charger

Abstract

To more exactly determine an abnormality of a current detection system which detects charging current to a battery.SOLUTION: A charge path of a charger is provided with a current detection unit which detects charging current. In addition, the charger is provided with: a first amplifier which amplifies output from the current detection unit to be output as a first detection signal of the charging current; and a second amplifier which similarly amplifies the output from the current detection unit to be output as a second detection signal of the charging current. An abnormality determination unit determines whether or not an abnormality occurs in a detection system of the charging current including the first amplifier and the second amplifier on the basis of the first detection signal to be output from the first amplifier and the second detection signal to be output from the second amplifier.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a charger that determines an abnormality in a current detection system that detects a charging current to a battery. [Background technology]

[0002] Patent document 1 describes a charger that is configured to measure the amount of power being charged to the battery by detecting the charging current using a current detection means provided in the charging path to the battery and integrating the detected charging current at regular intervals.

[0003] In Patent Document 1, the measurement result of the amount of charging power by the charger is transmitted to the battery pack, and the battery pack calculates the amount of power stored in the battery based on the amount of charging power obtained from the charger and the amount of discharged power measured when the battery is discharged. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6207127 Summary of the Invention [Problem to be solved by the invention]

[0005] The charging current detected by the current detection means is used not only to measure the amount of power being charged to the battery, but also to control the charging current to the battery. Therefore, if the current detection means malfunctions and is no longer able to accurately detect the charging current, it will no longer be possible to properly control the charging of the battery.

[0006] For this reason, chargers are usually configured to determine whether the current detection means is faulty based on the charging current detection results. However, faults can only be determined from the charging current detection results when the detection result is 0 or an abnormal value, and faults cannot be determined when the detection result is within the normal range.

[0007] An object of one aspect of the present disclosure is to enable more accurate determination of an abnormality in a current detection system used to detect a charging current to a battery. [Means for solving the problem]

[0008] A charger according to one aspect of the present disclosure includes a charging path, a current detection unit, a first amplifier, a second amplifier, and an abnormality determination unit. The charging path is configured to supply a charging current from a power supply circuit to a battery, and the current detection unit is configured to detect the charging current flowing through the charging path.

[0009] The first amplifier is configured to amplify the output from the current detection unit and output it as a first detection signal of the charging current, and the second amplifier is configured to amplify the output from the current detection unit and output it as a second detection signal of the charging current.

[0010] The abnormality determination unit is configured to determine whether or not an abnormality has occurred in the charging current detection system including the first amplifier and the second amplifier, based on the first detection signal output from the first amplifier and the second detection signal output from the second amplifier.

[0011] In this way, the charger of the present disclosure is configured to detect the charging current in two systems using the first amplifier and the second amplifier, and the detected two-system detection signals are used to calculate the charging current. Therefore, according to the charger of the present disclosure, it is possible to accurately detect an abnormality in the charging current detection system including the first amplifier and the second amplifier. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a perspective view illustrating the appearance of a battery pack and a charger that constitute a charging system according to an embodiment. [Figure 2] FIG. 2 is a block diagram showing the circuit configuration of a battery pack and a charger. [Figure 3]10 is a flowchart showing a charging control process executed in a second MPU of the charger. [Figure 4] 4 is a flowchart showing details of the charging current abnormality detection process shown in FIG. 3. [Figure 5] FIG. 10 is a block diagram showing a modified example of the circuit configuration of the charger. [Figure 6] 10 is a flowchart illustrating a modified example of the charging current abnormality detection process. DETAILED DESCRIPTION OF THE INVENTION

[0013] [Summary of the embodiment] In a charger according to an embodiment, the current detection unit may include a shunt resistor provided on the charging path.

[0014] In this case, the first amplifier and the second amplifier may be configured to amplify the voltage across the shunt resistor and output the amplified voltage as a first detection signal and a second detection signal, respectively. That is, the first amplifier and the second amplifier may be configured to generate two systems of detection signals by amplifying the voltage across the shunt resistor common to each amplifier.

[0015] Additionally / alternatively, the current detection unit may include a first shunt resistor and a second shunt resistor arranged in series on the charging path. In this case, the first amplifier may be configured to amplify the voltage across the first shunt resistor and output it as a first detection signal. Also, the second amplifier may be configured to amplify the voltage across the second shunt resistor and output it as a second detection signal. In other words, the first amplifier and the second amplifier may be configured to generate two systems of detection signals by amplifying the voltage across their respective dedicated shunt resistors.

[0016] Additionally / alternatively, the first amplifier and the second amplifier may each be in the form of independent electronic components. In this way, when the first amplifier and the second amplifier are in the form of independent electronic components, the frequency with which the first amplifier and the second amplifier simultaneously fail can be reduced, making it easier to take measures when an abnormality is detected.

[0017] Additionally / alternatively, the abnormality determination unit may be configured to determine that an abnormality has occurred when the first detection signal and / or the second detection signal is outside a preset tolerance range. In this way, an abnormality in the detection system including the first amplifier and the second amplifier can be accurately and stably detected.

[0018] In this case, the abnormality determination unit may be configured to calculate a first difference between the first detection signal and the target value of the charging current, and a second difference between the second detection signal and the target value of the charging current, and determine that an abnormality has occurred when the first difference and / or the second difference is outside a predetermined tolerance range.

[0019] Alternatively, the abnormality determination unit may be configured to calculate a third difference between the first detection signal and the second detection signal, and determine that an abnormality has occurred when the third difference is outside a preset tolerance range.

[0020] Additionally / alternatively, the abnormality determination unit may be configured to output a command to stop charging the battery when it determines that an abnormality has occurred during charging of the battery. In this way, by stopping charging of the battery when an abnormality is determined, it is possible to prevent deterioration of the battery due to overcharging or the like.

[0021] Additionally / alternatively, the first amplifier and the second amplifier may be configured to output detection signals having different accuracies as the first detection signal and the second detection signal. In this case, the first amplifier may be configured to generate, as the first detection signal, a detection signal with higher accuracy than the second detection signal, and output the generated first detection signal to a control circuit that performs feedback control so that the charging current becomes a target current. In this way, the accuracy of the first detection signal used to control the charging current is higher than that of the second detection signal, and the charging current can be controlled with high accuracy.

[0022] Furthermore, since the second amplifier has lower accuracy in detecting the charging current than the first amplifier, it can be implemented at a lower cost than the first amplifier, which reduces the cost of the charger compared to when the first amplifier and the second amplifier have the same accuracy in detecting the charging current.

[0023] Specific Exemplary Embodiments Exemplary embodiments of the present disclosure will be described below in conjunction with the drawings. As shown in FIG. 1, the charging system of this embodiment includes a battery pack 2 and a charger 40.

[0024] The battery pack 2 houses a battery 10 shown in Fig. 2. The battery pack 2 has a first attachment part 4 for detachably attaching to various electric working machines, such as a rechargeable power tool, a rechargeable vacuum cleaner, or a rechargeable brush cutter, or to a charger 40. When the battery pack 2 is attached to the electric working machine via the first attachment part 4, it is electrically connected to the electric working machine via a first terminal part 6 provided on the first attachment part 4, and power is supplied from the battery 10 to the electric working machine.

[0025] The charger 40 is configured to generate a charging voltage (DC voltage) for charging the battery by receiving power from an external power source (generally a commercial power source: AC voltage) via a power cord 49. For this reason, the charger 40 is provided with a second mounting portion 44 for mounting the battery pack 2.

[0026] The second mounting portion 44 is formed to correspond to the shape of the first mounting portion 4 of the battery pack 2 so that the battery pack 2 can be slid and mounted. The second mounting portion 44 is provided with a second terminal portion 46 that is fitted with the first terminal portion 6 on the battery pack 2 side when the battery pack 2 is mounted.

[0027] When the battery pack 2 is attached to the second attachment portion 44, the charger 40 is electrically connected to the battery pack 2 via the second terminal portion 46, and charges the battery 10 in the battery pack 2 by supplying a charging current to the battery pack 2 at the generated charging voltage.

[0028] As shown in FIG. 2, the first terminal portion 6 on the battery pack 2 side and the second terminal portion 46 on the charger 40 side are provided with terminals 11 to 13 and 41 to 43, respectively, which are connected to each other when the battery pack 2 is attached to the charger 40.

[0029] In the battery pack 2, terminals 11 and 12 are connected to the positive and negative sides of the battery 10, respectively. Therefore, the terminals 11 and 12 are a positive terminal and a negative terminal for passing a charging current supplied from the charger 40 and a discharging current from the battery 10 to the electric work machine. Furthermore, the terminal 13 is a communication terminal for communicating with the charger 40 and the electric work machine. do.

[0030] In the charger 40, terminals 41 and 42 are connected to terminals 11 and 12 of the battery pack 2, respectively, when the battery pack 2 is attached, and are a positive terminal and a negative terminal for supplying a charging current to the battery 10. In addition, terminal 43 is connected to terminal 13 of the battery pack 2 and is a communication terminal for communicating with the battery pack 2.

[0031] The battery 10 in the battery pack 2 is configured by connecting multiple chargeable and dischargeable cells in series. In addition to the battery 10, the battery pack 2 also includes a first MPU 20, an AFE 22, a first communication unit 24, a shunt resistor 26, and a first power supply circuit 28.

[0032] The first MPU 20 is a microprocessing unit including a CPU, a ROM, a RAM, etc. The AFE 22 is an analog front end that performs data communication with the first MPU 20, and inputs various detection signals to the first MPU 20.

[0033] For example, the AFE 22 acquires the battery voltage and the voltage of each cell (cell voltage) from the battery 10 and inputs them to the first MPU 20. The AFE 22 also acquires the battery temperature from a temperature sensor provided in the battery 10 and inputs it to the first MPU 20.

[0034] The shunt resistor 26 is provided in the charge / discharge path 18 that connects the negative electrode of the battery 10 to the terminal 12, and is used to detect the discharge current that flows through this charge / discharge path 18. The AFE 22 measures the discharge current from the battery 10 to the electric work machine based on the voltage across the shunt resistor 26, and inputs the measured value to the first MPU 20.

[0035] The first power supply circuit 28 receives power from the battery 10, generates a power supply voltage (constant DC voltage) Vdd for driving the first MPU 20, the AFE 22, the first communication unit 24, etc., and supplies it to each of these units.

[0036] The first MPU 20 executes various control processes according to programs pre-stored in the ROM. For example, the first MPU 20 executes a process to determine whether an abnormality has occurred during charging or discharging of the battery 10 based on the battery voltage, cell voltage, battery temperature, discharge current, etc. input from the AFE 22.

[0037] If an abnormality is determined in this determination process, the first MPU 20 sends a command to the charger 40 or the electric work machine via the first communication unit 24 to stop charging or discharging the battery 10, thereby stopping charging or discharging the battery 10.

[0038] The first MPU 20 also executes a process of monitoring the amount of power stored in the battery 10 based on the discharge current measured via the shunt resistor 26 and the charge current measured on the charger 40 side.

[0039] Then, based on the amount of power updated in this monitoring process, the first MPU 20 sets the charging current during charging and requests it from the charger 40. Furthermore, when discharging to the electric work machine, based on the amount of power updated in the monitoring process, it determines whether the amount of power stored in the battery 10 has fallen to a stop determination value, and when the amount of power has fallen to the stop determination value, the first MPU 20 stops discharging to the electric work machine.

[0040] Next, the charger 40 converts AC voltage (for example, AC 100V) supplied from an external power source via a power cord 49 into DC voltage for charging the battery, and supplies a charging current to the battery 10. A second power supply circuit 50 is provided for generating

[0041] The positive electrode side of the second power supply circuit 50 and the terminal 41, and the negative electrode side of the second power supply circuit 50 and the terminal 42 are connected to the battery 10 via a charging path 48, respectively.

[0042] The charger 40 also includes a second communication unit 52, a first shunt resistor 54, a first amplifier 56, a second amplifier 58, a second MPU 60, a comparator 62, a photocoupler 64, and a switching IC (hereinafter referred to as SW IC) 66.

[0043] In addition to the charging voltage for the battery 10, the second power supply circuit 50 also generates a power supply voltage Vcc for driving the internal circuits of the charger 40, i.e., the second communication unit 52, the first amplifier 56, the second amplifier 58, the second MPU 60, the comparator 62, etc.

[0044] The second MPU 60 is a microprocessing unit including a CPU, a ROM, a RAM, etc., and is capable of communicating with the battery pack 2 via the second communication unit 52. That is, the second communication unit 52 is connected to the terminal 43. Therefore, when the battery pack 2 is attached to the charger 40, the terminal 43 is connected to the terminal 13 on the battery pack 2 side, and the second MPU 60 can communicate with the first MPU 20 on the battery pack 2 side via the second communication unit 52.

[0045] The first shunt resistor 54 is an electronic component that corresponds to an example of a current detection unit of the present disclosure, and is provided on the negative side of the charging path 48 between the terminal 42 and the second power supply circuit 50. Therefore, the charging current flowing through the charging path 48 can be detected from the voltage across the first shunt resistor 54.

[0046] The first shunt resistor 54 is in the form of a resistor as an electronic component so that its resistance value will not change due to laser trimming, etc. This prevents the first shunt resistor 54 from failing due to a short circuit at the trimming point caused by the flow of charging current.

[0047] In addition to the charging current, a discharging current larger than the charging current flows through the shunt resistor 26 on the battery pack 2 side. Therefore, the shunt resistor 26 is in the form of a resistor alone, an electronic component with a higher rated power than the first shunt resistor 545.

[0048] Next, the first amplifier 56 and the second amplifier 58 each take in the voltage across the first shunt resistor 54 and amplify it to a voltage level that can be input to the second MPU 60, thereby generating a first detection signal Chrg_I_1 and a second detection signal Chrg_I_2 of the charging current.

[0049] The first amplifier 56 and the second amplifier 58 are each configured as a differential amplifier using operational amplifiers, which are independent electronic components, and each operational amplifier has a different offset voltage. Specifically, the offset voltage of the first amplifier 56 is lower than the offset voltage of the second amplifier 58. Therefore, the first amplifier 56 has higher accuracy in detecting the charging current than the second amplifier 58.

[0050] An A / D converter (not shown) included in the second MPU 60 A / D converts the first detection signal Chrg_I_1 and the second detection signal Chrg_I_2, respectively, and captures them as a first current detection value AD_Chrg_I_1 and a second current detection value AD_Chrg_I_2.

[0051] The second MPU 60 then determines whether or not an abnormality has occurred in the charging current detection system based on the first current detection value AD_Chrg_I_1 and the second current detection value AD_Chrg_I_2. The system includes a first shunt resistor 54, a first amplifier 56, and a second amplifier 58. The charging current detection system may further include an A / D converter.

[0052] In this embodiment, the second MPU 60 calculates the difference between the first current detection value AD_Chrg_I_1 and the target value PWM_SET of the charging current, and the difference between the second current detection value AD_Chrg_I_2 and the target value PWM_SET of the charging current, as a first deviation Diff_I_1 and a second deviation Diff_I_2. Then, based on the calculated first deviation Diff_I_1 and second deviation Diff_I_2, an abnormality determination is made in the charging current detection system.

[0053] The target value PWM_SET of the charging current is set according to the charging current (hereinafter, requested current) Bat_Req_I requested by the first MPU 20 of the battery pack 2. Then, the second MPU 60 performs D / A conversion on this target value PWM_SET to generate a signal representing the target current CC_PWM and outputs it to the comparator 62.

[0054] Next, the comparator 62 compares the signal representing the target current CC_PWM input from the second MPU 60 with the first detection signal Chrg_I_1 output from the first amplifier 56, and outputs a difference signal representing the difference between the actual charging current and the target current.

[0055] This difference signal is input to the switch IC 66 via the photocoupler 64. The switch IC 66 is a switching circuit that controls the charging current generated by the second power supply circuit 50 so that the difference signal becomes zero.

[0056] Then, a pulse-width modulated PWM signal for controlling the charging current is output from the switch IC 66 to the second power supply circuit 50. Therefore, in this embodiment, the comparator 62, the photocoupler 64, and the switch IC 66 function as an example of a control circuit that performs feedback control so that the charging current becomes the target current.

[0057] Next, a description will be given of the charge control process executed by the second MPU 60 of the charger 40 to charge the battery 10. Note that this charge control process is realized by the CPU in the second MPU 60 executing a program stored in advance in a ROM or the like.

[0058] As shown in FIG. 3, in the charge control process, first, in S100, an initial setting process is executed in which the requested current Bat_Req_I and the target value PWM_SET of the charge current are set to initial values ​​of 0, and the current abnormality flag is set to the OFF state.

[0059] Next, in S110, a charging current abnormality detection process is executed to determine whether the charging currents detected by the first amplifier 56 and the second amplifier 58 are normal, and the process proceeds to S115. Note that this charging current abnormality detection process corresponds to an example of the abnormality determination unit of the present disclosure, and will be described in detail later.

[0060] In S115, it is determined whether an abnormality has been detected in the charging current abnormality detection process, depending on whether the current abnormality flag is on. If the current abnormality flag is off and no abnormality has been detected in the charging current abnormality detection process, the process proceeds to S120.

[0061] If the current abnormality flag is on and an abnormality is detected in the charging current abnormality detection process, the process proceeds to S180 and the current abnormality process is executed. In this case, since an abnormality has occurred in the charging current detection system, the current abnormality process notifies the user of the abnormality via a notifying unit (not shown). The notifying unit may be, for example, an LED for indicating an abnormality, and the current abnormality process notifies the user of the abnormality by lighting or blinking the LED.

[0062] Next, in S120, it is determined whether or not communication with the battery pack 2 is possible via the second communication unit 52, thereby determining whether or not the battery 10 to be charged is connected to the charger 40. If it is determined in S120 that the battery 10 is not connected, the process returns to S110, and if it is determined in S120 that the battery 10 is connected, the process proceeds to S130.

[0063] In S130, the requested current Bat_Req_I is acquired from the battery pack 2 by communicating with the battery pack 2 via the second communication unit 52, and in the following S140, it is determined whether charging of the battery 10 is completed. Note that in S140, it is determined that charging is completed when, for example, the requested current Bat_Req_I from the battery pack 2 is 0 or equal to or less than the charge completion threshold.

[0064] If it is determined in S140 that charging of the battery 10 is not complete, the process proceeds to S150, where the target value PWM_SET of the charging current is set according to the requested current Bat_Req_I obtained from the battery pack 2.

[0065] This set target value PWM_SET is D / A converted into a signal representing the target current CC_PWM and output to the comparator 62. As a result, the control circuit including the comparator 62, photocoupler 64, and SW IC 66 controls the charging current to the battery 10 to be the target current CC_PWM.

[0066] Next, in S160, similar to S110, the charging current abnormality detection process is executed, and the process proceeds to S170. In S170, similar to S115, it is determined whether an abnormality has been detected in the charging current abnormality detection process depending on whether the current abnormality flag is on.

[0067] If the current abnormality flag is off and no abnormality is detected in the charging current abnormality detection process, the process proceeds to S130. If the current abnormality flag is on and an abnormality is detected in the charging current abnormality detection process, the process proceeds to S180, where current abnormality processing is executed.

[0068] In this case, since an abnormality has occurred in the charging current detection system, the current abnormality processing stops the output of charging current from the second power supply circuit 50 to the battery 10, and notifies the user that an abnormality has occurred via an alarm unit (not shown).

[0069] In addition, in the current abnormality processing, when the output of the charging current from the second power supply circuit 50 is stopped, for example, the target value PWM_SET of the charging current is set to an initial value of 0, but the charging path 48 may also be cut off by turning off a switch provided in the charging path 48.

[0070] Next, if it is determined in S140 that charging of the battery 10 is complete, the process proceeds to S190, where it is determined whether or not the battery 10 is connected, using the same procedure as in S120. If it is determined in S190 that the battery 10 is not connected (disconnected), the process returns to S100, and if it is determined in S190 that the battery 10 is connected, the process proceeds to S200.

[0071] In S200, the target value PWM_SET of the charging current is set to an initial value of 0, and the output of the charging current from the second power supply circuit 50 is stopped. Then, in the following S210, similar to S160, the charging current abnormality detection process is executed, and the process proceeds to S220.

[0072] In S220, similarly to S115 and S170, it is determined whether an abnormality has been detected in the charging current abnormality detection process by checking whether the current abnormality flag is on. If the current abnormality flag is off and no abnormality has been detected in the charging current abnormality detection process, S The flow proceeds to S190. If the current abnormality flag is on and an abnormality is determined in the charging current abnormality detection process, the flow proceeds to S180 and current abnormality process is executed.

[0073] Next, the charging current abnormality detection process executed in S110, S160, or S210 will be described. 4, in the charging current abnormality detection process, in S310, the process waits for a preset fixed time (e.g., 125 ms) to elapse since the previous start of the process. Then, after the fixed time has elapsed, the process proceeds to S320, where the first current detection value AD_Chrg_I_1 is acquired from the first amplifier 56. Then, in the following S330, the second current detection value AD_Chrg_I_2 is acquired from the second amplifier 58.

[0074] In S340, the absolute value of the difference between the first current detection value AD_Chrg_I_1 acquired in S320 and the target value PWM_SET of the charging current is calculated as a first deviation Diff_I_1 representing the difference between these values. Also, in S340, the absolute value of the difference between the second current detection value AD_Chrg_I_2 acquired in S330 and the target value PWM_SET of the charging current is calculated as a second deviation Diff_I_2 representing the difference between these values.

[0075] Next, in S350, it is determined whether the first deviation amount Diff_I_1 calculated in S340 is smaller than a preset first threshold value Dth1 (for example, 100) for determining an abnormality. If it is determined in S350 that the first deviation amount Diff_I_1 is smaller than the first threshold value Dth1, the first current detection value AD_Chrg_I_1 is determined to be normal, and the process proceeds to S360, where the first error counter Cerr_I_1 is decremented (−1).

[0076] On one hand, at S350, when it is determined that the first deviation amount Diff_I_1 is greater than or equal to the first threshold value Dth1, it is considered that the first current detection value AD_Chrg_I_1 is abnormal, and the process proceeds to S370, where the first error counter Cerr_I_1 is incremented (+1).

[0077] After the execution of the process in S360 or S370, the process proceeds to S380, where it is determined whether the second deviation amount Diff_I_2 calculated at S340 is smaller than a preset second threshold value Dth2 for abnormality determination, for example, 250.

[0078] At S380, when it is determined that the second deviation amount Diff_I_2 is smaller than the second threshold value Dth2, it is considered that the second current detection value AD_Chrg_I_2 is normal, and the process proceeds to S390, where the second error counter Cerr_I_2 is decremented (-1).

[0079] On the other hand, at S380, when it is determined that the second deviation amount Diff_I_2 is greater than or equal to the second threshold value Dth2, it is considered that the second current detection value AD_Chrg_I_2 is abnormal, and the process proceeds to S400, where the second error counter Cerr_I_2 is incremented (+1).

[0080] Note that the minimum values of the first error counter Cerr_I_1 and the second error counter Cerr_I_2 are 0, and the first error counter Cerr_I_1 and the second error counter Cerr_I_2 do not become negative values when decremented.

[0081] Also, the first threshold value Dth1 is set to a value smaller than the second threshold value Dth2 (Dth1 < Dth2) because the detection accuracy of the first current detection value AD_Chrg_I_1 is higher than that of the second current detection value AD_Chrg_I_2.

[0082] In other words, even if the first threshold Dth1 is set to a value smaller than the second threshold Dth2 and the allowable range of the first current detection value AD_Chrg_I_1 is made narrower than that of the second current detection value AD_Chrg_I_2, the first current detection value AD_Chrg_I_1 has high accuracy, so abnormalities can be accurately determined.

[0083] Next, after the process of S390 or S400 is executed, the process proceeds to S410, where it is determined whether the first error counter Cerr_I_1 is smaller than a preset first count value Cth1. If it is determined in S410 that the first error counter Cerr_I_1 is smaller than the first count value Cth1, the process proceeds to S420.

[0084] In S420, it is determined whether the second error counter Cerr_I_2 is smaller than a preset second count value Cth2. If it is determined in S420 that the second error counter Cerr_I_2 is smaller than the second count value Cth2, it is determined that the charging current detection system including the first amplifier 56 and the second amplifier 58 is normal, and the charging current abnormality detection process is terminated.

[0085] The first count value Cth1 and the second count value Cth2 are set to, for example, 32. This is because, when the charging current abnormality detection process is performed at the above-mentioned 125 ms cycle, if the first deviation amount Diff_I_1 is equal to or greater than the first threshold value Dth1 or the second deviation amount Diff_I_2 is equal to or greater than the second threshold value Dth2 for 4 seconds or more, an abnormality in the detection system for the charging current is determined.

[0086] However, the first threshold Dth1, second threshold Dth2, first count value Cth1, and second count value Cth2 used for abnormality determination may be set appropriately according to the characteristics of the charger or battery pack that performs the abnormality determination.

[0087] On the other hand, if it is determined in S410 that the first error counter Cerr_I_1 is equal to or greater than the first count value Cth1, or if it is determined in S420 that the second error counter Cerr_I_2 is equal to or greater than the second count value Cth2, the process proceeds to S430.

[0088] Then, in S430, it is determined that an abnormality has occurred in the charging current detection system including the first amplifier 56 and the second amplifier 58, the current abnormality flag is set to ON, and the charging current abnormality detection process ends.

[0089] In this embodiment, abnormalities in the charging current detection system include abnormalities caused by failures in the first shunt resistor 54, the first amplifier 56, the second amplifier 58, or the A / D converter in the second MPU 60.

[0090] As described above, in the charger 40 of this embodiment, the first shunt resistor 54 serving as a current detection unit is provided on the charging path 48 to the battery pack 2. The voltage across the first shunt resistor 54 is amplified by the first amplifier 56 and the second amplifier 58, respectively, and input to the second MPU 60 as the first detection signal Chrg_I_1 and the second detection signal Chrg_I_2 of the charging current.

[0091] The second MPU 60 executes a charging current abnormality determination process as an abnormality determination unit to determine whether the first detection signal Chrg_I_1 and the second detection signal Chrg_I_2 are normal. If it determines that the first detection signal Chrg_I_1 and / or the second detection signal Chrg_I_2 are abnormal, it turns on a current abnormality flag and stops the output of the charging current from the second power supply circuit 50.

[0092] Therefore, according to the charger 40 of this embodiment, abnormalities in the charging current detection system including the first amplifier 56 and the second amplifier 58 can be accurately detected, and the charging current can be prevented from being erroneously controlled to a current value different from the target current.

[0093] Furthermore, the charging current to the battery 10 is controlled to be the target current based on the detection result by the first amplifier 56, which has higher detection accuracy than the second amplifier 58, so that the control accuracy of the charging current can be increased.

[0094] Since the second amplifier 58 has a lower accuracy in detecting the charging current than the first amplifier 56, a lower cost amplifier than the first amplifier 56 can be used for the second amplifier 58, thereby reducing the overall cost of the charger 40.

[0095] Although the embodiments for carrying out the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments and can be carried out in various modified forms. [Variation 1] In the above embodiment, in the charger 40, the charging path 48 is provided with a first shunt resistor 54 as a current detection unit, and the first amplifier 56 and the second amplifier 58 are each described as amplifying the voltage across the first shunt resistor 54.

[0096] Alternatively, as shown in FIG. 5, a first shunt resistor 54 and a second shunt resistor 55 may be directly provided on the charging path 48 of the charger 40, with a first amplifier 56 connected to the first shunt resistor 54 and a second amplifier 58 connected to the second shunt resistor 55.

[0097] In this way, the first amplifier 56 can generate a first detection signal Chrg_I_1 by amplifying the voltage across the first shunt resistor 54, and the second amplifier 58 can generate a second detection signal Chrg_I_2 by amplifying the voltage across the second shunt resistor 55.

[0098] Therefore, first amplifier 56 and second amplifier 58 can detect the charging current using dedicated shunt resistors 54 and 55, respectively. Therefore, according to the present modification 1, it is possible to detect an abnormality in the charging current detection system including shunt resistor 54 in first amplifier 56, or an abnormality in the charging current detection system including shunt resistor 55 in second amplifier 58.

[0099] In addition, the first shunt resistor 54 and the second shunt resistor 55 for detecting the charging current may be provided in the positive charging path between the terminal 41 and the second power supply circuit 50, rather than in the negative charging path 48 between the terminal 42 and the second power supply circuit 50.

[0100] [Variation 2] In the above embodiment, it has been described that an abnormality in the charging current detection system is determined by calculating the absolute value of the difference between the first current detection value AD_Chrg_I_1 and the second current detection value AD_Chrg_I_2 and the target value PWM_SET of the charging current as the first deviation amount Diff_I_1 and the second deviation amount Diff_I_2.

[0101] However, an abnormality in the charging current detection system may be determined based on the difference (that is, the amount of deviation) between the first current detection value AD_Chrg_I_1 and the second current detection value AD_Chrg_I_2. The charging current abnormality detection process when the abnormality determination is performed in this manner will be described below.

[0102] 6, the charging current abnormality detection process of Modification 2 first executes the processes of S510 to S530. Note that the processes of S510 to S530 are executed in the same procedure as S310 to S330 shown in FIG. 4, and therefore a description thereof will be omitted.

[0103] Next, in S540, the absolute value of the difference between the first current detection value AD_Chrg_I_1 and the second current detection value AD_Chrg_I_2 acquired in S520 and S530 is calculated as a third deviation amount Diff_I_3 representing the difference between the first detection signal Chrg_I_1 and the second detection signal Chrg_I_2.

[0104] Then, in the next step S550, it is determined whether the third deviation amount Diff_I_3 calculated in step S540 is smaller than a preset third threshold value Dth3 for determining an abnormality, for example, 350. If it is determined in S550 that the third deviation amount Diff_I_3 is smaller than the third threshold value Dth3, It is determined that the first current detection value AD_Chrg_I_1 and the second current detection value AD_Chrg_I_2 are normal, and the process proceeds to S560, where the current error counter Cerr_I_3 is decremented (−1).

[0105] Furthermore, if it is determined in S550 that the third deviation amount Diff_I_3 is greater than or equal to the third threshold value Dth3, the first current detection value AD_Chrg_I_1 and / or the second current detection value AD_Chrg_I_2 is determined to be abnormal, and the process proceeds to S570, where the current error counter Cerr_I_3 is incremented (+1).

[0106] The minimum value of the current error counter Cerr_I_3 is 0, similar to the first error counter Cerr_I_1 and the second error counter Cerr_I_2 in the above embodiment, and the current error counter Cerr_I_3 will never become a negative value by being decremented.

[0107] Furthermore, the third threshold Dth3 is greater than the first threshold Dth1 and the second threshold Dth2 in the above embodiment, and is the sum of these values ​​in Modification 2. This is because the third threshold Dth3 is used to determine whether the difference between the first current detection value AD_Chrg_I_1 and the second current detection value AD_Chrg_I_2 is within an allowable range.

[0108] In other words, in this variant example 2, by adding the allowable error range of the first detection signal Chrg_I_1 and the allowable error range of the second detection signal Chrg_I_2, it is possible to determine whether the first detection signal Chrg_I_1 and / or the second detection signal Chrg_I_2 are abnormal.

[0109] Next, after the process of S560 or S570 is executed, the process proceeds to S580, where it is determined whether the current error counter Cerr_I_3 is smaller than a preset third count value Cth3. Then, in S580, if it is determined that the current error counter Cerr_I_3 is smaller than the third count value Cth3, it is determined that the charging current detection system including the first amplifier 56 and the second amplifier 58 is normal, and the charging current abnormality detection process is terminated.

[0110] If it is determined in S580 that the current error counter Cerr_I_3 is equal to or greater than the third count value Cth3, it is determined that an abnormality has occurred in the charging current detection system including the first amplifier 56 and the second amplifier 58, and the process proceeds to S590. Then, in S590, the current abnormality flag is set to the ON state, and the charging current abnormality detection process ends.

[0111] The third count value Cth3 is set to, for example, 32, similarly to the first count value Cth1 and the second count value Cth2 in the above embodiment. As described above, in this variant example 2, an abnormality in the charging current detection system is determined based on the deviation Diff_I_3 between the first current detection value AD_Chrg_I_1 and the second current detection value AD_Chrg_I_2. Even in this way, an abnormality in the charging current detection system can be accurately determined.

[0112] [Other embodiments] In the above embodiment, the charger 40 is described as being provided with one second mounting section 44 for mounting the battery pack 2, but the charger 40 may be provided with two or more second mounting sections 44.

[0113] In this case, a plurality of second power supply circuits 50 for generating charging current and a plurality of charging paths 48 may be provided so that the batteries 10 in the battery packs 2 attached to two or more second attachment portions 44 can be individually charged. Therefore, in this case, it is preferable to provide a current detection unit for detecting charging current and first and second amplifiers for each charging path 48.

[0114] In the above embodiments, multiple functions of one component may be realized by multiple components, or one function of one component may be realized by multiple components. Also, multiple functions of multiple components may be realized by one component. Alternatively, one function that is realized by multiple components may be realized by a single component. Also, part of the configuration of the above embodiments may be omitted. Also, at least part of the configuration of the above embodiments may be added to or substituted for the configuration of another of the above embodiments. Note that all aspects included in the technical idea identified only by the wording of the claims are embodiments of the present disclosure.

[0115] The charger of the present disclosure can also be configured as a device for detecting charging current. The charger of the present disclosure can also be realized in various forms, such as a charging system, a program for causing a computer to function as a charger, a non-transitory tangible recording medium such as a semiconductor memory on which the program is recorded, or a method for determining charging abnormalities. [Explanation of symbols]

[0116] 2...battery pack, 10...battery, 40...charger, 48...charging path, 50...second power supply circuit, 54...first shunt resistor, 55...second shunt resistor, 56...first amplifier, 58...second amplifier, 60...second MPU.

Claims

1. a charging path configured to supply a charging current to the battery from a power supply circuit that generates the charging current to the battery; a current detection unit configured to detect the charging current flowing through the charging path; a control circuit configured to feedback-control the charging current so that the charging current reaches a target value; a first amplifier configured to amplify an output from the current detection unit and output the amplified output as a first detection signal of the charging current; a second amplifier configured to amplify an output from the current detection unit and output the amplified output as a second detection signal of the charging current; an abnormality determination unit configured to calculate a first difference between the first detection signal and the target value and a second difference between the second detection signal and the target value, and determine that an abnormality has occurred in the detection system of the charging current including the first amplifier and the second amplifier when the first difference and / or the second difference is outside a predetermined allowable range; Charger with.

2. 2. The charger according to claim 1, the current detection unit includes a shunt resistor provided on the charging path, The charger, wherein the first amplifier and the second amplifier are configured to amplify the voltage across the shunt resistor and output the amplified voltage as the first detection signal and the second detection signal, respectively.

3. 2. The charger according to claim 1, the current detection unit includes a first shunt resistor and a second shunt resistor that are provided in series on the charging path, the first amplifier is configured to amplify a voltage across the first shunt resistor and output the first detection signal; The second amplifier is configured to amplify the voltage across the second shunt resistor and output the second detection signal.

4. The charger according to any one of claims 1 to 3, The charger, wherein the first amplifier and the second amplifier are each in the form of an independent electronic component.

5. The charger according to any one of claims 1 to 4, The charger is configured such that, when it is determined that the abnormality has occurred during charging of the battery, the abnormality determination unit outputs a command to stop charging of the battery.

6. The charger according to any one of claims 1 to 5, The charger, wherein the first amplifier and the second amplifier are configured to output, as the first detection signal and the second detection signal, detection signals having different accuracies from each other.

7. A charger according to claim 6, the first amplifier is configured to generate, as the first detection signal, a detection signal having higher accuracy than the second detection signal, and to output the generated first detection signal to the control circuit.

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