JP2012228164A - Motor drive device, and heat pump device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor drive device capable of grasping the rotating speed of a motor before it starts without being subject to influences in DC bus GND potential fluctuations and common mode potential fluctuations.SOLUTION: In a motor drive device 20, a rotating speed estimation part 28 estimates the rotating speed of a fan motor 51 from a value detected by an inter-winding voltage detection part 27 before the fan motor 51 starts. When a microcomputer 30 determines that an estimated rotating speed of the fan motor 51 before the fan motor 51 starts is less than a predetermined rotating speed, drive voltage is outputted to the fan motor 51. When the microcomputer 30 determines that the estimated rotating speed of the fan motor 51 before the fan motor 51 starts is a predetermined rotating speed or more, the drive voltage is not outputted to the fan motor 51.

Description

  The present invention relates to a motor drive device.

  The outdoor unit of the heat pump device is equipped with an outdoor fan, and an outdoor heat exchanger that performs heat exchange between the refrigerant and the air by blowing from the outdoor fan.As a driving source of the outdoor fan, for example, Brushless DC motors are widely adopted.

  In the outdoor unit as described above, the outdoor fan may be already rotating due to the influence of wind or the like before the motor is started. In such a case, air is sent to the outdoor heat exchanger. May not be driven. Therefore, it is desirable to know the number of rotations of the motor before startup.

  For example, Patent Document 1 (Japanese Patent Laid-Open No. 7-337080) discloses a method for grasping the rotational speed of the motor before startup.

  According to Patent Document 1, the rotational speed of the fan before startup is estimated based on the induced voltage generated by the rotation of the motor composed of a plurality of phases, that is, the terminal voltage.

  However, the method of estimating the rotation speed of the fan from the voltage between the motor terminals is easily affected by the GND potential fluctuation and the common mode potential fluctuation, and it is difficult to stably detect the voltage.

  The subject of this invention is providing the motor drive device which can grasp | ascertain the rotation speed of the motor before starting, without being influenced by DC bus GND electric potential fluctuation | variation and common mode electric potential fluctuation | variation.

  A motor drive device according to a first aspect of the present invention is a motor drive device that drives and stops a motor by controlling an output voltage to the motor, and includes a winding voltage detection unit and a control unit. Yes. The inter-winding voltage detection unit detects a voltage between the windings of the motor. The controller determines whether or not to output a drive voltage to the motor based on the detection value by the inter-winding voltage detector before starting the motor.

  In this motor drive device, the interwinding voltage detection unit is not connected to the DC bus GND, so that it is not affected by the DC bus GND potential fluctuations and is not affected by the common mode potential fluctuations. Therefore, stable voltage detection is performed.

  A motor drive device according to a second aspect of the present invention is the motor drive device according to the first aspect, further comprising a rotation speed estimation unit. The rotational speed estimation unit estimates the rotational speed of the motor from the value detected by the inter-winding voltage detection unit before starting the motor. When the estimated rotational speed of the motor before startup estimated by the rotational speed estimation unit is less than the predetermined rotational speed, a drive voltage is output to the motor, and the estimated rotational speed of the motor before startup estimated by the rotational speed estimation unit is the predetermined rotational speed. When the number is more than the number, the drive voltage is not output to the motor.

  For example, when this motor drive device is applied to a motor of an outdoor fan that blows air to an outdoor heat exchanger of a heat pump device, the rotation speed is predetermined in a state where the motor before starting is already rotating due to the influence of wind or the like. If it is more than the number of rotations, sufficient air has already been sent to the outdoor heat exchanger, so that the function as a heat exchanger can be sufficiently obtained. Therefore, the motor drive device does not start the motor. Conversely, if the rotational speed is less than the predetermined rotational speed, even if the motor is rotating, the motor drive device starts the motor because the amount of air sent to the outdoor heat exchanger is insufficient. Let As described above, since the start of the motor is controlled in accordance with the rotational speed of the motor before the start, the amount of power consumed by the start / operation of the motor can be minimized.

  A motor drive device according to a third aspect of the present invention is the motor drive device according to the first aspect or the second aspect, wherein the inter-winding voltage detection unit divides the voltage between the windings of the motor and rotates. Output to the estimation unit.

  In this motor drive device, stable voltage detection is performed, and the voltage between the windings is divided and output to the rotation speed estimation unit, so that the component rating on the rotation speed estimation unit side can be reduced. The size, size, and cost can be reduced.

  A motor driving device according to a fourth aspect of the present invention is the motor driving device according to the third aspect, wherein the rotation speed estimation unit outputs a first signal when the estimated rotation speed is equal to or greater than a predetermined value, and the estimated rotation When the number is less than a predetermined value, a second signal different from the first signal is output. The rotation speed estimation unit electrically insulates the first signal and the second signal from the inter-winding voltage detection unit and outputs them to the control unit.

  In this motor drive device, stable voltage detection is performed, and the first signal and the second signal are electrically insulated and output, so that noise resistance is also improved.

  A motor driving device according to a fifth aspect of the present invention is the motor driving device according to the third aspect, in which the rotation speed estimation unit outputs an output voltage corresponding to the estimated rotation speed to the inter-winding voltage detection unit. Electrically insulated and output to the control unit.

  In this motor drive device, stable voltage detection is performed, and an output voltage corresponding to the estimated rotational speed is output after being electrically insulated, so noise resistance is also improved.

  A motor drive device according to a sixth aspect of the present invention is the motor drive device according to the fifth aspect, wherein the control unit includes a determination unit that determines whether or not the estimated rotational speed is equal to or higher than a predetermined rotational speed. .

  In this motor drive device, stable voltage detection is performed, and it is possible to reliably determine whether the rotation speed of the motor before startup is equal to or higher than the rotation speed to be started, and the startup of the motor is controlled accordingly. Therefore, the amount of power consumed by starting the motor can be minimized.

  A motor driving device according to a seventh aspect of the present invention is the motor driving device according to the first or second aspect, wherein the interwinding voltage detection unit and the rotation speed estimation unit are insulated by an insulating transformer. . The rotation speed estimation unit estimates the rotation speed of the motor from the output voltage of the insulation transformer.

  In this motor drive device, stable voltage detection is performed and insulation is further improved because the motor drive device is insulated by an insulation transformer.

  A motor drive device according to an eighth aspect of the present invention is the motor drive device according to the seventh aspect, in which the rotation speed estimation unit has a first signal when the estimated rotation speed is equal to or greater than a predetermined value, and the estimated rotation speed is predetermined. When the value is less than the value, a second signal different from the first signal is output to the control unit.

  In this motor drive device, stable voltage detection is performed and insulation is further improved because the motor drive device is insulated by an insulation transformer.

  A motor drive device according to a ninth aspect of the present invention is the motor drive device according to the seventh aspect, in which the rotation speed estimation unit outputs an output voltage corresponding to the estimated rotation speed to the control unit.

  In this motor drive device, stable voltage detection is performed and insulation is further improved because the motor drive device is insulated by an insulation transformer.

  A motor drive device according to a tenth aspect of the present invention is the motor drive device according to the ninth aspect, wherein the control unit includes a determination unit that determines whether or not the estimated rotation number is equal to or greater than a predetermined rotation number. .

  In this motor drive device, stable voltage detection is performed, and it is possible to reliably determine whether the rotation speed of the motor before startup is equal to or higher than the rotation speed to be started, and the startup of the motor is controlled accordingly. Therefore, the amount of power consumed by starting the motor can be minimized.

  A motor drive device according to an eleventh aspect of the present invention is the motor drive device according to the first or second aspect, wherein the interwinding voltage detection unit rectifies the voltage between the windings of the motor to rotate the motor speed. Output to the estimation unit.

  In this motor drive device, stable voltage detection is performed, and it is more stable as a signal to detect the rectified voltage than to obtain the rotation speed from an AC voltage whose voltage fluctuates every cycle.

  A motor drive device according to a twelfth aspect of the present invention is the motor drive device according to the eleventh aspect, wherein the rotational speed estimation unit outputs a first signal when the estimated rotational speed is equal to or greater than a predetermined value, and the estimated rotational speed When the number is less than a predetermined value, a second signal different from the first signal is output. The rotation speed estimation unit electrically insulates the first signal and the second signal from the inter-winding voltage detection unit and outputs them to the control unit.

  In this motor drive device, stable voltage detection is performed, and the first signal and the second signal are electrically insulated and output, so that noise resistance is also improved.

  A motor drive device according to a thirteenth aspect of the present invention is the motor drive device according to the eleventh aspect, in which the rotation speed estimation unit outputs an output voltage corresponding to the estimated rotation speed to the inter-winding voltage detection unit. Electrically insulated and output to the control unit.

  In this motor drive device, stable voltage detection is performed, and an output voltage corresponding to the estimated rotational speed is output after being electrically insulated, so noise resistance is also improved.

  A motor drive device according to a fourteenth aspect of the present invention is the motor drive device according to the thirteenth aspect, wherein the control unit includes a determination unit that determines whether or not the estimated rotation number is equal to or greater than a predetermined rotation number. .

  In this motor drive device, stable voltage detection is performed, and it is possible to reliably determine whether the rotation speed of the motor before startup is equal to or higher than the rotation speed to be started, and the startup of the motor is controlled accordingly. Therefore, the amount of power consumed by starting the motor can be minimized.

  A motor drive device according to a fifteenth aspect of the present invention is the motor drive device according to any one of the first to fourteenth aspects, wherein the motor is a brushless DC fan motor.

  In this motor drive device, the rotation speed before starting the brushless DC fan motor is easily estimated.

  A motor drive device according to a sixteenth aspect of the present invention is the motor drive device according to the fifteenth aspect, wherein the motor is driven without a rotor position sensor after starting.

  In this motor drive device, since the motor rotation speed before startup is correctly detected, the startup operation can be performed smoothly, and the rotor position sensorless drive after startup is performed normally.

  A motor drive device according to a seventeenth aspect of the present invention is the motor drive device according to any one of the first to sixteenth aspects, further comprising an inverter, a bootstrap circuit, and a drive circuit. . The inverter is formed of an upper arm side switching element and a lower arm side switching element. The bootstrap circuit generates a higher potential than the low potential side of the upper arm side switching element. The drive circuit takes in a higher potential from the bootstrap circuit to turn on and off the upper arm side switching element.

  For example, in the method of estimating the rotational speed of the fan by detecting the voltage between the motor terminals as in Patent Document 1, even when the rotational speed is 0, a current flows to the bootstrap circuit via the circuit that detects the terminal voltage. Since the motor terminal voltage is generated, the rotation speed may not be detected accurately.

  On the other hand, in this motor drive device, since the interwinding voltage detector is not connected to the DC bus GND, it is not affected by the bootstrap circuit.

  A heat pump device according to an eighteenth aspect of the present invention includes a fan, a fan motor that rotates the fan, and a motor driving device according to any one of the first to sixteenth aspects that drives the fan motor. .

  In this heat pump device, since the interwinding voltage detection unit of the motor drive device is not connected to the DC bus GND, stable voltage detection is performed without being affected by the potential fluctuation of the DC bus GND. Therefore, the rotation speed of the fan motor can be estimated more accurately.

  A heat pump device according to a nineteenth aspect of the present invention is the heat pump device according to the eighteenth aspect, wherein the motor drive device further includes a first inverter and a second inverter. The first inverter converts the DC voltage supplied from the DC power supply unit into a driving voltage for driving the fan motor and outputs the driving voltage to the fan motor. The second inverter is connected to the DC power supply unit in parallel with the first inverter, and drives a load different from the fan motor.

  For example, when the first inverter for driving the fan motor and the second inverter for driving the compressor motor share the GND potential, the GND potential varies depending on the operation of the compressor motor driving inverter. Although there is a concern about the influence on the detection, in this heat pump device, since it is estimated from the voltage between the windings of the fan motor, the rotation speed is estimated without being affected by the GND potential fluctuation.

  In the motor drive device according to the first aspect of the present invention, the interwinding voltage detection unit is not connected to the DC bus GND, so that it is not affected by the DC bus GND potential fluctuation, and is not affected by the common mode potential fluctuation. . Therefore, stable voltage detection is performed.

  In the motor drive device according to the second aspect of the present invention, the motor start-up execution is controlled in accordance with the number of rotations of the motor before start-up, so that the amount of power consumed by motor start-up and operation can be minimized. it can.

  In the motor drive device according to the third aspect of the present invention, stable voltage detection is performed and the voltage between the windings is divided and output to the rotation speed estimation unit. The size can be reduced, and accordingly, downsizing and cost reduction can be achieved.

  In the motor drive device according to the fourth aspect of the present invention, stable voltage detection is performed, and the first signal and the second signal are electrically insulated and output, so that noise resistance is also improved.

  In the motor drive device according to the fifth aspect of the present invention, stable voltage detection is performed, and an output voltage corresponding to the estimated rotational speed is electrically insulated and output, so noise resistance is also improved.

  In the motor drive device according to the sixth aspect of the present invention, the amount of power consumed by starting the motor can be minimized.

  In the motor drive device according to the seventh aspect to the ninth aspect of the present invention, stable voltage detection is performed and the insulation is further improved since the insulation is performed by the insulation transformer.

  In the motor drive device according to the tenth aspect of the present invention, the amount of power consumed by starting the motor can be minimized.

  In the motor drive device according to the eleventh aspect of the present invention, stable voltage detection is performed, and it is better to detect the voltage after rectification than to obtain the rotation speed from an AC voltage whose voltage fluctuates every cycle. The signal is stable.

  In the motor drive device according to the twelfth aspect of the present invention, stable voltage detection is performed, and since the first signal and the second signal are output after being electrically insulated, noise resistance is also improved.

  In the motor drive device according to the thirteenth aspect of the present invention, stable voltage detection is performed, and an output voltage corresponding to the estimated rotational speed is electrically insulated and output, so noise resistance is also improved.

  In the motor drive device according to the fourteenth aspect of the present invention, the amount of power consumed by starting the motor can be minimized.

  In the motor drive device according to the fifteenth aspect of the present invention, the rotation speed before the start of the brushless DC fan motor is easily estimated.

  In the motor drive device according to the sixteenth aspect of the present invention, the motor after startup is normally driven by the rotor position sensorless.

  In the motor drive device according to the seventeenth aspect of the present invention, the interwinding voltage detector is not connected to the DC bus GND, and therefore is not affected by the bootstrap circuit.

  In the heat pump device according to the eighteenth aspect of the present invention, the motor driving device is not affected by the potential fluctuation of the DC bus GND, and the rotational speed of the fan motor is estimated more accurately.

  In the heat pump device according to the nineteenth aspect of the present invention, since the rotation speed is estimated from the voltage between the windings of the fan motor, the rotational speed is estimated without being affected by the GND potential fluctuation.

1 is a block diagram illustrating an overall configuration of a system in which a motor drive device according to an embodiment of the present invention is employed and an internal configuration of the motor drive device. The block diagram of the outdoor unit of a heat pump apparatus. The circuit diagram of the voltage detection part between windings, and a rotation speed estimation part. The conceptual diagram showing the relationship between the rotation speed of the fan motor before starting, and the voltage between windings. The block diagram of the sensorless control circuit as an example. The flowchart which shows the operation | movement which a motor drive device performs. The flowchart which shows the operation | movement which a motor drive device performs. The circuit diagram of the voltage detection part between windings which concerns on a 1st modification, and a rotation speed estimation part. The circuit diagram of the voltage detection part between windings which concerns on a 2nd modification, and a rotation speed estimation part. The circuit diagram of the voltage detection part between windings which concerns on a 3rd modification, and a rotation speed estimation part. The circuit diagram of the voltage detection part between windings which concerns on a 4th modification, and a rotation speed estimation part. The circuit diagram of the voltage detection part between windings which concerns on a 5th modification, and a rotation speed estimation part. The block diagram which shows the whole structure of the system by which the motor drive device which concerns on a 6th modification is employ | adopted, and the internal structure of a motor drive device. The block diagram showing the function part in the drive IC by the side of the fan motor concerning a 6th modification. The block diagram showing the function part in the drive IC by the side of the compressor motor which concerns on a 6th modification. The circuit diagram of the principal part of the motor drive device which concerns on a 7th modification.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following embodiments are specific examples of the present invention and do not limit the technical scope of the present invention.

(1) Overview FIG. 1 is a block diagram showing an overall configuration of a system 100 in which a motor drive device according to an embodiment of the present invention is employed and an internal configuration of a motor drive device 20. In FIG. 1, a fan motor 51 is a brushless DC motor for driving an outdoor fan 15 mounted on the outdoor unit 10 (see FIG. 2) of the heat pump device. The motor drive device 20 is also mounted in the outdoor unit 10.

(1-1) Outdoor unit 10
FIG. 2 is a configuration diagram of the outdoor unit 10 of the heat pump apparatus. In FIG. 2, the outdoor unit 10 is an outdoor unit of a heat pump type water heater, and includes a compressor 11, a water heat exchanger 12, an expansion valve 13, an evaporator 14, and an outdoor fan 15. The compressor 11, the water heat exchanger 12, the expansion valve 13, and the evaporator 14 are sequentially connected to constitute a refrigeration cycle.

  The compressor 11 compresses the refrigerant circulating in the refrigeration cycle. The water heat exchanger 12 is provided with a heat exchange channel 16 through which water supplied from the outside of the outdoor unit 10 passes, and heat is exchanged between the water flowing in the heat exchange channel 16 and the refrigerant. The expansion valve 13 is an electrically controlled valve that depressurizes the refrigerant circulating in the refrigeration cycle. The evaporator 14 performs heat exchange between the refrigerant in the refrigerant cycle and the air, and evaporates the refrigerant. The outdoor fan 15 is a propeller fan, and guides air from the outside of the outdoor unit 10 to the evaporator 14 by rotation.

  In the outdoor unit 10, when the compressor 11 is driven and the refrigerant circulates, the water heat exchanger 12 functions as a condenser, and water passing through the heat exchange water channel 16 is heated.

(1-2) Fan motor 51
The fan motor 51 is a three-phase brushless DC motor, and includes a stator 52 and a rotor 53. The stator 52 includes U-phase, V-phase, and W-phase drive coils Lu, Lv, and Lw that are star-connected. One ends of the drive coils Lu, Lv, and Lw are connected to drive coil terminals TU, TV, and TW of U-phase, V-phase, and W-phase wirings extending from the inverter 25, 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 53 as the rotor 53 rotates.

  The rotor 53 includes a plurality of permanent magnets including N poles and S poles, and rotates about the rotation axis with respect to the stator 52. The rotation of the rotor 53 is output to the outdoor fan 15 via an output shaft (not shown) that is on the same axis as the rotation shaft.

(2) Configuration of Motor Drive Device 20 As shown in FIG. 1, the motor drive device 20 includes a DC power supply unit configured by a commercial power supply 91, a rectifying unit 21, and a smoothing capacitor 22, a voltage detection unit 23, and a current. The detector 24, the inverter 25, the gate drive circuit 26, the interwinding voltage detector 27, the rotation speed estimator 28, the sensorless control circuit 29, and the microcomputer 30 are provided. These are mounted on, for example, one printed board.

(2-1) Rectifier 21
The rectifying unit 21 is configured in a bridge shape by four diodes D1a, D1b, D2a, and D2b. Specifically, the diodes D1a and D1b and D2a and D2b are respectively connected in series. The cathode terminals of the diodes D1a and D2a are both connected to the plus side terminal of the smoothing capacitor 22 and function as the positive side output terminal of the rectifying unit 21. The anode terminals of the diodes D1b and D2b are both connected to the negative side terminal of the smoothing capacitor 22 and function as the negative side output terminal of the rectifying unit 21.

  A connection point between the diode D1a and the diode D1b is connected to one pole of the commercial power supply 91. A connection point between the diode D2a and the diode D2b is connected to the other pole of the commercial power supply 91. The rectifying unit 21 rectifies the AC voltage output from the commercial power supply 91 to generate a DC power supply, and supplies this to the smoothing capacitor 22.

(2-2) Smoothing capacitor 22
The smoothing capacitor 22 has one end connected to the positive output terminal of the rectifying unit 21 and the other end connected to the negative output terminal of the rectifying unit 21. The smoothing capacitor 22 smoothes the voltage rectified by the rectifying unit 21. Hereinafter, for the convenience of explanation, the voltage after smoothing by the smoothing capacitor 22 is referred to as “smoothed voltage Vfl”.

  The smoothed voltage Vfl is applied to the inverter 25 connected to the output side of the smoothing capacitor 22. In other words, the commercial power supply 91, the rectifying unit 21, and the smoothing capacitor 22 constitute a DC power supply unit for the inverter 25.

  In addition, as a kind of capacitor | condenser, although an electrolytic capacitor, a ceramic capacitor, a tantalum capacitor etc. are mentioned, an electrolytic capacitor is employ | adopted as the smoothing capacitor 22 in this embodiment.

(2-3) Voltage detection unit 23
The voltage detector 23 is connected to the output side of the smoothing capacitor 22 and detects the voltage across the smoothing capacitor 22, that is, the value of the smoothed voltage Vfl. The voltage detector 23 is configured, for example, such that two resistors connected in series with each other are connected in parallel to the smoothing capacitor 22 and the smoothed voltage Vfl is divided. The voltage value at the connection point between the two resistors is input to the sensorless control circuit 29.

(2-4) Current detection unit 24
The current detection unit 24 is connected between the smoothing capacitor 22 and the inverter 25 and connected to the negative output terminal side of the smoothing capacitor 22. The current detection unit 24 detects the motor current Im flowing through the fan motor 51 after the fan motor 51 is started.

  The current detection unit 24 may be configured by, for example, an amplifier circuit using a shunt resistor and an operational amplifier that amplifies the voltage across the resistor. The motor current detected by the current detection unit 24 is input to the sensorless control circuit 29.

(2-5) Inverter 25
The inverter 25 is connected to the output side of the smoothing capacitor 22. In FIG. 1, an inverter 25 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. including.

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

  The inverter 25 is applied with the smoothed voltage Vfl from the smoothing capacitor 22, and the transistors Q3a to Q5b are turned on and off at the timing instructed by the gate drive circuit 26, thereby driving the fan motor 51. SU, SV, SW are generated. The drive voltages SU, SV, SW are output to the fan motor 51 from the connection points NU, NV, NW of the transistors Q3a and Q3b, Q4a and Q4b, and Q5a and Q5b.

  The inverter 25 activates the fan motor 51 or cancels the activation in accordance with a signal from the rotation speed estimation unit 28 that indicates what the rotation speed of the fan motor 51 before activation is.

  Specifically, when the start signal acquired from the rotation speed estimation unit 28 indicates that the rotation speed of the fan motor 51 before the start is less than a predetermined rotation speed, the inverter 25 is driven by the drive voltages SU, SV, SW. Is output to the fan motor 51. As a result, the fan motor 51 starts.

  However, when the signal indicates that the rotational speed of the fan motor 51 before activation is equal to or higher than the predetermined rotational speed, the inverter 25 does not output the drive voltages SU, SV, SW to the fan motor 51. As a result, the fan motor 51 remains in a state where it is not activated.

  If the outdoor fan 15 is affected by wind or the like and the fan motor 51 is already rotating at a sufficient number of revolutions before the start-up, the rotation of the outdoor fan 15 causes the evaporator 14 to rotate. It is assumed that sufficient air is being sent. In such a case, since the function as the evaporator 14 of the heat pump device is not impaired, the inverter 25 does not have to output the drive signals SU, SV, SW to the fan motor 51.

  On the other hand, if the rotation speed of the fan motor 51 before startup is not sufficient (including the case where the fan motor 51 before startup is not rotating), sufficient air is not sent to the evaporator 14. . In this case, since the evaporator 14 may not function sufficiently, the inverter 25 outputs the drive signals SU, SV, SW to the fan motor 51 to start the fan motor 51.

(2-6) Gate drive circuit 26
The gate drive circuit 26 changes the on and off states of the transistors Q3a to Q5b of the inverter 25 based on the start command Vpwm from the sensorless control circuit 29. Specifically, the gate drive circuit 26 is configured so that the drive voltages SU, SV, SW having the duty determined by the sensorless control circuit 29 are output from the inverter 25 to the fan motor 51, so that the gates of the transistors Q3a to Q5b. The gate control voltages Gu, Gx, Gv, Gy, Gw, and Gz to be applied to are generated. The generated gate control voltages Gu, Gx, Gv, Gy, Gw, Gz are applied to the gate terminals of the respective transistors Q3a to Q5b.

(2-7) Interwinding voltage detector 27
The interwinding voltage detection unit 27 has two input terminals connected to the U-phase drive coil terminal TU and the V-phase drive coil terminal TV of the fan motor 51, and an output connected to the rotation speed estimation unit 28. Yes. The inter-winding voltage detection unit 27 is located on the rear stage side of the inverter 25, and detects the induced voltage Vuv (see FIG. 3) generated from the fan motor 51 when the fan motor 51 is rotating before starting. .

  An example of the configuration of the inter-winding voltage detection unit 27 will be described with reference to the drawings. FIG. 3 is a circuit diagram of the inter-winding voltage detection unit 27 and the rotation speed estimation unit 28. In FIG. 3, a first resistor R1 and a second resistor R2 are connected in series to an input line from the V-phase drive coil terminal TV of the fan motor 51.

  When the resistance values of the first resistor R1 and the second resistor R2 are r1 and r2, respectively, [r1 · Vuv / (r1 + r2)], [r2 · Vuv are provided at both ends of the first resistor R1 and the second resistor R2. / (R1 + r2)] is generated, and one of the two voltages is input to the rotation speed estimation unit 28.

(2-8) Revolution number estimation unit 28
The rotation speed estimation unit 28 is connected to the output terminal of the interwinding voltage detection unit 27 and the input terminal of the microcomputer 30. The rotation speed estimation unit 28 is a circuit that estimates the rotation speed of the fan motor 51 before startup based on the detection result of the inter-winding voltage detection unit 27.

  In the state before the start of the fan motor 51, the inverter is not operating and an induced voltage is generated in the fan motor 51 rotating due to the influence of wind or the like. Is a value that directly represents the rotational speed of the fan motor 51.

  FIG. 4 is a conceptual diagram showing the relationship between the rotational speed of the fan motor before starting and the voltage between windings (for example, effective value, average value, peak value). In FIG. 4, the inter-winding voltage is substantially proportional to the rotational speed, and the inter-winding voltage increases as the rotational speed of the fan motor 51 before startup increases. The rotation speed estimation unit 28 grasps in advance the relationship between the magnitude of the interwinding voltage and the rotation speed of the fan motor 51 before starting, so that the fan motor 51 before starting is determined from the magnitude of the winding voltage. The rotational speed can be estimated.

  As shown in FIG. 3, the rotation speed estimation unit 28 includes a Zener diode ZD1, a photocoupler 280, and a third resistor R3. The photocoupler 280 has a first terminal T1, a second terminal T2, a third terminal T3, and a fourth terminal T4.

  In the rotation speed estimation unit 28, the connection point C1 between the first resistor R1 and the second resistor R2 of the interwinding voltage detection unit 27 is connected to the first terminal T1 of the photocoupler 280 via the Zener diode ZD1. Specifically, the cathode of the Zener diode ZD1 is connected to the connection point C1, and the anode is connected to the first terminal T1. The input line from the low potential side of the second resistor R2 and the U-phase drive coil terminal TU is connected to the second terminal T2 of the photocoupler 280.

  The third terminal T3 is connected to the control power supply Vc side, and the fourth terminal T4 is connected to the GND side via the third resistor R3. Further, the high potential side of the third resistor R3 is connected to the input terminal P1 of the microcomputer 30.

  The photocoupler 280 includes a phototransistor 281 and a light emitting diode 282. The collector of the phototransistor 281 communicates with the third terminal T3, and the emitter of the phototransistor 281 communicates with the fourth terminal T4.

  The anode of the light emitting diode 282 communicates with the first terminal T1, and the cathode of the light emitting diode 282 communicates with the second terminal T2.

  For example, when the fan motor 51 rotates by natural wind, an induced electromotive voltage Vuv is generated between the U-phase drive coil terminal TU and the V-phase drive coil terminal TV of the fan motor 51. When the voltage at the connection point C1 at this time exceeds the Zener voltage of the Zener diode ZD1, the light emitting diode 282 emits light and the phototransistor 281 conducts, and the High signal as the first signal is supplied to the input terminal P1 of the microcomputer 30. Is entered.

  Conversely, when the voltage at the connection point C1 is lower than the Zener voltage of the Zener diode ZD1, the light emitting diode 282 does not emit light, so that the phototransistor 281 does not conduct and the potential of the input terminal P1 of the microcomputer 30 is 0. . This state is the same as the input of the second signal (here, the Low signal) having a potential low enough to be distinguished from the first signal.

  Therefore, the resistance value of the first resistor R1 and the second resistor R2 or the value of the Zener diode ZD1 is set so that the rotational speed of the fan motor 51 when the voltage at the connection point C1 exceeds the Zener voltage of the Zener diode ZD1 is a predetermined rotational speed. By selecting the Zener voltage, when the first signal is input to the input terminal P1 of the microcomputer 30, it can be estimated that the rotational speed of the fan motor 51 is equal to or higher than the predetermined rotational speed. Conversely, when the second signal (Low signal) is input to the input terminal P1 of the microcomputer 30, it can be estimated that the rotational speed of the fan motor 51 is less than the predetermined rotational speed.

  As shown in FIG. 4, the relationship between the magnitude of the interwinding voltage and the rotational speed of the fan motor 51 before startup is based on the characteristics of the fan motor 51, the capacity of the smoothing capacitor 22, etc. It has been guided in advance by experiments.

  Since Vuv is an alternating voltage whose instantaneous value changes with time, the first signal input to the input terminal P1 is a pulse signal.

(2-9) Sensorless control circuit 29
The sensorless control circuit 29 is connected to the inter-winding voltage detection unit 27, the voltage detection unit 23, the current detection unit 24, the gate drive circuit 26, and the microcomputer 30. The sensorless control circuit 29 is a circuit that drives the fan motor 51 in a rotor position sensorless system based on an operation command including the rotation speed command Vfg sent from the microcomputer 30.

  The rotor position sensorless system refers to various parameters indicating the characteristics of the fan motor 51, the detection result of the interwinding voltage detection unit 27 after the start of the fan motor 51, the result of the voltage detection unit 23, the result of the current detection unit 24, and the fan This is a method of performing estimation of the rotor position and the rotational speed, PI control for the rotational speed, PI control for the motor current, and the like using a predetermined mathematical model related to the control of the motor 51. Examples of various parameters indicating the characteristics of the fan motor 51 include the winding resistance, inductance component, induced voltage, and number of poles of the fan motor 51 used.

  FIG. 5 is a configuration diagram of a sensorless control circuit as an example. In FIG. 5, the sensorless control circuit 29 is mainly configured by a motor model calculation unit 29a, a rotor position estimation unit 29b, an operation rotation number estimation unit 29c, an LPF 29d, a rotation number control unit 29e, and a current control unit 29f.

  The motor model calculation unit 29a calculates the ideal value of the motor current from the command voltage to the motor 51, the estimated rotor position, and the estimated rotation speed, using various parameters indicating the characteristics of the fan motor 51 as a motor model.

  The rotor position estimator 29b estimates the current rotor position using the result obtained by subtracting the ideal value from the motor current Im actually detected by the current detector 24 as an input.

  The operating rotational speed estimation unit 29c estimates the current rotational speed of the fan motor 51 using the estimated rotor position. The estimation results in the respective estimation units 29b and 29c are corrected so that the difference between the ideal value of the motor current and the actual motor current Im is “0”, and the motor model is corrected. The LPF 29d removes noise components and harmonic components from the estimated rotation speed. The rotation speed of the fan motor 51 output from the LPF 29d becomes a desired rotation speed signal FG by the waveform shaping section 29g and is output to the microcomputer 30.

  The rotation speed of the fan motor 51 output from the LPF 29d is subtracted from the rotation speed command Vfg included in the operation command sent from the microcomputer 30. When the result of the subtraction process is input, the rotation speed control unit 29e performs PI control on the rotation speed. The current control unit 29f includes a d-axis torque current command Id * that is a control result of the rotation speed control unit 29e, a command “Iq * = 0” such that the q-axis current command Iq is “0”, a winding Current control is performed based on the voltage detected by the inter-voltage detection unit 27, and a command voltage Vpwm is generated so as to be a current based on these commands. By such control of the current control unit 29f, the command voltage Vpwm including the duty of the drive voltages SU, SV, SW is generated and input to the gate drive circuit 26. The command voltage Vpwm is input to the motor model calculation unit 29a, and further correction of the motor model is performed.

  It can be said that the sensorless control circuit 29 having such a configuration estimates the rotor position only when the inverter 25 is controlled by the microcomputer 30 and the gate drive circuit 26. When the inverter 25 is being controlled, the fan motor 51 is started by a start command and is being driven.

  In other words, the sensorless control circuit 29 cannot estimate the rotational speed of the fan motor 51 before the fan motor 51 is started. This is because, as described above, in the rotor position sensorless system, the estimated rotor position is used for estimating the rotation speed, and therefore the rotor position cannot be estimated in the fan motor 51 before starting.

(2-10) Microcomputer 30
The microcomputer 30 is connected to the rotation speed estimation unit 28 and the sensorless control circuit 29. The microcomputer 30 is also connected to an outdoor unit side control unit that controls each device of the outdoor unit 10 in an integrated manner, and drives the fan motor 51 according to whether there is an abnormality in each device. Control. Therefore, the microcomputer 30 functions as the determination unit 30a.

  The microcomputer 30 is always supplied with power different from that of the inverter 25 regardless of the driving state of the fan motor 51.

  The determination unit 30a compares the rotational speed of the fan motor 51 before startup estimated by the rotational speed estimation unit 28 with a predetermined rotational speed, and determines whether the rotational speed of the fan motor 51 before startup is equal to or higher than the predetermined rotational speed. to decide.

  If the rotation speed of the fan motor 51 before the start is greater than or equal to the predetermined rotation speed, the fan motor 51 has already been rotated at a sufficient rotation speed due to the influence of wind or the like. Since sufficient air is being sent to and sufficient heat exchange is possible, the determination unit 30a determines that the fan motor 51 is not started. In this case, since the startup command for the fan motor 51 is not sent from the microcomputer 30 to the sensorless control circuit 29, the transistors Q3a to Q5b of the inverter 25 remain off.

  Conversely, if the rotational speed of the fan motor 51 before activation is less than the predetermined rotational speed, sufficient air has not been sent to the evaporator 14 at the present time. Is determined to activate. In this case, an activation command for the fan motor 51 is sent from the microcomputer 30 to the sensorless control circuit 29, and the transistors Q3a to Q5b of the inverter 25 are turned on and off at different timings.

  It is assumed that the above-described predetermined rotational speed is set to an appropriate value in advance by desktop calculation, simulation, experiment, or the like based on the characteristics of the fan motor 51, the outdoor fan 15, and the evaporator 14.

(3) Operation FIGS. 6 and 7 are flowcharts showing the operation performed by the motor drive device 20. Hereinafter, the operation of the motor drive device 20 will be described with reference to FIGS. 6 and 7.

  Steps S <b> 1 to S <b> 3: When an operation start command for the outdoor fan 15 is acquired from the outdoor unit side control unit of the outdoor unit 10 (Yes in Step S <b> 1), the interwinding voltage detection unit 27 The voltage is detected (step S2), and the rotation speed estimation unit 28 estimates the rotation speed of the fan motor 51 at the current time before activation (step S3).

  Steps S4 and S5: The determination unit 30a compares the rotational speed of the fan motor 51 before startup estimated in Step S3 with a predetermined rotational speed (Step S4). If the rotation speed of fan motor 51 before activation is equal to or higher than the predetermined rotation speed (Yes in step S4), determination unit 30a determines that fan motor 51 is not activated at the present time (step S5). In this case, the drive voltage SU, SV, SW is not output from the inverter 25 to the fan motor 51.

  Step S6: Every time a predetermined time elapses from the operation of Step S2, the operations after Step S2 are repeated. That is, when it is determined in step S5 that the fan motor 51 is not activated, the voltage detection operation between the windings of the fan motor 51 is retried.

  Step S7: If the rotational speed of the fan motor 51 at the current time before activation is less than the predetermined rotational speed in Step S4 (No in Step S4), the determination unit 30a determines to activate the fan motor 51. In this case, the drive voltages SU, SV, and SW are output from the inverter 25 to the fan motor 51, and the fan motor 51 is started.

  Step S8: The fan motor 51 started in step S7 is driven by the sensorless control circuit 29 without the rotor position sensor.

  Steps S9 and S10: When the fact that an abnormality has occurred in the equipment included in the outdoor unit 10 during driving of the fan motor 51 is acquired from the outdoor unit side control unit (Yes in step S9), driving by the inverter 25 The output of the voltages SU, SV, SW to the fan motor 51 is stopped, and the fan motor 51 stops driving (step S10).

  Step S11: When a drive stop instruction for the outdoor fan 15 is acquired without acquiring from the outdoor unit side control unit that an abnormality has occurred in the equipment included in the outdoor unit 10 while the fan motor 51 is being driven (step S9). No), the output of the drive voltages SU, SV, SW to the fan motor 51 by the inverter 25 is stopped, and the fan motor 51 stops driving.

(4) Features (4-1)
In the motor drive device 20, the rotation speed estimation unit 28 estimates the rotation speed of the fan motor 51 from the detection value by the inter-winding voltage detection unit 27 before the fan motor 51 is started. When the microcomputer 30 determines that the estimated rotational speed of the fan motor 51 before activation is less than the predetermined rotational speed, the drive voltage is output to the fan motor 51. Further, when the microcomputer 30 determines that the estimated number of rotations of the fan motor 51 before activation is equal to or higher than the predetermined number of rotations, the drive voltage is not output to the fan motor 51.

  In this motor drive device, the interwinding voltage detection unit is not connected to the DC bus GND, so that it is not affected by the DC bus GND potential fluctuations and is not affected by the common mode potential fluctuations. Therefore, stable voltage detection is performed.

(4-2)
In addition, since the start execution of the fan motor 51 is controlled according to the rotation speed of the fan motor 51 before the start, the amount of power consumption due to the start-up and operation of the fan motor 51 can be minimized.

(4-3)
Further, since the interwinding voltage detection unit 27 divides the voltage between the windings of the fan motor 51 and outputs the divided voltage to the rotation speed estimation unit 28, the component rating on the rotation speed estimation unit 28 side can be reduced. Accordingly, downsizing and cost reduction can be achieved.

(4-4)
Further, the rotation speed estimation unit 28 outputs a first signal when the estimated rotation speed is equal to or greater than a predetermined value, and outputs a second signal when the estimated rotation speed is less than the predetermined value. Since the rotation speed estimation unit 28 electrically insulates the first signal and the second signal from the inter-winding voltage detection unit 27 and outputs them to the microcomputer 30, noise resistance is also improved.

(4-5)
In the motor drive device 20, the fan motor 51 is a brushless DC fan motor, and the number of rotations before starting is easily estimated.

(4-6)
In the motor driving device 20, the fan motor 51 after startup is normally driven by the rotor position sensorless.

(4-7)
In the heat pump device, since the interwinding voltage detection unit 27 of the motor drive device 20 is not connected to the DC bus GND, stable voltage detection is performed without being affected by the potential fluctuation of the DC bus GND. Therefore, the rotation speed of the fan motor 51 is estimated more accurately.

(5) Modification In the above embodiment, when the first signal is input to the input terminal P1 of the microcomputer 30, it is estimated that the rotational speed of the fan motor 51 is equal to or higher than the predetermined rotational speed. The means for estimating the rotational speed of the fan motor 51 is not limited thereto. Hereinafter, other means for estimating the rotational speed of the fan motor 51 will be described as first to fifth modifications.

(5-1) First Modification FIG. 8 is a circuit diagram of an inter-winding voltage detection unit 27 and a rotation speed estimation unit 28 according to a first modification. In FIG. 8, the photocoupler 280 has a first terminal T1, a second terminal T2, a third terminal T3, and a fourth terminal T4.

  A first resistor R1 and a second resistor R2 are connected in series to the input line from the V-phase drive coil terminal TV of the fan motor 51. A connection point C1 between the first resistor R1 and the second resistor R2 is connected to the first terminal T1. The input line from the low potential side of the second resistor R2 and the U-phase drive coil terminal TU is connected to the second terminal T2 of the photocoupler 280.

  The third terminal T3 is connected to the control power supply Vc side, and the fourth terminal T4 is connected to the GND side via the third resistor R3. Further, the high potential side of the third resistor R3 is connected to the input terminal P1 of the microcomputer 30.

  The photocoupler 280 includes a phototransistor 281 and a light emitting diode 282. The collector of the phototransistor 281 communicates with the third terminal T3, and the emitter of the phototransistor 281 communicates with the fourth terminal T4.

  The anode of the light emitting diode 282 communicates with the first terminal T1, and the cathode of the light emitting diode 282 communicates with the second terminal T2.

  For example, when the fan motor 51 rotates by natural wind, an induced electromotive voltage Vuv is generated between the U-phase drive coil terminal TU and the V-phase drive coil terminal TV of the fan motor 51. Since the light emitting diode 282 emits light according to the voltage at the connection point C1 at this time, the phototransistor 281 becomes conductive.

  As the rotation speed of the fan motor 51 increases, the induced electromotive voltage Vuv increases, and the voltage at the connection point C1 increases accordingly. When the voltage at the connection point C1 increases, the current flowing through the light emitting diode 282 increases and the current flowing through the phototransistor 281 also increases. As a result, the potential of the input terminal P1 of the microcomputer 30 increases.

  Here, since Vuv is an alternating voltage whose instantaneous value changes with time, the correlation between the peak value or the average value of the potential of the input terminal P1 of the microcomputer 30 and the rotation speed of the fan motor 51 is previously measured. By storing the information in the computer 30 or the determination unit 30a, the rotation speed of the fan motor 51 can be estimated. Alternatively, the rotational speed can be estimated by measuring the fluctuation cycle of the potential of P1 that fluctuates.

  In addition, since the rotation speed estimation part 28 is electrically insulated with respect to the voltage detection part 27 between windings, and outputs the output voltage according to the estimated rotation speed to the microcomputer 30, it has high noise resistance.

(5-2) Second Modification FIG. 9 is a circuit diagram of the inter-winding voltage detection unit 27 and the rotation speed estimation unit 28 according to a second modification. In FIG. 9, the insulation transformer 270 has a first terminal T21, a second terminal T22, a third terminal T23, and a fourth terminal T24.

  An input line from the V-phase drive coil terminal TV of the fan motor 51 is connected to the first terminal T21 of the isolation transformer 270. An input line from the U-phase drive coil terminal TU of the fan motor 51 is connected to the second terminal T22 of the isolation transformer 270.

  A Zener diode ZD19, a diode D20, and a resistor R are connected in series to the third terminal T23 of the isolation transformer 270. Specifically, the cathode of the Zener diode ZD19 is connected to the third terminal T23, the anode of the diode D20 is connected to the anode of the Zener diode ZD19, and the resistor R is connected to the cathode of the diode D20.

  A connection point C2 between the cathode of the diode D20 and the resistor R is connected to the input terminal P1 of the microcomputer 30. Further, the fourth terminal T24 of the insulation transformer 270 and the low potential side of the second resistor R2 are connected to the GND side.

  For example, when the fan motor 51 rotates by natural wind, an induced electromotive voltage Vuv is generated between the U-phase drive coil terminal TU and the V-phase drive coil terminal TV of the fan motor 51. The induced electromotive force Vuv is applied as a primary voltage between the first terminal T21 and the second terminal T22 of the isolation transformer 270, and a transformation ratio is applied between the third terminal T23 and the fourth terminal T24 of the isolation transformer 270. A secondary voltage corresponding to is output. When the voltage applied to both ends of the Zener diode ZD19 at this time exceeds the Zener voltage, a current flows through the resistor R, and a High signal as the first signal is input to the input terminal P1 of the microcomputer 30.

  Conversely, when the voltage across the Zener diode ZD19 is below the Zener voltage, no current flows through the resistor R, and the potential at the input terminal P1 of the microcomputer 30 is zero. This state is the same as the case where the second signal having a potential low enough to be distinguished from the first signal is input.

  Accordingly, when the rotation speed of the fan motor 51 when the voltage applied to both ends of the Zener diode ZD19 exceeds the Zener voltage is set to a predetermined rotation speed, the first signal is input to the input terminal P1 of the microcomputer 30. It can be estimated that the rotational speed of the fan motor 51 is equal to or higher than the predetermined rotational speed. Conversely, when the second signal is input to the input terminal P1 of the microcomputer 30, it can be estimated that the rotational speed of the fan motor 51 is less than the predetermined rotational speed.

  In the second modification, the inter-winding voltage detection unit 27 and the rotation speed estimation unit 28 are insulated by the insulation transformer 270, so that the insulation is high. Since Vuv is an alternating voltage whose instantaneous value changes with time, the first signal input to the input terminal P1 is a pulse signal.

(5-3) Third Modification FIG. 10 is a circuit diagram of the inter-winding voltage detection unit 27 and the rotation speed estimation unit 28 according to a third modification. In FIG. 10, the insulation transformer 270 has a first terminal T21, a second terminal T22, a third terminal T23, and a fourth terminal T24.

  An input line from the V-phase drive coil terminal TV of the fan motor 51 is connected to the first terminal T21 of the isolation transformer 270. An input line from the U-phase drive coil terminal TU of the fan motor 51 is connected to the second terminal T22 of the isolation transformer 270.

  A diode D20, a first resistor R21, and a second resistor R22 are connected in series to the third terminal T23 of the isolation transformer 270. Specifically, the anode of the diode D20 is connected to the third terminal T23, the first resistor R21 is connected to the cathode of the diode D20, and the second resistor R22 is connected in series to the first resistor R21.

  A connection point C3 between the first resistor R21 and the second resistor R22 is connected to the input terminal P1 of the microcomputer 30. Further, the fourth terminal T24 of the insulation transformer 270 and the low potential side of the second resistor R22 are connected to the GND side.

  For example, when the fan motor 51 rotates by natural wind, an induced electromotive voltage Vuv is generated between the U-phase drive coil terminal TU and the V-phase drive coil terminal TV of the fan motor 51. The induced electromotive force Vuv is applied as a primary voltage between the first terminal T21 and the second terminal T22 of the isolation transformer 270, and a transformation ratio is applied between the third terminal T23 and the fourth terminal T24 of the isolation transformer 270. A secondary voltage corresponding to is output.

  The induced electromotive voltage Vuv increases as the rotational speed of the fan motor 51 increases, and the voltage at the connection point C3 increases accordingly. As a result, the potential of the input terminal P1 of the microcomputer 30 increases.

  Here, since Vuv is an alternating voltage whose instantaneous value changes with time, the correlation between the peak value or average value of the potential of the input terminal P1 of the microcomputer 30 and the rotational speed of the fan motor 51 is previously measured. By storing the information in the computer 30 or the determination unit 30a, the rotation speed of the fan motor 51 can be estimated. Alternatively, the rotational speed can be estimated by measuring the fluctuation cycle of the potential of P1 that fluctuates.

  In the third modification, the inter-winding voltage detection unit 27 and the rotation speed estimation unit 28 are insulated by the insulation transformer 270, so that the insulation is high.

(5-4) Fourth Modification FIG. 11 is a circuit diagram of the inter-winding voltage detection unit 27 and the rotation speed estimation unit 28 according to a fourth modification. In FIG. 11, the rectifier circuit 268 is configured in a bridge shape by four diodes D41a, D41b, D42a, and D42b. The diode D41a and the diode D41b are connected in series, and the diode D42a and the diode D42b are connected in series. The cathode terminals of the diode D41a and the diode D42a are both connected to the plus side terminal of the smoothing capacitor 269 and function as the positive side output terminal of the rectifier circuit 268. The anode terminals of the diode D41b and the diode D42b are both connected to the negative terminal of the smoothing capacitor 269 and function as the negative output terminal of the rectifier circuit 268.

  An input line from the V-phase drive coil terminal TV of the fan motor 51 is connected to a connection point between the diode D41a and the diode D41b. An input line from the U-phase drive coil terminal TU is connected to a connection point between the diode D42a and the diode D42b. The rectifier circuit 268 rectifies the interwinding voltage of the fan motor 51 and supplies it to the smoothing capacitor 269.

  Further, a first resistor R31 and a second resistor R32 connected in series are connected in parallel to both ends of the smoothing capacitor 269. Further, a photocoupler 280 is connected in parallel to both ends of the second resistor R32. Specifically, the photocoupler 280 has a first terminal T1, a second terminal T2, a third terminal T3, and a fourth terminal T4, and a connection point C4 between the first resistor R31 and the second resistor R32 is provided. Are connected to the first terminal T1 of the photocoupler 280 via the Zener diode ZD1. Specifically, the cathode of the Zener diode ZD1 is connected to the connection point C4, and the anode is connected to the first terminal T1. Further, the low potential side of the second resistor R32 is connected to the second terminal T2 of the photocoupler 280.

  The third terminal T3 is connected to the control power supply Vc side, and the fourth terminal T4 is connected to the GND side via the third resistor R33. Further, the high potential side of the third resistor R33 is connected to the input terminal P1 of the microcomputer 30.

  The photocoupler 280 includes a phototransistor 281 and a light emitting diode 282. The collector of the phototransistor 281 communicates with the third terminal T3, and the emitter of the phototransistor 281 communicates with the fourth terminal T4.

  The anode of the light emitting diode 282 communicates with the first terminal T1, and the cathode of the light emitting diode 282 communicates with the second terminal T2.

  For example, when the fan motor 51 rotates by natural wind, an induced electromotive voltage Vuv is generated between the U-phase drive coil terminal TU and the V-phase drive coil terminal TV of the fan motor 51. When the voltage at the connection point C4 at this time exceeds the Zener voltage of the Zener diode ZD1, the light emitting diode 282 emits light and the phototransistor 281 is turned on, and the High signal as the first signal is supplied to the input terminal P1 of the microcomputer 30. Is entered.

  Conversely, when the voltage at the connection point C1 is lower than the Zener voltage of the Zener diode ZD1, the light emitting diode 282 does not emit light, so that the phototransistor 281 does not conduct and the potential of the input terminal P1 of the microcomputer 30 is 0. . This state is the same as the case where the second signal having a potential low enough to be distinguished from the first signal is input.

  Therefore, when the first signal is input to the input terminal P1 of the microcomputer 30 by setting the rotational speed of the fan motor 51 when the voltage at the connection point C4 exceeds the Zener voltage of the Zener diode ZD1 to a predetermined rotational speed. Can be estimated that the rotational speed of the fan motor 51 is equal to or higher than a predetermined rotational speed. Conversely, when the second signal is input to the input terminal P1 of the microcomputer 30, it can be estimated that the rotational speed of the fan motor 51 is less than the predetermined rotational speed.

  Since the interwinding voltage detection unit 27 rectifies the voltage between the windings of the fan motor 51 and outputs the rectified voltage to the rotation number estimation unit 28, the rotation number is obtained from an AC voltage whose voltage fluctuates every cycle. Is stable as a signal. Therefore, stable voltage detection is performed with simple detection logic and noise resistance is high.

(5-5) Fifth Modification FIG. 12 is a circuit diagram of the inter-winding voltage detection unit 27 and the rotation speed estimation unit 28 according to a fifth modification. In FIG. 12, a rectifier circuit 268, a smoothing capacitor 269, a first resistor R31, a second resistor R32, an input line from the V-phase drive coil terminal TV of the fan motor 51, and an input line from the U-phase drive coil terminal TU. Since the connection form is the same as that of the fourth modification, the description thereof is omitted.

  In FIG. 12, photocouplers 280 are connected in parallel to both ends of the second resistor R32. Specifically, the photocoupler 280 has a first terminal T1, a second terminal T2, a third terminal T3, and a fourth terminal T4, and a connection point C4 between the first resistor R31 and the second resistor R32 is provided. , Connected to the first terminal T1 of the photocoupler 280. Further, the low potential side of the second resistor R32 is connected to the second terminal T2 of the photocoupler 280.

  The third terminal T3 is connected to the control power supply Vc side, and the fourth terminal T4 is connected to the GND side via the third resistor R33. Further, the high potential side of the third resistor R33 is connected to the input terminal P1 of the microcomputer 30.

  The photocoupler 280 includes a phototransistor 281 and a light emitting diode 282. The collector of the phototransistor 281 communicates with the third terminal T3, and the emitter of the phototransistor 281 communicates with the fourth terminal T4.

  The anode of the light emitting diode 282 communicates with the first terminal T1, and the cathode of the light emitting diode 282 communicates with the second terminal T2.

  For example, when the fan motor 51 rotates by natural wind, an induced electromotive voltage Vuv is generated between the U-phase drive coil terminal TU and the V-phase drive coil terminal TV of the fan motor 51. Since the light emitting diode 282 emits light according to the voltage at the connection point C4 at this time, the phototransistor 281 becomes conductive.

  As the rotation speed of the fan motor 51 increases, the induced electromotive voltage Vuv increases, and the voltage at the connection point C4 increases accordingly. When the voltage at the connection point C4 increases, the current flowing through the light emitting diode 282 increases and the current flowing through the phototransistor 281 also increases. As a result, the potential of the input terminal P1 of the microcomputer 30 increases.

  By storing the correlation between the potential of the input terminal P1 of the microcomputer 30 and the rotation speed of the fan motor 51 in advance in the microcomputer 30 or the determination unit 30a, the rotation speed of the fan motor 51 can be estimated.

  Since the inter-winding voltage detection unit 27 rectifies the voltage between the windings of the fan motor 51 and outputs the rectified voltage to the rotation speed estimation unit 28, the rotation speed is obtained from the AC voltage whose voltage fluctuates every cycle. Is stable as a signal. Therefore, stable voltage detection is performed with simple logic and noise resistance is high.

(5-6) Sixth Modification In the above embodiment, the case where the motor driving device 20 drives only the fan motor 51 has been described. However, the motor drive device described above can also be applied to the case where the fan motor 51 and the compressor motor 61 are driven in a configuration in which the fan motor 51 is connected in parallel to the compressor motor 61.

  FIG. 13 is a block diagram illustrating an overall configuration of a system 200 in which a motor driving device according to a sixth modification is employed, and an internal configuration of the motor driving device. In FIG. 13, in order to simplify the configuration, the detailed configuration inside the rectifying unit 131 and each of the inverters 125 and 133 is omitted, but the internal configuration of the rectifying unit 131 and each of the inverters 125 and 133 is The same as FIG.

  The motor driving device 120 includes a smoothing capacitor 122, a current detection unit 124, an inverter 125, a fan motor side driving IC 126, and an inter-winding voltage detection unit 127 as a configuration on the fan motor 51 side.

  The motor driving device 120 includes a second inverter 133 and a driving IC 136 as a configuration on the compressor motor 61 side. The motor driving device 120 includes a rectifying unit 131 connected to the commercial power supply 91 and a second smoothing capacitor 132 as a configuration common to the compressor 11 and the outdoor fan 15.

  FIG. 14A is a block diagram illustrating functional units in a drive IC on the fan motor side according to a sixth modification. In FIG. 14A, the driving IC 126 includes a gate driving circuit 126a, a rotation speed estimation unit 126b, and a sensorless control circuit 126c.

  FIG. 14B is a block diagram illustrating functional units in the drive IC on the compressor motor side according to the sixth modification. In FIG. 14B, the driving IC 136 on the compressor motor 61 side includes a gate driving circuit 136a and a sensorless control circuit 136c.

  The smoothing capacitor 122, the current detection unit 124, the fan inverter 125, the gate drive circuit 126a, the rotation speed estimation unit 126b, the sensorless control circuit 126c, and the inter-winding voltage detection unit 127 include the smoothing capacitor 22, the current according to the above-described embodiment. The detection unit 24, the inverter 25, the gate drive circuit 26, the rotation speed estimation unit 28, the sensorless control circuit 29, and the inter-winding voltage detection unit 27 are the same.

  That is, the smoothing capacitor 122 smoothes the DC power supplied from the rectifier 131, and the current detector 124 detects the motor current Im of the fan motor 51 after startup. The fan inverter 125 generates drive voltages SU 1, SV 1, SW 1 for driving the fan motor 51 and outputs them to the fan motor 51. The gate drive circuit 126 a outputs a gate control voltage to the fan inverter 125. The rotation speed estimation unit 126b estimates the rotation speed of the fan motor 51 before activation based on the detection result of the inter-winding voltage detection unit 127. The sensorless control circuit 126c drives and controls the fan motor 51 after startup by a rotor position sensorless system.

  The rectifying unit 131 is connected to the commercial power supply 91 and rectifies the AC voltage from the commercial power supply 91. The second smoothing capacitor 132 is connected in parallel to the first smoothing capacitor 122 and the inverter 125, and smoothes the DC power supplied from the rectifying unit 131. The voltage smoothed by the second smoothing capacitor 132 is supplied to the second inverter 133 and also supplied to the smoothing capacitor 122 side which is the fan side. In addition, although the capacity | capacitance of the 2nd smoothing capacitor 132 is generally larger than the capacity | capacitance of the smoothing capacitor 122, this system is useful regardless of the magnitude relationship of the capacity | capacitance. The second inverter 133 generates drive voltages SU <b> 2, SV <b> 2, SW <b> 2 for driving the compressor motor 61, and outputs them to the compressor motor 61. The gate drive circuit 136a outputs a gate control voltage to the second inverter 133. The sensorless control circuit 136c drives and controls the compressor motor 61 by a rotor position sensorless system.

  The determination unit 130aa determines whether or not the estimated rotation speed of the fan motor 51 before startup is equal to or higher than a predetermined rotation speed. When the estimated number of rotations of the fan motor 51 before activation is greater than or equal to the predetermined number of rotations, the determination unit 130aa determines that the fan motor 51 is not activated. When the estimated number of rotations of the fan motor 51 before activation is less than the predetermined number of rotations, the determination unit 130aa determines to activate the fan motor 51. When determination unit 130aa determines that fan motor 51 is to be activated, inverter 125 outputs drive voltages SU1, SV1, and SW1 to fan motor 51, and fan motor 51 is activated.

  When the determination unit 130aa determines that the fan motor 51 is not activated, the inverter 125 does not output the drive voltages SU1, SV1, and SW1 to the fan motor 51. It will keep rotating under the influence.

  Thus, in a state where the fan motor 51 before starting is already rotating due to the influence of wind or the like, if the rotation speed is equal to or higher than the predetermined rotation speed, sufficient air is already in the evaporator 14 in the outdoor unit 10. Since the motor is being sent, the motor driving device 120 does not intentionally start the fan motor 51.

  On the other hand, if the rotational speed is less than the predetermined rotational speed, even if the fan motor 51 is rotating, the amount of air sent to the evaporator 14 in the outdoor unit 10 is considered to be insufficient. The driving device 120 activates the fan motor 51.

  Thus, since the start execution of the fan motor 51 is controlled in accordance with the rotational speed of the fan motor 51 before the start-up, the amount of power consumption due to the start-up of the fan motor 51 can be minimized.

  It is assumed that the above-described predetermined rotational speed is set to an appropriate value in advance by desktop calculation, simulation, experiment, or the like based on the characteristics of the fan motor 51, the outdoor fan 15, and the evaporator 14.

  As shown in FIG. 13, the microcomputer 130 functions as an operation control unit 130ba as a compressor motor control system 130b. The operation control unit 130ba controls the start and stop of driving of the compressor motor 61.

  In this heat pump apparatus, the inverter 125 for driving the fan motor and the second inverter 133 for driving the compressor motor share the GND potential, and the GND by the second inverter 133 that generally requires a larger output than the inverter 125. Although the fluctuation of the potential and the common mode potential fluctuation of the compressor motor occur, the rotation speed of the fan motor 51 is estimated from the voltage between the windings of the fan motor 51, so that the rotation speed is not affected by the fluctuation of the GND potential. Is estimated.

  Further, in the above embodiment, since the estimation of the rotational speed is performed only before the motor is started, if the connection between the winding voltage detection unit 27 and the rotational speed estimation unit 28 is disconnected after the startup, It can be set as the motor drive device with less power consumption.

(5-7) Seventh Modification FIG. 15 is a circuit diagram of the main part of a motor drive device according to a seventh modification. In FIG. 15, an inverter 25 similar to that in the above embodiment is employed as the inverter. Further, as the gate drive circuit, the same gate drive circuit 26 as in the above embodiment is employed. Note that parts other than the inverter 25 and the gate drive circuit 26 and having the same functions as those in the above embodiment are given the same names and symbols as in the above embodiment, and description thereof is omitted.

(5-7-1) Inverter 25
The inverter 25 includes an output line 81 connected to the U phase of the fan motor 51, an output line 82 connected to the V phase, and an output line 83 connected to the W phase.

  The upper arm of the inverter 25 is constituted by a transistor Q3a, a transistor Q4a and a transistor Q5a. The emitter of the transistor Q3a is connected to the output line 81, the emitter of the transistor Q4a is connected to the output line 82, and the emitter of the transistor Q5a is connected to the output line 83. Yes.

  The lower arm of the inverter 25 is constituted by a transistor Q3b, a transistor Q4b, and a transistor Q5b. The collector of the transistor Q3b is connected to the output line 81, the collector of the transistor Q4b is connected to the output line 82, and the collector of the transistor Q5b is connected to the output line 83. Yes.

  To the collectors of the transistors Q3a, Q4a, and Q5a, a positive electrode of a motor power supply Vfl (“smoothed voltage Vf1” in the above embodiment) is connected to supply a voltage to the fan motor 51. The emitters of the transistors Q3b, Q4b, and Q5b are connected to the negative electrode of the motor power supply Vfl (“smoothed voltage Vf1” in the above embodiment) in order to supply a voltage to the fan motor 51. Since the output line 81 passes through a connection point between the emitter of the transistor Q3a and the collector of the transistor Q3b, when the transistor Q3a is turned on, the motor power supply Vfl and the output line 81 become conductive, and the U phase of the fan motor 51 The output current flows through.

  Similarly, since the output line 82 passes through a connection point between the emitter of the transistor Q4a and the collector of the transistor Q4b, when the transistor Q4a is turned on, the motor power supply Vfl and the output line 82 are conducted, and the fan motor 51 The output current flows in the V phase.

  Similarly, since the output line 83 passes through a connection point between the emitter of the transistor Q5a and the collector of the transistor Q5b, when the transistor Q5a is turned on, the motor power supply Vfl and the output line 83 are conducted, and the fan motor 51 The output current flows in the W phase.

(5-7-2) Gate drive circuit 26
The gate drive circuit 26 internally includes an upper arm side drive circuit 26a that drives the transistors Q3a, Q4a, and Q5a on the upper arm side, and a lower arm side drive circuit 26b that drives the transistors Q3b, Q4b, and Q5b on the lower arm side. And 10 terminals Vcc, Vdd, Hin, Lin, Vss, Vbo, Ho, Vs, Lo, and COM.

  The sensorless control circuit 29 controls the inverter 25 via the three gate drive circuits 26, the first gate drive circuit 261 operates the transistors Q3a and Q3b, and the second gate drive circuit 262 operates the transistors Q4a and transistors. Q4b is operated, and the third gate drive circuit 263 operates the transistors Q5a and Q5b. Hereinafter, when the contents common to the first gate driving circuit 261, the second gate driving circuit 262, and the third gate driving circuit 263 are described, the expression gate driving circuit 26 is used.

  In the gate drive circuit 26, the positive electrode of the driving power source Vb for driving the transistor is connected to the terminal Vcc, and the positive electrode of the logic power source Vc is connected to the terminal Vdd. The signal line from the sensorless control circuit 29 is connected to the terminal Hin and the terminal Lin, and the negative electrodes of the driving power supply Vb and the logic power supply Vc are connected to the terminal Vss, and the motor power supply Vfl (in the above-described embodiment, “after smoothing”). The voltage Vf1 ") is connected to the negative electrode.

  The line branched from the high potential side pole of the capacitor of the bootstrap circuit 6 is connected to the terminal Vbo, the emitters of the transistors Q3a, Q4a, Q5a are connected to the terminal Vs, and the emitters of the transistors Q3b, Q4b, Q5b. Is connected to the terminal COM. Further, the gates of the transistors Q3a, Q4a, and Q5a are connected to the terminal Ho, and the gates of the transistors Q3b, Q4b, and Q5b are connected to the terminal Lo.

  The transistors Q3a, Q4a, Q5a, Q3b, Q4b, and Q5b are turned on / off by the gate drive circuit 26 controlling the gate potential via the terminal Ho and the terminal Lo. The operation of the gate drive circuit 26 is controlled based on a duty ratio control signal input from the sensorless control circuit 29 to the terminal Hin and the terminal Lin.

(5-7-3) Bootstrap circuit 6
The gate drive circuit 26 includes a positive electrode of the drive power supply Vb connected to the terminal Vcc and the emitters of the transistors Q3a, Q4a, Q5a in order to appropriately input the gate potential to the transistors Q3a, Q4a, Q5a on the upper arm side. Between the two, a bootstrap circuit 6 is provided. The first bootstrap circuit 61 corresponding to the first gate driving circuit 261 includes a capacitor 611, a resistor 612, and a diode 613. The second bootstrap circuit 62 corresponding to the second gate driving circuit 262 includes a capacitor 621, a resistor 622, and a diode 623. The third bootstrap circuit 63 corresponding to the third gate drive circuit 263 includes a capacitor 631, a resistor 632, and a diode 633. Hereinafter, when the contents common to the first bootstrap circuit 61, the second bootstrap circuit 62, and the third bootstrap circuit 63 are described, the expression “bootstrap circuit 6” is used.

  As shown in FIG. 15, one ends of capacitors 611, 621, and 631 are connected to a connection point between the emitters of the upper-arm transistors Q3a, Q4a, and Q5a and the collectors of the lower-arm transistors Q3b, Q4b, and Q5b. . The other ends of the capacitors 611, 621, 631 are connected to the positive electrode of the driving power supply Vb through resistors 612, 622, 632 and diodes 613, 623, 633.

  The resistors 612, 622, and 632 are provided to limit the charging current of the capacitors 611, 621, and 631, and the diodes 613, 623, and 633 prevent the capacitors 611, 621, and 631 from being discharged through the resistors 612, 622, and 632, respectively. The forward direction is directed from the positive electrode side of the drive power supply Vb to the capacitors 611, 621, 631 side.

  The upper arm side drive circuit 26a inside the gate drive circuit 26 takes in a high potential from the capacitors 611, 612, 613 in order to control the on / off of the transistors Q3a, Q4a, Q5a. The lower arm side drive circuit 26b inside the gate drive circuit 26 controls on / off of the transistors Q3b, Q4b, Q5b, but is connected to the terminal Vcc because the emitter side of the transistors Q3b, Q4b, Q5b is grounded. It can be controlled only by the potential of the positive electrode of the drive power supply Vb.

  By turning on the lower arm side transistors Q3b, Q4b, Q5b by the lower arm side drive circuit 26b, the drive power supply Vb (positive electrode) -diodes 613, 623, 633, resistors 612, 622, 632, capacitors 611, 621, 631 -Current flows through the path of the lower arm side transistors Q3b, Q4b, Q5b-drive power supply Vb (negative electrode). At this time, since the capacitors 611, 621, and 631 are charged, it can be used as a power supply for driving the upper arm.

  It can also be said that the drive power sources Vb and Vs are connected with a predetermined impedance (resistance value) by the bootstrap circuit 6 including the gate drive circuit 26 (between Vbo and Vs). Since the gate drive circuit 26 and the bootstrap circuit 6 normally use the same circuit / element in each phase, the impedance (resistance value) of each phase is almost the same value.

(5-7-4) Operation of Motor Drive Device 20 When the transistor of one arm corresponding to a certain phase is turned on by the control of the sensorless control circuit 29, the transistor of the other arm is turned off. For example, the upper arm side transistor Q3a and the lower arm side transistor Q3b corresponding to the U phase are not turned on at the same time, and the transistor Q3b is turned off when the transistor Q3a is turned on. In FIG. 15, for example, when the transistor Q3a corresponding to the V phase is turned on and the transistor Q4b is turned on, from the positive electrode of the motor power supply Vfl, the collector of the transistor Q3a, the emitter of the transistor Q3a, the output line 81, the fan motor 51, Current flows in the order of the output line 82, the collector of the transistor Q4b, the emitter of the transistor Q4b, and the negative electrode of the motor power supply Vfl.

  In the motor drive device 20, the rotation speed estimation unit 28 (see FIG. 1) estimates the rotation speed of the fan motor 51 from the detection value of the interwinding voltage detection unit 27 before the fan motor 51 is started. When the microcomputer 30 (see FIG. 1) determines that the estimated rotational speed of the fan motor 51 before activation is less than the predetermined rotational speed, a drive voltage is output to the fan motor 51. Further, when the microcomputer 30 determines that the estimated number of rotations of the fan motor 51 before activation is equal to or higher than the predetermined number of rotations, the drive voltage is not output to the fan motor 51.

(5-7-5) Features For example, in the method of detecting the motor terminal voltage and estimating the rotation speed of the fan as in Patent Document 1, a current flows to the bootstrap circuit 6 via a circuit that detects the terminal voltage. Therefore, even when the rotational speed is 0, a DC voltage is generated at the motor terminal by dividing the drive power supply Vb by the bootstrap circuit 6 and the terminal voltage detection circuit. Therefore, there is a possibility that the rotational speed cannot be detected accurately.

  On the other hand, in the motor drive device 20 according to the seventh modification, the interwinding voltage detection unit 27 is not connected to the DC bus GND, and detection is performed based on the interwinding terminal voltage, that is, the terminal voltage difference. Therefore, it is possible to detect the rotational speed almost without being affected by the bootstrap circuit 6. In particular, in the case of using the insulation transformer among the above-described modified examples, since the DC component of the voltage between the winding terminals can be removed, the bootstrap circuit 6 is not affected at all.

  As described above, according to the present invention, even a motor whose rotor position before starting is not estimated can be started without causing abnormalities such as overvoltage, overcurrent, and step-out to the inverter. This is useful for motors that are later driven by rotor position sensorless control.

  A motor that is relatively less susceptible to the influence of an external force is particularly useful because it extends the range in which a safe and stable restart can be performed without providing a rotation state detection circuit before the start. Therefore, stable voltage detection is performed.

15 Outdoor fan 20 Motor drive device 22 Smoothing capacitor 25 Inverter 27 Inter-winding voltage detection unit 28 Rotational speed estimation unit 29 Sensorless control circuit 30 Microcomputer (control unit)
30a determination unit 51 fan motor 91 commercial power supply 125 first inverter 133 second inverter 61, 62, 63 bootstrap circuit 261, 262, 263 gate drive circuit Q3a, Q4a, Q5a transistor (upper arm side switching element)
Q3b, Q4b, Q5b Transistor (lower arm side switching element)

JP-A-7-337080

Claims (19)

A motor drive device for controlling the output voltage to the motor (51) to drive and stop the motor (51),
An inter-winding voltage detector (27) for detecting a voltage between windings of the motor (51);
A control unit (30) for determining whether to output a drive voltage to the motor (51) based on a detection value by the inter-winding voltage detection unit (27) before starting the motor (51);
Comprising
Motor drive device (20). Before starting the motor (51), further comprising a rotation speed estimation unit (28) for estimating the rotation speed of the motor (51) from the detection value by the inter-winding voltage detection unit (27),
When the estimated rotational speed of the motor (51) before startup estimated by the rotational speed estimation unit (28) is less than a predetermined rotational speed, a drive voltage is output to the motor (51),
When the estimated rotational speed of the motor (51) before startup estimated by the rotational speed estimation unit (28) is equal to or higher than a predetermined rotational speed, a drive voltage is not output to the motor (51).
The motor drive device (20) according to claim 1. The inter-winding voltage detection unit (27) divides the voltage between the windings of the motor (51) and outputs the divided voltage to the rotation speed estimation unit (28).
The motor drive device (20) according to claim 2. The rotational speed estimation unit (28) outputs a first signal when the estimated rotational speed is equal to or greater than a predetermined value, and a second signal different from the first signal when the estimated rotational speed is less than the predetermined value, Electrically insulated from the interwinding voltage detector (27) and output to the controller (30);
The motor drive device (20) according to claim 3. The rotation speed estimation unit (28) electrically insulates the output voltage corresponding to the estimated rotation speed from the inter-winding voltage detection unit (27) and outputs the output voltage to the control unit (30).
The motor drive device (20) according to claim 3. The control unit (30) includes a determination unit (30a) that determines whether the estimated rotation number is equal to or higher than a predetermined rotation number.
The motor drive device (20) according to claim 5. The interwinding voltage detector (27) and the rotation speed estimator (28) are insulated by an insulating transformer,
The rotation speed estimation unit (28) estimates the rotation speed of the motor (51) from the output voltage of the insulation transformer.
The motor drive device (20) according to claim 2. The rotational speed estimation unit (28) outputs a first signal when the estimated rotational speed is greater than or equal to a predetermined value, and a second signal different from the first signal when the estimated rotational speed is less than the predetermined value. Output to the control unit (30),
The motor drive device (20) according to claim 7. The rotation speed estimation unit (28) outputs an output voltage corresponding to the estimated rotation speed to the control unit (30).
The motor drive device (20) according to claim 7. The control unit (30) includes a determination unit (30a) that determines whether the estimated rotation number is equal to or higher than a predetermined rotation number.
The motor drive device (20) according to claim 9. The inter-winding voltage detection unit (27) rectifies the voltage between the windings of the motor (51) and outputs the rectified voltage to the rotation speed estimation unit (28).
The motor drive device (20) according to claim 2. The rotational speed estimation unit (28) outputs a first signal when the estimated rotational speed is equal to or greater than a predetermined value, and a second signal different from the first signal when the estimated rotational speed is less than the predetermined value, Electrically insulated from the interwinding voltage detector (27) and output to the controller (30);
The motor drive device (20) according to claim 11. The rotation speed estimation unit (28) electrically insulates the output voltage corresponding to the estimated rotation speed from the inter-winding voltage detection unit (27) and outputs the output voltage to the control unit (30).
The motor drive device (20) according to claim 11. The control unit (30) includes a determination unit (30a) that determines whether the estimated rotation number is equal to or higher than a predetermined rotation number.
The motor drive device (20) according to claim 13. The motor (51) is a brushless DC fan motor.
The motor drive device (20) according to any one of claims 1 to 14. The motor (51) is driven without a rotor position sensor after startup,
The motor drive device (20) according to claim 15. An inverter (25) formed by the upper arm side switching elements (Q3a, Q4a, Q5a) and the lower arm side switching elements (Q3b, Q4b, Q5b);
A bootstrap circuit (61, 62, 63) for generating a higher potential than the lower potential side of the upper arm side switching element (Q3a, Q4a, Q5a);
A drive circuit (261, 262, 263) that takes in the high potential from the bootstrap circuit (61, 62, 63) and turns on and off the upper arm side switching elements (Q3a, Q4a, Q5a);
Further comprising
The motor drive device (20) according to any one of claims 1 to 16. Fan (15),
A fan motor (51) for rotating the fan (15);
The motor driving device (20) according to any one of claims 1 to 16, which drives the fan motor (51);
A heat pump device comprising: The motor driving device (20)
A first inverter (125) that converts a DC voltage supplied from a DC power supply unit into a drive voltage for driving the fan motor (51) and outputs the drive voltage to the fan motor (51);
A second inverter (133) connected in parallel to the first inverter (125) to the DC power supply unit and driving a load different from the fan motor (51);
Further comprising
The heat pump apparatus according to claim 18.

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