JP2009156236A - Compressor driving device and refrigerating cycle device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compressor driving device and a refrigeration cycle device having excellent safety and capable of surely preventing an abnormal rise of the pressure and temperature of a hermetic compressor independently of kind of a motor mounted on the hermetic compressor. <P>SOLUTION: A protection device 15 to be operated when the pressure inside of a hermetic case 1a rises abnormally to form a short-circuit relative to phase winding, is provided inside of the hermetic case 1a of a hermetic compressor 1. When the protection device 15 is operated, over current flows to an inverter, and an over-current detector 42 detects it. At this point, a control section 60 stops operation of the inverter. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a compressor driving device and a refrigeration cycle device having a protective function for a hermetic compressor.

  As a drive device for a hermetic compressor composed of an electric motor and a compression mechanism, the voltage of a commercial AC power source is converted to DC, and the DC voltage is converted into a three-phase pseudo AC voltage by switching to each phase winding of the motor. Some have an inverter to be applied to. In this case, in order to sequentially switch the multi-phase energization from the inverter to each phase winding, the voltage induced in the non-energized phase winding of each phase winding is detected, and the rotor rotation of the motor is detected from the detected voltage. The position is detected, and the switching timing of the inverter is controlled according to the detected position.

In addition, in such a drive device, there is a device in which a protective device that opens a contact when the temperature rises abnormally is housed in a hermetic case of a hermetic compressor, and the energization to the phase winding is interrupted when the protective device is activated. (For example, patent document 1). In this case, when the protective device is activated and the energization to the phase winding is interrupted, so-called phase loss operation is performed, and it becomes impossible to detect all the voltages induced in each phase winding. As a result, the rotational position of the rotor cannot be detected, the switching operation of the inverter is stopped, and the abnormal temperature rise of the hermetic compressor is prevented.
JP-A-11-75386

The electric motor mounted on the hermetic compressor is a permanent magnet electric motor including a rotor having a permanent magnet and a stator having a plurality of phase windings. In order to drive the permanent magnet motor, as described above, the voltage induced in the phase winding in the non-energized state is detected, the rotor rotational position of the motor is detected from the detected voltage, and an inverter according to the detected position On the other hand, the electric motor includes an induction motor in addition to the permanent magnet motor. In the case of a hermetic compressor equipped with this induction motor, detection of the rotor rotational position is unnecessary. In such a situation, as described above, the protective device is housed in the hermetic case of the hermetic compressor, and even if the protective device is activated when the abnormal temperature rises, the hermetic compressor remains in an open phase state. There is a problem that the operation is continued and the abnormal temperature rise of the hermetic compressor cannot be prevented.

  The present invention takes the above circumstances into consideration, and is excellent in safety that can reliably prevent an abnormal increase in pressure or temperature of the hermetic compressor regardless of the type of electric motor mounted in the hermetic compressor. Another object is to provide a compressor driving device and a refrigeration cycle device.

  The compressor drive device of the invention according to claim 1 includes a motor having a plurality of phase windings, and a hermetic compressor in which a compression mechanism driven by the motor is housed in a hermetic case. A protective device provided in a hermetic case of the hermetic compressor and activated when the pressure or temperature in the hermetic case is abnormally increased, and forms a short circuit for the phase winding; , An inverter that returns the AC voltage by switching and applies it to each phase winding of the hermetic compressor, an overcurrent detection means for detecting an overcurrent to the inverter, and an overcurrent detected by the overcurrent detection means Control means for stopping the operation of the inverter when detected.

  According to a fifth aspect of the present invention, there is provided a refrigeration cycle apparatus according to any one of the first to fourth aspects, wherein the refrigerant discharged from the hermetic compressor is a condenser, a decompressor, and an evaporator. And a refrigeration cycle that returns to the hermetic compressor through a vessel.

  According to the compressor driving device and the refrigeration cycle device of the present invention, regardless of the type of electric motor mounted on the hermetic compressor, it is possible to reliably prevent an abnormal increase in pressure or temperature of the hermetic compressor, Safety is improved.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
In FIG. 1, reference numeral 1 denotes a hermetic compressor, in which a permanent magnet motor 10 and a compression mechanism unit 20 driven by the permanent magnet motor 10 are housed in a sealed case 1a. The permanent magnet motor 10 is also referred to as a brushless DC motor, and includes a stator 11 provided in contact with the inner peripheral surface of the sealed case 1a, a rotor 12 provided rotatably inside the stator 11, a central axis of the rotor 12, The rotor 12 is rotated by an interaction between a magnetic field generated by energizing each phase winding of the stator 11 and a magnetic field created by a plurality of permanent magnets embedded in the rotor 12. The rotational power of the rotor 12 is transmitted to the compression mechanism unit 20 by the shaft 13.

  In addition, suction pipes 2a and 2b are provided below the sealed case 1a, and an accumulator 3 is connected to the suction pipes 2a and 2b. A discharge pipe 4 and a sealed terminal portion 5 are provided on the upper portion of the sealed case 1a, and a terminal terminal 6 and a connector 7 are provided on the upper surface side and the lower surface side of the sealed terminal portion 5, respectively. A plurality of lead wires are connected from the respective phase windings of the stator 11 of the permanent magnet motor 10 to the connector 7, and a protection device 15 is connected between the two lead wires 8 and 9. As shown in FIG. 2, the protective device 15 has a normally-open contact 16 that is activated and closed when the pressure (or temperature) in the sealed case 1a abnormally increases. Are substantially the same.

  Furthermore, one end of a condenser 31 is piped to the discharge pipe 4 of the hermetic compressor 1, and the other end of the condenser 31 is piped to one end of an evaporator 33 via a decompressor, for example, an expansion valve 32. The other end of the evaporator 33 is connected to the suction pipes 2 a and 2 b via the accumulator 3. That is, the air is sucked into the compression mechanism 20 through the suction pipes 2a and 2b, and is compressed by the compression mechanism 20 and discharged from the discharge pipe 4. The discharged refrigerant passes through the condenser 31, the expansion valve 32, the evaporator 33, and the accumulator 3, and is sucked into the suction pipes 2a and 2b again. The hermetic compressor 1, the condenser 31, the expansion valve 32, and the evaporator 33 constitute a refrigeration cycle.

  In addition, lubricating oil (not shown) is accommodated in the inner bottom portion of the hermetic case 1a of the hermetic compressor 1, and the compression mechanism unit 20 is secured while the mechanical lubricating action of the compression mechanism unit 20 is secured by the lubricating oil. To be cooled.

The compressor driving device of FIG. 3 is connected to the hermetic compressor 1 having such a configuration.
That is, the voltage of the commercial AC power supply 40 is converted to DC by the forward conversion unit 41, and the DC voltage is applied to the switching circuit 50 via the overcurrent detector 42. The overcurrent detector 42 detects an overcurrent flowing through the switching circuit 50.

  The switching circuit 50 has a series circuit of three phases U, V, and W of a switching element located on the positive side of the applied DC voltage and a switching element located on the negative side, on the positive side of the U phase. A switching element U +, a switching element U− on the negative side, a switching element V + on the positive side of the V phase, a switching element V− on the negative side, a switching element W + on the positive side of the W phase, and a switching element W− on the negative side, The input DC voltage is converted into a three-phase pseudo AC voltage by switching and output. The switching circuit 50 and the forward conversion unit 41 constitute an inverter. The non-connection end of the phase winding Lu is connected to the interconnection point of the switching elements U + and U− of the switching circuit 50, and the non-connection end of the phase winding Lv is connected to the interconnection point of the switching elements V + and V−. Then, the non-connected end of the phase winding Lw is connected to the interconnection point of the switching elements W + and W−. The phase windings Lu, Lv, Lw are star-connected around the neutral point C. The switching circuit 50 and the phase windings Lu, Lv, Lw are connected via the terminal terminal 6 and the connector 7.

  A position detector 43 is connected to the energization line between the switching circuit 50 and the hermetic compressor 1. The position detector 43 detects a voltage induced in the non-energized phase winding among the phase windings Lu, Lv, and Lw, and detects the rotor rotational position of the permanent magnet electric motor 10 from the detected voltage. This detection result is supplied to the control unit 60.

  The forward conversion unit 41, the switching circuit 50, the position detection unit 43, and the control unit 60 constitute an inverter that supplies a drive voltage to the phase windings Lu, Lv, and Lw of the permanent magnet motor 10.

The control unit 60 has the following means (1) and (2) as main functions.
(1) Positioning is performed so that two-phase energization is performed while the switching elements of two series circuits are turned on and off and the switching elements of the remaining one series circuit are turned on in order. A means for generating and outputting a plurality of drive signals according to the detection result of the detection unit 43. These drive signals are supplied to each switching element of the switching circuit 50.

  (2) Control means for stopping the operation of the inverter by stopping the supply of the drive signal to the switching circuit 50 when an overcurrent is detected by the overcurrent detector 42.

  On the other hand, the protection device 15 is connected between two lead wires among a plurality of lead wires connected from the respective phase windings of the stator 11 of the permanent magnet motor 10 to the connector 7 as described above. Has been. That is, as shown in FIG. 3, it is connected between the non-connection end of the phase winding Lu and the non-connection end of the phase winding Lw, and the normally open contact 16 when the pressure in the sealed case 1a rises abnormally. Closes and forms a short circuit for the two phase windings Lu and Lw.

  In addition, a plurality of permanent magnets embedded in the rotor 12 of the permanent magnet motor 10 are subjected to magnetizing current through the phase windings Lu, Lv, Lw via the terminal terminals 6 after the assembly of the permanent magnet motor 10. Is magnetized.

Next, the operation will be described.
A drive signal for each switching element of the switching circuit 50 is generated by the control unit 60, and the drive signal is supplied to each switching element. Thereby, the two-phase energization in which the switching elements of the two series circuits in the switching circuit 50 are turned on and off and the remaining one of the series circuits is turned on is sequentially switched, and the phase winding of the permanent magnet motor 10 is switched. A sinusoidal current flows through each of Lu, Lv, and Lw, and the permanent magnet motor 10 operates.

  Thus, when the hermetic compressor 1 is in operation, if the pressure in the hermetic case 1a of the hermetic compressor 1 rises abnormally, the protection device 15 is activated and the normally open contact 16 is closed. When the normally open contact 16 is closed, the non-connected ends of the phase windings Lu and Lw are short-circuited, and a current that flows through the phase windings Lu and Lw flows through the normally open contact 16. With this short circuit, an overcurrent flows through the switching circuit 50 and is detected by the overcurrent detector 42. At this time, the control unit 60 stops supplying the drive signal to the switching circuit 50 in response to the overcurrent detection of the overcurrent detector 42. When the supply of the drive signal is stopped, the operation of the switching circuit 50 is stopped, the operation of the permanent magnet motor 10 is stopped, and the operation of the hermetic compressor 1 is stopped. By stopping the operation, an abnormal increase in pressure in the sealed case 1a of the hermetic compressor 1 is prevented.

  When the pressure in the sealed case 1a of the hermetic compressor 1 decreases, the protective device 15 returns and the normally open contact 16 is opened, the short circuit path to the non-connected ends of the phase windings Lu and Lw is released. As a result, a current flows through all the phase windings Lu, Lv, Lw, the operation of the permanent magnet motor 10 is resumed, and the operation of the hermetic compressor 1 is resumed.

  Thus, even if the electric motor mounted in the hermetic compressor 1 is not the permanent magnet motor 10 but the induction motor, the overcurrent protection control by the control unit 60 works along with the operation of the protection device 15. An abnormal increase in the pressure of the hermetic compressor 1 can be reliably prevented.

  In addition, the normally open contact 16 of the protective device 15 is closed only when the pressure rises abnormally and is otherwise open, so that the permanent magnet of the rotor is magnetized after the permanent magnet motor 10 is assembled. Even if a magnetizing current is passed through the phase windings Lu, Lv, and Lw, there is no problem that the magnetizing current is short-circuited. Therefore, the permanent magnet can be reliably magnetized.

  In addition, the protection device 15 employs an operating point and a return point that are substantially the same for the following reason. First, as a protection device, it is common to secure a differential between the operating point and return point to prevent frequent repetition of operation and return. Due to the curved shape, the differential can be secured at low cost. However, in the case of sensing pressure, a snap action is required to secure the differential, and the adoption of the action causes problems such as a complicated structure, an increase in size, and an increase in cost. In this embodiment, in order to cope with such a problem, the protective device 15 having substantially the same operating point and return point is employed. Even if the protective device 15 repeats the operation and the return, the control of the control unit 60 is interposed for each operation and return, and the operation and stop of the hermetic compressor 1 are controlled at an appropriate timing. The problem that the compressor 1 frequently repeats operation and stop does not occur at all. However, it is also possible to secure a differential between the operating point and the return point with a protective device that operates by sensing pressure.

  In the above embodiment, the protection device 15 having the normally open contact 16 has been described as an example. However, as shown in FIG. 4, the normally open contact 16 and the current limiting element 17 connected in series to the normally open contact 16 are used. A protective device 15 may be adopted. For example, a resistor or a positive temperature coefficient thermistor is used as the current limiting element 17. According to this configuration, the magnitude of the short-circuit current due to the closing of the normally open contact 16 can be appropriately limited, and the destruction of the switching element in the switching circuit 50 can be prevented in advance.

  In the above embodiment, the protection device 15 is connected between the non-connection ends of the two phase windings. However, the invention is not limited thereto, and the protection device 15 is connected to the non-connection end of one phase winding and the middle. It is good also as a structure connected between the sex points C.

  Further, in the above embodiment, the rotor rotational position of the permanent magnet motor 10 is detected from the induced voltage. However, as shown in FIG. 5, a current is supplied to the energization line between the switching circuit 50 and the hermetic compressor 1. It is good also as a structure which provides the sensors 44u and 44v and detects the rotor rotational position of the permanent magnet electric motor 10 from the detection electric current of these current sensors 44u and 44v.

  In addition, the present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment.

The figure which shows the structure of the inside of the hermetic compressor in connection with one Embodiment, and a refrigerating cycle. The figure which shows the specific structure of the protection apparatus in one Embodiment. The block diagram which shows the structure of one Embodiment. The figure which shows the structure of the modification of the protection apparatus in one Embodiment. The block diagram which shows the structure of the modification of one Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Sealed compressor, 1a ... Sealed case, 2a, 2b ... Suction pipe, 3 ... Accumulator, 4 ... Discharge pipe, 5 ... Sealed terminal part, 6 ... Terminal terminal, 7 ... Connector, 10 ... Permanent magnet motor, 11 DESCRIPTION OF SYMBOLS ... Stator, 12 ... Rotor, 13 ... Shaft, 20 ... Compression mechanism, 15 ... Protection device, 16 ... Normally open contact, 17 ... Current limiting element, 31 ... Condenser, 32 ... Expansion valve (decompressor), 33 ... Evaporator 40 ... Commercial AC power source 41 ... Forward conversion unit 42 ... Overcurrent detector 43 ... Position detection unit 50 ... Switching circuit 60 ... Control unit Lu, Lv, Lw ... Phase winding

Claims (5)

In an electric motor having a plurality of phase windings and a hermetic compressor in which a compression mechanism driven by the electric motor is housed in a hermetic case,
A protective device that is provided in a hermetic case of the hermetic compressor and is activated when the pressure or temperature in the hermetic case is abnormally increased, and forms a short circuit for the phase winding;
An AC voltage is returned to DC, an inverter that returns it to AC voltage by switching and applies to each phase winding of the hermetic compressor,
Overcurrent detection means for detecting overcurrent to the inverter;
Control means for stopping the operation of the inverter when an overcurrent is detected by the overcurrent detection means;
A compressor driving device comprising: The electric motor comprises a rotor having a permanent magnet and a stator having a plurality of phase windings,
The permanent magnet is magnetized by a magnetizing current that flows through the phase windings.
The compressor driving device according to claim 1. The electric motor includes a rotor having a permanent magnet and a stator having a plurality of phase windings connected in a star shape.
The protective device is connected between the unconnected ends of any two phase windings of the phase windings, and is a normally open contact that closes when the pressure or temperature in the sealed case abnormally rises. The compressor driving device according to claim 1, further comprising a current limiting element connected in series to the normally open contact. The compressor driving device according to claim 1, wherein the protection device operates when the pressure in the sealed case abnormally rises, and the operation point and the return point are substantially the same. A compressor driving device according to any one of claims 1 to 4, and a refrigeration cycle for returning refrigerant discharged from the hermetic compressor to a hermetic compressor through a condenser, a decompressor, and an evaporator. A refrigeration cycle apparatus comprising:

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