JP2003111491A - Power converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely reduce a leakage current by obtaining a high gain even in the case of a relatively small leakage current. SOLUTION: The power converter converts an AC power from an AC power source 101 into an AC power having an arbitrary frequency, and supplies the AC power to a motor 107 to drive the motor at a variable speed. The converter comprises a noise reducing circuit for detecting the leakage current from the power source line of the power source 101, inputting the leakage current to the amplifiers 130, 133, regulating the gain by a resistor to obtain a noise compensating current, and supplying a noise compensating current to an earth line of a power converter body so as to cancel the leakage current. The converter further comprises a plurality of the noise reducing circuits, in such a manner that the operations of the amplifiers 130, 133 of each noise reducing circuit correspond to the levels of the leakage currents and set to incorporate a difference of operating regions to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power converter device provided with a noise reduction circuit for supplying a noise compensation current so as to cancel a leakage current when a motor is driven at a variable speed on the basis of AC power. The present invention relates to a power converter device capable of reliably reducing the leakage current even when the leakage current is relatively small.

[0002]

2. Description of the Related Art Conventionally, when driving an electric motor for driving an elevator, for example, a power converter capable of supplying a desired power has been widely used.

Typical examples of this type of power converter are, for example, GTO (Gate turn-off thyristor) and IGB.
There is an inverter device in which a plurality of semiconductor switching elements such as T (insulated gate bipolar transistor) are arranged in series and parallel.

This inverter device will be described as a typical example of the power conversion device in the following description.

In recent years, in a drive system for an electric motor using this type of inverter device, a ground leakage current (hereinafter referred to as a leakage current) accompanying high-speed switching of each semiconductor switching element has been noted as a problem.

Therefore, in order to solve such a problem, recently, a power converter device having a noise reduction circuit for supplying a noise compensation current so as to cancel a leakage current has been proposed.

FIG. 8 is a circuit diagram showing an example of the overall configuration of a power converter device provided with a conventional noise reduction circuit of this type.

In FIG. 6, an AC three-phase AC voltage is supplied from an AC power supply 1 to a full-wave rectifier circuit 2.

The full-wave rectifier circuit 2 is composed of a plurality of diode elements D1 to D6 connected to a three-phase bridge, converts this three-phase AC voltage into a DC voltage, and this DC voltage is connected to the positive side input line P. Supply to the inverter device 3 from between the negative side input line N.

The inverter device 3 comprises a plurality of switching elements Q1 to Q6 connected in a three-phase bridge, and each switching element Q1 by a gate drive circuit (not shown).
The pulse width voltage of which the width is controlled is applied to the winding of each phase of the electric motor 4 by the PWM (pulse width modulation) control of Q6.

The electric motor 4 is driven by this pulsed voltage.

Then, due to the voltage change rate dv / dt at this time, a leakage current as a noise current flows to the ground through the stray capacitance C between the four windings of the motor and the frame ground.

This leakage current passes through each earth line between the electric motor 4 and the earth terminal of the AC power source 1 and the ground,
According to the polarity, the current flows in or out of the ground terminal of the AC power supply 1.

Therefore, the leakage current causes a malfunction of the leakage breaker or an electric shock accident.

Therefore, in order to reduce this leakage current, a noise reduction circuit 6 is provided.

The noise reduction circuit 6 controls the leakage current based on the leakage current detected by the leakage current detector 5 which detects the leakage current from the power supply line between the AC power supply 1 and the full-wave rectification circuit 2. A noise compensation current is applied to the ground line so as to cancel it.

That is, the noise reduction circuit 6 rectifies the AC voltage, which is insulated by the transformer 7 from the phase that does not fall to the ground as the power source, by the diode bridge circuit 8 and rectifies the two smoothing capacitors 9a and 9b. Stabilize as a DC voltage via.

Then, the signal of the leakage current detected by the leakage current detector 5 for detecting the leakage current is inverted and amplified by the inverting amplifier circuit 10 and connected to the DC voltage.
The noise current compensation component is flown to the earth line connected via the capacitor C _E by the type transistor TR1 and the PNP type transistor TR2.

[0019]

By the way, in the power converter having the conventional noise reduction circuit as described above, when the leakage current is large, the noise is adjusted according to the peak value of the leakage current. Since the gain of the inverting amplifier circuit 10 of the reduction circuit 6 is set, the leakage current cannot be sufficiently reduced in the case where the magnitude of the leakage current is relatively small.

Therefore, recently, the emergence of means capable of reliably reducing the leakage current even when the leakage current is relatively small has been strongly desired.

An object of the present invention is to provide a power conversion device which can obtain a high gain even when the leakage current is relatively small and can surely reduce the leakage current.

[0022]

To achieve the above object, in the invention corresponding to claim 1, the AC power from the AC power supply is converted into AC power having an arbitrary frequency, and the AC power is converted into a motor. To the variable speed drive,
Leakage current is detected from the power supply line of the AC power supply, the leakage current is input to the amplifier circuit, the gain is adjusted by a resistor to obtain noise compensation current, and the noise compensation is performed on the ground line of the power converter so as to cancel the leakage current. In a power conversion device configured to include a noise reduction circuit that flows current, the noise reduction circuit is provided in a plurality of circuits, and the operation of the amplification circuit of each noise reduction circuit differs depending on the level of the leakage current. Is set to have.

Therefore, in the power converter of the invention according to claim 1, a plurality of noise reduction circuits are provided,
By setting the operation of the amplifier circuit of each noise reduction circuit so that the operation area has a difference depending on the level of the leakage current, a high gain can be obtained even when the level of the leakage current is low. As a result, it is possible to reduce the leakage current at the time of switching of the switching element of the power conversion device. That is, even if the leakage current is relatively small, the leakage current can be surely reduced.

Further, in the invention according to claim 2, in the power converter of the invention according to claim 1, the operation of the amplifier circuit for the leakage current in each noise reduction circuit is performed.
A series circuit including a constant voltage diode and a variable resistor is connected to the input portion of the amplifier circuit of the noise reduction circuit other than the noise reduction circuit that performs the leakage current compensation operation.

Therefore, in the power converter of the invention according to claim 2, among the noise reduction circuits, the noise reduction circuits other than the noise reduction circuit for performing the amplification circuit operation / leakage current compensation operation for the leakage current are included. By connecting a series circuit composed of a constant voltage diode and a variable resistor to the input part of the amplifier circuit, in addition to the same operation as the invention corresponding to claim 1, the noise reduction circuit Since it becomes possible to change the operation region of the amplifier circuit, it is possible to carry out adjustment corresponding to the external environment.

Further, in the invention according to claim 3, in the power converter of the invention according to claim 1, Hall CT is used as means for detecting a leakage current, and the main circuit wire of the input power source of the power converter is used. When it is not possible to penetrate the hole CT into the hole CT, connect auxiliary wires in parallel to the extent that the main circuit wire of the input power supply can penetrate into the hole CT, and penetrate the hole CT into the auxiliary wire. ing.

Therefore, in the power converter of the invention according to claim 3, the Hall CT is used as a means for detecting the leakage current, and the main circuit wire of the input power source of the power converter cannot be penetrated into the Hall CT. In such a case, an auxiliary electric wire to the extent that the main circuit electric wire of the input power source of the power conversion unit can be penetrated into the hole CT is connected in parallel, and the hole CT is penetrated into the auxiliary electric wire. As a result, in addition to the same effect as the invention corresponding to claim 1, the leak current detecting means similar to the above-described conventional configuration can be applied to a device having a large power conversion unit capacity. .

Furthermore, in the invention according to claim 4, in the power converter of the invention according to claim 1, DC power supplies serving as power supplies for noise compensation current in each noise reduction circuit are connected in parallel. Have been shared.

Therefore, in the power converter of the invention according to claim 4, the DC power supplies that are the power supplies for the noise compensation currents in the noise reduction circuits are connected in parallel and shared. Thus, in addition to achieving the same effect as the invention corresponding to claim 1,
The number of parts can be reduced.

On the other hand, in the invention according to claim 5, in the power converter of the invention according to claim 1, the peak value of the output from the amplifier circuit is used as the adjusting means of the gain of the amplifier circuit in each noise reduction circuit. A peak hold means for holding and outputting is provided for each noise reduction circuit.

Therefore, in the power converter of the invention according to claim 5, the peak value of the output from the amplifier circuit is held and output, so that it is the same as the invention according to claim 1. In addition to the above effect, it is possible to adjust the gain by the resistance based on the hold voltage of the peak hold means. Therefore, even when a plurality of noise reduction circuits are provided,
It is possible to easily adjust the gain of the noise reduction circuit.

Further, in the invention according to claim 6, in the power conversion device of the invention according to claim 5, voltage measuring means for measuring the voltage output from the peak hold means is added.

Therefore, in the power converter of the invention according to claim 6, by measuring the voltage output from the peak hold means, the same effect as that of the invention according to claim 5 can be obtained. In addition to the above, it becomes possible to confirm the hold voltage of the peak hold means by the voltage measuring means. Therefore, even when a plurality of noise reducing circuits are provided, the noise reducing circuit can be simply provided by only the voltage measuring means. The gain can be adjusted.

Further, in the invention corresponding to claim 7, in the power conversion device of the invention according to claim 5 or 6, the gain adjusting mode switch means for resetting the hold voltage in the peak hold means is added. ing.

Therefore, in the power converter of the invention according to claim 7, the hold voltage of the peak hold means is reset, so that the same as the invention according to claim 5 or 6 is obtained. Since the adjustment operation can be repeatedly performed in addition to the effect, the gain of the noise reduction circuit can be easily adjusted even when a plurality of noise reduction circuits are provided.

On the other hand, in the invention according to claim 8, in the power converter of the invention according to claim 1, an electronic potentiometer is used as a resistor for adjusting the gain of the amplifier circuit, which is output from the peak hold means. A / D conversion means for converting the output voltage to a digital signal and outputting the digital signal, and A / D
A microcomputer that calculates and outputs a gain based on the output from the conversion unit and a unit that adjusts the resistance value of the electronic volume based on the output from the microcomputer are added.

Therefore, in the power converter of the invention according to claim 8, the gain is calculated based on the hold voltage of the peak hold means, and the gain is output to the electronic volume to adjust the resistance value. In addition to the same effect as the invention according to claim 1 described above, the gain of the amplifier circuit of each noise reduction circuit can be automatically adjusted. Therefore, when a plurality of noise reduction circuits are provided. Also in this case, the gain of the noise reduction circuit can be easily adjusted.

Further, in the invention corresponding to claim 9, in the power converter of the invention according to claim 8, gain adjustment mode switch means for resetting the hold voltage in the peak hold means is added, and the power from the microcomputer. The resistance value of the electronic volume is automatically adjusted based on the output, and the gain adjustment mode switch means is automatically opened and closed.

Therefore, in the power converter of the invention according to claim 9, the hold voltage of the peak hold means is automatically reset, so that the same operation as that of the invention according to claim 8 is achieved. In addition to the above, it is possible to repeat the adjustment operation, so even when a plurality of noise reduction circuits are provided,
It is possible to easily adjust the gain of the noise reduction circuit.

[0040]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(First Embodiment) FIG. 1 is a circuit diagram showing an example of the overall configuration of a power conversion device equipped with a noise reduction circuit according to this embodiment.

Although FIG. 1 shows an example in which the commercial AC three-phase power supply has a Y connection, the commercial AC three-phase power supply has the same Δ connection configuration as the conventional one described above. Also, although this embodiment can be similarly applied,
The description thereof will be omitted here.

In FIG. 1, a commercial three-phase AC input power source (Y
An AC three-phase AC voltage is supplied from the (connection) 101 to the rectifier circuit of the power converter via the reactors 103a to 103c for each of the three phases.

The rectifier circuit of this power converter has P side, N side
Is configured by bridge-connecting the switching elements 104 for the three phases on the side, the three-phase AC voltage is converted into a DC voltage, and this DC voltage is passed through the smoothing capacitor 105 of the DC link unit of the power converter. It supplies to the inverter of a power converter from between a positive side input line P and a negative side input line N.

The inverters of this power converter are
The switching elements 106 for the three phases on the N side are bridge-connected to each other, and a PWM (pulse width modu
lation), a pulse-shaped voltage having a controlled width is applied to the winding of each phase of the electric motor 107.

The electric motor 107 is driven by this pulsed voltage.

Then, due to the voltage change rate dv / dt at this time, a leakage current as a noise current flows to the ground through the stray capacitance C between the winding of the motor 107 and the frame ground.

This leakage current flows into or out of the earth terminal 135 of the commercial three-phase AC power supply 101 through each earth line and the ground between the electric motor 107 and the ground terminal 135 of the commercial three-phase AC power supply 101. It flows according to the polarity.

Therefore, the leakage current causes a malfunction of the leakage breaker or an electric shock accident.

Therefore, in order to reduce the leakage current, a noise reduction circuit, which is surrounded by a dashed-dotted line in the figure and is composed of an inverting amplifier circuit 130 and a DC power supply unit 131 for supplying a noise current compensation component, is provided.

This noise reduction circuit is based on the leakage current detected by the leakage current detector 102 which detects the leakage current from the power supply line between the commercial three-phase AC power supply 101 and the rectifier circuit of the power converter. A noise compensation current is sent to the ground line so as to cancel the leakage current.

DC power supply unit 131 of this noise reduction circuit
The AC voltage extracted by the capacitors 108a to 108c for forming the neutral point potential of the commercial three-phase AC power supply 101 is converted into a DC voltage via two smoothing capacitors 116a and 116b connected in series. Stabilize.

Further, the smoothing capacitors 116a, 1
NPN type transistor 1 is provided at both ends of the 16b series circuit.
17a and PNP transistor 117b are connected as shown.

Further, the inverting amplifier circuit 13 of the noise reduction circuit
0 is the resistors 109, 110, 114 and the variable resistor 11
1, 113, operational amplifier 112 (OA1), NPN
Type transistor 115a, PNP type transistor 115
It is configured as shown in FIG.

That is, in this noise reduction circuit, the signal of the leakage current detected by the leakage current detector 102 for detecting the leakage current is inverted and amplified by the inverting amplifier circuit 110,
NPN type transistor 117a and PNP connected to both ends of the series circuit of the smoothing capacitors 116a and 116b.
The noise current compensation component is supplied to the ground line by the type transistor 117b.

Up to this point, the circuit configuration is equivalent to the above-described conventional configuration having one noise reduction circuit, but in the present embodiment, the inverting amplification circuit section 133 and the noise surrounded by the one-dot chain line in the figure are further added. Another noise reduction circuit composed of a DC power supply unit 134 for supplying a current compensation component is added and configured.

The DC power supply section 134 of the added noise reduction circuit is connected in series with the AC voltage extracted by the capacitors 108a to 108c for forming the neutral point potential of the commercial three-phase AC power supply 101. It is stabilized as a DC voltage via the two smoothing capacitors 127a and 127b.

Furthermore, the smoothing capacitors 127a, 1
NPN type transistor 1 is provided at both ends of the series circuit of 27b.
28a and PNP transistor 128b are connected as shown.

Further, the inverting amplifier circuit section 133 of the added noise reducing circuit is the same as the inverting amplifier circuit 1 of the noise reducing circuit.
The output voltage value from the operational amplifier 112 (OA1) of 30 is input, and the bidirectional constant voltage diode 120 connected to the input section, the resistors 121, 122 and 125, the variable resistor 124, and the operational amplifier 123 (OA2). And NP
N-type transistor 126a, PNP-type transistor 12
6b and 6b, as shown in the figure.

Here, the operation of the inverting amplifier circuits 130 and 133 of each noise reduction circuit is set so as to have different operation regions in accordance with the level of the above leakage current, and further, each noise reduction circuit. Inverting amplifier circuit 130,
The gain of 133 can be set individually.

Next, the operation of the power conversion device according to the present embodiment configured as described above will be described.

In FIG. 1, the output signal of the leak current detector 102 is input to the inverting amplifier circuit 130 of the noise reduction circuit.

Similar to the conventional adjustment method described above, the variable resistor 111 adjusts the gain so that the peak value of the output signal of the operational amplifier 112 (OA1) becomes 10 (V).

Here, by inputting the output signal of the operational amplifier 112 (OA1) to the operational amplifier 123 (OA2) via 5 (V) of the constant voltage diode 120, the operational amplifier 123 (OA2) has a maximum ±±. A 5V signal will be input.

Then, with respect to this input signal, the resistors 121 and 12 that determine the gain of the operational amplifier 123 (OA2).
By selecting the gain by 2 so that a double gain is obtained, the maximum output of the operational amplifier 123 (OA2) is ± 10 (V).

FIG. 2 shows the operational amplifiers 112 and 123 (O
It is a conceptual diagram which shows the operation area | region of A1, OA2).

As shown in FIG. 2, the operational amplifier 123 (O
A2) is a transistor 126a, 126b within ± 5V with respect to the output signal of the operational amplifier 112 (OA1).
The transistor base current is supplied.

Regarding the transistors 115a and 115b, the operational amplifier 112 is used as in the conventional case described above.
The operation is performed with respect to the output signal of (OA1) ± 10V.

That is, the noise compensation total gain of the DC power supply units 131 and 134 in each noise reduction circuit is as follows.

DC power supply 131: operational amplifier 112
Operates with an output signal of (OA1) ± 10 V (gain is set to 1.) DC power supply unit 134 ... Operates with an output signal of ± 5 V of the operational amplifier 112 (OA1) (twice). Within the range, the total gain is tripled.

It should be noted that ± 5 to 10 V is gain 1 as it is.
Is.

Therefore, by setting the operation region as described above, it is possible to obtain a high gain even when the level of the leakage current is relatively low, and therefore, when switching the switching element of the power conversion device. Leakage current can be reduced.

As described above, in the power converter according to this embodiment, a high gain can be obtained even when the leakage current is relatively small, and the leakage current can be surely reduced.

(Second Embodiment) FIG. 3 is a circuit diagram showing an example of the overall configuration of a power conversion device having a noise reduction circuit according to the present embodiment. The same parts as those in FIG. The description thereof will be omitted and only different parts will be described here.

That is, as shown in FIG. 3, the power conversion device according to the present embodiment has the noise reduction circuit of FIG. 1 which performs the inverting amplification circuit operation / leakage current compensation operation with respect to the leakage current. The inverting amplifier circuit of the noise reducing circuit other than the reducing circuit (in this example, the inverting amplifier circuit 13
The variable resistance 301 is connected in series to the constant voltage diode 120 connected to the input section 3).

Next, the operation of the power converter according to the present embodiment configured as described above will be described.

In the first embodiment which requires the provision of a plurality of noise reduction circuits as shown in FIG. 1, the operational region of the operational amplifier 123 (OA2) is fixed.

The power conversion device cannot cope with the change because the level of the leakage current varies depending on external factors such as the installation environment.

Therefore, as in the present embodiment shown in FIG. 3, by connecting the variable resistor 301 in series with the constant voltage diode 120, the operational region of the operational amplifier 123 (OA2) can be varied, and an external configuration is provided. Adjustments can be made according to the environment.

As described above, in the power converter according to the present embodiment, the operating region of the inverting amplifier circuit 133 of the noise reduction circuit can be changed, so that it is possible to carry out the adjustment corresponding to the external environment. Become.

(Third Embodiment) FIG. 4 is a circuit diagram showing an example of the overall configuration of a power conversion device having a noise reduction circuit according to the present embodiment. The same parts as those in FIG. The description thereof will be omitted and only different parts will be described here.

That is, as shown in FIG. 4, the power converter according to this embodiment uses the Hall CT as the leakage current detector 102 for detecting the leakage current in FIG. 1, and uses the main CT of the input power source of the power converter. In the case where the circuit wire cannot be penetrated into the hole CT, auxiliary wires are connected in parallel to the extent that the main circuit wire of the input power source can penetrate into the hole CT, and the hole CT102 is connected to the auxiliary wire. It is made to penetrate.

Next, the operation of the power converter according to the present embodiment configured as described above will be described.

In the first embodiment which requires the provision of a plurality of noise reduction circuits as shown in FIG. 1, the power converter capacity of the power converter is relatively large.

Along with this, the diameter of the electric wire used for the main circuit of the input power source of the power converter also becomes large, and it may be difficult to penetrate the leak current detector 102.

Therefore, as in the present embodiment shown in FIG. 4, the leakage current detector 102 is penetrated by a relatively thin auxiliary wire that bypasses the main circuit portion of the input power source of the power converter as shown by the broken line. As a result, the same leakage current detector as in the above-described conventional configuration can be applied to a power converter having a large power converter capacity.

As described above, in the power converter according to the present embodiment, it is possible to apply the same leakage current detector as the above-mentioned conventional structure to a device having a large power converter capacity.

(Fourth Embodiment) FIG. 5 is a circuit diagram showing an example of the overall configuration of a power conversion device having a noise reduction circuit according to the present embodiment. The same parts as those in FIG. The description thereof will be omitted and only different parts will be described here.

That is, in the power converter according to the present embodiment, as shown in FIG. 5, the DC power supply units 131 and 134, which are power supplies for supplying the noise compensation current in the noise reduction circuits of FIG. 1, are connected in parallel. Connect to DC power supply unit 5
By sharing the same with 01, the two smoothing capacitors 127a of the DC power supply unit 134 of one noise reduction circuit,
127b is omitted.

Next, the operation of the power conversion device according to this embodiment having the above configuration will be described.

In the first embodiment which requires the provision of a plurality of noise reduction circuits as shown in FIG. 1, an increase in the number of parts may pose a problem.

Therefore, as in the present embodiment shown in FIG. 5, DC power supply units 131 and 134, which are power supplies for supplying noise compensation current in each noise reduction circuit, are connected in parallel to each other in the DC power supply unit 501. With the shared configuration, the number of component smoothing capacitors 127a and 127b
Can be reduced.

As described above, in the power converter according to this embodiment, the number of parts can be reduced.

(Fifth Embodiment) FIG. 6 is a circuit diagram showing an example of the overall configuration of a power conversion device having a noise reduction circuit according to the present embodiment. The same parts as those in FIG. The description thereof will be omitted and only different parts will be described here.

That is, the power converter according to the present embodiment, as shown in FIG. 6, corresponds to the noise reduction circuits shown in FIG. 1 and corresponds to the peak hold circuit 60.
8,618 is added.

The peak hold circuits 608 and 618 are the inverting amplifier circuits 130 and 13 in the noise reduction circuits.
Holds the peak value of the output from 3 and outputs it.

The peak hold circuits 608 and 618
Is an operational amplifier 112 of the inverting amplifier circuits 130 and 133,
Comparators 603 and 6 whose outputs from 123 (OA1 and OA2) are input to the non-inverting input terminal and whose output from the connection point of the ground circuit composed of diodes 602 and 612 and capacitors 606 and 616 described later is input to the inverting input terminal.
13, a ground circuit including diodes 602 and 612 and capacitors 606 and 616 connected in series to the output terminals of the comparators 603 and 613, and a resistor 60 connected in parallel to the capacitors 606 and 616 of the ground circuit.
4, 614 and gain adjustment mode switch 605
A comparator in which the output from the comparators 603 and 613 obtained via the diodes 602 and 612 is used as the input of the non-inverting input terminal and the output of the book itself is used as the input of the inverting input terminal. 601 and 611 and the comparators 601 and 61
1 is connected to the output terminal of the inverting amplifier circuit 130, 13
3 of the operational amplifiers 112 and 123 (OA1 and OA2), and check pins 607 and 617 to which a voltage holding the maximum value of the output signal is output.

Here, to the check pins 607 and 617, an analog voltmeter or a digital voltmeter, which is a voltage measuring means for measuring the voltage output from the peak hold circuits 608 and 618, can be appropriately connected.

Next, the operation of the power converter according to the present embodiment having the above-described structure will be described.

In FIG. 6, the output signal of the leak current detector 102 is input to the inverting amplifier circuits 130 and 133, and the peak value of the output is held by the peak hold circuits 608 and 618.

The voltage of the peak hold circuits 608 and 618 is read by an analog voltmeter or a digital voltmeter connected to the check pins 607 and 617.

Then, while the hold voltage is read by the analog voltmeter or the digital voltmeter, the gains are manually adjusted by the variable resistors 111 and 610.

When the gain adjustment is completed, the gain adjustment mode switches 605 and 615 (RST1 and RST2) of the peak hold circuits 608 and 618 are manually closed to operate the peak hold circuits 608 and 618.
After resetting the hold voltage of, the peak voltage is 10V
Repeat the measurement until

By repeating the above operation,
Even when a plurality of noise reduction circuits are provided, an appropriate gain adjustment of the noise reduction circuit can be performed in a short time using only an analog voltmeter or a digital voltmeter.

That is, when the peak hold circuits 608 and 618 shown in this embodiment are not provided, the output voltage waveform of the operational amplifier of each noise reduction circuit is confirmed by an oscilloscope or the like, and the output signal Since the method is such that the variable resistors 111 and 610 are respectively adjusted after confirming the maximum value, it is understood that by applying the present embodiment, the gain adjustment time can be significantly shortened.

As described above, in the power converter according to the present embodiment, even when a plurality of noise reduction circuits are provided, the gain of the noise reduction circuit can be easily adjusted.

The peak hold circuits 608 and 618 are also provided.
The hold voltage of can be confirmed with an analog voltmeter or a digital voltmeter, and even when multiple noise reduction circuits are provided, the gain of the noise reduction circuit can be adjusted only with the analog voltmeter or digital voltmeter. It becomes possible.

Furthermore, the peak hold circuits 608 and 61
By resetting the hold voltage of 8, the adjustment operation can be repeated.

(Sixth Embodiment) FIG. 7 is a circuit diagram showing an example of the overall configuration of a power conversion device having a noise reduction circuit according to the present embodiment. The same parts as those in FIG. The description thereof will be omitted and only different parts will be described here.

That is, in the power converter according to this embodiment, as shown in FIG. 7, the electronic volume 707 (701, 702, 703) is used as a variable resistor for adjusting the gain of the inverting amplifier circuits 130, 133 in FIG. , 70
4) is used, and the check pins 607 and 617 and the analog voltmeter or the digital voltmeter connected to the check pins 607 and 617 are omitted, and instead of these, the A / D converter 7
05 and a microcomputer 706.

The A / D converter 705 converts the output voltage output from each of the peak hold circuits 608 and 618 into a digital signal and outputs it.

The microcomputer 706 calculates and outputs a gain based on the output from the A / D converter 705.

Then, according to the output from the microcomputer 706, the electronic volume 707 (701, 702, 70
No. 3,704) and the adjustment mode switches 605, 615 (RST1, RST) for each gain.
The opening and closing of 2) is operated.

Next, the operation of the power converter according to the present embodiment having the above structure will be described.

In FIG. 7, the automatic adjustment mode is set,
The output signal from the leakage current detector 102 is an inverting amplifier circuit 1
The peak value of the output is input to the peak hold circuits 608 and 618, and is input to the input terminals 30 and 133.

The voltages of the peak hold circuits 608 and 618 are converted into digital signals by the A / D converter 705.

The digital signal from the A / D converter 705 is read by the microcomputer 706, the gain is calculated, and any appropriate resistance value is set to the electronic volume 707 (701, 70).
By outputting to 3), the resistance value is adjusted and the gain is automatically adjusted.

When the gain adjustment is completed, the gain adjustment mode switches 605 and 615 of the peak hold circuits 608 and 618 are also automatically closed by the output of the microcomputer 706, whereby the peak hold circuit 60 is closed.
After resetting the hold voltage of 8,618, measurement is performed again.

By automatically repeating the above operation, even when a plurality of noise reduction circuits are provided, it is possible to automatically perform an appropriate gain adjustment of the noise reduction circuit in a short time.

That is, when the peak hold circuits 608 and 618 shown in this embodiment are not provided, the output voltage waveform of the operational amplifier of each noise reduction circuit is confirmed by an oscilloscope or the like, and the output signal Since the method is such that the variable resistors 111 and 610 are respectively adjusted after confirming the maximum value, it is understood that by applying the present embodiment, the gain adjustment time can be significantly shortened.

As described above, in the power converter according to the present embodiment, even when a plurality of noise reducing circuits are provided, it is possible to easily and automatically adjust the gain of the noise reducing circuit. .

The peak hold circuits 608 and 618 are also provided.
By automatically resetting the hold voltage of, the adjustment operation can be automatically repeated.

(Other Embodiments) The present invention is not limited to the above-described embodiments, and can be variously modified and implemented at the stage of implementation without departing from the spirit thereof. Is. In addition, the respective embodiments may be implemented in combination as appropriate as possible, and in that case, combined operation effects can be obtained. Further, the above-described embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent features. For example, even if some constituent elements are deleted from all the constituent elements shown in the embodiment, the problem (at least one) described in the section of the problem to be solved by the invention can be solved, and When the effect (at least one) described in the section can be obtained, a structure in which this constituent element is deleted can be extracted as an invention.

[0124]

As described above, according to the power converter of the present invention, the leakage current is detected from the power source line of the AC power source, the leakage current is input to the amplifier circuit, and the gain is adjusted by the resistor to reduce the noise. A plurality of noise reduction circuits that flow a noise compensation current to the ground line of the power converter to obtain a compensation current and cancel the leakage current are provided, and the operation of the amplification circuit of each noise reduction circuit is made to correspond to the level of the leakage current. Since the operating regions are set to be different from each other, a high gain can be obtained even when the leakage current is relatively small, and the leakage current can be surely reduced.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram showing a first embodiment of a power conversion device including a noise reduction circuit according to the present invention.

FIG. 2 is a conceptual diagram for explaining the operation of the noise reduction circuit in the power conversion device according to the first embodiment.

FIG. 3 is a circuit configuration diagram showing a second embodiment of a power conversion device including a noise reduction circuit according to the present invention.

FIG. 4 is a circuit configuration diagram showing a third embodiment of a power conversion device including a noise reduction circuit according to the present invention.

FIG. 5 is a circuit configuration diagram showing a fourth embodiment of a power conversion device including a noise reduction circuit according to the present invention.

FIG. 6 is a circuit configuration diagram showing a fifth embodiment of a power conversion device including a noise reduction circuit according to the present invention.

FIG. 7 is a circuit configuration diagram showing a sixth embodiment of a power conversion device including a noise reduction circuit according to the present invention.

FIG. 8 is a circuit diagram showing a configuration example of a power conversion device including a conventional noise reduction circuit.

[Explanation of symbols]

101 ... Commercial three-phase AC power supply, 102 ... Leakage current detector, 103a-103c ... Reactor, 104, 106 ... Switching element, 105 ... Smoothing capacitor, 107 ... Electric motor, 108a-108c, 116a, 116b, 127a,
127b, 606, 616 ... Capacitor, 109, 110, 114, 121, 122, 125, 6
04,614 ... Resistors, 111, 113, 124, 301 ... Variable resistors, 112, 123, 601, 603, 611, 613 ... Operational amplifiers, 115a, 117a, 126a, 128a ... NPN type transistors, 115b, 117b, 126b, 128b ... PNP type transistor, 120 ... Bidirectional constant voltage diode, 135 ... Ground, 130, 133 ... Inversion amplification circuit of noise reduction circuit, 131, 134, 501 ... DC power supply section of noise reduction circuit, 602, 612 ... Diode, 601 , 603, 611, 613 ... Comparator, 605, 615 ... Gain adjustment mode switch, 607, 617 ... Check pin, 608, 618 ... Peak hold circuit, 707 (701, 702, 703, 704) ... Electronic volume, 705 ... A / D converter, 706 ... Microcomputer.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5H007 AA01 AA07 AA08 AA12 BB06                       CA01 CB04 CB05 CC23 DA00                       DA05 DB01 DC02                 5H576 AA07 BB05 BB10 CC05 DD02                       EE04 GG07 GG08 HB02 JJ03                       JJ16 KK06 LL22

Claims (9)

[Claims] 1. A leak current is detected from a power supply line of the AC power supply by converting the AC power from the AC power supply into AC power having an arbitrary frequency and supplying the AC power to a motor to drive at a variable speed. Then, the leakage current is input to the amplifier circuit, the gain is adjusted by a resistor to obtain a noise compensation current, and a noise reduction circuit that causes the noise compensation current to flow to the earth line of the power conversion device main body so as to cancel the leakage current is provided. In the power conversion device configured as described above, a plurality of the noise reduction circuits are provided, and the operation of the amplification circuit of each of the noise reduction circuits is set so as to have a difference in operation region depending on the level of the leakage current. A power conversion device comprising: 2. The power conversion device according to claim 1, wherein among the noise reduction circuits, a noise reduction circuit other than a noise reduction circuit that performs an amplification circuit operation / leakage current compensation operation for the leakage current. A power conversion device comprising a series circuit including a constant voltage diode and a variable resistor connected to an input section of an amplifier circuit. 3. The power converter according to claim 1, wherein Hall CT is used as means for detecting the leakage current,
The main circuit wire of the input power source of the power converter is connected to the hole C.
When it is not possible to penetrate T, an auxiliary electric wire that allows the main circuit electric wire of the input power source to penetrate the hole CT is connected in parallel, and the auxiliary electric wire penetrates the hole CT. An electric power conversion device characterized by comprising: 4. The power conversion device according to claim 1, wherein DC power supplies serving as power supplies for supplying noise compensation currents in the noise reduction circuits are connected in parallel and shared. Power converter. 5. The power converter according to claim 1, wherein a peak hold means for holding and outputting a peak value of an output from the amplifier circuit is provided as a means for adjusting a gain of the amplifier circuit in each of the noise reduction circuits. A power conversion device comprising the respective noise reduction circuits. 6. The power converter according to claim 5, further comprising voltage measuring means for measuring the voltage output from the peak hold means. 7. The power converter according to claim 5 or 6, further comprising gain adjustment mode switch means for resetting a hold voltage in the peak hold means. . 8. The power converter according to claim 1, wherein an electronic volume is used as a resistor for adjusting a gain of the amplifier circuit, and an output voltage output from the peak hold means is converted into a digital signal. A / D conversion means for outputting, a microcomputer for calculating and outputting gain based on the output from the A / D conversion means, and means for adjusting the resistance value of the electronic volume based on the output from the microcomputer And a power conversion device characterized by being added. 9. The power converter according to claim 8, further comprising a gain adjustment mode switch means for resetting a hold voltage in the peak hold means, and based on an output from the microcomputer, A power converter characterized in that the resistance value is automatically adjusted and the gain adjustment mode switch means is automatically opened and closed.