CN-121770505-B - Self-adaptive soft-turn-off circuit of power switch device

CN121770505BCN 121770505 BCN121770505 BCN 121770505BCN-121770505-B

Abstract

The invention discloses a self-adaptive soft turn-off circuit of a power switch device, which relates to the technical field of electronic circuits and comprises a turn-off control module, a detection module, an energy storage delay module and a soft turn-off execution module, wherein the detection module and the energy storage delay module are connected in series and then are connected between a drain electrode and a source electrode of the power switch device, the detection module, the energy storage delay module and the power switch device form a drain-source electrode loop, when the drain-source electrode voltage in the turn-off process of the power switch device is compared with a preset safety threshold value, the energy storage delay module is controlled to store or discharge, the resistance value of a soft turn-off resistor in a grid electrode connected with the power switch device is dynamically adjusted according to the stored energy or discharge, and the turn-off speed of the power switch device is adjusted. And a control signal is generated through energy storage, the resistance value of a soft turn-off resistor connected into the grid electrode of the power switch device is dynamically adjusted, and the turn-off speed of the power switch device is slowed down, so that voltage spikes are restrained.

Inventors

LUO JIAN
WU YONG
ZENG MAOLIANG
ZHANG JUNQING

Assignees

成都迈硕电气有限公司

Dates

Publication Date: 20260512
Application Date: 20260304

Claims (7)

1. The utility model provides a power switching device's self-adaptation soft shutdown circuit, its characterized in that includes turn-off control module, detection module, energy storage delay module and soft shutdown executive module, connects between power switching device's drain electrode and source after detection module and energy storage delay module establish ties, and detection module, energy storage delay module and power switching device form the drain-source circuit, wherein: the turn-off control module is used for detecting the on state of the power switch device and controlling the soft turn-off mode to be started according to the on state; the detection module is used for detecting the drain-source voltage of the power switch device in the soft-off mode starting process, comparing the drain-source voltage with a preset safety threshold value and controlling the conduction state of a drain-source loop according to the comparison result; The detection module comprises one or more voltage stabilizing diodes connected in series, wherein the cathode of the voltage stabilizing diode is connected to the drain electrode of the power switch device, and the anode of the voltage stabilizing diode is connected to the energy storage delay module; The energy storage delay module is used for storing energy or discharging according to the conduction state of the drain-source circuit and generating a control signal; The energy storage delay module comprises a current-limiting resistor and an energy storage capacitor, wherein one end of the current-limiting resistor is connected with the anode of the voltage-stabilizing diode, and the other end of the current-limiting resistor is connected with the anode of the energy storage capacitor; the control end of the soft turn-off execution module is connected with the energy storage delay module and is used for responding to the control signal, dynamically adjusting the resistance value of the soft turn-off resistor in the grid electrode of the power switch device and adjusting the turn-off speed of the power switch device; the soft turn-off execution module comprises a control switch and a turn-off resistor, wherein a control electrode of the control switch is connected to the positive electrode of the energy storage capacitor, a first power terminal of the control switch is connected with the grid electrode of the power switch device, and a second power terminal of the control switch is connected to the turn-off control module through the turn-off resistor; When the drain-source circuit is conducted, the voltage of the control electrode of the control switch rises, so that the on-resistance of the control switch is increased, the resistance value of a soft off resistor connected to the grid electrode of the power switch device is increased, and when the stored energy storage voltage stored by the energy storage capacitor reaches the closing threshold value of the control switch, the control switch disconnects the closing resistor from the power switch device, and the turn-off speed of the power switch device is reduced; When the drain-source circuit is disconnected, after the energy storage capacitor is discharged, the switch is controlled to be turned on, and the closing resistor is connected to reduce the resistance value of the soft-off resistor in the grid electrode of the power switch device, so that the turn-off speed of the power switch device is increased.
2. The adaptive soft-off circuit of a power switching device of claim 1, wherein the off control module comprises: The desaturation detection circuit is connected between the drain electrode of the power switch device and the driving module and used for detecting the conduction state of the power switch device in real time; the driving module is used for calculating a drain-source changing voltage value transmitted to the driving module according to the on state of the power switch device, comparing the drain-source changing voltage value with a protection threshold value, and controlling the soft-off mode to be started when the drain-source changing voltage value exceeds the protection threshold value set by the driving module.
3. The self-adaptive soft-switching circuit of a power switching device according to claim 2, wherein a high-side gate driving output end of the driving module is connected with one end of a first on resistor, the other end of the first on resistor is connected with a gate of the power switching device, a low-side gate driving output end is respectively connected with one end of a second off resistor and one end of a closing resistor, the other end of the second off resistor is connected with the gate of the power switching device, and the first on resistor is smaller than the second off resistor; When the soft off mode is started, a second off resistor switched to the low-side gate drive output terminal is connected to the gate of the power switch device, and the resistance value Roff of the soft off resistor in the gate of the power switch device is as follows: Roff= (resistance of off-resistance + resistance of on-resistance of control switch)// resistance of second off-resistance, where// represents parallel calculation.
4. The self-adaptive soft-turn-off circuit of a power switch device according to claim 1, wherein a transient voltage suppression diode is connected in parallel to two ends of the energy storage capacitor, one end of a discharging resistor is further connected to the control electrode of the control switch, the other end of the discharging resistor is connected to the source electrode of the power switch device, when the energy storage voltage stored in the energy storage capacitor reaches the turn-off threshold value of the control switch, the control switch disconnects the turn-off resistor from the power switch device, and the resistance value of the soft-turn-off resistor connected to the gate electrode of the power switch device reaches the maximum value.
5. The adaptive soft-off circuit of a power switching device according to claim 2, wherein the desaturation detection circuit comprises a high voltage blocking diode, a blanking capacitor and a voltage dividing resistor network, wherein a cathode of the high voltage blocking diode is connected to a drain of the power switching device, an anode of the high voltage blocking diode is connected to a desaturation pin of the driving module through the voltage dividing resistor network, and the desaturation pin is grounded through the blanking capacitor.
6. The adaptive soft-off circuit of claim 2, wherein the turn-off control module further comprises a gate drive protection circuit comprising two zener diodes, the cathodes of the two zener diodes being connected, wherein the anode of one zener diode is connected to the gate of the power switching device and the anode of the other zener diode is connected to the source of the power switching device.
7. An adaptive soft-off circuit of a power switching device according to claim 1, wherein the preset safety threshold is defined by a breakdown voltage of a zener diode.

Description

Self-adaptive soft-turn-off circuit of power switch device Technical Field The invention relates to the technical field of electronic circuits, in particular to a self-adaptive soft-turn-off circuit of a power switch device. Background In the turn-off process of the power switch device, a turn-off voltage spike can be generated due to the existence of loop parasitic inductance. Too high a voltage spike may break down the device, threatening the reliability of the system. The traditional inhibition method comprises the following steps: the passive absorption circuit (RC) has the advantages that the circuit is simple, but the resistor consumes energy, reduces the system efficiency, has fixed damping effect and cannot be self-adaptive. The active clamp circuit (ACTIVE CLAMP) has the advantage of fast clamping speed, but generally directs energy to the gate or source, which can cause gate overvoltage stress, and parasitic parameters of the circuit itself can affect the switching speed of the main power loop. Increasing the off-resistance has the advantage of being simple, but can fixedly increase the off-loss and can lead to excessive device temperature rise. Therefore, it is necessary to develop a soft turn-off circuit with simple structure and low cost, which can effectively inhibit voltage spike, and improve the reliability of the power switch device in the turn-off process. Disclosure of Invention The invention aims to provide a self-adaptive soft-turn-off circuit of a power switch device, which dynamically adjusts the resistance value of a soft-turn-off resistor connected into the grid electrode of the power switch device by generating a control signal through energy storage and slows down the turn-off speed of the power switch device. In order to achieve the above object, the following solutions are proposed: the invention provides a self-adaptive soft turn-off circuit of a power switch device, which comprises a turn-off control module, a detection module, an energy storage delay module and a soft turn-off execution module, wherein the detection module and the energy storage delay module are connected in series and then are connected between a drain electrode and a source electrode of the power switch device, and the detection module, the energy storage delay module and the power switch device form a drain-source electrode loop, wherein: the turn-off control module is used for detecting the on state of the power switch device and controlling the soft turn-off mode to be started according to the on state; the detection module is used for detecting the drain-source voltage of the power switch device in the soft-off mode starting process, comparing the drain-source voltage with a preset safety threshold value and controlling the conduction state of a drain-source loop according to the comparison result; The energy storage delay module is used for storing energy or discharging according to the conduction state of the drain-source circuit and generating a control signal; And the control end of the soft turn-off execution module is connected with the energy storage delay module and is used for responding to the control signal, dynamically adjusting the resistance value of the soft turn-off resistor in the grid electrode of the power switch device and adjusting the turn-off speed of the power switch device. In some embodiments, the detection module includes one or more zener diodes in series, a cathode of the zener diode being connected to the drain of the power switching device and an anode of the zener diode being connected to the energy storage delay module. In some embodiments, the energy storage delay module comprises a current-limiting resistor and an energy storage capacitor, wherein one end of the current-limiting resistor is connected with an anode of the voltage-stabilizing diode, the other end of the current-limiting resistor is connected with a cathode of the energy storage capacitor, a cathode of the energy storage capacitor is connected to a source electrode of the power switch device, when the drain-source voltage is greater than or equal to a preset safety threshold value, a drain-source circuit is conducted to charge the energy storage capacitor, and when the drain-source voltage is smaller than the preset safety threshold value, the drain-source circuit is disconnected to discharge the energy storage capacitor. In some specific embodiments, the soft shutdown execution module comprises a control switch and a shutdown resistor, wherein the control electrode of the control switch is connected to the positive electrode of the energy storage capacitor, the first power terminal of the control switch is connected with the grid electrode of the power switch device, and the second power terminal of the control switch is connected to the shutdown control module through the shutdown resistor; When the drain-source circuit is conducted, the voltage of the control electrode of the control switch rises, so t