CN117055674A - Bipolar pulse constant current source with high switching rate - Google Patents

Bipolar pulse constant current source with high switching rate Download PDF

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Publication number
CN117055674A
CN117055674A CN202311163877.8A CN202311163877A CN117055674A CN 117055674 A CN117055674 A CN 117055674A CN 202311163877 A CN202311163877 A CN 202311163877A CN 117055674 A CN117055674 A CN 117055674A
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constant current
current source
mos tube
triode
pulse constant
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辛振
王新宇
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Hebei University of Technology
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Hebei University of Technology
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    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/10—Regulating voltage or current
    • G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
    • G05F1/56—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices
    • G05F1/561—Voltage to current converters

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Abstract

The application relates to a bipolar pulse constant current source with high switching rate, belonging to the technical field of power electronics. The bipolar pulse constant current source comprises a positive pulse constant current source and a negative pulse constant current source, wherein the positive pulse constant current source comprises a positive reference potential selection circuit, a positive constant current source circuit and a positive pulse constant current source control circuit, and the negative pulse constant current source comprises a negative reference potential selection circuit, a reverse constant current source circuit and a negative pulse constant current source control circuit. The noise filtering capacitor of the reference potential selection circuit and the filtering inductance of the constant current source circuit greatly reduce the fluctuation of the output current of the constant current source; according to the application, the MOS tube is driven by adopting a charge pump-like method while the rapid switching of the pulse current source is ensured, and the switch tube is not driven by an isolated power supply, so that the volume of the circuit is greatly reduced. The bipolar pulse constant current source has the characteristics of high switching speed, high stability, high precision, small volume, bipolar output and the like, and can meet the measurement requirement of quickly extracting various temperature-sensitive electrical parameters of the power semiconductor device under the working condition of quick change of junction temperature.

Description

Bipolar pulse constant current source with high switching rate
Technical Field
The application belongs to the technical field of power electronics, and particularly relates to a bipolar pulse constant current source with high switching rate.
Background
The constant current source with high precision, low temperature drift, high reliability and high switching rate is widely applied to various fields such as transient thermal characteristic test, temperature-sensitive electrical parameter measurement, clock circuits, oscillators and the like of power semiconductor devices. The high-precision instrument and the high-precision measurement bring forward the non-invasive, quick-response and high-precision demands on the constant current source, and particularly in the temperature-sensitive electrical parameter measurement of the power semiconductor device, the accurate measurement of the junction temperature of the power semiconductor device is the premise of real-time state monitoring and reliability evaluation of the device, so that the junction temperature extraction of the power semiconductor device is important in a power electronic system. In practical application, a temperature-sensitive electrical parameter method is often used for acquiring the junction temperature of the power semiconductor device in real time, and the method has the advantages of non-invasiveness, quick response, high precision, low cost and the like. With the development of power electronics related technologies, the accuracy requirements for junction temperature extraction technologies are increasing.
On the one hand, when the temperature-sensitive electrical parameters of the power semiconductor device are extracted, constant current source auxiliary measurement is often required, and a stable constant current source is a precondition for ensuring the extraction accuracy of the temperature-sensitive electrical parameters. On the other hand, different temperature-sensitive electrical parameters have different requirements on the current polarity of the auxiliary constant current source, for example, when measuring the voltage drop of the SiC MOSFET body diode, a constant current from source to drain needs to be provided; in measuring the threshold voltage of a SiC MOSFET, it is necessary to provide a constant drain-to-source current. Therefore, the constant current source capable of generating bipolar pulse current has important significance for meeting measurement requirements of different temperature-sensitive electrical parameters, reducing the complexity of measurement operation and increasing the universality of a measurement circuit. In addition, the switching delay of the constant current source is a key factor affecting the junction temperature extraction accuracy, and particularly, the switching delay requirement on the constant current source is higher under the working condition of rapid change of the junction temperature. In practical applications, the constant current source is required to have high voltage resistance and current backflow prevention capability due to the high voltage and large current of the main circuit. The existing pulse constant current source mainly has the following problems that firstly, the switching speed of most pulse constant current sources is slower, the pulse current has output delay of hundred us level and even ms level, and the requirement of high switching speed such as transient thermal property test cannot be met. Secondly, the stability of the output current is insufficient, and the high-precision measurement requirement cannot be met. Third, constant current sources that utilize ground resistance feedback are difficult to integrate with other circuits.
Disclosure of Invention
Aiming at the measurement requirement of temperature-sensitive electrical parameters of the current power semiconductor device, the application provides a bipolar pulse constant current source with high switching rate. The bipolar pulse constant current source has the characteristics of high switching speed, high stability, high precision, small volume, bipolar output and the like, and can meet the measurement requirement of quickly extracting various temperature-sensitive electrical parameters of the power semiconductor device under the working condition of quick change of junction temperature.
In order to achieve the above purpose, the technical scheme adopted by the application is as follows:
a bipolar pulse constant current source with high switching rate comprises a positive pulse constant current source and a negative pulse constant current source; the positive pulse constant current source comprises a positive reference potential selection circuit, a positive constant current source circuit and a positive pulse constant current source control circuit; the negative pulse constant current source comprises a negative reference potential selection circuit, a reverse constant current source circuit and a negative pulse constant current source control circuit;
the positive pulse constant current source control circuit comprises MOS tubes M1-M4, driving resistors R4-R8, diodes D1-D2, a capacitor C2, a triode Q2 and a positive pulse current control end; the triode Q2 is an NPN triode, the MOS transistors M1 and M4 are N-channel MOS transistors, and the MOS transistors M2 and M3 are P-channel MOS transistors; the drain electrode of the MOS tube M1 is connected with the collector electrode of the triode Q1 of the forward constant current source circuit, the source electrode of the MOS tube M1 is grounded, the grid electrode of the MOS tube M1 is connected with one end of the driving resistor R4, the other end of the driving resistor R4 and one end of the driving resistor R5 are connected with the cathode of the diode D1, and the anode of the diode D1 is connected with the other end of the driving resistor R5, one end of the driving resistor R6, one end of the driving resistor R8 and the positive pulse constant current source control end; the other end of the driving resistor R6 is connected with the grid electrodes of the MOS tube M3 and the MOS tube M4, the source electrode of the MOS tube M4 is connected with a negative voltage source, the drain electrode of the MOS tube M4 is connected with the drain electrode of the MOS tube M3 and one end of the driving resistor R7, the other end of the driving resistor R7 is connected with the other end of the capacitor C2, one end of the capacitor C2 and the source electrode of the MOS tube M2 are connected with the collector electrode of the triode Q1 of the forward constant current source circuit; the other end of the driving resistor R8 is connected with the base electrode of the triode Q2, the emitter electrode of the triode Q2 is connected with the source electrode of the MOS tube M3 and the grid electrode of the MOS tube M2, the collector electrode of the triode Q2 is connected with the source electrode of the MOS tube M2, the drain electrode of the MOS tube M2 is connected with the anode electrode of the diode D2, and the cathode electrode of the diode D2 is the output end of a positive pulse constant current source;
the negative pulse constant current source control circuit comprises MOS tubes M5-M8, driving resistors R12-R16, diodes D3-D4, a capacitor C4, a triode Q4 and a negative pulse current control end; the MOS transistors M7 and M8 are N-channel MOS transistors, the MOS transistors M5 and M6 are P-channel MOS transistors, and the triode Q4 is a PNP triode; the source electrode of the MOS tube M5 is grounded, the drain electrode of the MOS tube M5 is connected with the collector electrode of the triode Q3 of the reverse constant current source circuit, the grid electrode of the MOS tube M5 is connected with one end of the driving resistor R12, the other end of the driving resistor R12 is connected with one end of the driving resistor R13 and the anode of the diode D3, and the cathode of the diode D3 is connected with the other end of the driving resistor R13, one end of the driving resistor R14, one end of the driving resistor R16 and the negative pulse current control end; the other end of the driving resistor R14 is connected with the grid electrodes of the MOS tube M6 and the MOS tube M7, the source electrode of the MOS tube M6 is connected with a positive voltage source, the drain electrode of the MOS tube M6 is connected with the drain electrode of the MOS tube M7 and one end of the driving resistor R15, the other end of the driving resistor R15 is connected with one end of a capacitor C4, and the other end of the capacitor C4, the source electrode of the MOS tube M8 and the collector electrode of the triode Q4 are connected with the collector electrode of the triode Q3 of the reverse constant current source circuit; the other end of the driving resistor R16 is connected with the base electrode of the triode Q4, the emitter electrode of the triode Q4 is connected with the source electrode of the MOS tube M7 and the grid electrode of the MOS tube M8, the collector electrode of the triode Q4 is connected with the source electrode of the MOS tube M8, the drain electrode of the MOS tube M8 is connected with the cathode of the diode D4, and the anode of the diode D4 is the output end of the negative pulse constant current source.
Further, the positive reference potential selecting circuit comprises voltage dividing resistors R1 and R2 and a noise filtering capacitor C1; one end of the voltage dividing resistor R1 is connected with a positive voltage source, the other end of the voltage dividing resistor R2 is connected with one end of the noise filtering capacitor C1 and the non-inverting input end of the operational amplifier U1 of the forward constant current source circuit, and the other ends of the voltage dividing resistor R2 and the noise filtering capacitor C1 are grounded; or the positive reference potential selecting circuit adopts DAC signals to output positive reference potential through the in-phase proportional operation circuit.
Further, the forward constant current source circuit comprises a filter inductor L1, a current adjusting resistor R3, an operational amplifier U1 and a triode Q1, wherein the triode Q1 is a PNP triode; one end of the filter inductor L1 is connected with a positive voltage source, the other end of the filter inductor L1 is connected with one end of the current regulating resistor R3, the other end of the current regulating resistor R3 is connected with an emitter of the triode Q1 and an inverting input end of the operational amplifier U1, a base electrode of the triode Q1 is connected with an output end of the operational amplifier U1, and a collector electrode of the triode Q1 is connected with a positive pulse constant current source control circuit.
Further, the negative reference potential selecting circuit comprises voltage dividing resistors R9 and R10 and a noise filtering capacitor C3; one end of the voltage dividing resistor R10 is connected with a negative voltage source, and the other end of the voltage dividing resistor R9 is connected with one end of the noise filtering capacitor C3 and the non-inverting input end of the operational amplifier U2 of the reverse constant current source circuit, and the other ends of the voltage dividing resistor R9 and the filtering capacitor C3 are grounded.
Further, the reverse constant current source circuit comprises a filter inductor L2, a current adjusting resistor R11, an operational amplifier U2 and a triode Q3, wherein the triode Q3 is an NPN triode; one end of the filter inductor L2 is connected with a negative voltage source, the other end of the filter inductor L2 is connected with one end of the current regulating resistor R11, the other end of the current regulating resistor R11 is connected with an emitter of the triode Q3 and an inverting input end of the operational amplifier U2, a base electrode of the triode Q3 is connected with an output end of the operational amplifier U2, and a collector electrode of the triode Q3 is connected with a negative pulse constant current source control circuit.
Further, when the positive pulse constant current source control end outputs a high level, the positive pulse constant current source current provided by the positive pulse constant current source control end passes through the diode D1 and the driving resistor R4, so that the MOS tube M1 is quickly turned on by charging the grid electrode of the MOS tube M1, the positive pulse constant current source control end provides a base current for the triode Q2 to disconnect the MOS tube M2, meanwhile, the positive pulse constant current source current discharges the grid electrode of the MOS tube M3 and charges the grid electrode of the MOS tube M4 through the driving resistor R6, so that the MOS tube M3 is disconnected, the MOS tube M4 is turned on, and the negative voltage source charges the capacitor C2 through the driving resistor R7, so that the positive pulse constant current source current does not flow through the MOS tube M2 any more but only flows through the MOS tube M1, and current switching is completed; when the positive pulse constant current source control end outputs a low level, the positive pulse constant current source current provided by the positive pulse constant current source control end passes through the driving resistors R4 and R5 to rapidly disconnect the MOS tube M1 for grid discharge of the MOS tube M1, the positive pulse constant current source control end does not provide base current for the triode Q2 any more, meanwhile, the positive pulse constant current source current charges the grid of the MOS tube M3 and discharges the grid of the MOS tube M4 through the driving resistor R6 to open the MOS tube M3, the MOS tube M4 is disconnected, the capacitor C2 charges the grid of the MOS tube M2 through the driving resistor R7 and the MOS tube M3 to open the MOS tube M2, and at the moment, the current does not flow through the MOS tube M1 any more but only flows through the MOS tube M2 to finish current switching;
when the negative pulse constant current source control end outputs a low level, the negative pulse constant current source current provided by the negative pulse constant current source control end passes through the diode D3 and the driving resistor R13 to charge the grid electrode of the MOS tube M5 so as to enable the MOS tube M5 to be rapidly opened, the negative pulse constant current source control end provides base current for the triode Q4 so as to enable the MOS tube M8 to be disconnected, meanwhile, the negative pulse constant current source current passes through the driving resistor R14 to discharge the grid electrode of the MOS tube M7 and charge the grid electrode of the MOS tube M6 so as to enable the MOS tube M7 to be disconnected, the MOS tube M6 is opened, the positive voltage source charges the capacitor C4 through the driving resistor R15, and at the moment, the negative pulse constant current source current does not flow through the MOS tube M8 but only flows through the MOS tube M5, and current switching is completed; when the negative pulse constant current source control end outputs a high level, the negative pulse constant current source current provided by the negative pulse constant current source control end passes through the driving resistors R12 and R13 to rapidly disconnect the MOS tube M5 for grid discharge of the MOS tube M5, the negative pulse constant current source control end does not provide base current for the transistor Q4 any more, meanwhile, the negative pulse constant current source current charges the grid of the MOS tube M7 and discharges the grid of the MOS tube M6 through the driving resistor R14, the MOS tube M7 is opened, the MOS tube M6 is disconnected, the capacitor C4 charges the grid of the MOS tube M8 through the driving resistor R15 and the MOS tube M7, and the MOS tube M8 is opened, at the moment, the positive pulse constant current source current does not flow through the MOS tube M5 any more and only flows through the MOS tube M8, and current switching is completed.
Compared with the prior art, the application has the advantages that:
1. under the working condition that the junction temperature is rapidly and monotonically changed, the switching delay of the constant current source is a key factor influencing the extraction of the peak value/valley value junction temperature of the power semiconductor device, and the excessive switching delay can cause larger deviation between the measurement result and the actual value of the peak value/valley value junction temperature, so that the working state of the power semiconductor device can not be accurately reflected. Therefore, the application provides a pulse constant current source with high switching rate for assisting temperature-sensitive electrical parameter extraction of a power semiconductor device. When the electric parameters of the power semiconductor device are measured, the constant current value of the constant current source can influence the measurement of the electric parameters, and as the noise filtering capacitor is added in the reference potential selection circuit and the filtering inductor is added in the constant current source circuit, the fluctuation of the output current of the constant current source is greatly reduced, and in the actual test, when the output current is set to be 1mA, the fluctuation of the current is only less than 50nA, and the current stability is extremely high. Therefore, the bipolar pulse constant current source designed by the application has higher precision and can be used for precisely measuring the electric parameters of the power semiconductor device.
2. The existing control circuit of the pulse constant current source mostly needs an isolation power supply for driving the switching tube, and the application adopts a charge pump-like method to drive the MOS tube while ensuring the rapid switching of the pulse current source, so that the isolation power supply is not needed to drive the switching tube, and the volume of the circuit is greatly reduced.
3. The application adopts the MOS tube with low switch delay and has extremely high switching rate. Compared with the switching delay of us level or even ms level required by using the solid-state relay as a change-over switch, the switching delay adopted by the application can reach ns level, greatly shortens the output response time of current, and is suitable for serving as an auxiliary pulse constant current source in transient thermal test with extremely rapid temperature change.
4. Compared with a conventional current source, the current source designed by the application is structurally optimized, and the current adjusting resistors R3 and R11 of the constant current source are connected to the power supply end, so that the unification of the current negative output end and the ground is realized; the design method increases the complexity of the structure, and when the conventional constant current source is used for measurement, the output voltage of the pulse constant current source can be obtained by subtracting the voltage of the current negative output end due to the existence of the grounded feedback resistor, and the direct measurement of the obtained voltage is the output voltage of the pulse constant current source without subtraction operation, so that the measurement step of the output voltage is simplified.
5. The application has the diode which is arranged at the current output end and has the same direction with the output current, and can prevent the current from flowing backwards into the constant current source circuit. The MOS tubes (M2, M8) and the diodes (D2, D4) used in the application are replaced by devices which can withstand high voltage, so that the device to be tested can be used in the occasion of high voltage operation. The MOS tube M2 of the positive pulse constant current source is replaced by a high-voltage resistant device, the positive pulse constant current source has the capability of tolerating high negative voltage, and the diode M2 of the positive pulse constant current source is replaced by the high-voltage resistant device, and the positive pulse constant current source has the capability of tolerating high positive voltage. Similarly, the MOS tube M8 of the negative pulse constant current source is replaced by a high voltage resistant device, the negative pulse constant current source has the capability of tolerating high positive voltage, and the diode M4 of the negative pulse constant current source is replaced by the high voltage resistant device, and the negative pulse constant current source has the capability of tolerating high negative voltage. Therefore, the voltage withstand level of the bipolar pulse constant current source can be improved by selecting MOS (metal oxide semiconductor) tubes and diodes with different voltage withstand voltages, and the application range of the bipolar pulse constant current source is widened.
Drawings
FIG. 1 is a topology of a bipolar pulsed constant current source of the present application;
FIG. 2 is a DAC-based positive and negative reference potential generation circuit;
FIG. 3 is a SiC MOSFET threshold voltage measurement circuit;
fig. 4 is a circuit for measuring the body diode drop of a SiC MOSFET.
Detailed Description
The following description will give specific embodiments with reference to the accompanying drawings, which are only used for describing the technical scheme of the present application in detail, and are not used for limiting the protection scope of the present application.
The application provides a bipolar pulse constant current source with high switching rate (bipolar pulse constant current source for short, see fig. 1-2), which has the characteristics of high switching rate, high reliability, high precision, small volume and the like, and comprises a positive pulse constant current source and a negative pulse constant current source;
the positive pulse constant current source comprises a positive reference potential selection circuit, a positive constant current source circuit and a positive pulse constant current source control circuit; the positive reference potential selecting circuit comprises voltage dividing resistors R1 and R2 and a noise filtering capacitor C1; one end of the voltage dividing resistor R1 is connected with a positive voltage sourceVcc, one end of the divider resistor R2, the non-inverting input end of the operational amplifier U1 of the forward constant current source circuit and one end of the noise filtering capacitor C1 are connected to form a connection point, and the connection point provides a positive reference potential V for the backward constant current source circuit ref_I+ The method comprises the steps of carrying out a first treatment on the surface of the The other end of the divider resistor R2 and the noise filtering capacitor C1 is grounded. The noise filter capacitor C1 can be 1 μF. The positive reference potential calculation formula is:
wherein R is 1 、R 2 Is the resistance value of the voltage dividing resistors R1 and R2, V cc Is the voltage of the positive voltage source Vcc.
The positive reference potential selection circuit can also adopt a DAC mode besides a resistor voltage division structure; as shown in FIG. 2, the DAC signal can be generated by a special DAC chip or DAC peripheral of a singlechip, the DAC signal is connected to one end of a resistor R3, the other end of the resistor R4 is connected with the in-phase input end of an operational amplifier, one end of a resistor R2 is connected with the output end of the operational amplifier, the other end of the resistor R2 is connected with the inverting input end of the operational amplifier and one end of a resistor R1, the other end of the resistor R1 is grounded, and the DAC signal is output by the in-phase proportional operation circuit to obtain a positive reference potential V ref_I+ 。
The forward constant current source circuit comprises a filter inductor L1, a current regulating resistor R3, an operational amplifier U1 and a triode Q1; one end of a filter inductor L1 is connected with a positive voltage source Vcc, the other end of the filter inductor L1 is connected with one end of a current regulating resistor R3, the other end of the current regulating resistor R3 is connected with an emitter of a triode Q1 and an inverting input end of an operational amplifier U1, a base electrode of the triode Q1 is connected with an output end of the operational amplifier U1, and a collector electrode of the triode Q1 is connected with a drain electrode of an MOS tube M1, a source electrode of an MOS tube M2, a collector electrode of the triode Q2 and one end of a capacitor C2 of a positive pulse constant current source control circuit; the triode Q1 is a PNP triode, the PNP triode can be replaced by a P channel MOS tube, and the grid electrode, the source electrode and the drain electrode of the P channel MOS tube replace the base electrode, the emitting electrode and the collecting electrode of the PNP triode respectively.
The operational amplifier U1 achieves the purpose of constant current by controlling the constant voltage difference from the positive voltage source Vcc to the other end of the current regulating resistor R3, and the collector current of the triode Q1 is the positive pulse output current of the bipolar pulse current source; because the current amplification factor of the triode Q1 is larger, and the base current of the triode Q1 is negligible, the collector current of the triode Q1 can be approximately equal to the emitter current; when the collector current is smaller than the preset positive pulse constant current source current, the emitter current is reduced to reduce the voltage difference from the positive voltage source Vcc to the other end of the current regulating resistor R3, the voltage of the reverse input end of the operational amplifier U1 is larger than the voltage of the non-inverting input end, the output voltage of the operational amplifier U1 is reduced due to the negative feedback effect, the voltage drop from the emitter to the base of the triode Q1 is almost unchanged, the voltage of the other end of the current regulating resistor R3 is reduced, the voltage difference from the positive voltage source Vcc to the other end of the current regulating resistor R3 is increased, the emitter current and the collector current of the triode Q1 are increased to form the negative feedback effect of the current, and finally the output current is stabilized at the preset positive pulse constant current source current. When the collector current of the triode Q1 is larger than the preset positive pulse constant current source current, the emitter current is increased to cause the voltage difference from the positive voltage source Vcc to the other end of the current regulating resistor R3 to be increased, the voltage of the reverse input end of the operational amplifier U1 is smaller than the voltage of the non-inverting input end, the output voltage of the operational amplifier U1 is increased due to the action of negative feedback, the diode voltage drop from the emitter of the triode Q1 to the base is almost unchanged, the voltage of the other end of the current regulating resistor R3 is increased, the voltage difference from the positive voltage source Vcc to the other end of the current regulating resistor R3 is reduced, the emitter circuit and the collector current of the triode Q1 are reduced, the negative feedback action of current is formed, and finally the output current is stabilized at the preset positive pulse constant current source current. The preset positive pulse constant current source current calculation formula is as follows:
wherein R is 3 For regulating currentThe resistance of the resistor R3.
The positive pulse constant current source control circuit comprises MOS tubes M1-M4, driving resistors R4-R8, diodes D1-D2, a capacitor C2, a triode Q2 and a positive pulse current control end I+ CTR; the MOS transistors M1 and M4 are N-channel MOS transistors, the MOS transistors M2 and M3 are P-channel MOS transistors, and the triode Q2 is an NPN triode; the drain electrode of the MOS tube M1 is connected with the collector electrode of the triode Q1, the source electrode of the MOS tube M1 is grounded, the grid electrode of the MOS tube M1 is connected with one end of a driving resistor R4, the other end of the driving resistor R4 and one end of a driving resistor R5 are connected with the cathode of a diode D1, the anode of the diode D1 is connected with the other end of the driving resistor R5, one end of the driving resistor R6, one end of the driving resistor R8 and a positive pulse constant current source control end I_CTR, and the positive pulse constant current source control end I_CTR is used for controlling the positive pulse constant current source to be switched rapidly; the other end of the driving resistor R6 is connected with the grid electrodes of the MOS tube M3 and the MOS tube M4, the source electrode of the MOS tube M4 is connected with the negative voltage source Vee, the drain electrode of the MOS tube M4 is connected with the drain electrode of the MOS tube M3 and one end of the driving resistor R7, the other end of the driving resistor R7 is connected with the other end of the capacitor C2, and one end of the capacitor C2 and the source electrode of the MOS tube M2 are connected with the collector electrode of the triode Q1; the other end of the driving resistor R8 is connected with the base electrode of the triode Q2, the emitter electrode of the triode Q2 is connected with the source electrode of the MOS tube M3 and the grid electrode of the MOS tube M2, the collector electrode of the triode Q2 is connected with the source electrode of the MOS tube M2, the drain electrode of the MOS tube M2 is connected with the anode of the diode D2, and the cathode of the diode D2 is the output end of the positive pulse constant current source; the positions of the driving resistor R7 and the capacitor C2 can be interchanged; the NPN triode Q2 can be replaced by an N channel MOS tube, and the grid electrode, the source electrode and the drain electrode of the N channel MOS tube replace the base electrode, the emitter electrode and the collector electrode of the NPN triode respectively.
When the positive pulse constant current source control end I+ CTR is at a high level, the current provided by the positive pulse constant current source control end passes through the diode D1 and the driving resistor R4 to charge the grid electrode of the MOS tube M1 so as to enable the channel of the MOS tube M1 to be quickly opened, the positive pulse constant current source control end provides base current for the triode Q2 and enables the MOS tube M2 to be disconnected through the current amplification effect of the triode Q2, meanwhile, the current provided by the positive pulse constant current source control end passes through the driving resistor R6 to discharge the grid electrode of the MOS tube M3 and charge the grid electrode of the MOS tube M4 so that the MOS tube M3 is disconnected and the MOS tube M4 is opened, the negative voltage source Vee passes through the driving resistor R7 to charge the capacitor C2, and at the moment, the positive pulse constant current does not flow through the MOS tube M2 any more, but only flows through the MOS tube M1, and the pulse current successfully completes current switching. When the positive pulse constant current source control end is at a low level, the positive pulse constant current source control end provides current to pass through the driving resistors R4 and R5 to cause the gate discharge of the MOS tube M1 to cause the delayed channel to pinch off, the positive pulse constant current source control end does not provide base current for the triode Q2 any more, meanwhile, the positive pulse constant current source control end provides current to charge the gate of the MOS tube M3 and discharge the gate of the MOS tube M4 through the driving resistor R6, so that the MOS tube M3 is turned on, the MOS tube M4 is turned off, the capacitor C2 charges the gate of the MOS tube M2 through the driving resistor R7 and the MOS tube M3 to turn on, at the moment, the positive pulse constant current source current does not flow through the MOS tube M1 any more but only flows through the MOS tube M2, and the pulse current successfully completes current switching. It should be noted that the driving resistors R4 and R8 need to be adjusted to make the MOS transistors M1 and M2 have a certain turn-on overlap time, so as to prevent the current of the filter inductor L1 from having no freewheeling circuit.
The negative pulse constant current source comprises a negative reference potential selection circuit, a reverse constant current source circuit and a negative pulse constant current source control circuit; the negative reference potential selecting circuit comprises divider resistors R9 and R10 and a noise filtering capacitor C3; one end of the divider resistor R10 is connected with the negative voltage source Vee, the other end is connected with one end of the divider resistor R9, the non-inverting input end of the operational amplifier U2 and one end of the noise filtering capacitor C3 to form a connection point, and the connection point provides a negative reference potential V for a post constant current source circuit ref_I- The method comprises the steps of carrying out a first treatment on the surface of the The other end of the divider resistor R9 and the filtering capacitor C3 is grounded. The noise filter capacitor C3 may be 1 μf. The negative reference potential calculation formula is:
wherein R is 9 、R 10 Is the resistance value of the voltage dividing resistors R9 and R10, V ee Is the voltage of the negative voltage source Vee.
The negative reference potential selection circuit can also be generated by DAC mode besides the resistor voltage division structureFIG. 2 shows; the DAC signal can be generated by a special DAC chip or the DAC peripheral of a singlechip, the DAC signal is connected with one end of a resistor R4, the other end of the resistor R4 is connected with a resistor R5 and the reverse input end of an operational amplifier, the other end of the resistor R5 is connected with the output end of the operational amplifier, one end of a resistor R6 is connected with the non-inverting input end of the operational amplifier and the other end of the resistor R6 is grounded, and the DAC signal is output by an inverting proportion circuit to obtain a negative reference potential V ref_I- 。
The reverse constant current source circuit comprises a filter inductor L2, a current regulating resistor R11, an operational amplifier U2 and a triode Q3; one end of the filter inductor L2 is connected with a negative voltage source Vee, the other end of the filter inductor L2 is connected with one end of a current regulating resistor R11, the other end of the current regulating resistor R11 is connected with an emitter of a triode Q3 and an inverting input end of an operational amplifier U2, a base electrode of the triode Q3 is connected with an output end of the operational amplifier U2, and a collector electrode of the triode Q3 is connected with a drain electrode of a MOS tube M5, a source electrode of a MOS tube M8, a collector electrode of a triode Q4 and one end of a capacitor C4 of a negative pulse constant current source control circuit; the triode Q3 is an NPN triode, the NPN triode can be replaced by an N channel MOS tube, and the grid electrode, the source electrode and the drain electrode of the N channel MOS tube replace the base electrode, the emitter electrode and the collector electrode of the PNP triode respectively.
The operational amplifier U2 achieves the purpose of constant current by controlling the constant voltage difference from the negative voltage source Vee to the other end of the current regulating resistor R11, and the collector current of the triode Q3 is the negative pulse output current of the bipolar pulse current source. Because the current amplification factor of the triode Q3 is larger, the base current is negligible, the collector current can be approximately equal to the emitter current, when the collector current is smaller than the preset constant current source current, the emitter current is reduced to reduce the voltage difference from the negative voltage source Vee to the other end of the current regulating resistor R11, the voltage of the reverse input end of the operational amplifier U2 is smaller than the voltage of the non-inverting input end, the output voltage of the operational amplifier U2 is increased due to the action of negative feedback, the diode voltage drop from the emitter to the base of the triode Q3 is almost unchanged, the voltage of the other end of the current regulating resistor R11 is increased, the voltage difference from the negative voltage source Vee to the other end of the current regulating resistor R11 is increased, the emitter and the collector current of the triode Q3 are increased, the negative feedback action of the current is formed, and finally the output current is stabilized at the preset negative pulse constant current source. When the collector current of the triode Q3 is larger than the preset negative pulse constant current source current, the voltage difference from the negative voltage source Vee to the other end of the current regulating resistor R11 is reduced due to the fact that the emitter current is increased as well, the voltage of the reverse input end of the operational amplifier U2 is larger than the voltage of the non-inverting input end, the output voltage of the operational amplifier U2 is reduced due to the effect of negative feedback, the diode voltage drop from the emitter of the triode Q3 to the base is almost unchanged, the voltage of the other end of the current regulating resistor R11 is reduced, the voltage difference from the negative voltage source Vee to the other end of the current regulating resistor R11 is reduced, the emitter and collector currents of the triode Q3 are reduced, the negative feedback effect of current is formed, and finally the output current is stabilized at the preset negative pulse constant current source current. The calculation formula of the preset negative pulse constant current source current is as follows:
wherein R is 11 The resistance of the resistor R11 is adjusted for the current.
The negative pulse constant current source control circuit comprises MOS tubes M5-M8, driving resistors R12-R16, diodes D3-D4, a capacitor C4, a triode Q4 and a negative pulse current control end; the MOS transistors M7 and M8 are N-channel MOS transistors, the MOS transistors M5 and M6 are P-channel MOS transistors, and the triode Q4 is a PNP triode; the source electrode of the MOS tube M5 is grounded, the drain electrode of the MOS tube M5 is connected with the collector electrode of the triode Q3, the grid electrode of the MOS tube M5 is connected with one end of the driving resistor R12, the other end of the driving resistor R12 is connected with one end of the driving resistor R13 and the anode of the diode D3, the cathode of the diode D3 is connected with the other end of the driving resistor R13, one end of the driving resistor R14, one end of the driving resistor R16 and the negative pulse current control end, and the negative pulse current control end is used for controlling the negative pulse constant current source to be switched rapidly; the other end of the driving resistor R14 is connected with the grid electrodes of the MOS tube M6 and the MOS tube M7, the source electrode of the MOS tube M6 is connected with the positive voltage source Vcc, the drain electrode of the MOS tube M6 is connected with the drain electrode of the MOS tube M7 and one end of the driving resistor R15, the other end of the driving resistor R15 is connected with one end of the capacitor C4, and the other end of the capacitor C4 is connected with the source electrode of the MOS tube M8 and the collector electrode of the triode Q4; the other end of the driving resistor R16 is connected with the base electrode of the triode Q4, the emitter electrode of the triode Q4 is connected with the source electrode of the MOS tube M7 and the grid electrode of the MOS tube M8, the collector electrode of the triode Q4 is connected with the source electrode of the MOS tube M8, the drain electrode of the MOS tube M8 is connected with the cathode of the diode D4, and the anode of the diode D4 is the output end of the negative pulse constant current source; the positions of the driving resistor R15 and the capacitor C4 can be interchanged; the PNP triode Q2 can be replaced by a P channel MOS tube, and the grid electrode, the source electrode and the drain electrode of the P channel MOS tube replace the base electrode, the emitting electrode and the collecting electrode of the PNP triode respectively.
When the negative pulse constant current source control end I_CTR is at a low level, the negative pulse constant current source control end provides current to pass through the diode D3 and the driving resistor R13 so as to charge the grid electrode of the MOS tube M5 to enable a channel of the MOS tube to be quickly opened, the negative pulse constant current source control end provides base current to the triode Q4 and enables the MOS tube M8 to be disconnected through the current amplification effect of the triode Q4, meanwhile, the negative pulse constant current source control end provides current to discharge the grid electrode of the MOS tube M7 and charge the grid electrode of the MOS tube M6 through the driving resistor R14 so that the MOS tube M7 is disconnected and the MOS tube M6 is opened, the positive voltage source Vcc charges the capacitor C4 through the driving resistor R15, and at the moment, the negative pulse constant current source current does not flow through the MOS tube M8 any more and only flows through the MOS tube M5, and the pulse current successfully completes current switching. When the negative pulse constant current source control end I+ CTR is at a high level, the negative pulse constant current source control end provides current through the driving resistors R12 and R13 to enable the gate electrode of the MOS tube M5 to discharge so as to enable the delay channel of the MOS tube M5 to pinch off, the negative pulse constant current source control end does not provide base current for the transistor Q4 any more, meanwhile, the negative pulse constant current source control end provides current through the driving resistor R14 to charge the gate electrode of the MOS tube M7 and discharge the gate electrode of the MOS tube M6, so that the MOS tube M7 is turned on, the MOS tube M6 is turned off, the capacitor C4 charges the gate electrode of the MOS tube M8 through the driving resistor R15 and the MOS tube M7, and at the moment, positive pulse constant current source current does not flow through the MOS tube M5 any more, but only flows through the MOS tube M8, and the pulse current successfully completes current switching. It should be noted that the driving resistors R4 and R8 need to be adjusted to make the MOS transistors M5 and M8 have a certain turn-on overlap time, so as to prevent the current of the filter inductor L2 from having no freewheeling circuit.
Fig. 3 and 4 are respectively a SiC MOSFET threshold voltage measurement circuit and a body diode drop measurement circuit. When the threshold voltage is measured, the grid electrode and the drain electrode of the SiC MOSFET are required to be short-circuited, the positive pulse constant current source is controlled by the positive pulse current control end I+ CTR of the bipolar pulse constant current source, and when the positive pulse constant current source outputs constant current, the end voltage between the drain electrode and the source electrode of the SiC MOSFET is the threshold voltage. When the voltage drop of the body diode is measured, negative pressure is required to be applied to the grid electrode and the source electrode of the SiC MOSFET, the negative pulse constant current source is controlled by the negative pulse current control end I_CTR of the bipolar pulse constant current source, and when the negative pulse constant current source outputs constant current, the end voltage between the drain electrode and the source electrode of the SiC MOSFET is the voltage drop of the body diode.
The application is applicable to the prior art where it is not described.

Claims (6)

1. A bipolar pulse constant current source with high switching rate comprises a positive pulse constant current source and a negative pulse constant current source; the positive pulse constant current source comprises a positive reference potential selection circuit, a positive constant current source circuit and a positive pulse constant current source control circuit; the negative pulse constant current source comprises a negative reference potential selection circuit, a reverse constant current source circuit and a negative pulse constant current source control circuit;
the positive pulse constant current source control circuit comprises MOS tubes M1-M4, driving resistors R4-R8, diodes D1-D2, a capacitor C2, a triode Q2 and a positive pulse current control end; the triode Q2 is an NPN triode, the MOS transistors M1 and M4 are N-channel MOS transistors, and the MOS transistors M2 and M3 are P-channel MOS transistors; the drain electrode of the MOS tube M1 is connected with the collector electrode of the triode Q1 of the forward constant current source circuit, the source electrode of the MOS tube M1 is grounded, the grid electrode of the MOS tube M1 is connected with one end of the driving resistor R4, the other end of the driving resistor R4 and one end of the driving resistor R5 are connected with the cathode of the diode D1, and the anode of the diode D1 is connected with the other end of the driving resistor R5, one end of the driving resistor R6, one end of the driving resistor R8 and the positive pulse constant current source control end; the other end of the driving resistor R6 is connected with the grid electrodes of the MOS tube M3 and the MOS tube M4, the source electrode of the MOS tube M4 is connected with a negative voltage source, the drain electrode of the MOS tube M4 is connected with the drain electrode of the MOS tube M3 and one end of the driving resistor R7, the other end of the driving resistor R7 is connected with the other end of the capacitor C2, one end of the capacitor C2 and the source electrode of the MOS tube M2 are connected with the collector electrode of the triode Q1 of the forward constant current source circuit; the other end of the driving resistor R8 is connected with the base electrode of the triode Q2, the emitter electrode of the triode Q2 is connected with the source electrode of the MOS tube M3 and the grid electrode of the MOS tube M2, the collector electrode of the triode Q2 is connected with the source electrode of the MOS tube M2, the drain electrode of the MOS tube M2 is connected with the anode electrode of the diode D2, and the cathode electrode of the diode D2 is the output end of a positive pulse constant current source;
the negative pulse constant current source control circuit comprises MOS tubes M5-M8, driving resistors R12-R16, diodes D3-D4, a capacitor C4, a triode Q4 and a negative pulse current control end; the MOS transistors M7 and M8 are N-channel MOS transistors, the MOS transistors M5 and M6 are P-channel MOS transistors, and the triode Q4 is a PNP triode; the source electrode of the MOS tube M5 is grounded, the drain electrode of the MOS tube M5 is connected with the collector electrode of the triode Q3 of the reverse constant current source circuit, the grid electrode of the MOS tube M5 is connected with one end of the driving resistor R12, the other end of the driving resistor R12 is connected with one end of the driving resistor R13 and the anode of the diode D3, and the cathode of the diode D3 is connected with the other end of the driving resistor R13, one end of the driving resistor R14, one end of the driving resistor R16 and the negative pulse current control end; the other end of the driving resistor R14 is connected with the grid electrodes of the MOS tube M6 and the MOS tube M7, the source electrode of the MOS tube M6 is connected with a positive voltage source, the drain electrode of the MOS tube M6 is connected with the drain electrode of the MOS tube M7 and one end of the driving resistor R15, the other end of the driving resistor R15 is connected with one end of a capacitor C4, and the other end of the capacitor C4, the source electrode of the MOS tube M8 and the collector electrode of the triode Q4 are connected with the collector electrode of the triode Q3 of the reverse constant current source circuit; the other end of the driving resistor R16 is connected with the base electrode of the triode Q4, the emitter electrode of the triode Q4 is connected with the source electrode of the MOS tube M7 and the grid electrode of the MOS tube M8, the collector electrode of the triode Q4 is connected with the source electrode of the MOS tube M8, the drain electrode of the MOS tube M8 is connected with the cathode of the diode D4, and the anode of the diode D4 is the output end of the negative pulse constant current source.
2. The bipolar pulse constant current source with high switching rate according to claim 1, wherein the positive reference potential selecting circuit comprises voltage dividing resistors R1, R2 and a noise filtering capacitor C1; one end of the voltage dividing resistor R1 is connected with a positive voltage source, the other end of the voltage dividing resistor R2 is connected with one end of the noise filtering capacitor C1 and the non-inverting input end of the operational amplifier U1 of the forward constant current source circuit, and the other ends of the voltage dividing resistor R2 and the noise filtering capacitor C1 are grounded; or the positive reference potential selecting circuit adopts DAC signals to output positive reference potential through the in-phase proportional operation circuit.
3. The bipolar pulse constant current source with high switching rate according to claim 1 or 2, wherein the forward constant current source circuit comprises a filter inductance L1, a current adjusting resistor R3, an operational amplifier U1 and a triode Q1, the triode Q1 being a PNP triode; one end of the filter inductor L1 is connected with a positive voltage source, the other end of the filter inductor L1 is connected with one end of the current regulating resistor R3, the other end of the current regulating resistor R3 is connected with an emitter of the triode Q1 and an inverting input end of the operational amplifier U1, a base electrode of the triode Q1 is connected with an output end of the operational amplifier U1, and a collector electrode of the triode Q1 is connected with a positive pulse constant current source control circuit.
4. The bipolar pulse constant current source with high switching rate according to claim 1, wherein the negative reference potential selecting circuit comprises voltage dividing resistors R9, R10 and a noise filtering capacitor C3; one end of the voltage dividing resistor R10 is connected with a negative voltage source, and the other end of the voltage dividing resistor R9 is connected with one end of the noise filtering capacitor C3 and the non-inverting input end of the operational amplifier U2 of the reverse constant current source circuit, and the other ends of the voltage dividing resistor R9 and the filtering capacitor C3 are grounded.
5. The bipolar pulse constant current source with high switching rate according to claim 1 or 4, wherein the reverse constant current source circuit comprises a filter inductance L2, a current adjusting resistor R11, an operational amplifier U2 and a triode Q3, and the triode Q3 is an NPN triode; one end of the filter inductor L2 is connected with a negative voltage source, the other end of the filter inductor L2 is connected with one end of the current regulating resistor R11, the other end of the current regulating resistor R11 is connected with an emitter of the triode Q3 and an inverting input end of the operational amplifier U2, a base electrode of the triode Q3 is connected with an output end of the operational amplifier U2, and a collector electrode of the triode Q3 is connected with a negative pulse constant current source control circuit.
6. The bipolar pulse constant current source with high switching rate according to claim 1, wherein when the positive pulse constant current source control end outputs high level, the positive pulse constant current source current provided by the positive pulse constant current source control end passes through the diode D1 and the driving resistor R4 to charge the grid electrode of the MOS transistor M1 so as to rapidly turn on the MOS transistor M1, the positive pulse constant current source control end provides base current for the triode Q2 so as to disconnect the MOS transistor M2, meanwhile, the positive pulse constant current source current passes through the driving resistor R6 to discharge the grid electrode of the MOS transistor M3 and charge the grid electrode of the MOS transistor M4 so as to disconnect the MOS transistor M3 and turn on the MOS transistor M4, and the negative voltage source passes through the driving resistor R7 to charge the capacitor C2, so that the positive pulse constant current source current does not flow through the MOS transistor M2 but only flows through the MOS transistor M1, and current switching is completed; when the positive pulse constant current source control end outputs a low level, the positive pulse constant current source current provided by the positive pulse constant current source control end passes through the driving resistors R4 and R5 to rapidly disconnect the MOS tube M1 for grid discharge of the MOS tube M1, the positive pulse constant current source control end does not provide base current for the triode Q2 any more, meanwhile, the positive pulse constant current source current charges the grid of the MOS tube M3 and discharges the grid of the MOS tube M4 through the driving resistor R6 to open the MOS tube M3, the MOS tube M4 is disconnected, the capacitor C2 charges the grid of the MOS tube M2 through the driving resistor R7 and the MOS tube M3 to open the MOS tube M2, and at the moment, the current does not flow through the MOS tube M1 any more but only flows through the MOS tube M2 to finish current switching;
when the negative pulse constant current source control end outputs a low level, the negative pulse constant current source current provided by the negative pulse constant current source control end passes through the diode D3 and the driving resistor R13 to charge the grid electrode of the MOS tube M5 so as to enable the MOS tube M5 to be rapidly opened, the negative pulse constant current source control end provides base current for the triode Q4 so as to enable the MOS tube M8 to be disconnected, meanwhile, the negative pulse constant current source current passes through the driving resistor R14 to discharge the grid electrode of the MOS tube M7 and charge the grid electrode of the MOS tube M6 so as to enable the MOS tube M7 to be disconnected, the MOS tube M6 is opened, the positive voltage source charges the capacitor C4 through the driving resistor R15, and at the moment, the negative pulse constant current source current does not flow through the MOS tube M8 but only flows through the MOS tube M5, and current switching is completed; when the negative pulse constant current source control end outputs a high level, the negative pulse constant current source current provided by the negative pulse constant current source control end passes through the driving resistors R12 and R13 to rapidly disconnect the MOS tube M5 for grid discharge of the MOS tube M5, the negative pulse constant current source control end does not provide base current for the transistor Q4 any more, meanwhile, the negative pulse constant current source current charges the grid of the MOS tube M7 and discharges the grid of the MOS tube M6 through the driving resistor R14, the MOS tube M7 is opened, the MOS tube M6 is disconnected, the capacitor C4 charges the grid of the MOS tube M8 through the driving resistor R15 and the MOS tube M7, and the MOS tube M8 is opened, at the moment, the positive pulse constant current source current does not flow through the MOS tube M5 any more and only flows through the MOS tube M8, and current switching is completed.
CN202311163877.8A 2023-09-11 2023-09-11 Bipolar pulse constant current source with high switching rate Pending CN117055674A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117519396A (en) * 2023-12-27 2024-02-06 中国科学院合肥物质科学研究院 Load self-adaptive high-efficiency pulse constant current source and control method

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117519396A (en) * 2023-12-27 2024-02-06 中国科学院合肥物质科学研究院 Load self-adaptive high-efficiency pulse constant current source and control method
CN117519396B (en) * 2023-12-27 2024-03-22 中国科学院合肥物质科学研究院 Load self-adaptive high-efficiency pulse constant current source and control method

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