Driving circuit of motor and switch tube
By outputting different magnitudes of drive current at different stages of the switching transistor, the problem of excessively rapid voltage change rate caused by excessive drive current of the switching transistor in the prior art is solved, thereby improving the EMI performance and stability of the circuit.
Patent Information
- Application Number
- CN202520334971.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-27
- Publication Date
- 2026-02-03
- Estimated Expiration
- 2035-02-27
AI Technical Summary
The existing driving circuits for switching transistors use a large driving current, which causes the gate-drain parasitic capacitance of the NMOS transistor to charge at an extremely fast rate. This leads to a larger voltage change and worse EMI performance of the switching transistor, affecting circuit functionality.
A driving circuit for a switching transistor is provided. Through the coordinated operation of a control unit and a constant current source unit, different driving currents of different magnitudes, including positive and negative currents, are output at different switching stages to control the turn-on and turn-off process of the NMOS transistor, reduce the voltage change rate, and improve EMI performance.
By applying appropriate drive current at different stages, the switching of the transistor is made smoother, which improves the EMI performance of the circuit and avoids circuit failure caused by excessively rapid voltage change rate.
Smart Images
Figure CN223872201U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of electronic circuit technology, specifically to a drive circuit for a motor and a switching transistor. Background Technology
[0002] In the field of electronic circuits, to reduce circuit losses, MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) with low on-resistance are generally chosen as switching transistors. However, for NMOS (N-Metal-Oxide-Semiconductor) transistors, the wafer area required for low on-resistance NMOS transistors is larger, resulting in a larger parasitic capacitance. NMOS transistors are generally driven by either voltage-mode or current-mode methods. To meet the control performance requirements of the switching transistor, current-mode driving is generally used.
[0003] Because NMOS transistors with low on-resistance are chosen as the switching transistors, the low on-resistance leads to an increase in the gate-source parasitic capacitance, while the gate-drain parasitic capacitance remains unchanged. Typically, the driving circuit for an NMOS transistor uses a constant current source to charge the gate-source and gate-drain parasitic capacitances to turn it on. However, to achieve rapid turn-on and reduce switching losses, the NMOS transistor must turn on within a specific timeframe, requiring a large drive current. This large current causes the gate-drain parasitic capacitance to charge extremely quickly, resulting in a larger voltage change at the switching transistor, which degrades EMI performance and affects circuit functionality. Utility Model Content
[0004] In response to this, this application provides a driving circuit for a motor and a switching transistor to solve the problem that the existing driving circuit for the switching transistor, which uses a large driving current, causes the gate-drain parasitic capacitance of the NMOS transistor to charge at an extremely fast rate, resulting in a larger voltage change value and worse EMI performance of the switching transistor, thus affecting the circuit function.
[0005] To achieve the above objectives, the embodiments of this application provide the following technical solutions:
[0006] The first aspect of this application discloses a driving circuit for a switching transistor, including: a control unit and a constant current source unit;
[0007] The output terminal of the control unit is connected to the control terminal of the constant current source unit, and outputs a constant current source output control signal.
[0008] The first output terminal of the constant current source unit is connected to the gate of the switching transistor, and the second output terminal of the constant current source unit is connected to the source of the switching transistor.
[0009] When the switching transistor is in the first or third turn-on stage, the first output terminal of the constant current source unit outputs a first driving current; when the switching transistor is in the second turn-on stage, the first output terminal of the constant current source unit outputs a second driving current; when the switching transistor is in the fourth turn-on stage, the first output terminal of the constant current source unit outputs a third driving current. The first driving current, the second driving current, and the third driving current are all positive currents. The first driving current is greater than the second driving current, and the third driving current is greater than the second driving current.
[0010] When the switching transistor is in the first or second off phase, the second output terminal of the constant current source unit outputs a fourth drive current; when the switching transistor is in the second off phase, the second output terminal of the constant current source unit outputs a fifth drive current; when the switching transistor is in the fourth off phase, the second output terminal of the constant current source unit outputs a sixth drive current, wherein the fourth, fifth, and sixth drive currents are negative currents, the fourth drive current is less than the fifth drive current, and the sixth drive current is less than the fourth drive current.
[0011] Optionally, in the driving circuit of the switching transistor described above, the constant current source unit includes at least: a charge pump, a first constant current source subunit, and a second constant current source subunit;
[0012] The output terminal of the charge pump is connected to the input terminal of the first constant current source subunit;
[0013] The output terminal of the first constant current source subunit is connected to the input terminal of the second constant current source subunit, and the connection point serves as the first output terminal of the constant current source unit.
[0014] The output terminal of the second constant current source subunit serves as the second output terminal of the constant current source unit.
[0015] Optionally, in the above-mentioned driving circuit of the switching transistor, the first constant current source subunit includes at least: N parallel-connected first current source branches, N≥2, the first current source branch includes a switch and a current source connected in series, the parallel input terminal of the first current source branch serves as the input terminal of the first constant current source subunit, and the parallel output terminal of the first current source branch serves as the output terminal of the first constant current source subunit.
[0016] Optionally, in the above-mentioned driving circuit of the switching transistor, the second constant current source subunit includes at least M parallel-connected second current source branches, M≥2, the second current source branch includes a switch and a current source connected in series, the parallel input terminal of the second current source branch serves as the input terminal of the second constant current source subunit, and the parallel output terminal of the second current source branch serves as the output terminal of the second constant current source subunit.
[0017] Optionally, the driving circuit of the switching transistor described above further includes: a power supply unit, wherein the input terminal of the power supply unit is connected to the power supply voltage of the switching transistor, and the output terminal of the power supply unit is connected to the power supply terminal of the control unit;
[0018] Alternatively, a clamping unit, wherein the first end of the clamping unit is connected to the gate of the switching transistor, and the second end of the clamping unit is connected to the source of the switching transistor.
[0019] Optionally, the driving circuit of the aforementioned switching transistor further includes: a drain-source voltage detection unit, wherein the first input terminal of the drain-source voltage detection unit is connected to the drain of the switching transistor, the second input terminal of the drain-source voltage detection unit is connected to the source of the switching transistor, and the output terminal of the drain-source voltage detection unit is connected to the input terminal of the control unit to output the drain-source comparison voltage of the switching transistor.
[0020] Optionally, in the driving circuit of the switching transistor described above, the drain-source voltage detection unit includes: a first comparator and a second comparator;
[0021] The non-inverting input of the first comparator serves as the first input of the drain-source voltage detection unit, the inverting input of the first comparator serves as the second input of the drain-source voltage detection unit, and the output of the first comparator is connected to the inverting input of the second comparator.
[0022] The non-inverting input of the second comparator receives the drain-source threshold voltage of the switching transistor, and the output of the second comparator serves as the output of the drain-source voltage detection unit.
[0023] Optionally, the driving circuit of the above-mentioned switching transistor further includes: a gate-source voltage detection unit, wherein the first input terminal of the gate-source voltage detection unit is connected to the gate of the switching transistor, the second output terminal of the gate-source voltage detection unit is connected to the source of the switching transistor, and the output terminal of the gate-source voltage detection unit is connected to the input terminal of the control unit to output the gate-source comparison voltage of the switching transistor.
[0024] Optionally, in the above-described driving circuit for the switching transistor, the gate-source voltage detection unit includes: a third comparator and a fourth comparator;
[0025] The non-inverting input of the third comparator serves as the first input of the gate-source voltage detection unit, the inverting input of the third comparator serves as the second output of the gate-source voltage detection unit, and the output of the third comparator is connected to the inverting input of the fourth comparator.
[0026] The input terminal of the fourth comparator receives the gate-source threshold voltage of the switching transistor, and the output terminal of the fourth comparator serves as the output terminal of the gate-source voltage detection unit.
[0027] The second aspect of this application discloses a motor including at least one half-bridge circuit, the half-bridge circuit including two switching transistors connected in series, the switching transistors being provided with a driving circuit as described in any of the claims of the first aspect.
[0028] The driving circuit for the switching transistor provided in this application includes: a control unit and a constant current source unit; the output terminal of the control unit is connected to the control terminal of the constant current source unit, and outputs a constant current source output control signal; the first output terminal of the constant current source unit is connected to the gate of the switching transistor, and the second output terminal of the constant current source unit is connected to the source of the switching transistor; when the switching transistor is in a first turn-on stage or a third turn-on stage, the first output terminal of the constant current source unit outputs a first driving current; when the switching transistor is in a second turn-on stage, the first output terminal of the constant current source unit outputs a second driving current; when the switching transistor is in a fourth turn-on stage, the first output terminal of the constant current source unit outputs a third driving current, wherein the first driving current, the second driving current, and the third driving current are positive currents, the first driving current is greater than the second driving current, and the third driving current is greater than the second driving current; when the switching transistor is in a first turn-off stage or... During the third turn-off phase, the second output terminal of the constant current source unit outputs the fourth drive current; during the second turn-off phase, the second output terminal of the constant current source unit outputs the fifth drive current; during the fourth turn-off phase, the second output terminal of the constant current source unit outputs the sixth drive current. The fourth, fifth, and sixth drive currents are negative currents, with the fourth drive current being less than the fifth drive current and the sixth drive current being less than the fourth drive current. This allows different drive currents to be applied to the switch at different stages, ensuring smoother switching and thus improving the EMI performance of the circuit. This addresses the problem that existing switch drive control circuits, by using a large drive current, cause the gate-drain parasitic capacitance of the NMOS transistor to charge extremely quickly, leading to larger voltage changes and poorer EMI performance, thus affecting circuit functionality. Attached Figure Description
[0029] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.
[0030] Figure 1 A schematic diagram of the equivalent parasitic capacitance of a MOS transistor provided in an embodiment of this application;
[0031] Figure 2 A schematic diagram of a drive circuit for a switching transistor provided in an embodiment of this application;
[0032] Figure 3 A circuit diagram of a drive circuit for a switching transistor provided in an embodiment of this application;
[0033] Figure 4 A circuit diagram of another driving circuit for a switching transistor provided in an embodiment of this application;
[0034] Figure 5 This is a schematic diagram of the switching process of a switching transistor provided in an embodiment of this application. Detailed Implementation
[0035] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0036] First, it should be noted that, as Figure 1 As shown, a MOSFET is an important basic component in circuits. MOSFETs are commonly used in amplifier circuits or switching circuits, and their various states can be controlled by controlling the voltage difference between the gate (G) and source (S) of the MOSFET. Due to the manufacturing process of MOSFETs, parasitic capacitance is generated between each pair of plates at the drain (D), gate (G), and source (S).
[0037] This application provides a driving circuit for a motor and a switching transistor to solve the problem that existing driving circuits for switching transistors, when driven by a large driving current, cause the gate-drain parasitic capacitance of the NMOS transistor to charge at an extremely fast rate, resulting in a larger voltage change value and worse EMI performance of the switching transistor, thus affecting the circuit function.
[0038] Please see Figure 2 The driving circuit of the switching transistor mainly includes: control unit 101 and constant current source unit 102;
[0039] The output terminal of the control unit 101 is connected to the control terminal of the constant current source unit 102, and outputs a constant current source output control signal.
[0040] The first output terminal of the constant current source unit 102 is connected to the gate of the switching transistor, and the second output terminal of the constant current source unit 102 is connected to the source of the switching transistor.
[0041] When the switching transistor is in the first or third turn-on stage, the first output terminal of the constant current source unit 102 outputs a first driving current; when the switching transistor is in the second turn-on stage, the first output terminal of the constant current source unit 102 outputs a second driving current; when the switching transistor is in the fourth turn-on stage, the first output terminal of the constant current source unit 102 outputs a third driving current. The first driving current, the second driving current, and the third driving current are all positive currents. The first driving current is greater than the second driving current, and the third driving current is greater than the second driving current.
[0042] When the switching transistor is in the first or third off stage, the second output terminal of the constant current source unit 102 outputs a fourth driving current; when the switching transistor is in the second off stage, the second output terminal of the constant current source unit 102 outputs a fifth driving current; when the switching transistor is in the fourth off stage, the second output terminal of the constant current source unit 102 outputs a sixth driving current. The fourth, fifth, and sixth driving currents are negative currents, and the fourth driving current is less than the fifth driving current, and the sixth driving current is less than the fourth driving current.
[0043] In practical applications, the control unit 101 can output a corresponding constant current source output control signal according to the stage of the switching transistor, so as to control the constant current source unit 102 to output different drive currents.
[0044] In some embodiments, such as Figure 3 As shown, the constant current source unit 102 includes at least: a charge pump, a first constant current source subunit (a current source connected in parallel in the upper part of the constant current source unit 102) and a second constant current source subunit (a current source connected in parallel in the lower part of the constant current source unit 102).
[0045] The output terminal of the charge pump is connected to the input terminal of the first constant current source subunit; the output terminal of the first constant current source subunit is connected to the input terminal of the second constant current source subunit, and the connection point serves as the first output terminal of the constant current source unit 102; the output terminal of the second constant current source subunit serves as the second output terminal of the constant current source unit 102.
[0046] The charge pump is used to boost the voltage to power the gate of the switching transistor.
[0047] In practical applications, the first constant current source subunit includes at least N parallel-connected first current source branches, where N≥2. Each first current source branch includes a switch and a current source connected in series. The parallel input terminal of the first current source branch serves as the input terminal of the first constant current source subunit, and the parallel output terminal of the first current source branch serves as the output terminal of the first constant current source subunit.
[0048] It is understandable that whether each first current source branch can output is controlled by the switch state on the branch; when the switch on the first current source branch is in the closed state, the first current source branch has an output; conversely, when the switch on the first current source branch is in the open state, the first current source branch has no output.
[0049] In practical applications, the second constant current source subunit includes at least M parallel-connected second current source branches, M≥2. The second current source branch includes a switch and a current source connected in series. The parallel input terminal of the second current source branch serves as the input terminal of the second constant current source subunit, and the parallel output terminal of the second current source branch serves as the output terminal of the second constant current source subunit.
[0050] It is understandable that whether each second current source branch can output is controlled by the switch state on the branch; when the switch on the second current source branch is in the closed state, the second current source branch has an output; conversely, when the switch on the second current source branch is in the open state, the second current source branch has no output.
[0051] In some embodiments, combined with Figure 5 Taking an NMOS transistor as an example, the first turn-on stage corresponds to the first t1 stage in the figure. That is, when the gate-source voltage of the transistor gradually increases, the drain current of the transistor gradually increases, and the drain-source voltage of the transistor remains unchanged under the premise that the switching signal of the transistor is pulled high, the first turn-on stage is in which the gate-source voltage of the transistor gradually increases, the drain current of the transistor gradually increases, and the drain-source voltage of the transistor remains unchanged.
[0052] During the first turn-on phase, the constant current source unit 102 gradually charges the gate-source parasitic capacitance of the switching transistor through the gate of the switching transistor, thereby causing the gate-source voltage of the switching transistor to rise. When the gate-source voltage of the switching transistor is greater than the gate-source threshold voltage of the switching transistor, a current flows through the switching transistor, and the current gradually increases as the gate-source voltage of the switching transistor rises, but the drain-source voltage of the switching transistor remains almost unchanged.
[0053] The second opening phase corresponds to Figure 5 The first t2 stage, that is, when the switching signal of the switching transistor is pulled high, the gate-source voltage of the switching transistor remains unchanged, the drain current of the switching transistor remains unchanged, and the drain-source voltage of the switching transistor decreases, belongs to the second turn-on stage.
[0054] During the second turn-on phase, continuing to charge the gate of the switching transistor reveals that the drain current no longer increases, and the gate-source voltage remains almost unchanged. However, the drain-source voltage begins to decrease, and the impedance of the switching transistor also begins to decrease, indicating that the switching transistor has entered the Miller plateau stage of the conduction state. In the Miller plateau stage, the drain-source voltage of the switching transistor changes drastically, rapidly dropping from the supply voltage to Id*Rdson, where Id represents the drain current and Rdson represents the parasitic resistance. At this time, the rate of change of voltage dv / dt increases rapidly, which can lead to circuit oscillation and deterioration of EMI performance. During this stage, the current flowing into the gate of the switching transistor is mainly used to charge the gate-drain parasitic capacitance.
[0055] The third opening phase corresponds to Figure 5 The first t3 stage, that is, when the switching signal of the switching transistor is pulled high, the gate-source voltage of the switching transistor gradually increases, the drain current of the switching transistor remains unchanged, and the drain-source voltage of the switching transistor remains unchanged, it belongs to the third turn-on stage.
[0056] In the third turn-on state, continuing to charge the gate of the switch reveals that the drain-source voltage no longer decreases, and the gate-source voltage begins to rise. The drain current remains constant until the gate voltage equals the charge pump voltage. During this stage, the gate current flowing into the switch is almost entirely used to charge the gate-source parasitic capacitance, ensuring the switch enters the variable resistance region, where the on-resistance is minimized, and losses and heat generation are also minimized.
[0057] The fourth opening stage corresponds to Figure 5 In the first t4 stage, after the third turn-on stage, a strong pull-up current source is needed to pull up the gate voltage of the switch to keep it continuously conducting. Since this current source only needs to maintain the gate state, high precision is not required, which saves costs. During the fourth turn-on stage, the gate-source voltage of the switch remains unchanged.
[0058] The turn-off phase of the switching transistor is the opposite of the turn-on phase, and is also combined with... Figure 5 The first shutdown stage corresponds to the second t3 stage in the figure. Under the premise that the switching signal of the switching transistor is pulled low, the gate-source voltage of the switching transistor gradually decreases while the drain current of the switching transistor remains unchanged. When the drain-source voltage of the switching transistor remains unchanged, it belongs to the first shutdown stage.
[0059] During the first shutdown phase, releasing the gate voltage of the switching transistor reveals that the gate-source voltage gradually decreases, while the drain-source voltage remains constant, and the drain current remains unchanged. In this phase, the gate-source parasitic capacitance acts as a buffer, and the switching transistor enters the variable resistance region. In this region, the on-resistance of the switching transistor remains in the on state, thus minimizing losses and heat generation.
[0060] The second closing phase corresponds to Figure 5 The second t2 stage, that is, when the switching signal of the switching transistor is pulled low, the gate-source voltage of the switching transistor remains unchanged, the drain current of the switching transistor remains unchanged, and the drain-source voltage of the switching transistor rises, it belongs to the second shutdown stage.
[0061] With the switching signal pulled low, continuing to discharge the switching transistor reveals that while the gate-source voltage and drain current remain constant, the drain-source voltage and impedance begin to rise, indicating that the transistor has entered the Miller plateau phase of the off state. During the Miller plateau phase, the drain-source voltage undergoes a drastic change, rapidly increasing from Id*Rdson to the supply voltage, where Id represents the drain current and Rdson represents the parasitic resistance. This means the rate of change of voltage (dv / dt) increases rapidly, potentially causing circuit oscillations and deteriorating EMI performance. This phase primarily involves releasing the current from the gate-drain parasitic capacitance in the transistor.
[0062] The third closing phase corresponds to Figure 5 The second t1, that is, when the switching signal of the switching transistor is pulled low, the gate-source voltage of the switching transistor gradually decreases, the drain current of the switching transistor gradually decreases, and the drain-source voltage of the switching transistor remains unchanged, it belongs to the third turn-off stage.
[0063] During the third shutdown phase, the constant current source unit 102 provides a low negative voltage to gradually discharge the gate-source parasitic capacitance of the switching transistor, thereby causing the gate-source voltage of the switching transistor to decrease. When the gate-source voltage of the switching transistor is lower than the gate-source threshold voltage of the switching transistor, the drain current of the switching transistor drops sharply to 0, accompanied by a continuous decrease in the gate-source voltage of the switching transistor, but the drain-source voltage of the switching transistor remains almost unchanged.
[0064] The fourth closing phase corresponds to Figure 5 In the second t4 stage, during the fourth shutdown stage, the gate-source voltage of the switching transistor drops to 0, the drain current of the switching transistor remains at 0, and the drain-source voltage of the switching transistor remains almost unchanged.
[0065] After the third shutdown phase, in order to keep the switch transistor continuously off, a strong pull-down current source is needed to pull down the gate voltage of the switch transistor. Since this current source only needs to maintain the gate state, it does not need to be highly accurate, which can save costs.
[0066] in, Figure 5 In this context, Isoure represents the first drive current, Idrvp represents the second drive current, Ihold represents the third drive current, Isink represents the fourth drive current, Idrvn represents the fifth drive current, Istrong represents the sixth drive current, Vgs represents the gate-source voltage of the switch, Id represents the drain current of the switch, and Vds represents the drain-source voltage of the switch.
[0067] Based on the above, this application can optimize the EMI performance of the switching transistor by controlling the constant current source unit 102 to output different magnitudes of drive current according to the various stages of the switching transistor.
[0068] Taking the on state as an example, since shortening the time of the first or third on stage will not cause a sudden change in the circuit voltage and will not affect the EMI performance of the circuit, a larger drive current can be used to drive the switch in the first or third on stage, such as the first drive current. In order to extend the time of the second on stage and reduce the voltage change rate of the switch, a smaller drive current can be used to drive the switch in the second on stage, such as the second drive current. Furthermore, after the switch is successfully driven, in order to maintain the conduction state of the switch, a larger pull-up current can be used in the fourth on stage to maintain the gate voltage of the switch, so that the switch remains in the conduction state until it receives the turn-off command (the switch signal of the switch is pulled low).
[0069] In practical applications, based on the above logic principles, the control unit 101 can count using an internal timer, or, as... Figure 4 As shown, by setting an external timer unit 107, the constant current source unit 102 is controlled to output different magnitudes of drive current at corresponding stages, thereby enabling the EMI performance of the switching transistor to reach the optimal level.
[0070] Since the switching transistor is symmetrical when it is turned on and off, the magnitude of the drive point current in each stage of the off phase can be derived from the above-mentioned on-state, which will not be repeated in this application.
[0071] It should be noted that the switching transistor in this application can be an NMOS transistor; of course, it is not limited to this, and can also be other existing types of switching transistors. This application does not limit the specific type of switching transistor, and all of them are within the protection scope of this application.
[0072] Based on the above principles, the driving circuit for the switching transistor provided in this embodiment includes: a control unit 101 and a constant current source unit 102; the output terminal of the control unit 101 is connected to the control terminal of the constant current source unit 102, and outputs a constant current source output control signal; the first output terminal of the constant current source unit 102 is connected to the gate of the switching transistor, and the second output terminal of the constant current source unit 102 is connected to the source of the switching transistor; when the switching transistor is in the first turn-on stage or the third turn-on stage, the first output terminal of the constant current source unit 102 outputs a first driving current; when the switching transistor is in the second turn-on stage, the first output terminal of the constant current source unit 102 outputs a second driving current; when the switching transistor is in the fourth turn-on stage, the first output terminal of the constant current source unit 102 outputs a third driving current, wherein the first driving current, the second driving current, and the third driving current are positive currents, the first driving current is greater than the second driving current, and the third driving current is greater than the second driving current; When the switching transistor is in the first or third off stage, the second output terminal of the constant current source unit 102 outputs a fourth drive current; when the switching transistor is in the second off stage, the second output terminal of the constant current source unit 102 outputs a fifth drive current; when the switching transistor is in the fourth off stage, the second output terminal of the constant current source unit 102 outputs a sixth drive current. The fourth, fifth, and sixth drive currents are negative currents, with the fourth drive current being less than the fifth drive current and the sixth drive current being less than the fourth drive current. This allows different drive currents to be applied to the switching transistor at different stages, ensuring smoother switching on and off, thereby improving the EMI performance of the circuit. This addresses the problem that existing switching transistor drive control circuits, when driven by a large drive current, cause the gate-drain parasitic capacitance of the NMOS transistor to charge extremely quickly, leading to larger voltage changes and poorer EMI performance, thus affecting circuit functionality.
[0073] Optionally, such as Figure 3 As shown, the driving circuit for the switching transistor provided in another embodiment of this application further includes a power supply unit 103, the input terminal of which is connected to the power supply voltage Vbat of the switching transistor, and the output terminal of which is connected to the power supply terminal of the control unit 101.
[0074] In practical applications, a power supply unit 103 can be added to power the control unit 101 by taking power from the power supply voltage of the switching transistor. Directly using the internal power supply can reduce the area of the drive circuit board and improve the reliability of the drive circuit of the switching transistor.
[0075] Alternatively, clamping unit 104, with its first end connected to the gate of the switching transistor and its second end connected to the source of the switching transistor.
[0076] In practical applications, the same applies. Figure 3As shown, the clamping unit 104 includes at least one Zener diode Z1. Multiple Zener diodes Z1 are connected, with one end of the connection serving as the first terminal of the clamping unit 104 and the other end serving as the second terminal. The connection method between the multiple Zener diodes Z1 can be series, parallel, or a combination thereof, depending on the application environment and user requirements, and all are within the scope of this application. Figure 3 Take Zener diode Z1 as an example.
[0077] In practical applications, setting a clamping unit 104 between the gate and source of the switching transistor can prevent the gate-source voltage of the switching transistor from becoming too large and damaging the switching transistor, thereby further improving the reliability of the driving circuit of the switching transistor.
[0078] Optionally, such as Figure 3 As shown, another embodiment of the present application provides a driving circuit for a switching transistor that further includes a drain-source voltage detection unit 105. The first input terminal of the drain-source voltage detection unit 105 is connected to the drain of the switching transistor, the second input terminal of the drain-source voltage detection unit 105 is connected to the source of the switching transistor, and the output terminal of the drain-source voltage detection unit 105 is connected to the input terminal of the control unit 101 to output the drain-source comparison voltage of the switching transistor.
[0079] In practical applications, such as Figure 3 As shown, the drain-source voltage detection unit 105 may include: a first comparator A1 and a second comparator A2.
[0080] In this configuration, the non-inverting input of the first comparator A1 serves as the first input of the drain-source voltage detection unit 105, the inverting input of the first comparator A1 serves as the second input of the drain-source voltage detection unit 105, and the output of the first comparator A1 is connected to the inverting input of the second comparator A2. The non-inverting input of the second comparator A2 receives the drain-source threshold voltage of the switching transistor, and the output of the second comparator A2 serves as the output of the drain-source voltage detection unit 105.
[0081] It should be noted that the drain-source voltage of the switching transistor can be acquired through the first comparator A1, and then the acquired drain-source voltage is input to the second comparator A2 for comparison with the drain-source threshold voltage of the switching transistor, according to the formula Vds=Rdson*I. DS It can be known that (I) DS The drain-source current of the switching transistor is represented by the drain-source current. When the switching transistor experiences an overcurrent, its drain-source voltage will increase. Based on this characteristic, the controller unit 101 can be used to determine in real time whether the drain-source voltage of the switching transistor is over-voltage at each stage. If it is determined that the drain-source voltage of the switching transistor is over-voltage, the switching transistor can be controlled to disconnect, thereby protecting the switching transistor and its drive circuit.
[0082] Specifically, the function of determining whether there is an overvoltage in the drain-source voltage of the switching transistor can be enabled when the switching transistor is in the on state and disabled when the switching transistor is in the off state, thereby avoiding false alarms when the switching transistor is in the off state and further improving the reliability of the switching transistor's drive circuit.
[0083] It should also be noted that the specific value of the drain-source threshold voltage of the switching transistor can be determined according to the application environment and user requirements. Different values of the drain-source threshold voltage of the switching transistor can control the overcurrent protection of the switching transistor at different thresholds.
[0084] Optionally, such as Figure 3 As shown, another embodiment of the present application provides a driving circuit for a switching transistor that further includes a gate-source voltage detection unit 106. The first input terminal of the gate-source voltage detection unit 106 is connected to the gate of the switching transistor, the second output terminal of the gate-source voltage detection unit 106 is connected to the source of the switching transistor, and the output terminal of the gate-source voltage detection unit 106 is connected to the input terminal of the control unit 101 to output the gate-source comparison voltage of the switching transistor.
[0085] In practical applications, such as Figure 3 As shown, the gate-source voltage detection unit 106 may include a third comparator A3 and a fourth comparator A4.
[0086] The non-inverting input of the third comparator A3 serves as the first input of the gate-source voltage detection unit 106, and the inverting input of the third comparator A3 serves as the second output of the gate-source voltage detection unit 106. The output of the third comparator A3 is connected to the inverting input of the fourth comparator A4. The input of the fourth comparator A4 receives the gate-source threshold voltage of the switching transistor, and the output of the fourth comparator A4 serves as the output of the gate-source voltage detection unit 106.
[0087] It should be noted that the gate-source voltage of the switching transistor can be acquired through the third comparator A3. This acquired gate-source voltage is then input to the fourth comparator A4 and compared with the gate-source threshold voltage of the switching transistor. Based on the relationship between the acquired gate-source voltage and the gate-source threshold voltage, it can be determined whether the switching transistor has malfunctioned. For example, if the acquired gate-source voltage is less than the gate-source threshold voltage when the switching transistor is in the on state, and the switching transistor is in the fourth on stage, it indicates that the switching transistor has malfunctioned and cannot be turned on. In this case, the control unit 101 can be used to turn off the switching transistor to protect it and its drive circuit. Conversely, if the acquired gate-source voltage is greater than the gate-source threshold voltage when the switching transistor is in the off state, and the switching transistor is in the fourth off stage, it indicates that the switching transistor has malfunctioned and cannot be turned off. In this case, the control unit 101 can be used to turn off the switching transistor to protect it and its drive circuit.
[0088] Based on the above, alternatively, another embodiment of this application also provides a motor, which includes at least one half-bridge circuit, the half-bridge circuit including two switching transistors connected in series, the switching transistors being provided with a driving circuit as described in any of the above embodiments.
[0089] In practical applications, the motor can be a three-phase motor; of course, it is not limited to this, and can be determined according to the application environment and user needs. This application does not make specific limitations, and all of them are within the protection scope of this application.
[0090] It should be noted that, Figure 3 The circuit diagram of the driving circuit for the switching transistors shown is presented using three half-bridges, with the driving circuit for each switching transistor in each half-bridge being identical.
[0091] It should also be noted that reducing the number of control units 101 saves circuit costs, as the drive circuits for each switching transistor in the motor can be supplied by one control unit 101.
[0092] It should be noted that the relevant descriptions of the drive circuit for the switching transistor can be found in the corresponding embodiments described above, and will not be repeated here; the relevant descriptions of the motor can also be found in the existing foundation, and will not be repeated here either.
[0093] The features described in the various embodiments of this specification can be substituted for or combined with each other. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, for system or system embodiments, since they are basically similar to method embodiments, the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments. The systems and system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without creative effort.
[0094] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.
[0095] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
[0096] It should also be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
Claims
1. A driving circuit for a switching transistor, characterized in that, include: Control unit and constant current source unit; The output terminal of the control unit is connected to the control terminal of the constant current source unit, and outputs a constant current source output control signal. The first output terminal of the constant current source unit is connected to the gate of the switching transistor, and the second output terminal of the constant current source unit is connected to the source of the switching transistor. When the switching transistor is in the first turn-on stage or the third turn-on stage, the first output terminal of the constant current source unit outputs a first drive current; when the switching transistor is in the second turn-on stage, the first output terminal of the constant current source unit outputs a second drive current. When the switching transistor is in the fourth turn-on stage, the first output terminal of the constant current source unit outputs a third driving current. The first driving current, the second driving current and the third driving current are positive currents. The first driving current is greater than the second driving current and the third driving current is greater than the second driving current. When the switching transistor is in the first or third off phase, the second output terminal of the constant current source unit outputs a fourth drive current. When the switching transistor is in the second off phase, the second output terminal of the constant current source unit outputs a fifth drive current. When the switching transistor is in the fourth off phase, the sixth drive current at the second output terminal of the constant current source unit is a negative current, the fourth drive current, the fifth drive current and the sixth drive current are negative currents, the fourth drive current is less than the fifth drive current and the sixth drive current is less than the fourth drive current.
2. The driving circuit for the switching transistor according to claim 1, characterized in that, The constant current source unit includes at least: a charge pump, a first constant current source subunit, and a second constant current source subunit; The output terminal of the charge pump is connected to the input terminal of the first constant current source subunit; The output terminal of the first constant current source subunit is connected to the input terminal of the second constant current source subunit, and the connection point serves as the first output terminal of the constant current source unit. The output terminal of the second constant current source subunit serves as the second output terminal of the constant current source unit.
3. The driving circuit for the switching transistor according to claim 2, characterized in that, The first constant current source subunit includes at least N parallel-connected first current source branches, where N≥2. Each first current source branch includes a switch and a current source connected in series. The parallel input terminal of the first current source branch serves as the input terminal of the first constant current source subunit, and the parallel output terminal of the first current source branch serves as the output terminal of the first constant current source subunit.
4. The driving circuit for the switching transistor according to claim 2, characterized in that, The second constant current source subunit includes at least M parallel-connected second current source branches, M≥2. Each second current source branch includes a switch and a current source connected in series. The parallel input terminal of the second current source branch serves as the input terminal of the second constant current source subunit, and the parallel output terminal of the second current source branch serves as the output terminal of the second constant current source subunit.
5. The driving circuit for the switching transistor according to claim 1, characterized in that, Also includes: A power supply unit, wherein the input terminal of the power supply unit is connected to the power supply voltage of the switching transistor, and the output terminal of the power supply unit is connected to the power supply terminal of the control unit; Alternatively, a clamping unit, wherein the first end of the clamping unit is connected to the gate of the switching transistor, and the second end of the clamping unit is connected to the source of the switching transistor.
6. The driving circuit for the switching transistor according to claim 1, characterized in that, Also includes: A drain-source voltage detection unit is provided, wherein the first input terminal of the drain-source voltage detection unit is connected to the drain of the switching transistor, the second input terminal of the drain-source voltage detection unit is connected to the source of the switching transistor, and the output terminal of the drain-source voltage detection unit is connected to the input terminal of the control unit, and outputs the drain-source comparison voltage of the switching transistor.
7. The driving circuit for the switching transistor according to claim 6, characterized in that, The drain-source voltage detection unit includes: a first comparator and a second comparator; The non-inverting input of the first comparator serves as the first input of the drain-source voltage detection unit, the inverting input of the first comparator serves as the second input of the drain-source voltage detection unit, and the output of the first comparator is connected to the inverting input of the second comparator. The non-inverting input of the second comparator receives the drain-source threshold voltage of the switching transistor, and the output of the second comparator serves as the output of the drain-source voltage detection unit.
8. The driving circuit for the switching transistor according to claim 1, characterized in that, Also includes: A gate-source voltage detection unit is provided, wherein the first input terminal of the gate-source voltage detection unit is connected to the gate of the switching transistor, the second output terminal of the gate-source voltage detection unit is connected to the source of the switching transistor, and the output terminal of the gate-source voltage detection unit is connected to the input terminal of the control unit, and outputs the gate-source comparison voltage of the switching transistor.
9. The driving circuit for the switching transistor according to claim 8, characterized in that, The gate-source voltage detection unit includes: a third comparator and a fourth comparator; The non-inverting input of the third comparator serves as the first input of the gate-source voltage detection unit, the inverting input of the third comparator serves as the second output of the gate-source voltage detection unit, and the output of the third comparator is connected to the inverting input of the fourth comparator. The input terminal of the fourth comparator receives the gate-source threshold voltage of the switching transistor, and the output terminal of the fourth comparator serves as the output terminal of the gate-source voltage detection unit.
10. An electric motor, characterized in that, It includes at least one half-bridge circuit, the half-bridge circuit including two switching transistors connected in series, the switching transistors being provided with a driving circuit for the switching transistors as described in any one of claims 1-9.