JPH05118617A - Controller of air conditioner - Google Patents

Abstract

PURPOSE:To protect a compressor by converting the voltage waveform of a commercial electric power source into pulse signals and taking in this pulse signal from an electric power interruption port and detecting instantaneous power failure due to a dropped pulse signal, counting the duration time of power failure and starting a delay timer to delay restarting when the duration time of power failure goes over a standard value. CONSTITUTION:When a commercial electric power fails instantaneously, a microcomputer 2 is backed up by the capacitor 6 in a rectifying circuit 1 and maintains normal action. A pulse signal conversion circuit 3 converts the wave form of the commercial electric power into pulse signal and it is inputted to an electric power interruption terminal of a microcomputer control section 2. The microcomputer control section 2 detects omission of pulse signal that is inputted to the microcomputer controls section 2, and when it judges an instantaneous power failure it drives a counter 7. When the value of the counting exceeds a reference value, a delay timer 10 is started, and it delays the restarting of a compressor 4 by the set delay time of a delay timer 10. With this arrangement locking of the motor of the compressor and heat generation by overloading electric current are prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an air conditioner, and more particularly to restart protection in the event of a momentary power failure of a commercial power source.

[0002]

2. Description of the Related Art Conventionally, when an instantaneous power failure of a commercial power source occurs, the microcomputer control unit is backed up by a large-capacity capacitor inserted in the power supply circuit and malfunctions without being affected by an instantaneous power failure of about ten and several cycles. However, the compressor goes into a stopped state due to a momentary power failure for several cycles, during which the microcomputer control unit continues to issue a command to operate the compressor, and the compressor immediately after the momentary power failure of commercial power is restored. It is set to restart. However, when the compressor is stopped, a high pressure difference remains on the high pressure side and the low pressure side of the refrigerant circuit until a certain period of time elapses, and if the compressor is restarted as it is, the load on the compressor motor increases, The compressor motor may be locked, the overcurrent relay installed in the compressor may operate, the contacts of the overcurrent relay may seize, and as a result, heat generated by overcurrent may cause damage to the compressor motor. ing.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems of the prior art. In the case where the compressor is stopped by the momentary power failure of the commercial power supply and is restarted by the microcomputer controller immediately after the recovery from the momentary power failure. Another object of the present invention is to provide a control device for an air conditioner that delays the restart of the compressor for a certain period of time to reduce the pressure difference between the high pressure side and the low pressure side of the compressor and then restarts the compressor.

[0004]

In order to achieve the above object, a pulse signal conversion circuit for converting a voltage waveform of a commercial power supply into a pulse signal and a pulse signal taken in from a power supply interrupt port of a microcomputer control unit A counter that detects an instantaneous power failure due to missing and counts the instantaneous power failure time by the number of interrupt searches during the instantaneous power failure, a comparison circuit that compares the detected instantaneous power failure time value with a preset reference value, and a delay timer When the instantaneous power failure is detected and the instantaneous power failure time value exceeds the reference value, the restart of the compressor is delayed by a delay timer and controlled.

[0005]

According to the above configuration, the voltage waveform of the commercial power supply is converted into a pulse signal by the pulse signal conversion circuit, is taken into the microcomputer control unit from the power supply interrupt port, and the pulse signal is confirmed by the interrupt check of the microcomputer control unit. The instantaneous power failure time is detected by detecting a momentary power failure due to the lack of a pulse signal, counting the number of interrupt searches operated by the clock of the microcomputer control unit during the momentary power failure by the counter, and measuring the instantaneous power failure time. By comparing with the reference value stored in the memory, driving the delay timer when exceeding the reference value, and restarting the compressor after a certain period of time,
It is possible to prevent the compressor from being restarted in the overload state immediately after the stop, and to prevent the compressor motor from being locked and the heat generation due to the overload current.

[0006]

Embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing the configuration of the present invention. A rectifier circuit 1 for rectifying a commercial power source, a microcomputer control unit 2, a pulse signal conversion circuit 3 for converting a voltage waveform of the commercial power source into a pulse signal, and a compressor. 4 and a compressor drive circuit 5 for driving the compressor 4. When the compressor 4 is operating and an instantaneous power failure of about 10 cycles occurs with the commercial power supply, the microcomputer controller 2 backs up the instantaneous voltage drop by the large-capacity capacitor 6 provided in the rectifier circuit 1. The normal operation is maintained until the momentary power failure with commercial power is recovered. On the other hand, the compressor 4 stops when a momentary power failure that exceeds several cycles of the commercial power source occurs, and when the momentary power failure ends, the compressor 4 is restarted immediately by a start signal from the microcomputer control unit 2.

When the compressor 4 is in operation, the refrigerant gas pressure on the discharge side is kept high and the refrigerant gas pressure on the suction side is kept low. When the compressor 4 is stopped due to an instantaneous power failure, the refrigerant gas on the discharge side is kept in the refrigerant circuit. It gradually flows to the suction side through the evaporator, expansion valve, and condenser, and also flows inside the compressor 4 to the suction side, but its flow rate is small, and when the momentary power failure ends, the pressure difference between the discharge side and the suction side is When it remains large, the compressor motor is overloaded when the compressor 4 is restarted by the start signal from the microcomputer control unit 2. In order to avoid this state, in the present invention, the voltage waveform of the commercial power supply is taken out from the rectifier circuit 1, converted into a pulse signal by the pulse signal conversion circuit 3, and input to the power supply interrupt terminal of the microcomputer control unit 2 and then by the microcomputer control unit 2. It is confirmed by the interrupt search that the commercial power supply is normal because the pulse signal is continuing, and when a momentary power failure occurs, the lack of the pulse signal from the pulse signal conversion circuit 3 is detected and it is determined that the power failure has occurred. The momentary power failure time is measured by counting the number of interrupt searches of the microcomputer controller 2 during the momentary power failure by the counter 7, and the momentary power failure time when the preliminary compressor 4 stops is obtained by actual measurement and the like. The reference value stored in the memory 8 and the measured instantaneous power failure time are compared by the comparison circuit 9, and if the measured instantaneous power failure time exceeds the reference value, the delay time is delayed. Drive the motor 10 and shut off the restart signal from the microcomputer control unit 2 for a certain period of time, wait until the pressure difference between the discharge side and the suction side does not interfere with the restart, and after the time is up, restart the compressor 4 I'm trying to restart.

FIG. 2 is a flow chart showing the details of the present invention. During the operation of the compressor 4, a momentary power failure of the commercial power source is detected from the lack of the pulse signal entering the power source interrupt port of the microcomputer control unit 2, and during the momentary power failure. The momentary power failure time is counted from the number of interrupt searches (21), and when the momentary power failure time exceeds the reference value t (22), the operation stop state of the compressor 4 is confirmed (23),
The delay timer 10 is started when the compressor 4 is in a stopped state (24), and after a certain period of time elapses (25), the compressor 4 is restarted by a signal from the microcomputer control unit 2 (26). I am trying.

[0009]

As described above, in the present invention, when an instantaneous power failure of the commercial power source occurs, the instantaneous power failure is detected and the instantaneous power failure time is counted, and the instantaneous power failure time exceeds the time until the compressor motor is stopped. In this case, the restart of the compressor can be delayed by the delay timer for a certain period of time to avoid restarting the compressor in the overload state immediately after the momentary power failure, and prevent the compressor motor from locking and heat generation due to overload current. .

[Brief description of drawings]

FIG. 1 is a principal block diagram showing a configuration of the present invention.

FIG. 2 is a flow chart showing details of the present invention.

[Explanation of symbols]

 1 Rectifier circuit 2 Microcomputer control unit 3 Pulse signal conversion circuit 4 Compressor 5 Compressor drive circuit 6 Capacitor 7 Counter 8 Memory 9 Comparison circuit 10 Delay timer

Claims (1)

[Claims] 1. A pulse signal conversion circuit for converting a voltage waveform of a commercial power supply into a pulse signal, and the same pulse signal is taken from a power supply interrupt port of a microcomputer control unit to detect an instantaneous power failure due to a missing pulse signal, and an interrupt during the instantaneous power failure. It is equipped with a counter that counts the instantaneous power failure time according to the number of searches, a comparator circuit that compares the detected instantaneous power failure time value with a preset reference value, and a delay timer. When the value exceeds a reference value, the restart of the compressor is controlled by delaying it for a certain period of time by a delay timer to control the air conditioner.