Patent Publication Number: US-2009229898-A1

Title: Controller for Electric Storage Device and Vehicle with Controller for Electric Storage Device

Description:
INCORPORATION BY REFERENCE 
     The disclosure of the following priority application is herein incorporated by reference: 
     Japanese Patent Application No. 2008-20630 filed Jan. 31, 2008 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a controller for an electric storage device, in particular, it relates to a controller for an electric storage device that stores regenerated energy of a vehicle such as an automobile or the like, and to a vehicle that is equipped with such a controller. 
     2. Description of Related Art 
     In the prior art, an electric storage device for regenerated energy in a vehicle has been proposed in which an auxiliary power supply is connected to a generator that is linked to an engine, and this auxiliary power supply is connected to a main power supply consisting of a 12V battery and electrical load such as an auxiliary device of some sort via a switch independent of a DC/DC converter (refer to Japanese Laid-Open Patent Publication No. 2004-328988). By recuperating the regenerated energy into the auxiliary power supply, this electric storage device increases the capacity for recuperated energy and enhances the efficiency of recuperation so as to improve the fuel consumption of the vehicle. 
     With an electric storage device for regenerated energy as described above, a conversion loss takes place in the DC/DC converter because the energy that has been recuperated to the auxiliary power supply is supplied to the main power supply via the DC/DC converter, and this causes a increase of the fuel consumption. Moreover, although it is possible to enhance the robustness in the case of a DC/DC converter fault and reduce the conversion loss of the DC/DC converter by using the switch independent of the DC/DC converter, this invites further complication of the electric storage device. 
     Furthermore, the negative electrode side of the auxiliary power supply is grounded to the vehicle independently, and this is different from the ground point of the negative electrode within the DC/DC converter. Due to this, electrical current leaked by the DC/DC converter flows between the auxiliary power supply and the DC/DC converter via the chassis of the vehicle or the like, and this constitutes a cause for the generation of EMC noise. 
     The object of the present invention is to convert and recuperate the regenerated energy in the vehicle such as an automotive or the like with high efficiency, and moreover to provide a controller for an electric storage device and a vehicle with this controller for an electric storage device, with high reliability and EMC noise due to leak current during the conversion being reduced. 
     SUMMARY OF THE INVENTION 
     According to a first aspect of the present invention, a controller for an electric storage device, one side of which is linked with a generator or a motor generator that is rotated by power of an engine to generate AC electrical power and includes a rectifier that converts the AC electrical power into DC electrical power, and the other side of which is linked with an on-vehicle battery and an auxiliary device, comprises an arm that includes first and second switching elements connected in series, an electric storage battery that is connected in parallel with the first and second switching elements, a primary rectification capacitor that is connected in parallel with the first and second switching elements, a reactor, one end of which is connected to a connection portion at which the first and second switching elements are connected, and the other end of which is connected to an output terminal to the on-vehicle battery and the auxiliary device, a secondary rectification capacitor that is connected to the output terminal side of the reactor, and a control unit that switches the first switching element. In this controller for an electric storage device, the control unit turns the first switching element ON when a state of charge of the electric storage battery is greater than a state of charge necessary for starting the engine and a voltage of the on-vehicle battery is less than a voltage necessary for starting the engine. 
     According to a second aspect of the present invention, a controller for an electric storage device, one side of which is linked with a generator or a motor generator that is rotated by power of an engine to generate AC electrical power and includes a rectifier that converts the AC electrical power into DC electrical power, and the other side of which is linked with an on-vehicle battery and an auxiliary device, comprises an arm that includes first and second switching elements connected in series, an electric storage battery that is connected in parallel with the first and second switching elements, a primary rectification capacitor that is connected in parallel with the first and second switching elements, a reactor, one end of which is connected to a connection portion at which the first and second switching elements are connected, and the other end of which is connected to an output terminal to the on-vehicle battery and the auxiliary device, a secondary rectification capacitor that is connected to the output terminal side of the reactor, and a control unit that switches the first switching element, In this controller for an electric storage device, the control unit turns the first switching element continuously ON when a voltage difference between the voltage of the electric storage battery and the voltage of the on-vehicle battery is less than a predetermined value, and the control unit turns the first switching element intermittently ON when the voltage difference is greater than the predetermined value. 
     According to a third aspect of the present invention, the controller for an electric storage device according to the second aspect may further comprise a terminal that is installed in a vehicle body and to which the arm, the electric storage battery, the primary rectification capacitor and the secondary rectification capacitor are electrically connected. 
     According to a fourth aspect of the present invention, in the controller for an electric storage device according to the second aspect, it is preferable that, when the voltage of the on-vehicle battery is greater than a predetermined maximum voltage, the control unit turns the first switching element OFF to stop supply of electrical power to the on-vehicle battery and to the auxiliary device, when the voltage of the on-vehicle battery is less than the maximum voltage and the voltage difference is greater than the predetermined value, the control unit turns the first switching element intermittently ON and stops generation of the AC electrical power by the generator or the motor generator, and when the voltage of the on-vehicle battery is less than the maximum voltage and the voltage difference is less than the predetermined value, the control unit turns the first switching element continuously ON and performs control for adjusting amount of generation of the AC electrical power by the generator or the motor generator. 
     According to a fifth aspect of the present invention, in the controller for an electric storage device according to the second aspect, it is also preferable that, when a state of charge of the electric storage battery is greater than a state of charge necessary for starting the engine and the voltage of the on-vehicle battery is less than a voltage necessary for starting the engine, the control unit turns the first switching element ON so that electrical power from the electric storage battery is supplied to a starter that is connected to the on-vehicle battery. 
     According to a sixth aspect of the present invention, in the controller for an electric storage device according to any one of the first through fifth aspects, it is desirable that two of the arms and two of the reactors are provided and the phase difference between the timings at which the two first switching elements that are provided to the two arms are turned ON and OFF is made to be approximately 180°. 
     According to a seventh aspect of the present invention, an electricity generation and storage unit comprises a field winding type generator or motor generator that includes a field winding, is linked to an engine, is rotated by the engine to generate AC electrical power and includes a rectifier that converts the AC electrical power into DC electrical power, and an electric storage device, one side of which is linked with the generator or the motor generator, and the other side of which is linked with an on-vehicle battery and an auxiliary device. In this electricity generation and storage unit, the electric storage device comprises an arm that includes first and second switching elements connected in series, an electric storage battery that is connected in parallel with the first and second switching elements, a primary rectification capacitor that is connected in parallel with the first and second switching elements, a reactor, one end of which is connected to a connection portion at which the first and second switching elements are connected, and the other end of which is connected to an output terminal to the on-vehicle battery and the auxiliary device, a secondary rectification capacitor that is connected to the output terminal side of the reactor, and a control unit that switches the first switching element. And the control unit turns the first switching element ON when a state of charge of the electric storage battery is greater than a state of charge necessary for starting the engine and a voltage of the on-vehicle battery is less than a voltage necessary for starting the engine. 
     According to an eighth aspect of the present invention, an electricity generation and storage unit comprises a field winding type generator or motor generator that includes a field winding, is linked to an engine, is rotated by the engine to generate AC electrical power and includes a rectifier that converts the AC electrical power into DC electrical power, and an electric storage device, one side of which is linked with the generator or the motor generator, and the other side of which is linked with an on-vehicle battery and an auxiliary device. In this electricity generation and storage unit, the electric storage device comprises an arm that includes first and second switching elements connected in series, an electric storage battery that is connected in parallel with the first and second switching elements, a primary rectification capacitor that is connected in parallel with the first and second switching elements, a reactor, one end of which is connected to a connection portion at which the first and second switching elements are connected, and the other end of which is connected to an output terminal to the on-vehicle battery and the auxiliary device, a secondary rectification capacitor that is connected to the output terminal side of the reactor, and a control unit that switches the first switching element. The control unit turns the first switching element continuously ON when a voltage difference between the voltage of the electric storage battery and the voltage of the on-vehicle battery is less than a predetermined value, and the control unit turns the first switching element intermittently ON when the voltage difference is greater than the predetermined value. 
     According to a ninth aspect of the present invention, the electricity generation and storage unit according to the eighth aspect may further comprise a terminal that is installed in a vehicle body and to which the arm, the electric storage battery, the primary rectification capacitor and the secondary rectification capacitor are electrically connected. 
     According to a tenth aspect of the present invention, in the electricity generation and storage unit according to the eighth aspect, it is preferable that, when a state of charge of the electric storage battery is greater than a state of charge necessary for starting the engine and the voltage of the on-vehicle battery is less than a voltage necessary for starting the engine, the control unit turns the first switching element ON so that electrical power from the electric storage battery is supplied to a starter that is connected to the on-vehicle battery. 
     According to an eleventh aspect of the present invention, in the electricity generation and storage unit according to the eighth aspect, it is also preferable that, when the voltage of the on-vehicle battery is greater than a predetermined maximum voltage, the control unit turns the first switching element OFF to stop supply of electrical power to the on-vehicle battery and to the auxiliary device, when the voltage of the on-vehicle battery is less than the maximum voltage and the voltage difference is greater than the predetermined value, the control unit turns the first switching element intermittently ON and stops generation of the AC electrical power by the generator or the motor generator, and when the voltage of the on-vehicle battery is less than the maximum voltage and the voltage difference is less than the predetermined value, the control unit turns the first switching element continuously ON and performs control for adjusting amount of generation of the AC electrical power by the generator or the motor generator. 
     According to a twelfth aspect of the present invention, in the electricity generation and storage unit according to any one of the seventh through eleventh aspects, it is desirable that two of the arms and two of the reactors are provided and the phase difference between the timings at which the two first switching elements that are provided to the two arms are turned ON and OFF is made to be approximately 180°. 
     According to a thirteenth aspect of the present invention, in a vehicle equipped with the controller for an electric storage device according to any one of the first through sixth aspects, or in a vehicle equipped with the generation and storage unit according to any one of the seventh through twelfth aspects, it is preferable that, when the state of charge of the electric storage battery drops below a maximum state of charge during deceleration of the vehicle, regenerated energy is recuperated into the electric storage battery by performing regeneration control of the generator or the motor generator by controlling its field current based upon a state variable according to at least any one of the state of charge of the electric storage battery, rotational speed of the generator or the motor generator, and vehicle speed. 
     According to a fourteenth aspect of the present invention, in a vehicle equipped with the controller for an electric storage device according to the third aspect, or in a vehicle equipped with the generation and storage unit according to the ninth aspect, it is also preferable that the terminal is connected to the body of the vehicle. 
     According to a fifteenth aspect of the present invention, in the vehicle according to the thirteenth or fourteenth aspect, it is desirable that, when the state of charge of the electric storage battery rises above the maximum state of charge during deceleration of the vehicle, the field current is turned OFF to stop generation of electrical power using the regenerated energy. 
     According to a sixteenth aspect of the present invention, in the vehicle according to the thirteenth or fourteenth aspect, it is also desirable that, when the voltage of the on-vehicle battery rises above a maximum voltage during deceleration of the vehicle, the first switching element is turned OFF, and when the voltage of the on-vehicle battery drops below the maximum voltage during deceleration of the vehicle, the first switching element is turned intermittently ON. 
     According to the present invention described above, high reliability and cost reduction are achieved in a controller for an electric storage device. In addition, the fuel consumption and EMC noise are reduced in the vehicle according to the present invention such as an automotive or the like, since this vehicle is able to convert and recuperate the regenerated energy with high efficiency. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         FIG. 1  shows a vehicle that is equipped with an electric storage device according to the present invention (Embodiment 1); 
         FIG. 2  shows a block diagram of an electric storage device  100  according to the present invention and of an alternator  200 ; 
         FIG. 3  shows the flow of control operation after a key of the vehicle is turned ON; 
         FIG. 4  shows the flow of control operation for control of generation of electricity by the alternator, when recuperation of regenerated energy is being performed after the engine of the vehicle has been started; 
         FIG. 5  shows the flow of an operation for controlling the alternator with the field current I f , when recuperating the regenerated energy of the vehicle; 
         FIG. 6  shows the operation of a MOS-FET  13 , when recuperating the regenerated energy of the vehicle; 
         FIG. 7  shows examples of transitions between various states of vehicle speed and so on in a specific condition under which the vehicle is traveling; 
         FIG. 8  shows examples of methods for connection of an electric storage battery  11  according to the present invention; 
         FIG. 9  shows an example of a block diagram of a non-insulated type electrical power conversion device according to the present invention; 
         FIG. 10  shows a waveform when a MOS-FET  13   a  goes ON and OFF, and a waveform when a MOS-FET  13   b  goes ON and OFF; 
         FIG. 11  shows another vehicle that is equipped with an electric storage device according to the present invention (Embodiment 2); 
         FIG. 12  shows a block circuit diagram of a motor controller  500  shown in  FIG. 11 ; 
         FIG. 13  shows the flow of control operation when the engine of the vehicle shown in  FIG. 11  is started; 
         FIG. 14  shows the flow of control operation when retrieval of regenerated energy is not being performed after the engine of the vehicle shown in  FIG. 11  has been started; 
         FIG. 15  shows the flow of control operation for controlling an M/G (motor generator) when regenerated energy of the vehicle shown in  FIG. 11  is being recuperated; 
         FIG. 16  shows the flow of control operation for controlling the MOS-FET when regenerated energy of the vehicle shown in  FIG. 11  is being recuperated; and 
         FIG. 17  shows an example of a method of communication between a control device  40  of the electric storage device  100 , a control circuit  54  of a motor controller, and a control unit  600  that is an upper controller than the control device  40  and the control circuit  54 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of the present invention will now be explained with reference to  FIGS. 1 through 17 . 
     Embodiment 1 
       FIG. 1  shows a vehicle that is equipped with an electric storage device according to the present invention. In  FIG. 1 , the vehicle  1  is equipped with an engine  2 . The engine  2  drives front wheels  6   a  and  6   b  via a transmission  3  and wheel axles  5   a  and  5   b.  It should be understood that the present invention is not limited to the front wheel drive vehicle shown in  FIG. 1 ; it could also be applied to a vehicle in which the engine drives the rear wheels  10   a  and  10   b , or to a vehicle in which all four wheels are driven, or to a truck that is equipped with six or more wheels, or to a towing vehicle such as a trailer. 
     An alternator  200 , consisting of an AC electric motor that is linked via a belt  9  to the engine  2 , is provided within the engine compartment. This alternator  200  is driven by the engine  2 , and serves both to charge up an on-vehicle battery  7  and to supply power to some type of auxiliary device  8  of the vehicle that operates as a load. An electric storage device  100  is provided between the alternator  200  and the on-vehicle battery  7  and auxiliary device  8 . This electric storage device  100  functions as a storage battery for electrical power generated by the alternator  200 , in a similar manner to the on-vehicle battery  7 , and, along with supplying the charged electrical power to the auxiliary device  8 , also recuperates regenerated energy that is converted into electrical power by the alternator  200 . A starter  4 , that is an engine starting means, is linked to the engine  2 . This starter  4  is electrically connected to the on-vehicle battery  7 . 
     It should be understood that although, according to the above explanation, the alternator  200  is linked to the engine  2  by the belt  9 , it would also be acceptable to arrange to link the alternator  200  and the engine  2  by some other means. For example, it would be acceptable to arrange to link them by a chain. Moreover, it would also be acceptable to arrange to mount the alternator  200  between the transmission  3  and the engine  2 , and to link it to the crank shaft or to a shaft within the transmission  3 . Furthermore, it would be acceptable for the voltage of the battery  7  to be, not 12V like an ordinary passenger car, but for example 24V or 42V. The electric storage device  100  not only may be mounted in the engine compartment, but also in the trunk or the passenger compartment or the like. 
       FIG. 2  shows a block diagram of an electric storage device  100  according to the present invention and of an alternator  200 . As shown in  FIG. 2 , the alternator  200  includes a stator coil  21  having three phases, and a field coil  23  that generates a magnetic field. The three phases of the stator coil  21  are connected to a rectifier  22  that consists of diodes. This rectifier  22  converts the AC electrical power of the stator coil  21  into DC electrical power. The field coil  23  is connected to an electrical current control circuit  24  that includes a semiconductor switch. This current control circuit  24  is connected to a control device  40 . The control device  40  controls the field current I f  of the field coil  23  via the current control circuit  24 . 
     The current control circuit  24  is connected to the positive electrode of the rectifier  22 . The current control circuit  24  receives supply of the field current I f  due to the DC output from the positive electrode of the rectifier  22 . The negative electrode of the rectifier  22  and the current control circuit  24  are both grounded to the vehicle earth. In the alternator  200 , when the magnetic field changes according to the magnitude of the field current I f , the generated electrical power also changes. Due to this, the control device  40  controls the electrical power generated by the alternator  200  by controlling the field current I f . 
     It should be understood that although, in the above example, the stator coil  21  is a three phase coil, it would also be acceptable for it to be a two phase coil, or some other number of multiple phases. Furthermore, for the rectifier  22 , as well as a diode, a MOS-FET or the like could also be used. 
     The electric storage device  100  includes an electric storage battery  11  (a secondary battery) that consists of an ultra-capacitor, a primary rectification capacitor  12  that consists of an electrolytic capacitor, a MOS-FET  13 , a diode  14 , a reactor  15 , and a secondary rectification capacitor  16  that consists of a film capacitor. The MOS-FET  13  and the diode  14  constitute an arm. This arm and the primary rectification capacitor  12 , the reactor  15 , and the secondary rectification capacitor  16  constitute a non-insulated type step-down converter. The output  12 VOUT of the reactor  15  is connected to the on-vehicle battery  7  of the vehicle  1  and to the auxiliary device  8 . 
     The electric storage battery  11  is connected in parallel with the primary rectification capacitor  12 . The positive electrodes of the electric storage battery  11  and the primary rectification capacitor  12  are connected to the rectifier  22 . The negative electrodes of each of the electric storage battery  11 , the primary rectification capacitor  12 , the diode  14 , and the secondary rectification capacitor  16  are connected to a single electrical spot shown as GND-P, for example by a bus bar or the like, and grounded to the vehicle earth. Moreover, a gate output for turning the MOS-FET  13  ON and OFF is connected to the control device  40 . By turning the MOS-FET  13  ON and OFF, the control device  40  converts the electrical power of the electric storage battery  11  and the electrical power generated by the alternator  200 , and supplies electrical power to the on-vehicle battery  7  and the auxiliary device  8 . Each of a current signal I-Signal  1  from a current sensor  17  for the electric storage battery  11 , a current signal I-Signal  2  from a current sensor  18  for the output line  12 VOUT, a voltage signal V-Signal  1  connected to the electric storage battery  11 , and a voltage signal V-Signal  2  connected to the output line  12 VOUT, is connected to the control device  40 . 
     Due to the structure described above, it is possible for the control device  40  to recuperate the energy regenerated by the alternator  200  to the electric storage battery  11 , and to control the supply of the electrical power of the alternator  200  and the electric storage battery  11  to the on-vehicle battery  7  and the auxiliary device  8 . Moreover, the leak current that is generated due to the MOS-FET  13  being turned ON and OFF flows at the single electrical spot GND-P, and does not flow to any portion of the vehicle, such as for example the vehicle body frame or the like. Accordingly, it is possible to reduce EMC noise due to leak current. 
     Although, in the example described above, the arm is a combination of the MOS-FET  13  and the diode  14 , it would also be acceptable to utilize a combination of other switching elements, for example of two MOS-FETs, or a combination of an IGBT and a diode, or the like. Furthermore, the primary rectification capacitor  12  and the secondary rectification capacitor  16  are not particularly limited to being particular types of capacitor. For example, it would also be acceptable for the primary rectification capacitor  12  to be a film capacitor, and for the secondary rectification capacitor  16  to be an electrolytic capacitor, or the like. Or it would also be possible to utilize capacitors of other types. In a similar manner, the electric storage battery  11  could also be some type other than an ultra-capacitor. For example, it would also be acceptable for it to be a capacitor unit in which a large number of electrolytic capacitors are connected in parallel, or to be a lithium ion battery or the like. 
       FIG. 3  shows the flow of control operation after a key of the vehicle has been turned ON. As shown by this flow, during engine starting after the key has been turned ON, the control device  40  determines the state of charge SOC of the electric storage battery  1  and the state of the voltage VB of the on-vehicle battery  7 . As a result, when the state of charge SOC is greater than a critical state of charge SOC CR  for engine starting, and moreover the voltage VB is less than a critical voltage VB CR  for engine starting, then the control device  40  drives the MOS-FET  13 , and supplies the electrical power of the electric storage battery  11  to the on-vehicle battery  7  and the starter  4 . At this time, if the voltage difference between the electric storage battery  11  and the on-vehicle battery  7  is greater than a critical voltage ΔV L  for MOS-FET being continuously ON, then the control device  40  turns the MOS-FET  13  ON intermittently, in order for excessive current not to flow; while, when this voltage difference is below that critical voltage, then the control device  40  turns the MOS-FET  13  on continuously. 
     When the starter  4  is driven so as to attempt to start the engine  2 , if the engine has not yet been started, this engine starting is repeated a number of times, for example around three times. After the engine has been started, a changeover is made to the alternator power generation control shown in  FIG. 4 . By turning the MOS-FET  13  intermittently ON, the turning ON and OFF of the MOS-FET  13  is repeated at a fixed or a fluctuating cycle. At this time, voltage control is performed so that the voltage VB of the on-vehicle battery  7  attains some value, for example so that this voltage VB attains the maximum value in the voltage range over which the on-vehicle battery  7  can be used. When the MOS-FET  13  is turned intermittently ON, the voltage difference between the electric storage battery  11  and the on-vehicle battery  7  is periodically detected, and the MOS-FET  13  is kept continuously ON, when this voltage difference has dropped below the critical voltage ΔV L  for MOS-FET being continuously ON. 
     As described above, when the voltage of the on-vehicle battery  70  is not sufficient for engine starting, the electrical power of the electric storage battery  11  is supplied to the starter  4  and to the on-vehicle battery  7 . Due to this, the startability of the engine is enhanced. Furthermore, since the drive method for the MOS-FET  13  is selected to either continuously ON or intermittently ON, accordingly it is possible to reduce the switching loss of the MOS-FET  13  and the diode  14 . 
       FIG. 4  shows the flow of control operation for control of generation of electricity by the alternator, when recuperation of regenerated energy is not being performed after the engine of the vehicle has been started. In this flow, the control device  40  monitors the voltage VB of the on-vehicle battery  7  upon some cycle. When the result is that the voltage VB exceeds the maximum voltage VB H  for the on-vehicle battery, then the generation of power by the alternator  200  is stopped by turning the MOS-FET  13  and the field current I f  OFF, so that the supply of electrical power to the on-vehicle battery  7  and the auxiliary device  8  is stopped. 
     When the voltage VB is less than the maximum voltage VB H , then the control device  40  obtains the voltage difference between the electric storage battery  11  and the on-vehicle battery  7 . When this voltage difference is greater than the critical voltage ΔV L  for MOS-FET being continuously ON, then voltage control for turning the MOS-FET  13  intermittently ON is performed. Furthermore, generation of power by the alternator  200  is stopped by turning the field current I f  OFF. 
     When the voltage difference between the electric storage battery  11  and the on-vehicle battery  7  is less than the critical voltage ΔV L  for MOS-FET being continuously ON, then the control device  40  controls the amount of power generation by the alternator  200 , by turning the MOS-FET  13  continuously ON and fluctuating the field current I f , so that the voltage VB of the on-vehicle battery  7  becomes some value, for example so that it keeps within the voltage range over which the on-vehicle battery  7  can be used. 
     By doing this, during the alternator power generation control, the generation of power by the alternator  200  is stopped when the voltage of the electric storage battery  11  is higher than the voltage of the on-vehicle battery  7  by at least the critical value for MOS-FET being continuously ON. As a result, the power in the electric storage battery  11  is consumed. As the electrical power of the electric storage battery  11  is continuously consumed, finally, the system transits to the state in which the MOS-FET  13  is continuously ON. In this manner, it is possible to reduce the switching losses of the MOS-FET  13  and the diode  14 , or to ensure that such switching losses do not occur at all. 
       FIG. 5  and  FIG. 6  show the flow of control operation when recuperating the regenerated energy of the vehicle  1 .  FIG. 5  shows the flow for operating the alternator  200  with the field current I f . In this flow, during braking of the vehicle  1  with its brakes or by engine braking, when the state of charge SOC of the electric storage battery  11  is below the maximum state of charge SOC H , then the control device  40  determines, based upon a map that are stored in advance, a value to be set for the field current I f  according to the state of charge SOC, the rotational speed of the alternator  200 , the vehicle speed, and so on. It should be understood that, in the map, information is recorded for the optimum value for the field current I f  according to the state of charge SOC, the rotational speed of the alternator  200 , the vehicle speed, and so on. Recuperation control of the alternator  200  is performed by controlling the field current I f  in this manner, and the regenerated energy of the vehicle  1  is recuperated into the electric storage battery  11 . Furthermore, on each period, the control device  40  monitors the state of braking of the vehicle with its brakes or by engine braking, and the state of charge SOC of the electric storage battery  11 . When the result is that the braking of the vehicle with its brakes or by engine braking has ceased, then the system changes over to the alternator power generation control of  FIG. 4 . In addition, the field current I f  is turned OFF when the state of charge SOC of the electric storage battery  11  rises above the maximum state of charge SOC H ; 
     Although, in the above explanation, the map is used for determining the field current I f , it would also be acceptable to provide some other means for performing this determination, for example calculation or the like. 
       FIG. 6  shows the operation of the MOS-FET  13 . In this flow, during braking of the vehicle with its brakes or braking by engine braking, when the voltage VB of the on-vehicle battery  7  is greater than the maximum voltage VB H , then the control device  40  turns the MOS-FET  13  OFF. Due to this, the supply of electrical power from the electric storage battery  11  to the on-vehicle battery  7  and the auxiliary device  8  stops. On the other hand, when the voltage VB of the on-vehicle battery  7  is less than the maximum voltage VB H , then voltage control for the MOS-FET  13  being turned ON intermittently is performed. Moreover, on each period, the control device  40  monitors the state of braking of the vehicle with its brakes or by engine braking, and the state of charge SOC of the electric storage battery  11 . When the result is that the braking of the vehicle with its brakes or by engine braking has ceased, then the system changes over to the alternator power generation control of  FIG. 4 . 
     By the control described above, the regenerated energy of the vehicle is recuperated directly into the electric storage battery  11 . Furthermore, by turning the MOS-FET  13  intermittently ON, it is possible to keep the on-vehicle battery voltage VB at this time fixed, or within some range. Due to this, during the recuperation of regenerated energy into the electric storage battery  11 , the on-vehicle battery voltage VB does not experience suppression. Accordingly, it becomes possible to recuperate regenerated energy at high capacity, and thereby the fuel consumption of the vehicle is enhanced. 
     While, in the above explanation, the regenerated energy is recuperated during braking with the brakes or braking using engine braking, it would also be acceptable for this to be recuperated during some other state, such as during high speed travel when the engine load is comparatively low, or the like. 
       FIG. 7  shows examples of transitions of the vehicle speed, the alternator load, the electrical power generated by the alternator, the state of charge SOC of the electric storage battery, and the on-vehicle battery voltage VB, while the vehicle  1  is traveling under a specific condition. After the key is turned ON at the timing shown by the circled numeral “ 1 ”, as the vehicle  1  travels while gaining speed, the alternator  200  generates electricity, and supplies electrical power to the on-vehicle battery  7  and the auxiliary device  8 . The state of charge SOC of the electric storage battery  11  at this time is low, and the voltage of the electric storage battery  11  is equal to that of the on-vehicle battery  7 . Accordingly, the MOS-FET  13  is continuously ON, and no electrical power conversion loss occurs. 
     Thereafter, the vehicle  1  starts to decelerate at the timing shown by the circled numeral “ 2 ”, and stops at the timing shown by the circled numeral “ 3 ”. During this period, the alternator  200  generates power at high load, and the regenerated energy of the vehicle  1  is recuperated into the electric storage battery  11 . Due to this, the state of charge SOC of the electric storage battery  11  and its voltage rise. In a similar manner, the voltage of the on-vehicle battery  7  also rises. At this time, the fluctuation of the on-vehicle battery voltage VB due to the elevation of the voltage of the on-vehicle battery  7  is kept within a predetermined range, for example within a range in which no influence is exerted upon the auxiliary device  8  or the like, by the MOS-FET being turned intermittently ON. Moreover, the electric storage battery  11  does not experience any influence from the voltage of the on-vehicle battery  7 , so that recuperation of the regenerated energy is possible within the range of the state of charge SOC that can be used. During this recuperation of the regenerated energy, the alternator  20  is controlled so that the load remains almost constant, or so that fluctuation of the load upon the alternator imparts almost no sense of discomfort to the persons riding in the vehicle in terms of sensing the operation of deceleration of the vehicle. 
     After the recuperation of the regenerated energy up to the timing shown by the circled numeral “ 3 ”, the state of charge SOC of the electric storage battery  11  is high. Accordingly, generation of power by the alternator  200  is stopped, and electrical power is supplied to the on-vehicle battery  7  and the auxiliary device  8  from the electric storage battery  11 . At this time, since the load upon the alternator  200  is minimum, accordingly the load upon the engine  2  is decreased and the fuel consumption of the vehicle is enhanced. 
     At the timing shown by the circled numeral “ 4 ”, the state of charge SOC of the electric storage battery  11  becomes equal to the minimum value within the hypothesized SOC range, or to the voltage of the on-vehicle battery  7 . The alternator  200  starts power generation at this timing, and supplies electrical power to the on-vehicle battery  7  and the auxiliary device  8 . At this time the MOS-FET  13  becomes continuously ON, and the conversion loss of electrical power becomes zero. The above operations are repeated by the vehicle. 
     At the timing shown by the circled numeral “ 5 ”, recuperation of the regenerated energy is performed when the state of charge SOC of the electric storage battery  11  is high. At this time, due to the control operation shown in  FIG. 5 , the amount of electrical power generated by the alternator  200  is set to be low as compared to when the state of charge SOC is low. As a result, control of power generation by the alternator  200  is performed so that the load during recuperation of energy remains almost constant, or so that fluctuation of the load upon the alternator imparts almost no sense of discomfort to the persons riding in the vehicle in terms of sensing the operation of deceleration of the vehicle. 
     At the timing shown by the circled numeral “ 6 ”, the key of the vehicle is turned to OFF. After this timing, if the state of charge SOC of the electric storage battery  11  is high and the voltage of the electric storage device  11  is in a high state, for example it is greater than or equal to a voltage that is safe for the human body, thereafter the electric storage battery  11  is discharged by a discharge resistor or the like down to a predetermined voltage, for example down to a voltage that is safe for the human body. After the electric storage battery  11  has been discharged, then, this state of charge SOC is maintained so that the electric storage battery  11  is able to supply its stored electrical power to the starter  4  at the next time that the key is turned to ON and engine starting is to be performed. By the above, along with this vehicle  1  being able to recuperate regenerated energy at high capacity, the fuel consumption is also greatly enhanced, since this electrical power is utilized at high efficiency. 
       FIG. 8  shows examples of ways in which the electric storage battery  11  may be connected, according to the present invention. In the upper left of this figure, the positive electrode of the electric storage battery  11  is connected to the primary rectification capacitor  12  and the alternator  200  via the switch  19  that consists of a P-channel MOS-FET. The control signal line of the switch  19  is connected to the control device  40 . In the upper right of the figure, an example is shown in which the switch  19  is an N-channel MOS-FET and is connected to the negative electrode side of the electric storage battery  11 ; and in the lower portion of the figure an example is shown in which the switch  19  is a mechanical switch. The electric storage battery  11  may be connected by any one of the methods described above. 
     The control device  40  cuts off the switch  19  when the voltage of the electric storage battery  11  goes into some anomalous state, for example when a voltage that is greater than the withstand voltage of the electric storage battery  11  is applied since two or more on-vehicle batteries in the vehicle are erroneously connected in series, or the like. Due to this, it is possible to prevent application of a voltage in a range that exceeds the withstand voltage of the electric storage battery  11 . In the above explanation, instead of the switch  19 , it would also be acceptable to employ some other type of switching means, such as for example an IGBT or an electromagnetic switch or the like. 
       FIG. 9  shows an example of a block diagram of a non-insulated type electric power conversion device according to the present invention, in which two arms that consist of MOS-FETs  13   a  and  13   b  and diodes  14   a  and  14   b  are respectively connected to reactors  15   a  and  15   b.  The other ends of each of the reactors  15   a  and  15   b  are connected to the secondary rectification capacitor  16 . The two arms are both connected in parallel to the primary rectification capacitor  12 . The gates of the MOS-FETs  13   a  and  13   b  are connected to the control device  40 . The control device  40  performs ON/OFF control of the MOS-FETs  13   a  and  13   b  by these gates. At this time, as shown in  FIG. 10 , the control device  40  performs control so that the phase difference between the ON/OFF timing of the MOS-FET  13   a  and the ON/OFF timing of the MOS-FET  13   b  is approximately 180°. 
     Since, by doing this, the ripple current of the secondary rectification capacitor  16  that is created by the switching of the MOS-FETs  13   a  and  13   b  becomes small, accordingly it is possible to make the secondary rectification capacitor  16  smaller. Moreover, when a problem such as, for example, a connection fault or the like has occurred with one of the MOS-FETs  13   a  and  13   b,  or with one of the diodes  14   a  and  14   b,  or with one of the reactors  15   a  and  15   b,  then it is still possible to supply the electrical power of the alternator  200  or of the electric storage battery  11  to the on-vehicle battery  7  and the auxiliary device  8 , via the arm and the reactor in which no problem is occurring. 
     Embodiment 2 
       FIG. 11  shows another vehicle that is equipped with an electric storage device according to the present invention. In  FIG. 11 , instead of the alternator  200  of the vehicle  1  shown in  FIG. 1 , a motor generator  30  consisting of a three phase AC electric motor that directly drives an engine  2  or vehicle wheels  6 A and  6 B and also performs power generation, and a motor controller  500 , are mounted to a vehicle  1 A. 
     The motor controller  500  controls the generation by the motor generator  30  and also its drive force. Due to this control, the AC electrical power generated by the motor generator  30  is converted into DC electrical power, and thereby regenerated energy is recuperated by the electric storage device  100 . Moreover, electrical power is supplied via the electric storage device  100  to the on-vehicle battery  7  and the auxiliary device  8 . Furthermore, by the control performed by the motor controller  500 , the DC electrical power of the electric storage device  100  or the on-vehicle battery  7  is converted into AC electrical power, and is supplied to the motor generator  30 . The other structural components shown in  FIG. 11  are the same as those shown in  FIG. 1 . 
     Although, in the example shown in  FIG. 11 , a vehicle is shown in which the engine drives the front wheels  6 A and  6 B, this is not to be considered as being limitative of the present invention. For example, the present invention could also be applied to a vehicle in which the engine drives the rear wheels  10 A and  10 B, or to a vehicle in which all four wheels are driven, or to a truck that is equipped with six or more wheels, or to a towing vehicle such as a trailer. Furthermore, while in the example of  FIG. 11  the motor generator  30  is linked to the engine  2  by the belt  9 , it would also be acceptable to arrange to link the motor generator  30  and the engine  2  by some other means. For example, it would be acceptable to arrange to link them by a chain. Moreover, it would also be acceptable to arrange to mount the motor generator  30  between the transmission  3  and the engine  2 , and to link it to the crank shaft or to a shaft within the transmission  3 . 
     Furthermore, it would be acceptable for the voltage of the battery  7  to be, not 12V like an ordinary passenger car, but for example 24V or 42V. Moreover, the electric storage device  100  may not only be mounted in the engine compartment, but also in the trunk or the passenger compartment or the like. It should be understood that while, with this vehicle  1 A, the engine  2  is started using the motor generator  30  or the starter  4 , the present invention could also be applied to a vehicle in which only the motor generator  30  is used for starting the engine  2 . In this case, the starter  4  would not need to be provided. For the motor generator  30 , instead of a three phase AC electric motor, it would also be acceptable to use a two phase coil, or one having some other number of multiple phases; and, moreover, it would also be acceptable to employ a field winding type electric motor. 
       FIG. 12  shows a block circuit diagram of the motor controller  500  shown in  FIG. 11 . This motor controller  50  includes a semiconductor device  51  that consists of MOS-FETs, a capacitor  52  consisting of an electrolytic capacitor and connected to the DC output side of the semiconductor device, a drive circuit  53  that drives the semiconductor device  51 , and a control circuit  54  that controls the drive circuit  53 . 
     The phase coils of the motor generator  30  are connected to the semiconductor device  51 . The negative electrode sides of the capacitor  52  and the semiconductor device  51  are grounded to the earth of the vehicle. The control circuit  54  receives a signal from a position sensor  56  of the motor generator  30  attached thereto and signals from current sensors  55   a  through  55   c  that detect the phase currents of the motor generator  30 , and drives the semiconductor device  51  via the drive circuit  53 . Due to this, the power generated by the motor generator  30  and its drive force are controlled. 
     Although in the above explanation, with the example shown in  FIG. 12 , the semiconductor  51  consists of MOS-FETs, it would also be acceptable to make it from other switching elements, for example from IGBTs and flywheel diodes. Moreover, it would also be acceptable to utilize a film capacitor or the like for the capacitor  52 . While, in the example shown in  FIG. 12 , the number of the current sensors  55   a  through  55   c  is three, it would also be acceptable for this number to be two. Furthermore, instead of these current sensors, it would also be acceptable to utilize, for example, shunt resistors. Instead of the position sensor  56 , it would also be acceptable to utilize, for example, a Hall IC. It would also be acceptable to arrange to connect the negative electrode sides of the capacitor  52  and the semiconductor device  51  to the GND-P of the electric storage device  100  shown in  FIG. 2 . Moreover, it would also be acceptable to arrange to utilize a field winding type electric motor for the motor generator  30 , and for the motor controller  500  to use a current control circuit made from a switching element or the like, so as to control the winding line current. 
       FIG. 13  shows the flow of control operation during starting of the engine of the vehicle  1 A. The vehicle  1 A is endowed with an idling stop function (i.e., with a function of stopping idling when the vehicle speed becomes zero). Upon idling start after the key has been turned ON or after an idling stop, the control circuit  54  selects engine starting by any one of the starter  4 , or the motor generator  30 , or the starter  4  and the motor generator  30 , on the basis of the SOC of the electric storage battery  11 , the temperature of the cooling water of the engine  2 , the voltage of the on-vehicle battery  7 , and so on. For example engine starting by the motor generator  30  may be selected, when the SOC of the electric storage battery  11  is sufficient in terms of the electrical power and the drive force of the motor generator  30  that are necessary during engine starting. It should be understood that, when starting by the starter  4  has been selected, then the power of the electric storage battery  11  is supplied to the starter  4  by the same control operation as in  FIG. 3 . Due to this, the engine startability of the vehicle  1 A is enhanced. It should be understood that this procedure could also be applied to a vehicle that is not endowed with any idling stop function. 
       FIG. 14  shows the flow of control operation when retrieval of regenerated energy is not being performed after the engine of the vehicle  1 A has been started. Here, only the alternator of  FIG. 4  has been replaced by the motor generator, and the operation is the same. Due to this, the electrical energy of the electric storage battery  11  is consumed after engine starting, and when recuperation of regenerated energy is not being performed, and finally the MOS-FET  13  is kept continuously ON, and generation control of the motor generator  30  is performed. Due to this, the switching losses in the MOS-FET  13  and the diode  14  are reduced or do not occur. 
       FIGS. 15 and 16  show the control operation when regenerated energy of the vehicle  1 A is being recuperated. Here, only the alternator of  FIG. 5  has been replaced by the motor generator, and the operation is the same. The map determines the amount of electrical power generated by the motor generator. However, it would also be acceptable to arrange to perform this determination of the amount of electrical power generated by the motor generator by some means other than a map, for example by calculation. 
     By the above control, the regenerated energy of the vehicle is directly recuperated into the electric storage battery  11 . Moreover, the on-vehicle battery voltage VB at this time can be held constant by turning the MOS-FET  13  intermittently ON. By doing this, it becomes possible to recuperate energy at high capacity, since the recuperation of energy into the electric storage battery  11  does not experience suppression by the voltage of the on-vehicle battery. 
     It should be understood that while, in the above explanation, the regenerated energy is recuperated during deceleration while braking with the brakes or while braking by using engine braking, it would also be acceptable to perform such recuperation in other circumstances, as during high speed travel when the engine load is comparatively low, or the like. 
     From the above, according to this vehicle  1 A, it is possible to obtain similar advantageous effects as those obtained with the vehicle  1 . In other words, the transitions of the vehicle speed, the load of the motor generator that corresponds to the alternator, the electrical power generated by the motor generator, the SOC of the electric storage battery, and the on-vehicle battery voltage, while the vehicle  1 A is traveling under the specific traveling condition, are the same as those shown in  FIG. 7 . Due to this, it is possible to recuperate energy at high capacity, and to reduce the electrical power conversion losses. Moreover, during the period in  FIG. 7  in which the vehicle speed becomes zero, the vehicle  1 A is idling stopped. During engine starting when traveling is to commence, the SOC of the electric storage battery is kept in a high state due to the regenerated energy that has been recuperated, and also, in a similar manner, the voltage of the electric storage battery is kept in a high state. Accordingly, if engine starting by the motor generator  30  has been selected by the control of  FIG. 13 , then the voltage applied to the motor generator becomes high, so that it is possible to drive the motor generator  30  at high output. Therefore, when starting the engine after idling stop, it becomes possible to supply fuel only after having raised the engine rotational speed to, for example, the idling rotational speed of the engine; and it even becomes possible to perform traveling with the motor generator  30  before engine starting. 
     To this vehicle  1 A, it is also possible to apply the structure shown in  FIGS. 8 and 9 , and similar advantageous effects may be obtained. 
       FIG. 17  is a figure showing an example of a method of communication between the control device  40  of the electric storage device  100 , the control circuit  54  of the motor controller, and a control unit  600  that is an upper controller than the control device  40  and the control circuit  54 . The control device  40 , the control circuit  54 , and the control unit  600  mutually communicate via a CAN line. Due to this, the control unit  600  is able to control the electric storage device  100  and the motor generator  30  via the control device  40  and the control circuit  54 , and it is possible to perform the control operation for the vehicle  1 A described above in a simple and easy manner. Although, in the above explanation, the control unit  600  is used, it is not absolutely necessary to provide this control unit  600  for controlling the electric storage device  100  and the motor generator  30 . For example, it would be acceptable to arrange for the control device  40  to control the motor generator  30  via the control circuit  54 , and for the control circuit  54  to control the electric storage device  100  via the control device  40 . Moreover, it would also be acceptable to utilize some communication means other than CAN, for example serial communication or the like.