WO2005039037A1

WO2005039037A1 - Fan controller, refrigeration cycle system and method for estimating rotation speed of fan

Info

Publication number: WO2005039037A1
Application number: PCT/JP2004/013932
Authority: WO
Inventors: Takahisa Endo; Naohito Kamiya; Takayuki Kambe
Original assignee: Toshiba Carrier Corporation
Priority date: 2003-10-17
Filing date: 2004-09-24
Publication date: 2005-04-28
Also published as: JP4436651B2; JP2005124330A; KR100803444B1; CN100508358C; CN1868111A; KR20060063995A

Abstract

[PROBLEMS] A fan controller capable of preventing demagnetization of the permanent magnet of a motor and breakdown of a switching element on the negative side of an inverter even if starting control is performed while the fan is rotating with natural wind, and a refrigeration cycle system and a method for estimating the rotation speed of the fan. [MEANS FOR SOLVING PROBLEMS] A control means (13) is provided that turns on switching elements for three phases forming the negative side arm of an inverter at the time of starting, and, when the current level detected by a current level detecting means (11) under on state exceeds a protection level set lower than a level being judged as short circuit of the arm, resets the switching elements for three phases to off state thus interrupting the starting operation.

Description

Specification

Fan control device, refrigeration cycle device, and fan rotation speed estimation method

Technical field

The present invention relates to startup control of a fan that may rotate due to an external factor, and relates to a control device for the fan, a refrigeration cycle device employing the control, and a method of estimating a fan speed during control.

Background art

[0002] An outdoor fan or the like of an air conditioner drives a fan motor and rotates by natural wind in a state. Conventionally, a fan drive device using a brushless DC motor has a sensor for detecting the rotational position of a rotor such as a Hall element, and detects the rotational position of the rotor based on an output signal of the sensor when the fan is started. After controlling the energization to each switching element constituting the inverter in accordance with the rotational position, stopping the fan and positioning the motor, the start is started (for example, Japanese Patent Application Publication No. 2000-125584). ) OAt this time, when the rotation speed of the fan rotating by natural wind was high, the compressor was driven without controlling the start of the fan.

Disclosure of the invention

Problems to be solved by the invention

[0003] In recent years, when driving a motor, a method has been adopted in which a sensor such as a Hall element that detects the rotational position of a rotor is eliminated, the number of components is reduced, reliability is reduced by component failure, and cost is reduced. Have been. For example, a motor drive device for a compressor detects a current flowing through the winding of each phase, calculates a rotation speed from the current value, and estimates a rotor position to adopt a vector control for driving. RU

[0004] However, in the case of the above-described fan motor, unlike the compressor, the load on the fan itself is light, and thus the fan motor rotates by itself due to natural wind even when the operation is stopped. If an attempt is made to use a sensorless motor for such a motor, the number of revolutions can be estimated from the current flowing through the motor after startup, but before the startup, the fan has no rotation at all. Force start control will be executed. In that case, the fan with strong natural wind When the motor starts to be started while rotating, an excessive current flows through the winding and the switching element forming the inverter due to the induced voltage generated in the motor winding, and the permanent magnet of the rotor is demagnetized, There was a problem that the switching element was destroyed. For this reason, a sensorless motor cannot be used for the fan motor, and a rotational position sensor must be provided! / Was in the situation.

[0005] When an FET or an IGBT is used as a switching element in an inverter, a driving power supply for a three-phase switching element constituting a positive-side (hereinafter, also referred to as an upper phase) arm is used as a negative-side (hereinafter, referred to as an upper-phase) driving power supply. In general, a simplified power supply circuit that drives the switching element is provided by providing a capacitor that is charged by the current that flows when the switching element that constitutes the arm is turned on. Have been.

[0006] In the inverter device having such a circuit, it is necessary to turn on the lower-phase switching element and charge up the capacitor serving as the power supply of the upper-phase switching element at the time of starting or before starting drive control. is there. However, if the lower-phase switching element is kept in the ON state during this charge-up, when the fan is rotating at high speed, the overcurrent demagnetizes the permanent magnet of the rotor or switches the switching element, as described above. There was a problem of being destroyed.

[0007] The present invention has been made to solve the above problems, and an object of the present invention is to reduce the demagnetization of the permanent magnet of the motor and the motor even if the startup control is performed while the fan is rotating by natural wind. An object of the present invention is to provide a fan control device and a refrigeration cycle device that can prevent destruction of a switching element on the negative side of an inverter.

[0008] Another object of the present invention is to provide a refrigeration cycle apparatus capable of preventing the refrigeration cycle from being overloaded when the natural wind is weakened after the air conditioning operation is started in a state where the natural wind is strong. Is to provide.

[0009] Still another object of the present invention is to provide a method for estimating the number of revolutions of a fan, which can estimate the number of revolutions without a rotation position detecting element.

Means for solving the problem

[0010] In order to achieve the above object, the present invention provides inventions represented by claims 1, 3, and 7. The invention according to claim 1 is a sensorless motor for driving a fan, an inverter connected to a switching element power S3-phase bridge to supply three-phase AC power to the motor, and current detection means for detecting a current flowing to the motor. When the switching elements for the three phases forming the negative side arm of the inverter are turned on at the time of startup, the protection level is set lower than the current detection value of the current detection means in this on state is determined to be arm short circuit. And a control means for returning the three-phase switching elements to an off state and stopping the activation when the number exceeds three.

[0011] The invention according to claim 3 provides a refrigeration cycle including a compressor, an outdoor heat exchanger, and an outdoor fan for promoting heat exchange thereof, a sensorless motor for driving the outdoor fan, and a three-phase bridge comprising a switching element. The inverter connected to supply three-phase AC power to the motor, current detection means for detecting the current flowing to the motor, and the three-phase switching elements forming the negative arm of the inverter at startup are turned on. When the current detection value of the current detection means in the state exceeds the protection level set lower than the value determined as arm short-circuit, the start of the fan is stopped by returning the three-phase switching elements to the off state. Execute the fan start control to stop the fan and the wind fan stop control to operate the compressor while the fan is stopped. A refrigeration cycle apparatus and control means for repeatedly performing fan startup control after excessive.

[0012] The invention according to claim 7 provides a three-phase component in which a switching element forms a negative arm of a three-phase bridge-connected inverter so as to supply three-phase AC power to a sensorless motor that drives a fan. And turning on the switching elements of the three phases, detecting the current flowing to the motor when the switching elements for three phases are on, and estimating the fan rotation speed based on the detected current value. Steps and

Are sequentially executed.

Brief Description of Drawings

FIG. 1 is a diagram showing a schematic configuration of a control unit of an air conditioner as a first embodiment for implementing a fan control device, a refrigeration cycle device, and a fan rotation speed estimation method according to the present invention. .

FIG. 2 is a cross-sectional view showing a configuration of a main part of the outdoor unit.

[Fig.3] is a circuit diagram partially showing the detailed configuration of the outdoor fan inverter. FIG. 4 is a diagram showing a relationship between a current flowing through a winding of the motor and time to explain the operation of the first embodiment.

FIG. 5 is a diagram showing the relationship between the number of rotations of the motor and the current flowing through the windings, for explaining the operation of the first embodiment.

FIG. 6 is a time chart showing two typical control examples according to the first embodiment.

FIG. 7 is a flowchart showing a specific processing procedure of the MCU when executing the operation of the first embodiment.

FIG. 8 is a flowchart showing a specific processing procedure of an MCU constituting a control unit according to a second embodiment of the present invention.

FIG. 9 is a flowchart showing a specific processing procedure of an MCU constituting a control unit according to a third embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in detail based on preferred embodiments shown in the drawings.

FIG. 1 is a diagram showing a schematic configuration of a control unit of an air conditioner as a first embodiment for implementing a fan control device, a refrigeration cycle device, and a method of estimating a fan rotation speed according to the present invention. In the figure, an inverter 2 is connected to an AC power supply 1. The inverter 2 rectifies and smoothes the alternating current, converts the obtained direct current into alternating current with a variable voltage and variable frequency, and outputs the converted alternating current. The compressor 3 constituting the refrigeration cycle is connected.

[0015] The refrigeration cycle includes a compressor 3, a four-way valve 4, an outdoor heat exchanger 5, an expansion valve 6, an indoor heat exchanger 7, an outdoor fan 8, and an indoor fan 9. The outdoor fan 8 includes a fan 8F and a motor 8M as described later, and includes an inverter 10 for controlling the motor 8M. The inverter 10 has a current detection circuit 11 for detecting a winding current of the motor 8M. In addition, a speed control circuit 12 is provided to control the speed of the indoor fan 9. Furthermore, a control unit 13 that controls the inverters 2 and 10 described above and provides a speed command to the speed control circuit 12 is provided. And an abnormality display section 15 for performing the operation. Control unit 13 Includes a microcomputer unit (hereinafter abbreviated as MCU), and executes arithmetic processing described later.

FIG. 2 is a cross-sectional view showing a configuration of a main part of the outdoor unit 17. When viewed from the front (below the drawing), the outdoor heat exchange 5 is bent at a substantially right angle on the left side and the rear side. A compressor 3 is arranged on the right side, and an outdoor fan 8 that drives a fan 8F by a motor 8M is installed inside the outdoor heat exchanger 5, and sucks outside air from the directions of arrows A and B. It is configured to promote the heat exchange of the outdoor heat exchange 5 by discharging in the direction.

FIG. 3 is a circuit diagram partially showing the detailed configuration of the inverter 10 by blocks.

In the figure, for example, six switching elements U, V, W, X, Υ, で composed of IGBTs are connected in a three-phase bridge. That is, a series connection circuit of the switching elements U and X, a series connection circuit of the switching elements V and と, and a series connection circuit of the switching elements W and Ζ are connected in parallel, and one end thereof is connected to the positive electrode of the DC power supply 21. The other end is connected to the negative electrode of the DC power supply 21.

[0018] Of these, switching elements U, V, W constitute an upper phase arm, and switching elements X, Υ, Ζ constitute a lower phase arm. Also, the interconnection point of the switching elements U and X, the interconnection point of the switching elements V and 、, and the interconnection point of the switching elements W and が are outside the U, V, and W phases of the star-connected motor 8Μ. Connected to the connecting conductor.

A drive circuit 22 is connected to each gate of the switching elements U, V, W. In order to store the drive power of each drive circuit 22, a capacitor C is provided, one end of which is connected to the drive circuit 22 and the other end of which is connected to the sources (negative voltage side) of the switching elements U, V, W, respectively. In order to charge up the capacitor, a negative pole is connected to the negative pole of the DC power supply 21 and a positive pole is connected to one end of the capacitor C via a diode D for preventing backflow. Being done.

The drive circuit 22 is also connected to each gate of the switching elements X, Υ, Ζ.

1S For simplicity of explanation and drawings, they are omitted.

On the other hand, in order to detect a current flowing through each phase winding of the motor 8M, a resistor R is connected between the sources of the switching elements X, Υ, and Z and the negative electrode of the DC power supply 21. Operational amplifiers 23 are provided to amplify voltages generated on the switching elements X, Υ, and Z, respectively. These three resistors R and three operational amplifiers 23 constitute the above-described current detection circuit 11. The control unit 13 includes an EEPROM 24 that stores a protection level Is, which is a control stop level, a repetition period Tv, and the like, which will be described later, and the switching elements U, V, W, X, and The drive circuit 22 of (1) and (2) is provided with an MCU 25 for applying an on / off control signal to the inverter 2, the speed control circuit 12, and the abnormality display unit 15 shown in FIG.

[0022] The principle of the present embodiment configured as described above will be described with reference to Figs. 4 to 6 and then the operation thereof will be described. If the outdoor fan is stopped, no voltage is induced in the motor windings, so the switching element current of the inverter is zero. However, when the outdoor fan is rotated by natural wind, a voltage is induced in the winding of the motor, and when the switching element is turned on, a sine wave current flows through the winding of the motor.

In the present invention, in order to detect the rotating state of the outdoor fan before starting, the switching element in the lower phase of the inverter is turned on for a predetermined time T1. At this time, assuming that the outdoor fan is rotating, the winding current of each phase changes as shown by a solid line al in FIG. 4 or a dashed line a2 saturated in the middle. Also, when the lower-phase switching element is turned on, one of the corresponding upper-phase switching elements is short-circuited and the change in the current value when the arm is short-circuited. Shown in b.

[0024] When the arm is short-circuited as shown by the straight line b, an extremely large current exceeding the threshold lb for determining that the arm is short-circuited flows. For this reason, as soon as the threshold value lb is exceeded, all of the switching elements are turned off and abnormally stopped. If this abnormal stop is applied to the outdoor fan of the air conditioner, the compressor will not be operated thereafter and an error display will be performed. Since the current flowing at this time flows from the upper phase switching element to the lower phase switching element, the current flowing to the winding is substantially zero.

[0025] On the other hand, when the rotation speed of the outdoor fan is low, the current after the time T1 passes through only A2 as shown by the dashed line a2 where the intermediate force of the solid line al also saturates, as shown by the solid line al. As described above, when the number of rotations of the outdoor fan is high, the current increases linearly with the passage of time, and when the time T1 has elapsed, the current reaches a high value of A1. The current value at this time T1 is As shown in FIG. 5, it increases in proportion to the rotation speed. The final current value is determined by the relationship between the motor winding inductance and the induced voltage. If the outdoor fan rotates and a voltage is induced in the winding, the rate of increase (slope) of the current value increases in the same manner because it is determined by the inductance of the motor winding, but the rotation speed is low and the induced voltage is small. In such a case, the increase of the current is stopped at an early stage, and the value is maintained. At higher speeds, the current continues to increase and eventually reaches a higher value. Therefore, after a certain period of time, the current fan speed can be used to estimate the rotational speed of the outdoor fan at that time.

Here, depending on the characteristics of the motor, when the current flowing through the winding is large as in the case of the solid line al, the permanent magnet of the rotor may be demagnetized at time T1. Also, the switching element may be destroyed by the overcurrent. Therefore, if the current value at the level at which the permanent magnet of the rotor is demagnetized or the overcurrent value at which the switching element breaks down is lower than the lower value of the slip force, and the protection level Is is reached, at that point The switching element in the lower phase is returned to the off state to prevent demagnetization and element destruction.

That is, in the case of the solid line al, the switching element of the lower phase is turned off at the time t.

Power depending on motor and inverter specifications In general, the current value leading to demagnetization is lower than the current value leading to element destruction, so it is best to set a lower protection level Is based on the demagnetization current value. General.

[0028] In the current pattern indicated by the solid line al in FIG. 4, a state where the protection level is exceeded is also shown for reference. Since the phase switching element is turned off, the protection level does not exceed Is. In addition, in the case of the straight line b indicating the state of the current increase when the arm is short-circuited, a large current flows beyond the protection level Is. In this case, since the large current flows in a very short time, the protection level Is No response is made even if is set, and the switching elements X, Y, and Z in the lower phase are returned to the off state at the threshold lb for arm short circuit detection.

[0029] For example, before reaching the current lb at the time of arm short-circuit, the protection level Is is reached first. However, since the determination that the protection level Is is reached is made slower in response to noise countermeasures, the arm The switching elements X, Y, and Z are turned off in response to the short-circuit current lb.

[0030] On the other hand, if the outdoor fan is rotating due to natural wind at the start of operation, the rotation speed Is large, sufficient ventilation is provided to the outdoor heat exchanger without driving the fan by the motor, so that heat exchange is possible and air conditioning operation can be continued.

[0031] The rotational speed of the outdoor fan capable of performing the air-conditioning operation varies depending on its characteristics and the configuration of the refrigeration cycle of the air conditioner. Generally, in FIG. 5, the natural speed of the fan capable of performing the air-conditioning operation without driving the fan is shown. The motor current value at the above-described time T1 corresponding to the lower limit value R of the rotation speed due to the wind is lower than the current value leading to element destruction and the current value leading to demagnetization.

[0032] Therefore, in a motor that drives an outdoor fan for air conditioning, if the protection level Is is set to a value corresponding to the rotational speed R at which the fan can be driven, element destruction, demagnetization is eliminated, and the outdoor fan is not driven. The air conditioning operation can be performed while the drive of the air conditioner is stopped.

[0033] When the air-conditioning operation is continued without driving the fan, it is conceivable that the natural wind decreases during the operation, and the heat radiation and heat absorption in the outdoor heat exchange become insufficient. If such a situation occurs, the heat exchange in the outdoor heat exchanger will be insufficient, and the pressure on the high pressure side of the refrigeration cycle will rise abnormally, possibly leading to equipment failure.

[0034] Therefore, even when it is determined that driving of the fan is unnecessary by the above-described control at the time of start-up, the switching element of the lower phase is turned on at every predetermined repetition cycle Tv to check whether the rotational speed of the outdoor fan has decreased. It is repeatedly determined whether or not it is. In this case, if the number of rotations of the outdoor fan due to natural winds decreases, the current value in the ON state of the lower-phase switching element becomes lower than the protection level Is even after time T1, so that the outdoor The startup of the fan is not stopped, the forced stop for the fan positioning is performed, and then the PWM drive is started.

[0035] Here, to summarize the protection level Is, when applied to an outdoor fan of an air conditioner, the protection level Is is a value corresponding to the natural rotation speed of a fan that can be air-conditioned without driving the fan. Is set. When applied to other fans, the protection level Is is set to the difference between the current value leading to element destruction and the current value leading to demagnetization, or a low value.

The embodiment shown in FIGS. 1 to 3 is configured according to the above principle, and its operation will be described below. When an infrared signal such as an operation mode, a set temperature, and an air volume is output from the remote control device 16, the infrared signal is received by the light receiving unit 14 and applied to the control unit 13. The control unit 13 detects the rotation state of the outdoor fan 8 before executing the control according to the received signal, so that the lower-phase switching elements X, Y, Z for a predetermined time T1. Is turned on.

When the outdoor fan 8 is normally driven, as shown in FIG. 2, the two-directional force of arrows A and B sucks outside air and discharges it in the direction of arrow C. At the start of operation, the outdoor fan 8 itself is driven by natural wind. It may be rotating. When the lower phase switching elements X, Y, and Z are turned on and the outdoor fan 8 is rotating at a relatively high speed due to natural wind outside, the motor 8M acts as a generator. As shown by the solid line al, a current I that increases in proportion to time flows. In the case where the rotation speed is low, a current as shown by a broken line a2 which saturates from the middle of the solid line al flows. At this time, a three-phase AC voltage is output from the three operational amplifiers 23, so that the MCU is free of 25 volts.

[0038] Based on the outputs of all the operational amplifiers 23, the MCU 25 checks whether or not the current detection value I exceeds a threshold lb for judging an arm short circuit. , Z are returned to the OFF state, and the abnormality display section 15 indicates that one or more of the upper-phase switching elements U, V, W is abnormal, and stops the air conditioning operation. If the current detection value I is equal to or less than the threshold lb for judging an arm short circuit, it is checked whether or not the current detection value I exceeds the protection level Is. If the current detection value I exceeds the protection level Is, the lower-phase switching elements X, Υ , Z is returned to the off state, and the operation of the refrigeration cycle is started. If the current detection value I is equal to or smaller than the threshold lb for judging an arm short, it is checked whether the current detection value I is a sine wave or 0 for all three phases. Or, if it is not 0, the lower phase switching elements X, Y, and Z are returned to the off state to indicate the force with a short circuit in the winding of the motor or the abnormality in the current detection circuit 11 in the abnormality display section. Displayed at 15 stops the air conditioning operation.

[0039] If the current detection value I is equal to or less than the threshold lb for judging an arm short circuit, equal to or less than the protection level Is, and all three phases are sinusoidal, the lower phase is reached at time T1. The switching elements X, Y, and Z are returned to the off state, and then the upper-phase switching elements U, V, and W are turned on. The switching element U, V, W of the upper phase is returned to the off state if it exceeds, and one or more of the switching elements X, Υ, Z of the lower phase are displayed on the abnormality display section 15. The abnormality is displayed and the air conditioning operation is stopped. If the current detection value I is equal to or less than the threshold lb for judging the arm short circuit, the switching elements U, V, W Is returned to the off state, and the operation of the refrigeration cycle is started.

Since the operation of the refrigeration cycle has been proposed and known, only the general operation will be described. The four-way valve 4 is turned on or off in accordance with the operation mode, and a frequency command for controlling the capacity of the compressor 3 is applied to the inverter 2 in accordance with the air-conditioning load. As a result, in the cooling mode, as indicated by the solid arrow, the refrigerant flows through the path of the compressor 3, the four-way valve 4, the outdoor heat exchanger 5, the expansion valve 6, the indoor heat exchanger 7, the four-way valve 4, and the compressor 3. In the heating mode, as shown by the dashed arrow, in the path of compressor 3 → four-way valve 4 → indoor heat exchanger 7 → expansion valve 6 → outdoor heat exchanger 5 → four-way valve 4 → compressor 3 Refrigerant is circulated

Then, a speed command is given to the speed control circuit 12 so that the air volume is set by the remote control device 16, and the inverter 10 that controls the outdoor fan 8 so that heat exchange according to the air conditioning capacity is performed. Then, the opening degree of the expansion valve 6 is controlled so that the state of the refrigerant in the indoor heat exchange 7 becomes appropriate.

At this time, the switching elements U, V, W, X, Υ, and Z of the inverter 10 are turned on and off in a predetermined order, but the lower-phase switching elements X, Y, and Z are controlled. When turned on, the upper-phase switching elements U, V, W in series connection are turned off, and the capacitor C provided corresponding to the off-state switching elements U, V, W The drive circuit 22 is charged up and supplies drive power for the drive circuit 22.

FIG. 6 is a time chart showing two typical control examples according to the present embodiment. FIG. 6 (a) shows the current when the lower-phase switching elements X, Υ, and Z are turned on. The detected value I is lower than the protection level Is.Figure 6 (b) shows that the current detection value I when the lower-phase switching elements X, Υ, and Z are turned on exceeds the protection level Is. The case is shown.

That is, as shown in FIG. 6 (a), after the control unit 13 starts its operation, the lower-phase switching elements X, Y, and Z are turned on, and the current when the time T1 has elapsed is passed. If the detected value I is equal to or lower than the protection level Is, the lower-phase switching elements X, Υ, and Z are turned off at the time and the upper-phase switching elements U, V, and W are turned on, and the current is turned on. If the detected current value I is not equal to the threshold lb for judging the arm short circuit, the deceleration and stop control of the outdoor fan 8 is executed when the time T1 has elapsed, and the output is stopped when the outdoor fan 8 stops. The drive control of the outdoor fan 8 is performed by controlling the barter 10 and supplying a PWM current to the motor 8M.

On the other hand, as shown in FIG. 6 (b), the lower-phase switching elements X, Y, and Z are turned on after the control unit 13 starts its operation, and the current is If the detected value I exceeds the protection level Is, the stop control of the outdoor fan 8 is executed at that time, and when the control unit 13 starts the operation and the repetition period Tv elapses. If the current detection value I is equal to or lower than the protection level Is, the driving control of the outdoor fan 8 is executed in the same manner as described with reference to FIG.

FIG. 7 is a flowchart showing a specific processing procedure of the MCU 25 when executing the above-described operation, and the processing will be described below. First, in step 31, the data lb, Is, and Tv stored in the EEPROM 24 are read, and in step 32, the lower-phase switching elements X, Υ, and Z are simultaneously turned on. In step 33, the current detection value I Read.

Next, in Step 34, it is determined whether the current detection value I exceeds a threshold lb for determining a short circuit. If the current detection value I is not larger than the threshold lb, the process proceeds to Step 35. If the current detection value I is larger than the threshold lb, the process proceeds to step 52. The current I for three phases can be read simultaneously or one phase at a time.

[0048] In step 35, it is determined whether or not the current detection values I for the three phases are all 0. If not, in step 36, it is determined whether or not the current detection waveforms for the three phases are all sinusoidal. If it is a sine wave, it is determined in step 37 whether or not the current detection value I is greater than the protection level Is. If not, the process proceeds to step 38.

[0049] When it is determined in step 35 that the currents of all three phases are 0, the process proceeds directly to step 38, and in step 36, if one or more of the three phases is not a sine wave. If it is determined, the process proceeds to step 54.

In step 38, it is checked whether or not a predetermined time T1 has elapsed since the lower-phase switching elements X, Υ, and Z were turned on. Repeat the process. When it is determined in Step 38 that the predetermined time T1 has elapsed, the process proceeds to Step 39, where the lower-phase switching elements X, Y, and Z are returned to the off state. Switching elements U, V, and W are turned on, and current detection is performed in step 41. Read out value I. Further, in step 42, it is determined whether or not the current detection value I exceeds the threshold value lb for determining a short circuit. When the value I is larger than the threshold lb, the process proceeds to step 50.

In step 43, it is checked whether or not a predetermined time T1 has elapsed since the upper-phase switching elements U, V, W were turned on, and if not, the processing of steps 41 to 43 is repeated. . When it is determined in step 43 that the predetermined time T1 has elapsed, the process proceeds to step 44, where the upper-phase switching elements U, V, W are returned to the off state, and then compressed in step 45. The operation of the refrigeration cycle is started by operating the machine 3 and the like, and then, in step 46, the start control of the motor 8M is started, and the operation proceeds to a known air conditioning operation.

On the other hand, if it is determined in step 37 that the current detection value I is larger than the protection level Is, the lower-phase switching elements X, Υ, and Z are turned off in step 47 and the next step 48 is performed. Then, the operation of the refrigeration cycle is started by operating the compressor 3 and the like, and after the repetition cycle Tv has passed in step 49, the process returns to the first step 31 and the above process is repeated.

When it is determined in step 42 that the current detection value I exceeds the short-circuit determination threshold lb, the switching elements U, V, and W of the upper phase are turned off in step 50, Subsequently, in step 51, the abnormality display section 15 displays that one or more of the lower-phase switching elements X, Υ, and Z are abnormal, and then in step 56, all devices including the refrigeration cycle are stopped. Perform an abnormal process such as

When it is determined in step 34 that the current detection value I exceeds the short-circuit determination threshold lb, in step 52, the lower-phase switching elements X, Υ, and Z are turned off. In step 53, the abnormal display section 15 displays that one or more of the upper phase switching elements U, V, and W are abnormal, and then stops all devices including the refrigeration cycle in step 56. Perform an abnormal process such as

If it is determined in step 36 that the three phases are not sinusoidal, the switching elements X, Υ, and Z of the lower phase are turned off in step 54, and in step 55, the motor winding is turned off. Indicates that a short circuit has occurred or that the current detection circuit 11 is abnormal, and proceeds to the process of step 56. As described above, the control described with reference to FIGS. 4 to 6 can be performed by the MCU 25 included in the control unit 13 executing the processing illustrated in the flowchart of FIG.

[0057] By force, according to the first embodiment, the lower-phase switching element is turned on for braking in a state where the outdoor fan is rotating at a high speed due to natural wind or for charging the capacitor. In this case, the demagnetization of the permanent magnet of the motor and the destruction of the lower phase switching element due to the overcurrent can be prevented.

Further, in a state where the natural wind is strong, the start of the outdoor fan is stopped to prevent the demagnetization of the motor and the destruction of the switching element, and the compressor is operated while the driving of the outdoor fan is stopped. The air conditioner is operated and the outdoor fan is driven when natural wind stops.This prevents overloading of the refrigeration cycle due to continued operation of the compressor with little ventilation to the outdoor heat exchanger. can do.

By the way, as described as the principle of the present invention, sufficient heat exchange is possible in the outdoor heat exchange 5 if the rotational speed S of the outdoor fan 8 due to natural wind is at least a certain level. In the case where the compressor 3 is driven at a variable speed by the inverter 2, the compressor 3 can perform the power control operation, so that the compressor 3 rotates according to the rotation speed of the outdoor fan 8 due to natural wind. If the number is controlled, the air conditioning operation can be performed without driving the outdoor fan 8.

As described above, if the air conditioning operation is performed without driving the outdoor fan 8, the electric power consumed by the motor 8M is not required, and an energy saving effect can be obtained. In this case, the rotation speed of the outdoor fan 8 is estimated, and based on the estimation result, the rotation speed of the compressor 3 is limited, and the air-conditioning operation can be performed in a range where overload does not occur.

FIG. 8 is a flowchart showing a specific processing procedure of an MCU constituting a control unit as a second embodiment of an air conditioner controlled according to this principle. In this case, the lower phase switching elements X, Υ, and Z are turned on in step 61, the timer T is started in step 62, and the current I is detected in step 63. Then, in step 64, it is determined whether or not the current detection value I is smaller than the protection level Is. If smaller, the process proceeds to step 65, and if not, the process proceeds to step 70. In step 65, it is determined whether or not the time counted by the timer T is equal to or greater than a predetermined value T1. Is repeated. If it is T1 or more, in step 66, for example, the rotational speed r of the outdoor fan 8 is estimated based on the current detection value I at that time.

[0062] Next, in step 67, it is determined whether or not the estimated rotational speed r is lower than the minimum rotational speed rl at which sufficient heat exchange is performed by natural wind. , And normal air-conditioning operation is executed in step 69.

On the other hand, if the estimated rotation speed r is equal to or more than rl in step 67, it is determined in step 73 whether the estimated rotation speed r is lower than r2 set in a larger range. At 74, the start of the outdoor fan 8 is stopped, the power supply frequency corresponding to the upper limit of the rotation speed of the compressor 3 is set to 40 Hz, and the process proceeds to step 72.If the estimated rotation speed r is not lower than r2, In step 75, the start of the outdoor fan 8 is stopped, the power supply frequency is set to 40 Hz corresponding to the upper limit of the rotation speed of the compressor 3, and the process proceeds to step 72.

If the current detection value I is equal to or higher than the protection level Is in step 64, the start of the outdoor fan 8 is stopped in step 70, and the air conditioning operation is performed in step 71 without limiting the rotation speed of the compressor. At step 72, it is determined whether or not a predetermined time Tv has elapsed. At the stage when the predetermined time Tv has elapsed, the process returns to step 61 and the same process is repeated.

[0065] According to the second embodiment, the number of rotations can be estimated without using the rotation position detecting element, and an energy saving effect can be obtained.

[0066] In the above-described second embodiment, the rotation speed of the outdoor fan 8 is estimated, but this rotation speed estimation method can be used for the dehumidifying operation. That is, in the dehumidifying operation, etc., since the rotation speed of the compressor 3 is reduced, the amount of heat exchange in the outdoor heat exchange 5 can be small, so that even if the amount of ventilation to the outdoor heat exchanger 5 is small. good. Therefore, the heat exchange amount (required heat exchange amount) of the outdoor heat exchanger 5 required in the air-conditioning operation is calculated, and it is estimated whether or not it is necessary to drive the outdoor fan 8 according to the required heat exchange amount. It may be determined according to the rotation speed of the outdoor fan 8.

[0067] Usually, the required heat exchange amount in the air conditioner is determined based on the rotational speed of the compressor, the operation mode, and the like as a meter. The rotation speed F of the outdoor fan 8 corresponding to the required heat exchange amount determined here (the rotation speed in a state where the outdoor fan 8 rotates freely by natural wind) is determined and compared with the rotation speed estimation value r. To start the outdoor fan 8. FIG. 9 is a flowchart showing a specific processing procedure of an MCU constituting a control unit as a third embodiment of an air conditioner controlled according to this principle. In this case, the lower-stage switching elements X, Υ, and Z are turned on in step 81, the timer T is started in step 82, and the current I is detected in step 83. Then, in step 84, it is determined whether or not the current detection value I is smaller than the protection level Is. If smaller, the process proceeds to step 85, and if not, the process proceeds to step 91. In step 85, it is determined whether or not the time counted by the timer T is equal to or greater than a predetermined value T1, and if not, the processing of steps 83-85 is repeated. If it is not less than T1, in step 86, the rotational speed r of the outdoor fan 8 is estimated.

Next, in step 87, the required fan rotation speed F of the air conditioner is determined, and then, in step 88, it is determined whether or not the estimated rotation speed r is lower than the required rotation speed F. In this case, start control of the outdoor fan 8 is performed in step 89, and normal air conditioning operation is performed in step 90.

On the other hand, when it is determined in step 84 that the current detection value I is not smaller than the protection level Is, and in step 88, it is determined that the estimated rotation speed r is not lower than the required rotation speed F. In step 91, the start of the outdoor fan 8 is stopped in step 91, the air conditioning operation is performed in step 92, and it is determined whether or not a predetermined time Tv has elapsed in step 93. Return and repeat the same process.

According to the third embodiment, it is possible to estimate the number of rotations without using a rotation position detecting element, and it is possible to obtain an energy saving effect.

In each of the above embodiments, the air conditioner has been described as an embodiment of the refrigeration cycle apparatus. However, the hot water supply having an outdoor unit and a refrigeration cycle configured similarly to the air conditioner is described. Instruments are also being marketed. The present invention can be applied not only to air conditioners but also to other refrigeration cycle devices such as water heaters whose main parts are configured similarly. Industrial applicability

[0073] With the above-described configuration of the present invention, even if the startup is controlled in a state where the fan is rotated by natural wind, the demagnetization of the permanent magnet of the motor and the switching element on the negative side of the inverter are controlled. Destruction can be prevented beforehand. Also, before starting the fan, Can be estimated.

Claims

The scope of the claims

[1] A sensorless motor that drives the fan,

An inverter in which a switching element is connected in a three-phase bridge and supplies three-phase AC power to the motor;

Current detection means for detecting a current flowing through the motor,

At the time of startup, the switching elements for the three phases forming the negative arm of the inverter are turned on, and the current detection value of the current detection means in this on state is set lower than a value determined to be short-circuited to the arm. Control means for returning the three-phase switching elements to an off state and stopping the start when the level is exceeded,

Fan control device with

[2] In the fan control device according to claim 1,

A fan control device including a capacitor that is charged when the negative arm is turned on, as a power supply for a drive circuit that drives three-phase switching elements forming the positive arm of the inverter.

[3] a refrigeration cycle including a compressor, an outdoor heat exchanger and an outdoor fan for promoting the heat exchange;

A sensorless motor that drives the outdoor fan,

Current detection means for detecting a current flowing through the motor,

At the time of startup, the switching elements for the three phases forming the negative arm of the inverter are turned on, and the current detection value of the current detection means in this on state is set lower than a value determined to be short-circuited to the arm. When the level is exceeded, the switching elements for the three phases are returned to the off state, thereby starting the fan to stop the start of the fan, and controlling the wind fan to operate the compressor while the fan is stopped. Control means for stopping the activation of the fan and repeatedly executing the activation control of the fan after a predetermined time has elapsed; and

Refrigeration cycle device equipped with.

[4] a refrigeration cycle including a compressor, an outdoor heat exchanger and an outdoor fan for promoting the heat exchange,

A sensorless motor that drives the outdoor fan,

Current detection means for detecting a current flowing through the motor,

At the time of startup, the three-phase switching elements forming the negative arm of the inverter are turned on, and the fan rotation speed is estimated based on the current detection value of the current detection means in this on state. If the number of rotations is equal to or higher than a predetermined value, the switching elements for the three phases are returned to the off state to control the start of the fan for stopping the start of the fan, and to operate the compressor while the fan is stopped. Control means for executing a wind fan stop control to start the fan, stopping the start of the fan, and repeatedly executing the start control of the fan after a predetermined time has elapsed.

Refrigeration cycle device equipped with.

[5] The refrigeration cycle apparatus according to claim 3,

The control means turns on the three-phase switching elements forming the negative arm of the inverter at the time of start-up, and when the current detection value of the current detection means in this ON state is equal to or more than a value determined to be arm short-circuited. A refrigeration cycle device that keeps the compressor stopped at one time.

[6] The refrigeration cycle apparatus according to claim 4,

[7] The refrigeration cycle apparatus according to claim 3,

The control means monitors the current detection values of the current detection means when the three-phase switching elements forming the negative arm are turned on, and all the current waveforms of the three phases are sine waves. !, Or if the current detection values for all three phases are not approximately 0, A refrigeration cycle device that does not start the compressor or stops its operation as a line abnormality.

[8] The refrigeration cycle apparatus according to claim 4,

The control means monitors the current detection values of the current detection means when the three-phase switching elements forming the negative arm are turned on, and all the current waveforms of the three phases are sine waves. In the case of!, Or in the case where the detected current values of all three phases are not substantially 0, the refrigeration cycle apparatus does not start the compressor or stops its operation as winding abnormality of the motor.

[9] The refrigeration cycle apparatus according to claim 5,

[10] Step of turning on the three-phase switching elements forming the negative arm of the inverter in which the switching elements are connected in a three-phase bridge so as to supply three-phase AC power to the sensorless motor that drives the fan When,

Detecting a current flowing through the motor when the switching elements for the three phases are on;

Estimating the rotational speed of the fan based on the detected current value.