High-side current collection and safety protection circuit for power electronic switch transistors

Abstract

The present invention provides a high-side current collection and safety protection circuit for a power electronic switch transistor, which includes a power electronic switch transistor for driving a load, a power power source for supplying power energy to the power electronic switch transistor, a control module for sensing a current source signal included in the power electronic switch transistor and converting the sensed current source signal into a control signal for performing safety protection for the power electronic switch transistor, and an isolated power source for providing an operating power source for the control module. The negative pole of the isolated power source is connected to the positive pole of the power source. The present invention has a simple structure, high reliability and low cost.

Description

[Technical field]

[0001] The present invention relates to the technical field of high-side driven power electronic switch transistor conduction current detection and power electronic switch transistor safety protection, in particular to a high-side current collection and safety protection circuit of a power electronic switch transistor. [Background technology]

[0002] There are three main methods for detecting the current of a high-side drive power electronic switch transistor: current loop type, Hall element type, and integrated circuit sensor type. The volume of the current loop type or Hall type current sensor is large, and the cost of the integrated circuit type current sensor is high.

[0003] At present, in order to reduce costs, it is common to place the sense resistor at a high position between the positive pole of the power supply voltage and the power electronic switch transistor, and amplify the signal using an operational amplifier to realize current detection. However, since the common mode voltage of the sense amplifier is close to the power supply voltage, such a wide range of common mode voltage requires the operational amplifier to have high common mode characteristics, which increases the cost.

[0004] Therefore, it is important to reduce the cost of current detection and protection of power electronic switch transistors when they are used in large numbers, such as in automobiles. Summary of the Invention

[0005] SUMMARY OF THE PRESENT EMBODIMENTS The present invention aims to provide a current collection circuit and safety protection circuit for a high side power electronic switch transistor that is simple in structure and relatively low in cost.

[0006] To achieve the above objectives, the present invention uses the following technical solutions:

[0007] 1. A high side current collection and safety protection circuit for a power electronic switch transistor, comprising: a power electronic switch transistor for driving a load; a power supply for providing power energy to the power electronic switch transistor; a control module for sensing a current source signal included in the power electronic switch transistor and converting the sensed current source signal into a control signal that implements safety protection for the power electronic switch transistor; and an isolated power supply for providing operating power to the control module, the negative terminal of the isolated power supply being connected to the positive terminal of the power supply.

[0008] Furthermore, the input terminal of the power electronic switch transistor is connected to a power source VP, and the output terminal is connected to a load. The power electronic switch transistor includes an insulated gate electrode MOSFET and an IGBT.

[0009] Furthermore, the control module includes a logic control unit, a signal conditioning unit for converting a current source signal of a power electronic switch transistor, and a drive conditioning unit for converting a safety protection control signal inputted by the logic control unit.

[0010] Further, the signal conditioning unit includes a resistor R2, a resistor R3, and a reference power supply VW. One end of the resistor R2 is connected to the source electrode of the power electronic switch transistor, and the other end is connected to one end of the resistor R3. The other end of the resistor R3 is connected to the reference power supply VW. The reference power supply VW is an independent power supply or a voltage source output by a D / A converter in the logic control unit.

[0011] Further, the signal conditioning unit includes a resistor R4, a resistor R5, a resistor R6, and an operational amplifier OP. One end of the resistor R4 is connected to the drain electrode of the power electronic switch transistor, and the other end is connected to the positive electrode of the operational amplifier OP. One end of the resistor R5 is connected to the source electrode of the power electronic switch transistor, and the other end is connected to the negative electrode of the operational amplifier OP. One end of the resistor R6 is connected to the negative electrode of the operational amplifier OP, and the other end is connected to the output end of the operational amplifier OP.

[0012] Furthermore, the output port IO-1 of the logic control unit is connected to the command input port CIN of the drive adjusting unit. The output port OUT of the drive adjusting unit is connected to the control end TG of the power electronic switch transistor 1, and the control end TG is connected to the gate electrode of the power electronic switch transistor via a resistor R1. The input signal of the input port CIN of the drive adjusting unit is a logic level signal, and the output signal of the output port OUT of the drive adjusting unit is a level signal for driving the power electronic switch transistor. This level signal is used to control the conduction of the MOSFET in the power electronic switch transistor.

[0013] Further, the logic control unit includes an A / D converter, a digital logic comparator and a digital threshold level unit. The input of the A / D converter is the output of the signal conditioning unit. The logic control unit is used for protecting a power electronic switch transistor. A first input terminal of the digital logic comparator is connected to the output conversion result of the A / D converter, a second input terminal is connected to the configurable digital threshold level unit, and an output of the digital logic comparator is connected to the input CIN terminal of the drive conditioning unit. The digital logic comparator includes a virtual digital logic comparator realized by arithmetic logic, or a digital logic comparator configured by software.

[0014] Furthermore, the logic control unit further includes an analog logic comparator, a first input terminal of the analog logic comparator is connected to the output terminal of the signal conditioning circuit, a second input terminal of the analog logic comparator is connected to a settable analog threshold level, and an output terminal of the analog logic comparator is connected to the input CIN terminal of the drive conditioning unit.

[0015] Furthermore, the outputs of the digital logic comparator and the analog logic comparator are both connected to the output terminal IO-1 of the logic control unit, and the logic control unit performs a logical AND operation on the outputs of the digital logic comparator and the analog logic comparator, and then outputs the logical AND operation to the CIN input terminal of the drive adjustment unit.

[0016] Furthermore, the isolated power supply includes a DC / DC isolated power supply, the negative terminal of the isolated power supply being connected to the positive terminal of the power supply through at least one diode.

[0017] Industrial Applicability (1) The current sensor signal source in the present invention is obtained from the internal resistance of the power electronic switch transistor, which eliminates the need for an additional sensor, thereby reducing the size and cost. (2) The method of connecting the isolated power supply and the power supply of the present invention provides a safe power supply for the conductive operation and safety protection of the MOSFET, thereby improving the reliability of the power electronic switch transistor. (3) The present invention organically combines a control module, an isolated power supply and a power electronic switch transistor to form an intelligent electronic switch mechanism with safety protection and current detection. The structure of the logic control unit and the current source signal conditioning circuit is simple, the logic line is short, and it is easy to implement. (4) The present invention upgrades the ordinary electronic switch transistor to an intelligent electronic switch transistor with safety protection and current detection, which has a simple structure, high reliability, low cost and wide application range. The present invention provides a high-side current collection and safety control circuit of a power electronic switch transistor with a simple structure and low performance requirements, thereby ensuring reliable performance and at the same time reducing the volume and cost of the system constituted by the present invention. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic diagram showing the circuit principle of the first embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram of the circuit principle according to the second embodiment of the present invention. [Diagram 3] FIG. 3 is a schematic diagram of the circuit principle according to the third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

[0020] The high side current collection and safety protection circuit of a power supply switch transistor shown in FIG. 1 includes a power electronic switch transistor 1 for driving a load 2, a power supply for supplying power energy to the power electronic switch transistor, a control module 3 for sensing a current source signal included in the power electronic switch transistor and converting the sensed current source signal into a control signal that performs safety protection for the power electronic switch transistor, and an isolated power supply 4 for providing an operating power source to the control module.

[0021] The power input terminal of the power electronic switch transistor 1 in this preferred embodiment is connected to the power supply VP, and the output terminal is connected to the load 2. The other terminal of the load is connected to the ground of the power supply. The power electronic switch transistor 1 includes an insulated gate electrode MOSFET and an IGBT. The current sensor signal source in the present invention is obtained from the internal resistance of the power electronic switch transistor 1, and an additional sensor can be omitted. The isolated power supply 4 includes a DC / DC isolated power supply driven by the power supply, and the negative pole of the isolated power supply 4 is connected to the positive pole of the power supply. In the present invention, the positive pole of the power supply is set to the reference ground level of the control module 3, which simplifies the signal conditioning circuit 32 and the logic control unit 31 and reduces the requirements of the control system on the circuit performance.

[0022] Specifically, the control module 3 includes a logic control unit 31, a signal conditioning unit 32 for converting the current source signal of the power electronic switch transistor so as to meet the requirement of the logic control unit A / D sampling level signal, and a drive conditioning unit 33 for converting the safety protection control signal input by the logic control unit so as to meet the requirement of the level signal for driving the power electronic switch transistor to turn off or on. The logic control unit 31 includes a single-chip microcomputer, a CPLD and an FPGA.

[0023] As a preferred embodiment, the implementation method of the signal conditioning unit described in this embodiment is as follows.

[0024] <Embodiment 1> This is realized by the signal conditioning unit 32 being a bias resistor. As shown in FIG. 1, the power electronic switch transistor 1 is an N-type MOSFET, and the signal conditioning unit 32 includes a resistor R2, a resistor R3, and a reference power supply VW. One end of the resistor R2 is connected to the source electrode of the power electronic switch transistor 1, and the other end is connected to one end of the resistor R3. The other end of the resistor R3 is connected to the reference power supply VW. The reference power supply VW is an independent power supply or a voltage source output by a D / A converter in the logic control unit 31. The logic control unit 31 is provided with an A / D converter connected to the other end of the resistor R2 and a D / A converter connected to the other end of the resistor R3. The output port IO-1 of the logic control unit 31 is connected to the command input port CIN of the drive adjustment unit 33. The output port OUT of the drive adjustment unit 33 is connected to the control end TG, and the control end TG is connected to the gate electrode of the power electronic switch transistor 1 via the resistor R1. The input signal CIN of the drive adjusting unit 33 is a logic level signal, and the output signal OUT of the drive adjusting unit 33 is a level signal that drives the power electronic switch transistor 1. This level signal can control the conduction and closing of the MOSFET.

[0025] The working principle of the high side current collection of the power electronic switch transistor is as follows.

[0026] The conduction resistance between the drain electrode and the source electrode of the power electronic switch transistor 1 is RON, and when the power electronic switch transistor 1 is conducting, a voltage difference signal VDS=IA*RON is generated at the resistance by the current IA. This voltage difference signal VDS is connected to the VI+ and VI- terminals of the signal conditioning unit 32 as the current source signal of the power electronic switch transistor 1. Since the level of the source electrode of the power electronic switch transistor 1 is lower than the level of the drain electrode and presents a negative level signal to the A / D converter of the logic control unit 31, it needs to be connected to a forward bias circuit. The forward bias circuit is composed of an independent stabilized voltage source VW, resistor R2, and resistor R3. The forward bias circuit makes the VDS voltage at the input terminal of the A / D converter a positive level signal. The calculation formula for the voltage at the connection point of resistors R2 and R3 is as follows: VIA=(R2*VW-R3*VI-) / (R2+R3); In the specific implementation process, (R2*VW-R3*VI-)>0.

[0027] The working principle of the above-mentioned high side current safety protection of the power electronic switch transistor is as follows.

[0028] A safety protection current threshold (the reference number is omitted in the drawings) is preset for the threshold unit VIG of the logic control unit 31, and when the A / D sampling current value of the logic control unit 31 is compared by software and is greater than the set current threshold VIG, the control port BD1 of the logic control unit 31 outputs an OFF signal at the output port IO-1. This OFF signal is converted by the drive adjustment unit 33 and output from the OUT port, which turns off the power electronic switch transistor 1, thereby protecting the safety of the power electronic switch transistor.

[0029] At the same time, the A / D sampled current value can be read and used by another externally connected unit or system (examples and explanations of specific circuit types are omitted).

[0030] <Embodiment 2> This is realized by the signal conditioning unit 32 being an operational amplifier. As shown in Fig. 2, the signal conditioning unit 32 includes a resistor R4, a resistor R5, a resistor R6, and an operational amplifier OP. One end of the resistor R4 is connected to the drain electrode of the power electronic switch transistor 1, and the other end is connected to the positive electrode of the operational amplifier OP. One end of the resistor R5 is connected to the source electrode of the power electronic switch transistor 1, and the other end is connected to the negative electrode of the operational amplifier OP. One end of the resistor R6 is connected to the negative electrode of the operational amplifier OP, and the other end is connected to the output end of the operational amplifier OP.

[0031] The working principle of the high side current collection of the power electronic switch transistor is as follows.

[0032] The conduction resistance between the drain electrode and the source electrode of the power electronic switch transistor 1 is RON. When the power electronic switch transistor 1 is conducting, a voltage difference signal VDS=IA*RON is generated at the resistance by the current IA. This voltage difference signal VDS is connected to the VI+ and VI- terminals of the signal conditioning unit 32 as the current source signal of the power electronic switch transistor 1. The signal conditioning unit 32 has an operational amplifier OP built in. The output voltage of the operational amplifier OP is VIA, and the voltage calculation formula for the output voltage VIA is as follows: VIA=(VI+ - VI-)*(R6 / R5); When the operational amplifier OP of the signal conditioning unit 32 is powered by a single power supply, the negative signal received at its VI- input terminal will distort the amplified output. In order to make the signal at the VI- terminal a positive signal, the negative output terminal VP of the isolated power supply 4 is connected in series with one or more diodes and then connected to the positive terminal of the power supply VP. Since the conduction resistance of the power electronic switch transistor 1 is generally several milliohms, the voltage that the load current forms across its internal resistance is generally lower than the forward conduction voltage of the diode (the forward conduction voltage of the diode is about 0.6V). After the diode is connected in series, the ground level VPP of the control module 3 is lower than VP, so the signal received by the operational amplifier at its negative terminal is a positive polarity signal.

[0033] The safety protection circuit and principle of this embodiment are similar to those of the first embodiment.

[0034] <Embodiment 3> Based on the second embodiment, one analog comparator is added to the logic control unit 31. Other parts are the same as the second embodiment.

[0035] Specifically, as shown in FIG. 3, the logic control unit 31 includes an analog comparator ACOMP made of discrete elements and a digital comparator DCOMP made of a digital logic unit. The negative terminal of the analog comparator is connected to the output terminal of the operational amplifier OP1, and the positive terminal is connected to the analog comparison threshold setting unit AVIG. The negative terminal of the digital comparator DCOMP is connected to the output terminal of the A / D converter, and the positive terminal is connected to the digital comparison threshold unit DVIG. The port IO-1 is in a logical AND relationship with the output port of the analog comparator ACOMP and the output port of the digital comparator DCOM. That is, whichever comparator outputs a logical OFF signal, the port IO-1 outputs a logical OFF signal. The input signal CIN of the drive adjustment unit is a logical level signal, and the output signal OUT of the drive unit is a level signal that drives the power electronic switch transistor 1. This level signal can turn off the conduction of the MOSFET.

[0036] The operating principle of the current collecting circuit of this embodiment is the same as that of the second embodiment.

[0037] The working principle of the analog comparator ACOMP outputting the OFF logic signal is as follows: The logic control unit 31 presets a current threshold for the threshold unit AVIG of the analog comparator ACOMP, and when the value VIA level value of the output terminal of the operational amplifier is greater than the preset current threshold AVIG, the comparator ACOMP outputs a signal to turn off the power electronic switch transistor 1.

[0038] The working principle of the digital comparator DCOM outputting the OFF logic signal is as follows: The logic control unit 31 presets a current threshold for the threshold unit DVIG of the digital comparator DCOMP, and when the output of the A / D converter is greater than the preset current threshold DVIG, the comparator DCOMP outputs a signal to turn off the power electronic switch transistor 1.

[0039] Since the output of the digital comparator DCOMP is controlled only by software, the digital comparator DCOMP can be set to different output control logic.

[0040] In practical application, when the current passing through the load is greater than the set current threshold DVIG and the electronic switch transistor needs to be protected, it can be made into two steps.

[0041] (1) A level signal VIA applied to the negative terminal of the analog comparator ACOMP causes the analog comparator ACOMP to output an OFF signal. (2) At the same time, the control logic outputs the overload current value collected by the A / D converter to the negative terminal of the digital comparator DCOMP, causing the digital comparator DCOMP to output an off signal.

[0042] Since the output port IO-1 and the two comparators are in a logical AND relationship, any off signal will cause the logical output port IO-1 to output an off signal to the input port CIN of the drive adjustment unit 33, turning off the power electronic switch transistor 1. The digital comparator DCOMP is controlled by software, and in the software logic, when the digital comparator DCOMP outputs an off signal, this off logic is maintained. That is, no matter how the value of its input port applied by the A / D converter changes, the power electronic switch transistor 1 will not be conductive until the logic control unit 31 receives another external signal to turn on the power electronic switch transistor.

[0043] The above embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Any modifications and improvements made by those skilled in the art to the technical solutions of the present invention should fall within the scope of protection of the claims of the present invention, provided that they do not deviate from the design spirit of the present invention. [Explanation of symbols]

[0044] 1 - power electronic switch transistor, 2 - load, 3 - control module, 31 - logic control unit, 32 - signal conditioning unit, 33 - drive conditioning unit, 4 - isolated power supply.

Claims

1. 1. A high side current collection and safety protection circuit for a power electronic switch transistor, comprising: A power electronic switch transistor (1) for driving a load (2); a power supply for providing power energy to the power electronic switch transistor; a control module (3) for sensing a current source signal of the power electronic switch transistor and converting the sensed current source signal into a control signal for implementing safety protection for the power electronic switch transistor; and an isolated power supply (4) for providing an operating power supply to the control module, the negative terminal of the isolated power supply being connected to the positive terminal of the power supply.

2. 2. The high side current collection and safety protection circuit of claim 1, wherein the power electronic switch transistor (1) has an input terminal connected to a power supply VP and an output terminal connected to a load, and the power electronic switch transistor (1) includes one of an insulated gate electrode MOSFET and an IGBT.

3. 3. The high side current collection and safety protection circuit of a power electronic switch transistor as claimed in claim 2, wherein the control module (3) includes: a logic control unit (31); a signal conditioning unit (32) for converting a voltage of a current source signal of the power electronic switch transistor so as to meet the requirement of the logic control unit; and a drive conditioning unit (33) for converting a safety protection control signal input by the logic control unit into a level signal for driving the power electronic switch transistor so as to meet the requirement of driving a power battery switch transistor.

4. 4. The high side current collecting and safety protection circuit of the power electronic switch transistor of claim 3, wherein the signal conditioning unit (32) comprises: a resistor R2, a resistor R3 and a reference power source VW, one end of the resistor R2 is connected to the source electrode of the power electronic switch transistor, the other end is connected to one end of the resistor R3, and the other end of the resistor R3 is connected to the reference power source VW, and the reference power source VW is an independent power source or a voltage source that outputs a voltage by a D / A converter in a logic control unit.

5. 4. The high-side current collection and safety protection circuit of a power electronic switch transistor as claimed in claim 3, wherein the signal conditioning unit (32) comprises: a resistor R4, a resistor R5, a resistor R6 and an operational amplifier OP, one end of the resistor R4 is connected to the drain electrode of the power electronic switch transistor (1) and the other end is connected to the positive electrode of the operational amplifier OP, one end of the resistor R5 is connected to the source electrode of the power electronic switch transistor (1) and the other end is connected to the negative electrode of the operational amplifier OP, one end of the resistor R6 is connected to the negative electrode of the operational amplifier OP and the other end is connected to the output end of the operational amplifier OP.

6. 4. The high-side current collection and safety protection circuit of the power electronic switch transistor of claim 3, wherein the output port IO-1 of the logic control unit (31) is connected to a command input port CIN of a drive adjusting unit (33), the output port OUT of the drive adjusting unit (33) is connected to the gate electrode of the power electronic switch transistor (1) through a resistor R1, the input signal of the input port CIN of the drive adjusting unit (33) is a logic level signal, and the output signal of the output port OUT of the drive adjusting unit (33) is a level signal for driving the power electronic switch transistor, which level signal is used to control the conduction of the MOSFET in the power electronic switch transistor (1).

7. 7. The high side current collection and safety protection circuit of claim 6, wherein the logic control unit (31) includes an A / D converter, a digital logic comparator and a digital threshold level unit, an input of the A / D converter is an output of a signal conditioning unit (32), the logic control unit (31) is used for protecting a power electronic switch transistor, a first input end of the digital logic comparator is connected to an output conversion result of the A / D converter, a second input end is connected to a configurable digital threshold level unit, and an output of the digital logic comparator is connected to an input CIN end of a drive conditioning unit (33), and the digital logic comparator includes a virtual digital logic comparator realized by arithmetic logic or a digital logic comparator configured by software.

8. 8. The high side current collection and safety protection circuit of a power electronic switch transistor as claimed in claim 7, characterized in that the logic control unit (31) further includes an analog logic comparator, a first input end of the analog logic comparator is connected to an output end of a signal conditioning circuit (32), a second input end of the analog logic comparator is connected to a settable analog threshold level, and an output of the analog logic comparator is connected to an input CIN end of a drive conditioning unit (33).

9. The high side current collection and safety protection circuit of the power electronic switch transistor as claimed in claim 8, characterized in that the outputs of the digital logic comparator and the analog logic comparator are both connected to the output terminal IO-1 of the logic control unit (31), and the output terminal IO-1 of the logic control unit (31) is connected to the CIN input terminal of the drive adjustment unit (33), and the logic control unit (31) performs a logical AND operation on the outputs of the digital logic comparator and the analog logic comparator, and then outputs to the CIN input terminal of the drive adjustment unit (33).

10. 2. The high side current collection and safety protection circuit of a power electronic switch transistor according to claim 1, characterized in that the isolated power supply (4) comprises a DC / DC isolated power supply, and the negative terminal of the isolated power supply (4) is connected to the positive terminal of a power supply through at least one diode.

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