CN112269154A

CN112269154A - Fault diagnosis circuit of H bridge

Info

Publication number: CN112269154A
Application number: CN202011265425.7A
Authority: CN
Inventors: 方锦海; 郑鲲鲲
Original assignee: Guangdong Aohong Technology Co ltd
Current assignee: Guangdong Aohong Technology Co ltd
Priority date: 2020-11-13
Filing date: 2020-11-13
Publication date: 2021-01-26

Abstract

The invention discloses a fault diagnosis circuit of an H bridge, which comprises a comparator A1 and a comparator A2, wherein the in-phase input end of the comparator A1 is connected with one end of a motor coil through a field effect tube M9 and a resistor R5, the reverse phase input end of the comparator A2 is connected with the other end of the motor coil through a field effect tube M10 and a resistor R6, a resistor R3, a field effect tube M6 and a field effect tube M5 are connected between the motor coil and the resistor R6 in parallel, a resistor R4, a field effect tube M7 and a field effect tube M8 are connected between the motor coil and the resistor R5, the other end of the resistor R3 is connected with the field effect tube M6 and the field effect tube M5 in series and then is connected with a power supply VCC, one end of a resistor R4 is connected between the motor coil and the resistor R6, and the other end of the resistor R4 is connected with the field effect tube M7 and the field effect tube M86. The invention can detect the fault condition of the motor winding without using a sensor, thereby greatly improving the convenience and the accuracy of detection.

Description

Fault diagnosis circuit of H bridge

Technical Field

The invention relates to a fault diagnosis circuit of an H bridge, and belongs to the field of direct current motor control.

Background

The H-bridge is a typical dc motor control circuit that can be used for dc brushless motor control or multi-phase stepper motor control. When the motor works, the current flowing in the coil is generally noticed, the coil is prevented from being burnt out, and whether the connection between the driving circuit and the coil is normal or not is easily ignored. If one of the coils of the stepping motor is connected to fail, the stepping motor may lose step or even step in place when in operation. Therefore, the patent proposes a diagnostic circuit for an H-bridge in a closed state, which can detect a motor winding fault without using a sensor.

Disclosure of Invention

The invention aims to provide a diagnostic circuit of an H bridge in a closed state, which can detect the winding fault of a motor without using a sensor.

In order to achieve the purpose, the invention adopts the technical scheme that: a fault diagnosis circuit of an H bridge comprises a comparator A1 and a comparator A2, wherein the non-inverting input end of the comparator A1 is connected with one end of a motor coil through a field effect tube M9 and a resistor R5, the inverting input end of the comparator A2 is connected with the other end of the motor coil through a field effect tube M10 and a resistor R6, a resistor R3 is connected between the motor coil and the resistor R5 in parallel, a field effect tube M6 and a field effect tube M5 are connected between the motor coil and the resistor R6 in parallel, a resistor R4, a field effect tube M7 and a field effect tube M8 are connected between the motor coil and the resistor R5, the other end of the resistor R3 is connected with a power supply VCC after being connected with the field effect tube M6 and the field effect tube M5 in series in sequence, one end of a resistor R4 is connected between the motor coil and the resistor R6, and the other end of the resistor R7 and the field effect.

Furthermore, the gate of the fet M5 is used as an enable signal terminal, the source of the fet M5 is connected to the VCC, the drain of the fet M5 is connected to the drain of the fet M6, and the source of the fet M6 is connected to the resistor R3.

Furthermore, the gate of the fet M8 serves as an enable signal terminal, the source of the fet M8 is grounded, the drain of the fet M8 is connected to the source of the fet M7, and the drain of the fet M7 is connected to the drain connection resistor R4.

Further, the source of the field effect transistor M9 is connected to the non-inverting input terminal of the comparator a1, and the drain is connected to the resistor R5.

Further, the source of the field effect transistor M10 is connected to the inverting input terminal of the comparator a2, and the drain is connected to the resistor R6.

Furthermore, a voltage division branch circuit for providing reference voltage for the comparator is arranged between the power supply VCC end and the grounding end.

Further, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a resistor R10 and a field effect transistor M11 are connected in series to the voltage dividing branch, and by means of voltage division of the resistors, 3V voltage is correspondingly provided to the inverting input terminal of the comparator a1, and 2V voltage is provided to the non-inverting input terminal of the comparator a 2.

Further, the field-effect transistor M5, the field-effect transistor M6, and the field-effect transistor M7 are all P-channel MOS transistors, the field-effect transistor M8, the field-effect transistor M9, the field-effect transistor M10, and the field-effect transistor M11 are all N-channel MOS transistors, and parasitic diodes are arranged between the source and the drain of the field-effect transistor M6, the field-effect transistor M7, the field-effect transistor M9, and the field-effect transistor M10.

The invention has the beneficial effects that: the diagnosis circuit can detect the fault condition of the motor winding without using a sensor, greatly improves the convenience and accuracy of detection, and has a higher application prospect.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

Fig. 1 is a conventional bridge driver circuit.

Fig. 2 is a fault diagnosis circuit.

Fig. 3 is a fault diagnosis circuit with a voltage dividing branch.

Detailed Description

The invention is described in detail below with reference to the figures and specific embodiments.

As shown in fig. 2 and 3, a fault diagnosis circuit for an H bridge includes a comparator a1 and a comparator a2, a non-inverting input terminal of the comparator a1 is connected to one end of a motor coil through a fet M9 and a resistor R5, an inverting input terminal of the comparator a2 is connected to the other end of the motor coil through a fet M10 and a resistor R6, a resistor R3 is connected between the motor coil and the resistor R5 in parallel, a fet M6 and a fet M5 are connected between the motor coil and the resistor R6 in parallel, a resistor R4, a fet M7 and a fet M8 are connected between the motor coil and the resistor R5 in parallel, the other end of the resistor R3 is connected to a power supply VCC after being connected to a fet M6 and a fet M5 in series, one end of the resistor R4 is connected to a motor coil and a resistor R6, and the other end of the resistor R7 and a fet M8 in series are connected to a ground.

In this embodiment, the gate of the fet M5 is used as an enable signal terminal, the source of the fet M5 is connected to the VCC, the drain of the fet M5 is connected to the drain of the fet M6, and the source of the fet M6 is connected to the resistor R3. The grid of the field effect transistor M8 is used as an enabling signal end, the source electrode of the field effect transistor M8 is grounded, the drain electrode of the field effect transistor M8 is connected with the source electrode of the field effect transistor M7, and the drain electrode of the field effect transistor M7 is connected with the resistor R4. The source electrode of the field effect transistor M9 is connected with the non-inverting input end of the comparator A1, and the drain electrode is connected with the resistor R5. The source electrode of the field effect transistor M10 is connected with the inverting input end of the comparator A2, and the drain electrode is connected with the resistor R6.

In this embodiment, a voltage dividing branch for providing a reference voltage for the comparator is disposed between the VCC terminal and the ground terminal. Wherein, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a resistor R10 and a source electrode connected with a field effect tube M11 and connected with a field effect tube M11 are connected in series on the voltage dividing branch, and a drain is connected with the resistor 10; the branch circuit utilizes resistance voltage division to provide 3V voltage for the inverting input terminal of the comparator A1 and 2V voltage for the non-inverting input terminal of the comparator A2 respectively.

In this embodiment, the fet M5, the fet M6, and the fet M7 are all P-channel MOS transistors, the fets M8, M9, M10, and M11 are all N-channel MOS transistors, and parasitic diodes are disposed between the sources and drains of the fets M6, M7, M9, and M10.

The working principle of the diagnosis circuit is analyzed as follows:

as shown in fig. 1, a commonly used H-bridge driving circuit: when the motor is in an off state, the voltage at two ends of the coil is in a suspended state, the two ends of the winding coil are directly connected by a lead to obtain the voltage of power failure, and R1 and R2 represent the resistance of the lead.

If the motor fault diagnosis circuit shown in fig. 2 is introduced, the coil acts as a conducting wire in an ideal state, and the acquired voltage is compared with the set threshold voltage to serve as fault diagnosis data. Assuming that the power VCC of the introduced fault diagnosis module is 5V, when the fault diagnosis module is normally connected, the voltages at two ends of the coil are equal to be VCC/2 (ideally, the coil serves as a conducting wire and is matched with R3 and R4, and M6 and M7), at this time, the output of the comparator is all low level, and 00 codes can be obtained by correspondingly transmitting the low level to the ADC module and stored in the register as the state that the driving circuit is normally connected with the winding coil.

When the load and the power supply are in a short circuit state, the voltage at the OUTA and OUTB points is higher than 3V, the comparator A1 outputs a high level, and the comparator A2 outputs a low level.

When the load and the ground are in a short circuit state, the voltage at the OUTA and OUTB points is lower than 2V, the comparator A1 outputs a low level, and the comparator A2 outputs a high level.

When the OUTA voltage is higher than 3V and the OUTB voltage is lower than 2V when the load is in an open state, the comparators a1 and a2 simultaneously output a high level.

In addition, as shown in fig. 3, the reference voltage for comparison of the comparator can be realized by dividing the voltage by resistors, but considering the temperature coefficient and the power consumption problem during diagnosis together, assuming that each resistor is 20K, a fixed 50uA current will continuously flow from the power supply to the ground during diagnosis. And because the working voltage of the motor can reach dozens of volts or even dozens of volts when the motor works, DMOS is required to be used as a power isolation protection fault diagnosis circuit, such as M6-M10. Meanwhile, in order to avoid the phenomenon of misdiagnosis when the motor works, M5, M8 and M11 switch tubes are required to be added, so that the diagnosis circuit is in a failure state when the motor works.

The foregoing illustrates and describes the principles, general features, and advantages of the present invention. It should be understood by those skilled in the art that the above embodiments do not limit the scope of the present invention in any way, and all technical solutions obtained by using equivalent substitution methods fall within the scope of the present invention.

The parts not involved in the present invention are the same as or can be implemented using the prior art.

Claims

1. The fault diagnosis circuit of the H bridge is characterized by comprising a comparator A1 and a comparator A2, wherein the non-inverting input end of the comparator A1 is connected with one end of a motor coil through a field effect transistor M9 and a resistor R5, the inverting input end of the comparator A2 is connected with the other end of the motor coil through a field effect transistor M10 and a resistor R6, a resistor R3, a field effect transistor M6 and a field effect transistor M5 are connected between the motor coil and the resistor R6 in parallel, a resistor R4, a field effect transistor M7 and a field effect transistor M8 are connected between the motor coil and the resistor R5, the other end of the resistor R3 is connected with the field effect transistor M6 and the field effect transistor M5 in series and then connected with a power supply VCC, one end of a resistor R4 is connected between the motor coil and the resistor R6, and the other end of the resistor R4 is connected with the field effect transistor M7 and the field effect transistor M8 in series and.

2. The H-bridge fault diagnosis circuit according to claim 1, wherein the gate of the FET M5 is used as an enable signal terminal, the source of the FET M5 is connected to a power supply VCC, the drain of the FET M5 is connected to the drain of the FET M6, and the source of the FET M6 is connected to the resistor R3.

3. The H-bridge fault diagnosis circuit according to claim 1, wherein the gate of the FET M8 is used as an enable signal terminal, the source of the FET M8 is grounded, the drain of the FET M8 is connected to the source of the FET M7, and the drain of the FET M7 is connected to the resistor R4.

4. The H-bridge fault diagnosis circuit according to claim 1, wherein the source of the FET M9 is connected to the non-inverting input terminal of the comparator A1, and the drain is connected to the resistor R5.

5. The H-bridge fault diagnosis circuit according to claim 1, wherein the source of the FET M10 is connected to the inverting input terminal of the comparator A2, and the drain is connected to the resistor R6.

6. The H-bridge fault diagnosis circuit according to claim 1, wherein a voltage dividing branch for providing a reference voltage for the comparator is provided between the VCC terminal and the ground terminal.

7. The H-bridge fault diagnosis circuit according to claim 6, wherein the voltage dividing branch is connected in series with a resistor R6, a resistor R7, a resistor R8, a resistor R9, a resistor R10 and a field effect transistor M11, and by means of voltage division of the resistors, A3V voltage is provided to the inverting input terminal of the comparator A1 and a 2V voltage is provided to the non-inverting input terminal of the comparator A2.

8. The H-bridge fault diagnosis circuit according to claim 1, wherein the field effect transistor M5, the field effect transistor M6 and the field effect transistor M7 are all P-channel MOS transistors, the field effect transistor M8, the field effect transistor M9, the field effect transistor M10 and the field effect transistor M11 are all N-channel MOS transistors, and parasitic diodes are arranged between the source and the drain of the field effect transistor M6, the field effect transistor M7, the field effect transistor M9 and the field effect transistor M10.