A bridge circuit switch device on-off state detection circuit

Abstract

The present invention discloses a bridge circuit switch device on-off state detection circuit, including: a voltage divider circuit divides the DC voltage and each bridge arm midpoint voltage; a voltage comparison circuit compares each bridge arm voltage division with a first DC reference voltage and a second DC reference voltage obtained by dividing the current DC voltage to generate a comparison result; a judgment module sends a drive signal to the corresponding switch device; the drive signal is compared with the corresponding comparison result, and when the drive signal is different from the corresponding comparison result, a corresponding switch device locking signal is generated. The voltage divider circuit of the present invention divides the current DC voltage and each bridge arm midpoint voltage, the voltage comparison circuit compares the obtained two DC reference voltages with each bridge arm midpoint voltage division, the judgment module compares the drive signal and the comparison result, and when the two are different, the switch device is locked, thereby effectively and accurately detecting the on-off state of each switch device.

Description

Technical Field

[0001] The invention relates to the technical field of power electronics, and in particular to an on-off state detection circuit for a bridge circuit switch device. Background Art

[0002] In the prior art, the fully controlled three-phase bridge circuit is mostly composed of switching devices such as MOSFET, IGBT, and triode, which are mainly used in motor drivers, inverters, controlled rectifiers and other products. They are the main circuit power devices in these controllers and are also key components. In order to protect the safe and reliable operation of the switching devices in the bridge circuit, the on-off status of the switching devices in the upper and lower bridges must be detected in real time. The current detection methods are as follows: (1) using a dedicated integrated drive module to determine whether it is reliably turned on by detecting the on-voltage drop of the switching device. It can only be detected when it is turned on, and the cost is relatively high; (2) using a current transformer to detect the output or input current of the bridge circuit. When it is greater than the set current value, the protection circuit is shut down. This method is only suitable for short-circuit state judgment and cannot effectively and accurately detect the on-off state of each switching device. Summary of the invention

[0003] Therefore, the technical problem to be solved by the present invention is to overcome the defect in the prior art that the on-off state of each switch device in the bridge circuit cannot be effectively and accurately detected, thereby providing an on-off state detection circuit for the switch devices in the bridge circuit.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] In a first aspect, an embodiment of the present invention provides a bridge circuit switch device on-off state detection circuit, the bridge circuit includes multiple bridge arms, each bridge arm is composed of an upper bridge arm and a lower bridge arm, each upper bridge arm and each lower bridge arm includes a switch device, the switch device of the upper bridge arm of the same bridge arm is connected in series with the switch device of the lower bridge arm, the upper and lower output ends of each bridge arm are respectively connected to the positive DC bus and the negative DC bus, the lead wire of the midpoint of each bridge arm is connected to the AC motor, the detection circuit includes: a voltage divider circuit, a voltage comparison circuit and a judgment module, wherein the voltage divider circuit, its input end is respectively connected to the positive DC bus, the negative DC bus and the lead wire of the midpoint of each bridge arm, and its output end is connected to the voltage comparison circuit, for dividing the DC voltage and the voltage at the midpoint of each bridge arm , obtain the current DC voltage division and the voltage division of each bridge arm midpoint; the voltage comparison circuit, whose input end is connected to the voltage division circuit, and whose output end is connected to the judgment module, is used to divide the current DC voltage division to obtain the first DC reference voltage and the second DC reference voltage; the voltage division of each bridge arm midpoint is compared with the first DC reference voltage and the second DC reference voltage respectively to generate a comparison result; the judgment module, whose input end is connected to the voltage comparison circuit, and whose output end is connected to each switching device, is used to obtain the driving signal of each switching device and send it to the corresponding switching device; the driving signal of each switching device is compared with the corresponding comparison result, and when the driving signal of the switching device is different from the corresponding comparison result, the corresponding switching device locking signal is generated.

[0006] In one embodiment, the on-off state detection circuit of the bridge circuit switch device also includes: a driving circuit, which is respectively connected to the judgment module and each switch device, and is used to drive the corresponding switch device to be turned on and off according to the driving signal sent by the judgment module; and lock the corresponding switch device according to the locking signal of the switch device.

[0007] In one embodiment, the voltage divider circuit includes: a DC voltage divider circuit and multiple bridge arm midpoint voltage divider circuits, wherein the DC voltage divider circuit has a first end and a second end respectively connected to the positive DC bus and the negative DC bus, and is used to divide the current DC voltage to obtain the current DC voltage division; the first end of each bridge arm midpoint voltage divider circuit is connected to a lead-out line of a bridge arm midpoint, and the second end is connected to the negative DC bus, and is used to divide the DC voltage and each bridge arm midpoint voltage to obtain each bridge arm midpoint voltage division.

[0008] In one embodiment, a DC voltage divider circuit includes: a first voltage divider resistor and a first resistor string, wherein two ends of the first voltage divider resistor connected in series with the first resistor string are respectively connected to a positive DC bus and a negative DC bus, and a DC voltage divider lead line is led out from the midpoint of the connection line between the first voltage divider resistor and the first resistor string.

[0009] In one embodiment, each bridge arm midpoint voltage divider circuit includes: multiple second voltage divider resistors and multiple second resistor strings, wherein each second voltage divider resistor is connected in series with a second resistor string, and both ends are respectively connected to a lead wire of a bridge arm midpoint and a negative DC bus, and the midpoint of the connecting line between the second voltage divider resistor and the second resistor string leads to the bridge arm midpoint voltage divider lead wire.

[0010] In one embodiment, the voltage comparison circuit includes: a reference voltage generating circuit and multiple comparison circuits, wherein the reference voltage generating circuit has an input end respectively connected to a DC voltage dividing lead and a negative DC voltage bus, and an output end connected to an input end of each comparison circuit, for dividing a current DC voltage to obtain a first DC reference voltage and a second DC reference voltage; the input end of each comparison circuit is respectively connected to the reference voltage generating circuit and a bridge arm midpoint voltage dividing lead, and the output end is connected to a judgment module, for comparing the first DC reference voltage and the second DC reference voltage with the same bridge arm midpoint voltage divider, and generating a comparison result.

[0011] In one embodiment, the reference voltage generating circuit includes: three voltage-dividing resistors, wherein the first end of the three voltage-dividing resistors connected in series is connected to a DC voltage-dividing lead wire, the second end is connected to a negative DC bus, the other end of the voltage-dividing resistor connected to the DC voltage-dividing lead wire leads to a first DC reference voltage lead wire, and the other end of the voltage-dividing resistor connected to the negative DC bus leads to a second DC reference voltage lead wire.

[0012] In one embodiment, each bridge arm corresponds to a comparison circuit, and each comparison circuit includes:

[0013] A first operational comparator, whose non-inverting input terminal is connected to the second DC reference voltage lead-out line, whose inverting input terminal is connected to the bridge arm midpoint voltage divider lead-out line, and whose output terminal is connected to the bridge arm midpoint voltage divider circuit judgment module through a pull-up resistor; a second operational comparator, whose non-inverting input terminal is connected to the bridge arm midpoint voltage divider lead-out line, whose inverting input terminal is connected to the first DC reference voltage lead-out line, and whose output terminal is connected to the bridge arm midpoint voltage divider circuit judgment module through a pull-up resistor.

[0014] In one embodiment, the driving signals of the two switching devices in the same bridge arm are complementary, and a dead time is set; the first DC reference voltage and the second DC reference voltage are such that when the switching device of the upper bridge arm is turned on, the first operational comparator outputs a low level and the second operational comparator outputs a high level; and when the switching device of the upper bridge arm is turned off, the first operational comparator outputs a high level and the second operational comparator outputs a low level.

[0015] In one embodiment, the judgment module includes: a single chip microcomputer, which is used to compare the comparison result output by the first operational comparator of each comparison circuit with the driving signal of the switching device of the lower bridge arm of the corresponding bridge arm, and compare the comparison result output by the second operational comparator with the driving signal of the switching device of the upper bridge arm of the same bridge arm, and when the driving signal of the switching device is different from the corresponding comparison result, generate a corresponding switching device locking signal.

[0016] The technical solution of the present invention has the following advantages:

[0017] The present invention provides a bridge circuit switch device on-off state detection circuit, a voltage divider circuit divides the current DC voltage and the bridge arm midpoint voltage, a voltage comparison circuit divides the current DC voltage again to obtain two DC reference voltages with different amplitudes, and compares the two DC reference voltages with each bridge arm midpoint voltage, thereby outputting high and low levels, the high and low levels are used to indicate the current on-off state of the switch device, a judgment module compares the current drive signal of the switch device and the corresponding high and low levels, thereby judging whether the switch device is faulty, and when faulty, the corresponding switch device is locked, thereby effectively and accurately detecting the on-off state of each switch device, thereby improving the reliability of the bridge circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 A structural diagram of a bridge circuit provided by an embodiment of the present invention;

[0020] Figure 2 A composition diagram of a specific example of an on-off state detection circuit for a bridge circuit switch device provided by an embodiment of the present invention;

[0021] Figure 3 A composition diagram of another specific example of the on-off state detection circuit of the bridge circuit switch device provided by the embodiment of the present invention;

[0022] Figure 4 A composition diagram of another specific example of the on-off state detection circuit of the bridge circuit switch device provided by the embodiment of the present invention;

[0023] Figure 5 A composition diagram of a specific example of a voltage divider circuit based on a three-phase bridge circuit provided in an embodiment of the present invention;

[0024] Figure 6 A composition diagram of another specific example of the on-off state detection circuit of the bridge circuit switch device provided by the embodiment of the present invention;

[0025] Figure 7 A composition diagram of a specific example of a voltage comparison circuit based on a three-phase bridge circuit provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0026] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0028] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0030] Example

[0031] The embodiment of the present invention provides a bridge circuit switch device on-off state detection circuit, which is applied to occasions where the on-off state of the switch device needs to be detected in real time, such as Figure 1As shown, the bridge circuit of the embodiment of the present invention includes multiple bridge arms, each bridge arm is composed of an upper bridge arm and a lower bridge arm, each upper bridge arm and each lower bridge arm includes a switch device, the switch device of the upper bridge arm of the same bridge arm is connected in series with the switch device of the lower bridge arm, the upper and lower ends of each bridge arm are respectively connected to the positive DC bus DC+ and the negative DC bus DC-, the lead wire of the midpoint of each bridge arm is connected to the AC motor, the switch device of the embodiment of the present invention can be IGBT, MOSFET, etc., which is only used for example here, but not limited to this. In addition, the driving signals of the two switch devices in the same bridge arm are complementary, and a dead time is set.

[0032] like Figure 2 As shown, the detection circuit of the embodiment of the present invention includes: a voltage dividing circuit 1, a voltage comparison circuit 2 and a judgment module 3.

[0033] like Figure 2 As shown, the voltage divider circuit 1 of the embodiment of the present invention has its input end connected to the positive DC bus, the negative DC bus and the lead-out wires of each bridge arm midpoint respectively, and its output end connected to the voltage comparison circuit 2, which is used to divide the DC voltage and the voltage at the midpoint of each bridge arm to obtain the current DC voltage division and the voltage division of the midpoint of each bridge arm.

[0034] In the embodiment of the present invention, when the upper bridge arm switch device is turned on and the lower bridge arm switch device is turned off, the bridge arm midpoint voltage is slightly less than the positive DC bus voltage due to the conduction voltage drop of the switch device; when the upper bridge arm switch device is turned off and the lower bridge arm switch device is turned on, the bridge arm midpoint voltage is approximately equal to the negative DC bus voltage. In the process of the upper and lower bridge arms being alternately turned on, the embodiment of the present invention divides the current DC bus voltage in real time to obtain the current DC voltage division, and divides the bridge arm midpoint voltage to obtain each bridge arm midpoint voltage division.

[0035] like Figure 2 As shown, the voltage comparison circuit 2 of the embodiment of the present invention has its input end connected to the voltage divider circuit 1, and its output end connected to the judgment module 3, and is used to divide the current DC voltage to obtain a first DC reference voltage and a second DC reference voltage; divide the midpoint voltage of each bridge arm, and compare it with the first DC reference voltage and the second DC reference voltage respectively to generate a comparison result.

[0036] The voltage comparison circuit 2 of the embodiment of the present invention divides the current DC voltage to obtain reference voltages with different amplitudes, namely, a first DC reference voltage and a second DC reference voltage (the amplitude of the first DC reference voltage is greater than the amplitude of the second DC reference voltage), and then compares the two reference voltages with the divided voltage of the midpoint of each bridge arm, thereby detecting the current conduction state of the switching device, namely, the comparison result.

[0037] like Figure 2As shown, the judgment module 3 of the embodiment of the present invention has its input end connected to the voltage comparison circuit 2, and its output end connected to each switching device, for obtaining the driving signal of each switching device and sending it to the corresponding switching device; comparing the driving signal of each switching device with the corresponding comparison result, and generating a corresponding switching device locking signal when the driving signal of the switching device is different from the corresponding comparison result.

[0038] The judgment module 3 of the embodiment of the present invention sends a driving signal to the corresponding switching device. When the switching device is normal, the switching device is turned on or off according to the corresponding driving signal. However, since the switching frequency of the switching device in the bridge circuit is too high, the switching device may not be turned on or off normally. Therefore, the judgment module 3 compares the current driving signal with the comparison result generated by the voltage comparison circuit 2. When the two are different, the judgment module 3 sends a locking signal to control the switching device that is not turned on or off normally to be locked.

[0039] The embodiment of the present invention provides a bridge circuit switch device on-off state detection circuit, a voltage divider circuit divides the current DC voltage and the bridge arm midpoint voltage, the voltage comparison circuit divides the current DC voltage again to obtain two DC reference voltages with different amplitudes, and compares the two DC reference voltages with each bridge arm midpoint voltage, thereby outputting high and low levels, the high and low levels are used to indicate the current on-off state of the switch device, the judgment module compares the current drive signal of the switch device and the corresponding high and low levels, thereby judging whether the switch device is faulty, and when faulty, the corresponding switch device is locked, thereby effectively and accurately detecting the on-off state of each switch device, thereby improving the reliability of the bridge circuit.

[0040] In a specific embodiment, if Figure 3 As shown, the on-off state detection circuit of the bridge circuit switch device also includes:

[0041] The driving circuit 4 is connected to the judgment module 3 and each switch device respectively, and is used to drive the corresponding switch device to be turned on and off according to the driving signal sent by the judgment module 3; and to lock the corresponding switch device according to the switch device locking signal.

[0042] In a specific embodiment, if Figure 4 As shown, the voltage divider circuit 1 includes: a DC voltage divider circuit 11 and multiple bridge arm midpoint voltage divider circuits 12, wherein the DC voltage divider circuit 11 has a first end and a second end connected to the positive DC bus and the negative DC bus respectively, and is used to divide the current DC voltage to obtain the current DC voltage division; the first end of each bridge arm midpoint voltage divider circuit 12 is connected to the lead-out line of the midpoint of a bridge arm, and the second end is connected to the negative DC bus, and is used to divide the midpoint voltage of each bridge arm to obtain the midpoint voltage of each bridge arm.

[0043] The embodiment of the present invention provides two voltage-dividing circuits, one for dividing the current DC side voltage to obtain the current DC voltage division, and the other voltage-dividing circuit includes a plurality of small voltage-dividing circuits, each bridge arm corresponds to a small voltage-dividing circuit, and the two ends of each small voltage-dividing circuit are respectively connected to the lead-out wire of a bridge arm midpoint and the negative DC bus, and are used to divide the bridge arm midpoint voltage to obtain the corresponding bridge arm midpoint voltage division.

[0044] In a specific embodiment, the DC voltage divider circuit 11 includes: a first voltage divider resistor and a first resistor string, wherein the two ends of the first voltage divider resistor connected in series with the first resistor string are respectively connected to the positive DC bus and the negative DC bus, and a DC voltage divider lead line is led out from the midpoint of the connection line between the first voltage divider resistor and the first resistor string.

[0045] Specifically, Figure 5 As shown, taking a three-phase bridge circuit as an example, a DC voltage divider circuit 11 is composed of R7 and R8 in series, wherein R7 is a first resistor string, and R8 is a first voltage divider resistor (wherein the number of resistors and the resistance value required for R7 are different depending on the bus voltage level), and the two ends of R7 and R8 in series are connected to the positive and negative DC busbars, and a DC voltage divider lead-out line is drawn out from the midpoint of the connecting line of R7 and R8, which is used to draw out the current DC voltage divider VDC.

[0046] In a specific embodiment, each bridge arm midpoint voltage divider circuit 12 includes: multiple second voltage divider resistors and multiple second resistor strings, wherein each second voltage divider resistor is connected in series with a second resistor string, and both ends are respectively connected to a lead wire of a bridge arm midpoint and a negative DC bus, and the midpoint of the connecting line between the second voltage divider resistor and the second resistor string leads to the bridge arm midpoint voltage divider lead wire.

[0047] Specifically, Figure 5 As shown, R1 and R2 are connected in series to form a bridge arm midpoint voltage divider circuit 12 of the U phase bridge arm, R3 and R4 are connected in series to form a bridge arm midpoint voltage divider circuit of the V phase bridge arm, and R5 and R6 are connected in series to form a bridge arm midpoint voltage divider circuit of the W phase bridge arm. A bridge arm voltage divider lead-out line is set on the midline of each small voltage divider circuit to lead out the bridge arm midpoint voltage dividers V1, V2, and V3 corresponding to the U phase, V phase, and W phase, respectively, wherein R2, R4, and R6 are the second voltage divider resistors, R1, R3, and R5 are the second resistor string, and R1, R3, and R5 are all composed of multiple resistors, wherein the number and resistance value of the resistors are selected according to actual conditions.

[0048] In a specific embodiment, if Figure 6 As shown, the voltage comparison circuit 2 includes: a reference voltage generation circuit 21 and a plurality of comparison circuits 22 .

[0049] like Figure 6As shown, the reference voltage generating circuit 21 of the embodiment of the present invention has its input end connected to the DC voltage dividing lead and the negative DC voltage bus respectively, and its output end connected to the input end of each comparison circuit 22, and is used to divide the current DC voltage to obtain a first DC reference voltage and a second DC reference voltage.

[0050] like Figure 6 As shown, the input end of each comparison circuit 22 of the embodiment of the present invention is respectively connected to the reference voltage generating circuit 21 and a bridge arm midpoint voltage divider lead wire, and the output end is connected to the judgment module 3, which is used to compare the first DC reference voltage and the second DC reference voltage with the same bridge arm midpoint voltage divider, and generate a comparison result.

[0051] The reference voltage generating circuit 21 of the embodiment of the present invention divides the current DC voltage again, thereby obtaining two DC reference voltages with different amplitudes, namely, a first DC reference voltage and a second DC reference voltage. A plurality of comparison circuits 22 are provided, each comparison circuit 22 includes two operational comparators, wherein the non-inverting input terminal of one operational comparator is connected to the second DC reference voltage, and the inverting input terminal is connected to the voltage dividing lead wire of the midpoint of one of the phase bridge arms, and the inverting input terminal of the other operational comparator is connected to the first DC reference voltage, and the inverting input terminal is connected to the voltage dividing lead wire of the midpoint of the same phase bridge arm, wherein the first DC reference voltage and the second DC reference voltage make the first operational comparator output a low level and the second operational comparator output a high level when the switch device of the upper bridge arm is turned on; and make the first operational comparator output a high level and the second operational comparator output a low level when the switch device of the upper bridge arm is turned off and the lower bridge arm is turned on.

[0052] In a specific embodiment, the reference voltage generating circuit 21 includes: three voltage-dividing resistors, wherein the first end of the three voltage-dividing resistors connected in series is connected to a DC voltage-dividing lead wire, the second end is connected to a negative DC bus, the other end of the voltage-dividing resistor connected to the DC voltage-dividing lead wire leads to a first DC reference voltage lead wire, and the other end of the voltage-dividing resistor connected to the negative DC bus leads to a second DC reference voltage lead wire.

[0053] Each bridge arm corresponds to a comparison circuit 22, and each comparison circuit 22 includes:

[0054] A first operational comparator, whose non-inverting input terminal is connected to the second DC reference voltage lead-out line, whose inverting input terminal is connected to the bridge arm midpoint voltage divider lead-out line, and whose output terminal is connected to the bridge arm midpoint voltage divider circuit judgment module 3 through a pull-up resistor; a second operational comparator, whose non-inverting input terminal is connected to the bridge arm midpoint voltage divider lead-out line, whose inverting input terminal is connected to the first DC reference voltage lead-out line, and whose output terminal is connected to the bridge arm midpoint voltage divider circuit judgment module 3 through a pull-up resistor.

[0055] Specifically, Figure 7 As shown, taking the detection of the on-off state of the switch device of the three-phase bridge circuit as an example, R9, R10 and R11 are connected in series to form a reference voltage generating circuit, one end of R9 is connected to the DC voltage dividing lead wire, and the other end leads to a first DC reference voltage lead wire, one end of R11 is connected to the negative DC bus, and the other end leads to a second DC reference voltage lead wire, that is, the current DC voltage dividing voltage VDC and the negative DC bus DC- are applied to both ends of the reference voltage generating circuit, and the first DC reference voltage VDC-H is obtained by voltage dividing by R9, and the second DC reference voltage VDC-L is obtained by voltage dividing by R11, wherein the amplitude of the first DC reference voltage VDC-H is greater than the amplitude of the second DC reference voltage VDC-L.

[0056] In the embodiment of the present invention, each comparison circuit 22 is composed of two operational comparators, and one bridge arm corresponds to one comparison circuit 22, that is, Figure 7 As shown, taking the detection of the on-off state of the switch device of the three-phase bridge circuit as an example, U2B and U2A, U1C and U1D, U1B and U1A respectively constitute a comparison circuit, wherein U2B and U2A correspond to the U-phase bridge arm, U1C and U1D correspond to the V-phase bridge arm, and U1B and U1A correspond to the W-phase bridge arm. In each comparison circuit, the bridge arm midpoint voltage divided voltage V1, V2, V3 is compared with the amplitude of the first DC reference voltage VDC-H and the second DC reference voltage VDC-L respectively.

[0057] It should be noted that the embodiment of the present invention uses the judgment basis as a preset condition, and sets the resistance value of each voltage-dividing resistor after a large number of tests on the bridge circuit. Specifically, Figure 5 In the method for setting the amplitude of the first DC reference voltage and the second DC reference voltage obtained by the voltage division of each voltage divider resistor, the following three conditions need to be met: (1) The amplitude of the first DC reference voltage is greater than the amplitude of the second DC reference voltage. (2) When the driving signal of G1 is high and the driving signal of G2 is low (G1 is turned on and G2 is turned off), V1 is greater than the first DC reference voltage VDC-H and greater than the second DC reference voltage VDC-L, U2A outputs a low level, U2B outputs a high level, the output signal of U2A is the same as the driving signal of G2, and the output signal of U2B is the same as the driving signal of G1. (3) When the driving signal of G1 is low and the driving signal of G2 is high (G1 is turned off and G2 is turned on), V1 is less than the first DC reference voltage VDC-H and less than the second DC reference voltage VDC-L, U2A outputs a high level, U2B outputs a low level, the output signal of U2A is the same as the driving signal of G2, and the output signal of U2B is the same as the driving signal of G1.

[0058] Therefore, through the above method of setting the amplitudes of the first DC reference voltage and the second DC reference voltage, the comparison results output by the two operational comparators of each comparison circuit 22 correspond to the driving signal of the upper bridge arm or the driving signal of the lower bridge arm.

[0059] In a specific embodiment, the judgment module 3 includes: a single chip microcomputer, which is used to compare the comparison result output by the first operational comparator of each comparison circuit 22 with the driving signal of the switching device of the lower bridge arm of the corresponding bridge arm, and compare the comparison result output by the second operational comparator with the driving signal of the switching device of the upper bridge arm of the same bridge arm, and when the driving signal of the switching device is different from the corresponding comparison result, generate a corresponding switching device locking signal.

[0060] It should be noted that the judgment module 3 in the embodiment of the present invention is not limited to a single chip microcomputer, but may also be other processing chips or logic comparison circuits. This is only an example, but not a limitation.

[0061] The embodiment of the present invention provides a bridge circuit switch device on-off state detection circuit, a voltage divider circuit divides the current DC voltage and the bridge arm midpoint voltage, the voltage comparison circuit divides the current DC voltage again to obtain two DC reference voltages with different amplitudes, and compares the two DC reference voltages with each bridge arm midpoint voltage, thereby outputting high and low levels, the high and low levels are used to indicate the current on-off state of the switch device, the judgment module compares the current drive signal of the switch device and the corresponding high and low levels, thereby judging whether the switch device is faulty, and when faulty, the corresponding switch device is locked, thereby effectively and accurately detecting the on-off state of each switch device, thereby improving the reliability of the bridge circuit.

[0062] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the scope of protection of the invention.

Claims

1. A bridge circuit switch device on-off state detection circuit, characterized in that: The bridge circuit includes a plurality of bridge arms, each bridge arm is composed of an upper bridge arm and a lower bridge arm, each upper bridge arm and each lower bridge arm includes a switch device, the switch device of the upper bridge arm of the same bridge arm is connected in series with the switch device of the lower bridge arm, the upper and lower ends of each bridge arm are respectively connected to the positive DC bus and the negative DC bus, and the lead wire of the midpoint of each bridge arm is connected to the AC motor, the detection circuit includes: a voltage divider circuit, a voltage comparison circuit, a drive circuit and a judgment module, wherein, A voltage divider circuit, whose input end is respectively connected to the positive DC bus, the negative DC bus and the lead-out wires of each bridge arm midpoint, and whose output end is connected to the voltage comparison circuit, is used to divide the DC voltage and the voltage at the midpoint of each bridge arm to obtain the current DC voltage division and the voltage division of the midpoint of each bridge arm; A voltage comparison circuit, whose input end is connected to the voltage divider circuit and whose output end is connected to the judgment module, is used to divide the current DC voltage to obtain a first DC reference voltage and a second DC reference voltage; divide the voltage of the midpoint of each bridge arm, and compare it with the first DC reference voltage and the second DC reference voltage respectively to generate a comparison result; A judgment module, whose input end is connected to the voltage comparison circuit and whose output end is connected to each switch device, is used to obtain the driving signal of each switch device and send it to the corresponding switch device; compare the driving signal of each switch device with the corresponding comparison result, and generate a corresponding switch device locking signal when the driving signal of the switch device is different from the corresponding comparison result; A driving circuit, connected to the judgment module and each switch device, respectively, for driving the corresponding switch device to be turned on and off according to the driving signal sent by the judgment module; and locking the corresponding switch device according to the switch device locking signal; The voltage divider circuit includes: a DC voltage divider circuit and a plurality of bridge arm midpoint voltage divider circuits, wherein the DC voltage divider circuit has a first end and a second end connected to the positive DC bus and the negative DC bus, respectively, and is used to divide the current DC voltage to obtain the current DC voltage; the first end of each bridge arm midpoint voltage divider circuit is connected to a lead-out line of a bridge arm midpoint, and the second end is connected to the negative DC bus, and is used to divide the voltage of each bridge arm midpoint to obtain the voltage of each bridge arm midpoint; The DC voltage-dividing circuit comprises: a first voltage-dividing resistor and a first resistor string, wherein two ends of the first voltage-dividing resistor connected in series with the first resistor string are respectively connected to the positive DC bus and the negative DC bus, and a DC voltage-dividing lead wire is led out from the midpoint of the connection line between the first voltage-dividing resistor and the first resistor string; Each bridge arm midpoint voltage divider circuit comprises: a plurality of second voltage divider resistors and a plurality of second resistor strings, wherein each second voltage divider resistor is connected in series with a second resistor string, and both ends are connected to a bridge arm midpoint lead wire and a negative DC bus respectively, and a bridge arm midpoint voltage divider lead wire is led out from a midpoint of the connection line between the second voltage divider resistor and the second resistor string; The voltage comparison circuit comprises: a reference voltage generation circuit and a plurality of comparison circuits, wherein the reference voltage generation circuit has an input end connected to the DC voltage division lead wire and the negative DC voltage bus respectively, and an output end connected to the input end of each comparison circuit, and is used to divide the current DC voltage to obtain a first DC reference voltage and a second DC reference voltage; the input end of each comparison circuit is connected to the reference voltage generation circuit and a bridge arm midpoint voltage division lead wire respectively, and the output end is connected to the judgment module, and is used to compare the first DC reference voltage and the second DC reference voltage with the same bridge arm output voltage division, and generate a comparison result; The reference voltage generating circuit comprises: three voltage-dividing resistors, wherein the first end of the three voltage-dividing resistors connected in series is connected to the DC voltage-dividing lead-out line, the second end is connected to the negative DC bus, the other end of the voltage-dividing resistor connected to the DC voltage-dividing lead-out line leads to a first DC reference voltage lead-out line, and the other end of the voltage-dividing resistor connected to the negative DC bus leads to a second DC reference voltage lead-out line; Each bridge arm corresponds to a comparison circuit, and each comparison circuit includes: a first operational comparator, whose in-phase input terminal is connected to the second DC reference voltage lead-out line, whose inverting input terminal is connected to the bridge arm midpoint voltage divider lead-out line, and whose output terminal is connected to the judgment module through a pull-up resistor; a second operational comparator, whose in-phase input terminal is connected to the bridge arm midpoint voltage divider lead-out line, whose inverting input terminal is connected to the first DC reference voltage lead-out line, and whose output terminal is connected to the judgment module through a pull-up resistor; The driving signals of the two switching devices in the same bridge arm are complementary, and a dead time is set; the first DC reference voltage and the second DC reference voltage are such that when the switching device of the upper bridge arm is turned on, the first operational comparator outputs a low level and the second operational comparator outputs a high level; and when the switching device of the upper bridge arm is turned off, the first operational comparator outputs a high level and the second operational comparator outputs a low level.

2. The on-off state detection circuit of the bridge circuit switch device according to claim 1, characterized in that: The judging module comprises: A single chip microcomputer is used to compare the comparison result output by the first operational comparator of each comparison circuit with the driving signal of the switching device of the lower bridge arm of the corresponding bridge arm, and to compare the comparison result output by the second operational comparator with the driving signal of the switching device of the upper bridge arm of the same bridge arm, and to generate a corresponding switching device locking signal when the driving signal of the switching device is different from the corresponding comparison result.

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