JP4030932B2 - Battery charger for vehicle - Google Patents

Description

  The present invention relates to a vehicle battery charger for charging a vehicle battery.

  2. Description of the Related Art Conventionally, an electric vehicle that operates by receiving power supply from a battery, such as an industrial vehicle such as a battery-type forklift or an electric vehicle, is known. And in this kind of vehicle, since it is necessary to charge a battery, the charging device for battery charging is provided separately.

In addition, this type of charging device includes a quasi-constant voltage method utilizing the characteristics of the transformer, a constant voltage charging method, a constant current method that charges the battery with a constant current, and a charging current at the start of charging. Of the multistage constant current method that charges the battery by switching the charging current step by step so that the charging current is low at the end of charging, or the charging current to the battery is controlled to a constant current at the start of charging. When the voltage reaches a target voltage (in general, a reversal voltage that is a voltage at which gas starts to be generated from the battery liquid during charging), a constant current-constant voltage method that controls the charging voltage to the battery to the target voltage, etc. Various charging systems are known (see, for example, Patent Documents 1 and 2).
JP 2003-87991 A Japanese Patent No. 3069090

  By the way, in a storage battery (generally a lead storage battery) used as an in-vehicle battery, in the case of a charging device using constant voltage charging (including constant voltage region of constant current constant voltage charging) or semi-constant voltage charging method, the temperature is high. The charging current increases, and the charging current decreases when the temperature is low. For this reason, it is considered that the battery temperature is detected and the charging conditions such as the charging time and the charging voltage are set according to the detected battery temperature. That is, by setting the charging conditions (charging time, charging voltage, etc.) of the battery according to the battery temperature, the amount of charge to the battery can be optimally controlled without excess or deficiency.

  However, when the battery charging conditions are set according to the battery temperature in this way, the temperature sensor for temperature detection is incorporated in the charging device and detects the ambient temperature near the battery. Depending on the battery temperature, the temperature detected by the temperature sensor may not correspond to the battery temperature, and the battery charging condition may not be set appropriately according to the battery temperature.

  In other words, since the battery to be charged is mounted on the vehicle, and the on-board battery is provided in the charging device, and the battery temperature cannot be directly detected by the temperature sensor on the charging device side. When the charging condition is set according to the temperature, the temperature around the charging device is detected by the temperature sensor, and the battery charging condition is set according to the detected temperature.

  In this case, since the temperature detected by the temperature sensor is affected by the temperature of the charging device itself, for example, in the case where a plurality of batteries are sequentially charged sequentially by the charging device, charging associated with charging is performed. If the temperature detected by the temperature sensor does not correspond to the actual battery temperature due to the heat generated by the device itself, and the charging condition is set every time charging of the battery is started, charging is performed at the second and subsequent charging of the battery. There arises a problem that the conditions cannot be set properly.

  The present invention has been made in view of these problems, and in order to prevent an excess or deficiency in the amount of charge, a charging device for a vehicle battery in which charging conditions are set in accordance with the ambient temperature, The purpose is to allow the charging conditions to be set properly at all times without being affected by the generated heat.

In the vehicle battery charging device according to claim 1, which is made to achieve this object, when a charging start command is input from the outside, first, the determination unit starts from the previous charging end time by the charging device. The elapsed time up to the current time is calculated as the charge stop time, and it is determined whether or not the charge stop time is equal to or longer than a preset time.

  Then, when the determination unit determines that the charging stop time is equal to or longer than the set time, the charging condition setting unit sets the charging condition according to the ambient temperature detected by the detection unit, and the determination unit If it is determined that the charging stop time is shorter than the set time, the condition setting prohibiting unit prohibits the charging condition setting operation by the charging condition setting unit, and the charging condition used at the previous charging is changed to the current charging condition. Set as.
  Then, when the current charging condition is set by the charging condition setting unit or the condition setting prohibiting unit as described above, the control unit controls the charging unit according to the set charging condition and causes the battery to be charged. .

  In other words, when starting charging the battery, if the charge stop time from the completion of the previous charge is shorter than the set time, the temperature of the charging device itself is higher due to the heat generated during the previous charge, Since the temperature detected by the detection means is also considered to be higher than the ambient temperature (and hence the temperature of the battery to be charged next), in the present invention, in such a case, the charging condition for the next charging is used. Is made the same as the charging condition at the time of the previous charging, so that the charging condition is prevented from being set based on an inappropriate temperature.

  For this reason, according to the vehicle battery charging device of the present invention, the charging conditions can be appropriately set without being affected by the heat generated in the charging device due to the charging operation to the battery. As a result, the battery can be always optimally charged while preventing the charge amount from being excessive or insufficient.

  In the present invention, when it is determined that the charging stop time is short and the temperature detected by the detecting means does not correspond to the ambient temperature (in other words, the battery temperature), the charging condition used at the previous charging is changed to the next charging. However, if the charging stop time is short, the ambient temperature (and hence the temperature of the battery to be charged) will not fluctuate greatly, and the next charging condition will be This is because the battery can be charged satisfactorily even if it matches the previous charging condition.

  Here, the charging condition setting means is for preventing an excess or deficiency in the amount of charge caused by a change in charging current due to a temperature change, and the charging condition to be set is when charging the battery at a constant voltage. The target voltage, the time for applying a constant voltage or a constant current (that is, the charging time), etc. may be set according to the ambient temperature detected by the detecting means.

  Specifically, as described in claim 2, the control means controls the charging means so that the charging current to the battery becomes a constant current in the initial stage after the start of charging the battery. When configured to control the charging unit so that the voltage supplied from the charging unit to the battery becomes the target voltage when the voltage reaches the target voltage (that is, the constant current-constant voltage method described above or described later) The charging condition setting means is configured to set the target voltage used for control by the control means in accordance with the ambient temperature detected by the detection means. That's fine.

  Further, for example, as described in claim 3, when a charging time from the charging unit to the battery is set as one of the charging conditions used by the control unit to control the charging unit, the charging condition The setting means may be configured to set the charging time according to the ambient temperature detected by the detection means.

  On the other hand, the present invention may be applied to a charging device mounted on a vehicle together with a battery. However, as described in claim 4, a so-called stationary charging configured separately from a vehicle mounted with a battery. If applied to the apparatus, the effect can be further exhibited.

  That is, a stationary charging device configured separately from a vehicle may be used to sequentially and sequentially charge a battery mounted on a plurality of vehicles, compared to a charging device mounted on a vehicle. Therefore, if the present invention is applied, it is possible to prevent the amount of charge to the battery from being excessive or insufficient and to charge the battery of each vehicle optimally.

  In this case, the stationary charging device may be installed in a charging area where a vehicle equipped with a battery can enter, and the battery mounted in the vehicle may be directly charged in the charging area. In the charging area, the battery mounted on the vehicle may be replaced with a charged one, and the battery removed from the vehicle by the replacement may be connected to the charging device to charge the battery. In addition, the stationary charging device does not necessarily have to be installed in a charging area where the vehicle can enter, but is installed in an area where the vehicle cannot enter, and the battery removed from the vehicle is carried to the area for charging. It may be.

  Hereinafter, embodiments of the present invention will be described.

  FIG. 1 is a block diagram illustrating an overall configuration of a vehicle battery charging device (hereinafter simply referred to as a charging device) 10 according to an embodiment to which the present invention is applied.

  The charging device 10 according to the present embodiment operates by receiving power from an external commercial power supply (AC power supply) and charges a battery 2 composed of a lead storage battery or the like mounted on an electric vehicle such as a battery-type forklift. For example, it is installed in a predetermined charging area in a factory where a battery-type forklift is used.

  As shown in FIG. 1, the charging device 10 according to the present embodiment includes a step-down transformer 12 that steps down AC power supplied from electrical equipment in a factory via a power cord (not shown), and the step-down transformer 12. A power supply unit 14 that converts the stepped-down AC power source into DC and supplies it to an external battery 2 mounted on the vehicle, and current detection that detects current and voltage supplied from the power supply unit 14 to the battery 2 respectively. Unit 16 and voltage detection unit 18, control unit 20 for charging battery 2 with a predetermined charging pattern by controlling power supply unit 14 based on detection signals from current detection unit 16 and voltage detection unit 18, and control unit 20 is provided with an operation panel 22 for instructing the start / stop of charge control to 20 and a temperature sensor 24 for detecting the ambient temperature.

  Here, the temperature sensor corresponds to the detection means of the present invention, and for example, a thermistor or the like is used.

  The power supply unit 14 corresponds to the charging means of the present invention, and rectifies the AC power source stepped down by the step-down transformer 12 with a rectifier element to generate a DC voltage, and the generated DC voltage Is supplied to the battery 2 via a power control semiconductor element (IGBT, SCR, etc.).

  The step-down transformer 12 is for stepping down the AC power supply. The reason for using the step-down transformer 12 is that the green is used for preventing electric shock and the power factor is improved by optimizing the charging voltage. It is also for the purpose.

  On the other hand, the control unit 20 is constituted by a microcomputer including a CPU, a ROM, a RAM, and the like, and when a charge start command to the battery 2 is input from the operation panel 22, the detection units 16 and 18 receive the command. Based on the detection signal, the power control semiconductor element in the power supply unit 14 is controlled.

  That is, in this embodiment, the operation panel 22 is charged by rapid charging as shown in FIG. 2 so that three charging methods of rapid charging, automatic charging, and equal charging can be selected as charging methods for the battery 2. Button 22a for instructing start / stop of charging, an operation button 22b for instructing start / stop of charging by automatic charging, and an operation button 22c for instructing start / stop of charging by equal charging Is provided. The operation panel 22 is also provided with charging notification pilot lamps PLa, PLb, and PLc that are turned on when the battery 2 is actually charged by each of these charging methods.

  When the user commands the start of charging by automatic charging by operating the operation button 22b, as shown in FIG. 3, immediately after the charging start command is input (initial charging), the control unit 20 detects current detection. The constant current control for controlling the power supply unit 14 is performed so that the charging current detected by the unit 16 becomes a preset first control current (target current) I1, and the voltage detection unit 18 is controlled by the constant current control. When the charging voltage (battery voltage) detected at 1 reaches a preset target voltage (specifically, a reversal voltage at which gas starts to be generated from the battery 2: a so-called gassing voltage) Vg, then current detection is performed. Until the charging current detected by the unit 16 drops to a preset second control current I2 (mid-charging period), the charging voltage detected by the voltage detecting unit 18 is the target voltage (polarization voltage). Vg The constant voltage control for controlling the power supply unit 14 is performed, and when the charging current is reduced to the second control current I2 by the constant voltage control, the power supply unit 14 is controlled so that the charging current becomes the second control current I2. The charging control for the battery 2 is performed by the procedure of executing the second constant current control to be performed (the end of charging).

  Note that the end timing of the second constant current control at the end of charging is defined by the elapsed time from the start of constant voltage control at the middle of charging, and the controller 20 starts the constant voltage control at the middle of charging, When a certain time has elapsed, the charging control is terminated.

  In addition, when the quick charge is instructed via the operation panel 22, the control unit 20 first sets the first time for a certain time (for example, 1 hour) at the initial charging time (at the time of the first constant current control) during the automatic charging. Constant current control (rapid supplementary charging) is performed to control the power supply unit 14 so that the third control current I3 is larger than the control current I1, and then constant current control and constant voltage control are performed in the same procedure as in automatic charging. By performing constant current control, charge control for charging the battery 2 faster than automatic charging is performed.

  In this way, in the rapid charging, rapid supplementary charging is performed with the third control current I3 that is larger than the first control current I1 for a certain time after the start of charging, and thereafter, charging control similar to normal automatic charging is performed. The reason for returning to is to prevent the battery 2 from being damaged.

  And current (3rd control current) I3 at the time of performing quick supplementary charge is about 0.2C-O. 4C [A], the current (first control current) I1 at the time of constant current control after the end of the rapid supplementary charging is smaller than the third control current I3, about 0.1 C to O.D. Set to 2C [A]. However, C represents battery capacity [Ah].

  Furthermore, when an equal charge is instructed via the operation panel 22, the control unit 20 performs constant current control, constant voltage control, and constant current control in the same procedure as automatic charging, and executes control after the middle stage of charging. Charging control is performed to equalize the specific gravity of each cell of the battery 2 by extending the time by a certain time (for example, 1 to 2 hours) compared to the time of automatic charging.

  The control unit 20 corresponds to the charging method of the battery 2 among the pilot lamps PLa to PLc provided on the operation panel 22 when the above charging control is being executed (that is, during charging of the battery 2). The pilot lamp PL is turned on to notify that the battery 2 is currently being charged.

  Further, when the control unit 20 starts charging control in accordance with the charging command input via the operation panel 22, the controller 20 detects the ambient temperature via the temperature sensor 24, and according to the detected ambient temperature, A target voltage (inversion voltage) Vg in the middle of charging, which is a common charging condition for executing each charging control, is set.

  That is, when the battery 2 is charged, the charging current flowing through the battery 2 increases as the temperature of the battery 2 increases. If the charging condition is constant regardless of the temperature of the battery 2, the charge amount of the battery 2 is excessive. Since shortage occurs (specifically, overcharge occurs when the temperature of the battery 2 is high, and shortage occurs when the temperature is low), in this embodiment, when the control unit 20 starts charge control. Then, the ambient temperature of the charging device 10 is detected using the temperature sensor 24, and the charging temperature (inversion voltage Vg) is set assuming that the detected temperature is the temperature of the battery 2, thereby charging the battery 2. It is designed to execute optimally without excess or deficiency.

  In addition, the ambient temperature detected by the temperature sensor 24 substantially matches the outside air temperature when the charging device 10 stops charging the battery 2, and eventually the temperature of the battery 2 mounted on the vehicle. When the charging device 10 starts charging the battery 2 and a charging current is supplied to the battery 2 via the step-down transformer 12 and the power supply unit 14, these units (particularly the step-down transformer 12 and the power supply unit 14) Due to heat generation, the temperature of the charging device 10 itself rises, and the ambient temperature detected by the temperature sensor 24 is also affected by the temperature rise of the charging device 10 itself, and becomes higher than the temperature of the battery 2 to be charged. .

  Therefore, the control unit 20 has a short time (charging stop time) from the end of charging to the battery 2 to the start of charging of the next battery 2, and the temperature of the charging device 10 is increased to the outside air temperature (delayed). Is considered to be inconsistent with the temperature of the battery 2 to be charged), the setting of the charging condition (inversion voltage Vg) using the temperature detected by the temperature sensor 24 is prohibited and set at the previous charging. The charging control of the battery 2 is executed according to the charging condition (polarization voltage Vg).

  Hereinafter, the charging control process executed by the control unit 20 to charge the battery 2 in such a procedure will be described with reference to the flowchart shown in FIG.

  In order to execute the charging control process shown in FIG. 4, a non-volatile memory (EEPROM 20a in this embodiment) is connected to the control unit 20, and control is necessary in the non-volatile memory (EEPROM 20a). Various parameters (inversion voltage Vg, charging end time described later, etc.) are stored.

  In the charge control process shown in FIG. 4, any of the operation buttons 22 a to 22 c provided on the operation panel 22 is operated, and the control unit 20 is charged by any one of charging methods of automatic charging, quick charging, and equal charging. This process is started when a start command is input.

  When this process is started, first, in S110 (S represents a step), the current time (that is, the previous charge end time) stored when the process was executed and ended is read from the EEPROM 20a. Subsequently, in S120, the current time is detected using the built-in clock of the microcomputer constituting the control unit 20. In subsequent S130, an elapsed time from the previous charging end time read in S110 to the current time detected in S120 is calculated as a charging stop time ΔT.

  When the charge stop time ΔT is calculated in this way, it is determined in S140 whether or not the charge stop time ΔT is equal to or longer than a preset set time Δt. This set time Δt is a time during which the ambient temperature (and hence the temperature of the battery 2) can be accurately detected by the temperature sensor 24 without being affected by the heat generated in the charging device 10 during the previous charging. This is a preset charging stop time.

  That is, the set time Δt is within the entire operating temperature range corresponding to the specifications of the charging device 10, and the temperature of the charging device 10 rises most and the temperature detected by the temperature sensor 24 is saturated, as illustrated in FIG. 5. Rapid supplementary charging (constant current control by the third control current I3) at which the temperature becomes TH1 is continuously performed for a predetermined time (for example, 1 hour), and then the charging is stopped, and the temperature detected by the temperature sensor 24 from the stop time. Is set in such a procedure that the time until the temperature falls to coincide with the outside temperature TH2 is measured, and the longest time among the measured times is selected. This set time Δt is set so that it does not exceed 24 hours at the maximum so that the battery can be charged after one day has passed, assuming a day off on a weekend in a factory or the like. It is desirable to do.

  In S140, if the actual charging stop time ΔT is shorter than the set time Δt, the heat generated during the previous charging remains in the charging device 10 and the ambient temperature detected by the temperature sensor 24 is reached. Is determined to be affected by the heat, and the process proceeds to S210. Conversely, when the charging stop time ΔT is equal to or longer than the set time Δt, the charging device 10 is sufficiently dissipated, The temperature detected by the temperature sensor 24 is determined to be substantially the same as the outside air temperature (and thus the temperature of the battery 2), and the process proceeds to S150.

  Next, in S150, the ambient temperature is detected using the temperature sensor 24, and in S160, a reversal voltage Vg, which is a target voltage for constant voltage control in the middle of charging, is set based on the detected temperature.

  Specifically, when the detected temperature is within the reference temperature range of 5 ° C. to 30 ° C., a preset reference voltage VM is set as the inversion voltage Vg, and charging is performed when the detected temperature exceeds 30 ° C. Since the current increases, in order to prevent overcharging, the voltage VL lower than the reference voltage VM is set as the reversal voltage Vg, and the charging current decreases when the detected temperature falls below 5 ° C. In order to prevent the shortage, a voltage VH higher than the reference voltage VM is set as the inversion voltage Vg.

  In the subsequent S170, the reversal voltage Vg set in this way is stored in the EEPROM 20a as a parameter representing the charging conditions during the current charging, and in the subsequent S180, the charging method (automatic operation) commanded via the operation panel 22 is stored. The above-described charging control is performed to control the power supply unit 14 according to charging, quick charging, and equal charging.

  Further, in the subsequent S190, it is determined whether or not the charging of the battery 2 has been completed by the process of S180. If the charging has not been completed, the process proceeds to S180 again to complete the charging of the battery 2. When the charging is completed, the process proceeds to S200, where the current time is detected using the built-in clock of the microcomputer, the current time is stored in the EEPROM 20a as the current charging end time, and the process ends.

  On the other hand, in S210, which is executed when it is determined in S140 that the charging stop time ΔT is shorter than the set time Δt, the inversion voltage Vg which is the charging condition at the previous charging is read from the EEPROM 20a, The reversal voltage Vg is set as the current charging condition, and the process proceeds to S180.

  As a result, when the charging stop time ΔT is shorter than the set time Δt and there is a possibility that the temperature detected by the temperature sensor 24 does not correspond to the outside air temperature (and thus the temperature of the battery 2), in S180, the previous time Charging control is executed using the same reversal voltage Vg as that used during charging.

  As described above, in the charging device 10 of the present embodiment, the ambient temperature is detected using the temperature sensor 24 in order to prevent overcharging or insufficient charging due to the temperature change of the battery 2, and the detected temperature is detected. The inversion voltage Vg, which is a charging condition for the battery 2, is set according to the temperature, but the next battery 2 is charged after the charging of the battery 2 is completed, such as when sequentially charging a plurality of batteries 2. When the time until charging starts (charging stop time) ΔT is shorter than the set time Δt, the temperature sensor 24 is affected by the heat generated by the charging device 10 itself, and the ambient temperature (in other words, the battery 2) is not accurately detected, and the charging condition (inversion voltage Vg) of the battery 2 is set to the same charging condition as in the previous charging.

  For this reason, according to the charging device 10 of the present embodiment, the charging condition (inversion voltage Vg) is appropriately set without being affected by the heat generated in the charging device 10 due to the charging operation of the battery 2. As a result, the battery 2 can be always optimally charged while preventing the charge amount from being excessive or insufficient.

  In the present embodiment, among the charge control processes executed by the control unit 20, the process of S180 functions as the control means of the present invention, and the process of S160 functions as the charge condition setting means of the present invention. The process of S140 functions as a determination unit of the present invention, and the process of S210 functions as a condition setting prohibition unit of the present invention.

  As mentioned above, although one Example of this invention was described, this invention is not limited to the said Example, A various aspect can be taken.

  For example, in the above-described embodiment, the charging condition set according to the temperature detected by the temperature sensor 24 is described as the target voltage (inversion voltage Vg) for constant voltage control performed during the middle charging period. The charging time of the battery 2 such as the charging control execution time until the charging is completed may be set according to the detected temperature.

  Specifically, for example, when the detected temperature is 30 ° C. or higher, the charging time at the end of charging is shortened by a predetermined time (for example, 1 hour) from the normal time, and when the detected temperature is 5 ° C. or lower, the end of charging is performed. Even if the charging time is extended by a predetermined time (for example, 2 hours) from the normal time, the same effect as in the above embodiment can be obtained.

  In addition, when setting the charging conditions (polarization voltage Vg and charging time) according to the detected temperature in this way, the temperature range is divided into three areas as in the above embodiment, and the charging conditions are set for each area. However, the charging condition may be set more finely by further increasing the number of dividing the temperature range.

  Moreover, although the said Example demonstrated the charging device which charges the battery 2 by a constant current-constant voltage-constant current system, even if this invention is a charging device of a constant voltage system, for example, it is a semi-constant voltage. Even if it is a charging device of a system or a charging device of a constant current-constant voltage system, it can apply similarly to the said Example and can acquire the same effect.

  In the above embodiment, the charging device is described as a stationary device provided separately from the vehicle. However, the present invention may be an in-vehicle charging device mounted on a vehicle together with a battery. Applicable.

It is a block diagram showing the whole structure of the charging device of an Example. It is explanatory drawing showing the structure of the operation panel of the charging device of an Example. It is a time chart explaining the charging operation of the charging device of an Example. It is a flowchart showing the charge control process performed in the control part of the charging device of an Example. It is explanatory drawing explaining the setting method of the setting time for charge stop time determination in the charging device of an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 ... Battery, 10 ... Charging apparatus, 12 ... Step-down transformer, 14 ... Electric power supply part, 16 ... Current detection part, 18 ... Voltage detection part, 20 ... Control part, 20a ... EEPROM, 22 ... Operation panel, 22a-22c ... Operation buttons, 24 ... temperature sensors, PLa to PLc ... pilot lamps.

Claims (4)

A vehicle battery charging device comprising a charging means for receiving a power supply from an external power source and supplying a charging current to the vehicle battery,
Detection means for detecting the ambient temperature;
When a charge start command is input from the outside, the elapsed time from the previous charge end time by the charging device to the current time is calculated as the charge stop time, and is the charge stop time equal to or greater than a preset set time? Determining means for determining whether or not;
When the determination unit determines that the charging stop time is equal to or longer than the set time, a charging condition setting unit that sets a charging condition according to the ambient temperature detected by the detection unit;
Similar the determination means, wherein when the charging stop time is determined shorter than the set time, prohibits the setting operation of the charge condition by the charging condition setting means, this charging conditions used during the previous charge A condition setting prohibiting means for setting as a charging condition of
When the current charging condition is set by the charging condition setting unit or the condition setting prohibiting unit, the control unit controls the charging unit according to the set charging condition and performs charging of the battery;
Vehicle battery charging apparatus comprising the. The control means controls the charging means so that a charging current to the battery becomes a constant current in an initial stage after the start of charging the battery, and then, when the battery voltage reaches a target voltage, the charging means Configured to control the charging means such that a voltage supplied from the means to the battery becomes the target voltage,
2. The vehicle battery charging device according to claim 1, wherein the charging condition setting means sets a target voltage used for control by the control means in accordance with an ambient temperature detected by the detection means. As one of the charging conditions used by the control means to control the charging means, a charging time from the charging means to the battery is set,
3. The vehicle battery charging device according to claim 1, wherein the charging condition setting unit sets the charging time according to an ambient temperature detected by the detecting unit.   The vehicle battery charging device according to any one of claims 1 to 3, wherein the battery charging device is configured separately from a vehicle on which the battery is mounted.

Images