Adaptive driving circuit of power device and electronic equipment

Abstract

This invention discloses an adaptive drive circuit and electronic device for power devices. By setting up a first slope detection module and a second slope detection module, the drain-source voltage drop slope and rise slope during the power device's turn-on and turn-off processes are detected respectively. Based on different slope thresholds, corresponding detection signals are output. This dynamically generates different turn-on and turn-off level signals according to the actual switching state of the power device, controlling the drive circuit to output corresponding drive current levels. When the power device's switching speed is too fast, the corresponding drive current is reduced to decrease drain-source voltage overshoot, ringing, and electromagnetic interference; when the switching speed is slow, the corresponding drive current is increased to reduce switching losses and increase switching speed. This application solves the technical problem that fixed gate resistor drive methods struggle to balance switching speed, switching losses, and system reliability, achieving the technical effects of reducing overshoot and ringing, decreasing switching losses, and improving system stability.

Description

Technical Field

[0001] This invention relates to the field of circuit design, and in particular to an adaptive drive circuit and electronic device for power devices. Background Technology

[0002] With the widespread application of wide-bandgap power devices such as SiC MOSFETs, power conversion systems are gradually developing towards higher frequencies, higher efficiency, and higher power density. Because SiC power devices have high switching speeds, their drain-source voltage exhibits a large voltage change slope during switching, easily leading to significant voltage overshoot, ringing, and electromagnetic interference. Furthermore, excessively fast switching can cause the devices to experience large transient stresses, thus affecting system stability and device reliability. Therefore, how to suppress overshoot and ringing while ensuring switching speed and reducing switching losses has become a crucial issue in SiC drive technology.

[0003] In existing technologies, such as Figure 1 SW_ON is the signal that controls the turn-on of the SiC power device, and DRV is the corresponding drive voltage. A fixed gate resistor is typically used to adjust the drive speed of the SiC power device. While a smaller gate resistor can increase switching speed and reduce switching losses, it can easily lead to an excessively large drain-source voltage slope, resulting in significant overshoot and electromagnetic interference. Conversely, a larger gate resistor can suppress overshoot and ringing, but it will reduce switching speed and increase switching losses. Summary of the Invention

[0004] The purpose of this invention is to provide an adaptive drive circuit and electronic device for power devices, which solves the technical problem that fixed gate resistor drive methods are difficult to balance switching speed, switching loss and system reliability, and achieves the technical effects of reducing overshoot and ringing, reducing switching loss and improving system stability.

[0005] In a first aspect, the present invention provides an adaptive driving circuit for a power device, comprising: The first slope detection module includes at least two turn-on detection circuits, each of which is pre-configured with a corresponding falling slope threshold, and the falling slope thresholds are all different from each other; the first slope detection module is used to detect the falling slope of the drain-source voltage during the turn-on process of the power device; The second slope detection module includes at least two turn-off detection circuits, each of which is pre-configured with a corresponding rising slope threshold, and each rising slope threshold is different from the others; the second slope detection module is used to detect the rising slope of the drain-source voltage during the turn-off process of the power device; A control circuit, connected to the first slope detection module and the second slope detection module respectively, is used to receive the detection signals output by each detection circuit and generate an on-gear signal and an off-gear signal according to the detection signals; wherein, the on-gear signal has at least three different gears and the off-gear signal has at least three different gears. A driving circuit, connected to the gate of the power device, is used to output an on-drive current of the corresponding gear according to the on-gear signal, and to output an off-drive current of the corresponding gear according to the off-gear signal.

[0006] Optionally, each detection circuit includes: The sensing capacitor has one end connected to the drain of the power device; The comparison module includes a non-inverting input terminal, an inverting input terminal, and an output terminal. The non-inverting input terminal is connected to a reference node, the inverting input terminal is connected to the other end of the detection capacitor, and the output terminal is used to output the detection signal.

[0007] Optionally, the comparison module includes a transistor, a first resistor, a second resistor, a comparator, and an inverter; the comparator includes a first transistor and a second transistor. The first end of the second resistor is connected to the second end of the first resistor and the other end of the detection capacitor. The second end of the second resistor is grounded. The first end of the first resistor is connected to the emitter of the transistor. The collector of the transistor is connected to a preset power supply. The first ends of the first transistor and the first ends of the second transistor are both connected to a preset current source. The first end of the second transistor is also connected to the input of the inverter. The output of the inverter outputs the detection signal. The second end of the first transistor is grounded. The second end of the second transistor is connected to the other end of the detection capacitor. The base of the transistor is connected to the preset current source.

[0008] Optionally, when the detection circuit is a shutdown detection circuit, the comparison module further includes a third resistor; The first end of the third resistor is connected to the second end of the first transistor, and the second end of the third resistor is grounded.

[0009] Optionally, the comparison module further includes a Zener diode; The anode of the Zener diode is grounded, and the cathode of the Zener diode is connected to the control terminal of the transistor.

[0010] Optionally, the detection circuit further includes a reference circuit, which includes a preset current source, a first current mirror transistor, a second current mirror transistor, a third current mirror transistor, and a fourth current mirror transistor. The preset current source is connected to the second terminal and control terminal of the first current mirror transistor, the second terminal and control terminal of the second current mirror transistor, the second terminal and control terminal of the third current mirror transistor, and the second terminal and control terminal of the fourth current mirror transistor, respectively. The first terminal of the first current mirror transistor, the first terminal of the second current mirror transistor, the first terminal of the third current mirror transistor, and the first terminal of the fourth current mirror transistor are connected to and connected to the preset power supply.

[0011] Optionally, the driving circuit includes an on-drive circuit and an off-drive circuit; Each of the turn-on drive circuits and each of the turn-off drive circuits includes multiple drive current branches connected in parallel, and the control terminal of each drive current branch is connected to the control circuit. The turn-on drive circuit is used to control the conduction state of each drive current branch according to the turn-on gear signal, so as to form a turn-on drive current of a magnitude corresponding to the turn-on gear signal. The shutdown drive circuit is used to control the conduction state of each drive current branch according to the shutdown position signal, so as to form a shutdown drive current of the same magnitude as the shutdown position signal.

[0012] Optionally, each of the driving current branches includes a current mirror branch and a switching control transistor; The output terminal of the current mirror branch is connected to one end of the switch control transistor, the other end of the switch control transistor is connected to the gate of the power device, and the control terminal of the switch control transistor is connected to the control circuit. The current mirror branch is used to provide a constant drive current; The switch control transistor is used to turn on or off according to the on or off gear signal received by its own control terminal.

[0013] Optionally, both the turn-on drive circuit and the turn-off drive circuit have at least one drive current branch as a basic drive branch. The basic drive branch is in a continuously conducting state during the power device's turn-on or turn-off process. The other drive current branches, excluding the basic drive branch, switch their own conduction or turn-off states according to the turn-on or turn-off signal.

[0014] Secondly, the present invention provides an electronic device including an adaptive drive circuit for the power device described above.

[0015] This invention provides an adaptive drive circuit and electronic device for power devices. By setting up a first slope detection module and a second slope detection module, the drain-source voltage drop slope during the power device's turn-on process and the drain-source voltage rise slope during the turn-off process are detected respectively. Based on different slope thresholds, different detection signals are output. This dynamically generates different turn-on and turn-off level signals according to the actual switching state of the power device, thereby controlling the drive circuit to output the corresponding level of drive current. When the power device's switching speed is too fast, the corresponding drive current is reduced to decrease drain-source voltage overshoot, ringing, and electromagnetic interference; when the switching speed is slow, the corresponding drive current is increased to reduce switching losses and increase switching speed. This application solves the technical problem that fixed gate resistor drive methods struggle to balance switching speed, switching losses, and system reliability, achieving the technical effects of reducing overshoot and ringing, decreasing switching losses, and improving system stability. Attached Figure Description

[0016] To more clearly illustrate the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of a driving circuit in the prior art; Figure 2 A schematic diagram of an adaptive drive circuit for a power device provided by the present invention; Figure 3 A schematic diagram of a shutdown detection circuit provided by the present invention; Figure 4 This is a schematic diagram of an activation detection circuit provided by the present invention; Figure 5 A schematic diagram of a driving circuit provided by the present invention; Figure 6 This is a schematic diagram of the driving waveforms of each switch in a driving circuit provided by the present invention. Detailed Implementation

[0018] The core of this invention is to provide an adaptive drive circuit and electronic device for power devices, which solves the technical problem that fixed gate resistor drive methods are difficult to balance switching speed, switching loss and system reliability, and achieves the technical effects of reducing overshoot and ringing, reducing switching loss and improving system stability.

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] like Figure 2 In a first aspect, the present invention provides an adaptive drive circuit 14 for a power device, comprising: The first slope detection module 11 includes at least two turn-on detection circuits. Each turn-on detection circuit is pre-configured with a corresponding falling slope threshold, and each falling slope threshold is different from the others. The first slope detection module 11 is used to detect the falling slope of the drain-source voltage during the turn-on process of the power device. The second slope detection module 12 includes at least two turn-off detection circuits. Each turn-off detection circuit is pre-configured with a corresponding rising slope threshold, and each rising slope threshold is different from the others. The second slope detection module 12 is used to detect the rising slope of the drain-source voltage during the turn-off process of the power device. The control circuit 13 is connected to the first slope detection module 11 and the second slope detection module 12 respectively, and is used to receive the detection signals output by each detection circuit, and generate an on gear signal and an off gear signal according to the detection signals; wherein, the on gear signal has at least three different gears, and the off gear signal has at least three different gears. The drive circuit 14 is connected to the gate of the power device and is used to output the turn-on drive current of the corresponding gear according to the turn-on gear signal and the turn-off drive current of the corresponding gear according to the turn-off gear signal.

[0021] This embodiment provides an adaptive drive circuit 14 for a power device. During the turn-on and turn-off processes of the power device, the drain-source voltage changes rapidly, and different rates of change typically correspond to different switching states. When the drain-source voltage changes too quickly, significant voltage overshoot, ringing, and electromagnetic interference are likely to occur. When the drain-source voltage changes too slowly, it may lead to increased switching losses. Therefore, this embodiment does not employ a fixed drive method. Instead, it uses a first slope detection module 11 and a second slope detection module 12 to detect the drain-source voltage changes during the turn-on and turn-off phases of the power device, respectively, and uses the detection results as the basis for adjusting the drive current.

[0022] In this embodiment, the first slope detection module 11 includes at least two turn-on detection circuits, each corresponding to a different falling slope threshold. When the power device enters the turn-on process, the first slope detection module 11 can, but is not limited to, classify the drain-source voltage falling slope according to multiple falling slope thresholds. For example, when the falling slope is in a lower range, it can correspond to a single detection result (e.g., ...). Figure 2 (ON1 and ON2 output from the circuit). When the drop slope exceeds a higher threshold, it corresponds to another detection result. Since the drop slope thresholds corresponding to each turn-on detection circuit are different, the drain-source voltage drop rate during the turn-on process can be divided into multiple intervals, rather than simply judging whether a single threshold is exceeded.

[0023] Similar to the turn-on process, the second slope detection module 12 is used to detect the rise slope of the drain-source voltage during the turn-off process of the power device. Each turn-off detection circuit corresponds to a different rise slope threshold, so the rise rate of the drain-source voltage during the turn-off process can also be divided into multiple intervals. When the rise slope of the drain-source voltage is in different intervals, the combination relationship of the detection signals output by each turn-off detection circuit will also change (e.g., Figure 2 (OFF1 and OFF2 in the diagram). In this way, the control circuit 13 can not only know that the power device is currently in the off-state process, but also further know the slope range corresponding to the current off-state speed. For example, if the actual decreasing slope is detected to be higher than the preset maximum threshold during the turn-on process, it indicates that the switching is too fast and prone to overshoot. The control circuit 13 then sets the turn-on position signal to a certain level; if the slope is moderate, it sets it to another level; if the slope is too slow, it sets it to a third level. The turn-off position signal is generated in the same way. Thus, the turn-on position signal contains at least three different levels, and the turn-off position signal is the same. The essence of the position signal is to tell the drive circuit 14 how much drive current is currently required.

[0024] After receiving the detection signals output by each detection circuit, the control circuit 13 can generate corresponding on / off position signals based on different combinations of detection signals. In this embodiment, both the on / off position signal and the off position signal have at least three different positions (e.g., Figure 2 The control circuit 13, with its parameters SW_ON1, SW_ON2, SW_ON3, SW_OFF1, SW_OFF2, and SW_OFF3, can represent multiple drive levels, not just on and off states. For example, it can output a lower drive level signal when a rapid change in drain-source voltage is detected, and a higher drive level signal when a slow change in drain-source voltage is detected. The number of drive levels can be, but is not limited to, three, four, or more.

[0025] The drive circuit 14 outputs a corresponding drive current based on the received on or off position signal. In other words, the drive current is no longer fixed but dynamically adjusted according to the change in the drain-source voltage slope. When the drain-source voltage changes rapidly, the drive current for the corresponding position decreases; when the drain-source voltage changes slowly, the drive current for the corresponding position increases. In this way, throughout the entire switching process of the power device, the drive capability can be adjusted according to the actual switching state, ensuring that the power device receives a matching drive current under different operating conditions, achieving a balance between switching speed and overshoot / ringing.

[0026] As an optional embodiment, the first slope detection module 11, the second slope detection module 12, the control circuit 13, and the drive circuit 14 are integrated into the same chip. Compared with using multiple independent devices to implement detection, control, and drive functions, this embodiment integrates drain-source voltage slope detection, range control, and drive current output into a single chip, allowing the detection signal to directly participate in drive regulation without needing a long external transmission path. Therefore, the influence of parasitic parameters introduced by external connections on the detection results and control signals can be reduced, while also reducing the number of peripheral devices. In a specific embodiment, the first slope detection module 11, the second slope detection module 12, the control circuit 13, and the drive circuit 14 can be integrated into a single drive chip, requiring only connection to power devices and a small number of external components to complete drive control.

[0027] like Figure 3 and Figure 4 As an optional embodiment, each detection circuit includes: The sensing capacitor Cs has one end connected to the drain of the power device; The comparison module includes a non-inverting input, an inverting input, and an output. The non-inverting input is connected to the reference node, the inverting input is connected to the other end of the detection capacitor Cs, and the output is used to output the detection signal.

[0028] This embodiment provides a specific implementation of the detection circuit. Each detection circuit includes a detection capacitor Cs. When the drain-source voltage changes rapidly, the detection capacitor Cs generates a displacement current due to the voltage change across its terminals. This current flows through the impedance of the inverting input, forming a voltage. The non-inverting input of the comparator module is connected to a fixed reference node, i.e., a reference voltage. The comparator module compares the voltage at the inverting input with the reference voltage in real time. If the voltage at the inverting input is higher than the reference, the output goes low; otherwise, the output goes high. Thus, the output signal of the comparator module directly reflects whether the drain-source voltage slope exceeds a preset threshold for the detection circuit. Because the threshold value is determined by the capacitance of the detection capacitor Cs, the voltage of the reference node, and the load impedance of the inverting input, different slope thresholds can be set for different detection circuits by adjusting these parameters.

[0029] It is easy to understand that this structure in this embodiment can be used simultaneously for both turn-on and turn-off detection. Taking turn-off detection as an example, when the power device turns off, the drain-source voltage rises rapidly, the displacement current generated by the detection capacitor Cs has a fixed direction, and the voltage at the inverting terminal changes accordingly. The comparison module compares this change with a fixed reference voltage. Once the slope exceeds a preset value, the output signal will flip. The control circuit 13 receives this flip signal and knows that the current turn-off speed is too fast, and it needs to reduce the turn-off drive current. The turn-on process is the same, except that the drain-source voltage decreases and the displacement current is in the opposite direction, but the comparison principle is exactly the same.

[0030] As an optional embodiment, the detection circuit also includes a voltage divider circuit, comprising resistors R4 and R5. The detection capacitor Cs is not directly connected to the drain of the power device, but rather connected through the voltage divider circuit. Since the drain of the power device may experience a large voltage change range during switching, directly connecting it to the detection circuit could easily subject the detection node to a high voltage. Therefore, this embodiment uses R4 and R5 to divide the drain voltage, keeping the voltage change signal received by the detection capacitor Cs within a preset range. Simultaneously, since the detection capacitor Cs responds to the rate of change of the voltage across its terminals, the drain voltage change after voltage division still reflects the slope information of the drain-source voltage of the power device. The detection sensitivity and the corresponding slope detection range can be set by adjusting, but not limited to, the resistance ratio of R4 and R5, to adapt to power devices with different withstand voltage ratings and switching speeds.

[0031] As an optional embodiment, the detection circuit also includes a small-capacity capacitor Cf connected between the other end of the detection capacitor Cs and ground. The relatively small capacitance of Cf is used to filter out high-frequency noise generated by the drain of the power device during switching, which may originate from switching spikes or parasitic ringing. Without Cf, high-frequency interference may cause false triggering of the detection circuit, resulting in abnormal fluctuations or incorrect ranges in the slope signal. By setting Cf, the detection signal can be made smoother and more reliable without significantly affecting the drain-source voltage slope response, thereby ensuring accurate output of the turn-on and turn-off range signals. The value of Cf can be selected, but is not limited to, based on the switching speed of the power device and the noise amplitude, to balance response speed and anti-interference capability.

[0032] As an optional embodiment, the comparator module includes a transistor Q1, a first resistor R1, a second resistor R2, a comparator, and an inverter Inv; the comparator includes a first transistor NM1 and a second transistor NM2; The first end of the second resistor R2 is connected to the second end of the first resistor R1 and the other end of the detection capacitor Cs. The second end of the second resistor R2 is grounded. The first end of the first resistor R1 is connected to the emitter of the transistor Q1. The collector of the transistor Q1 is connected to a preset power supply. The first ends of the first transistor NM1 and the second transistor NM2 are both connected to a preset current source. The first end of the second transistor NM2 is also connected to the input of the inverter Inv. The output of the inverter Inv outputs the detection signal Vout. The second end of the first transistor NM1 is grounded. The second end of the second transistor NM2 is connected to the other end of the detection capacitor Cs. The base of the transistor Q1 is connected to a preset current source.

[0033] In this embodiment, the specific circuit operation of the comparison module is as follows: the voltage signal from the other end of the detection capacitor Cs first passes through a voltage divider network consisting of the first resistor R1 and the second resistor R2. One end of the second resistor R2 is grounded, and the other end is connected to both the first resistor R1 and the detection capacitor Cs. Therefore, the voltage change across the detection capacitor Cs will be reflected across the second resistor R2. This voltage change is related to the rate of change of the drain voltage of the power device. This voltage is applied to the emitter of the transistor Q1. The collector of the transistor Q1 is connected to a preset power supply (VCC), and the base is connected to a preset current source (i.e.,...). Figure 3 or Figure 4The first reference source in the circuit indicates that transistor Q1 is in the on state, and its base voltage is approximately fixed. When the emitter voltage changes, the current flowing through transistor Q1 changes accordingly. This current then flows back to the sensing capacitor Cs node through the first resistor R1. Finally, a voltage related to the displacement current is formed across the second resistor R2. This voltage, together with the fixed potential of the base of transistor Q1, determines the potential of the inverting input terminal of the comparator. In other words, the faster the drain voltage of the power device changes, the larger the current generated by the sensing capacitor Cs, and the more obvious the voltage change at the corresponding node.

[0034] In this embodiment, transistor Q1 works in conjunction with a preset current source to provide a relatively stable reference condition. Since the detection capacitor Cs outputs a dynamic current signal related to the voltage slope, the comparator module needs to judge this dynamic signal under a fixed reference condition. Transistor Q1 can, but is not limited to, operate in the linear region, forming a reference voltage through its own conduction state in conjunction with the first resistor R1 and the second resistor R2, enabling the comparator to distinguish detected signal changes. In this way, the detection current corresponding to different drain-source voltage slopes can be converted into comparison signals of different amplitudes.

[0035] The comparator consists of a first transistor NM1 and a second transistor NM2. The first terminals of both transistors are connected to the same preset current source, and their second terminals are grounded and connected to the other end of the detection capacitor Cs, respectively. This forms a differential pair, where the gate (or base) of the first transistor NM1 is connected to a fixed bias, and the gate of the second transistor NM2 is connected to the voltage across the detection capacitor Cs. The comparison result is output from the first terminal of the second transistor NM2, and then shaped by the inverter Inv to obtain the final detection signal. It is easy to understand that the flip-flop threshold of this comparator depends on the size of the preset current source and the size ratio of the first transistor NM1 and the second transistor NM2. When the voltage across the detection capacitor Cs causes the current flowing through the second transistor NM2 to be greater than that through the first transistor NM1, the output flips. The inverter Inv increases the comparator gain and provides greater drive capability.

[0036] The entire comparison module implements the slope detection function. The preset current source in this embodiment can be copied from an external reference using a current mirror, but is not limited to this. The comparator can also be replaced with other differential structures, such as using PMOS transistors as input pairs.

[0037] like Figure 3 As an optional embodiment, when the detection circuit is a turn-off detection circuit, the comparison module further includes a third resistor R3; The first terminal of the third resistor R3 is connected to the second terminal of the first transistor NM1, and the second terminal of the third resistor R3 is grounded.

[0038] In this embodiment, the turn-off detection circuit has an additional third resistor R3 compared to the turn-on detection circuit. This resistor is connected between the second terminal of the first transistor NM1 and ground. This resistor is added because the drain-source voltage rises rapidly during turn-off, and the displacement current generated by the detection capacitor Cs flows in the opposite direction to that during turn-on. During turn-on, the displacement current flows to the other end of the detection capacitor Cs, while during turn-off, the displacement current flows out from the other end of the detection capacitor Cs, which causes a change in the internal current relationship of the comparator. Without the third resistor R3, the differential pair formed by the first transistor NM1 and the second transistor NM2 may not flip properly during turn-off, or the flipping threshold may deviate too much from the design value. With the third resistor R3, a portion of the current flowing through the first transistor NM1 will pass through this resistor to ground, thereby changing the operating point of the differential pair. This allows the turn-off detection circuit to achieve detection accuracy and threshold stability similar to the turn-on detection circuit even under reverse current. It is understood that the value of this resistor needs to be selected based on the magnitude of the preset current source and the expected slope range on the turn-off side; different power devices may have different resistor values.

[0039] The turn-off slope detection algorithm is as follows: Capacitor charging and discharging formula: .

[0040] According to Kirchhoff's current law: , .

[0041] When VN > VP, Vout outputs low.

[0042] From the above formula, we can obtain that when

[0043] dV DS / dt >(( R4+R5 )[ Ib1 ×( R3-R2 ()( R1+R2 )-( Vz - ΔVbe )× R2 ]) / ( Cs × R5 ×( R1+ R2 When )), the output Vout is low.

[0044] This invention employs two parallel turn-off slope detection circuits, and then achieves a three-level threshold V by adjusting the resistance values ​​of R1, R2, R3, R4, and R5, the capacitance value of Cs, or the reference current Ib1. DS Ascent slope detection, when the slope exceeds dV DSOFF2 Pulling down SW_OFF2 at / dt reduces the drive capability of SiC when it is turned off, when the slope exceeds dV. DSOFF1Pulling down SW_OFF1 during / dt further reduces the drive capability when SiC is turned off.

[0045] The slope detection algorithm is as follows: The known formula for charging and discharging a capacitor is: ； At this time dV DS Since / dt is negative, Is is also negative. According to Kirchhoff's current law: ; VP=0 ; When VN > VP, Vout outputs low.

[0046] From the above formula, we can obtain that when dV DS / dt >(-( R4+R5 )[ Vz-Vbe+Ib1 ( R1+R2 )]) / (( R1+R2 ) Cs × R5 When Vout is low, the output Vout is low.

[0047] This invention employs two parallel turn-on slope detection circuits, and then achieves a three-level threshold V by adjusting the resistance values ​​of R1, R2, R4, and R5, the capacitance value of Cs, or the reference current Ib1. DS Falling slope detection, when the slope exceeds dV DSON2 When / dt is applied, pull up SW_ON2 to reduce the drive capability when SiC is turned off. When the slope exceeds dV DSON1 Pulling up SW_ON1 during / dt further reduces the driving capability when SiC is turned on.

[0048] Among them, V DS The drain-source voltage of SiC is dV. DS / dt represents the change in drain-source voltage of SiC over time, i.e., the slope of the drain-source voltage change. Cs is the internally integrated sensing capacitor, which will convert dV... DS / dt is converted to a current signal. Cf is a filter capacitor that filters out high-frequency noise. Is is the current flowing through capacitor Cs, which can be understood as the real-time current flowing through capacitor Cs. Ib1 is the first reference current provided by the reference source. VN and VP are the node voltages of this circuit. Vz is the fixed voltage generated by the ZENER transistor, and ΔVbe is the voltage drop across the junction of transistor Q1be.

[0049] As an optional embodiment, the comparison module also includes a Zener diode Z1; The anode of Zener diode Z1 is grounded, and the cathode of Zener diode Z1 is connected to the control terminal of transistor Q1.

[0050] In this embodiment, a Zener diode Z1 is added to the comparison module. The anode of Zener diode Z1 is grounded, and the cathode is directly connected to the base of transistor Q1. This is done to clamp the base voltage of transistor Q1 to a fixed value by Zener diode Z1. When the current from the collector to the emitter of transistor Q1 changes, the base current also changes accordingly. Without Zener diode Z1, the base voltage would fluctuate with the base current, thus affecting the voltage detection accuracy at the other end of the sensing capacitor Cs. With Zener diode Z1, by providing a relatively stable reference voltage, the change in base current has a smaller impact on the Zener voltage Vz when different currents flow between the collector and emitter of transistor Q1. Vz can remain basically stable. It is easy to understand that the more stable the reference voltage, the more stable the judgment result of the comparison module on the detected current, thus ensuring the accuracy of current detection. It is evident that the Zener diode Z1 ensures that the displacement current generated by the sensing capacitor Cs is accurately converted into a voltage signal, and the slope threshold setting will not drift due to changes in the operating current of the transistor Q1.

[0051] As an optional embodiment, the detection circuit further includes a reference circuit, which includes a preset current source, a first current mirror transistor, a second current mirror transistor, a third current mirror transistor, and a fourth current mirror transistor. The preset current source is connected to the second terminal and control terminal of the first current mirror transistor, the second terminal and control terminal of the second current mirror transistor, the second terminal and control terminal of the third current mirror transistor, and the second terminal and control terminal of the fourth current mirror transistor, respectively. The first terminal of the first current mirror transistor, the first terminal of the second current mirror transistor, the first terminal of the third current mirror transistor, and the first terminal of the fourth current mirror transistor are connected to and connected to the preset power supply.

[0052] In this embodiment, the detection circuit also includes a reference circuit, which provides a stable reference current to ensure the consistency and reliability of the outputs of each detection circuit. This embodiment uses a preset current source (i.e., Figure 3 or Figure 4 The first reference source in the circuit generates a fixed current, which is then shunted and replicated through four current mirror transistors (PM1-PM4). The preset current is precisely replicated to each detection branch according to a certain ratio. In this way, each turn-on or turn-off detection circuit can obtain a consistent reference current to drive the comparison module, thereby enabling different detection units to generate comparable detection signals when faced with changes in the slope of the drain-source voltage of the power device.

[0053] It's easy to understand that these four current mirror outputs can be flexibly distributed to various biasing points within the comparator module. For example, one output can provide a preset current Ib1 to the base of transistor Q1, while another can provide a preset current source to the first terminals of the first transistor NM1 and the second transistor NM2 in the comparator. Since the four transistors can be designed with different size ratios, the output currents can be equal, amplified, or reduced by a certain factor. This eliminates the need for a separate reference source for each current-required point in the detection circuit; the entire bias network is derived from the same preset current source through the current mirrors, resulting in a simpler circuit structure and a more stable proportional relationship between the currents in each branch.

[0054] Overall, this reference circuit does not participate in direct signal comparison, but it determines the operating point and topping threshold of the comparison module. For example, adjusting the size of the preset current source or changing the size ratio of the four current mirror transistors can alter the comparator's comparison accuracy and response speed. In this embodiment, the current mirror transistors can be, but are not limited to, PMOS transistors, and the preset power supply can be a low-voltage power supply regulated internally by the chip. It is also important to understand that... Figure 2 The document provides a first reference source, a second reference source, a third reference source, and a fourth reference source. The currents of each reference source can be the same or different, and each reference source can act on at least one detection circuit.

[0055] As an optional embodiment, the drive circuit 14 includes an on drive circuit and an off drive circuit; Each turn-on drive circuit and each turn-off drive circuit includes multiple drive current branches connected in parallel, and the control terminal of each drive current branch is connected to the control circuit 13. The turn-on drive circuit is used to control the conduction state of each drive current branch according to the turn-on position signal, so as to form a turn-on drive current of the same magnitude as the turn-on position signal. The shutdown drive circuit is used to control the conduction state of each drive current branch according to the shutdown position signal, so as to form a shutdown drive current of the same magnitude as the shutdown position signal.

[0056] In this embodiment, the driving circuit 14 includes an on-drive circuit and an off-drive circuit, which correspond to the on-process and off-process of the power device, respectively. Unlike the traditional method of using a single path to output a fixed drive current, this embodiment divides the driving circuit 14 into multiple parallel drive current branches. Each drive current branch can be independently turned on or off under the control of the control circuit 13, meaning each branch can independently inject or extract current into or from the gate of the power device. Thus, different combinations of drive current branches correspond to different levels of drive capability. When the power device is in the on-state, the on-drive circuit selects the appropriate number of drive current branches to participate in the operation according to the on-gear signal. When the power device is in the off-state, the off-drive circuit selects the corresponding drive current branch to participate in the operation according to the off-gear signal.

[0057] In this embodiment, each drive current branch is equivalent to multiple independently controllable drive units. After receiving the detection signal output by the detection circuit, the control circuit 13 can determine the current drain-source voltage slope range and further determine the corresponding on-state or off-state signal. When the position changes, the number of drive current branches involved in the operation also changes accordingly. From a control perspective, the number of on-state signals corresponds to the number of conduction combinations configured by the drive circuit 14. For example, in one specific embodiment, there are three on-state signals, which can be, but are not limited to, using three drive current branches connected in parallel. When only one branch is on, a small drive current is formed; when two branches are on simultaneously, a medium-sized drive current is formed; and when all three branches are on simultaneously, a large drive current is formed. By using different branch combinations, multiple drive states can be switched. The off-state drive circuit is completely similar, except that the current direction is reversed, used to pull down the gate voltage. The position signals output by the control circuit 13 are actually a set of parallel control levels, each control level corresponding to the switching of a drive current branch.

[0058] Since the drive current is formed by multiple drive current branches, the drive capability is no longer a fixed value but can dynamically change with the on or off signal. When a rapid change in drain-source voltage is detected, the number of drive current branches participating in the operation can be reduced to lower the drive current; when a slow change in drain-source voltage is detected, the number of drive current branches participating in the operation can be increased to increase the drive current. Furthermore, this parallel branch structure is very flexible to implement; the current magnitude of each branch can be designed independently, for example, by changing the size ratio of the current mirrors in the branches. The resulting total drive current can cover a wide adjustment range. It is easy to understand that, in this way, the drive circuit 14 can adjust the drive capability in stages according to the actual switching state of the power device, ensuring that both the on and off processes obtain a drive current that matches the current operating state.

[0059] As an optional embodiment, each drive current branch includes a current mirror branch and a switching control transistor; The output terminal of the current mirror branch is connected to one end of the switching control transistor, the other end of the switching control transistor is connected to the gate of the power device, and the control terminal of the switching control transistor is connected to the control circuit 13. The current mirror branch is used to provide a constant drive current; The switching control transistor is used to turn on or off according to the on or off gear signal received by its own control terminal.

[0060] In this embodiment, each drive current branch includes a current mirror branch and a switching control transistor. The current mirror branch generates a constant-magnitude drive current. The drive currents for different drive current branches can be the same or set to different values ​​according to actual needs. By providing drive current through the current mirror branch, the output current of each drive current branch can remain relatively stable, thus making the drive capability corresponding to different branch combinations clearer and facilitating the division of drive levels.

[0061] In this embodiment, the switch control transistor is used to control whether the corresponding drive current branch participates in the current driving process. When the control circuit 13 outputs different on-state signals or off-state signals, the on-state of the corresponding switch control transistor changes, thereby determining whether the drive current output by the corresponding current mirror branch is transmitted to the gate of the power device. For example, in one specific embodiment, it is possible, but not limited to, to make some drive current branches in the on state while the remaining drive current branches are in the off state, so as to form different total drive currents.

[0062] It is easy to understand that, since each drive current branch can be controlled independently, the drive current ultimately output to the gate of the power device by the drive circuit 14 is actually formed by the superposition of multiple constant drive currents. When the number of drive current branches involved in operation increases, the total drive current increases; when the number of drive current branches involved in operation decreases, the total drive current decreases. In this way, different combinations of multiple fixed current branches can be used to achieve multi-level drive current output, so that the drive capability can be switched according to the on-gear signal or the off-gear signal.

[0063] Separating the current mirror and the switching control transistor simplifies the circuit design and makes it easier to ensure current matching between branches. The current mirror branch can be configured as a standard cascode structure to improve output impedance and ensure that the current remains constant under different gate voltages. In this embodiment, the switching control transistor can be, but is not limited to, a PMOS transistor in the turn-on drive circuit because a positive current needs to be injected into the gate; while an NMOS transistor is typically used in the turn-off drive circuit because current needs to be drawn from the gate. The specific type of transistor used can be selected according to the actual needs of the drive circuit 14.

[0064] like Figure 5 The switching control transistors corresponding to the turn-on drive circuit are 406, 407, and 408, and their corresponding turn-on position signals are SW_ON1, SW_ON2, and SW_ON3, respectively. The switching control transistors corresponding to the turn-off drive circuit are 410, 411, and 412, and their corresponding turn-off position signals are SW_OFF1, SW_OFF2, and SW_OFF3, respectively. Figure 5 In the circuit diagram, transistors 401 and 416 generate a reference current, Ib, with the value Ib = (VCC - Vth) / R6. This reference current is then used to provide a fixed current to the corresponding branch via current mirrors 403, 404, and 405. Transistors 406, 407, and 408 are three branch switches that turn on the corresponding branch when the voltage is low. Transistors 402 and 409 copy the reference current to the pull-down branch drive current. Transistors 413, 414, and 415 are current mirrors providing a fixed current to the corresponding branch. Transistors 410, 411, and 412 are the corresponding branch switches. Transistor 417 limits the voltage at the gate of the SiC circuit, and transistor 418 is the corresponding power device.

[0065] As an optional embodiment, both the turn-on drive circuit and the turn-off drive circuit have at least one drive current branch as the basic drive branch. Among them, the basic drive branch is in a continuous conducting state during the power device's turn-on or turn-off process, and the other drive current branches, except for the basic drive branch, switch their own conduction or turn-off states according to the turn-on or turn-off signal.

[0066] In this embodiment, both the turn-on and turn-off drive circuits include a basic drive branch. This basic drive branch remains continuously conducting during the turn-on or turn-off process of the power device, providing the basic drive current. This ensures that the power device gate always receives a certain level of drive capability, regardless of the current drive level, preventing drive interruption caused by the simultaneous turn-off of all drive current branches.

[0067] In one specific implementation, three drive current branches can be provided, but are not limited to: one drive current branch serving as the basic drive branch, and the other two drive current branches serving as switchable drive branches. When the power device enters the turn-on or turn-off process, the basic drive branch remains on, while the other two drive current branches selectively conduct according to the turn-on or turn-off signal. For example, the first drive current is formed when only the basic drive branch is on; the second drive current is formed when the basic drive branch and one of the switchable drive branches are on simultaneously; and the third drive current is formed when all three drive current branches are on simultaneously. Of course, the number of drive current branches is not limited to three and can be set to more according to actual needs.

[0068] Because the basic drive branch is always involved in the driving process, the power device always possesses basic driving capability throughout the switching process, while the adjustment of the driving capability is accomplished by the other drive current branches. When a change in the drain-source voltage slope is detected, only the conduction state of the switchable drive branch needs to be adjusted to change the magnitude of the drive current, without frequently changing the operating state of all drive branches. This enables multi-level drive current switching while ensuring that the power device remains under control during turn-on and turn-off.

[0069] like Figure 5 In the diagram, 408 is the basic drive branch in the turn-on drive circuit, and 412 is the basic drive branch in the turn-off drive circuit. Figure 5 The waveforms of each switching transistor are as follows: Figure 6 As shown, during the SiC power device turn-on process, SW_ON3 is normally low to ensure basic driving capability. During SiC turn-on, if the VDS falling slope is higher than the first threshold, then SW_ON1 and SW_ON2 are both high, correspondingly reducing the driving current. When the VDS falling slope is lower than the first threshold but higher than the second threshold, SW_ON1 is high and SW_ON2 is low, correspondingly increasing the driving current. When the VDS falling slope is lower than the second threshold, SW_ON1 and SW_ON2 are both low, correspondingly increasing the driving current. Correspondingly, during SiC turn-off, SW_OFF3 is always high to ensure basic driving capability; during SiC turn-off, when the VDS rising slope is higher than the first rising slope threshold, SW_OFF1 and SW_OFF2 are simultaneously set low, reducing the driving current accordingly; when the VDS rising slope is lower than the first rising slope threshold but higher than the second rising slope threshold, SW_OFF1 is set low and SW_OFF2 is set high, increasing the driving current accordingly; when the VDS rising slope is lower than the second rising slope threshold, SW_OFF1 and SW_OFF2 are simultaneously set high, increasing the driving current accordingly.

[0070] In a second aspect, the present invention provides an electronic device including an adaptive drive circuit for the power device described above.

[0071] Because the adaptive drive circuit of this power device can dynamically adjust the drive current according to the slope of the drain-source voltage drop during the power device's turn-on process and the slope of the drain-source voltage rise during the turn-off process, the power device in the electronic device can obtain the drive capability corresponding to the current switching state under different operating conditions, ensuring switching speed while taking into account overshoot, ringing, and switching losses. It can be applied, but is not limited to, to switching power supplies, inverters, frequency converters, vehicle power supplies, motor drives, and other electronic devices that use power devices for energy conversion.

[0072] For further details on the electronic device, please refer to the embodiments of the adaptive drive circuit of the power device described above; these will not be repeated here.

[0073] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0074] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An adaptive drive circuit for a power device, characterized in that, include: The first slope detection module includes at least two turn-on detection circuits, each of which is pre-configured with a corresponding falling slope threshold, and the falling slope thresholds are all different from each other; the first slope detection module is used to detect the falling slope of the drain-source voltage during the turn-on process of the power device; The second slope detection module includes at least two turn-off detection circuits, each of which is pre-configured with a corresponding rising slope threshold, and each rising slope threshold is different from the others; the second slope detection module is used to detect the rising slope of the drain-source voltage during the turn-off process of the power device; A control circuit, connected to the first slope detection module and the second slope detection module respectively, is used to receive the detection signals output by each detection circuit and generate an on-gear signal and an off-gear signal according to the detection signals; wherein, the detection circuit includes an on-gear detection circuit and an off-gear detection circuit, the on-gear signal has at least three different gears, and the off-gear signal has at least three different gears; A driving circuit, connected to the gate of the power device, is used to output an on-drive current of the corresponding gear according to the on-gear signal, and to output an off-drive current of the corresponding gear according to the off-gear signal. Each of the aforementioned turn-on detection circuits and turn-off detection circuits includes a detection capacitor, one end of which is connected to the drain of the power device; each detection circuit also includes a comparison module, which is used to compare the voltage of the node corresponding to the detection capacitor with the voltage of the reference node and output a detection signal. The driving circuit includes an on-drive circuit and an off-drive circuit; the on-drive circuit is used to control the conduction state of each driving current branch according to the on-gear signal to form an on-drive current of the same magnitude as the on-gear signal; the off-drive circuit is used to control the conduction state of each driving current branch according to the off-gear signal to form an off-drive current of the same magnitude as the off-gear signal. In both the turn-on drive circuit and the turn-off drive circuit, at least one drive current branch is set as a basic drive branch. The basic drive branch is in a continuously conducting state during the turn-on or turn-off process of the power device. The other drive current branches, except for the basic drive branch, switch their own conduction or turn-off states according to the turn-on gear signal or the turn-off gear signal.

2. The adaptive drive circuit for the power device as described in claim 1, characterized in that, The comparison module includes a non-inverting input terminal, an inverting input terminal, and an output terminal. The non-inverting input terminal is connected to a reference node, the inverting input terminal is connected to the other end of the detection capacitor, and the output terminal is used to output the detection signal.

3. The adaptive drive circuit for the power device as described in claim 2, characterized in that, The comparison module includes a transistor, a first resistor, a second resistor, a comparator, and an inverter; the comparator includes a first transistor and a second transistor. The first end of the second resistor is connected to the second end of the first resistor and the other end of the detection capacitor. The second end of the second resistor is grounded. The first end of the first resistor is connected to the emitter of the transistor. The collector of the transistor is connected to a preset power supply. The first ends of the first transistor and the first ends of the second transistor are both connected to a preset current source. The first end of the second transistor is also connected to the input of the inverter. The output of the inverter outputs the detection signal. The second end of the first transistor is grounded. The second end of the second transistor is connected to the other end of the detection capacitor. The base of the transistor is connected to the preset current source.

4. The adaptive drive circuit for the power device as described in claim 3, characterized in that, When the detection circuit is a turn-off detection circuit, the comparison module further includes a third resistor; The first end of the third resistor is connected to the second end of the first transistor, and the second end of the third resistor is grounded.

5. The adaptive drive circuit for the power device as described in claim 3, characterized in that, The comparison module also includes a Zener diode; The anode of the Zener diode is grounded, and the cathode of the Zener diode is connected to the control terminal of the transistor.

6. The adaptive drive circuit for the power device as described in claim 3, characterized in that, The detection circuit further includes a reference circuit, which includes a preset current source, a first current mirror transistor, a second current mirror transistor, a third current mirror transistor, and a fourth current mirror transistor. The preset current source is connected to the second terminal and control terminal of the first current mirror transistor, the second terminal and control terminal of the second current mirror transistor, the second terminal and control terminal of the third current mirror transistor, and the second terminal and control terminal of the fourth current mirror transistor, respectively. The first terminal of the first current mirror transistor, the first terminal of the second current mirror transistor, the first terminal of the third current mirror transistor, and the first terminal of the fourth current mirror transistor are connected to and connected to the preset power supply.

7. The adaptive drive circuit for the power device as described in any one of claims 1-6, characterized in that, Each of the aforementioned drive current branches includes a current mirror branch and a switch control transistor; The output terminal of the current mirror branch is connected to one end of the switch control transistor, the other end of the switch control transistor is connected to the gate of the power device, and the control terminal of the switch control transistor is connected to the control circuit. The current mirror branch is used to provide a constant drive current; The switch control transistor is used to turn on or off according to the on or off gear signal received by its own control terminal.

8. The adaptive drive circuit for the power device as described in claim 1, characterized in that, The first slope detection module, the second slope detection module, the control circuit, and the drive circuit are integrated into the same chip.

9. The adaptive drive circuit for the power device as described in claim 2, characterized in that, The detection circuit also includes a capacitor Cf, which is connected between the other end of the detection capacitor and ground.

10. An electronic device, characterized in that, The adaptive drive circuit includes the power device according to any one of claims 1 to 9.

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