阅读说明：本技术 一种电力电子器件瞬态过程时间信息检测装置 (Transient process time information detection device for power electronic device ) 是由 张曦春 徐霄宇 于 2021-07-30 设计创作，主要内容包括：本发明公开了一种电力电子器件瞬态过程时间信息检测装置,涉及电力电子器件监测技术领域,包括：RC等效电路,并联在电力电子器件形成的等效电压源上；所述RC等效电路为电阻电容网络；所述电阻电容网络至少包括一个电阻和一个电容；数字隔离组件,连接在所述电阻电容网络上或者连接在所述电阻电容网络的一个分支电路上,用于：在所述电力电子器件的关断瞬态过程中,提取电容充电时的脉冲电流信号的时间点信息；和/或,在所述电力电子器件的开通瞬态过程中,提取电容放电时的脉冲电流信号的时间点信息其中,所述时间点信息包括起始点时刻和/或结束点时刻。本发明能够达到成本低、精度高、抗干扰能力强的目的。(The invention discloses a device for detecting transient process time information of a power electronic device, which relates to the technical field of power electronic device monitoring and comprises the following components: the RC equivalent circuit is connected in parallel to an equivalent voltage source formed by the power electronic device; the RC equivalent circuit is a resistance-capacitance network; the resistance-capacitance network at least comprises a resistor and a capacitor; a digital isolation component connected to the RC network or to a branch circuit of the RC network, for: extracting time point information of a pulse current signal when a capacitor is charged in a turn-off transient process of the power electronic device; and/or extracting time point information of a pulse current signal when the capacitor discharges in the switching transient process of the power electronic device, wherein the time point information comprises a starting point time and/or an end point time. The invention can achieve the purposes of low cost, high precision and strong anti-interference capability.)

1. A power electronic device transient process time information detection device is characterized by comprising:

the RC equivalent circuit is connected in parallel to an equivalent voltage source formed by the power electronic device; the RC equivalent circuit is a resistance-capacitance network; the resistance-capacitance network at least comprises a resistor and a capacitor;

a digital isolation component connected to the RC network or to a branch circuit of the RC network, for:

extracting time point information of a pulse current signal when a capacitor is charged in a turn-off transient process of the power electronic device;

and/or extracting time point information of a pulse current signal when the capacitor discharges in the switching transient process of the power electronic device;

the time point information comprises a starting point time and/or an end point time.

2. The apparatus of claim 1, further comprising: a time measurement module;

the time measuring module is connected with the output end of the digital isolation component and used for:

determining voltage rise time information of the power electronic device in a turn-off transient process based on time point information of the pulse current signal;

and/or determining voltage drop time information of the power electronic device in the process of switching on transient based on the time point information of the pulse current signal.

3. A power electronic device transient process time information detecting device according to claim 1, wherein when said resistor-capacitor network comprises a resistor and a capacitor, said digital isolation component is connected in series with a circuit formed by connecting said resistor and said capacitor in series;

when the resistance-capacitance network comprises a resistor and a plurality of capacitors, the digital isolation component is connected in series with a circuit formed by connecting the resistor and the capacitors in series;

when the resistance-capacitance network comprises a plurality of resistors and a capacitor, the digital isolation component is connected in series with a circuit formed by connecting a plurality of resistors and a plurality of capacitors in series;

when the resistance-capacitance network comprises a plurality of resistors and a plurality of capacitors, the digital isolation component is connected in series on a circuit formed by connecting the plurality of resistors and the plurality of capacitors in series;

when the resistance-capacitance network comprises a plurality of resistors and a plurality of capacitors, the digital isolation component is connected in series with a circuit formed by connecting the equivalent resistors and the equivalent capacitors in series; the equivalent resistor is formed by connecting a plurality of resistors in parallel; the equivalent capacitor is formed by connecting a plurality of capacitors in parallel;

when the resistance-capacitance network comprises a plurality of resistors and a plurality of capacitors and the resistance-capacitance network comprises N branch circuits, the first N-1 branch circuits are all circuits formed by connecting the plurality of resistors in series, the first N-1 branch circuits are all connected in parallel to an equivalent voltage source formed by a power electronic device, the Nth branch circuit is a circuit formed by connecting the resistors and the capacitors in series, the Nth branch circuit is connected in parallel to one or more resistors of the N-1 branch circuit, and the digital isolation component is connected in series to the Nth branch circuit; the number of the resistors in the Nth branch circuit is one or more, and the number of the capacitors in the Nth branch circuit is one or more;

when the resistance-capacitance network comprises a plurality of resistors and a plurality of capacitors and the resistance-capacitance network comprises N branch circuits, the first N-1 branch circuits are all circuits formed by connecting the resistors and the capacitors in series, the first N-1 branch circuits are all connected in parallel to an equivalent voltage source formed by a power electronic device, the Nth branch circuit is a circuit formed by connecting one or more resistors in series, the Nth branch circuit is connected in parallel to one or more resistors of the N-1 branch circuit, and the digital isolation component is connected in series to the Nth branch circuit; the number of the resistors of each branch circuit in the first N-1 branch circuits is one or more, and the number of the capacitors of each branch circuit in the first N-1 branch circuits is one or more;

wherein N is a positive integer greater than or equal to 2.

4. The apparatus of claim 1, wherein the input signal of the digital isolation module is continuously variable, and the output signal of the digital isolation module is low level or high level; the input end and the output end of the digital isolation component are electrically isolated;

when the input signal of the digital isolation component is smaller than a first threshold value, the output signal of the digital isolation component is a high level signal, and when the input signal of the digital isolation component is larger than a second threshold value, the output signal of the digital isolation component is a low level signal, and when the input signal of the digital isolation component is reduced from a value higher than the second threshold value to a value lower than the first threshold value, the output signal of the digital isolation component is a high level signal; wherein the first threshold is less than or equal to the second threshold;

when the input signal of the digital isolation assembly is smaller than the first threshold value, the output signal of the digital isolation assembly is a low level signal, and when the input signal of the digital isolation assembly is larger than the second threshold value, the output signal of the digital isolation assembly is a high level signal, and when the input signal of the digital isolation assembly is reduced from a value higher than the second threshold value to a value lower than the first threshold value, the output signal of the digital isolation assembly is a low level signal.

5. The apparatus of claim 1, wherein the digital isolation module comprises an optical isolation module and a hysteresis comparison module; wherein, emitting diode among the optical isolation module does the input side of digital isolation subassembly, the photosensitive element among the optical isolation module is the input of hysteresis comparison module, the output of hysteresis comparison module is the output side of digital isolation subassembly.

6. The apparatus of claim 1, further comprising: a clamping device;

the digital isolation assembly is connected with the RC equivalent circuit through the clamping device.

7. A power electronic device transient process time information detection device is characterized by comprising:

the first sampling branch circuit is connected in parallel to an equivalent voltage source formed by the power electronic device; the first sampling branch circuit is an RC equivalent circuit; the RC equivalent circuit is a resistor-capacitor network, and the resistor-capacitor network at least comprises a resistor and a capacitor;

the second sampling branch circuit is connected in parallel to an equivalent voltage source formed by the power electronic device; the second sampling branch circuit is a resistance voltage division equivalent circuit or an RC equivalent circuit; the resistance voltage-dividing equivalent circuit is a resistance network; the resistor network comprises at least two resistors;

a digital isolation component; the first input end of the digital isolation component is connected to the first sampling branch, the second input end of the digital isolation component is connected to the second sampling branch, and the digital isolation component is used for extracting time point information corresponding to an absolute value of current in the transient switching-off and/or switching-on process of the power electronic device; the current absolute value is the absolute value of the difference value of the current determined by the first sampling branch and the current determined by the second sampling branch; the current determined by the first sampling branch circuit is a pulse current signal when a capacitor flowing through an RC equivalent circuit is charged or discharged; the current determined by the second sampling branch circuit is determined according to a voltage signal output by the resistance voltage division equivalent circuit or the RC equivalent circuit; the time point information comprises a starting point time and/or an ending time;

a time measurement module connected to an output of the digital isolation assembly for:

determining voltage rising time information of the power electronic device in a turn-off transient process based on time point information corresponding to the absolute value of the current;

and/or determining voltage drop time information of the power electronic device in the switching-on transient process based on the time point information corresponding to the absolute value of the current.

8. The apparatus of claim 7, wherein when the second sampling branch is an RC equivalent circuit, the time constant of the first sampling branch is different from the time constant of the second sampling branch.

9. A power electronic device transient process time information detection device is characterized by comprising:

the first RC equivalent circuit is connected in parallel to an equivalent voltage source formed by the power electronic device;

the second RC equivalent circuit is connected in parallel to an equivalent voltage source formed by the power electronic device; the first RC equivalent circuit and the second RC equivalent circuit are both resistance-capacitance networks; the resistance-capacitance network at least comprises a resistor and a capacitor;

the first digital isolation component is connected in parallel to the first RC equivalent circuit; the first digital isolation component is used for extracting a signal at the end moment of a pulse current signal generated by the first RC equivalent circuit in the transient process of switching off and/or switching on the power electronic device;

the second digital isolation component is connected in parallel to the second RC equivalent circuit; the second digital isolation component is used for extracting a starting moment signal of a pulse current signal generated by the second RC equivalent circuit in the switching-off and/or switching-on transient process of the power electronic device;

a time measurement module connected to the output of the first digital isolation component and the output of the second digital isolation component for: and determining voltage rising time information of the power electronic device in the turn-off transient process and/or voltage falling time information of the power electronic device in the turn-on transient process based on the starting time signal and the ending time signal.

10. A power electronic device transient process time information detection device is characterized by comprising:

the resistance voltage-dividing equivalent circuit is connected in parallel to an equivalent voltage source formed by the power electronic device; the resistance voltage-dividing equivalent circuit is a resistance network; the resistor network comprises at least two resistors;

the RC equivalent circuit is connected in parallel to an equivalent voltage source formed by the power electronic device; the RC equivalent circuits are all resistance-capacitance networks; the resistance-capacitance network at least comprises a resistor and a capacitor;

the first digital isolation component is connected in parallel to the RC equivalent circuit; the first digital isolation component is used for extracting a signal at the end moment of a pulse current signal generated by the RC equivalent circuit in the transient process of switching off and/or switching on the power electronic device;

the second digital isolation component is connected in parallel to the resistance voltage-dividing equivalent circuit; the second digital isolation component is used for extracting a starting moment signal of a current signal determined by the resistance voltage-dividing equivalent circuit in the transient switching-off and/or switching-on process of the power electronic device;

the time measuring module is connected with the output ends of the first digital isolation component and the second digital isolation component and is used for: and determining voltage rising time information of the power electronic device in the turn-off transient process and/or voltage falling time information of the power electronic device in the turn-on transient process based on the starting time signal and the ending time signal.

Technical Field

The invention relates to the technical field of power electronic device monitoring, in particular to a device for detecting transient process time information of a power electronic device.

Background

The state of health of the power electronics device is closely related to the turn-off transient or the turn-on transient of the power electronics device. The voltage rise time of the power electronics during the turn-off transient (from the start time to the end time) or the voltage fall time of the power electronics during the turn-on transient (from the start time to the end time) can now be used as a switching characteristic variable to characterize the aging state of the power electronics during operation.

Since the voltage rise time of the power electronic device during the turn-off transient or the voltage fall time during the turn-on transient is very short, the requirement on the detection accuracy is very high. At present, a high-precision high-voltage probe is adopted to detect the voltage rise time of a power electronic device in the turn-off transient process or the voltage fall time of the power electronic device in the turn-on transient process. However, this detection method is expensive and has poor safety, and cannot be applied to an actually operated device.

Disclosure of Invention

The invention aims to provide a device for detecting the transient process time information of a power electronic device, so as to achieve the purposes of low cost, high precision and strong anti-interference capability.

In order to achieve the purpose, the invention provides the following scheme:

a power electronic device transient process time information detection apparatus, comprising:

the RC equivalent circuit is connected in parallel to an equivalent voltage source formed by the power electronic device; the RC equivalent circuit is a resistance-capacitance network; the resistance-capacitance network at least comprises a resistor and a capacitor;

a digital isolation component connected to the RC network or to a branch circuit of the RC network, for: extracting time point information of a pulse current signal when a capacitor is charged in a turn-off transient process of the power electronic device; and/or extracting time point information of a pulse current signal when the capacitor discharges in the switching transient process of the power electronic device; the time point information comprises a starting point time and/or an end point time.

A power electronic device transient process time information detection apparatus, comprising:

the first sampling branch circuit is connected in parallel to an equivalent voltage source formed by the power electronic device; the first sampling branch circuit is an RC equivalent circuit; the RC equivalent circuit is a resistor-capacitor network, and the resistor-capacitor network at least comprises a resistor and a capacitor; the second sampling branch circuit is connected in parallel to an equivalent voltage source formed by the power electronic device; the second sampling branch circuit is a resistance voltage division equivalent circuit or an RC equivalent circuit; the resistance voltage-dividing equivalent circuit is a resistance network; the resistor network comprises at least two resistors;

a digital isolation component; the first input end of the digital isolation component is connected to the first sampling branch, the second input end of the digital isolation component is connected to the second sampling branch, and the digital isolation component is used for extracting time point information corresponding to an absolute value of current in the transient switching-off and/or switching-on process of the power electronic device; the current absolute value is the absolute value of the difference value of the current determined by the first sampling branch and the current determined by the second sampling branch; the current determined by the first sampling branch circuit is a pulse current signal when a capacitor flowing through an RC equivalent circuit is charged or discharged; the current determined by the second sampling branch circuit is determined according to a voltage signal output by the resistance voltage division equivalent circuit or the RC equivalent circuit; the time point information comprises a starting point time and/or an ending time;

a time measurement module connected to an output of the digital isolation assembly for: determining voltage rising time information of the power electronic device in a turn-off transient process based on time point information corresponding to the absolute value of the current; and/or determining voltage drop time information of the power electronic device in the switching-on transient process based on the time point information corresponding to the absolute value of the current.

A power electronic device transient process time information detection apparatus, comprising:

the first RC equivalent circuit is connected in parallel to an equivalent voltage source formed by the power electronic device; the second RC equivalent circuit is connected in parallel to an equivalent voltage source formed by the power electronic device; the first RC equivalent circuit and the second RC equivalent circuit are both resistance-capacitance networks; the resistance-capacitance network at least comprises a resistor and a capacitor;

the first digital isolation component is connected in parallel to the first RC equivalent circuit; the first digital isolation component is used for extracting a signal at the end moment of a pulse current signal generated by the first RC equivalent circuit in the transient process of switching off and/or switching on the power electronic device; the second digital isolation component is connected in parallel to the second RC equivalent circuit; the second digital isolation component is used for extracting a starting moment signal of a pulse current signal generated by the second RC equivalent circuit in the switching-off and/or switching-on transient process of the power electronic device;

a time measurement module connected to the output of the first digital isolation component and the output of the second digital isolation component for: and determining voltage rising time information of the power electronic device in the turn-off transient process and/or voltage falling time information of the power electronic device in the turn-on transient process based on the starting time signal and the ending time signal.

A power electronic device transient process time information detection apparatus, comprising:

the resistance voltage-dividing equivalent circuit is connected in parallel to an equivalent voltage source formed by the power electronic device; the resistance voltage-dividing equivalent circuit is a resistance network; the resistor network comprises at least two resistors; the RC equivalent circuit is connected in parallel to an equivalent voltage source formed by the power electronic device; the RC equivalent circuits are all resistance-capacitance networks; the resistance-capacitance network at least comprises a resistor and a capacitor;

the first digital isolation component is connected in parallel to the RC equivalent circuit; the first digital isolation component is used for extracting a signal at the end moment of a pulse current signal generated by the RC equivalent circuit in the transient process of switching off and/or switching on the power electronic device; the second digital isolation component is connected in parallel to the resistance voltage-dividing equivalent circuit; the second digital isolation component is used for extracting a starting moment signal of a current signal determined by the resistance voltage-dividing equivalent circuit in the transient switching-off and/or switching-on process of the power electronic device;

the time measuring module is connected with the output ends of the first digital isolation component and the second digital isolation component and is used for: and determining voltage rising time information of the power electronic device in the turn-off transient process and/or voltage falling time information of the power electronic device in the turn-on transient process based on the starting time signal and the ending time signal.

According to the specific embodiment provided by the invention, the invention discloses the following technical effects:

in the embodiment, an RC equivalent circuit is used as a sampling circuit, and a capacitance charging current waveform obtained by sampling is used for detecting the key moment of a voltage rising stage of a power electronic device in a turn-off transient process or a capacitance discharging current waveform obtained by sampling is used for detecting the key moment of a voltage falling stage of the power electronic device in a turn-on transient process; the method has the advantages of low cost, high precision and strong anti-interference capability.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.

Fig. 1 is a block diagram of a power electronic device transient process time information detection apparatus according to an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a time measurement module according to an embodiment of the present invention;

FIG. 3 is an electrical schematic diagram of an IGBT device according to an embodiment of the invention;

FIG. 4 is a schematic diagram of an equivalent transient voltage source connected to an RC equivalent circuit according to an embodiment of the present invention;

fig. 5 is a schematic waveform diagram of the capacitor voltage and the capacitor current in the turn-off transient process of an IGBT device according to an embodiment of the present invention;

fig. 6 is a schematic waveform diagram of the capacitor voltage and the capacitor current in the turn-on transient process of an IGBT device according to an embodiment of the present invention;

FIG. 7 is a schematic diagram illustrating a connection principle of an equivalent transient voltage source, an RC equivalent circuit and an isolation device according to an embodiment of the present invention;

FIG. 8 is a schematic diagram of the connection principle of an equivalent transient voltage source, an RC equivalent circuit and an isolation device according to an embodiment of the present invention;

FIG. 9 is a schematic diagram of the connection principle of an equivalent transient voltage source, an RC equivalent circuit and an isolation device according to an embodiment of the present invention;

FIG. 10 is a schematic diagram of the connection principle of an equivalent transient voltage source, an RC equivalent circuit and an isolation device according to an embodiment of the present invention;

FIG. 11 is a schematic diagram of input signals of a digital isolation device according to an embodiment of the present invention;

FIG. 12 is a schematic diagram of output signals of a digital isolation device according to an embodiment of the present invention;

fig. 13 is a schematic diagram of the rise time of the voltage of the turn-off device at two ends of the IGBT device CE according to the embodiment of the present invention;

FIG. 14 is a schematic diagram of input signals of a digital isolation assembly connected to an IGBT device according to an embodiment of the present invention;

FIG. 15 is a schematic diagram of the output signals of a digital isolation assembly connected to an IGBT device according to an embodiment of the present invention;

FIG. 16 is a schematic structural diagram of a digital isolation device according to an embodiment of the present invention;

fig. 17 is a schematic view of a part of a structure of a transient process time information detection apparatus of a power electronic device according to a second embodiment of the present invention;

fig. 18 is a schematic diagram of the rise time of the voltage of the turn-off device at two ends of the second IGBT device CE according to the second embodiment of the present invention;

FIG. 19 is a schematic diagram of input signals of a digital isolation assembly connected to an IGBT device according to a second embodiment of the present invention;

fig. 20 is a schematic diagram of output signals of a digital isolation assembly connected to an IGBT device according to a second embodiment of the present invention;

fig. 21 is a schematic structural diagram of a time information detection apparatus for transient process of three power electronic devices according to an embodiment of the present invention;

fig. 22 is a schematic diagram of the rise time of the voltage of the turn-off device at two ends of the three IGBT device CE according to the embodiment of the present invention;

fig. 23 is a schematic diagram of a first input signal of a digital isolation assembly connected to an IGBT device according to a third embodiment of the present invention;

fig. 24 is a schematic diagram of a second input signal of the digital isolation assembly connected to the IGBT device according to the third embodiment of the present invention;

FIG. 25 is a schematic diagram of output signals of a digital isolation assembly connected to an IGBT device according to a third embodiment of the present invention;

fig. 26 is a schematic structural diagram of a transient process time information detection apparatus for four power electronic devices according to an embodiment of the present invention;

fig. 27 is a schematic diagram of the rise time of the voltage of the turn-off device at two ends of the four IGBT device CE according to the embodiment of the present invention;

fig. 28 is a schematic diagram of a first input signal of a digital isolation assembly connected to an IGBT device according to a fourth embodiment of the present invention;

fig. 29 is a schematic diagram of a second input signal of a digital isolation assembly connected to an IGBT device according to a fourth embodiment of the present invention;

fig. 30 is a schematic diagram of output signals of a digital isolation assembly connected to an IGBT device according to the fourth embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.

Example one

The embodiment provides a sampling circuit based on a single-circuit RC series circuit and a digital isolation detection technology, which comprises the steps of firstly obtaining a pulse current signal of capacitance charge/discharge of RC equivalent circuits at two ends of an equivalent transient voltage source formed by a power electronic device in parallel, then detecting a specific time point of the pulse current signal by using a digital isolation component, and further obtaining voltage rising time information of the power electronic device in a turn-off transient process or voltage falling time information of the power electronic device in a turn-on transient process.

Referring to fig. 1, the transient process time information detection apparatus provided in this embodiment includes:

the RC equivalent circuit is connected in parallel to an equivalent voltage source formed by the power electronic device; the RC equivalent circuit is a resistance-capacitance network; the resistor-capacitor network at least comprises a resistor and a capacitor.

A digital isolation component connected to the RC network or to a branch circuit of the RC network, for: extracting time point information of a pulse current signal when a capacitor is charged in a turn-off transient process of the power electronic device; and/or extracting time point information of a pulse current signal when the capacitor discharges in the switching transient process of the power electronic device; the time point information comprises a starting point time and/or an end point time; the digital isolation component is a digital isolation device or a digital isolation module.

Further, referring to fig. 2, the detecting device of the present embodiment further includes: and a time measuring module.

The time measuring module is connected with the output end of the digital isolation component and used for:

determining voltage rise time information of the power electronic device in a turn-off transient process based on time point information of the pulse current signal; and/or determining voltage drop time information of the power electronic device in the process of switching on transient based on the time point information of the pulse current signal.

The time measuring module is composed of a NOT gate and a high-precision time measuring chip TDC-GP 1. The output of the digital isolation component is taken as a START signal of a time measurement chip TDC-GP1 after passing through a first level change edge after not-gating, namely the time when the output of the digital isolation component is turned to zero from a high level, a time measurement chip TDC-GP1 is started and timing is started; the output signal of the digital isolation assembly is directly used as a STOP signal of a time measurement chip TDC-GP1, namely the time measurement chip TDC-GP1 STOPs timing when the output signal of the digital isolation assembly is turned from a low level to a high level, so that the time measurement chip TDC-GP1 measures the output pulse width of the digital isolation assembly, namely the time length of the IGBT turn-off transient process is measured, and the measurement work is completed.

Taking the IGBT device as an example, the voltage rise time information of the power electronic device in the turn-off transient process and the voltage fall time information of the power electronic device in the turn-on transient process will be described.

Fig. 3 is an electrical symbol diagram of the IGBT device, C is a collector of the IGBT device, and E is an emitter of the IGBT device. Both ends of the RC equivalent circuit described in this embodiment are respectively connected to both ends of the CE of the IGBT device, as shown in fig. 4. When the IGBT device is turned off, the voltage at two ends of the CE rises, then the capacitor connected in parallel with the RC equivalent circuit at two ends of the CE is charged, then the digital isolation assembly can extract the time point information of the pulse current signal when the capacitor is charged, and finally the voltage rising time information of the IGBT device in the turn-off transient process is determined based on the time point information of the pulse current signal. When the IGBT device is in a switching-on period, the voltage at two ends of the CE is reduced, the capacitor connected in parallel to the RC equivalent circuit at two ends of the CE discharges, then the digital isolation assembly can extract the time point information of the pulse current signal when the capacitor discharges, and finally the voltage reduction time information of the IGBT device in the switching-on transient process is determined based on the time point information of the pulse current signal.

Fig. 5 is a schematic waveform diagram of the capacitance voltage and the capacitance current of the IGBT device during the turn-off transient, and fig. 6 is a schematic waveform diagram of the capacitance voltage and the capacitance current of the IGBT device during the turn-on transient. Wherein u is_s(t) or u_sAll represent the voltage across CE when u_c(t＝t₁) When it reaches the maximum value u_d；u_c(t) or u_cAll represent the capacitor voltage i_c(t) or i_cBoth represent the capacitive current.

The resistor-capacitor network described in this embodiment may be composed of a plurality of resistors and a plurality of capacitors. Referring to fig. 7-10, the left side (containing capitals R, R2, C) of "Uin" of fig. 1 is an RC equivalent circuit connected in parallel across the equivalent transient voltage source formed by the power electronics. The RC equivalent circuit is a sampling circuit, and can be equivalent to the series connection of a resistor and a capacitor in various topological structures, and then represents the charging current of the capacitor on the RC sampling circuit through the voltage on the resistor; 2) the right side of Uin is a processing part of the output signal of the sampling circuit and consists of a matching resistor r and a digital isolation component; 3) the charging current collected by the sampling circuit and the voltages at two ends of the equivalent transient voltage source formed by the power electronic device have a corresponding relation, in the charging process of the capacitor, the current rising edge time is the voltage rising time at two ends of the equivalent transient voltage source, or the discharging current collected by the sampling circuit and the voltages at two ends of the equivalent transient voltage source formed by the power electronic device have a corresponding relation, and in the discharging process of the capacitor, the current falling edge time is the voltage rising time at two ends of the equivalent transient voltage source. (4) In the RC equivalent circuit, the voltage across the resistor represents the capacitance current (voltage-resistance current), and the maximum value of the capacitance current is proportional to the voltage across the equivalent transient voltage source. Wherein, the output signal (Uin) enters the digital isolation component, and impedance matching is needed to ensure that the input of the digital isolation component is within the specified current range.

Referring to fig. 7 to 10, when the resistor-capacitor network includes a resistor and a capacitor, the digital isolation component is connected in series to a circuit in which the resistor and the capacitor are connected in series. When the resistor-capacitor network comprises a resistor and a plurality of capacitors, the digital isolation component is connected in series with a circuit formed by connecting the resistor and the capacitors in series. When the resistor-capacitor network comprises a plurality of resistors and a capacitor, the digital isolation component is connected in series with a circuit formed by connecting the plurality of resistors and the plurality of capacitors in series. When the resistance-capacitance network comprises a plurality of resistors and a plurality of capacitors, the digital isolation component is connected in series with a circuit formed by connecting the plurality of resistors and the plurality of capacitors in series. When the resistance-capacitance network comprises a plurality of resistors and a plurality of capacitors, the digital isolation component is connected in series with a circuit formed by connecting the equivalent resistors and the equivalent capacitors in series; the equivalent resistor is formed by connecting a plurality of resistors in parallel; the equivalent capacitor is formed by connecting a plurality of capacitors in parallel. When the resistance-capacitance network comprises a plurality of resistors and a plurality of capacitors and the resistance-capacitance network comprises N branch circuits, the first N-1 branch circuits are all circuits formed by connecting the plurality of resistors in series, the first N-1 branch circuits are all connected in parallel to an equivalent voltage source formed by a power electronic device, the Nth branch circuit is a circuit formed by connecting the resistors and the capacitors in series, the Nth branch circuit is connected in parallel to one or more resistors of the N-1 branch circuit, and the digital isolation component is connected in series to the Nth branch circuit; the number of the resistors in the Nth branch circuit is one or more, and the number of the capacitors in the Nth branch circuit is one or more. When the resistance-capacitance network comprises a plurality of resistors and a plurality of capacitors and the resistance-capacitance network comprises N branch circuits, the first N-1 branch circuits are all circuits formed by connecting the resistors and the capacitors in series, the first N-1 branch circuits are all connected in parallel to an equivalent voltage source formed by a power electronic device, the Nth branch circuit is a circuit formed by connecting one or more resistors in series, the Nth branch circuit is connected in parallel to one or more resistors of the N-1 branch circuit, and the digital isolation component is connected in series to the Nth branch circuit; the number of the resistors of each branch circuit in the first N-1 branch circuits is one or more, and the number of the capacitors of each branch circuit in the first N-1 branch circuits is one or more; wherein N is a positive integer greater than or equal to 2.

As a preferred implementation manner, a current waveform collected by the RC equivalent circuit in this embodiment has the same waveform characteristics as a capacitance current or a resistance current on the RC equivalent circuit, and the current waveform includes a rising process and a falling process; for example, the time when the charging current reaches a peak value corresponds to the time when the voltage across the power electronic device reaches a maximum value corresponding to the charging process of the capacitor, and the current waveform signal may also be obtained from a point on the circuit network of the RC equivalent circuit. The current signal representing the RC equivalent circuit is matched by a proper matching resistor r and then input into the input end of a digital isolation component A. The matching resistance r ranges from 0 to 1000 mohm.

Therefore, the apparatus for detecting transient process time information of a power electronic device according to this embodiment further includes: and matching the resistance. The first input end of the digital isolation assembly is connected to the RC equivalent circuit, and the second input end of the digital isolation assembly is connected to the RC equivalent circuit through the matching resistor.

As a preferred embodiment, the timing at which the 1 st changing edge of the switching signal output by the digital isolation component occurs is approximately the timing at which the voltage rise of the power electronic device starts during the turn-off process or the timing at which the voltage drop starts during the turn-on process; the time when the 2 nd change edge of the switching signal output by the digital isolation component occurs may approximately correspond to the time when the voltage rise of the power electronic device ends during the turn-off transient or the time when the voltage drop of the power electronic device ends during the turn-on transient. The time difference of the two time signals can obtain the voltage rising time width in the turn-off transient process or the voltage falling time width in the turn-on transient process of the power electronic device. And finally, accurately calculating the voltage rising time of the turn-off transient process or the voltage falling time of the turn-on transient process of the power electronic device through fitting or calibration.

Therefore, the change process of the output signal of the digital isolation device is performed in the switching-off transient process or the switching-on transient process of the power electronic device in the embodiment. The input signal X of the digital isolation assembly is allowed to vary continuously; the output signals of the digital isolation assembly are two stable levels, namely a low level Y0 and a high level Y1; the input end and the output end of the digital isolation component are electrically isolated.

The first case: when the input signal of the digital isolation assembly is smaller than a first threshold value X0, the output signal of the digital isolation assembly is high level Y1, and when the input signal of the digital isolation assembly is larger than a second threshold value X1, the output signal of the digital isolation assembly is low level Y0; when the input signal of the digital isolation assembly is reduced to be lower than the first threshold value X0 from a value higher than the second threshold value X1, the output signal of the digital isolation assembly is high level Y1. Wherein the first threshold X0 is less than or equal to the second threshold X1. The input-output signal relationship of the digital isolation assembly is shown in fig. 11 and 12.

The second case: when the input signal of the digital isolation assembly is smaller than a first threshold value X0, the output signal of the digital isolation assembly is low level Y0, and when the input signal of the digital isolation assembly is larger than a second threshold value X1, the output signal of the digital isolation assembly is high level Y1; when the input signal of the digital isolation assembly is reduced to be lower than the first threshold value X0 from the value higher than the second threshold value X1, the output signal of the digital isolation assembly is low level Y0.

Referring to fig. 13, the time constant of the RC equivalent circuit connected in parallel to the two ends of the IGBT device CE is denoted as τ, when the IGBT device is turned off, the voltage across the CE increases at dv/dt rate until reaching the cut-off voltage Ud of the IGBT device, and during this turn-off transient, the voltage across the CE increases, and it is known from theoretical analysis that the current flowing through the RC equivalent circuit gradually increases as the voltage across the CE increases, and the signal at the input end of the digital isolation component also gradually increases, and when the signal is higher than the second threshold X1 of the digital isolation component, the output signal of the digital isolation component is at the low level Y0; when the voltage across the CE reaches the highest value, the current of the RC equivalent circuit reaches the maximum value at the same time, then when the voltage across the CE is in the off period with the unchanged voltage, the current in the RC equivalent circuit decreases exponentially from the maximum value with tau as a time constant, the input signal of the digital isolation assembly also decreases, and when the input signal decreases to the first threshold value X0, the output of the digital isolation assembly is inverted to another value, namely, a low level Y1. Through the scheme, the output of the digital isolation assembly obtains a switching signal.

Fig. 14 shows the charging process of the digital isolation device corresponding to the whole capacitor. Referring to fig. 15, the output of the isolation component is composed of two changing edges (e.g., a falling edge and a rising edge), and the time width of the output switching signal is positively correlated to the transient time of the charging current waveform of the RC equivalent circuit and positively correlated to the turn-off time (voltage rising process) of the IGBT device. The moment when the 1 st change edge of the isolating component output switching signal occurs (the falling edge occurrence moment T01 in the figure) is approximate to the moment when the electronic device turn-off process of the force starts; the isolation component outputs the 2 nd changing edge of the switching signal, and the time of occurrence can approximately correspond to the time of the end of the voltage rise in the turn-off transient of the power electronic device (the time T11 of the rising edge in the figure). And measuring the time difference of the two time signals to obtain the voltage rising time width in the turn-off transient process of the power electronic device.

τ is the time constant, τ ═ R × C, and the circuit will have a time constant as long as there is capacitance. The current and voltage on a resistor are synchronous, the current and voltage on a capacitor are asynchronous (phase), and the time constant of the RC equivalent circuit is used for representing the characteristics of the circuit.

Therefore, by properly designing the time constant τ of the resistor-capacitor network, i.e., controlling the rate of change of the input signal of the digital isolation device, such that the time for the signal input to the input terminal of the digital isolation device to fall from the peak value to the first threshold value X0 is less than or equal to the expected error value measured at the end time of the turn-off transient, the error obtained by the above-mentioned scheme can be ensured to be within an acceptable range.

The expected error value means that the scheme has errors necessarily in the detection method, but the errors can be controlled, and the error control is realized by optimizing the time constant tau and the second threshold X0 in design.

As a preferred implementation manner, the digital isolation component of this embodiment may also include, as shown in fig. 16, an optical isolation module and a hysteresis comparison module; wherein, emitting diode among the optical isolation module does the input side of digital isolation subassembly, the photosensitive element among the optical isolation module is the input of hysteresis comparison module, the output of hysteresis comparison module is the output side of digital isolation subassembly.

As a preferable implementation manner, the transient process time information detection apparatus provided in this embodiment further includes: a clamping device; the digital isolation assembly is connected with the RC equivalent circuit through a clamping device.

Example two

The embodiment provides a detection method based on parallel sampling and digital isolation of a double-branch series circuit. Two sampling circuits, namely a sampling branch A and a sampling branch B, are connected in parallel at two ends of the power electronic device (such as two ends of CE of an IGBT). The sampling branch a may be equivalent to a series circuit of R1 and C1 with a time constant τ 1 — R1 — C1, or the sampling branch a may be equivalent to a series circuit of R3 and R4. The sampling branch B may be equivalent to a series circuit of R2 and C2, with a time constant τ 2 — R2 — C2; when the sampling branch A is an RC equivalent circuit, the time constant of the sampling branch A is different from that of the sampling branch B.

Referring to fig. 17, the transient process time information detection apparatus provided in this embodiment includes:

a first sampling branch (sampling branch B in the figure) connected in parallel to an equivalent voltage source formed by the power electronic device; the first sampling branch circuit is an RC equivalent circuit; the RC equivalent circuit is a resistance-capacitance network, and the resistance-capacitance network at least comprises a resistor and a capacitor.

A second sampling branch (a sampling branch a in the figure) connected in parallel to an equivalent voltage source formed by the power electronic device; the second sampling branch circuit is a resistance voltage division equivalent circuit or an RC equivalent circuit; the resistance voltage-dividing equivalent circuit is a resistance network; the resistor network includes at least two resistors.

A digital isolation component; the first input end of the digital isolation component is connected to the first sampling branch, the second input end of the digital isolation component is connected to the second sampling branch, and the digital isolation component is used for extracting time point information corresponding to an absolute value of current in the transient switching-off and/or switching-on process of the power electronic device; the current absolute value is the absolute value of the difference value of the current determined by the first sampling branch and the current determined by the second sampling branch; the current determined by the first sampling branch circuit is a pulse current signal when a capacitor flowing through an RC equivalent circuit is charged or discharged; the current determined by the second sampling branch circuit is determined according to a voltage signal output by the resistance voltage division equivalent circuit or the RC equivalent circuit; the time point information comprises a starting point time and/or an ending time.

A time measurement module connected to an output of the digital isolation assembly for:

determining voltage rising time information of the power electronic device in a turn-off transient process based on time point information corresponding to the absolute value of the current; and/or determining voltage drop time information of the power electronic device in the switching-on transient process based on the time point information corresponding to the absolute value of the current.

Similar to the first embodiment, the output ends of the sampling branches are resistors, and the access resistors r1 and r2 are matched resistors, the first input end of the digital isolation component is connected to the first sampling branch through a matched resistor r1, and the second input end of the digital isolation component is connected to the second sampling branch through a matched resistor r 2.

When the input signal of the digital isolation assembly is smaller than a specified first threshold value X0, the output signal of the digital isolation assembly is high level Y1, when the input signal of the digital isolation assembly is larger than a specified second threshold value X1, the output signal of the digital isolation assembly is low level Y0, and when the input signal of the digital isolation assembly is decreased from a value higher than the second threshold value X1 to a value lower than the first threshold value X0, the output signal of the digital isolation assembly is high voltage Y1. Wherein the first threshold value X0 is less than or equal to the second threshold value X1.

Or, when the input signal of the digital isolation assembly is smaller than a specified first threshold value X0, the output signal of the digital isolation assembly is low Y0, when the input signal of the digital isolation assembly is larger than a specified second threshold value X1, the output signal of the digital isolation assembly is high Y1, and when the input signal of the digital isolation assembly is decreased from a value higher than the second threshold value X1 to a value lower than the first threshold value X0, the output signal of the digital isolation assembly is low Y0.

Taking the IGBT device as an example, please refer to fig. 18-20, where t0 is the starting time of the voltage rising phase of the IGBT device. When the IGBT device is turned off, the voltage at two ends of the CE rises at a dv/dt rate until the voltage reaches a cut-off voltage Ud of the IGBT device, and in the turn-off transient process, when the voltage at two ends of the CE rises and the absolute value of the voltage or the absolute value of the current is always smaller than a second threshold value X1, the output signal of the digital isolation assembly is at a high level Y1; when the voltage at two ends of the CE reaches the peak value, the output voltage UA and the output voltage UB drop in an exponential law, the absolute value of the voltage or the absolute value of the current exceeds a second threshold value X1 within an allowed time error, the output signal of the digital isolation assembly is inverted to a low level Y0, and the change edge of the output of the digital isolation assembly from the high level Y1 to the low level Y0 can be approximate to the signal of the voltage rising ending moment in the turn-off transient process of the IGBT device.

Extracting a voltage signal UA which is in direct proportion to the current in the equivalent circuit from the sampling branch A; the design of the sampling branch B should simultaneously satisfy the following requirements: (1) in the turn-off transient process of the IGBT device, the sampling branch circuit B outputs a voltage signal UB positively correlated with the voltage at two ends of CE of the IGBT, and the UB-UA value is ensured not to exceed a second threshold value X1 at the stage; (2) in the phase when the voltage across the CE of the IGBT device reaches the maximum value and the cut-off voltage Ud is maintained, the voltage signal output by the sampling branch B should be such that UB-UA exceeds the second threshold X1 within the allowed time error.

EXAMPLE III

The embodiment provides a detection method based on parallel sampling and digital isolation of a double-branch RC series circuit. Referring to fig. 21, the transient process time information detection apparatus provided in this embodiment includes:

the first RC equivalent circuit is connected in parallel to an equivalent voltage source formed by the power electronic device;

the second RC equivalent circuit is connected in parallel to an equivalent voltage source formed by the power electronic device; the first RC equivalent circuit and the second RC equivalent circuit are both resistance-capacitance networks; the resistance-capacitance network at least comprises a resistor and a capacitor;

and the first digital isolation component (represented by an isolation device A in the figure) is connected in parallel with the first RC equivalent circuit and is used for extracting a signal at the end moment of a pulse current signal generated by the first RC equivalent circuit in the process of the turn-off and/or turn-on transient of the power electronic device.

And the second digital isolation component (represented by an isolation device B in the figure) is connected in parallel with the second RC equivalent circuit and is used for extracting a starting moment signal of a pulse current signal generated by the second RC equivalent circuit in the switching-off and/or switching-on transient process of the power electronic device.

A time measurement module connected to the output of the first digital isolation component and the output of the second digital isolation component for: and determining voltage rising time information of the power electronic device in the turn-off transient process and/or voltage falling time information of the power electronic device in the turn-on transient process based on the starting time signal and the ending time signal.

The obtained signal which is in equal proportion to the current of R1 or C1 is input to an isolation component A or an isolation device A; when the input signal of the isolation component A is less than the first threshold value X0, the isolation component A outputs a high level Y1, and when the input signal of the isolation component A is higher than the second threshold value X1, the output of the isolation component A is inverted from the high level Y1 to a low level Y0. The obtained signal which is in equal proportion to the current of R2 or C2 is input to an isolation component B or an isolation device B; when the input signal of the isolation element B is less than the first threshold value X0, the isolation element A outputs a high level Y1, and when the input signal of the isolation element B is higher than the second threshold value X1, the output of the isolation element B is inverted from the high level Y1 to a low level Y0.

Or, the obtained signal which is in equal proportion to the current of R1 or C1 is input to the isolation component A or the isolation device A; when the input signal of the isolation component A is less than the first threshold value X0, the isolation component A outputs a low level Y0, and when the input signal of the isolation component A is higher than the second threshold value X1, the output of the isolation component A is inverted from the low level Y0 to a high level Y1. The obtained signal which is in equal proportion to the current of R2 or C2 is input to an isolation component B or an isolation device B; when the input signal of the isolation element B is less than the first threshold value X0, the isolation element A outputs a low level Y0, and when the input signal of the isolation element B is higher than the second threshold value X1, the output of the isolation element B is inverted from the low level Y0 to a high level Y1.

The role of the clamping device or clamping device module is to protect the isolation component when the "isolation component" input signal is too large. Therefore, the isolation component can be protected by arranging a clamping device at the front section of the isolation component to clip the overhigh input signal (greater than the second threshold value X1). Therefore, the apparatus provided in this embodiment further includes: a first clamping device and a second clamping device; the first digital isolation component is connected with the first RC equivalent circuit through the first clamping device; the second digital isolation component is connected to the second RC equivalent circuit through the second clamping device.

The first RC equivalent circuit and the second RC equivalent circuit (two completely symmetrical circuits) are sampling circuits, sampled voltages are converted into a current ic1 of an R1C1 branch circuit and a current ic2 of an R2C2 branch circuit, the peak value (or the valley value) of the two currents is related to the parameters of resistance and capacitance of the branch circuit, and the larger the resistance is, the smaller the peak value of the current is. The resistors and capacitors of the R1C1 branch and the R2C2 branch are designed appropriately so that the time for the current ic1 and the current ic2 to reach the peak value (the first stage of capacitor charging is completed) or the valley value (the first stage of capacitor discharging is completed) are the same.

Referring to fig. 22 to 25, the capacitor charging is divided into two stages, the first stage is to increase according to the CE voltage approximate ramp function, and the capacitor is charged; the second phase is that the CE voltage reaches the maximum value Ud, and the capacitor voltage is smaller than the CE voltage to continue charging. Two branches a and B, the peak value of the current ic1 of the branch a is larger than the peak value of the current ic2 of the branch B. When the CE voltage at two ends of the IGBT device is a saturation voltage drop close to 0 (i.e., before the device is turned off), the current ic1 and the current ic2 are both 0, the signal input to the isolation component is 0 and is both smaller than the first threshold X0 and the second threshold X1, the output of the two isolation components is Y1 (high level), the voltage at two ends of the IGBT device changes (rises), when the current ic2 is larger than the first threshold X0, the output of the isolation component B becomes Y0 (low level), and at this time, the output can be used as the starting time of voltage rise in the turn-off process of the power electronic device, although there is a certain error, by designing an RC parameter, the error can be made very small; as the voltage across the power electronic device CE rises to reach the maximum value Ud, the currents of both branches reach the maximum value (peak value), and at this time, the outputs of the isolation components a and B are both Y0 (low level); next, the voltage across CE is maintained, and the charging current of the two branches decreases from the peak value to 0, thereby completing the second stage of charging. During the second phase, the current ic2 of the selected branch B observes that when the input of the isolation element B is smaller than the second threshold X1 when the current ic2 decreases, the state of the isolation element B changes from Y0 (low level) to Y1 (high level), which can be approximately used as the ending time of the voltage rising process, and also, although there is a certain error, the error can be made small by designing the RC parameter.

By utilizing the characteristics of the isolation assembly, a starting time signal and an ending time signal of the voltage rising process in the transient switching-off process of the power electronic device can be obtained.

Example four

The embodiment provides a parallel sampling circuit based on an RC series circuit and a resistance voltage division circuit and a digital isolation detection method. Referring to fig. 26, the detecting device provided in this embodiment includes:

the resistance voltage-dividing equivalent circuit is connected in parallel to an equivalent voltage source formed by the power electronic device; the resistance voltage-dividing equivalent circuit is a resistance network; the resistor network includes at least two resistors.

The RC equivalent circuit is connected in parallel to an equivalent voltage source formed by the power electronic device; the RC equivalent circuits are all resistance-capacitance networks; the resistor-capacitor network at least comprises a resistor and a capacitor.

And the first digital isolation component (an isolation device A in the figure) is connected in parallel with the RC equivalent circuit and is used for extracting a signal of the ending moment of a pulse current signal generated by the RC equivalent circuit in the switching-off and/or switching-on transient process of the power electronic device.

And the second digital isolation component (an isolation device B in the figure) is connected in parallel with the resistance voltage division equivalent circuit and is used for extracting a starting moment signal of a current signal determined by the resistance voltage division equivalent circuit in the switching-off and/or switching-on transient process of the power electronic device.

The time measuring module is connected with the output ends of the first digital isolation component and the second digital isolation component and is used for: and determining voltage rising time information of the power electronic device in the turn-off transient process and/or voltage falling time information of the power electronic device in the turn-on transient process based on the starting time signal and the ending time signal.

The embodiment outputs the obtained signal which is in equal proportion to the current of R3 or C to an isolation component A or an isolation device A; when the input signal of the isolation component A is less than the first threshold value X0, the isolation component A outputs a high level Y1, and when the input signal of the isolation component A is higher than the second threshold value X1, the output of the isolation component A is inverted from the high level Y1 to a low level Y0. After the equivalent voltage formed by the power electronic device is divided by another pure resistance network (R1, R2), a signal which is in direct proportion to the equivalent voltage is obtained and is output to the isolation component B or the isolation device B; when the input signal of the isolation element B is less than the first threshold value X0, the isolation element A outputs a high level Y1, and when the input signal of the isolation element B is higher than the second threshold value X1, the output of the isolation element B is inverted from the high level Y1 to a low level Y0.

Or, the obtained signal which is in equal proportion to the current of R3 or C1 is input to the isolation component A or the isolation device A; when the input signal of the isolation component A is less than the first threshold value X0, the isolation component A outputs a low level Y0, and when the input signal of the isolation component A is higher than the second threshold value X1, the output of the isolation component A is inverted from the low level Y0 to a high level Y1. After the equivalent voltage formed by the power electronic device is divided by another pure resistance network (R1, R2), a signal which is in direct proportion to the equivalent voltage is obtained and is output to the isolation component B or the isolation device B; when the input signal of the isolation element B is less than the first threshold value X0, the isolation element A outputs a low level Y0, and when the input signal of the isolation element B is higher than the second threshold value X1, the output of the isolation element B is inverted from the low level Y0 to a high level Y1.

The role of the clamping device or module is to protect the isolation component when the "isolation component" incoming signal is too large.

Referring to fig. 27 to fig. 30, both the R1R2 equivalent circuit and the R3C equivalent circuit are sampling circuits, and convert the sampled voltage (CE voltage of the power electronic device, which rises from a saturation voltage drop close to 0 to a cutoff voltage Ud during the turn-off process) into the current iR of the R1R2 branch and the iC of the R3C branch. The branch R1R2 is a pure resistance branch, and the voltages at the two ends of the current iR and the CE are changed to be in the same phase. The branch R3C is a resistor-capacitor branch, and the current is a capacitor charging current iC which has two stages. The first stage is that the CE voltage rises according to an approximate ramp function, the capacitor is charged, and the second stage is that the CE voltage reaches the maximum value Ud and the capacitor voltage is smaller than the CE voltage to continue charging.

When the CE voltage across the power electronic device is a saturation voltage drop close to 0 (i.e., before turn-off), the current iR and the current iC are both 0 and smaller than the first threshold X0 and the second threshold X1, and the outputs of the two isolation components are both Y1 (high level); when the voltage at two ends of the power electronic device changes (rises), and when the current iR of the branch R1R2 is greater than the first threshold value X0, the output of the isolation component B becomes Y0 (low level), which can be used as the starting moment of the voltage rise in the turn-off process of the power electronic device, although there is a certain error, the error can be made very small by the design parameters; as the voltage across the power electronic device CE rises to reach the maximum value Ud, the current of the branch a (R3C) reaches the maximum value (peak value), and the output of the isolation component a is Y0 (low level), and then the voltage across the CE remains unchanged, and the charging current of the branch a becomes smaller from the peak value to 0, thereby completing the charging in the second stage. During the second phase, the current iC of the selected branch a is observed, and when the input of the isolation component a is smaller than the second threshold X1 when the current iC decreases, the state of the isolation component a changes from Y0 (low level) to Y1 (high level), which can be approximately used as the ending time of the voltage rising process, and also, although there is a certain error, the error can be made small by designing the parameters of R3C.

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.

The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.