JP2012059495A - Charging cable for electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charging cable for an electric vehicle which has a small outside diameter, does not require shielding and is superior in flexibility.SOLUTION: The cable is so structured that it has four feeders made by uniformly dividing the conductor cross-sectional area of a feeder into two and arranging feeders having the same polarity in parallel or in diagonal positions. The outside diameter of the cable can be made small and a charging cable for an electric vehicle which is flex and superior in handleability and housing property can be obtained by uniformly dividing the conductor cross-sectional area of the feeder into two to make four feeders. Since the outside diameter of the feeder becomes small by dividing the conductor cross-sectional area of the feeder into two, and consequently the distance between the conductors of the feeder becomes short, the characteristic impedance between the polarities of the feeder can be decreased, and the emission of noise occurring from the feeder to the outside can be prevented.

Description

  The present invention relates to a charging cable for an electric vehicle.

An electric vehicle that travels using electric power stored in a battery as a power source has been put into practical use. These electric vehicles charge a battery by receiving power supply from a commercial power source supplied to each household or an outdoor charging facility.
For charging a battery, a charging cable for an electric vehicle that connects a power supply port and a power supply battery mounted on a vehicle is used.
The charging cable is generally composed of two power supply lines of an anode (+ electrode) and a cathode (−) and a plurality of signal control lines. A power supply line of this type of charging cable uses a conductor having a relatively large cross-sectional area in order to safely supply a large current to a battery of an electric vehicle and complete charging in a short time.

  Further, since a large current flows through the feeder lines, the signal control lines are reliably shielded in order to prevent noise with respect to the signal control lines adjacent to these feeder lines.

  Since the charging cable used for charging the battery of the electric vehicle as described above has a large conductor cross-sectional area of the feeder line, the outer diameter of the cable is increased and flexibility is impaired. Moreover, the rigidity of the cable is increased by shielding the signal control line. Therefore, it is desired to develop a flexible charging cable for an electric vehicle from the viewpoint of handling and storage.

The charging cable for electric vehicles having a large outer diameter and high rigidity according to the prior art has the following problems.
(1) Since the outer diameter is large and the rigidity is high, it is necessary to secure a sufficient length of the charging cable and improve the handleability by utilizing the elasticity of this length.
(2) When charging, a large radius of curvature is required to bend the charging cable, and it is necessary to secure a large working space.
(3) When the charging cable is wound around the charging cable storage device in the trunk of the automobile, it is necessary to enlarge the charging cable storage device.
(4) The cost increases as the cable outer diameter increases, and the weight of the vehicle increases.

  The present invention has been made to solve these problems, and provides an inexpensive charging cable that has a small cable outer diameter, excellent flexibility, and is easy to use even if the conductor cross-sectional area of the feeder line is the same. Objective.

  In addition, the present invention is a malfunction of the electrical equipment connected to the signal control line caused by the conduction noise propagating from the power supply source (inverter, converter) to the power supply line wrapping around the signal control line without shielding, It is another object of the present invention to provide a charging cable that prevents noise propagating through a feeder line from being emitted as radiated noise using the feeder line as an antenna and becoming a noise to a signal control line or an electronic device in a close position.

    In order to achieve the above object, the charging cable for an electric vehicle according to the present invention equally divides the set conductor cross-sectional area of the power supply line into two parts, and appropriately requires four power supply lines having the same conductor cross-sectional area. A charging cable for an electric vehicle in which the outer diameter of the cable is reduced by applying a sheath to an assembly formed by twisting a plurality of signal control lines, and four feed line conductors are provided at both ends of the charging cable. It is characterized by being connected to the charging side feeding port and the (+) pole and the cathode (−) of the receiving port anode of the electric vehicle by matching them two by two.

  Also, by dividing the feeder line conductor into two parts and arranging the feeder lines of the same polarity of the four feeder lines with a reduced outer diameter in parallel or diagonally, the conductor of the feeder line that does not divide the conductor cross-sectional area into two parts By reducing the distance between the conductors and reducing the characteristic impedance between the feed line polarities, the noise in the feed line is not emitted outside the feed line.

  According to the present invention, it is possible to reduce the outer diameter of the charging cable even when the conductor cross-sectional area of the feeder line is the same, and to provide a charging cable for an electric vehicle that is small in rigidity and excellent in flexibility and easy to use. Can do.

Further, since noise leaking from the power supply line can be surely reduced, there is no need to shield the signal control line or the entire cable, thereby providing a low-rigidity and inexpensive charging cable for an electric vehicle.

Sectional drawing of the charging cable for electric vehicles which arrange | positioned the feed line of the same polarity of this invention in parallel Sectional drawing of the charging cable for electric vehicles which arrange | positioned the feed line of the same polarity of this invention diagonally Sectional view of a conventional charging cable for electric vehicles Enlarged view of the signal control line of a conventional charging cable for electric vehicles

The electric vehicle charging cable of the present invention has been created based on the following two findings.

  As shown in FIGS. 1 and 2, the charging cable for an electric vehicle of the present invention is composed of four power supply lines and a plurality of signal control lines, and the same polarity power supply lines are arranged in parallel (FIG. 1) or diagonally (see FIG. 1). By arranging in 2), the distance between feeder conductors having different polarities is arranged to be short.

(1) Dividing the conductor cross-sectional area of the feeder line into two equal parts, and reducing the outer diameter of the feeder line aggregate twist by using four feeder lines

The conductor outer diameter of the feeder line is derived from the set conductor cross-sectional area by the following equation.
From A = πr ^ 2 d = 2 · √ (A / π)
d: conductor outer diameter A: conductor area r: conductor radius

The thickness of the insulator of the feeder line is determined from the insulation resistance required for the feeder line, and the outer diameter of the feeder line at that time is derived from the following equation.

Insulation resistance R = 0.366ρlog (D / d) × 10 ^ -5
Feed wire outer diameter D = [10 ^ (R / (0.366ρ × 10 ^ -5))] × d

R: Insulation resistance of power supply line (Ω · km)
ρ: Volume resistivity (Ω · cm) of insulator material
D: Feeder outer diameter d: Conductor outer diameter

The outer diameter of the assembly when the feeder lines are twisted is derived from the following equation.

Outer diameter of feeder line Da = [(1 + 1 / sin (π / n)] × D

Da: collective outer diameter n: number of cores of collective twisted feed line D: feed line outer diameter

From the above formula, the cross-sectional area when the conductor cross-sectional area of the feeder line is not divided into two is A = 1 (the number of the feeder lines of the cable is two), and the sectional area when equally divided into two is A = 0.5 ( 4), and insulation resistance R required for the feed line R = 50 × 10 6 Ω · km and volume specific resistance of the material used for the feed line ρ = 5 × 10 13 Ω · cm (the insulation material is PVC) When calculating the aggregate twist outer diameter as the value when
Conductor outer diameter d = 1.13, feeder line outer diameter D = 2.12, feeder line aggregate twist outer diameter Da = 4.23 when cross-sectional area A = 1 when not divided into two
Conductor outer diameter d = 0.80 when the cross-sectional area A is 0.5 when divided into two, feeder outer diameter D = 1.50, feeder aggregate twist outer diameter Da = 3.61
become.

  From the above results, the outer diameter of the feeder line aggregate twist can be reduced by about 15% by equally dividing the conductor cross-sectional area of the feeder line into two. This makes it possible to reduce the diameter of the electric vehicle charging cable.

(2) The power supplied from the power source to the charging cable is reduced by dividing the conductor cross-sectional area of the feeder line into two equal parts, reducing the diameter of the feeder line, and shortening the distance between the feeder conductors of different polarities. It is converted into an electrical component (frequency, voltage, etc.) suitable for charging and supplied through an inverter or converter. Since inverters and converters perform power conversion by switching control, noise due to switching is likely to occur, and the generated noise propagates through the feeder line in a form overlapping the power waveform.

  Noise propagating through the feeder line is composed of various frequency components, and has a property that it is likely to be released to the outside through the electrostatic capacitance of the insulator of the feeder line.

  In charging cables, the capacitance of the feeder insulation affects the noise diffusion, and adjacent insulation with a different polarity (flowing in the reverse direction) through the capacitance of the insulation. Noise is propagated to the core wire (other power supply lines and signal control lines).

  As a measure for preventing the spread of noise propagating through the power supply line, the noise between the power supply lines having different polarities (flowing in the opposite direction) is increased, so that the noise propagating through the anode (+ pole) becomes the cathode (GND). ) To be easily leaked. In this way, it is effective to cause noise to be looped in the feed line and reduce noise emission to the outside of the feed line.

The capacitance is expressed by the following formula.

Capacitance C = (12.05ε) / [log10 (D1 + √ (D12−k2 · d2) / (k · d)]

C: Capacitance (nF / km)
D1: Feeder conductor distance (mm)
k: Conductor effective outer diameter coefficient d: Conductor diameter (mm)
ε: Effective relative permittivity From this, it can be seen that the capacitance increases as the conductor spacing of the feed lines of different polarities decreases.

Further, when a current flows through the feeder line, an induced electromotive force is generated due to the inductance of the feeder line. The induced electromotive force is a voltage generated in a direction opposite to the current flow due to the magnetic flux generated by the current flow, and inhibits the current flow. Therefore, in order to efficiently flow the leaked noise to the cathode (GND), it is effective to reduce the inductance.
Inductance is expressed by the following equation.

Inductance L = 0.4loge (2D1 / d) + 0.1μ

L: Inductance (mH / km)
D1: Distance between conductors (mm)
d: Conductor diameter (mm)
μ: Relative permeability of conductor (copper = 1)
From this, it can be seen that the inductance becomes smaller as the conductor spacing of the feeding lines of different polarities is smaller.

As described above, the capacitance C, the inductance, and the characteristic impedance Z0 have the following relationship.
Zo = √ (L / C)
In order to exert an effective noise reduction effect, the larger the capacitance C, the smaller the inductance L, and the above equation, the lower the characteristic impedance Z0, the higher the noise reduction effect. .

Based on the above-described principle, the present invention equally divides the conductor cross-sectional area of the two power supply lines into two parts, sets the power supply lines to four, and reduces the outer diameter of the power supply lines, thereby providing different power supply lines. Capacitance can be increased by shortening the distance between the conductors, and by further arranging power supply lines of the same polarity diagonally and adjacent to each other with different polarity power supply lines. The noise is reduced by reducing the inductance and lowering the characteristic impedance Z0.
Hereinafter, a cable structure according to an embodiment of the present invention will be specifically described with reference to the drawings.

  FIG. 1 is a cross-sectional view of a charging cable for an electric vehicle to which the present invention is applied when the conductor cross-sectional area of the feeder line is set to 35.6 mm 2, and Table 1 shows the configuration and characteristic impedance performance of this charging cable. Is.

In FIG. 1, the conductor of the feeder line is made by twisting 700 strands having a strand diameter of 0.18 mm, and its cross-sectional area is a conductor cross-sectional area that is ½ of the set cross-sectional area of the feeder line conductor. Is. An insulation coating of PVC having a thickness calculated from the above formula was formed outside the conductor. The anode power supply lines 1a and 1b (two) and the cathode power supply lines 2a and 2b (two) are arranged so that the power supply lines of the same polarity are arranged in parallel, and are shielded against twisting. The signal control line 3 is combined and twisted in the arrangement shown in the cross-sectional view of FIG. 1, and the sheath 4 is formed on the outside thereof. The charging cable had a feeder line conductor diameter of 5.50 mm, a feeder line outer diameter of 9.1 mm, and an aggregate twist outer diameter of 22.3 mm.
In addition, the signal control line 3 does not affect the collective outer diameter of the power supply line by being arranged in a space generated in the power supply line assembly.
Further, the characteristic impedance between the polarities of the feeder lines was 46Ω when measured by the TDR method using a digital sampling oscilloscope “TDS8200 manufactured by Tektronix”.

A charging cable was manufactured under the same conditions except that the anode feeders 1a and 1b (two) and the cathode feeders 2a and 2b (two) were arranged at diagonal positions with the same polarity of the feeder.
The charge cable conductor diameter, the feed line outer diameter, and the collective twist outer diameter of this charging cable were the same as those in Example 1.
Further, the characteristic impedance between the feeder line polarities was 27Ω when measured by the TDR method in the same manner as in Example 1.

Comparative example

  FIG. 3 is a cross-sectional view of a conventional charging cable for an electric vehicle when the conductor cross-sectional area of the feeder line is set to 35.6 mm 2 as in the embodiment, and Table 1 shows the configuration and characteristic impedance performance of this charging cable. It is a thing.

In FIG. 3, the conductor of the feeder line is obtained by twisting 1400 strands having a strand diameter of 0.18 mm. An insulation coating of PVC having a thickness calculated from the above formula was formed outside the conductor. Then, the anode power supply line 5 and the cathode power supply line 6 and the anti-twist signal control line 7 which is shielded as shown in FIG. 4 are twisted together in the arrangement shown in FIG. The charging cable had a feeding line conductor diameter of 7.77 mm, a feeding line outer diameter of 12.9 mm, and an aggregate twist outer diameter of 26.1 mm.
It should be noted that the signal control line 7 has an influence on the outer diameter of the collective twist of the feed line by being arranged in a space generated in the aggregate of the feed lines, similarly to the charging cable of FIGS. 1 and 2 of the embodiment of the present invention. There is no.
Further, the characteristic impedance between the feed line polarities was measured by the TDR method in the same manner as in Example 1, and it was 77Ω.

As can be seen by comparing the examples of Table 1 and the comparative example, in the same conductor cross-sectional area, the charging cable for an electric vehicle of the present invention has a collective twist outer diameter as theoretically compared to a conventional charging cable for an electric vehicle. The diameter was reduced by about 15%.
Even when the thickness of the sheath is set to the same thickness of 3.60 mm for the purpose of protection, the outer diameter of the charging cable of the present invention is 29.5 mm, and the conventional charging cable is 33.3 mm, which is about 11% thinner. The diameter was reduced.

  The characteristic impedance between the feed lines of different polarities was 77Ω in the conventional electric vehicle charging cable, but was 46Ω in Example 1 in Table 1. This is due to the fact that the conductor interval of the power supply lines having different polarities is reduced by reducing the insulation outer diameter of the power supply line.

Moreover, in Example 2 of Table 1, the impedance between the feed lines of different polarities was 27Ω. this is,
In the first embodiment (FIG. 1), the power supply lines having different polarities arranged diagonally are arranged adjacent to each other in the second embodiment (FIG. 2). This is because the capacitance between 2a increases and the inductance decreases.

  The ratio of the amount of noise generated by the power supply line is inversely proportional to the characteristic impedance between the power supply line polarities. In the charging cable for an electric vehicle of the present invention, the noise generated from the conventional electric vehicle charging cable is higher in Example 1. The reduction was 40%, and in Example 2, the reduction was 65%.

  This makes it possible to omit shielding from the signal control line 7 of the conventional charging cable.

  The embodiment of the present invention has been described above. However, the present invention is not limited to the conductor cross-sectional area of 35.6 mm 2, and the same applies to any conductor cross-sectional area within the scope of the present invention. The effect is obtained.

1a Feed line (anode) with two-part conductor cross-sectional area
1b Feed wire (anode) with two-part conductor cross-sectional area
2a Feed wire (cathode) with two-part conductor cross-sectional area
2b Feed wire (cathode) with two-part conductor cross-sectional area
3 Signal control line without shielding 4 Sheath 5 Feed line (anode) of conductor cross-section not divided into two
6 Feed line (cathode) with conductor cross-section not divided into two
7 Shielded signal control line 8 Sheath 9 Intervening 10 Holding tape 11 Braided shield 12 Aluminum tape shield

Claims (1)

  The four cross sections of the power supply line conductor set from the amount of power supplied from the power source are equally divided into four power supply line conductors, and four power supply lines having an insulation coating formed on the outside of the conductor; In a charging cable for an electric vehicle configured by twisting together a plurality of necessary signal control lines as appropriate, the feeding lines of the same polarity are arranged in parallel or diagonally, and four feeding line conductors are provided at both ends of the cable. A charging cable for an electric vehicle, characterized in that the two are connected to the charging side feeding port and the receiving port of the electric vehicle as anode (+ pole) and cathode (-) feeding lines