JPS5934935B2 - heat source device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is capable of varying the capacity of a refrigeration cycle heat source device that compresses refrigerant using a compressor for compressing refrigerant and this motor according to the load, and also changing the capacity of the refrigerant cycle heat source device for compressing refrigerant according to the load, and also changing the capacity of the refrigeration cycle heat source device that compresses the refrigerant using a compressor for compressing refrigerant and this motor. This is intended to control the start and stop of the compressor within a predetermined hysteresis width, thereby stabilizing operation, improving lifespan, comfort, and controllability.

Furthermore, by adding an inverter or the like that drives the compressor motor at a frequency higher than the commercial power supply frequency, the aim is to reduce the size of the compressor, the size of the motor, and the weight of the motor while maintaining the same refrigerating capacity.

Conventionally, there has been a method of changing the capacity in stages by changing the number of poles of the compressor motor (2P←4P), but this method has the disadvantage that capacity proportional control cannot be performed according to the load.

Another idea is to operate the compressor motor at variable speed using an inverter or the like to proportionally control the refrigerating capacity, but there are difficulties in operating it (startup and stop control) especially at light loads, and it is difficult to ensure stable operation of the equipment. There were problems with compressor life and vibration.

Hereinafter, the configuration and operation of an embodiment of the present invention will be described based on the accompanying drawings.

FIG. 1 shows an embodiment using a heat source device such as a heat pump type that heats and cools by a refrigeration cycle, and the figure shows an application to a separate air conditioner.

1 is an outdoor unit of a separate air conditioner, 2 is an indoor unit, and the outdoor unit 1 includes a compressor 3, a motor 4 for driving the compressor 3, a four-way valve 5, a capillary tube 6, an outdoor heat exchanger 7, It has an outdoor fan 8.

The indoor unit 2 includes an indoor heat exchanger 9 and an indoor fan 10, and the fan 10 circulates the air in the air-conditioned room to perform heating, cooling, etc.

The four-way valve 5 is used to switch between heating and cooling by switching the direction of refrigerant circulation.

11 is a commercial power supply, 12 is an operation switch, 13 is a motor 4
This is the main power source for the choke input, which is full-wave rectified by a diode group 14 and smoothed by a choke coil 15 and a capacitor 16.

17 is a chopper which receives pulsed power from a control circuit (described later) through terminals 17a and 17b, chops the transistor 18 at a predetermined frequency and duty, and smoothes it with a choke 19 and a capacitor 20. 3 diodes 21 are freewheel diodes, 22 is a diode for protecting the transistor 18.

Reference numeral 23 denotes an inverter, in which transistors 24 to 29 are turned on and off at predetermined intervals, and three-phase power is applied to the motor 4.

Diodes 30-35 are diodes for protecting transistors 24-29.

36 is a control power supply, which includes a transformer 37 and a diode group 3.
8, the voltage is stepped down, full-wave rectified, and smoothed by a capacitor 39.

As described above, the present invention uses the control block described below to control the chopper 17 depending on the load state (refrigeration capacity state).
The voltage applied to the motor is controlled by changing the frequency-duty of the motor 4, and the motor 4 is controlled by changing the driving frequency of the inverter 23 using this voltage.
This control block provides hysteresis in starting and stopping the motor 4, and this control block will be explained below.

The output voltage of the control power supply 36 is taken out from E and F, and the comparator 40 operates based on this voltage.

In the comparator 40, for example, a thermistor for detecting the room temperature of the room heated or cooled by the indoor unit 2 is connected to the terminal 40a, and the terminal voltage is set to +h.

Further, a volume (variable resistor, etc.) for adjusting the room temperature is connected to the terminal 40a, and this terminal voltage is set as Vad.

Comparator 40 calculates the deviation of each terminal voltage, fV
a=Vad-Vth is processed as shown in FIG.

That is, in FIG. 2, when the horizontal axis is the deviation AVa and the vertical axis is the output Va, the following relationship is established.

■ Deviation, +AVa≧+A■During the period of 1, the output Va is proportional to the deviation +AVa.

■Deviation 1. (During the period when Va is 101~-A1, the output V
a is fixed to val and does not change.

■ During the period when the deviation, AV a , < -AV 1, the output Va becomes zero.

■ Next, when the deviation /Na returns from -A■1 to +A-, the output Va switches from zero to Va, and from then on ■
~ ■ Go through the process.

As described above, a dead zone, that is, a hysteresis H is provided during the period from +AV1 to -A1.

This output is output from 41 and enters a comparator 42 of the current limiter.

The comparator 42 has an input terminal 44 of a current sensor 43, and when a current higher than a predetermined current flows, the comparator 42
It has the function of controlling and lowering the output Va of.

Therefore, normally the voltage Va (output in FIG. 2) at the output terminal 41 of the comparator 40 is the output 45 of the comparator 42.
and enters the chopper driver 46.

The chopper driver 46 changes the on/off duty of the outputs 1γa and 1γb under a constant frequency condition, or keeps the on time constant and changes the off time, depending on the input voltage Va (output from the terminal 45).

That is, the output terminals 17a and 17b are controlled by varying the output frequency or by controlling one of them.

Therefore, the chopper 17 is chopped by its transistor 18, and a voltage VOD is taken out between the outputs C and D of the chopper 17 in proportion to the input voltage Va of the chopper driver 46.

That is, the input voltage of the comparator 40, /fva-(
When (Vad-Vth) is large, the output voltage VOD of the chopper 17 is large, and vice versa, it is small.

This means that the output voltage VOD of the chopper 17 is Va in FIG.
This means that the lightning voltage is proportional.

Next is the drive section of the inverter 23, and the chopper 17.
Let the output voltage ■cD be the input 47.

A voltage-to-frequency (VOD f) converter 48 whose output frequency f is taken out from a terminal 49 and enters a ring counter 50 .

The output frequency-divided and controlled by the ring counter 50 is applied to the transistor groups 24 to 29 of the inverter 23 and alternately switched with a phase shift of 120 degrees, and this three-phase power is applied to the motor 4.

1 of the results of driving the compressor at high speed using the circuit shown in Figure 1
Give an example.

FIG. 3 shows an example of about 1.5 horsepower, and the y curve shows the operating torque characteristics of compressor 3, Xl, X2. X3 and the like are characteristics of the torque and rotation speed of the motor 4.

When using the circuit shown in FIG. 1, for example, the comparator 40
input V a d - V th = , (V a
The torque characteristic of the motor 4 by the inverter 23 is x, and the motor 4 rotates at approximately 1 oooorpm, which is the intersection with the y characteristic, which is the operating torque of the compressor 3.

Next, as the room temperature rises, the deviation value of the comparator 40,
(When Va becomes smaller, the motor characteristics become an X2 curve.

If it becomes even smaller, that is, if it exceeds the set value, then
The motor 4 rotates at approximately 2000 rllln as a curved line, and above this point, the motor 4 stops based on the output characteristics of the comparator 40 as shown in FIG.

Thereafter, control is performed according to the characteristics shown in FIG.

Figure 4 shows the characteristics of the refrigerating capacity of compressor 3.
The capacity can be varied in accordance with the rotation speed of the motor 4 shown in the figure.

Note that although a transistor type is used for the chopper 17 and the impark 23, a similar effect can be obtained by using a thyrisk type as well.The chopper 17 is omitted and control is performed using a thyrisk etc. in place of the group of diodes in the control power source 13, and variable DC Power supply V
You may get OD.

Alternatively, the thermistor for detecting the room temperature may be omitted, and the variable capacity knob may be used as an input to the comparator 40 for open loop control.

Moreover, it is natural that the present invention can be applied to any equipment and control method having a refrigeration cycle.

The heat source device of the present invention provides the following excellent effects by providing means for obtaining the hysteresis H shown in FIG.

(1) The compressor 3 including the motor 4 can be smoothly controlled from maximum rotation speed to zero rotation.

That is, in particular, problems with bearings in low-speed rotation, problems with the pressure balance between the inlet and outlet sides of the compressor that forms the refrigeration cycle, and problems with the inverter 2.
It is possible to avoid the problem of unstable operation caused by the lower applied voltage cD in No. 3.

(2) When adopting a lubrication method that can withstand high-speed drive at a frequency higher than the commercial frequency by an inverter, the lubricating oil does not flow sufficiently to the bearings and compression parts of the compressor 3 during low-speed rotation, resulting in a shortened life due to slugs and other problems. It is possible to avoid

(3) When increasing the gain of the comparator 40, the number of times the compressor starts and stops increases at light loads. During control, although the swing in room temperature due to overshoot becomes large, the number of start-stops can be reduced.

(4) Since the drive frequency of the inverter is controlled by the output voltage ■cD of the chopper 17, even if there is a momentary power outage or a sudden change in the setting of the comparator 40, there will be no malfunction due to the voltage tracking type. , can maintain a stable operating state.

(5) By rotating the motor at a frequency higher than the commercial frequency, the motor and compressor can be made smaller, resulting in economical efficiency and resource savings.

[Brief explanation of drawings]

FIG. 1 is an electric circuit diagram of a heat source device according to an embodiment of the present invention, FIG. 2 is a hysteresis control diagram, FIG. 3 is a motor operating characteristic diagram, and FIG. 4 is a compressor performance characteristic diagram. 1... Outdoor unit, 2... Indoor unit, 3... Compressor, 4... Motor,
5...Four-way valve, 6...Capillary tube, 7...Outdoor heat exchanger, 8...Outdoor fan, 9...Indoor Heat exchanger, 10...
...Indoor fan, 11...Commercial power supply, 17...
...Choppa, 23...Impark, 40
, 42...Comparator, 46...Chopper driver, 48...Voltage/frequency converter, 50...Ring counter.

Claims (1)

[Scope of Claims] 1. A compressor for compressing refrigerant, a motor for driving the compressor, a heat exchanger section for absorbing and dissipating heat from the refrigerant compressed by the compressor in a condensing section and an evaporating section, and a refrigerant compressor. A refrigeration cycle is formed by the expansion section, and an inverter power source is used as a power source for the drive motor of the compressor, and the voltage and frequency of the inverter power source is stopped depending on the adjustment of the capacity adjustment knob and the load condition. The compressor is operated at variable speed, and at a predetermined hysteresis width during light load and light capacity.
A heat source device characterized by having a control means for starting and stopping an inverter power supply. 2. As a control means for the inverter that serves as the power source for the motor, the input DC voltage of the impark is controlled according to the load condition, and the output of an oscillator that generates a frequency approximately proportional to this DC voltage is used to control a switching element such as a transistor. The heat source device according to claim 1, further comprising a chopper that operates to drive the motor.