Charging circuit

Abstract

To provide a charge circuit capable of charging two batteries with one power source.SOLUTION: A first battery is connected between high and middle voltage terminals of a charge circuit, and a second battery is connected between middle and low voltage terminals. A first capacitor is connected between the high and middle voltage terminals, and a second capacitor is connected between the middle and low voltage terminals. A first switch connects a series circuit of a coil and a third capacitor to between the high and middle voltage terminals. A second switch connects the series circuit to between the middle and low voltage terminals. A third switch connects the series circuit to a power source. A controller performs switching of the following three modes including: a first mode for closing the first switch and opening the second and third switches; a second mode for closing the second switch and opening the first and third switches; and a third mode for closing the third switch and opening the first and second switches. The controller controls the switches so as to repeat the modes in the order of the third mode, the first mode, the third mode and the second mode.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a charging circuit that is connected between a power source and a battery and is used to charge the battery with power from the power source. [Background technology]

[0002] As electric vehicles become more popular, the number of charging stations is also increasing. While older charging stations can only supply low-voltage power, newer charging stations can supply high-voltage power. An example of "low voltage" is 300-600 volts, and an example of "high voltage" is 600-1200 volts. Note that the terms "low voltage" and "high voltage" relatively represent the difference in output voltage between the two power sources, and the technology disclosed in this specification is not limited to these voltages.

[0003] It is desirable for an electric vehicle to be able to be charged from either of two types of power sources (a low-voltage power source and a high-voltage power source). Patent Documents 1 and 2 disclose charging circuits compatible with two types of power sources. The charging circuits in Patent Documents 1 and 2 are mounted on an electric vehicle (or a hybrid vehicle). The electric vehicle (or a hybrid vehicle) is mounted with two batteries. The charging circuit can charge the two batteries from either a low-voltage power source or a high-voltage power source. When a low-voltage power source is used, the charging circuit connects the two batteries in parallel. When a high-voltage power source is used, the charging circuit connects the two batteries in series. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-047677 [Patent Document 2] U.S. Patent No. 11,336,101 Summary of the Invention [Problem to be solved by the invention]

[0005] This specification provides a charging circuit that can charge two batteries using one power source. In particular, this specification provides a charging circuit that can shorten the time required to charge two batteries. This specification also provides a circuit that can be used not only for charging but also for supplying power from the batteries to an electrical device. [Means for solving the problem]

[0006] The charging circuit disclosed in this specification is connected between a power source and two batteries. The charging circuit includes a high-voltage terminal, a medium-voltage terminal, a low-voltage terminal, first, second, third, and fourth capacitors, a coil, first, second, and third switches, and a controller. The high-voltage terminal is connected to the positive terminal of the first battery. The medium-voltage terminal is connected to the negative terminal of the first battery and the positive terminal of the second battery. The low-voltage terminal is connected to the negative terminal of the second battery. The first capacitor is connected between the high-voltage terminal and the medium-voltage terminal. The second capacitor is connected between the medium-voltage terminal and the low-voltage terminal. The coil and the third capacitor are connected in series. The series-connected circuit of the coil and the third capacitor will be referred to simply as the series circuit hereinafter. The fourth capacitor is connected in parallel with the power source. The first switch connects the series circuit between the high-voltage terminal and the medium-voltage terminal. The second switch connects the series circuit between the medium-voltage terminal and the low-voltage terminal. The third switch connects the series circuit to the power source and the fourth capacitor. The controller controls the first switch, second switch, and third switch. The controller can switch between the following three modes. First mode: Close the first switch and open the second and third switches. Second mode: Close the second switch and open the first and third switches. Third mode: Close the third switch and open the first and second switches. The controller controls the first, second, and third switches to cycle through the following modes in the order of third mode, first mode, third mode, and second mode.

[0007] The voltage of the first capacitor is equal to the voltage of the first battery, the voltage of the second capacitor is equal to the voltage of the second battery, and the voltage of the fourth capacitor is equal to the voltage of the power supply. In the third mode, the fourth capacitor and the third capacitor are connected, and current flows from the fourth capacitor to the third capacitor. When the controller switches from the third mode to the first mode, the third capacitor and the first capacitor are connected, and current flows from the third capacitor to the first capacitor. As a result, the total voltage of the first and second capacitors increases, and current flows from the first and second capacitors to the first and second batteries. In other words, the first and second batteries are charged. The first capacitor suppresses pulsations in the current flowing into the first battery and stabilizes the voltage across the first battery.

[0008] When the controller switches from the first mode to the third mode, electrical energy is stored again in the series circuit.

[0009] When the controller switches from mode 3 to mode 2, the third capacitor and the second capacitor are connected, and current flows from the third capacitor to the second capacitor. As a result, the total voltage of the first and second capacitors rises, and current flows from the first and second capacitors to the first and second batteries. In other words, the first and second batteries are charged. The second capacitor suppresses pulsations in the current flowing into the second battery and stabilizes the voltage across the second battery.

[0010] Each time the controller switches modes, current flows from the power supply to the fourth capacitor, and then from the fourth capacitor to the first capacitor (or second capacitor). The total voltage of the first and second capacitors rises, charging the first and second batteries. Using this charging circuit allows current to flow to the first and second batteries, shortening the time required for charging.

[0011] To charge a single battery using the charging circuit, simply connect the positive and negative terminals of the battery to the high-voltage and low-voltage terminals, respectively. By using the controller to control the three switches as described above, you can charge a single battery.

[0012] The controller should control the first, second, and third switches so that the three modes mentioned above are switched at intervals that are half the resonant period of the resonant circuit consisting of the coil and third capacitor. When the switches are controlled at the above timing, the current that flows through the switch when it is switched becomes small (theoretically, it becomes zero). Therefore, controlling the switches at the above timing can reduce switching losses.

[0013] An example of the first and second switches is as follows: The first switch is connected between the medium voltage terminal and the low voltage side of the series circuit. The second switch is connected between the high voltage side of the series circuit and the medium voltage terminal. In this case, it is preferable to provide the following first and second diodes: The first diode has its anode connected to the high voltage side of the series circuit and its cathode connected to the high voltage terminal. The second diode has its anode connected to the low voltage terminal and its cathode connected to the low voltage side of the series circuit. Such an arrangement of switches and diodes provides a simple circuit. A specific circuit configuration will be described in the examples.

[0014] With the following switch configuration, a charging circuit can be used to both charge a battery and power an electrical device from the battery. The first switch includes switch 1A and switch 1B. The second switch includes switch 2A and switch 2B. Switch 1A is connected between the medium voltage terminal and the low voltage side of the series circuit. Switch 1B is connected between the high voltage side of the series circuit and the high voltage terminal. Switch 2A is connected between the high voltage side of the series circuit and the medium voltage terminal. Switch 2B is connected between the low voltage terminal and the low voltage side of the series circuit. This charging circuit can charge a battery, just like the previous charging circuit. An electrical device is connected instead of a power source. By switching between modes 1, 2, and 3 as described above, the charging circuit can supply power from the battery to an electrical device.

[0015] Details and further improvements of the technology disclosed in this specification are described in the following "Description of Embodiments of the Invention." [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 4 is a circuit diagram of the charging circuit of the first embodiment (third mode). [Figure 2] FIG. 10 is a circuit diagram of a charging circuit (first mode). [Figure 3] FIG. 10 is a circuit diagram of a charging circuit (second mode). [Figure 4] This is a graph of the voltage and current in the coil when the switch is turned on, and a graph of the electrical energy stored in the series circuit. [Figure 5] 1 is a time chart of switch states and current flow. [Figure 6] Fig. 6(A) is a diagram showing the path of the current Icap31, and Fig. 6(B) is a diagram showing the path of the current Icap32. [Figure 7] This is a circuit diagram of the charging circuit (charging one battery / first mode). [Figure 8] This is a circuit diagram of the charging circuit (charging one battery / second mode). [Figure 9]FIG. 10 is a circuit diagram of a charging circuit according to a second embodiment (first mode). [Figure 10] FIG. 10 is a circuit diagram of a charging circuit according to a second embodiment (third mode). [Figure 11] FIG. 10 is a circuit diagram of a charging circuit according to a second embodiment (second mode). [Figure 12] FIG. 10 is a diagram illustrating an example of charging. [Figure 13] FIG. 10 is a diagram illustrating an example of power supply. DETAILED DESCRIPTION OF THE INVENTION

[0017] (First embodiment) A charging circuit 10 of the first embodiment will be described with reference to the drawings. FIG. 1 shows a circuit diagram of the charging circuit 10. The charging circuit 10 is connected between a DC power supply 90 and two batteries (a first battery 91 and a second battery 92). The charging circuit 10 can charge the two batteries 91 and 92 with power from the DC power supply 90. The two batteries 91 and 92 are mounted on, for example, an electric vehicle. The DC power supply 90 is provided in, for example, a charging station. The charging circuit 10 may be provided in the charging station or in the electric vehicle.

[0018] The circuitry of the charging circuit 10 will now be described. The charging circuit 10 has two input terminals 17d and 17e and three output terminals. The positive electrode of a DC power supply 90 is connected to the positive input terminal 17d, and the negative electrode of the DC power supply 90 is connected to the negative input terminal 17e.

[0019] The three output terminals are referred to as high-voltage terminal 17a, medium-voltage terminal 17b, and low-voltage terminal 17c. A first battery 91 is connected between high-voltage terminal 17a and medium-voltage terminal 17b. The positive electrode of first battery 91 is connected to high-voltage terminal 17a, and the negative electrode of first battery 91 is connected to medium-voltage terminal 17b. A second battery 92 is connected between medium-voltage terminal 17b and low-voltage terminal 17c. The positive electrode of second battery 92 is connected to medium-voltage terminal 17b, and the negative electrode of second battery 92 is connected to low-voltage terminal 17c.

[0020] The charging circuit 10 includes four capacitors (first capacitor 11, second capacitor 12, third capacitor 13, and fourth capacitor 14). The first capacitor 11 is connected between the high voltage terminal 17a and the medium voltage terminal 17b. The second capacitor 12 is connected between the medium voltage terminal 17b and the low voltage terminal 17c. The first capacitor 11 and the second capacitor 12 are connected in series.

[0021] Third capacitor 13 is connected in series with coil 15. For convenience, the series connection circuit of third capacitor 13 and coil 15 is referred to as series circuit 16. Series circuit 16 is connected between high-voltage terminal 17a and low-voltage terminal 17c via a switch. Series circuit 16 is also connected between input terminals 17d and 17e via another switch.

[0022] The fourth capacitor 14 is connected between the positive input terminal 17d and the negative input terminal 17e. That is, the fourth capacitor 14 is connected in parallel to the power supply 90. In other words, the fourth capacitor 14 is connected in parallel to the series circuit 16. However, a third switch 23 is connected between the fourth capacitor 14 and the series circuit 16. Next, the switch will be described.

[0023] Charging circuit 10 includes three switches (first switch 21, second switch 22, and third switch 23). First switch 21 is connected between medium voltage terminal 17b and low voltage side 16b of series circuit 16. Second switch 22 is connected between high voltage side 16a of series circuit 16 and medium voltage terminal 17b. Third switch 23 is connected between positive input terminal 17d and high voltage side 16a. A diode 34 that prevents backflow is connected to switch 21. A diode 35 that prevents backflow is connected to switch 22, and a diode 36 that prevents backflow is connected to switch 23.

[0024] Charging circuit 10 also includes three diodes (first diode 31, second diode 32, and third diode 33). First diode 31 is connected between high-voltage side 16a and high-voltage terminal 17a. The anode of first diode 31 is connected to high-voltage side 16a, and the cathode is connected to high-voltage terminal 17a.

[0025] The second diode 32 is connected between the low-voltage terminal 17c and the low-voltage side 16b. The anode of the second diode 32 is connected to the low-voltage terminal 17c, and the cathode is connected to the low-voltage side 16b. The third diode 33 is connected between the low-voltage side 16b and the negative input terminal 17e. The anode of the third diode 33 is connected to the low-voltage side 16b, and the cathode is connected to the negative input terminal 17e. The diodes 31, 32, and 33 are provided to prevent reverse current flow.

[0026] The switches 21, 22, and 23 are controlled by a controller 24. In other words, the controller 24 opens and closes each of the switches 21, 22, and 23. Here, "closing a switch" means connecting both ends of the switch, and "opening a switch" means disconnecting one end from the other end of the switch. Because the switches 21, 22, and 23 are semiconductor switches, "closing a switch" can be expressed as "turning on a switch," and "opening a switch" can be expressed as "turning off a switch."

[0027] When the first switch 21 is closed, the series circuit 16 is connected to the first capacitor 11. When the first switch 21 is opened, the series circuit 16 is disconnected from the first capacitor 11.

[0028] When the second switch 22 is closed, the series circuit 16 is connected to the second capacitor 12. When the second switch 22 is opened, the series circuit 16 is disconnected from the second capacitor 12. Since the second battery 92 is connected across the second capacitor 12, when the second switch 22 is closed, the series circuit 16 is connected to the second battery 92, and when the second switch 22 is opened, the series circuit 16 is disconnected from the second battery 92.

[0029] When the third switch 23 is closed, the series circuit 16 is connected to the power supply 90 (and the fourth capacitor 14). When the third switch 23 is opened, the series circuit 16 is disconnected from the power supply 90 (and the fourth capacitor 14).

[0030] A controller 24 controls the switches 21, 22, and 23. The controller 24 closes the third switch 23 and opens the first switch 21 and the second switch 22. This state is called the third mode. The state of each switch in the third mode is shown in a table at the bottom of FIG. 1. The symbols SW1, SW2, and SW3 in the table represent the first switch 21, the second switch 22, and the third switch 23, respectively.

[0031] The controller 24 closes the first switch 21 and opens the second switch 22 and the third switch 23. This state is referred to as the first mode. The controller 24 closes the second switch 22 and opens the first switch 21 and the third switch 23. This state is referred to as the second mode. The controller 24 controls the switches 21, 22, and 23 to achieve one of the first, second, and third modes. The controller 24 controls the switches 21, 22, and 23 so that the third mode, the first mode, the third mode, and the second mode are repeated in this order. When the switches 21, 22, and 23 are switched in this manner, current flows through the first capacitor 11 and the second capacitor 12. The first capacitor 11 and the second capacitor 12 are connected in series, and the total voltage of the first capacitor 11 and the second capacitor 12 increases. As a result, current flows from the first capacitor 11 and the second capacitor 12 to the first battery 91 and the second battery 92, charging these batteries.

[0032] The current flow in each mode will be explained. The thick arrows in FIG. 1 (solid arrows and dashed arrows) indicate the current flow in the third mode. The thick solid arrows indicate the path of DC current, and the thick dashed arrows indicate the path through which a sinusoidal current flows. The sinusoidal current is generated by resonance of the series circuit 16 (an LC resonant circuit formed by the coil 15 and the third coil 13).

[0033] The controller 24 closes the third switch 23 and opens the first switch 21 and the second switch 22. In the third mode, the series circuit 16 is connected to the DC power supply 90 and the fourth capacitor 14 through the third switch 23 and the third diode 33. Because the first switch 21 and the second switch 22 are open, the series circuit 16 is disconnected from the first capacitor 11 and the second capacitor 12. The DC power supply 90 and the fourth capacitor 14 are connected in parallel, and a DC current flows from the DC power supply 90 to the fourth capacitor 14. The fourth capacitor 14 is charged.

[0034] As soon as the third switch 23 is closed, a current begins to flow from the fourth capacitor 14 to the series circuit 16. Because the series circuit 16 is an LC resonant circuit, the current flowing from the fourth capacitor 14 to the series circuit 16 gradually increases. As the third capacitor 13 of the series circuit 16 is charged, the current flowing from the fourth capacitor 14 to the series circuit 16 gradually decreases. In this way, a sinusoidal current flows from the fourth capacitor 14 to the series circuit 16.

[0035] FIG. 2 shows the current flow in the first mode. The thick arrows in FIG. 2 (solid arrows and dashed arrows) indicate the current flow in the first mode. In FIG. 2, the thick solid arrows indicate the path of the DC current, and the thick dashed arrows indicate the path of the sinusoidal current. This is also true in the subsequent circuit diagrams, where the thick solid arrows indicate the path of the DC current, and the thick dashed arrows indicate the path of the sinusoidal current. In all circuit diagrams, the sinusoidal current is generated by the resonance of series circuit 16 (an LC resonant circuit formed by coil 15 and third coil 13).

[0036] In the first mode, the controller 24 closes the first switch 21 and opens the second switch 22 and the third switch 23. In the first mode, the series circuit 16 is connected to the first capacitor 11 through the first switch 21 and the first diode 31. By opening the second switch 22 and the third switch 23, the series circuit 16 is disconnected from the DC power supply 90, the fourth capacitor 14, and the second capacitor 12.

[0037] The controller 24 controls the switches 21, 22, and 23 to switch from the third mode to the first mode. Immediately before switching to the first mode, electrical energy is stored in the third capacitor 13. In the first mode, the DC power supply 90 and the fourth capacitor 14 are disconnected from the series circuit 16. Meanwhile, when the first switch 21 is closed, current begins to flow from the series circuit 16 to the first capacitor 11. Because the series circuit 16 is an LC resonant circuit, the current flowing from the series circuit 16 to the first capacitor 11 gradually increases. When the third capacitor 13 of the series circuit 16 discharges, the current flowing from the series circuit 16 to the first capacitor 11 gradually decreases. In this way, a sinusoidal current flows from the series circuit 16 to the first capacitor 11.

[0038] When the voltage across the first capacitor 11 increases, the total voltage across the first capacitor 11 and the second capacitor 12 increases. As a result, current flows from the series-connected circuit of the first capacitor 11 and the second capacitor 12 to the series-connected circuit of the first battery 91 and the second battery 92. In other words, the first battery 91 and the second battery 92 are charged.

[0039] The controller 24 switches from the first mode to the third mode. The series circuit 16 is again connected to the DC power supply 90, and the series circuit 16 is disconnected from the first capacitor 11 and the second capacitor 12. Electrical energy is again stored in the third capacitor 13, which was discharged in the first mode.

[0040] Next, the controller 24 switches from the third mode to the second mode. FIG. 3 shows the current flow in the second mode. The thick arrows in FIG. 3 indicate the current flow in the second mode. The solid arrows indicate the path of the DC current, and the dashed arrows indicate the path of the sinusoidal current. In the second mode, the controller 24 closes the second switch 22 and opens the first switch 21 and the third switch 23. In the second mode, the series circuit 16 is connected to the second capacitor 12 through the second switch 22 and the second diode 32. By opening the first switch 21 and the third switch 23, the series circuit 16 is disconnected from the DC power source 90, the fourth capacitor 14, and the first capacitor 11.

[0041] Immediately before switching to the second mode, electrical energy is stored in the third capacitor 13. In the second mode, the DC power supply 90 and the fourth capacitor 14 are disconnected from the series circuit 16. Meanwhile, when the second switch 22 is closed, current begins to flow from the series circuit 16 to the second capacitor 12. For the same reason as in the first mode, a sinusoidal current flows from the series circuit 16 to the second capacitor 12. The voltage across the second capacitor 12 rises, and the total voltage of the first capacitor 11 and the second capacitor 12 also rises. As a result, current flows from the series-connected circuit of the first capacitor 11 and the second capacitor 12 to the series-connected circuit of the first battery 91 and the second battery 92. In other words, the first battery 91 and the second battery 92 are charged.

[0042] The controller 24 switches from the second mode to the third mode. The series circuit 16 is again connected to the DC power supply 90 and the fourth capacitor 14, and the series circuit 16 is disconnected from the first capacitor 11 and the second capacitor 12. Electrical energy is again stored in the third capacitor 13, which was discharged in the second mode.

[0043] The controller 24 repeatedly switches the mode between the third mode / first mode / third mode / second mode. Each time the controller 24 switches from the third mode to the first mode or the second mode, the first battery 91 and the second battery 92 are charged little by little. Each time the controller 24 repeats the cycle of "third mode / first mode / third mode / second mode", the first battery 91 and the second battery 92 are charged little by little.

[0044] A preferred time interval for mode switching will now be described. The charging circuit 10 includes a resonant circuit consisting of a third capacitor 13 and a coil 15. The capacitance of the third capacitor 13 is represented by the symbol "C", and the reactance of the coil 15 is represented by the symbol "L". The resonant frequency fr of the resonant circuit is fr = 1 / (2 × PAI × Root(LC)). Here, "PAI" represents the constant of the circumference of a circle, and Root(X) represents the square root of X. The resonant period Tr is represented by the reciprocal of the resonant frequency, Tr = 1 / fr = 2 × PAI × Root(LC).

[0045] The controller 24 controls the switches 21, 22, and 23 so that the mode is switched at a time interval (=Tr / 2) corresponding to half the period (resonance period) of the resonant circuit formed by the coil 15 and the third capacitor 13. The advantages of this process will be explained with reference to Figures 4 and 5. In the following, the time interval (=Tr / 2) corresponding to half the period (resonance period) of the resonant circuit may be referred to as the resonant half period (Tr / 2). In addition, in the following, the influence of the capacitors 11, 12, and 14 is ignored for simplicity of explanation.

[0046] Figure 4 is a time chart before and after switching from the third mode to the first mode (second mode). The upper graph shows the voltage Vc across the coil 15 and the current Ic flowing through the coil 15, and the lower graph is a graph of the electrical energy stored in the series circuit 16 (i.e., the coil 15 and the fourth capacitor 14). Due to the influence of the reactance L of the coil 15, there is a phase difference of Tr / 4 between the current change and the voltage change in the coil 15. Positive values ​​on the graph of the current Ic represent the current flowing from the coil 15 to the third capacitor 13.

[0047] The period from time zero to time Tr / 2 is the third mode, and the period from time Tr / 2 to time Tr is the first mode (second mode). At time zero, the first mode (or second mode) switches to the third mode. A current Ic flows from the fourth capacitor 14 to the third capacitor 13 (series circuit 16). Due to the influence of the reactance L of the coil 15, the current Ic flowing into the third capacitor 13 forms a sine wave. At time Tr / 2, the current Ic becomes zero. At this time, the energy Ecap stored in the third capacitor 13 becomes maximum. At this time, the energy Ecoil stored in the coil 15 becomes minimum. As is well known, in a series circuit of a coil and a capacitor, in a resonant state, the sum of the coil energy Ecoil and the capacitor energy Ecap is always constant. The capacitor energy Ecap is maximum at time zero and time Tr / 2. At time zero, the voltage across the third capacitor 13 becomes minimum. At time Tr / 2, the voltage across the third capacitor 13 reaches a maximum.

[0048] At time Tr / 2, the mode switches from the third mode to the first mode (or the second mode). This time, the current Ic flows from the third capacitor 13 to the first capacitor 11 (or the second capacitor 12). At this time, due to the influence of the reactance L of the coil 15, the current Ic flowing out of the third capacitor 13 forms a sine wave. At time Tr, the current Ic becomes zero. At this time, the energy Ecap stored in the third capacitor 13 becomes a maximum. At time Tr, as at time zero, the voltage across the third capacitor 13 becomes a minimum.

[0049] The energy Ecap stored in the third capacitor 13 is maximized when the voltage across the third capacitor 13 is maximized and minimized. Therefore, the change period of the energy Ecap is half the change period of the voltage across the third capacitor 13 (i.e., the change period of the voltage Vc across the coil 15). In other words, one period of change in the voltage across the third capacitor 13 (i.e., one period of change in the voltage Vc across the coil 15) includes a process in which electrical energy is stored so that the voltage across the third capacitor 13 is maximized, and a process in which electrical energy is stored so that the voltage across the third capacitor 13 is minimized.

[0050] In this way, by switching modes at a resonant half cycle (Tr / 2), the third capacitor 13 repeatedly charges and discharges. When charging, the current Ic flows from the fourth capacitor 14 to the third capacitor 13. When discharging, the current Ic flows from the third capacitor 13 to the first capacitor 11 (or the second capacitor 12).

[0051] FIG. 5 shows a time chart of the state of each switch and the current when the switches are switched sequentially. In FIG. 4, the symbols "SW1," "SW2," and "SW3" represent the first switch 21, the second switch 22, and the third switch 23, respectively. FIG. 5(1) is a time chart of the operation of SW3 (the third switch 23). FIG. 5(2) is a time chart of the operation of SW1 (the first switch 21). FIG. 5(3) is a time chart of the operation of SW2 (the second switch 22). The switches 21, 22, and 23 are semiconductor switches, and "ON" in FIG. 5 means that the switch is closed, and "OFF" means that the switch is open.

[0052] Figure 5(4) is a time chart of the current Ips flowing out from the DC power supply 90. Figure 5(5) is a term chart of the current Icap3 flowing through the third capacitor 13. In Figure 5(5) as well, positive values ​​indicate the current flowing into the third capacitor 13, and negative values ​​indicate the current flowing out of the third capacitor 13.

[0053] FIG. 5(6) is a time chart of the current Icap31 flowing from the third capacitor 13 to the first capacitor 11, and FIG. 5(7) is a time chart of the current Icap32 flowing from the third capacitor 13 to the first capacitor 11. FIG. 6(A) shows the path of the current Icap31, and FIG. 6(B) shows the path of the current Icap32. The current Icap31 flows from the third capacitor 13 through the coil 15 and diode 31 to the first capacitor 11. The current Icap31 then flows from the first capacitor 11 through the medium-voltage terminal 17b and the first switch 21, and returns to the third capacitor 13. The current Icap32 flows from the third capacitor 13 through the coil 15, the second switch 22, and the medium-voltage terminal 17b to the second capacitor 12. The current Icap32 then flows from the second capacitor 12 through the low-voltage terminal 17c and diode 32, and returns to the third capacitor 13.

[0054] FIG. 5(8) is a time chart of the current Ibt flowing into the batteries (first battery 91 and second battery 92).

[0055] Between times T1 and T2, the controller 24 closes the third switch 23 and opens the first switch 21 and the second switch 22. Current flows from the fourth capacitor 14 to the third capacitor 13. As explained using FIG. 4, electrical energy is stored in the third capacitor 13 during this time. The period from time T1 to T2 corresponds to a resonant half cycle (Tr / 2). In the resonant circuit, the current becomes zero every resonant half cycle. Because the time from time T1 to T2 corresponds to a resonant half cycle (Tr / 2), the current flowing in the third capacitor 13 becomes zero at times T1 and T2.

[0056] At time T2, the controller 24 controls the switches 21, 22, and 23 to switch from the third mode to the first mode. At time T2, the controller 24 closes SW1 (first switch 21) and opens SW2 (second switch 22) and SW3 (third switch 23). Between times T2 and T3, current flows from the third capacitor 13 to the first capacitor 11. The location indicated by arrow A in FIG. 5 indicates that current flows from the third capacitor 13 to the first capacitor 11. Because the time interval from time T2 to T3 is also a half-cycle of the resonance (Tr / 2), the current is also zero at time T3.

[0057] Between times T2 and T3, the total voltage of the first capacitor 11 and the second capacitor 12 rises. Therefore, a current flows from the series-connected circuit of the first capacitor 11 and the second capacitor 12 to the series-connected circuit of the first battery 91 and the second battery 92. In other words, the first battery 91 and the second battery 92 are charged. Figure 5 (8) shows a time chart of the current flowing into the first battery 91 and the second battery 92. A constant current flows into the first battery 91 and the second battery 92.

[0058] At time T3, the controller 24 controls the switches 21, 22, and 23 to switch from the first mode to the third mode. In the third mode, the third capacitor 13 is charged again. At time T4, the controller 24 switches the switches 21, 22, and 23 from the third mode to the second mode. Between times T4 and T5, current flows from the third capacitor 13 to the second capacitor 12. The location indicated by arrow B in FIG. 5 indicates that current flows from the third capacitor 13 to the second capacitor 12. Because the time interval from time T4 to T5 also corresponds to a half-cycle of resonance (Tr / 2), the current is zero at times T4 and T5. A similar mode switching sequence is repeated after time T5.

[0059] The controller 24 constantly switches the switches 21, 22, and 23 at a time interval of one half resonant cycle (Tr / 2). As shown in the graphs of Figures 4 and 5, the current flowing through each switch is almost zero when the switches are switched. Because the switches are switched when the current is zero, power switching loss is reduced. By switching the switches 21, 22, and 23 at the same time as the resonant half cycle (Tr / 2), the charging circuit 10 can reduce switching loss.

[0060] 1-3, the case where the charging circuit 10 simultaneously charges two batteries (first battery 91 and second battery 92) has been described. The charging circuit 10 can also charge only one battery. The controller 24 can charge one battery using the same mode switching sequence as when charging two batteries. Here, the mode switching sequence means that the controller 24 controls the switches 21, 22, and 23 so that the modes are switched in the following order: third mode / first mode / third mode / second mode.

[0061] 7 and 8, the case of charging one battery (third battery 93) will be described. Third battery 93 is connected between high-voltage terminal 17a and low-voltage terminal 17c. The positive electrode of third battery 93 is connected to high-voltage terminal 17a, and the negative electrode is connected to low-voltage terminal 17c.

[0062] The third mode has already been described with reference to FIG. 1. The controller 24 switches from the third mode to the first mode. In the first mode, the controller 24 closes the first switch 21 and opens the second switch 22 and the third switch 23. The thick arrows in FIG. 7 indicate the current flow in the first mode. The thick solid arrows indicate the path of the DC current, and the thick dashed arrows indicate the path of the sinusoidal current. The sinusoidal current is generated by resonance of the series circuit 16 (an LC resonant circuit formed by the coil 15 and the third coil 13).

[0063] Current flows from the series circuit through first diode 31 and high-voltage terminal 17a to first capacitor 11. The negative electrode of first capacitor 11 is connected to series circuit 16 through medium-voltage terminal 17b and first switch 21. The total voltage of first capacitor 11 and second capacitor 12 increases. Current flows from the series circuit of first capacitor 11 and second capacitor 12 to third battery 93. That is, third battery 93 is charged.

[0064] The controller 24 controls the switches 21, 22, and 23 to switch the mode from the first mode to the third mode. The third mode has been described with reference to FIG. 1. In the third mode, the third capacitor 13 is charged. Next, the controller 24 controls the switches 21, 22, and 23 to switch the mode from the third mode to the second mode. In the second mode, the controller 24 closes the second switch 22 and opens the first switch 21 and the third switch 23. The thick arrows in FIG. 8 indicate the current flow in the second mode. In FIG. 8 as well, the thick solid arrows indicate the path of the DC current, and the thick dashed arrows indicate the path of the sinusoidal current. The sinusoidal current is generated by resonance of the series circuit 16 (an LC resonant circuit formed by the coil 15 and the third coil 13).

[0065] Current flows from third capacitor 13 to second capacitor 12 through second switch 22 and medium voltage terminal 17b. The negative electrode of second capacitor 12 is electrically connected to third capacitor 13 through low voltage terminal 17c and second diode 32. The total voltage of first capacitor 11 and second capacitor 12 increases. Current flows from the series circuit of first capacitor 11 and second capacitor 12 to third battery 93. The third battery 93 is also charged in the second mode.

[0066] In this way, the charging circuit 10 can charge one battery using the same mode switching sequence as when charging two batteries.

[0067] (Second Embodiment) A charging circuit 10a of a second embodiment will be described with reference to Figures 9-11. The charging circuit 10a of the second embodiment can charge a battery in the same way as the charging circuit 10 of the first embodiment. In addition, the charging circuit 10a can supply power from the battery to an electrical device. In Figures 9-11, an electrical device 95 is connected to the charging circuit 10a instead of the power supply 90 of Figure 1.

[0068] Figures 9-11 show circuit diagrams of the charging circuit 10a. The charging circuit 10a adds switches 21b, 22b, and 23b to the circuitry of the charging circuit 10 of the first embodiment. Note that the switches 21, 22, and 23 in Figure 1 are given the reference numerals 21a, 22a, and 23a in Figures 9-11. In the charging circuit 10a, the first switch 21, the second switch 22, and the third switch 23 in Figure 1 are referred to as the 1A switch 21a, the 2A switch 22a, and the 3A switch 23a, respectively. Furthermore, the newly added switches 21b, 22b, and 23b are referred to as the 1B switch 21b, the 2B switch 22b, and the 3B switch 23b, respectively.

[0069] The first-B switch 21b is connected in parallel with the first diode 31. That is, the first-B switch 21b is connected between the high-voltage side 16a of the series circuit 16 and the high-voltage terminal 17a. The second-B switch 22b is connected in parallel with the second diode 32. That is, the second-B switch 22b is connected between the low-voltage terminal 17c and the low-voltage side 16b of the series circuit 16. The third-B switch 23b is connected in parallel with the third diode 33. That is, the third-B switch 23b is connected between the low-voltage side 16b and the negative input terminal 17e.

[0070] The controller 24 simultaneously opens or simultaneously closes the first-A switch 21a and the first-B switch 21b. Therefore, the first-A switch 21a and the first-B switch 21b are collectively referred to as the first switch 21. The controller 24 simultaneously opens or simultaneously closes the second-A switch 22a and the second-B switch 22b. Therefore, the second-A switch 22a and the second-B switch 22b are collectively referred to as the second switch 22. The controller 24 simultaneously opens or simultaneously closes the third-A switch 23a and the third-B switch 23b. Therefore, the third-A switch 23a and the third-B switch 23b are collectively referred to as the third switch 23.

[0071] As in the first embodiment, a state in which the controller 24 closes the first switch 21 (21a, 21b) and opens the second switch 22 (22a, 22b) and the third switch 23 (23a, 23b) is referred to as a first mode. A state in which the controller 24 closes the second switch 22 (22a, 22b) and opens the first switch 21 (21a, 21b) and the third switch 23 (23a, 23b) is referred to as a second mode. A state in which the controller 24 closes the third switch 23 (23a, 23b) and opens the first switch 21 (21a, 21b) and the second switch 22 (22a, 22b) is referred to as a third mode.

[0072] First mode: When the controller 24 closes the first switch 21 (21a, 21b) and opens the second switch 22 (22a, 22b) and the third switch 23 (23a, 23b), the first capacitor 11 (i.e., the first battery 91) is connected to the series circuit 16, and the second capacitor 12 (i.e., the second battery 92) and the electrical device 95 are disconnected from the series circuit 16.

[0073] Second mode: When the controller 24 closes the second switch 22 (22a, 22b) and opens the first switch 21 (21a, 21b) and the third switch 23 (23a, 23b), the second capacitor 12 (i.e., the second battery 92) is connected to the series circuit 16, and the first capacitor 11 (i.e., the first battery 91) and the electrical device 95 are disconnected from the series circuit 16.

[0074] Third mode: When the controller 24 closes the third switch 23 (23a, 23b) and opens the first switch 21 (21a, 21b) and the second switch 22 (22a, 22b), the electrical device 95 is connected to the series circuit 16 and the first capacitor 11 (i.e., the first battery 91) and the second capacitor 12 (i.e., the second battery 92) are disconnected from the series circuit 16.

[0075] When a power supply 90 is connected to the charging circuit 10a instead of the electric device 95 and the controller 24 executes the mode switching sequence in the same manner as in the first embodiment, the batteries 91 and 92 are charged by the power from the power supply 90.

[0076] When an electric device 95 is connected to the charging circuit 10a and a mode switching sequence similar to that in the first embodiment is executed, power can be supplied from the batteries 91 and 92 to the electric device 95.

[0077] FIG. 9 shows the current flow in the first mode (power supply). The thick arrows in FIG. 9 indicate the current flow in the first mode (power supply). In FIG. 9, the thick solid arrows indicate the path of the DC current, and the thick dashed arrows indicate the path of the sinusoidal current. The sinusoidal current is generated by resonance of the series circuit 16 (an LC resonant circuit formed by the coil 15 and the third coil 13).

[0078] In the first mode, the series circuit 16 is connected to the first capacitor 11 (i.e., the first battery 91) through the first switch 21 (21a, 21b). By opening the second switch 22 (22a, 22b) and the third switch 23 (23a, 23b), the series circuit 16 is disconnected from the electric device 95 and the second capacitor 12. Before switching to the first mode, the first capacitor 11 and the second capacitor 12 are charged by the first battery 91 and the second battery 92.

[0079] As soon as the first switch 21 is closed, current begins to flow from the first capacitor 11 to the series circuit 16. As with charging a battery, the current gradually increases and then decreases due to resonance between the third capacitor 13 and the coil 15. In this way, a sinusoidal current flows from the first capacitor 11 to the third capacitor 13 (indicated by the dashed arrow in Figure 9). When a half-cycle (Tr / 2) of resonance has elapsed since the first switch 21 was closed, the current returns to zero, and the electrical energy stored in the third capacitor 13 reaches a maximum.

[0080] In the first A switch 21a, current also flows through the diode 34. Therefore, in the first mode during power supply, the first A switch 21a may be off (open). However, in the first mode, current flows from one terminal of the first A switch 21a to the other terminal (through the diode 34), so in circuit theory, the first A switch 21a is in a state equivalent to being in an on state (closed state).

[0081] The controller 24 switches the mode from the first mode to the third mode. FIG. 10 shows the current flow in the third mode (power supply). The thick arrows in FIG. 10 indicate the current flow in the third mode (power supply). As with the previous circuit diagrams, the thick solid arrows indicate the path of the DC current, and the thick dashed arrows indicate the path of the sinusoidal current. The sinusoidal current is generated by resonance of the series circuit 16 (an LC resonant circuit formed by the coil 15 and the third coil 13).

[0082] In the third mode, the series circuit 16 is connected to the electric device 95 through the third switch 23 (23a, 23b). By opening the first switch 21 (21a, 21b) and the second switch 22 (22a, 22b), the series circuit 16 is disconnected from the first capacitor 11 (first battery 91) and the second capacitor 12 (second battery 92).

[0083] As soon as the third switch 23 is closed, a current begins to flow from the third capacitor 13 to the fourth capacitor 14. As in the case of charging a battery, a sinusoidal current flows from the third capacitor 13 to the fourth capacitor 14 due to resonance between the third capacitor 13 and the coil 15 (indicated by the dashed arrow in FIG. 10). When a half resonance period (Tr / 2) has elapsed since the third switch 23 was closed, the current returns to zero, and all the electrical energy stored in the third capacitor 13 is transferred to the fourth capacitor 14. This electrical energy supplies power from the fourth capacitor 14 to the electrical device 95.

[0084] In the 3A switch 23a, current also flows through the diode 36. Therefore, in the third mode during power supply, the 3A switch 23a may be off (open). However, in the third mode, current flows from one terminal of the 3A switch 23a to the other terminal (through the diode 36), so in circuit theory, the 3A switch 23a is in a state equivalent to being in an on state (closed state).

[0085] FIG. 11 shows the current flow in the second mode (power supply). The thick arrows in FIG. 11 show the current flow in the second mode (power supply). In FIG. 11, the thick solid arrows also show the path of the DC current, and the thick dashed arrows show the path of the sinusoidal current. The sinusoidal current is generated by the resonance of series circuit 16 (an LC resonant circuit formed by coil 15 and third coil 13).

[0086] In the second mode, the series circuit 16 is connected to the second capacitor 12 (i.e., the second battery 92) through the second switch 22 (22a, 22b). By opening the first switch 21 (21a, 21b) and the third switch 23 (23a, 23b), the series circuit 16 is disconnected from the electric device 95 and the first capacitor 11. Before switching to the second mode, the first capacitor 11 and the second capacitor 12 are charged by the first battery 91 and the second battery 92.

[0087] As soon as the second switch 22 is closed, a current begins to flow from the second capacitor 12 to the third capacitor 13. Due to resonance between the third capacitor 13 and the coil 15, a sinusoidal current flows from the second capacitor 12 to the third capacitor 13 (indicated by the dashed arrow in FIG. 11). When a half-cycle (Tr / 2) of resonance has elapsed since the second switch 22 was closed, the current returns to zero, and the electrical energy stored in the third capacitor 13 reaches a maximum.

[0088] When the controller 24 switches the mode from the second mode to the third mode, similar to when switching from the first mode to the third mode, current flows from the third capacitor 13 to the fourth capacitor 14, and power is stored in the fourth capacitor 14. Power is supplied from the fourth capacitor 14 to the electric device 95.

[0089] In the second A switch 22a, current also flows through the diode 35. Therefore, in the second mode during power supply, the second A switch 22a may be off (open). However, in the second mode, current flows from one terminal of the second A switch 22a to the other terminal (through the diode 35), so in circuit theory, the second A switch 22a is in a state equivalent to being in an on state (closed state).

[0090] The controller 24 controls the switches 21 (21a, 21b), 22 (22a, 22b), and 23 (23a, 23b) so that the modes are switched in the order of first mode / third mode / second mode / third mode. The controller 24 controls the switches so that the modes are switched repeatedly. Therefore, the process of "switching in the order of first mode / third mode / second mode / third mode" is equivalent to the process of "switching in the order of third mode / first mode / third mode / second mode."

[0091] In this way, the charging circuit 10a of the second embodiment can charge the battery by connecting to a power source, and can supply power from the battery to the electrical device by connecting to the electrical device. The controller 24 can achieve both charging and power supply using the same mode switching sequence.

[0092] FIG. 12 shows an example of the relationship between the power supply and the batteries during charging. FIG. 12(A) shows an example in which two batteries (a first battery 91 and a second battery 92) are charged. FIG. 12(A) shows an example in which a first battery 91 of 360 V is connected between the high-voltage terminal 17 a and the medium-voltage terminal 17 b, and a second battery 92 of 360 V is connected between the medium-voltage terminal 17 b and the low-voltage terminal 17 c. The power supply 90 can supply a constant current of 400 A. When the controller 24 executes the mode switching sequence described above, both the first battery 91 and the second battery 92 are charged to 400 V. Note that the "mode switching sequence described above" refers to the controller 24 controlling the switches 21, 22, and 23 so that the third mode / first mode / third mode / second mode are repeated in this order.

[0093] FIG. 12(B) shows an example in which one battery (third battery 93) is charged. In FIG. 12(B), the third battery 93 of 780 [V] is connected between the high voltage terminal 17a and the low voltage terminal 17c. The power supply 90 can supply a constant current of 400 [A]. When the controller 24 executes the mode switching sequence described above, the third battery 93 is charged up to 800 [V].

[0094] The example of FIG. 12 is valid even if the charging circuit 10 is replaced with a charging circuit 10a.

[0095] An example of the relationship between the power source and the batteries during power supply is shown in Figure 13. Figure 13(A) shows an example in which two batteries (a first battery 91 and a second battery 92) are used to supply power to an electric device 95. For power supply, the charging circuit 10a of the second embodiment is used. The first battery 91 of 400 [V] is connected between the high-voltage terminal 17a and the medium-voltage terminal 17b of the charging circuit 10a, and the second battery 92 of 400 [V] is connected between the medium-voltage terminal 17b and the low-voltage terminal 17c. When the controller 24 executes the mode switching sequence described above, a constant current of 100 [A] is supplied from the charging circuit 10a to the electric device 95.

[0096] 13(B) shows an example in which one battery (third battery 93) is used to power an electric device 95. The third battery 93 of 800 V is connected between the high-voltage terminal 17 a and the low-voltage terminal 17 c of the charging circuit 10 a. When the controller 24 executes the mode switching sequence described above, a constant current of 100 A is supplied from the charging circuit 10 a to the electric device 95.

[0097] As described above, the charging circuits 10, 10a can simultaneously charge the first battery 91 and the second battery 92. In particular, the charging circuits 10, 10a can shorten the charging time by forcing current (power) into the batteries using the electrical energy stored in the third capacitor 13. The charging circuit 10a can also supply power from the batteries 91, 92 to the electrical device 95. The mode switching sequence during power supply may be the same as the mode switching sequence during charging.

[0098] The controller 24 controls the switches 21, 22, and 23 so that the mode is switched at time intervals corresponding to a half resonance period (Tr / 2) of the resonance circuit (series circuit 16) formed by the coil 15 and the third capacitor 13. By switching the mode (switching the switches) every half resonance period (Tr / 2), switching loss can be reduced.

[0099] The preferred relationship between the voltage of the DC power supply 90 and the battery voltage will now be described. When charging two batteries (first battery 91 and second battery 92), it is desirable that the voltage of the DC power supply 90 be the same as the voltage of each battery. The voltage of the DC power supply 90 may also be twice the voltage of each battery.

[0100] When charging one battery (third battery 93), the voltage of DC power supply 90 is preferably half that of one battery. The voltage of DC power supply 90 may be the same as the voltage of one battery. Because charging circuit 10 uses the electrical energy stored in third capacitor 13 to push current (power) into the battery, the voltage of the DC power supply may be lower than the voltage of the battery.

[0101] In the charging circuit 10a of the second embodiment, the third B switch 23b may be omitted. The arrangement of the first switch 21 in Figure 1-3 is an example, and the first switch 21 is not limited to the configuration in Figure 1-3. The first switch 21 may be any switch that can connect the series circuit 16 to the first capacitor 11 and also disconnect the two.

[0102] 1-3 are also examples. The second switch 22 may be any switch that can connect the series circuit 16 to the second capacitor 12 and disconnect the two. The third switch 23 may be any switch that can connect the series circuit 16 to the DC power supply 90 and disconnect the two.

[0103] Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above. The technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technology exemplified in this specification or drawings can achieve multiple objectives simultaneously, and achieving one of these objectives alone is technically useful. [Explanation of symbols]

[0104] 10, 10a: Charging circuit 11-14: Capacitor 15: Coil 16: Series circuit 17a: High voltage terminal 17b: Medium voltage terminal 17c: Low voltage terminal 21-23: Switch 24: Controller 31-34: Diode 90: DC power supply 91-93: Battery 95: Electrical device

Claims

1. a high voltage terminal to which the positive electrode of the first battery is connected; a medium voltage terminal to which the negative electrode of the first battery and the positive electrode of the second battery are connected; a low voltage terminal to which the negative electrode of the second battery is connected; a first capacitor connected between the high voltage terminal and the medium voltage terminal; a second capacitor connected between the medium voltage terminal and the low voltage terminal; a series circuit in which the coil and a third capacitor are connected in series; a fourth capacitor connected in parallel with the power supply; a first switch connecting the series circuit between the high voltage terminal and the medium voltage terminal; a second switch connecting the series circuit between the medium voltage terminal and the low voltage terminal; a third switch connecting the series circuit to the power supply and the fourth capacitor; a controller that controls the first switch, the second switch, and the third switch; It is equipped with The controller a first mode in which the first switch is closed and the second switch and the third switch are open; a second mode in which the second switch is closed and the first switch and the third switch are open; a third mode in which the third switch is closed and the first switch and the second switch are open; and controls the first / second / third switches to cycle through the third mode, the first mode, the third mode, and the second mode in this order.

2. 2. The charging circuit according to claim 1, wherein the controller controls the first / second / third switches so that the first / second / third modes are switched sequentially at a time interval that is half a resonant period of a resonant circuit formed by the coil and the third capacitor.

3. a first diode having an anode connected to the high-voltage side of the series circuit and a cathode connected to the high-voltage terminal; a second diode having an anode connected to the low voltage terminal and a cathode connected to the low voltage side of the series circuit; It also has the first switch is connected between the medium voltage terminal and the low voltage side; the second switch is connected between the high voltage side and the medium voltage terminal; 3. A charging circuit according to claim 1 or 2.

4. the first switches include a first A switch and a first B switch; the second switches include a second A switch and a second B switch; the first A switch is connected between the medium voltage terminal and the low voltage side of the series circuit; the first B switch is connected between the high voltage side of the series circuit and the high voltage terminal; the second A switch is connected between the high voltage side and the medium voltage terminal; the second B switch is connected between the low voltage terminal and the low voltage side; 3. A charging circuit according to claim 1 or 2.

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