Miller voltage sampling circuit of power tube, driving circuit and electronic equipment

Abstract

The invention provides a Miller voltage sampling circuit of a power tube, a driving circuit and electronic equipment. The Miller voltage sampling circuit obtains the gate-source voltage of the power tube in the switching process through the voltage dividing unit, and carries out voltage dividing and filtering on the gate voltage. And the sampling unit amplifies the divided and filtered voltage to obtain and output the Miller voltage of the power tube. According to the invention, the filtering of the gate-source voltage of the power tube in the switching process is realized through the voltage dividing unit, and the power tube is not easily influenced by the oscillation of the gate-source voltage, so that the loss and stress of the power tube are reduced, the power tube is not easily damaged, and the safe operation of the power tube is ensured. According to the sampling circuit provided by the invention, the Miller voltage of the power tube in the switching process can be accurately obtained, the segmented control of the grid current of the power tube is realized through the driving circuit, the switching action quality of the power tube can be improved, and the rapid control of the power tube is realized.

Description

Technical Field

[0001] The present application relates to the field of power electronics technology, and in particular to a Miller voltage sampling circuit, a driving circuit and an electronic device for a power tube. Background Art

[0002] Power tubes such as SiC Metal-Oxide-Semiconductor Field-EffectTransistor (SiC MOSFET) have the characteristics of high thermal conductivity, low on-state impedance and low parasitic parameters, and have been widely used in various electronic equipment. However, since the switching speed of the power tube is very fast, generally in the nanosecond level, the driving circuit of the power tube during the switching process needs to quickly and accurately collect the Miller voltage of the power tube to achieve segmented control of the power tube.

[0003] The driving circuit may include a sampling circuit, through which the Miller voltage of the power tube can be sampled. The sampling circuit provided in the related art generally implements the sampling of the Miller voltage through a first voltage-dividing resistor and a second voltage-dividing resistor connected in series. It can be seen that the sampling circuit provided in the related art is easily affected by the oscillation of the gate-source voltage, which not only causes a large loss of the power tube, but also causes the power tube to be damaged due to high stress. Summary of the invention

[0004] In order to solve the problem of large power tube loss and damage due to high stress in the prior art, the present application provides a Miller voltage sampling circuit for a power tube, which may include a voltage divider unit and a sampling unit. The voltage divider unit is connected to the gate and source of the power tube, and the voltage divider unit is also connected to the sampling unit.

[0005] The voltage divider unit is used to obtain the gate-source voltage of the power tube during the switching process, and to divide and filter the gate-source voltage.

[0006] The sampling unit is used to amplify the voltage after voltage division and filtering, and output the Miller voltage of the power tube.

[0007] Optionally, the first input end of the voltage divider unit is connected to the gate of the power tube, the second input end of the voltage divider unit is connected to the source of the power tube, the output end of the voltage divider unit is connected to the input end of the sampling unit, and the output end of the sampling unit is used to output the Miller voltage of the power tube.

[0008] In some possible implementations, the voltage dividing unit includes a voltage dividing resistor, a first voltage dividing capacitor, and a second voltage dividing capacitor.

[0009] The first end of the voltage-dividing resistor serves as the first input end of the voltage-dividing unit, and the second end of the second voltage-dividing capacitor serves as the second input end of the voltage-dividing unit. The second end of the voltage-dividing resistor is connected to the first end of the first voltage-dividing capacitor. The second end of the first voltage-dividing capacitor is connected to the first end of the second voltage-dividing capacitor as the output end of the voltage-dividing unit.

[0010] In some other possible implementations, the sampling unit includes a sampling capacitor, a first transmission gate, a second transmission gate, and an amplifier.

[0011] The positive terminal of the sampling capacitor is connected to the first terminal of the second transmission gate as the input terminal of the sampling unit. The negative terminal of the sampling capacitor and the first terminal of the first transmission gate are both connected to the inverting input terminal of the amplifier, and the second terminal of the first transmission gate and the non-inverting input terminal of the amplifier are both connected to the ground terminal. The second terminal of the second transmission gate is connected to the output terminal of the amplifier as the output terminal of the sampling unit.

[0012] Furthermore, the sampling unit also includes a third transmission gate, a fourth transmission gate and a voltage stabilizing capacitor.

[0013] The first end of the third transmission gate is used as the input end of the sampling unit, the second end of the third transmission gate is connected to the positive end of the sampling capacitor, and the second end of the third transmission gate is connected to the first end of the second transmission gate. The first end of the fourth transmission gate is connected to the output end of the amplifier. The second end of the fourth transmission gate is connected to the positive end of the voltage stabilizing capacitor as the output end of the sampling unit. The negative end of the voltage stabilizing capacitor is connected to the ground end.

[0014] Exemplarily, the working phases of the Miller voltage sampling circuit include a sampling phase, an amplification phase and a holding phase.

[0015] Optionally, during the sampling phase, a Miller voltage sampling circuit is used to:

[0016] The first transmission gate and the third transmission gate are controlled to be turned on, and the second transmission gate and the fourth transmission gate are controlled to be turned off, so as to charge the sampling capacitor.

[0017] Optionally, during the amplification stage, a Miller voltage sampling circuit is used to:

[0018] The first transmission gate and the third transmission gate are controlled to be turned off, and the second transmission gate and the fourth transmission gate are controlled to be turned on, and the voltage after voltage division and filtering is amplified by the amplifier and the Miller voltage of the power tube is output.

[0019] Optionally, during the hold phase, a Miller voltage sampling circuit is used to:

[0020] The first transmission gate, the third transmission gate and the fourth transmission gate are all controlled to be turned off, and the third transmission gate is controlled to be turned on, so that the Miller voltage of the power tube is stored through the voltage stabilizing capacitor.

[0021] Exemplarily, the first transmission gate, the second transmission gate, the third transmission gate and the fourth transmission gate are all CMOS transmission gates.

[0022] A CMOS transmission gate includes a P-type field effect transistor (ie, PMOS) and an N-type field effect transistor (ie, NMOS) connected in parallel.

[0023] On the other hand, the present application also provides a driving circuit, including the above-mentioned Miller voltage sampling circuit.

[0024] Optionally, the driving circuit may further include a comparator, and the Miller voltage sampling circuit may be connected to an input terminal of the comparator.

[0025] Of course, the driving circuit may also be other parts, which is not limited in this application.

[0026] On the other hand, the present application also provides an electronic device, including the above-mentioned driving circuit.

[0027] Optionally, the electronic device may be a converter, a frequency converter, etc. Of course, the electronic device may also be other devices, which is not limited in this application.

[0028] Compared with the prior art, the beneficial effects of this application are:

[0029] The Miller voltage acquisition circuit provided in the present application obtains the gate-source voltage of the power tube during the switching process through a voltage divider unit, and divides and filters the gate voltage. The voltage after voltage division and filtering is amplified by the sampling unit to obtain the Miller voltage of the power tube and output it. It can be seen that the present application realizes the filtering of the gate-source voltage of the power tube during the switching process through the voltage divider unit, which is not easily affected by the oscillation of the gate-source voltage, thereby reducing the loss and stress of the power tube, not easily damaging the power tube, and ensuring the safe operation of the power tube.

[0030] The voltage divider circuit in the present application includes a voltage divider unit including a voltage divider resistor, a first voltage divider capacitor and a second voltage divider capacitor, that is, an RCC structure is adopted, which can compensate for the gate impedance, input capacitance and output capacitance of the power tube, so that the Miller voltage sampling is not easily distorted, that is, the reliability of the sampling is improved.

[0031] The sampling circuit provided in the present application can accurately obtain the Miller voltage of the power tube during the switching process, and then realize segmented control of the gate current of the power tube through the driving circuit, which can improve the switching action quality of the power tube and realize rapid control of the power tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the present application or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0033] Figure 1 A schematic structural diagram of a Miller voltage acquisition circuit in an embodiment of the present application;

[0034] Figure 2 is another schematic structural diagram of the Miller voltage acquisition circuit in the embodiment of the present application;

[0035] Figure 3 is another schematic structural diagram of the Miller voltage acquisition circuit in the embodiment of the present application;

[0036] Figure 4 This is an equivalent circuit diagram of the Miller voltage acquisition circuit in the sampling stage in the embodiment of the present application;

[0037] Figure 5 This is an equivalent circuit diagram of the Miller voltage acquisition circuit in the amplification stage in the embodiment of the present application;

[0038] Figure 6 : is an equivalent circuit diagram of the Miller voltage acquisition circuit in the holding stage in the embodiment of the present application. DETAILED DESCRIPTION

[0039] The technical solution in this application will be described below in conjunction with the accompanying drawings.

[0040] The terms "first", "second", etc. in the specification embodiments, claims, and drawings of the present application are only used for the purpose of distinguishing descriptions, and cannot be understood as indicating or implying relative importance, nor can they be understood as indicating or implying order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, including a series of steps or units. The method, system, product, or device is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products, or devices.

[0041] It should be understood that in the present application, "at least one (item)" means one or more, and "plurality" means two or more. "And / or" is used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, "A and / or B" can mean: only A exists, only B exists, and A and B exist at the same time, where A and B can be singular or plural. The character " / " generally indicates that the objects associated before and after are in an "or" relationship. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

[0042] The present application embodiment provides a Miller voltage sampling circuit for a power tube, such as Figure 1 The Miller voltage sampling circuit 10 of the power tube includes a voltage dividing unit 1 and a sampling unit 2. The voltage dividing unit 1 is connected to the gate G and the source S of the power tube, and the voltage dividing unit 1 is also connected to the sampling unit 2.

[0043] The voltage divider unit 1 is used to obtain the gate-source voltage of the power tube during the switching process, and divide and filter the gate-source voltage to obtain the voltage after voltage division and filtering (which can be represented by v1).

[0044] Sampling unit 2 is used to amplify the voltage v1 after voltage division and filtering, and output the Miller voltage of the power tube (which can be expressed as v out express).

[0045] Optional, such as Figure 1 As shown, the first input terminal IN11 of the voltage divider unit 1 is connected to the gate G of the power tube, the second input terminal IN12 of the voltage divider unit 1 is connected to the source S of the power tube, the output terminal OUT1 of the voltage divider unit 1 is connected to the input terminal IN2 of the sampling unit 2, and the output terminal OUT2 of the sampling unit 2 is used to output the Miller voltage v of the power tube out .

[0046] In some embodiments, Figure 2 As shown, the voltage dividing unit 1 includes a voltage dividing resistor R1, a first voltage dividing capacitor CG1 and a second voltage dividing capacitor CG2.

[0047] The first end of the voltage-dividing resistor R1 serves as the first input end of the voltage-dividing unit 1, and the second end of the second voltage-dividing capacitor CG2 serves as the second input end of the voltage-dividing unit 1. The second end of the voltage-dividing resistor R1 is connected to the first end of the first voltage-dividing capacitor CG1. The second end of the first voltage-dividing capacitor CG1 is connected to the first end of the second voltage-dividing capacitor CG2, serving as the output end of the voltage-dividing unit 1.

[0048] In other embodiments, reference Figure 2 The sampling unit 2 includes a sampling capacitor CS, a first transmission gate S1, a second transmission gate S2 and an amplifier A. The amplifier A may be an operational amplifier or the like.

[0049] The positive terminal of the sampling capacitor CS is connected to the first terminal of the second transmission gate S2 as the input terminal of the sampling unit 2. The negative terminal of the sampling capacitor CS and the first terminal of the first transmission gate S1 are both connected to the inverting input terminal of the amplifier A, and the second terminal of the first transmission gate S1 and the non-inverting input terminal of the amplifier A are both connected to the ground terminal. The second terminal of the second transmission gate S2 is connected to the output terminal of the amplifier A as the output terminal of the sampling unit 2.

[0050] For further reference, Figure 3 The sampling unit 2 further includes a third transmission gate S3, a fourth transmission gate S4 and a voltage stabilizing capacitor CS.

[0051] The first end of the third transmission gate S3 serves as the input end of the sampling unit 2, the second end of the third transmission gate S2 is connected to the positive end of the sampling capacitor CS, and the second end of the third transmission gate S3 is connected to the first end of the second transmission gate S2. The first end of the fourth transmission gate S4 is connected to the output end of the amplifier A. The second end of the fourth transmission gate S4 is connected to the positive end of the voltage stabilizing capacitor CS as the output end of the sampling unit 2. The negative end of the voltage stabilizing capacitor CS is connected to the ground end.

[0052] Exemplarily, the first transmission gate S1 , the second transmission gate S2 , the third transmission gate S3 and the fourth transmission gate S4 are all CMOS transmission gates.

[0053] Optionally, the CMOS transmission gate includes a P-type field effect transistor (ie, PMOS) and an N-type field effect transistor (ie, NMOS) connected in parallel.

[0054] Exemplarily, the working phases of the Miller voltage sampling circuit 10 include a sampling phase, an amplification phase, and a holding phase.

[0055] Optionally, the Miller voltage sampling circuit 10 in the sampling stage, the amplification stage and the holding stage are respectively equivalent circuit diagrams as shown in FIG. Figure 4 , Figure 5 and Figure 6 shown.

[0056] In the sampling phase, the Miller voltage sampling circuit 10 is used to:

[0057] like Figure 4 As shown, the first transmission gate S1 and the third transmission gate S3 are controlled to be turned on, and the second transmission gate S2 and the fourth transmission gate S4 are controlled to be turned off, so as to charge the sampling capacitor CS. Figure 4In FIG. 1 , RON1 represents the on-resistance of the first transmission gate S1, and RON2 represents the on-resistance of the third transmission gate S3. GS Indicates the gate-source voltage of the power tube during the switching process.

[0058] During the sampling phase, the voltage across the sampling capacitor CS is CS It is necessary to track the changes of the voltage v1 after voltage division and filtering. Therefore, in the sampling phase, the first transmission gate S1 and the third transmission gate S3 remain turned on, and the second transmission gate S2 and the fourth transmission gate S4 are turned off. The voltage division unit 1 collects the gate-source voltage V GS , the voltage v1 after voltage division and filtering is obtained through the voltage division unit 1. Since the first transmission gate S1 is turned on, the voltage v1(t) after voltage division and filtering at time t and the voltage v across the sampling capacitor CS at time t are CS (t) respectively satisfy:

[0059]

[0060] In the formula, C S Indicates the capacitance of the sampling capacitor CS, C G1 Represents the capacitance of the first voltage divider capacitor CG1, C G2 Represents the capacitance of the second voltage divider capacitor CG2, C G represents the equivalent capacitance of the first voltage-dividing capacitor CG1 and the second voltage-dividing capacitor CG2 in series, R G1 is the resistance of the voltage divider resistor, R ON It is the series equivalent resistance of the on-resistance RON1 of the first transmission gate S1 and the on-resistance RON2 of the third transmission gate S3.

[0061] In the amplification stage, the Miller voltage sampling circuit 10 is used to:

[0062] like Figure 5 As shown, the first transmission gate S1 and the third transmission gate S3 are both turned off, and the second transmission gate S2 and the fourth transmission gate S4 are both turned on, and the voltage v1 after voltage division and filtering is amplified by the amplifier A and the Miller voltage v of the power tube is output. out .

[0063] In the amplification stage, the inverting input of amplifier A is regarded as a virtual ground due to the high gain. Due to the law of charge conservation, the charge stored on the sampling capacitor CS does not change, so that the output voltage of amplifier A is equal to the voltage across the sampling capacitor CS at the last moment of the sampling stage, thereby completing the sampling of the Miller voltage.

[0064] When the states of the first transmission gate S1, the second transmission gate S2, and the third transmission gate S3 are switched, the charge in the transistor channel constituting the transmission gate will be injected into the sampling capacitor CS, which is prone to sampling errors caused by charge injection. The sampling error can be reduced by first disconnecting the first transmission gate S1, then disconnecting the third transmission gate S2, and finally closing the second transmission gate S2.

[0065] In the holding phase, the Miller voltage sampling circuit 10 is used to:

[0066] like Figure 6 As shown, the first transmission gate S1, the third transmission gate S3 and the fourth transmission gate S4 are all turned off, and the third transmission gate S3 is turned on, and the Miller voltage v of the power tube is stored through the voltage stabilizing capacitor CH. out .

[0067] In the holding stage, the first transmission gate S1, the third transmission gate S3 and the fourth transmission gate S4 are all turned off, and the third transmission gate S3 is turned on, which can ensure that the output voltage of the amplifier A will not affect the output of the current sampling circuit (i.e., the voltage across the voltage-stabilizing capacitor CH) during the next sampling, avoiding interference with the sampled Miller voltage, and providing a highly reliable Miller voltage v for the judgment and comparison of the gate voltage during the switching process of the power tube and the segmented control acquisition. out .

[0068] An embodiment of the present application also provides a driving circuit, including the above-mentioned Miller voltage sampling circuit.

[0069] Optionally, the driving circuit may further include a comparator, and the Miller voltage sampling circuit may be connected to an input terminal of the comparator.

[0070] Of course, the driving circuit may also be other parts, which is not limited in the embodiments of the present application.

[0071] An embodiment of the present application also provides an electronic device, comprising the above-mentioned driving circuit.

[0072] Optionally, the electronic device may be a converter, a frequency converter, etc. Of course, the electronic device may also be other devices, which is not limited in the embodiments of the present application.

[0073] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are included in the scope of the claims of the present invention to be approved.

Claims

1. A Miller voltage sampling circuit for a power tube, characterized in that: It includes a voltage dividing unit and a sampling unit; the voltage dividing unit is connected to the gate and source of the power tube, and the voltage dividing unit is also connected to the sampling unit; The voltage dividing unit is used to: obtain the gate-source voltage of the power tube during the switching process, and divide and filter the gate-source voltage; The sampling unit is used to amplify the voltage after voltage division and filtering, and output the Miller voltage of the power tube.

2. The Miller voltage sampling circuit according to claim 1, characterized in that: The first input end of the voltage divider unit is connected to the gate of the power tube, the second input end of the voltage divider unit is connected to the source of the power tube, the output end of the voltage divider unit is connected to the input end of the sampling unit, and the output end of the sampling unit is used to output the Miller voltage of the power tube.

3. The Miller voltage sampling circuit according to claim 2, characterized in that: The voltage dividing unit includes a voltage dividing resistor, a first voltage dividing capacitor and a second voltage dividing capacitor; The first end of the voltage-dividing resistor serves as the first input end of the voltage-dividing unit, and the second end of the second voltage-dividing capacitor serves as the second input end of the voltage-dividing unit; the second end of the voltage-dividing resistor is connected to the first end of the first voltage-dividing capacitor; the second end of the first voltage-dividing capacitor is connected to the first end of the second voltage-dividing capacitor, serving as the output end of the voltage-dividing unit.

4. The Miller voltage sampling circuit according to claim 2, characterized in that: The sampling unit includes a sampling capacitor, a first transmission gate, a second transmission gate and an amplifier; The positive terminal of the sampling capacitor is connected to the first terminal of the second transmission gate as the input terminal of the sampling unit; the negative terminal of the sampling capacitor and the first terminal of the first transmission gate are both connected to the inverting input terminal of the amplifier, and the second terminal of the first transmission gate and the non-inverting input terminal of the amplifier are both connected to the ground terminal; the second terminal of the second transmission gate is connected to the output terminal of the amplifier as the output terminal of the sampling unit.

5. The Miller voltage sampling circuit according to claim 4, characterized in that: The sampling unit also includes a third transmission gate, a fourth transmission gate and a voltage stabilizing capacitor; The first end of the third transmission gate serves as the input end of the sampling unit, the second end of the third transmission gate is connected to the positive end of the sampling capacitor, and the second end of the third transmission gate is connected to the first end of the second transmission gate; the first end of the fourth transmission gate is connected to the output end of the amplifier; the second end of the fourth transmission gate is connected to the positive end of the voltage stabilizing capacitor as the output end of the sampling unit; the negative end of the voltage stabilizing capacitor is connected to the ground end.

6. The Miller voltage sampling circuit according to claim 5, characterized in that: The working phases of the Miller voltage sampling circuit include a sampling phase, an amplification phase and a holding phase.

7. The Miller voltage sampling circuit according to claim 6, characterized in that: In the sampling phase, the Miller voltage sampling circuit is used to: The first transmission gate and the third transmission gate are controlled to be turned on, and the second transmission gate and the fourth transmission gate are controlled to be turned off, so as to charge the sampling capacitor.

8. The Miller voltage sampling circuit according to claim 6, characterized in that: In the amplification stage, the Miller voltage sampling circuit is used to: The first transmission gate and the third transmission gate are controlled to be turned off, and the second transmission gate and the fourth transmission gate are controlled to be turned on, and the voltage after voltage division and filtering is amplified by the amplifier to output the Miller voltage of the power tube.

9. The Miller voltage sampling circuit according to claim 6, characterized in that: In the holding phase, the Miller voltage sampling circuit is used to: The first transmission gate, the third transmission gate and the fourth transmission gate are all controlled to be turned off, and the third transmission gate is controlled to be turned on, so that the Miller voltage of the power tube is stored through the voltage stabilizing capacitor.

10. The Miller voltage sampling circuit according to claim 5, characterized in that: The first transmission gate, the second transmission gate, the third transmission gate and the fourth transmission gate are all CMOS transmission gates; The CMOS transmission gate includes a P-type field effect transistor and an N-type field effect transistor connected in parallel.

11. A driving circuit, characterized in that: The method comprises the Miller voltage sampling circuit as claimed in any one of claims 1 to 10.

12. An electronic device, characterized in that: Comprising the driving circuit as claimed in claim 11.

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