JP4054776B2 - Hybrid system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hybrid system in which electric double layer capacitors are employed as power storage units in addition to a battery, where torque assist performance by a motor and power regeneration performance by a generator are enhanced by using these capacitor power storage units and the battery depending on the traveling conditions or working conditions, and long time torque assist by the motor can be ensured. <P>SOLUTION: When the quantity of power stored in a capacitor power storage unit 21 exceeds a specified level, a first change-over switch 30a is turned on while a second change-over switch 30b is turned off and the capacitor power storage unit 21 stores power generated from a motor/generator 11 and supplies power to the motor/generator 11. When the quantity of power stored in the capacitor power storage unit 21 drops below the specified level, the first change-over switch 30a is turned off while the second change-over switch 30b is turned on and power is supplied from a battery 28 to the motor/generator 11. <P>COPYRIGHT: (C)2005,JPO&amp;NCIPI

Description

  The present invention relates to a hybrid system that extracts at least a mechanical driving force and electric power from an engine, and more particularly to a power storage system in the hybrid system.

  In recent years, in working machines such as automobiles and construction machines, a generator using an engine as a drive source, a battery (secondary battery) as a power storage device that stores electric power generated by the generator, and supply from this battery A motor (electric motor) that is driven using the generated electric power, and the battery is stored by the generator and the engine is torque-assisted by the motor, so that the engine can be used effectively while saving energy. So-called hybrid systems that enable efficient operation are adopted, and such technology is becoming the mainstream in the future.

  In the hybrid system as described above, in order to enable a large amount of power to be supplied to the motor that assists the engine in a short time, such as when an automobile is accelerated or when a heavy work load is applied to the work machine. In addition, in order to improve the power regeneration efficiency of the power storage device by the generator, it is proposed to use an electric double layer capacitor having a low internal resistance, a high output density, and a high charge / discharge efficiency as a power storage device. (For example, refer to Patent Document 1).

JP 2002-120602 A

  However, since the electric double layer capacitor used as a power storage device has the properties as described above, it is suitable for charging and discharging in a short time, but it is difficult to supply power for a long time. In other words, since the electric double layer capacitor has a lower energy density than the battery, there is a problem that it is impossible to supply power to the motor when the motor assists for a long time. Therefore, in the present invention, an electric double layer capacitor is used as a power storage device in the hybrid system, and a battery is provided side by side, and the capacitor power storage device and the battery are used in accordance with a traveling situation and a work situation, thereby generating torque generated by the motor. Provided is a hybrid system that improves assist performance and power regeneration performance by a generator, and enables long-time torque assist by a motor.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

The hybrid generator according to claim 1, comprising: an engine (2); a motor that assists the engine (2); a control unit that controls the motor; and a generator that uses the engine as a drive source. A capacitor power storage device (21) that stores power generated from the motor and supplies power to the motor, and a first constant current that performs constant current control of charging current from the generator to the capacitor power storage device (21). A control circuit (100), a battery (28) that supplies power to the motor, and a first changeover switch (30a) that is controlled by the control means to turn on and off the capacitor power storage device (21). And a second changeover switch (30b) that is controlled by the control means to turn on / off the power supply to the battery. However, if the value exceeds a preset value, the first changeover switch (30a) is turned on and the second changeover switch (30b) is turned off, and the capacitor power storage device (21) When the electric power is stored from the generator and the electric power is supplied to the motor, and the amount of power stored in the capacitor power storage device (21) falls below a predetermined value, the first changeover switch ( 30a) is turned off and the second changeover switch (30b) is turned on to supply power from the battery (28) to the motor. In this state, the battery voltage of the battery (28) is When the value exceeds a preset value, the first changeover switch (30a) is turned off and the second changeover switch (30b) is turned on. Then, the battery (28) directly stores the generated power from the generator and supplies power to the motor, and the battery voltage of the battery (28) is lower than a preset specified value, and When the voltage drop rate per unit time becomes larger than a preset specified value, the first changeover switch (30a) is turned on, and the electric power from the capacitor power storage device (21) to the motor is turned on. Supply .

According to claim 2, in the hybrid system according to claim 1, a capacitor power storage device (21) that stores power generated from the generator and supplies power to the motor, and the capacitor power storage from the generator. A first constant current control circuit (100) for performing constant current control of charging current to the device (21) is provided, and the capacitor voltage of the capacitor power storage device (21) is lower than the battery voltage of the battery (28). In this case, the battery (28) allows the capacitor power storage device (21) to be charged, and the second constant current control performs constant current control of the charging current from the battery (28) to the capacitor power storage device (21). A circuit (100a) is provided .

  As effects of the present invention, the following effects can be obtained.

According to the first aspect of the present invention, normally, the capacitor power storage device having a higher output density than the battery stores the generated power from the generator and supplies the power to the motor, so that the torque assist performance and power generation by the motor can be achieved. The power regeneration performance of the machine can be improved, and it is possible to cope with sudden load fluctuations of the engine. When the amount of power stored in the capacitor power storage device decreases, power is supplied to the motor by a battery having a battery capacity capable of supplying an instantaneous large current to the motor. For example, when the power is extended for a long time, the power shortage of the capacitor power storage device having a lower energy density than that of the battery can be compensated.
Also, by providing a first changeover switch and a second changeover switch and controlling them to a predetermined level, when supplying power from the battery to the motor, an excessive current instantaneously flows from the battery to the capacitor power storage device. Therefore, the capacitor power storage device having a low internal resistance can be protected from being destroyed or broken. When the capacitor power storage device is recharged, the generated power from the generator is not supplied to the battery, so that the capacitor power storage device can be charged efficiently.

  According to the second aspect of the present invention, the power storage device that normally supplies power to the motor by a battery and supplies power to the motor only when necessary, such as when the engine is suddenly subjected to a high load, is a capacitor. Since it switches to the power storage device, it can prevent voltage drop (abrupt voltage drop caused by instantaneous battery discharge due to sudden load fluctuation) and prevent malfunction of the system, and long-time power to the motor Can be supplied. In other words, as a power storage device that supplies power to a motor that performs torque assist, a battery can be used for a continuous load, and a capacitor power storage device can be used for an instantaneous and suddenly high load. Thus, it is possible to appropriately use the high energy density of the capacitor and the high output density of the capacitor power storage device. As a result, a long-time torque assist by the motor is possible even in an operation where a sudden load fluctuation occurs.

  According to the third aspect of the present invention, since the capacitor power storage device charged at any time by the battery can store the generated power from the generator and supply the power to the motor, the torque assist performance by the motor and the power regeneration of the generator can be achieved. The performance can be improved, and it is possible to cope with a rapid load fluctuation of the engine for a long time.

  Next, embodiments of the invention will be described. 1 is a diagram showing an example of a configuration of a hybrid system according to the present invention, FIG. 2 is a diagram showing a configuration of a constant current control circuit, FIG. 3 is a diagram showing a control flow of constant current control by the constant current control circuit, and FIG. Is a diagram showing the configuration of the equalization control circuit, FIG. 5 is a diagram showing changes in the battery voltage, FIG. 6 is a diagram showing another configuration of the power storage system unit, and FIG. FIG.

  First, the configuration of the hybrid system will be described with reference to FIG. In this embodiment, a hybrid system having a motor generator 11 having both functions of a motor and a generator will be described. However, the present invention is not limited to this, and a hybrid having a configuration in which a motor and a generator are separately provided. The effects of the present invention can also be obtained in a system or the like. That is, the present invention can be applied to a hybrid system that can supply power from a battery to a motor that assists the engine and store the battery by a generator in accordance with a load on the engine. In this hybrid system, the output shaft of the engine 2 can be driven by both the engine 2 and the motor generator 11 that functions as a motor. The driving force extracted from the output shaft portion is transmitted to a load 7 such as a traveling portion or various working portions in an automobile or a work machine via a clutch portion or a power transmission device.

  The motor generator 11 is attached with the drive shaft connected to the crankshaft of the engine 2, and is electrically connected to the power storage system unit 20 via the inverter converter 12. Further, the motor generator 11 functions as a motor or a generator, performs torque assist of the engine 2 that drives the load 7 by functioning as a motor, and functions as a generator to generate the generated power and the load 7. The regenerative power generated by the inertial force on the side is stored in the power storage device. The inverter converter 12 functions as an inverter or a converter, and converts input power into direct current or alternating current and also converts it into a predetermined voltage and frequency. The power storage system unit 20 includes a step-up / step-down chopper 22, a capacitor power storage device 21, and a battery 28, and operates according to each operation mode of the power storage system unit 20, as will be described later. The engine 2, the inverter converter 12, and the step-up / down chopper 22 are connected in communication with the system controller 1 as control means, and the hybrid system is controlled by the system controller 1.

  In the hybrid system having such a configuration, as described above, the motor generator 11 having functions as a motor and a generator exhibits each function in accordance with a work situation or the like. When the motor generator 11 is operated as a motor, electric power is supplied from the capacitor power storage device 21 or the battery 28. Electric power supplied from the capacitor power storage device 21 or the battery 28 is input to the inverter converter 12 via the step-up / step-down chopper 22. At this time, the step-up / step-down chopper 22 functions as a step-up chopper, boosts the voltage of power supplied from the capacitor power storage device 21 or the battery 28 to a predetermined voltage, and outputs it to the inverter converter 12. At this time, the inverter converter 12 functions as an inverter, converts the input power into a predetermined value, and supplies the converted power to the motor generator 11. Thus, when the motor generator 11 operates as a motor, the driving force is transmitted from the driving shaft of the motor generator 11 connected to the crankshaft of the engine 2 to the engine 2 to perform torque assist.

  On the other hand, when the motor generator 11 is operated as a generator, the motor generator 11 is operated by the driving force of the engine 2 to generate power. The electric power generated by the motor generator 11 is input to the inverter converter 12. At this time, the inverter converter 12 functions as a converter. Then, the electric power subjected to the predetermined conversion by the inverter converter 12 is input to the capacitor power storage device 21 or the battery 28 via the step-up / step-down chopper 22 and stored. At this time, the step-up / step-down chopper 22 functions as a step-down chopper and steps down the electric power output from the inverter converter 12 to a predetermined voltage and stores it in the capacitor power storage device 21.

  Such torque assist and power generation by the motor generator 11 are applied to the engine 2 on the basis of the speed command (motor command) transmitted from the system controller 1 to the inverter converter 12, the fuel injection amount of the engine 2, the engine speed, and the like. This is performed according to the load. That is, when the load applied to the engine 2 becomes higher than a certain value, the motor generator 11 is operated as a motor, torque assist of the engine 2 is performed, and when the load applied to the engine 2 becomes lower than a certain value, the motor generator 11 is operated. Is operated as a generator, and the power generated by the motor generator 11 is controlled to be stored in the capacitor power storage device 21 or the battery 28.

  Moreover, when applying the hybrid system of such a structure to a small working machine etc., it can also be set as the structure which does not use the said raising / lowering chopper 22. That is, when the output of the motor generator 11 that operates as a motor is relatively small and does not affect the operation, such as a small working machine, a high voltage is required to exert the motor function of the motor generator 11. Therefore, the step-up / step-down chopper 22 may not be used. In this case, the capacitor power storage device 21 and the battery 28 are connected to the inverter converter 12 without going through the step-up / down chopper 22, and the power storage capacities of the capacitor power storage device 21 and the battery 28 correspond to the motor output of the motor generator 11 that operates as a motor. Will be.

  Next, the power storage system unit 20 will be described in detail. The power storage system unit 20 stores the generated power from the motor generator 11 that operates as a generator and supplies the DC power to the inverter converter 12 and the capacitor power storage device 21 that supplies power to the motor generator 11 that operates as a motor. A step-up / down chopper 22 that performs charge / discharge control on the capacitor power storage device 21 and a battery 28 that supplies power to the motor generator 11 that operates as a motor are provided. As described above, when the hybrid system does not use the step-up / step-down chopper 22, the power storage system unit 20 has a control unit having the same function as the control function of the capacitor power storage device 21 by the step-up / step-down chopper 22. Is provided separately, or the system controller 1 is provided with a control function of the capacitor power storage device 21 by the step-up / step-down chopper 22.

  The power storage system unit 20 includes a current / voltage sensor 25 that detects charge / discharge current of the capacitor power storage device 21 and a capacitor voltage of the capacitor power storage device 21 and a battery voltage of the battery 28, and a motor generator that operates as a generator. 11 includes a constant current control circuit 100 that performs constant current control of charging current from 11 to the capacitor power storage device, and an equalization control circuit 200, and a first changeover switch 30a and a second changeover switch 30b are provided. The first change-over switch 30a and the second change-over switch 30b are composed of a mechanical switch or a semiconductor element such as a power transistor, and the system controller controls the turning on / off thereof. The first changeover switch 30 a is a switch for turning on / off the energization of the capacitor power storage device 21, and the second changeover switch 30 b is a switch for turning on / off the energization of the battery 28.

  The capacitor power storage device 21 includes a plurality of (two connected in series in this embodiment) electric double layer capacitors (hereinafter referred to as “capacitor modules”) 21 a and 21 b that are connected in a predetermined manner. That is, the equalization control circuit 200 is for equalizing the voltages of the capacitor modules 21a and 21b. Therefore, it is used when the capacitor power storage device 21 has a plurality of capacitor modules, and when the capacitor power storage device 21 is configured by a single capacitor module, the power storage system unit 20 does not use the equalization control circuit 200. It can also be.

  As described above, when the motor generator 11 operates as a motor, the step-up / step-down chopper 22 boosts the electric power supplied from the capacitor power storage device 21 to the motor generator 11 and the motor generator 11 operates as a generator. Is for stepping down the electric power generated by the motor generator 11 and storing it in the capacitor power storage device 21. The step-up / step-down chopper 22 receives a charge limiter, a voltage limiter, a charge start command, and a charge stop command from the system controller 1. Such a signal is input. The current / voltage sensor 25 detects the current between the step-up / step-down chopper 22 and the capacitor power storage device 21 and detects the capacitor voltage of the capacitor power storage device 21 and the battery voltage of the battery 28. The current value / voltage value detected by the sensor 25 is input to the step-up / step-down chopper 22.

  Next, the constant current control circuit 100 and the equalization control circuit 200 will be described in detail.

<Constant current control circuit 100>
The constant current control circuit 100 will be described. The constant current control circuit 100 is a control circuit for always controlling a current value supplied to the capacitor to a specified value. Thus, by always setting the current value supplied to the capacitor power storage device 21 to a specified value, an excessive current flows into the capacitor power storage device 21 to prevent the capacitor from being destroyed. is there.

FIG. 2 shows the configuration of the constant current control circuit 100. The constant current control circuit 100 is connected in parallel to a capacitor power storage device 21 composed of a plurality of capacitor modules 21a and 21b, whereby the input / output terminal of the step-up / down chopper 22 arranged on the load side is Capacitor power storage device 21 and constant current control circuit 100 are connected in parallel. In FIG. 2, the current of the current value IMAX is output from the step-up / step-down chopper 22, is shunted at the terminal 110a, the current of the current value Io is supplied to the capacitor power storage device 21, and the current of the current value IDS is a constant current. It is supplied to the control circuit 100 (IMAX≈Io + IDS). Reference numeral 101 denotes a MOSFET as a current control element, and the current value IDS of the current shunted at the terminal 110a is changed and set in accordance with the value of the gate source voltage VGS as the control input voltage of the MOSFET 101. Yes. The terminal 110 a is a terminal arranged between the plus terminal of the step-up / down chopper 22 and the plus terminal of the capacitor power storage device 21. A control voltage SV is input from the system controller 1 (see FIG. 1). Reference numeral 102 denotes a first inverting amplifier. The first inverting amplifier 102 receives the divided voltage Va of the control voltage SV and the voltage Vb at the terminal 110b. The terminal 110b is a terminal arranged between the minus terminal of the step-up / down chopper 22 and the minus terminal of the capacitor power storage device 21. Reference numeral 103 denotes a shunt resistor as a constant voltage element connected in series to the capacitor power storage device 21. The voltage Vb is determined by the shunt resistor 103 and the current value Io of the current flowing through the capacitor power storage device 21. Become. Here, the reason why the shunt resistor 103 (resistance value r) is used is to reduce variation in the current value Io. Reference numeral 104 denotes a second inverting amplifier. The output voltage VOP of the first inverting amplifier 102 and the ground voltage are input to the second inverting amplifier 104. The first inverting amplifier 102 and the second inverting amplifier 104 constitute a voltage comparison circuit between the voltage Vb of the shunt resistor 103 and the control voltage SV (a divided voltage Va). The output is a gate-source voltage VGS that is a control input voltage of the MOSFET 101.

  The constant current control circuit 100 performs the constant current control as shown in the control flow of FIG. In this flow, the voltage Vb is set by setting (decreasing or increasing) the control voltage SV input from the system controller 1 to the constant current control circuit 100, and determined by the voltage Vb and the shunt resistor 103. It shows that the current value Io to be set is set to a specified value. First, the flow in which the current value Io is corrected to the specified value when the current value Io increases from the specified value will be described. When the current value Io increases from the specified value and the voltage Vb becomes larger than the divided voltage Va of the set control voltage SV (step 401), the output voltage VOP in the first inverting amplifier 102 decreases (step 402). The gate source voltage VGS that is the output of the second inverting amplifier 104 is increased (step 403). As the gate source voltage VGS increases, the current value IDS of the current passing through the MOSFET 101 increases (step 404), and as the current value IDS increases, the current value Io of the current flowing through the capacitor power storage device 21 decreases. (Step 405). When the current value Io decreases, the value of the voltage Vb determined by the resistance value of the shunt resistor 103 decreases (step 406), and the divided voltage Va and the voltage Vb determined by the control voltage SV are set to be substantially the same ( Step 407). As described above, when the current value Io increases from the specified value, the voltage Vb is decreased until it becomes substantially the same as the divided voltage Va, and as a result, the current value Io is corrected to the specified value. Become. That is, the current value Io is set to a specified value.

  Similarly, the case where the current value Io is reduced from the specified value will be described. In this case, the voltage Vb is smaller than the divided voltage Va of the set control voltage SV (step 411). As a result, the output voltage VOP in the first inverting amplifier 102 increases (step 412), and the gate-source voltage VGS that is the output of the second inverting amplifier 104 decreases (step 413). Then, the current value IDS of the current passing through the MOSFET 101 is decreased by the decrease of the gate source voltage VGS (step 414), and the current value Io of the current flowing through the capacitor power storage device 21 is increased by the decrease of the current value IDS. (Step 415). When the current value Io increases, the value of the voltage Vb determined by the resistance value of the shunt resistor 103 increases (step 416), and the divided voltage Va and the voltage Vb determined by the control voltage SV are set to be approximately the same ( Step 407). As described above, when the current value Io decreases from the specified value, the voltage Vb is increased until it becomes substantially the same as the divided voltage Va. As a result, the current value Io is corrected to the specified value. Become. That is, the current value Io is set to a specified value.

  As can be seen from the above flow, the current value Io is determined by the set voltage (divided voltage Va) of the control voltage SV. By detecting this voltage Vb and changing the control voltage SV, the current value Io is determined. The current value Io can be controlled. That is, according to the constant current control circuit 100 of FIG. 2, it is possible to set the current value Io flowing through the capacitor power storage device 21 as a specified value by setting the control voltage SV, and the current value Io is set to the specified value. It is possible to control (control to a constant current).

  As described above, the constant current control circuit 100 includes the current control element (MOSFET 101) connected in series between the charging path 110A of the capacitor power storage device 21 and the ground terminal, and the current stabilization element connected in series with the capacitor power storage device 21. (Shunt resistor 103), and a voltage comparison circuit for the voltage of the shunt resistor 103 and the control voltage SV (a divided voltage Va), and the output of the voltage comparison circuit is used as the control input voltage (gate source voltage VGS) of the MOSFET 101. Thus, the current value Io flowing through the capacitor power storage device 21 can be set as a specified value by setting the control voltage SV, and the current value Io is controlled to the specified value (constant). It is possible to control the current). Then, by controlling the value of the current supplied to the capacitor power storage device 21 to always be a specified value, an excessive current flows into each of the capacitor modules 21a and 21b, thereby preventing the capacitor power storage device 21 from being destroyed. it can. Further, even when overcharge is caused by the step-up / step-down chopper 22, the current of the current value IDS can be released to the constant current control circuit 100 at the terminal 110a, and the failure of the capacitor power storage device 21 can be prevented.

<Equal control circuit 200>
Next, the equalization control circuit 200 will be described. The equal control circuit is a control circuit for equalizing the inter-terminal voltages of the capacitor modules connected in series in the capacitor power storage device 21. And, in this way, the voltage between terminals of each capacitor module connected in series is equalized, thereby increasing the voltage between terminals of a specific capacitor module and trying to prevent such a problem that the charging efficiency is lowered. Is. This also prevents the occurrence of a problem that the voltage between the terminals of a specific capacitor module exceeds the withstand voltage even when charging and discharging are repeated.

  FIG. 4 shows the configuration of the equalization control circuit 200. The equalization control circuit 200 is configured by providing shunt circuits 200 a and 200 b for the capacitor modules 21 a and 21 b connected in series in the capacitor power storage device 21, respectively. The shunt circuits 200a and 200b attempt to control the magnitude of the current value Iout of the current input to the capacitor modules 21a and 21b by shunting the current of the current value It at the terminals 120a and 120b, respectively. As shown in FIG. 4, the capacitor modules 21a and 21b are connected in parallel to the step-up / step-down chopper 22 as the capacitor power storage device 21, and the terminal voltage of the step-up / step-down chopper 22 is set as the charging voltage VMAX. The sum of the inter-terminal voltages 21a and 21b corresponds to the charging voltage VMAX. In addition, it is a desirable state that the voltage between terminals of each capacitor module 21a and 21b becomes uniform.

  In FIG. 4, reference numerals 131a and 131b denote resistors having the same resistance value, whereby currents having the same current value Iin are supplied to the terminals 120a and 120b, respectively. Of the currents shunted at the terminals 120a and 120b, the current of the current value Iout is supplied to the capacitor modules 21a and 21b, and the current of the current value It is shunted to the shunt circuits 200a and 200b. Here, 132a and 132b are MOSFETs as current control elements, and the magnitude of the current value Iout is determined by the MOSFETs 132a and 132b. The MOSFETs 132a and 132b are connected in parallel to the capacitor modules 21a and 21b. The gate source voltage VGS as a control input voltage to the MOSFETs 132a and 132b is an output voltage of the error amplifiers 133a and 133b serving as a voltage comparison circuit. The gate source voltage VGS includes the reference voltage VREF and the detection resistors 134a and 135a. It is determined by comparison with the partial pressure VR of 134b and 135b. Reference numerals 136a and 136b denote Zener diodes as constant voltage elements, which are connected in parallel to the capacitor modules 21a and 21b. The zener diodes 136a and 136b avoid self-discharge of the capacitor modules 21a and 21b, and avoid overcharging (overvoltage) of the capacitor modules 21a and 21b. In other words, the Zener diodes 136a and 136b have the property of conducting when the voltage is higher than the set voltage, and thus perform the functions of self-discharge prevention and overvoltage prevention.

  The shunt circuits 200a and 200b having the above configuration have the same configuration. Among these, first, the operation of the shunt circuit 200a will be described. When the charging of the capacitor module 21a proceeds and the capacitor voltage increases, the divided voltage VR increases. As a result, the output of the error amplifier 133a, that is, the gate source voltage VGS increases, and the current value It of the current flowing through the MOSFET 132a increases. When the current value It increases, the current value Iout of the current shunted to the capacitor module 21a side at the terminal 120a is decreased. In this way, the increase / decrease of the current value Iout is controlled by the capacitor voltage. When the capacitor voltage is low, that is, when the amount of charge is small, the current value Iout is increased and the battery is quickly charged, so that full charge is achieved. As the capacitor voltage increases as it approaches, the current value Iout decreases, and overcharging is not performed. When the capacitor module 21a is finally fully charged, the current supply to the capacitor module 21a is terminated. In this way, the capacitor voltage is always kept constant. The above also applies to the operation of the shunt circuit 200b in the capacitor module 21b. That is, when the capacitor power storage device 21 has two or more capacitor modules, a similar shunt circuit is provided in each capacitor module.

  Further, in the above charging, particularly when rapid charging is performed, a difference occurs in the voltages of the capacitor modules 21a and 21b. For example, when the capacitor module 21a is fully charged first. There is. In this case, since current supply to the capacitor module 21a is not performed by the control of the shunt circuit 200a, the capacitor module 21a is not overcharged. On the other hand, during the control by the shunt circuit 200a, the capacitor module 21b is charged, and the capacitor module 21b reaches a fully charged state. In addition, as shown in FIG. 4, by providing the diode 220, when the capacitor module 21b is fully charged first, the current flowing to the capacitor module 21b side may be supplied to the capacitor module 21a. Good.

  As described above, the capacitor modules 21a and 21b that are connected in series in the capacitor power storage device 21 are configured to supply the charge current evenly and to the capacitor modules 21a and 21b. The shunt circuits 200a and 200b for shunting a part of the evenly shunted current are provided, and each of the shunt circuits 200a and 200b includes current control elements (MOSFETs 132a and 132b) connected in parallel to the capacitor modules 21a and 21b. A voltage comparison circuit (error amplifiers 133a and 133b) for comparing the voltage (divided voltage VR) of the capacitor modules 21a and 21b and the reference voltage VREF, and a constant voltage element (zener diode 136a) connected in parallel to the capacitor modules 21a and 21b 136b), and voltage The output of the comparison circuit (error amplifiers 133a and 133b) is applied as the control input voltage (gate source voltage VGS) of the MOSFETs 132a and 132b, whereby the current (current value It) of the charging paths 120A and 120B is discharged. By dividing the current to 120C, overcharge is prevented while keeping the capacitor voltage of each of the capacitor modules 21a and 21b constant. Then, overcharging is prevented, that is, the capacitor voltage is kept lower than the withstand voltage, so that heating, breakage, and failure of the capacitor modules 21a and 21b can be prevented (overcharge). protection). In addition, since both capacitor modules 21a and 21b are finally fully charged, the capacitor power storage device 21 as a whole maintains a high output density (specified output density) even when charging and discharging are repeated. And can take full advantage of the merits of capacitors, such as high responsiveness.

  The power storage system unit 20 having such a configuration has the following operation mode. Hereinafter, each operation mode will be described.

  First, the first operation mode will be described. In this operation mode, power is supplied to motor generator 11 that performs torque assist mainly by capacitor power storage device 21. When the amount of power stored in capacitor power storage device 21 falls below a preset specified value, supply of power from capacitor power storage device 21 to motor generator 11 is stopped, and power to motor generator 11 is supplied by battery 28. Supply.

  That is, in this operation mode, when the charged amount Q of the capacitor power storage device 21 exceeds the preset specified value QN, the first changeover switch 30a is turned on and the second changeover switch 30b. The capacitor power storage device 21 stores the generated power from the motor generator 11 that operates as a generator and supplies the power to the motor generator 11 that operates as a motor. When the charged amount Q of the capacitor power storage device 21 falls below a preset specified value QN, the first changeover switch 30a is turned off and the second changeover switch 30b is turned on, so that the battery 28 and the motor are turned on. It is characterized in that power is supplied to the motor generator 11 that operates as follows.

The amount of electricity stored (remaining capacity) Q of the capacitor power storage device 21 is defined as follows. The capacitance indicating the ability of the capacitor power storage device 21 to store charges is C, and the capacitor voltage of the capacitor power storage device 21 is VC. The storage amount Q is expressed by the following equation (1).
Q = CVC2 / 2 (1)
That is, the storage amount Q of the capacitor power storage device 21 can be grasped from the capacitor voltage VC of the capacitor power storage device. When the capacitor voltage VC is the withstand voltage of the capacitor power storage device 21, the fully charged state of the capacitor power storage device 21 is determined. Will be shown. Based on this equation (1), the charged amount Q of the capacitor power storage device 21 is calculated from the capacitor voltage VC detected by the current / voltage sensor 25 and the capacitance C of the capacitor power storage device 21. The specified value QN is set to, for example, the amount of electricity stored when the capacitor voltage VC is ½ of the withstand voltage of the capacitor electricity storage device 21.

  The amount Q stored in the capacitor power storage device 21 calculated in this way is determined by the system controller 1 whether it exceeds or falls below a preset specified value QN. That is, a prescribed value QN is set in advance in the system controller 1, and in this system controller 1, the stored amount Q of the capacitor power storage device 21 calculated as described above is compared with the prescribed value QN, and the capacitor charge is stored. It is always determined whether the storage amount Q of the device 21 is above or below the specified value QN.

  Under such a determination, in the state where the charged amount Q of the capacitor power storage device 21 exceeds the specified value QN, the power supply to the motor generator 11 at the time of torque assist is performed by the capacitor power storage device 21. That is, in this case, the first changeover switch 30a for turning on / off the energization of the capacitor power storage device 21 is in the on state, and the second changeover switch 30b for turning on / off the energization of the battery 28 is in the off state, Supply of electric power to the motor generator 11 that performs torque assist when the engine 2 is in a high load state is performed by the capacitor power storage device 21. In this case, the capacitor power storage device 21 also stores the generated power from the motor generator 11 that operates as a generator when the engine 2 is in a low load state.

  Then, when the engine 2 is in a high load state or continues for a long time, the amount of charge Q of the capacitor power storage device 21 decreases, and when the amount of power storage Q falls below a specified value QN, the motor by the capacitor power storage device 21 The supply of power to the generator 11 is stopped and is performed by the battery 28 instead. That is, in this case, the first changeover switch 30a is turned off, the second changeover switch 30b is turned on, and the battery 28 supplies power to the motor generator 11 that operates as a motor. . When the amount of power stored in the capacitor power storage device 21 decreases in this way, the battery 28 supplies power to the motor generator 11, so that the battery 28 is a motor when the engine 2 is suddenly subjected to a high load. It is assumed that the battery capacity is such that a large current can be instantaneously supplied to the generator 11. Here, the first changeover switch 30a is turned off when the second changeover switch 30b is turned on in order to supply power from the battery 28 to the motor generator 11. This is to prevent an excessive current from flowing into the power storage device 21 instantaneously.

  As described above, when the storage amount Q of the capacitor power storage device 21 decreases and the power supply to the motor generator 11 by the battery 28 is performed, the subsequent recharging of the capacitor power storage device 21 is performed by the engine. This is performed when the load 2 is in a steady state. That is, in the state where the load on the engine 2 is reduced and the torque assist by the motor generator 11 is no longer necessary, the generated power of the motor generator 11 that operates as a generator by the surplus output of the engine 2 is stored in the capacitor power storage device 21. At this time, the first changeover switch 30a is turned on and the second changeover switch 30b is turned off so that the electric power generated by the motor generator 11 is stored only in the capacitor power storage device 21. In this manner, the capacitor power storage device 21 as the main power storage device in this operation mode stores power generated from the motor generator 11 that operates as a generator and supplies power to the motor generator 11 that operates as a motor. Return to.

  The battery 28 is charged by the generated power from the motor generator 11 when the amount of power stored in the battery 28 is reduced by supplying power to the motor generator 11 by the battery 28 as described above. After the charging of 21 is completed, the generated power from the motor generator 11 is stored in the battery 28. That is, as described above, after the capacitor power storage device 21 is recharged and the capacitor power storage device 21 is fully charged by the generated power from the motor generator 11, the first changeover switch 30a is turned off, and the second By setting the changeover switch 30b to the on state, the generated power from the motor generator 11 is stored in the battery 28. The battery 28 can be charged by external charging using a separate charger or the like.

  In the first operation mode of the power storage system unit 20, normally, the capacitor power storage device 21 having a higher output density than the battery is used to store the generated power from the motor generator 11 that operates as a generator and to operate as a motor. By supplying electric power to the motor generator 11, torque assist performance and power regeneration performance by the motor generator 11 can be improved, and sudden load fluctuations of the engine 2 can be dealt with. When the amount of power stored in the capacitor power storage device 21 decreases, the power supply to the motor generator 11 that operates as a motor is a battery 28 having a battery capacity capable of instantaneously supplying a large current to the motor generator 11. Therefore, the shortage of electric power of the capacitor power storage device 21 having a lower energy density than that of the battery can be compensated, for example, when the torque assist by the motor generator 11 takes a long time.

  Further, as described above, by controlling the first changeover switch 30a and the second changeover switch 30b, when power is supplied from the battery 28 to the motor generator 11, it is instantaneously excessive from the battery 28 to the capacitor power storage device 21. Therefore, it is possible to prevent and protect the capacitor power storage device 21 having a low internal resistance from being destroyed or failed. When the capacitor power storage device 21 is recharged, the generated power from the motor generator 11 is not supplied to the battery 28, so that the capacitor power storage device 21 can be charged efficiently.

  Next, a second operation mode in the power storage system unit 20 will be described. In this operation mode, power is supplied to the motor generator 11 that performs torque assist mainly by the battery 28. Then, when the battery voltage of the battery 28 falls below a predetermined value set in advance at a certain rate of change, the capacitor power storage device 21 supplies power to the motor generator 11 that operates as a motor.

  That is, in this operation mode, when the battery voltage VBAT of the battery 28 exceeds the preset specified value VN, the first changeover switch 30a is turned off and the second changeover switch 30b is turned on. The battery 28 stores the generated power from the motor generator 11 that operates as a generator and supplies power to the motor generator 11 that operates as a motor. When the battery voltage VBAT of the battery 28 is lower than the preset specified value VN and the voltage drop rate per unit time is larger than the preset specified value, in other words, the voltage is When the gradient (rate of change) S (= dVBAT / dt) at the time of decrease falls below a preset specified value SN (when the gradient becomes steep or the rate of decrease increases), the first switching is performed. The switch 30a is turned on to supply electric power from the capacitor power storage device 21 to the motor generator 11.

  The battery voltage VBAT of the battery 28 is detected by the current / voltage sensor 25 as described above, and the slope S when the battery voltage VBAT decreases is sampled and calculated every certain time (for example, 1 second) in the system controller 1. Is done. The battery voltage VBAT and the gradient S thereof are respectively determined by the system controller 1 whether they are above or below a predetermined value VN (for example, 45 V) and SN (for example, 10 V) set in advance. That is, specified values VN and SN are set in advance in the system controller 1, and the system controller 1 compares the battery voltage VBAT of the battery 28 detected by the current / voltage sensor 25 with the specified value VN. It is always determined whether the battery voltage VBAT 28 is above or below the specified value VN. Further, the gradient S of the battery voltage VBAT calculated at regular intervals as described above is compared with the specified value SN, and it is determined at regular intervals whether the gradient S is above or below the defined value SN. ing.

  Under such a determination, in a state where the battery voltage VBAT of the battery 28 exceeds the specified value VN, the battery 28 supplies power to the motor generator 11 at the time of torque assist. That is, in this case, the first changeover switch 30a for turning on / off the energization of the capacitor power storage device 21 is turned off, and the second changeover switch 30b for turning on / off the energization of the battery 28 is turned on. The battery 28 supplies power to the motor generator 11 that performs torque assist when the engine 2 is in a high load state. In this case, the battery 28 also stores the generated power from the motor generator 11 that operates as a generator when the engine 2 is in a low load state.

  Then, when a high load is suddenly applied to the engine 2 and the battery voltage VBAT of the battery 28 is suddenly reduced, power is supplied to the motor generator 11 from the capacitor power storage device 21. That is, when a high load is suddenly applied to the engine 2, the motor generator 11 performs torque assist in accordance with this load. Therefore, it is necessary to instantaneously supply a large current from the battery 28 to the motor generator 11. In 28, instantaneous discharge needs to be performed. However, when the battery 28 supplies such an instantaneous large current and reaches the limit of its output, as shown in FIG. 5, it causes a sudden drop (voltage drop) of the battery voltage VBAT. The voltage drop of the battery 28 causes malfunction or stop of the system. Therefore, in order to prevent a voltage drop of the battery 28, when the engine 2 is suddenly subjected to a high load, the capacitor power storage device 21 supplies power to the motor generator 11.

  Specifically, in a state where the battery voltage VBAT of the battery 28 is lower than the specified value VN and the gradient S thereof is lower than the specified value SN, that is, in a state where the battery voltage VBAT is lower than the specified value VN, When the engine 2 is suddenly subjected to a high load and the battery voltage VBAT is suddenly lowered, the first changeover switch 30a is turned on, and the power supply to the motor generator 11 operating as a motor is performed by the capacitor power storage device 21. It becomes. That is, the specified value SN is a reference for the load when the engine 2 is suddenly subjected to a high load. Here, the second changeover switch 30b may be in the on state or in the off state. That is, when the engine 2 is suddenly subjected to a high load and the voltage of the battery 28 decreases, the power is supplied to the motor generator 11 by the capacitor power storage device 21, so the voltage on the battery 28 side is the capacitor power storage device 21. This is because the voltage is lower than that of the battery and current does not flow from the battery 28 to the capacitor power storage device 21. However, in order to further ensure the safety of the capacitor power storage device 21, it is desirable to turn off the second changeover switch 30b.

  In this way, when the engine 2 is suddenly subjected to a high load, the battery voltage VBAT of the battery 28 is suddenly lowered, and the electric power is supplied to the motor generator 11 by the capacitor power storage device 21. The capacitor power storage device 21 that consumes power is charged when the load of the engine 2 is in a steady state. That is, when the load on the engine 2 decreases and torque assist by the motor generator 11 is no longer necessary, the electric power generated by the motor generator 11 that operates as a generator by the surplus output of the engine 2 is stored in the capacitor power storage device 21. When the capacitor power storage device 21 is fully charged and charging of the capacitor power storage device 21 is completed, the first changeover switch 30a is turned off, the second changeover switch 30b is turned on, and the battery 28 is connected to the motor. It will be in the state connected with the generator 11. FIG. That is, in this operation mode, the battery 28 as the main power storage device returns to the state in which the generated power is stored from the motor generator 11 operating as a generator and the power is supplied to the motor generator 11 operating as a motor.

  In the second operation mode of the power storage system unit 20, it is usually necessary when power is supplied to the motor generator 11 that operates as a motor by the battery 28 and the engine 2 is suddenly subjected to a high load. Only in this case, the power storage device that supplies power to the motor generator 11 is switched to the capacitor power storage device 21, so that the voltage drop of the battery 28 as described above can be prevented and the malfunction of the system can be prevented. It is possible to supply power to the motor generator 11 for a long time. That is, as the power storage device that supplies power to the motor generator 11 that performs torque assist, the battery 28 is used for a continuous load, and the capacitor power storage device 21 is used for an instantaneous and sudden high load. Therefore, the high energy density of the battery 28 and the high output density of the capacitor power storage device 21 can be appropriately used. As a result, the motor generator 11 can assist torque for a long time even in an operation where a sudden load fluctuation occurs.

  Next, another configuration of the power storage system unit 20 will be described. Note that the power storage system unit 20 of this configuration is substantially the same as that shown in FIG. 1, and therefore, devices having the same uses and functions as those shown in FIG. Is omitted, and the different parts will be described along the description of the operation mode.

  In the operation mode of the power storage system unit 20 of this configuration, the capacitor power storage device 21 performs storage of generated power from the motor generator 11 that operates as a generator and supply of power to the motor generator 11 that operates as a motor. When the amount of electricity stored in the capacitor power storage device 21 decreases, the battery 28 charges the capacitor power storage device 21. That is, in this operation mode, the battery 28 does not supply power to the motor generator 11 but only charges the capacitor power storage device 21, and all power is supplied to the motor generator 11 that operates as a motor. This is performed by the capacitor power storage device 21.

  That is, in the operation mode in this configuration, when the amount of power stored in capacitor power storage device 21 decreases and capacitor voltage VC decreases below battery voltage VBAT of battery 28, capacitor power storage device 21 is charged by battery 28. It is characterized by being. Therefore, in this configuration, as shown in FIG. 6, a second constant current control circuit 100 a that performs constant current control of the charging current from the battery 28 to the capacitor power storage device 21 is provided. That is, in the present configuration, the first constant current control circuit includes the constant current control circuit 100 that performs constant current control of the charging current from the motor generator 11 that operates as a generator to the capacitor power storage device 21. In addition, a second constant current control circuit 100a that performs constant current control of charging current from the battery 28 to the capacitor power storage device 21 is provided. In this way, power is not supplied from the battery 28 to the motor generator 11, and the second constant current control circuit 100a can be connected in parallel to the capacitor power storage device 21 and the battery 28. Therefore, the capacitor power storage device 21 and the battery There is no need to provide the first change-over switch 30a and the second change-over switch 30b for turning on / off the power to the power supply 28. Since the structure of the second constant current control circuit 100a is substantially the same as that of the constant current control circuit 100, the description thereof is omitted.

  By the way, in this hybrid system, the load of the engine 2 is leveled by performing the torque assist by the motor generator 11 and the power storage of the capacitor power storage device 21 in accordance with the load on the engine 2. When work or the like is performed and the capacitor power storage device 21 repeats charging and discharging, the capacitor voltage VC gradually decreases due to the characteristics of the capacitor power storage device 21 as shown in FIG. FIG. 7 is a graph showing the capacitor voltage VC and the battery voltage VBAT when charging and discharging with the same amount of electricity are repeated in the capacitor power storage device 21 and the battery 28, respectively. As can be seen from this figure, the capacitor voltage VC decreases every time charging / discharging of the capacitor power storage device 21 is repeated, whereas the battery voltage VBAT of the battery 28 decreases or decreases when discharged or charged. Although it rises, it returns to a constant voltage each time, and always maintains a constant voltage as the battery voltage VBAT. The capacitor power storage device 21 is charged by the battery 28 using such charge / discharge characteristics of the capacitor power storage device 21 and the battery 28. In other words, due to the charge / discharge characteristics of the capacitor power storage device 21 and the battery 28, the voltage of the capacitor power storage device 21 is always lower between the capacitor power storage device 21 and the battery 28. Therefore, this voltage difference is used. Thus, the battery 28 is charged with the capacitor 28 as needed. In order to control the charging current from the battery 28 to the capacitor power storage device 21, the second constant current control circuit 100a is provided.

  Specifically, in normal times, that is, when the capacitor power storage device 21 has a sufficient power storage amount to supply power to the motor generator 11, the capacitor power storage device 21 causes the motor generator 11 that operates as a generator to The generated electric power is stored and the electric power is supplied to the motor generator 11 that operates as a motor according to the load applied to the engine 2. In this case, the current from the battery 28 is controlled by the second constant current control circuit 100a so as not to flow to the capacitor power storage device 21. That is, the second constant current control circuit 100a that controls the charging current from the battery 28 to the capacitor power storage device 21 sets the current flowing from the battery 28 to the capacitor power storage device 21 to zero.

  As described above, when the capacitor voltage VC of the capacitor power storage device 21 decreases due to repeated charge / discharge of the capacitor power storage device 21 due to load leveling by the motor generator 11, the battery 28 charges the capacitor power storage device 21. Power is supplied. At this time, the charging current to the capacitor power storage device 21 is constant current controlled by the second constant current control circuit 100a. Such charging of the capacitor power storage device 21 by the battery 28 can be performed while the capacitor power storage device 21 is supplying power to the motor generator 11 that is performing torque assist. In this case, for example, when the high load state of the engine 2 continues for a long time and the power supply to the motor generator 11 by the capacitor power storage device 21 takes a long time, the capacitor power storage device 21 is charged by the battery 28, It becomes possible to continue supplying power to the motor generator 11 by the capacitor power storage device 21.

  The charging of the capacitor power storage device 21 by the battery 28 can also be performed as follows. That is, as shown in FIG. 6, the third changeover switch 30c is provided at a position where the energization between the capacitor power storage device 21 and the motor generator 11 side can be turned on and off while the power supply between the capacitor power storage device 21 and the battery 28 is maintained. . When charging the capacitor power storage device 21 with the battery 28, the third changeover switch 30c is turned off. The third changeover switch 30c is composed of a mechanical switch or a semiconductor element such as a power transistor, and its on / off is controlled by the system controller. By doing so, while the capacitor 28 is charged by the battery 28, the energization of the capacitor power storage device 21 to the motor generator 11 is cut off. That is, since the capacitor power storage device 21 has a characteristic of high charging efficiency, the battery 28 can be charged in a short time. Therefore, when the capacitor power storage device 21 is charged by the battery 28, the third The changeover switch 30c is once turned off, and when charging of the capacitor power storage device 21 is completed, the third changeover switch 30c is returned to the on state again so that the motor generator 11 side of the capacitor power storage device 21 is energized.

  For example, if the capacitor voltage VC of the capacitor power storage device 21 decreases while the power is being supplied to the motor generator 11 by the capacitor power storage device 21, the third changeover switch 30c is momentarily turned off, and the capacitor by the battery 28 is turned off. The power storage device 21 is charged instantaneously, and when the capacitor power storage device 21 is in a fully charged state or when the amount of stored power reaches a certain amount or more, the third changeover switch 30c is turned on again. By doing so, it is possible to prevent the charging power supplied from the battery 28 from flowing to the motor generator 11 side. Thus, by providing the third changeover switch 30c and controlling the turning on / off of the third changeover switch 30c as described above, the charging of the capacitor power storage device 21 by the battery 28 becomes efficient.

  It should be noted that charging of capacitor power storage device 21 with battery 28 in this way causes charging of battery 28 when the amount of power storage is reduced by the generated power from motor generator 11 or the charged power from battery 28. This is performed by storing the generated power from the motor generator 11 in the battery 28 when the power storage device 21 is in a fully charged state. In this case, constant current control circuit 100 controls the charging current to capacitor power storage device 21 and also controls the charging current to battery 28. The battery 28 can be charged by external charging using a separate charger or the like.

  In the operation mode in the power storage system unit 20 configured as shown in FIG. 6, the capacitor power storage device 21 charged as needed by the battery 28 operates to store the generated power from the motor generator 11 that operates as a generator and to operate as a motor. Therefore, it is possible to improve the torque assist performance and power regeneration performance of the motor generator 11, and to cope with a sudden load fluctuation of the engine 2 over a long period of time. It becomes.

  1 and 6 described above can also be configured to serve as the same power storage system unit. That is, by providing the power storage system unit 20 shown in FIG. 1 with the third changeover switch 30c and the second constant current control circuit 100a shown in FIG. 6, the above-described operation modes can be implemented in the same power storage system unit. It can also be set as the structure which can be performed.

The figure which shows an example of a structure of the hybrid system which concerns on this invention. The figure which shows the structure of a constant current control circuit. The figure which shows the control flow of the constant current control by a constant current control circuit. The figure which shows the structure of a uniform control circuit. The figure which shows the change of a battery voltage. The figure which shows the other structure of an electrical storage system part. The figure which shows the charging / discharging characteristic of a battery and a capacitor electrical storage apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 System controller 2 Engine 11 Motor generator 21 Capacitor electrical storage apparatus 28 Battery 30a 1st changeover switch 30b 2nd changeover switch 30c 3rd changeover switch 100 Constant current control circuit (1st constant current control circuit)
100a Second constant current control circuit

Claims (2)

In a hybrid system comprising an engine (2), a motor that assists the engine (2), a control means that controls these, and a generator that uses the engine as a drive source, storage of generated power from the generator And a capacitor power storage device (21) that supplies power to the motor, and a first constant current control circuit (100) that performs constant current control of charging current from the generator to the capacitor power storage device (21); A battery (28) for supplying electric power to the motor, a first changeover switch (30a) controlled by the control means to turn on and off the capacitor power storage device (21), and the control means And a second changeover switch (30b) that is controlled to turn on / off the power supply to the battery, and the amount of electricity stored in the capacitor power storage device (21) is preset. When the value exceeds a certain value, the first changeover switch (30a) is turned on and the second changeover switch (30b) is turned off, and the generated power from the generator by the capacitor power storage device (21). When the amount of power stored in the capacitor power storage device (21) falls below a preset specified value, the first changeover switch (30a) is turned off. At the same time, the second changeover switch (30b) is turned on, and power is supplied from the battery (28) to the motor. In this state, the battery voltage of the battery (28) is set to a preset value. If it exceeds the upper limit, the first changeover switch (30a) is turned off, and the second changeover switch (30b) is turned on. (28) to store the generated power from the generator and supply the power to the motor, the battery voltage of the battery (28) is lower than a preset specified value, and per unit time When the voltage drop rate becomes larger than a predetermined value set in advance, the first changeover switch (30a) is turned on, and power is supplied from the capacitor power storage device (21) to the motor. A hybrid system characterized by The hybrid system according to claim 1, wherein a capacitor power storage device (21) that stores power generated by the generator and supplies power to the motor, and a power storage device from the generator to the capacitor power storage device (21). A first constant current control circuit (100) for performing constant current control of charging current is provided, and when the capacitor voltage of the capacitor power storage device (21) is lower than the battery voltage of the battery (28), the battery ( And 28) a second constant current control circuit (100a) that enables charging of the capacitor power storage device (21) and performs constant current control of charging current from the battery (28) to the capacitor power storage device (21). A hybrid system characterized by being provided .

Images