JP5560552B2 - Inverter device and air conditioner using the same - Google Patents

Description

  The present invention relates to an inverter device and an air conditioner using the inverter device, and particularly relates to an inverter device that improves the power factor and an air conditioner using the inverter device.

  In an inverter device used for an air conditioner, a reactor is arranged in a DC unit to which a DC voltage rectified by a diode module is supplied in order to improve a power factor and suppress harmonics. Specifically, Patent Document 1 discloses an example of an inverter device in which a reactor is arranged in a direct current section.

JP 2001-275360 A

  However, if the load of the compressor or the like increases and the inverter increases in size, the loss increases with the square of the current. Therefore, it is necessary to increase the size of the main circuit relay and reactor provided in the DC section. In particular, when the main circuit relay becomes large and cannot be mounted on the substrate of the DC part, it is necessary to provide the main circuit relay at a location different from the substrate and to electrically connect the main circuit relay and the substrate with a contactor. This contactor is large due to the necessity of flowing a large current, and is expensive as a part. Therefore, the inverter device configured to connect the main circuit relay and the substrate using the contactor is increased in size and cost.

  Therefore, an object of the present invention is to provide a small-sized and low-cost inverter device and an air conditioner using the same while ensuring a current capacity.

In order to solve the above problems, an inverter device according to the present invention includes a diode module that rectifies an input AC voltage into a DC voltage, a relay that controls input of the AC voltage to the diode module, and the relay and diode module. A reactor connected in series, a capacitor charged with the DC voltage rectified by the diode module, and an inverter that drives a load based on a voltage across the capacitor, and the relay is opened and closed. Regardless, a plurality of combinations of the relays and the reactors connected in series are provided in parallel.

  A plurality of the relays provided in parallel may be integrally formed.

  Each of the relays may have a plurality of contacts.

Furthermore, in order to solve the said subject, this air conditioner is the inverter apparatus as described in any one of Claim 1 thru | or 3 , the electric motor which is the said load driven by the said inverter apparatus, and the said electric motor. A compressor that compresses the refrigerant by operation.

According to the inverter device of the present invention, a relay that controls an input of the alternating current to the diode module is provided with the series connected reactors between the relay and the diode module, provided to the AC portion The relay can be reduced in size and cost while securing a current capacity.

  In addition, the plurality of relays provided in parallel can be reduced in size by being formed integrally, and variation in contact resistance between the relays can be reduced.

  In addition, each of the relays has a plurality of contacts, so that a larger current capacity can be secured.

  Furthermore, according to this air conditioner, since an inverter device in which a plurality of combinations of the relays and the reactors connected in series are arranged in parallel is adopted, it is possible to reduce the size and cost while securing the current capacity.

(Embodiment 1)
As a method of using a small relay while ensuring current capacity, a method of connecting a plurality of relays in parallel can be considered. However, when multiple relays are simply connected in parallel, the contact resistance varies greatly among the individual relays, so that current concentrates on one of the multiple relays connected in parallel, and sufficient current capacity is achieved. It is difficult to ensure. Specifically, when two relays with a current capacity of 20A are connected in parallel, theoretically, a current capacity of 20A × 2 = 40A can be ensured. Since most of the current flows through one of the relays, it is said that a current capacity of only about 22 to 25 A can be secured. An example showing the relationship between the energization current and the contact resistance is shown in FIG. It can be seen from the graph shown in FIG. 6 that the contact resistance varies greatly even when the same energization current is supplied to the relay A and the relay B.

  Therefore, the inverter device according to the present embodiment is configured as shown in the circuit diagram of FIG. 1 to ensure the required current capacity. In the inverter device shown in FIG. 1, a diode module 1 that rectifies an AC voltage input from an AC power supply (not shown) into a DC voltage, an inverter 2 that drives a load (not shown), a diode module 1 and an inverter 2 and a DC unit to which a DC voltage is supplied.

  The DC unit shown in FIG. 1 includes a capacitor 3 charged with a DC voltage rectified by the diode module 1, a relay 4 that controls connection between the diode module 1 and the capacitor 3, and between the relay 4 and the capacitor 3. A reactor 5 connected in series is provided. Further, in the direct current section shown in FIG. 1, two combinations of the relay 4 and the reactor 5 are provided in parallel.

  In addition, the inrush current prevention circuit 6 is provided in the inverter apparatus shown in FIG. The inrush current prevention circuit 6 is configured by a relay circuit, a resistor, or the like, and prevents an inrush current from being supplied to the inverter 2.

  The diode module 1 includes a plurality of diodes (not shown), and full-wave rectifies the input AC voltage and supplies it as a DC voltage to the wiring of the DC unit. The capacitor 3 is a smoothing capacitor and smoothes the DC voltage from the diode module 1 and outputs it to the inverter 2. The inverter 2 includes a plurality of semiconductor switches such as IGBTs (insulated gate bipolar transistors), generates arbitrary three-phase alternating current by controlling switching of the semiconductor switches, and drives a motor as a load.

  Next, in the inverter device shown in FIG. 1, the reactor 5 is connected in series to each of the two relays 4, and the combination of the relay 4 and the reactor 5 connected in series (hereinafter simply referred to as “combination”) They are connected in parallel to each other. Therefore, the inverter device shown in FIG. 1 can absorb the variation in the contact resistance between the relays 4 with the resistance of the reactor 5, and can secure more current capacity as a whole in which the combinations are connected in parallel.

  This will be specifically described with reference to FIGS. First, the contact resistance of the relay 4 shown in FIG. 1 is about 1 mΩ, and the contact resistance variation between different relays 4 is 100%. Therefore, if one of the relays 4a shown in FIG. 7 has a contact resistance of 1 mΩ, the contact resistance of the other relay 4b may be 2 mΩ. In this case, as shown in FIG. 7, the current flowing through the relay 4a is 26.7A out of 40A, and is about twice the current (13.3A) flowing through the other relay 4b.

  However, in the inverter device according to the present embodiment, as shown in FIG. 8A, the reactor 5a is connected in series to the relay 4a, and the reactor 5b is connected in series to the relay 4b. The direct current resistance of the reactors 5a and 5b is sufficiently larger than the contact resistance of the relays 4a and 4b, for example, about 20 mΩ. The variation in DC resistance between the reactors 5a and 5b is as small as about 10%. Therefore, if the series resistance of the reactor 5a connected in series to one relay 4a is 20 mΩ and the series resistance of the reactor 5b connected in series to the other relay 4b is 22 mΩ, the resistance due to the combination of one relay 4a and the reactor 5a The value is 1 + 20 = 21 mΩ, and the resistance value by the combination of the other relay 4b and the reactor 5b is 2 + 22 = 24 mΩ. Therefore, as shown in FIG. 8A, the current flowing through the relay 4a is 18.7A out of 40A and the current of 21.3A flows through the other relay 4b. The current imbalance can be reduced as compared with the case of FIG. Further, if each of the relays 4a and 4b can only flow up to 20A, the current flowing through the relays 4a and 4b is about 37.6A so that the current flowing through the relay 4b is 20A as shown in FIG. 8B. Keep it down.

  Therefore, the variation in resistance between the combination of one relay 4a and the reactor 5a and the combination of the other relay 4b and the reactor 5b can be suppressed to about 20%. That is, by connecting the reactors 5a and 5b in series to the relays 4a and 4b, variation in contact resistance is suppressed and current imbalance between the relays 4a and 4b is reduced. By reducing the current imbalance between the relays 4a and 4b, the current capacity can be increased by connecting the relays 4a and 4b in parallel. Specifically, when two relays 4a and 4b having a current capacity of 20A are simply arranged in parallel as shown in FIG. 7, a current capacity of only about 25A can be secured as shown in FIG. 8B. As a result, a current capacity of about 37.6 A can be secured. Therefore, a larger current capacity can be ensured by using a plurality of inexpensive and small relays 4 having a small current capacity (about 20 A).

  Further, since the reactor 5 is connected in series to each of the relays 4 as shown in FIG. 1, the current flowing through one reactor 5 can be reduced. For example, when one reactor 5 corresponding to the current capacity is provided in one relay 4 having a large current capacity, or a plurality of relays 4 having a small current capacity are arranged in parallel, and one reactor 5 is connected to the plurality of relays 4. Compared with the case where it provides, the electric current which flows into the one reactor 5 can be made small. If the current flowing through the reactor 5 can be reduced, the reactor 5 itself can be downsized and inexpensive.

  In the inverter device according to the present embodiment, an example in which two series-connected combinations of the relay 4 and the reactor 5 are arranged in parallel has been described. However, the present invention is not limited to this, and a configuration in which three or more are arranged in parallel is used. There may be.

(Embodiment 2)
Some relays currently on the market have a plurality of contacts in one package. When the packaged relay (hereinafter also referred to as a relay circuit) is used to configure the inverter device shown in FIG. 1, the circuit configuration shown in FIG. 2 is obtained.

  In the inverter device shown in FIG. 2, a relay circuit 40 having two contacts is used. Each contact of this relay circuit 40 is handled as a relay 4, and the contact and the reactor 5 are connected in series, and an inverter device in which two series-connected combinations of the relay 4 and the reactor 5 are arranged in parallel is configured. Yes. The inverter device shown in FIG. 2 has the same configuration as that of the inverter device shown in FIG. 1 except that the two relays 4 arranged in parallel are replaced by a relay circuit 40. Omitted.

  As in the inverter device shown in FIG. 2, by replacing the two relays 4 arranged in parallel with the relay circuit 40, there is an advantage that the individual relays 4 can be downsized rather than being mounted on the substrate. Further, since the variation in the contact resistance of each relay 4 in the relay circuit 40 packaged in one is smaller than the variation in the contact resistance in the individual relay 4, the inverter apparatus shown in FIG. This has the advantage that a larger current capacity can be secured.

  One current supply is sufficient to operate the relay 4.

  2 shows an example in which the relay circuit 40 having two contacts is used. However, the present invention is not limited to this, and the relay 4 and the reactor are connected using the relay circuit 40 having three contacts. A configuration in which three or more combinations of 5 connected in series may be arranged in parallel.

(Modification)
Furthermore, a circuit diagram of a modification of the inverter device according to the present embodiment is shown in FIG. In the inverter device shown in FIG. 3, a relay circuit having two contacts is employed for each relay 4 of the inverter device shown in FIG. That is, the relay 4 shown in FIG. 3 includes a relay circuit in which the contacts 4a and 4b are connected in parallel. A configuration in which a reactor 5 is connected in series to each of the relays 4 having the two contact points 4a and 4b, and two combinations of the relay 4 and the reactor 5 are arranged in parallel is the inverter device shown in FIG.

  Since the reactor 5 is not connected to each of the contacts 4a and 4b, variation in the contact resistance of both the contacts 4a and 4b is not absorbed. Therefore, when both the contacts 4a and 4b are arranged in parallel, the current is concentrated on one of the contacts. However, a large current capacity cannot be ensured. However, the relay 4 having two contacts in parallel has a larger current capacity than the relay 4 having at least one contact. Therefore, compared to the case where each relay 4 has one contact as in the inverter device shown in FIG. 1, the case where each relay 4 has two contacts as in the inverter device shown in FIG. However, a larger current capacity can be secured.

  Further, by adopting the relay 4 having two contacts, even if one contact fails, the operation of the entire apparatus is not affected. Therefore, the inverter device according to this modification is a more reliable device. It becomes.

  In addition, although the example which uses the relay 4 which has two contacts was shown in the inverter apparatus shown in FIG. 3, this invention is not limited to this, You may use the relay 4 which has three or more contacts. In addition, in the inverter device shown in FIG. 3, a configuration in which two series-connected combinations of the relay 4 having two contacts and the reactor 5 are arranged in parallel is shown, but the present invention is not limited to this and has a plurality of contacts. A configuration in which three or more combinations of the relay 4 and the reactor 5 connected in series are arranged in parallel may be used.

  Further, in the inverter device according to the present embodiment and the modification, the relay 4 is turned on / off after the semiconductor switch of the inverter 2 is turned off to stop the current flowing through the load.

(Embodiment 3)
In the inverter devices according to the first and second embodiments, the configuration in which the relay 4 is provided in the DC unit to which the DC voltage rectified by the diode module 1 is supplied has been described, but the present invention is not limited to this. The inverter device according to the present embodiment has a configuration in which a relay 4 is provided in a portion for supplying an AC voltage to the diode module 1 (hereinafter also simply referred to as an AC unit) as shown in FIG.

  The inverter device shown in FIG. 4 includes a configuration in which two combinations of a relay 4 and a reactor 5 connected in series are arranged in parallel in the AC unit. On the other hand, unlike the inverter device shown in FIG. 1 etc., the relay 4 etc. are not provided in the DC part of the inverter device shown in FIG. Since the inverter device shown in FIG. 4 has the same configuration as the inverter device shown in FIG. 1 except for the arrangement of the relay 4 and the reactor 5, the same reference numerals are given and detailed description thereof is omitted.

  Also in the inverter device shown in FIG. 4, as in the inverter device shown in FIG. 1, a larger current capacity can be ensured by paralleling two combinations of the relay 4 and the reactor 5 connected in series.

  In the inverter device shown in FIG. 4, the example in which the relay 4 having one contact is used in the AC unit is shown, but the present invention is not limited to this, and the relay 4 having two or more contacts may be used. . Further, in the inverter device shown in FIG. 4, the configuration in which two combinations of the relay 4 and the reactor 5 connected in series are arranged in parallel in the AC unit is shown, but the present invention is not limited to this, and the relay 4 and the reactor 5 A configuration in which three or more combinations connected in series are arranged in parallel may be used.

(Embodiment 4)
The inverter device according to Embodiments 1 to 3 can be used for an air conditioner. Specifically, the case where the inverter device according to Embodiment 1 is used for an air conditioner will be described. FIG. 5 is a circuit block diagram of an air conditioner using the inverter device shown in FIG.

  In the air conditioner shown in FIG. 5, in addition to the configuration of the inverter device shown in FIG. 1, the motor 7 driven by the inverter 2, the compressor 8 that is driven by the motor 7 to compress the refrigerant, and the diode module 1. And an AC power supply 9 for supplying an AC voltage to the power source.

  By adopting the inverter device shown in FIG. 1 like the air conditioner shown in FIG. 5, the entire air conditioner can be reduced in size and cost while ensuring the necessary current capacity.

It is a circuit diagram of the inverter apparatus which concerns on Embodiment 1 of this invention. It is a circuit diagram of the inverter apparatus which concerns on Embodiment 2 of this invention. It is a circuit diagram of the inverter apparatus which concerns on the modification of Embodiment 2 of this invention. It is a circuit diagram of the inverter apparatus which concerns on Embodiment 3 of this invention. It is a circuit block diagram of the air conditioner which concerns on Embodiment 4 of this invention. It is a figure for demonstrating operation | movement of the inverter apparatus which concerns on Embodiment 1 of this invention. It is a figure for demonstrating operation | movement of the inverter apparatus which concerns on Embodiment 1 of this invention. It is a figure for demonstrating operation | movement of the inverter apparatus which concerns on Embodiment 1 of this invention.

Explanation of symbols

1 Diode Module 2 Inverter 3 Capacitor 4 Relay 5 Reactor 6 Inrush Current Prevention Circuit 7 Motor 8 Compressor 9 AC Power Supply 40 Relay Circuit

Claims (4)

A diode module (1) for rectifying the input AC voltage into a DC voltage;
A relay (4) for controlling the input of the AC voltage to the diode module (1) ;
A series-connected reactors (5) between the front SL relay (4) and the diode module (1),
A capacitor (3) charged with the DC voltage rectified by the diode module (1);
An inverter (2) for driving a load based on the voltage across the capacitor (3),
An inverter device in which a plurality of combinations of the relay (4) and the reactor (5) connected in series are provided in parallel regardless of the open / closed state of the relay. The inverter device according to claim 1,
An inverter device in which a plurality of the relays (4) provided in parallel are integrally formed . The inverter device according to claim 1 or claim 2,
An inverter device in which each of the relays (4) has a plurality of contacts . An inverter apparatus according to any one of claims 1 to 3,
An electric motor (7) as the load driven by the inverter device;
An air conditioner comprising a compressor (8) that compresses refrigerant by an operation of the electric motor (7) .

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