JP3492756B2 - Refrigeration cycle device - Google Patents

Abstract

PURPOSE:To provide a freezing cycle apparatus of which the power supply circuit can be made small, and of which the power consumption cost can be reduced. CONSTITUTION:In a power supply circuit for a freezing cycle apparatus, a switching power supply is provided which uses a high frequency transformer 32 having at least five secondary wirings, the three secondary wirings 32b to 32d thereamong supplying power to a first drive circuit 33, a second drive circuit 34, and a third drive circuit 35, the secondary wiring 32e supplying power to a fourth drive circuit 36 and an inverter control circuit 37, and the secondary winding 32f supplying power to a freezing cycle control circuit 38 for common use thereof.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration cycle apparatus having an inverter circuit capable of changing the rotation speed of a compressor. 2. Description of the Related Art In general, a refrigeration cycle device used for an air conditioner, a refrigerator and the like is disclosed in
As disclosed in Japanese Unexamined Patent Publication No. 0064/2004 and the like, the number of revolutions of the compressor is changed using an inverter circuit, and the compressor is operated at an optimum refrigeration capacity according to the load state, thereby improving the energy saving effect and improving comfort. We are trying to improve. [0003] A conventional refrigeration cycle apparatus will be described below. FIG. 2 shows a block diagram of a conventional refrigeration cycle apparatus. As shown in FIG. 2, a refrigeration cycle is configured by sequentially communicating a compressor 1, a condenser 2, a capillary tube 3, an evaporator 4, and the like. That is, the refrigerant is caused to flow in the direction indicated by the arrow in the freezing operation. [0004] Reference numeral 10 denotes an AC power supply, which is a single-phase 100V, single-phase 200V, three-phase 200V generally used in commerce.
V and the like. A forward conversion circuit 11 receives the AC power supply 10 as input and outputs DC. Reference numeral 12 denotes an inverse conversion circuit, which is a forward conversion circuit 11
Is input, and is further converted into AC power of an arbitrary frequency and voltage by a switching operation. A waveform (for example, a PWM waveform or the like) for generating the AC power is generated by the inverter control circuit 13, and further operates the inverse conversion circuit 12 via the drive circuit 14. Reference numeral 15 denotes a refrigeration cycle control circuit which receives inputs of a room temperature sensor 16, a pipe sensor 17, an outside air temperature sensor 18 and the like, determines the current state of the refrigeration cycle, and determines an optimum frequency according to the situation. , To the inverter control circuit 13 as a command signal. Reference numeral 19 denotes a power supply circuit which receives the DC power of the forward conversion circuit 11 and supplies power to the inverter control circuit 13 and the drive circuit 14. Reference numeral 20 denotes a second power supply circuit, which inputs the AC power supply 10 and supplies power to the refrigeration cycle control circuit 15. Generally, a switching power supply using a high-frequency transformer is used for the power supply circuit 19, and a power supply using a low-frequency transformer is often used for the second power supply circuit. Reference numeral 21 denotes first insulating means, which is provided between the inverter control circuit 13 and the drive circuit 14, and generally uses a photocoupler. 22 is the second
It is an insulating means provided between the refrigeration cycle control circuit 15 and the inverter control circuit 13, and generally a photocoupler is often used. The power supply circuit 19 will be described in more detail. The power supply circuit 19 is configured as shown in, for example, Japanese Utility Model Publication No. 4-24792. In the above publication, the secondary winding of the switching power supply and the rectifying
Three of which are independently supplied to each of the three switching element drive circuits of the upper bridge of the three-phase bridge-connected switching elements, and the other one of the three-phase bridge-connected switching elements. The power is commonly supplied to the drive circuits of the three switching elements of the lower bridge, and the remaining one is also supplied to the inverter control circuit. However, in the above-mentioned conventional configuration, since the power supply circuit 19 and the second power supply circuit 20 need to be provided, the size of the device is increased, the input is increased, and the power consumption is increased. In addition, there is a problem that the cost is further increased. [0011] In addition, applying Japanese Utility Model Publication No. 4-24792, a secondary winding is newly added, and a refrigeration cycle control circuit 1 is provided.
Even if it is supplied to 5, it is apparent that at least six secondary windings are required after all, and the device becomes large in size. In recent years, with the advancement of inverter control methods, it has become necessary to detect the voltage and current states of the inverse conversion circuit 12 in detail. For example, a method has been proposed in which a voltage ripple in a DC section is detected and the output waveform is controlled by feedforward, and a method in which the output waveform is optimized so that the current in the DC section is minimized. In order to realize such control, it is difficult in a conventional configuration in which the inverter control circuit 13 and the drive circuit 14 are insulated from each other, and even if it is realized, it is very expensive. The present invention solves the above-mentioned problems, and provides a refrigeration cycle apparatus which can reduce the size of the apparatus, reduce power consumption, reduce the cost, and withstand advanced control. Aim. In order to achieve this object, a refrigeration cycle apparatus according to the present invention comprises a compressor, a forward conversion circuit for converting an AC input to DC, and a DC for the forward conversion circuit. A reversing circuit for converting to alternating current by a switching element connected in a three-phase bridge, a power supply circuit to which direct current of the forward converting circuit is input, an inverter control circuit for controlling the reversing circuit, and a refrigerating machine including the compressor In a refrigeration cycle apparatus having a refrigeration cycle control circuit for controlling a cycle, the power supply circuit is connected to a high-frequency transformer having a primary winding and at least five secondary windings, and an output side of the forward conversion output circuit. A switching circuit that is connected in series with the primary winding of the high-frequency transformer and performs on / off at a high frequency; and rectifies and outputs an AC output generated in each of the secondary windings. A rectifying / smoothing circuit for smoothing and smoothing, and three rectifying / smoothing circuits of three secondary windings of the secondary windings of the high-frequency transformer. The output of the rectifying / smoothing circuit of another one of the secondary windings of the high-frequency transformer is supplied to each of the drive circuits independently of each other. Bridge 3
Power supply to the inverter control circuit as well as to the drive circuit of the switching elements in common,
The output of the rectifying / smoothing circuit of the remaining one secondary winding of the secondary winding of the high-frequency transformer is supplied to the refrigeration cycle control circuit. With this configuration, the power supply circuit of the refrigeration cycle control circuit and the power supply circuit required for the inverter including the inverter control circuit can be used in common, so that the power supply circuit can be downsized and the device can be downsized. The input can be reduced, the power consumption can be reduced, and the cost can be reduced. Also, one power supply output is commonly supplied to the drive circuits of the three switching elements of the lower bridge, and power is also supplied to the inverter control circuit. The side and the ground line are shared, and direct detection of DC voltage can be easily realized by using A / D conversion of a microcomputer, so that inverter control can be advanced easily and at low cost. Will be able to respond. (Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram of a refrigeration cycle apparatus according to one embodiment of the present invention. In FIG. 1, reference numeral 30 denotes a forward conversion circuit, which is a three-phase commercial AC power supply (symbols R, S, T in the figure)
, And bridge-connected diodes D1 to D6
, And smoothed by the capacitor C1 to be converted into a DC voltage. Reference numeral 31 denotes an inverse conversion circuit, which is a switching element Q1.
To Q6 are bridge-connected to convert the DC output of the forward conversion circuit 30 into a three-phase AC whose frequency and voltage are adjusted. The compressor 1 is operated by the three-phase alternating current to control its capacity. Reference numeral 32 denotes a high-frequency transformer, and 33 denotes a switching circuit. One end of a primary winding 32a of the high-frequency transformer 32 is connected to the plus side of the output of the forward conversion circuit 30. The other end is connected to one end of the switching circuit 33, and the other end of the switching circuit 33 is connected to the negative side of the forward conversion circuit 30. Reference numerals 32b to 32f denote two of the high frequency transformers 32.
Next winding. The secondary winding 32b is rectified and smoothed via a diode D7 and a capacitor C7,
3 is supplied with power. The first drive circuit 33 operates the switching element Q1 of the inverse conversion circuit 31. The secondary winding 32c is rectified and smoothed via the diode D8 and the capacitor C8, and supplies power to the second drive circuit 34. The second drive circuit 34 operates the switching element Q3 of the inverse conversion circuit 31. Also 2
The secondary winding 32d is rectified and smoothed via the diode D9 and the capacitor C9, and supplies power to the third drive circuit 35. The third drive circuit 35 operates the switching element Q5 of the inverse conversion circuit 31. The secondary winding 32e includes a diode D10,
The power is rectified and smoothed via the capacitor C10 and power is supplied to the fourth drive circuit 36 and the inverter control circuit 37.
The fourth drive circuit 36 operates the switching elements Q2, Q4, Q6 of the inverse conversion circuit 31. The secondary winding 32
f is rectified and smoothed via the diode D11 and the capacitor C11, and supplies power to the refrigeration cycle control circuit 38. The refrigeration cycle control circuit 38 is supplied with a room temperature sensor 16, a pipe sensor 17, an outside air temperature sensor 18, and the like. The refrigeration cycle control device 38 is formed on a separate substrate from other circuits. The operation of the refrigeration cycle apparatus configured as described above will be described with reference to FIG. In the forward conversion circuit 30, the commercial AC voltage is rectified by the diodes D1 to D6, further smoothed by the capacitor C1, and converted into a DC voltage. The switching circuit 33 performs an on / off switching operation at a high speed (usually about several tens of kHz), so that the primary winding 3 of the high-frequency transformer 32 is turned on.
A high frequency current is passed through 2a. A high-frequency voltage is induced in the secondary windings 32b to 32f by the current of the primary winding 32a. 32b
Is rectified by the diode D7,
The voltage is smoothed by the capacitor C7 and supplied to the first drive circuit 33 as a DC voltage. The high-frequency voltage induced in 32c is rectified by a diode D8, smoothed by a capacitor C8, and supplied to the second drive circuit 34 as a DC voltage. The high-frequency voltage induced in 32d is rectified by the diode D9, smoothed by the capacitor C9, and supplied to the third drive circuit 35 as a DC voltage. The high-frequency voltage induced in 32e is rectified by a diode D10, smoothed by a capacitor C10, and supplied as a DC voltage to a fourth drive circuit 36 and an inverter control circuit 37. The high-frequency voltage induced at 32f is rectified by the diode D11, smoothed by the capacitor C11, and supplied to the refrigeration cycle control circuit 38 as a DC voltage. As described above, DC power required for operation is supplied to all circuits. Next, the control operation will be described. The refrigeration cycle control circuit 38 receives the room temperature sensor 16, the pipe sensor 17, the outside air temperature sensor 18 and the like, determines the current state of the refrigeration cycle, finds the optimum frequency according to the situation, and controls the inverter. Circuit 3
7 as a command signal. Here, the refrigeration cycle control circuit 38 and the inverter control circuit 37 are insulated by insulating means 39. Generally, a photocoupler is often used as the insulating means 39. The inverter control circuit 37 and the refrigeration cycle control circuit 38 are electrically insulated by this insulating means. Receiving the command signal sent from the refrigeration cycle control circuit 38, the inverter control circuit 37 generates a waveform for operating the forward conversion circuit 31 according to the command.
Generally, a sine wave PWM waveform or the like is used as this waveform. For the waveform signal output to the U phase, the upper arm signal is supplied to the first drive circuit 33, and the switching element Q1 is operated (on / off) by the signal, and the lower arm signal is supplied to the fourth drive circuit 36. The switching element Q2 is operated (on / off) by the signal. As for the waveform signal output to the V phase, the upper arm signal is supplied to the second drive circuit 34, and the switching element Q3 is operated (on / off) by the signal, and the lower arm signal is supplied to the fourth drive circuit 36. The switching element Q4 is operated (on / off) by the signal. As the waveform signal output to the W phase, the upper arm signal is supplied to the third drive circuit 35, and the switching element Q5 is operated (on / off) by the signal, and the lower arm signal is supplied to the fourth drive circuit 36. The switching element Q6 is operated (on / off) by the signal. By the above operation, the compressor 1
, An output of an arbitrary voltage and an arbitrary frequency consisting of three phases of a U phase, a V phase, and a W phase required to operate the refrigeration cycle control circuit 38 can be output according to a command signal. As described above, according to the present embodiment, the high-frequency transformer 32 having the primary winding 32a and the five secondary windings 32b to 32f, and the high-frequency transformer connected to the output side of the forward conversion output circuit 30 32, a switching circuit 33 connected in series with the primary winding 32a and performing on / off at a high frequency.
And a rectifying and smoothing circuit for rectifying and smoothing the AC output generated in each of the secondary windings 32b to 32f, and a rectifying and smoothing circuit for three of the secondary windings 32b to 32d of the high frequency transformer 32. Are independently supplied to the drive circuits 33, 34, 35 of the three switching elements Q1, Q3, Q5 of the upper bridge of the switching elements Q1 to Q6 connected in a three-phase bridge. The output of the rectifying / smoothing circuit of the other one secondary winding 32e in the line is 3
Three switching elements Q2, Q4, Q6 of the lower bridge of switching elements Q1-Q6 connected in phase bridge
And a power supply to the inverter control circuit 37 as well.
By supplying the output of the rectifying / smoothing circuit of the remaining one secondary winding 32f of the second secondary winding to the refrigeration cycle control circuit 38, the power supply circuit of the refrigeration cycle control circuit 38 and the inverter control circuit The power supply circuit necessary for the inverter including the inverter 37 can be commonly used by one high-frequency transformer 32, so that the power supply circuit can be downsized. Further, since they are commonly used, the size of the apparatus can be reduced, the number of inputs can be reduced, the power consumption can be reduced, and the cost can be reduced. Further, one power supply output is commonly supplied to the drive circuits of the three switching elements of the lower bridge, and power is also supplied to the inverter control circuit. The side and the ground line are shared, and direct detection of DC voltage can be easily realized by using A / D conversion of a microcomputer, so that inverter control can be advanced easily and at low cost. Will be able to respond. By providing the insulating means 39, the refrigeration cycle control circuit 38 is insulated from other circuits, so that a safe device excellent in noise resistance and free from accidents such as electric shock can be realized. Also. By using the refrigeration cycle control circuit 38 on a separate substrate from other circuits, the effect of this insulation is further improved, and safety is significantly improved by paying attention to electric shock and the like only on the other substrates. As described above, according to the present invention, the power supply circuit includes a high-frequency transformer having a primary winding and at least five secondary windings, and the high-frequency transformer connected to the output side of a forward conversion output circuit. A switching circuit that is connected in series with a primary winding of a transformer to perform on / off at a high frequency; a rectifying and smoothing circuit that rectifies and smoothes an AC output generated in each of the secondary windings; The rectifying and smoothing circuits of three secondary windings of the line are independently supplied to each of the drive circuits of the three switching elements of the upper bridge of the three-phase bridge-connected switching elements, and The output of the rectifying / smoothing circuit of another one of the secondary windings among the secondary windings is used to drive the three switching elements of the lower bridge of the three-phase bridge-connected switching element. And the power supply to the inverter control circuit, and the output of the rectifying and smoothing circuit of the remaining one secondary winding of the secondary winding of the high frequency transformer to the refrigeration cycle control circuit. By supplying the power, the power supply circuit of the refrigeration cycle control circuit and the power supply circuit required for the inverter including the inverter control circuit can be used in common, so that the power supply circuit can be downsized and the device can be downsized. , The input is further reduced, the power consumption is reduced, and the cost is reduced. Further, one power supply output is commonly supplied to the drive circuits of the three switching elements of the lower bridge, and power is also supplied to the inverter control circuit. The side and the ground line are shared, and direct detection of DC voltage can be easily realized by using A / D conversion of a microcomputer, so that inverter control can be advanced easily and at low cost. Will be able to respond.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram of a refrigeration cycle apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram of a conventional refrigeration cycle apparatus. Conversion circuit 32 High frequency transformer 33 Switching circuit

────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideo Hayashi 3-22, Takaidahondori, Higashiosaka-shi, Osaka Matsushita Refrigeration Machinery Co., Ltd. Field surveyed (Int.Cl. ⁷ , DB name) F24F 11/02 102

Claims (1)

(57) [Claim 1] A compressor, a forward conversion circuit for converting an AC input to DC, and a DC of the forward conversion circuit is converted to AC by a switching element connected in a three-phase bridge. An inverse conversion circuit, and a power supply circuit to which the direct current of the forward conversion circuit is input,
In a refrigeration cycle apparatus having an inverter control circuit for controlling the inverse conversion circuit and a refrigeration cycle control circuit for controlling a refrigeration cycle including the compressor, the power supply circuit includes a primary winding and at least five secondary windings. A high-frequency transformer having a line, a switching circuit connected to the output side of the forward conversion output circuit, connected in series with a primary winding of the high-frequency transformer, and performing on / off at a high frequency; and a secondary winding. A rectifying and smoothing circuit for rectifying and smoothing each of the AC outputs, and an upper bridge of a switching element connected to the three-phase bridge by connecting the rectifying and smoothing circuits of three secondary windings among the secondary windings of the high-frequency transformer. Rectifying / smoothing circuit for supplying independently to each of the drive circuits of the switching elements and for the other one of the secondary windings of the high-frequency transformer An output is commonly supplied to a drive circuit of three switching elements in a lower bridge of the switching elements connected to the three-phase bridge, and power is also supplied to the inverter control circuit. Wherein the output of the rectifying and smoothing circuit of the remaining one secondary winding is supplied to the refrigeration cycle control circuit.