JP2012120383A - Method of charging electric automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide improvements to contact failures of a charging cable which impede the infrastructure, a communication method isolating an in-vehicle CAN communication, multiplexed communication in charging, and a method of simplifying charging cable connection, in rapid charging of an electric automobile.SOLUTION: By using analog modems 23 and 29 for remote communication reversely to extremely-short-range rapid charging communication, increase in contact resistance which causes communication failures is significantly improved, and connection becomes possible by using a shape and a material similar to those of an AC power supply connector for a general electric machine. A charging system and a communication system can be connected by triple poles by using a single line DC superposition system for communication signals, which allows further simplification of cable connection. Thereby, since the time to replace connector components of communication lines, which were conventionally required to be exchanged frequently in a coastal area or a chemical gas generation section, can be postponed drastically, charging stands can be installed everywhere, thus infrastructure can be realized. Isolation and multiplex communication of in-vehicle CAN communication can be also performed.

Description

  The present invention relates to two-way communication between an electric vehicle and a quick charger when charging a secondary battery in the electric vehicle from an external quick charger in a plug-in manner.

  As one of the countermeasures against global warming, the electric vehicle is actively promoted, but the motor drive source in the electric vehicle is obtained from a secondary battery mounted on the electric vehicle. As a matter of course, the energy of the secondary battery mounted on the vehicle is reduced mainly due to the distance traveled, resulting in the lack of gas and the loss of the motor drive source. In order to prevent electric vehicles from running out of electricity, it is sometimes necessary to charge from an external electric vehicle quick charger. The quick charger for an electric vehicle is a device that converts 200V three-phase AC power into direct current and charges a secondary battery mounted on the electric vehicle in a short time of about 15 to 30 minutes. For this reason, it can be said that the development of electric vehicles has become an infrastructure only when quick chargers for electric vehicles, that is, charging stations, are installed throughout the country.

  In addition, when performing rapid charging of an electric vehicle, the electronic control unit (ECU) in the electric vehicle that manages the secondary battery in the electric vehicle and the computer (microcomputer board) in the charging stand communicate with each other, and charging is performed. In order to be optimal, it is necessary to control the charging current value and the charging voltage value in accordance with the state of the secondary battery of the electric vehicle.

  On the other hand, information management in the automobile is processed in real time by connecting two cables around the inside of the car and connecting them to control units arranged in each part. That is, a CAN communication application, which is a kind of serial communication method, is performed, and the control unit of each unit is not operating independently, but exchanges data with other control units as necessary. To put it simply, by using a weak DC voltage circuit, applications such as display of operating speed and engine speed, hydraulic pressure and seat belt warning, and automatic lighting control are performed. In particular, in electric vehicles, monitoring control of the charging status of secondary batteries is extremely important, and reliable communication processing is required. Note that in-vehicle CAN communication is a multiplex communication, has a high transmission speed, and has a function of strictly checking an error signal. Therefore, there is no mistake that the in-vehicle CAN communication is a very excellent and optimal method for in-vehicle communication.

FIG. 1 shows a microcomputer for rapid charging in a charging stand when charging a secondary battery 1 from a power supply source 2 by connecting a communication cable 5 and a charging cable 6 in order to rapidly charge an electric vehicle. It is a schematic diagram which shows that the board 4 and the electronic control unit 3 in an electric vehicle mutually exchange information.
Table 1 shows the contents of data communication at the time of rapid charging of the electric vehicle. The operation status is transmitted from the charging station to the electric vehicle, and the charging command and the charging current value are transmitted from the electric vehicle to the charging station. It is also necessary to transmit a command such as a charging voltage value. Since the electric circuit in the car originally exchanges information using the CAN communication method, the existing information communication is performed by directly connecting the electric car and the external charging station using CAN communication. It is a method.

FIG. 2 shows a case where the communication cable and the charging cable are connected as separate cables when the electric vehicle is rapidly charged.
A communication connector 11 and a charging connector 13 are provided in the electric vehicle. A communication connector 12 is provided at the tip of the communication lines 7 and 8, and charging is provided at the tip of the plus side charging line 9 and the minus side charging line 10. A connector 14 is provided. The communication connector 12 is connected to the communication connector 11, and the charging connector 14 is connected to the charging connector 13.
Further, FIG. 3 shows a method conceived so that the cable connection work can be performed at one time during charging. 3 includes a composite connector 15 in which a communication connector and a charging connector are integrated on the electric vehicle side, and the communication connector and the charging line are bundled together to form a single cable. And a composite connector 16 in which a charging connector is integrated. A method of simplifying the connection work by connecting the integrated composite connector 16 to the integrated composite connector 15 on the electric vehicle side at once is also performed.

JP-A-6-245326

<Problem 1>
One of the biggest obstacles to the lack of infrastructure for rapid charging for electric vehicles is the increase in the contact resistance of the communication connector when connecting the electric vehicle and the charging stand, that is, poor contact. Occurrence.
Communication within the automobile is CAN communication. CAN communication is a communication system using a DC micro voltage circuit, but the contact resistance that is regarded as a problem in such a DC micro voltage circuit generally indicates a small resistance value of 0.1Ω or less in theory. It is. It is well known that an increase in this small contact resistance value introduces noise such as ripples into the communication circuit, greatly affects data transmission, and often impedes accurate information transmission. Causes of increased contact resistance include contact surface roughness, oxide film, oil, dust, rust, and poor tightening. Therefore, in order to keep the contact resistance of the connector portion to a minimum, various measures are being considered for the connector portion.
For example,
By selecting the material, such as reducing the resistance value by making the contact part gold-plated and preventing corrosion at the same time,
A method of enlarging the contact surface by sandwiching a metal with a needle-like tip in a deep groove,
A pressure-contact type in which the needle-shaped tip is inserted into a spring-shaped receptacle, and a structure in which a strong spring is provided on the plug and the lever is used to press-contact on the lever principle to prevent loosening.
Etc.
However, the gold plating method is not suitable for charging an electric vehicle because the material is expensive and the plating peels off if the material is frequently inserted and removed, and the contact resistance may increase. In addition, the connector of the method of expanding the contact surface, press-contacting with a strong spring, or fixing with a lever to reduce the contact resistance is mechanically complicated and naturally has many failures and is expensive.

In addition, it is necessary to consider the fact that the connector part is handled roughly because the quick charging of an electric vehicle is not performed by a person who has received a certain degree of training or a person who has obtained qualifications, but by an unspecified number of ordinary people. is there. Therefore, it is necessary to take a countermeasure on the assumption that contact failure frequently occurs due to adhesion of hand grease or dust to the metal part of the connector.
In addition, the charging stand connector installed near the coast promotes corrosion of the metal part due to salt damage, and promotes corrosion of the metal part due to the influence of gas even in a volcanic area or near a factory where chemical substances are contained in the air. It is natural to make it happen.
In other words, charging stations are not installed in certain locations unless the rate of malfunctions due to poor communication line contact during charging, which is an obstacle to the spread of charging stations indispensable for electric vehicles, can be drastically reduced. Nowhere in the country, such as coastal and volcanic areas, can be an infrastructure that enables charging.

<Problem 2>
Isolation of CAN communication in the automobile is the next major obstacle as the reason why the infrastructure for rapid charging for electric vehicles does not progress.
Data communication that is performed not only in automobiles but in a specific location should be processed only in communication at that specific location. When communication is performed by linking to other systems, it is via some medium. It is common general knowledge in communication technology that the communication format should be changed. For example, when charging an electric vehicle, it is assumed that the communication line on the charging station side is short-circuited due to a poor maintenance system of the charging station or deterioration of the surrounding environment of the charging station. As a result, the in-vehicle CAN communication of the electric vehicle in which the communication line is connected to the charging station in which the communication line is short-circuited becomes a failure state, and it is concluded that there is no risk of causing troubles in the operation of each part such as the display in the vehicle and the door lock. Absent. Or, in the near future, there is a high possibility that the charging station side will be networked. In that case, information on CAN communication in the electric vehicle leaks to the other through the charging station, or unnecessary from the charging station side. Information and instructions may enter the CAN communication of the electric vehicle and become nuisance information.
On the other hand, as a method of not directly linking the electric vehicle and the charging station, there is also the use of a wireless LAN. However, since wireless information is emitted in a radial pattern, interception and interruption of nuisance information are performed more easily than wired communication. End up.
Therefore, it is the best means to isolate the signal by arranging some medium so that unnecessary information cannot be interrupted during communication between the electric vehicle and the charging station in the rapid charging of the electric vehicle. Of course.

<Problem 3>
Next, what is required is a request for diversification of two-way communication between an electric vehicle and a charging station by effectively using a charging time of 15 to 30 minutes.
In the near future, it is assumed that the car navigation software has been improved on the automobile side, and a system environment has been established in which a computer for purposes other than the quick charging computer has been installed on the charging station side. As a result, it is easy to multiplex communications during rapid charging, and it is certain that the diversity between the electric vehicle and the charging station can be improved at once.
Table 2 is an example of a request in a city delivery truck business. In Table 2, for example, the “vehicle number” is stored in advance in the car navigation during the production process of the electric vehicle, so that the charging station can automatically recognize the vehicle number and manage the vehicle. For example, the “password” is useful for preventing unauthorized charging by the driver driving from the car navigation system before charging. For example, if the “navigation time” and “delivery time” can be automatically recognized by the car navigation, it becomes easy to grasp the details of the vehicle operation and to manage the operation. For example, if car navigation automatically transmits the “eco-drive distance”, it can contribute to the eco-measures that are the national policy as a business moral. For example, the “office visit instruction” is a simple means of communication from the business manager to the driver. That is, Table 2 shows the diversification of data transmission that improves convenience in managing vehicles.
Table 3 is an example of a request in the collection and delivery work in the city transportation collection and delivery truck, and is information transmission for shortening the collection and delivery time and managing the luggage. By linking a computer with a certain communication protocol to the office side, it is possible to manage packages such as “Which vehicle is carrying emergency packages” and “When will it be delivered?” At the same time, the time required for the collection and delivery business can be shortened, thereby reducing labor costs.

Such diversification of communication between electric vehicles and charging stations is not limited to collection / delivery trucks, and if it reaches an environment where the networking of charging stations is progressing, it will surely be applied to personal vehicles. For example, if a personal car is charged at a charging station in a parking lot for shopping or eating, a communication system is expected such that the charge is automatically withdrawn from the bank.
However, in contrast to Table 1, which is an indispensable information exchange for quick charging, the information in Tables 2 and 3 is merely a pursuit of convenience on the side of using the car, and the purpose dimension is different from Table 1. You must also pay attention to this. It is not a good idea to interrupt the in-vehicle CAN communication with other-dimensional information such as vehicle operation management and baggage information because it can be a cause of malfunction of the in-vehicle CAN communication. That is, the data necessary for quick charging and other data are not processed by the same protocol, and the multiplex communication between the electric vehicle and the desk lamp such as the data communication shown in Tables 2 and 3 is different. Should be handled by the protocol.

<Problem 4>
The next problem is the structure of the connector for connecting the charging cable.
Since existing connectors are mechanically complex and are frequently inserted and removed, they are parts that are prone to mechanical failure and are expensive parts. Moreover, it should be improved so that the detaching operation becomes easier.
As a connector that can be easily attached and detached, there is a three-pole plug for AC three-phase for connecting a power source of a general electric machine. Although these three-pole plugs have a large current value, they are slightly larger than ordinary home appliance plugs. However, the structure is simple, there are few failures, and it is easy to attach / detach to / from an outlet. As described above, it is desired that the cable can be attached and detached by a simple operation such as plugging / unplugging the plug of a general household appliance during the quick charging.
In order to easily insert the plug into the outlet, it is natural that the number of poles of the plug should be small, such as three poles rather than four.

As described above, the issues sought in rapid charging of electric vehicles are
(1) To drastically reduce the contact failure rate of communication lines,
(2) Do not link in-vehicle CAN communication directly to external equipment.
(3) Diversify communication lines by performing multiplex communication;
(4) Simplify the structure of the cable connection part (connector) to reduce failure and simplify attachment / detachment.
It is.

The present invention provides a power supply provided in a charging stand while transmitting a control signal and an information signal for controlling a charging state between a first control unit provided in the charging stand and a second control unit provided in the electric vehicle. The present invention relates to a method for charging a secondary battery by supplying DC power from a source to a secondary battery provided in an electric vehicle.
The DC power is supplied through a positive charging line and a negative charging line connecting the power supply source and the secondary battery.
In addition, the transmission of the control signal and the information signal includes a first communication line connecting the first control unit and the second control unit, a second communication line using any one of the plus side charging line and the minus side charging line, , Done through.

In the charging method of the present invention, if the first control unit includes the first analog modem and the second control unit includes the second analog modem, the control signal and the information signal are the first analog modem and the second analog modem. It is preferable that the data is transmitted between the first control unit and the second control unit via an analog modem.
By doing so, it is possible to enable normal communication even if there is a resistance that causes attenuation of the control signal in the communication line.

In the charging method according to the present invention, the first control unit includes a first analog modem and a first encoding circuit unit, and the second control unit includes a second analog modem and a second encoding circuit unit. The signal and the information signal are mutually transmitted between the first control unit and the second control unit via the first analog modem and the first encoding circuit unit and the second analog modem and the second encoding circuit unit. Preferably it is transmitted.
By doing so, the first control unit and the second control unit are mutually transmitted with an alternating current signal converted into a fixed protocol (communication protocol) in cooperation with the encoding circuit and the analog modem, thereby causing the CAN signal. Can be isolated.

  In the charging method of the present invention, a resistor and a coupling capacitor can be provided in the first communication line and the second communication line. By doing so, the analog modem can be protected.

  Furthermore, in the charging method of the present invention, it is preferable that transmission of the control signal and the information signal between the first control unit and the second control unit is performed by multiplex communication using frequency division.

  Areas where coastal areas and volcanic gases are generated because the probability of communication failure due to poor contact at the connector part can be dramatically reduced to 1 / 100,000 or less by performing communication using an analog modem. Can greatly extend the life of replacement parts for connectors. Therefore, charging stations can be deployed at certain locations throughout the country, which can play a major role in building infrastructure that is indispensable for the popularization of electric vehicles.

  By adopting an information communication technique using an analog modem, in-vehicle CAN communication can be isolated.

  In addition, multiplex communication in which information communication related to quick charging and other information communication are operated by different protocols is possible, and diversification of information communication is achieved. For example, if a quick charger side is networked in the case of a collection / delivery business, it is easy to grasp the position of a package and a delivery time prediction as well as management of a collection / delivery vehicle, thereby improving convenience.

  Furthermore, since the number of contact portions is changed from four to three by making the one-side DC superimposition of the communication signal, it is possible to plug in with a shape similar to the AC three-phase three-pole plug that is easy to handle and has few failures.

  Even if a resistance of about 12 KΩ exists in the communication line, communication is not hindered. Therefore, the contact point of the communication line can be sufficiently made of a material similar to an AC power outlet and plug.

It is a figure for demonstrating the outline | summary of the quick charge in an electric vehicle. It is a figure in the case of connecting the communication line and charge line in quick charge with a separate connector. It is a figure in the case of connecting the communication line and charge line in quick charge with one connector. It is a schematic diagram of DC superposition. It is a circuit diagram showing only the direct current part in quick charge. It is a virtual diagram for demonstrating that an alternating current cannot be superimposed on a charging circuit. It is a figure for the proposal explanation which superimposes an alternating current only on the plus side line of a charging circuit. It is a figure for explanation which superimposes exchange only on the minus side line of a charging circuit. It is the figure explaining utilizing the general industrial information transmission apparatus in the case of performing unidirectional, and superimposing the signal of an analog modem on the single line of a charging circuit. It is a figure for demonstrating that communication is possible even if there is resistance in a communication line. It is a figure explaining maintaining the safety | security of a one-line direct current | flow superimposition. It is a systematic diagram for demonstrating the system form which summarized this proposal.

Hereinafter, the present invention will be described in detail based on embodiments.
<Corresponding to Issue 4>
First, we propose a method for simplifying cable insertion and removal. The most effective method for reducing contact failure such as increase in contact resistance is to eliminate the contact portion, and it goes without saying that contact failure does not occur if the communication line can be eliminated. There is a DC superposition method as an existing technique known as a method of eliminating a communication line. FIG. 4 is a circuit in which DC power for driving the remote load 17 at the point A is supplied from the remote load power supply unit 18 at the point B, utilizing the nature of the impedance of the coil and the capacitor to supply an AC signal to the DC circuit. It is a circuit diagram of a general direct current superposition method for superposition.

Although the impedance of the coil is obtained by equation (1) and the impedance of the capacitor is obtained by equation (2), it can be seen that the impedance of the coil is proportional to the frequency and the impedance of the capacitor is inversely proportional to the frequency.
Coil impedance Z _L = jωL (1)
Capacitor impedance Z _C = 1 / JωC (2)
ω: 2πf (where π is a circular ratio, f is a frequency), J is an imaginary number For example, suppose that the choke coil L3 in FIG. 4 has an inductance of 1H (Henry). When the impedance of the choke coil L3 when passing the frequency of 1 KHz through the choke coil L3 is applied to the equation (1), the value becomes a large value as in the equation (3) and the AC signal (control signal) generated from the AC transmitter 19 is obtained. It is possible to suppress the penetration of the remote load power supply unit 18 into the DC circuit as much as possible.
Z _L3 = ωL = 2 × 3.14 × (1 × 10 ³ ) × 1 = 6.28 KΩ (3)

For example, assume that the coupling capacitor C3 in FIG. 4 has a capacitance of 1 μF (microfarad). When the impedance of the coupling capacitor C3 when the frequency of 1 KHz (kilohertz) is allowed to pass through the coupling capacitor C3 is applied to the equation (2), the impedance becomes a relatively small value as in the equation (4), and the AC transmitter 19 Therefore, the AC signal emitted from can easily enter the DC power supply line 21 through the coupling capacitor.
_{Z C3 = 1 / ωC = 1} /2 × 3.14 × (1 × 10 3) × (1 × 10 -6) = about 159Ω ... (4)
Since the capacitor does not allow direct current to pass through, the direct current does not pass through the capacitor and does not affect the AC transmitter 19 or the AC receiver 20.

For this reason, in FIG. 4, the AC signal sent from the AC transmitter 19 at the point B easily passes through the coupling capacitors C3, C4, C1, and C2 having a relatively low impedance and reaches the AC receiver 20 at the point A. However, since the impedance of the choke coils L3, L4, L1, and L2 is relatively large, the AC signal sent from the AC transmitter 19 is blocked by the choke coils L3, L4, L1, and L2, and the remote load power is supplied. The influence on the unit 18 and the remote load 17 is extremely small and does not interfere with the DC circuit.
In FIG. 4, if the AC transmitter at point B is moved to point A, the AC receiver at point A is moved to point B, and the transmitter and receiver are replaced, the AC signal transmitted by the AC transmitter at point A is sent. Can be received by the AC receiver at point B.

On the other hand, FIG. 5 is a circuit diagram showing only the DC part of charging. FIG. 6 shows coupling capacitors C3, C4, C1, C2 and choke coils L3, L4, L1, L2 based on the same concept as in FIG. 4 in order to superimpose an AC signal on the DC circuit to be charged in FIG. It is the deployed virtual circuit diagram. In FIG. 6, the AC signal sent from the AC transmitter 19 on the charging stand side seems to be able to be transmitted to the AC receiver 20 on the electric vehicle side. It cannot be superimposed on a DC circuit. This is because the choke coil must block the passage of the AC signal, which is the mission of the choke coil, but it must have a certain impedance to block the AC signal. In order to increase the impedance of the coil, it is necessary to increase the number of turns of the coil. The increase in the number of turns of the coil is because the direct current resistance increases and the impedance of the battery is zero. For example, in FIG. 6, if the DC resistance of each of the choke coils L1 to L4 is 1Ω (ohms), the total DC resistance value of the choke coils L1 to L4 is 1Ω × 4 = 4Ω. When an attempt is made to perform rapid charging with 100 A flowing, the DC power consumed by the DC resistances of the choke coils L1 to L4 is expressed by equation (5) and consumes enormous power.
Power consumption of choke coil P = I ² R = 100 ² × 4 = 40K (VA) (5)
VA: DC power (equivalent to AC wattage (W))
That is, when charging the secondary battery 1 from the power supply source 2 with 50 KVA, the power supply source 2 has an energy of 90 KVA added by 40 VA, which is wasted power consumed by the choke coils L1 to L4 existing in the charging path. It will be necessary to twist. Assuming that the choke coils L1 to L4 are eliminated in order to avoid wasteful power consumption by the choke coil, the AC signal sent from the AC transmitter 19 enters the charging lines 9 to 10 via the coupling capacitors C3 and C4. Although the impedance of the secondary battery 1 is zero (it is a short state when viewed from the AC), the AC signal disappears in the secondary battery 1. That is, even if a coupling capacitor or choke coil is provided in a charging circuit through which a large current flows, it is impossible to transmit information by superimposing alternating current on the charging circuit.

Therefore, in this embodiment, the circuit shown in FIG. 7 is proposed. In order to perform communication, normally, two communication lines 7 and 8 are required as shown in FIGS. 2 and 3. Of these two communication lines, for example, the communication line 7 (the first line on one side of the communication line) 1 communication line) and the plus-side charging line 9 (second communication line) are used for communication. In other words, this is a one-line DC superimposition method in which an AC signal is allowed to enter only the plus side line of the DC circuit. However, since the communication AC signal also flows through the positive charging line 9, the number of contact points of the AC signal is two in total: the connector CN 1 that contacts the communication line 7 and the connector CN 2 of the positive charging line 9. The number of contact points of the communication signal is not reduced.
However, since the communication line can be halved, the number of contact portions can be reduced from four to three.
Therefore, it is possible to reduce the failure at the time of connecting the charging cable, which is one of the problems to be solved, and to easily attach and detach the plug to the outlet (problem 4).
Note that FIG. 8 performs communication using the communication line 7 and the minus-side charging line 10, but it is natural that the function is the same as that of FIG.

<Corresponding to Issue 2>
Next, a method for not directly linking in-vehicle CAN communication with an external charging station will be described.
One of the current infrastructures is a telephone line. The original idea of a telephone line is an electric line that attempts to convert a human voice into an electrical signal and send it to a distant place. Using this pair of (two wires) telephone lines, a digital signal is sent to a far place. There are many existing remote monitoring and control devices (sometimes referred to as information transmission devices) for general industrial use. Such an information transmission device mainly includes an interface unit that captures or retrieves a large amount of data from an external computer, etc., and an encoding circuit unit that tests whether there is an error in a signal transmitted or received according to a specified transmission protocol. And an analog modem that converts a digital signal into an analog signal. The task of the analog modem is to transmit information to a distant place using an AC signal having a frequency of 0.3 to 3.4 KHz, which is a frequency (audible frequency) that can be heard by the human ear. In such an information transmission system, the DC micro voltage circuit is completely isolated by the encoding circuit unit and the analog modem.
FIG. 9 includes a transmission analog modem 23 for modulating and transmitting a signal, a reception analog modem 29 for demodulating a reception signal, encoding circuit units (enc) 35 and 36, and interfaces (IF) 41 and 42. 1 shows an information transmission circuit. By utilizing such a communication method to communicate between the CAN signal in the electric vehicle and the charging station, it is possible to isolate the CAN communication in the electric vehicle without linking it directly to the charging station. It becomes.

<Corresponding to Issue 1>
Next, based on the above proposals, a method that enables communication even when the resistance of the contact point of the communication line increases when connecting an electric vehicle and a charging stand during quick charging, which is the most important issue. explain.
In FIG. 9, a digital signal that the microcomputer board 4 on the charging stand side wants to transmit is transmitted to the transmission analog modem 23 via the interface 41 and the encoding circuit unit 35, and the transmission analog modem 23 generates this signal by the microcomputer board 4. The digital information is modulated to an audible frequency and transmitted to the receiving analog modem 29.
The reception analog modem 29 captures and demodulates the audible frequency modulation signal from the transmission analog modem 23, and the demodulated signal is passed to the interface 42 via the encoding circuit unit 36. The interface 42 can convert this into a CAN signal and transmit it to the electronic control unit 3 for managing the secondary battery 1 in the vehicle.
As described in the previous section, there is a general industrial remote monitoring and control device (sometimes referred to as an information transmission device) as a method of transmitting information to a long distance via a telephone line with such a configuration. There is a regulation (JEM-1318) established by the Japan Electrical Manufacturers' Association in the remote monitoring control device. For example, when communication is performed with an analog modem that complies with the regulations of JEM-1318, normal communication is possible even if the resistance value in the transmission path between the charging station and the electric vehicle is about 18 KΩ. In other words, the purpose of analog modems is to transmit normally to a distance of several kilometers to several tens of kilometers using a telephone line (transmission path), and to transmit normally to a distance of about 10 km using a telephone line (transmission path). The purpose of JEM-1318 was to assume that electrical energy transmitted through a telephone line (transmission line) is attenuated. By reversely using an analog modem conforming to JEM-1318 for transmission over a very short distance of several meters, even if the communication line resistance between the charging station and the electric vehicle is about 18 KΩ, communication is possible without any problem.

Here, the outline of analog modem transmission theory will be described.
The impedance series in the transmission of the analog modem is assumed to be 600 Ω of the audio system, the signal level is expressed in decibels (db), and the signal level reference is 0 (db). Reference 0db is expressed by equation (6) because the power value of 1 mW is defined as an absolute value in the state of impedance 600Ω. Equation (7) and Equation (8) are the voltage value and current value at 0 (db) derived from Ohm's law from Equation (6), and the voltage value of 0 db in the 600Ω system is 0.775 V and the current value Is found to be 1.2916 mA.
The ^{0db, P = V 2 / R} = V 2 / 600Ω = 1 × 10 -3 W = 1mW ... (6)
V _0db = (1 × 10 ⁻³ × 0.6) ^1/2 = 0.775 V (7)
I _0db = V / R = 0.775 / 600 = 1.2916 mA (8)

Furthermore, equation (9) is used as a method for conveniently calculating the transmission level power amount in the analog modem.
10 · log ₁₀ A = X [db] (9)
A: Multiple to reference value X: Decibel value

On the other hand, there is a remote monitoring control device as a typical existing information transmission device that effectively uses an analog modem. Remote monitoring and control devices are widely used in power company power station monitoring and control, national river dam monitoring and control, and municipal waterworks, etc. A unified standard established by the Japan Electrical Manufacturers' Association regarding these remote monitoring and control devices As JEM-1318. Regarding the analog modem of JEM-1318, “Signal transmission section” is defined as follows.
Transmission level 0dbm / ch
Reception level 0 to -20db / ch
Line disconnection detection Operates at 10-15db from standard incoming calls
ch: Channel
Line disconnection detection: A value that should be regarded as a line disconnection even if the modem has reception capability. That is, the transmission output of the analog modem built in the remote monitoring control device is 0 (db), and the reception of the analog modem receiver is received. In the case of a communication transmission line that has reached a level of −20 db, it means that normal reception is required even at −30 to −35 db, which is 10 to 15 db lower than the standard reception level at −20 db on the receiving side. ing.
By the way, a 0.4φ local cable, which is a general telephone line, has an attenuation of about 2 db at 1 km. Accordingly, it is assumed that there is a remote monitoring and control apparatus that sets the transmission level to 0 db. If this is transmitted by a 0.4φ cable, the reception level of the remote monitoring control apparatus 10 km away is about −20 db.
It can be understood from the equation (9) that −20 db is a power value of 1/100 of 0 db. When this is applied to Equation (6), Equation (7) and Equation (8), the power value reaching the analog modem receiver 20 km ahead is 0.01 mW of Equation (10), and the voltage value is Equation (11). ) Of 0.0775V, and the current flowing through the analog modem receiver is 0.12916 mA of equation (12).
−20 db means P = V ² /600Ω=0.01 mW (10)
V- _20db = 0.01 * 10 < ^-3 > * 600 = 0.0775V (11)
I- _20db = 0.0775V / 600Ω = 0.129mA (12)
Since -30db, which is supposed to be normally received, is a power value of 1/1000 from Equation (9), the power value is 0.001 mW of Equation (13), and the voltage is Equation (14). Of 0.0245 V, and the current is 0.0408 mA of equation (15).
−30 db is P = V ² /600Ω=0.001 mW (13)
^{_{V -30db = 0.001 × 10 -3 ×}} 600 = 0.0245V ... (14)
_{I -30db = 0.0245V / 600Ω = 0.0408mA} ... (15)

FIG. 10 is a circuit diagram in which a resistor Rt is inserted into the circuit of FIG. 9 to attenuate the level at which the AC modulation signal transmitted from the transmitting analog modem 23 arrives at the receiving analog modem 29. If the transmission level of the transmission analog modem 23 is 0 db and the arrival level of the reception analog modem 29 is −20 db due to the resistor Rt, the voltage of the transmission analog modem 23 is 0.775 from the equation (7). Since the voltage of the reception analog modem 29 is 0.0775 V from the equation (11), the insertion of Rt into the communication circuit causes the voltage of 0.697 V to drop at the resistor Rt as shown by the equation (16). become. Therefore, when the value of Rt is obtained according to Ohm's law, equation (17) is obtained, and the resistance value of Rt that is attenuated to −20 db is 5.4 KΩ.
Rt voltage drop V _Rt = 0.775V-0.0775V = 0.6975V (16)
Rt = V / I = 0.6975 / 0.129 × 10 ⁻³ = 5.4 KΩ (17)

If the level of the modulation signal transmitted from the transmission analog modem 23 is 0 db and the arrival level of the reception analog modem 29 is −30 db due to the resistor Rt, the voltage of the transmission analog modem 23 is expressed by the equation (7). Since the voltage of the reception analog modem 29 is 0.0245V from the equation (14), the insertion of Rt into the communication circuit results in the resistance Rt being 0.7505V as shown in the equation (18). The voltage will be dropped. Therefore, when the value of Rt is obtained according to Ohm's law, equation (19) is obtained, and the resistance value of Rt when attenuated to −30 db is 18.39 KΩ.
Voltage drop of _Rt V _Rt = 0.775V-0.0245V = 0.7505V (18)
Rt = V / I = 0.7505 / 0.0408 × 10 ⁻³ = 18.39 KΩ (19)

Further, in FIG. 10, there is an accident in which a charging voltage of about 500 V DC is applied between the communication line 7 and the plus side charging line 9 which are communication transmission paths of the transmitting analog modem 23 and the receiving analog modem 29 for some reason. I can't say I don't. When this occurs, the transmission analog modem 23 and the reception analog modem 29 are damaged, and communication becomes impossible.
Therefore, in this embodiment, coupling capacitors C1 to C4 that do not allow direct current to pass as shown in FIG. 11 are provided, and the Rt value is 5.4 KΩ when the analog modem is attenuated to the standard reception level of −20 db. The resistors R1 to R4 having a 1/4 value of 1.35 KΩ are distributed to protect the transmitting analog modem 23 and the receiving analog modem 29 more safely. If the frequency of the analog modem is 1 KHz in this state, the value of Rt corresponding to a sufficiently receivable level of −30 db is 18.39 KΩ, so the total value of R1 to R4 corresponding to Rt from 18.39 KΩ ( 1.35 KΩ × 4 = 5.4 KΩ) and a resistance of 12.35 KΩ, which is a value obtained by subtracting the impedances of the coupling capacitors C1 to C4 (159Ω × 4 = 636Ω), are present in the communication transmission line. It will be good. This means that communication is sufficiently possible even if the total value of the contact resistances of the connector CN1 and the connector CN2 which are contact points of the communication signal is 12.35 KΩ.
That is, since the conventional communication method at the time of charging from the charging station was a DC weak voltage circuit, the presence or absence of an increase in contact resistance value (0.1Ω or less) was a major obstacle, but conforming to JEM-1318 By adopting an analog modem system, there is no problem even if 12.35 KΩ, which is 100,000 times more than 0.1Ω, is present in the communication transmission line. In other words, in the maintenance and inspection of the charging station, it is sometimes necessary to replace the connector part of the communication line. However, if it is assumed that the increase in the resistance value of the contact part is proportional to time, the connector part is replaced. It is possible to extend the life by about 100,000 times.
In addition, unlike the normal two-wire communication circuit, the one-line DC superimposition in FIG. 11 has a slightly high failure rate when the charging DC 500V is applied between the communication line 7 and the plus-side charging line 9, that is, the communication circuit. Therefore, the transmitting analog modem 23, the receiving analog modem 29, the coupling capacitors C1 to C4, and the dispersion resistors R1 to R4 are selected and arranged with parts that are not damaged by a voltage of about DC500V, and are temporarily installed in a failed charging stand. It is desirable to ensure safety so that even if the charging cable is connected, it does not affect the communication equipment of the electric vehicle.

<Corresponding to Issue 3>
Next, a multiplex communication method will be described. For example, in JEM-1318, the following is also described in “Signal transmission section”.
JEM-1318 “Signal transmission” At a transmission rate of 200 bits / second, the following conditions are assumed.
Frequency array used: 800 + 400 × (n−1) Hz (n = 1-6)
The meaning here is that when transmitting at a speed of 200 bits / second (bps), an audible frequency of 0.3 to 3.4 KHz is divided into six channels as shown below. It is. In other words, when performing multiplex communication, first, the channel that communicates at a frequency of 800 Hz is channel 1 (cH1), and the channel that communicates using a frequency of 1200 Hz above 400 Hz is channel 2 (cH2). Six channels are formed. In addition, it is said that a band pass filter capable of passing only the corresponding frequency should be added to the analog modem to extract the channel of the corresponding frequency and multiplex communication should be performed.
Channel frequency at 200 bps Channel (cH1): 800 Hz
Channel (cH2): 1200Hz
Channel (cH3): 1600Hz
Channel (cH4): 2000Hz
Channel (cH5): 2400Hz
Channel (cH6): 2800Hz

FIG. 12 is a diagram when multiplex communication is performed at 200 bps in accordance with JEM-1318 in an electric vehicle and a charging station.
For example, channel 5 (ch5) and channel 6 (ch6) are used to process information necessary for the rapid charging described with reference to Table 1 by bidirectional communication. Using channel 1 (ch1) and channel 2 (ch2), for example, two-way communication of information necessary for vehicle operation management described with reference to Table 2 is performed, and channel 3 (ch3) and channel 4 (ch4) are used. The two-way communication of information necessary for the package management described with reference to Table 3 can be performed.
Reference numerals 35 to 40 denote encoding circuit sections of the respective channels, reference numerals 41 to 46 denote interfaces of the respective channels, and reference numerals 47 to 50 denote computers other than those for rapid power reception of the respective channels.

It should be noted that as described above, in the rapid charging of an electric vehicle, the management of charging voltage and charging current, so-called “process for strictly managing constant current / constant voltage charging” is very important. In other words, charging with a constant current until the cell voltage of the battery becomes constant, and switching to the constant voltage at the moment when the cell voltage of the battery becomes constant prevents the heating accident due to charging and extends the life of the battery. It must be done. When switching the charge setting value, there is a concern about transmission delay in bidirectional communication at a transmission rate of 200 bps. However, even if quick charge management control is performed at a transmission rate of 200 bps in accordance with a method compliant with JEM-1318, it can be performed in 0.5 seconds or less, so there is almost no influence due to a transmission delay. If necessary, it is possible to eliminate the anxiety of rapid charge management by executing software processing in which a mechanism such as a predictive control signal is added to the charge control signal.
In addition, the remote monitoring and control apparatus defined by JEM-1318 is intended to monitor and control power plants and dams using a telephone line, and therefore needs to withstand various obstacles. For this reason, it is a strong and large-sized device with a variety of rigorous equipment, but if it is specialized for quick charging of electric vehicles, the parts (equipment) that can be excluded from existing remote monitoring and control devices Very many. Therefore, even if a bi-directional communication device including an isolation, an encoding circuit unit, and an analog modem according to JEM-1318 only in the essential part is manufactured, according to the recent electronic device manufacturing technology, downsizing is not possible. It is extremely easy to supply at low cost by mass production. Naturally, the production of an interface unit (IF) for converting CAN communication is also easy.

1: secondary battery, 2: power supply source, 3: electronic control unit (ECU),
4: microcomputer board (CPU), 5: communication cable, 6: charging cable,
7-8: Communication line, 9: Positive side charging line, 10: Negative side charging line,
11-12: Communication connector, 13-14: Charging connector, 15-16: Composite connector for communication and charging, 17: Remote load, 18: Remote load power supply unit,
19: AC transmitter, 20: AC receiver, 21-22: DC power line,
23 to 28: analog modem for transmission, 29 to 34: analog modem for reception,
35-40: Coding circuit part, 41-46 interface,
47-50: Computers other than for rapid power reception,
C1 to C4: coupling capacitors, L1 to L4: choke coils,
CN1 to CN3: connector (connection portion), Rt: resistance,
R1 to R4: Dispersion resistance

The present invention provides a power supply provided in a charging stand while transmitting a control signal and an information signal for controlling a charging state between a first control unit provided in the charging stand and a second control unit provided in the electric vehicle. The present invention relates to a method for charging a secondary battery by supplying DC power from a source to a secondary battery provided in an electric vehicle.
The DC power is supplied through a positive charging line and a negative charging line connecting the power supply source and the secondary battery.
In addition, the transmission of the control signal and the information signal includes a first communication line connecting the first control unit and the second control unit, a second communication line using any one of the plus side charging line and the minus side charging line, , Done through.
Accordingly, the power supply source includes the first communication line, one of the positive charging line and the negative charging line used for the second communication line, the first control unit and the second control unit, and A closed circuit that does not include the secondary battery is formed.

Claims (5)

While transmitting the control signal and the information signal for controlling the state of charging between the first control unit provided in the charging stand and the second control unit provided in the electric vehicle, the power supply source provided in the charging stand A method of charging the secondary battery by supplying direct current power to a secondary battery provided in an electric vehicle,
The supply of DC power is
It is performed via a positive charging line and a negative charging line connecting the power supply source and the secondary battery,
Transmission of the control signal and the information signal is as follows:
A first communication line connecting the first control unit and the second control unit, and a second communication line using one of the positive side charging line and the negative side charging line.
A charging method characterized by that. The first control unit includes a first analog modem;
The second control unit includes a second analog modem;
The control signal and the information signal are mutually transmitted between the first control unit and the second control unit via the first analog modem and the second analog modem.
The charging method according to claim 1. The first control unit includes a first analog modem and a first encoding circuit unit,
The second control unit includes a second analog modem and a second encoding circuit unit,
The control signal and the information signal are transmitted to the first control unit and the first encoding circuit unit via the first analog modem and the first encoding circuit unit, and the second analog modem and the second encoding circuit unit, respectively. Are transmitted between two control units,
The charging method according to claim 1. A resistor and a coupling capacitor are provided in the first communication line and the second communication line.
The charging method according to any one of claims 1 to 3. Transmission of the control signal and the information signal between the first control unit and the second control unit is performed by multiplex communication by frequency division.
The charging method according to any one of claims 1 to 4.

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