CN-121978492-A - Circuit structure for multiplexing Casode diode to realize IGBT freewheel and on-state voltage drop extraction

CN121978492ACN 121978492 ACN121978492 ACN 121978492ACN-121978492-A

Abstract

The invention discloses a circuit structure for multiplexing a Cascade diode to realize extraction of follow current and on-state voltage drop of an IGBT, which belongs to the technical field of power semiconductor devices and comprises a common-gate common-source diode structure connected in parallel between a collector and an emitter of the IGBT to be tested and a low-voltage clamping circuit connected in parallel at two ends of a low-voltage silicon Schottky barrier diode in the structure, wherein the common-gate common-source diode structure is formed by connecting a high-voltage normally-on silicon carbide junction field effect transistor and a common-gate common-source of the low-voltage silicon Schottky barrier diode, the low-voltage clamping circuit is formed by a resistor and two voltage stabilizing diodes connected in reverse series, the high-voltage blocking function is automatically born when the IGBT is turned off, a follow current path is automatically formed when the IGBT is turned on, signals corresponding to the on-state voltage drop of the IGBT are synchronously output from the low-voltage clamping circuit, and the function of the follow current diode and the on-state voltage measuring circuit is realized. The invention simplifies the circuit structure, reduces the cost and the loss, and meets the high-speed and high-precision measurement requirements on the on-state voltage drop of the IGBT.

Inventors

ZHAO CHENG
XIANG YANKUN
CAI JIAYI
ZHANG HUAIQING
LU WEIGUO
AN HENG

Assignees

重庆大学

Dates

Publication Date: 20260505
Application Date: 20260116

Claims (10)

1. A circuit structure for multiplexing a Cascode diode to realize IGBT freewheel and on-state voltage drop extraction is characterized by comprising a common-gate common-source diode structure and a low-voltage clamping circuit; the common-gate and common-source diode structure is connected in parallel between the collector and the emitter of the IGBT to be tested; The low-voltage clamping circuit is connected in parallel with two ends of a low-voltage silicon Schottky barrier diode in the common-gate and common-source diode structure and is used for realizing voltage clamping and on-state voltage drop signal extraction; The low-voltage clamping circuit is configured to output signal voltage corresponding to the on-state voltage drop of the IGBT to be tested when the IGBT to be tested is conducted, so that multiplexing of a follow current function and an on-state voltage extraction function is achieved.
2. The circuit structure for realizing extraction of IGBT freewheel and on-state voltage drop by multiplexing a Casode diode according to claim 1 is characterized in that the common-gate common-source diode structure comprises a high-voltage normally-on junction field effect transistor and a low-voltage silicon Schottky barrier diode, a grid electrode and a source electrode of the high-voltage normally-on junction field effect transistor are commonly connected and are connected with an anode of the low-voltage silicon Schottky barrier diode, and a drain electrode of the high-voltage normally-on junction field effect transistor and a cathode of the low-voltage silicon Schottky barrier diode are respectively used as two ends of the common-gate common-source diode structure.
3. The circuit structure for multiplexing a Cascode diode according to claim 2, wherein said high voltage normally-on junction field effect transistor is a silicon carbide junction field effect transistor.
4. The circuit structure for multiplexing a Cascode diode according to claim 2, wherein said low voltage schottky barrier diode is a silicon schottky barrier diode.
5. The circuit structure for realizing the extraction of the follow current and the on-state voltage drop of the IGBT by multiplexing the Casoded diode according to claim 1, wherein the low-voltage clamping circuit comprises a resistor and two voltage stabilizing diodes, wherein after the two voltage stabilizing diodes are reversely connected in series, the two voltage stabilizing diodes are connected with the resistor in series to form a series branch, and the series branch is connected with two ends of the low-voltage Schottky barrier diode in parallel.
6. The circuit structure for multiplexing a Cascode diode according to claim 5, wherein said two zener diodes have different voltage stabilizing values.
7. The circuit structure for implementing IGBT freewheeling and on-state voltage drop extraction by multiplexing a Cascode diode according to claim 5, wherein a common connection point of the resistor and two zener diodes is used as an output terminal of the on-state voltage drop signal.
8. The circuit structure for multiplexing a Cascode diode to achieve IGBT freewheeling and on-state voltage drop extraction according to claim 1, wherein the operating modes of the circuit structure include a freewheeling diode operating mode and an on-state voltage measurement circuit operating mode, and mode switching is automatically completed based on an on-off state of the IGBT.
9. The circuit structure for realizing IGBT freewheeling and on-state voltage drop extraction by the multiplexed Cascode diode according to claim 8, wherein the forward voltage of the Cascode diode structure in freewheel mode is lower than that of a silicon carbide schottky diode of the same nominal parameter, and no reverse recovery current.
10. The circuit structure for multiplexing a Cascode diode to achieve IGBT freewheeling and on-state voltage drop extraction according to any one of claims 1 to 9, wherein when the IGBT is turned off, a silicon carbide junction field effect transistor in the Cascode diode structure is turned off, a low voltage silicon schottky barrier diode is reverse biased, and a zener diode in the low voltage clamp circuit maintains a clamp state, sharing high voltage between the IGBT collector and emitter.

Description

Circuit structure for multiplexing Casode diode to realize IGBT freewheel and on-state voltage drop extraction Technical Field The invention belongs to the technical field of power semiconductor devices, and particularly relates to a circuit structure for multiplexing a Casode diode to realize extraction of IGBT freewheel and on-state voltage drop. Background As a main stream of a novel power semiconductor device, a silicon (Si) insulated gate bipolar transistor (InsulatedGateBipolarTransistor, IGBT) has wide application in the power electronics fields such as electric automobiles, motor variable frequency speed regulation, distributed photovoltaic inverters and the like due to the advantages of reduced saturation voltage, small power loss, high input impedance and the like. However, the IGBT itself lacks reverse conduction capability, and a Free-WheelingDiod, FWD is needed to be connected in anti-parallel between the collector and the emitter so as to ensure the normal operation of the circuit under the working conditions of inductive load and the like. Meanwhile, the On-state voltage drop (V on_ds) of the IGBT is a key index for reflecting the ageing degree of the device, and in order to prevent sudden faults caused by ageing, the On-state voltage measuring circuit (On-StateVoltageMeasurementCircuit, OVMC) is required to extract the parameters in real time. To extract V on_ds, the conventional scheme generally requires an additional set of independent OVMC outside the IGBT main power loop. However, this conventional discrete design approach has the following significant drawbacks: First, in terms of structure, FWDs and OVMC generally exist as independent modules, resulting in complicated circuit topology, a large number of components, and a large layout occupation space, which is disadvantageous for miniaturization and integration of the system. In addition, in terms of cost and performance, the independent OVMC often needs an additional precise sampling resistor, an isolation operational amplifier or a special measuring chip, so that the system cost and power consumption are increased, and meanwhile, in order to ensure the measurement safety, the OVMC needs to bear the same high-voltage isolation requirement as that of a main loop, so that the cost and design difficulty are further increased. Finally, in performance matching, it is difficult for discrete designs to optimize freewheel performance and measurement performance simultaneously. For example, fast recovery diodes, which are chosen for fast freewheeling, may have characteristics that conflict with the need for high-precision voltage measurement, while parasitic parameters introduced by the measurement circuit may affect the switching speed of the main loop. Therefore, the traditional discrete scheme can not meet the comprehensive requirements of high-speed (quick response) and high-precision (small error) measurement on V on_ds on the premise of simplifying the circuit structure and reducing the overall cost and loss. The present invention has been made to overcome the above-mentioned drawbacks of the prior art. Disclosure of Invention Aiming at the defects in the prior art, the invention provides a circuit structure for multiplexing the Cascade diode to realize the extraction of the follow current and on-state voltage drop of the IGBT, and simultaneously realizes the functions of the follow current diode and the on-state voltage measurement circuit in the running process of the IGBT, which is used for solving the technical problems of complex circuit structure, high number of high-voltage devices, high system cost and loss, complex driving and controlling and difficult consideration of high-speed and high-precision measurement requirements caused by the discrete design of the follow current diode and the on-state voltage measurement circuit in the traditional scheme, and can well meet the measurement requirements of high-speed, high-precision and low-cost of V on_ds while simplifying the circuit structure. The invention adopts the following technical scheme: A circuit structure for multiplexing a Cascode diode to realize IGBT freewheel and on-state voltage drop extraction comprises a common-gate common-source diode structure and a low-voltage clamping circuit; the common-gate and common-source diode structure is connected in parallel between the collector and the emitter of the IGBT to be tested; The low-voltage clamping circuit is connected in parallel with two ends of a low-voltage silicon Schottky barrier diode in the common-gate and common-source diode structure and is used for realizing voltage clamping and on-state voltage drop signal extraction; The low-voltage clamping circuit is configured to output signal voltage corresponding to the on-state voltage drop of the IGBT to be tested when the IGBT to be tested is conducted, so that multiplexing of a follow current function and an on-state voltage extraction function is achieved. Preferably