JP2008187865A - Charger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charger that can improve charging efficiency to a battery to be charged and prolong the battery lifetime. <P>SOLUTION: This charger comprises a plurality of switching power sources 2a-2d, which are connected, in parallel with each other and can be controlled to either an operation state, in which a secondary battery 7 is charged or a stop state in which the operation state is stopped; a current detecting section 3, which detects the charging current Io flowing in the secondary battery 7; a power source control section 5, which shifts the switching power sources 2a-2d in the operation state to the stoppage state, to gradually reduce the number of switching power sources 2a-2d, in the operation state along the reduction of the charging current Io detected by the current detecting section 3. The power-source control section 5 determines the switching power sources 2a-2d, that shift to the stop state so as to obtain the averaged operation ratio of each of the switching power sources 2a-2d. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a charging device that charges a battery to be charged (for example, a rechargeable battery such as a secondary battery).

As this type of charging device, a charging device disclosed in Japanese Patent Laid-Open No. 5-64376 is known. This charging device is configured to charge a storage battery by operating a plurality of chargers in parallel, and detects the power of a load supplied via the storage battery when charging the storage battery, and the minimum required according to the load power. Only a limited number of chargers are operated, and the other chargers are operated in a completely stopped state. Thereby, in this charging apparatus, reduction of power supply capacity is achieved.
JP-A-5-64376 (2nd page, FIG. 1)

  By the way, in this conventional charging device, when determining the number of chargers to be operated, only the power of the load is considered, and the state of charge of the storage battery is not considered. In this case, the current value of the current output from each charger also changes depending on the state of charge of the storage battery (for example, whether the battery is almost fully charged or hardly charged). In addition, this type of charger is often configured using a switching power supply, but in general, the switching power supply has a lighter load (the output current decreases) as shown in FIG. Accordingly, the power supply efficiency is reduced. Therefore, in the charging device using the switching power supply for each charger while adopting the configuration of this charging device, an operation for determining the number of chargers to be operated according to the charging current is performed when charging the storage battery. Therefore, there is a problem that the charging efficiency of the entire apparatus is lowered. Moreover, since the operating rate of the charger to be operated is not taken into consideration, there is a possibility that the operating rate of a specific charger may protrude, thereby causing a problem that the lifetime of the entire charging device is reduced. .

  The present invention has been made to solve such a problem, and a main object of the present invention is to provide a charging device capable of improving the charging efficiency of a battery to be charged and extending the service life.

  In order to achieve the above object, the charging device according to claim 1 is connected in parallel to each other and can be controlled to one of an operating state for charging the battery to be charged and a stopped state for stopping the operating state. A plurality of switching power supply units, a current detection unit that detects a charging current flowing through the battery to be charged, and the switching power supply unit in the operating state is stopped as the charging current detected by the current detection unit decreases. And a power supply control unit that gradually reduces the number of switching power supply units in the operating state, wherein the power supply control unit averages the operating rate of each switching power supply unit The switching power supply unit to be shifted to the stopped state is determined.

  According to a second aspect of the present invention, in the charging device according to the first aspect, the power supply control unit randomly determines the switching power supply unit to be shifted to the stopped state.

  The charging device according to claim 3 is the charging device according to claim 1, wherein the power supply control unit calculates a cumulative time of the operating state for each of the switching power supply units. The switching power supply unit to be shifted to the stopped state is determined so as to be averaged.

  In the charging device according to the first aspect, the power supply control unit gradually decreases the number of the switching power supply units in the operating state as the charging current flowing through the charging target battery detected by the current detection unit decreases. Therefore, according to this charging device, it is possible to sufficiently reduce the situation where the switching power supply unit operates in a light load state that is not efficient, and as a result, the efficiency of the switching power supply unit, and thus the entire device, can be increased. Charging efficiency for the battery to be charged can be sufficiently improved. In addition, the power supply control unit determines the switching power supply unit to be shifted to the stop state so that the operation rate of each switching power supply unit is averaged, so that the switching power supply unit in the operation state is stopped according to a preset order. Unlike the configuration that shifts to the above, even if the charging process is performed on the charging target battery with various battery capacities, it is possible to avoid the bias that only the operating rate of the specific switching power supply unit is increased. Product life can be sufficiently improved.

  According to the charging device of claim 2, the power supply control unit randomly determines the switching power supply unit to be shifted from the operation state to the stop state, thereby averaging the operation rate of each switching power supply unit with a simple configuration. can do.

  Further, in the charging device according to claim 3, the power supply control unit calculates the accumulated time of the operation state for each switching power supply unit, and makes the switching power supply shift to the stopped state so that each accumulated time is averaged. Determine the part. Therefore, according to this charging device, the operating rates of the respective switching power supply units can be averaged with high accuracy, so that the product life of the entire device can be further improved.

  Hereinafter, the best mode of a charging apparatus according to the present invention will be described with reference to the accompanying drawings. In addition, the structure which charges a secondary battery (specifically lead acid battery) as an example of a charge object battery is given and demonstrated.

  As shown in FIG. 1, the charging device 1 includes a plurality of switching power supply units 2 a to 2 d (hereinafter also referred to as “switching power supply unit 2” when not distinguished), a current detection unit 3, a storage unit 4, and a power supply control unit 5. As an example, the AC voltage Vi is input from the AC power source 6 to generate the DC voltage Vo and the secondary battery 7 can be charged by outputting the DC voltage Vo.

  Each switching power supply unit 2 is formed by a switching power supply circuit having the same configuration as an example, and has a power supply capacity (maximum output current) and current output characteristics (charging efficiency (current output efficiency) with respect to output current I). Change characteristics) are almost the same. As an example, each switching power supply unit 2 has a maximum output current of 15 [A] and has a current output characteristic shown in FIG. In this example, as an example, since the secondary battery 7 in which the charging current Io flows at a maximum of about 60 [A] during charging is used as the charging target battery, the number of the switching power supply units 2 is the switching power supply units 2a and 2b. , 2c, 2d. Each of the switching power supply units 2a, 2b, 2c, and 2d is either in an operating state in which the secondary battery 7 is charged or in a stopped state in which the operating state is stopped by each control signal S1, S2, S3, S4. It is configured to be controllable to the state. Each switching power supply unit 2 has a pair of input terminals (not shown) connected to the input terminals P1 and P2 of the charging device 1, respectively, and a pair of output terminals (not shown) as a pair of output lines L1, They are connected to a pair of output terminals P3 and P4 of the charging device 1 via L2 and connected in parallel to each other.

  The current detection unit 3 is connected (intervened) to one of the output lines L1 and L2 (in this example, the output line L2), and detects the current value I1 of the charging current Io flowing through the secondary battery 7. Output. The storage unit 4 is composed of a semiconductor memory such as a ROM or a RAM. Further, the storage unit 4 stores in advance an operation program for the power supply control unit 5 and a reference current value Ir for the charging current Io. In this example, three reference current values Ir1, Ir2, and Ir3 (Ir1> Ir2> Ir3) are stored in advance as reference current values Ir corresponding to the number of each switching power supply unit 2. The power supply control unit 5 includes a CPU (not shown) and the like, and executes a charging process according to an operation program stored in the storage unit 4 to charge the secondary battery 7. In this charging process, the power supply control unit 5 executes control for each switching power supply unit 2 by outputting the control signals S1, S2, S3, and S4.

  Next, operation | movement of the charging device 1 is demonstrated with reference to FIGS. As an example, an example in which the secondary battery 7 having a DC voltage of 48 [V] and a battery capacity of 485 [Ah] is charged from the state where the remaining capacity is 25 [%] until it is almost fully charged will be given. explain. The charging current value I1 flowing through the secondary battery 7 having a remaining capacity of approximately 0 [%] is about 60 [A] at the maximum. In addition, it is assumed that the reference current values Ir1, Ir2, and Ir3 are set to 40 [A], 28 [A], and 14 [A], respectively, as an example.

  First, when the charging device 1 is activated in a state where the discharged secondary battery 7 is connected between the output terminals P3 and P4, the current value of the charging current Io that the current detection unit 3 flows to the secondary battery 7 is activated. While the detection of I1 is started, the power supply control part 5 starts the charging process with respect to the secondary battery 7. FIG.

  In this charging process, as shown in FIG. 3, the power supply control unit 5 first outputs each control signal S1, S2, S3, S4 to each switching power supply unit 2, thereby causing each switching power supply unit 2 to operate. The operation state is shifted (step 51). Thereby, according to the charging state of the secondary battery 7, the switching power supply unit 2a starts to output the charging current Ia, the switching power supply unit 2b starts to output the charging current Ib, and the switching power supply unit 2c starts to output the charging current Ic. The switching power supply unit 2d starts outputting the charging current Id. As a result, the charging current Io having a current value I1 (about 58 [A], see FIG. 2) equal to the sum of the current values of the charging currents Ia to Id is supplied to the secondary battery 7 via the output lines L1 and L2. Start to be supplied. In addition, since each switching power supply part 2 has substantially the same current output characteristics and the like, the charging currents Ia, Ib, Ic, and Id are substantially equal current values (about 14.5 [A] at the beginning of charging, respectively). It has become.

  Next, the power supply control unit 5 detects the current value I1 of the charging current Io output from the current detection unit 3 (step 52), and compares the detected current value I1 with the reference current value Ir1 read from the storage unit 4 (Step 53) is repeatedly executed. As the charging of the secondary battery 7 proceeds, the current value I1 of the charging current Io gradually decreases, and accordingly, the load on each switching power supply unit 2 gradually decreases. As a result, as shown in FIG. 2, as the current value I1 of the charging current Io approaches 41 to 40 [A], the efficiency of each switching power supply unit 2 in the operating state (also the efficiency of the charging device 1) is increased. It gradually decreases from about 92% at the beginning of charging.

  Thereafter, when the current value I1 of the charging current Io decreases to the reference current value Ir1 (= 40 [A]), that is, when the charging current value of each switching power supply unit 2 decreases to about 10 [A] In step 53, the power supply control unit 5 detects this, determines one switching power supply unit 2 to be stopped at random (switching power supply unit 2a as an example), and outputs the control signal S1 to the switching power supply unit 2a. Stop. Thereby, switching power supply part 2a stops an operation state, and shifts to a stop state which does not generate charge current Ia (Step 54). As a result, the number of switching power supply units 2 in the operating state is reduced to three, and as a result, the load of each switching power supply unit 2 increases (charging currents Ib, Ic, Id are about 13.3 [A], respectively). Therefore, as shown in FIG. 2, the efficiency of each of the switching power supply units 2b, 2c, and 2d in the operating state (which is also the output efficiency of the charging device 1) returns to about 92% at the beginning of charging. Thereby, the charging efficiency with respect to the secondary battery 7 as the whole charging device 1 improves.

  Subsequently, the power supply control unit 5 executes the operations in Steps 52 to 54 described above in Steps 55 to 57 by replacing the reference current value Ir1 with the reference current value Ir2 (= 28 [A]). . As a result, as shown in FIG. 2, the efficiency (charging efficiency) of each switching power supply unit 2b, 2c, 2d (charging device 1) as a whole is around 30 [A] when the current value I1 of the charging current Io is cut below 30 [A]. Although it starts to decrease, the power supply controller 5 detects the current value I1 of the charging current Io (step 55), and detects this when the current value I1 reaches the reference current value Ir2 (step 56). One switching power supply unit 2 to be stopped is randomly determined (for example, the switching power supply unit 2b), and the output of the control signal S2 to the switching power supply unit 2b is stopped. As a result, the switching power supply unit 2b shifts from the operating state to the stopped state (step 57), the number of switching power supply units 2 in the operating state is reduced from three to two, and the load of each switching power supply unit 2 is reduced. Since the charging currents Ic and Id increase to about 14 [A], respectively, the overall efficiency of the switching power supply units 2c and 2d in the operating state (output efficiency of the charging device 1) is increased as shown in FIG. It will return to about 92% of the initial charge. Thereby, the charging efficiency with respect to the secondary battery 7 as the whole charging device 1 improves.

  Next, the power supply controller 5 executes the operations in steps 52 to 54 in steps 58 to 60 by replacing the reference current value Ir1 with Ir3 (= 14 [A]). Thereby, as shown in FIG. 2, the efficiency of each of the switching power supply units 2c and 2d (charging device 1) gradually decreases and reaches about 90% as the current value I1 of the charging current Io decreases. The power supply control unit 5 detects the current value I1 of the charging current Io (step 58), and detects the current value I1 when it reaches the reference current value Ir3 (step 59), and stops the switching power supply unit. 2 is randomly determined (for example, the switching power supply unit 2c), and the output of the control signal S3 to the switching power supply unit 2c is stopped. As a result, the switching power supply unit 2c shifts from the operating state to the stopped state (step 60), the number of switching power supply units 2 in the operating state decreases from two to one, and the load of the switching power supply unit 2d increases. (Charging current Id increases to 14 [A]), as shown in FIG. 2, the efficiency of switching power supply unit 2d in the operating state (which is also the output efficiency of charging device 1) is about 92% of the initial charge. Return. Thereby, the charging efficiency with respect to the secondary battery 7 as the whole charging device 1 improves.

  Thereafter, the power supply control unit 5 detects the state of charge of the secondary battery 7 (step 61), and determines whether or not the secondary battery 7 has reached a fully charged state based on the detected state of charge (step 62). ) Repeatedly. In step 61, the power supply control unit 5 is based on, for example, the current value I1 of the charging current Io or the battery voltage of the secondary battery 7 (the voltage across the battery detected by a voltage detection unit (not shown)). The charging state of the secondary battery 7 is detected. As the secondary battery 7 approaches the fully charged state, as shown in FIG. 2, the charging current Io gradually decreases and the load becomes lighter, and accordingly, the efficiency gradually decreases. Note that the relationship between the charging current Io and the efficiency of the charging device 1 is equal to the current output characteristic of one switching power supply unit 2d in the operating state. Finally, when the power supply control unit 5 determines in step 62 that the secondary battery 7 has reached full charge, the power supply control unit 5 stops outputting the control signal S4 to one switching power supply unit 2d in the operating state (step 63). ). Thereby, the charging process is completed.

  Thus, in this charging device 1, the power supply control unit 5 gradually reduces the number of switching power supply units 2 in the operating state as the charging current Io flowing through the secondary battery 7 detected by the current detection unit 3 decreases. Reduce to. Therefore, according to this charging device 1, since the situation where the switching power supply unit 2 operates in an inefficient light load state can be sufficiently reduced, the efficiency of the switching power supply unit 2, and thus the charging device 1 as a whole is increased. As a result, the charging efficiency for the secondary battery 7 can be sufficiently improved. Moreover, in this charging device 1, when the power supply control part 5 transfers the switching power supply part 2 of an operation state to a stop state in order to suppress the fall of the efficiency accompanying the reduction | decrease of the charging current Io, each switching power supply part 2 The switching power supply unit 2 to be shifted to the stopped state is determined so that the operation rates of the two are averaged. For this reason, according to this charging device 1, unlike the configuration in which the switching power supply unit 2 in the activated state is shifted to the stopped state in accordance with a preset order, the charging process for the secondary battery 7 having various battery capacities is performed. However, as a result of avoiding the bias that only the operating rate of the specific switching power supply unit 2 increases, the product life of the entire charging device 1 can be sufficiently improved. In particular, according to the charging apparatus 1, the power supply control unit 5 randomly determines one switching power supply unit 2 to be shifted from the operating state to the stopped state, thereby reducing the operating rate of each switching power supply unit 2 with a simple configuration. Can be averaged.

  In addition, this invention is not limited to above-described embodiment, The structure can be changed suitably. For example, the example in which the switching power supply unit 2 to be shifted from the operating state to the stopped state is determined at random has been described above. However, the power supply control unit 5 calculates the cumulative time of the operating state for each switching power supply unit 2 respectively. It is also possible to employ a configuration that determines the switching power supply unit 2 to be shifted to the stopped state so that the time is averaged. In this case, the power supply control unit 5 calculates the accumulated time of the operating state of each switching power supply unit 2 by integrating the output times of the control signals S1 to S4 output to the switching power supply units 2a to 2d. According to this configuration, the operating rate of each switching power supply unit 2 can be averaged with high accuracy, so that the product life of the entire charging device 1 can be further improved.

  In addition, the configuration in which the number (the same number) of reference current values Ir1 to Ir3 corresponding to the number of each switching power supply unit 2 is previously stored in the storage unit 4 has been described above, but although not illustrated, for example, operation of an operation panel, a keyboard, or the like It is also possible to employ a configuration in which a unit can be provided and the values of the respective reference current values Ir1 to Ir3 can be arbitrarily set.

It is a lineblock diagram of charging device 1 concerning an embodiment of the invention. It is a characteristic view which shows the relationship between the charging current Io of the charging device 1, and efficiency. 3 is a flowchart for explaining an operation in a charging process of the charging device 1; It is a characteristic view which shows the relationship between the charging current about the switching power supply part 2 of the charging device 1, and efficiency.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Charging device 2, 2a, 2b, 2c, 2d Switching power supply unit 3 Current detection unit 4 Storage unit 5 Power supply control unit 7 Secondary battery Io Charging current

Claims (3)

A plurality of switching power supply units connected in parallel to each other and controllable to any one of an operation state for charging the battery to be charged and a stop state for stopping the operation state;
A current detector for detecting a charging current flowing in the battery to be charged;
As the charging current detected by the current detection unit decreases, the power supply control unit gradually shifts the number of switching power supply units in the operating state by shifting the switching power supply unit in the operating state to the stopped state. A charging device comprising:
The said power supply control part is a charging device which determines the said switching power supply part made to transfer to the said stop state so that the operation rate of each said switching power supply part may be averaged.   The charging device according to claim 1, wherein the power supply control unit randomly determines the switching power supply unit to be shifted to the stopped state.   The power supply control unit calculates a cumulative time of the operating state for each of the switching power supply units, and determines the switching power supply unit to shift to the stopped state so that the cumulative time is averaged. Item 2. The charging device according to Item 1.

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