Bidirectional DC-DC buck-boost circuit

Abstract

The utility model relates to the technical field of electric tools, and discloses a bidirectional DC-DC buck-boost circuit capable of realizing mutual charging / discharging of battery packs and having high reliability, which comprises a first interface module (110), a second interface module (120), a switching power module (130) and a buck-boost master control module (140), the control pulse is used for controlling boost / buck conversion of the switching power module (130) so as to control boost / buck of the battery pack, thereby realizing bidirectional charging / discharging.

Description

Technical Field

[0001] The utility model relates to the technical field of electric tools, and more specifically to a bidirectional DC-DC step-up and step-down circuit. Background Art

[0002] A circuit that converts the input DC voltage into the DC voltage required by the circuit is called a DC-DC power supply circuit. Currently, there are only unidirectional DC-DC conversion circuits on the market, that is, the input can only be used for input, the output can only be used for output, the current direction is fixed, and the reverse charging function is not possible. Its power supply function is single, which limits its use scenarios.

[0003] Therefore, providing a DC-DC conversion circuit that can realize mutual charging / discharging between battery packs has become a technical problem that technical personnel in this field urgently need to solve. Utility Model Content

[0004] The technical problem to be solved by the present invention is that, in view of the defects of the above-mentioned unidirectional DC-DC conversion circuit in the prior art, that is, the input can only be used as input, the output can only be used as output, the current direction is fixed, and the reverse charging function is not possible, a bidirectional DC-DC buck-boost circuit is provided which can realize mutual charging / discharging of battery packs and has high reliability.

[0005] The technical solution adopted by the utility model to solve the technical problem is to construct a bidirectional DC-DC step-up and step-down circuit, which has:

[0006] A first interface module is disposed in the buck-boost circuit, one end of which is connected to a port of a battery pack;

[0007] A second interface module, one end of which is connected to a port of another battery pack;

[0008] a switch power module, a first end of which is connected to the other end of the first interface module,

[0009] The second end of the switching power module is connected to the other end of the second interface module;

[0010] A voltage boost / buck main control module, whose signal output terminal is connected to the signal input terminal of the switch power module, and the switch power module is used to receive the control pulse output by the voltage boost / buck main control module,

[0011] The control pulse is used to control the step-up / step-down conversion of the switching power module to control the step-up / step-down of the battery pack to achieve bidirectional charging / discharging.

[0012] In some embodiments, the switch power module includes at least a first MOS transistor and a second MOS transistor.

[0013] The gate of the first MOS tube is connected to the first signal output terminal of the boost / buck main control module, and is used to receive a first control pulse.

[0014] The gate of the second MOS tube is connected to the second signal output terminal of the boost / buck main control module for receiving a second control pulse.

[0015] The drain of the first MOS tube is connected to the source of the second MOS tube,

[0016] The drain of the second MOS tube is connected to one end of the second interface module through a second resistor.

[0017] The source of the first MOS tube is connected to the common end.

[0018] In some embodiments, the switch power module further includes a third MOS transistor and a fourth MOS transistor.

[0019] The gate of the third MOS tube is connected to the third signal output terminal of the boost / buck main control module, and is used to receive a third control pulse.

[0020] The gate of the fourth MOS tube is connected to the fourth signal output terminal of the boost / buck main control module, and is used to receive a fourth control pulse.

[0021] The drain of the third MOS tube is connected to the source of the fourth MOS tube,

[0022] The drain of the fourth MOS tube is connected to one end of the first interface module through a first resistor.

[0023] The source of the third MOS tube is connected to the common end.

[0024] In some embodiments, the switching power module further includes a first inductor.

[0025] One end of the first inductor is respectively connected to the drain of the first MOS tube, the source of the second MOS tube and a signal end of the boost / buck main control module.

[0026] The other end of the first inductor is respectively connected to the drain of the third MOS tube, the source of the fourth MOS tube and the other signal end of the boost / buck main control module.

[0027] In some embodiments, the voltage boost / voltage reduction main control module includes at least a main controller,

[0028] The first signal output terminal of the main controller is coupled to the gate of the first MOS tube, and is used to output the first control pulse.

[0029] The second signal output terminal of the main controller is coupled to the gate of the second MOS tube, and is used to output the second control pulse.

[0030] The third signal output terminal of the main controller is coupled to the gate of the third MOS tube, and is used to output the third control pulse.

[0031] The fourth signal output terminal of the main controller is coupled to the gate of the fourth MOS tube and is used for outputting the fourth control pulse.

[0032] In some embodiments, a signal terminal of the main controller is connected to one end of the first inductor.

[0033] The other signal end of the main controller is connected to the other end of the first inductor.

[0034] In some implementations, the first interface module includes a voltage divider circuit, one end of which is connected to a voltage feedback end of the main controller.

[0035] In some embodiments, the voltage divider circuit includes a first resistor and a second resistor connected in series.

[0036] The connection end of the first resistor and the second resistor is connected to the voltage feedback end of the main controller.

[0037] The bidirectional DC-DC buck-boost circuit described in the utility model includes a first interface module, a second interface module, a switch power module and a boost / buck main control module, wherein the boost / buck main control module is used to output a control pulse, and the control pulse is used to control the boost / buck conversion of the switch power module to control the boost / buck of the battery pack, thereby realizing bidirectional charging / discharging. Compared with the prior art, the boost / buck conversion of the switch power module is controlled by the control pulse output by the boost / buck main control module to realize bidirectional charging / discharging between battery packs, which can effectively solve the problem of the existing unidirectional DC-DC conversion circuit, that is, the input can only be used as input, the output can only be used as output, the current direction is fixed, and reverse charging is not possible. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0039] Figure 1 The utility model provides a circuit schematic diagram of an embodiment of a bidirectional DC-DC buck-boost circuit. DETAILED DESCRIPTION

[0040] In order to have a clearer understanding of the technical features, purposes and effects of the present utility model, the specific implementation methods of the present utility model are now described in detail with reference to the accompanying drawings.

[0041] like Figure 1 As shown, in the first embodiment of the bidirectional DC-DC buck-boost circuit of the present utility model, the bidirectional DC-DC buck-boost circuit 100 includes a first interface module 110, a second interface module 120, a switch power module 130 and a boost / buck main control module 140.

[0042] The first interface module 110 is used to connect to an external battery pack (corresponding to P1_B+).

[0043] The second interface module 120 is used to connect to another external battery pack (corresponding to P2_B+).

[0044] The switch power module 130 is used to step up or step down the voltage input from the battery pack (such as P1_B+ or P2_B+).

[0045] For example, when the voltage of the battery pack (corresponding to P1_B+) is higher than the voltage of the battery pack (corresponding to P2_B+), when the battery pack (corresponding to P1_B+) charges the battery pack (corresponding to P2_B+), the switching power module 130 works as a buck switch; or

[0046] When the voltage of the battery pack (corresponding to P1_B+) is lower than the voltage of the battery pack (corresponding to P2_B+), the boost switch works;

[0047] The boost / buck main control module 140 has the functions of control pulse, voltage feedback, and signal processing, wherein it outputs at least 4 control pulses to control the boost / buck working state of the switch power module 130;

[0048] Specifically, the first interface module 110 is configured in the buck-boost circuit, and one end thereof is connected to a port of a battery pack (corresponding to P1_B+). A battery pack (corresponding to P1_B+) can input a charging current through the first interface module 110 or output a charging current to a subsequent circuit;

[0049] Furthermore, one end of the second interface module 120 is connected to a port of another battery pack (corresponding to P2_B+), and the other battery pack (corresponding to P2_B+) can input a charging current through the second interface module 120 or output a charging current to a subsequent circuit;

[0050] Furthermore, the first end of the switching power module 130 is connected to the other end of the first interface module 110, and can receive the charging current output by a battery pack (corresponding to P1_B+) through the first interface module 110.

[0051] Or input charging current to a battery pack (corresponding to P1_B+);

[0052] The second end of the switch power module 130 is connected to the other end of the second interface module 120, and can receive the charging current output by another battery pack (corresponding to P2_B+) through the second interface module 120.

[0053] Or input charging current to another battery pack (corresponding to P2_B+);

[0054] Furthermore, the voltage increase / decrease main control module 140 is used to output multiple control pulse signals.

[0055] The output end of the voltage boost / buck main control module 140 is connected to the signal input end of the switch power module 130 respectively.

[0056] The switch power module 130 is used to receive the control pulse output by the voltage increase / decrease main control module 140.

[0057] The control pulse is used to control the step-up / step-down conversion of the switching power module 130 to control the step-up / step-down of the battery pack (corresponding to P1_B+ or P2_B+) to achieve bidirectional charging / discharging of the battery pack (corresponding to P1_B+ or P2_B+).

[0058] In some implementations, in order to ensure the reliability of the charging / discharging process, a first MOS transistor Q29 and a second MOS transistor Q39 may be provided in the switching power module 130, wherein the above MOS transistors are both selected as N-channel MOS transistors and both have the function of switches;

[0059] The gate of the first MOS tube Q29 is connected to the first signal output terminal of the boost / buck main control module 140 to receive the first control pulse.

[0060] The gate of the second MOS transistor Q39 is connected to the second signal output terminal of the boost / buck main control module 140 for receiving the second control pulse.

[0061] The drain of the first MOS tube Q29 is connected to the source of the second MOS tube Q39.

[0062] The drain of the second MOS transistor Q39 is connected to one end of the second interface module 120 through the second resistor RS2.

[0063] The source of the first MOS transistor Q29 is connected to the common terminal.

[0064] When the first control pulse is at a high level, the second control pulse is at a low level, the first MOS tube Q29 is turned on, and the second MOS tube Q39 is turned off.

[0065] When the second control pulse is at a high level, the first control pulse is at a low level, the second MOS transistor Q39 is turned on, and the first MOS transistor Q29 is turned off.

[0066] In some implementations, in order to ensure the reliability of the charging / discharging process, a third MOS transistor Q30 and a fourth MOS transistor Q38 may be provided in the switching power module 130, wherein the above MOS transistors are both selected as N-channel MOS transistors and both have the function of switches;

[0067] The gate of the third MOS tube Q30 is connected to the third signal output terminal of the boost / buck main control module 140 to receive the third control pulse.

[0068] The gate of the fourth MOS tube Q38 is connected to the fourth signal output terminal of the boost / buck main control module 140 to receive the fourth control pulse.

[0069] The drain of the third MOS tube Q30 is connected to the source of the fourth MOS tube Q38.

[0070] The drain of the fourth MOS tube Q38 is connected to one end of the first interface module 110 through the first resistor RS1.

[0071] The source of the third MOS transistor Q30 is connected to the common terminal.

[0072] When the first control pulse and the fourth control pulse are at high level, the second control pulse and the third control pulse are at low level, the first MOS tube Q29 and the fourth MOS tube Q38 are turned on, and the second MOS tube Q39 and the third MOS tube Q30 are turned off.

[0073] When the second control pulse and the third control pulse are at high level, the first control pulse and the fourth control pulse are at low level, the second MOS tube Q39 and the third MOS tube Q30 are turned on, and the first MOS tube Q29 and the fourth MOS tube Q38 are turned off.

[0074] In some embodiments, in order to ensure the reliability of the charging / discharging process, a first inductor L4 may be provided in the switching power module 130.

[0075] One end of the first inductor L4 is connected to the drain of the first MOS transistor Q29, the source of the second MOS transistor Q39 and a signal end of the boost / buck main control module 140 respectively.

[0076] The other end of the first inductor L4 is respectively connected to the drain of the third MOS transistor Q30 , the source of the fourth MOS transistor Q38 , and the other signal end of the boost / buck main control module 140 .

[0077] In some embodiments, the voltage boost / buck master control module 140 includes at least a master controller U1, which is used to output multiple control pulses;

[0078] The first signal output terminal (corresponding to pin 23) of the main controller U1 is connected to the gate of the first MOS tube Q29 through the nineteenth resistor 199, and is used to output the first control pulse.

[0079] The second signal output terminal (corresponding to pin 21) of the main controller U1 is connected to the gate of the second MOS tube Q39 through the eighteenth resistor 198, and is used to output the second control pulse.

[0080] The third signal output terminal (corresponding to pin 27) of the main controller U1 is connected to the gate of the third MOS tube Q30 through the sixteenth resistor 160, and is used to output the third control pulse.

[0081] The fourth signal output terminal (corresponding to pin 29) of the main controller U1 is connected to the gate of the fourth MOS transistor Q38 through the seventeenth resistor 157, and is used to output a fourth control pulse.

[0082] In some implementations, a signal terminal (corresponding to pin 22) of the main controller U1 is connected to one end of the first inductor L4.

[0083] Another signal terminal (corresponding to pin 28) of the main controller U1 is connected to the other end of the first inductor L4.

[0084] In some implementations, the first interface module 110 includes a voltage divider circuit, wherein one end of the voltage divider circuit is connected to a voltage feedback end (corresponding to pin 14) of the main controller U1.

[0085] The voltage divider circuit includes a first resistor R147 and a second resistor R150 connected in series.

[0086] The connection end of the first resistor R147 and the second resistor R150 is connected to the voltage feedback end (corresponding to pin 14) of the main controller U1. The voltage input from a battery pack (corresponding to P1_B+) is divided by the first resistor R147 and the second resistor R150, and then output to the voltage feedback end (corresponding to pin 14) of the main controller U1.

[0087] Its working principle is:

[0088] The DC-DC buck-boost circuit is used for bucking and boosting. When the input voltage is higher than the output voltage, the buck switch works; when the input voltage is lower than the output voltage, the boost switch works.

[0089] For example, when one battery pack (corresponding to P1_B+) charges another battery pack (corresponding to P2_B+),

[0090] When the voltage of one battery pack (corresponding to P1_B+) is higher than the voltage of another battery pack (corresponding to P2_B+), it works as a step-down switch.

[0091] Among them, the pin 23 of the main controller U1 provides a first control pulse signal to the first MOS tube Q29 through the nineteenth resistor 199 to control the switch state of the first MOS tube Q29;

[0092] Pin 21 of the main controller U1 provides a second control pulse signal to the second MOS tube Q39 through the eighteenth resistor 198 to control the switch state of the second MOS tube Q39;

[0093] Pin 27 of the main controller U1 provides a third control pulse signal to the third MOS tube Q30 through the sixteenth resistor 160 to control the switch state of the third MOS tube Q30;

[0094] Pin 29 of the main controller U1 provides a fourth control pulse signal to the fourth MOS tube Q38 through the seventeenth resistor 157 to control the switch state of the fourth MOS tube Q38;

[0095] Pin 8 of the main controller U1 is used as the midpoint detection circuit of the fourth MOS tube Q38 and the third MOS tube Q30.

[0096] The nineteenth capacitor C119 is a bootstrap circuit, providing a high start-up power supply for the fourth MOS tube Q38;

[0097] Pin 22 of the main controller U1 is used as the midpoint detection circuit of the second MOS tube Q39 and the first MOS tube Q29.

[0098] The twenty-third capacitor C123 is a bootstrap circuit, which provides a high start-up power supply for the second MOS tube Q39.

[0099] The charging current direction is: P1_B+→first resistor RS1→fourth MOS tube Q38_D-S pole→first inductor L4→second MOS tube Q39_D-S pole→second resistor RS2→P2_B+→SGND (right)→SGND (left),

[0100] In this process, the fourth MOS tube Q38 works at high frequency, and the third MOS tube Q30 does not work.

[0101] The second MOS tube Q39 is always turned on, and the first MOS tube Q29 plays the role of high-frequency switch freewheeling.

[0102] The first MOS tube Q29 and the fourth MOS tube Q38 work in a complementary manner;

[0103] When the voltage of one battery pack P1_B+ is lower than the voltage of another battery pack P2_B+, the boost switch works.

[0104] The charging current direction is divided into two paths. The first current direction is P1_B+→first resistor RS1→fourth MOS tube Q38_D-S pole→first inductor L4→second MOS tube Q39_D-S pole→second resistor RS2→P2_B+→SGND (right)→SGND (left).

[0105] During this process, the fourth MOS tube Q38 is always turned on, and the third MOS tube Q30 is not working.

[0106] The first MOS tube Q29 works as a high-frequency switch, and the second MOS tube Q39 acts as an upgrade diode for the high-frequency switch.

[0107] The first MOS transistor Q29 and the second MOS transistor Q39 are in high-frequency switching complementary operation;

[0108] The output voltage of the step-up / step-down circuit from left to right is sent to the 16th pin of the main controller U1 through the fifty-fourth resistor R154 and the twenty-third resistor R23 to output 21V.

[0109] The calculation formula is as follows: (the fifty-fourth resistor R154 / the twenty-third resistor R23+1)*1.2=(330 / 20+1)*1.2=21V;

[0110] The current is sampled through the second resistor RS2 and sent to the 17th and 18th pins of the main controller U1 through the 15th resistor R195, the 36th resistor R196, and the 20th capacitor C120. The output is adjusted to 8A current, which can meet the 20V / 8A charging characteristic from left to right.

[0111] Discharge process:

[0112] When the other battery pack P2_B+ discharges to the one battery pack P1_B+, when the voltage of the other battery pack P2_B+ is higher than the voltage of the one battery pack P1_B+, it is a step-down switch operation.

[0113] Charging current direction: P2_B+→second resistor RS2→second MOS tube Q39_D-S pole→first inductor L4→fourth MOS tube Q38_D-S pole→first resistor RS1→P1_B+→SGND (left)→SGND (right),

[0114] In this process, the second MOS tube Q39 works at a high frequency switch, the first MOS tube Q29 does not work, the fourth MOS tube Q38 is always turned on, and the third MOS tube Q30 works at a high frequency switch and plays a freewheeling role.

[0115] The third MOS tube Q30 and the second MOS tube Q39 work in a complementary manner.

[0116] When the voltage of another battery pack P2_B+ is lower than the voltage of one battery pack P1_B+, the boost switch is in operation.

[0117] Charging current direction: P2_B+→second resistor RS2→second MOS tube Q39_D-S pole→first inductor L4→fourth MOS tube Q38_D-S pole→first resistor RS1→P1_B+→SGND (left)→SGND (right),

[0118] During this process, the second MOS tube Q39 is always turned on, and the first MOS tube Q29 is not working.

[0119] The third MOS tube Q30 acts as a high-frequency switch, and the fourth MOS tube Q38 acts as an upgrade diode for the high-frequency switch;

[0120] The third MOS transistor Q30 and the fourth MOS transistor Q38 are in high-frequency switching complementary operation;

[0121] The output voltage of the step-up / step-down circuit from right to left is sent to the 14th pin of the main controller U1 by setting the first resistor R147 and the second resistor R150, and the output is about 22V.

[0122] The calculation formula is as follows: (first resistor R147 / second resistor R150+1)*2=(330 / 33+1)*2=22V,

[0123] The current is sampled through the first resistor RS1, and sent to pins 1 and 32 of the main controller U1 for detection through the fifty-eighth resistor R158, the fifty-ninth resistor R159, and the eighteenth capacitor C118, and the output is adjusted to 8A current, which satisfies the 20V / 8A charging characteristic from right to left.

[0124] The main controller U1 is used to drive the working state (on / off) of the four external power MOS tubes (Q38, Q30, Q39, Q29). " / CE" and "PSTOP" are the enable start switches. The main controller U1 always works normally.

[0125] Its working mode is connected to the main controller U1 by the network of "VCC, SCL, SDA, GND" in "CN1", and the host computer sends instructions to the register of the main controller U1 to control the direction of the charging current, that is, when "OTG=0" in the 0x09 register is set, it is charged from left to right, and when "OTG=1" is set to discharge from right to left, the bidirectional DC-DC charging / discharging function is realized;

[0126] By adopting this technical solution, two different battery packs can be charged each other, that is, one battery pack P1_B+ (left side) can charge another battery pack P2_B+ (right side), or another battery pack P2_B+ (right side) can be used to charge a battery pack P1_B+ (right side), so as to meet the instant charging / discharging function of different battery packs, and more flexibly meet customers' needs for convenient and fast charging at home.

[0127] The embodiments of the utility model are described above in conjunction with the accompanying drawings, but the utility model is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the enlightenment of the utility model, ordinary technicians in this field can also make many forms without departing from the scope of protection of the utility model and the claims, all of which are within the protection of the utility model.

Claims

1. A bidirectional DC-DC buck-boost circuit, characterized in that: have: A first interface module is disposed in the buck-boost circuit, one end of which is connected to a port of a battery pack; A second interface module, one end of which is connected to a port of another battery pack; a switch power module, a first end of which is connected to the other end of the first interface module, The second end of the switching power module is connected to the other end of the second interface module; A voltage boost / buck main control module, whose signal output terminal is connected to the signal input terminal of the switch power module, and the switch power module is used to receive the control pulse output by the voltage boost / buck main control module, The control pulse is used to control the step-up / step-down conversion of the switching power module to control the step-up / step-down of the battery pack to achieve bidirectional charging / discharging.

2. The bidirectional DC-DC buck-boost circuit according to claim 1, characterized in that: The switch power module at least includes a first MOS tube and a second MOS tube. The gate of the first MOS tube is connected to the first signal output terminal of the boost / buck main control module, and is used to receive a first control pulse. The gate of the second MOS tube is connected to the second signal output terminal of the boost / buck main control module for receiving a second control pulse. The drain of the first MOS tube is connected to the source of the second MOS tube, The drain of the second MOS tube is connected to one end of the second interface module through a second resistor. The source of the first MOS tube is connected to the common end.

3. The bidirectional DC-DC buck-boost circuit according to claim 2, characterized in that: The switch power module also includes a third MOS tube and a fourth MOS tube. The gate of the third MOS tube is connected to the third signal output terminal of the boost / buck main control module, and is used to receive a third control pulse. The gate of the fourth MOS tube is connected to the fourth signal output terminal of the boost / buck main control module, and is used to receive a fourth control pulse. The drain of the third MOS tube is connected to the source of the fourth MOS tube, The drain of the fourth MOS tube is connected to one end of the first interface module through a first resistor. The source of the third MOS tube is connected to the common end.

4. The bidirectional DC-DC buck-boost circuit according to claim 3, characterized in that: The switching power module further includes a first inductor, One end of the first inductor is respectively connected to the drain of the first MOS tube, the source of the second MOS tube and a signal end of the boost / buck main control module. The other end of the first inductor is respectively connected to the drain of the third MOS tube, the source of the fourth MOS tube and the other signal end of the boost / buck main control module.

5. The bidirectional DC-DC buck-boost circuit according to claim 4, characterized in that: The voltage boost / down main control module at least includes a main controller, The first signal output terminal of the main controller is coupled to the gate of the first MOS tube, and is used to output the first control pulse. The second signal output terminal of the main controller is coupled to the gate of the second MOS tube, and is used to output the second control pulse. The third signal output terminal of the main controller is coupled to the gate of the third MOS tube, and is used to output the third control pulse. The fourth signal output terminal of the main controller is coupled to the gate of the fourth MOS tube and is used for outputting the fourth control pulse.

6. The bidirectional DC-DC buck-boost circuit according to claim 5, characterized in that: A signal terminal of the main controller is connected to one end of the first inductor, The other signal end of the main controller is connected to the other end of the first inductor.

7. The bidirectional DC-DC buck-boost circuit according to claim 6, characterized in that: The first interface module includes a voltage divider circuit, one end of which is connected to a voltage feedback end of the main controller.

8. The bidirectional DC-DC buck-boost circuit according to claim 7, characterized in that: The voltage divider circuit includes a first resistor and a second resistor connected in series, The connection end of the first resistor and the second resistor is connected to the voltage feedback end of the main controller.

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