A switching drive device, a switching drive chip and a switching device

Abstract

A switch driving device, a switch driving chip and a switch device, which can reduce the loss of a power switch tube, and improve the EMI problem and voltage stress problem in the conduction or cut-off process of the power switch tube. The switch driving device comprises a first voltage detection circuit, a second voltage detection circuit, a voltage transformation rate detection circuit, a current regulation circuit and a control circuit; the first voltage detection circuit is connected with the control circuit and detects the first electrode voltage of the power switch tube; the second voltage detection circuit is connected with the control circuit and detects the control electrode voltage of the power switch tube; the voltage transformation rate detection circuit is connected with the control circuit and detects the voltage transformation rate of the first electrode of the power switch tube; the control circuit is connected with the current regulation circuit, determines the voltage transformation start time and voltage transformation end time in the conduction or cut-off process of the power switch tube, and adjusts the driving current output by the current regulation circuit by using the voltage transformation rate and a preset driving current value.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and in particular to a switch driver, a switch driver chip, and a switch device. Background Technology

[0002] Power switching devices are transistors that exhibit good conduction and cutoff characteristics under certain conditions. They can be turned on and off by applying a control signal to their control terminal (e.g., the gate), and are widely used in various applications. Metal-oxide-semiconductor (MOS) field-effect transistors, insulated-gate bipolar transistors (IGBTs), and silicon carbide (SiC), as voltage-controlled power switching devices, are used for higher-frequency switching applications due to their low cost and low switching losses.

[0003] like Figure 1 The diagram shows a schematic of a switching circuit composed of MOSFETs Q1 and Q2. The drain of the MOSFET is the first electrode, the source is the second electrode, and the gate is the control electrode of the switch. When it is necessary to control Q1 to conduct, a drive current can be sent to the control electrode of Q1 to control Q1's conduction. Specifically, the conduction process of Q1 can be divided into four stages. Figure 2The diagram shows the changes in gate voltage Vg, drain-source voltage Vds, and drain current Id during the conduction of Q1. When the pulse width modulation (PWM) signal used to control the conduction or turn-off of the MOS field-effect transistor is received, a drive current is input to the control electrode of the MOS transistor, and Q1 enters the first stage t0-t1. At this time, the drive current charges the parasitic capacitance Cgs between the gate and source of Q1 through the gate resistor. As the charging process continues, the gate voltage Vg gradually rises. When the voltage across the parasitic capacitance Cgs reaches the threshold voltage of Q1, Q1 turns on and enters the second stage t1-t2. When Q1 enters the second stage t1-t2, Q1 is in the on state, and the current of the device connected to the drain of Q1 can flow to the drain of Q1. Due to the drain inductance of Q1, the drain current Id of Q1 cannot change abruptly, and the drain current Id of Q1 gradually increases. When the current flowing through the drain of Q1 reaches the maximum current value (load current), it enters the third stage t2-t3. When Q1 is in the third stage t2-t3, the parasitic capacitance Cds between the drain and source of Q1 begins to discharge. As the discharge process of parasitic capacitance Cds continues, the voltage Vds between the drain and source of Q1 gradually decreases. When the parasitic capacitance Cds is completely discharged, the voltage Vds between the drain and source of Q1 drops to zero, and Q1 enters the fourth stage t3-t4. When Q1 enters the fourth stage t3-t4, the driving current continues to charge the parasitic capacitance Cgs. When the voltage of the parasitic capacitance Cgs reaches its maximum value, Q1 exhibits its maximum conduction degree, Q1's internal resistance is at its minimum, Q1 is fully turned on, and the Q1 conduction process ends.

[0004] As can be seen from the conduction process of Q1, when Q1 is in the second stage, the drain current Id of Q1 changes rapidly, and when Q1 enters the third stage, the voltage Vds between the drain and source of Q1 changes rapidly. The faster the switching speed of Q1, the lower the losses generated during the conduction process, the shorter the duration of the second and third stages, and the faster the current and voltage changes. However, the faster the voltage and current changes, the more noise is generated during the switching process, causing serious electromagnetic interference (EMI) problems. Similarly, EMI problems also exist during the cutoff process of Q1, and the faster the switching speed of Q1, the greater the voltage stress on Q1. Summary of the Invention

[0005] This application provides a switch driver device, a switch driver chip, and a switching device to reduce the losses of power switching transistors while improving EMI and voltage stress problems during the power switching transistor's turn-on or turn-off process.

[0006] In a first aspect, this application provides a switch driving device that is connected to a power switching transistor and drives the power switching transistor to turn on or off. The switch driving device includes: a first voltage detection circuit, a second voltage detection circuit, a voltage conversion rate detection circuit, a current regulation circuit, and a control circuit.

[0007] Specifically, a first voltage detection circuit is connected to the control circuit and is used to connect to the first electrode of the power switch transistor, detect the voltage of the first electrode of the power switch transistor, and output the first electrode voltage to the control circuit. The first electrode of the power switch transistor is the electrode that receives a high level. A second voltage detection circuit is connected to the control circuit and is used to connect to the control electrode of the power switch transistor, detect the voltage of the control electrode of the power switch transistor, and output the control electrode voltage to the control circuit. A voltage conversion rate detection circuit is connected to the control circuit and is used to connect to the first electrode of the power switch transistor, detect the voltage conversion rate of the first electrode of the power switch transistor, and output the voltage conversion rate to the control circuit. The control circuit is connected to the current regulation circuit. The control circuit is used to determine the start and end times of voltage conversion during the conduction or cutoff process of the power switch transistor based on the first electrode voltage, and adjusts the drive current output by the current regulation circuit using the voltage conversion rate and a preset drive current value. The current regulation circuit is used to connect to the control electrode of the power switch transistor and provide drive current to the control electrode of the power switch transistor. The voltage conversion rate is the rate of change of voltage amplitude at the first electrode of the power switch transistor per unit time.

[0008] Using the aforementioned switch driving device, taking the conduction process of a MOSFET as an example, during the control of the power switch's on / off process, to mitigate EMI issues caused by noise generated during MOSFET conduction, when the MOSFET's gate voltage reaches the threshold voltage, it is determined that the MOSFET has entered the second stage of current conversion. This can be achieved by reducing the drive current provided to the gate by the current regulation circuit, thereby reducing the MOSFET's current conversion rate and improving the EMI problem in the second stage. When the voltage conversion start time of the MOSFET's conduction process is detected, it is determined that the MOSFET has entered the third stage of voltage conversion. Based on the detection results of the voltage conversion rate detection circuit, it is determined whether the current drain voltage conversion rate meets the EMI requirements. If the requirements are not met, the voltage conversion rate of the MOSFET can be reduced by decreasing the drive current provided to the gate by the current regulation circuit, thereby reducing the MOSFET's voltage conversion rate and improving the EMI problem in the third stage. Similarly, the same method can be used to adjust the value of the drive current during the cutoff process of a MOSFET, thereby improving EMI and voltage stress issues during the cutoff process. For other stages of the conduction or cutoff process, a large drive current can be used to reduce the duration of other stages, thereby accelerating the switching speed of the power switch and reducing its losses.

[0009] In one possible implementation, the current regulation circuit includes: a first current regulation unit and a second current regulation unit.

[0010] The first current regulating unit has a first terminal connected to the power supply, a second terminal connected to the control electrode of the power switch, and a third terminal connected to the control circuit. The first current regulating unit provides drive current to the control electrode of the power switch during the conduction process. The second current regulating unit has a first terminal connected to the control electrode of the power switch, a second terminal grounded, and a third terminal connected to the control circuit. The second current regulating unit provides drive current to the control electrode of the power switch during the cutoff process.

[0011] Using the aforementioned switch drive device, during the conduction process of the power switch, the conduction process of the power switch can be controlled by controlling the drive current output by the first regulating unit. During the cutoff process of the power switch, the cutoff process of the power switch can be controlled by controlling the drive current output by the second regulating unit.

[0012] In one possible implementation, the first current regulating unit includes a plurality of first switches. The second current regulating unit includes a plurality of second switches.

[0013] The first electrode of each first switch is used to connect to the power supply, the second electrode of each first switch is used to connect to the control electrode of the power switch, and the control electrode of each first switch is connected to the control circuit. The first electrode of each second switch is used to connect to the control electrode of the power switch, the second electrode of each second switch is grounded, and the control electrode of each second switch is connected to the control circuit.

[0014] The control circuit is specifically used to: adjust the driving current value provided by the current regulation circuit to the control electrode of the power switch by controlling the number of first switches turned on in the first current regulation unit; or adjust the driving current value provided by the current regulation circuit to the control electrode of the power switch by controlling the number of second switches turned on in the second current regulation unit.

[0015] Using the aforementioned switch driving circuit, by controlling the number of the first switches in the first current regulating unit that are turned on, the total impedance value in the first current regulating unit is controlled, thereby adjusting the driving current value output by the first current regulating unit. Similarly, by controlling the number of the second switches in the second current regulating unit that are turned on, the total impedance value in the second current regulating unit is controlled, thereby adjusting the driving current value output by the second current regulating unit.

[0016] In one possible implementation, the first voltage detection circuit includes a first capacitor and a second capacitor.

[0017] The first terminal of the first capacitor is used to connect to the first electrode of the power switch transistor, and the second terminal of the first capacitor is connected to the control circuit and the first terminal of the second capacitor respectively; the second terminal of the second capacitor is used to ground.

[0018] Using the above-mentioned switch driving device, when the power switch is used in a high-voltage operating scenario, in order to facilitate the detection and control circuit to process the detected voltage, the first capacitor and the second capacitor form a voltage divider circuit to detect the first electrode voltage of the power switch.

[0019] In one possible implementation, the second voltage detection circuit includes a first resistor and a second resistor.

[0020] The first end of the first resistor is used to connect to the control electrode of the power switch transistor, and the second end of the first resistor is connected to the control circuit and the first end of the second resistor respectively; the second end of the second resistor is used to ground.

[0021] Using the above-mentioned switch driving device, when the power switch is used in a high-voltage operating scenario, in order to facilitate the detection and control circuit to process the detected voltage, the first resistor and the second resistor form a voltage divider circuit to detect the control electrode voltage of the power switch.

[0022] In one possible implementation, the voltage conversion rate detection circuit includes a third capacitor and a third resistor.

[0023] The first terminal of the third capacitor is used to connect to the first electrode of the power switch transistor, and the second terminal of the third capacitor is connected to both the control circuit and the first terminal of the third resistor. The second terminal of the third resistor is used to ground.

[0024] Using the aforementioned switch driving device, the third capacitor and the third resistor form a high-pass filter to detect the voltage conversion rate of the first electrode of the power switch.

[0025] In one possible implementation, the control circuit is specifically used to: control the current regulation circuit to output a first preset drive current until the control electrode voltage of the power switch reaches the threshold voltage; control the current regulation circuit to output a second preset drive current until the voltage transformation start time of the power switch conduction process is reached; according to the voltage transformation rate, control the current regulation circuit to output a third preset drive current until the voltage transformation end time of the power switch conduction process is reached; and control the current regulation circuit to output a fourth preset drive current until the power switch conduction process ends.

[0026] By using the aforementioned switch drive device, the control circuit can control the current regulation circuit to output different drive current values ​​at different stages of the power switch conduction process, thereby controlling the voltage conversion rate in the voltage conversion stage and the current conversion rate in the current conversion stage, thus improving the EMI problem during the power switch conduction process.

[0027] In one possible implementation, the control circuit is specifically used to: control the current regulation circuit to output a fifth preset drive current until the voltage transformation start time of the power switch's turn-off process is reached; control the current regulation circuit to output a sixth preset drive current according to the voltage transformation rate until the voltage transformation end time of the power switch's turn-off process is reached; control the current regulation circuit to output a seventh preset drive current until the control electrode voltage of the power switch reaches the threshold voltage; and control the current regulation circuit to output an eighth preset drive current until the power switch's turn-off process ends.

[0028] By using the aforementioned switch drive device, the control circuit can control the current regulation circuit to output different drive current values ​​at different stages of the power switch's turn-off process, thereby controlling the voltage conversion rate in the voltage conversion stage and the current conversion rate in the current conversion stage, thus improving the EMI problem during the power switch's turn-off process.

[0029] In one possible implementation, the control circuit includes a first comparator, a second comparator, and a controller.

[0030] The first comparator has its first input terminal connected to the first voltage detection circuit, its second input terminal for receiving a first reference voltage value, and its output terminal connected to the controller. The second comparator has its first input terminal connected to the first voltage detection circuit, its second input terminal for receiving a second reference voltage value, and its output terminal connected to the controller. The controller is connected to the second voltage detection circuit, the voltage conversion rate detection circuit, and the current regulation circuit. The controller determines the start and end times of voltage conversion during the conduction or cutoff process of the power switch transistor based on the comparison results of the first and second comparators, and adjusts the drive current output by the current regulation circuit using the voltage conversion rate and a preset drive current value.

[0031] In one possible implementation, the switch driving device further includes a reference voltage generation circuit. The reference voltage generation circuit includes a step-down unit, a first sampling unit, and a second sampling unit.

[0032] The step-down unit is connected to the first voltage detection circuit and is used to step down the voltage detected by the first voltage detection circuit to obtain a first reference voltage value and a second reference voltage value. The first sampling unit is connected to the step-down unit and the first comparator and is used to sample the first reference voltage value and output it to the second input terminal of the first comparator. The second sampling unit is connected to the step-down unit and the second comparator and is used to sample the second reference voltage value and output it to the second input terminal of the second comparator.

[0033] The aforementioned switch driving device uses the voltage detected by the first voltage detection circuit to generate a first reference voltage and a second reference voltage, thereby enabling the adjustment of the values ​​of the first and second reference voltages when the power switch is applied to different scenarios, thus ensuring the driving effect.

[0034] In one possible implementation, the step-down unit includes a fourth capacitor, a fifth capacitor, and a sixth capacitor.

[0035] The first terminal of the fourth capacitor is connected to the first voltage detection circuit, and the second terminal of the fourth capacitor is connected to the fifth capacitor and the first sampling unit; the second terminal of the fifth capacitor is connected to the second sampling unit and the first terminal of the sixth capacitor; the second terminal of the sixth capacitor is used for grounding.

[0036] In one possible implementation, the first sampling unit includes a third switch, a seventh capacitor, and a first follower. The first electrode of the third switch is connected to the buck unit, and the second electrode of the third switch is connected to the input terminal of the first follower and the first terminal of the seventh capacitor; the second terminal of the seventh capacitor is grounded; the output terminal of the first follower is connected to the second input terminal of the first comparator.

[0037] The second sampling unit includes a fourth switch, an eighth capacitor, and a second follower. The first electrode of the fourth switch is connected to the step-down unit, and the second electrode of the fourth switch is connected to the input terminal of the second follower and the first terminal of the eighth capacitor; the second terminal of the eighth capacitor is grounded; the output terminal of the second follower is connected to the second input terminal of the second comparator.

[0038] In one possible implementation, the power switch can be a metal-oxide-semiconductor field-effect transistor (MOSFET), an insulated-gate bipolar transistor (IGBT), or silicon carbide (SiC).

[0039] Secondly, this application provides a switch driver chip, which includes the switch driving device provided in the first aspect of this application and any possible design thereof. The switch driver chip is used to connect to a power switch transistor and drive the power switch transistor to drive or cut off.

[0040] Thirdly, this application provides a switching device, the switching circuit, and the switching drive provided in the first aspect of this application and any possible design thereof.

[0041] The switching circuit is used to connect to the power supply and the load, and control the connection between the power supply and the load, or to convert the electrical energy output by the power supply into voltage and output the converted electrical energy to the load; the switching drive device is connected to the switching circuit and is used to provide drive current to a power switch in the switching circuit and drive the power switch to turn on or off. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of a switching circuit provided in an embodiment of this application;

[0043] Figure 2 A schematic diagram of voltage and current waveforms during the driving process of a power switch provided in this application embodiment. Figure 1 ;

[0044] Figure 3 An equivalent schematic diagram of a power switch provided in an embodiment of this application;

[0045] Figure 4 A schematic diagram of the current flow direction of a power switch provided in an embodiment of this application. Figure 1 ;

[0046] Figure 5 A schematic diagram of the current flow direction of a power switch provided in an embodiment of this application. Figure 2 ;

[0047] Figure 6 A schematic diagram of the current flow direction of a power switch provided in an embodiment of this application. Figure 3 ;

[0048] Figure 7 A schematic diagram of the current flow direction of a power switch provided in an embodiment of this application. Figure 4 ;

[0049] Figure 8 A schematic diagram of the voltage and current waveforms of a power switch provided in this application embodiment. Figure 5 ;

[0050] Figure 9 This is a schematic diagram of the structure of a switch driving device provided in an embodiment of this application;

[0051] Figure 10 This is a schematic diagram of the structure of a first voltage detection circuit provided in an embodiment of this application;

[0052] Figure 11 This is a schematic diagram of the structure of a second voltage detection circuit provided in an embodiment of this application;

[0053] Figure 12 This is a schematic diagram of a voltage conversion rate detection circuit provided in an embodiment of this application;

[0054] Figure 13 This is a schematic diagram of a current regulation circuit provided in an embodiment of this application;

[0055] Figure 14 A schematic diagram of the current flow direction of a current regulation circuit provided in this application embodiment. Figure 1 ;

[0056] Figure 15 A schematic diagram of the current flow direction of a current regulation circuit provided in this application embodiment. Figure 2 ;

[0057] Figure 16 A schematic diagram of the current and voltage waveforms during the driving process of a power switch provided in this application embodiment. Figure 2 ;

[0058] Figure 17 A schematic diagram of the current and voltage waveforms during the driving process of a power switch provided in this application embodiment. Figure 3 ;

[0059] Figure 18 This is a schematic diagram of a control circuit provided in an embodiment of this application;

[0060] Figure 19 A schematic diagram of a reference voltage generation circuit provided in an embodiment of this application;

[0061] Figure 20 A schematic diagram of voltage and current waveforms of a power switch provided in an embodiment of this application. Figure 6 ;

[0062] Figure 21 This is a schematic flowchart illustrating the driving process of a power switch transistor as provided in an embodiment of this application. Detailed Implementation

[0063] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. It should be noted that in the description of this application, "at least one" refers to one or more, where "multiple" refers to two or more. Therefore, in the embodiments of this application, "multiple" can also be understood as "at least two". "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / ", unless otherwise specified, generally indicates that the preceding and following related objects have an "or" relationship. Furthermore, it should be understood that in the description of this application, words such as "first" and "second" are only used for distinguishing the purpose of description and should not be construed as indicating or implying relative importance or order.

[0064] It should be noted that in the embodiments of this application, "connection" can be an electrical connection or a communication connection. An electrical connection between two electrical components can be a direct or indirect connection between the two components. For example, a connection between A and B can be a direct connection between A and B, or an indirect connection between A and B through one or more other electrical components, such as a connection between A and B. Alternatively, A can be directly connected to C, and C can be directly connected to B, with A and B connected through C.

[0065] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0066] It should be noted that the power switch in the embodiments of this application is a voltage-controlled switching device, and the power switch can be, but is not limited to, a MOSFET, an IGBT, and SiC. Each power switch can include a first electrode, a second electrode, and a control electrode, wherein the control electrode is used to control the conduction or cutoff of the power switch. When the power switch is on, current can be transferred between the first electrode and the second electrode; when the power switch is off, no current can be transferred between the first electrode and the second electrode. Taking a MOSFET as an example, the control electrode of the power switch is the gate, the first electrode can be the source, and the second electrode can be the drain, or the first electrode can be the drain and the second electrode can be the source.

[0067] To facilitate understanding of the switch driving device, driver chip, and switching equipment provided in the embodiments of this application, their application scenarios will be introduced below.

[0068] Power switching transistors are crucial components in switching circuits and are used within them. Switching circuits can act as intermediaries between the power supply and the load, controlling the connection between them or converting the power supply's output voltage into the load's operating voltage.

[0069] For example, a data center typically contains multiple loads (such as servers). The power grid enters the server room to supply power, usually at a medium voltage (e.g., 10kV) AC. However, the data center's load devices typically require low voltage (e.g., 220V or 400V) DC or AC power as their operating voltage. Therefore, switching circuits are usually installed to convert the power grid voltage to the required voltage level and type for the loads.

[0070] It should be noted that the power supply can be either DC or AC. The load can be either DC or AC powered. When the power supply is DC and the load is DC powered, the switching circuit only has a connection function or performs voltage conversion. When the power supply is AC and the load is DC powered, the switching circuit also has a rectification function.

[0071] In practical applications, the internal structure of a switching circuit varies depending on its function. (See also...) Figure 1 As shown, this is a common switching circuit consisting of two switches connected in series. The switches require a dedicated driver to turn them on or off. Below, we will use a MOSFET as an example to explain the conduction process of a power switching transistor.

[0072] See Figure 3The diagram shown is the equivalent circuit diagram of a MOS field-effect transistor. When the driving device receives the PWM signal used to control the conduction of switch Q1, the conduction process of switch Q1 is mainly divided into four stages.

[0073] In the first stage (t0-t1), the drive voltage output by the driving device is converted into a drive current Ig after passing through the gate resistor Rg. This drive current charges the parasitic capacitance Cgs between the gate G and source S of Q1. When the voltage across the parasitic capacitance Cgs reaches the threshold voltage of Q1, Q1 meets the turn-on condition and enters the second stage (t1-t2). The current flow direction of the switch during the first stage (t0-t1) can be found in [reference needed]. Figure 4 As shown.

[0074] In the second stage, t1-t2, Q1 begins to conduct. At this time, the current in the device connected to the drain D of Q1 starts to flow to the drain D of Q1. Due to the parasitic inductance of the drain of Q1 and the characteristic that inductor current cannot change abruptly, the current Ids flowing from the drain D of Q1 to the source S gradually increases until it reaches its maximum value, i.e., the load current. This marks the beginning of the third stage, t2-t3. The current flow direction of the switch during the second stage, t1-t2, can be found in [reference needed]. Figure 5 As shown.

[0075] In the third stage (t2-t3), the parasitic capacitance Cds between the drain (D) and source (S) of switch Q1 is discharged. As the discharge time of Cds increases, the voltage Vds between the drain (D) and source (S) of switch Q1 gradually decreases until Cds is completely discharged, and the process enters the fourth stage (t3-t4). The current flow direction of the switch during the third stage (t2-t3) can be found in [reference needed]. Figure 6 As shown.

[0076] In the fourth stage, t3-t4, the driving current Ig continues to charge the parasitic capacitance Cgs until Cgs is charged to its maximum voltage. At this point, the conduction degree of switch Q1 is at its maximum, and the internal resistance of switch Q1 is at its minimum, ending the conduction process of Q1. The current flow direction of the switch during the fourth stage, t3-t4, can be found in [reference needed]. Figure 7 As shown.

[0077] As described above regarding the switch conduction process, the current Ids continuously changes during the second stage of switch Q1's conduction, while the voltage Vds continuously changes during the third stage. The shorter the conduction process of switch Q1, the lower its conduction loss, and consequently, the shorter the duration of the second and third stages. When the duration of the second and third stages is shortened, the rate of change of current Ids in the second stage increases, and the rate of change of voltage Vds in the third stage increases. This leads to an increase in the amount of noise generated by the rapid changes in current and voltage, causing serious electromagnetic interference (EMI) problems.

[0078] Additionally, see Figure 8 As shown, the higher the switching speed of Q1, the higher the voltage amplitude of the drain voltage Vd of Q1. Therefore, there is still a voltage stress problem during the conduction and cutoff processes of Q1.

[0079] To address the aforementioned issues, this application provides a switch driver and a switching device that reduces power switch losses while improving EMI and voltage stress during switch on / off processes.

[0080] See Figure 9 The diagram shown is a schematic diagram of the structure of the switch driving device provided in the embodiment of this application. The switch driving device 900 can be connected to the power switch tube and can provide a suitable drive current to the power switch tube during the conduction or cutoff process, thereby reducing the loss of the power switch tube and improving the EMI problem and electrical stress problem generated during the conduction or cutoff process of the power switch tube.

[0081] See Figure 9 As shown, the switch drive device 900 includes: a first voltage detection circuit 901, a second voltage detection circuit 902, a voltage conversion rate detection circuit 903, a current regulation circuit 904, and a control circuit 905.

[0082] The circuit comprises the following components: a first voltage detection circuit 901 connected to the control circuit 905, connected to the first electrode of the power switch transistor, detecting the voltage at the first electrode of the power switch transistor, and outputting the voltage at the first electrode to the control circuit 905; a second voltage detection circuit 902 connected to the control circuit 905, connected to the control electrode of the power switch transistor, detecting the voltage at the control electrode of the power switch transistor, and outputting the voltage at the control electrode to the control circuit 905; and a voltage conversion rate detection circuit 903 connected to the control circuit 905, connected to the drain of the power switch transistor, detecting the voltage conversion rate at the first electrode of the power switch transistor, and outputting the voltage at the first electrode to the control circuit 905. The voltage conversion rate is output to the control circuit 905. The voltage conversion rate is the rate of change of voltage amplitude at the first electrode of the power switch per unit time. The control circuit 905 is connected to the current regulation circuit 904. The control circuit 905 is used to determine the start and end times of voltage conversion during the conduction or cutoff process of the power switch based on the voltage at the first electrode. It also adjusts the current value output by the current regulation circuit 904 using the voltage conversion rate of the power switch and a preset drive current value. The current regulation circuit 904 is connected to the control electrode of the power switch and provides drive current to the control electrode. The first electrode of the power switch is the electrode that receives a high-level voltage.

[0083] It should be understood that the current regulation circuit 904 is connected to the control electrode of the power switch transistor. The control circuit 905 can adjust the value of the drive current output to the control electrode of the power switch transistor through the current regulation circuit 904. When the drive current changes, the duration of the power switch transistor's conduction or cutoff process is different, and the electrical parameters of the power switch transistor also change during the conduction and cutoff processes.

[0084] When the switching drive device 900 provided in this application drives the power switch to turn on or off, the second voltage detection circuit 902 can detect the control electrode voltage of the power switch. When it is determined that the control electrode voltage reaches the threshold voltage, it can be determined that the power switch has entered the second stage of large current change. The control circuit 905 can control the current regulation circuit 904 to reduce the current to the driving current value output by the control electrode of the power switch, thereby reducing the conduction degree of the power switch. The conversion rate of the current Ids flowing between the drain and source of the power switch is reduced, thereby reducing the amount of noise generated in the second stage and improving the EMI problem caused by the large current change in the second stage. The control circuit uses the first voltage detection circuit 901 to detect the voltage value of the first electrode. When it determines that the voltage transformation starts during the conduction or cutoff process of the power switch, it determines that the second stage of the conduction process of the power switch ends and enters the third stage of large voltage transformation. The control circuit 905 determines whether the voltage transformation rate detected by the voltage transformation rate detection circuit 903 meets the EMI requirements. When it is determined that the current voltage transformation rate will generate a large amount of noise and cannot meet the EMI requirements, it can control the current regulation circuit 904 to reduce the driving current value output to the control electrode of the power switch, thereby reducing the conduction degree of the power switch, reducing the discharge index of the parasitic capacitance Cds between the drain and source of the power switch, thereby reducing the voltage transformation rate of voltage Vds, thereby reducing the amount of noise generated and improving the EMI problem caused by the large voltage transformation in the third stage.

[0085] It should be understood that when the switch driving device 900 provided in the embodiments of this application drives the power switch to be turned on or off, the voltage transformation amplitude and current transformation amplitude during the voltage transformation stage can be controlled, thereby controlling the first electrode voltage of the power switch and thus improving the voltage stress problem during the conduction or cutoff process.

[0086] In addition, for other stages of the power switch's conduction or cutoff process, a large drive current can be provided to the power switch to reduce the occupation time of other stages, thereby accelerating the switching speed of the power switch and improving EMI and voltage stress issues during the power switch's conduction or cutoff process while reducing power switch losses.

[0087] In practical applications, the shorter the duration of the conduction and cutoff processes of the power switch, the lower its conduction or cutoff losses. To reduce the power loss generated during the conduction or cutoff processes, the control circuit 905 can control the current regulation circuit to increase the output current in other stages of the conduction or cutoff processes of the power switch, thereby reducing the duration of other stages and increasing the duration of the conduction or cutoff processes of the power switch, thus reducing the conduction or cutoff losses of the power switch.

[0088] In practical applications, the switch driver 900, as a device that drives the power switch to turn on or off, can be fixedly connected to the power switch. In another implementation, the switch driver 900 can be set to a flexible and detachable form. For example, the switch driver 900 is provided with a fixed interface, through which the power switch can be connected to the switch driver 900. In this case, the switch driver 900 can be regarded as a device independent of the power switch.

[0089] The first voltage detection circuit 901, the second voltage detection circuit 902, the voltage conversion rate detection circuit 903, the current regulation circuit 904, and the control circuit 905 in the switch drive device 900 will be described in detail below.

[0090] I. First Voltage Detection Circuit 901

[0091] The first voltage detection circuit 901 is connected to the control circuit 905 and is used to connect to the first electrode of the power switch transistor to detect the voltage of the first electrode of the power switch transistor and output the first electrode voltage to the control circuit 905.

[0092] The first voltage detection circuit 901 includes a first capacitor and a second capacitor. The first terminal of the first capacitor is connected to the first electrode of the power switch transistor, and the second terminal of the first capacitor is connected to both the control circuit 905 and the first terminal of the second capacitor; the second terminal of the second capacitor is grounded.

[0093] The purpose of setting the first capacitor and the second capacitor is as follows: Since the power supply amplitude connected to the switching circuit where the power switch is located may be high, in order to facilitate the control circuit 905 to process the detected first electrode voltage of the power switch, the first capacitor and the second capacitor can form a voltage divider circuit to reduce the voltage of the first electrode of the power switch so that the control circuit can perform high voltage detection through the first voltage detection circuit 901.

[0094] For ease of understanding, a specific example of the structure of the first voltage detection circuit 901 is given below.

[0095] See Figure 10 This is a schematic diagram of the structure of the first voltage detection circuit 901 provided in an embodiment of this application. Figure 10 In this diagram, C1 can be considered as the first capacitor, and C2 can be considered as the second capacitor.

[0096] Figure 10 The connection relationship of each device in the first voltage detection circuit 901 shown can be as follows: the first end of C1 is connected to the first electrode of the power switch tube, the second end of C1 is connected to the first end of the control circuit 905 and C2 respectively, and the second end of C2 is grounded.

[0097] pass Figure 10 When the first voltage detection circuit 901 shown detects the first electrode voltage of the power switch transistor, the first end of C1 can be used as the input end of the first voltage detection circuit 901, and the second end of C1 can be used as the output end of the first voltage detection circuit 901. Energy is transmitted from right to left, and the first electrode voltage of the left power switch transistor is stepped down and then output to the control circuit 905.

[0098] It should be understood that when the switching circuit is applied to different scenarios, the drain voltage of the power switch tube is different. In order to facilitate the sampling of the first electrode voltage by the first voltage detection circuit 901 and the processing of the detected first electrode voltage by the control circuit 905, C1 and C2 can form a voltage divider circuit to divide the first electrode voltage of the power switch tube and output the first voltage after voltage division to the control circuit 905.

[0099] It should be understood that the above description of the first voltage detection circuit 901 is for illustrative purposes only. In actual use, the first voltage detection circuit 901 can also adopt other circuit structures. For example, the first voltage detection circuit 901 includes two series-connected voltage divider resistors, which form a voltage divider circuit to divide the first electrode voltage of the power switch transistor and output the divided first electrode voltage to the control circuit 905.

[0100] II. Second Voltage Detection Circuit 902

[0101] The second voltage detection circuit 902 is connected to the control circuit 905 and is used to connect to the control electrode of the power switch transistor, detect the control electrode voltage of the power switch transistor, and output the control electrode voltage to the control circuit 905.

[0102] The second voltage detection circuit 902 includes a first resistor and a second resistor. The first end of the first resistor is connected to the control electrode of the power switch transistor, and the second end of the first resistor is connected to both the control circuit 905 and the first end of the second resistor; the second end of the second resistor is grounded.

[0103] The purpose of setting the first resistor and the second resistor is as follows: Since the voltage amplitude of the control voltage of the power switch may be high, in order to facilitate the control circuit to collect the control electrode voltage of the power switch, the first resistor and the second resistor can form a voltage divider circuit to reduce the voltage of the control electrode of the power switch so that the control circuit can perform high voltage detection through the second voltage detection circuit 902.

[0104] For ease of understanding, a specific example of the structure of the second voltage detection circuit 902 is given below.

[0105] See Figure 11 This is a schematic diagram of the structure of the second voltage detection circuit 902 provided in an embodiment of this application. Figure 11 In this circuit, R1 can be considered as the first resistor, and R2 can be considered as the second resistor.

[0106] Figure 11 The connection relationship of each device in the second voltage detection circuit 902 shown can be as follows: the first end of R1 is used to connect to the control electrode of the power switch tube, the second end of R1 is connected to the control circuit 905 and the first end of R2 respectively; the second end of R2 is used to ground.

[0107] pass Figure 11 When the second voltage detection circuit 902 shown detects the control electrode voltage of the power switch, the first end of R1 can be used as the input end of the second voltage detection circuit 902, and the second end of R1 can be used as the output end of the second voltage detection circuit 902. Energy is transmitted from right to left, and the control electrode voltage of the left power switch is stepped down and then output to the control circuit 905.

[0108] It should be understood that when the switching circuit is applied to different scenarios, the detected control voltage of the power switch is different. In order to facilitate the second voltage detection circuit 902 to sample the first electrode voltage and the control circuit 905 to process the detected control electrode voltage, R1 and R2 can form a voltage divider circuit to divide the control electrode voltage of the power switch and output the divided control voltage to the control circuit 905.

[0109] It should be understood that the above description of the second voltage detection circuit 902 is for illustrative purposes only. In actual use, the second voltage detection circuit 902 can also adopt other circuit structures. For example, the second voltage detection circuit 902 includes two series-connected voltage-dividing capacitors, which form a voltage divider circuit to divide the control electrode voltage of the power switch transistor and output the divided control electrode voltage to the control circuit 905.

[0110] III. Voltage Transformation Rate Detection Circuit 903

[0111] The voltage conversion rate detection circuit 903 is connected to the control circuit 905 and is used to connect to the first electrode of the power switch transistor to detect the voltage conversion rate of the first electrode of the power switch transistor and output the voltage conversion rate to the control circuit 905.

[0112] The voltage conversion rate detection circuit 903 includes a third capacitor and a third resistor. The first terminal of the third capacitor is connected to the first electrode of the power switch transistor, and the second terminal of the third capacitor is connected to both the control circuit 905 and the first terminal of the third resistor; the second terminal of the third resistor is grounded.

[0113] The function of setting the third capacitor and the third resistor is as follows: the third capacitor and the third resistor form a high-pass filter, which is used to detect the voltage conversion rate of the first electrode of the power switch, and output the detected voltage conversion rate to the control circuit 905.

[0114] To facilitate understanding, a specific example of the voltage conversion rate detection circuit 903 is given below.

[0115] See Figure 12 This is a schematic diagram of the voltage conversion rate detection circuit 903 provided in an embodiment of this application. Figure 12 In this diagram, C3 can be considered as the third capacitor, and R3 can be considered as the third resistor.

[0116] Figure 12 The connection relationship of each device in the voltage conversion rate detection circuit 903 shown can be as follows: the first end of C3 is used to connect to the first electrode of the power switch tube, the second end of C3 is connected to the control circuit 905 and the first end of R3 respectively; the second end of R3 is used to ground.

[0117] pass Figure 12 When the voltage conversion rate detection circuit 903 shown detects the voltage conversion rate of the first electrode of the power switch, the first terminal of C3 can be used as the input terminal of the voltage conversion rate detection circuit 903, and the second terminal of C3 can be used as the output terminal of the voltage conversion rate detection circuit 903. Energy is transmitted from right to left. C3 and R3 form a high-pass filter to detect the voltage conversion rate of the first electrode of the power switch and output the voltage conversion rate to the control circuit 905.

[0118] It should be understood that the above description of the voltage conversion rate detection circuit 903 is for illustrative purposes only. In actual use, the voltage conversion rate detection circuit 903 can also adopt other circuit structures. For example, the voltage conversion rate detection circuit 903 can include N timers and N voltage detectors, with the N timers and N voltage detectors corresponding to each other. The N timers have different timing durations and different start times. When each timer finishes timing, it controls the corresponding voltage detector to collect the first electrode voltage of the power switch. The control circuit 905 can use the first electrode voltages collected at different times by multiple timers to calculate the first electrode voltage conversion rate of the power switch.

[0119] IV. Current Adjustment Circuit 904

[0120] The current regulation circuit 904 is connected to the control circuit 905. The current regulation circuit 904 is connected to the control electrode of the power switch and provides drive current to the control electrode of the power switch under the control of the control circuit 905 to drive the power switch to turn on or off.

[0121] The current regulation circuit 904 includes: a first current regulation unit and a second current regulation unit.

[0122] Specifically, the first end of the first current regulating unit is connected to the power supply, the second end of the first current regulating unit is connected to the control electrode of the power switch, and the third end of the first current regulating unit is connected to the control circuit 905. The first current regulating unit is used to provide drive current to the control electrode of the power switch during the conduction process of the power switch. The first end of the second current regulating unit is connected to the control electrode of the power switch, the second end of the second current regulating unit is grounded, and the third end of the second current regulating unit is connected to the control circuit 905. The second current regulating unit is used to provide drive current to the control electrode of the power switch during the cutoff process of the power switch.

[0123] The functions of the first current regulating unit and the second current regulating unit are as follows: the first current regulating unit is used to provide a driving current to the control electrode of the power switch during the conduction process of the power switch, thereby controlling the conduction process of the power switch; the second current regulating unit is used to provide a driving current to the control electrode of the power switch during the cutoff process of the power switch, thereby controlling the cutoff process of the power switch.

[0124] The specific structures of the first current regulating unit and the second current regulating unit are given below.

[0125] Specifically, the first current regulating unit includes a plurality of first switches. The second current regulating unit includes a plurality of second switches.

[0126] In this circuit, the first electrode of each first switch is used to connect to the power supply, the second electrode of each first switch is used to connect to the control electrode of the power switch, and the control electrode of each first switch is connected to the control circuit 905; the first electrode of each second switch is used to connect to the control electrode of the power switch, the second electrode of each second switch is used to ground, and the control electrode of each second switch is connected to the control circuit 905.

[0127] In practical use, multiple first switches are connected between the power supply and the control electrode of the power switching transistor, and each first switch has internal resistance. Therefore, the multiple first switches can serve as driving resistors for the power switching transistor. During the power switching transistor's conduction process, the control circuit 905 can control the number of first switches in the first current adjustment unit, thereby changing the number of parallel first switches on the path between the power supply and the power switching transistor. When the number of parallel first switches changes, their parallel resistance also changes, thus changing the magnitude of the driving current output by the power supply to the power switching transistor's control circuit, thereby controlling the conduction process of the power switching transistor. Similarly, during the power switching transistor's cutoff process, the control circuit 905 can control the number of second switches in the second current adjustment unit, thereby changing the number of parallel second switches on the path between the power switching transistor's control circuit and the ground wire. When the number of parallel second switches changes, the discharge resistance of the parasitic capacitance Cgs between the power switching transistor's control electrode and the source S changes, thereby controlling the power switching transistor's cutoff process.

[0128] It should be understood that the number of the first switch and the second switch in the first current regulation unit and the second current regulation unit can be set according to the drive requirements and the EMI of the switching circuit connection equipment. Furthermore, the first switch and the second switch can be voltage-controlled switching devices.

[0129] For ease of understanding, a specific example of the current regulation circuit 904 is given below.

[0130] See Figure 13 This is a schematic diagram of a current regulation circuit 904 provided in an embodiment of this application. Figure 13 In this diagram, K1 can be considered as the first switch, and K2 can be considered as the second switch. N switches K1 constitute the first current regulating unit, and N switches K2 constitute the second current regulating unit. Here, N is a natural number greater than 1.

[0131] Figure 13 The connection relationship of each device in the current regulation circuit 904 shown can be as follows: the first electrode of each K1 is used to connect to the power supply, the second electrode of each K1 is used to connect to the control electrode of the power switch, and the control electrode of each K1 is connected to the control circuit 905; the first electrode of each K2 is used to connect to the control electrode of the power switch, the second electrode of each K2 is used to ground, and the control electrode of each K2 is connected to the control circuit 905.

[0132] In practical applications, during the conduction process of the power switch, the drive current flows from the power supply to the control electrode of the power switch. The direction of the current flow can be found in [reference needed]. Figure 14As shown. During the turn-off process of the power switch, the drive current flows from the control electrode of the power switch to ground; the direction of the current flow can be found in [reference needed]. Figure 15 As shown.

[0133] It should be understood that since the conduction and cutoff processes of the power switch are two different operations, when the power switch is turned on, all the second switches in the second current regulation unit are in the off state. Similarly, when the power switch is turned off, all the first switches in the first current regulation unit are in the off state.

[0134] When the current regulating circuit 904 provided in this application is used to regulate the magnitude of the driving current, the control electrodes of the multiple first switches and the multiple second switches are all connected to the control circuit 905 and receive the driving signal sent by the control circuit 905 to turn on or off, thereby changing the number of parallel switches in the path through which the driving current flows, thereby changing the resistance value in the path through which the driving current flows, and thus adjusting the output driving current value.

[0135] V. Control Circuit 905

[0136] The control circuit 905 is connected to the first voltage detection circuit 901, the second voltage detection circuit 902, the voltage conversion rate detection circuit 903, and the current adjustment circuit 904, respectively. The control circuit can receive the first electrode voltage of the power switch tube output by the first voltage detection circuit, the control electrode voltage of the power switch tube output by the second voltage detection circuit 902, and the voltage conversion rate output by the voltage conversion rate detection circuit. Based on the received multiple values, the control circuit determines the time corresponding to each stage of the power switch tube's conduction or cutoff process, and adjusts the drive current value of the power switch tube at each stage through the current adjustment unit to control the conduction or cutoff process of the power switch tube.

[0137] The following is combined with Figure 13 The process of controlling the power converter via the 905 control circuit is explained.

[0138] The first phase, t0-t1, see [link / reference] Figure 16 As shown, after receiving the PWM signal used to control the power switch to turn on, the control circuit 905 sends a drive signal to multiple first switches K1 in the current regulation circuit 904 to drive K1 to turn on. After passing through multiple turned-on K1s, the power supply outputs a first preset drive current IR1 until the control electrode voltage value of the power switch reaches the threshold voltage VR1. This determines that the first stage t0-t1 of the power switch conduction process ends and the second stage t1-t2 of rapid current conversion begins.

[0139] Optionally, accelerating the turn-on speed of the power switch can shorten the duration of the first stage t0-t1, i.e., the first preset drive current IR1 is the maximum drive current, i.e., all K1 in the first current regulation unit is turned on. At this time, the parallel resistance of multiple K1 is the minimum, thereby achieving rapid entry into the second stage t1-t2.

[0140] In the second stage t1-t2, based on the EMI requirements of the equipment connected to the switching circuit where the power switch is located, a second preset drive current IR2 is determined. The number of K1 transistors turned on is determined based on this second preset drive current IR2, and the difference between this number and the number of K1 transistors turned on in the first stage t0-t1 is determined. A control signal is sent to the number of K1 transistors turned on by this difference to control the number of K1 transistors turned off, thereby reducing the number of K1 transistors turned on. This causes the current output of the current regulating circuit 904 to decrease from the first preset drive current IR1 to the second preset drive current IR2, thus slowing down the conduction rate of the power switch during the second stage t1-t2, which involves large current changes, thereby reducing the current conversion speed in the second stage t1-t2 and improving the EMI problem in the second stage t1-t2. When the first voltage detection circuit 901 detects the voltage and determines the voltage conversion start time of the conduction process, the third stage t2-t3 begins. At this time, the control electrode voltage value of the power switch reaches VR2. The voltage conversion start time is the start time of the third stage t2-t3. See [link to relevant documentation]. Figure 17 As shown.

[0141] In practice, the conduction characteristics of the power switch can be used to determine the first reference voltage value VREF1 of the power converter corresponding to the start time of voltage conversion. After receiving the first electrode voltage output by the first voltage detection circuit 901, the control circuit 905 compares the received first electrode voltage with the first reference voltage value VREF1. When the amplitude of the received first electrode voltage is equal to or lower than the first reference voltage value VREF1, the start time of voltage conversion in the conduction process is determined, that is, the start time of the third stage t2-t3.

[0142] Optionally, see Figure 18 As shown, the control circuit includes a first comparator G1 and a controller. The first input terminal of the first comparator is connected to the first voltage detection circuit 901. The second input terminal of the first comparator is used to receive the first reference voltage value VREF1. The output terminal of the first comparator is connected to the controller. The controller can determine whether the power switch has entered the third stage t2-t3 of the rapid voltage conversion based on the comparison result.

[0143] It should be understood that since the first electrode voltage output by the first voltage detection circuit 901 is a voltage that has been divided, when comparing the received voltage with the first reference voltage value VREF1, the first reference voltage value VREF1 needs to be proportionally stepped down to ensure the accuracy of the detection result.

[0144] In the third stage t2-t3, the voltage conversion rate output by the voltage conversion rate detection circuit 903 is received, and it is determined whether the voltage conversion rate meets the EMI requirements of the equipment connected to the switching circuit where the power switch is located. If it is determined that the voltage conversion rate does not meet the EMI requirements, a third preset drive current IR3 is determined based on the voltage conversion rate and the EMI requirements. The number of K1s turned on is determined based on the third preset drive current IR3, and the difference between the number of K1s turned on and the number of K1s turned on in the second stage t1-t2 is determined. A control signal is sent to the number of K1s turned on by the difference to control the number of K1s turned off, thereby reducing the number of K1s turned on. As a result, the current output by the current regulation circuit 904 is reduced from the second preset drive current IR2 to the third preset drive current IR3. This slows down the conduction rate of the power switch in the third stage t2-t3, where the voltage changes significantly, thereby reducing the voltage conversion rate between the first and second electrodes of the power switch Vds, thus reducing the voltage conversion speed of the first electrode voltage and improving the EMI problem in the third stage t2-t3. When the voltage detected by the first voltage detection circuit 901 determines that the voltage transformation has reached the end time of the conduction process, the fourth stage t3-t4 begins, at which point the control electrode voltage of the power switch reaches VR3. The end time of the voltage transformation is the end time of the third stage t3-t4.

[0145] In practice, the conduction characteristics of the power switch can be used to determine the second reference voltage value VREF2 of the power converter at the end of the voltage conversion. After receiving the first electrode voltage output by the first voltage detection circuit 901, the control circuit 905 compares the received first electrode voltage with the second reference voltage value VREF2. When the amplitude of the received first electrode voltage is equal to or lower than the second reference voltage value VREF2, the end time of the voltage conversion during the conduction process is determined, that is, the end time of the third stage t2-t3.

[0146] Optionally, see Figure 18 As shown, the control circuit includes a second comparator G2. The first input terminal of the second comparator is connected to the first voltage detection circuit 901. The second input terminal of the second comparator is used to receive the second reference voltage value VREF2. The output terminal of the second comparator is connected to the controller. The controller can determine whether the third stage of the rapid voltage conversion has ended based on the comparison result.

[0147] It should be understood that since the first electrode voltage output by the first voltage detection circuit 901 is a voltage that has been divided, when comparing the received voltage with the second reference voltage value VREF2, the second reference voltage value VREF2 needs to be proportionally stepped down to ensure the accuracy of the detection result.

[0148] Optionally, when the switching circuit containing the power switch is used in a specific scenario, the amplitude of the power supply connected to the switching circuit is fixed. Therefore, the amplitudes of the first reference voltage value VREF1 and the second reference voltage value VREF2 are fixed, and a fixed power supply can be used to provide the amplitudes of the first reference voltage value VREF1 and the second reference voltage value VREF2.

[0149] Optionally, to allow the switching circuit containing the power switch to be used in different scenarios, the switch driver 900 also includes a reference voltage generation circuit. Specifically, the reference voltage generation circuit includes a buck unit, a first sampling unit, and a second sampling unit.

[0150] The step-down unit is connected to the first voltage detection circuit and is used to step down the voltage detected by the first voltage detection circuit to obtain a first reference voltage value and a second reference voltage value. The first sampling unit is connected to the step-down unit and the first comparator and is used to sample the first reference voltage value and output it to the second input terminal of the first comparator. The second sampling unit is connected to the step-down unit and the second comparator and is used to sample the second reference voltage value and output it to the second input terminal of the second comparator.

[0151] For practical use, please refer to Figure 19 As shown, the step-down unit includes a fourth capacitor C4, a fifth capacitor C5, and a sixth capacitor C6; the first sampling unit includes a third switch K3, a seventh capacitor C7, and a first follower G4; the second sampling unit includes a fourth switch K4, an eighth capacitor C8, and a second follower G4.

[0152] Specifically, the first terminal of the fourth capacitor C4 is connected to the first voltage detection circuit 901; the second terminal of the fourth capacitor C4 is connected to the fifth capacitor C5 and the third switch K3; the second terminal of the fifth capacitor C5 is connected to the fourth switch K4 and the first terminal of the sixth capacitor C6; the second terminal of the sixth capacitor C6 is grounded; the second electrode of the third switch K3 is connected to the input terminal of the first follower G3 and the first terminal of the seventh capacitor C7; the second terminal of the seventh capacitor C7 is grounded; the output terminal of the first follower G3 is connected to the second input terminal of the first comparator G1; the second electrode of the fourth switch K4 is connected to the input terminal of the second follower G2 and the first terminal of the eighth capacitor C8; the second terminal of the eighth capacitor C8 is grounded; the output terminal of the second follower G4 is connected to the second input terminal of the second comparator G2.

[0153] It should be understood that when the application scenario of the switching circuit changes, causing the first electrode voltage of the power switch to change, the buck circuit proportionally converts the first electrode voltage of the power switch to obtain the first reference voltage value and the second reference voltage value, thereby enabling the adaptive modification of the first reference voltage value and the second reference voltage value according to the application scenario.

[0154] In the fourth stage t3-t4, the number of K1 transistors turned on is determined according to the fourth preset drive current IR4, and the difference between this number and the number of K1 transistors turned on in the third stage t2-t3 is determined. A control signal is sent to the number of K1 transistors turned on according to this difference to control the number of K1 transistors turned on, thereby increasing the number of K1 transistors turned on. This causes the current output by the current regulating circuit 904 to increase from the third preset drive current IR3 to the fourth preset drive current IR4. When the voltage output by the second voltage detection circuit 902 reaches the highest voltage VR4 of the control electrode, the power switch is fully turned on and the internal resistance of the power switch is at its minimum. At this time, the conduction process of the power switch ends.

[0155] Optionally, in order to speed up the turn-on speed of the power switch, the duration of the fourth stage t3-t4 can be shortened, that is, the fourth preset drive current IR4 is equal to the first preset drive current IR1 as the maximum drive current, so as to realize the end of the conduction process.

[0156] It should be understood that, since the drive current can be controlled at each stage of the power switch's conduction process, the voltage across the power switch can be effectively controlled, thus effectively improving the voltage stress problem during conduction.

[0157] For practical use, see Figure 20 As shown, when the application scenario of the switching circuit containing the power switch is different, the load of the switching circuit is different, and the loss value of the power switch during the conduction and cutoff processes is also different. For example, when the switching circuit is an inverter circuit, the load current of the switching circuit is variable, that is, the current of the power switch is constantly changing. For non-fixed load conditions as mentioned above, the drive current value at each stage can be adjusted according to the load size, thereby meeting the requirements for voltage stress and loss regulation.

[0158] Specifically, the voltage rises rapidly under heavy load during the turn-off process of the power switch, posing a risk of voltage stress. However, the voltage rises slowly under light load. Therefore, the voltage change amplitude of the switch under light and heavy load can be controlled, thereby solving the problem between loss and voltage stress.

[0159] It should be understood that the cutoff process t5-t9 of the power switch is the discharge process of the parasitic capacitance Cgs of the control electrode of the power converter. Therefore, the number of K2 conducting in the current regulation unit can be controlled, thereby adjusting the discharge resistance of the parasitic capacitance Cgs and the amplitude of the driving current during the discharge process of the parasitic capacitance Cgs, so as to control the cutoff process of the power converter. Its working principle is the same as that of the conduction process, and will not be repeated here.

[0160] In actual use, the current regulation circuit 904 is composed of switching transistors, and the drive current value output by the current regulation circuit 904 can be achieved by adjusting the operating state of these switching transistors.

[0161] In this application, the operating state of the above-mentioned device can be adjusted by a controller.

[0162] In actual use, the controller can be connected to the control electrode of the switch in the current regulation circuit 904, and by providing a drive signal to the switch in the current regulation circuit 904, it can control the on-time and on-duration of the switch, thereby controlling the value of the drive current output by the current regulation circuit 904.

[0163] Specifically, if the switching transistor of the current regulating circuit 904 is a MOS field-effect transistor, the controller in the control circuit can be connected to the gate of the MOS field-effect transistor. The number of switches turned on in the current regulating circuit 904 is controlled by turning the MOS field-effect transistor on and off, thereby adjusting the value of the drive current output by the current regulating circuit 904.

[0164] In practice, the controller can be any of the following: microcontroller unit (MCU), central processing unit (CPU), field-programmable gate array (FPGA), or digital signal processor (DSP). Of course, the specific form of the controller is not limited to the examples mentioned above.

[0165] Based on the above introduction, the working process of the control circuit driving the power switching transistor is as follows: Figure 21 As shown, see Figure 21 As shown, the driving process of the control circuit may include the following steps:

[0166] Step 2101: When a PWM signal is received and the amplitude of the PWM signal is high, the control current regulation circuit outputs a first preset drive current until the control electrode voltage of the power switch reaches the threshold voltage, and then executes step 2102.

[0167] Step 2102: Control the current regulation circuit to output the second preset drive current until the voltage transformation start time of the power switch tube conduction process is reached, and then execute step 2103.

[0168] Step 2103: Based on the voltage conversion rate, control the current regulation circuit to output the third preset drive current until the voltage conversion ends during the power switch's conduction process, then execute step 2104.

[0169] Step 2104: Control the current regulation circuit to output the fourth preset drive current until the power switch tube conduction process ends, then execute step 2105.

[0170] Step 2105: When it is determined that the amplitude of the PWM signal drops to zero, the control current regulation circuit outputs the fifth preset drive current until the voltage transformation start time of the power switch tube cutoff process is reached, and then step 2106 is executed.

[0171] Step 2106: Based on the voltage conversion rate, control the current regulation circuit to output the sixth preset drive current until the voltage conversion ends during the power switch's turn-off process, then execute step 2107.

[0172] Step 2107: Control the current regulation circuit to output the seventh preset drive current until the control electrode voltage of the power switch reaches the threshold voltage, and then execute step 2108.

[0173] Step 2108: Control the current regulation circuit to output the eighth preset drive current until the power switch transistor is turned off.

[0174] Step 2109: Check if the PWM signal has been received again. If yes, proceed to step 2101; otherwise, proceed to step 2110.

[0175] Step 2110: Keep the power switch in the off state.

[0176] Based on the same concept, embodiments of this application provide a switch drive signal, wherein the switch drive chip includes the aforementioned switch drive device 900. The switch drive chip is used to connect to a power switch transistor and drive the power switch transistor to drive or cut off.

[0177] Based on the same concept, embodiments of this application provide a switching device, which includes a switching circuit and the aforementioned switch driving device 900.

[0178] The switching circuit is used to connect to the power supply and the load, and control the connection between the power supply and the load, or to convert the electrical energy output by the power supply into voltage and output the converted electrical energy to the load; the switching drive device is connected to the switching circuit and is used to provide drive current to a power switch in the switching circuit and drive the power switch to turn on or off.

[0179] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0180] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to this application. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0181] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0182] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0183] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the scope of protection of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A switch driving device, characterized in that, For connection with a power switching transistor, the switching drive device includes: a first voltage detection circuit, a second voltage detection circuit, a voltage conversion rate detection circuit, a current regulation circuit, and a control circuit; The first voltage detection circuit is connected to the control circuit and is used to connect to the first electrode of the power switch transistor, detect the voltage of the first electrode of the power switch transistor, and output the first electrode voltage to the control circuit; the first electrode of the power switch transistor is the electrode at which the power switch transistor receives a high level. The second voltage detection circuit is connected to the control circuit and is used to connect to the control electrode of the power switch transistor, detect the control electrode voltage of the power switch transistor, and output the control electrode voltage to the control circuit. The voltage conversion rate detection circuit is connected to the control circuit and is used to connect to the first electrode of the power switch transistor. It is used to detect the voltage conversion rate of the first electrode of the power switch transistor and output the voltage conversion rate to the control circuit. The voltage conversion rate is the rate of change of voltage amplitude of the first electrode of the power switch transistor per unit time. The control circuit is connected to the current regulation circuit and is used to determine the start time and end time of voltage transformation during the conduction or cutoff process of the power switch tube based on the first electrode voltage, and to adjust the drive current output by the current regulation circuit using the voltage transformation rate and the preset drive current value. The current regulation circuit is used to connect to the control electrode of the power switch and to provide drive current to the control electrode of the power switch. The current regulation circuit includes: a first current regulation unit and a second current regulation unit; The first current regulation unit is used to provide drive current to the control electrode of the power switch during the conduction process of the power switch. The second current regulation unit is used to provide drive current to the control electrode of the power switch during the turn-off process of the power switch. The first current regulating unit includes: a plurality of first switches; The first electrode of each first switch is used to connect to the power supply, the second electrode of each first switch is used to connect to the control electrode of the power switch tube, and the control electrode of each first switch is connected to the control circuit. The second current regulating unit includes: a plurality of second switches; The first electrode of each second switch is used to connect to the control electrode of the power switch tube, the second electrode of each second switch is used to ground, and the control electrode of each second switch is connected to the control circuit. The control circuit is specifically used to: adjust the driving current value provided by the current regulation circuit to the control electrode of the power switch transistor by controlling the number of first switches turned on in the first current regulation unit; and By controlling the number of second switches turned on in the second current regulation unit, the driving current value provided by the current regulation circuit to the control electrode of the power switch tube is adjusted.

2. The switch driving device as described in claim 1, characterized in that, The first end of the first current regulating unit is used to connect to the power supply, the second end of the first current regulating unit is used to connect to the control electrode of the power switching transistor, and the third end of the first current regulating unit is connected to the control circuit. The first end of the second current regulating unit is used to connect to the control electrode of the power switch, the second end of the second current regulating unit is used to ground, and the third end of the second current regulating unit is connected to the control circuit.

3. The switch driving device as described in claim 1 or 2, characterized in that, The second voltage detection circuit includes: a first resistor and a second resistor; The first end of the first resistor is used to connect to the control electrode of the power switch, and the second end of the first resistor is connected to the control circuit and the first end of the second resistor, respectively. The second end of the second resistor is used for grounding.

4. The switch driving device according to any one of claims 1-3, characterized in that, The voltage conversion rate detection circuit includes: a third capacitor and a third resistor; The first terminal of the third capacitor is used to connect to the first electrode of the power switch transistor, and the second terminal of the third capacitor is connected to the control circuit and the first terminal of the third resistor, respectively. The second end of the third resistor is used for grounding.

5. The switch driving device according to any one of claims 1-4, characterized in that, The control circuit is specifically used for: The current regulation circuit is controlled to output a first preset drive current until the control electrode voltage of the power switch reaches the threshold voltage. The current regulation circuit is controlled to output a second preset drive current until the voltage transformation start time of the power switch tube conduction process is reached; According to the voltage conversion rate, the current regulation circuit is controlled to output a third preset drive current until the voltage conversion ends during the conduction process of the power switch. The current regulation circuit is controlled to output a fourth preset drive current until the power switch tube conduction process ends.

6. The switch driving device according to any one of claims 1-5, characterized in that, The control circuit is specifically used for: The current regulation circuit is controlled to output a fifth preset drive current until the voltage transformation start time of the power switch tube's turn-off process is reached; According to the voltage conversion rate, the current regulation circuit is controlled to output a sixth preset drive current until the voltage conversion ends during the power switch's turn-off process. The current regulation circuit is controlled to output a seventh preset drive current until the control electrode voltage of the power switch reaches the threshold voltage. The current regulation circuit is controlled to output an eighth preset drive current until the power switch tube is turned off.

7. The switch driving device according to any one of claims 1-6, characterized in that, The control circuit includes: a first comparator, a second comparator, and a controller; The first input terminal of the first comparator is connected to the first voltage detection circuit, the second input terminal of the first comparator is used to receive the first reference voltage value, and the output terminal of the first comparator is connected to the controller. The first input terminal of the second comparator is connected to the first voltage detection circuit, the second input terminal of the second comparator is used to receive the second reference voltage value, and the output terminal of the second comparator is connected to the controller. The controller is connected to the second voltage detection circuit, the voltage conversion rate detection circuit, and the current regulation circuit respectively. The controller is used to determine the start time and end time of voltage conversion during the conduction or cutoff process of the power switch tube according to the comparison results of the first comparator and the second comparator, and to adjust the drive current output by the current regulation circuit using the voltage conversion rate and the preset drive current value.

8. The switch driving device as described in claim 7, characterized in that, The switch driving device further includes a reference voltage generation circuit; The reference voltage generation circuit includes: a step-down unit, a first sampling unit, and a second sampling unit; The step-down unit is connected to the first voltage detection circuit, and the step-down unit is used to step down the voltage detected by the first voltage detection circuit to obtain the first reference voltage value and the second reference voltage value. The first sampling unit is connected to the buck unit and the first comparator. The first sampling unit is used to sample the first reference voltage value and output it to the second input terminal of the first comparator. The second sampling unit is connected to the buck unit and the second comparator. The second sampling unit is used to sample the second reference voltage value and output it to the second input terminal of the second comparator.

9. The switch driving device as described in claim 8, characterized in that, The step-down unit includes: a fourth capacitor, a fifth capacitor, and a sixth capacitor; The first terminal of the fourth capacitor is connected to the first voltage detection circuit, and the second terminal of the fourth capacitor is connected to the fifth capacitor and the first sampling unit. The second terminal of the fifth capacitor is connected to the second sampling unit and the first terminal of the sixth capacitor; The second terminal of the sixth capacitor is used for grounding.

10. The switch driving device as described in claim 8 or 9, characterized in that, The first sampling unit includes: a third switch, a seventh capacitor, and a first follower; The first electrode of the third switch is connected to the step-down unit, and the second electrode of the third switch is connected to the input terminal of the first follower and the first terminal of the seventh capacitor; The second terminal of the seventh capacitor is used for grounding; The output of the first follower is connected to the second input of the first comparator; The second sampling unit includes: a fourth switch, an eighth capacitor, and a second follower; The first electrode of the fourth switch is connected to the step-down unit, and the second electrode of the fourth switch is connected to the input terminal of the second follower and the first terminal of the eighth capacitor; The second terminal of the eighth capacitor is used for grounding; The output of the second follower is connected to the second input of the second comparator.

11. The switch drive device according to any one of claims 1-10, characterized in that, The power switching transistors include: metal oxide semiconductor field-effect transistors (MOS), insulated gate bipolar transistors (IGBTs), or silicon carbide (SiC).

12. A switch driver chip, characterized in that, The switch driver chip includes the switch driver device as described in any one of claims 1-11; The switch driver chip is used to connect to the power switch transistor and drive the power switch transistor to drive or cut off.

13. A switching device, characterized in that, Includes a switching circuit and a switching drive device as described in any one of claims 1-11; The switching circuit is used to connect to the power supply and the load, and to control the connection between the power supply and the load, or to convert the electrical energy output by the power supply into voltage and output the converted electrical energy to the load. The switch driving device is connected to the switch circuit and is used to provide a driving current to a power switch in the switch circuit and drive the power switch to turn on or off.

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