JP2006101580A - Inverter device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To rationally drive a plurality of motors using inverters. <P>SOLUTION: This inverter device is driven rationally by connecting a first motor 44 which has coils 41, 42, and 43 and a second motor 48 which has coils 45, 46, and 47 in series, and connecting the set to one inverter 49. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an inverter device that is used for home use or business use, is used as a power source for various electric devices, and converts electric power into mechanical power to drive a mechanical load.

Conventionally, in order to drive a plurality of electric motors, this type of inverter device is driven by being connected to outputs of separate inverters (see, for example, Patent Document 1). FIG. 6 is a circuit diagram of a conventional inverter device described in Patent Document 1. In FIG. As shown in FIG. 6, a total of three electric motors, that is, a compressor 5, a cooling DC fan 8, and an internal DC fan 10 are provided. Power transformer 13, control power supply 14, microcontroller 15, three-phase six-stone compressor drive inverter 23, gate amplifier 24, and fan drive inverter 25. Compressor 5 is driven by a compressor. The cooling DC fan 8 is driven by a fan driving inverter 25 provided separately from the compressor driving inverter 23, and the internal DC fan 10 is also driven by a drive connected to the output of the inverter 23. A drive inverter 25 is provided and driven, and each of the three motors is a separate inverter, that is, a total of three inverters. Configuration were those of the motion.
JP-A-11-281218

  However, in the conventional configuration, there is an advantage that a plurality of electric motors can be controlled separately. For example, in the case of an inverter device that does not have any problem if it is simultaneously driven when driving other electric motors such as a cooling fan. Since the number of inverters increases according to the number of electric motors, the number of components increases, and the cost and shape increase.

  The present invention solves the above problems, and by driving a plurality of motors from the same inverter in an inverter device that connects a plurality of motors that are driven simultaneously, the number of inverters is reduced relative to the number of motors, An object of the present invention is to provide an inverter device having a small cost and shape.

  In order to solve the above problems, an inverter device of the present invention includes a plurality of electric motors having windings and an inverter, and the plurality of electric motors are connected in series and connected to the inverter for driving. .

  As a result, the current output from one inverter passes through the windings of one motor and then passes through the windings of another motor connected in series, so that current is supplied from one inverter to a plurality of motors. As a result, the number of inverters can be reduced relative to the number of electric motors, and an inverter device with reduced cost and shape can be realized.

  The inverter device of the present invention is driven by supplying current from a single inverter to a plurality of electric motors, so that the number of inverters can be reduced relative to the number of electric motors, and the cost and shape are reduced. An inverter device can be realized.

  A first invention has a plurality of electric motors having windings and an inverter, and the plurality of electric motors are connected in series and connected to the inverter for driving, thereby connecting the electric motors connected in series. Since the power is supplied from the same inverter and driven, the number of inverters can be reduced, and the cost and shape can be reduced.

  According to the second invention, in particular, the first electric motor of the first invention has a permanent magnet, and has a position detecting means for detecting a relative position between the permanent magnet and the winding. Since the electric motor generates an output by the current supplied to the permanent magnet and the winding, and the phase of the electric current with respect to the permanent magnet is accurately controlled by the action of the position detection means, the first electric motor is driven with high efficiency. Furthermore, since the same current is supplied from the same inverter to the motors other than the first motor, the number of inverters can be reduced with respect to the number of motors, and the cost and shape can be increased with high efficiency. It is possible to realize a configuration in which is low.

  The third aspect of the invention is particularly favorable because the second electric motor of the second aspect of the invention is an induction motor, and it has a very simple configuration and does not step out even when the output frequency of the inverter fluctuates greatly. A load can be driven, and a configuration with reduced cost and shape by reducing the number of inverters can be realized.

  In the fourth aspect of the invention, in particular, the second motor of the second aspect of the invention is a reluctance motor, so that the load is driven at a speed almost synchronized with the output frequency of the inverter with a relatively simple configuration. An apparatus having a reduced shape is realized.

  The fifth aspect of the invention has a fan provided as a load of the second electric motor of the first aspect of the invention in particular, and the fan is effective in a simple configuration that does not increase the number of inverters by cooling the inverter. Inverter can be cooled, and the configuration of the apparatus and the cost can be reduced.

  In the sixth aspect of the invention, in particular, the windings of the plurality of electric motors of the first aspect of the invention are all three-phase, and are configured to receive a three-phase AC output from the inverter. While the electric motor can be configured, sufficient power performance can be obtained, and the shape and cost can be reduced by reducing the number of inverters.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a circuit diagram of an inverter device according to a first embodiment of the present invention. In FIG. 1, a first electric motor 44 having three-phase windings 41, 42, and 43, a second electric motor 48 having three-phase windings 45, 46, and 47, and an inverter 49 are provided. In the connection of the electric motor, that is, the first electric motor 44 and the second electric motor 48, the windings 41 and 45 are connected in series, the windings 42 and 46 are connected in series, and the windings 43 and 47 are connected in series. Are connected in series, and are driven by receiving three-phase AC output from the inverter 49.

  The inverter 49 receives a DC voltage of 230V from the DC power supply 50. More specifically, the inverter 49 can be constituted by, for example, a 100V AC power supply configured by voltage doubler rectification. .

  Further, the first electric motor 44 includes a rotor 53 provided with permanent magnets 51 and 52 that are magnetically linked to the windings 41, 42, and 43 and can be rotated by a bearing such as a bearing, and Hall ICs 55, 56, and 57. And has a position detection means 58 for detecting the relative positions of the permanent magnets 51 and 52 with respect to the windings 41, 42 and 43.

  The second electric motor 48 has a cage-shaped rotor 60 and has a configuration of an induction motor that is very commonly used. The second electric motor 48 has three phases supplied to the windings 45, 46, and 47. The fan 61, which is a load, rotates so as to be dragged by the rotating magnetic field generated by the current. In the present embodiment, the second electric motor 48 and the fan 61 are the same as the inverter 49. The fan 61 is mounted on a printed circuit board and provided so as to cool the heat generating components in the inverter 49.

  The inverter 49 has a three-phase six-stone configuration including six stone switching elements 70, 71, 72, 73, 74, and 75 that are formed of an insulated gate bipolar transistor (IGBT) and a diode. By switching the switching elements 70, 71, 72, 73, 74, 75 on and off, a three-phase alternating current is output.

  2, (a) shows the output voltage waveform of the Hall IC 55, (A) shows the output voltage waveform of the Hall IC 56, and (C) shows the output voltage waveform of the Hall IC 57.

  3, (a) is the gate voltage waveform of the switching element 70, (A) is the gate voltage waveform of the switching element 71, (C) is the gate voltage waveform of the switching element 72, and (D) is the gate voltage of the switching element 73. The waveform, (e) is the gate voltage waveform of the switching element 74, and (f) is the gate voltage waveform of the switching element 75.

  The operation shown in these operation waveform diagrams is generally known as 120-degree energization. When a signal is input from the Hall ICs 55, 56, 57 to the drive circuit 76, the switching element 70, 71, 72, 73, 74, and 75 are turned on and off in order at predetermined electrical angles (60 degrees) by a signal from the drive circuit 76.

  Note that the switching elements 70, 71, 72 are not kept on throughout the period of 120 electrical angles, but are repeatedly turned on and off in a predetermined carrier frequency, for example, 4 kHz, and the ratio of the on period. By adjusting the output voltage, the output voltage can be controlled, and the speed can be adjusted freely.

  The inverter 49 performs three-phase AC output in performing the above-described operation. In the present embodiment, the same three-phase is connected to the second motor 48 and the first motor 44 connected in series. The two electric motors 44 and 48 are driven by one inverter 49.

  Here, in the present embodiment, the first electric motor 44 has a relatively large power, such as several tens of watts to several kilowatts, whereas the second electric motor 48 is connected to the inverter 49 by the fan 61. It is composed of a small size of about several W or less which is sufficient for the purpose of supplying cooling air.

  For this reason, the value of the current supplied from the inverter 49 is several A or more so that the first electric motor 44 can be sufficiently driven, and the windings 45, 46, 47 of the second electric motor are about two to three turns. The voltage between both terminals of each of the windings 45, 46, and 47 can be a very small value such as about 1V or less, so that the output voltage of the inverter 49 is effectively applied to the first motor 44. It can be supplied.

  Further, with respect to the first electric motor 44, since the position detection means 58 detects the positions of the permanent magnets 51 and 52 with high accuracy, the permanent magnets 51 and 52 and the windings 41, 42, and 43 are detected. With respect to the induced electromotive force generated by this interaction, a current having a small phase difference is supplied, and a characteristic of generating torque efficiently can be obtained.

  In addition, for example, by further controlling the advance angle to the drive circuit 76, it is possible to perform control such that the d-axis current is zero and the current is effectively converted into torque.

  Regarding the second electric motor 48, the frequency of the current flowing through the windings 45, 46 and 47 is determined by the speed of the first electric motor 44, so the first electric motor 44 is driven at a high speed. When the first motor 44 is driven at low speed, the frequency is low.

  For example, many inverter devices that drive a motor, such as a compressor that compresses refrigerant, increase the power under the condition that the speed of the first electric motor is high, and the switching element 70 that is a component constituting the inverter 49, The loss power of 71, 72, 73, 74, and 75, that is, heat generation increases, and in the case of such an inverter device, the speed of the fan 61 by the second electric motor 48 is also high when the heat generation of the inverter 49 is increased. Therefore, the effect that the inverter 49 is effectively cooled can be obtained.

  Further, although the speed of the first electric motor 44 may greatly change in a relatively short time due to a change in the load of the first electric motor 44, the second electric motor 48 in the present embodiment is Since it is configured as an induction motor, the second motor 48 does not stop rotating due to a step-out or the like. The fan 61 is sufficiently driven and can sufficiently increase the cooling effect of the inverter 49.

  Further, in the present embodiment, since the number of terminals of the first electric motor 44 that is three-phase is three, it is effective when used in a compressor (compressor) that compresses the refrigerant, for example. However, since the second electric motor 48 is also configured as a three-phase like the first electric motor 44, the number of terminals of each winding 45, 46, 47 is six in total. However, wiring is not particularly troublesome by mounting on the same printed circuit board as the inverter 49.

  However, connecting the second electric motor 48 closer to the inverter 49 than the first electric motor 44 is not an absolute condition. Conversely, the first electric motor 44 is first connected from the inverter 49, The second electric motor 48 may be connected behind it, but in this case, the first electric motor 44 has six terminals.

  In the present embodiment, the position detection means 58 is configured to directly detect the polarities of the permanent magnets 51 and 52 by the Hall ICs 55, 56 and 57. For example, an optical type, a configuration in which an induced electromotive force generated at a three-phase terminal by rotation of the permanent magnets 51 and 52 is detected using a voltage detection circuit, or the like. Position detection by detecting the position from the phase current with a microcomputer, etc., and detecting each current value of the three phases from the instantaneous value of the current of the DC part supplied from the DC power supply 50 and calculating with the microcomputer It does not matter if it is something that performs.

(Embodiment 2)
FIG. 4 is a configuration diagram in which the second electric motor according to the second embodiment of the present invention is realized using a reluctance motor 84. In FIG. 4, the three-phase windings 45, 46, and 47 are the same as those in the first embodiment, and the configuration of the rotor 80 is slightly different. In the present embodiment, the rotor 80 has a rotation center shaft 81 and a secondary conductor 82 formed by casting aluminum, as shown in the sectional view of FIG. The configuration up to this point is the same as the cage rotor of a general induction motor, and forms a short circuit.

  Further, the rotor 80 is provided with a gap 83 in the iron plate, so that as a four-pole motor, a rotor position having a large inductance (easy to pass magnetic flux) and a rotor position having a small inductance (a magnetic flux hardly passes) are provided. Will occur. The configuration of the other part of the inverter device is exactly the same as that of the first embodiment.

  In the present embodiment, when the inverter 49 drives the first electric motor 44 as in the first embodiment, the three-phase windings 45, 46, 47 of the second electric motor 84 configured by a reluctance electric motor are also used. A three-phase current is supplied.

  Here, when the speed of the rotor 80 is greatly different from the speed of the rotating magnetic flux, a current flows through the secondary conductor 82, which generates a torque due to the interaction with the rotating magnetic field. This is exactly the same as that in which the second electric motor 48 is configured using the induction motor of the first embodiment.

  Then, when the second motor 84 accelerates and the speed of the rotor 80 becomes close to the rotating magnetic field, the reluctance torque that rotates in synchronization with the direction in which the magnetic flux generated by the gap 83 easily passes is drawn into the rotating magnetic field. As a result, the motor rotates as a synchronous motor.

  Therefore, in the present embodiment, at the time of start-up or the like, the acceleration is supplementarily accelerated by the induced torque caused by the current flowing in the secondary conductor 82, and thereafter, the motor is rotated as a synchronous motor, and therefore after being synchronized. Since there is no slippage, the efficiency is high and there is no out-of-step, so there is no fear that the cooling fan 61 will stop unexpectedly, and the reliability is high. And since it implement | achieved by the very simple thing of providing the clearance gap 83 in an iron core as a structure which generate | occur | produces reluctance torque, the cost is also suppressed low.

  Note that the structure of the rotor 80 for generating reluctance is not limited to the structure of the rotor 80 having the gap 83 shown in the present embodiment, and the surface of the rotor is provided with unevenness so that the magnetic flux passes. A method of alternately arranging convex portions that are easy to pass and concave portions that are difficult to pass can also be used.

(Embodiment 3)
FIG. 5 shows a circuit diagram of an inverter device according to the third embodiment of the present invention. In FIG. 5, the third electric motor 86 is provided between the inverter 49 and the second electric motor 48, but the configuration of other parts is the same as that of the first embodiment. In the present embodiment, the third electric motor 86 has a three-phase winding 87, 88, 89 and a cage rotor 90.

  Therefore, in the present embodiment, the first electric motor 44, the second electric motor 48, and the third electric motor 86 are driven by receiving three-phase AC output from one inverter circuit 49, which is very rational. Therefore, a compact and low-cost inverter device can be realized.

  As described above, the inverter device according to the present invention includes a plurality of motors having windings and an inverter, and the plurality of motors are connected in series and connected to the inverter for driving. An inverter device that rationally drives a plurality of electric motors can be provided.

The circuit diagram of the inverter apparatus in Embodiment 1 of this invention Output waveform diagram of position detection means of the inverter device Output waveform diagram of the drive circuit of the inverter device Sectional drawing of the reluctance motor in Embodiment 2 of this invention The circuit diagram of the inverter apparatus in Embodiment 3 of this invention Circuit diagram of inverter device in the prior art

Explanation of symbols

41 Winding 42 Winding 43 Winding 44 First Motor 45 Winding 46 Winding 47 Winding 48 Second Motor 49 Inverter 51 Permanent Magnet 52 Permanent Magnet 58 Position Detection Means 61 Fan 84 Reluctance Motor 86 Third Motor 87 windings 88 windings 89 windings

Claims (6)

An inverter device comprising a plurality of motors having windings and an inverter, wherein the plurality of motors are connected in series and connected to the inverter for driving. The inverter apparatus according to claim 1, wherein the first electric motor includes a permanent magnet and includes a position detection unit that detects a relative position between the permanent magnet and the winding. The inverter device according to claim 2, wherein the second electric motor is an induction motor. The inverter device according to claim 2, wherein the second electric motor is a reluctance electric motor. The inverter device according to claim 1, further comprising: a fan provided as a load on the second electric motor, wherein the fan cools the inverter. The inverter device according to claim 1, wherein all of the windings of the plurality of electric motors have three phases and receive a three-phase AC output from the inverter.

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