JP2005143201A - Floating charge control system of battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize floating charge of a battery charger group with high accuracy without being affected by load variation. <P>SOLUTION: The floating charge control system comprises a plurality of battery groups 1 and 2 (B1, Bm) connected in parallel, loads 15 (auxiliary machine L) and 16 (motor M), a prime mover driving generator 12(G) for charging the battery groups 1 and 2 and supplying power to the loads 15 and 16, a charge/discharge control circuit and battery state monitor 23, and a generator controller 25. At the time of floating charge, the generator controller 25 controls the voltage of the generator 12 such that the generator voltage VG has a level slightly higher than the battery voltage VB thus preventing a charging current from flowing into the battery groups 1 and 2 (ΣIB=0). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention is suitable for application to a so-called hybrid system, such as an electric vehicle or an electric propulsion ship, which includes a storage battery as a primary power source and a generator for charging the storage battery, and supplies power from the storage battery and the generator to power. The present invention relates to a floating battery charge control system.

  In a large-capacity system using a storage battery as a primary power source, a lead storage battery and an alkaline storage battery have been frequently used in the past, and 200 to 300 large-capacity single cells are connected in series to form a group, and 2 to 4 groups of this battery group are connected in parallel. What is connected is common. In addition, the lithium ion battery targeted by the present invention has a high energy density, and in recent years, it has been put into practical use in the small capacity field for consumer use and industrial use.

However, large-capacity lithium-ion batteries intended for application to large-capacity systems are in the research and development stage, and future trends are unclear, but at this stage, many small and medium-capacity cells are connected in series and in parallel. It is thought to be done.
In addition, while lithium-ion batteries have the advantage of high energy density, it has been reported that there are dangers of ignition, explosion, etc. due to overcharging, so careful attention and strict monitoring and control are required when charging. It becomes.

By the way, for a plurality of battery groups connected in parallel, so-called floating charging operation is performed in which a charging / discharging current is set to 0 A in order to maintain or maintain a full charge capacity state. FIG. 3 is a schematic diagram showing a floating charging system similar to that disclosed in Patent Document 1, for example.
Here, the power conversion device P using a commercial power source or the like as a power source supplies a power to a load such as the auxiliary machine power L and the electric motor M, so that the charge / discharge current of the fully charged battery group becomes 0A. Although controlled, since a stable power source such as a commercial power source is used here, it can be said that the control is relatively easy.

JP 2002-171680 A (second page, FIG. 5)

  However, in a hybrid system that uses a generator as a power source, a transition to a fully charged battery occurs due to a transient control response / transient variation of the generator voltage control that accompanies load fluctuations such as the auxiliary power L and the motor M. Charging / discharging occurs. In addition, from the point of voltage control accuracy, it is expected that the charging current continuously flows although it is very small. Furthermore, it is difficult to set the charge / discharge current of each battery group to 0 A due to the characteristic variation of the plurality of battery groups. In any case, the occurrence of an overcharged state, whether transient or small, with respect to a fully charged battery is expected to cause significant stress and damage, especially for lithium ion batteries. It is desirable to avoid as much as possible.

  Therefore, an object of the present invention is to accurately control the charge / discharge current in a fully charged state to 0 A even in a hybrid system including a plurality of battery groups connected in parallel and a generator that supplies power to the battery group. It is to be able to avoid dangers such as battery stress (characteristic deterioration), ignition, and explosion due to overcharge.

  In order to solve such a problem, in the invention of claim 1, a plurality of battery groups in which n (natural number of 2 or more) batteries are connected in series are connected in parallel to m (natural number of 2 or more) groups. Each of the battery groups, a load including an electric motor, a prime mover drive generator for charging the plurality of battery groups and supplying power to the loads, and an anti-parallel circuit of a semiconductor element and a diode. A switch connected in series; and a control circuit that performs on / off control of the switch to perform charge / discharge control of the plurality of battery groups and control of the prime mover drive generator; and floating charge by the control circuit When performing the operation, it is detected that charging of all the battery groups is completed, the semiconductor element is turned off to stop the charging operation, and the charging method immediately before full charging is constant current charging or constant current. In the case of the pulse charging method, the generator is switched from constant current control to constant voltage control, and in the case where the charging method immediately before full charging is constant voltage charging or constant voltage pulse charging method, the generator is controlled by constant voltage control. After that, the voltage command of the generator is set to a value slightly higher than the voltage of all the battery groups, and the generator voltage is controlled by the diode to block the generator voltage and allow the charging current to flow. It is characterized by not.

In the invention of claim 2, a load including a plurality of battery groups in which a battery group in which n (natural number of 2 or more) batteries are connected in series is connected in parallel to m (natural number of 2 or more) groups, and an electric motor A prime mover drive generator for charging the plurality of battery groups and supplying power to the load, a switch composed of an anti-parallel circuit of a semiconductor element and a diode and connected in series to each of the battery groups, A control circuit that controls charging and discharging of the plurality of battery groups by controlling on and off of the switch and controls the motor-driven generator, and the control circuit allows constant current charging or constant current pulse charging system, When shifting to the floating charging operation from the middle of the charging operation by either constant voltage charging or constant voltage pulse charging method, the semiconductor element is turned off to stop the charging operation and Is switched from constant current control to constant voltage control when the constant current charging or constant current pulse charging method is used, and when the charging method is constant voltage charging or constant voltage pulse charging method, the generator is controlled. After leaving the voltage control, the voltage command of the generator is set to a value slightly higher than the highest voltage in the battery group, and the generator voltage is controlled by the diode. It is characterized by blocking to prevent charging current from flowing.
In the invention of claim 1 or 2, when the generator is stopped, it is possible to supply power to the load without interruption (invention of claim 3).

According to the present invention, the following effects are brought about.
(1) In a hybrid system including a plurality of battery groups connected in parallel and a generator, when the floating charging operation mode is selected, the semiconductor element in the charging direction is turned off to stop the charging operation, and the generator voltage is changed. Since the generator voltage command VGs (battery voltage + diode layering voltage + α voltage) is slightly higher than the battery group, the generator voltage VG becomes higher than the battery voltage VB. The diodes D1 to Dm in the connected switches 3 to 4 block the generator voltage and do not flow charging current. In addition, since the semiconductor element is OFF, no discharge current flows, and the battery group can obtain an ideal floating state that can maintain or maintain a fully charged state without being affected by disturbance due to load fluctuations.

(2) Floating charge regardless of the state of full charge, charging operation, constant voltage charge, constant current charge, constant voltage pulse charge, battery charge state including constant current pulse charge, charge operation state, and charge method It is possible to shift to floating charging by selecting the operation switch, and to return to the original state by returning selection of the floating charging operation switch.
(3) Even in the floating charging operation state, if the generator is stopped, power can be supplied to the load without interruption through the diodes D1 to Dm in the switches 3 to 4.

FIG. 1 is a schematic diagram showing an embodiment of the present invention.
That is, the circuit shown in FIG. 1 includes batteries B1 to Bm, a generator G, an auxiliary machine L, a propulsion motor M, and the like. The generator G not only charges the batteries B1 to Bm but also the auxiliary machine L and the propulsion motor M. Also supply power.
In the floating charging operation mode in such a configuration, the generator G uses the switches SW1 to SWm inserted in series in each battery group so that the charging current does not flow to the batteries B1 to Bm and the battery is not discharged. On the other hand, generator control is performed so that power is supplied to the auxiliary machine L and the propulsion motor M which are loads.

  Therefore, the floating charging operation from the operation state immediately before the transition to the floating charging operation mode will be described in detail with reference to FIG. In FIG. 2, 1 and 2 are batteries (B1, Bm), 3 and 4 are switch circuits composed of antiparallel circuits of semiconductor elements (Q1, Qm) and diodes (D1, Dm), 5, 6, 9 , 13, 26 are current detectors, 7, 8, 10, and 14 are voltage detectors, 11 is a motor for driving a generator (DE), 12 is a generator (G), 15 is an auxiliary machine (L), 16 is a propulsion motor (M), 17 is a program setting device, 18 is a pulse charge switch (SWP), 19 is a charge changeover switch (SWC), 20 is a floating charge switch (SWH), 21 is a voltage setting device (VRV), 22 is a current setting device (VRI), 23 is a charge / discharge control circuit & battery state monitoring device, 24 is a charge control changeover switch (SWvc), 25 is a generator control device, 27 is a generator field, and 28 to 31 are switches. Indicates.

1) Floating charging operation of a fully charged battery When the battery is fully charged, the charge / discharge control circuit & battery state monitoring device 23 detects and judges this, turns off all the semiconductor elements Q1 to Qm, and stops charging. However, the generator 12 supplies power to the auxiliary machine L and the propulsion motor M by a voltage control operation. Therefore, if “mode 1” is selected or selected in advance by the floating charge switch SWF20, the charge / discharge control circuit & battery state monitoring device 23 receives this signal, and the detection signal of the whole battery voltage detector VDB10. A generator voltage command VGs (battery voltage + diode layering voltage + α voltage) slightly higher than this voltage is output with reference to VBi and provided to the generator control device 25.

The generator control device 25 uses the generator voltage command VGs as a set value, the detection signal VGi of the generator voltage detector VDG14, the detection signal IGi of the generator current detector SHG13, and the generator field current detector SHGF26. Control signal IGfi is used as a feedback signal to output a current IGF of the generator field Gf27 to control the generator voltage. Thus, a stable generator voltage VG can be obtained even if the loads of the auxiliary machine L15, the electric motor M, etc. fluctuate.
In this way, by making the generator voltage VG higher than the battery voltage VB, the diodes D1 to Dm provided in the semiconductor switches 3 to 4 connected to the battery group block the generator voltage, so that the charging current flows. Absent. Moreover, since all the battery groups are already fully charged and each of the semiconductor elements Q1 to Qm is OFF, no discharge current flows.

  That is, the battery group in the fully charged state can obtain an almost ideal floating state that maintains (maintains) the fully charged state without being affected by the load fluctuation, and this floating state turns off the floating charging switch SWF20. Continue until. Naturally, if the generator is stopped, the generator voltage VG decreases. Therefore, the battery group starts discharging through the diodes D1 to Dm, and the power supply to the load is started. It becomes possible. The α voltage is preferably determined in consideration of a voltage fluctuation value associated with the control response of the generator due to a load fluctuation disturbance.

2) Transition from constant current pulse charge operation to floating charge operation The constant current pulse charge operation is a mode in which the charge switch SWC19 is set to “constant current” and the pulse charge switch SWP18 is set to “ON”. & Battery state monitoring device 23 switches charge control changeover switch SW _VC 24 to the “current” side, makes the generator constant current control by IBs according to the current command, and charge / discharge control circuit & battery state monitoring device 23 is a battery. Apply time-sequential ON-OFF signals Q1dv to Qmdv to the semiconductor elements Q1 to Qm connected in series to the group, charge the battery group with a pulsed constant current, and stop charging sequentially from the battery group that has been charged. This is a charging method for fully charging all battery groups.

2-1) Transition from charge completion to floating charge = floating charge switch SWF20 “mode 1”
When the floating charge switch SWF20 is selected as “mode 1” or is selected in advance, the charge / discharge control circuit & battery state monitoring device 23 determines that all the battery groups have been charged, and charging is performed. The control changeover switch SW _VC 24 is switched from “current” to “voltage”, and the generator control is switched from constant current control to constant voltage control. Further, the charge / discharge control circuit & battery state monitoring device 23 uses the detected voltage VBi detected by the total battery voltage detector VDB as a reference, and a generator voltage command VGs (battery voltage + diode layering voltage slightly higher than this voltage). + Α voltage) and output to the generator control device 25.
The voltage control by the generator control device 25 is performed in the same manner as described in paragraph 0015. As a result, the generator voltage VG is higher than the battery voltage VB and is provided in the semiconductor switches 3 to 4 connected to the battery group. Since the generator voltage is blocked by the diodes D1 to Dm, no charging current flows. Moreover, since all the battery groups are already fully charged and the semiconductor elements Q1 to Qm are OFF, no discharge current flows.

2-2) Operation for shifting to the floating charging operation from the middle of the constant current pulse charging operation When it is desired to shift to the floating charging mode from the middle of the constant current pulse charging operation for some reason, the floating charging switch SWF20 is selected to “mode 2”. . Thereby, the charge / discharge control circuit & battery state monitoring device 23 turns off the semiconductor elements Q1 to Qm of all the battery groups to stop the pulse charging operation, and changes the charge control changeover switch SW _VC 24 from “current” to “voltage”. The generator control is switched from constant current control to constant voltage control. Further, the charge / discharge control circuit & battery state monitoring device 23 determines the highest voltage among the battery voltage detectors VD1 to VDmi of the battery group detectors VD1 to VDm as a reference, and is slightly higher than this voltage. A higher generator voltage command VGs (battery voltage + diode layering voltage + α voltage) is output and supplied to the generator control device 25.

The voltage control by the generator control device 25 is performed in the same manner as described above, and the generator voltage VG is controlled to a voltage higher than the highest battery voltage in the battery group. As a result, the generator voltage becomes higher than the voltage of the battery group, the generator voltage is blocked by the diodes D1 to Dm provided in the semiconductor switches 3 to 4 connected to the battery group, and the charging current does not flow.
Also, when releasing the floating charge switch SWF20 from “mode 2”, returning to “OFF” returns to the original constant current pulse charging operation, and if “mode 1” is further selected, all of the constant current pulse charging operation is performed. When the charging / discharging control circuit & battery state monitoring device 23 detects that the battery group of the battery has been fully charged, it automatically shifts to the fully charged floating charging operation. In this state, the floating charging switch SWF20 is turned “OFF”. Continue until Naturally, if the generator is stopped, the generator voltage decreases, so the battery group starts discharging through each diode and starts supplying power to the load.

3) When shifting from constant voltage pulse charge operation to floating charge operation The constant voltage pulse charge operation is a mode in which the charge switch SWC19 is set to “constant voltage” and the pulse charge switch SWP18 is set to ON. The state monitoring device 23 switches the charge control changeover switch SW _VC 24 to the “voltage” side to control the generator to be a constant voltage control using the voltage command VGs as a set value, and further charge / discharge control circuit & battery state monitoring The device 23 applies time-sequential ON-OFF signals Q1dv to Qmdv to the semiconductor elements Q1 to Qm connected in series to the battery group, charges the battery group with a pulsed constant voltage, and sequentially starts from the battery group that has been charged. This is a charging method in which charging is stopped and all battery groups are fully charged.

3-1) Transition from charge completion to floating charge = floating charge switch SWF “mode 1”
When the charging / discharging control circuit & battery state monitoring device 23 determines that all the battery groups have been fully charged when the floating charge switch SWF20 is selected to "mode 1" or is pre-selected, the generator While the control remains constant voltage control, the charge / discharge control circuit & battery state monitoring device 23 uses the detected voltage VBi detected by the total battery voltage detector VDB10 as a reference, and a generator voltage command slightly higher than this voltage. VGs (battery voltage + diode layering voltage + α voltage) is output and supplied to the generator control device 25.
The voltage control by the generator control device 25 is performed in the same manner as described above, and as a result, the generator voltage VG becomes higher than the battery voltage VB. Thereby, the diodes D1-Dm provided in the semiconductor switches 3-4 connected to the battery group block the generator voltage, and the charging current does not flow. Moreover, since all the battery groups are already fully charged and the semiconductor elements Q1 to Qm are OFF, no discharge current flows.

3-2) Operation for Shifting from Constant Voltage Pulse Charging Operation to Floating Charging Operation If it is desired to shift to the floating charging mode from the middle of constant voltage pulse charging operation for some reason, floating charging switch SWF20 is selected to “mode 2”. . As a result, the charge / discharge control circuit & battery state monitoring device 23 turns off the semiconductor elements Q1 to Qm of all the battery groups to stop the pulse operation, and the charge control changeover switch SW _VC 24 remains “voltage”. The generator control is set to constant voltage control. Further, the charge / discharge control circuit & battery state monitoring device 23 determines the highest voltage among the battery voltage detectors VD1 to VDmi of the battery group detectors VD1 to VDm as a reference, and is slightly higher than this voltage. A higher generator voltage command VGs (battery voltage + diode layering voltage + α voltage) is output and supplied to the generator control device 25.

The voltage control by the generator control device 25 is performed in the same manner as described above. As a result, the generator voltage VG is controlled to a voltage higher than the highest battery voltage in the battery group. Thereby, the generator voltage becomes higher than the voltage of the battery group, the generator voltage is blocked by the diodes D1 to Dm provided in the semiconductor switches 3 to 4 connected to the battery group, and the charging current does not flow.
When the floating charge switch SWF20 is released from “mode 2”, it returns to “OFF” to return to the original constant voltage pulse charging operation, and if “mode 1” is selected, all the constant voltage pulse charging operations are performed. When the charging / discharging control circuit & battery state monitoring device 23 detects that the battery group of the battery has been fully charged, it automatically shifts to the fully charged floating charging operation. In this state, the floating charging switch SWF20 is turned “OFF”. Continue until Naturally, if the generator is stopped, the generator voltage decreases, and therefore the battery group starts discharging through each diode, and the power supply to the load is started.

4) When shifting from the constant current charging operation to the floating charging operation If it is desired to shift to the floating charging operation mode for some reason during the constant current charging operation, the charging / discharging control is performed by selecting the floating charging switch SWF20 to “mode 2”. The circuit & battery state monitoring device 23 turns off the semiconductor elements Q1 to Qm of all the battery groups to stop the constant current charging operation, and the charging control changeover switch SW _VC 24 switches from “current control” to “voltage control”. . Further, the charge / discharge control circuit & battery state monitoring device 23 uses the detection voltage VBi detected by the total battery voltage detector VDB10 as a reference, and a generator voltage command VGs (battery voltage + diode layering voltage slightly higher than this voltage). + Α voltage) and output to the generator control device 25.
The voltage control by the generator control device 25 is performed in the same manner as described above, and the generator voltage VG is made higher than the battery voltage VB. Thereby, the diodes D1-Dm provided in the semiconductor switches 3-4 connected to the battery group block the generator voltage, and the charging current does not flow. Moreover, since all the semiconductor elements Q1 to Qm are OFF, no discharge current flows.

  Also, when returning the floating charge switch SWF20, returning to “OFF” returns to the original constant current charging operation, and further selecting “Mode 1”, charging is performed in a pre-programmed charging mode. When the charge / discharge control circuit & battery state monitoring device 23 detects that the battery group has been fully charged, it automatically shifts to a fully charged floating charge operation, and this state turns off the floating charge switch SWF20. Continue until Naturally, if the generator is stopped, the generator voltage decreases, so the battery group starts discharging through each diode, and the power supply to the load is started.

5) When shifting from the constant voltage charging operation to the floating charging operation When it is desired to shift to the floating charging operation mode for some reason during the constant voltage charging operation, the charge / discharge control is performed by selecting the floating charging switch SWF20 to “mode 2”. The circuit & battery state monitoring device 23 turns off the semiconductor elements Q1 to Qm of all battery groups, and the charge control changeover switch SW _VC 24 remains in “voltage” control. Further, the charge / discharge control circuit & battery state monitoring device 23 uses the detection voltage VBi detected by the total battery voltage detector VDB10 as a reference, and a generator voltage command VGs (battery voltage + diode layering voltage slightly higher than this voltage). + Α voltage) and output to the generator control device 25.
The voltage control by the generator control device 25 is performed in the same manner as described above, and the generator voltage VG is made higher than the battery voltage VB. Thereby, the diodes D1-Dm provided in the semiconductor switches 3-4 connected to the battery group block the generator voltage, and the charging current does not flow. Moreover, since all the semiconductor elements Q1 to Qm are OFF, no discharge current flows.

  Further, when the floating charge switch SWF20 is returned, if the SWF is turned “OFF”, the operation returns to the original constant voltage charging operation, and if “mode 1” is selected, the charging is performed in the pre-programmed charging mode. When the charging / discharging control circuit & battery state monitoring device 23 detects that all the battery groups have been fully charged, the state automatically shifts to a fully charged state floating charging operation. Continue until "OFF". Naturally, if the generator is stopped, the generator voltage decreases, so the battery group starts discharging through each diode, and the power supply to the load is started.

Schematic diagram showing an embodiment of the present invention Configuration diagram showing details of FIG. Schematic diagram showing an example of conventional floating charging method

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,2 ... Battery (B1, Bm), 3, 4 ... Switch circuit, 5, 6, 9, 13, 26 ... Current detector, 7, 8, 10, 14 ... Voltage detector, 11 ... Drive motor ( DE), 12 ... Generator (G), 15 ... Auxiliary machine (L), 16 ... Propulsion motor (M), 17 ... Program setting device, 18 ... Pulse charge switch (SWP), 19 ... Charge changeover switch (SWC) , 20 ... floating charge switch (SWF), 21 ... voltage setter (VRV), 22 ... current setter (VRI), 23 ... charge control circuit & battery state monitoring device, 24 ... charge control changeover switch (SWvc), 25 ... generator control device, 27 ... generator field, 28-31 ... switch.

Claims (3)

a plurality of battery groups in which n (natural number of 2 or more) batteries connected in series are connected in parallel to m (natural number of 2 or more) groups, a load including an electric motor, and the plurality of battery groups A motor-driven generator for charging the battery and supplying power to the load; a switch comprising an anti-parallel circuit of a semiconductor element and a diode; and a switch connected in series to each of the battery groups. A control circuit for performing charge / discharge control of the plurality of battery groups and controlling the prime mover drive generator,
When performing the floating charging operation by the control circuit, it detects that the charging of all the battery groups is completed, stops the charging operation by turning off the semiconductor element, and the charging method immediately before full charging is constant current charging or When the constant current pulse charging method is used, the generator is switched from constant current control to constant voltage control. When the charging method immediately before full charging is constant voltage charging or constant voltage pulse charging method, the generator is After the control is left, the generator voltage command is set to a value slightly higher than the total battery group voltage, and the generator voltage is controlled by the diode to block the generator voltage and charge current. A floating charge control system for a battery, characterized in that it does not flow. a plurality of battery groups in which n (natural number of 2 or more) batteries connected in series are connected in parallel to m (natural number of 2 or more) groups, a load including an electric motor, and the plurality of battery groups A motor-driven generator for charging the battery and supplying power to the load; a switch comprising an anti-parallel circuit of a semiconductor element and a diode; and a switch connected in series to each of the battery groups. A control circuit for performing charge / discharge control of the plurality of battery groups and controlling the prime mover drive generator,
When the control circuit shifts to the floating charging operation from the middle of the charging operation by either constant current charging or constant current pulse charging method, constant voltage charging or constant voltage pulse charging method, the semiconductor element is turned off and the charging operation is performed. When the charging method is constant current charging or constant current pulse charging method, the generator is switched from constant current control to constant voltage control, and when the charging method is constant voltage charging or constant voltage pulse charging method. After the generator is kept at constant voltage control, the voltage command of the generator is set to a value slightly higher than the highest voltage in the battery group to perform voltage control of the generator. A battery floating charge control system characterized in that a generator voltage is blocked by a diode so that a charging current does not flow. 3. The battery floating charge control system according to claim 1, wherein when the generator is stopped, power can be supplied to the load without interruption.

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