Controller for controlling an inverter for battery charge and discharge and a charger / discharger

Abstract

The present invention discloses a charger / discharger for charging and discharging a battery. The charger / discharger includes an inverter, and the inverter includes: a transformer; a first switching circuit that forms a current path between a power supply unit and a primary winding of the transformer within a first transfer interval; and a second switching circuit that forms a current path between the battery and a secondary winding of the transformer within a second transfer interval. The first switching circuit has a dead time interval during which no current path is formed between the power supply unit and the primary winding of the transformer. The inverter operates in such a manner that the length of the overlapping portion between the dead time interval during battery discharge and the second transfer interval is less than that during battery charging.

Description

Technical Field

[0001] The present invention relates to a controller and a charger / discharger for controlling an inverter for charging and discharging a battery. Background Art

[0002] A secondary battery is a battery that can be repeatedly discharged and charged and reused, and is used in various electronic articles. In particular, recently, it has been widely applied to portable electronic devices such as mobile devices and smart watches, and its usage amount has gradually increased with the popularization of electric vehicles.

[0003] A secondary battery can be made into a packaged form having a plurality of electromagnetic units. The secondary battery manufactured in a process or the like is not directly shipped out, but can be shipped out after passing through a formation process. The formation process is a process of activating the secondary battery so that it can be normally used.

[0004] In the formation process, there is a formation process of repeatedly charging and discharging the secondary battery. During the above-mentioned formation process, an inverter is used to continuously charge and discharge the battery. In this case, when the battery is charged and discharged, the higher the efficiency, the more the energy efficiency during the entire formation process is improved. Summary of the Invention

[0005] An object of the present invention is to provide a controller and a charger / discharger for improving the efficiency difference between battery charging and discharging of an inverter included in a charger / discharger.

[0006] An object of the present invention is to provide a controller and a charger / discharger that can improve the problem of reduced efficiency during battery discharge of an inverter of a charger / discharger by adjusting the position of the dead time interval of a plurality of switches of a primary side switching circuit of the inverter of the charger / discharger.

[0007] The charger / discharger according to an embodiment of the present invention is connected between a power supply unit and a battery and is used for charging and discharging the battery. The charger / discharger includes an inverter. The inverter includes: a transformer for transferring power between the power supply unit and the battery; a first switching circuit for forming a current path between the power supply unit and the primary winding of the transformer in a first transfer interval according to a switching operation; and a second switching circuit for forming a current path between the battery and the secondary winding of the transformer in a second transfer interval according to a switching operation. The first switching circuit has a dead time interval in which a current path between the power supply unit and the primary winding of the transformer is not formed. The inverter operates in such a way that the length of the overlapping portion between the dead time interval and the second transfer interval during battery discharge is less than the length during battery charging.

[0008] The controller and the charger / discharger according to the embodiments of the present invention have the following effects, that is, they can improve the efficiency difference during battery charging and discharging of the converters included in the charger / discharger.

[0009] The controller and the charger / discharger according to the embodiments of the present invention have the following effects, that is, by adjusting the position of the dead time intervals of multiple switches of the primary side switching circuit of the converter of the charger / discharger, the problem of reduced efficiency during battery discharging of the converter can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 Shows a battery charging and discharging system according to an embodiment of the present invention.

[0011] Figure 2 Shows a controller according to an embodiment of the present invention.

[0012] Figure 3 Shows a converter according to an embodiment of the present invention.

[0013] Figures 4 to 6 Is a diagram for explaining the operation of the converter according to an embodiment of the present invention.

[0014] Figure 7 Shows a switching signal output to the converter during discharging according to an embodiment of the present invention.

[0015] Figure 8 Is a flowchart for explaining the dead time offset according to an embodiment of the present invention.

[0016] Figure 9 Shows a converter according to an embodiment of the present invention. DETAILED DESCRIPTION

[0017] Parts irrelevant to the description are omitted for clear explanation of the present invention, and the same reference numerals are given to the same or similar structural elements throughout the specification.

[0018] Although there is no different definition, the meanings of all terms, including technical terms and scientific terms used herein, are the same as those generally understood by those of ordinary skill in the technical field to which the present invention pertains. The meanings of terms defined in commonly used dictionaries should have meanings consistent with relevant technical literature and the currently disclosed content, and unless otherwise defined, cannot be interpreted as idealized or overly formulaic meanings.

[0019] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the technical field to which the present invention pertains can easily implement the present invention. However, the present invention can be embodied in various different forms and is not limited to the embodiments described herein.

[0020] Figure 1 Shows a battery charging and discharging system according to an embodiment of the present invention. Refer toFigure 1 , the battery charge and discharge system 10 may include a charger 100, a power supply unit 200, and a battery 300.

[0021] The charger 100 can be connected to the power supply unit 200 and the battery 300, and can charge and discharge the battery 300.

[0022] The charger 100 may include an inverter (hereinafter, inverter 110) and a controller 120.

[0023] The inverter 110 can use the power (or voltage / current) transmitted from the power supply unit 200 to charge the battery 300, or transmit the power (or voltage / current) transmitted from the battery 300 to the power supply unit 200 to discharge the battery 300. On the other hand, when the battery 300 discharges, the power transmitted from the battery 300 can be transmitted to the ground connected to the power supply unit 200. According to an embodiment, the inverter 110 can convert the power transmitted from the power supply unit 200 and transmit it to the battery 300, and convert the power transmitted from the battery 300 and transmit it to the power supply unit 200.

[0024] The inverter 110 may include a plurality of switches and a transformer, and transmit power from the power supply unit 200 to the battery 300 or transmit power from the battery 300 to the power supply unit 200 according to the switching operation of the plurality of switches. For example, the inverter 110 can be a phase-shift full bridge inverter, but is not limited thereto.

[0025] The controller 120 can control the inverter 110. According to an embodiment, the controller 120 can generate a switching signal for controlling the switching of the plurality of switches included in the inverter 110. In this case, there can be a plurality of switching signals. For example, the controller 120 can determine whether to charge or discharge the battery 300 based on the stored information, and output a switching signal for controlling the inverter 110 according to whether the determined battery 300 is charging or discharging. That is, the controller 120 can output a switching signal that causes the inverter 110 to charge the battery 300 when the battery 300 is charging, and output a switching signal that causes the inverter 110 to discharge the battery 300 when the battery 300 is discharging.

[0026] The power supply unit 200 can transmit an input power supply to the charger 100. According to an embodiment, the power supply unit 200 can transmit a DC power supply to the charger 100, but the embodiments of the present invention are not limited thereto. Also, the power supply unit 200 can receive the discharge power of the battery 300 transmitted from the charger 100. For example, the power supply unit 200 can output the discharge power of the battery 300 through a ground terminal.

[0027] The battery 300 can be a device capable of storing or supplying electric energy. According to an embodiment, the battery 300 can be a secondary battery that can be repeatedly charged and discharged. For example, the battery 300 can be a lead-acid battery, a nickel-cadmium battery (Ni-Cd battery), a nickel-metal hydride battery (Ni-MH battery), a lithium-ion battery (Li-ion battery), or an all-solid-state battery, but the embodiments of the present invention are not limited thereto.

[0028] The battery 300 can be a general term for a battery cell including a cathode, an anode, an electrolyte, and a separator, a battery module including a plurality of battery cells, or a battery pack including a plurality of battery modules.

[0029] Figure 2 A controller showing an embodiment of the present invention. Refer to Figure 2 , the controller 120 may include a switching signal output circuit 121, a memory 123, and a processor 125.

[0030] The switching signal output circuit 121 can output a switching signal for controlling the converter 110. According to an embodiment, the switching signal output circuit 121 can generate a switching signal for controlling a plurality of switches included in the converter 110 and output the generated switching signal to the converter 110. For example, the switching signal output circuit 121 can output a charging switching signal for charging the battery 300 and a discharging switching signal for discharging the battery 300. That is, in the following description, the charging switching signal and the discharging switching signal are collectively referred to as the switching signal.

[0031] According to an embodiment, the switching signal output circuit 121 can generate a switching signal by using the offset information and the reference clock information stored in the memory 123. For example, the switching signal output circuit 121 can generate a charging switching signal based on the first offset information stored in the first space of the memory 123 and can generate a discharging switching signal based on the second offset information stored in the second space of the memory 123.

[0032] According to an embodiment, the switching signal output circuit 121 can generate a switching signal for controlling the pulse width modulation (PWM) of the converter 110. That is, the switching signal output circuit 121 can control the output power of the converter 110 by adjusting the duty cycle of the switching signal output to the converter 110.

[0033] The memory 123 can store the data required for the operation of the controller 120. According to an embodiment, the memory 123 can store the data for generating the control signal of the converter 110. Also, the memory 123 can store the information related to the charge and discharge scheduling of the battery 300 of the charger 100. Also, the memory 123 can store the information related to the state (voltage, current, temperature, etc.) of the battery 300.

[0034] In this case, the controller 120 can determine whether to charge or discharge the battery 300 based on the information related to the charge and discharge scheduling of the battery 300 stored in the memory 123.

[0035] The processor 125 can control the overall operation of the controller 120. According to an embodiment, the processor 125 can control the operation of the controller 120 by controlling the switching signal output circuit 121 and the memory 123.

[0036] For example, the processor 125, as an integrated circuit with arithmetic processing functions, can be a central processing unit (CPU), a microcontroller unit (MCU), a graphics processing unit (GPU), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or an application processor (AP), but the embodiments of the present invention are not limited thereto.

[0037] The processor 125 can generate a control instruction for causing the switching signal output circuit 121 to output a switching signal. The switching signal output circuit 121 can read the offset information from the memory 123 in response to the control instruction to generate a switching signal.

[0038] The processor 125 can control the switching signal output circuit 121 so that the switching signal output circuit 121 outputs other switching signals according to the charge and discharge state of the battery 300.

[0039] For example, when the battery 300 is in a charging state, the processor 125 can output a first control instruction to the switching signal output circuit 121, and the switching signal output circuit 121 outputs a charging switching signal to the converter 110 in response to the first control instruction. In this case, the switching signal output circuit 121 can generate a charging switching signal in response to the first control instruction.

[0040] For example, when the battery 300 is in a discharging state, the processor 125 may output a second control instruction to the switching signal output circuit 121. In response to the second control instruction, the switching signal output circuit 121 outputs a discharging switching signal to the converter 110. In this case, the switching signal output circuit 121 may generate the discharging switching signal in response to the second control instruction.

[0041] According to an embodiment, the processor 125 may determine whether the battery 300 is in a charging state or a discharging state based on information related to the charge-discharge schedule of the battery 300 stored in the memory 123.

[0042] The switching signal output circuit 121 according to an embodiment of the present invention may output switching signals with different characteristics to the converter 110 according to the charging and discharging states of the battery 300. In particular, even if the power between the converter 110 and the battery 300 is the same, the characteristics of the charging switching signal output during charging and the discharging switching signal output during discharging may be different. As a result, there is an effect that the charging and discharging efficiency of the converter 110 can be improved.

[0043] Figure 3 The converter according to an embodiment of the present invention is shown. Refer to Figure 3 , the converter 110 may include a transformer 111, a first switching circuit 113, a second switching circuit 115, and a current sensor 117. The converter 110 may be connected between the power supply unit 200 and the battery 300.

[0044] On the other hand, additionally, the converter 110 may further include a plurality of devices (inductor L1, inductor L2, and capacitor C) disposed between the power supply unit 200 and the transformer 111 and between the transformer 111 and the battery 300, but this is not necessary.

[0045] The transformer 111 may transfer power between the power supply unit 200 and the battery 300. According to an embodiment, the transformer 111 converts the power of the primary circuit (for example, the power supply unit 200 side circuit) into a specified multiple and transfers it to the secondary circuit (for example, the battery 300 side circuit), or converts the power of the secondary circuit into the reciprocal of the above-specified multiple and transfers it to the primary circuit. For example, the transformer 111 may include a primary winding corresponding to the primary circuit and a secondary winding corresponding to the secondary circuit.

[0046] The first switching circuit 113 may be connected between the power supply unit 200 and the transformer 111. According to an embodiment, the first switching circuit 113 may be connected between the power supply unit 200 and the primary winding of the transformer 111 and form a current path according to the switching operation. For example, according to the switching operation of the first switching circuit 113, current may flow between the power supply unit 200 and the primary winding of the transformer 111.

[0047] The second switching circuit 115 may be connected between the battery 300 and the transformer 111. According to an embodiment, the second switching circuit 115 may be connected between the battery 300 and the secondary winding of the transformer 111 to form a current path according to the switching operation. That is, according to the switching operation of the second switching circuit 115, current may flow between the battery 300 and the secondary winding of the transformer 111.

[0048] That is, the converter 110 according to the embodiment of the present invention may convert the power of the power supply unit 200 according to the operations of the first switching circuit 113 and the second switching circuit 115 and transfer it to the battery 300, and convert the power of the battery 300 and transfer it to the power supply unit 200.

[0049] The first switching circuit 113 may include a plurality of switches SWa, SWb, SWc, and SWd. The plurality of switches SWa, SWb, SWc, and SWd may include switching devices (e.g., transistors or diodes). Additionally, the plurality of switches SWa, SWb, SWc, and SWd may further include energy storage devices such as capacitors.

[0050] The plurality of switches SWa, SWb, SWc, and SWd may be turned on and off in response to the input switching signals Qa, Qb, Qc, and Qd respectively, and a current path is formed between the power supply unit 200 and the primary winding of the transformer 111 according to the turning on and off of the plurality of switches SWa, SWb, SWc, and SWd.

[0051] The first switch SWa may be connected between one end of the power supply unit 200 and one end of the primary winding of the transformer 111 and may operate in response to the first switching signal Qa. The second switch SWb may be connected between the other end of the power supply unit 200 and one end of the primary winding of the transformer 111 and may operate in response to the second switching signal Qb.

[0052] To prevent a short circuit in the circuit, the first switch SWa and the second switch SWb may operate complementarily. That is, the on-time (or off-time) of the first switch SWa and the on-time (or off-time) of the second switch SWb may not overlap with each other. The first switch SWa and the second switch SWb may be referred to as front-end switches.

[0053] The third switch SWc may be connected between one end of the power supply unit 200 and the other end of the primary winding of the transformer 111 and may operate in response to the third switching signal Qc. The fourth switch SWd may be connected between the other end of the power supply unit 200 and the other end of the primary winding of the transformer 111 and operate in response to the fourth switching signal Qd.

[0054] To prevent a short circuit within the circuit, the third switch SWc and the fourth switch SWd can operate complementarily. That is, the on-time (or off-time) of the third switch SWc and the on-time (or off-time) of the fourth switch SWd may not overlap with each other. The third switch SWc and the fourth switch SWd can be referred to as back-end switches.

[0055] The first switching circuit 113 can form a current path between the power supply unit 200 and the primary winding of the transformer 111 within the first transfer interval. For example, the first transfer interval can include an interval in which the first switch SWa and the fourth switch SWd are off and an interval in which the second switch SWb and the third switch SWc are on.

[0056] The second switching circuit 115 can include a plurality of switches SWe and Swf. The plurality of switches SWe and Swf can each include a switching device (e.g., a transistor or a diode). Additionally, the plurality of switches SWe and Swf can each further include an energy storage device such as a capacitor.

[0057] The plurality of switches SWe and Swf can be turned on and off in response to the input switching signals Qe and Qf respectively, and form a current path between the battery 300 and the secondary winding of the transformer 111 according to the on and off of the plurality of switches SWe and Swf.

[0058] The fifth switch SWe can be connected between one end of the battery and one end of the secondary winding of the transformer 111 and operate in response to the fifth switching signal Qe. According to an embodiment, one end of the fifth switch SWe can be connected together to one end of the secondary winding of the transformer 111 and the other end of a first inductor L1 whose one end is connected to the other end of the battery 300.

[0059] The sixth switch SWf can be connected between one end of the battery and the other end of the secondary winding of the transformer 111 and operate in response to the sixth switching signal Qf. According to an embodiment, one end of the sixth switch SWf can be connected together to the other end of the secondary winding of the transformer 111 and the other end of a second inductor L2 whose one end is connected to the other end of the battery 300.

[0060] The second switching circuit 115 can form a current path between the power supply unit 200 and the secondary winding of the transformer 111 within the second transfer interval. For example, the second transfer interval can include an interval in which at least one of the fifth switch SWe and the sixth switch SWf is off.

[0061] The current sensor 117 can measure the current flowing between the battery 300 and the converter 110. According to an embodiment, the current sensor 117 can be connected between the second switching circuit 115 and the battery 300, measure the intensity and direction of the current flowing between the second switching circuit 115 and the battery 300, and generate a measurement result.

[0062] According to an embodiment, the measurement result based on the current sensor 117 can be transmitted to the controller 120.

[0063] Among them, the first switch pair corresponds to the first switch SWa and the second switch SWb or the third switch SWc and the fourth switch SWd, and the second switch pair corresponds to the fifth switch SWe and the sixth switch SWf.

[0064] Figures 4 to 6 It is a diagram for explaining the operation of the converter according to the embodiment of the present invention.

[0065] Refer to Figures 4 to 6 , as the multiple switches SWa to SWf of the converter 110 are turned on and off, a current path between the power supply unit 200 and the battery 300 is formed, so that the electric energy between the power supply unit 200 and the battery 300 can move. In this case, the charging and discharging of the battery 300 can be determined according to the magnitudes of the current voltage of the battery 300 and the output voltage of the converter 110.

[0066] Refer to Figure 4 , the controller 120 can output switching signals Qa to Qf for controlling the converter 110. According to an embodiment, the controller 120 can output switching signals for controlling the converter 110 based on the stored charge and discharge scheduling information of the battery 300 and the current state of the battery 300 (for example, voltage, state of health (SOH), state of charge (SOC)). For example, Figure 4 The switching signals Qa to Qf shown can be charging switching signals.

[0067] According to an embodiment, the switching signals Qa to Qf can be pulse width modulation signals in the form of pulses with a specified period. The multiple switches SWa to SWf can be turned on in response to the respective switching signals Qa to Qf at a high level and can be turned off in response to the respective switching signals Qa to Qf at a low level. However, it is not limited thereto.

[0068] According to an embodiment, the duty ratios of the switching signals Qa, Qb, Qc, and Qd can be 50%. On the other hand, the magnitude of the output voltage (voltage across the primary winding / secondary winding) of the converter 110 can be based on the overlapping width of the high interval of the first switching signal Qa and the high interval of the fourth switching signal Qd.

[0069] For the complementary operation of multiple front-end switches SWa and SWb, the high intervals of the first switching signal Qa and the second switching signal Qb may not overlap. For the stable complementary operation of multiple front-end switches SWa and SWb, a first dead-time interval DT1 may exist between the high interval of the first switching signal Qa and the high interval of the second switching signal Qb. That is, the controller 120 may output the rising edge of the second switching signal Qb after the first dead time from the time point when the falling edge of the first switching signal Qa is output.

[0070] Similarly, for the complementary operation of multiple back-end switches SWc and SWd, the high intervals of the third switching signal Qc and the fourth switching signal Qd may not overlap. A second dead-time interval DT2 may exist between the high interval of the third switching signal Qc and the high interval of the fourth switching signal Qd. That is, the controller 120 may output the rising edge of the fourth switching signal Qd after the second dead time from the time point when the falling edge of the third switching signal Qc is output.

[0071] On the other hand, during the dead-time intervals DT1 and DT2 of the first switching circuit 113, a pair of complementary switches SWa and SWb are both turned off, and only one of the other pair of complementary switches SWc and SWd is turned on. Therefore, a current path of the first switching circuit 113 is not formed.

[0072] Refer to Figure 5 and show the operation of the converter in the interval Figure 4 [t0, t3].

[0073] In the interval [t0, t1], multiple switches SWa and SWb are both turned off. That is, the interval [t0, t1] is the first dead-time interval DT1. In the interval [t0, t1], energy is not transferred through the transformer 111.

[0074] In the interval [t1, t2], in response to the switching signal, the second switch SWb and the third switch SWc will be turned on. According to the complementary operation, the first switch SWa and the fourth switch SWd will be turned off. Also, the sixth switch SWf is turned off, and according to the complementary operation, the fifth switch SWe will be turned on. In the interval [t1, t2], the power of the power supply unit 200 is applied to the primary winding of the transformer 111. The transformer 111 converts the power applied to the primary winding and transfers it to the secondary winding. The converted power transferred to the secondary winding of the transformer 111 passes through the second inductor L2 and is transferred to the battery 300. That is, in the interval [t1, t2], energy is transferred through the transformer 111 to charge (or discharge) the battery 300.

[0075] In the interval [t2, t3], multiple switches SWc and SWd are both closed. That is, the interval [t2, t3] is the second dead time interval DT2, and energy is not transferred through the transformer 111.

[0076] Refer to Figure 6 , which shows the operation of the converter in the interval [t4, t7] of Figure 4 .

[0077] In the interval [t4, t5], multiple switches SWa and SWb are both closed. That is, the interval [t4, t5] is the first dead time interval DT1. In the interval [t4, t5], energy is not transferred through the transformer 111.

[0078] In the interval [t5, t6], in response to the switching signal, the first switch SWa and the fourth switch SWd will turn on. According to complementary operation, the second switch SWb and the third switch SWc will turn off. Also, the fifth switch SWe is off, and according to complementary operation, the sixth switch SWf will turn on. In the interval [t5, t6], the power of the power supply unit 200 is applied to the primary winding of the transformer 111. The transformer 111 converts the power applied to the primary winding to transfer it to the secondary winding. The converted power transferred to the secondary winding of the transformer 111 passes through the second inductor L2 to be transferred to the battery 300. That is, in the interval [t5, t6], energy is transferred through the transformer 111 to charge (or discharge) the battery 300.

[0079] In the interval [t6, t7], multiple switches SWc and SWd are both closed. That is, the interval [t6, t7] is the second dead time interval DT2, and energy is not transferred through the transformer 111.

[0080] As described above, energy transfer (i.e., charging) between the power supply unit 200 and the battery 300 can be performed in the interval E where the first transfer interval W1 of the first switching circuit 113 and the second interval W2 of the second switching circuit 115 overlap. In the above interval, the battery 300 can be charged or discharged.

[0081] On the other hand, referring to Figure 4 again, the dead time interval DT1 or DT2 of the first switching circuit 113 and the second transfer interval W2 of the second switching circuit 115 can at least partially overlap. In this case, due to the asymmetry of the first switching circuit 113 and the second switching circuit 115, it is possible that the discharge efficiency of the battery 300 is less than the charging efficiency.

[0082] To this end, in the charger / discharger 100 according to the embodiment of the present invention, the length of the overlapping portion of the dead time intervals DT1 or DT2 of the plurality of switches of the first switching circuit 113 and the second transfer interval of the second switching circuit 115 during discharging is made relatively smaller than that during charging. Thus, the efficiency during discharging of the battery 300 can be relatively increased.

[0083] In this case, the phenomenon that the overlapping portion of the dead time intervals DT1 or DT2 of the plurality of switches of the first switching circuit 113 and the second transfer interval of the second switching circuit 115 during discharging is smaller than that during charging is referred to as "dead time shift".

[0084] Figure 7 Shows the switching signals output to the converter during discharging according to the embodiment of the present invention. Figure 7 The switching signals Qa to Qf shown may be signals output by the controller 120 during discharging of the battery 300. On the other hand, when the battery 300 is being charged, the controller 120 may output Figure 4 the switching signals Qa to Qf shown.

[0085] The controller 120 can determine whether the battery 300 is in a charging state or a discharging state (i.e., whether the converter 110 is in a charging operating state or a discharging operating state), and output the switching signals Qa to Qf corresponding to charging or discharging respectively according to the determination result.

[0086] According to an embodiment, the controller 120 can use the measurement result generated by the current sensor 117 to determine whether the battery 300 is in a charging state or a discharging state. According to an embodiment, the current sensor 117 can measure the intensity and direction of the current between the converter 110 and the battery 300, and transmit the measurement result to the controller 120. The controller 120 can determine whether the battery 300 is in a charging state or a discharging state through the above measurement result. For example, when the measurement result shows that the current flows from the converter 110 towards the battery 300, the controller 120 can determine that the battery 300 is in a charging state.

[0087] Alternatively, according to an embodiment, the controller 120 can use the information related to the charge / discharge schedule of the battery 300 stored in the memory 123 to determine whether the current battery 300 is in a charging state or a discharging state. In this case, Figure 3 the current sensor 117 shown can be omitted.

[0088] When with Figure 4When comparing, the controller 120 can output switching signals Qa to Qf so that the length of the overlapping part between the dead time intervals DT1 or DT2 of the first switching circuit 113 and the second transfer interval of the second switching circuit 115 during discharging is less than that during charging. For example, when charging and discharging, the controller 120 can output different switching signals Qa to Qd to the first switching circuit 113.

[0089] The controller 120 can maintain the charge and discharge voltage of the battery 300 (or the output voltage of the charger / discharger 100) and perform dead time offset. That is, according to an embodiment of the present invention, even if the current voltage of the battery 300 is the same, depending on whether the battery 300 is in a charging state or a discharging state, switching signals Qa to Qf for controlling the converter 110 are output in such a way that the overlapping parts of the dead time intervals DT1 or DT2 of multiple switches and the second transfer interval of the second switching circuit 115 are different.

[0090] According to an embodiment, the controller 120 makes the duty lengths and duty ratios of the switching signals Qa to Qd during charging and discharging of the battery 300 the same, and performs dead time offset only by adjusting the positions of the dead time intervals DT1 or DT2 of the switching signals Qa to Qd. For example, even if the dead time is offset, the lengths of the dead time intervals DT1 or DT2 themselves may not change.

[0091] According to an embodiment, the controller 120 can perform dead time offset by adjusting the relative positions of the switching signals Qe or Qf of the second switching circuit 115 with respect to the switching signals Qa to Qd of the first switching circuit 113.

[0092] According to an embodiment, for the reference clock signal, the controller 120 can perform dead time offset with different offsets during charging and discharging of the battery 300.

[0093] According to this dead time offset, the efficiency of the charger / discharger 100 during discharging of the battery 300 can be improved.

[0094] For example, Figure 4 in the case where, in the overlapping part between the dead time intervals DT1 or DT2 of multiple switches and the second transfer interval of the second switching circuit 115, the battery 300 forms a current path with the secondary winding of the transformer 111, however, the primary winding of the transformer 111 does not form a current path with the power supply unit 200, thus the discharging efficiency of the battery 300 will decrease. For example, the energy transfer interval E becomes smaller than the second transfer interval W2 of the second switching circuit 115 due to the first dead time interval DT1.

[0095] On the contrary, in Figure 7In this case, since there is no overlapping portion between the dead time intervals DT1 or DT2 of the multiple switches and the second transfer interval of the second switching circuit 115, a current path is formed between the battery 300 and the secondary winding of the transformer 111 while a current path is formed between the power supply unit 200 and the primary winding of the transformer 111. Therefore, the discharge efficiency of the battery 300 will not decrease. For example, since the first dead time interval DT1 is located outside the second transfer interval W2, the energy transfer interval E' will be the same as the second transfer interval W2.

[0096] Figure 8 FIG. is a flowchart for explaining the dead time offset of an embodiment of the present invention. Refer to Figure 8 The method described can be executed by the controller 120.

[0097] Refer to Figure 8 , the controller 120 can calculate the charge and discharge efficiency of the battery 300 of the converter 110 before and after the dead time offset, compare the charge and discharge efficiency with a reference value, and adjust whether to additionally execute the dead time offset and the execution degree according to the comparison result.

[0098] Refer to Figure 8 , the controller 120 can determine whether the battery 300 is in a discharge state (step S110). According to an embodiment, the processor 125 can use information related to the battery 300 to determine whether the battery 300 is in a discharge state. For example, the processor 125 can determine whether the battery 300 is in a discharge state based on the charge and discharge schedule of the charger 100 for the battery 300, the direction of the current flowing into the battery 300, and the voltage of the battery 300.

[0099] The controller 120 can calculate the charge and discharge efficiency Eff_pre before the dead time offset (step S120). According to an embodiment, the processor 125 can calculate the charge and discharge efficiency Eff_pre based on the ratio of the input power to the output power of the converter 110.

[0100] According to an embodiment, the charge and discharge efficiency Eff_pre can be calculated according to the following mathematical formula 1.

[0101] Mathematical formula 1

[0102] Eff pre =f((V out ×I out ),(V in ×I in ))

[0103] where f is an arbitrary function, V out is the output voltage of the converter 110, I out is the output current of the converter 110, Vin is the input voltage of the converter 110, I in is the input current of the converter 110.

[0104] The processor 125 may store the charge-discharge efficiency Eff_pre before the calculated dead-time offset in the memory 123.

[0105] The controller 120 may perform a dead-time offset (step S130). According to an embodiment, the processor 125 may control the switching signal output circuit 121 to output a switching signal such that the overlapping portion of the dead-time intervals DT1 or DT2 of the plurality of switches of the first switching circuit 113 during discharging and the second transfer interval of the second switching circuit 115 is less than that during charging.

[0106] According to an embodiment, the controller 120 may offset the dead-time interval DT1 or DT2 by a positive offset amount. Here, offsetting the dead-time interval DT1 or DT2 by a positive offset amount means that, compared with charging, the first dead-time interval DT1 during discharging is at an earlier time point, or compared with charging, the second dead-time interval DT2 during discharging is at a later time point.

[0107] The controller 120 may calculate the charge-discharge efficiency Eff_cur after the dead-time offset (step S140). According to an embodiment, the processor 125 may calculate the charge-discharge efficiency Eff_cur based on the ratio of the input power to the output power of the converter 110. The processor 125 may store the calculated charge-discharge efficiency Eff_cur after the dead-time offset in the memory 123.

[0108] The charge-discharge efficiency Eff_cur after the dead-time offset may be calculated in the same manner as the charge-discharge efficiency Eff_pre before the dead-time offset.

[0109] The controller 120 may determine whether the difference Eff_cur - Eff_pre between the charge-discharge efficiencies before and after the dead-time offset is equal to or greater than a first value K1 (step S150). According to an embodiment, the processor 125 may read the charge-discharge efficiencies Eff_pre, Eff_cur stored in the memory 123 and calculate the difference between them to determine whether the difference Eff_cur - Eff_pre between the charge-discharge efficiencies is equal to or greater than the first value K1. In this case, the first value K1 may be a positive number.

[0110] If the difference Eff_cur - Eff_pre between the charge-discharge efficiencies is equal to or greater than a first value K1 (YES in step S150), the controller 120 may store the charge-discharge efficiency Eff_cur after the dead time offset as the charge-discharge efficiency Eff_pre before the dead time offset (step S160), and may perform the dead time offset again (step S130).

[0111] That is, the difference Eff_cur - Eff_pre between the charge-discharge efficiencies being equal to or greater than the first value K1 means that the charge-discharge efficiency has been improved according to the dead time offset. Therefore, the controller 120 may perform the dead time offset again (step S130) to further improve the charge-discharge efficiency.

[0112] If the difference Eff_cur - Eff_pre between the charge-discharge efficiencies is less than the first value K1 (NO in step S150), the controller 120 may determine whether the difference Eff_cur - Eff_pre between the charge-discharge efficiencies before and after the dead time offset is equal to or less than a second value K2 (step S170). In this case, the second value K2 may be negative. For example, the second value K2 is the additive inverse of the first value K1 (i.e., -K1).

[0113] If the difference Eff_cur - Eff_pre between the charge-discharge efficiencies is equal to or less than the second value K2 (YES in step S170), the processor 125 may store the charge-discharge efficiency Eff_cur after the dead time offset as the charge-discharge efficiency Eff_pre before the dead time offset (step S180), and perform the dead time offset again (step S190). In this case, the controller 120 may offset the dead time interval DT1 or DT2 by a negative offset amount. Here, offsetting the dead time interval DT1 or DT2 by a negative offset amount means that, compared with charging, the first dead time interval DT1 during discharging is at a later time point, or compared with charging, the second dead time interval DT2 during discharging is at an earlier time point.

[0114] That is, the difference Eff_cur - Eff_pre between the charge-discharge efficiencies being equal to or less than the second value K2 means that the charge-discharge efficiency has deteriorated according to the dead time offset. Therefore, the controller 120 performs a dead time offset in the direction opposite to the previously performed dead time offset, thereby allowing the deteriorated charge-discharge efficiency to be restored through the dead time offset.

[0115] If the difference Eff_cur - Eff_pre between the charge-discharge efficiencies is greater than the second value K2 (NO in step S170), the controller 120 may end the dead time offset.

[0116] According to the referenceFigure 8 According to the method described, the controller 120 can determine the optimal dead-time offset for improving the discharge efficiency of the converter 110.

[0117] Figure 9 A converter showing an embodiment of the present invention. Compared with Figure 3 that, Figure 9 the converter 110A of Figure 3 has the difference that the current sensor 117 of the converter 110 of

[0118] is replaced by a voltage sensor 118, and the controller 120A has the difference of using the measurement result VSEN output from the voltage sensor 118 to judge the charging or discharging of the battery 300. Figure 9 Referring to

[0119] , the voltage sensor 118 can measure the current voltage of the battery 300 and generate a measurement result VSEN. The measurement result VSEN can be transmitted to the controller 120A.

[0120] The controller 120A can use the measurement result VSEN generated by the voltage sensor 118 to judge whether the battery 300 is in a charging state or a discharging state. According to an embodiment, the controller 120A can periodically receive the measurement result VSEN from the voltage sensor 118, judge whether the voltage of the battery 300 increases or decreases based on the received measurement result VSEN, and thus can judge whether the battery 300 is in a charging state or a discharging state. Figures 1 to 8 The controller 120A can judge whether the battery 300 is charging or discharging according to the measurement result of the voltage sensor 118, and output switching signals Qa to Qf corresponding to the conditions of each battery 300 according to the judgment result. The operation of the controller 120A to output the switching signals Qa to Qf according to whether the battery 300 is charging or discharging is the same as the operation and principle of the controller 120 described with reference to

[0121] As described above, the preferred embodiments of the present invention have been described. The present invention can be deformed into various forms, and as long as it is an ordinary technician in the technical field to which the present invention belongs, various deformation examples and modification examples can be implemented without exceeding the scope of the invention claimed by the present invention.

Claims

1. A charger / discharger for charging and discharging a battery, characterized in that, the charger / discharger includes an inverter, the inverter includes: a transformer for transferring power between a power supply unit and the battery; a first switching circuit for forming a current path between the power supply unit and the primary winding of the transformer within a first transfer interval according to a switching operation; and a second switching circuit for forming a current path between the battery and the secondary winding of the transformer within a second transfer interval according to a switching operation, the first switching circuit has a dead time interval in which no circuit path is formed between the power supply unit and the primary winding of the transformer, the inverter operates in such a way that the length of the overlapping portion between the dead time interval and the second transfer interval during battery discharge is less than that during battery charging.

2. The charger according to claim 1, characterized in that, The first switching circuit is a full-bridge circuit.

3. The charger according to claim 2, wherein The first switching circuit includes: a first switch pair connected between the power supply unit and the primary winding of the transformer, operating complementarily; and a second switch pair connected between the power supply unit and the primary winding of the transformer, operating complementarily.

4. The charger according to claim 3, characterized in that, The dead time interval is an interval in which one of the first switch pair or the second switch pair is turned off.

5. The charger according to claim 1, wherein, The second switching circuit includes two switches, one end of which is connected to the secondary winding of the transformer and the other end of which is connected to the battery.

6. The charger according to claim 5, characterized in that, The second transfer interval is an interval in which one of the two switches is turned off.

7. The charger according to claim 1, wherein The inverter operates in such a way that there is no length of the overlapping portion between the dead time interval and the second transfer interval during battery discharge.

8. The charger according to claim 1, characterized in that, The charger / discharger further includes a controller for generating a switching signal for controlling the switching operations of the first switching circuit and the second switching circuit.

9. The charger / discharger according to claim 8, characterized in that, the controller determines whether the battery is in a charging state or a discharging state, and adjusts the output time of the switching signal according to whether the battery is charging or discharging.

10. The charger according to claim 9, characterized in that, The controller outputs the switching signal so that the output time of the switching signal during battery charging is different from the output time of the switching signal during battery discharge.

11. The charger according to claim 9, characterized in that, The controller outputs the switching signal for making the length of the overlapping portion between the dead time interval and the second transfer interval of the inverter during battery discharge less than that during battery charging.

12. The charger according to claim 11, characterized in that, The controller outputs the switching signal for making the length of the overlapping portion between the dead time interval and the second transfer interval during battery discharge non-existent.

13. The charger according to claim 9, characterized in that, The controller outputs the switching signal for making the position of the dead time interval during battery discharge offset relative to the position of the dead time interval during charging.

14. The charger according to claim 13, characterized in that, The controller calculates the difference in the charge / discharge efficiency of the battery, determines the degree of offset of the position of the dead time interval during battery discharge according to the charge / discharge efficiency, and outputs the switching signal according to the determined degree of offset.

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