Mos tube clamping absorption circuit, buck-boost bidirectional circuit and lithium battery test equipment

Abstract

The utility model provides a clamping absorption circuit, a buck-boost bidirectional circuit and a lithium battery test device, the clamping absorption circuit comprises two groups of protection circuits, the first group of protection circuits is coupled between the grid electrode and the source electrode of a first mos transistor, and the second group of protection circuits is coupled between the grid electrode and the source electrode of a second mos transistor; the first group of RC absorption circuits are coupled between the source electrode and the drain electrode of the first mos transistor, and the second group of RC absorption circuits are coupled between the source electrode and the drain electrode of the second mos transistor; and two groups of energy recovery circuits, the first group of energy recovery circuits is coupled between the grid electrode of the first mos transistor and the first negative voltage end, and the second group of energy recovery circuits is coupled between the grid electrode of the second mos transistor and the second negative voltage end. By adopting the voltage stabilizing diode, the RC absorption circuit and the Schottky diode, reverse driving voltage spikes generated when the mos tube is switched on and switched off are effectively reduced, the switching loss is reduced, the temperature of the mos tube during operation is reduced, and the equipment efficiency is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of power supply circuits, and specifically but not limited to a MOS tube clamping absorption circuit, a buck-boost bidirectional circuit and a lithium battery testing device. Background Art

[0002] In the lithium battery testing industry, the voltage of the battery module is generally below 200V, so most of the DCDC converters used for testing use MOS tubes as power devices.

[0003] However, for MOSFET, the Miller effect (distributed capacitance between input and output) amplifies the equivalent input capacitance value under the inverting amplification effect, which results in the formation of a platform voltage during the MOSFET gate drive process, causing the switching time to become longer, and voltage spikes to appear at the drain and source, and the gate will also have a reverse voltage. The voltage spike and the reverse voltage of the gate increase the switching loss and heat generation, and are also prone to puncture and damage the MOS tube.

[0004] The existing technical solutions mainly include: selecting MOS tubes with high withstand voltage and slow on / off speed or increasing driving resistance to slow down the on / off speed of MOS tubes to reduce the voltage spikes and reverse voltage generated during switching.

[0005] The main problem with choosing MOS tubes with high withstand voltage and slow turn-on speed is that in this application scenario, under the premise of ensuring that the output current remains unchanged, because the conduction loss of high withstand voltage is generally higher than the conduction loss of low withstand voltage, the number of MOS tubes used needs to be increased, which will increase the cost. In addition, the selection is difficult and the delivery time may not be guaranteed.

[0006] In view of this, it is necessary to provide a new structure to solve at least part of the above problems. Utility Model Content

[0007] In view of one or more problems in the prior art, the utility model proposes a MOS tube clamping absorption circuit, a buck-boost bidirectional circuit and a lithium battery testing device. By adopting a voltage stabilizing diode, an RC absorption circuit and a Schottky diode, the reverse driving voltage spike generated when the MOS tube is turned on and off is effectively reduced, the switching loss is reduced, and the temperature of the MOS tube during operation is reduced, thereby improving the efficiency of the equipment.

[0008] The technical solution to achieve the purpose of this utility model is:

[0009] A MOSFET clamping absorption circuit is used for a buck-boost bidirectional circuit. The buck-boost bidirectional circuit includes a first MOSFET and a second MOSFET connected in series. The clamping absorption circuit includes: two groups of protection circuits, a first group of protection circuits is coupled between a gate and a source of the first MOSFET, and a second group of protection circuits is coupled between a gate and a source of the second MOSFET, for reducing a spike voltage when the first MOSFET and the second MOSFET are turned on and off; two groups of RC absorption circuits, a first group of RC absorption circuits is coupled between a source and a drain of the first MOSFET, and a second group of RC absorption circuits is coupled between a source and a drain of the second MOSFET, for absorbing an induced voltage when the first MOSFET and the second MOSFET are turned on and off; and two groups of energy recovery circuits, a first group of energy recovery circuits is coupled between a gate of the first MOSFET and a first negative voltage terminal, and a second group of energy recovery circuits is coupled between a gate of the second MOSFET and a second negative voltage terminal, for reducing a gate reverse voltage when the first MOSFET and the second MOSFET are turned off.

[0010] Furthermore, in the MOS tube clamp absorption circuit of the utility model, the first group of protection circuits includes a first zener diode and a second zener diode, the cathodes of the first zener diode and the second zener diode are connected, the anode of the first zener diode is coupled to the gate of the first MOS tube, and the anode of the second zener diode is coupled to the source of the first MOS tube; the second group of protection circuits includes a third zener diode and a fourth zener diode, the cathodes of the third zener diode and the fourth zener diode are connected, the anode of the third zener diode is coupled to the gate of the second MOS tube, and the anode of the fourth zener diode is coupled to the source of the second MOS tube.

[0011] Furthermore, in the MOS tube clamp absorption circuit of the utility model, the operating voltages of the first zener diode and the second zener diode both meet the following requirements: being greater than the forward drive voltage of the first MOS tube and being less than the maximum rated gate-source voltage Vgs of the first MOS tube; the operating voltages of the third zener diode and the fourth zener diode both meet the following requirements: being greater than the forward drive voltage of the second MOS tube and being less than the maximum rated gate-source voltage Vgs of the second MOS tube.

[0012] Furthermore, in the MOS tube clamping absorption circuit of the utility model, the first group of RC absorption circuits includes a first resistor and a first capacitor connected in series; the second group of RC absorption circuits includes a second resistor and a second capacitor connected in series.

[0013] Furthermore, in the MOS tube clamp absorption circuit of the utility model, the first group of energy recovery circuits includes a first Schottky diode, the positive electrode of the first Schottky diode is coupled to the gate of the first MOS tube, and the negative electrode is coupled to the first negative voltage terminal; the second group of energy recovery circuits includes a second Schottky diode, the positive electrode of the second Schottky diode is coupled to the gate of the second MOS tube, and the negative electrode is coupled to the second negative voltage terminal.

[0014] A buck-boost bidirectional circuit comprises a first MOSFET, a second MOSFET, an inductor, and any one of the above MOSFET clamping absorption circuits, wherein the gate of the first MOSFET is connected to a first pulse width modulation signal, the gate of the second MOSFET is connected to a second pulse width modulation signal, the drain of the first MOSFET is coupled to a positive bus voltage, the source of the first MOSFET is coupled to a drain of the second MOSFET and one end of the inductor, the source of the second MOSFET is coupled to a negative bus voltage and serves as an output negative electrode of the buck-boost bidirectional circuit, and the other end of the inductor is an output positive electrode of the buck-boost bidirectional circuit.

[0015] Furthermore, the buck-boost bidirectional circuit of the utility model also includes a first drive circuit and a second drive circuit, wherein the negative voltage end of the first drive circuit is coupled to the cathode of the first Schottky diode for connecting to the negative voltage released by the first Schottky diode, and the negative voltage end of the second drive circuit is coupled to the cathode of the second Schottky diode for connecting to the negative voltage released by the second Schottky diode.

[0016] Furthermore, the buck-boost bidirectional circuit of the utility model also includes a first drive circuit and a second drive circuit, wherein the output end of the first drive circuit is coupled to the gate of the first MOSFET for providing a first pulse width modulation signal to the first MOSFET; the output end of the second drive circuit is coupled to the gate of the second MOSFET for providing a second pulse width modulation signal to the second MOSFET.

[0017] Furthermore, in the buck-boost bidirectional circuit of the present invention, the output end of the first driving circuit is coupled to the gate of the first MOSFET through the third resistor, and the output end of the second driving circuit is coupled to the gate of the second MOSFET through the fourth resistor.

[0018] A lithium battery testing device comprises any one of the above-mentioned MOS tube clamping absorption circuits.

[0019] Compared with the prior art, the utility model adopts the above technical solution and has the following technical effects:

[0020] 1. The MOS tube clamping absorption circuit of the utility model can effectively reduce the reverse spike voltage generated when the MOS tube is turned on and off by utilizing the reverse blocking characteristics of the reverse series Zener diode, thereby preventing the MOS tube from being damaged due to Vgs overvoltage.

[0021] 2. The MOS tube clamp absorption circuit of the utility model absorbs the induced voltage by utilizing the RC absorption circuit and consumes it through resistance heat generation, thereby effectively reducing EMI noise, reducing the ringing effect when the MOS tube is turned on and off, and improving the stability of the circuit.

[0022] 3. The MOS tube clamp absorption circuit of the utility model utilizes the characteristics of low forward conduction threshold voltage, fast switching speed and low switching loss of Schottky diode to quickly release the stored energy when the MOS tube is turned off, reduce the reverse voltage of the gate, reduce heat loss and improve power supply efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are used to provide a further understanding of the present invention and are used together with the description to explain the embodiments of the present invention, but do not constitute a limitation of the present invention. In the accompanying drawings:

[0024] Figure 1 The utility model shows a schematic structural diagram of the MOS tube clamping absorption circuit.

[0025] Figure 2 The schematic diagram shows the structure of the first driving circuit of the buck-boost bidirectional circuit of the utility model.

[0026] Figure 3 The schematic diagram shows the structure of the second driving circuit of the buck-boost bidirectional circuit of the utility model. DETAILED DESCRIPTION

[0027] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0028] The description in this section is only for typical embodiments, and the present invention is not limited to the scope of the embodiments. The combination of different embodiments, the mutual replacement of some technical features in different embodiments, and the mutual replacement of the same or similar prior art means with some technical features in the embodiments are also within the scope of the description and protection of the present invention.

[0029] According to one aspect of the utility model, a clamping absorption circuit is used for a buck-boost bidirectional circuit, the buck-boost bidirectional circuit includes a first MOS tube and a second MOS tube connected in series, the clamping absorption circuit includes two groups of protection circuits, two groups of RC absorption circuits and two groups of energy recovery circuits, wherein:

[0030] The first protection circuit is coupled between the gate and source of the first MOS tube, and the second protection circuit is coupled between the gate and source of the second MOS tube, and is used to reduce the spike voltage when the first MOS tube and the second MOS tube are turned on and off.

[0031] The first RC absorption circuit is coupled between the source and drain of the first MOS tube, and the second RC absorption circuit is coupled between the source and drain of the second MOS tube, and is used to absorb the induced voltage when the first MOS tube and the second MOS tube are turned on and off.

[0032] The first energy recovery circuit is coupled between the gate of the first MOS tube and the first negative voltage terminal, and the second energy recovery circuit is coupled between the gate of the second MOS tube and the second negative voltage terminal, and is used to reduce the gate reverse voltage when the first MOS tube and the second MOS tube are turned off.

[0033] Example 1

[0034] A clamping snubber circuit, such as Figure 1 As shown, it is used for a buck-boost bidirectional circuit, the buck-boost bidirectional circuit includes a first MOS tube Q1 and a second MOS tube Q2 connected in series, the clamping absorption circuit includes two groups of protection circuits, two groups of RC absorption circuits and two groups of energy recovery circuits, wherein:

[0035] (1) Two sets of protection circuits, the first set of protection circuits is coupled between the gate and source of the first MOSFET Q1, and the second set of protection circuits is coupled between the gate and source of the second MOSFET Q2, for reducing the spike voltage when the first MOSFET Q1 and the second MOSFET Q2 are turned on and off.

[0036] In one embodiment, the first group of protection circuits includes a first Zener diode D2 and a second Zener diode D3, the cathodes of the first Zener diode D2 and the second Zener diode D3 are connected, the anode of the first Zener diode D2 is coupled to the gate of the first MOS tube Q1, and the anode of the second Zener diode D3 is coupled to the source of the first MOS tube Q1. In a specific embodiment, the operating voltages of the first Zener diode D2 and the second Zener diode D3 both meet the requirements of: being greater than the forward drive voltage of the first MOS tube Q1 and less than the maximum rated gate-source voltage Vgs of the first MOS tube Q2. The forward drive voltage is provided by the drive circuit, and the forward direction refers to the source being at zero level and the gate being at high level.

[0037] In another embodiment, the second group of protection circuits includes a third zener diode D4 and a fourth zener diode D6, the cathodes of the third zener diode D4 and the fourth zener diode D6 are connected, the anode of the third zener diode D4 is coupled to the gate of the second MOS tube Q2, and the anode of the fourth zener diode D6 is coupled to the source of the second MOS tube Q2. In a specific embodiment, the operating voltages of the third zener diode D4 and the fourth zener diode D6 both meet the requirements of: being greater than the forward drive voltage of the second MOS tube Q2 and less than the maximum rated gate-source voltage Vgs of the second MOS tube Q2. The forward drive voltage is provided by the drive circuit, and the forward direction refers to the source being at zero level and the gate being at high level.

[0038] The two groups of Zener diodes utilize the reverse blocking characteristics of the diodes to reduce the gate-source forward and reverse spike voltages generated by the charging and discharging of the Miller capacitance of the MOSFETs when the first MOSFET Q1 and the second MOSFET Q2 are turned on / off, thereby preventing the MOSFETs from being damaged due to Vgs overvoltage.

[0039] (2) Two groups of RC absorption circuits, the first group of RC absorption circuits is coupled between the source and drain of the first MOSFET Q1, and the second group of RC absorption circuits is coupled between the source and drain of the second MOSFET Q2, for absorbing the induced voltage when the first MOSFET Q1 and the second MOSFET Q2 are turned on and off.

[0040] In one embodiment, the first RC absorption circuit comprises a first resistor R1 and a first capacitor C1 connected in series.

[0041] In another embodiment, the second RC absorption circuit comprises a second resistor R3 and a second capacitor C2 connected in series.

[0042] The two sets of RC absorption circuits absorb the induced voltage and dissipate heat through resistors R1 and R3, reduce EMI noise, reduce the ringing effect when turning on / off, and improve the stability of the circuit.

[0043] (3) Two energy recovery circuits, a first energy recovery circuit coupled between the gate of the first MOSFET Q1 and the first negative voltage terminal, and a second energy recovery circuit coupled between the gate of the second MOSFET Q2 and the second negative voltage terminal, for reducing the gate reverse voltage when the first MOSFET Q1 and the second MOSFET Q2 are turned off.

[0044] In one embodiment, the first energy recovery circuit comprises a first Schottky diode D1, wherein the anode of the first Schottky diode D1 is coupled to the gate of the first MOS tube Q1, and the cathode of the first Schottky diode D1 is coupled to a first negative voltage terminal provided by a driving circuit.

[0045] In another embodiment, the second energy recovery circuit comprises a second Schottky diode D5, wherein the anode of the second Schottky diode D5 is coupled to the gate of the second MOS tube Q2, and the cathode of the second Schottky diode D5 is coupled to the second negative voltage terminal provided by the driving circuit.

[0046] The two sets of energy recovery circuits utilize the characteristics of low forward conduction threshold voltage, fast switching speed and low switching loss of Schottky diodes. They can quickly release the energy stored in the Miller capacitor when the MOS tube is turned off and feed it back to the negative voltage end of the drive circuit. While reducing the reverse voltage of the gate, it can also reduce the corresponding heat loss and improve power supply efficiency.

[0047] The MOS tube clamping absorption circuit proposed by the utility model can effectively reduce the reverse driving voltage spike generated when the MOS tube is turned on and off, improve the circuit stability, increase the conversion efficiency, thereby achieving energy saving effect while reducing the failure rate, and uses universal devices with low cost.

[0048] According to another aspect of the utility model, a buck-boost bidirectional circuit includes a first MOSFET, a second MOSFET, an inductor, and any one of the above MOSFET clamping absorption circuits, wherein the gate of the first MOSFET is connected to a first pulse width modulation signal, the gate of the second MOSFET is connected to a second pulse width modulation signal, the drain of the first MOSFET is coupled to the positive electrode of the bus voltage, the source of the first MOSFET is coupled to the drain of the second MOSFET and one end of the inductor, the source of the second MOSFET is coupled to the negative electrode of the bus voltage and serves as the output negative electrode of the buck-boost bidirectional circuit, and the other end of the inductor is the output positive electrode of the buck-boost bidirectional circuit.

[0049] Example 2

[0050] A buck-boost bidirectional circuit, such as Figure 1 As shown, it includes a first MOSFET Q1, a second MOSFET Q2, an inductor L1, and any of the above MOSFET clamping absorption circuits, wherein the gate of the first MOSFET Q1 is connected to the first pulse width modulation signal PWM1, the gate of the second MOSFET Q2 is connected to the second pulse width modulation signal PWM2, the drain of the first MOSFET Q1 is coupled to the bus voltage positive electrode BUS+, the source of the first MOSFET Q1 is coupled to the drain of the second MOSFET Q2 and one end of the inductor L1, the source of the second MOSFET Q2 is coupled to the bus voltage negative electrode BUS- and serves as the output negative electrode OUT- of the buck-boost bidirectional circuit, and the other end of the inductor L1 is the output positive electrode OUT+ of the buck-boost bidirectional circuit.

[0051] In one embodiment, the buck-boost bidirectional circuit further includes a first driving circuit and a second driving circuit. Figure 2 As shown, the negative voltage terminal Vee of the first driving circuit is coupled to the cathode of the first Schottky diode D1, and is used to connect the negative voltage -5V1 released by the first Schottky diode D1. The negative voltage terminal Vee of the second driving circuit is coupled to the cathode of the second Schottky diode D5, and is used to connect the negative voltage -5V2 released by the second Schottky diode D5.

[0052] In another embodiment, the buck-boost bidirectional circuit further includes a first drive circuit and a second drive circuit, wherein the output end of the first drive circuit is coupled to the gate of the first MOSFET Q1, and is used to provide the first MOSFET Q1 with a first pulse width modulation signal PWM1; the output end of the second drive circuit is coupled to the gate of the second MOSFET Q2, and is used to provide the second pulse width modulation signal PWM2 to the second MOSFET Q2. In a specific implementation, the output end of the first drive circuit is coupled to the gate of the first MOSFET Q1 through a third resistor R2, and the output end of the second drive circuit is coupled to the gate of the second MOSFET Q2 through a fourth resistor R4.

[0053] According to another aspect of the utility model, a lithium battery testing device includes any one of the above-mentioned MOS tube clamping absorption circuits.

[0054] The description and application of the utility model here are illustrative, and it is not intended to limit the scope of the utility model to the above-mentioned embodiments. The relevant descriptions of the effects or advantages involved in the specification may not be reflected in the actual experimental examples due to the uncertainty of specific condition parameters or other factors, and the relevant descriptions of the effects or advantages are not used to limit the scope of the utility model. The deformation and changes of the embodiments disclosed here are possible, and the replacement of the embodiments and the various equivalent components are well known to those of ordinary skill in the art. It should be clear to those skilled in the art that the utility model can be implemented in other forms, structures, arrangements, proportions, and with other components, materials and parts without departing from the spirit or essential features of the utility model. Other deformations and changes can be made to the embodiments disclosed here without departing from the scope and spirit of the utility model.

Claims

1. A MOS tube clamping absorption circuit, characterized in that: Used in a buck-boost bidirectional circuit, the buck-boost bidirectional circuit comprises a first MOS tube and a second MOS tube connected in series, and the clamping absorption circuit comprises: Two sets of protection circuits, the first set of protection circuits is coupled between the gate and source of the first MOS tube, and the second set of protection circuits is coupled between the gate and source of the second MOS tube, for reducing the spike voltage when the first MOS tube and the second MOS tube are turned on and off; Two groups of RC absorption circuits, the first group of RC absorption circuits are coupled between the source and drain of the first MOS tube, and the second group of RC absorption circuits are coupled between the source and drain of the second MOS tube, for absorbing the induced voltage when the first MOS tube and the second MOS tube are turned on and off; Two sets of energy recovery circuits, a first set of energy recovery circuits coupled between the gate of the first MOS tube and the first negative voltage terminal, and a second set of energy recovery circuits coupled between the gate of the second MOS tube and the second negative voltage terminal, are used to reduce the gate reverse voltage when the first MOS tube and the second MOS tube are turned off.

2. The MOS tube clamping absorption circuit according to claim 1 is characterized in that: The first protection circuit comprises a first voltage stabilizing diode and a second voltage stabilizing diode, wherein the cathodes of the first voltage stabilizing diode and the second voltage stabilizing diode are connected, the anode of the first voltage stabilizing diode is coupled to the gate of the first MOS tube, and the anode of the second voltage stabilizing diode is coupled to the source of the first MOS tube; The second protection circuit includes a third zener diode and a fourth zener diode, the cathodes of the third zener diode and the fourth zener diode are connected, the anode of the third zener diode is coupled to the gate of the second MOS tube, and the anode of the fourth zener diode is coupled to the source of the second MOS tube.

3. The MOS tube clamping absorption circuit according to claim 2 is characterized in that: The operating voltages of the first zener diode and the second zener diode both meet the following requirements: greater than the forward drive voltage of the first MOS tube and less than the maximum rated gate-source voltage Vgs of the first MOS tube; The operating voltages of the third zener diode and the fourth zener diode both meet the following requirements: greater than the forward driving voltage of the second MOS tube, and less than the maximum rated gate-source voltage Vgs of the second MOS tube.

4. The MOS tube clamping absorption circuit according to claim 1, characterized in that: The first RC absorption circuit comprises a first resistor and a first capacitor connected in series; The second RC absorption circuit includes a second resistor and a second capacitor connected in series.

5. The MOS tube clamping absorption circuit according to claim 1, characterized in that: The first energy recovery circuit comprises a first Schottky diode, wherein the anode of the first Schottky diode is coupled to the gate of the first MOS tube, and the cathode of the first Schottky diode is coupled to the first negative voltage terminal; The second energy recovery circuit comprises a second Schottky diode, wherein the anode of the second Schottky diode is coupled to the gate of the second MOS tube, and the cathode of the second Schottky diode is coupled to the second negative voltage terminal.

6. A buck-boost bidirectional circuit, characterized in that: The invention comprises a first MOSFET, a second MOSFET, an inductor, and a MOSFET clamping absorption circuit as described in any one of claims 1 to 5, wherein the gate of the first MOSFET is connected to a first pulse width modulation signal, the gate of the second MOSFET is connected to a second pulse width modulation signal, the drain of the first MOSFET is coupled to a positive pole of a bus voltage, the source of the first MOSFET is coupled to a drain of the second MOSFET and one end of the inductor, the source of the second MOSFET is coupled to a negative pole of the bus voltage and serves as an output negative pole of a buck-boost bidirectional circuit, and the other end of the inductor is an output positive pole of the buck-boost bidirectional circuit.

7. The buck-boost bidirectional circuit according to claim 6, characterized in that: It also includes a first drive circuit and a second drive circuit, wherein the negative voltage end of the first drive circuit is coupled to the cathode of the first Schottky diode for connecting to the negative voltage released by the first Schottky diode, and the negative voltage end of the second drive circuit is coupled to the cathode of the second Schottky diode for connecting to the negative voltage released by the second Schottky diode.

8. The buck-boost bidirectional circuit according to claim 6, characterized in that: It also includes a first driving circuit and a second driving circuit, wherein the output end of the first driving circuit is coupled to the gate of the first MOS tube, and is used to provide a first pulse width modulation signal for the first MOS tube; The output end of the second driving circuit is coupled to the gate of the second MOS tube, and is used to provide a second pulse width modulation signal for the second MOS tube.

9. The buck-boost bidirectional circuit according to claim 8, characterized in that: The output end of the first driving circuit is coupled to the gate of the first MOS tube through the third resistor, and the output end of the second driving circuit is coupled to the gate of the second MOS tube through the fourth resistor.

10. A lithium battery testing device, characterized in that: It comprises the MOS tube clamping absorption circuit as described in any one of claims 1-5.

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