Abstract:
An electronic control unit and on-vehicle devices are each connected to a common power supply line via a communication module. The power supply line has positive and negative electrode side core wires. Each communication module is provided with a connection unit and a signal processor. The connection unit has a transformer having two pairs of input-output terminals, a first pair of which is respectively connected to the positive and negative electrode side core wires. The signal processor is connected to the second pair of input-output terminals of the transformer. The signal processor converts analog signals from the power supply line and outputted from the second pair of input-output terminals, converts externally inputted digital signals into analog signals and transmits the converted analog signals to the second pair of input-output terminals so that the converted analog signals are superimposed on the power supply line voltage.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application relates to and incorporates by reference Japanese Patent application No. 2009-104208 filed on Apr. 22, 2009. 
     BACKGROUND 
     1. Technical Field 
     The present application relates to a system for performing communication between devices mounted in vehicle, and in particular, the system that uses a power line to perform the communication between an ECU (Electronic Control Unit) and each of on-vehicle devices such as an inverter, a compressor etc., which are mounted in vehicles including a hybrid vehicle and an electric vehicle. 
     The present application also relates to a communication module incorporated in the above system. 
     2. Description of the Related Art 
     In recent vehicles such as hybrid vehicles and electric vehicles, it is frequently required to reliably perform high-speed communication among on-vehicle devices for controlling behaviors of the vehicle. 
     Conventionally, when communicating between ECU and on-vehicle devices in a hybrid vehicle, the communication was performed by connecting target devices by communication lines of exclusive use. A composition example of the system for performing communication between devices mounted in vehicle is shown in  FIG. 1 . The system  10  for performing communication between devices mounted in vehicle shown in  FIG. 1  includes an A/C-ECU  11  which performs air-conditioner control as ECU, an HV-ECU  13  which is connected to the A/C-ECU  11  by CAN (Controller Area Network)—through the GW (Gateway) device  12  which is connected by LIN (Local Interconnect Network) to the A/C-ECU  11  and performs signal conversion and an E/G-ECU  14  which performs engine control. However, the HV-ECU  13  performs the motor control for a hybrid vehicle, etc. 
     The system  10  for performing communication further includes a battery unit  21  which has a high-voltage battery  21   a  and supervises battery voltage of the high-voltage battery  21   a , a DC/DC converter  22  which converts the high voltage of the high-voltage battery  21   a  in the battery unit  21  into 12V of the low voltage, a driving inverter  23  which performs drive control of a motor for hybrid, an electric compressor  24  which compresses a coolant of an air-conditioner, a pump  25 , such as a cooling-water circulation pump and an oil pump and a fan  26 , such as a battery cooling fan and a radiator fan. These on-vehicle devices  21 - 26  are connected by power supply line  27  shown with solid line. 
     Meanwhile, the HV-ECU  13  is connected to the battery unit  21 , the DC/DC converter  22 , the driving inverter  23 , the electric compressor  24  and the pump  25  by communication lines  28  shown with dashed lines, and the E/G-ECU  14  and the fan  26  are also connected by communication lines  28 , Thereby required communication is performed respectively. 
     An example of such conventional art of communication in a vehicle is disclosed, for example, in a Japanese Patent Application Laid-Open Publication No. 2007-230520. 
     However, in the above-mentioned conventional system for performing communication between devices mounted in vehicle, in order for ECU and each on-vehicle device to perform predetermined communication, communication lines of exclusive use are required. For this reason, there is a problem that troublesome work, such as drag, connection, etc. of communication lines, occurs, and as a result, work cost increases. 
     SUMMARY OF THE INVENTION 
     The present exemplary embodiment has been made in view of such conventional problems, and thus, it is an object of the present exemplary embodiment to provide a system for performing communication between devices mounted in vehicle which can reduce work cost of the wiring for predetermined communication between an ECU and each on-vehicle device. 
     In order to achieve the aforementioned object, the present exemplary embodiment provides a system for performing communication between devices mounted in vehicle which enables communication between an electronic control unit and different kinds of on-vehicle devices including a power line and a to communication module. The electronic control unit and each of the on-vehicle devices is connected to the power line, the power line is connected to a battery having a negative electrode and a positive electrode for power supply to the power line, the power line has a positive electrode side core wire connected to a positive electrode of the battery and a negative electrode side core wire connected to the negative electrode of the battery. The communication module is included in the electronic control unit and each of the on-vehicle devices, the communication module includes a connection unit and a signal processor. The connection unit has a transformer having two input-output terminals, wherein each of the positive electrode side core wire and the negative electrode side core wire is connected to one end of one of the input-output terminals of the transformer through a capacitor. The signal processor is connected to the other input-output terminal of the transformer, adapted to convert analog signals branched in the connection unit from voltage signals of the power supply line and outputted from the other input-output terminal, adapted to convert externally inputted digital signals into analog signals and adapted to transmit the converted analog signals to the other input-output terminal of the transformer so that the converted analog signals is allowed to be superimposed on the voltage signals of the power supply line in the connection unit. 
     In this configuration, the devices for vehicles include both the electronic control unit and the on-vehicle devices, and communication between the electronic control unit and different kinds of the on-vehicle devices includes not only communication between the electronic control unit and one of the on-vehicle devices but also communication between one of the on-vehicle devices and another one. 
     According to this configuration, in the electronic control unit and different kinds of the on-vehicle devices, the analog signals converted in the signal processor of the communication module are superimposed on the voltage signals of the power supply line in the connection unit, and, the analog signals superimposed on the voltage signals of the power supply line are branched in the connection unit then processed in the signal processor. If the analog signals are used as signals for communication, communication between the electronic control unit and different kinds of the on-vehicle devices may be possible using the power supply line which supplies power to the electronic control unit and different kinds of the on-vehicle devices. Therefore, since the conventional communication lines of exclusive use for communicating between the electronic control unit and different kinds of the on-vehicle devices becomes unnecessary, troublesome work, such as drag, connection, etc. of communication lines, becomes almost unnecessary whereby the work cost can be reduced sharply. Moreover, since the communication lines of exclusive use themselves are also unnecessary, material cost is also reducible. 
     It is preferable that the power supply line may have a grounded shield part, made of electrical conducting material, which insulatively covers the positive electrode side core wire, and the one input-output terminal of the transformer of the connection unit is connected to the shield part and the negative electrode side core wire of the power supply line through the capacitor. 
     According to this configuration, the analog signals for communication superimposed on the voltage signals are transmitted between the shield part and the negative electrode side core wire. However, no noise is generated in the shield part since the shield part is grounded, whereby noise can be removed from the analog signals transmitted through the power supply line. 
     It is also preferable that the power supply line may have a grounded shield part, made of electrical conducting material, in which the positive electrode side core wire and the negative electrode side core wire are paired up, and the shield part covers both the positive electrode side core wire and the negative electrode side core wire with insulating material, and the one input-output terminal of the transformer is connected to the shield part and the positive electrode side core wire of the power supply line through the capacitors. 
     As explained above, according to the present exemplary embodiment, a system for performing communication between devices mounted in vehicle which can reduce work cost of the wiring for predetermined communication between an ECU and each on-vehicle device can be provided. 
     According to a second aspect of the present exemplary embodiment, there is provided a communication module incorporated in a system for performing communication between devices mounted in vehicle, wherein the system enables communication between an electronic control unit and different kinds of on-vehicle devices, wherein the communication module is included in the electronic control unit and each of the on-vehicle devices, and the communication module includes a connection unit and a signal processor the connection unit having a transformer having two input-output terminals, wherein each of the positive electrode side core wire and the negative electrode side core wire is connected to one end of one of the input-output terminals of the transformer through a capacitor. The signal processor connected to the other input-output terminal of the transformer, adapted to convert analog signals branched in the connection unit from voltage signals of the power supply line and outputted from the other input-output terminal, adapted to convert externally inputted digital signals into analog signals and adapted to transmit the converted analog signals to the other input-output terminal of the transformer so that the converted analog signals is allowed to be superimposed on the voltage signals of the power supply line in the connection unit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the accompanying drawings: 
         FIG. 1  is a block diagram showing the composition of the conventional system for performing communication between devices mounted in vehicle. 
         FIG. 2  is a block diagram showing the composition of the system for performing communication between devices mounted in vehicle according to an preferred embodiment of the present invention; 
         FIG. 3  is a block diagram showing the composition of the communication module of the system for performing communication between devices mounted in vehicle of the preferred embodiment; 
         FIG. 4  shows a connection composition of the connection unit to the power supply line in the system for performing communication between devices mounted in vehicle of the preferred embodiment; and 
         FIG. 5  shows another connection composition of the connection unit to the power supply line in the system for performing communication between devices mounted in vehicle of the preferred embodiment. 
         FIG. 6  shows an example of further connection composition of the connection unit to the power supply line in the system for performing communication between devices mounted in vehicle of the preferred embodiment. 
         FIG. 7  shows an example of further connection composition of the connection unit to the power supply line in the system for performing communication between devices mounted in vehicle of the preferred embodiment. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Hereinafter, a preferred embodiment of the present invention will be described referring to the drawings. In this description, the same reference symbols as those in  FIG. 1  will be given in all drawings of this specification—for the sake of simplified explanations. 
       FIG. 2  is a block diagram showing a composition of the system for performing communication between devices mounted in vehicle according to the preferred embodiment of the present invention. 
     A system  30  for performing communication between devices mounted in vehicle shown in  FIG. 2  is mounted for example, in a hybrid vehicle. The system  30  for performing communication between devices mounted in vehicle includes, as ECUs, an A/C-ECU  11  which controls an air-conditioner, a HV-ECU  31  connected by CAN to the A/C-ECU  11  through a GW device  12  which is connected to the A/C-ECU  11  by LIN and converts signals, and an E/G-ECU  14  which is connected to the HV-ECU  31  by CAN and controls an engine. The HV-ECU  31  and on-vehicle devices  41  to  46  are wired for communication by power supply line  52 . 
     As the on-vehicle devices  41  to  46 , the system  30  for performing communication between devices mounted in vehicle further includes a battery unit  41  which has a high-voltage battery  41   a  and supervises battery voltage of the high-voltage battery  41   a , a DC/DC converter  42  which converts high voltage of the high-voltage battery  41   a  in the battery unit  41  into 12V of low voltage, a driving inverter  43  which performs drive control of a motor for hybrid, an electric compressor  44  which compresses a coolant of the air-conditioner, a pump  45 , such as a cooling-water circulation pump and an oil pump, and a fan  46 , such as a battery cooling fan and a radiator fan. 
     These on-vehicle devices  41  to  46  and the HV-ECU  31  are associated with communication modules  51  for performing required communication respectively. Each communication module  51  is connected to the power supply line  52  which connects the on-vehicle devices  41  to  46  and the HV-ECU  31 . 
     As shown in  FIG. 3 , the communication module  51  includes a connection unit  54  which connects the communication module  51  to the power supply line  52 , and a PLC (Power Line Communication) functional circuit  55  functioning as a signal-processor. 
     The PLC functional circuit  55  includes a series parallel conversion section  61  which converts into n parallel data series input data which were generated by any of the on-vehicle devices  41  to  46  and the HV-ECU  31 , n data holding sections  62 - 1  to  62 - n  which hold the converted parallel data temporarily, an IFFT (Inverse Fast Fourier Transform) section  63  which carries out inverse fast Fourier transform of the held parallel data. In addition, the PLC functional part  55  includes a parallel series conversion section  64  which converts into series data the parallel data by which inverse fast Fourier transform was carried out, a D/A (digital/analog) conversion section  65  which converts the series data into analog signals, an LPF (Low-Pass Filter)  66  which removes unnecessary harmonics components from the converted analog signals, an oscillation section  67  which oscillates local frequency signals, and a mixing section  68  which mixes the local frequency signals with the analog signals which passed the LPF  66 , and converts the mixture into a predetermined frequency. 
     The analog signals converted into a predetermined frequency in the mixing section  68  are superimposed on voltage signals of the power supply line  52  in the connection unit  54  and transmitted. Here, if the power supply line  52  is for example, a high-voltage power supply line for a hybrid vehicle, analog signals are superimposed on the power supply line high-voltage of 288V, and are transmitted as superimposed waves. 
     The PLC functional circuit  55  further includes an A/D (analog/digital) conversion section  74  which converts into data the analog signals which are branched from the voltage signals of the power supply line  52  in the connection unit  54  and converted into the local frequency signals in the mixing section  68 , further, whose unnecessary harmonics components are removed in the LPF  66 , a series parallel conversion section  75  which converts the converted series data into n parallel data streams, n data holding sections  76 - 1  to  76 - n  which hold the converted parallel data temporarily, and an FFT (Fast Fourier Transform) section  77  which carries out fast Fourier transform of the held parallel data. The data on which fast Fourier transform was carried out in the FFT section  77  are outputted to a control processor (not shown in  FIG. 3 ). 
     Here, the PLC functional circuit  55  may have a functional composition which performs communication operation by a spectrum diffusion system other than the above-mentioned functional composition of operation. 
     An example of the connection unit  54  is shown in  FIG. 4 . In the example, the communication module  51  is associated with the driving inverter  43  between the on-vehicle devices  41  to  46 . An inverter part  43   a , in the driving inverter  43 , which performs drive control of a motor for hybrid vehicles, is connected to a positive electrode of a high-voltage battery  41   a  for hybrid vehicles, for example, in the battery unit  41  by a positive electrode side core wire  52   a  through a coil L 1  for suppressing high frequency signal components. The inverter part  43   a  is also connected to a negative electrode of the high-voltage battery  41   a  for hybrid vehicles by a negative electrode side core wire  52   b  through a coil L 2  for high frequency suppression. Thereby the power can be supplied to the driving inverter  43 . 
     The connection unit  54  includes capacitors C 1  and C 2  for blocking a direct-current component, and a transformer T 1 . One input-output terminal of the transformer T 1  is connected to the positive electrode side core wire  52   a  through the capacitor C 1  and the negative electrode side core wire  52   b  through the capacitor C 2 . The other input-output terminal of the transformer T 1  is connected to the mixing section  68  (not shown in  FIG. 4 , see  FIG. 3 ) of the PLC functional circuit  55 . 
     That is, the connection unit  54  superimposes or branches analog signals for communication inputted and outputted to the PLC functional circuit  55  on or from voltage signals superimposed on the power supply line  52 . Input data and output data of the PLC functional circuit  55  are exchanged with inverter part  43   a.    
     The power supply line  52  includes a shield part  52   a - s , made of electrical conducting material, which covers the positive electrode side core wire  52   a  with insulating material, and a shield part  52   b - s , made of electrical conducting material, which covers the negative electrode side core wire  52   b  with insulating material. The shield part  52   b - s  is grounded. Moreover, the case of the high-voltage battery  41   a  for hybrid vehicles is also grounded. 
     In the system  30  for performing communication between devices mounted in vehicle of such composition, for example, digital signals of the inverter part  43   a  of the driving inverter  43  shown in  FIG. 4  are converted into analog signals of predetermined frequency in the PLC functional circuit  55  of the communication module  51 , the analog signals are superimposed on voltage signals of the power supply line  52  in the connection unit  54 , and the superimposed waves are transmitted to the HV-ECU  31 . 
     When the superimposed waves transmitted from the communication module  51  of the HV-ECU  31  through the power supply line  52  are inputted into the connection unit  54  of the communication module  51  of the driving inverter  43 , analog signals are branched from the superimposed waves in the connection unit  54 , and the analog signals are inputted into the PLC functional circuit  55 . The inputted analog signals are converted into digital signals in the PLC functional circuit  55 , and then the digital data are inputted into the inverter part  43   a.    
     Thus, according to the system  30  for performing communication between devices mounted in vehicles of the present embodiment, each of the HV-ECU  31  and different kinds of on-vehicle devices  41  to  46  includes a communication module  51  connected to power supply line  52 , and they mutually communicate through communication modules  51 . The power supply line  52  includes positive electrode side core wire  52   a  connected to the positive electrode of the high-voltage battery  41   a  for hybrid vehicles and negative electrode side core wire  52   b  connected to the negative electrode of the high-voltage battery  41   a  for hybrid vehicles. The communication module  51  includes connection unit  54  and PLC functional circuit  55 . The connection unit  54  includes the transformer T 1 . One pair of input-output terminals of the transformer T 1  are connected to the positive electrode side core wire  52   a  and the negative electrode side core wire  52   b  of power supply line  52  through capacitors C 1  and C 2 , respectively. The power supply line  52  is connected for power supply to the HV-ECU  31  and the on-vehicle devices  41  to  46 . The other pair of input-output terminals of the transformer T 1  are connected to PLC functional circuit  55 . The PLC functional circuit  55  converts the analog signals branched from the voltage signals of power supply line  52  in connection unit  54  and outputted from the other input-output terminals into digital signals. In parallel, PLC functional circuit  55  converts externally inputted digital signals into analog signals. Then PLC functional circuit  55  transmits converted analog signals to the other input-output terminals of the transformer T 1  so that the converted analog signals may be superimposed on power supply line  52  in connection unit  54 . 
     Accordingly, in the HV-ECU  31  and different kinds of on-vehicle devices  41  to  46 , analog signals converted in PLC functional parts  55  of communication modules  51  are superimposed on power supply line  52  in connection units  54 . The analog signals superimposed on power supply line  52  are branched in connection unit  54 , and then processed in PLC functional circuit  55 . If the analog signals are used as signals for communication, communication between HV-ECU  31  and different kinds of the on-vehicle devices  41  to  46  may be possible using power supply line  52  which supplies power to the HV-ECU  31  and different kinds of the on-vehicle devices  41  to  46 . 
     Therefore, since the conventional communication lines of exclusive use for communicating between the HV-ECU  31  and different kinds of the on-vehicle devices  41  to  46  becomes unnecessary, troublesome work, such as drag, connection, etc. of communication lines, becomes almost unnecessary whereby the work cost can be reduced sharply. Moreover, since the communication lines of exclusive use themselves are also unnecessary, material cost is also reducible. 
     Alternatively, as shown in  FIG. 5 , the connection unit  54  may connect one input-output terminal of the transformer T 1  to the grounded shield part  52   b - s , made of electrical conducting material, of power supply line  52  through one capacitor C 1 , and to negative electrode side core wire  52   b  through the other capacitor C 2 . 
     In this case, although the analog signals for communication superimposed on the voltage signals are transmitted between negative electrode side core wire  52   b  and shield part  52   b - s , no noise is generated in shield part  52   b - s  since shield part  52   b - s  is grounded, whereby noise can be removed from the analog signals transmitted through power supply line  52 . 
     A further alternative is shown in  FIG. 6  where, in connection unit  54 , the analog signals for communication are transmitted between positive electrode side core wire  52   a  and shield part  52   a - s.    
     Furthermore, although each of positive electrode side core wire  52   a  and negative electrode side core wire  52   b  are shielded by shield parts  52   a - s  and  52   b - s , respectively, in the present embodiment, connection unit  54  is connectable to the power supply line by pairing up positive electrode side core wire  52   a  and negative electrode side core wire  52   b  and shielding the pair collectively with a shield part  52 - s  as well as the above. In this case, as shown in  FIG. 7 , connection unit  54  may be constituted so that the analog signals for communication are transmitted between positive electrode side core wire  52   a  and shield part  52 - s . Alternatively, connection unit  54  may be constituted so that the analog signals for communication are transmitted between negative electrode side core wire  52   b  and shield part  52 - s .