JP3906680B2 - Noise reduction device and power conversion device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a noise reduction device and a power conversion device.
[0002]
[Prior art]
A power converter such as an inverter that supplies electric power to a motor or a switching regulator that supplies voltage to a computer converts electric power supplied from a predetermined power source into electric power of a predetermined voltage and supplies the electric power to a load.
[0003]
In such a power conversion device, power conversion is performed by turning on and off the switching element, so that switching noise is generated due to switching of the switching element. Since the frequency of this switching noise is very high, a noise filter having a wide band and a large attenuation characteristic is required. Further, in the circuit, there is a capacitance including a stray capacitance between the ground, and noise due to switching of the switching element flows as a high-frequency leakage current to the ground line via this capacitance. When this leakage current flows through the ground line, the voltage level of the frame (housing) of the power converter varies.
[0004]
In particular, when a motor having a large power capacity is connected to the power converter via the inverter, the stray capacity between the ground and the leakage current increases accordingly. When this leakage current is large, the earth leakage breaker is interrupted or the surrounding electronic devices are disturbed.
[0005]
In order to reduce such noise, there is a noise reduction device for a power converter that reduces noise by supplying a compensation current to a ground line in a direction that cancels out leakage current. (Refer to Unexamined-Japanese-Patent No. 9-266677 etc.).
[0006]
The configuration of such a conventional power converter is shown in FIG.
The conventional power conversion device includes a noise filter unit 51, a rectifying / smoothing circuit unit 52, a power conversion circuit unit 53, a leakage current detector 54, and an amplifier circuit 55.
[0007]
The noise filter unit 51 is connected to prevent switching noise generated by switching of the switching element provided in the power conversion circuit unit 53 from flowing out to the AC power supply 56 side, and the capacitors C61 and C62. , 63 and a choke coil L61.
[0008]
The capacitor C61 is an across-the-line capacitor that attenuates normal mode noise propagating between each pair of AC power supply lines, and the capacitors C62 and C63 propagate between the AC power supply line and the ground line. This is a capacitor for reducing common mode noise.
The choke coil L61 is a common mode choke coil that attenuates common mode noise.
[0009]
The rectifying / smoothing circuit unit 52 includes a bridge rectifier circuit including four diodes D61 to D64 and a capacitor C64.
The power conversion circuit unit 53 includes an inverter, a switching regulator, and the like, converts DC power into predetermined DC power, and supplies the DC voltage to a load R60 such as a motor.
[0010]
The leakage current detector 54 is constituted by a zero-phase current transformer, and detects a leakage current flowing through the power supply line as a current difference.
The amplifier circuit 55 includes an NPN transistor Q61, a PNP transistor Q62, and diodes D65 and D66, and amplifies the difference in current detected by the leakage current detector 54.
[0011]
In such a power converter, the load R60 such as a motor has a capacitance, and the leakage current leaked from the load R60 flows to the ground line through the capacitance of the load R60. This leakage current returns to the load R60 via the AC power source 56, the noise filter unit 51, the leakage current detector 54, and the power conversion circuit unit 53.
[0012]
The leakage current detector 54 detects this leakage current as a difference in current flowing in the power supply line, and the amplifier circuit 55 amplifies the difference in current and compensates the leakage current with a capacitor C65. To the ground line. Thereby, noise is reduced.
[0013]
[Problems to be solved by the invention]
However, in such a power converter, the leakage current via the AC power supply 56 is directly detected to cancel the leakage current. In this case, since a large leakage current due to common mode noise flows through the capacitor C65 to the ground line, the difference in current flowing through the power supply line must be amplified with a high amplification factor. In particular, the greater the capacitance of the load R60, the greater the leakage current that flows to the ground line via the capacitor C65.
[0014]
However, when the amplification factor of the amplifier circuit 55 is increased, there is a problem that oscillation is likely to occur and the operation becomes unstable unless the phase compensation is accurately performed.
[0015]
The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a noise reduction device and a power conversion device that can stably perform noise reduction.
[0016]
[Means for Solving the Problems]
  In order to achieve this object, a noise reduction device according to the first aspect of the present invention provides:
  Provided between an AC power source and a power converter that converts AC power supplied from the AC power source into predetermined AC power or DC power and supplies the load to the load, and leaks from the power converter and the load to the ground line Supply current to the ground line in a direction to cancel the leakage current, in the power converterA noise reduction device for reducing noise,
  In order to detect a current corresponding to the leakage current, AC power supplied from the AC power supply is inserted into a pair of power supply lines that supply the power converter, and a zero-phase current of the pair of power supply lines is detected as a detection ratio. 1Leakage current detection means for detecting;
  Power supply means for inputting an alternating current power supply voltage on the alternating current power supply side from the leakage current detection means, rectifying and smoothing, and outputting a predetermined direct current voltage;
  A direction in which the DC voltage supplied from the power supply means is used as a power source, and the current corresponding to the leakage current detected by the leakage current detection means is amplified with an amplification factor of 1 to cancel the leakage current to the ground line. And amplifying means for supplying toIt is a thing.
[0022]
The amplification means includes
An NPN transistor, a PNP transistor, a capacitor,
With
The collector of the NPN transistor is connected to the positive side of the power supply means, the emitter of the PNP transistor is connected to the emitter of the NPN transistor, and the collector of the PNP transistor is connected to the negative side of the power supply means. The one output terminal of the leakage current detecting means is connected to the base of the NPN transistor and the base of the PNP transistor, and the other output terminal of the leakage current detecting means is the emitter of the NPN transistor and the emitter of the PNP transistor. Connected to
The capacitor may be configured to be connected between the ground line and a base of the NPN transistor and a base of the PNP transistor.
[0023]
The leakage current detection means has two output windings,
The amplification means includes
Two NPN transistors, a capacitor,
With
The collector of the one NPN transistor is connected to the positive side of the power supply means, and the base and emitter of the one NPN transistor are respectively connected to both ends of one output winding of the leakage current detection means. The collector of the other NPN transistor is connected to the base of the one NPN transistor, and the base and emitter of the other NPN transistor are respectively connected to the other output winding of the leakage current detecting means. Connected to both ends, the base of the other NPN transistor is connected to the negative side of the power supply means,
The capacitor may be configured to be connected between the ground line and a base of the one NPN transistor.
[0024]
The leakage current detection means has two output windings,
The amplification means includes
A PNP transistor, an NPN transistor, a capacitor,
With
The base of the PNP transistor is connected to the positive electrode side of the power supply means, the collector of the NPN transistor is connected to the collector of the PNP transistor, and the base and emitter of the PNP transistor are each configured to detect the leakage current. Connected to both ends of one output winding of the means, and the base and emitter of the NPN transistor are respectively connected to both ends of the other output winding of the leakage current detecting means, and the base of the NPN transistor is Connected to the negative electrode side of the power supply means,
The capacitor may be configured to be connected between the ground line and a collector of the NPN transistor.
[0025]
The leakage current detection means has two output windings,
The amplification means includes
Two PNP transistors, a capacitor,
With
The base of the one PNP transistor is connected to the positive side of the power supply means, and the base and the emitter are respectively connected to both ends of one output winding of the leakage current detection means, and the other The base of the PNP transistor is connected to the collector of the one PNP transistor, the base and the emitter are respectively connected to both ends of the other output winding of the leakage current detecting means, and the collector is connected to the power Connected to the negative side of the supply means,
The capacitor may be configured to be connected between the ground line and a base of the other PNP transistor.
[0026]
  In the amplification means, the NPN transistor may be replaced with an N-type field effect transistor, and the PNP transistor may be replaced with a P-type field effect transistor.
[0030]
  A power conversion device according to a second aspect of the present invention provides:
  In the power converter which converts the alternating current power supplied from alternating current power supply into predetermined alternating current power or direct current power, and supplies it to a load, the noise reduction device according to claim 1 was provided in the input sideIs.
[0031]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a power converter according to an embodiment of the present invention will be described with reference to the drawings.
The configuration of the power conversion apparatus according to this embodiment is shown in FIG.
The power conversion device includes a noise filter unit 1, a rectifying and smoothing circuit unit 2, a power conversion circuit unit 3, and a noise reduction circuit unit 4.
[0032]
The noise filter unit 1 includes capacitors C1, C2, and C7 and a choke coil L1.
Capacitors C <b> 1 and C <b> 2 are across-the-line capacitors that attenuate normal mode noise, and are connected between a pair of power lines E <b> 1 and E <b> 2 of the AC power supply 5.
The capacitor C7 is a capacitor for reducing common mode noise, and is connected between the line E2 and the ground line.
[0033]
The choke coil L1 is a common mode choke coil that attenuates common mode noise, and is connected in series to the lines E1 and E2 of the AC power supply 5 with the same winding direction.
[0034]
The rectifying / smoothing circuit unit 2 includes a rectifying circuit 11 and a capacitor C3.
The rectifier circuit 11 rectifies the AC voltage supplied from the AC power supply 5, and is connected to the line E1 and the line E2. The rectifier circuit 11 is constituted by, for example, a bridge rectifier circuit including four diodes.
[0035]
The capacitor C <b> 3 is a capacitor for smoothing the pulsating flow of the rectified voltage output from the rectifier circuit 11, and is connected to the output terminal of the rectifier circuit 11.
[0036]
The power conversion circuit unit 3 converts predetermined DC power into DC power of a predetermined voltage and supplies the DC voltage to the load R0. The transformer T, the switching element Q1, the diodes D1 and D2, the choke The coil L2 and the capacitor C4 are provided to constitute a forward converter.
[0037]
The transformer T is for transmitting primary power to the secondary side, and includes a primary winding n1 and a secondary winding n2. The primary winding n1 is a winding for generating a voltage by a switching current and generating excitation energy in the transformer T. The secondary winding n2 is a voltage with the excitation energy generated by the primary winding n1. It is a winding for generating. One end Pt11 of the primary winding n1 is connected to the positive (+) terminal of the capacitor C3.
[0038]
The switching element Q1 is an element that is supplied with the signal S1, switches the current flowing through the primary winding n1 of the transformer T, and induces a voltage in the primary winding n1 of the transformer T. The other end Pt12 of the next winding n1 is connected between the negative electrode (−) side terminal of the capacitor C3. A control unit (not shown) supplies a pulse signal S1 to the switching element Q1 and performs PWM control based on fixed oscillation to stabilize the output voltage.
[0039]
The diode D1 is a diode for rectifying current from the voltage generated in the secondary winding n2 during the ON period of the switching element Q1, and its anode is connected to one end Pt21 of the secondary winding n2.
[0040]
The diode D2 is a diode for circulating the current flowing according to the excitation energy accumulated in the choke coil L2 during the ON period of the switching element Q1 to the positive (+) side of the capacitor C4 during the OFF period, and its anode is a secondary winding. It is connected to the other end Pt22 of the line n2, and its cathode is connected to the cathode of the diode D1.
[0041]
The choke coil L2 is for smoothing the current flowing to the capacitor C4, and is connected between the cathodes of the diodes D1 and D2 and the positive electrode (+) side terminal of the capacitor C4.
[0042]
The capacitor C4 is for smoothing the current that has passed through the choke coil L2 to generate a DC voltage, and is connected in parallel with the diode D2 via the choke coil L2. The choke coil L2 and the capacitor C4 constitute a low frequency LC filter. The power conversion circuit unit 3 supplies the generated DC voltage to the load R0.
The capacitance C5 indicates a stray capacitance that exists between the negative electrode (−) line of the DC voltage and the ground line.
[0043]
The noise reduction circuit unit 4 is a circuit unit for reducing noise, and includes a zero-phase current transformer 21, an amplifier circuit 22, and a constant voltage circuit 23.
[0044]
The zero-phase current transformer 21 corresponds to leakage current detection means for detecting leakage current, and an equivalent circuit thereof is as shown in FIG. A primary winding n11 shown in FIG. 2A represents a pair of power supply lines, that is, windings of lines E1 and E2. In the present embodiment, the turn ratio between the primary winding n11 and the secondary winding n12 is set to 1.
[0045]
The terminals P3 and P4 of the secondary winding of the zero-phase current transformer 21 are connected to the base and emitter of the transistors Q11 and Q12, respectively.
[0046]
When a leakage current flows through the lines E1 and E2, a difference in current occurs between the lines E1 and E2. The zero-phase current transformer 21 detects a leakage current by detecting the difference between the currents.
[0047]
The reason why a current difference occurs between the lines E1 and E2 due to the leakage current is as follows. If no noise is generated and there is no stray capacitance, currents having the same current value and opposite directions flow through the lines E1 and E2, respectively. When noise is generated, the noise is superimposed on a line connected to the noise generation source and propagates to each line. Further, if there is a stray capacitance, the stray capacitance also varies depending on the position. Due to this noise propagation and stray capacitance variation, current imbalance occurs between the lines. Also, if there are capacitors C2 and C7, a leakage current flows to the ground line via the capacitors C2 and C7, and current imbalance between the lines appears as a difference in current flowing through the lines E1 and E2. come.
[0048]
The zero-phase current transformer 21 is formed by connecting lines E1 and E2 to a through-type current transformer 21b shown in FIG. 2 (b) having a magnetic core 21a and a secondary winding n12 as shown in FIG. 2 (c). It is configured by winding around a core 21a.
[0049]
The primary winding n11 of the zero-phase current transformer 21 has a primary current I as a difference between currents flowing through the lines E1 and E2.₁Flows in the secondary winding n12 and the primary current I₁Based on the current I₂Is induced. The winding direction of the secondary winding n12 depends on the induced current I₂Is set to flow in the ground line in a direction to cancel the leakage current.
[0050]
The amplifier circuit 22 includes an induced current I generated in the secondary winding n12 of the zero-phase current transformer 21.₂And includes transistors Q11 and Q12 and a capacitor C6. In this embodiment, in order to make the current value of the compensation current equal to the current value of the leakage current, the amplifier circuit 22 is configured so that the amplification factor is 1. The reason will be described later.
[0051]
The transistor Q11 is an NPN-type bipolar transistor, and its collector is connected to the positive electrode of the constant voltage circuit 23.
The transistor Q12 is a PNP-type bipolar transistor, the emitter of which is connected to the emitter of the transistor Q11, and the collector of which is connected to the negative electrode (E2 line) of the constant voltage circuit 23.
The capacitor C6 is a capacitor for supplying a compensation current to the ground line.
[0052]
The constant voltage circuit 23 is a DC power supply circuit that supplies a constant voltage to the amplifier circuit 22, and includes a diode D3, capacitors C8 and C9, a Zener diode Dz, and resistors R1 and R2.
[0053]
The diode D3 is for rectifying the AC voltage supplied from the AC power source 5, and the anode thereof is connected to the line E1.
The resistors R1 and R2 are current limiting resistors and are connected in series to the cathode of the diode D3.
[0054]
Capacitors C8 and C9 are smoothing capacitors. The capacitor C8 is connected between the connection point of the resistors R1 and R2 and the line E2. The capacitor C9 is connected between the resistor R2 and the line E2.
[0055]
The Zener diode Dz is a diode for generating a DC constant voltage by clamping the voltage smoothed by the capacitor C9 with the Zener voltage, and is connected to both ends of the capacitor C9.
[0056]
Next, the operation of the power conversion device according to the present embodiment will be described.
A signal S1 as shown in FIG. 3A is supplied to the switching element Q1. When the signal S1 becomes high level, the switching element Q1 is turned on, and when the signal S1 becomes low level, the switching element Q1 is turned off. Time t0 to t1 is an on period of the switching element Q1, and time t1 to t2 is an off period of the switching element Q1.
[0057]
In the ON period of the switching element Q1, as shown in FIG. 3B, the voltage Vq1 applied to the switching element Q1 is substantially zero, and the switching element Q1 has a current Iq1 as shown in FIG. Flows.
[0058]
In addition, during the OFF period of the switching element Q1, the voltage Vq1 applied to the switching element Q1 is higher than the charging voltage of the capacitor C3 as shown in FIG. 3B, and the current Iq1 flowing through the switching element Q1 is As shown in FIG. 3C, it becomes almost zero.
[0059]
When the switching element Q1 is turned on / off, the current flowing in the primary winding n1 of the transformer T is switched, and a voltage is generated in the primary winding n1 of the transformer T. Voltage is generated.
[0060]
The diode D1 rectifies the current flowing in accordance with the voltage generated in the secondary winding n2 during the ON period of the switching element Q1, and the diode D2 converts the current flowing through the choke coil L2 during the OFF period of the switching element Q1 Return to the (+) side. The current flowing through the diodes D1 and D2 is smoothed by the choke coil L2 and the capacitor C4 to generate a DC voltage, and the power conversion circuit unit 3 supplies the generated DC voltage to the load R0.
[0061]
When the switching element Q1 is switched, a leakage current Is as shown in FIG. 3D flows to the ground line via the capacitor C7 between the grounds in the circuit of the power conversion device.
The zero-phase current transformer 21 detects the leakage current Is as a difference between currents generated between the lines E1 and E2. The noise reduction circuit unit 4 amplifies the difference in current detected by the zero-phase current transformer 21 and supplies a compensation current Ir as shown in FIG. 3E to the ground line. Thereby, the leakage current Is becomes small as shown in FIG.
[0062]
Next, the principle of canceling out this leakage current will be described with reference to FIG.
In FIG. 4, capacitors C51 and C52 respectively correspond to the capacitance of the load R0 and the capacitor C7 for common mode noise. Further, the diode D51 and the switch SW correspond to the rectifier circuit 11 and the switching element Q1 in FIG. 1, respectively. Leakage currents Is1 and Is2 indicate a leakage current that flows from the AC power supply 5 due to switching of the switch SW, and a leakage current that propagates in the power converter.
[0063]
This leakage current Is1 is canceled by the compensation current Ir. Two methods are conceivable as the method.
In the first method, as shown in FIG. 4, the zero-phase current transformer 21 is arranged at the point a (the AC power supply 5 side from the injection point b of the compensation current Ir), and the leakage current Is1 is detected at the point a. The detected current is amplified by the amplifier AMP, and the amplified compensation current Ir is supplied to the ground line via the capacitor C52 in a direction to cancel the leakage current Is1.
[0064]
In the second method, the zero-phase current transformer 21 is arranged at the detection point c (the power conversion circuit unit 3 side of the injection point b of the compensation current Ir), the leakage current Is2 is detected at the point c, and the detection current is detected. In this way, the compensation current Ir is supplied to the ground line in the same manner as the first method.
[0065]
The conventional power converter shown in FIG. 17 uses the first method.
In the first method, the following relational expression is established.
A1 × (is1−ir) −is1≈0
A1: amplification factor of the amplifier circuit AMP when the first method is used
is1: Current value of leakage current Is1
ir: current value of the compensation current Ir
Therefore,
ir = (1-1 / A1) * is1
[0066]
As shown by this equation, in order to cancel the leakage current Is1 with the compensation current Ir, the amplification factor A1 of the amplifier circuit AMP must be increased. However, as described above, when the amplification factor A1 is large, there arises a disadvantage that the amplifier circuit AMP easily oscillates.
[0067]
On the other hand, when the second method is used, the following relational expression is established.
is1-A2 * ir = 0
A2: amplification factor of the amplifier circuit AMP when the second method is used
Therefore,
ir = A2 × is2
[0068]
As shown by this equation, in order to cancel the leakage current Is1 with the compensation current Ir, the amplification factor A2 of the amplifier circuit AMP has only to be set to 1, and the conventional inconvenience does not occur. In the present embodiment, the latter method is used. This is the reason why the amplification factor of the amplifier circuit 22 is 1.
[0069]
However, in the case of the latter method, it is necessary to configure the amplifier circuit 22 so that the amplification factor is exactly 1.
If the amplifier circuit 22 is configured using an operational amplifier or the like, the configuration of the amplifier circuit 22 becomes complicated.
Therefore, in the present embodiment, as shown in FIG. 1, the amplifier circuit 22 is configured to have an amplification factor of 1 with a simple configuration.
[0070]
The principle of the amplifier circuit 22 will be described with reference to FIG. 5A is a principle diagram when the transistor Q11 which is an NPN bipolar transistor is used, and FIG. 5B is a principle diagram when an FET (field effect transistor) is used as the transistor. It is the same.
[0071]
However, when an FET is used, since the gate current of the FET can be regarded as almost 0, the amplification factor is exactly 1, there is no unstable element such as oscillation, and the effect can be expected up to a high frequency range.
[0072]
Here, the principle will be described with reference to FIG.
A primary current I of the zero-phase current transformer 21 as shown in FIG. 5A is applied to the primary winding n11 of the zero-phase current transformer 21.₁Flows in the secondary winding n12, the induced current I₂Flows.
[0073]
Primary current I₁Current value i₁Is i, since the turns ratio of the primary winding n11 and the secondary winding n12 of the zero-phase current transformer 21 is 1, the induced current I₂Current value i₂Is also i. This induced current I₂Is shunted and the base current I is applied to the base of the transistor Q11._ThreeFlows and the current I flows through the load R11._FourFlows. Induced current I₂Causes the potential of the emitter of the transistor Q11 to rise. The base current I_ThreeFlows to the base, the potential of the base of the transistor Q11 also rises. When the amplification factor of the transistor Q11 is Hfe, the current I_ThreeCurrent value i_ThreeBecomes i / Hfe.
[0074]
Therefore, the current I_FourCurrent value i_FourBecomes (i-i / Hfe). If the amplification factor Hfe of the transistor Q11 is sufficiently larger than 1, the amplification factor of the amplification circuit 22 is 1.
This current value i_FourCurrent I_FourIs supplied to the ground line in a direction opposite to the leakage current Is, the leakage current Is is the current I_FourIs offset by
[0075]
By combining this principle with the circuit of the transistor Q12, the circuit of the transistor Q11 shown in FIG. 5A operates in the positive half cycle, and the circuit of the transistor Q12 operates in the negative half cycle. Both transistors Q11 and Q12 can be operated by a pair of primary winding n11 and secondary winding n12.
[0076]
Next, this operation will be described with reference to FIG.
Induced current I of the zero-phase current transformer 21₂Flows in the direction shown in FIG. 6A, as shown by the broken line in FIG. 6B, the induced current I₂Flows into the base of the transistor Q11, and the transistor Q11 is turned on. When the transistor Q11 is turned on, as indicated by the solid line in FIG. 6B, a current Iq11 sequentially passes from the constant voltage circuit 23 through the transistor Q11, the secondary winding n12 of the zero-phase current transformer 21, and the capacitor C6. Then, it flows out to the output terminal Pout1, and returns to the constant voltage circuit 23 from the output terminal Pout2.
[0077]
Induced current I of the zero-phase current transformer 21₂However, when flowing in the direction opposite to the direction shown in FIG. 6A, as shown by the broken line in FIG.₂Flows into the base of the transistor Q12, and the transistor Q12 is turned on. When the transistor Q12 is turned on, as indicated by the solid line in FIG. 6C, the current Iq12 sequentially passes from the capacitor C6 to the output terminal Pout2 through the secondary winding n12 of the zero-phase current transformer 21 and the transistor Q12. It flows out and returns to the capacitor C6 from the output terminal Pout1.
[0078]
This timing is shown in the timing chart of FIG.
Primary current I of the zero-phase current transformer 21₁Flows as shown in FIG. 7 (a), and the induced current I₂Is assumed to flow as shown in FIG. Note that the current flowing so that the current flows out from the output terminal Pout1 is positive.
[0079]
Assuming that the transistor Q11 is turned on and the transistor Q12 is turned off at times t11 to t12, a current Iq11 as shown in FIG. 7C flows through the transistor Q11, and the current Iq12 of the transistor Q12 is as shown in FIG. It becomes 0 as shown in d).
[0080]
Assuming that the transistor Q11 is turned off and the transistor Q12 is turned on at time t12 to t13, the current Iq11 of the transistor Q11 becomes 0 as shown in FIG. 7C, and the transistor Q12 has the current shown in FIG. A current Iq12 as shown flows.
[0081]
A current obtained by combining the currents Iq11 and Iq12 becomes a compensation current Ir as shown in FIG. If this compensation current Ir is supplied to the ground line, the leakage current Is is canceled by the compensation current Ir.
[0082]
As described above, according to the present embodiment, the zero-phase current transformer 21 is disposed closer to the power conversion circuit unit 3 than the injection point of the compensation current Ir to detect a leakage current that propagates in the power conversion device. The compensation current is supplied to the ground line based on the leakage current.
[0083]
Therefore, the gain of the amplifier circuit 22 can be reduced, and noise reduction can be performed stably. Further, by setting the gain to 1, the high frequency characteristics are improved, and noise can be reduced to the high frequency region.
[0084]
The amplifier circuit 22 can also be configured with a simple circuit. Moreover, since a leakage current can be reduced efficiently, the large noise filter part 1 is not required and the whole power converter device can be reduced in size.
[0085]
In carrying out the present invention, various forms are conceivable and the present invention is not limited to the above embodiment.
For example, even if the turn ratio of the zero-phase current transformer 21 and the amplification factor of the amplifier circuit 22 are not set to 1, respectively, the current value of the compensation current may be set appropriately so as to be equal to the current value of the leakage current. it can.
[0086]
Moreover, it can also be set as the current sensor using a Hall element instead of the zero phase current transformer 21.
[0087]
The configurations of the zero-phase current transformer 21 and the amplifier circuit 22 are not limited to those described above. As shown in FIG. 8, the amplifier circuit 22 includes NPN-type bipolar transistors Q13 and Q14, and zero Two secondary windings of the phase current transformer 21 may be provided to supply current to the transistors Q13 and Q14, respectively.
[0088]
Further, as shown in FIG. 9, the amplifier circuit 22 includes a PNP-type bipolar transistor Q15 and an NPN-type bipolar transistor Q16, and two secondary windings of the zero-phase current transformer 21 are provided. A current may be supplied to the transistors Q15 and Q16.
[0089]
Further, as shown in FIG. 10, the amplifier circuit 22 includes PNP-type bipolar transistors Q17 and Q18, and two secondary windings of the zero-phase current transformer 21 are provided so that current is supplied to the transistors Q17 and Q18. You may make it supply.
[0090]
In addition, as shown in FIG. 11, the amplifier circuit 22 includes an N-type FET 11 and a P-type FET 12, and two secondary windings of the zero-phase current transformer 21 are provided, and current is supplied to the FET 11 and the FET 12, respectively. May be supplied.
[0091]
As shown in FIG. 12, the amplifier circuit 22 includes two N-type FETs 13 and 14, and two secondary windings of the zero-phase current transformer 21 are provided to supply current to the FETs 13 and 14. It may be.
[0092]
As shown in FIG. 13, the amplifier circuit 22 includes a P-type FET 15 and an N-type FET 16, and two secondary windings of the zero-phase current transformer 21 are provided to supply current to the FET 15 and the FET 16. You may make it do.
[0093]
As shown in FIG. 14, the amplifier circuit 22 includes P-type FETs 17 and 18, and two secondary windings of the zero-phase current transformer 21 are provided to supply current to the FETs 17 and 18. Also good.
[0094]
In the above embodiment, as shown in FIG. 15, the compensation current is supplied from the AC power source 5 to the AC line through which the AC current flows. However, as shown in FIG. 16, the compensation current can be supplied to the DC line through which the DC current output from the rectifying and smoothing circuit unit 2 flows. Further, the noise reduction circuit unit 4 can be inserted on the output side.
[0095]
【The invention's effect】
As described above, according to the present invention, noise reduction can be performed stably.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a power conversion device according to a first embodiment of the present invention.
2A is a circuit diagram showing the zero-phase current transformer of FIG. 1, FIG. 2B is a perspective view of a through-type current transformer, and FIG. 2C is a perspective view of the zero-phase current transformer. It is.
FIG. 3 is a timing chart showing the operation of the power conversion device of FIG. 1;
FIG. 4 is an explanatory diagram showing the principle of canceling a leakage current.
FIG. 5 is an explanatory diagram for explaining the operation of the noise reduction circuit unit of FIG. 1;
6 is an explanatory diagram for explaining the operation of the noise reduction circuit unit of FIG. 1; FIG.
7 is a timing chart showing an operation of the noise reduction circuit unit of FIG. 1;
FIG. 8 is a circuit diagram showing another configuration of the zero-phase current transformer and the amplifier circuit of FIG. 1;
FIG. 9 is a circuit diagram showing another configuration of the zero-phase current transformer and the amplifier circuit of FIG. 1;
10 is a circuit diagram showing another configuration of the zero-phase current transformer and the amplifier circuit of FIG. 1; FIG.
11 is a circuit diagram showing another configuration of the zero-phase current transformer and the amplifier circuit of FIG. 1; FIG.
12 is a circuit diagram showing another configuration of the zero-phase current transformer and the amplifier circuit of FIG. 1; FIG.
13 is a circuit diagram showing another configuration of the zero-phase current transformer and the amplifier circuit of FIG. 1; FIG.
14 is a circuit diagram showing another configuration of the zero-phase current transformer and the amplifier circuit of FIG. 1; FIG.
FIG. 15 is a block diagram showing the configuration of the power conversion apparatus in FIG. 1;
FIG. 16 is a block diagram showing another configuration of the power conversion device.
FIG. 17 is a circuit diagram showing a configuration of a conventional power converter.
[Explanation of symbols]
1 Noise filter section
3 Power conversion circuit
4 Noise reduction circuit
21 Zero-phase current transformer
22 Amplifier circuit
23 Constant voltage circuit

Claims (7)

Provided between an AC power source and a power converter that converts AC power supplied from the AC power source into predetermined AC power or DC power and supplies the load to the load, and leaks from the power converter and the load to the ground line A noise reduction device that supplies current to the ground line in a direction that cancels leakage current, and reduces noise in the power conversion device ,
In order to detect a current corresponding to the leakage current, AC power supplied from the AC power supply is inserted into a pair of power supply lines that supply the power converter, and a zero-phase current of the pair of power supply lines is detected as a detection ratio. A leakage current detecting means for detecting in 1 ;
Power supply means for inputting an alternating current power supply voltage on the alternating current power supply side from the leakage current detection means, rectifying and smoothing, and outputting a predetermined direct current voltage;
A direction in which the DC voltage supplied from the power supply means is used as a power source, and the current corresponding to the leakage current detected by the leakage current detection means is amplified with an amplification factor of 1 to cancel the leakage current to the ground line. Amplifying means for supplying to
Noise reduction apparatus comprising the. The amplification means includes
An NPN transistor, a PNP transistor, a capacitor,
With
The collector of the NPN transistor is connected to the positive side of the power supply means, the emitter of the PNP transistor is connected to the emitter of the NPN transistor, and the collector of the PNP transistor is connected to the negative side of the power supply means. The one output terminal of the leakage current detecting means is connected to the base of the NPN transistor and the base of the PNP transistor, and the other output terminal of the leakage current detecting means is the emitter of the NPN transistor and the emitter of the PNP transistor. Connected to
The capacitor is configured to be connected between the ground line and a base of the NPN transistor and a base of the PNP transistor.
The noise reduction device according to claim 1 . The leakage current detection means has two output windings,
The amplification means includes
Two NPN transistors, a capacitor,
With
The collector of the one NPN transistor is connected to the positive side of the power supply means, and the base and emitter of the one NPN transistor are respectively connected to both ends of one output winding of the leakage current detection means. The collector of the other NPN transistor is connected to the base of the one NPN transistor, and the base and emitter of the other NPN transistor are respectively connected to the other output winding of the leakage current detecting means. Connected to both ends, the base of the other NPN transistor is connected to the negative side of the power supply means,
The capacitor is configured to be connected between the ground line and the base of the one NPN transistor.
The noise reduction device according to claim 1 . The leakage current detection means has two output windings,
The amplification means includes
A PNP transistor, an NPN transistor, a capacitor,
With
The base of the PNP transistor is connected to the positive electrode side of the power supply means, the collector of the NPN transistor is connected to the collector of the PNP transistor, and the base and emitter of the PNP transistor are each configured to detect the leakage current. Connected to both ends of one output winding of the means, and the base and emitter of the NPN transistor are respectively connected to both ends of the other output winding of the leakage current detecting means, and the base of the NPN transistor is Connected to the negative electrode side of the power supply means,
The capacitor is configured to be connected between the ground line and a collector of the NPN transistor.
The noise reduction device according to claim 1 . The leakage current detection means has two output windings,
The amplification means includes
Two PNP transistors, a capacitor,
With
The base of the one PNP transistor is connected to the positive side of the power supply means, and the base and the emitter are respectively connected to both ends of one output winding of the leakage current detection means, and the other The base of the PNP transistor is connected to the collector of the one PNP transistor, the base and the emitter are respectively connected to both ends of the other output winding of the leakage current detecting means, and the collector is connected to the power Connected to the negative side of the supply means,
The capacitor is configured to be connected between the ground line and a base of the other PNP transistor.
The noise reduction device according to claim 1 . 6. The noise reduction device according to claim 2, wherein in the amplifying means, the NPN transistor is replaced with an N-type field effect transistor, and the PNP transistor is replaced with a P-type field effect transistor. . 2. A power converter for converting AC power supplied from an AC power source into predetermined AC power or DC power and supplying the load to a load, wherein the noise reduction device according to claim 1 is provided on the input side. Conversion device.

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