15v → winding 15w → diode D5 → The current flows through the path of the positive side DC power supply line 5 → transistor 9 → winding 15v, and as shown by the arrow A5, the current due to the release of accumulated energy in the winding 15u is winding 15u → winding 15w → diode D5 → the positive side. DC power line 5 → smoothing capacitor 4b
→ Diode D2 → It flows in the route of winding 15u. Then, the current flowing through the path indicated by arrow A5 gradually decreases due to the release of the accumulated energy of the winding 15u, and the commutation ends when the current becomes zero.

After the commutation, when the transistor 12 is turned on by the PWM signal P1 as shown in FIG.
In (a), the current flows through the same route as shown by the arrow A3,
When the transistor 12 is turned off by the PWM signal P1,
A current flows through the same path as the path indicated by arrow A4 in FIG.

The PWM signal P at such commutation timing
14, the terminal voltage Vu and the fundamental wave signal Vu 'are shown in FIG. In FIG. 14, ts indicates the start of commutation and te indicates the end of commutation. In FIG. 14A, the commutation ends when the PWM signal P1 is in the high level state (transistor 12 is on). In case (b), the commutation ends when the PWM signal P1 is in the low level state (transistor 12 is off). During the commutation from ts to te, the terminal voltage Vu of the winding 15u causes the diode D2 to conduct when the diode 12 is on or off (FIG. 1).
(See arrows A2 and A5 in 2).
It is maintained at the potential of. Then, when the commutation ends when the PWM signal P1 is in the high level state because the transistor 9 remains on, an induced voltage appears in the terminal voltage Vu, and when the PWM signal P1 is in the low level state, the commutation is performed. When is finished, the voltage of the positive side DC power supply line 5 appears in the terminal voltage Vu.

However, since the time required for commutation is short and the commutation ends while the induced voltage exceeds the reference voltage V0, the fundamental wave signal Vu 'which is the result of comparison between the terminal voltage Vu and the reference voltage V0. Changes to a high level when the commutation ends, regardless of the level of the PWM signal P1. Therefore,
Commutation start time ts (switching of energization signals Up and Vp)
From this, it can be recognized that the period when the fundamental wave signal Vu ′ is at the low level is the period during commutation, and the commutation time can be detected by measuring the time during that period. Although the commutation at the end of the second phase division pattern Y3 has been described above, the second phase division patterns Y1 and Y5 are described.
In the same way, it is possible to recognize that the commutation is in progress at the end point of the time period from the start time of the commutation to the time period during which the fundamental wave signals Vw ′ and Vv ′ are at the low level as the commutation period. The flow time can be detected.

On the other hand, FIGS. 15 and 16 show a case where commutation is performed between two transistors of the negative side transistors 8, 10, 12 when any of the positive side transistors 7, 9, 11 is in the ON period. As an example of (the second phase division pattern Y2, Y4, Y6 in FIG. 2), commutation at the end of the second phase division pattern Y4, that is, when the positive side transistor 9 is in the ON period, the negative side transistor 12
The on-state of FIG. 13 ends (the off-period starts) and the on-state of the negative-side transistor 8 starts. The state before commutation is the same as in FIG. It is omitted and FIG. 15 shows a state during commutation and FIG. 16 shows a state after commutation.

Before commutation, as shown in FIG. 13, when the transistor 12 is turned on by the PWM signal P1, current flows through the path of arrow A3, and when the transistor 12 is turned off by the PWM signal P1, current is passed through the path of arrow A4. Flowing.

When the commutation is started by the transistor 12 entering the off period and the transistor 8 entering the on period (the transistor 9 is on / off controlled by the PWM signal P1 and the transistor 8 remains in the on state), the PWM
When the transistor 9 is turned on by the signal P1, the DC power supply circuit 2 applies a voltage to the positive DC power supply line 5 → transistor 9 → winding 1 as shown by an arrow A6 in FIG.
5v → winding 15u → transistor 8 → negative side DC power supply line 6
While a new current starts to flow in the path of, the current due to the release of the stored energy of the winding 15w flows in the same path as the path indicated by the arrow A4 in FIG.

When the transistor 9 is turned off by the PWM signal P1, as shown by an arrow A7 in FIG. 15 (b), the current due to the release of the stored energy in the windings 15v and 15u is a winding 15v → a winding 15u → a transistor 8 → Negative side DC power supply line 6 → diode D4 → winding 15v, and as shown by an arrow A8, current due to release of stored energy in winding 15w is winding 15w → diode D5 → positive side DC power supply line 5 → smoothing capacitor 4b → negative side DC power supply line 6 → diode D4 → winding 15v → winding 15w. Then, the current flowing through the path indicated by the arrow A8 gradually decreases due to the release of the accumulated energy of the winding 15w, and the commutation ends when the current becomes zero.
After the commutation, as shown in FIG. 16, when the transistor 9 is turned on by the PWM signal P1, current flows through the same path as the path indicated by the arrow A6 in FIG. 15A, and when the transistor 9 is turned off by the PWM signal P1, The arrow A in FIG.
The current flows through the same route as shown by 7.

During such commutation, during the commutation, the terminal voltage Vw of the winding 15w is such that the diode D5 is conducting regardless of whether the transistor 9 is on or off (see arrows A4 and A8 in FIG. 15). Therefore, the potential of the positive side DC power supply line 5 is maintained as it is regardless of the on / off state of the transistor 9. Then, when the commutation ends when the PWM signal P1 is in the high level state by the transistor 8 remaining on, an induced voltage appears in the terminal voltage Vw, and when the PWM signal P1 is in the low level state, the commutation is performed. When is finished, the voltage of the negative side DC power supply line 6 appears in the terminal voltage Vw.

However, since the time required for commutation is short and the commutation ends while the induced voltage is lower than the reference voltage V0, the fundamental wave signal Vw 'which is the result of comparison between the terminal voltage Vw and the reference voltage V0. Keeps high level during commutation and changes to low level when commutation ends. Therefore, it is possible to recognize that the period during which the fundamental wave signal Vw ′ is at the high level from the start of commutation (at the time of switching the energization signals Up and Vp) is the period during commutation, and by measuring the time during that period, The commutation time can be detected. Although the commutation at the end of the second phase division pattern Y4 has been described above, it is recognized that the commutation is started at the end of the second phase division pattern Y2 and Y6. The period during which the fundamental wave signals Vv ′ and Vu ′ are at the high level from the time point can be recognized as the commutation period, and the commutation time can be detected by measuring the time during the period.

From the above, the fundamental wave signal Vu during commutation at the end of the second phase division patterns Y1 to Y6 is obtained.
The high (H) and low (L) levels of ', Vv', and Vw 'are as shown in Table 1 below.

[0048]

[Table 1]

Then, each second phase division pattern Y1 ...
At the end of commutation at Y6, each fundamental wave signal Vu
Since ', Vv', and Vw 'are inverted from the states shown in Table 1, the respective fundamental wave signals Vu', Vv ', and Vw' at the time when the commutation is finished in each of the first phase division patterns X1 to X6. Yes,
Table 2 below shows the row level relationships.

[0050]

[Table 2]

Now, the microcomputer 48 uses the terminal voltages Vu, Vv, Vw including the induced voltages of the windings 15u, 15v, 15w of the brushless motor 15 and the reference voltage V0.
The time point at which and cross (zero cross time point) is detected, and the time point delayed by 30 degrees from that time point is the commutation timing. When detecting the zero-cross time point, the microcomputer 48 prevents the time point at which the pulse voltage crosses the reference voltage V0 due to the current flowing through the diodes D1 to D6 during commutation from being erroneously recognized as the zero-cross time point.
Functions as a commutation end detection means, and recognizes from the time when the commutation is detected based on the level relationship of each signal in Table 2 to the start time of each of the first phase division patterns X1 to X6 as the specific period Ti. Then, within this specific period Ti, the fundamental wave signals Vu ′ and Vv from the comparators 18 to 20 are obtained.
Input ′ and Vw ′ to detect the zero crossing point.

The zero crossing point recognition by the microcomputer 48 is performed by comparing the fundamental wave signals Vu ', Vv', Vw 'and the PWM signal P1 with the comparison data for position detection. As shown in Table 3 below, the comparison data for position detection includes the fundamental wave signals Vu ', Vv', Vw 'and the PWM signal P1 for each of the first phase division patterns X1 to X6.
Are configured as high (H) and low (L) level modes.

[0053]

[Table 3]

The level relations of Table 3 are stored in the memory of the microcomputer 48 in association with the first phase division patterns X1 to X6 together with the level relations of Table 2 above. Further, the microcomputer 48 also functions as a torque detecting unit that obtains load torque information from the commutation time measured as described above. In this embodiment, the microcomputer 48 uses the brushless motor 15
Is controlled to a constant rotation speed, for example, 10 rps, and torque information associated with the rotation position of the rotor is obtained.

Specifically, since the compressor 32 exerts a compression action once per one rotation of the brushless motor 15, the load torque of the brushless motor 15 is periodically set with one rotation as one cycle as shown in FIG. fluctuate. On the other hand, since the brushless motor 15 of this embodiment is a three-phase, four-pole motor, one revolution of the brushless motor 15 corresponds to the first phase division pattern X.
This corresponds to two cycles of 1 to X6. Therefore, one rotation of the brushless motor 15 is performed for each of the first phase division patterns X1 to X.
It is configured to be divided into 12 zones corresponding to 6 and to store the commutation time in each zone during commutation as it is as load torque information in a memory (not shown).

In this case, the microcomputer 48 tabulates the commutation times ta to td of the past four rotations for each of the 12 sections, that is, the first phase division patterns X1 to X6 for two cycles, and stores them in a memory. Then, the average time T1 to T12 of the commutation times ta to td of four rotations and the total average commutation time T1 to T12 which is the average of the average commutation times T1 to T12 for each of the first phase division patterns X1 to X6 for two cycles. The flow time Tave is calculated and also stored in the commutation time table. The following Table 4 conceptually shows this commutation time table.
become that way.

[0057]

[Table 4]

The microcomputer 48 has a table (not shown) in a memory (not shown) showing the relationship between the commutation time and the load torque for the rotation speed of 10 rps, which is calculated from the above-mentioned total average commutation time Tave. The average load torque magnitude Tq of each of the first phase division pattern sections X1 to X6 for two cycles is obtained, and the average commutation time T1 to
The load torque of the maximum value and the minimum value of T12 is obtained, the difference is calculated, and this difference is set as the magnitude Tqx of the fluctuation of the load torque.

Further, the microcomputer 48 functions as an abnormality determining means for determining the presence or absence of abnormality of the air conditioner based on the magnitude Tq of the load torque and the magnitude Tqx of the variation of the load torque obtained as described above. . That is, in FIG. 6, the rotation speed of the brushless motor 15 is 10 rp.
The magnitude of the load torque and the magnitude of the variation of the load torque at s are shown. The range surrounded by solid lines A to C in the figure is normal, the region a outside the solid line A is refrigerant leak, and the four-way valve 35 is shown. If an abnormality due to the refrigerant passage occurs, such as
The area b outside the solid line B indicates the solid line when abnormalities in the air blowers 39 and 40 of the indoor and outdoor heat exchangers 36 and 38 or abnormalities in the air blowers 39 and 40 due to the presence of obstacles occur. A region c outside C indicates a case where an abnormality relating to the compressor 32 such as "galling" of the cylinder of the compressor 32 or demagnetization of the brushless motor 15 occurs. Note that FIG. 6 shows the results obtained by the experiment.

Then, the magnitude of the load torque shown in FIG.
The relationship between the magnitude of the fluctuation and the normal range, the abnormal range, and the relationship between the above-mentioned abnormal contents are tabulated and stored in a memory (not shown).
Is configured to compare the above Tq and Tqx with this abnormality determination data table to determine the presence or absence of an abnormality and the cause of the abnormality.

Next, the operation of the above configuration will be described with reference to the flow charts shown in FIGS. FIG. 7 is a flowchart showing the rotation speed control in the normal control of the brushless motor 15, which is executed once per one rotation of the brushless motor 15 within a range not hindering the execution of the flowchart shown in FIG. In this rotation speed control, the microcomputer 43 of the indoor unit 42 determines the rotation speed of the brushless motor 15 on the basis of the temperature set by the operation unit 44 and the temperatures detected by the temperature sensors inside and outside the room (not shown). The outdoor unit 41 via the communication line 46 as the speed command signal Sc
Send to. The microcomputer 48 first reads the speed command signal Sc sent through the communication line 46 in step SA to obtain the command rotation speed Nc, and then in step SB
The rotor speed N is detected by. The rotation speed N is determined by integrating the first transfer division patterns X1 to X6, which will be described later, for the past 12 times.

Next, the microcomputer 48 calculates the duty D by the following equation (1) in step SC,
The signal Sd having the duty D is given to the pulse width modulation circuit 23. Then, the pulse width modulation circuit 23 controls the duty of the PWM signal P1 to the magnitude of D from the signal Sd, and thereby the brushless motor 15 is controlled so as to have the rotation speed determined by the microcomputer 43 of the indoor unit 42. It D = D + Kp (Nc-N) (1) However, Kp is a constant.

On the other hand, FIG. 8 shows a flowchart for determining commutation timing and detecting commutation time. In the flowchart shown in FIG. 8, assuming that the specific period Ti of the first phase division pattern X1 to X6 of a certain number of divisions is now entered, the microcomputer 48 proceeds to step S1. The fundamental wave signals Vu ', Vv', Vw 'and the PWM signal P1 which are loaded with the position detection comparison data (see Table 3) of the first phase division pattern of the number of zones currently in progress and are input in the specific period Ti The high of
Step S2 for comparing the row state with the comparison data is executed. When the induced voltage crosses the reference voltage V0, the high / low level states of the fundamental wave signals Vu ', Vv', Vw 'and the PWM signal P1 match the comparison data ("YES" in step S2). , The first of the following wards
Is started, and the required time Tb (measurement time of the first timer function) of the completed first phase division pattern is loaded and the required time of the started first phase division pattern is measured. In order to do so, the first timer function is restarted (step S3).

As is clear from the above, the first timer function (first timer means) starts time counting with the start of the first phase division pattern of each division number, and the first count function is started.
The end of the time division is ended with the end of the phase division pattern (start of the first phase division pattern of the next division number). Therefore, the first timer function counts the time (corresponding to 60 degrees) from the zero cross time point to the next zero cross time point.

Then, in the next step S4, the time of the second phase division pattern (time Y1 to Y6 to be measured by the second timer function) is calculated by the equation of Tb / 2 (calculation means), Start the timer function (second timer means). As a result, the commutation timing is set to a time point delayed by 30 degrees from the zero cross time point.

Next, the microcomputer 48 increments the number of divisions of the first phase division pattern stored in the memory (not shown) (step S5), and sets it to the number of divisions of the newly started first phase division pattern. At the same time, the division number of the commutation time table stored in the memory (not shown) is incremented and set to the division number corresponding to the newly started division number of the first phase division pattern (step S6).

In order to explain the above concretely by way of example, assuming that the specific period Ti of the first phase division pattern having the number X1 of zones is entered, the microcomputer 48 sets the number X1 of zones shown in Table 3 as follows. Comparison data for position detection Vu ′ = H, Vv
'= L, Vw' = L, P1 = H are loaded (step S
1), fundamental wave signals Vu ', Vv', Vw 'and PWM
Comparison with the high / low state of the signal P1 (step S
2). When the two match, the next section number X2 starts, and the microcomputer 48 finishes the section number X1.
Number of wards started with loading the required time Tb of X2
The first timer function is started to measure the required time (step S3). Next, the microcomputer 48 calculates the time of the second phase division pattern Y2 and starts the second timer function (step S4), and sets the section number X1 stored in the memory to the newly started section number X2. At the same time (step S5), the number of divisions in the commutation time table is set to "2" (step S6).

Now, the second timer function is (Tb / 2)
When the counting of is finished (“YE
S ”), and the commutation timing is set at this end point, so the energization signal is switched in the next step S8. Next, the microcomputer 48 starts the third timer function (third timer means) to measure the commutation time (step S9), and at the same time, detects the current first time to detect the end point of the commutation. The comparison data for detecting the commutation end (see Table 2) in the phase division pattern of (1) is loaded (step S1).
0), the high / low level states of the fundamental wave signals Vu ′, Vv ′, Vw ′ are compared with the comparison data (step S1).
1).

When the commutation is completed, the fundamental wave signals Vu ', Vu
Since the high and low level states of v ', Vw' and the PWM signal P1 match the comparison data ("YES" in step S11), the microcomputer 48 detects the end of commutation at this point and the third timer The time measured by the function, that is, the commutation time tx (x is the number of zones of the current first phase division pattern) is loaded (step S12). Then, it is next determined whether or not a commutation time table creation command has been issued (step S13), and if a creation command has not been issued ("NO" in step S13), detection of the commutation end is detected. As a result, since it is recognized that the specific period Ti has been entered, the process returns to step S1 of loading the position detection data of the first phase division pattern of the current section incremented in step S5, and the above-described operation is repeated thereafter.

When a commutation time table creation command is issued ("YES" in step S13), the process proceeds to step S14 and the commutation time tx is incremented in step S6 of the commutation time table. Write in the section. Subsequently, it is determined whether or not the commutation time table is completed (step S15), and if not completed (“NO” in step S15), the process returns to step S1 and thereafter the operations from step S1 to step S15 are repeated. Then, when the commutation time table is completed, "YES" is determined in step S15, the commutation table completion flag is set in the next step S16, the process returns to step S1, and the operations of steps S1 to S16 are repeated thereafter. . The commutation time table is completed when four pieces of commutation time data are written in each section, and the average commutation time for each section is calculated and the total average commutation time is calculated and the commutation time is calculated. Written to the time table.

Whether or not the air conditioner is abnormal is determined at the start of operation. This abnormality determination will be described with reference to the flowchart shown in FIG. Microcomputer 48
When the power is turned on (started), the system always monitors whether or not the operation start command is input (step S
T1). Then, when the operation start operation is performed by the operation unit 44, the operation start command is given from the microcomputer 43 of the indoor unit 42, so that “YE” is given in step ST1.
S (there is an operation command) ", and the brushless motor 15 is started (step ST2).

At this time, the microcomputer 48 executes the operation according to the flowchart of FIG. 7 so as to control the rotation speed of the brushless motor 15 to a constant rotation speed of 10 rps, and gives the signal Sd to the pulse width modulation circuit 23 (step ST3). At the same time, the operation according to the flowchart of FIG. 8 is executed to control the brushless motor 15. When the rotation speed of the brushless motor 46 reaches 10 rps and is maintained at that rotation speed, the microcomputer 48 issues a commutation time table preparation command (step ST4) and waits for completion of the commutation time table (step ST5).

When the commutation time table is completed by repeatedly executing steps S1 to S15 of the flowchart shown in FIG. 6 and the completion flag is set ("YES" in step ST5), this commutation time table The load torque magnitude Tq and the load torque Tq
The magnitude of the fluctuation of x is obtained and stored in the memory as load torque data. Then, the magnitude Tq of the load torque and the magnitude Tqx of the variation thereof are compared with the abnormality determination data table (steps ST7 to ST9).

First, if Tq is small and Tqx is small and is in the abnormal area a in FIG. 6, "YES" is determined in the step ST7, and in the next step ST10, for example, energization signals Up, Un, V.
All of p, Vn, Wp, Wn and the selection signal Sp are set to the low level to stop the brushless motor 15, and the indoor unit 42 is sent via the communication line 46 in step ST11.
A notification signal of a defective refrigerant passage is given to. Small Tq, Tqx
Is large and is in the abnormal area b in FIG. 6, “Y” is determined in step ST8.
ES ", the brushless motor 15 is stopped in the next step ST12, and a notification signal of the defective blowers 39, 40 is given to the indoor unit 42 via the communication line 46 in step ST13. Further, if Tq is large and Tqx is large and is in the abnormal region c in FIG. 6, "YES" is determined in step ST9, the brushless motor 15 is stopped in the next step ST14, and the communication line 46 is transmitted in step ST15. A notification signal indicating that the compressor 32 is defective is given to the indoor unit 42.

The microcomputer 43 of the indoor unit 42 displays an abnormal display of the contents on the display device 45 in response to the notification signal given from the microcomputer 48. Here, as the display content of the display unit 45, when the display unit 45 is composed of, for example, three light-emitting elements, one of them is turned on to display the content of abnormality, and the display unit 45 is an LCD. If it is composed of, it is possible that the contents of the abnormality are displayed in characters.

When all of the steps ST7 to ST9 are "NO", it is determined that there is no abnormality, and the process shifts to the normal control of step ST16. FIG. 10 shows the operation in the case of determining the magnitude Tq of the load torque and the magnitude Tqx of the variation thereof from the commutation time described above. The commutation time is long at the rotational position where the load torque is large, The commutation time is short at the rotational position where the load torque is small. Then, the average of the load torques at each rotation position becomes the load torque Tq corresponding to the total average commutation time Tave, and the maximum value of the load torques at each rotation position is the load torque corresponding to the longest commutation time, and the minimum. The value is the load torque corresponding to the shortest commutation time, and the difference between them is the magnitude Tqx of the fluctuation of the load torque.

As described above, according to this embodiment, the commutation time tx at the time of commutation occurring in each of the first phase division patterns X1 to X6 is detected, and the load torque information obtained based on the commutation time is detected. According to this configuration, the magnitude of the load torque and the magnitude of the fluctuation of the load torque are determined to determine the abnormality. Therefore, the abnormality determination can be performed early and accurately.

In this embodiment, the commutation time tx is detected by measuring the energization time of the diodes D1 to D6, and the fact that the diodes D1 to D6 are in the energized state is determined by the windings 15u and 15v. , 15w terminal voltage V
Since the detection is performed by comparing u, Vv, Vw with the reference voltage V0, a circuit for detecting the energization state of the diodes D1 to D6 is not required, and the commutation time tx can be measured by a microcomputer program. You can
The configuration for measuring the commutation time becomes simple.

In addition, when it is determined that there is an abnormality, the brushless motor 15 is stopped, so that it is possible to solve the problem that the operation is continued as an abnormality and wastes electric power or induces another failure. You can Further, since the cause of abnormality is determined from the magnitude Tq of the load torque and the magnitude Tqx of its variation and the abnormality is notified by the display 45, the abnormal portion can be easily found and the time required for repair can be shortened.

By the way, as described above, the diodes D1 ...
The fact that D6 is energized means that the windings 15u, 15v, 1
In the case of detecting by comparing the terminal voltage Vu, Vv, Vw of 5w with the reference voltage V0, in this embodiment, when the commutation is performed between the transistors 7, 9, 11 on the positive side by the selection signal Sp, the voltage on the negative side is changed. PWM the transistors 8, 10 and 12
The on / off control is performed according to the on / off mode of the signal P1, and when the commutation is performed between the negative side transistors 8, 10 and 12, the positive side transistors 7, 9 and 11 are PWMed.
Since the ON / OFF control is performed according to the ON / OFF mode of the signal P1, the windings 15u and 15 are controlled by the PWM control.
Even if the voltage control of v and 15w is performed, the fundamental wave signal Vu ′,
The level changes of Vv 'and Vw' appear in synchronism with the actual end point of commutation, and as a result, the diodes D1 ...
It is possible to accurately detect the time point when the energization of D6 ends, and to accurately measure the commutation time Tx.

However, as in the conventional inverter device shown in FIG. 20, the positive side transistors 7, 9, 10 are always provided.
In the configuration in which ON / OFF is controlled by the PWM signal P1, commutation occurs between two of the positive side transistors 7, 9, 11 when any of the negative side transistors 8, 10, 12 is in the energization period. When performed (Fig. 20)
End points of the second phase division patterns Y1, Y3, Y5) of
The level changes of the fundamental wave signals Vu ′, Vv ′, Vw ′ do not coincide with the actual end point of commutation, and the end point of commutation may not be detected, and thus the commutation time may not be accurately measured.

This will be described with reference to FIGS. That is, FIGS. 17 and 18 show a case where commutation is performed between two of the positive side transistors 7, 9, 11 when any of the negative side transistors 8, 10, 12 is in the energization period (FIG. 20). Of the second phase division pattern Y1, Y3, Y5), the commutation at the end point of the second phase division pattern Y3 (the same as in the case of FIGS. 11 to 13) is taken as an example. The current path after commutation is shown. The current path before commutation is the same as in FIG.

During commutation, when the transistor 9 is turned on by the PWM signal P1, as shown by an arrow B1 in FIG. 17A, the positive side DC power supply line 5 → transistor 9 → winding 15v →
A new current starts to flow in the path of the winding 15w → transistor 12 → negative side DC power supply line 6, and the current due to the release of stored energy in the winding 15u is as shown by an arrow B2.
It flows in the route of winding 15u → winding 15w → transistor 12 → negative side DC power supply line 6 → diode D2 → winding 15u (same as FIG. 12 (a)). When the transistor 12 is turned off by the PWM signal P1, as shown by the arrow B3 in (b), the current due to the release of accumulated energy in the windings 15v and 15w is winding 15v → winding 15w → transistor 12 → negative side DC power supply line. 6 → diode D4 → winding 15v, and a current due to release of stored energy in the winding 15u flows in the same route as the arrow B2. And
The current flowing through the path indicated by arrow B2 gradually decreases due to the release of the accumulated energy of the winding 15u, and the commutation ends when the current becomes zero.

After the commutation, as shown in FIG. 18, when the transistor 12 is turned on by the PWM signal P1, a current flows through the same path as the path indicated by the arrow B1 to generate the PWM signal P1.
When the transistor 12 is turned off by 1, the above arrow B3
The current flows through the same route as the route indicated by.

The PWM signal P at such commutation timing
19, the terminal voltage Vu and the fundamental wave signal Vu ′ are shown in FIG. In the figure, (a) shows the case where the commutation ends during the high level of the PWM signal P1, (b) shows the case where the commutation ends during the low level of the PWM signal P1, and in the figure,
ts represents a commutation timing (commutation start time), and te represents an actual commutation end time. As is apparent from FIG. 17 described above, during the commutation, the diode D2 is always conductive regardless of whether the transistor 9 is turned on or off by the PWM signal P1, so that the terminal voltage Vu becomes the potential of the negative side DC power supply line 6, The fundamental wave signal Vu ′ maintains the low level state.

When the commutation is completed during the high level period of the PWM signal P1 (transistor 9 is on) (see FIG. 19).
In the case of (a)), since the current indicated by the arrow B1 in FIG.
Of the fundamental wave signal Vu ', the fundamental wave signal Vu' changes from low level to high level. Therefore, the measured commutation time Te coincides with the actual commutation time. However, when the commutation ends during the low level period of the PWM signal P1 (transistor 9 is off) (see FIG. 19).
In the case of (b)), the current shown by the arrow B3 in FIG. 18 flows and the diode D4 is in a conductive state, so that the terminal voltage Vu remains at the potential of the negative side DC power supply line 6 even after the commutation ends. The PWM signal P1 rises above the reference voltage V0 only when the PWM signal P1 changes to the high level. Therefore, the measured commutation time Te has a difference from the actual commutation time. This also occurs in the second phase division patterns Y1 and Y5.

According to this embodiment, however, the commutated positive side transistor 9 is maintained in the ON state and the negative side transistor 12 is ON / OFF controlled by the PWM signal P1. Therefore, as shown in FIG. In addition, the terminal voltage Vu always rises from the low level to the high level at the end of commutation, the end point of commutation can be accurately detected, and the commutation time can be accurately measured.

Further, in this embodiment, the time Tb required for each of the first phase division patterns X1 to X6 is measured by the first timer function, and the time from the zero cross point to the commutation timing is measured based on this measurement time. Since the calculation is performed and the time when the calculated time is measured by the second timer function is determined as the commutation timing, the time from the zero-cross time to the commutation timing varies depending on the rotation speed of the rotor. Even if there is, commutation timing can be easily determined by a computer program.

In the above embodiment, the division for detecting the commutation time is set to 12 for one rotation of the brushless motor 15 (for two cycles of the first phase division patterns X1 to X6). When the two compression units 33 are driven by the brushless motor 15, the load torque fluctuations occur periodically with one half rotation of the rotor as one cycle, so that the voltage pattern section corresponds to the first phase division patterns X1 to X6. It may be divided into 6 as one cycle.

Besides, the present invention is not limited to the embodiments described above and shown in the drawings, but can be modified or expanded as follows. The comparators 18 to 20 function as comparing means for comparing the terminal voltages Vu, Vv, Vw and the reference voltage V0, but they may be replaced with other well-known circuits. Although the voltage dividing resistance circuit 16 corresponds to the reference voltage generating means, it may be replaced with another means, and the reference voltage is 1/2 of the output voltage of the DC power supply circuit 2.
Not limited to

The pulse width modulation circuit 23 corresponds to the voltage control means, but it may be replaced with a chopper circuit. Further, the inverter device 47 is not limited to the inverter device that controls the motor of the compressor of the air conditioner, but can be widely applied to the inverter device for motor control.

[0092]

As described above, according to the inverter device of the present invention, the energization time of the diode during commutation, that is, the commutation time is detected, and the rotational position of the rotor is detected based on this commutation time and the rotor position information. Since the load torque information corresponding to is obtained, the abnormality can be detected early based on the load torque information.

Further, in the inverter device of the present invention, the terminal voltage of the winding is compared with the reference voltage, and the position information of the rotor is obtained based on the comparison result, thereby eliminating the need for the position detection sensor. Further, by adopting a configuration in which the current-carrying state of the diode is detected by comparing the terminal voltage of the winding with the reference voltage, it is not necessary to provide a circuit for detecting the current-carrying state of the diode, and the commutation time is measured. This simplifies the configuration. Further, when the abnormality determining means determines that the motor is abnormal, the motor is not energized so that the motor is not continuously operated in the abnormal state.

Therefore, the air conditioner of the present invention in which the compressor motor is controlled by the above-described inverter device can detect an abnormality early. In addition, it becomes easy to find an abnormal point by adopting a configuration in which the defectiveness of the blower of the refrigerant passage, the indoor / outdoor heat exchanger and the defectiveness of the compressor are determined from the magnitude of the load torque and the magnitude of the fluctuation of the load torque. .

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

[Figure 2] Waveform diagram of each part

FIG. 3 is a schematic configuration diagram of an indoor / outdoor unit of an air conditioner.

FIG. 4 is a characteristic diagram showing the relationship between load torque and commutation time when the voltage applied to the winding is constant.

FIG. 5 is a characteristic diagram showing the relationship between load torque and winding applied voltage when the rotation speed is constant.

FIG. 6 is a diagram showing the relationship between the presence / absence of an abnormality and the load torque and its variation when the rotation speed is constant.

FIG. 7 is a flowchart showing the contents of rotation speed control.

FIG. 8 is a flowchart showing control contents for determining commutation timing and detecting commutation time.

FIG. 9 is a flowchart showing the control contents for abnormality determination.

FIG. 10 is a diagram for explaining the operation

FIG. 11 is a circuit diagram showing a current path before the start of commutation.

FIG. 12 is a circuit diagram showing a current path during commutation.

FIG. 13 is a circuit diagram showing a current path after the end of commutation.

FIG. 14 is a waveform diagram showing the relationship between the winding voltage and the PWM signal of the fundamental wave signal during commutation.

FIG. 15 is a circuit diagram showing a current path during commutation in a state different from that of FIG.

16 is a view corresponding to FIG. 13.

FIG. 17 is a view corresponding to FIG. 12 for comparison with the present invention.

FIG. 18 is a view equivalent to FIG.

FIG. 19 is a view corresponding to FIG. 14.

FIG. 20 is a diagram corresponding to FIG. 1 showing a conventional inverter device.

FIG. 21 is a view corresponding to FIG.

FIG. 22 is a waveform diagram of the terminal voltage and current of one winding of the brushless motor.

[Explanation of symbols]

5 is a positive side DC power supply line, 6 is a negative side DC power supply line, 7, 9, 1
1 is a positive side switching transistor (positive side switching element) 8, 10 and 12 are negative side switching transistors (negative side switching element), 13 is a three-phase bridge circuit (switching circuit), 15 is a brushless motor, 1
5u, 15v, 15w are windings, 17 is a position signal circuit (position detecting means), 23 is a pulse width modulation circuit, 31 is a heat pump, 32 is a compressor, 35 is a four-way valve, 36 is an indoor heat exchanger, and 37 is Decompression device, 38 outdoor heat exchanger, 45 indicator, 47 inverter device, 48 microcomputer (conduction signal forming means, commutation time detecting means, torque detecting means, abnormality determining means), 49 gate circuit (Driving means).

Claims (9)

[Claims] 1. A switching circuit including a plurality of switching elements having diodes in parallel for sequentially energizing windings of a plurality of phases included in a motor, and position detection means for obtaining position information of a rotor included in the motor. An energization signal forming unit that obtains an energization signal corresponding to a predetermined commutation timing based on the position information, a driving unit that drives the switching element based on the energization signal, and a winding unit that commutates the switching element. Commutation time detection means for detecting the energization time of the diode due to release of accumulated energy of the wire, and the detection time being the commutation time of the switching element, and rotation of the rotor based on the position information and the commutation time. Torque detecting means for obtaining load torque information corresponding to the position, and an abnormality determining hand for determining abnormality based on the load torque information. An inverter device having a step. 2. The inverter device according to claim 1, wherein the position detecting means is configured to compare the terminal voltage of the winding with a reference voltage and obtain position information based on the comparison result. 3. The inverter device according to claim 1, wherein the commutation time detecting means is configured to detect the energized state of the diode by comparing a terminal voltage of the winding with a reference voltage. 4. The inverter device according to claim 1, further comprising means for stopping energization of the motor when the abnormality determination means determines that the abnormality has occurred. 5. A heat pump in which a compressor, an outdoor heat exchanger, a pressure reducing device, and an indoor heat exchanger are connected by a refrigerant passage, wherein the compressor motor is an inverter device according to any one of claims 1 to 3. An air conditioner characterized by being controlled. 6. The abnormality determining means determines the magnitude of the load torque and the magnitude of the fluctuation of the load torque from the load torque information, and when the magnitude of the load torque is small and the fluctuation of the load torque is small, the abnormality of the refrigerant passage is detected. The air conditioner according to claim 5, wherein 7. The abnormality determining means determines the magnitude of the load torque and the magnitude of the variation of the load torque from the load torque information, and when the magnitude of the load torque is small and the variation of the load torque is small, the abnormality of the refrigerant passage is detected. The air conditioner according to claim 5, wherein the air conditioner is determined to be: 8. The abnormality determining means determines the magnitude of the load torque and the variation of the load torque from the load torque information, and when the magnitude of the load torque is large and the variation of the load torque is large, it is determined that the compressor is abnormal. The air conditioner according to any one of claims 5 to 7, which is determined. 9. The air conditioner according to claim 5, further comprising means for notifying an abnormality determination result of the abnormality determination means.