Charging device

Abstract

The present specification provides a charging device capable of adjusting an output in accordance with the performance of a power source. A charging device disclosed in the present specification is connected between a power source and a battery. The charging device (1) increases the output current to less than or equal to the upper limit value of the current increase rate that the power supply can output. Furthermore, the charging device (2) suppresses the output current to be less than or equal to the upper limit value of the current that can be output by the power supply. The charging device disclosed in the present specification can adjust the output in accordance with the performance (current increase rate upper limit value and current upper limit value) of the power supply.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a charging device connected between a power source and a battery. Background Technology

[0002] Electric vehicles (e.g., Patent Document 1) are known to use circuits that combine the switching elements of an inverter and the stator coils of a motor as voltage converters to boost or buck the voltage of a power source and output it to a battery. In this electric vehicle, the inverter (switching elements) and the motor (stator coils) function as charging devices. Hereinafter, for the sake of simplicity, "motor" will sometimes be referred to simply as "motor".

[0003] Furthermore, Patent Document 2 discloses an electric vehicle having a first battery and a second battery. In the case of a drive motor, the first battery and the second battery are connected in series. In the case of charging the batteries using an external power source for the electric vehicle, the first battery and the second battery are connected in parallel.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2005-184947

[0007] Patent Document 2: Japanese Patent Application Publication No. 2019-118221 Summary of the Invention

[0008] The charging device sets a target value for the voltage or current suitable for charging the battery, causing the charging device's output to track the target value. However, if the target value is set beyond the power supply's performance, there is a possibility that the charging device's output will fail to track the target value. This manual provides a charging device capable of adjusting its output to match the power supply's performance.

[0009] The charging device disclosed in this specification is connected between a power source and a battery. The charging device increases the output current to below the upper limit of the rate of increase of the current that the power source can output. Furthermore, the charging device suppresses the output current to below the upper limit of the current that the power source can output. The charging device disclosed in this specification can adjust the output in accordance with the performance of the power source.

[0010] The following "Detailed Description" describes the detailed contents of the technology disclosed in this specification and further improvements. Attached Figure Description

[0011] Figure 1 This is a circuit diagram of the charging device in an embodiment.

[0012] Figure 2 This is a flowchart of the charging control performed by the charging device. Detailed Implementation

[0013] Referring to the accompanying drawings, the charging device 2 of an embodiment will be described. Figure 1 This is the circuit diagram of charging device 2. The positive terminal of power supply 70 is connected to input terminal 2a of charging device 2, and the positive terminal of battery 3 is connected to output terminal 2b. Charging device 2 has a ground 9, and the negative terminals of power supply 70 and battery 3 are connected to ground 9. Charging device 2 can adjust the output current of power supply 70 and output it from output terminal 2b to charge battery 3.

[0014] The charging device 2 is a buck-boost converter capable of making the voltage at the output terminal 2b (output voltage) higher than the voltage at the input terminal 2a (input voltage) and also capable of making the voltage at the output terminal 2b (output voltage) lower than the voltage at the input terminal 2a (input voltage). The charging device 2 includes a first switching element 12, a second switching element 22, diodes 13, 14, 23, and 24, a reactor 31, capacitors 15 and 25, voltage sensors 5 and 6, a current sensor 4, and a controller 7. Hereinafter, for ease of explanation, the "switching element" will be referred to as "SW element".

[0015] A first SW element 12 is connected between input terminal 2a and one end 31a of reactor 31, and a diode 13 is connected in anti-parallel to the first SW element 12. A diode 14 is connected between one end 31a of reactor 31 and ground 9. When the first SW element 12 is turned on, it allows current to flow from input terminal 2a to reactor 31; when turned off, it prevents current from flowing. Diodes 13 and 14 ensure that current always flows from ground 9 to input terminal 2a, preventing current from flowing in the reverse direction. A capacitor 15 is connected between input terminal 2a and ground 9.

[0016] A second SW element 22 is connected between ground 9 and the other end 31b of reactor 31, and a diode 23 is connected in antiparallel to the second SW element 22. A diode 24 is connected between the other end 31b of reactor 31 and output terminal 2b. When the second SW element 22 is turned on, it allows current to flow from reactor 31 to ground 9; when turned off, it prevents current from flowing. Diodes 23 and 24 ensure that current always flows from ground 9 to output terminal 2b, preventing current from flowing in the reverse direction. A capacitor 25 is connected between output terminal 2b and ground 9.

[0017] The charging device 2 includes voltage sensors 5 and 6 and a current sensor 4. The measurements from these sensors are sent to the controller 7. Voltage sensor 5 measures the voltage applied to input terminal 2a (input voltage), voltage sensor 6 measures the voltage output from output terminal 2b (output voltage), and current sensor 4 measures the current output from output terminal 2b (output current). In other words, the controller 7 can determine the input voltage, output voltage, and output current.

[0018] Figure 1 The circuit is well-known. If the second SW element 22 is fixed to cut off, and the first SW element 12 is turned on or off using a PWM signal with an appropriate duty cycle, the output voltage decreases relative to the input voltage. Conversely, if the first SW element 12 is fixed to turn on, and the second SW element is turned on or off using a PWM signal with another appropriate duty cycle, the output voltage increases relative to the input voltage. In other words, the charging device 2 is a buck-boost converter capable of increasing or decreasing the output voltage relative to the input voltage.

[0019] If the output voltage is made slightly higher than the voltage of battery 3, current flows from power supply 70 to battery 3. If the output voltage is increased further, more current is supplied to battery 3. If the output voltage is decreased, less current is supplied to battery 3. Controller 7 adjusts the output voltage in such a way that the current supplied to battery 3 (i.e., the output current of charging device 2) tracks the target current value. As described above, controller 7 can adjust the output voltage by adjusting the duty cycle of the PWM signal provided to the first SW element 12 or the second SW element 22.

[0020] The controller 7 and the power supply 70 can communicate and exchange information via communication line 40. Communication line 40 can also be wireless or connected to the Internet. The controller 7 obtains the upper limit of the current increase rate and the upper limit of the current from the power supply 70 via communication line 40. The upper limit of the current increase rate means the upper limit of the rate at which the power supply 70 can output current. The upper limit of the current means the upper limit of the current that the power supply 70 can output.

[0021] Figure 2 A flowchart illustrating the charging process executed by controller 7 is shown. Controller 7 first obtains information on the upper limit of the current increase rate and the upper limit of the current from power supply 70, as described above (step S2). Next, controller 7 determines the target value of the output current (step S3). Controller 7 sets the current target value by referring to the previous target value, causing the output current to gradually increase from zero over time. The target value of the output current at the start of charging is zero. In step S3, controller 7 does not consider the upper limit of the current increase rate of power supply 70 and sets the current target value by increasing it at the highest possible rate. Here, "current" and "previous" refer to the "current" and "previous" control cycles of controller 7.

[0022] Next, controller 7 compares the current target value with the current upper limit value (step S4). If the current target value equals the current upper limit value, controller 7 adjusts the output voltage so that the output current tracks the target value (step S4: "Yes", S7). As described above, if the output voltage is increased, the output current increases; if the output voltage is decreased, the output current decreases.

[0023] If the target value is not equal to the current upper limit (in other words, the target value has not reached the current upper limit), the controller 7 compares the difference between the current target value and the previous target value (current increment) with the current increase rate upper limit (step S5). If the current increment does not exceed the current increase rate upper limit, the controller 7 adjusts the output voltage so that the output current tracks the target value (step S5: "No", S7).

[0024] If the current increment exceeds the upper limit of the current increase rate, the controller 7 changes the target value to "the previous target value + the upper limit of the current increase rate" and controls the output voltage in a way that makes the output current track the target value (steps S5: "Yes", S6, S7).

[0025] Furthermore, in step S5, more precisely, the controller 7 compares the value obtained by dividing the current increment by the controller 7's control cycle with the upper limit of the current increase rate. And, if the value obtained by dividing the current increment by the control cycle exceeds the upper limit of the current increase rate, the controller 7 changes the current target value to "the previous target value + the upper limit of the current increase rate × the control cycle". This is to match the upper limit of the current increase rate with the time interval of the current increase.

[0026] The controller 7 repeats steps S3 to S7 until the battery 3 reaches full charge (step S8: "No"). If the battery 3 reaches full charge, the controller 7 ends the process (step S8: "Yes", end). Furthermore, upon ending the process, the controller 7 sends an output stop command to the power supply 70.

[0027] Through the above processing, the controller 7 (charging device 2) achieves the following effects: (1) The charging device 2 can increase the output current to below the upper limit of the current increase rate that the power supply 70 can output. (2) The charging device 2 can suppress the output current to below the upper limit of the current that the power supply 70 can output. That is, the charging device 2 can adjust the output current in accordance with the performance of the power supply 70.

[0028] Notes relating to the techniques described in the embodiments. Figure 1 The circuit described is an example of charging device 2. Charging device 2 can also be a current regulator capable of adjusting the output current to any value. Alternatively, the charging device can be implemented using a dual-inverter structure, where one end of the motor's stator coil is connected to the AC terminal of the first inverter and the other end to the AC terminal of the second inverter. It is known that a circuit combining the inverter's SW element and the stator coil can be used as a voltage converter. A structure where inverters are connected to each end of the stator coil is equivalent to... Figure 1 The buck-boost converters are connected in parallel to three devices.

[0029] The action of "fixing the SW component to conduct" is equivalent to the action of "closing the SW component," which means that the devices connected to each end of the SW component will be electrically connected. The action of "fixing the SW component to cut off" is equivalent to the action of "opening the SW component," which means that the devices connected to each end of the SW component will be electrically disconnected.

[0030] The specific examples of the present invention have been described in detail above, but these are merely illustrative and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples described above. The technical elements described in this specification or drawings exert their technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of application. Furthermore, the technology illustrated in this specification or drawings can achieve multiple objectives simultaneously, and achieving one of these objectives is itself technically useful.

[0031] (Symbol Explanation)

[0032] 2: Charging device; 3: Battery; 4: Current sensor; 5, 6: Voltage sensor; 7: Controller; 9: Ground; 12, 22: Switching element; 13, 14, 23, 24: Diode; 15, 25: Capacitor; 40: Communication line; 70: Power supply.

Claims

1. A charging device, connected between a power source and a battery, wherein, The charging device increases the output current to below the upper limit of the current increase rate that the power supply can output, and suppresses the output current to below the upper limit of the current that the power supply can output.

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