Control method and control circuit for a hybrid device

Abstract

Embodiments of the present application provide a control method and control circuit of a hybrid device, and relate to the technical field of electronics. The hybrid device comprises a first switch tube and a second switch tube connected in parallel. The control method comprises: obtaining a load current; the load current is a current flowing through a load. If the load current is less than a first current, the first switch tube is controlled to be turned on, and the second switch tube is controlled to be turned off; the first current is a turning point current of the first switch tube. If the load current is greater than the first current and less than a second current, the first switch tube is controlled to be turned on, and then the second switch tube is controlled to be turned on; the second current is a maximum pulse current of the first switch tube. If the load current is greater than the second current, the second switch tube is controlled to be turned on, and then the first switch tube is controlled to be turned on; after the first switch tube is controlled to be turned off, the second switch tube is controlled to be turned off. The control method can reduce the operating loss of the hybrid device.

Description

Technical Field

[0001] This disclosure relates to the field of electronic technology, and in particular to a control method and control circuit for a hybrid device. Background Technology

[0002] Currently, most power electronic converters are traditional silicon-based insulated-gate bipolar transistors (Si IGBTs). However, due to inherent limitations in the material, such as narrow bandgap, low thermal conductivity, and low critical electric field, Si IGBT converters suffer from high losses, low switching frequencies, and difficulty in meeting higher blocking voltages and power factors. With the development of semiconductor materials such as silicon carbide (SiC), its superior performance has been gradually discovered. For example, SiC semiconductor devices have advantages in breakdown field strength, bandgap width, carrier saturation drift velocity, and thermal conductivity. Its lower losses, higher breakdown voltage, and higher thermal conductivity make it more suitable for high-power applications in high-temperature and high-voltage environments. Among semiconductor devices made of SiC materials, SiC metal-oxide-semiconductor field-effect transistors (MOSFETs) have a wide range of applications because they can effectively improve the efficiency and power density of power electronic converters and easily achieve the goals of lightweighting and miniaturization of power electronic devices.

[0003] Because the process technology for SiC semiconductor devices is not yet mature, their current carrying capacity is far lower than that of Si IGBTs. Furthermore, the packaging of SiC semiconductor devices currently uses Si device packaging technology, resulting in relatively lagging development and significantly higher product prices compared to Si semiconductors.

[0004] Chinese patent publication number CN 114301269A proposes to combine SiC MOSFETs and Si IGBTs in parallel to form a... Figure 1A The hybrid device shown in the patent controls the on / off state of the SiC MOSFET and Si IGBT based on the load current flowing through it, thereby reducing losses. The control method for the hybrid device provided in this patent includes, for example... Figure 1B The switch mode A shown is similar to... Figure 1CThe diagram illustrates switching mode B. When the load current is less than the current that the SiC MOSFET can withstand, the hybrid device is controlled using switching mode A, where the SiC MOSFET turns on before the Si IGBT and turns off after the Si IGBT. In this case, the SiC MOSFET primarily bears the switching losses of the hybrid device, while the Si IGBT primarily bears the conduction losses. When the load current is greater than the current that the SiC MOSFET can withstand but less than the rated current of the Si IGBT, the hybrid device is controlled using switching mode B, where the SiC MOSFET turns on after the Si IGBT and turns off before the Si IGBT. In this case, the Si IGBT primarily bears the switching losses of the hybrid device, and both devices share the conduction losses.

[0005] However, the method in Chinese Patent No. CN 114301269A does not fully utilize the switching characteristics of SiC MOSFETs and Si IGBTs, and the use of the same constant drive voltage for SiC MOSFETs cannot further reduce losses. Summary of the Invention

[0006] The purpose of the embodiments of this disclosure is to provide a control method and control circuit for a hybrid device, which controls the on and off of SiC MOSFET and Si IGBT according to the load current flowing through the hybrid device, and further reduces losses by controlling the drive voltage of SiC MOSFET and Si IGBT.

[0007] To achieve the above objectives, the embodiments of this disclosure provide the following technical solutions:

[0008] On one hand, a control method for a hybrid device is provided. The hybrid device is connected in series between a power source and a load, and is configured to control the switching on and off of the load and the power source. The hybrid device includes a first switch and a second switch, which are connected in parallel. The control method includes: acquiring a load current; the load current is the current flowing through the load. If the load current is less than a first current, then controlling the first switch to turn on and controlling the second switch to turn off; the first current is the inflection point current of the first switch. If the load current is greater than the first current but less than the second current, then controlling the first switch to turn on and then controlling the second switch to turn on. And, controlling the second switch to turn off and then controlling the first switch to turn off; the second current is the maximum pulse current of the first switch. And, if the load current is greater than the second current, then controlling the second switch to turn on and then controlling the first switch to turn on, and controlling the first switch to turn off and then controlling the second switch to turn off.

[0009] The control method for the hybrid device described above utilizes the switching characteristics of SiC MOSFET and Si IGBT to control the on and off states of SiC MOSFET and Si IGBT based on the load current flowing through the hybrid device, thereby reducing the losses of the hybrid device.

[0010] In some embodiments, if the load current is less than the first current or greater than the second current, controlling the first switch to turn on includes: providing a voltage of 20V to the control electrode of the first switch.

[0011] In some embodiments, if the load current is greater than a first current and less than a third current, controlling the first switch to turn on includes: providing a voltage of 20V to the control electrode of the first switch; the third current is the rated current value of the first switch. If the load current is greater than the third current and less than a second current, controlling the first switch to turn on includes: providing a voltage of 15V to the control electrode of the first switch.

[0012] In some embodiments, controlling the first switch to turn off includes providing a voltage of -5V to the control electrode of the first switch.

[0013] In some embodiments, controlling the second switch to turn on includes: providing a voltage of 15V to the control electrode of the second switch; controlling the second switch to turn off includes: providing a voltage of -5V to the control electrode of the second switch.

[0014] In some embodiments, the first switching transistor is a silicon carbide metal-oxide-semiconductor field-effect transistor, and the gate of the first switching transistor is the gate of the silicon carbide metal-oxide-semiconductor field-effect transistor; the second switching transistor is a silicon-based insulated-gate bipolar transistor; and the gate of the second switching transistor is the gate of the silicon-based insulated-gate bipolar transistor.

[0015] On the other hand, a control circuit for a hybrid device is provided. The hybrid device is connected in series between a power supply and a load, and is configured to control the switching on and off of the load and the power supply; the hybrid device includes a first switch and a second switch. The control circuit for the hybrid device includes a current detection circuit, a controller, and a drive circuit. The current detection circuit is connected to the load and is configured to acquire the load current. The controller is connected to the current detection circuit, the first switch, and the second switch, and is configured to output a control signal for the first switch, a control signal for the second switch, and a timing signal for the drive circuit based on the load current. The drive circuit is connected to the controller, the first switch, and the second switch, and is configured to provide a voltage of 20V, 15V, or -5V to the control terminal of the first switch, and a voltage of 15V or -5V to the control terminal of the second switch, based on the control signal of the first switch, the control signal of the second switch, and the timing signal.

[0016] In some embodiments, the controller includes a first controller and a second controller. The first controller is configured to output control signals for a first switching transistor and a second switching transistor. The second controller is connected to the first controller and the current detection circuit, and is configured to output a timing signal based on the load current, the first control signal, and the second control signal.

[0017] In some embodiments, the timing signals include a first timing signal, a second timing signal, and a third timing signal. The first timing signal instructs the drive circuit to provide a voltage of 20V or -5V to the control terminal of the first switching transistor according to the first timing signal. The second timing signal instructs the drive circuit to provide a voltage of 15V or -5V to the control terminal of the first switching transistor according to the second timing signal. The third timing signal instructs the drive circuit to provide a voltage of 15V or -5V to the control terminal of the second switching transistor according to the third timing signal.

[0018] In some embodiments, the driving circuit includes a first driving circuit, a second driving circuit, and a third driving circuit. The first driving circuit is connected to a second controller and a first switching transistor, and is configured to provide a voltage of 20V or -5V to the control electrode of the first switching transistor according to a control signal and a first timing signal. The second driving circuit is connected to the second controller and the first switching transistor, and is configured to provide a voltage of 15V or -5V to the control electrode of the first switching transistor according to a control signal and a second timing signal. The third driving circuit is connected to the second controller and the second switching transistor, and is configured to provide a voltage of 15V or -5V to the control electrode of the second switching transistor according to a control signal and a third timing signal.

[0019] The beneficial effects of this invention are: the control method and control circuit of the hybrid device proposed in this invention can use different driving voltage values ​​and device switching sequences based on the magnitude of the load current. While ensuring the reliability of the hybrid device, it reduces the operating loss of the hybrid device, thereby effectively reducing the operating junction temperature of the hybrid device, improving the service life of the device, and increasing the switching frequency of the hybrid device, thereby improving the power quality and efficiency of the power output of the power electronic device. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in this disclosure, the accompanying drawings used in some embodiments of this disclosure will be briefly described below. Obviously, the drawings described below are only drawings of some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings. In addition, the drawings described below can be regarded as schematic diagrams and are not intended to limit the actual size of the product, the actual flow of the method, the actual timing of the signals, etc. involved in the embodiments of this disclosure.

[0021] Figure 1A A structural diagram of a hybrid device proposed in Chinese Patent Publication No. CN 114301269A;

[0022] Figure 1B A timing diagram of a hybrid device proposed in Chinese Patent Publication No. CN 114301269A;

[0023] Figure 1C Another timing diagram of a hybrid device proposed in Chinese Patent Publication No. CN 114301269A;

[0024] Figure 2 This is a structural diagram of a hybrid device according to some embodiments;

[0025] Figure 3 This is a flowchart of a control method for a hybrid device according to some embodiments;

[0026] Figure 4 Output characteristic curves of Si IGBT and SiC MOSFET;

[0027] Figure 5 This is a schematic diagram of the switching modes of a hybrid device corresponding to different load currents according to some embodiments;

[0028] Figure 6A The driving voltage and timing diagram of a first switch and a second switch according to some embodiments;

[0029] Figure 6B Here is a driving voltage and timing diagram for another first and second switching transistor according to some embodiments;

[0030] Figure 6C Here is a driving voltage and timing diagram of the first and second switching transistors according to some embodiments;

[0031] Figure 6D Here is a driving voltage and timing diagram of a first switch and a second switch according to some embodiments;

[0032] Figure 7 This is a simulation circuit diagram according to some embodiments;

[0033] Figure 8 This is a schematic diagram illustrating the relationship between the loss optimization data and the load current based on Table 2.

[0034] Figure 9 This is another simulation circuit diagram according to some embodiments;

[0035] Figure 10 In order to be in Figure 9The simulation circuit shown is a schematic diagram of the switching modes of the hybrid device proposed in Chinese Patent No. CN 114301269A, which corresponds to different load currents.

[0036] Figure 11 According to some embodiments in Figure 9 The simulation circuit shown is a schematic diagram of the switching modes of the hybrid device corresponding to different load currents.

[0037] Figure 12 This is a structural diagram of the control circuit of another hybrid device according to some embodiments;

[0038] Figure 13 This is a structural diagram of the control circuit of another hybrid device according to some embodiments;

[0039] Figure 14 This is a structural diagram of the control circuit of another hybrid device according to some embodiments;

[0040] Figure 15 This is a circuit diagram of a control circuit for a hybrid device according to some embodiments. Detailed Implementation

[0041] The technical solutions in some embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments provided in this disclosure are within the scope of protection of this disclosure.

[0042] The present invention provides a control method and control circuit for a hybrid device. The control method and control circuit for the hybrid device are described by way of example below.

[0043] Embodiments of the present invention provide a control method for hybrid devices. For example... Figure 2 As shown, the hybrid device 10 is connected in series between the power supply 20 and the load 30, and is configured to control the on and off states between the load 30 and the power supply 20. The hybrid device 10 includes a first switch 101 and a second switch 102, which are connected in parallel.

[0044] In some embodiments, as shown in FIG1, the first switching transistor 101 is a silicon carbide metal-oxide-semiconductor field-effect transistor (SiC MOSFET), and the second switching transistor 102 is a silicon-based insulated-gate bipolar transistor (Si IGBT). In this case, the losses of the hybrid device include three main parts: turn-on loss, turn-off loss, and conduction loss. The turn-on loss and turn-off loss of the hybrid device are usually collectively referred to as switching losses. The mathematical models for switching losses and conduction losses are described below.

[0045] The mathematical model for conduction loss is as follows.

[0046] Since Si IGBT is a bipolar device, its conduction characteristic has a turn-on voltage. When the load current is small, the on-state voltage drop of the hybrid device is less than the turn-on voltage of the Si IGBT. At this time, the Si IGBT inside the hybrid device is not conducting, and all current flows only through the SiC MOSFET. This inflection point current value can be expressed as Equation (1).

[0047]

[0048] Vth is the turn-on voltage of the Si IGBT, Rds is the on-resistance of the SiC MOSFET, and Iknee is the inflection point current of the hybrid device. If the load current of the hybrid device is less than Iknee, only the SiC MOSFET is turned on inside the hybrid device. If the load current of the hybrid device is greater than Iknee, the hybrid device is turned on by both the SiC MOSFET and the Si IGBT.

[0049] Based on the shunting characteristics inside the hybrid device, the conduction loss of the hybrid device is shown in equations (2) to (7).

[0050]

[0051]

[0052]

[0053]

[0054]

[0055] E 总 =E cond_MOS (V gs ,I F ,T j_MOS )+E cond_IGBT (I F ,T j_IGBT (7)

[0056] Equation (2) represents the conduction loss of the SiC MOSFET in the hybrid device, and Equation (3) represents the conduction loss of the Si IGBT in the hybrid device. Wherein, I... F I represents the total current of the hybrid device. mos V is the current flowing through the SiC MOSFET. gs T is the drive voltage of the SiC MOSFET. j_IGBT T j_MOSThese are the junction temperatures of Si IGBT and SiC MOSFET, respectively, and R... ce R ds These are the on-resistances of the Si IGBT and SiC MOSFET, respectively. Using equations (2) to (7), the conduction losses of the SiC MOSFET and Si IGBT inside the hybrid device under different load currents and drive voltages can be calculated.

[0057] The mathematical model of conduction loss has been described in detail above. The mathematical model of switching loss includes the mathematical model of turn-on loss and the mathematical model of turn-off loss. The mathematical model of switching loss is as follows.

[0058] The turn-on loss of hybrid devices is related to the turn-on and turn-off timing of SiC MOSFETs and Si IGBTs, as well as the drive delay time T. on_delay Related to the drive delay time T on_delay This refers to the time when the SiC MOSFET turns on before the Si IGBT, i.e., after the SiC MOSFET is turned on, a drive delay time T elapses. on_delay Then, the Si IGBT is turned on. The turn-on loss of the hybrid device consists of the turn-on loss of the SiCMOSFET and the turn-on loss of the Si IGBT. The loss model of the hybrid device is shown in Equations (8) to (11).

[0059]

[0060]

[0061]

[0062]

[0063] Among them, E on_MOS E on_IGBT The turn-on losses of SiC MOSFET and Si IGBT are t, respectively. on_1 , t on_2 Vgs and Vgs_ref represent the turn-on times of the Si IGBT and SiC MOSFET, respectively, while Vgs and Vgs_ref represent the drive voltage and reference drive voltage of the SiC MOSFET, respectively. F I ref These are the total current and the total current reference value for the hybrid device, respectively, V DC V DC_ref These represent the total current and the total current reference value for the hybrid device, respectively, T. cs_on_MOS and T cs_on_IGBT These are the temperature correction factors for hard turn-on losses of SiC MOSFETs and Si IGBTs, respectively, a1, b1, c1, a2, b2, c2, b gs_MOSc I_MOS d DC_MOS b gs_IGBT c I_IGBT d DC_IGBT It is a constant.

[0064] Equation (8) represents the turn-on loss of the SiC MOSFET in the hybrid device, and Equation (9) represents the turn-on loss of the Si IGBT in the hybrid device. Using these two formulas, the turn-on losses of the SiC MOSFET and Si IGBT inside the hybrid device under different load currents, drive delays, and drive voltages can be calculated.

[0065] The turn-off losses of the internal components of the hybrid device mainly include the turn-off losses of the Si IGBT, the hard turn-off losses of the SiC MOSFET, and the turn-off losses of the SiC MOSFET at T... off_delay The additional conduction loss within the device consists of three main parts. First, as shown in the following equation, the turn-off loss of the SiC MOSFET in the hybrid device is composed of the hard turn-off loss of the SiC MOSFET and the turn-off loss of the SiC MOSFET at T... off_delay The internal turn-off loss of the hybrid device consists of two parts: the turn-off loss of the Si IGBT, the hard turn-off loss of the SiC MOSFET, and the additional turn-off loss of the SiC MOSFET within Toff_delay.

[0066] As shown in equations (12) to (14), the turn-off loss of the SiC MOSFET in the hybrid device consists of two parts: the hard turn-off loss of the SiC MOSFET and the additional conduction loss of the SiC MOSFET within Toff_delay.

[0067] E off_MOS (T off_delay V gs ) = E off_hard_MOS +ΔE con (T off_delay V gs (12)

[0068]

[0069]

[0070] In equations (12) to (14), E off_MOS E off_hard_MOS ΔE con These are the total turn-off loss, hard turn-off loss, and T value of the SiC MOSFET. off_delay Additional conduction loss within, k gs_MOS m I_MOSn DC_MOS These are the nonlinear correction coefficients for the hard turn-off losses of SiC MOSFETs on the device drive voltage, on-current, and bus voltage, respectively. off_delay It is the turn-off delay of the hybrid device, T CS_off_MOS It is the temperature correction factor for the hard turn-on loss of SiC MOSFET.

[0071] There are two cases for the Si IGBT device turn-off in the hybrid device. When the Si IGBT turns off before the SiC MOSFET, the hybrid device is soft turn-off, and its loss model is shown in Equation (15). When the Si IGBT turns off after the SiC MOSFET, the hybrid device is hard turn-off, and its loss model is shown in Equation (16).

[0072]

[0073]

[0074] In equations (15) and (16), E off_IGBT E off_hard_IGBT These are the turn-off loss and hard turn-off loss of the Si IGBT, respectively. E res τ is the residual loss of the Si IGBT, and τ is the exponential decay coefficient of the turn-off loss and turn-off delay of the Si IGBT. These two parameters can be extracted from the hybrid device dual-pulse test.

[0075] The mathematical model described above is a hybrid device loss model considering the driving voltage of the SiC MOSFET. As can be seen from the operating characteristics of SiC MOSFETs, increasing the driving voltage reduces the turn-on and turn-off times, thereby lowering the switching losses. Conversely, increasing the driving voltage also reduces the on-resistance of the SiC MOSFET, further reducing its conduction losses.

[0076] As can be seen from the above analysis, under the premise of ensuring reliable operation of the hybrid device, the loss of the hybrid device can be reduced by adjusting the turn-on and turn-off driving timing of SiC MOSFET and Si IGBT in the hybrid device, as well as the turn-on driving voltage of SiC MOSFET and Si IGBT.

[0077] Based on the above analysis, such as Figure 3 As shown, the control method includes steps 301 to 304.

[0078] Step 301: Obtain the load current.

[0079] Understandably, load current is the current flowing through the load.

[0080] Step 302: If the load current is less than the first current, control the first switch to turn on and control the second switch to turn off; the first current is the inflection point current of the first switch.

[0081] In some embodiments, if the load current is less than the first current, controlling the first switch to turn on includes: providing a voltage of 20V to the control electrode of the first switch.

[0082] Step 303: If the load current is greater than the first current but less than the second current, then after controlling the first switch to turn on, control the second switch to turn on; and after controlling the second switch to turn off, control the first switch to turn off; the second current is the maximum pulse current of the first switch.

[0083] In some embodiments, if the load current is greater than the first current and less than the third current, controlling the first switch to turn on includes: providing a voltage of 20V to the control electrode of the first switch. The third current is the rated current value of the SiC first switch.

[0084] In some embodiments, if the load current is greater than the third current and less than the second current, controlling the first switch to turn on includes providing a voltage of 15V to the control electrode of the first switch. Controlling the first switch to turn off includes providing a voltage of -5V to the control electrode of the first switch.

[0085] Step 304: If the load current is greater than the second current, then control the second switch to turn on, then control the first switch to turn on, and control the first switch to turn off, then control the second switch to turn off.

[0086] In some embodiments, if the load current is greater than the second current, controlling the first switch to turn on includes providing a 20V voltage to the control electrode of the first switch. Controlling the first switch to turn off includes providing a -5V voltage to the control electrode of the first switch.

[0087] In steps 302 to 304, controlling the second switch to turn on includes providing a 15V voltage to the control electrode of the second switch; controlling the second switch to turn off includes providing a -5V voltage to the control electrode of the second switch.

[0088] Understandably, if the first switch 101 is a SiC MOSFET, the control electrode of the first switch 101 can be the gate of the SiC MOSFET. If the second switch 102 is a Si IGBT, the control electrode of the second switch can be the gate of the Si IGBT.

[0089] The output characteristic curves of Si IGBT and SiC MOSFET are as follows: Figure 4As shown below, the control method for the hybrid device provided by this invention will be explained in conjunction with the output characteristic curves of Si IGBT and SiCMOSFET.

[0090] SiC MOSFETs are unipolar devices, such as Figure 4 As shown, the conduction characteristic curve of a SiC MOSFET has no inflection point voltage. During operation, a SiC MOSFET can be approximated as a resistor with a very small resistance. In contrast, a Si IGBT is a bipolar device, such as... Figure 4 As shown, the conduction characteristic curve of a Si IGBT has an inflection point voltage, which is the turn-on voltage of the Si IGBT. Therefore, if the load current is small and the on-state voltage drop of the hybrid device is less than the turn-on voltage of the Si IGBT, the Si IGBT will not conduct, and the entire load current will flow through the SiC MOSFET. Figure 4 It can be seen that the load current I1 corresponding to the turn-on voltage is the inflection point current of the hybrid device.

[0091] like Figure 5 and Figure 6A As shown, if the load current is less than the first current, i.e. the inflection point current value I1 of the hybrid device, the hybrid device operates in switching mode I.

[0092] The explanation for switching mode I is as follows: If the load current flowing through the hybrid device is less than the inflection point current of the hybrid device, the SiC MOSFET turns on. However, the voltage drop across the hybrid device is less than the turn-on voltage of the Si IGBT, so the Si IGBT in the hybrid device does not turn on. In this case, the SiC MOSFET uses a drive voltage of +20V / -5V. On the one hand, the +20V drive voltage reduces the switching and conduction losses of the SiC MOSFET. On the other hand, because the load current is small, even though the +20V drive voltage increases the current overshoot during the device turn-on process compared to the +15V drive voltage, it is far less than the maximum pulse current that the SiC MOSFET can withstand, thus ensuring the reliability of the hybrid device. The Si IGBT uses a -5V drive voltage, keeping the Si IGBT always off.

[0093] like Figure 5 and Figure 6B As shown, when the load current is greater than the first current, i.e. the inflection point current value I1 of the hybrid device, but less than the third current, i.e. the rated current value I2 of the SiC MOSFET, the hybrid device operates in switching mode II.

[0094] The explanation of Switching Mode II is as follows: If the load current flowing through the hybrid device is greater than the inflection point current of the hybrid device, the SiC MOSFET turns on. Since the voltage drop across the hybrid device is greater than the turn-on voltage of the Si IGBT, the Si IGBT in the hybrid device also turns on. At this time, the hybrid device uses a switching sequence where the SiC MOSFET turns on first and then turns off, enabling soft turn-on and soft turn-off of the Si IGBT, thereby reducing the switching losses of the Si IGBT. Simultaneously, because the load current is less than the rated current of the SiC MOSFET, the SiC MOSFET can withstand the current overshoot during the device turn-on process caused by the +20V drive voltage. Therefore, under the premise of ensuring reliability, a drive voltage of +20V / -5V is used for the SiC MOSFET to reduce the switching and conduction losses of the SiC MOSFET and improve the operating efficiency of the hybrid device. A drive voltage of +15V / -5V is used for the Si IGBT.

[0095] like Figure 5 and Figure 6C As shown, when the load current is greater than the third current, i.e. the rated current value I2 of the SiC MOSFET, and less than the second current, i.e. the maximum pulse current value I3 that the SiC MOSFET can withstand, the hybrid device operates in switching mode III.

[0096] The explanation for switching mode III is as follows: If the load current flowing through the hybrid device is greater than the rated current of the SiC MOSFET in the hybrid device, but less than the maximum pulse current of the SiC MOSFET, then during the switching process of the hybrid device, it is necessary to suppress the turn-on current of the hybrid device to prevent the SiC MOSFET from being damaged by electrical stress. Therefore, the hybrid device also adopts the switching sequence of SiC MOSFET turning on first and then turning off, while the SiC MOSFET adopts a driving voltage of +15V / -5V. The lower driving voltage can suppress the electrical stress overshoot of the hybrid device and ensure the reliability of the hybrid device. At the same time, the Si IGBT adopts a driving voltage of +15V / -5V.

[0097] like Figure 5 and Figure 6D As shown, when the load current is greater than the second current, i.e. the maximum pulse current value I3 that the SiC MOSFET can withstand, the hybrid device operates in switching mode IV.

[0098] The explanation for switching mode IV is as follows: If the load current flowing through the hybrid device exceeds the maximum pulse current that the SiC MOSFET can withstand, the reliability of the SiC MOSFET in the hybrid device needs to be ensured during the switching process. Therefore, the hybrid device adopts a switching sequence of SiC MOSFET turning on first and then turning off first. At this time, the SiC MOSFET is in the soft-turn-on and soft-turn-off stage. Therefore, the SiC MOSFET uses a drive voltage of +20V / -5V to reduce the switching loss and conduction loss of the SiC MOSFET and improve the operating efficiency of the hybrid device. At the same time, the Si IGBT uses a drive voltage of +15V / -5V.

[0099] In some embodiments, the inflection point current I1, the rated current I2 of the SiC MOSFET, and the maximum pulse current I3 of the SiC MOSFET can be determined using a hybrid device test platform. By simultaneously driving the two internal switches of the hybrid device—that is, turning on the SiC MOSFET with a +20V drive voltage and turning on the Si IGBT with a +15V drive voltage—the on-state voltage drop across the Si IGBT is measured. When the on-state voltage drop across the Si IGBT exceeds the turn-on voltage specified in the Si IGBT datasheet, the load current I1 is the inflection point current. The rated current I2 of the SiC MOSFET can be obtained from the SiC MOSFET datasheet. The maximum pulse current I3 that the SiC MOSFET can withstand has two limiting factors: first, the hybrid device drive delay time, i.e., the maximum value of the time the SiC MOSFET turns on before the Si IGBT and the time the SiC MOSFET turns off after the Si IGBT; and second, the bus voltage that the hybrid device withstands. By referring to the SiC MOSFET datasheet, the maximum pulse current value that the hybrid device can withstand under the drive delay and bus voltage can be selected as the maximum pulse current value I3 that the SiC MOSFET can withstand.

[0100] For example, based on the determined inflection point current value I1 of the hybrid device, the rated current value I2 of the SiC MOSFET, and the maximum pulse current value I3 of the SiC MOSFET, it is possible to determine which range the load current value is in and decide which operating mode the hybrid device adopts, thereby realizing the control of the hybrid device.

[0101] The following example uses the Si IGBT IGW25N120H3 (1200V / 25A) and the SiC MOSFET C2M0160120D (1200V / 12A) as an example, with a rated current ratio of approximately 2:1 between the Si IGBT and SiC MOSFET. Based on LTSPICE simulation software, a simulation model is built as follows: Figure 7 The simplified simulation circuit diagram is shown.

[0102] Figure 7 In the simulation, U1 is a Si IGBT (model IGW25N120H3, 1200V / 25A), U2 is a SiC MOSFET (model C2M0160120D, 1200V / 12A), voltage source V1 simulates the DC bus voltage during the switching process of the device (800V is selected in the simulation), voltage source V3 represents the case temperature of the SiC MOSFET (set to a constant 25℃ in the simulation), and current source I1 simulates the load current during the switching process. L1 is the stray inductance of the circuit. V5 and V2 are the drive voltages for the Si IGBT and SiC MOSFET, respectively. V5 is a pulse waveform, where PULSE(-5 15 1u 10n 10n 18u 40u 1) represents the -5V turn-off voltage, 15V forward voltage, 1µs delay, 10ns voltage rise time, 10ns voltage fall time, 18µs forward voltage turn-on time, 40µs cycle time, and one cycle, respectively. V2 is also a pulse waveform, where PULSE(-5 20 0u 10n 10n 20u 40u 1) represents the -5V turn-off voltage, 20V forward voltage, 0µs delay, 10ns voltage rise time, 10ns voltage fall time, 20µs forward voltage turn-on time, 40µs cycle time, and one cycle, respectively. Rigbt and Rmos are the drive resistors for the Si IGBT and SiC MOSFET, respectively. D1 is a diode.

[0103] First, the inflection point current of the hybrid device was determined. The SiC MOSFET was continuously turned on with a constant +20V drive voltage, and the Si IGBT was continuously turned on with a constant +15V drive voltage. According to the Si IGBT datasheet, its turn-on voltage is approximately 0.7V. The simulation involved changing the load current flowing through the hybrid device using a constant current source, and then detecting the current flowing through the SiC MOSFET and Si IGBT, as well as the on-state voltage drop across the hybrid device. The simulation results are shown in Table 1.

[0104] Table 1. Current distribution and voltage drop inside the hybrid device under different load currents.

[0105] <![CDATA[I 负载 (A)]]> <![CDATA[I MOS (A)]]> <![CDATA[I IGBT (A)]]> <![CDATA[V 压降 (V)]]> 1 1.00 0 0.15 2 2.00 0 0.30 3 2.99 0.01 0.45 4 3.94 0.06 0.60 5 4.72 0.28 0.70 6 5.25 0.75 0.80

[0106] Simulation results show that when the load current is less than 5A, the SiC MOSFET carries almost all the load current, while the current flowing through the Si IGBT is tens to hundreds of milliamps. The on-state voltage drop of the hybrid device is less than 0.7V, at which point the Si IGBT is not turned on. When the load current is 5A, the load current flowing through the SiC MOSFET is 4.72A, and the load current flowing through the Si IGBT is 0.28A. The on-state voltage drop of the hybrid device is equal to 0.7V, at which point the Si IGBT is turned on. Therefore, the inflection point current of the hybrid device is approximately 5A.

[0107] Secondly, the rated current and maximum pulse current of the SiC MOSFET need to be determined. The rated current of the SiC MOSFET, obtained from the datasheet, is 12A. In this patent, the switching delay between the two devices within the hybrid device is set to 1µs. Therefore, the SiC MOSFET turns on 1µs earlier. Since the switching time of the SiC MOSFET is in the tens of nanoseconds, it bears all the load current of the hybrid device during this period. Therefore, it is necessary to determine the maximum pulse current of the SiC MOSFET within the 1µs time. The SiC MOSFET datasheet indicates that the maximum pulse current is 18A.

[0108] Therefore, in the current range of [0A, 5A), the hybrid device adopts switching mode I; in the current range of [5A, 12A), the hybrid device adopts switching mode II; in the current range of [12A, 18A), the hybrid device adopts switching mode III; and in the current range of [18A, 25A], the hybrid device adopts switching mode IV.

[0109] according to Figure 7 The simulation model of the hybrid device shown is used to perform simulation calculations for the current range of 0 to 25A with 1A intervals, to compare the control method of the hybrid device provided in the embodiments of the present invention (i.e., switching mode I to switching mode IV) with the control method of the hybrid device mentioned in Chinese Patent No. CN114301269A (i.e., switching mode A and switching mode B). The simulation results are shown in Table 2.

[0110] Table 2 Total losses of traditional strategy and proposed strategy under different load currents.

[0111]

[0112] In Table 2, "loss optimization" refers to the difference between the loss of the control method for the hybrid device provided in this embodiment and the loss of the control method for the hybrid device mentioned in Chinese Patent Publication No. CN114301269A. The "loss optimization percentage" refers to the ratio of the loss optimization to the loss of the control method for the hybrid device mentioned in Chinese Patent CN114301269A. A larger value for loss optimization or loss optimization percentage indicates that the control method for the hybrid device provided in this embodiment can further reduce losses. The loss optimization data in Table 2 is summarized in a graph, as shown below. Figure 8 As shown.

[0113] According to Table 2 and Figure 8 It can be seen that when the load current is less than 12A, the loss optimization is greater than 0, and the loss optimization increases with the increase of the load current. This indicates that the switching modes I and II of the control method for the hybrid device provided in this embodiment can greatly reduce the loss of the hybrid device. When the load current is in the range of 12A to 18A, the optimized loss is 0 because the control method for the hybrid device provided in this embodiment is the same as the control method for the hybrid device mentioned in Chinese Patent Publication No. CN114301269A. When the load current is greater than 18A, the loss optimization is greater than 0, and the loss optimization increases with the increase of the load current. This indicates that in the control method for the hybrid device provided in this embodiment, switching mode IV can further reduce the loss of the hybrid device and improve the operating efficiency of the hybrid device.

[0114] As can be seen, the control method for hybrid devices provided in the embodiments of the present invention can reduce the losses of hybrid devices and improve their operating efficiency.

[0115] To further verify that the control method for hybrid devices provided in this embodiment can reduce the losses and improve the operating efficiency of hybrid devices, a simulation of the application of hybrid devices in an inverter is performed next, such as... Figure 9 As shown, Figure 9 This is a simplified simulation circuit diagram for the application of hybrid devices in an inverter. The current source is set to I = 25sin(314t), indicating that one current cycle is 20ms. Due to the symmetry of the current and to simplify the simulation calculation, a quarter current cycle (i.e., 5ms) is simulated. The switching frequency of the hybrid device is 25kHz, and the switching timing is set to 20us on and 20us off to simulate the half-bridge structure in the inverter. Within the quarter current cycle, the following methods are used: Figure 10 The switch modes A and B shown are as follows, and... Figure 11 The simulation data for switch modes I to IV are shown in Table 3.

[0116] As shown in Table 3, when the load current is in range I (0A, 5A), the total loss of the hybrid device control method provided in this embodiment of the invention is reduced by 86uJ compared to the total loss of the hybrid device control method mentioned in Chinese Patent Publication No. CN114301269A, representing a reduction of 8.32%. When the load current is in range II (5A, 12A), the total loss of the hybrid device control method provided in this embodiment of the invention is reduced by 882uJ compared to the total loss of the hybrid device control method mentioned in Chinese Patent Publication No. CN114301269A, representing a reduction of 12.77%. When the load current is in range III (12A, 18A), the hybrid device control method provided in this embodiment of the invention is the same as the hybrid device control method mentioned in Chinese Patent Publication No. CN114301269A, therefore the total loss is equal. When the load current is in range IV (18A, 25A), the total loss of the hybrid device control method provided in this embodiment of the invention is reduced by 58uJ compared to the total loss of the hybrid device control method mentioned in Chinese Patent Publication No. CN114301269A, representing a reduction of 0.23%. Therefore, within 1 / 4 cycle, the total loss of the hybrid device control method provided in this embodiment of the invention is reduced by 1026uJ compared to the total loss of the hybrid device control method mentioned in Chinese Patent Publication No. CN114301269A, representing a reduction of 2.03%.

[0117] Table 3 Losses in non-switching mode over 1 / 4 load current cycle

[0118]

[0119] Analysis of the simulation data in Tables 2 and 3 shows that the control method for hybrid devices provided in this embodiment of the invention, compared with the control method for hybrid devices mentioned in Chinese Patent No. CN114301269A, can further reduce the loss of hybrid devices and improve the operating efficiency of hybrid devices.

[0120] Based on the above exemplary descriptions and analyses, the hybrid device control method provided in this embodiment of the invention, by combining driving timing and driving voltage, reduces the overall loss of the hybrid device and improves the efficiency of the power electronic device while ensuring its reliability. The hybrid device control method provided in this embodiment of the invention can reduce the operating losses of the hybrid device, thereby effectively reducing the operating junction temperature of the hybrid device and improving its lifespan. Furthermore, the hybrid device control method provided in this embodiment of the invention can reduce the operating losses of the hybrid device, increase the switching frequency of the hybrid device, and improve the power quality output of the power electronic device.

[0121] Embodiments of the present invention also provide a control circuit for a hybrid device, such as Figure 12 As shown, the control circuit 100 of the hybrid device includes a current detection circuit 103, a controller 104, and a drive circuit 105. The current detection circuit 103 is connected to the load 30 and configured to acquire the load current. The controller 104 is connected to the current detection circuit 104, a first switch 101, and a second switch 102, and is configured to output control signals for the first switch 101, the second switch 102, and the timing signals for the drive circuit 105 based on the load current. The drive circuit 105 is connected to the controller 104, the first switch 101, and the second switch 102, and is configured to provide a voltage of 20V, 15V, or -5V to the control terminal of the first switch 101, and a voltage of 15V or -5V to the control terminal of the second switch 102, based on the control signals for the first switch 101, the second switch 102, and the timing signals for the drive circuit 105.

[0122] In some embodiments, such as Figure 13 As shown, controller 104 may include a first controller 1041 and a second controller 1042. The first controller 1041 is configured to output a control signal for a first switch 101 and a control signal for a second switch 102. The second controller 1042 is connected to the first controller 1041 and the current detection circuit 103, and is configured to output a timing signal for the drive circuit 105 based on the load current, the first control signal, and the second control signal.

[0123] In some embodiments, such as Figure 14 As shown, the driving circuit 105 includes a first driving circuit 1051, a second driving circuit 1052, and a third driving circuit 1053. In this case, the timing signals of the driving circuit 105 may include a first timing signal, a second timing signal, and a third timing signal. The first driving circuit 1051 is connected to the second controller 1042 and the first switching transistor 101, and is configured to provide a voltage of 20V or -5V to the control electrode of the first switching transistor 101 according to the control signal of the first switching transistor 101 and the first timing signal. The second driving circuit 1052 is connected to the second controller 1042 and the first switching transistor 101, and is configured to provide a voltage of 15V or -5V to the control electrode of the first switching transistor 101 according to the control signal of the first switching transistor 101 and the second timing signal. The third drive circuit 1053 is connected to the second controller 1042 and the second switch 102, and is configured to provide a voltage of 15V or -5V to the control electrode of the second switch 102 according to the control signal of the second switch 102 and the third timing signal.

[0124] The working principle of the control circuit of the hybrid device in the above embodiments will be explained below.

[0125] Understandably, such as Figure 15 As shown, the current detection circuit 103 may include a current sensor 1031, which detects the current value of the main circuit, i.e., the load current. The current detection circuit 103 transmits the acquired load current to the second controller 1042. The current detection circuit 103 may also include an integrator circuit 1032, which includes a second capacitor C2, a first resistor R1, a second resistor R2, a third resistor R3, and an operational amplifier A. Figure 15 In the current detection circuit 103, filter capacitors C1 and C3 may also be included.

[0126] For example, such as Figure 15 As shown, the second controller 1042 can be a Complex Programmable Logic Device (CPLD). The second controller 1042 can compare the current value of the load current with a preset current reference value and determine the range in which the load current value falls. Simultaneously, the first controller 1041 can issue a first control signal PWM1 and a second control signal PWM2. For example, the first controller 1041 can be a Digital Signal Processor (DSP). Based on the range in which the load current value falls, the first control signal PWM1, and the second control signal PWM2, the second controller 1042 can determine the timing signals of the drive circuit 105 through logical judgment. These timing signals include high and low levels, delay time, and sequence.

[0127] Understandably, when the drive circuit 105 includes a first drive circuit 1051, a second drive circuit 1052, and a third drive circuit 1053, the timing signals of the drive circuit 105 may include a first timing signal, a second timing signal, and a third timing signal.

[0128] For example, such as Figure 15 As shown, the first driving circuit 1051, the second driving circuit 1052, or the third driving circuit 1053 may include a pair of transistors. The structure of the second driving circuit 1052 will be described below as an example. For instance, the second driving circuit 1052 may include a first transistor Q1 and a second switching transistor Q2. The first transistor Q1 and the second switching transistor Q2 have the same parameters but opposite polarities. The base of the first switching transistor Q1 is connected to the base of the second switching transistor Q2, and the emitter of the first switching transistor Q1 is connected to the emitter of the second switching transistor Q2. The collector of the first switching transistor Q1 is connected to a +15V voltage source, and the collector of the first switching transistor Q1 is connected to a -5V voltage source.

[0129] For example, Figure 15 In this circuit, the fourth resistor R4 is the driving resistor for the turn-off process of the first switch 101, the fifth resistor R5 is the driving resistor for the turn-on process of the first switch 101, and the first diode L1 and the second diode L2 are used to ensure unidirectional current flow. The sixth resistor R6 is the driving resistor for the turn-off process of the second switch 102, the seventh resistor R7 is the driving resistor for the turn-on process of the second switch 102, and the third diode L3 and the fourth diode L4 are used to ensure current flow.

[0130] The specific implementation of the first driving circuit 1051 providing a 20V or -5V voltage to the control electrode of the first switching transistor 101 according to the control signal and the first timing signal can be referred to the switching mode I, switching mode II and switching mode IV in the control method of the above-mentioned hybrid device. The first timing signal can be respectively as follows: Figure 6A , Figure 6B and Figure 6D The timing diagram of the SiC MOSFET is shown. The specific implementation of the second drive circuit 1052 providing a 15V or -5V voltage to the control electrode of the first switch 101 based on the control signal and the second timing signal can be found in Switching Mode III of the control method for the hybrid device described above. The second timing signal can be as follows: Figure 6C The timing diagram of the SiC MOSFET is shown. The specific implementation of the third drive circuit 1053 providing a 15V or -5V voltage to the control electrode of the second switch 102 based on the control signal and the third timing signal can be found in the control methods for the hybrid device described above, specifically in switch mode I, switch mode II, switch mode III, and switch mode IV. The third timing signal can be as follows: Figure 6A , Figure 6B , Figure 6C and Figure 6D The timing diagram of the Si IGBT is shown in the figure, and will not be repeated here.

[0131] The beneficial effects of the control circuit for a hybrid device provided in the embodiments of the present invention can be referred to the beneficial effects of the control method for the hybrid device in the above embodiments, and will not be repeated here.

[0132] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A control method for a hybrid device, wherein the hybrid device is connected in series between a power source and a load, and is configured to control the on / off switching between the load and the power source; the hybrid device includes a first switch and a second switch, wherein the first switch and the second switch are connected in parallel; characterized in that, The control method includes: Obtain the load current; the load current is the current flowing through the load; If the load current is less than the first current, the first switch is turned on and the second switch is turned off; the first current is the inflection point current of the first switch. If the load current is greater than the first current but less than the second current, then after controlling the first switch to turn on, the second switch to turn on; and after controlling the second switch to turn off, the first switch to turn off; the second current is the maximum pulse current of the first switch; wherein, if the load current is greater than the first current and less than the third current, controlling the first switch to turn on includes: providing a 20V voltage to the control terminal of the first switch; the third current is the rated current value of the first switch; if the load current is greater than the third current and less than the second current, controlling the first switch to turn on includes: providing a 15V voltage to the control terminal of the first switch; and, If the load current is greater than the second current, then after controlling the second switch to turn on, the first switch to turn on is controlled; after controlling the first switch to turn off, the second switch to turn off is controlled.

2. The control method for the hybrid device according to claim 1, characterized in that, If the load current is less than the first current or greater than the second current, then controlling the first switch to turn on includes: providing a voltage of 20V to the control electrode of the first switch.

3. The control method for the hybrid device according to claim 2, characterized in that, The control of turning off the first switch includes providing a -5V voltage to the control electrode of the first switch.

4. The control method for the hybrid device according to claim 1, characterized in that, The control of the second switch to turn on includes: providing a voltage of 15V to the control electrode of the second switch; the control of the second switch to turn off includes: providing a voltage of -5V to the control electrode of the second switch.

5. The control method for the hybrid device according to claim 3 or 4, characterized in that, The first switching transistor is a silicon carbide metal-oxide-semiconductor field-effect transistor, and the gate of the first switching transistor is the control electrode of the silicon carbide metal-oxide-semiconductor field-effect transistor; the second switching transistor is a silicon-based insulated-gate bipolar transistor; the gate of the second switching transistor is the control electrode of the silicon-based insulated-gate bipolar transistor.

6. A control circuit for a hybrid device, the hybrid device being connected in series between a power source and a load, and configured to control the on / off switching between the load and the power source; the hybrid device comprising a first switching transistor and a second switching transistor, characterized in that, The hybrid device also includes: A current sensing circuit, connected to the load, is configured to acquire the load current. A controller, connected to the current detection circuit, the first switching transistor, and the second switching transistor, is configured to: output a control signal for the first switching transistor, a control signal for the second switching transistor, and a timing signal for the drive circuit based on the load current; wherein the timing signal includes: a first timing signal instructing the drive circuit to provide a 20V voltage to the control electrode of the first switching transistor according to the first timing signal; a second timing signal instructing the drive circuit to provide a 15V voltage to the control electrode of the first switching transistor according to the second timing signal; and The drive circuit is connected to the controller, the first switch, and the second switch, and is configured to: Based on the control signal of the first switch, the control signal of the second switch, and the timing signal, a voltage of 20V, 15V, or -5V is provided to the control electrode of the first switch; and a voltage of 15V or -5V is provided to the control electrode of the second switch.

7. The control circuit for the hybrid device according to claim 6, characterized in that, The controller includes: A first controller is configured to output control signals for a first switch and a second switch; and The second controller is connected to the first controller and the current detection circuit, and is configured to output the timing signal based on the load current, the first control signal and the second control signal.

8. The control circuit for the hybrid device according to claim 7, characterized in that, The timing signal further includes: a third timing signal, used to instruct the driving circuit to provide a voltage of 15V or -5V to the control electrode of the second switching transistor according to the third timing signal; The first timing signal is also used to instruct the drive circuit to provide a -5V voltage to the control electrode of the first switching transistor according to the first timing signal; The second timing signal is also used to instruct the drive circuit to provide a -5V voltage to the control electrode of the first switching transistor according to the second timing signal.

9. The control circuit for the hybrid device according to claim 8, characterized in that, The driving circuit includes: A first driving circuit is connected to the second controller and the first switching transistor, and is configured to provide a voltage of 20V or -5V to the control electrode of the first switching transistor according to the control signal of the first switching transistor and the first timing signal. The second driving circuit is connected to the second controller and the first switching transistor, and is configured to provide a voltage of 15V or -5V to the control electrode of the first switching transistor according to the control signal of the first switching transistor and the second timing signal. A third driving circuit, connected to the second controller and the second switching transistor, is configured to provide a voltage of 15V or -5V to the control electrode of the second switching transistor according to the control signal of the second switching transistor and the third timing signal.

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