JP3473612B2 - Air conditioner - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner equipped with an electric compressor driven by a DC power source.

[0002]

2. Description of the Related Art In an air conditioner using an electric compressor, an electric compressor driving device for driving an electric compressor for air conditioning supplies a large current to the electric compressor. A capacitor is provided in the power supply section. This configuration will be described with reference to the drawings.

FIG. 5 is an explanatory view of measures against a recovery current of an air conditioner equipped with an electric compressor. As shown in FIG. 5A, a battery 3 is connected to the electric compressor drive device 1, but a stray inductance 8 formed by wiring or the like exists between the electric compressor drive device 1 and the battery 3. . Further, the electric compressor 2 is connected to the electric compressor drive device 1.

The output portion of the electric compressor driving device 1 to the electric compressor 2 has the structure shown in FIG. 5 (b), and the recovery current is generated as follows.

The upper output transistor 4 and the lower output transistor 5 are turned on, and the electric current a is supplied to the electric compressor 2.
Is washed away. Next, when the lower output transistor 5 is turned off, the current b flows through the flywheel diode 6 due to the inductance of the motor coil of the electric compressor 2. This allows the flywheel diode 6
Since electric charges are accumulated in the electric current, the recovery current c of the flywheel diode 6 flows when the lower output transistor 5 is turned on next time.

Since this recovery current c also flows through the stray inductance 8 shown in FIG. 5 (a), when the recovery current c is turned off, the stray inductance 8 causes the power input voltage Vp to the electric compressor drive device 1 to be changed to the value shown in FIG.
A surge voltage is generated as shown in (b).

This surge voltage causes destruction of the upper output transistor 4, the lower output transistor 5 and the like. Therefore, normally, as shown in FIG. 5C, the recovery current countermeasure capacitor 7 that serves as a supply source of the recovery current c of the flywheel diode 6 and does not flow into the stray inductance 8 is input to the electric compressor drive device 1 as a power source. It is provided in the section.

[0008]

In the circuit configured as described above, the resonance current flows in the power supply line of the electric compressor drive device 1 as follows, electromagnetic wave interference occurs, and the capacitor provided in the power supply line is There are problems such as heat generation, generation of voltage pulse on the power supply line, and deterioration of current detection accuracy of the power supply line.

FIG. 6 is an explanatory diagram of a resonance current of an air conditioner using an electric compressor. As shown in the figure, in addition to the stray inductance 8 in the power supply line, the transformer of the current detection device is required due to the necessity of the circuit. There is a circuit inductance 9 due to the above.

When a current im shown in FIG. 6 flows through the electric compressor drive device 1, a resonance current ic due to the recovery current countermeasure capacitor 7, the circuit inductance 9 and the stray inductance 8 flows at the rise and fall of the current im. Therefore, a voltage pulse is generated in the voltage Vp of the power supply line of the electric compressor drive device 1, and a component of the resonance current ic flows in the current iLC of the power supply line at the rising and falling of the current.

Next, FIG. 7 shows a circuit configuration for reducing the resonance current ic. As shown in the figure, a reverse resonance current countermeasure diode 10 is connected in parallel with the circuit inductance 9 in the direction opposite to the direct current flow path of the electric compressor drive device 1.

When a current im shown in FIG. 5 flows through the electric compressor drive device 1, the recovery current countermeasure capacitor 7, the circuit inductance 9 and the stray inductance 8 cause the rising and falling of the current im.
The resonance current ic described in FIG. 6 tries to flow.

However, the resonance energy is absorbed by the reverse resonance current countermeasure diode 10, and the current iD shown in FIG. 5 flows through the reverse resonance current countermeasure diode 10.
Therefore, the resonance current ic shown in FIG. 7 is smaller than the resonance current ic shown in FIG. Then, the voltage pulse generated in the voltage Vp also becomes small.

Therefore, the resonance current ic is reduced, and accordingly, electromagnetic wave interference, heat generation of the capacitor provided in the power supply line, and voltage pulse of the power supply line are reduced.

However, the current iLC of the power supply line is the sum of the current im and the current iD as shown in FIG. 7, and the circuit configuration of FIG. 7 has the circuit configuration of FIG. 6 due to the abrupt rising waveform of the current iLC of the power supply line. Similarly, the accuracy of current detection of the power supply line is reduced.

In order to protect the electric compressor driving device 1 and the like, it is necessary to monitor the maximum value of the current im with a current detecting device, but the current detected by the current detecting device is i.
If the detection accuracy of the LC is reduced, the protective function of the electric compressor drive device 1 and the like becomes inconvenient.

Therefore, the present invention solves the problems such as the occurrence of electromagnetic wave interference due to the resonance current, the heat generation of the capacitor provided in the power supply line, the voltage pulse of the power supply line, and the deterioration of the current detection accuracy of the power supply line. An object of the present invention is to provide an air conditioner using an electric compressor driven by a DC power source, which is solved.

[0018]

In order to solve the above problems, the present invention provides, as a first means, an electric compressor drive device for converting electric power from a DC power supply into an AC to drive an electric compressor, and the DC power supply. And a capacitor connected between plus and minus of a power supply line connecting the electric compressor drive device and a coil, a coil inserted in the middle of a power supply line connecting the DC power supply and the electric compressor drive device, and a coil generated from the coil A current detection device for detecting a value of a current flowing through the coil by magnetic flux, and a diode connected in parallel with the coil are provided, and the diode is connected in a direction in which the rising of the current flowing through the coil becomes gentle. .

With this configuration, the resonance current ic is reduced, the occurrence of electromagnetic wave interference, the heat generation of the capacitor provided in the power supply line, and the voltage pulse of the power supply line are reduced. Further, the maximum value of the current detected by the current detection device is equal to the maximum value of the current flowing through the electric compressor drive device because no resonance current flows. Therefore, the current detection of the power supply line becomes extremely accurate, and the electric compressor drive device and the like can be properly protected.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a circuit diagram and a waveform diagram of an air conditioner according to Embodiment 1 of the present invention.

As shown in FIG. 1 (a), a forward resonance current countermeasure diode 11 is connected in parallel with the circuit inductance 9 in the same direction as the direct current flow path of the electric compressor drive device 1.

The electric compressor drive unit 1 is shown in FIG.
When the current im shown in (b) flows, the recovery current countermeasure capacitor 7, the circuit inductance 9, and the stray inductance 8 at the rising and falling of the current im.
As a result, the resonance current ic shown in FIG. 6 tends to flow.
However, the resonance energy is absorbed by the forward resonance current countermeasure diode 11, and the current iD shown in FIG. 1B flows through the forward resonance current countermeasure diode 11.

Therefore , the resonance current ic shown in FIG. 1 is smaller than the resonance current ic shown in FIG. 6, and the voltage pulse generated in the voltage Vp is also small. On the other hand, the current iL of the power line
C is the sum of the current im and the current iD as shown in the figure,
The rise will be gentle.

In this way, the resonance current ic is reduced, so that the occurrence of electromagnetic wave interference, the heat generation of the capacitor provided in the power supply line, and the voltage pulse of the power supply line are reduced.

Further, in order to protect the electric compressor driving device 1 and the like, the maximum value of the current im (A in FIG.
It is necessary to monitor the point) with the current detection device, but the current detected by the current detection device is iLC, and its maximum value is equal to the maximum value of the current im because the resonance current ic does not flow. In addition, since the rise of the current iLC is configured to be gentle, it is possible to prevent erroneous detection of the maximum value of the current iLC, so that the current detection of the power supply line becomes extremely accurate.

FIG. 2 is a circuit diagram in which the current detection device is specified in the circuit of FIG. 1 (a).

In the figure, a forward resonance current countermeasure diode 11 is connected in parallel to the primary side of the current detection transformer 17, so that the recovery current countermeasure capacitor 7 and the current are prevented when the electric compressor drive device 1 rises and falls. The energy of the resonance current due to the primary side (circuit inductance 9) of the detection transformer 17 and the stray inductance 8 is the forward resonance current countermeasure diode 1
It is absorbed in 1.

Therefore, the resonance current is reduced, the occurrence of electromagnetic wave interference, the heat generation of the capacitor provided in the power supply line, and the voltage pulse of the power supply line are reduced, so that the above-mentioned specific effect can be obtained.

In this case, the voltage drop due to the DC current flowing through the primary side of the current detection transformer 17 is sufficiently smaller than the forward voltage of the diode 11 for preventing the forward resonance current, so that the operation of the electric circuit is not affected.

The maximum value of the current flowing through the electric compressor drive device 1 is equal to the maximum value of the current flowing through the primary side of the current detecting transformer 17. Further, the negative current is not detected by the rectifier diode 18 on the secondary side.
Therefore, the current detection of the power supply line becomes extremely accurate.

(Second Embodiment) FIG. 3 is a circuit diagram and a waveform diagram of an air conditioner according to a second embodiment of the present invention.

As shown in FIG. 3A, both the reverse resonance current countermeasure diode 10 and the forward resonance current countermeasure diode 11 are connected in parallel with the circuit inductance 9.

The electric compressor drive unit 1 is shown in FIG.
When the current im shown in (b) flows, the recovery current countermeasure capacitor 7, the circuit inductance 9, and the stray inductance 8 at the rising and falling of the current im.
As a result, the resonance current ic shown in FIG. 6 tends to flow.

However, at the rising edge, the resonance energy is absorbed by the forward resonance current countermeasure diode 11, and the forward resonance current countermeasure diode 11 is shown in FIG.
The current iDF shown in (b) flows. Further, at the fall, the resonance energy is absorbed by the reverse resonance current countermeasure diode 10, and the reverse resonance current countermeasure diode 1 is absorbed.
The current iDR shown in FIG.

Therefore, the resonance current ic shown in FIG. 3 is smaller than the resonance current ic shown in FIG. 6, and the voltage pulse generated in the voltage Vp is also small. On the other hand, the current iL of the power line
As shown in the figure, C is the sum of the current im and the currents iDF and iDR, and the rising and falling are gentle.

In this way, the resonance current ic is reduced, so that the occurrence of electromagnetic interference, the heat generation of the capacitor provided in the power supply line, and the voltage pulse of the power supply line are reduced.

Further, in order to protect the electric compressor driving device 1 and the like, the maximum value of the current im (A in FIG.
It is necessary to monitor the point) with the current detection device, but the current detected by the current detection device is iLC, and its maximum value is equal to the maximum value of the current im because the resonance current ic does not flow. In addition, since the rise of the current iLC is configured to be gentle, it is possible to prevent erroneous detection of the maximum value of the current iLC, so that the current detection of the power supply line becomes extremely accurate.

Further, in this case, since a negative current does not flow in the iLC, the current detecting device does not need a rectifying circuit or the like, and the circuit structure is simplified.

FIG. 4 is a circuit diagram in which the current detection device is specified in the circuit of FIG. 3 (a).

In the figure, by connecting both the forward resonance current countermeasure diode 11 and the reverse resonance current countermeasure diode 10 in parallel to the primary side of the current detection transformer 17, the current of the electric compressor drive device 1 rises and rises. At the time of falling, the energy of the resonance current due to the recovery current countermeasure capacitor 7, the primary side (circuit inductance 9) of the current detection transformer 17 and the stray inductance 8 is the forward resonance current countermeasure diode 11 at the time of rising and at the time of falling. It is absorbed by the diode 10 against the reverse resonance current.

Therefore, the resonance current is reduced, the occurrence of electromagnetic wave interference, the heat generation of the capacitor provided in the power supply line, and the voltage pulse of the power supply line are reduced, so that the above-mentioned specific effect can be obtained.

In this case, the voltage drop due to the DC current flowing through the primary side of the current detection transformer 17 is sufficiently smaller than the forward voltage of the diode 11 for preventing the forward resonance current, so that the operation of the electric circuit is not affected.

The maximum value of the current flowing through the electric compressor drive device 1 is equal to the maximum value of the current flowing through the primary side of the current detection transformer 17. Therefore, the current detection of the power supply line becomes extremely accurate. Further, in this case, since a negative current does not flow, the rectifying diode is unnecessary on the secondary side of the current detection transformer 17.

Although the forward resonance current countermeasure diode 11 is used in the above embodiment, the reverse side resonance current countermeasure diode 10 is used to detect the primary side current of the current detection transformer 17 including the resonance current. It may be used for a protection function or the like.

Other than the above, various applications are possible within a range satisfying the gist of the present invention.

[0047]

According to the present invention, the resonance current is reduced,
As a result, generation of electromagnetic interference, heat generation of the capacitor provided in the power supply line, and voltage pulse of the power supply line are reduced.
Furthermore, the maximum value of the current detected by the current detection device does not flow to the electric compressor drive device because no resonance current flows.
Equal to the maximum value of the current, which makes the current detection of the power line extremely accurate.

Further, according to the present invention, since a negative current does not flow in the current detecting device, the current detecting device does not require a rectifying circuit or the like, and the circuit configuration is simplified.

[Brief description of drawings]

1A is a circuit diagram of an air conditioner according to a first embodiment of the present invention, and FIG. 1B is a waveform diagram thereof.

[Fig. 2] Circuit diagram of the air conditioner

3A is a circuit diagram of an air conditioner according to Embodiment 2 of the present invention, and FIG. 3B is a waveform diagram thereof.

FIG. 4 is a circuit diagram of the air conditioner.

FIG. 5A is a circuit diagram of a conventional air conditioner. (B) is the same illustration (C) is a circuit diagram of another conventional air conditioner

FIG. 6A is a circuit diagram of a conventional air conditioner. (B) is the same waveform diagram

FIG. 7A is a circuit diagram of another conventional air conditioner. (B) is the same waveform diagram

[Explanation of symbols]

1 Electric compressor drive 2 Electric compressor 3 battery 7 Recovery current countermeasure capacitor 8 Stray inductance 9 Circuit inductance 10 Reverse resonance current countermeasure diode 11 Forward resonance current countermeasure diode

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H02M 7/48 G01R 19/00 G01R 33/02

Claims (2)

(57) [Claims] 1. An electric compressor drive device for converting electric power from a direct current power supply into an alternating current to drive an electric compressor, and a capacitor connected between plus and minus of a power supply line connecting the direct current power supply and the electric compressor drive device. A coil inserted in the middle of a power supply line connecting the DC power supply and the electric compressor drive device, a current detection device for detecting a current value flowing in the coil by a magnetic flux generated from the coil, and the coil in parallel with the coil. And a diode connected to the diode ,
An air conditioner connected in such a direction that the rising of the current of the power supply line flowing through the coil becomes gentle. 2. The air conditioner according to claim 1, wherein another diode is additionally connected in parallel with the coil and in a direction opposite to the diode.