JP4153586B2 - Air conditioner - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an air conditioner that rectifies an AC voltage of a commercial power source and turns on and off the obtained DC voltage to drive a fan motor of an indoor unit.
[0002]
[Prior art]
As this type of blower motor, a PWM DC motor in which a switching circuit called an inverter main circuit and a control circuit for driving the switching circuit are built in a main body of the motor has been used.
FIG. 4 is a circuit diagram showing a control system of the indoor unit that drives the PWM DC motor. In the figure, an indoor control unit 10A is connected to an AC commercial power source 1, and a PWM DC motor 20 is connected to the indoor control unit 10A.
[0003]
10 A of indoor control parts are provided with the full wave rectifier circuit 11, the commercial power source 1 is connected between the alternating current terminals, and the smoothing capacitor 12 is connected between direct current terminals. Accordingly, a high DC voltage V _H corresponding to the AC voltage of the commercial power supply 1 is generated at both ends of the smoothing capacitor 12. This DC voltage V _H is supplied to the PWM DC motor 20 as a motor driving power source. A switching power supply circuit 13 known as a DC-DC converter is connected to both ends of the smoothing capacitor 12.
[0004]
This switching power supply circuit 13 converts the DC voltage V _H into AC and then converts it into a low-voltage AC voltage, and rectifies the AC voltage to generate a low-voltage DC. 14 and the smoothing capacitor 15 are connected, and a stabilized low-voltage DC voltage V _L is obtained at both ends of the smoothing capacitor 15. The DC voltage _VL is supplied as an operating power source for a microcomputer unit (hereinafter abbreviated as MCU) 16A and also as an operating power source for a motor drive IC 22 described later. Moreover, the input voltage detector 17 which detects the alternating voltage of the commercial power source 1 is provided, and the detected value is added to MCU16A. An abnormality display lamp 18 is connected to the MCU 16A.
[0005]
The PWM DC motor 20 includes a switching circuit 21 formed by connecting transistors in a three-phase bridge. Both ends of the smoothing capacitor 12 described above are connected to a DC input terminal, and a brushless motor 23 for a three-phase fan is connected to an AC output terminal. Has been. The blower brushless motor 23 has a magnet rotor, and in order to detect a relative position to the armature winding, a voltage signal induced in the armature winding is used as a magnetic pole position detection signal p _det to drive the motor drive IC 22. Have feedback. The motor drive IC 22 applies PWM signals to the armature windings of the brushless motor 23 for the blower by turning on and off each switching element of the switching circuit 21 in accordance with the rotational speed command n _ref output from the MCU 16A. Further, the motor drive IC 22 obtains the actual rotational speed from the position detection signal p _{det of} the blower brushless motor 23 and feeds it back to the MCU 16A as the rotational speed signal n _fb . The switching circuit 21 and the motor drive IC 22 constituting the PWM DC motor 20 are built in the motor body of the brushless motor 23 for the blower.
[0006]
With the above configuration, when the commercial power supply 1 supplies a voltage of AC 100 V, a DC voltage V _{H of} about 141 V is applied to the PWM DC motor 20. Further, by smoothing the output of the switching power supply circuit 13 by the smoothing capacitor 15, a voltage of DC 5 V is supplied as an operating power supply for the MCU 16 </ b> A and the motor drive IC 22. The MCU 16A outputs the rotational speed command n _ref while monitoring the rotational speed signal n _fb so as to obtain the air conditioning load or the set rotational speed, and applies it to the motor drive IC 22. The motor drive IC 22 controls on / off of each switching element of the switching circuit 21 so as to synchronize with the magnetic pole position detection signal p _det of the blower brushless motor 23 and to output a PWM voltage according to the rotational speed command n _ref. To do. Further, the MCU 16A determines whether or not it is connected to the commercial power source 1 having a voltage corresponding to the rated voltage based on the detection value of the input voltage detector 17, and when connected to a power source not corresponding to the rated voltage, the connection error occurs. The state is displayed on the abnormality display lamp 18.
[0007]
[Problems to be solved by the invention]
The above-described PWM DC motor 20 is also called a high-voltage PWM DC motor because a remarkably high voltage is applied as compared with, for example, a low-voltage PWM DC motor operated by a DC 12 V DC power supply. Therefore, as long as the indoor control unit 10A is connected to the commercial power source 1, a high-voltage DC voltage is applied to the PWM DC motor 20, and a slight leakage current flows through the switching circuit 21. For this reason, even if the air-conditioning operation is stopped, about 1 to 2 W of power is continuously consumed.
[0008]
The present invention has been made to solve the above problems, and a first object thereof is to provide an air conditioner capable of suppressing power consumption during operation stop.
[0009]
[Means for Solving the Problems]
The invention according to claim 1
Rectifying means for rectifying the AC voltage of the commercial power supply and outputting a DC voltage;
Switching means for turning on and off the DC voltage output from the rectifying means to supply to the fan motor;
Voltage converting means for converting the DC voltage output from the rectifying means into a low-voltage DC voltage;
Control means for controlling the switching means so that a pulse width modulation voltage having a duty ratio according to a rotational speed command is supplied to the blower motor, using the DC voltage output from the voltage conversion means as a drive power supply;
Opening and closing means provided in a DC voltage path for the control means;
Using the DC voltage output from the voltage conversion means as a driving power supply, receives a start command for air conditioning operation, outputs the rotation speed command to the control means, and controls to open the opening / closing means when the air conditioning operation is stopped. A computer unit;
It is an air conditioner equipped with.
[0010]
According to the present invention, when the air-conditioning operation including standby is stopped, the DC voltage input path to the control unit that controls the switching unit that supplies the pulse width modulation voltage to the blower motor is opened. An effect that power consumption can be suppressed is obtained.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on preferred embodiments shown in the drawings.
FIG. 1 is a circuit diagram showing a configuration of an embodiment of an air conditioner according to the present invention. In FIG. 1, the same elements as those in FIG. To do. This embodiment also shows a control system of a brushless motor for a compressor. Here, a voltage doubler rectifier circuit 34 is connected to the commercial power source 1 via a pair of contacts 31 a of the power relay 31 and a noise filter 32. The power relay 31 is energized during air-conditioning operation and closes the contact 31a to supply operating power to the subsequent circuit. The noise filter 32 causes noise associated with on / off of the switching circuit or the like to the commercial power source 1 side. This is to prevent leakage. The voltage doubler rectifier circuit 34 includes two intermediate capacitors connected in series, charges different intermediate capacitors in the positive half cycle and the negative half cycle, and smoothes the sum voltage of these intermediate capacitors. 35.
[0012]
Both ends of the smoothing capacitor 35 are connected to a DC input terminal of a switching circuit 36 called an inverter main circuit formed by connecting transistors to a three-phase bridge, and a three-phase compressor brushless motor 38 is connected to the AC output terminal. Yes. The compressor brushless motor 38 has a magnet rotor, and in order to detect a relative position with respect to the armature winding, a motor drive using a voltage signal induced in the armature winding as a magnetic pole position detection signal P _det. Feedback is provided to the circuit 37. The motor drive circuit 37 applies a PWM signal to the armature winding of the brushless motor 38 for the compressor by turning on and off each switching element of the switching circuit 36 according to the rotational speed command N _ref output from the MCU 16B. The motor drive circuit 37 further obtains the actual rotational speed from the position detection signal P _det of the brushless motor 38 for the compressor, and feeds it back to the MCU 16A as the rotational speed signal N _fb .
[0013]
On the other hand, a normally open contact 41a of a first relay 41 as an open / close control means is connected to one path for supplying a DC voltage generated at both ends of the smoothing capacitor 12 of the indoor control unit 10B to the PWM DC motor 20. The switching power supply circuit 13 outputs the drive voltage of the MCU 16B and the drive voltage of the motor drive IC 22 as control means from separate output terminals. A smoothing capacitor 15 is connected to one of the output terminals via a backflow preventing diode 14, and a low-voltage DC voltage V _L1 smoothed by the smoothing capacitor 15 is supplied as an operating power source for the MCU 16 </ b> B. Further, a smoothing capacitor 44 is connected to the other output terminal via a normally open contact 42a of the second relay 42 and a backflow preventing diode 43, and the low-voltage DC voltage V _L2 smoothed by the smoothing capacitor 44 is connected. Is supplied as an operating power source for the motor drive IC 22.
[0014]
One end of the first relay 41 is connected to the DC output terminal of the MCU 16 </ b> B, and the other end of the first relay 41 is connected to one end of the second relay 42. The other end of the second relay 42 is connected to the collector of the transistor 45, and the emitter of the transistor 45 is grounded. The MCU 16B supplies the base current of the transistor 45.
[0015]
A temperature fuse 39 is provided that blows due to overheating of the brushless motor 38 for the compressor caused by a large input current or overheating of the connector connected to the commercial power supply 1, and the MCU 16 </ b> B excites the power supply relay 31 through the temperature fuse 39. It is configured to do.
[0016]
The operation of the present embodiment configured as described above will be described below with reference to the flowchart of FIG. 2, particularly focusing on the differences from the conventional apparatus shown in FIG. 4.
First, while the air conditioning operation is stopped, the AC voltage of the commercial power supply 1 is full-wave rectified by the full-wave rectifier circuit 11, smoothed by the smoothing capacitor 12, and applied to the switching power supply circuit 13. The switching power supply circuit 13 has two output terminals with respect to the ground point, and the DC voltage of one output terminal is applied to the smoothing capacitor 15 via the diode 14, and the stabilized DC voltage V _L1 is applied to the MCU 16B. Supplied. Therefore, as long as the air conditioning unit is connected to the commercial power source 1 by a connector or the like, the MCU 16B continues to operate at all times. At this time, the MCU 16B maintains its base current at zero in order to turn off the transistor 45. Accordingly, both the first relay 41 and the second relay 42 are brought into a non-excited state, and the contacts 41a and 42a remain open. Further, during the stop of the air-conditioning operation, the MCU 16B also keeps the contact 31a in an open state by deactivating the power relay 31.
[0017]
Accordingly, the supply path of the DC voltage V _H to the switching circuit 21 constituting the PWM DC motor 20 is blocked by the contact 41a. Further, since the direct current voltage output from the other output terminal of the switching power supply circuit 13 and smoothed by the smoothing capacitor 44 via the diode 43 is also cut off by the contact 42a, the motor drive IC 22 constituting the PWM direct current motor 20 is prevented. Thus, the DC voltage V _L2 is not supplied. Furthermore, the AC voltage of the commercial power source 1 is not supplied to the circuit after the noise filter 32 by opening the contact 31a. As a result, the power consumption during operation stop can be suppressed to substantially zero.
[0018]
Next, when a command for starting the air conditioning operation is applied to the MCU 16B through a path (not shown), the MCU 16B supplies a base current to the transistor 45 to turn on the transistor 45. As a result, both the first relay 41 and the second relay 42 are excited, the DC voltage V _H is supplied to the switching circuit 21 constituting the PWM DC motor 20, and the DC voltage V _L2 is supplied to the motor drive IC 22. Thereby, the same operation as described with reference to FIG. 4 is performed.
[0019]
When an air conditioning operation start command is applied to the MCU 16B, the MCU 16B excites the power supply relay 31 to close the contact 31a. As a result, a DC voltage that is approximately twice the amplitude of the AC voltage of the commercial power supply 1 is output from the voltage doubler rectifier circuit 34, smoothed by the smoothing capacitor 35, and applied to the switching circuit 36.
[0020]
At this time, the MCU 16B outputs the rotational speed command N _ref while monitoring the rotational speed signal N _fb so as to obtain the rotational speed according to the air conditioning load, and applies it to the motor drive circuit 37. The motor drive circuit 37 turns on each switching element of the switching circuit 36 so that a PWM voltage is output in synchronization with the magnetic pole position detection signal P _det of the compressor brushless motor 38 and according to the rotational speed command N _ref. Control off. Further, the MCU 16B determines whether or not the AC voltage of the commercial power source 1 exceeds a reference value set in advance to determine overvoltage based on the detection value of the input voltage detector 17 serving as voltage detection means. When the value is exceeded, the base current of the transistor 45 is cut off, the transistor 45 is turned off, and the first relay 41 and the second relay 42 are turned off. As a result, even if there is a possibility that the air conditioning unit is erroneously connected to an AC power supply having a different voltage, it is possible to employ a relatively low withstand voltage IC or the like, and to reliably protect the IC or the like constituting the control unit. be able to.
[0021]
On the other hand, in this embodiment, when the connector for the compressor brushless motor 38 or the commercial power supply 1 is overheated, the thermal fuse 39 is blown, so that the power relay 31 is de-energized and the contact is opened. The operation of the machine brushless motor 38 is stopped. In this case, the MCU 16B has a function of determining whether or not the thermal fuse 39 is blown. When it is determined that the fuse is blown, the base current of the transistor 45 is cut off and the contact 41a and the contact 42a are opened. As a result, both the DC voltage V _H for the switching circuit 21 of the PWM DC motor 20 and the DC voltage V _L2 for the motor drive IC 22 are cut off when the brushless motor 38 for the compressor accompanying the melting of the temperature fuse 39 is stopped, which is useless. While avoiding power consumption, the motor drive IC 22 can be reliably protected.
[0022]
FIG. 2 is a flowchart showing a specific processing procedure for controlling the first relay 41 and the second relay 42 among various functions provided in the MCU 16B. In the figure, it is determined whether or not the operation start command is given in step 101 or the operation is continued, and if the operation start command is given or if the operation is continuing, step 102 The first relay 41 and the second relay 42 are excited to close the normally open contact point 41a and the contact point 42a, and the operating voltages of the brushless motor 23 for the blower and the motor drive IC 22 are supplied. In the next step 103, a rotation speed command n _ref is given to the motor drive IC 22 to control the rotation speed of the blower brushless motor 23. In the next step 104, whether or not the voltage supplied from the commercial power source 1, that is, the input voltage deviates from a reference value for determining overvoltage, that is, whether or not it exceeds 130V if it is a 100V model, 200V If it is a model, it is determined whether or not it is 170 V or less. If these reference values are not deviated, it is determined in step 105 whether or not the thermal fuse 39 has blown. If not, step 101 is determined. Return to the process.
[0023]
On the other hand, if it is determined in step 101 that the operation start command is not given and the operation is not continued, an operation stop command, that is, a zero rotation speed command n _ref is output in step 106. In step 107A, it is determined whether or not the blower brushless motor 23 has been stopped based on the feedback rotation speed signal n _fb, which is also referred to as the rotation speed return, and the processing in steps 101 to 107A is repeated until it stops. If it is determined that the blower brushless motor 23 has stopped, the first relay 41 and the second relay 42 are de-energized in step 109 in step 108, and the normally open contact point 41a and contact point 42a are opened. The supply of the operating voltage of the brushless motor 23 for the blower and the motor drive IC 22 is cut off, and the processing returns to Step 101. If it is determined in step 104 that the input voltage is outside the reference value for determining overvoltage or undervoltage, or if it is determined in step 105 that the thermal fuse 39 has blown, the process proceeds to step 108. The first relay 41 and the second relay 42 are de-energized and the normally open contact point 41a and the contact point 42a are opened to cut off the supply of the operating voltage of the brushless motor 23 and the motor drive IC 22 for the blower. Return to processing.
[0024]
Incidentally, the rotational speed command n _ref MCU16B in the above embodiment the motor drive IC 22, the rotation speed command N _ref to the motor drive circuit 37 has been described to give, respectively, instead of these rotational speed command The present invention can also be applied to a configuration in which an on-duty ratio command is output and the motor drive IC 22 and the motor drive circuit 37 respectively control the switching circuit 21 and the switching circuit 36 according to the on-duty ratio command. .
[0025]
FIG. 3 is a flowchart showing a specific processing procedure of the MCU 16B corresponding to the second embodiment of the present invention. In the figure, the processing in steps 101 to 106 and step 108 is exactly the same as that described in FIG. This embodiment is different in that the process of step 107B is executed instead of the process of step 107A in FIG. That is, if an instruction to stop the operation of the blower brushless motor 23 is output in step 106, the blower brushless motor 23 stops after a lapse of a certain time according to the characteristic. Therefore, a time until the stop after the operation stop command is output is set in advance, and it is determined in step 107B whether or not the set time has elapsed, and when it is determined that the time has elapsed, the process proceeds to step 108 Like that. As a result, substantially the same control as shown in FIG. 2 is performed.
[0026]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the effect which can suppress the power consumption during the stop of the air-conditioning driving | operation including the time of standby is acquired.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing a configuration of an embodiment of an air conditioner according to the present invention.
FIG. 2 is a flowchart showing a main processing procedure of the microcomputer unit constituting the embodiment shown in FIG. 1;
FIG. 3 is a flowchart showing another embodiment of the air conditioner according to the present invention, using main processing procedures of the microcomputer unit.
FIG. 4 is a circuit diagram showing a control system of an indoor unit that drives a PWM DC motor constituting a conventional air conditioner.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Commercial power supply 10B Indoor control part 11 Full wave rectifier circuit 12,15,44 Smoothing capacitor 13 Switching power supply circuit 16B Microcomputer unit (MCU)
20 PWM DC motor 21 Switching circuit 22 Motor drive IC
23 Brushless motor 31 for blower 31 Power supply relay 34 Voltage doubler rectifier circuit 36 Switching circuit 37 Motor drive circuit 38 Brushless motor 41 for compressor 41 First relay 42 Second relay 45 Transistor

Claims (2)

Rectifying means for rectifying the AC voltage of the commercial power supply and outputting a DC voltage;
Switching means for turning on and off the DC voltage output from the rectifying means to supply to the fan motor;
Voltage converting means for converting the DC voltage output from the rectifying means into a low-voltage DC voltage;
Control means for controlling the switching means so that a pulse width modulation voltage having a duty ratio corresponding to a rotational speed command is supplied to the blower motor, using a DC voltage output from the voltage conversion means as a drive power supply;
Opening and closing means provided in a DC voltage path for the control means;
A microcomputer unit that receives the DC voltage output from the voltage conversion means as a drive power supply, receives an air conditioning operation start command, outputs the rotational speed command to the control means, and opens the opening / closing means when the air conditioning operation is stopped When,
Air conditioner equipped with. The air conditioner according to claim 1, further comprising an opening and closing means in a DC voltage path to the switching means,
The microcomputer unit opens the two opening / closing means when the air-conditioning operation is stopped.

Images