JP2003309902A - Vehicle power converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress high frequency leakage current running via a parasitic capacitor component parasitizing in a vehicle power converter. <P>SOLUTION: The vehicle power converter comprises a power conversion circuit 1 consisting of a semiconductor switch, and a main circuit wiring (a positive power supply) 7; a main circuit wiring (a negative power supply) 8 connected to the power conversion circuit via an open switch 4; a short circuit switch 3; a smoothing capacitor (of the case is conductive) 2 which is connected to the power control circuit side, closer than the short circuit switch in parallel with a short circuit switch, and which smoothes DC input voltage of the power conversion circuit; and a grounding conductor 5 for connecting a housing 9 of the power converter with a vehicle body, and is rigged on the vehicle body. The smoothing capacitor is provided on an insulator 500, the insulation is made between the smoothing capacitor and the housing. The smoothing capacitor and the housing are connected to each other via a resistor 50, and the negative side of the open switch is connected with the housing via a resistor 51. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle power converter, and more particularly to a technique for suppressing high frequency leakage current emitted from the power converter.

[0002]

2. Description of the Related Art As a conventional technique, FIG. 8 shows an outfitted state of a power conversion device in a railway vehicle. Power converter 9
Is installed under the floor of the vehicle 6 and is installed on the overhead line, the roof of the vehicle, the current collector 13, the circuit breaker 14, the smoothing reactor 1
5, DC power is obtained from the substation through a path formed by the power conversion device 9, the carriage, and the rail. Figure 5
The electrical connection between the inside of the power conversion device and the vehicle body is shown in FIG. The power conversion device includes a power conversion circuit 1 including a semiconductor switch, a main circuit wiring (plus power supply) 7 that supplies power to the power conversion circuit, and a main switch connected to the power conversion circuit 1 via an open switch 4. The circuit wiring (minus power supply) 8, the short circuit switch 3 connected between the main circuit wiring 7 and the power conversion circuit side of the open switch 4, and the power conversion circuit side of the short circuit switch 3 in parallel with the short circuit switch 3. It is composed of a smoothing capacitor 2 which is connected and smoothes the DC input voltage of the power conversion circuit 1, and a ground wire 5 which connects the casing 9 of the power conversion device and the vehicle body 6. The alternating current from the power conversion circuit 1 is output via the motor line 10.

[0003]

When the semiconductor element forming the power conversion circuit is switched, the output voltage of the power conversion circuit changes abruptly. As the output voltage of the power conversion circuit fluctuates, a high-frequency leakage current flows through wiring inside the power conversion device, components such as a smoothing capacitor and the housing, and a parasitic capacitor component parasitic between the housing and the vehicle body.
Among them, the high frequency leakage current leaking from the case of the smoothing capacitor to the housing is large. These leakage currents leak to the outside of the power conversion device via the casing of the power conversion device,
It adversely affects communication equipment and signal equipment.

An object of the present invention is to suppress high-frequency leakage current flowing through a parasitic capacitor component parasitic inside the power conversion device.

[0005]

In order to solve the above problems, when the case of the smoothing capacitor is a conductor, the case of the power converter is insulated from the smoothing capacitor, and
The case and housing of the smoothing capacitor are connected via the current reduction element. Further, when the case of the smoothing capacitor is a conductor, the case of the smoothing capacitor and the case are insulated from each other. Further, the case of the smoothing capacitor is a conductor, and the case of the smoothing capacitor and the housing are connected via the current reducing element.
Also, when the smoothing capacitor case is non-conductive,
The surface of the case of the smoothing capacitor facing the housing of the power conversion device is covered with a conductive material, and the conductive material and the housing are connected via a current reducing element. Further, the wiring on the negative side of the DC input of the power conversion circuit and the housing are connected via the current reducing element.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of a vehicle power converter showing an embodiment of the present invention. In FIG.
The same symbols as those in FIG. 5 are attached to the same devices as those in FIG. In the present embodiment, the smoothing capacitor 2 (the case is conductive) 2 is arranged on the insulator 500 to insulate the smoothing capacitor 2 and the housing 9 from each other, and the smoothing capacitor 2 and the housing 9 are resistive. And the housing 9 is connected by a resistor 51 (current reduction element).

FIG. 2 shows an equivalent circuit for high frequency components in the configuration of FIG. An equivalent circuit for the high frequency component of the smoothing capacitor 2 is shown in FIG. In FIG.
The smoothing capacitor 2 has a configuration in which the capacitor cell 21 is covered with a metal case. The capacitor cell 21 is configured to store charges inside. At this time, parasitic capacitances 22 and 23 having an insulator between the capacitor cell 21 and the metal case of the smoothing capacitor 2 as a dielectric are generated, and the equivalent circuit of the smoothing capacitor 2 is as shown in FIG. In FIG.
11 is an equivalent noise source, 12 is a parasitic capacitor, 18 is a vehicle body ground, 24 and 44 are parasitic capacitors, 25 and 40 are parasitic inductances, 41 is a noise propagation path, and 50 and 5
Reference numeral 1 represents a resistor. A large leakage current I is generated by a resonance circuit formed by a capacitor (collection of parasitic capacitances 22 and 23) 24 parasitic between the metal case of the smoothing capacitor 2 and the included capacitor cell 21 and a parasitic inductance 25 of the wiring. Flowing. In the present embodiment, the smoothing capacitor 2 and the housing 9 are insulated (insulator 500), and the smoothing capacitor 2 and the housing 9 are connected via the resistor 50, so that the parasitic capacitor 24 and the wiring are connected. Resonance of the parasitic inductance 25 and high-frequency leakage current generated therewith are suppressed. Of course, it is possible to suppress the leakage current due to resonance without inserting the resistor 50 only by ensuring the insulation between the smoothing capacitor 2 and the housing 9. In addition, the smoothing capacitor 2 case and housing 9
If the case of the smoothing capacitor 2 and the case 9 are connected with a resistor having an impedance lower than the impedance between the case of the smoothing capacitor 2 and the case 9, the potential of the case of the smoothing capacitor 2 becomes stable. There is no potential difference between the two. As a result, even if the case of the smoothing capacitor 2 and the case 9 are not insulated, no leakage current flows between the case of the smoothing capacitor 2 and the case 9.

Further, the main circuit wiring 8 has a length of several meters to tens of meters in some cases. For this reason, the inductance 40 becomes non-negligible with respect to the high frequency component, and the potential of the negative terminal of the smoothing capacitor 2 becomes unstable at high frequencies. Therefore, with the switching of the power conversion circuit 1, the smoothing capacitor 2, the open switch 4, the short-circuit switch 3, and the power conversion circuit 1 that are present inside the power conversion device 1
A leakage current B flows through a parasitic capacitor (collectively expressed) 44 that is parasitic between an electric device such as the above and the housing 9. Therefore, the power source side of the open switch 4 is connected via the resistor 51. As a result, the potential on the power supply side of the open switch 4 of the main circuit wiring 8 becomes the casing 9, that is, the ground potential, and the potential on the negative side of the smoothing capacitor 2 and the potential of the electric equipment existing inside the power converter are stabilized. Is
Leakage current flowing through the parasitic capacitor 44 that is parasitic between these electric devices and the housing 9 can be suppressed. Of course, the same result can be obtained by connecting the resistor 51 between the smoothing capacitor 2 side of the open switch 4 and the housing 9.

In a vehicle power converter, it is common to periodically test whether or not the electrical equipment constituting the device maintains a sufficient insulation ability against the ground. In this test, the open switch 4 is opened, the short-circuit switch 5 is short-circuited, and a high voltage (in the case of a 1500V class device) is placed between the smoothing capacitor 2 side of the open switch 4 and the casing 9 (that is, the ground potential). , AC5400V) is applied.
Therefore, when the resistor 51 is connected to the smoothing capacitor 2 side of the open switch 4, the resistor 51 needs to have a withstand voltage considering the above test. On the other hand, when the resistor 51 is connected to the negative side of the open switch 4, the resistor 51 is disconnected during the above-described test, so that a resistor having a relatively low breakdown voltage can be used, which is advantageous in terms of size and weight reduction. Please note that.

FIG. 3 shows another embodiment of the present invention. In this embodiment, the smoothing capacitor 29 is made of non-metal (non-conductive).
It is an example in the case of. When the case is non-metallic, the insulation between the smoothing capacitor (the case is non-conductive) 29 and the case 9 can be ensured by the case. Therefore, as shown in FIG. No need to insulate with 500. However, the capacitor cell 21
Since a parasitic capacitor (not shown) including the parasitic capacitors 22 and 23 exists between the housing 9 and the housing 9, a resonant current due to the parasitic capacitor and the parasitic inductance (not shown) flows. In order to suppress this, the non-metal case is covered with the conductor 200, and the conductor 200 and the housing 9 are connected via the resistor 50. As a result, it is possible to suppress the leakage current flowing through the parasitic capacitor that is parasitic between the capacitor cell 21 and the housing 9. Here, the parasitic capacitor parasitic between the capacitor cell 21 and the housing 9 has the largest parasitic capacitance generated at the portion where the surface of the non-metal case and the surface of the housing 9 face each other. Therefore, as shown in FIG. 4, even if the conductor 200 is arranged only in a portion where the case surface and the housing 9 face each other and the conductor 200 and the housing 9 are connected via a resistor, the same result is obtained. The effect of is obtained.

FIG. 7 shows another embodiment of the present invention. The present embodiment is another example in which the case of the smoothing capacitor is non-metallic (non-conductive). The present embodiment has a configuration in which the terminals of the smoothing capacitor (the case is non-conductive) 29 and the housing 9 are connected via the capacitors 52 and 53 and the resistor 50. Capacitors 52 and 53 having a larger capacity than a parasitic capacitor (not shown) including parasitic capacitors 22 and 23 parasitic between the capacitor cell 21 and the housing 9.
And resistor 50 are connected. This allows the capacitor 5
A bypass circuit composed of 2, 53 and the resistor 50 is formed to suppress the current flowing in the parasitic capacitor parasitic between the capacitor cell 21 and the housing 9, and the action of the resistor 50 constitutes the bypass circuit. Resonance between the capacitors 52 and 53 and the parasitic inductance (not shown) is suppressed, and the same effect as in FIG. 3 is obtained. Of course, if there is enough room for the equipment, the housing 9
It is also possible to reduce the size of the parasitic capacitor by providing a distance between the capacitor and the smoothing capacitor 29, and to suppress the resonance between the parasitic inductance and the parasitic capacitor and the generation of leakage current due to the resonance. In this case, when the parasitic inductance is L, the parasitic capacitor is C, and the resistance of the wiring is R, if the distance between the smoothing capacitor 29 and the housing 9 is ensured so as to satisfy C <4L / R ² . It is possible to suppress the vibration component due to the resonance of the parasitic inductance and the parasitic capacitor. This is also effective when the case of the smoothing capacitor is a conductive substance.

Although the above embodiments have been described by taking the case where the smoothing capacitor is connected to the DC side of the power conversion circuit as an example, the same effect can be obtained when the capacitor is connected to the AC side of the power conversion circuit. It goes without saying that you can get it. FIG. 9 shows another embodiment of the present invention. This embodiment is an example in which a capacitor is connected to the AC side of the power conversion circuit. In FIG. 9, the power conversion circuit 1
A filter circuit including a reactor 101 and a capacitor 102 is provided on the AC output side for the purpose of removing the ripple component generated by. Even when the capacitor is connected to the AC side, the harmonic component accompanying switching causes a leakage current via the parasitic capacitance between the case of the capacitor 102 and the housing 9. In order to suppress this, the case of the capacitor 102 and the case 9 are insulated from each other by an insulator 104, and the case of the capacitor 102 and the case 9 are also insulated.
The resistor 103 is connected between the two. Thereby, the leakage current can be suppressed.

In the above-described embodiment, the leakage current is suppressed by using the resistor. However, if the direct current component flowing through the resistor cannot be ignored, it is necessary to increase the capacitance of the resistor, and Not only is it an obstacle to size and weight reduction, but the power consumed by the resistor reduces the efficiency of the power converter. Thus, when the DC component cannot be ignored, the resistor and the capacitor are connected in series to remove the DC component flowing through the resistor. This allows
The above problems can be solved. Further, the present invention is
Since the arrangement and connection of the electric devices inside the power conversion device are changed, the electric device can be implemented without affecting other elements constituting the vehicle, and can be realized relatively easily. The present invention is also applicable to an apparatus for an AC vehicle that receives an AC voltage as an input, rectifies the AC to obtain a DC voltage, and uses the DC voltage obtained by the rectification as a voltage source to obtain the AC.

[0014]

As described above, according to the present invention,
By insulating the smoothing capacitor from the case and connecting the smoothing capacitor case to the case with a resistor, resonance between the parasitic capacitor and the parasitic inductance component inside the smoothing capacitor can be suppressed, and high-frequency leakage current can be prevented. Can be suppressed. In addition, by connecting the wiring on the negative side of the DC input of the power conversion circuit and the housing with a resistor, the housing potential of the power conversion apparatus becomes stable at high frequencies, so high-frequency current that leaks from the power conversion apparatus to the vehicle body. Can be suppressed. By installing a resistor that connects the wiring on the negative side of the DC input of the power conversion circuit and the housing on the negative side of the open switch, when testing the insulation of the high-voltage equipment that constitutes the power conversion device, the resistance from the high-voltage power supply Since the resistor can be disconnected by the open switch, it is possible to use a low-voltage, low-cost resistor.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a vehicle power converter showing an embodiment of the present invention.

FIG. 2 is a diagram showing an equivalent circuit for noise in the present invention.

FIG. 3 is a diagram showing another embodiment of the present invention.

FIG. 4 is a diagram showing another embodiment of the present invention.

FIG. 5 is a configuration diagram of a power conversion device according to a conventional example.

FIG. 6 is a diagram showing an equivalent circuit of a smoothing capacitor.

FIG. 7 is a diagram showing another embodiment of the present invention.

FIG. 8 is a diagram showing a state in which the power conversion device is equipped.

FIG. 9 is a diagram showing another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Power conversion circuit, 2 ... Smoothing capacitor (case is conductive), 3 ... Short circuit switch, 4 ... Open switch, 5 ... Ground wire, 6 ... Car body, 7 ... Main circuit wiring (plus power supply), 8 ...
Main circuit wiring (minus power supply), 9 ... Casing, 10 ... Motor wire, 11 ... Equivalent noise source, 12 ... Parasitic capacitor, 13
... current collector, 14 ... circuit breaker, 15 ... smoothing reactor, 1
8 ... Body ground, 21 ... Capacitor cell, 22, 23 ...
Parasitic capacitor, 24 ... Parasitic capacitor, 25 ... Parasitic inductance, 29 ... Smoothing capacitor (case is non-conductive), 40 ... Parasitic inductance, 41 ... Noise propagation path, 44 ... Parasitic capacitor, 50, 51 ... Resistor, 50
0 ... Insulating plate, 200 ... Conductive cover, 52, 53 ... Bypass capacitor, 101 ... Reactor, 102 ... Capacitor, 103 ... Resistor, 104 ... Insulator

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takashi Kaneko             1070 Ichimo, Hitachinaka City, Ibaraki Prefecture Stock Association             Hitachi, Ltd. Transportation Systems Division Mito Transportation             System headquarters (72) Inventor Shoichi Hisada             1070 Ichimo, Hitachinaka City, Ibaraki Prefecture Stock Association             Hitachi, Ltd. Transportation Systems Division Mito Transportation             System headquarters F-term (reference) 5H007 AA01 BB06 CA00 CB02 HA03                 5H115 PA03 PC02 PG01 PI03 PI29                       PV09 PV21 UI33 UI34 UI38

Claims (9)

[Claims] 1. A power conversion circuit including at least a semiconductor, a smoothing capacitor for smoothing a DC voltage of the power conversion circuit, a wiring for supplying power to the smoothing capacitor, the power conversion circuit and the smoothing capacitor. In a vehicle power conversion device that is configured from a housing that encloses the wiring and is mounted on a vehicle body, the case of the smoothing capacitor is a conductor, and the case and the housing are insulated from each other. An electric power converter for a vehicle, which is connected to a housing via a first current reducing element. 2. A power conversion circuit comprising at least a semiconductor, a smoothing capacitor for smoothing a DC voltage of the power conversion circuit, a wiring for supplying power to the smoothing capacitor, the power conversion circuit and the smoothing capacitor. A vehicle power conversion device that is composed of a housing that encloses the wiring and is mounted on a vehicle body, wherein the case of the smoothing capacitor is a conductor, and the case and the housing are insulated from each other. Power converter. 3. A power conversion circuit composed of at least a semiconductor, a smoothing capacitor for smoothing a DC voltage of the power conversion circuit, wiring for supplying power to the smoothing capacitor, the power conversion circuit and the smoothing capacitor. A power conversion device for a vehicle, which comprises a casing including the wiring and is mounted on a vehicle body, wherein the case of the smoothing capacitor is a conductor, and the case and the casing are connected via a first current reducing element. A power conversion device for a vehicle, which is characterized in that the power conversion device is connected. 4. The electric power converter for a vehicle according to claim 3, wherein the impedance of the first current reducing element is smaller than the impedance between the case and the housing. 5. A power conversion circuit composed of at least a semiconductor, a smoothing capacitor for smoothing a DC voltage of the power conversion circuit, wiring for supplying power to the smoothing capacitor, the power conversion circuit and the smoothing capacitor. A power conversion device for a vehicle, which comprises a housing containing the wiring and is mounted on a vehicle body, wherein the case of the smoothing capacitor is a non-conductive body, and the surface of the non-conductive case facing the housing is An electric power converter for a vehicle, which is covered with a conductive material and connects the conductive material and the casing through a first current reducing element. 6. A power conversion circuit including at least a semiconductor, a smoothing capacitor for smoothing a DC voltage of the power conversion circuit, a wiring for supplying power to the smoothing capacitor, the power conversion circuit and the smoothing capacitor. In a vehicle power conversion device that is composed of a housing that encloses the wiring and is mounted on a vehicle body, the case of the smoothing capacitor is a non-conductive body, and the smoothing capacitor includes a capacitor cell and the housing. A power conversion device for a vehicle, characterized in that a terminal of the smoothing capacitor and the casing are connected via a circuit in which a capacitor having a larger capacity than a parasitic capacitor parasitic between and a first current reducing element are connected in series. 7. The electric power converter for a vehicle according to claim 1, wherein the wiring and the housing are connected via a second current reducing element. 8. The electric power converter for a vehicle according to claim 1, wherein the first and second current reducing elements are resistors. 9. The vehicle according to any one of claims 1 to 7, wherein the first and second current reducing elements are circuits configured by a series-parallel combination of a capacitor and a resistor. Power converter.