KR102529433B1 - Battery charger and discharger for charging and discharging battery - Google Patents

Abstract

The charging/discharging machine is started. The charger/discharger includes a bi-directional converter, wherein the bi-directional converter forms a current path between the power supply unit and the primary winding of the transformer during a first transmission section according to a transformer configured to transfer power between the power supply unit and the battery, and a switching operation. The configured first switching circuit includes a second switching circuit configured to form a current path between the secondary side winding of the transformer and the battery during a second transmission period according to a switching operation, the first switching circuit comprising: a power supply unit and a transformer; has a dead time period in which a current path is not formed between the primary windings of the bidirectional converter, when the battery is discharged, the length of the overlapping portion between the dead time period and the second transmission period is longer than when charging work in short

Description

Charging and discharging device for battery charging and discharging {BATTERY CHARGER AND DISCHARGER FOR CHARGING AND DISCHARGING BATTERY}

The present invention relates to a charger/discharger for charging/discharging a battery.

A secondary battery is a battery that can be repeatedly discharged and charged and used repeatedly, and is used in various electronic products. In particular, recently, it has been widely used in portable electronic devices such as mobile devices and smart watches, and its usage is gradually increasing with the increase in the spread of electric vehicles.

A secondary battery may be manufactured in the form of a package including a plurality of battery cells. A secondary battery manufactured in a factory or the like may not be shipped immediately, but may be shipped after a chemical conversion process. The formation process is a process that activates the secondary battery so that it can be used normally.

During the formation process, there is a formation process in which charging and discharging of the secondary battery is repeated. During this formation process, the battery is continuously charged and discharged using a bi-directional converter. At this time, the better the efficiency in charging and discharging the battery, the better the energy efficiency during the entire formation process.

An object of the present invention is to provide a charger/discharger for improving a difference between efficiency during charging and discharging of a battery of a bidirectional converter included in the charger/discharger.

An object of the present invention is to provide a charger/discharger capable of improving efficiency reduction during battery discharge of a bidirectional converter by adjusting positions of dead time intervals of switches of a primary side switching circuit of a bidirectional converter of the charger/discharger.

A charger/discharger according to embodiments of the present invention includes a bi-directional converter, and the bi-directional converter includes a transformer configured to transfer power between a power supply unit and a battery, and a primary side winding of the power supply unit and the transformer during a first transmission section according to a switching operation. a first switching circuit configured to form a current path between the battery and the secondary winding of the transformer during a second transmission period according to a switching operation; The switching circuit has a dead time period in which a current path is not formed between the power supply unit and the primary winding of the transformer, and the bidirectional converter has an overlapping portion between the dead time period and the second transmission period when the battery is discharged. It operates so that the length of is shorter than when charging.

The charger and discharger according to the embodiments of the present invention has an effect of improving the difference between the efficiency of charging and discharging the battery of the bidirectional converter included in the charger and discharger.

The charger/discharger according to embodiments of the present invention has an effect of improving efficiency reduction during battery discharge of the bidirectional converter by adjusting the positions of the dead time intervals of the switches of the primary side switching circuit of the bidirectional converter of the charger/discharger.

1 shows a battery charging/discharging system according to embodiments of the present invention.
2 shows a controller according to embodiments of the present invention.
3 shows a converter according to embodiments of the present invention.
4 to 6 are diagrams for explaining the operation of a converter according to embodiments of the present invention.
7 shows switch signals output to a converter during discharging according to embodiments of the present invention.

In order to clearly describe the present invention, parts irrelevant to the description are omitted, and the same reference numerals are assigned to the same or similar components throughout the specification.

Although not defined differently, all terms including technical terms and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. Terms defined in commonly used dictionaries are additionally interpreted as having meanings consistent with related technical literature and currently disclosed content, and are not interpreted in ideal or very formal meanings unless defined.

Hereinafter, with reference to the accompanying drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein.

1 shows a battery charging/discharging system according to embodiments of the present invention. Referring to FIG. 1 , a battery charging/discharging system 10 may include a charger/discharger 100 , a power supply unit 200 and a battery 300 .

The charger/discharger 100 is connected to the power source 200 and the battery 300 to charge and discharge the battery 300 .

The charger/discharger 100 may include a bidirectional converter (hereinafter referred to as converter 110) and a controller 120.

The converter 110 charges the battery 300 using power (or voltage/current) delivered from the power supply unit 200, or converts power (or voltage/current) delivered from the battery 300 to the power supply unit 200. ), the battery 300 may be discharged. Meanwhile, when the battery 300 is discharged, power transmitted from the battery 300 may be transmitted to the ground connected to the power supply unit 200 . According to embodiments, the converter 110 may convert power delivered from the power supply unit 200 and deliver it to the battery 300, and may also convert power delivered from the battery 300 and deliver the converted power to the power supply unit 200. there is.

The converter 110 includes a plurality of switches and a transformer, and may transfer power from the power supply unit 200 to the battery 300 or from the battery 300 to the power supply unit 200 according to switching operations of the switches. there is. For example, the converter 110 may be a phase-shift full bridge converter, but is not limited thereto.

The controller 120 may control the converter 110 . According to example embodiments, the controller 120 may generate a switch signal for controlling switching of switches included in the converter 110 . At this time, the switch signal may be plural.

The power supply unit 200 may transfer input power to the charger/discharger 100 . According to embodiments, the power supply unit 200 may transmit DC power to the charger/discharger 100, but embodiments of the present invention are not limited thereto. Also, the power supply unit 200 may receive discharge power of the battery 300 transmitted from the charger/discharger 100 . For example, the power supply unit 200 may output discharge power of the battery 300 through a ground terminal.

The battery 300 may be a device capable of storing or supplying electrical energy. According to embodiments, the battery 300 may be a secondary battery capable of repeatedly charging and discharging. For example, the battery 300 includes a lead-acid battery, a Ni-Cd battery, a Ni-MH battery, a Li-ion battery, and an electric battery. It may be a solid-state battery, but embodiments of the present invention are not limited thereto.

The battery 300 includes a battery cell including a cathode, an anode, an electrolyte and a separator, a battery module including a plurality of battery cells, or a plurality of batteries. It may collectively refer to a battery pack including modules.

2 shows a controller according to embodiments of the present invention. Referring to FIG. 2 , the controller 120 may include a switch signal output circuit 121 , a memory 123 and a processor 125 .

The switch signal output circuit 121 may output a switch signal for controlling the converter 110 . According to embodiments, the switch signal output circuit 121 may generate a switch signal for controlling switches included in the converter 110 and output the generated switch signal to the converter 110 . For example, the switch signal output circuit 121 may output a charge switch signal for charging the battery 300 and a discharge switch signal for discharging the battery 300 . That is, in the following specification, the charge switch signal and the discharge switch signal are collectively referred to as a switch signal.

According to example embodiments, the switch signal output circuit 121 may generate a switch signal using offset information stored in the memory 123 and a reference clock signal. For example, the switch signal output circuit 121 may generate charge switch signals based on the first offset information stored in the first space of the memory 123, and the second offset stored in the second space of the memory 123. Based on the information, discharge switch signals may be generated.

According to embodiments, the switch signal output circuit 121 may generate a switch signal for controlling the converter 110 through pulse width modulation (PWM). That is, the switch signal output circuit 121 may control the output power of the converter 110 by adjusting the duty cycle of the switch signal output to the converter 110 .

The memory 123 may store data necessary for the operation of the controller 120 . According to example embodiments, the memory 123 may store data used to generate a control signal for controlling the converter 110 . Also, the memory 123 may store information related to a charge/discharge schedule for the battery 300 of the charger/discharger 100 . Also, the memory 123 may store information about the state (voltage, current, temperature, etc.) of the battery 300 .

The processor 125 may control the overall operation of the controller 120 . According to example embodiments, the processor 125 may control the operation of the controller 120 by controlling the switch signal output circuit 121 and the memory 123 .

For example, the processor 125 is an integrated circuit having an arithmetic processing function, such as a central processing unit (CPU), a micro controller unit (MCU), a graphical processing unit (GPU), an application specific integrated circuit (ASIC), and an FPGA. It may be a field programmable gate array (field programmable gate array) or an application processor (AP), but embodiments of the present invention are not limited thereto.

The processor 125 may generate a control command to cause the switch signal output circuit 121 to output a switch signal. The switch signal output circuit 121 may generate a switch signal by reading offset information from the memory 123 in response to a control command.

The processor 125 may control the switch signal output circuit 121 so that the switch signal output circuit 121 outputs different switch signals according to the charge/discharge state of the battery 300 .

For example, when the battery 300 is being charged, the processor 125 may output a first control command to the switch signal output circuit 121, and the switch signal output circuit 121 responds to the first control command, Charge switch signals may be output to the converter 110 . At this time, the switch signal output circuit 121 may generate charge switch signals in response to the first control command.

For example, when the battery 300 is being discharged, the processor 125 may output a second control command to the switch signal output circuit 121, and the switch signal output circuit 121 responds to the second control command, Discharge switch signals may be output to the converter 110 . At this time, the switch signal output circuit 121 may generate discharge switch signals in response to the second control command.

The switch signal output circuit 121 according to embodiments of the present invention may output switch signals having 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 charge switch signal output during charging and the discharge switch signal output during discharging may have different characteristics. Accordingly, there is an effect that the charging and discharging efficiency of the converter 110 can be improved.

3 shows a converter according to embodiments of the present invention. Referring to FIG. 3 , the converter 110 may include a transformer 111 , a first switching circuit 113 and a second switching circuit 115 . The converter 110 may be connected between the power supply unit 200 and the battery 300 .

Meanwhile, additionally, the converter 110 further includes elements (inductors L1 and L2 and capacitor C) disposed between the power supply unit 200 and the transformer 111 and between the transformer 111 and the battery 300. It may be included, but it is not required.

The transformer 111 may be configured to transfer power between the power supply unit 200 and the battery 300 . According to embodiments, the transformer 111 converts the power of the primary side circuit (eg, the power supply unit 200 side circuit) by a predetermined multiple and transfers it to the secondary side circuit (eg, the battery 300 side circuit), or the secondary side The power of the circuit may be converted into a reciprocal of the predetermined multiple and transmitted to the primary side circuit. For example, the transformer 111 may include a primary-side winding corresponding to a primary-side circuit and a secondary-side winding corresponding to a secondary-side circuit.

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

The second switching circuit 115 may be connected between the battery 300 and the transformer 111 . According to example embodiments, 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 a switching operation. That is, current may flow between the secondary winding of the battery 300 and the transformer 111 according to the switching operation of the second switching circuit 115 .

That is, according to the operation of the first switching circuit 113 and the second switching circuit 115, the converter 110 according to the embodiments of the present invention can convert the power of the power supply unit 200 to the battery 300 and deliver it. In addition, power of the battery 300 may be converted to the power supply unit 200 and transmitted.

The first switching circuit 113 may include a plurality of switches SWa, SWb, SWc, and SWd. Each of the plurality of switches SWa, SWb, SWc, and SWd may include a switching element (eg, a transistor or a diode). Additionally, each of the plurality of switches SWa, SWb, SWc, and SWd may further include an energy storage device such as a capacitor.

The plurality of switches SWa, SWb, SWc, and SWd may be turned on and off in response to each of the input switch signals Qa, Qb, Qc, and Qd, and the plurality of switches SWa, SWb , SWc and SWd), a current path may be formed between the power supply unit 200 and the primary winding of the transformer 111 according to turn-on and turn-off.

The first switch SWa is connected to 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 switch signal Qa. The second switch SWb is connected to the other end of the power supply unit 200 and one end of the primary side winding of the transformer 111, and may operate in response to the second switch signal Qb.

In order to prevent a short in the circuit, the first switch SWa and the second switch SWb may operate complementary to each other. That is, the turn-on time (or turn-off time) of the first switch SWa and the turn-on time (or turn-off time) of the second switch SWb may not overlap each other. The first switch SWa and the second switch SWb may be referred to as front switches.

The third switch SWc is connected to one end of the power supply unit 200 and the other end of the primary side winding of the transformer 111, and may operate in response to the third switch signal Qc. The fourth switch SWd is connected to the other end of the power supply unit 200 and the other end of the primary side winding of the transformer 111, and may operate in response to the fourth switch signal Qd.

In order to prevent a short in the circuit, the third switch SWc and the fourth switch SWd may operate complementary to each other. That is, the turn-on time (or turn-off time) of the third switch SWc and the turn-on time (or turn-off time) of the fourth switch SWd may not overlap each other. The third switch SWc and the fourth switch SWd may be referred to as rear switches.

The first switching circuit 113 may form a current path between the power supply unit 200 and the primary winding of the transformer 111 during the first transmission period. For example, the first transmission period includes a period in which the first switch (SWa) and the fourth switch (SWd) are turned on, and a period in which the second switch (SWb) and the third switch (SWc) are turned on. can do.

The second switching circuit 115 may include a plurality of switches SWe and Swf. Each of the plurality of switches SWe and Swf may include a switching element (eg, a transistor or a diode). Additionally, each of the plurality of switches SWe and Swf may further include an energy storage device such as a capacitor.

The plurality of switches SWe and Swf may be turned on and turned off in response to each of the input switch signals Qe and Qf, and the plurality of switches SWe and Swf may be turned on and turned on. -A current path may be formed between the battery 300 and the secondary winding of the transformer 111 according to the off state.

The fifth switch SWe is connected to one end of the battery and one end of the secondary side winding of the transformer 111, and may operate in response to the fifth switch signal Qe. According to embodiments, one end of the fifth switch SWe may be connected to one end of the secondary winding of the transformer 111 and the other end of the first inductor L1 having one end connected to the other end of the battery 300.

The sixth switch SWf is connected to one end of the battery and the other end of the secondary winding of the transformer 111, and may operate in response to the sixth switch signal Qf. According to embodiments, one end of the sixth switch SWf may be connected to the other end of the secondary winding of the transformer 111 and the other end of the second inductor L2 having one end connected to the other end of the battery 300.

The second switching circuit 115 may form a current path between the power supply unit 200 and the secondary winding of the transformer 111 during the second transmission period. For example, the second transmission period may include a period in which at least one of the fifth switch SWe and the sixth switch SWf is turned off.

4 to 6 are diagrams for explaining the operation of a converter according to embodiments of the present invention.

4 to 6, as the switches SWa to SWf of the converter 110 are turned on and off, a current path is formed between the power supply unit 200 and the battery 300, Electrical energy transfer between 200 and battery 300 becomes possible. At this time, the charging and discharging of the battery 300 may be determined according to the magnitude of the current voltage of the battery 300 and the output voltage of the converter 110 .

Referring to FIG. 4 , the controller 120 may output switch signals Qa to Qf for controlling the converter 110 . According to embodiments, the controller 120 stores the charge/discharge schedule information for the battery 300 and the current state of the battery 300 (eg, voltage, state of health (SOH), state of charge (SOC)). Thus, a switch signal for controlling the converter 110 may be output. For example, the switch signals Qa to Qf shown in FIG. 4 may be charge switch signals.

According to embodiments, the switch signals Qa to Qf may be PWM signals in the form of pulses having regular cycles. Each of the switches SWa to SWf may be turned on in response to high level switch signals Qa to Qf and turned off in response to low level switch signals Qa to Qf. It is not limited to this.

According to example embodiments, the duty ratio of the switch signals Qa, Qb, Qc, and Qd may be 50%. Meanwhile, the magnitude of the output voltage (voltage across the primary winding/secondary winding) of the converter 110 is based on the overlapping width between the high section of the first switch signal Qa and the high section of the fourth switch signal Qd. can do.

For complementary operations of the previous switches SWa and SWb, the high period of the first switch signal Qa and the high period of the second switch signal Qb may not overlap. For stable complementary operation of the previous switches SWa and SWb, a first dead time period DT1 may exist between the high period of the first switch signal Qa and the high period of the second switch signal Qb. there is. That is, the controller 120 may output the rising edge of the second switch signal Qb after the first dead time from the time of outputting the falling edge of the first switch signal Qa.

Similarly, for the complementary operation of the subsequent switches SWc and SWd, the high period of the third switch signal Qc and the high period of the fourth switch signal Qd may not overlap. A second dead time period DT2 may exist between the high period of the third switch signal Qc and the high period of the fourth switch signal Qd. That is, the controller 120 may output the rising edge of the fourth switch signal Qd after the second dead time from the time of outputting the falling edge of the third switch signal Qc.

On the other hand, during the dead time period (DT1 and DT2) of the first switching circuit 113, a pair of switches (SWa and SWb) operating complementaryly are all turned off, and the other pair operating complementaryly Since only one of the switches SWc and SWd of is turned on, a current path of the first switching circuit 113 is not formed.

Referring to FIG. 5 , the operation of the converter in the interval [t0, t3] of FIG. 4 is shown.

In the interval [t0, t1], the switches SWa and SWb are all turned off. That is, the interval [t0, t1] is the first dead time interval DT1. In the period [t0, t1], energy is not transferred by the transformer 111.

In the period [t1, t2], the second switch SWb and the third switch SWc are turned on in response to the switch signals. According to the complementary operation, the first switch SWa and the fourth switch SWd are turned off. Also, the sixth switch SWf is turned off, and according to the complementary operation, the fifth switch SWe is turned on. In the period [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 delivered to the secondary winding of the transformer 111 is delivered to the battery 300 via the second inductor L2. That is, in the period [t1, t2], energy is transferred by the transformer 111, and the battery 300 is charged (or discharged).

In the period [t2, t3], both the switches SWc and SWd are turned off. That is, the period [t2, t3] is the second dead time period DT2, and energy is not transferred by the transformer 111.

Referring to FIG. 6 , the operation of the converter in the section [t4, t7] of FIG. 4 is shown.

In the interval [t4, t5], the switches SWa and SWb are all turned off. That is, the interval [t4, t5] is the first dead time interval DT1. In the period [t4, t5], energy is not transferred by the transformer 111.

In the period [t5, t6], the first switch SWa and the fourth switch SWd are turned on in response to the switch signals. According to the complementary operation, the second switch SWb and the third switch SWc are turned off. Also, the fifth switch SWe is turned off, and according to the complementary operation, the sixth switch SWf is turned on. In the period [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 and transfers it to the secondary winding. The converted power delivered to the secondary winding of the transformer 111 is delivered to the battery 300 via the second inductor L2. That is, in the period [t5, t6], energy is transferred by the transformer 111, and the battery 300 is charged (or discharged).

In the period [t6, t7], both switches SWc and SWd are turned off. That is, the period [t6, t7] is the second dead time period DT2, and energy is not transferred by the transformer 111.

As described above, in the section E where the first transmission section W1 of the first switching circuit 113 and the second section W2 of the second switching circuit 115 overlap, the power supply unit 200 and the battery 300 ), energy transfer (ie, charging) may be made, and the battery 300 may be charged or discharged in this section.

Meanwhile, referring to FIG. 4 again, the dead time period DT1 or DT2 of the first switching circuit 113 and the second transmission period W2 of the second switching circuit 115 may at least partially overlap. In this case, due to the asymmetry of the first switching circuit 113 and the second switching circuit 115, a phenomenon in which the discharging efficiency of the battery 300 is lower than the charging efficiency may occur.

Accordingly, in the charger/discharger 100 according to the embodiments of the present invention, the dead time period (DT1 or DT2) of the switches of the first switching circuit 113 and the second transmission period of the second switching circuit 115 overlap each other. By making the length of the portion relatively smaller during discharging than during charging, there is an effect of relatively increasing efficiency during discharging of the battery 300 .

At this time, making the overlapping portion of the dead time period (DT1 or DT2) of the switches of the first switching circuit 113 and the second transmission period of the second switching circuit 115 smaller during discharging than during charging is referred to as 'dead'. This is called time interval shifting.

7 shows switch signals output to a converter during discharging according to embodiments of the present invention. The switch signals Qa to Qf shown in FIG. 7 may be signals output by the controller 120 when the battery 300 is discharged. Meanwhile, when the battery 300 is charged, the controller 120 may output switch signals Qa to Qf shown in FIG. 4 .

4, the controller 120 determines that the length of the overlapping portion between the dead time period (DT1 or DT2) of the first switching circuit 113 and the second transfer period of the second switching circuit 115 is Switch signals Qa to Qf may be output such that they become smaller during discharge than during discharge. For example, the controller 120 may output different switching signals Qa to Qd to the first switching circuit 113 during charging and discharging.

The controller 120 may perform dead time period shifting while maintaining the charging/discharging voltage of the battery 300 (or the output voltage of the charger/discharger 100). That is, according to embodiments of the present invention, even if the current voltage of the battery 300 is the same, depending on whether the battery 300 is charged or discharged, the dead time period of the switches (DT1 or DT2) and the second switching circuit ( Switch signals Qa to Qf for controlling the converter 110 may be output so that the overlapping portions of the second transfer intervals of 115 are different from each other.

According to embodiments, the controller 120 maintains the same duty ratio and length of the duty cycle of the switch signals Qa to Qd when the battery 300 is charged and discharged, but the dead of the switch signals Qa to Qd Dead time interval shifting can be performed by adjusting only the positions of the time intervals DT1 or DT2. For example, even if the dead time interval shifting is performed, the length of the dead time interval DT1 or DT2 itself may not change.

According to embodiments, the controller 120 adjusts the relative positions of the switch signals Qa to Qd of the first switching circuit 113 with respect to the switch signals Qe or Qf of the second switching circuit 115. , dead time interval shifting can be performed.

According to example embodiments, the controller 120 may perform dead time period shifting by applying different offsets to the reference clock signal during charging and discharging of the battery 300 .

According to the shifting of the dead time interval, efficiency of the battery 300 of the charger/discharger 100 can be improved.

For example, in the case of FIG. 4 , the battery 300 is the secondary side of the transformer 111 in the portion where the dead time intervals (DT1 or DT2) of the switches and the second transfer interval of the second switching circuit 115 overlap each other. Although a current path is formed with the winding, the primary side winding of the transformer 111 does not form a current path with the power supply unit 200, so the discharge efficiency of the battery 300 is reduced. For example, the energy transfer period E is shorter than the second transfer period W2 of the second switching circuit 115 by the first dead time period DT1.

On the other hand, in the case of FIG. 7, since there is no overlap between the dead time intervals (DT1 or DT2) of the switches and the second transfer interval of the second switching circuit 115, the battery 300 and the transformer 111 Since the current path is formed between the power supply unit 200 and the primary winding of the transformer 111 together with the formation of the current path between the secondary windings, the discharge efficiency of the battery 300 is not reduced. . For example, since the first dead time period DT1 is located outside the second transfer period W2, the energy transfer period E' coincides with the second transfer period W2.

Although the preferred embodiment according to the present invention has been described above, it can be modified in various forms, and those skilled in the art can make various modifications and variations without departing from the scope of the claims of the present invention. It is understood that this can be done.

10: charge/discharge system 100: charge/discharge machine
110: bidirectional converter 120: controller
121 switch signal output circuit 123 memory
125: processor 200: power unit
300: battery

Claims (10)

A charger/discharger connected between a power supply unit and a battery to charge and discharge a battery, wherein the charger/discharger includes a bi-directional converter,
The bi-directional converter,
a transformer configured to transfer power between the power source and the battery;
a first switching circuit configured to form a current path between the power supply unit and the primary winding of the transformer during a first transmission period according to a switching operation;
A second switching circuit configured to form a current path between the battery and the secondary winding of the transformer during a second transfer period according to a switching operation,
The first switching circuit has a dead time period in which a current path is not formed between the power supply unit and the primary winding of the transformer;
The bi-directional converter operates such that when the battery is discharged, a length of an overlapping portion between the dead time period and the second transfer period is shorter than when the battery is charged.
charger and discharger. The method of claim 1, wherein the first switching circuit,
As a full bridge circuit,
charger and discharger. The method of claim 2, wherein the first switching circuit,
a first switch pair connected between the power supply unit and the primary side winding of the transformer and operating complementary to each other; and
A second switch pair connected between the power supply unit and the primary winding of the transformer and operating complementary to each other,
charger and discharger. The method of claim 3, wherein the dead time interval,
A period in which any one switch pair of the first switch pair or the second switch pair is turned off,
charger and discharger. The method of claim 1, wherein the second switching circuit,
Including two switches, one end of which is connected to the secondary winding of the transformer and the other end is connected to the battery,
charger and discharger. The method of claim 5, wherein the second transmission section,
A period in which one of the two switches is turned off,
charger and discharger. The method of claim 1, wherein the charger and discharger,
Further comprising a controller configured to generate switch signals for controlling switching operations of the first switching circuit and the second switching circuit.
charger and discharger. The method of claim 7, wherein the controller,
determine whether the battery is charging or discharging based on information related to the state of the battery;
When the battery is being discharged, by adjusting the output timing of the switch signals, the length of the overlapping portion between the dead time period and the second transmission period of the bi-directional converter is controlled to be shorter than during charging,
charger and discharger. The method of claim 7, wherein the controller,
When the battery is being discharged, controlling the position of the dead time interval by adjusting the output timing of the switch signals,
charger and discharger. The method of claim 1, wherein the bidirectional converter,
Operating so that there is no length of an overlapping portion between the dead time period and the second transmission period when the battery is discharged.
charger and discharger.

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