JP2011135686A - Device and method for controlling hybrid system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller for cargo handling machines or construction machines comprised of a hybrid system wherein it is possible to effectively utilize the power of a secondary battery without overcharging or overdischarging the secondary battery even in the process of cargo handling work or construction work. <P>SOLUTION: The controller for hybrid systems includes a working motor (4), a battery (5), a generator (12) that generates power by power from an engine (11), and an inverter (3) that converts a power supplied from the generator and/or the battery connected to a direct-current bus (14) to drive the motor. The sharing of load between the generator and the secondary battery is changed by adjusting the generator voltage during driving of the working motor. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a control device and a control method for controlling an engine hybrid system of a cargo handling machine or a construction machine.

  A cargo handling machine that performs cargo handling operations such as loading and unloading of containers includes an engine, a generator driven by the engine, and a motor for cargo handling work. The motor is driven by the power output from the generator to load and load the cargo. The unloading operation (loading operation) is performed. In the cargo handling machine, the electric power from the generator is further supplied to auxiliary equipment such as lighting devices and cab air conditioning equipment. Therefore, in the cargo handling machine, the engine is operated even during the cargo handling operation, and the power from the generator is supplied to the auxiliary machine.

  Also, in construction machines such as wheel loaders, construction work is hydraulic (hydraulic working device) that is performed by a hydraulic pump that is directly driven by the engine, and traveling work supplies power from the generator driven by the engine to the motor. Thus, a hybrid system that is an electric type (electric traveling device) is employed.

  In recent years, a generator / battery hybrid system including a generator and a secondary battery as a power source has been developed (see, for example, Patent Document 1 and Patent Document 2).

  In the cargo handling machine disclosed in Patent Document 1, when the hoisting machine requires a large amount of electric power, the engine is rated for operation to supply power from the generator, and when the no-load state continues, the engine is idled from the rated operation for idling. Switch the power supply to the auxiliary machine from the secondary battery, and when the voltage of the secondary battery drops below the specified value, the engine is switched from idle to rated operation and the power is supplied from the generator to the auxiliary machine. Supply.

  The construction machine disclosed in Patent Document 2 uses a power supply using a power generated from a generator as a base power and a secondary battery as an auxiliary power when driving a working motor. Long life, high efficiency, and downsizing are possible.

  In a hybrid system using a secondary battery as a power storage device, the secondary battery is connected to the DC bus of the inverter and supplies power required by a load (such as a work motor) in cooperation with a generator.

  In a hybrid system, there is an example in which a secondary battery is connected to a DC bus via a charge / discharge control device. This is because the output voltage of the secondary battery is converted to a voltage suitable for the operation of the load and supplied, or the secondary battery is over-discharged by storing it by converting it to a voltage / current suitable for the secondary battery. It is possible to adjust the excess or deficiency of power while preventing excessive charging and preventing excessive wear of the secondary battery.

JP 2004-360610 A JP 2005-012902 A

  Conventionally, in a hybrid system using a secondary battery as a power storage device, when the secondary battery is directly connected to the DC bus of the inverter, the secondary battery is excessively charged because the secondary battery is charged and discharged by the voltage of the DC bus. Charging or overdischarge may occur. If the secondary battery is overcharged or overdischarged, the secondary battery is damaged and the battery life is remarkably shortened.

  In addition, if the secondary battery is connected to the DC bus of the inverter via the charge / discharge control device, the above problems of overcharge / overdischarge are eliminated, but the configuration is complicated, and the charge / discharge control device is expensive and installed. There is a problem that costs increase.

  In the case of operating only an auxiliary machine or the like that does not require a large amount of electric power, a technique for supplying electric power from a secondary battery with an engine in an idle state has been proposed. On the other hand, during cargo handling work or construction work that requires a large amount of power, the generator is operated at rated power and operated with power from the generator. At this time, the secondary battery is not used. One of the reasons why both the generator and the secondary battery are not used during cargo handling work or construction work is to prevent overdischarge of the secondary battery.

  When the regenerative electric power generated in the work motor at the time of unloading the baggage or decelerating from the traveling state is stored in the secondary battery and used as the electric power during the cargo handling work or the construction work, the energy can be effectively used. Furthermore, if the secondary battery is charged during rated operation with high engine efficiency and this electric power is used for cargo handling work, fuel consumption can be reduced. However, in the conventional hybrid system, since the secondary battery is not used during the cargo handling work or the construction work, there is a problem that it is difficult to say that the secondary battery is effectively used as the power storage device.

  The present invention solves the above-described problems in the prior art, and the object of the present invention is to provide a secondary battery without overcharging / discharging the secondary battery even during cargo handling work or construction work. It is an object of the present invention to provide a control device and a control method for a cargo handling machine or a construction machine including a hybrid system that enables effective use of battery power. In addition, the present invention provides a control device and a control method for a hybrid system of a cargo handling machine and a construction machine with low fuel consumption.

  The present invention is a control device for a hybrid system including an engine and a secondary battery, wherein the hybrid system includes a work motor, a secondary battery, a generator that generates power by power from the engine, and the power generation An AVR that adjusts the power generation voltage of the machine, and an inverter that performs power conversion for driving the motor from the power supplied from the generator and / or the secondary battery, with the secondary battery connected to a DC bus. The control device is capable of adjusting the load sharing between the generator and the secondary battery by adjusting the voltage setting value of the AVR during driving of the motor. (Claim 1). The control device of the hybrid system of the present invention is a power flow control device 7 shown in FIG.

  According to this configuration, the engine may be an internal combustion engine such as a gasoline engine or a gas engine, and is preferably a diesel engine. The output shaft of the engine and the drive shaft of the generator are connected via a coupling to constitute an engine generator.

Further, according to this configuration, the secondary battery may be directly connected to the DC bus without using a device such as a charge / discharge control device that adjusts the voltage of the secondary battery.
The AVR is a control device that makes it possible to control the generated voltage (generator voltage) of the generator by adjusting the intensity of excitation of the generator. Therefore, the “AVR voltage setting value” may be referred to as a “generator voltage command”.

  If the generator voltage changes, since the generator and the secondary battery are connected via the DC bus, the load sharing ratio between the generator and the secondary battery changes.

  The hybrid system according to the present invention may further include a battery monitor that calculates a state of charge (SOC) of the secondary battery. At this time, the voltage setting value of AVR may be set according to the SOC value of the secondary battery calculated by the battery monitor.

  The hybrid system may further include a voltmeter for measuring a terminal voltage of the secondary battery, and the AVR voltage set value may be set according to a measured value of the voltmeter.

  When the voltage setting value of the AVR is equal to or less than a predetermined setting value, the engine speed may be switched from the rated speed to the idle speed.

  According to this configuration, when the voltage setting value of AVR is equal to or less than a predetermined setting value, the setting of the engine governor is lowered to put the engine in an idle state, and unnecessary fuel consumption can be suppressed. Further, when the generator voltage becomes lower than a predetermined value, the generator output becomes unstable. Therefore, it is meaningful to set the idle state to prevent this.

  Regardless of the value of the voltage setting value of AVR, when the output of the engine generator decreases, the engine speed may be switched from the rated speed to the idle speed. As a load of such an engine generator, for example, 30% L can be considered, but it may be 20% L.

  Furthermore, the engine speed may be switched from the rated speed to the idle speed when the voltage of the secondary battery becomes equal to or higher than a predetermined value. In this case, fuel consumption can be suppressed by positively using the power stored in the secondary battery.

  The hybrid system according to the present invention may be a control device for a hybrid system of a cargo handling machine (claim 5).

  In this case, the working motor may be a hoisting motor for raising the load in the cargo handling machine (Claim 6), or may be a traveling motor for running the cargo handling machine. (Claim 7) A traversing motor for traversing a load may be used (claim 8).

  According to this configuration, the cargo handling machine may be a crane used in a port facility, preferably a self-propelled transfer crane.

  The hybrid system according to the present invention may be a hybrid system of a construction machine (claim 9). In this case, the working motor may be a pump drive motor for driving the hydraulic pump in the construction machine (claim 10), or may be a traveling motor for running the construction machine (claim). Item 11).

  According to this configuration, the construction machine may be a wheel loader.

  The secondary battery may be charged by regenerative electric power of a work motor for a cargo handling machine or a construction machine (claim 12).

  According to this configuration, the inverter preferably has regenerative capability, and regenerative power from the hoisting motor of the cargo handling machine or the traveling motor of the construction machine is effectively stored in the secondary battery via the DC bus. It becomes possible to prevent waste of energy. In particular, since the hoisting motor of the cargo handling machine and the traveling motor of the construction machine have a large capacity, a large regenerative electric power can be recovered at the time of lowering or decelerating.

  The secondary battery may be a power storage facility having a so-called power storage function. Preferably, the secondary battery is a stacked nickel-metal hydride battery.

  The present invention relates to a control method for a hybrid system, which includes a work motor, a secondary battery, a generator that generates electric power by power from an engine, an AVR that adjusts the generated voltage of the generator, and a direct current. A secondary battery is connected to the bus, and an inverter that performs power conversion for driving the motor from the power supplied from the generator and / or the secondary battery is provided. Changing the voltage setting value of the AVR in order to adjust the load sharing between the battery and the secondary battery (claim 14).

  Furthermore, the control method according to the present invention includes a step of calculating a SOC (State of Charge) of the secondary battery, and a voltage setting value of the AVR according to the SOC value of the secondary battery calculated in the SOC calculation step. May be provided (claim 15).

  Further, a step of switching the engine speed from the rated speed to the idle speed when the voltage setting value of the AVR becomes equal to or lower than a predetermined setting value may be provided.

  According to the present invention, the electric power required to drive the working motor is supplied from both the engine and the secondary battery, and appropriate load sharing can be performed between the two. As a result, the secondary battery is not overdischarged, and the secondary battery as the power storage device can be prevented from being damaged, which can contribute to the extension of the battery life.

  Furthermore, when the power required to operate the hybrid system is reduced, the engine is idled by switching the engine to idle rotation, thereby preventing excessive fuel consumption and engine fuel consumption. The amount can be reduced.

  The power stored in the secondary battery is the regenerative power collected when the cargo handling machine is lowered or the construction machine is decelerated, and the power stored during engine rated operation, both of which are stored in an economical manner In addition, since it is possible to supply power from both the engine and the secondary battery during cargo handling work and construction work, it is possible to effectively use the inexpensive power of the secondary battery, resulting in the fuel consumption of the hybrid system. Can be saved.

1 is an external view of a cargo handling machine including a control device of the present invention. It is a block diagram which shows the structure of the cargo handling machine hybrid system of FIG. It is a flowchart which shows the control action of a control apparatus. It is FIG. (1) which shows the load sharing characteristic of a secondary battery and a generator. It is a figure (the 2) which shows the load sharing characteristic of a secondary battery and a generator. It is FIG. (The 3) which shows the load sharing characteristic of a secondary battery and a generator. It is a flowchart which shows the stop operation | movement of an engine generator. It is a flowchart which shows starting operation of an engine generator. It is a block diagram which shows the relationship between generator control and power flow control. It is an example of the adjustment characteristic figure which defines the correction amount of a generator voltage command. It is an example of the adjustment characteristic figure which defines the correction amount of a generator voltage command. It is a timing chart (when a generator voltage command increases) which shows a generator voltage control method. It is a timing chart (when a generator voltage command decreases) which shows a generator voltage control method. It is a flowchart for the control operation of the control device of the hybrid system. It is a graph which shows the conventional experiment result. It is a graph which shows the experimental result of this invention. It is a block diagram which shows the structure of a construction machine hybrid system. It is a SOC characteristic figure which shows the voltage change with respect to SOC of various batteries.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. However, the present invention is not limited to the embodiments.

  The embodiment of the present invention described below appropriately controls the load sharing between the engine generator and the secondary battery in the control of a hybrid system including the engine generator and the secondary battery connected to the DC bus of the inverter. By doing so, the battery life is prolonged by preventing overcharge and overdischarge of the secondary battery, and the regenerative power is used effectively, and when the charge of the secondary battery is large, the engine is put in an idle state. Then, power is supplied only to the battery from the battery to the auxiliary equipment and motor. Thereby, the effect that the fuel consumption of the engine is improved is obtained.

1. FIG. 1 schematically shows an appearance of a cargo handling machine when a hybrid system including a control device according to an embodiment of the present invention is applied to the cargo handling machine. The cargo handling machine 100 of the present embodiment is a rubber tired transfer crane (RTG) that is one of crane apparatuses used for cargo handling operations such as harbors.

  The cargo handling machine 100 includes a spreader 103 that lifts a container 101, a wire rope 109 that raises and lowers the spreader 103 by winding and lowering, a traverser 105 that causes the spreader 103 to traverse, and a tire that can travel in the front-rear direction. 107.

  The cargo handling machine 100 lifts the container 101 with the spreader 103, winds up the wire rope 109 attached to the spreader 103, raises the spreader 103, traverses the traverser 105 to a desired position, and then lowers the wire rope 109. The container 101 is unloaded by lowering the spreader 103. In addition, the cargo handling machine 100 can move to an arbitrary position by traveling with the tire 107.

  FIG. 2 is a block diagram showing the system configuration of the cargo handling machine 100 according to the present invention. The cargo handling machine 100 includes an engine generator 13 that outputs AC power, a power flow control device 7 that controls the engine generator 13, an inverter 3 connected to the engine generator 13, and electric power output from the inverter 3. The motor 4 to drive and the operation command part 8 which outputs an operation command to the inverter 3 are provided.

  The engine generator 13 includes an engine 11 and a generator 12 connected to the engine 11. In the present embodiment, the engine 11 is a diesel engine using light oil as fuel. When the engine 11 is rotating at a rated speed, the generator 12 operates to generate power, and when the engine 11 is idle, the generator 12 stops generating power.

  The power flow control device 7 adjusts the load of the engine 11 through the engine control device 1 to control the rotational speed of the engine 11 and further adjusts the excitation of the generator 12 through the AVR 2 to generate power. Control machine voltage.

  The inverter 3 includes a converter unit 31 that converts AC power into DC power, and an inverter unit 32 that converts DC power into AC power. The inverter 3 controls the converter unit 31 and the inverter unit 32 according to the operation command output from the operation command unit 8 and supplies electric power to the motor 4.

  The motor 4 is a winding motor for winding the wire rope 109 shown in FIG. The operation command unit 8 is provided in a cab of the cargo handling machine 100 or the like. The operation command unit 8 outputs an operation command instructed by the operator to the inverter 3. The operation command includes a hoisting and lowering command.

  The cargo handling machine 100 further calculates the secondary battery 5 directly connected to the DC bus 14 between the converter unit 31 and the inverter unit 32 of the inverter 3 and the state of charge (SOC) of the secondary battery 5. And a power flow control device 7 that controls the engine generator 13 based on the operation command and the SOC of the secondary battery 5.

  In the present embodiment, the secondary battery 5 is a stacked nickel metal hydride battery in which nickel metal hydride cells are stacked in series. Specifically, in a nickel metal hydride battery, a plurality of unit batteries each having a positive electrode cell and a negative electrode cell separated by a separator are adjacent to each other between a pair of plate-like current collectors provided to face each other. In the battery module, the positive electrode cell of one unit battery and the negative electrode cell of the other unit battery are stacked so as to face each other.

  Although the characteristics of the nickel metal hydride battery will be described later, the nickel metal hydride battery has a characteristic that the voltage fluctuation due to the fluctuation of the SOC (state of charge) is small, and can be directly connected to the DC bus 14. The output voltage of the secondary battery can be adjusted by the number of unit batteries stacked. In the case of a nickel metal hydride battery, the output voltage of the secondary battery can be adjusted by a small unit of 1.2V.

  The power flow control device 7 outputs an engine speed command to the engine 11 and generates power based on the operation command output from the operation command unit 8 to the inverter 3 and the SOC of the secondary battery 5 calculated by the battery monitor 6. A generator voltage command is output to the machine 12. The engine rotation command includes a rated rotation command for instructing a rated rotation speed and an idle command for instructing an idle having a rotation speed lower than the rated rotation speed.

  The cargo handling machine 100 includes a DC / AC converter 9 connected to the DC bus 14 between the converter unit 31 and the inverter unit 32 of the inverter 3, and an auxiliary machine 10 connected to the DC / AC converter 9. . The auxiliary machine 10 requires electric power not only during the cargo handling operation but also during the cargo handling operation. For example, the illuminating device provided in the cargo handling machine 100, the air conditioning equipment in the cab, a hydraulic unit (hydraulic unit) Pump, etc.).

2. Operation of the cargo handling machine The operation of the cargo handling machine 100 will be described by taking as an example a case where an operation command instructing winding is input. FIG. 3 is a flowchart showing a control operation in the control device of the hybrid system centering on the power flow control device 7 when starting winding. Before the winding is started, the power flow control device 7 normally outputs an idle command as an engine speed command. The engine 11 is in an idle state in accordance with an idle command. At this time, the power generated by the generator 12 is zero. The generator voltage command is set to a predetermined value (SV ₀ ) (S300).

  When the operator inputs a winding command to the operation command unit 8, the operation command unit 8 outputs the winding command. The power flow control device 7 determines whether or not a winding command from the operation command unit 8 has been input (S301). When the winding command is input, the power flow device 7 switches the engine speed command from the idle command to the rated rotation command, and outputs the rated rotation command to the engine control device 1 (S302). Next, the battery monitor 6 reads the measured values of the voltage, current, and temperature of the secondary battery (S303), calculates the SOC from these measured values (S304), and outputs the calculated result of the SOC to the power flow device 7. To do. The power flow control device 7 receives the SOC of the secondary battery 5 calculated by the battery monitor 6 and determines whether the SOC value of the secondary battery 5 is equal to or greater than a predetermined value (S305).

  If the SOC of the secondary battery 5 is less than the predetermined value (<α in S305), the power flow control device 7 increases the set value of the generator voltage (S306). That is,

(Equation 1)
SVn = SV ₀ + ΔSV
Here, SV ₀ is a reference value for the generator voltage setting, SVn is a new generator voltage setting, and ΔSV is a correction amount for the generator voltage setting.

  If the SOC of the secondary battery 5 is larger than the predetermined value (> α in S305), the power flow control device 7 decreases the set value of the generator voltage (S308). That is,

(Equation 2)
SVn = SV ₀ −ΔSV
As another method of determining the generator voltage setting (SVn), the following (Formula 3) is used instead of (Formula 1), and the following (Formula 4) is used instead of (Formula 2). You may repeat (S303)-(S309) for every effect waiting time. That is,

(Equation 3)
SVn = SVn−1 + ΔSV ₁

(Equation 4)
SVn = SVn−1−ΔSV ₁
Here, SVn−1 is a generator voltage setting at the previous control, SVn is a generator voltage setting at the current control, and ΔSV ₁ is a correction amount of the generator voltage setting.

  The AVR 2 increases and decreases the generator voltage based on the generator voltage command from the power flow control device 7.

When the winding command is turned off (S309), the power flow control device 7 returns the generator voltage command to the original predetermined value (S310). As a result, the AVR 2 controls the generator 12 so as to return the voltage generated by the generator to a predetermined value.
When the winding command is not ON, a predetermined value is set for the generator voltage setting (S300) (S310).

When the secondary battery 5 is used as the power storage device as the SOC predetermined value (α), it is preferable to set the SOC predetermined value in the range of 60% to 90% in order to ensure the storage state. More preferably, it can be defined in the range of 70% to 80%.
The generator voltage command correction amount (ΔSV) is a fixed value, but may be changed according to the SOC value.

  In the present embodiment, the predetermined value of SOC is 75%, but it may preferably have a dead band characteristic of ± 5% with 75% as the median as shown in FIG. If a dead band is provided, relatively smooth control can be realized. The dead band width may be smaller.

  In FIG. 10, if the SOC exceeds 80%, the fixed correction amount ΔSV is subtracted from the reference value of the generator voltage command, and if the SOC is less than 70%, the fixed correction amount ΔSV is set to the reference value of the generator voltage command. In addition, a generator voltage command is obtained. However, the correction amount ΔSV may not be a fixed value. For example, as shown in FIG. 11, it is good also as a continuous quantity according to the value of SOC.

  When the processes of steps (S303) to (S310) are repeated, the AVR 2 controls the voltage of the generator 12 according to the generator voltage command, and the engine control device 1 controls the engine 11 according to the rated rotation command. Rotate the motor at the rated speed. At this time, the generator 12 coupled to the engine 11 generates electric power, and electric power is supplied from both the engine generator 1 and the secondary battery 5 to the motor 4 to perform winding. That is, the AC power generated by the generator 12 is converted to DC power by the converter unit 31 of the inverter 3, and the DC power is output to the DC bus 14. Since the secondary battery 5 is also connected to the DC bus 14, power from the generator 12 and power from the secondary battery can be supplied to the DC bus 14.

  On the other hand, the inverter 3 operates in accordance with the winding command output from the operation command unit 8, converts the DC power supplied from the generator 12 through the secondary battery 5 and the converter unit 31 into AC power, and outputs the motor 4 To supply. In this way, the luggage is wound up with the electric power from the secondary battery 5 and the generator 12.

  Here, the state of load sharing between the secondary battery 5 and the generator 12 will be described with reference to FIG.

  FIG. 4 is a diagram showing current-voltage characteristics of the secondary battery 5 and the generator 12, and is a characteristic diagram when the DC bus voltage at the time of no load is equal. The current-voltage characteristics of the secondary battery 5 and the generator 12 both have a drooping characteristic, and the slope of the secondary battery 5 is generally larger.

In FIG. 4, when the DC bus voltage is Vc, the secondary battery 5 shares the current Ab at the intersection of the horizontal line with a constant Vc and the drooping characteristics of the secondary battery, and the generator 12 A current Ag + Ag is supplied to the motor 4 by sharing the current Ag at the intersection with the drooping characteristic. Since the bus voltage Vc is common, the load sharing ratio of the secondary battery 5 and the generator 12 is respectively
Ab / (Ab + Ag) and Ag / (Ab + Ag).

  FIG. 5 is a diagram showing the current-voltage characteristics of the secondary battery 5 and the generator 12 when the generator voltage is increased. The no-load voltage of the generator 12 is Vu, and the no-load of the secondary battery 5 is shown. The voltage is indicated by Ve.

  In FIG. 5, when the DC bus voltage is the same Vc as in FIG. 4, there is no change in the current shared by the secondary battery 5, but the current shared by the generator 12 increases and eventually the load sharing of the generator 12 is reduced. Will increase.

  On the contrary, the current-voltage characteristics of the secondary battery 5 and the generator 12 when the generator voltage is lowered are shown in FIG. In FIG. 6, when the DC bus voltage Vc is the same, there is no change in the current shared by the secondary battery 5, but the current shared by the generator 12 decreases and eventually the load sharing of the secondary battery 5 increases. It becomes.

  The DC bus voltage Vc is determined by the power required by the motor 4, and the load sharing is determined according to the current-voltage characteristics of the secondary battery 5 and the generator 12 under the common DC bus voltage.

  FIG. 9 is a block diagram showing the voltage control system of the generator 11. The power flow control device 7 sends a generator voltage increase / decrease command 20 to the AVR 2. In the AVR 2, the voltage setting value 21 and the increase / decrease command 20 provided inside the AVR 2 are added together in the adder 22 to be a setting value for the PID controller 24. The voltage of the generator 11 is detected by a voltmeter 25 and compared with a set value by a subtractor 23. The control error that is the output of the subtracter 23 is subjected to a control calculation by the PID controller 24 and outputs a control calculation result to the generator 11. The excitation of the generator 11 is adjusted according to the output of the PID controller 24, and the voltage of the generator changes.

  FIG. 7 is a flowchart showing a control flow when the engine 11 becomes idle from the rated rotation. In FIG. 7, the generator voltage command is checked (S701), and if it is below a predetermined value, then the battery voltage is checked (S702), and if it is above the predetermined value, an idle command is output to the engine 11 ( S703), the engine 11 becomes idle.

The power flow control device 7 controls the engine control device 1 so that the engine 11 maintains the rated rotation unless the generator voltage command is less than the predetermined value or the battery voltage is not higher than the predetermined value.
By performing stop control of the engine generator 13 in this way, useless operation of the engine 11 can be omitted.

  FIG. 8 is a flowchart showing the control flow when the engine 11 changes from idle to rated rotation. In FIG. 8, the battery voltage is checked (S801), and if it is below a predetermined value, a rated rotation command is output to the engine 11 (S803). Otherwise, the SOC value is checked next (S802), and if it is equal to or less than the predetermined value, a rated rotation command is output to the engine 11 (S803). If it does so, the engine 11 will become a rated rotation and the engine generator 1 will generate electric power.

By performing the operation control of the engine generator 13 in this way, the SOC of the secondary battery 5 can be maintained in an appropriate range.
The power flow control device 7 controls the engine control device 1 so that the engine 11 is kept idle if the battery voltage is not lower than the predetermined value and the SOC value is not lower than the predetermined value.

  12 and 13 show timing charts in the winding and lowering operations. 12 and 13, (a) shows ON / OFF of the winding command output from the operation command unit 8, (b) shows the generator voltage command output from the power flow control device 7, and (c) shows The output power of the engine generator 13 is shown, (d) shows the output power of the secondary battery 5, and (e) shows the SOC of the secondary battery 5.

  In FIG. 12, the power flow control device 7 outputs an idle command to the engine control device 1 as an engine speed command until a hoisting command is input (time t0 to time t1). Since the engine control device 1 makes the engine 11 idle according to the idle command, the generator 12 stops power generation. During this time, power is supplied to the auxiliary machine 10 only by the secondary battery 5. For this reason, the SOC of the secondary battery 5 decreases.

  A winding command is input at time t1. Since the SOC of the secondary battery 5 at this time is 60% and does not exceed the predetermined threshold value (75%) shown in FIG. 10, the power flow control device 7 increases the generator voltage setting by ΔSV (10%). Let As a result, the output voltage of the engine generator 13 increases, so the load sharing of the generator 11 increases (the load sharing changes from FIG. 4 to FIG. 5), and the generator power increases as shown in FIG. To increase. Since a large amount of electric power is required for winding up the load, the output of the secondary battery increases with a part of the increase in the required power. Thereby, winding is performed by both electric power from the engine generator 1 and the secondary battery 5 (time t1-time t2). The SOC decreases as the secondary battery output increases.

  When the winding is completed at time t2, the winding command is turned off. The generator voltage command returns to the original value, and as a result, the power of the engine generator 13 and the power of the secondary battery also return to the original values.

  On the other hand, when a command for lowering is input (time t2), the cargo handling machine 100 starts lowering. The lowering is performed by the weight of the container 101 without driving the motor 4. As the container 101 descends, the motor 4 rotates and regenerative power is generated. Since the secondary battery 5 is charged by the regenerative power, the SOC value starts to increase (time t2 to time t3). The electric power stored in the secondary battery 5 by the regenerative electric power is used for power feeding to the auxiliary machine 10 and the next winding work.

  In FIG. 13, the state is the same until the winding command is input (time t0 to time t1).

  When the winding command is input at time t1, the SOC of the secondary battery 5 at this time is 80% and exceeds a predetermined threshold (75%), so the power flow control device 7 sets the generator voltage. Decrease by ΔSV (10%). As a result, the output voltage of the engine generator 13 decreases, so the load sharing of the generator 11 decreases (the load sharing changes from FIG. 4 to FIG. 6). As a result, the output of the engine generator 13 increases. On the other hand, the load shared by the secondary battery output is determined according to the new load sharing (FIG. 6). Thereby, winding is performed by both electric power from the engine generator 1 and the secondary battery 5 (time t1-time t2). Compared with FIG. 12, the degree of decrease in SOC is greater than that in FIG. 12 because the load sharing of the secondary battery 5 increases.

  When the winding is completed at time t2, the winding command is turned off. The generator voltage command returns to the original value, and as a result, the power of the engine generator 13 and the power of the secondary battery also return to the original values.

  On the other hand, when a command for lowering is input (time t2), the cargo handling machine 100 starts lowering. The motor 4 generates regenerative electric power with the lowering. Since the secondary battery 5 is charged by the regenerative power, the SOC value starts to increase (time t2 to time t3).

  As another embodiment of the present invention, the generator voltage command may be adjusted according to the value of the battery voltage. FIG. 14 is a flowchart showing a control operation in a control device of a hybrid system according to another embodiment. If the battery voltage is smaller than a predetermined value (<β), the generator voltage command is increased (S1405). If the battery voltage is larger than a predetermined value (> β), the generator voltage command is decreased (S1407). When the winding command is not ON, a predetermined value is set for the generator voltage setting (S1410).

These SOC and battery voltage predetermined values (α, β), generator voltage setting reference values and correction amounts (SV ₀ , ΔSV) are predetermined values, for example, stored in a memory of a computer that performs control. It may be held.

  15 and 16 are diagrams showing test results when a simulation test is performed based on the above control. FIG. 15 shows the test results when the generator voltage setting is constant, and FIG. 16 shows the test results when the generator voltage setting according to the present invention is adjusted according to the SOC. In the test, winding and unwinding of the rated load (40.6 t) and unloading and unwinding were performed 10 times each in one hour. As shown in FIGS. 15 and 16, when comparing the SOC, when the generator voltage setting of FIG. 15 is constant, the SOC greatly decreases, whereas in the case of the present invention of FIG. It can be seen that the change in is small and the vicinity of the predetermined value is maintained. As a result, according to the method of the present invention, it was confirmed that the secondary battery was not overcharged or overdischarged.

  A system configuration according to still another embodiment of the present invention is shown in FIG. The embodiment shown in FIG. 17 is a hybrid system of a construction machine, and the work motor 54 is preferably a traveling motor. It may be a motor for driving a hydraulic pump in the hydraulic unit. The construction machine is preferably a wheel loader, but may be another construction machine.

  Since FIG. 17 conforms to FIG. 2, the description thereof is omitted. The control operation flow is also the same as that in FIG.

  FIG. 18 is an SOC characteristic diagram showing a voltage change with respect to SOC (state of charge) of various batteries and the like. Curve a shows the voltage change of the nickel metal hydride battery, curve b shows the voltage change of the lead acid battery, curve C shows the voltage change of the lithium ion battery, and curve d shows the voltage change of the electric double layer capacitor.

  The voltage change with respect to the SOC fluctuation is about 0.1 for a nickel metal hydride battery, about 1.5 for a lead acid battery, about 2 for a lithium ion battery, and about 3 for an electric double layer capacitor. That is, with the same voltage change, the nickel-metal hydride battery can be reduced to 1/15 of the lead storage battery, 1/20 of the lithium ion battery, and 1/30 of the electric double layer capacitor.

  As shown in FIG. 18, the nickel metal hydride battery indicated by curve a has stable voltage characteristics over a wide range S of SOC compared to other batteries and the like. That is, the nickel-metal hydride battery has a small battery voltage fluctuation with respect to the SOC fluctuation. Compared with this, in other batteries indicated by curves b, C, d, the battery voltage varies greatly with respect to the SOC. For example, in terms of the median SOC, nickel metal hydride batteries can be used in almost all ranges of SOC when the median voltage is Vl and the voltage fluctuation is within the range dVl. The capacity can be used effectively. On the other hand, when the lead-acid battery is used so that the median voltage is V2 and the voltage fluctuation falls within the range dV2, the SOC can be used only in a narrow range, and the battery capacity cannot be used effectively. . Similarly, when a lithium-ion battery is used so that the median voltage is V3 and the voltage fluctuation falls within the range dV3, the battery can be used only in a narrow range and the battery capacity cannot be used effectively. . Here, the magnitude of the voltage fluctuation range is normalized by the median value of the voltage, and dVl / Vl = dV2 / V2 = dV3 / V3.

  Therefore, when the secondary battery 5 is directly connected to the DC bus 14 as shown in FIG. 2, even if the state of charge (SOC) fluctuates due to repeated charging and discharging of the secondary battery 5, the battery voltage fluctuates greatly. Therefore, the battery capacity can be used effectively.

3. Summary As described above, according to the present embodiment, since the load sharing between the engine generator 13 and the secondary battery 5 can be adjusted according to the SOC value of the secondary battery 5, the DC bus of the inverter 3 can be adjusted. 14, the SOC of the secondary battery 5 can be adjusted to an appropriate range, and overdischarge and overdischarge of the secondary battery 5 can be prevented. The battery life can be extended. Further, since the regenerative power can be stored in the secondary battery 5 and used effectively, the fuel efficiency of the engine generator 13 is indirectly improved.

  Nickel metal hydride batteries have low internal resistance, and voltage fluctuations due to fluctuations in SOC (state of charge) are small and battery capacity can be used effectively. Therefore, batteries with smaller capacities than other secondary batteries can be used. Does not require a large installation site. Moreover, since the secondary battery 5 can be directly connected to the DC bus of the inverter by using a nickel-metal hydride battery having a small change in battery electromotive force due to the SOC as the secondary battery 5, the secondary battery 5 The charge / discharge control device for controlling the charge / discharge of the secondary battery 5, which is necessary in the prior art, is unnecessary between the DC bus and the DC bus. According to this embodiment, since no charge / discharge control device is used, an installation space for the charge / discharge control device is not required. Further, since an expensive charge / discharge control device is not used, the entire device becomes inexpensive.

  When the secondary battery 5 is directly connected to the DC bus 14, charging / discharging of the secondary battery 5 is determined by the difference between the electromotive force of the secondary battery 5 and the voltage of the DC bus 14 of the inverter 3. May become overcharged or overdischarged. However, according to the present embodiment, when the operation command is input, the engine generator 13 and the secondary battery 5 appropriately share the load based on the SOC of the secondary battery 5 calculated by the battery monitor 6. Since this can be performed, overdischarge of the secondary battery 5 can be prevented.

  According to the method of the present invention, the load sharing at the time of winding by the engine generator 1 and the secondary battery 5 is appropriately determined by the respective voltages, so that the electric power accumulated in the secondary battery 5 by regeneration is compensated at the time of engine idling. The power supply to the machine 10 can be sufficiently used. As a result, it is possible to prevent the engine from operating at a low load with poor fuel consumption, and to improve the fuel consumption as a whole.

4). In this embodiment, the case where the motor 4 is a hoisting motor has been described. However, the motor 4 is a traversing motor for traversing the traverser 105 or a traveling motor for traveling the tire 107. It may be. Even in this case, the present embodiment can be applied. That is, the load sharing between the engine generator 13 and the secondary battery 5 is appropriately performed by appropriately determining the generator voltage setting while the vehicle is traveling and while the vehicle is traveling. Thereby, the overdischarge of the secondary battery 5 can be prevented. Furthermore, at the end of traveling or at the end of traversal, the regenerative power from these work motors 4 can be effectively stored in the secondary battery 5 and fuel consumption can be reduced.

  The secondary battery 5 may be a power storage facility other than the nickel metal hydride battery. For example, the secondary battery 5 may be a lead storage battery, a lithium ion battery, or an electric double layer capacitor. In this case, a charge / discharge control device may be provided between power storage facilities such as a battery or a capacitor, and the voltage of the battery or the like may be appropriately increased or decreased and connected to the DC bus. Even in this case, the predetermined effect of the present invention can be obtained.

  Moreover, the cargo handling machine 100 may be a gantry crane, a jib crane, or the like in addition to RTG.

  According to the control device and the control method of the present invention, the secondary battery can be prevented from being overcharged and overdischarged, which is useful for a cargo handling machine and a construction machine.

1, 51 Engine control device 2, 52 AVR
3, 53 Inverter 4, 54 Motor 5, 55 Secondary battery 6, 56 Battery monitor 7, 57 Power flow control device 8, 58 Operation command section 9, 59 DC / AC converter 10, 60 Auxiliary machine 11, 61 Engine 12, 62 Generator 13, 63 Engine generator 14, 64 DC bus 31, 81 Converter unit 32, 82 Inverter unit 100 Handling machine 101 Container 103 Spreader 105 Traverser 107 Tire 109 Wire rope

Claims (16)

A control device for a hybrid system including an engine and a secondary battery,
The hybrid system
A working motor,
A secondary battery,
A generator for generating power from the engine,
AVR for adjusting the power generation voltage of the generator;
The secondary battery is connected to a DC bus, and an inverter that performs power conversion for driving the motor from the power supplied from the generator and / or the secondary battery;
With
The controller is capable of adjusting the load sharing between the generator and the secondary battery by adjusting the voltage setting value of the AVR while the motor is being driven. . The hybrid system further includes a battery monitor that calculates a SOC (State of Charge) of the secondary battery,
The control device for a hybrid system according to claim 1, wherein the voltage setting value of the AVR is set according to the SOC value of the secondary battery calculated by the battery monitor. The hybrid system further includes a voltmeter for measuring a terminal voltage of the secondary battery,
The hybrid system control device according to claim 1, wherein a voltage setting value of the AVR is set according to a measurement value of the voltmeter.   The hybrid system according to any one of claims 1 to 3, wherein when the voltage setting value of the AVR is equal to or less than a predetermined setting value, the engine speed is switched from a rated speed to an idle speed. Control device.   The hybrid system control device according to any one of claims 1 to 4, wherein the hybrid system is a hybrid system of a cargo handling machine.   The hybrid system control device according to claim 5, wherein the work motor of the cargo handling machine hybrid system is a hoisting motor for raising a load in the cargo handling machine.   The hybrid system control device according to claim 5, wherein the working motor is a traveling motor for traveling the cargo handling machine.   The hybrid system control device according to claim 5, wherein the work motor is a traverse motor for traversing a load in the cargo handling machine.   The hybrid system control device according to any one of claims 1 to 4, wherein the hybrid system is a hybrid system of a construction machine.   The hybrid system control device according to claim 6, wherein the work motor of the construction machine hybrid system is a pump drive motor for driving a hydraulic pump in the construction machine.   The hybrid system control device according to claim 10, wherein the working motor is a traveling motor for traveling the construction machine.   The control device of a hybrid system according to any one of claims 1 to 11, wherein the secondary battery is charged by regenerative electric power of the work motor.   The control device of a hybrid system according to any one of claims 1 to 12, wherein the secondary battery is a stacked nickel-metal hydride battery. A control method for a hybrid system,
The hybrid system
A working motor,
A secondary battery,
A generator for generating power from the engine,
AVR for adjusting the power generation voltage of the generator;
The secondary battery is connected to a DC bus, and an inverter that performs power conversion for driving the motor from the power supplied from the generator and / or the secondary battery;
With
The control method includes a step of changing a voltage setting value of the AVR in order to adjust a load sharing between the generator and the secondary battery during driving of the motor. Control method. In Claim 14, it further comprises the step of calculating the SOC (State of Charge) of the secondary battery,
The hybrid system control method according to claim 14, further comprising a step of setting a voltage setting value of the AVR in accordance with an SOC value of the secondary battery calculated in the SOC calculation step.   The hybrid system according to claim 14 or 15, further comprising a step of switching the engine speed from a rated speed to an idle speed when the voltage setting value of the AVR becomes equal to or less than a predetermined setting value. Control method.

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