JP2000050639A - Inverter device, and air conditioning machine using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inverter device with a simple constitution which can reduce leakage current and noise and to provide an air conditioning machine using the device, by eliminating the need for the means for detecting leakage current. SOLUTION: An inverter device is provided with an inverter circuit 5 in which the plurality of switching elements are bridge-connected, a DC source is connected to a DC terminal and a load is connected to an AC terminal, an inverter control means which on/off-controls the switching elements constituting the inverter circuit 5, and a short time conduction means for supplying the pulse current of a prescribed conduction period which is shorter than the on-period of the switching element to a load at least once by leaving a prescribed halt time, at least immediately before and just after the on-period of the switching element in the inverter circuit 5. An air conditioning machine uses the inverter device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter device for supplying AC power to a load such as an electric motor and an air conditioner using the same.

[0002]

2. Description of the Related Art A stray capacitance exists between an armature winding of an electric motor and a housing connected to a ground terminal. In addition, when driving electric power is supplied to the electric motor via the inverter device, when a switching element included in the inverter device is turned on and off, the ground potential of the winding of the electric motor fluctuates. As a result, current leaks from the winding of the motor to the ground via the stray capacitance. Therefore, for example, in Japanese Patent Application Laid-Open No. 10-42585, the leakage current is reduced by providing a leakage current detecting means and a circuit for flowing a compensation current in a direction opposite to the detected leakage current to the motor. However, since this method is a feedback control, a means for detecting a leakage current is indispensable, and the configuration has been inevitably complicated.

On the other hand, when the switching elements constituting the inverter device are turned on and off, the electric motor generates mechanical vibration and generates noise. For this reason, mechanical measures such as improving the fixing method of the electric motor to reduce noise, and shielding the electric motor with a sound insulating wall to prevent sound are required. In addition, there are problems that must be solved, such as reliability of materials used for mechanical measures and aging.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to reduce a leakage current and a noise with a simple configuration by eliminating a means for detecting a leakage current. It is to provide an inverter device that can be used.

Another object of the present invention is to provide an air conditioner capable of reducing leakage current and noise with a simple configuration.

[0006]

The invention according to claim 1 is
A plurality of switching elements are bridge-connected, a DC power supply is connected to a DC terminal thereof, a load is connected to the AC terminal thereof, an inverter circuit, and an inverter control means for turning on and off switching elements constituting the inverter circuit, At least one of immediately before and immediately after the ON period of the switching element of the inverter circuit, a pulse current of a predetermined energizing period shorter than the ON period of the switching element is supplied to the load at least once with a predetermined pause time. And a short-time energizing means.

According to a second aspect of the present invention, in the inverter device according to the first aspect, the short-time energizing means determines the energizing period and the idle time of the pulse current so as to suppress the current leaking from the load to the ground. And supply it to the load.

According to a third aspect of the present invention, in the inverter device according to the first or second aspect, the short-time energizing means is operated only in a range where the leakage current flowing from the load to the ground exceeds a specified value.

According to a fourth aspect of the present invention, in the inverter device according to the first aspect, the short-time energizing means determines the energizing period and the pause time of the pulse current so as to suppress the vibration generated in the load. Is to be supplied to

According to a fifth aspect of the present invention, in the inverter device according to any one of the first to fourth aspects, the short-time energizing means is a pair of switching elements connected in series between the positive and negative electrodes of the DC power supply. A predetermined one of a pair of switching elements is selected based on a capacitor connected between the interconnection point of the switching elements and the ground, and an on / off control signal of an inverter control means for the inverter circuit. And a waveform generating means for controlling ON / OFF of the selected switching element for a predetermined energizing period and a pause time.

According to a sixth aspect of the present invention, in the inverter device according to any one of the first to fifth aspects, the inverter control means and the short-time energizing means are constituted by a single microcomputer.

According to a seventh aspect of the present invention, in the inverter device according to any one of the first to third aspects, the inverter control means and the short-time energizing means are constituted by a single microcomputer, and the inverter control means comprises a PWM voltage. Is supplied to the load, and the short-time energizing means controls the inverter circuit so as to supply the pulse current to the load at least one of immediately before and immediately after the ON period of the PWM voltage waveform.

According to an eighth aspect of the present invention, in the inverter device according to any one of the first to seventh aspects, the energizing period and the quiescent time of the pulse current are controlled by the switching element and the short-time energizing means constituting the inverter circuit. The correction is performed in consideration of the delay time associated with the rise and fall of the switching element.

According to a ninth aspect of the present invention, there is provided an air conditioner for supplying drive power to a motor for driving a compressor forming a refrigeration cycle using the inverter device according to any one of the first to eighth aspects. .

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on preferred embodiments. FIG. 1 is a block diagram showing the configuration of the first embodiment of the present invention. In FIG. 1, a rectifier circuit 2 is connected to an AC power supply 1 and a smoothing capacitor 3 is connected to an output side of the rectifier circuit 2 to constitute a known DC power supply. An inverter circuit 5 is connected to this DC power supply via a low-pass filter 4 for removing noise. A leakage current reducing circuit 6 is connected between the positive and negative DC power lines between the low-pass filter 4 and the inverter circuit 5. The microcomputer 7 includes an inverter control unit for controlling the inverter circuit 5 and a leakage current reduction waveform generation unit for controlling the leakage current reduction circuit 6.

FIG. 2 is a circuit diagram showing a detailed configuration of the inverter circuit 5 and the leakage current reduction circuit 6 together with a compressor drive motor 11 of a refrigeration cycle as a load, for example. In FIG. 2, the inverter circuit 5 includes 6 switching elements each having a diode connected in anti-parallel.
Transistors X1, X2, X3, Y1, Y2, Y3
Are connected in a three-phase bridge, and their DC terminals, that is, a series connection circuit of transistors X1 and Y1, a series connection circuit of X2 and Y2, and transistors X3 and Y
The DC power supply lines P and N are connected to the parallel connection end with the series connection circuit 3 and the AC terminal thereof, that is, the transistor X1
, Y1, the transistors X2, Y2 and the transistors X3, Y3 are connected to one end of the phase windings U, V, W of the compressor drive motor 11, respectively. The other ends of the phase windings U, V, W are commonly connected. In this case, stray capacitances Cu, Cv and Cw exist between the phase windings U, V and W and their housings, that is, between the ground terminals.

The leakage current reducing circuit 6 has a DC power supply line P at one end of a series connection circuit of two transistors G1 and G2.
The other end is connected to the DC power supply line N, and the interconnection point of the transistors G1 and G2 is grounded via the impedance element Z and the capacitor C.

The operation of the first embodiment configured as described above will be described below with reference to FIGS. First, the AC voltage of the AC power supply 1 is rectified by the rectifier circuit 2, and the obtained pulsating current is smoothed by the smoothing capacitor 3 to become a DC voltage, which is passed through the low-pass filter 4 to the inverter circuit 5. Added. The low-pass filter 4 has both positive and negative coils synchronously wound around one core,
This prevents noise components on the load side from leaking to the power supply side. The inverter control means constituted by the microcomputer 7 controls the six transistors constituting the inverter circuit 5 so that the PWM voltage according to the frequency command determined according to the air conditioning load is supplied to the compressor drive motor 11. X1, X2, X3, Y1, Y2, Y3 are turned on and off. FIG. 3A shows this PWM voltage waveform,
The on-period, that is, the on-duty, is controlled for a predetermined PWM cycle.

Further, the leakage current reduction waveform generation means constituted by the microcomputer 7 immediately before the voltage during the above-mentioned PWM ON period rises, as shown in FIG.
A leakage current reduction signal whose energization period is x and whose idle period is y is transmitted to two transistors G1 and G2 of the leakage current reduction circuit 6.
G2 and a pulse current is supplied to the compressor drive motor 11.

In this case, when the voltage rises during the PWM ON period, the stray capacitances Cu and Cv of the compressor drive motor 11 are increased.
, Cw, the transient oscillating current shown in the leakage current waveform of FIG. At this time, the pulse current based on the leakage current reduction signal having the energization period of x and the pause period of y is supplied to the compressor drive motor 11 to suppress the leakage current during the PWM ON period. That is, the transient oscillating current shown in the leakage current waveform of FIG. 3C is caused to flow by the rising pulse current of the leakage current reduction signal, and the pulse current of FIG. 3C is caused by the falling pulse current of the leakage current reduction signal. The transient oscillating current shown in the leakage current waveform is applied. As a result, as shown in the leakage current waveform of FIG. 3C, three oscillating currents are superimposed during the PWM ON period, and the current value is suppressed to substantially zero.

In the inverter circuit 5, since any one of the transistors X1, X2, X3 and any one of the transistors Y1, Y2, Y3 constituting the inverter circuit 5 are on, the leakage current is reduced. The transistors G1 and G constituting the leakage current reducing circuit 6 according to the signal
When one of the two is turned on, a pulse current can flow to the compressor drive motor 11 via the impedance element Z and the capacitor C. That is, when the transistor G1 of the leakage current reducing circuit 6 is turned on, the DC power supply line P → the transistor G1 → the impedance element Z →
A pulse current flows through the path of the capacitor C → the ground E → the stray capacitance Cu → the phase winding U → the transistor Y1 → the DC power supply line N. On the other hand, when the transistor G2 of the leakage current reducing circuit 6 is turned on, the DC power supply line P → the transistor X3 → the phase winding W → the stray capacitance Cw → the ground E → the capacitor C → the impedance element Z → the transistor G2 → the DC power supply line N The pulse current flows through the path.

If the transient oscillating current waveform and cycle of the leakage current generated when the PWM voltage waveform rises are measured in advance, it is determined which of the transistors G1 and G2 should be turned on and the leakage current reduction signal is supplied. It is possible to determine how long the period x and the idle period y should be.

The conduction period x and the pause period y of the leakage current reduction signal shown in the first embodiment are determined by the following equation, where T is the oscillation period of the leakage current.

X = ± π / (3ω) + 2aπ / ω (1) y = ± π / (3ω) + 2bπ / ω (2) where ω = 2π / T a = 1, 2, 3,. .., X> 0 y> 0, and the values of a and b need not be the same.
If the sign of the first term in equation (1) is +,
When the compound of the first term in the expression (2) for obtaining y is also +, and when the compound of the first item in the expression (1) for obtaining x is-, y
In the equation (2), the compound of the first term is also-. Also,
FIG. 3 shows a case where x = y = π / 3ω. By generating a current waveform similar to a three-phase AC waveform, the leakage current reduction effect can be maximized.

The impedance of the load including the stray capacitance as viewed from the inverter circuit 5 with respect to the ground may not be the same as the impedance as viewed from the ground through the capacitor of the leakage current reducing circuit 6 from the DC power supply. In consideration of this, the impedance element Z is selected and connected so that these impedances substantially match.

Thus, according to the first embodiment, PW
The leakage current during the PWM ON period based on the change in the voltage rise during the M ON period can be suppressed to a very small value.

The above-described current leakage also occurs when the voltage falls during the PWM ON period. That is, the stray capacitance C
Due to the presence of u, Cv and Cw, a transient oscillating current shown in the leakage current waveform of FIG. 4C flows into the ground. At this time, the leakage current during the PWM off period can be suppressed by supplying a pulse current based on the leakage current reduction signal having the energization period of x and the pause period of y to the compressor drive motor 11. In this case, a transient oscillating current shown in the leakage current waveform of FIG. 4C is caused to flow by the rising pulse current of the leakage current reduction signal, and FIG. 4C is caused by the falling pulse current of the leakage current reduction signal. The transient oscillating current shown by the leakage current waveform shown in FIG. In this case, the energizing period x and the halt period y of the leakage current reduction signal are as described in (1)
It can be determined in exactly the same way as equation (2).

As a result, as shown in the leakage current waveform of FIG. 4C, the leakage current in the PWM off period based on the change in the voltage fall in the PWM on period can be suppressed to a very small value.

Also, by adding the leakage current reduction signal immediately before the PWM ON period shown in FIG. 3 and the leakage current reduction signal immediately after the PWM ON period shown in FIG. The leakage current can be kept small over the entire period. By the way, in the above-described example, the PWM based on the change of the voltage rise during the PWM ON period
In order to suppress the leakage current during the ON period, one pulse current is supplied immediately before the PWM ON period in FIG. 3, and in FIG. 4, the pulse current during the PWM OFF period is changed based on the change in the voltage fall during the PWM ON period. To reduce leakage current, P
One pulse current was supplied immediately after the WM ON period,
These pulse currents are not limited to one,
Even if two or more pulse currents are supplied based on a current waveform and an oscillation cycle obtained by measuring in advance so as to reduce the leakage current, leakage in the PWM on period based on a change in voltage rise during the PWM on period It is possible to suppress the leakage current during the PWM off period based on the change in the current or the voltage fall during the PWM on period. FIG. 5 is a waveform diagram for explaining an operation of supplying two pulse currents and reducing a leakage current in the PWM ON period based on a change in a voltage rise in the PWM ON period. In this case, the pulse current is supplied twice immediately before the PWM ON period, and the energizing period x and the pause period y can be determined by the following equations.

X = y = π / 5ω (3) where ω = 2π / T.

FIG. 6 shows that PW is supplied by supplying two pulse currents.
FIG. 9 is a waveform diagram for explaining an operation for reducing a leakage current during a PWM off period based on a change in voltage falling during an M on period. In this case, the pulse current is supplied twice immediately after the PWM off period, and the energizing period x and the pause period y can be determined by the equation (3).

Since the leakage current waveform is considered to be a periodic function, a configuration in which three or more pulse currents are supplied immediately before or immediately after the PWM ON period may be employed. , And the description thereof will be omitted.

Further, one or more leakage current reduction signals are applied to the leakage current reduction circuit 6 immediately before the PWM ON period,
Even if one or a plurality of leakage current reduction signals are added to the leakage current reduction circuit 6 immediately after the WM ON period, the leakage current can be kept small over the entire operation period.

Thus, according to the first embodiment, by eliminating the means for detecting the leakage current,
The leakage current can be reduced with a simple configuration.

In the first embodiment described above, the same microcomputer 7 waits for the leakage current reduction waveform generating means for controlling the on / off of the leakage current reduction circuit 6 and the inverter control means for controlling the inverter circuit 5. However, even if these means are separately provided, the same operation as described above can be performed. FIG. 7 is a block diagram showing the configuration of the second embodiment according to this concept. In the figure, the same elements as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.
In this embodiment, a microcomputer is provided with an inverter control means 9, and a leakage current reducing waveform generating means 8 for controlling the leakage current reducing circuit 6 is provided separately from the microcomputer. In this case, the leakage current reduction waveform generation means 8 generates one or both of the leakage current reduction signals of FIGS. 3B and 4B based on the control signal of the inverter control means 9. Or Figure 5
(B) and / or FIG. 6 (b).

FIG. 8 shows a third embodiment of the inverter device according to the present invention.
1 is a block diagram showing a configuration of an embodiment of FIG.
The same elements as those described above are denoted by the same reference numerals and description thereof will be omitted. In this embodiment, the inverter control means 10 generates both a PWM signal and a leakage current reduction signal, and controls ON / OFF of a switching element included in the inverter circuit 5. Here, the inverter control means 10 corresponds to FIG.
As shown by the broken line in (a), the leakage current reduction signal SA is generated immediately before the PWM-on period to reduce the leakage current in the PWM-on period, or as shown by the broken line in FIG. Thus, immediately after the PWM ON period, the leakage current reduction signal SB
To reduce the leakage current during the PWM off period. In this case, the energizing period x and the rest period y
Can be determined by equations (1) and (2). Further, only the inverter control means 10 is used as shown in FIG.
As shown by the broken line in FIG. 6, two leakage current reduction signals SA are generated immediately before the PWM ON period to reduce the leakage current during the PWM ON period, or are shown by the broken line in FIG. As described above, two leakage current reduction signals SB can be generated immediately after the PWM ON period to reduce the leakage current during the PWM OFF period.

According to the third embodiment shown in FIG. 8, the leakage current reducing circuit 6 provided in the first to fifth embodiments can be eliminated, and the leakage current can be reduced with a simpler configuration. Has the effect of reducing According to the third embodiment shown in FIG. 8, when a microcomputer is used as the inverter control means, a leakage current reduction function can be provided only by changing a program. There is also an advantage that can be applied.

When the power is supplied for a short time through the leakage current reducing circuit 6, the power loss is correspondingly caused, so that the leakage current flowing through the load to the ground satisfies, for example, an allowable range defined in Japanese Industrial Standards. Executing the short-time energization control only in the load range where no power is applied can minimize the reduction in efficiency and reduce the leakage current to a standard value or less.

When the switching elements of the inverter circuit 5 are turned on and off, not only leakage current is generated due to stray capacitance but also electromagnetic noise of a specific cycle, that is, vibration noise is generated by switching. is there. As described above, this noise is generated by changing the pulse current of the predetermined energizing period shorter than the ON period of the switching element to the predetermined pause time at least immediately before and immediately after the PWM ON period of the switching element of the inverter circuit 5. It is possible to reduce the power consumption by providing a short-time energizing means for supplying the load at least once.

As a specific method, an oscillating current reducing circuit having the same configuration as the leakage current reducing circuit 6 shown in FIG. 1 is provided, and a vibration reducing waveform generating means is replaced with a microcontroller instead of the leak current reducing waveform generating means. A configuration that the computer 7 has can be considered. Further, as in the example shown in FIG. 7, an independent vibration reduction waveform generating means may be provided in addition to the inverter control means 9, or the inverter circuit 5 is controlled as in the example shown in FIG. The inverter control means 10 may be configured to include a vibration reduction waveform generation function.

FIG. 9 is a waveform diagram for explaining the operation of the fourth embodiment in which the inverter control means 10 for controlling the inverter circuit 5 has a function of generating a vibration reduction waveform. In this case, when the voltage rises during the PWM ON period, a transient oscillating current shown by the oscillating waveform in FIG. 9B flows through the phase winding of the compressor drive motor 11. At this time, by supplying a pulse current based on the vibration reduction signal having the energization period of x and the suspension period of y to the compressor drive motor 11, the vibration during the PWM ON period is suppressed. That is, a transient oscillating current shown in the oscillation waveform of FIG. 9B is caused to flow by the rise of the pulse current based on the vibration reduction signal, and FIG.
The transient oscillating current shown in the oscillation waveform of FIG. As a result, the vibration is suppressed as shown in the vibration waveform of FIG. 9C.

Thus, it is possible to determine how long the energizing period x and the halt period y of the vibration reduction signal should be in accordance with the transient oscillating current waveform and the period of the oscillation generated when the PWM voltage waveform rises. .

By the way, the energizing period x and the halt period y of the vibration reduction signal shown in the fourth embodiment shown in FIG.

X = ± π / (3ω) + 2aπ / ω (4) y = ± π / (3ω) + 2bπ / ω (5) where ω = 2π / T a = 1, 2, 3,. .., X> 0 y> 0, and the values of a and b need not be the same.
Is +, the compound of the first term in the formula for obtaining y is also +, and the compound of the first term in the formula for obtaining x is-and In this case, the compound in the formula for obtaining y is also-. FIG. 9 shows the case where x = y = π / 3ω. By generating a current waveform similar to the three-phase AC waveform, the vibration reduction effect can be maximized.

The above-mentioned vibration noise also occurs when the voltage falls during the PWM ON period. That is, FIG.
A transient vibration shown by the vibration waveform of FIG. At this time, as shown in FIG. 10 (a), a pulse current based on a vibration reduction signal having an energization period of x and a pause period of y is supplied to the compressor drive motor 11 to suppress vibration during the PWM off period. Can be. In this case, the rise of the pulse current based on the vibration reduction signal causes the rise of the pulse current in FIG.
FIG. 1 shows the transient waveform shown in FIG. 1 and the falling of the pulse current based on the vibration reduction signal.
The transitional vibration shown by the vibration waveform of 0 (b) occurs. As a result, vibration is suppressed as shown in the vibration waveform of FIG.

In this case, the energizing period x and the pause period y of the vibration reduction signal can be determined in exactly the same manner as in the above equations (4) and (5).

Thus, according to the fourth embodiment, PW
Oscillation during the PWM off period based on a change in the voltage falling during the M on period can be suppressed to a very small level.

In the example shown in FIG. 9, one pulse current is supplied immediately before the PWM ON period in order to suppress the oscillation during the PWM ON period based on a change in the voltage rise during the PWM ON period. In the example, one pulse current is supplied immediately after the PWM on period in order to suppress the oscillation in the PWM off period based on the change in the voltage fall during the PWM on period, but these pulse currents are limited to one. However, even if two or more pulse currents are supplied based on a current waveform and a vibration cycle obtained by measuring in advance so as to reduce the vibration, it is based on a change in the voltage rise during the PWM ON period. It is possible to suppress the vibration during the PWM on period and the vibration during the PWM off period based on a change in the fall of the voltage during the PWM on period.

FIG. 11 shows that two pulse currents are supplied and P
FIG. 7 is a waveform diagram for explaining an operation of reducing vibration during a PWM on period based on a change in voltage rise during a WM on period. In this case, assuming that the pulse current is supplied twice immediately before the PWM ON period, the energization period x and the pause period y can be determined by the following equations.

X = y = π / 5ω (6) where ω = 2π / T.

FIG. 12 shows that two pulse currents are supplied and P
FIG. 7 is a waveform diagram for explaining an operation of reducing vibration in a PWM off period based on a change in voltage falling during a WM on period. In this case, if the pulse current is supplied twice immediately after the PWM off period, the energizing period x and the pause period y can be determined by the equation (6).

Since the vibration waveform is considered to be a periodic function, it is possible to supply three or more pulse currents immediately before or immediately after the PWM ON period. A description thereof will be omitted.

As is clear from the above description, according to the embodiments shown in FIGS. 9 to 12, vibration noise can be reduced with a simple configuration by eliminating the need for a means for detecting vibration. be able to.

In each of the above-described embodiments, the transistors X 1,
X2, X3, Y1, Y2, and Y3 require switching time. Therefore, as shown in FIG. 13A, the vibration reduction signal generated by the waveform
As shown in FIG. 3B, the transistors X1, X2, X3
, Y1, Y2, Y3 rise or fall with a delay. Further, the delay time at the rise is longer than the delay time at the fall. Therefore, the effect of the switching time can be eliminated by adding a function of compensating for the delay time to the waveform generating means. FIG.
(C) is the energization period x obtained by the above equations (4) to (6).
This is an example in which the output waveform of the waveform generating means is corrected so that the current of the idle period y flows, whereby the energizing period x and the idle period y shown in FIG. 13D can be secured.

FIG. 14 is a block diagram showing a configuration of an embodiment of an air conditioner using the inverter device according to the present invention. In the drawing, the same elements as those in FIG. Description is omitted. Here, a compressor drive motor 11 is connected to the leakage current reduction circuit 6 as a load. A compressor 12 is connected to the compressor drive motor 11, and a discharge side and a suction side of the compressor 12 are connected to a four-way valve 13, respectively. A well-known refrigerating cycle consisting of the compressor 12, the four-way valve 13, the indoor heat exchanger 14, the expansion valve 15, the outdoor heat exchanger 16, the four-way valve 13, and the compressor 12 is formed. An indoor fan 17 is provided to promote heat exchange of the exchanger 14, and an outdoor fan 18 is provided to promote heat exchange of the outdoor heat exchanger 16.

Here, the microcomputer 7 having the inverter control means and the leakage current reduction waveform generation means controls the inverter circuit 5 and the leakage current reduction circuit 6 to reduce the leakage current with a simple configuration. An air conditioner that can be obtained is obtained.

Although the air conditioner shown in FIG. 14 uses the inverter device shown in FIG. 1, the other air conditioners described with reference to FIGS. The leakage current can be reduced with a simple configuration.

Further, by controlling the inverter circuit 5 and the leakage current reducing circuit 6 by the microcomputer 7 having the vibration reducing waveform generating means described with reference to FIGS. An air conditioner that can be reduced is obtained.

[0059]

As is apparent from the above description, according to the inverter device of the present invention, it is possible to reduce leakage current and noise with a simple configuration.

According to the air conditioner of the present invention,
Leakage current and noise can be reduced with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment of an inverter device according to the present invention.

FIG. 2 is a circuit diagram showing a detailed configuration of main elements constituting the embodiment shown in FIG. 1;

FIG. 3 is a waveform chart for explaining the operation of the embodiment shown in FIG. 1;

FIG. 4 is a waveform chart for explaining the operation of the embodiment shown in FIG. 1;

FIG. 5 is a waveform chart for explaining the operation of the embodiment shown in FIG. 1;

FIG. 6 is a waveform chart for explaining the operation of the embodiment shown in FIG. 1;

FIG. 7 is a block diagram showing the configuration of a second embodiment of the inverter device according to the present invention.

FIG. 8 is a block diagram showing a configuration of a third embodiment of the inverter device according to the present invention.

FIG. 9 is a waveform chart for explaining the operation of the fourth embodiment of the inverter device according to the present invention.

FIG. 10 is a waveform chart for explaining the operation of the fourth embodiment of the inverter device according to the present invention.

FIG. 11 is a waveform chart for explaining the operation of the fourth embodiment of the inverter device according to the present invention.

FIG. 12 is a waveform chart for explaining the operation of the fourth embodiment of the inverter device according to the present invention.

FIG. 13 is a waveform chart for explaining the operation of the fourth embodiment of the inverter device according to the present invention.

FIG. 14 is a block diagram showing a configuration of an embodiment of an air conditioner according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 AC power supply 2 Rectifier circuit 3 Smoothing capacitor 4 Low-pass filter 5 Inverter circuit 6 Leakage current reduction circuit 7 Microcomputer 8 Leakage current reduction waveform generation means 9, 10 Inverter control means 11 Compressor drive motor 12 Compressor 13 Four-way valve 14 Indoor heat exchanger 15 Expansion valve 16 Outdoor heat exchanger 17 Indoor fan 18 Outdoor fan

Claims (9)

[Claims] 1. An inverter circuit in which a plurality of switching elements are bridge-connected, a DC power supply is connected to a DC terminal thereof, and a load is connected to an AC terminal thereof, and ON / OFF control of switching elements constituting the inverter circuit is performed. Inverter control means, and at least one of immediately before and immediately after the on-period of the switching element of the inverter circuit, the pulse current of a predetermined energizing period shorter than the on-period of the switching element is set to a predetermined pause time. And a short-time energizing means for supplying the load to the load at least once. 2. The inverter device according to claim 1, wherein the short-time energizing means determines an energizing period and a pause time of the pulse current so as to suppress a current leaking from the load to the ground and supplies the pulse current to the load. . 3. The inverter device according to claim 1, wherein the short-time energizing means is operated only in a range where a leakage current flowing from the load to the ground exceeds a standard value. 4. The inverter device according to claim 1, wherein the short-time energizing means determines an energizing period and a pause time of the pulse current so as to suppress vibration generated in the load, and supplies the pulse current to the load. 5. The short-time energizing means includes: a pair of switching elements connected in series between a positive electrode and a negative electrode of the DC power supply; and a capacitor connected between an interconnection point of the switching elements and the ground. Selecting a predetermined one of the pair of switching elements based on an on / off control signal of the inverter control means for the inverter circuit, and setting the selected switching element to a predetermined energizing period and a pause. The inverter device according to any one of claims 1 to 4, further comprising: a waveform generation unit that performs on / off control with time. 6. The inverter device according to claim 1, wherein said inverter control means and said short-time energizing means are constituted by a single microcomputer. 7. The inverter control means and the short-time power supply means are constituted by a single microcomputer, and the inverter control means controls the inverter circuit so as to supply a PWM voltage to a load. The means is P
The inverter device according to any one of claims 1 to 3, wherein the inverter circuit is controlled so as to supply a pulse current to the load at least immediately before and immediately after the ON period of the WM voltage waveform. 8. A pulse current conduction period and a pause time are corrected in consideration of a delay time associated with a rise and a fall of a switching element constituting the inverter circuit and a switching element constituting the short-time conduction means. The inverter device according to claim 1. 9. An air conditioner that supplies drive power to an electric motor that drives a compressor forming a refrigeration cycle, using the inverter device according to claim 1. Description: