igbt collector voltage discrete measurement circuit

Abstract

The invention provides an IGBT collector voltage discrete measurement circuit. The IGBT collector voltage discrete measurement circuit is characterized in that the IGBT collector voltage discrete measurement circuit includes diodes D1 and D2, a high-input impedance differential amplifier U1, a high-input impedance operational amplifier U2, identical high-precision current-limiting resistors R1 and R2, as well as current sources IS1 and IS2 of the same type; the current source IS1 injects current into the diode D1 and the diode D2 through the resistor R1; the current source IS2 injects current into the diode D2 through the resistor R2; the cathodes of the diode D1 and the diode D2 are connected with the collector and emitter of an IGBT (insulated gate bipolar translator) respectively; the anodes of the diode D1 and the diode D2 are connected with the in-phase end and reverse end of the high-input impedance differential amplifier U1 respectively; the in-phase end of the high-input impedance operational amplifier U2 is connected between a resistor RH and a resistor RL as well as between a capacitor CH and a capacitor CL; the reverse end of the high-input impedance operational amplifier U2 is connected with an output end; and the output end of a gate driver is connected with the base of the IGBT through a resistor RG. With the IGBT collector voltage discrete measurement circuit of the invention adopted, high-bandwidth measurement of the switching transient collector voltage of the IGBT and high-precision measurement of the break-over low voltage of the IGBT can be realized.

Description

technical field [0001] The invention belongs to the field of high-precision measurement of electrical signals, and in particular relates to a measurement circuit integrating IGBT off voltage and on voltage. Background technique [0002] At present, a very important development direction of power electronic converter technology is intelligence, medium and high voltage, large capacity, high power density, high maintainability and high reliability. Among them, high reliability is the most basic and most important performance index that the power electronic converter system needs to achieve. According to industry surveys, nearly one-third of power electronic converter system failures are caused by damage to power electronic power devices, especially device failures caused by overvoltage breakdown. Therefore, online monitoring of power device voltage is very important. important. [0003] IGBT is currently the most widely used medium-to-high-power, fully-controlled power electr...

AI Technical Summary

Problems solved by technology

At present, the traditional analog passive gate driver uses fixed turn-on and turn-off resistance switching to realize IGBT drive control, which has inherent contradictions between switching loss and switching performance, and cannot realize the change rate of collector voltage and current. Decoupling control limits the safe operating range of power devices

Active gate drive technology uses active devices to inject the required gate current into the IGBT gate or apply a specific gate voltage, which can achieve a better compromise between the switching loss and switching performance of the IGBT, but there are still some Inherent disadvantages: ①A large number of analog devices are used to realize more complex control functions, and the number of internal devices in the driver is large, which reduces the reliability of the driver; ②The analog driver cannot fully record and store the electrical variables and operating status of the IGBT port. It is convenient for the system controller to monitor and diagnose the operating status and fault behavior of the IGBT

The IGBT collector voltage measurement is realized by using a large resistance voltage divider circuit. Due to the large error of the measurement circuit system, only the blocking high voltage can be measured. The IGBT switch transient measurement needs to consider the influence of resistance parasitic parameters, and cannot be used for accurate saturation voltage drop. Measurement

The IGBT saturation voltage drop measurement is realized by fast switching of the relay, but the switching speed of the relay still cannot meet the online measurement requirements of the IGBT saturation voltage drop

The IGBT saturation voltage drop is measured by diode clamping, but the saturation voltage drop of the diode will change at high temperature, resulting in low measurement accuracy

The IGBT saturation voltage drop is measured through a diode and a Zener tube. The Zener tube is very beneficial for power IGBT thermal compensation, but the Zener tube increases the limitation of measurement at high voltage.

In addition, the IGBT turn-on and turn-off transient time is short, requiring the IGBT collector voltage measurement circuit to have a high bandwidth measurement capability, so the design needs to consider the influence of parasitic parameters such as resistance and diode in the measurement circuit, and design the corresponding compensation circuit

Images