Abstract:
A temperature/voltage detecting unit has a temperature detector and a voltage detector. The temperature detector has a light electric system stabilized power supply for stabilizing a light electric system power supply voltage, a temperature resistance element provided close to a corresponding battery element, for changing its resistance value based on a change in temperature, and a voltage-to-frequency converter operating based on a voltage from the light electric system stabilized power supply, for detecting a terminal voltage of the temperature resistance element to which a constant current flows from the light electric system stabilized power supply, converting this value into frequency information and outputting the frequency information. The voltage detector has a heavy electric system stabilized power supply for stabilizing a voltage supplied from the corresponding battery element, a voltage supply control section for inputting a signal to show whether or not the light electric system power supply voltage is being applied to the temperature detector, and, when this voltage is being supplied, for applying a voltage from the corresponding battery element to the heavy electric system stabilized power supply, and a voltage-to-frequency converter operating based on a voltage from the light electric system stabilized power supply, for detecting a terminal voltage of the corresponding battery element, converting this value into frequency information and outputting the frequency information.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field of the Invention 
     The present invention relates to a temperature/voltage detecting unit for detecting a temperature and a terminal voltage of each of batteries of a heavy electric system for supplying a voltage to a motor for operating an electric car. 
     Further, the present invention relates to a battery element unit having a battery element and a temperature/voltage detecting unit corresponding to this battery element. 
     2. Description of Prior Art 
     Conventionally, electric cars are run by rotationally driving a motor which is supplied with a voltage from a battery of a heavy electric system. Recently, along with the progress of development of batteries with high performance of charge and discharge functions, there has been an increasingly strong demand for voltage management and temperature management of these batteries. For example, a heavy electric system battery for a driving system is structured by about twenty to thirty battery elements connected in series, and it has become necessary to manage both voltage and temperature of each of these battery elements. Therefore, a voltage detector and a temperature detector are necessary by the number of these battery elements. 
     As a conventional voltage detector, there has been used a voltage detector to which a zero magnetic flux method is applied as shown in FIG. 1. A voltage detector  101  shown in FIG. 1 has a magnetic core  103  which is wound up with a primary winding  105  and a secondary winding  107 . The primary winding  105  is connected with a heavy electric system battery  111  structured by a plurality of power supplies  111   a,    111   b,  . . . , and  111   n  connected in series, through a resistor  109 . A Hall element  115  is provided in a gap  113  formed on a magnetic core  103 . 
     In this case, a magnetic fluxΦ 1  is generated within the magnetic core  103  by the primary current I 1  flowing through the primary winding  105 , and the Hall element  115  for detecting this magnetic field generates a voltage corresponding to a direction of the magnetic field and a size of the magnetic field, and outputs this voltage to a current amplifier  117 . The current amplifier  117  amplifies a current based on the voltage from the Hall element  115  and flows an output current I 2  to the secondary winding  107 . When the output current I 2  flows to the secondary winding  107 , a magnetic fluxΦ 2  is generated. In this case, the magnetic fluxΦ 2  works to cancel the magnetic fluxΦ 1 . 
     When the magnetic fluxΦ 2  becomes equal to the magnetic fluxΦ 1 , the magnetic fluxΦ 1  within the magnetic core  103  becomes zero. Accordingly, the Hall element  115  makes the output zero, and the magnetic fluxΦ 2  also becomes zero. In this state, the magnetic fluxΦ 1  is generated again within the magnetic core  103  and an output is generated in the Hall element  115  as well, so that the magnetic fluxΦ 2  becomes larger than the magnetic fluxΦ 1  within the magnetic core  103 . This operation is repeated in high frequency, and the output current I 2  is made as an effective value. At this time, the following law of equal ampere-turns is established. 
     
       
         
           N 
           1 
           ·I 
           1 
           =N 
           2 
           ·I 
           2. 
         
       
     
     When the output current I 2  from the current amplifier  117  is measured by using this expression, the primary current I 1  can be obtained. A detection voltage across both ends of the resistor  119  becomes a voltage proportional to the output current I 2 . 
     However, according to the prior-art technique, a unit having a voltage detector and a unit having a temperature detector are provided separately for each battery element, and therefore, a battery unit as a whole has a large size for these detectors and a considerably large space has been necessary for these detectors. 
     Further, although the prior-art voltage detector has high precision, this has required a large size for the. magnetic core  103 , the primary winding  105  and the secondary winding  107 , resulting in a high cost as well. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a compact and low-cost temperature/voltage detecting unit having a temperature detector and a voltage detector accommodated together therein, with insulation property. 
     Further, it is another object of the present invention to provide a battery element unit for accommodating the above temperature/voltage detecting unit in a groove portion on an external wall of the battery element unit. 
     In order to achieve the above objects, there is provided a temperature/voltage detecting unit corresponding to each of a plurality of battery elements connected in series that constitute a heavy electric system power supply for an electric car, the temperature/voltage detecting unit comprising: a temperature detector for detecting a temperature of a corresponding battery element when a light electric system power supply voltage is being applied; and a voltage detector for inputting a signal to show whether or not the light electric system power supply voltage is being applied to the temperature detector, and, when this voltage is being supplied, for detecting a terminal voltage of the corresponding battery element in a state electrically insulated from the signal. 
     In a preferred embodiment of the present invention, the temperature detector comprises: a light electric system stabilized power supply for stabilizing the light electric system power supply voltage: a temperature resistance element provided close to a corresponding battery element, for changing a resistance value thereof based on a change in the temperature of the battery element; and a resistance terminal voltage detector operating based on a voltage from the light electric system stabilized power supply, for detecting a terminal voltage of the temperature resistance element to which a constant current flows from the light electric system stabilized power supply. 
     In another preferred embodiment of the present invention, the temperature detector further comprises a voltage-to-frequency converter for converting a value of the terminal voltage detected by the resistance terminal voltage detector into frequency information and outputting the frequency information. 
     In still another preferred embodiment of the present invention, the voltage detector comprises: a heavy electric system stabilized power supply for stabilizing a voltage supplied from a corresponding battery element; a voltage supply control section for inputting a signal to show whether or not the light electric system power supply voltage is being applied to the temperature detector, and, when the light electric system power supply voltage is being supplied, for applying the voltage from the corresponding battery element to the heavy electric system stabilized power supply; and a battery element terminal voltage detector operating based on a voltage from the light electric system stabilized power supply, for detecting the terminal voltage of the corresponding battery element. 
     In yet still another preferred embodiment of the present invention, the voltage detector further comprises a voltage-to-frequency converter for converting a value of the terminal voltage detected by the battery element terminal voltage detector into frequency information and outputting the frequency information. 
     In a further preferred embodiment of the present invention, the voltage supply control section comprises: a light-emitting diode for inputting a signal to show whether or not the light electric system power supply voltage is being applied to the temperature detector, and for emitting light or non-emitting light depending on whether or not the light electric system power supply voltage is being applied; a photo-transistor for being turned on/off according to light emission/non-light emission of the light-emitting diode; and a transistor for applying the voltage from the corresponding battery element to the heavy electric system stabilized power supply according to on/off of the photo-transistor. 
     Further, in order to achieve the above objects, there is provided a battery element unit, comprising: the above temperature/voltage detecting unit; and a battery element body having a groove for accommodating the temperature/voltage detecting unit on an external wall thereof. 
     The nature, principle and utility of the invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the accompanying drawings: 
     FIG.1 is view for showing a structure of a prior-art voltage detector: 
     Fig. 2 is a circuit configuration diagram showing an embodiment of a temperature/voltage detecting unit according to the present invention; 
     FIG. 3 is a configuration diagram of each temperature/voltage detecting unit for detecting a temperature and a voltage of each of a plurality of batteries connected in series; 
     FIG. 4 Is an external view for showing a configuration of each temperature/voltage detecting unit; and 
     FIG. 5 is a view for showing a temperature/voltage detecting unit accommodated in a groove of a battery element unit. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     There will be described in detail below embodiments of a temperature/voltage detecting unit according to the present invention with reference to the accompanying drawings. 
     FIG.2 shows a circuit configuration diagram showing a temperature/voltage detecting unit in one embodiment of the present invention. A temperature/voltage detecting unit  1  shown in FIG. 2 is for detecting a temperature and a terminal voltage of each battery element of a heavy electric system battery  2  structured by a series connection of a plurality of battery elements  2   a,    2   b,  . . . The heavy electric system battery  2  has a circuit power supply structured at a primary side to supply a high voltage to a motor for rotationally driving the motor to thereby run an electric car. 
     The temperature/voltage detecting unit  1  has a temperature detector  3  for detecting a temperature of a battery element (for example, a battery  2   b ) of a heavy electric system, and a voltage detector  5  for detecting a terminal voltage of the battery element of the heavy electric system. 
     A light electric system power supply  7  is a +12 V power supply, for example, and supplies a voltage to the temperature detector  3  and the voltage detector  5  when the temperature detector  3  detects a temperature of the battery  2   b  and the voltage detector  5  detects a terminal voltage of this battery, more specifically, when an ignition is ON or during a charging of the battery, for example. For this purpose, the light electric system power supply  7  has switching elements such as a switching transistor and a relay not shown, for example. 
     The temperature detector  3  has a light electric system stabilized power supply  11 , a thermistor resistor  13 , a detection resistor  15  and a voltage-to-frequency converter (V/F)  17 . The light electric system stabilized power supply  11  stabilizes a voltage from the light electric system power supply  7  and supplies the voltage of the light electric system to the thermistor resistor  13 , the voltage-to-frequency converter  17 , a resistor  31  within the voltage detector  5  and a second photo-transistor  47  within the voltage detector  5 . The light electric system stabilized power supply  11  is a +5 V power supply, for example. 
     A resistance value of the thermistor resistor  13  changes according to a change in the temperature of the battery  2   b,  and the detection resistor  15  is connected in series to this thermistor  13 . The voltage-to-frequency converter  17  Inputs a voltage value generated by a division of a voltage according to respective resistance values of the thermistor resistor  13  and the detection resistor  15 , then converts the input voltage value into a frequency corresponding to this value and outputs this frequency information. 
     The frequency information from the voltage-to-frequency converter  17  Is sent to a battery controller not shown and is then processed by this battery controller, so that a temperature of the battery element is measured. 
     In the voltage detector  5 , a resistor  21  and a resistor  23  are connected in series on both ends of the battery  2   b.  The voltage detector  5  is provided with a first photo-coupler  25  which is structured by a first light-emitting diode  27  as a light-emitting element and a first photo-transistor  29  as a light-receiving element. 
     The first light-emitting diode  27  structures an input side, i.e. primary side, and the first photo-transistor  29  structures an output side, i.e. secondary side. The primary side and the secondary side are isolated from each other. A cathode of the first light-emitting diode  27  is grounded, and an anode of the first light-emitting diode  27  is connected to the light electric system stabilized power supply  11  through the resistor  31 . 
     The first light-emitting diode  27  emits light when a voltage of the light electric system stabilized power supply  11  is supplied through the resistor  31 , that is, when a temperature and a voltage of the battery  2   b  are detected. The first photo-transistor  29  receives the light of the first light-emitting diode  45  and operates a transistor  33 . 
     An emitter of the transistor  33  is connected to a positive electrode side (a heavy electric system battery terminal P 1 ) of the battery  2   b,  and a resistor  35  is connected between the emitter and a base of the transistor  33 . The base of the transistor  33  is connected to a collector of the first photo-transistor  29  through a resistor  37 , and an emitter of the first photo-transistor  29  is connected to a negative electrode side (a heavy electric system battery terminal P 2 ) of the battery  2   b.    
     To a collector of the transistor  33 , there is connected a heavy electric system stabilized power supply  39  for stabilizing a voltage from the battery  2   b  through the transistor  33 . This heavy electric system stabilized power supply  39  supplies a stabilized voltage to a voltage-to-frequency converter  41  and an anode of a second light-emitting diode  45  within a second photo-coupler  43 . 
     The second photo-coupler  43  is structured by the second light-emitting diode  45  as a light-emitting element and the second photo-transistor  47  as a light-receiving element. The second light-emitting diode  45  structures an input side, i.e. primary side, and the second photo-transistor  47  structures an output side, i.e. secondary side. The primary side is a heavy electric system and the secondary side is a light electric system, and the heavy electric system and the light electric system are isolated from each other. To a collector of the second photo-transistor  47 , there is applied a voltage of the light electric system stabilized power supply  11  for operating the second photo-transistor  47 . 
     The voltage-to-frequency converter  41  inputs a voltage value generated by a division of a voltage according to respective resistance values of the resistor  21  and the resistor  23 , then converts the input voltage value into a frequency corresponding to this value and outputs this frequency information to a cathode of the second light-emitting diode  45 . 
     The second light-emitting diode  45  emits/non-emits light in a light emission frequency according to the frequency of the frequency information from the voltage-to-frequency converter  41 . The second photo-transistor  47  receives the light of the second light-emitting diode  45  and switches the light into frequency information in a frequency corresponding to a terminal voltage of the battery element  2   b.    
     The frequency information from the second photo-transistor  47  is sent to a battery controller not shown, and is processed by the battery controller to measure the terminal voltage of the battery element. An emitter of the second photo-transistor  47  is grounded. 
     FIG.3 shows a configuration diagram of each temperature/voltage detecting unit for detecting a temperature and a voltage of each of a plurality of battery elements connected in series. As shown in FIG. 3, temperature/voltage detecting units  1   a,    1   b,    1   c,  . . . , and  1   n  are provided corresponding to battery elements  2   a,    2   b,    2   c,  . . . , and  2   n.  Voltage detectors  5   a,    5   b.    5   c,  . . . , and  5   n  are connected to both ends of the corresponding battery elements  2   a,    2   b,    2   c  . . . , and  2   n.  Each of the temperature/voltage detecting units  1   a,    1   b,    1   c,  . . . , and  1   n  has the same structure as that of the temperature/voltage detecting unit  1  shown in FIG.  2 . 
     Each battery element is 12 V and a total voltage of the batteries is 28 V, for example. A motor  51  is connected as a load of an electric car to both ends of the total batteries through a current detector  49 . The current detector  49  detects a current flowing through the motor  51 . 
     FIG. 4 shows an external view of a configuration of each temperature/voltage detecting unit. In the temperature/voltage detecting unit  1  shown in FIG. 4, there is provided a box-shaped accommodation case  55  for accommodating the above-descrlbed temperature detector  3  and the voltage detector  5 . Wires  59   a,    59   b,    59   c  and  59   d  are connected to this accommodation case  55  through a connector  57 . 
     A ring terminal  61   a  is fitted to a front end of the wire  59   a,  and this ring terminal  61   a  is connected to the heavy electric system battery terminal P 2  (the load side) shown in FIG. 2. A ring terminal  61   b  is fitted to a front end of the wire  59   b.  and this ring terminal  61   b  is connected to the heavy electric system battery terminal P 1  (the positive electrode side) shown in FIG.  2 . There is input a terminal voltage of the heavy electric system battery element to the voltage detector  5  within the accommodation case  55  through the ring terminals  61   a  and  61   b.    
     A connector  63  is fitted to a front end of the wire  59   c,  and this connector  63  Is connected to the light electric system power supply  7  shown in FIG. 2. A voltage of the light electric system is applied to each of the temperature detector  3  and the voltage detector  5  within the accommodation case  55  through this connector  63 . 
     A connector  65  is fitted to a front end of the wire  59   d,  and this connector  65  outputs frequency information from the voltage-to-frequency converter  17  within the temperature detector  3  within the accommodation case  55  and from the voltage-to-frequency converter  41  within the voltage detector  5 . 
     According to this temperature/voltage detecting unit  1 , as the temperature detector  3  and the voltage detector  5  are accommodated in the accommodation case  55  within the same unit, this has an effect that the unit can be provided in compact at low cost, as compared with the case where the temperature detector  3  and the voltage detector  5  are accommodated in separate units. Further, as the temperature/voltage detecting unit  1  is provided for each battery, this has a large effect. 
     Further, as shown in FIG. 5, there may be provided a temperature/voltage detecting unit  1  for each battery element, such as for, example, in a groove portion  67  of the battery element  2   b.  With this arrangement, a space occupied by the temperature detector  3  and the voltage detector  5  is not necessary and the peripheral structure of the batteries can be simplified. 
     Furthermore, by accommodating the temperature detector  3  and the voltage detector  5  in the same unit, electric wires for the heavy electric system becomes unnecessary. These detectors are optimum as a temperature detector and a voltage detector for an electric car for managing the temperature and voltage of each battery element. 
     Next, the operation of the temperature/voltage detecting unit of the present embodiment having the above-described structure will be explained with reference to FIG.  2 . At first, the light electric system power supply  7  applies a voltage to the light electric system stabilized power supply  11  at the time of detecting a temperature and a terminal voltage of the battery element  2   b.  Then, at the detection time, the light electric system stabilized power supply  11  applies a stabilized voltage to the thermistor resistor  13 , the voltage-to-frequency converter  17 , the resistor  31  and the second photo-transistor  47 . 
     Then, a current flows from the light electric system stabilized power supply  11  to the thermistor resistor  13  and the detection resistor  15 . The resistance value of the thermistor resistor  13  changes according to a change in the temperature of the battery  2   b.  A voltage value generated by a division of a voltage according to respective voltage values of the thermistor resistor  13  and the detection resistor  15  is input to the voltage-to-frequency converter  17 . The voltage-to-frequency converter  17  converts the input voltage value into a frequency information according to this value, and outputs this frequency information to a battery controller not shown. 
     On the other hand, in the voltage detector  5 , when a temperature and a voltage of the battery element  2   b  are detected, a voltage from the light electric system stabilized power supply  11  is applied to the first light-emitting diode  27  through the resistor  31 , so that the first light-emitting diode  27  emits light. 
     Then, the first photo-transistor  29  operates upon receiving the light of the first light-emitting diode  27 , and a current flows from the positive electrode side of the battery element  2   b  to the negative electrode side of the battery element  2   b  through the resistor  35 , the resistor  37  and the first photo-transistor  29 . 
     Thus, the transistor  33  operates, and a voltage of the heavy electric system of the battery element  2   b  is applied to the heavy electric system stabilized power supply  39 . Then, the heavy electric system stabilized power supply  39  applies a stabilized voltage to the voltage-to-frequency converter  41  and the second light-emitting diode  45  only at the time of detecting a temperature and a voltage of the battery element  2   b.    
     Further, when a voltage value generated by a division of a voltage according to the respective resistance values of the resistor  21  and the resistor  23  is input to the voltage-to-frequency converter  41 , the voltage-to-frequency converter  41  converts the input voltage value into a frequency information according to this value and outputs this frequency to the cathode of the second light-emitting diode  45 . Then, the second light-emitting diode  45  emit/non-emits light in a light emission frequency according to the frequency of the frequency information from the voltage-to-frequency converter  41 . The second photo-transistor  47  receives the light of the second light-emitting diode  45  and switches the light into frequency information in a frequency corresponding to a terminal voltage of the battery element  2   b.    
     Then, a battery controller not shown processes the frequency information from the temperature detector  3  and the frequency information from the voltage detector  5 , and measures the temperature and the terminal voltage of the battery element  2   b.    
     As explained above, according to the temperature/voltage detecting unit of the present embodiment, since the voltage detector  5  is structured by using the first photo-coupler  25  and the second photo-coupler  43  having insulation, it is possible to provide a compact and low-cost temperature/voltage detecting unit having insulation, as compared with a voltage detector using the zero magnetic flux method. 
     Further, as the light electric system power supply  7  drives the heavy electric system stabilized power supply  39  to operate the voltage-to-frequency converter  41  and the second light-emitting diode  45  only at the time of detecting a temperature and a voltage of the battery element  2   b,  it becomes possible to avoid a dark current flowing from the heavy electric system stabilized power supply  39 , that has received a voltage supply from the battery  2   b  of the heavy electric system, to the voltage-to-frequency converter  41  and the second photo-diode  45  within the second photo-coupler  43 , at the time of other than the detection of the temperature and the voltage of the battery element of the heavy electric system. By avoiding the flow of the dark current, a discharging of the battery element  2   b  of the heavy electric system can be prevented. 
     Further, by employing each voltage detector and each temperature detector, a voltage and a temperature of each battery element can be measured. As each voltage detector is compact and low cost, this is optimum as a voltage detector for an electric car in managing the voltage of each of a plurality of battery elements connected in series. 
     Further, as the voltage-to-frequency converter  17  and the voltage-to-frequency converter  41  are used, frequency information is obtained as an output, with small noise in the output, and this has an effect of obtaining an accurate output. 
     Furthermore, as the first photo-coupler  25  is used, the light electric system and the heavy electric system are insulated from each other, and it is possible to avoid an application of a heavy electric system voltage to the light electric system in case of an occurrence of an incident. 
     It should be understood that many modifications and adaptations of the Invention will become apparent to those skilled In the art and it is intended to encompass such obvious modifications and changes in the scope of the claims appended hereto.