JP2014128146A - Motor control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the time required until normal operation of a motor from being prolonged by detection of an open-phase fault or a short-circuit fault.SOLUTION: A gate drive circuit 53 performs DC electrification by setting an inverter circuit 30 to a first switching mode in the case of DC excitation when starting a fan motor 22 and then performs DC electrification by setting the inverter circuit 30 to a second switching mode different from the first switching mode further during the DC excitation. A current detection section 52 detects a first current flowing in the inverter circuit 30 under the first switching mode and a second current flowing in the inverter circuit 30 under the second switching mode. A fault detection section 55a performs fault detection by using the first current and the second current.

Description

  The present invention relates to a motor control device that controls a motor, and more particularly to a motor control device that controls a motor by controlling a switching operation of an inverter circuit that drives the motor.

  In recent years, in heat pump devices applied to air conditioners and water heaters, brushless DC motors are increasingly used to meet the demand for higher efficiency. Further, in order to reduce the cost of the heat pump apparatus, it is required to reduce the number of sensors for detecting the rotor position in such a brushless DC motor or the like.

  On the other hand, in order to appropriately drive a brushless DC motor or the like, it is also required to detect a failure of an inverter circuit that drives the motor or a failure of the motor. For example, in the detection method described in Patent Document 1 (Japanese Patent Application Laid-Open No. 2002-136147), an open-phase fault (open fault) is detected by measuring currents flowing through the inverter circuit in different switching modes. A short circuit fault has been detected.

  By the way, in the multiphase motor such as the brushless DC motor described in Patent Document 1, when detecting an open phase failure or a short circuit failure, there are many switching modes for specifying an abnormal part. For example, in the failure detection method of Patent Document 1, a failure is detected by six energization patterns, and it takes time to detect the failure.

  When the motor is sensorlessly controlled or driven with a small number of sensors, the rotor position is fixed by estimating the rotor position before starting or DC energization before starting, and then forcibly driven by adjusting the frequency and voltage. The steady operation is performed by estimating the rotor position. Therefore, when there is no sensor for detecting the rotor position or when there are few sensors, if the failure detection as described above is performed before starting each time the motor is driven, the starting time becomes longer.

  An object of the present invention is to prevent the time required for steady operation of a motor from becoming long due to detection of a phase failure or a short-circuit failure.

  A motor control device according to a first aspect of the present invention is a motor control device that controls a motor by controlling a switching operation of an inverter circuit that drives the motor, and is an inverter circuit during a positioning operation immediately after the start of the motor. An inverter control unit configured to set the inverter circuit in a second switching mode different from the first switching mode during the positioning operation and set the inverter circuit in the first switching mode. A current detection unit configured to detect a first current flowing in the inverter circuit of the first switching mode and a second current flowing in the inverter circuit of the second switching mode, and detected by at least the current detection unit Using the first current and the second current, the failure of the phase failure and the short circuit failure related to the motor and the inverter circuit Chino and a failure detecting section configured to detect failure including at least one, but.

  In the motor control device according to the first aspect, the first current flowing through the inverter circuit in the first switching mode and the second current flowing through the inverter circuit in the second switching mode during the positioning operation immediately after the start of the motor Therefore, failure detection can be performed at the time of positioning, and the motor startup time is shortened.

  A motor control device according to a second aspect of the present invention is the motor control device according to the first aspect, wherein the inverter control unit is turned on at least once for all the switching elements of the inverter circuit during the positioning operation immediately after startup. DC switching as a state is configured to switch between switching modes including the first switching mode and the second switching mode, and the current detection unit is configured to perform DC switching on the inverter circuit in the switching mode that the inverter control unit switches during the positioning operation. The failure detection unit is configured to detect a current including the first current and the second current that flows when the inverter control unit switches during the positioning operation. It is configured to perform fault detection.

  In the motor control device according to the second aspect, since direct current is energized at least once for all the switching elements of the inverter circuit, if a phase failure occurs in at least one switching element, A change occurs in one of the currents due to the phase failure. Therefore, it is possible to detect whether or not an open-phase failure has occurred in any of the switching elements of the inverter circuit.

  A motor control device according to a third aspect of the present invention is the motor control device according to the second aspect, wherein the inverter circuit includes the first switching element, the second switching element, and the third switching element in the upper arm and the second arm in the lower arm. Including four switching elements, a fifth switching element, and a sixth switching element, and the inverter control unit turns on the first switching element, the fourth switching element, and the fifth switching element in the first switching mode or the second switching mode, The second switching element, the third switching element, and the sixth switching element are configured to be turned on in the second switching mode or the first switching mode, and the failure detection unit includes the fourth switching element and the fifth switching element. A phase failure has occurred in one of the When the element has no phase failure, the first current or the second current and one of the second switching element and the third switching element has a phase failure, and the sixth switching element has a phase failure. From the larger value of the second current or the first current when it does not occur to the smaller value of the first current and the second current when no phase failure has occurred in the inverter circuit In the meantime, a threshold value for detecting a phase failure is set.

  In the motor control device according to the third aspect, it is possible to confirm an open phase failure related to all the switching elements of the inverter circuit with the two energization patterns of the first switching mode and the second switching mode.

  A motor control device according to a fourth aspect of the present invention is the motor control device according to the second aspect, wherein the inverter circuit includes the first switching element, the second switching element, and the third switching element in the upper arm and the second arm in the lower arm. The inverter control unit turns on the first switching element and the fourth switching element in the first switching mode, and sets the second switching element and the second switching device in the second switching mode. The fifth switching element is turned on, and the third switching element and the sixth switching element are turned on in the third switching mode. The current detection unit includes the first current and the second current, Configured to detect a third current flowing in an inverter circuit of three switching modes It has been, is intended.

  In the motor control device according to the fourth aspect, the change in the values of the first current to the third current can be increased between when the phase failure occurs and when the phase failure does not occur.

  The motor control device according to a fifth aspect of the present invention is the motor control device according to the fourth aspect, wherein the failure detection unit has a phase failure in any one of the first switching element to the sixth switching element. When the largest value among the first current, the second current and the third current flowing through the path of the phase failure and the phase loss failure does not occur in any of the first switching element to the sixth switching element A threshold for detecting an open-phase fault is set up to the smallest value among the first current, the second current, and the third current.

  In the motor control device according to the fifth aspect, even when the first current, the second current, and the third current flow slightly at the time of the phase failure, the phase failure can be detected.

  A motor control device according to a sixth aspect of the present invention is the motor control device according to any one of the first to fifth aspects, using at least the first current and the second current detected by the current detection unit. A winding resistance estimation unit for estimating the winding resistance value of the coil.

  The motor control device according to the sixth aspect can detect a failure or malfunction related to the motor winding from the winding resistance value of the motor estimated by the winding resistance estimation unit.

  A motor control device according to a seventh aspect of the present invention is the motor control device according to any one of the first to sixth aspects, wherein the motor is a brushless DC motor having two or less sensors.

  The motor control device according to the seventh aspect can reduce the cost because the number of sensors in the motor system including the brushless DC motor and the motor control device is small.

  In the motor control device according to the first aspect of the present invention, it is possible to suppress the time required for the steady operation of the motor from becoming long due to detection of a phase failure or a short circuit failure.

  In the motor control device according to the second aspect of the present invention, it is possible to suppress an increase in the time required for the steady operation of the motor even if the phase failure is detected for all the switching elements of the inverter circuit. .

  In the motor control device according to the third aspect of the present invention, it is possible to easily realize a motor control device capable of sufficiently shortening the startup time.

  In the motor control device according to the fourth aspect of the present invention, the change in the value of the first current to the third current becomes large, so that it is easy to detect the phase failure.

  In the motor control device according to the fifth aspect of the present invention, the certainty of detection of an open phase failure can be improved.

  In the motor control device according to the sixth aspect of the present invention, it is possible to detect a defect related to the winding of the motor.

  In the motor control device according to the seventh aspect of the present invention, the cost of the motor system including the motor and the motor control device can be kept low.

The refrigeration circuit diagram which shows an example of the air conditioning apparatus with which the motor control apparatus which concerns on this invention is applied. The circuit diagram for demonstrating the structure of the motor control circuit of this invention and the outdoor fan to which it is applied. The table for demonstrating the switching aspect which concerns on 1st Embodiment. (A) The timing chart which shows an example of the electric current which flows into shunt resistance, (b) The timing chart for demonstrating switching of a switching mode. The flowchart for demonstrating the failure detection of 1st Embodiment. The current waveform diagram for demonstrating the electric current which flows into the shunt resistance of 1st Embodiment. The table for demonstrating the relationship of the phase loss fault location and electric current detection of 1st Embodiment. The table for demonstrating the switching aspect which concerns on 2nd Embodiment. (A) The timing chart which shows an example of the electric current which flows into shunt resistance, (b) The timing chart for demonstrating switching of a switching mode. The current waveform diagram for demonstrating the electric current which flows into the shunt resistance of 2nd Embodiment. The table for demonstrating the relationship of the phase loss fault location and electric current detection of 2nd Embodiment.

<First Embodiment>
(1) Overall Configuration FIG. 1 is a diagram schematically illustrating the configuration of an air conditioner to which a motor control device according to a first embodiment of the present invention is applied. The air conditioner 10 of FIG. 1 includes an outdoor unit 101 and an indoor unit 102. The outdoor unit 101 is provided with a compressor 103, a four-way switching valve 104, an outdoor heat exchanger 105, an electric valve 106, an accumulator 107, an outdoor fan 20, and the like, and the indoor unit 102 includes an indoor heat exchanger 109. In addition, an indoor fan 110 and the like are provided. Here, one of the outdoor unit 101 and the indoor unit 102 corresponds to a heat source unit, and the heat source unit exchanges heat with other units to use heat.

  In the air conditioner 10, the outdoor unit 101 and the indoor unit 102 are connected by a pipe 111, whereby a refrigerant circuit in which refrigerant circulates is configured. In order to configure the refrigerant circuit, the outdoor heat exchanger 105 has one inlet / outlet connected to the four-way switching valve 104 and the other inlet / outlet not connected to the four-way switching valve 104 connected to the motor-operated valve 106. The motor valve 106 is connected to the indoor heat exchanger 109 at the inlet / outlet which is not connected to the outdoor heat exchanger 105. A four-way switching valve 104 is provided on the discharge side of the compressor 103. The refrigerant discharged from the compressor 103 enters from the first port of the four-way switching valve 104 and is returned to the compressor 103 from the third port of the four-way switching valve 104 via the accumulator 107.

  The four-way switching valve 104 has a connection indicated by a solid line during cooling, and a connection indicated by a broken line during heating, thereby switching the flow direction of the refrigerant during cooling and during heating. That is, during cooling, the second port and the first port of the four-way switching valve 104 connected to the outdoor heat exchanger 105 are opened, and the four-way switching valve 104 connected to the indoor heat exchanger 109 is opened. A connection is established between the fourth port and the third port. On the other hand, during heating, the fourth port and the first port of the four-way switching valve 104 connected to the indoor heat exchanger 109 are opened, and the second port connected to the outdoor heat exchanger 105 is connected to the second port. The connection with 3 ports is opened.

  The refrigerant circulates in a refrigeration circuit including the compressor 103, the outdoor heat exchanger 105, the motor-operated valve 106, the accumulator 107, and the indoor heat exchanger 109. During heating, the refrigerant that has taken in outdoor heat by the outdoor heat exchanger 105 of the outdoor unit 101 flows to the indoor heat exchanger 109 of the indoor unit 102, and the refrigerant heats indoor air by the indoor heat exchanger 109 of the indoor unit 102. discharge. Then, the refrigerant cooled by releasing heat returns from the indoor heat exchanger 109 to the outdoor heat exchanger 105. At the time of cooling, contrary to the time of heating, the refrigerant cooled by releasing heat to the outdoor heat exchanger 105 of the outdoor unit 101 flows into the indoor heat exchanger 109 of the indoor unit 102, and the indoor heat exchanger 109 The heat is taken away from the room air by taking in heat. The refrigerant whose temperature has risen due to the heat removed from the indoor heat exchanger 109 releases heat again in the outdoor heat exchanger 105.

  The outdoor air and the indoor fan 110 provided in the outdoor heat exchanger 105 and the indoor heat exchanger 109 generate the outdoor air and the air flow of the indoor air that exchange heat with the refrigerant. When a phase loss abnormality occurs in the driving devices of the fan motors 22 and 110a that drive the outdoor fan 20 and the indoor fan 110, the rotation speed of the fan motors 22 and 110a is reduced, noise is generated, The trouble that 110a stops or the like occurs. When the rotational speed of the fan motors 22 and 110a is reduced or stopped, the air flow is reduced or stopped, and the efficiency of heat exchange between the refrigerant and the indoor air or the outdoor air is deteriorated. 10 takes measures such as notifying the outside of the abnormality and stopping the operation of the air conditioner 10. Therefore, the air conditioning apparatus 10 includes a main control device 120 that performs overall control. Main controller 120 is connected to compressor 103, outdoor heat exchanger 105, motor-operated valve 106, outdoor fan 20, indoor heat exchanger 109, and indoor fan 110. This is because the main controller 120 obtains information necessary for control from various detectors in and around these devices, and a specific device among these devices, for example, the fan motors 22 and 110a. This is for controlling the rotation and the operating frequency of the compressor 103.

(2) Indoor fan and outdoor fan The motor control apparatus according to the first embodiment can be applied to any of the fan motors 22 and 110a of the outdoor fan 20 and the indoor fan 110. Here, the fan of the outdoor fan 20 is used. A case where it is applied to the motor 22 will be described. As shown in FIG. 2, the outdoor fan 20 includes a rotary blade 21, a fan motor 22, an inverter circuit 30, a rectifier circuit 40, and a motor control device 50. The rotary blade 21 is driven by a fan motor 22 to rotate. The fan motor 22 is supplied with drive voltages SU, SV, and SW from the inverter circuit 30. A DC voltage rectified by the rectifier circuit 40 is applied to the inverter circuit 30. The inverter circuit 30 is controlled by the motor control device 50. The motor control device 50 controls the number of revolutions of the fan motor 22 by controlling the inverter circuit 30.

(2-1) Rectifier circuit (2-1-1) Rectifier The four diodes D1a, D1b, D2a, and D2b constituting the rectifier 41 are connected in a bridge shape to form a bridge circuit. In order to form a bridge circuit, two diodes D1a and D1b are connected in series, and similarly two diodes D2a and D2b are connected in series. The cathode terminals of the diodes D1a and D2a are both connected to the plus side terminal of the smoothing capacitor 42 and function as the plus side output terminal of the rectifying unit 41. The anode terminals of the diodes D1b and D2b are both connected to the negative terminal of the smoothing capacitor 42 and function as the negative output terminal of the rectifier 41. A connection point between the anode terminal of the diode D1a and the cathode terminal of the diode D1b and a connection point between the anode terminal of the diode D2a and the cathode terminal of the diode D2b are connected to two output terminals of the commercial power supply 91, respectively. The rectifying unit 41 having such a configuration rectifies the AC voltage Vac input from the commercial power supply 91 and supplies it to the smoothing capacitor 42.

(2-1-2) Smoothing capacitor 42
The smoothing capacitor 42 smoothes the voltage rectified by the rectifying unit 41. The voltage smoothed by the smoothing capacitor 42 is a DC voltage Vdc with low ripple, and is applied to the inverter circuit 30 connected to the subsequent stage of the smoothing capacitor 42, that is, the output side. The potential of the line connected to the negative terminal of the smoothing capacitor 42 becomes a reference potential (hereinafter referred to as GND).

(2-2) Inverter Circuit The inverter circuit 30 is connected to the output side of the smoothing capacitor 42. As shown in FIG. 2, the inverter circuit 30 includes a plurality of insulated gate bipolar transistors (hereinafter simply referred to as transistors) Q3a, Q3b, Q4a, Q4b, Q5a, Q5b and a plurality of freewheeling diodes D3a, D3b, D4a, D4b, D5a, D5b are included. The inverter circuit 30 includes bootstrap capacitors C3, C4, C5, resistors R3, R4, R5 and diodes D3c, D4c, D5c connected in series thereto. A DC voltage VD that can drive the transistors Q3a, Q4a, and Q5a is connected to the bootstrap capacitors C3, C4, and C5 via the resistors R3, R4, and R5 and the diodes D3c, D4c, and D5c, and the transistors Q3b, Q4b, and Q5b Is turned on, the bootstrap capacitors C3, C4, and C5 are charged to voltages based on NU, NV, and NW, respectively. Although not shown here, the bootstrap capacitors C3, C4, and C5 are connected to the driving circuits of the transistors Q3a, Q4a, and Q5a on the diodes D3c, D4c, and D5c sides, respectively, and power sources for driving the transistors Q3a, Q4a, and Q5a It becomes. The diodes D3c, D4c, and D5c are not discharged to the DC voltage VD side when the potentials of the bootstrap capacitors C3, C4, and C5 fluctuate due to the inverter operation and become higher than the DC voltage VD. Is provided.

  Transistors Q3a and Q3b, Q4a and Q4b, Q5a and Q5b are connected to each other in series, and each of the diodes D3a to D5b has a transistor collector terminal and a diode cathode terminal, The transistors are connected in reverse parallel so that the emitter terminal of the transistor and the anode terminal of the diode are connected.

  The inverter circuit 30 is applied with the DC voltage Vdc from the smoothing capacitor 42, and the transistors Q3a to Q5b are turned on and off at the timing instructed by the motor control device 50, whereby the drive voltage SU for driving the fan motor 22 is supplied. , SV, SW are generated. The drive voltages SU, SV, SW are output to the fan motor 22 from connection points NU, NV, NW of the transistors Q3a and Q3b, Q4a and Q4b, and Q5a and Q5b.

(2-3) Fan motor 22
The fan motor 22 is configured by a three-phase brushless DC motor, and includes a stator 22a and a rotor 22b.

  The stator 22a includes U-phase, V-phase, and W-phase drive coils Lu, Lv, and Lw that are star-connected. One end of each drive coil Lu, Lv, Lw is connected to drive coil terminals TU, TV, TW of U-phase, V-phase, and W-phase wirings extending from an inverter circuit 30 (described later), respectively. The other ends of the drive coils Lu, Lv, and Lw are connected to each other as a terminal TN. These three-phase drive coils Lu, Lv, and Lw generate an induced voltage according to the rotational speed and the position of the rotor 22b when the rotor 22b rotates.

  The rotor 22b includes a plurality of permanent magnets including N poles and S poles, and rotates about the rotation axis with respect to the stator 22a. The rotational torque of the rotor 22b is transmitted to the rotary blade 21 via the output shaft that is on the same axis as the rotational shaft.

(2-4) Motor control device 50
As described above, the motor control device 50 controls the fan motor 22 by controlling the inverter circuit 30. In order to control the fan motor 22, currents and voltages related to the fan motor 22 and the inverter circuit 30 are detected, and a voltage detection unit 51 and a current detection unit 52 are provided. Further, in order to generate the gate control voltages Gu, Gx, Gv, Gy, Gw, Gz for changing the gate potentials of the transistors Q3a, Q3b, Q4a, Q4b, Q5a, Q5b to the inverter circuit 30, the gate driving circuit 53, A sensorless control circuit 54 and a microcomputer 55 are provided.

(2-4-1) Voltage detector 51
The voltage detection unit 51 is connected to the output side of the smoothing capacitor 42 and detects the voltage across the smoothing capacitor 42, that is, the magnitude of the DC voltage Vdc. For example, the voltage detection unit 51 is configured such that two resistors connected in series are connected in parallel to the smoothing capacitor 42 and the DC voltage Vdc is divided. The voltage at the connection point between these two resistors is input to the sensorless control circuit 54.

(2-4-2) Current detection unit 52
The current detection unit 52 is connected between the smoothing capacitor 42 and the inverter circuit 30 and connected to the negative terminal of the smoothing capacitor 42. The current detection unit 52 detects the motor current Im flowing through the fan motor 22 after the fan motor 22 is started. The current detection unit 52 may be configured by, for example, an amplifier circuit using a shunt resistor and an operational amplifier that amplifies the voltage across the resistor. In the current detection unit 52, for example, a shunt resistor is inserted in series in the GND side line supplying the DC voltage Vdc to the inverter circuit 30, and a voltage corresponding to the motor current Im detected by being amplified by the amplifier circuit is obtained. Input to the sensorless control circuit 54.

(2-4-3) Gate drive circuit 53
Based on the start command from the sensorless control circuit 54, the gate drive circuit 53 changes the on and off states of the transistors Q3a to Q5b of the inverter circuit 30. Specifically, the gate drive circuit 53 includes the transistors Q3a to Q5b so that the drive voltages SU, SV, SW having the duty determined by the sensorless control circuit 54 are output from the inverter circuit 30 to the fan motor 22. Gate control voltages Gu, Gx, Gv, Gy, Gw, and Gz to be applied to the gate are generated. The generated gate control voltages Gu, Gx, Gv, Gy, Gw, Gz are applied to the respective gate terminals of the transistors Q3a to Q5b.

  Since this fan motor 22 is sensorlessly controlled, it is DC-excited by the gate control voltages Gu, Gx, Gv, Gy, Gw, Gz of the gate drive circuit 53 immediately after startup. In particular, the motor control device 50 fixes the rotor by flowing a direct current through two switching modes in direct current excitation in order to perform a phase failure and short circuit failure during direct current excitation. The operation of the gate drive circuit 53 when the rotor is fixed will be described in detail later.

(2-4-4) Sensorless control circuit 54
The sensorless control circuit 54 is connected to the voltage detection unit 51, the current detection unit 52, the gate drive circuit 53, and the microcomputer 55. The sensorless control circuit 54 has a function for driving and controlling the fan motor 22 by a sensorless system, more specifically, by a rotor position sensorless system.

  The fan motor 22 is first activated by a direct current excitation method. The direct current excitation method is a state in which the position of the rotor 22b in the fan motor 22 is temporarily fixed at a predetermined position and the rotor 22b is fixed by applying a direct current to the fan motor 22 immediately after startup. In this method, rotation of the fan motor 22 is started.

  In the rotor position sensorless system for controlling the fan motor 22, a drive voltage having a predetermined AC waveform is applied in a state asynchronous with the rotational phase until the rotational phase reaches a rotational speed at which the rotational phase can be detected after the rotor 22b is fixed. Thus, forcible driving for forcibly increasing the rotational speed of the rotor 22b is performed.

  The sensorless control circuit 54 estimates the position of the rotor 22b of the fan motor 22 that has started rotating after the rotor is fixed, and estimates the rotational speed of the fan motor 22 based on the estimated position of the rotor 22b. The estimated rotational speed of the fan motor 22 is input to the microcomputer 55 as the rotational speed signal FG. When an operation command including the rotation speed command Vfg is sent from the microcomputer 55 to the sensorless control circuit 54, the sensorless control circuit 54 detects the operation command, the estimated position of the rotor 22b, the estimated rotation speed, and the voltage detection unit 51. And the detection result of the current detector 52 are used to determine the duty of the drive voltages SU, SV, SW at each control timing by the rotor position sensorless method, and the gate drive circuit 53 is instructed by the voltage command value Vpwm.

  In the rotor position sensorless system described here, various parameters indicating the characteristics of the fan motor 22, the DC voltage Vdc (that is, the detection result of the voltage detection unit 51), the motor current Im (that is, the detection result of the current detection unit 52). ), And a predetermined mathematical model related to the control of the fan motor 22, the position of the rotor 22 b is estimated, the rotational speed is estimated, the PI control is performed on the rotational speed, and the PI control is performed on the motor current Im. Examples of various parameters indicating the characteristics of the fan motor 22 include the winding resistance, inductance component, induced voltage, and number of poles of the fan motor 22 used.

(2-4-5) Microcomputer 55
The microcomputer 55 is connected to the current detection unit 52, the sensorless control circuit 54, and the main control device 120. The microcomputer 55 controls the fan motor 22 in accordance with a command from the main controller 120. Further, when a phase failure or a short-circuit failure occurs in the fan motor 22 or the inverter circuit 30, a signal indicating the occurrence of the failure is transmitted from the microcomputer 55 to the main controller 120.

  The microcomputer 55 detects a phase failure and a short-circuit failure when the rotor is fixed when the fan motor 22 is started. Therefore, the microcomputer 55 receives a signal related to the current detected by the current detection unit 52 from the current detection unit 52 during direct current excitation.

  The microcomputer 55 has a failure detection unit 55a for detecting a phase failure and a short-circuit failure when the rotor is fixed. The failure detection unit 55a detects an open-phase failure and a short-circuit failure based on the current detected by the current detection unit 52 in the two energization patterns when the rotor is fixed. The failure detection performed by the failure detection unit 55a will be described in detail later.

(3) Outline of start-up operation Three-phase alternating current is supplied to the fan motor 22 by the inverter circuit 30 from a state where the fan motor 22 is stopped or slightly rotated due to an air current or the like, and the fan motor 22 is instructed from the main controller 120 A brief explanation will be given until the number of rotations is reached. The main control device 120 instructs the motor control device 50 on the target rotational speed of the fan motor 22 in the control approaching the state of the refrigerant circuit that can realize the set air conditioning.

  The motor control device 50 performs direct current excitation in order to fix the rotor position immediately after the fan motor 22 is started. In this DC excitation, the inverter circuit 30 adopts two switching modes for energizing in two energization patterns. In these two switching modes, the motor control device 50 performs failure detection.

  If a failure is detected and there is no failure, the motor control device 50 then performs forcible driving, and further, the gate control voltages Gu, Gx, Gv, Gy, Gw, and Gz are generated. If a failure is detected by the failure detection, the motor control device 50 notifies the main control device 120 that at least one of a phase failure and a short-circuit failure has occurred. Main controller 120 receives the notification of the occurrence of the failure from motor control device 50 and displays the occurrence of the failure on a display unit (not shown) of air conditioner 10. The main controller 120 receives the notification of the occurrence of the failure from the motor controller 50 and stops the start-up operation of the fan motor 22.

(4) Operation related to failure detection Before explaining the switching mode at the time of DC excitation, the relationship between the switching modes S _{1 to} S ₆ and the current flowing in the U phase, V phase and W phase will be explained using FIG. To do. In FIG. 3, ◯ indicates that current flows, and × indicates that no current flows. For example, when the inverter circuit 30 takes the switching mode S _1, if there is a fault in the fan motor 22 and the inverter circuit 30, no current flows through the high-arm side of the U-phase and V-phase, the current W-phase of the high-arm side Flowing. That is, in the switching mode S _1, transistor Q3a, Q4a is turned off, the transistor Q5a is turned on. On the other hand, the low-arm side in switching mode S _1, current flows through the U-phase and V-phase, so that no current flows through the W-phase, the transistors Q3b, Q4b is turned on, the transistor Q5b is turned off.

As for switching modes S _{2 to} S ₆ , as shown in FIG. 3, the current flows in one phase on either the high arm side or the low arm side and the current does not flow in the two phases. In this configuration, current flows in two phases and no current flows in one phase.

In addition to the switching modes S _{1 to} S _6, there is a switching mode S ₀ . The switching mode S ₀ is a mode in which the high-arm transistors Q3a and Q4a of the inverter circuit 30 are turned off and only the low-arm transistors Q3b, Q4b, and Q5b are turned on. This switching mode S ₀ is provided for charging the bootstrap capacitors C 3, C 4, C 5, and allows a current to flow between the motor and the inverter circuit when DC excitation is not performed. Work. In this switching mode S ₀ , direct current excitation is not performed on the motor. While this reflux operation is being performed, current flows in the U-phase, V-phase, and W-phase on the low arm side, but no current is supplied from the DC voltage Vdc side, and the bootstrap capacitor is charged. if it has, the transistor Q3b, Q4b, charging current flowing through the Q5b and current detector 52, because negligibly small in comparison with the current detected by the DC excitation, switching mode S ₀ in FIG. 3 The current at this time is x.

The two energization patterns at the time of direct current excitation are combinations in which the six transistors Q3a to Q5b of the inverter circuit 30 are turned on once by these two energization patterns. For example, when the switching mode S ₁ is chosen one, the switching mode S ₆ is selected in the other. In other words, high-arm side transistor Q3a, Q4a is turned on when the switching mode S _6, transistor Q5a is turned on when the switching mode S _1. Looking at the low-arm side transistors Q3b, Q4b is turned on when the switching mode S _1, the transistor Q5b is turned on when the switching mode S _6.

Specifically, for example, switching of the switching mode is performed as in the DC excitation period Tdc shown in FIG. First, it performed the charging of the bootstrap capacitor C3~C5 in switching mode S ₀ is a transistor Q3a switching mode S _6, Q4a, is either not occur failures in any of Q5b be examined. Then again, in switching mode S ₀ with charging the bootstrap capacitor C3-C5, to attenuate the current flowing in the motor by refluxing operation. And further, a transistor Q3b switching mode S _1, Q4b, is either not occur failures in any of Q5a is examined.

Next, a failure detection procedure will be described with reference to the flowchart of FIG. In DC excitation, after being charged in the bootstrap capacitor C3-C5, the first switching mode, the case shown, for example, in FIG. 4 (b) is energized by the switching mode S ₆ (step ST1). With this energization, the rotor 22b starts rotating to move to a fixed position. At this time, the current detector 52 detects the current of the shunt resistor and outputs the detection result to the microcomputer 55 via the sensorless control circuit 54. In the microcomputer 55, the failure detection unit 55a detects an open phase failure and a short-circuit failure using the current detected by the current detection unit 52 (step ST2). If the failure detection unit 55a detects the occurrence of a failure (step ST3), the microcomputer 55 notifies the main controller 120 that there is an abnormality in the outdoor fan 20, and the microcomputer 55 causes the fan motor 22 to The rotation is stopped (step ST8).

If no failure is detected in the failure detection unit 55a in step ST2, the process proceeds from step ST3 to step ST4, and after the bootstrap capacitors C3 to C5 are charged, the second switching mode, for example, as shown in FIG. If that is being energized by the switching mode S _1. By this energization, the rotor 22b of the fan motor 22 is fixed at a predetermined position. At this time, the current detection unit 52 detects the current of the shunt resistor, and the failure detection unit 55a detects an open-phase failure and a short-circuit failure as in step ST2 (step ST5). At this time, the resistance value of the drive coils Lu, Lv, and Lw of the fan motor 22 is estimated using the current value detected by the shunt resistor and the voltage value detected by the voltage detector 51. This is performed by the resistance estimation unit 55b. If the failure detection unit 55a detects the occurrence of a failure (step ST6), the microcomputer 55 notifies the main controller 120 that there is an abnormality in the outdoor fan 20, and the microcomputer 55 causes the fan motor 22 to The rotation is stopped (step ST8). If no failure is detected in failure detection unit 55a in step ST5, the process proceeds from step ST6 to step ST7, forcibly energized to rotate the rotor.

The detection of the failure of the transistors Q3a to Q5b performed in steps ST2 and ST5 is performed by determining the magnitude of the current flowing through the shunt resistor of the current detection unit 52 shown in FIG. FIG. 4A shows a current waveform when no failure occurs, and the current values of the currents flowing in the switching modes S ₁ and S ₆ both exceed the threshold value I _th1 . .

FIG. 6 shows an enlarged view of the current waveform IW1 of the current flowing through the shunt resistor shown in FIG. FIG. 6 also shows current waveforms IW2 and IW3 of the current that flows through the shunt resistor when an open-phase failure has occurred. Further, FIG. 6 shows a current waveform IW4 when a short-circuit failure has occurred in the fan motor 22 or the inverter circuit 30. Since the current waveform IW1 is a current waveform when the open-phase fault as described above does not occur, it exceeds the threshold value I _th1 in the period T2 in which a steady state. However, since the current waveform IW1 does not exceed the threshold value I _th1 in the period T1 in the transient state, the phase loss failure inspection is performed in the period T2 in which the current value is relatively stable in the steady state. Using this current waveform IW1, the resistance values of the drive coils Lu, Lv, Lw of the fan motor 22 can be estimated.

  The current waveform IW2 is an example of a current waveform in a case where a phase failure has occurred in one of the arms to be energized in two phases. As can be seen from the current waveform IW2, when a phase failure has occurred in one phase, the current flows through two transistors connected in series, but the current flows through three transistors. As compared with the above, since the resistance value of the current path connected to the shunt resistor becomes high, the current flowing through the shunt resistor decreases.

  The current waveform IW3 is a current waveform when a phase failure has occurred in the arm to be energized in one phase, or a phase failure has occurred in both phases of the arm to be energized in two phases. It is an example of the current waveform when it has occurred. In this case, since there is no current path connected to the shunt resistor, no current flows through the shunt resistor.

The current waveform IW4 is an example of a current waveform when a short circuit failure has occurred in the fan motor 22 or the inverter circuit 30. In this case, since a short circuit with a very low resistance value is formed which connects the positive side terminal of the smoothing capacitor 42 to the negative side terminal of the smoothing capacitor 42 via the fan motor 22 or the inverter circuit 30 and the current detection unit 52, a shunt resistor can be formed. A very large current flows in Therefore, by setting a sufficiently large threshold value I _th2 compared to the largest current value of the current waveform IW1 when no failure has occurred, a short-circuit failure is detected using the current value detected by the current detection unit 52. can do. In detecting a short-circuit fault, it is not preferable to apply a large current for a long period of time. Therefore, the microcomputer 55 stops energization of the fan motor 22 based on the determination of the short-circuit fault when the threshold value I _th2 is exceeded even in the transient period T1. .

FIG. 7 shows a summary of the relationship between the above-described location of the phase failure and each switching mode. The upper part of FIG. 7 shows the correspondence between the type of arm and the phase failure. In the upper part of FIG. 7, “◯” indicates that no phase failure has occurred, and “X” indicates that a phase failure has occurred. For example, the first line in the upper stage of FIG. 7 describes whether or not a phase failure has occurred on the U-phase high arm side, that is, the transistor Q3a. The lower part of FIG. 7 shows the correspondence between switching modes and current detection. The circles in the lower part of FIG. 7 indicate that the current value detected by the current detection unit 52 exceeds the threshold value I _th1 . X in the lower part of FIG. 7 indicates that the current value was zero. Then, Δ in the lower part of FIG. 7 indicates that the current value was not 0 but was smaller than the threshold value I _th1 . In other words, ○ indicates that no phase failure has occurred (state of current waveform IW1), and x indicates that the current path is completely open (state of current waveform IW3) due to phase failure. , Δ indicates that the current value is decreasing due to an open phase failure (the state of the current waveform IW2). Usually, since the probability that two or more transistors fail simultaneously is small, it can be inferred that there is a high possibility that a transistor in which only one phase is involved in energization is broken at the lower part of FIG.

Next, the overall view of FIG. 7 will be described. In the upper row of FIG. 7, there is no “x” and only “◯” is marked. That is, the first column in FIG. 7 indicates that no phase failure has occurred in the inverter circuit 30 and the fan motor 22. Accordingly, the first row in the lower part of FIG. In the second row in the upper part of FIG. 7, “x” is marked only on the U-phase high arm side, indicating that a phase failure has occurred on the U-phase high arm side. In such a case, if the inverter circuit 30 is in the switching mode S ₄ , the current waveform IW3 is generated, and thus a phase failure has occurred, and the location may be on the U-phase high arm side. High is identified. In such a case, if the inverter circuit 30 is in the switching mode S ₅ , the current waveform IW2 is generated, so that it can be determined that a phase failure has occurred on the high arm side. It is not possible to specify whether it is the U phase or the W phase. Similarly, in such a case, if the inverter circuit 30 is in the switching mode S ₆ , the current waveform IW2 is generated, so that it can be identified that a phase failure has occurred on the high arm side, but the open state It is not possible to specify whether it is the U phase or the V phase.

For example, in the case of using the switching mode S ₁ and the switching mode S _{6 at} the time of DC excitation already described, when a phase failure is detected, a phase failure occurs on the high arm side and the low arm side of the W phase. It is possible to estimate that there is a high possibility that the phase failure has occurred in either the U phase or the V phase.

(5) Features (5-1)
As described above, at the time of direct current excitation (an example of a positioning operation) immediately after the start of the fan motor 22, for example, the switching mode S ₆ (an example of the first switching mode) by the gate drive circuit 53 (an example of the inverter control unit). Current flowing from the inverter circuit 30 to the current detection unit 52 (an example of the first current) and, for example, a current flowing from the inverter circuit 30 in the switching mode S ₁ (an example of the second switching mode) to the current detection unit 52 ( The failure detection unit 55a performs failure detection using the second current). Therefore, the failure detection can be performed in parallel with the DC excitation rotor position fixing, and the startup time of the fan motor 22 is shortened compared to the case where the DC excitation rotor position fixing and the failure detection are sequentially performed. Thus, in the motor control device 50, it is possible to prevent the time required for steady operation of the fan motor 22 from becoming long due to detection of a phase failure or a short-circuit failure.

In the above embodiment, at least once on state relative to (an example of the first switching element to sixth switching elements) all the transistors Q3a~Q5b inverter circuit 30 by using a combination of switching mode S ₁ and the switching mode S ₆ In this case, direct current is applied. Although the location where the phase failure has occurred cannot be specified, it is possible to detect whether or not the phase failure has occurred for all phases on the high arm (an example of the upper arm) side and the low arm (an example of the lower arm) side. . As a result, even if the phase failure of all the transistors Q3a to Q5b of the inverter circuit 30 is detected, it is possible to suppress an increase in the time required until the fan motor 22 operates normally.

In the above embodiment, the one time each and every transistor Q3a~Q5b uses a combination of switching mode S ₁ and the switching mode S ₆ for DC application is turned on and the combination of the switching mode of the inverter circuit 30 which only it is not limited, for example, may be a combination of switching mode S ₂ and switching mode S combination or switching mode S ₃ of the ₅ and switching mode S _4.

(5-2)
In winding resistance estimating unit 55b, in each switching manner of switching mode S ₁ and the switching mode S _6, based on the detection result of the voltage detector 51 and the current detection unit 52, the drive coils Lu of the fan motor 22, Lv, Lw The resistance value (an example of the winding resistance value) is estimated. If the winding resistance value estimated by the winding resistance estimation unit 55b deviates from a preset value, it can be estimated that some trouble has occurred in the drive coils Lu, Lv, and Lw.

(5-3)
As described above, in the failure detection unit 55a, the threshold value I _th1 shown in FIG. 6 is set in order to detect an open phase failure. This threshold value I _th1 is set to a value smaller than the current value of the current waveform IW1. The current value of the current waveform IW1 is a current value (an example of a smaller value of the first current and the second current) when no phase failure has occurred in the inverter circuit 30. On the other hand, the threshold value I _th1 is set to a value larger than the current value of the current waveform IW2. The current value of the current waveform IW2 is the current value (first current and current) when a phase failure has occurred in one of the two transistors connected in parallel in the inverter circuit 30 in the switching modes S ₁ and S ₆ . This is an example of the larger value of the second currents).

In the above description, when no phase failure has occurred, the transistor Q3a (an example of the second switching element), the transistor Q4a (an example of the third switching element), and the transistor in the switching mode S ₆ (an example of the first switching mode) The current waveform when Q5b (an example of the sixth switching element) is in an on state is a current waveform IW1. Similarly, when no phase failure has occurred, the transistor Q5a (an example of the first switching element), the transistor Q3b (an example of the fourth switching element), the transistor Q4b (an example of the second switching element) in the switching mode S ₁ (an example of the second switching mode). The waveform of the current when the example of the fifth switching element is on is also the current waveform IW1.

Here, a case has been described in which there is no magnitude between the currents flowing in the state of the switching modes S ₁ and S ₆ when no open-phase fault has occurred. The threshold value I _th1 is set to be smaller than the smaller current value.

Also, switching mode S ₁ state in transistor Q3b connected in parallel, the waveform of the current when open-phase fault in the transistor Q5a have occurred open-phase fault on one Q4b is not generated as the current waveform IW2 Become. Similarly, switching mode S ₆ of the state in the transistor Q3a is connected in parallel, as waveforms of the current waveform IW2 of current when the open-phase fault in the transistor Q5b have occurred open-phase fault on one Q4a has not occurred become.

Here, a case has been described in which an open-phase fault has occurred in one of the transistors connected in parallel, and the currents flowing in the states of the switching modes S ₁ and S ₆ are not large. In order to prevent erroneous detection, the threshold value I _th1 is set to be larger than the larger current value.

When the current waveform is IW3, that is, when a phase failure has occurred in the arm to be energized in one phase, or in both phases of the arm to be energized in two phases. When an open phase failure has occurred, the current value is smaller than the threshold value I _th1 , so that the open phase detection can be performed with the same threshold value even at the time of these open phase failures.

As described above, the open-phase fault related to all the transistors Q3a to Q5b of the inverter circuit 30 can be confirmed by the two energization patterns of the switching modes S ₁ and S ₆ . Confirmation can be made with two energization patterns, and a short activation time can be easily realized in the activation control of the motor control device 50. In addition, if the threshold value is set in this manner, for example, when the current value is large or small due to component characteristic variation or manufacturing variation, or the current value is different between the U phase, the V phase, and the W phase. Even if it is, it can respond.

(6) Modification (6-1) Modification 1A
In the first embodiment, the DC excitation when the fan motor 22 which is a brushless DC motor is driven by sensorless control is described as an example. However, if the motor is to be subjected to DC excitation, sensorless control is performed. It is not limited to a brushless DC motor. For example, the invention described in the above embodiment can be applied even in the case of direct current excitation of a brushless DC motor having two or less sensors for detecting the rotor position. Further, the motor is not limited to the brushless DC motor as long as the rotor position is fixed by DC excitation at the time of start-up, and can be applied to other types of motors. Further, the cost can be suppressed by setting the number of sensors to two or less.

(6-2) Modification 1B
In the first embodiment, the inverter circuit 30 configured using a bootstrap capacitor has been described as an example. However, the present invention can also be applied to an inverter circuit that does not use a bootstrap capacitor. In that case, it can be operated by omitting the switching mode S _0. Alternatively, it can be operated as a switching mode in which all transistors are turned off when DC excitation is not performed.

(6-3) Modification 1C
When direct current excitation is performed, the fixed position of the rotor varies depending on the switching mode. If it is known that the rotor position before DC excitation is within a predetermined range, such as by providing a rotor position detection sensor, the switching mode that can fix the rotor to a position close to that range is If the switching mode is selected, it is possible to reduce the amount of movement of the rotor when direct current excitation is performed. Therefore, the time until the current value is stabilized is shortened, and the fluctuation of the current can be reduced. .

(6-4) Modification 1D
In the first embodiment, DC excitation is performed for two modes in a switching mode in which two elements on one side arm and one element on the opposite side arm are energized, and abnormalities are detected in all modes by detecting abnormalities in either mode. If the abnormality of all elements can be detected, there may be three or more switching modes for performing DC excitation (fixing the position), and in that case, all the switching is performed. It is not necessary to detect anomalies in a manner.

After DC excitation, the abnormality detection in switching mode S ₆ in the above embodiment, although performing DC excitation, the abnormality detection in switching mode S _1, the rotor fixed position by these switching mode is 180 electrical degrees Therefore, for example, DC excitation (rotor position fixing) is performed in one of the switching modes S ₂ and S ₃ between these switching modes, or switching mode S ₆ → switching mode S ₂ → switching mode S ₃ → by performing a DC excitation (rotor stationary) operation in the order of switching mode S _1, it is possible to shorten the rotor movement distance in one DC excitation operation. As a result, the time until the current value is stabilized during DC excitation is shortened and the fluctuation of the current can be reduced, so that the measurement standby time until the current detection (period T2 shown in FIG. 6) is reduced. It can be shortened. At this time, abnormality detection may not be performed in the switching modes S ₂ and S ₃ .

Second Embodiment
(1) Configuration Next, a motor control device according to a second embodiment of the present invention will be described with reference to FIGS. An air conditioner to which a motor control device according to a second embodiment described below is applied is the same as the configuration of the first embodiment shown in FIG. 1, and the configuration of the motor control device is also shown in FIG. Since it is the same as the structure of 1st Embodiment shown, these descriptions are abbreviate | omitted and the motor control apparatus which concerns on 2nd Embodiment is demonstrated using FIG.1 and FIG.2.

  The motor control device according to the first embodiment performs failure detection using two energization patterns of the first switching mode and the second switching mode of the inverter circuit 30 during DC excitation. On the other hand, the motor control device of the second embodiment performs failure detection using three energization patterns at the time of DC excitation as described below.

(2) Switching Mode Here, a switching mode for performing the three energization patterns will be described with reference to FIGS. First, the relationship between the switching modes S _{1a to} S _6a shown in FIG. 8 and the current flowing in the U phase, the V phase, and the W phase will be described. In FIG. 8, ◯ indicates that current flows, and × indicates that current does not flow. For example, when the inverter circuit 30 adopts the switching mode S _1a , if there is no failure in the fan motor 22 and the inverter circuit 30, no current flows in the U-phase and V-phase on the high arm side, and no current flows in the W-phase on the high arm side. Flowing. That is, in the switching mode S _1a , the transistors Q3a and Q4a are turned off and the transistor Q5a is turned on. On the other hand, on the low arm side in the switching mode S _1a , the transistor Q3b is turned on and the transistors Q4b and Q5b are turned off so that no current flows in the U phase and no current flows in the V phase and the W phase. In addition, in the motor control device 50 of the second embodiment, the switching mode S ₀ has a switching mode S ₀ other than the switching modes S _{1a to} S _{6a in} order to charge the bootstrap capacitors C3, C4, and C5, as in the first embodiment. Is provided.

As shown in FIG. 8, the switching modes S _{2a to} S _6a also have a configuration in which a current flows in one phase and a current does not flow in two phases on both the high arm side and the low arm side. It has become.

(3) Failure detection The three energization patterns at the time of direct current excitation are combinations in which the six transistors Q3a to Q5b of the inverter circuit 30 are turned on once by these three energization patterns. For example, when the switching mode S _3a is selected for one, the switching modes S _5a and S _6a are selected for the other. That is, the transistor Q3a of the high-arm side is turned on when the switching mode S _6a, the transistor Q4a is turned on when the switching mode S _3a, transistor Q5a is turned on when the switching mode S _5a. Looking at the low-arm side, the transistor Q3b is turned on when the switching mode S _3a, transistor Q4b is turned on when the switching mode S _5a, transistor Q5b is on when the switching mode S _6a.

Specifically, for example, switching of the switching mode such as the DC excitation period Tdc shown in FIG. 9B is performed. First, the charging of the bootstrap capacitor C3~C5 in switching mode S ₀ is performed, switching mode S _6a transistors Q3a, Do failure in any of Q5b does not occur is examined. Then again, in switching mode S ₀ with charging the bootstrap capacitor C3-C5, to attenuate the current flowing in the motor by refluxing operation. Then, in switching mode S _3a , it is checked whether any of the transistors Q4a and Q3b has a phase failure. Again, in switching mode S ₀ with charging the bootstrap capacitor C3-C5, to attenuate the current flowing in the motor by refluxing operation. And further switching mode S _5a in transistor Q5a, Do failure in any of Q4b it does not occur is examined.

  As for the procedure of the fault inspection, only the step of fault detection when energized in the third switching mode is added to the procedure described along the flowchart of FIG. 5 in the first embodiment. That is, steps similar to steps ST1 to ST3 are repeated for the third switching mode between step ST3 and step ST4 in FIG.

Next, differences between the first embodiment and the second embodiment regarding failure detection will be described with reference to FIG. Further, FIG. 10 shows a current waveform IW3 of a current flowing through the shunt resistor when a phase failure occurs. Further, FIG. 10 shows a current waveform IW4 when a short-circuit failure has occurred in the fan motor 22 or the inverter circuit 30. As can be seen from comparison with FIG. 6, the current waveform IW2 described in FIG. 6 is not described in FIG. This is because in any of the switching modes S _3a , S _5a , and S _6a , for example, if the transistor is open and does not conduct, the current path is cut off and no current flows. Therefore, in the motor control device 50 of the second embodiment, the threshold I _th3 for determining the presence or absence of a phase failure is the current waveform IW5 when there is no phase failure and the current waveform IW3 when there is a phase failure. It may be set in between, and can be set smaller than the threshold value I _th1 of the first embodiment. Alternatively, it can be determined by causing the current detection unit 52 to detect the presence or absence of a current flowing through the shunt resistor.

  Further, by using this current waveform IW5, the resistance values of the drive coils Lu, Lv, Lw of the fan motor 22 can be estimated. In the case of the second embodiment, series connection of two drive coils of the drive coils Lu and Lv, the drive coils Lu and Lw, and the drive coils Lv and Lw according to the first switching mode, the second switching mode, and the third switching mode. The resistance value can be estimated.

FIG. 11 shows a summary of the relationship between the above-described location of the phase failure and each switching mode. The upper part of FIG. 11 shows the correspondence between the type of arm and the phase failure. In the upper part of FIG. 11, ◯ indicates that no phase failure has occurred, and x indicates that a phase failure has occurred. For example, the first line in the upper stage of FIG. 11 describes whether or not a phase failure has occurred on the U-phase high arm side, that is, the transistor Q3a. The lower part of FIG. 11 shows the correspondence between the switching mode and the current detection. A circle in the lower part of FIG. 11 indicates that the current value detected by the current detection unit 52 exceeds the threshold value I _th3 . X in the lower part of FIG. 11 indicates that the current value was zero. In other words, ○ indicates that no phase failure has occurred (state of current waveform IW5), and x indicates that the current path is completely open (state of current waveform IW3) due to phase failure. ing.

Next, the overall view of FIG. 11 will be described. In the upper row of FIG. 11, there is no “x” and only “◯” is marked. That is, the first column in FIG. 11 indicates that no phase failure has occurred in the inverter circuit 30 and the fan motor 22. Accordingly, the first row in the lower part of FIG. In the second row in the upper stage of FIG. 11, “x” is marked only on the U-phase high arm side, indicating that a phase failure has occurred on the U-phase high arm side. In such a case, if the inverter circuit 30 is in the switching mode S _6a , the current waveform IW3 is generated, and therefore a phase failure has occurred, and the U-phase high arm side or the W-phase low arm Side is identified. The fact that it is not specified on the U-phase high arm side, as can be seen from the seventh column of FIG. 11, also when the open-phase fault has occurred on the W-phase low arm side, the inverter circuit 30 is switched to the switching mode S _6a. This is because the current waveform IW3 is generated.

(4) Features (4-1)
When the motor control device 50 is configured as in the second embodiment, for example, by a gate drive circuit 53 (an example of an inverter control unit) during direct current excitation (an example of a positioning operation) immediately after the fan motor 22 is started. A current (an example of a first current) that flows from the inverter circuit 30 to the current detector 52 in the switching mode S _6a (an example of the first switching mode), and a switching mode S _3a (an example of the second switching mode), for example. In addition to the current that flows from the inverter circuit 30 to the current detector 52 (an example of the second current), for example, the current that flows from the inverter circuit 30 in the switching mode S _5a (an example of the third switching mode) to the current detector 52 (the first current) Failure detection is performed by the failure detection unit 55a using an example of three currents.

  Therefore, the failure detection can be performed in parallel with the DC excitation rotor position fixing, and the startup time of the fan motor 22 is shortened compared to the case where the DC excitation rotor position fixing and the failure detection are sequentially performed. As described above, in the motor control device 50, it is possible to prevent the time required for steady operation of the fan motor 22 from becoming long due to detection of a phase failure or a short circuit failure.

In the second embodiment, all of the transistors Q3a~Q5b inverter circuit 30 (an example of the first switching element to sixth switching element) using a combination of switching mode S _3a and the switching mode S _5a and switching mode S _6a On the other hand, direct current is applied at least once in the on state. Although the location where the open phase failure occurs cannot be specified, it is possible to detect whether or not the open phase failure occurs for all the phases on the high arm side and the low arm side. As a result, even if the phase failure of all the transistors Q3a to Q5b of the inverter circuit 30 is detected, it is possible to suppress an increase in the time required until the fan motor 22 operates normally.

In the above embodiment, the switching mode S _3a , the switching mode S _5a, and the switching mode S _6a are used in order to supply all the transistors Q3a to Q5b of the inverter circuit 30 to the on state once and to supply the DC current. This combination is not limited to this. For example, a combination of switching mode S _1a , switching mode S _2a, and switching mode S _4a may be used.

(4-2)
In winding resistance estimating unit 55b, in each switching manner of switching mode S _3a and the switching mode S _5a and switching mode S _6a, based on the detection result of the voltage detector 51 and the current detection unit 52, the driving coil of the fan motor 22 The resistance values of Lu, Lv, and Lw (an example of winding resistance values) are estimated. If the winding resistance value estimated by the winding resistance estimation unit 55b deviates from a preset value, it can be estimated that some trouble has occurred in the drive coils Lu, Lv, and Lw.

(4-3)
As described above, in the failure detection unit 55a, the threshold value I _th3 shown in FIG. 10 is set in order to detect an open phase failure. In the above description, it is assumed that no current flows through the shunt resistor when a phase failure occurs in any of the transistors Q3a to Q5b. However, in detail, when a phase failure occurs, the current is biased in the reverse direction. Leakage current flows through the reflux diodes D3a to D5b. Normally, since the leakage current is extremely small, it can be ignored in setting the threshold value I _th3 , but when the threshold value I _th3 is to be set very small, the threshold value I _th3 is set to be larger than the largest leakage current. . In the inverter circuit 30 described above, when a phase failure occurs in any of the transistors Q3a to Q5b, a leakage current flows through the return diodes D3a to D5b in the path of the phase failure, but depending on the configuration of the inverter circuit, In some cases, the current flows through other paths such as the current at the time of charging the bootstrap capacitor described above. Even in such a case, the threshold I _th3 is larger than the largest current value among the currents flowing in the path of the phase failure. It is set large.

Note that the threshold value I _th3 is set to a value smaller than the smallest value among the current values when no phase failure has occurred, as in the case of the threshold value I _{th1 in} the first embodiment.

If configured as in the second embodiment, the change in current value can be increased when an open-phase failure has occurred and when no open-phase failure has occurred, so that the threshold I _{th1 of} the first embodiment can be increased. As can be seen from a comparison between the setting of the threshold _Ith3 of the second embodiment and the setting of the threshold I _th3 of the second embodiment, it is easy to detect the phase failure. In addition, if the threshold value is set in this way, for example, when the current value varies due to component variation and manufacturing variation, or the current value is different in the U phase, the V phase, and the W phase. It can respond even if it is.

(5) Modification (5-1) Modification 2A
In the second embodiment, the DC excitation when the fan motor 22 which is a brushless DC motor is driven by sensorless control has been described as an example. However, if the motor performs DC excitation, sensorless control is performed. It is not limited to a brushless DC motor. For example, the invention described in the above embodiment can be applied even in the case of direct current excitation of a brushless DC motor having two or less sensors for detecting the rotor position. Further, the motor is not limited to the brushless DC motor as long as the rotor position is fixed by DC excitation at the time of start-up, and can be applied to other types of motors. Further, the cost can be suppressed by setting the number of sensors to two or less.

(5-2) Modification 2B
In the second embodiment, the inverter circuit 30 configured using a bootstrap capacitor has been described as an example. However, the present invention can also be applied to an inverter circuit that does not use a bootstrap capacitor. In that case, it can be operated by omitting the switching mode S _0. Alternatively, it can be operated as a switching mode in which all transistors are turned off when DC excitation is not performed.

(5-3) Modification 2C
When direct current excitation is performed, the fixed position of the rotor varies depending on the switching mode. If it is known that the rotor position before DC excitation is within a predetermined range, such as by providing a rotor position detection sensor, the switching mode that can fix the rotor to a position close to that range is If the switching mode is selected, it is possible to reduce the amount of movement of the rotor when direct current excitation is performed. Therefore, the time until the current value is stabilized is shortened, and the fluctuation of the current can be reduced. .

  Also, the rotor fixing position by these switching modes is shifted by 120 degrees in electrical angle, but by making the movement direction of the fixing position the same direction as the rotation direction of the motor, it shifts to forcible driving and rotates operation. When starting, the rotation operation can be started smoothly.

(5-4) Modification 2D
In the second embodiment, the DC excitation in the switching mode in which one element of the one side arm and one element of the opposite side arm are energized is performed in three modes, and abnormality detection is performed in any of these modes to detect abnormalities in all elements. If the abnormality of all elements can be detected, the number of switching modes in which DC excitation is performed (position fixing) may be four or more. In that case, all of the switching modes are detected. It is not necessary to detect anomalies in a manner.

In the above embodiment, after the DC excitation / abnormality is detected in the switching mode _S6a , the DC excitation / abnormality is detected in the switching mode _S3a and then in the switching mode _S5a. since the shifted 120 degrees respectively at the corners, for example, it may be provided a switching mode of the switching mode S _2a during switching mode S _6a and switching mode S _3a, switching mode S _1a between the switching mode S _3a and the switching mode S _5a By providing direct current excitation (rotor position fixing) with the above switching mode, the rotor moving distance in one direct current excitation operation can be shortened. As a result, the time until the current value is stabilized during DC excitation is shortened and the fluctuation of the current can be reduced, so that the measurement standby time until the current detection (period T2 shown in FIG. 10) is reduced. It can be shortened. At this time, in the switching modes S _2a and S _1a , it is not necessary to perform abnormality detection.

(5-5) Modification 2E
In the first embodiment, DC excitation / abnormality detection is performed twice in a switching mode in which two elements of the one-side arm and one element of the opposite-side arm are energized. In the second embodiment, opposite to the two elements of the one-side arm. Although the DC excitation / abnormality detection is performed three times in the switching mode in which one element of the side arm is energized, the DC excitation / abnormality detection can be performed by combining the switching modes of the first and second embodiments. Of course, if it is possible to detect the abnormality of all the elements, it is not necessary to detect the abnormality in all the switching modes.

20 Outdoor fan 22 Fan motor 30 Inverter circuit 50 Motor controller 51 Voltage detection unit 52 Current detection unit 53 Gate drive circuit 55 Microcomputer 55a Failure detection unit 55b Winding resistance estimation unit Q3a, Q3b, Q4a, Q4b, Q5a, Q5b Transistor

JP 2002-136147 A

Claims (7)

A motor control device (50) for controlling the motor by controlling a switching operation of an inverter circuit (30) for driving the motor (22),
After the inverter circuit is set to the first switching mode and DC is energized during the positioning operation immediately after the start of the motor, the inverter circuit is further switched to the second switching mode different from the first switching mode during the positioning operation. An inverter control unit (53) configured to set DC
A current detector configured to detect a first current flowing in the inverter circuit in the first switching mode and a second current flowing in the inverter circuit in the second switching mode;
At least one of the first current and the second current detected by the current detection unit is used to detect a fault including at least one of an open-phase fault and a short-circuit fault related to the motor and the inverter circuit. A fault detection unit (55a),
A motor control device. The switching including the first switching mode and the second switching mode in which the inverter control unit performs direct current energization at least once for all switching elements of the inverter circuit during a positioning operation immediately after startup. Configured to switch modes,
The current detection unit is configured to detect a current including the first current and the second current that flows when the inverter circuit is DC-directed in a switching mode in which the inverter control unit is switched during the positioning operation. ,
The failure detection unit is configured to perform the failure detection using a current detected by the current detection unit with respect to a switching mode that the inverter control unit switches during the positioning operation.
The motor control device according to claim 1. The inverter circuit includes a first switching element, a second switching element, and a third switching element on the upper arm, and includes a fourth switching element, a fifth switching element, and a sixth switching element on the lower arm,
The inverter control unit turns on the first switching element, the fourth switching element, and the fifth switching element in the first switching mode or the second switching mode, and the second switching mode or the first switching mode. The second switching element, the third switching element, and the sixth switching element are turned on in an aspect,
The failure detection unit includes the first current when the phase failure has occurred in one of the fourth switching element and the fifth switching element, and the phase failure has not occurred in the first switching element. The second current or the second current or the second current when one of the second switching element and the third switching element has a phase failure, and the sixth switching element has no phase failure. A phase failure is detected between the larger value of one current and the smaller value of the first current and the second current when no phase failure has occurred in the inverter circuit. A threshold is set for
The motor control device according to claim 2. The inverter circuit includes a first switching element, a second switching element, and a third switching element on the upper arm, and includes a fourth switching element, a fifth switching element, and a sixth switching element on the lower arm,
The inverter control unit turns on the first switching element and the fourth switching element in the first switching mode, turns on the second switching element and the fifth switching device in the second switching mode, Configured to turn on the third switching element and the sixth switching element in a third switching mode;
The current detection unit is configured to detect a third current flowing through the inverter circuit in the third switching mode in addition to the first current and the second current.
The motor control device according to claim 2. The failure detection unit includes the first current, the second current, and the first current that flow through a path of a phase failure when any phase failure occurs in any of the first switching element to the sixth switching element. The largest value of the three currents, and the first current, the second current, and the third current when no phase failure has occurred in any of the first to sixth switching elements. A threshold for detecting an open phase fault is set up to the smallest value of
The motor control device according to claim 4. A winding resistance estimation unit (55b) for estimating a winding resistance value of the motor using at least the first current and the second current detected by the current detection unit;
The motor control device according to any one of claims 1 to 5. The motor is a brushless DC motor having two or less sensors.
The motor control apparatus as described in any one of Claim 1 to 6.

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