A multi-mode switch control method for a hybrid device based on on-state current feedback

Abstract

The embodiment of the application provides a kind of hybrid device multi-mode switch control method based on on-state current feedback, by obtaining first preset current value and second preset current value, the absolute value of the first preset current value is less than the absolute value of the second preset current value, when detecting that there is load current in circuit, it is judged whether the load current is greater than the first preset current value, if not, control field effect tube to open working mode, and control triode to close working mode;If yes, control the field effect tube and the third pipe are all opened working mode;It is judged whether the load current is greater than the second preset current value, if yes, control the field effect tube to close working mode, and control the triode to open working mode.Such, can effectively reduce the power loss of hybrid device, prolong the life of transistor hybrid use.

Description

Technical Field

[0001] This application relates to the field of electronic power systems, and in particular to a hybrid device multi-mode switching control method based on on-state current feedback. Background Technology

[0002] Currently, most power devices in power electronic devices are based on traditional silicon (Si) materials. However, due to inherent performance limitations of traditional Si materials, such as narrow bandgap, low thermal conductivity, and low critical electric field, their converters suffer from problems such as high losses, low switching frequencies, and difficulty in meeting higher blocking voltages and power factors. With changing societal demands and shifts in semiconductor performance targets, silicon carbide (SiC), recognized worldwide as a third-generation semiconductor material, possesses superior performance. Compared to traditional Si materials, it offers advantages in breakdown field strength, bandgap width, carrier saturation drift velocity, and thermal conductivity. Its lower switching losses, higher breakdown voltage, and higher thermal conductivity make it more suitable for high-power applications in high-temperature and high-voltage environments. The most representative SiC MOSFET effectively improves the efficiency and power density of power electronic converters and facilitates the miniaturization and weight reduction of power electronic devices, making it suitable for a wide range of applications. However, due to the immaturity of current SiC semiconductor device technology, its chip current carrying capacity is far lower than that of Si IGBT, and the development of related packaging technology is relatively lagging behind, resulting in a product price that is much higher than that of Si semiconductors.

[0003] Related researchers have proposed a hybrid switch method, which combines SiC MOSFETs and Si IGBTs in parallel. Figure 1 As shown, Si IGBTs serve as the main switch, while SiC MOSFETs act as auxiliary switches. Gate control effectively combines the low-cost advantage of Si IGBTs with the low switching losses and high-performance characteristics of SiC MOSFETs. However, existing gate drive methods do not fully utilize the switching characteristics of SiC MOSFETs and Si IGBTs, and the power density of hybrid devices needs further improvement. Summary of the Invention

[0004] To address the existing technical problems, this application provides a hybrid device multi-mode switching control method based on on-state current feedback that can optimize the power loss of hybrid devices.

[0005] To achieve the above objectives, the technical solution of this application embodiment is implemented as follows:

[0006] This application provides a hybrid device multi-mode switching control method based on on-state current feedback, comprising: acquiring a first preset current value and a second preset current value, wherein the absolute value of the first preset current value is less than the absolute value of the second preset current value; when a load current is detected in the circuit, determining whether the absolute value of the load current is greater than the absolute value of the first preset current value; if not, controlling the field-effect transistor to turn on the operating mode and controlling the transistor to turn off the operating mode; if yes, controlling both the field-effect transistor and the transistor to turn on the operating mode; determining whether the absolute value of the load current is greater than the absolute value of the second preset current value; if yes, controlling the field-effect transistor to turn off the operating mode and controlling the transistor to turn on the operating mode.

[0007] Optionally, obtaining the first preset current value and the second preset current value includes: obtaining a first loss curve of the field-effect transistor (FET) under load current drive when the FET is in the on-state and the transistor is in the off-state; obtaining a mixed second loss curve of the FET and the transistor under load current drive when both the FET and the transistor are in the on-state; obtaining a third loss curve of the transistor under load current drive when the FET is in the off-state and the transistor is in the on-state; obtaining a first intersection point of the first loss curve and the second loss curve, and a second intersection point of the second loss curve and the third loss curve; and determining the first preset current value corresponding to the first intersection point and the second preset current value corresponding to the second intersection point, respectively.

[0008] Optionally, the control mode in which both the field-effect transistor and the transistor are turned on includes: controlling the field-effect transistor to turn on with a turn-on delay time earlier than the transistor, and turning off with a turn-off delay time.

[0009] Optionally, it also includes setting the activation delay time to 1µs and the deactivation delay time to 1µs.

[0010] Optionally, it also includes controlling the rated current ratio of the field-effect transistor to the transistor to be 1:2.

[0011] Optionally, it also includes: using a DC voltage source to provide load current to the circuit.

[0012] Optionally, it also includes controlling the switching frequencies of the field-effect transistor and the triode to be 50kHz.

[0013] The hybrid device multi-mode switching control method based on on-state current feedback provided in this application obtains a first preset current value and a second preset current value, where the absolute value of the first preset current value is less than the absolute value of the second preset current value. When a load current is detected in the circuit, it is determined whether the load current is greater than the first preset current value. If not, the MOSFET is controlled to turn on its operating mode, and the transistor is controlled to turn off its operating mode; if so, both the MOSFET and the transistor are controlled to turn on their operating modes. It is then determined whether the load current is greater than the second preset current value. If so, the MOSFET is controlled to turn off its operating mode, and the transistor is controlled to turn on its operating mode. Thus, the hybrid device composed of MOSFETs and transistors can correspondingly turn on the operating modes of the MOSFETs and / or transistors according to the magnitude of the load current in the circuit. That is, each device in the hybrid device can adaptively turn on or off its corresponding operating mode based on the feedback of the on-state current in the circuit, effectively reducing the power loss of the hybrid device, increasing its power density, and enabling it to operate at a higher switching frequency. This also reduces junction temperature fluctuations during operation and extends the lifespan of the hybrid transistors. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the working principle of a hybrid device.

[0015] Figures 2(a)-2(d) Four different gate drive methods for hybrid devices;

[0016] Figures 3(a) and 3(b) show two application curves of the hybrid device multi-mode switching control method based on on-state current feedback in the prior art;

[0017] Figure 4 This is a flowchart of a multi-mode switching control method for hybrid devices based on on-state current feedback in one embodiment of this application;

[0018] Figure 5 This is another application curve of the existing technology of multi-mode switching control method for hybrid devices based on on-state current feedback;

[0019] Figure 6 This is a schematic diagram of the drive signals of SiC MOSFET and Si IGBT in switch mode I according to an embodiment of this application;

[0020] Figure 7 This is a schematic diagram of the drive signals of SiC MOSFET and Si IGBT in switch mode II according to one embodiment of this application;

[0021] Figure 8This is a schematic diagram of the drive signals of SiC MOSFET and Si IGBT in switch mode III according to one embodiment of this application;

[0022] Figure 9 The output characteristic diagrams for a single Si IGBT and a single SiC MOSFET in one embodiment of this application are shown.

[0023] Figure 10 This is another flowchart of a hybrid device multi-mode switching control method based on on-state current feedback in one embodiment of this application;

[0024] Figure 11 This is a main circuit diagram of the application of a hybrid device multi-mode switching control method based on on-state current feedback in one embodiment of this application;

[0025] Figure 12(a) is a simulation model of a hybrid device in one embodiment of this application, Figure 12(b) is a simulation model of a single Si IGBT in one embodiment of this application, and Figure 12(c) is a simulation model of a single SiC MOSFET in one embodiment of this application.

[0026] Figure 13 This is a simulation diagram comparing the losses in a single SiC MOSFET on-mode, a single Si IGBT on-mode, and a hybrid device on-mode in one embodiment of this application.

[0027] Figure 14 This is an application curve of a hybrid device multi-mode switching control method based on on-state current feedback in one embodiment of this application;

[0028] Figure 15(a) shows the loss difference between the segmented switching strategy and the traditional switching strategy under small load current in one embodiment of this application; Figure 15(b) shows the loss curves of the segmented switching strategy and the traditional switching strategy under large load current in one embodiment of this application. Detailed Implementation

[0029] The technical solution of this application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to limit the ways in which this application may be implemented. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0031] In the description of this application, it should be understood that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0032] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0033] Hybrid devices composed of parallel Si IGBTs and SiC MOSFETs combine the high current-carrying capacity of Si IGBTs with the low switching losses of SiC MOSFETs, meeting market demands for power electronic converters in terms of energy transfer efficiency, power density, and market price. Therefore, optimizing the losses of Si IGBT / SiC MOSFET hybrid devices is of great significance for improving system efficiency.

[0034] Existing researchers have conducted relatively detailed studies on the gate drive signal control of Si IGBT / SiC MOSFET hybrid devices. Because SiC MOSFETs have a faster switching speed, they exhibit lower switching losses than Si IGBTs. Therefore, the switching losses of hybrid devices are mainly determined by the switching losses of Si IGBTs. If the SiC MOSFET handles all the turn-on and turn-off operations in the hybrid device, the switching losses of Si IGBTs can be significantly reduced, thereby reducing the switching losses of the hybrid device.

[0035] To fully utilize the characteristics of hybrid devices composed of SiC MOSFETs and Si IGBTs connected in parallel and reduce the losses of these hybrid devices, researchers have proposed different gate control methods. Typical gate drive signals include... Figures 2(a)-2(d) As shown, there are four main gate drive methods for hybrid devices. Among them, Figure 2(a) shows a special gate drive mode used to implement zero-voltage switching (ZVS) of Si IGBTs.

[0036] The traditional hybrid device zero-voltage switching driving method requires the SiC MOSFET to output a high level one turn-on delay time earlier than the Si IGBT and output a low level one turn-off delay time later than the Si IGBT. This reliably ensures that the Si IGBT achieves zero-voltage switching, effectively combining the advantages of the high current carrying capacity of the Si IGBT and the low switching loss of the SiC MOSFET.

[0037] However, while existing gate drive methods can reduce the losses of hybrid devices, they do not fully utilize the switching characteristics of SiC MOSFETs and Si IGBTs, and the power density of hybrid devices needs further improvement. Therefore, researchers have proposed a switching method to reduce hybrid device losses, as shown in Figures 3(a) and 3(b). Switching mode I involves only the SiC MOSFET being switched; switching mode II involves the SiC MOSFET being turned on first and then off; and switching mode III involves the Si IGBT being turned on first and then off. The intersection current i between switching modes I and II is... load1 The current value corresponding to the turn-on voltage of the Si IGBT, and the current i at the intersection of switching mode II and switching mode III. load2 This represents the maximum safe operating current of the SiC MOSFET. However, this method does not significantly optimize losses in switch mode I, and the Si MOSFET remains on in switch mode III, resulting in additional conduction losses. The switching method in Figure 3(b) further simplifies the switching modes of the hybrid device based on the method in 3(a). Switch mode I involves the Si IGBT being turned on early and turned off late; switch mode II involves the SiC MOSFET being turned on early and turned off late. The method in Figure 3(b) directly ignores switch mode I, which only involves the SiC MOSFET, in Figure 3(a). At the same time, it changes the switching frequency in real time based on the load current, achieving loss optimization and EMI suppression for the hybrid device. However, the boundary current between switch mode I and switch mode II is the same as that selected in Figure 3(a), and the SiC MOSFET still has additional conduction losses in switch mode II.

[0038] The multi-mode switching control method for hybrid devices based on on-state current feedback provided in this application embodiment is available for reference. Figure 4 It includes the following steps:

[0039] S401: Obtain a first preset current value and a second preset current value, wherein the absolute value of the first preset current value is less than the absolute value of the second preset current value.

[0040] Here, the first preset current value and the second preset current value refer to the state switching current values ​​predetermined by the circuit system for starting or stopping the working mode of each device in the hybrid device. Obtaining the first preset current value and the second preset current value can refer to the control device obtaining the first preset current value and the second preset current value, where the absolute value of the first preset current value is less than the absolute value of the second preset current value.

[0041] S402: When a load current is detected in the circuit, determine whether the absolute value of the load current is greater than the absolute value of the first preset current value. If not, control the field-effect transistor to turn on the working mode and control the transistor to turn off the working mode. If yes, control both the field-effect transistor and the transistor to turn on the working mode.

[0042] Here, the field-effect transistor can be a silicon carbide field-effect transistor, i.e., a SiC MOSFET. The transistor can be a silicon transistor, i.e., a Si IGBT. The circuit can be an electronic circuit consisting of a SiC MOSFET and a Si IGBT connected in parallel. The step of determining whether the absolute value of the load current is greater than the absolute value of the first preset current when a load current is detected in the circuit, and if not, controlling the field-effect transistor to turn on and the transistor to turn off; or controlling both the field-effect transistor and the transistor to turn on, can mean: when the control device detects the absolute value of the load current in the circuit, determining whether the load current is greater than the absolute value of the first preset current, and if not, controlling the SiC MOSFET to turn on and the Si IGBT to remain off; or controlling both the SiC MOSFET and the Si IGBT to turn on.

[0043] S403: Determine whether the absolute value of the load current is greater than the absolute value of the second preset current value. If so, control the field-effect transistor to turn off the working mode and control the transistor to turn on the working mode.

[0044] The above-described hybrid device multi-mode switching control method based on on-state current feedback in the embodiments of this application can be found in the following references. Figure 5 .in,

[0045] (1) A schematic diagram illustrating the SiC MOSFET's on-state operation and the Si IGBT's off-state operation when the absolute value of the load current is less than the absolute value of the first preset current. In Switching Mode I, the drive signals for the SiC MOSFET and Si IGBT are as follows: Figure 6As shown, the Si IGBT remains in the off state, with the load current handled solely by the SiC MOSFET. When the load current is below the intersection point I1 of the SiC MOSFET and the hybrid device, the conduction loss of the single SiC MOSFET switching strategy is lower than that of the traditional hybrid device zero-voltage switching strategy. Furthermore, since only the SiC MOSFET is turned on, the switching loss of the SiIGBT is reduced. Therefore, the single SiC MOSFET switching strategy minimizes losses in the load current range (0, I1).

[0046] (2) Switching Mode II is a schematic diagram showing the operating mode where the absolute value of the load current is greater than the absolute value of the first preset current, and both the SiC MOSFET and Si IGBT are turned on. In Switching Mode II, the SiC MOSFET turns on before the Si IGBT. The drive signals for the SiC MOSFET and Si IGBT are as follows: Figure 7 As shown. Compared to Si IGBTs, SiC MOSFETs turn on first and then turn off. This switching mode is applied when the load current is higher than the intersection current I1 of the losses of the SiC MOSFET and the hybrid device, but lower than the intersection current I2 of the losses of the Si IGBT and the hybrid device. In this mode, most of the switching losses are borne by the SiC MOSFET to achieve minimum switching losses in hybrid switching. That is, during the switching process of the hybrid device, the SiC MOSFET turns on before the Si IGBT, realizing the zero-voltage turn-on process (soft turn-on) of the Si IGBT. Similarly, the SiC MOSFET turns off after the Si IGBT during the subsequent turn-off process of the hybrid device, realizing the zero-voltage turn-off process (soft turn-off) of the Si IGBT. Considering the faster switching speed of SiC MOSFETs, the turn-on delay and turn-off delay are between those of SiC MOSFETs and Si IGBTs. It is necessary to ensure that the SiC MOSFET is fully turned on before the Si IGBT is turned on, and the Si IGBT is fully turned off before the SiC MOSFET is turned off. The specific value of the delay is determined by the actual switching speed of the equipment and the dead time between the two complementary hybrid switches in the converter phase branch.

[0047] Switching mode III is a schematic diagram illustrating the SiC MOSFET switching to off mode and the Si IGBT remaining on mode when the absolute value of the load current exceeds the absolute value of the second preset current. In switching mode III, the drive signals for the SiC MOSFET and Si IGBT are as follows: Figure 8As shown, when the load current exceeds the crossover current I2 of the hybrid device and the Si IGBT, the SiC MOSFET remains off, and only the Si IGBT switches the load current. The conduction loss of the single Si IGBT switching strategy is lower than that of the traditional hybrid device zero-voltage switching strategy, and since only the Si IGBT device is turned on, the switching loss of the SiC MOSFET device is reduced. Therefore, when the load current is greater than the crossover current I2, the loss of the single Si IGBT switching strategy is minimized. Given that the market price of Si IGBTs is much lower, and that Si IGBTs have a larger rated current and higher overload capacity than SiC MOSFETs, more Si IGBTs can be connected in parallel in the hybrid switch.

[0048] Based on the analysis of switching modes I, II, and III above, the segmented switching strategy for hybrid devices proposed at the intersection point I1 of the loss curves of SiC MOSFET and hybrid devices, and the intersection point I2 of the curves of hybrid devices and Si IGBTs, can dynamically select the switching mode with the minimum loss, thereby reducing the loss of hybrid devices and further improving the efficiency of electronic power devices. In other words, the hybrid device multi-mode switching control method based on on-state current feedback provided in this application involves the control device acquiring a first preset current value and a second preset current value. When a load current is detected in the circuit, the control device determines the magnitude of the load current relative to the first and second preset current values. When the absolute value of the load current is less than the first preset current value, the MOSFET is controlled to turn on its operating mode. When the load current is greater than the first preset current value, both the MOSFET and the transistor are controlled to turn on their operating modes. When the load current is greater than the second preset current value, the MOSFET is controlled to turn off its operating mode, and the transistor is controlled to turn on its operating mode. Thus, the hybrid device composed of MOSFETs and transistors can turn on the operating modes of the MOSFETs and / or transistors according to the magnitude of the load current in the circuit. That is, each device in the hybrid device can adaptively turn on or off the corresponding operating mode based on the feedback of the on-state current in the circuit, so as to effectively reduce the power loss of the hybrid device, increase the power density of the hybrid device, and enable the hybrid device to operate at a higher switching frequency. To a certain extent, it also reduces the junction temperature fluctuation during the operation of the hybrid device and extends the life of the hybrid transistors.

[0049] In some embodiments, obtaining the first preset current value and the second preset current value includes: obtaining a first loss curve of the field-effect transistor (FET) under load current driving when the FET is in an on-state and the transistor is in an off-state; obtaining a mixed second loss curve of the FET and the transistor under load current driving when both the FET and the transistor are in an on-state; obtaining a third loss curve of the transistor under load current driving when the FET is in an off-state and the transistor is in an on-state; obtaining a first intersection point of the first loss curve and the second loss curve, and a second intersection point of the second loss curve and the third loss curve; and determining a first preset current value corresponding to the first intersection point and a second preset current value corresponding to the second intersection point, respectively.

[0050] The losses of hybrid devices include three main parts: turn-on loss, turn-off loss, and conduction loss. The turn-on loss and turn-off loss of hybrid devices are usually referred to as switching losses. When using the traditional Si IGBT zero-voltage switching mode shown in Figure 2(a), the mathematical models of the switching losses and conduction losses of hybrid devices are introduced as follows. The mathematical model of the switching losses of hybrid devices is shown in equation (1).

[0051]

[0052] E in equation (1) total_1 E represents the sum of the turn-on and turn-off losses of a hybrid device, i.e., the switching loss of the hybrid device. IGBT E represents the switching loss of the IGBT. turn_ton1 and E turn_toff1 E represents the turn-on loss and turn-off loss of the IGBT, respectively. MOS E represents the switching loss of a SiC MOSFET. turn_ton2 and E turn_toff2 i represents the turn-on loss and turn-off loss of a SiC MOSFET, respectively. MOS This represents the current flowing through the SiC MOSFET during switching, V. F t represents the voltage drop during the switching process of a SiC MOSFET. on_MOS and t off_MOS These represent the turn-on and turn-off times of the SiC MOSFET, respectively.

[0053] The conduction loss of the hybrid device is shown in equation (2).

[0054]

[0055]

[0056] E in equations (2) and (3) cond_MOS Econd_IGBT R represents the conduction losses of SiC MOSFET and SiIGBT in the hybrid device, respectively. MOS With R IGBT T represents the equivalent on-resistance of the SiC MOSFET and the Si IGBT, respectively. MOS_on With T IGBT_on I represents the conduction time of the SiC MOSFET and the Si IGBT, respectively. L V represents the load current flowing through the hybrid device. knee with I knee This represents the turn-on voltage and corresponding critical load current of the Si IGBT in the hybrid device. Because of the Si IGBT's turn-on voltage, when the on-state voltage drop of the hybrid device is less than the V0 of the Si IGBT... knee At this time, the Si IGBT is not conducting, and the SiCMOSFET in the hybrid device carries all the load current; when the on-state voltage drop of the hybrid device is greater than the V of the Si IGBT... knee In the hybrid device, the SiC MOSFET and SiIGBT share the load current. Therefore, combining equations (1), (2), and (3) yields the total loss E of the hybrid device. total Expressed as

[0057] E total =E total_1 +E cond_MOS +E cond_IGBT (4),

[0058] According to the expression for the total loss of hybrid devices, if the efficiency of power electronic devices is to be improved, the loss of hybrid devices in the safe operating domain needs to be further optimized while ensuring the reliable operation of hybrid devices.

[0059] The output characteristics of a single Si IGBT and a single SiC MOSFET are as follows: Figure 9 As shown in the curve, the output characteristic curves of the Si IGBT and SiC MOSFET intersect at point A (1.05V, 6A). This indicates that when the load current is below 6A, most of the current flows through the SiC MOSFET. When the load current is above 6A, the Si IGBT will primarily handle the load current distribution. In other words, as the on-state current of the hybrid device increases, the equivalent on-state resistance of the Si IGBT will gradually decrease compared to the equivalent on-state resistance of the SiC MOSFET, leading to increased conduction losses in the SiC MOSFET. Figure 9Analysis shows that, without considering the switching losses of the devices, under the same load current, the SiC MOSFET has lower conduction losses when the load current is small, and the Si IGBT has a smaller on-state equivalent resistance (i.e., a larger slope) when the load current is large.

[0060] Here, when the state of obtaining the MOSFET's on-state and the transistor's off-state is described, the first loss curve of the MOSFET under the load current can refer to the loss curve of a single SiC MOSFET. When the state of obtaining both the MOSFET and the transistor's on-state is described, the mixed second loss curve of the MOSFET and the transistor under the load current can refer to the mixed loss curve of both the SiC MOSFET and the Si IGBT under the on-state. When the state of obtaining the MOSFET's off-state and the transistor's on-state is described, the third loss curve of the transistor under the load current can refer to the loss curve of a single Si IGBT under the load current in the on-state. Obtaining the first intersection point of the first and second loss curves, and the second intersection point of the second and third loss curves, and determining the first preset current value corresponding to the first intersection point and the second preset current value corresponding to the second intersection point, can mean that the conduction loss curves of a single SiC MOSFET and a single Si IGBT intersect the conduction loss curve of a traditional hybrid device switching strategy at current I, respectively. 1_on I 2_on That is, in the load current range (0, I) 1_on Within the load current range, SiCMOSFET has the lowest conduction loss, while using only Si IGBT for switching control results in the highest conduction loss, which is (I 1_on I 2_on Within this range, the traditional hybrid device switching strategy has the lowest conduction loss, while using only SiC MOSFETs for switching control results in the highest conduction loss, especially when the load current is greater than I. 2_on At this point, the conduction loss generated by using only Si IGBTs for switching control is the lowest, followed by the conduction loss generated by the traditional hybrid device switching strategy. Combining the above analysis of the conduction loss magnitudes in different load current ranges, in the three load current ranges (0, I... 1_on ), (I 1_on I 2_on ) and I 2_onIn the above cases, by using a single SiC MOSFET, a traditional hybrid device switch, and a single SiC MOSFET switch strategy respectively, the conduction loss of the device can always be minimized throughout the entire switching cycle.

[0061] Based on the above analysis of conduction losses under three different switching strategies, if switching losses are considered, there are still intersection points I1 for the loss curves of a single SiC MOSFET and a traditional hybrid device switching strategy, and I2 for the loss curves of a single Si IGBT and a traditional hybrid device switching strategy. In these cases, the loss curves are jointly determined by the switching loss and conduction loss curves. Within the load current range (0, I1), the single SiC MOSFET switching strategy generates the minimum loss. Within the load current range (I1, I2), the traditional hybrid device switching strategy generates the minimum loss. When the load current is greater than I2, the single Si IGBT switching strategy generates the minimum loss. Therefore, the device's loss can be kept to a minimum throughout the entire switching cycle. Thus, the acquisition of the first and second preset current values ​​described in this application's embodiments is actually for obtaining the operating mode state of the hybrid device, thereby adjusting the switching strategy of the hybrid device according to different load current ranges, further reducing the total loss of the hybrid device, and thus improving the operating efficiency of the power electronic device.

[0062] In some embodiments, the control mode in which both the field-effect transistor and the transistor are turned on includes: controlling the field-effect transistor to turn on with an earlier turn-on delay time than the transistor, and to turn off with a later turn-off delay time.

[0063] Here, controlling the MOSFET to turn on with a turn-on delay time relative to the transistor can mean that the control device controls the SiC MOSFET to turn on with a turn-on delay time relative to the Si IGBT. In this way, most of the switching losses are borne by the SiC MOSFET, thereby achieving the minimum switching losses of the hybrid switch, that is, realizing the zero-voltage turn-on process (soft turn-on) of the Si IGBT. Similarly, controlling the MOSFET to turn off with a turn-off delay time relative to the transistor can mean that the control device controls the SiC MOSFET to turn off with a turn-off delay time relative to the Si IGBT, thereby realizing the zero-voltage turn-off process (soft turn-off) of the Si IGBT.

[0064] The embodiments of this application can effectively reduce the total loss of hybrid devices when there is load current in the circuit, and significantly improve the working efficiency of power electronic devices.

[0065] In some embodiments, the hybrid device multi-mode switching control method based on on-state current feedback further includes: setting one turn-on delay time to 1µs and one turn-off delay time to 1µs.

[0066] In some embodiments, the hybrid device multi-mode switching control method based on on-state current feedback further includes: controlling the rated current ratio of the field-effect transistor to the transistor to be 1:2.

[0067] In some embodiments, the hybrid device multi-mode switching control method based on on-state current feedback further includes: using a DC voltage source to provide load current to the circuit.

[0068] In some embodiments, the hybrid device multi-mode switching control method based on on-state current feedback further includes controlling the switching frequencies of the field-effect transistor and the transistor to be 50 kHz.

[0069] For a more comprehensive description of the embodiments of this application, please refer to [link / reference needed]. Figure 10 This is a specific flowchart of a multi-mode switching control method for hybrid devices based on on-state current feedback provided in an embodiment of this application. The method can be applied to control equipment and includes:

[0070] S1001: The control equipment determines the model of Si IGBT and SiC MOSFET in the hybrid device and the switching frequency used.

[0071] S1002: The control device acquires the first loss curve of a single SiC MOSFET in its turn-on operating mode;

[0072] S1003: The control device acquires the second loss curve when both SiC MOSFET and Si IGBT are in the on-state operating mode;

[0073] S1004: The control device acquires the third loss curve of a single Si IGBT in its operating mode.

[0074] S1005: The control device acquires the first intersection point I1 of the first loss curve and the second loss curve;

[0075] S1006: The control device acquires the second intersection point I2 of the second loss curve and the third loss curve;

[0076] S1007: The control device determines whether the absolute value of the load current is greater than the absolute value of the first preset current value; if not, proceed to S1008; if yes, proceed to S1009.

[0077] S1008: Control device controls the single SiC MOSFET to turn on and operate in the specified mode;

[0078] S1009; The control device controls both SiC MOSFET and Si IGBT to be in working mode.

[0079] S1010: The control device determines whether the absolute value of the load current is greater than the absolute value of the second preset current value. If so, execute S1011.

[0080] S1011: The control device controls the single Si IGBT to start working mode.

[0081] To verify the reliability of the hybrid device multi-mode switching control method based on on-state current feedback described in the embodiments of this application, the experimental verification process is described below:

[0082] The more SiC MOSFETs connected in parallel in a hybrid switch, the lower its conduction and switching losses. However, due to the currently high price of SiC MOSFETs, lower power-rated SiC MOSFETs are typically used to limit the increased cost of hybrid devices caused by SiC devices. Therefore, the hybrid device used in this patent application consists of one Si IGBT (IGW40N120H3_L1, 1200V / 40A) and one SiC MOSFET (C2M0160120D, 1200V / 18A), wherein the rated current ratio of the SiC MOSFET to the Si IGBT is approximately 1:2.

[0083] Main circuit diagram as follows Figure 11 As shown, DC represents a DC voltage source used to provide the load current of the circuit; R1 is the resistance of the load; R2 and L1 are the parasitic resistance and inductance of the main circuit, respectively, and their values ​​are very small; R3 and C1 represent the RC snubber circuit of the Si IGBT; R4 and C2 represent the RC snubber circuit of the SiC MOSFET; R5 and R6 are the driving resistors of the Si IGBT and SiC MOSFET, respectively; the Si IGBT model is IGW40N120H3_L1; the SiC MOSFET model is C2M0160120D; Vgate1 and Vgate2 are the driving voltages of the Si IGBT and SiC MOSFET, respectively; since the parasitic inductance and capacitance values ​​of each device are very small, their impact on the experimental results of this invention is negligible, and this invention does not consider the role of the parasitic inductance and capacitance of the devices. The switching frequency f is 50KHz. The turn-on delay time and turn-off delay time of the hybrid device greatly affect the loss of the hybrid device. The turn-on delay time and turn-off delay time can be set to 1µs.

[0084] To compare the losses of SiC MOSFETs, Si IGBTs, and hybrid devices under different load currents, this patented technology constructed simulation models of SiC MOSFET / Si IGBT hybrid devices, single SiC MOSFETs, and single Si IGBT devices in LTspice software. The simulation models are shown below. Figures 12(a)-12(c)As shown in the figure, Figure 12(a) is the simulation model of the hybrid device, Figure 12(b) is the simulation model of the single Si IGBT, and Figure 12(c) is the simulation model of the single SiC MOSFET. The switching losses of these devices under different load currents are compared and analyzed, and the simulation loss comparison results are as follows: Figure 13 As shown.

[0085] Depend on Figure 13 It can be obtained that the intersection point of losses between the single SiC MOSFET switching strategy and the traditional hybrid device switching strategy is I1 = 2.8A, and the intersection point of losses between the single Si IGBT switching strategy and the traditional hybrid device switching strategy is I2 = 26.1A. The existence of the intersection points I1 and I2 of the loss curves in the simulation results successfully verifies the inference in this patent application. Among them, when the load current is lower than 2.8A, the loss curve of SiC MOSFET is always below the loss curve of hybrid device, that is, the loss of SiC MOSFET is always less than the loss of hybrid device. When the load current range is (2.8, 26.1), the loss curve of hybrid device is always below the loss curves of SiC MOSFET and Si IGBT. When the load current range is (26.1, I2), the loss curve of hybrid device is always below the loss curves of SiC MOSFET and Si IGBT. max When I is in this case, the loss curve of Si IGBT is always below the loss curve of SiC MOSFET and hybrid devices, where I max The maximum pulse current of the parallel SiC MOSFET in the hybrid device is limited. Therefore, the new strategy proposed in this patent technology can be represented by the following three modes:

[0086] Switching mode I: When the load current 0 < I < 2.8A, only the SiC MOSFET is used for switching, and the Si IGBT remains in the off state. In this range, the single SiC MOSFET switching strategy can minimize the losses generated by the device in one switching cycle.

[0087] Switching Mode II: When the load current is 2.8A < I < 26.1A, the traditional hybrid device switching strategy is adopted, that is, the SiC MOSFET turns on earlier than the Si IGBT, and the Si IGBT is turned off after it is completely turned off. In this range, this switching strategy can minimize the loss generated by the device in one switching cycle.

[0088] Switching Mode III: When the load current is 26.1A < I < I max In this configuration, only the Si IGBT is used for switching, while the SiC MOSFET remains off. Within this range, the single SiC MOSFET switching strategy can minimize the losses generated by the device in a single switching cycle.

[0089] The segmented switching strategy based on load current proposed in this application optimizes the hybrid device in the load current ranges (0, 2.8), (2.8, 26.1), and (26.1, 1). max The loss on the device was reduced, achieving the goal of optimizing the efficiency of the hybrid device across the entire operating domain.

[0090] The following is a simulation verification of this invention patent, with a load current I = 40sin(wt). The waveform of the load current is as follows. Figure 13 As shown, since the SiC MOSFET is model C2M0160120D and its maximum pulse current is 40A, in order to ensure the reliable operation of the hybrid device, I is selected. max =40A.

[0091] Due to the symmetry of the sine wave, this invention simplifies the loss analysis model by using 1 / 4 of its period. Figure 14 It can be seen that switch mode I is applied at (0,t0), switch mode II is applied at (t0,t1), and switch mode III is applied at (t1,t2). That is, a segmented switching strategy based on the load current is adopted at this time.

[0092] Traditional hybrid device switching strategies consistently cause the SiC MOSFET to turn on with a turn-on delay time earlier than the Si IGBT and turn off with a turn-off delay time in the (0,t2) time interval. Combining these two different switching strategies, a relevant model was built on LTspice for simulation analysis, and the simulation results are shown in the figure below. Figure 14 As shown.

[0093] Based on the above analysis, it can be seen that the hybrid device multi-mode switching control method based on on-state current feedback proposed in this application differs from the traditional hybrid device switching strategy in terms of (0, t0) and (t1, t2). From the loss difference curves of the segmented switching strategy and the traditional hybrid device switching strategy under small load current in Figure 15(a), it can be seen that as the load current gradually increases to I1 (2.8A), the loss difference first increases and then decreases to 0. When the load current is around 1.5A, the loss difference is 0.016μJ, reaching its maximum value. From the comparison of the loss curves in the (t1, t2) time period in Figure 15(b), it can be seen that there is a significant difference between the loss curves of the segmented switching strategy and the traditional hybrid device switching strategy under large load current. The loss curve of the segmented switching strategy is consistently below that of the traditional hybrid device switching strategy, and the difference between the two increases with increasing load current. When the load current is 40A, the loss of the segmented switching strategy is reduced by 18%. The loss values ​​of the segmented switching strategy and the traditional switching strategy under large load current are shown in Table 1.

[0094] Table 1 Loss values ​​of different switching strategies under high load current.

[0095]

[0096] Therefore, based on the analysis of the loss curves of the segmented switching strategy and the traditional switching strategy under small load current and large load current, it can be concluded that the hybrid device multi-mode switching control method based on on-state current feedback proposed in this application has lower losses in the load current range of (0, t0) and (t1, t2). That is, the segmented switching strategy will generate less loss than the traditional switching strategy throughout the entire switching cycle, thereby verifying that the segmented switching strategy proposed in this invention is more conducive to improving device efficiency.

[0097] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application is limited.

Claims

1. A multi-mode switching control method for hybrid devices based on on-state current feedback, characterized in that, include: Obtain a first preset current value and a second preset current value, and the absolute value of the first preset current value. The absolute value is less than the second preset current value; When a load current is detected in the circuit, it is determined whether the absolute value of the load current is greater than the absolute value of the first preset current value. If not, control the MOSFET to turn on and control the transistor to turn off. If so, both the field-effect transistor and the transistor will be turned on. Determine whether the absolute value of the load current is greater than the absolute value of the second preset current value. If so, control the field-effect transistor to operate in the off mode and control the transistor to operate in the on mode; The process of obtaining the first preset current value and the second preset current value includes: The first loss curve of the field-effect transistor under the load current drive is obtained when the field-effect transistor is in the on-state and the transistor is in the off-state. Obtain the mixed second loss curve of the field-effect transistor and the transistor under load current drive when both the field-effect transistor and the transistor are in the working mode; The third loss curve of the transistor under the load current is obtained when the field-effect transistor is in the off working mode and the transistor is in the on working mode. Obtain the first intersection point of the first loss curve and the second loss curve, and the second intersection point of the second loss curve and the third loss curve; The first preset current value corresponding to the first intersection point and the second preset current value corresponding to the second intersection point are determined respectively.

2. The hybrid device multi-mode switching control method based on on-state current feedback as described in claim 1, characterized in that, The operating modes where both the control field-effect transistor and the transistor are enabled include: The field-effect transistor is controlled to turn on with a turn-on delay time earlier than the transistor, and to turn off with a turn-off delay time later.

3. The hybrid device multi-mode switching control method based on on-state current feedback as described in claim 2, characterized in that, Also includes: The activation delay time is set to 1µs, and the deactivation delay time is set to 1µs.

4. The hybrid device multi-mode switching control method based on on-state current feedback as described in claim 1, characterized in that, Also includes: The rated current ratio of the field-effect transistor to the transistor is controlled to be 1:

2.

5. The hybrid device multi-mode switching control method based on on-state current feedback as described in claim 1, characterized in that, Also includes: A DC voltage source is used to provide load current to the circuit.

6. The hybrid device multi-mode switching control method based on on-state current feedback as described in claim 1, characterized in that, Also includes: The switching frequencies of the field-effect transistor and the transistor are controlled to be 50 kHz.

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