Power source apparatus for vehicle

Abstract

A power source apparatus mounted to a vehicle is equipped with a lead-acid battery and a lithium battery. An open circuit voltage and an internal resistance of each of the batteries are determined to satisfy the following conditions (a1), (a2), and (a3): (a1) In the use range of SOC of the lead-acid battery and the use range of SOC of the lithium battery, there is an equal voltage point Vds at which the open circuit voltage V 0 (Pb) of the lead-acid battery becomes equal to the open circuit voltage V 0 (Li) of the lithium battery; (a2) The relationship of V 0 (Li)>V 0 (Pb) is satisfied in the upper limit side of the use range of SOC of the battery; and (a3) A terminal voltage Vc (Li) of the lithium battery is not more than a set voltage Vreg of a regulator when a maximum current flows in the lithium battery.

1 . A power source apparatus which is mounted to a vehicle with an alternator and a constant voltage control means capable of adjusting a voltage of electric power generated by the alternator to a set voltage, the power source apparatus comprising:
 a lead-acid battery electrically connected to an alternator; and   a secondary battery, electrically connected in parallel to the lead-acid battery, having an output power density and an energy density which is higher than an output power density and an energy density of the lead-acid battery,   wherein an open circuit voltage and an internal resistance of the lead-acid battery and an open circuit voltage and an internal resistance of the secondary battery are determined in order to satisfy the following conditions (a), (b), and (c):   (a) an equal voltage point, at which the open circuit voltage of the lead-acid battery becomes equal to the open circuit voltage of the secondary battery, is present in a use range of state of charge (SOC) of the lead-acid battery and a use range of SOC of the secondary battery;   (b) the open circuit voltage of the secondary battery is higher than the open circuit voltage of the lead-acid battery at an upper limit side from the equal voltage point in the use range of SOC of the secondary battery; and   (c) a terminal voltage of the secondary battery when a maximum charging current flows in the secondary battery is not more than the set voltage which is set by the constant voltage control means.   
     
     
         2 . The power source apparatus according to  claim 1 , wherein the open circuit voltage and the internal resistance of the lead-acid battery and the open circuit voltage and the internal resistance of the secondary battery are determined so that the open circuit voltage of the secondary battery is lower than the open circuit voltage of the lead-acid battery at the lower limit side from the equal voltage point in the use range of SOC of the secondary battery. 
     
     
         3 . The power source apparatus according to  claim 2 , wherein the open circuit voltage and the internal resistance of the lead-acid battery and the open circuit voltage and the internal resistance of the secondary battery are determined so that an upper part at the upper limit side from the equal voltage point is wider than a lower part at the lower limit side from the equal voltage point in the use range of SOC of the secondary battery. 
     
     
         4 . The power source apparatus according to  claim 1 , further comprising voltage drop suppression means capable of suppressing discharge from the secondary battery to a starter motor mounted to the vehicle in order to suppress a voltage drop of the secondary battery. 
     
     
         5 . The power source apparatus according to  claim 4 , further comprising protection control means capable of protecting the secondary battery from overcharge by limiting a charging capacity to the secondary battery and of protecting the secondary battery from over discharge by limiting a discharging capacity from the secondary battery so that the residual capacity of the secondary battery is within the use range of the secondary battery,
 wherein the protection control means limits the charging capacity to the secondary battery or the discharging capacity from the secondary battery by using the voltage drop suppression means.   
     
     
         6 . The power source apparatus according to  claim 1 , further comprising protection control means capable of protecting the secondary battery from overcharge by controlling a charging capacity into the secondary battery and protecting the secondary battery from over discharge by controlling a discharging capacity to the secondary battery so that the residual capacity of the secondary battery is within the use range of the secondary battery,
 wherein the protection control means outputs an instruction signal which instructs the constant voltage control means to decrease the set voltage in order to control the charging capacity to the secondary battery.   
     
     
         7 . The power source apparatus according to  claim 4 , wherein the voltage drop suppression means is a switch means to open and close an electric connection between the secondary battery and the starter motor, and the switch means opens the electric connection between the secondary battery and the starter motor when the lead-acid battery supplies the electric capacity to the starter motor. 
     
     
         8 . The power source apparatus according to  claim 7 , wherein the switch means is one of a manual switch, an electromagnetic relay, and a semiconductor switch. 
     
     
         9 . The power source apparatus according to  claim 1 , wherein the secondary battery is a battery of non-aqueous electrolyte. 
     
     
         10 . The power source apparatus according to  claim 9 , wherein the secondary battery is comprised of a positive electrode made of positive electrode active material, a negative electrode made of negative electrode active material, and an electrolyte, the negative electrode active material is one of carbon, graphite, lithium-doped carbon or graphite, lithium titanium oxide, silicon-containing alloy, and tin-containing alloy, and the positive electrode active material is lithium metal composite oxide or activated carbon. 
     
     
         11 . The power source apparatus according to  claim 10 , wherein the positive electrode active material is made of lithium iron phosphate. 
     
     
         12 . The power source apparatus according to  claim 1 , wherein
 the secondary battery is comprised of a plurality of battery cells electrically connected in series, and further comprising cell equalizing means capable of detecting a voltage of each of the battery cells and of equalizing a residual capacity of each of the battery cells based on the detected voltage of each of the battery cells.   
     
     
         13 . The power source apparatus according to  claim 1 , wherein the power source apparatus is mounted to a vehicle with an idling stop function capable of automatically stopping and restarting the operation of the internal combustion engine. 
     
     
         14 . A power source apparatus which is mounted to a vehicle with an alternator and a constant voltage control means capable of adjusting a voltage of electric power generated by the alternator to a set voltage, the power source apparatus comprising:
 a lead-acid battery electrically connected to an alternator;   a secondary battery, electrically connected in parallel to the lead-acid battery, is higher in output density or energy density than the lead-acid battery; and   rectifying means placed between the lead-acid battery and the secondary battery so that a forward current direction of the rectifying means becomes a direction from the lead-acid battery to the secondary battery, and the rectifying means having a barrier voltage to the current flowing in the forward direction through the rectifying means,   wherein an open circuit voltage and an internal resistance of the lead-acid battery and an open circuit voltage and an internal resistance of the secondary battery are determined in order to satisfy the following conditions (a′), (b′), and (c′):   (a′) an equal voltage point, at which the open circuit voltage of the secondary battery is equal to a subtracted voltage obtained by subtracting the barrier voltage of the rectifying means from the open circuit voltage of the lead-acid battery, is present in a use range of state of charge (SOC) of the lead-acid battery and a use range of SOC of the secondary battery;   (b′) the open circuit voltage of the secondary battery is higher than the subtracted voltage of the lead-acid battery at an upper limit side from the equal voltage point in the use range of SOC of the secondary battery; and   (c′) a terminal voltage of the secondary battery when a maximum charging current flows in the secondary battery is not more than the set voltage which is set by the constant voltage control means.   
     
     
         15 . The power source apparatus according to  claim 14 , further comprising:
 open and close means, connected in parallel to the rectifying means, capable of electrically connecting the alternator with the secondary battery and disconnecting the alternator from the secondary battery; and   open and close control means to instruct the open and close means to close the electrical connection between the alternator and the secondary battery when the secondary battery is charged with electric power generated by the alternator, and to instruct the open and close means to open the electrical connection between the alternator and the secondary battery when the rectifying means performs the rectifying operation.   
     
     
         16 . The power source apparatus according to  claim 15 , wherein the open and close means is composed of a semiconductor switch, and the rectifying means is composed of a parasitic diode of the semiconductor switch. 
     
     
         17 . The power source apparatus according to  claim 15 , wherein the open and close means is composed of an electromagnetic relay which is connected in parallel to the rectifying means. 
     
     
         18 . The power source apparatus according to  claim 14 , wherein the open circuit voltage and the internal resistance of the lead-acid battery and the open circuit voltage and the internal resistance of the secondary battery are determined so that the open circuit voltage of the secondary battery is lower than the subtracted voltage of the lead-acid battery at the lower limit side from the equal voltage point in the use range of SOC of the secondary battery, where the subtracted voltage of the lead-acid battery is obtained by subtracting the barrier voltage of the rectifying means from the open circuit voltage of the lead-acid battery. 
     
     
         19 . The power source apparatus according to  claim 18 , wherein the open circuit voltage and the internal resistance of the lead-acid battery and the open circuit voltage and the internal resistance of the secondary battery are determined so that a range at the upper limit side from the equal voltage point in the use range of SOC of the secondary battery is wider than a lower part at the lower limit side from the equal voltage point in the use range of SOC of the secondary battery. 
     
     
         20 . The power source apparatus according to  claim 15 , further comprising protection control means capable of protecting the secondary battery from overcharge by limiting a charging capacity to the secondary battery and of protecting the secondary battery from over discharge by limiting a discharging capacity from the secondary battery so that the residual capacity of the secondary battery is within the use range of the secondary battery,
 wherein the protection control means limits the charging capacity to the secondary battery or the discharging capacity from the secondary battery by using the voltage drop suppression means.   
     
     
         21 . The power source apparatus according to  claim 15 , further comprising protection control means capable of protecting the secondary battery from overcharge by controlling a charging capacity to the secondary battery and protecting the secondary battery from over discharge by controlling a discharging capacity from the secondary battery so that the residual capacity of the secondary battery is within the use range of the secondary battery,
 wherein the protection control means outputs an instruction signal which instructs the constant voltage control means to decrease the set voltage in order to control the charging capacity to the secondary battery.   
     
     
         22 . The power source apparatus according to  claim 14 , wherein the secondary battery is a battery of non-aqueous electrolyte. 
     
     
         23 . The power source apparatus according to  claim 22 , wherein the secondary battery is comprised of a positive electrode made of positive electrode active material, a negative electrode made of negative electrode active material, and an electrolyte, the negative electrode active material is one of carbon, graphite, lithium-doped carbon or graphite, lithium titanium oxide, silicon-containing alloy, and tin-containing alloy, and the positive electrode active material is lithium metal composite oxide or activated carbon. 
     
     
         24 . The power source apparatus according to  claim 23 , wherein the negative electrode active material is made of lithium titanium oxide. 
     
     
         25 . The power source apparatus according to  claim 14 , wherein the secondary battery is comprised of a plurality of battery cells electrically connected in series, and further comprising cell equalizing means capable of detecting a voltage of each of the battery cells and of equalizing a residual capacity of each of the battery cells based on the detected voltage of each of the battery cells. 
     
     
         26 . The power source apparatus according to  claim 14 , wherein the power source apparatus is mounted to a vehicle with an idle stop function capable of automatically stopping and restarting the operation of the internal combustion engine.