H-bridge power transistor over-current detection protection circuit and motor driving controller

Abstract

The invention provides an H-bridge power transistor over-current detection protection circuit and a motor driving controller, which are applied to the technical field of motor driving, and the H-bridge power transistor over-current detection protection circuit comprises a first sampling detection unit, a second sampling detection unit, a third sampling detection unit and a fourth sampling detection unit, the high-side transistor is used for sampling and detecting a first current flowing from a positive bus of a power supply to the high-side transistor; the second sampling detection unit is arranged between a low-side transistor of the H bridge and the negative bus of the power supply and is used for sampling and detecting second current flowing from the low-side transistor to the negative bus of the power supply; and the processing unit is used for carrying out signal processing on the sampling signals output by the two sampling detection units, and the processing unit outputs a control signal required by the motor according to two processing results corresponding to the two sampling signals. And normal parameters of the motor and phase line short-circuit fault parameters of the motor can be monitored in real time through the sampling detection circuits arranged at the high and low edges of the H bridge.

Description

Technical Field

[0001] The present application relates to the field of motor drive technology, and in particular to an H-bridge power transistor overcurrent detection protection circuit and a motor drive controller. Background Art

[0002] The motor drive controller mainly plays the role of a power controller that drives the motor to rotate according to the designer's intention. Its main power devices include a microcontroller (MCU, also known as a microprocessor, which will not be distinguished below), a pre-driver (Pre-Driver, also known as a pre-driver, which will not be distinguished below), an H-bridge (H-Bridge) composed of power transistors (such as field effect transistors MOSFET, insulated gate bipolar transistors IGBT, etc.), a shunt collection circuit (SHUNT, also known as a current collection circuit, which will not be distinguished below), etc. Among them, the Pre-Driver is the most critical device. For occasions with high safety requirements, the Pre-Driver needs to integrate various over-current, over-voltage and other protection functions, and over-current protection is the most critical one.

[0003] Therefore, existing solutions all use a Pre-Driver with a drain-source voltage (VDS) overvoltage protection function to achieve overcurrent protection for each MOSFET in an H-bridge (including a two-phase H-bridge and a three-phase H-bridge). Summary of the invention

[0004] In view of this, the embodiments of this specification provide an H-bridge power transistor overcurrent detection protection circuit and a motor drive controller, which can achieve overcurrent protection for all MOSFETs of the H-bridge (including two-phase H-bridge and three-phase H-bridge) even if the Pre-Driver with VDS protection function is not required.

[0005] The embodiments of this specification provide the following technical solutions:

[0006] The embodiment of this specification provides an H-bridge power transistor overcurrent detection protection circuit, including: a first sampling detection unit, a second sampling detection unit and a processing unit;

[0007] The first sampling detection unit is arranged between the high-side transistor of the H-bridge and the positive bus of the power supply, and is used for sampling and detecting the first current flowing from the positive bus of the power supply to the high-side transistor to obtain a first sampling signal;

[0008] The second sampling detection unit is arranged between the low-side transistor of the H-bridge and the negative power bus, and is used for sampling and detecting the second current flowing from the low-side transistor to the negative power bus to obtain a second sampling signal;

[0009] The processing unit is used to process the first sampling signal and the second sampling signal respectively to form a first processing result corresponding to the first sampling signal and a second processing result corresponding to the second sampling signal, and to generate a corresponding first drive control signal according to the first processing result and the second processing result and output it to the pre-driver, and the first drive control signal is used to generate a power switching signal of the power transistor in the H-bridge in the pre-driver.

[0010] Preferably, the processing unit is also used to determine whether the motor driven by the H-bridge has a phase line short circuit fault based on the first processing result and the second processing result, and when it is determined that there is a phase line short circuit fault, output a second drive control signal to the pre-driver, and record the fault type corresponding to the phase line short circuit fault. The second drive control signal is used to cut off the path for the pre-driver to output the drive signal to the H-bridge.

[0011] Preferably, the first sampling detection unit includes a first current sampling circuit and a first signal conditioning circuit, wherein the first current sampling circuit is connected in series between the high-side transistor of the H-bridge and the positive bus of the power supply, and is used to form a first feedback signal according to a first current flowing from the positive bus of the power supply to the high-side transistor; and the first signal conditioning circuit is used to perform signal amplification and conditioning on the first feedback signal, so as to output the first sampling signal to the processing unit;

[0012] and / or:

[0013] The second sampling detection unit includes a second current sampling circuit and a second signal conditioning circuit, wherein the second current sampling circuit is connected in series between the low-side transistor of the H-bridge and the negative power bus, and is used to form a second feedback signal according to a second current flowing from the low-side transistor to the negative power bus; and the second signal conditioning circuit is used to amplify and condition the second feedback signal to output the second sampling signal to the processing unit.

[0014] Preferably, the first current sampling circuit comprises a first shunt sampler, and the first signal conditioning circuit comprises a first operational amplifier, wherein the first shunt sampler is used to convert the first current into a first feedback signal in the form of a voltage signal, and the first operational amplifier is used to proportionally amplify the first feedback signal in the form of a voltage signal to form the first sampling signal in the form of a voltage signal;

[0015] and / or:

[0016] The second current sampling circuit includes a second shunt sampler, and the second signal conditioning circuit includes a second operational amplifier, wherein the second shunt sampler is used to convert the second current into a second feedback signal in the form of a voltage signal, and the second operational amplifier is used to proportionally amplify the second feedback signal in the form of a voltage signal to form the second sampling signal in the form of a voltage signal.

[0017] Preferably, the first current shunt sampler comprises a first sampling resistor, and the first operational amplifier is used to proportionally amplify a first voltage drop on the first sampling resistor;

[0018] And / or: the second current shunt sampler includes a second sampling resistor, and the second operational amplifier is used to proportionally amplify a second voltage drop on the second sampling resistor.

[0019] Preferably, the processing unit comprises a first comparator, wherein one input terminal of the first comparator is electrically connected to the first sampling detection unit, the other input terminal of the first comparator inputs a first reference signal, and the first comparator is used to output the first processing result according to the difference between the first sampling signal and the first reference signal;

[0020] and / or:

[0021] The processing unit includes a second comparator, wherein one input end of the second comparator is electrically connected to the second sampling detection unit, and the other input end of the second comparator inputs a second reference signal, and the second comparator is used to output the second processing result according to the difference between the second sampling signal and the second reference signal.

[0022] Preferably, the processing unit includes a first analog-to-digital converter and a first judgment unit, wherein the input end of the analog-to-digital converter is electrically connected to the first sampling detection unit, the first analog-to-digital converter is used to convert the first sampling signal into a first digital signal; the first judgment unit is used to judge the first digital signal with a preset first threshold and then output the first processing result;

[0023] and / or:

[0024] The processing unit includes a second analog-to-digital converter and a second judgment unit, wherein the input end of the second analog-to-digital converter is electrically connected to the second sampling detection unit, and the second analog-to-digital converter is used to convert the second sampling signal into a second digital signal; the second judgment unit is used to output the second processing result after judging the second digital signal with a preset second threshold.

[0025] Preferably, the processing unit comprises a microcontroller, and the microcontroller is a processor including a comparator and an analog-to-digital converter.

[0026] The embodiment of the present specification also provides a motor drive controller, including: a detection protection circuit, a pre-driver and an H-bridge, wherein the detection protection circuit is electrically connected to the pre-driver, the pre-driver is electrically connected to the H-bridge, and the load output end of the H-bridge is used to connect to a target motor;

[0027] The detection protection circuit is an H-bridge power transistor overcurrent detection protection circuit as described in any one of the embodiments in this specification, which is used to sample and detect a first current flowing from a positive bus of a power supply to a high-side transistor in the H-bridge, and to sample and detect a second current flowing from a low-side transistor in the H-bridge to a negative bus of a power supply, and output a corresponding control signal to the pre-driver after processing the first current and the second current;

[0028] The pre-driver is used to generate a power switch signal of the power transistor in the H-bridge according to the control signal output by the detection protection circuit;

[0029] The power transistors in the H-bridge drive the target motor to operate under the drive of the power switch signal.

[0030] Preferably, the pre-driver is a pre-driver without drain-source overvoltage protection;

[0031] And / or, the power transistor in the H-bridge is a MOSFET or an IGBT;

[0032] And / or, the control signal output by the detection protection circuit to the pre-driver includes a PWM signal.

[0033] Compared with the prior art, the at least one technical solution adopted in the embodiments of this specification can achieve the following beneficial effects:

[0034] By setting sampling detection branch units on the high and low sides of the H-bridge respectively, these sampling detection results are processed and judged by the processing unit for overcurrent detection and protection. Even if a Pre-Driver without VDS protection is used, only some general devices (such as SHUNT, operational amplifier, etc.) are needed to achieve device-level overcurrent detection and protection of MOSFET in the H-bridge (including two-phase H-bridge and three-phase H-bridge, etc.), and the type of short-circuit fault can be given in time, which is convenient for locating, eliminating and analyzing the fault.

[0035] Moreover, because the components used are universal and mature, the device cost is low and can be purchased domestically, avoiding the defects of long supply cycle and high cost of imported components, which is conducive to reducing product costs, shortening product delivery cycle, and improving product production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0037] Figure 1 It is a structural diagram of a motor drive controller in an existing solution;

[0038] Figure 2 It is a structural schematic diagram of an H-bridge power transistor overcurrent detection protection circuit and a motor drive controller in this application;

[0039] Figure 3 It is a structural schematic diagram of the sampling and detection unit in this application. DETAILED DESCRIPTION

[0040] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0041] The following describes the implementation methods of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the following embodiments and the features in the embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.

[0042] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present application, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspect described herein can be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method.

[0043] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application. The drawings only show components related to the present application rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0044] Additionally, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, it will be understood by those skilled in the art that the examples can be practiced without these specific details.

[0045] like Figure 1 As shown, in the existing motor drive controller hardware architecture, the microcontroller (MCU, also known as a microprocessor, which is not distinguished in this article) outputs 4 or 6 PWMs to the Pre-Driver, and then the Pre-Driver drives the 4 MOSFETs in the two-phase H-bridge (H-Bridge) or the 6 MOSFETs in the three-phase H-bridge to turn on and off, thereby controlling the magnitude and direction of the current flowing through the load (Load), that is, controlling the current and direction of the motor (Motor). In addition, the detection of the current of each phase of the motor is performed by sampling the current through the shunt detector (SHUNT), and the sampling signal is then sent to the low-side operational amplifier for signal conditioning and the conditioned signal is finally processed by the processing unit (such as MCU) to complete the signal processing and control adjustment.

[0046] Under the hardware architecture, when the motor is working, if any phase line of the motor is short-circuited to the positive bus VBAT+ or the negative bus VBAT-, or if two phase lines are short-circuited, the MOSFET will inevitably pass a large current in a short period of time and be damaged or even destroyed.

[0047] Therefore, a Pre-Driver without VDS protection cannot provide device-level overcurrent protection for the MOSFET in the H-bridge.

[0048] At present, in this structure, the Pre-Driver is required to have a VDS protection function to perform overcurrent protection on all MOSFETs in the H-bridge (including two-phase H-bridge and three-phase H-bridge). The Pre-Drivers with VDS protection function are all imported integrated devices. The price of the Pre-Driver is relatively high and it is an imported device. Due to the shortage of chips, the supply of such integrated Drivers is tight, the price is high, and the supply cycle is long, resulting in high overall production costs and long delivery cycles.

[0049] In view of this, through in-depth research and improvement exploration of motor drive controller and Pre-Driver, preliminary findings:

[0050] The foregoing Figure 1In the illustrated hardware architecture, after adopting the Pre-Driver with VDS protection function, the overcurrent protection of the transistor in the H-bridge can be realized, wherein the overcurrent protection is based on the hardware in the Pre-Driver to monitor the voltage drop VDS between the drain (Drain) and the gate (Source) of the corresponding MOSFET in real time at the turn-on time, and then judge whether the MOSFET may have an overcurrent fault according to VDS, and immediately turn it off when it is judged that an overcurrent fault may occur, so as to avoid the MOSFET from being damaged or even destroyed due to overcurrent;

[0051] However, since there is generally a spike voltage in the voltage drop VDS between Drain and Source when the MOSFET is turned on, when the hardware in the Pre-Driver monitors the voltage drop VDS between Drain and Source of the MOSFET in the H-bridge at the time of turning on, the hardware in the Pre-Driver needs to be able to accurately identify the spike voltage to prevent the MOSFET in normal working state from being mistakenly turned off by the Pre-Driver due to false triggering of the spike voltage, causing abnormal operation of the motor. Therefore, the Pre-Driver is designed with relevant hardware circuits with VDS protection function. Compared with the Pre-Driver without VDS protection function, not only is the device cost of the Pre-Driver high, but the circuit structure of the Pre-Driver is also complex. These factors are not conducive to the design, production and subsequent maintenance of the motor drive controller;

[0052] Moreover, this type of Pre-Driver is an imported device, and the actual production of motor drivers is often subject to the supply of this type of imported devices, such as high prices, long delivery cycles, and even chip shortages.

[0053] In the exploration of further improvements to the existing motor drive, it was also found that:

[0054] The foregoing Figure 1 In the hardware architecture, the sampling and detection branches such as the shunt sampler (SHUNT) and the operational amplifier (OPA) are set between the low-side MOSFET of the H-bridge and the negative bus of the power supply. This branch is only used to sample and detect the current size, direction and other parameters of the motor under the working state. Therefore, the existing scheme has not found that the sampling and detection circuit may have further uses under this hardware architecture, such as being used to detect the real-time short-circuit protection of the MOSFET, and has not further applied the possible uses of this branch in the overall circuit.

[0055] In addition, after an in-depth analysis of the short circuit situation, it was also found that: Figure 1The hardware architecture can timely perform overcurrent protection on the power transistor of the H-bridge when a short-circuit fault occurs in the motor phase line. However, even if it is known that a short-circuit fault (i.e., an overcurrent fault) has occurred, it is impossible to know where the phase line and the circuit are short-circuited to cause the current short-circuit fault.

[0056] For example, the short circuit fault may be any of the following fault types: a phase line short circuited to the positive busbar of the power supply, a phase line short circuited to the negative busbar of the power supply, or a phase line short circuited to each other.

[0057] Therefore, once a short circuit fault occurs, it is very inconvenient to locate the short circuit fault in time and to eliminate and analyze it because the type of short circuit fault cannot be directly known, which seriously affects the troubleshooting and maintenance of the motor drive and the motor.

[0058] Based on this, the embodiment of this specification proposes an architecture of an H-bridge power transistor overcurrent detection protection circuit:

[0059] like Figure 2 As shown, two upper and lower sampling detection branches are respectively set at the high side and low side of the H-Bridge (such as Figure 2 The diagram shows a sampling detection branch including "SHUNT+op amp"), and these two sampling detection branches sample and detect the working parameters of the load motor (such as current, direction, etc.), and the processing unit processes and judges the sampling detection results. Finally, the processing unit controls the control signal of the Pre-Driver (such as the PWM signal for driving) in time according to the judgment result, so that the Pre-Driver drives the MOSFET of the H-bridge accordingly (for example, does not output the driving signal) under the control of these control signals, thereby performing overcurrent detection and protection on all transistors in the H-bridge.

[0060] For example, when any phase line of the load motor is short-circuited to the negative bus VBAT- of the power supply, the short-circuit current flows through the high-side sampling detection circuit (such as SHUNT) and the high-side MOSFET (such as Figure 2 GHA transistor shown in the figure), low-side MOSFET (such as Figure 2The GLB transistor shown in the figure), and then flows to VBAT- through the phase line of the motor short circuit. At this time, the high-side SHUNT completes the sampling detection of overcurrent, such as taking the voltage drop caused by the short-circuit current on the high-side SHUNT as the sampling detection result, and the sampling detection result is input into the high-side signal conditioning circuit (such as the operational amplifier OPA) for signal conditioning. After the processing and judgment of the conditioning signal in and out by the processing unit (such as MCU), it can timely judge that the transistor may have an overcurrent fault, and then control the PWM signal output to the Pre-Driver, so as to realize the control of the MOSFET working state. For example, when it is judged that the voltage value of the sampling detection result of the high-side SHUNT is higher than the set overcurrent protection threshold, the hardware overcurrent protection is triggered: for example, the processing unit MCU cuts off the PWM signal output, thereby removing the MOSFET drive signal, so that the Pre-Driver no longer drives the MOSFET to work, thereby cutting off the short-circuit current loop to achieve short-circuit protection.

[0061] For example, when any phase line of the load motor and the positive bus VBAT+ of the power supply are short-circuited, the current of VBAT+ flows through the phase line of the motor, flows to the MOSFET that is being turned on at the low side of the H-bridge (including 2-phase H-bridge and 3-phase H-bridge), and then flows to VBAT- through the low-side SHUNT. At this time, the low-side SHUNT completes the sampling detection of overcurrent, such as taking the voltage drop caused by the short-circuit current on the low-side SHUNT as the sampling detection result, and the sampling detection result is input into the low-side signal conditioning circuit (such as operational amplifier OPA) for signal conditioning, and the processing unit (such as MCU) processes the conditioned signal. After processing and judgment, it can be judged in time that the transistor may have an overcurrent fault, and then the PWM signal output to the Pre-Driver can be controlled to achieve the control of the MOSFET working state. For example, when it is judged that the voltage value of the sampling detection result of the low-side SHUNT is higher than the set overcurrent protection threshold, the hardware overcurrent protection is triggered: for example, the processing unit MCU cuts off the output of the PWM signal, thereby removing the MOSFET drive signal, so that the Pre-Driver no longer drives the MOSFET to work, thereby cutting off the short-circuit current loop to achieve short-circuit protection.

[0062] For example, when a short circuit occurs between any two phase lines in the load motor, the short-circuit current flows through the high-side SHUNT and the high-side MOSFET that is in the on state via VBAT+, and then flows through the short-circuited phase line of the motor to the lower MOSFET that is being turned on in the other bridge arm, and then flows to the low-side SHUNT and then to VBAT-. In this case, the short-circuit current will flow through both the high-side and low-side SHUNTs. After the high-side and low-side op amps amplify the signal, it is sent to the processing circuit (such as MCU) for processing and judgment. At this time, any processing and judgment result can indicate that there is an overcurrent fault, and then all MOSFETs are cut off, and the short-circuit current loop is cut off.

[0063] In summary, by setting sampling detection branch units on the high and low sides of the H-bridge respectively, these sampling detection results are processed and judged by the processing unit for overcurrent detection and protection. Even if a Pre-Driver without VDS protection is used, only some general devices (such as SHUNT, operational amplifier, etc.) are needed to achieve device-level overcurrent detection and protection of MOSFET in the H-bridge (including two-phase H-bridge and three-phase H-bridge, etc.), and the type of short-circuit fault can be given in time, which is convenient for locating, eliminating and analyzing the fault.

[0064] In addition, because the components used are general and mature, the device cost is low and can also be purchased domestically, avoiding the defects of long supply cycle and high cost of imported components, which is conducive to reducing product costs, shortening product delivery cycle, and improving product production efficiency.

[0065] The technical solutions provided by various embodiments of the present application are described below in conjunction with the accompanying drawings.

[0066] like Figure 2 As shown, the embodiment of the specification provides an H-bridge power transistor overcurrent detection protection circuit, wherein the circuit includes: a first sampling detection unit 110, a second sampling detection unit 120 and a processing unit 130. Among them, the first sampling detection unit 110 is arranged between the high-side transistor of the H-bridge 30 and the positive power bus VBAT+, and the second sampling detection unit 120 is arranged between the low-side transistor of the H-bridge and the negative power bus VBAT-, that is, a sampling detection branch is respectively arranged between the high-side and low-side transistors of the H-bridge and the power bus, and the branch performs sampling detection on the current between the power transistor of the H-bridge and the bus, and the processing unit 130 processes the sampling detection result of the branch to form a driving signal required for the H-bridge to drive the motor (Motor) to work, or the processing unit 130 processes the sampling detection result based on the processing, and then generates the control signal required by the pre-driver, so that the pre-driver 20 correctly drives the H-bridge 30 under the action of the control signal.

[0067] Specifically, the first sampling detection unit 110 is used to detect the current flowing from the positive bus VBAT+ of the power supply to the high-side transistor of the H bridge (for example Figure 2 The first current (eg, Figure 2 The current shown in the dotted line flow direction is sampled and detected to obtain a first sampling signal;

[0068] The second sampling detection unit 120 is used to detect the low-side transistors (such as Figure 2 The GLB transistor in the diagram) samples and detects a second current flowing to the negative bus of the power supply to obtain a second sampling signal;

[0069] The processing unit 130 is used to process the first sampling signal and the second sampling signal respectively to form a first processing result corresponding to the first sampling signal and a second processing result corresponding to the second sampling signal, and to generate a corresponding first drive control signal according to the first processing result and the second processing result and then output it to the pre-driver 20. The first drive control signal is used to generate a power switching signal of the power transistor in the H-bridge 30 in the pre-driver 20, so that the transistor performs a switching action under the action of the corresponding power switching signal to realize the driving of the load (Load), where the load can be a motor 40 (Motor).

[0070] It should be noted that the load motor can be a two-phase motor or a three-phase motor, so the H-bridge is correspondingly provided with power transistors for driving the two-phase motor or the three-phase motor.

[0071] In implementation, the sampling and detection units are also arranged corresponding to the H-bridge, that is, each H-bridge corresponds to two upper and lower sampling and detection units, wherein the first sampling and detection unit arranged on the high side of the H-bridge is used to sample and detect the first current flowing from the positive bus of the power supply to the high-side transistor of the H-bridge, and the second sampling and detection unit arranged on the low side of the H-bridge is used to sample and detect the second current flowing from the low-side transistor of the H-bridge to the negative bus of the power supply.

[0072] In summary, by respectively setting the first sampling detection unit and the second sampling detection unit on the high and low sides of the H-bridge, the current flowing through the high-side transistor of the H-bridge can be monitored in real time by the first sampling detection unit, and the current flowing through the low-side transistor of the H-bridge can be monitored in real time by the second sampling detection unit. Therefore, through these two monitoring results, it is possible to judge in real time whether there is a short-circuit fault in the phase line of the motor during the operation of the motor, and control the pre-driver according to the judgment result.

[0073] Among them, when there is no short-circuit fault, the control signal (such as PWM signal) is still normally output to the pre-driver, so that the pre-driver can drive the power switch of the power transistor of the H-bridge, so that the H-bridge can drive the motor to work normally; when there is a short-circuit fault, the pre-driver is controlled to cut off the path of the power switch driving of the H-bridge, and the power transistor of the H-bridge is protected from overcurrent in time.

[0074] In some implementations, after the processing unit processes the sampling signal in real time, when a short circuit fault is determined based on the processing result, overcurrent protection may be performed in a timely manner.

[0075] As schematically illustrated above, since the first sampling signal corresponds to the sampling result of the first current flowing from the positive bus of the power supply to the high-side transistor of the H-bridge, the first processing result can be used to characterize whether the phase line of the motor is short-circuited to the positive bus of the power supply VBAT+; similarly, the second processing result can be used to characterize whether the phase line of the motor is short-circuited to the negative bus of the power supply VBAT-; and the first processing result and the second processing result can be used together to characterize the existence of a short-circuit fault between the phase lines of the motor.

[0076] For example, when the first processing result reflects that a short circuit fault currently exists, and the second processing result does not reflect that a short circuit fault currently exists, the short circuit fault type is that the phase line of the motor is short-circuited to the negative bus VBAT- of the power supply;

[0077] For example, when the first processing result does not reflect that a short circuit fault currently exists, and the second processing result reflects that a short circuit fault currently exists, the short circuit fault type is that the phase line of the motor is short-circuited to the positive bus VBAT+ of the power supply;

[0078] For example, when the first processing result reflects that a short circuit fault currently exists, and the second processing result also reflects that a short circuit fault currently exists, the short circuit fault type is that a short circuit exists between phase lines of the motor.

[0079] Therefore, the processing unit 130 is also used to determine whether the motor 40 driven by the H-bridge 30 has a phase line short circuit fault based on the first processing result and the second processing result, and when it is determined that the phase line short circuit fault exists, output a second drive control signal to the pre-driver 20, and record the fault type corresponding to the phase line short circuit fault, wherein the second drive control signal is used to cut off the path for the pre-driver 20 to output the power switching signal to the H-bridge 30.

[0080] For example, the processing unit 130 no longer outputs the PWM signal to the pre-driver 20 , so that the pre-driver 20 loses control of the PWM signal, and thus the pre-driver 20 no longer generates the power switch signal required by the H-bridge 40 .

[0081] In some embodiments, at the moment of a short circuit fault, the fluctuation of the monitored current signal may be relatively small, so the sampled signal can be amplified and conditioned in time after sampling, so that the conditioned signal is easier to be processed by the subsequent circuit unit. Therefore, the sampling detection unit may include a sampling circuit unit and a signal conditioning circuit unit.

[0082] In some examples, such as Figure 3 As shown, the first sampling detection unit 110 includes a first current sampling circuit 1101 and a first signal conditioning circuit 1102, wherein the first current sampling circuit 1101 is connected in series to the high-side transistor of the H-bridge 30 (as described above). Figure 2between the GHA transistor shown in the figure) and the positive bus VBAT+ of the power supply, and is used to flow from the positive bus VBAT+ of the power supply to the first current of the high-side transistor (as described above) Figure 2 The first signal conditioning circuit 1102 is used to amplify and condition the first feedback signal to output the first sampling signal V1 to the processing unit.

[0083] In some examples, such as Figure 3 In other words, the second sampling detection unit 120 can also adopt the circuit form of the first sampling detection unit 110. Specifically, the second sampling detection unit 120 includes a second current sampling circuit 1201 and a second signal conditioning circuit 1202, wherein the second current sampling circuit 1201 is connected in series to the low-side transistor of the H bridge 30 (such as the aforementioned Figure 2 between the GLB transistor shown in the figure) and the negative power bus VBAT-, for a second current (as described above) flowing from the low-side transistor to the negative power bus VBAT- Figure 2 The second feedback signal is formed by a current (indicated by the dotted line in the middle); and the second signal conditioning circuit 1202 is used to amplify and condition the second feedback signal to output the second sampling signal V2 to the processing unit.

[0084] In implementation, the sampling detection unit may sample current based on sampling means such as a sampling resistor, a Hall sensor, a fluxgate current sensor, etc. The specific sampling circuit may be configured according to the different sampling means used.

[0085] It should be noted that, in each of the above examples, the first sampling signal obtained by the first sampling detection unit through sampling and detection of the current can be a current signal or a voltage signal; accordingly, the processing unit can process the first sampling signal by processing the current signal or the voltage signal. Similarly, the second sampling signal obtained by the second sampling detection unit through sampling and detection of the current can be a current signal or a voltage signal; accordingly, the processing unit can process the second sampling signal by processing the current signal or the voltage signal.

[0086] The following is a schematic explanation of a circuit in which a current signal is sampled and converted into a voltage signal.

[0087] Voltage quantities can usually be directly measured and processed, so the sampling detection unit can first sample the monitored current signal and convert it into a voltage signal, and then amplify and condition the voltage signal based on the operational amplifier circuit, so that the subsequent circuit can process the conditioned voltage signal.

[0088] In some implementations, current sampling may be accomplished by a shunt sampler, wherein the shunt sampler is used to measure current, and thus the shunt sampler may be used in a current sampling circuit to accomplish sampling of a current signal.

[0089] In some examples, such as Figure 3 As shown, the first current sampling circuit 1101 includes a first shunt sampler, and the first signal conditioning circuit 1102 includes a first operational amplifier circuit, wherein the first shunt sampler is used to convert the first current into a first feedback signal in the form of a voltage signal, and the first operational amplifier circuit is used to proportionally amplify the first feedback signal in the form of a voltage signal to form the first sampling signal in the form of a voltage signal.

[0090] The first operational amplifier unit may include several stages of operational amplifier circuits, and each stage of operational amplifier circuit may be as follows: Figure 3 Schematic operational amplifier circuit: The two input terminals of the operational amplifier U11 are respectively connected to the two ends of the first shunt sampler through corresponding resistors, and a proportional amplifier circuit is formed by setting corresponding resistors. For example, the in-phase input terminal of U11 is connected to the connection between the first shunt sampler and the positive bus of the power supply through R11, the in-phase input terminal of U11 is connected to the ground through R12, the inverting input terminal of U11 is connected to the connection between the first shunt sampler and the high-side transistor of the H bridge 30 through R13, and the inverting input terminal of U11 is connected to the output terminal of U11 through R14.

[0091] In some examples, the second current sampling circuit 120 may also adopt the circuit form of the aforementioned first current sampling circuit 110. Specifically, the second current sampling circuit 1201 includes a second shunt sampler, and the second signal conditioning circuit 1202 includes a second operational amplifier circuit, wherein the second shunt sampler is used to convert the second current into a second feedback signal in the form of a voltage signal, and the second operational amplifier circuit is used to proportionally amplify the second feedback signal in the form of a voltage signal to form the second sampling signal in the form of a voltage signal. It should be noted that the circuit functions and connection relationships of the second comparator U21 and the resistors R21-R24 of the second operational amplifier circuit can be found in Figure 3 The schematic diagram of the aforementioned first operational amplifier circuit will not be further described.

[0092] In some examples, a shunt sampler (SHUNT) may be connected in series on the current path, so that a voltage signal of a voltage drop across the SHUNT may be obtained, and then the voltage drop signal may be amplified and conditioned by an operational amplifier circuit.

[0093] Further, if Figure 3As shown in FIG. 1 , by setting a sampling resistor in the SHUNT, the circuit form of converting the current signal into a voltage signal after being sampled is further simplified.

[0094] For example, see Figure 3 Schematically, the first current shunt sampler includes a first sampling resistor R S1 , the first sampling resistor R S1 The first operational amplifier circuit is connected in series between the positive power bus VBAT+ and the high-side transistor of the H-bridge 30 , and can be used to proportionally amplify the first voltage drop on the first sampling resistor.

[0095] For example, see Figure 3 The second current shunt sampler includes a second sampling resistor R S2 The second operational amplifier is used to proportionally amplify the second voltage drop on the second sampling resistor.

[0096] It should be noted that the sampling resistor set in SHUNT can be a resistor with a very small resistance value, for example, the resistance value can be 0.1mΩ, 0.15mΩ, 0.25mΩ and other specifications. This type of resistor has high precision and small temperature drift, and the accuracy of the full range can be guaranteed. Compared with other current detection solutions (such as Hall sensors), the overall accuracy is very high and can meet various application scenarios.

[0097] In some implementations, a comparator circuit may be used in the processing unit to compare and judge the sampling signals, thereby quickly determining whether a phase line of the motor has a short circuit fault through comparison and judgment.

[0098] In one example, as mentioned above Figure 2 As shown, the processing unit 130 includes a first comparator A1, wherein one input terminal of the first comparator A1 is electrically connected to the first sampling detection unit 110, and another input terminal of the first comparator A1 inputs a first reference signal (e.g. Figure 2 The first comparator A1 is used to output the first processing result according to the difference between the first sampling signal and the first reference signal.

[0099] Therefore, when the first sampling signal output by the first sampling detection unit 110 is greater than the first reference signal, the comparator is triggered to flip and output the first comparison result (which can be recorded as the first processing result), indicating that there is a short circuit fault in the phase line of the motor. Specifically, whether the phase line of the motor is short-circuited to the negative bus VBAT- of the power supply, or the phase lines are short-circuited, it is also necessary to combine the second sampling signal output by the second sampling detection unit 120 to make a judgment.

[0100] In one example, as mentioned above Figure 2As shown, the processing unit 130 includes a second comparator A2, wherein one input terminal of the second comparator A2 is electrically connected to the second sampling detection unit 120, and another input terminal of the second comparator A2 inputs a second reference signal (e.g. Figure 2 The second comparator A2 is used to output the second processing result according to the difference between the second sampling signal and the second reference signal.

[0101] Therefore, when the second sampling signal output by the second sampling detection unit 120 is greater than the second reference signal, the comparator is triggered to flip and output the second comparison result (which can be recorded as the second processing result), indicating that there is a short circuit fault in the phase line of the motor. Specifically, whether the phase line of the motor is short-circuited to the positive bus VBAT+ of the power supply, or the phase lines are short-circuited, it is also necessary to combine the second sampling signal output by the first sampling detection unit 110 to make a judgment.

[0102] In implementation, the comparator may be in the form of an independent circuit, or may be a functional circuit in a signal processing processor (such as an MCU).

[0103] In addition, the comparator in the aforementioned example can be selected as a current type comparator when the sampling signal is in the form of a current signal, and can be selected as a voltage type comparator when the sampling signal is in the form of a voltage signal.

[0104] It should be noted that the first processing result is combined with the second processing result to determine the type of short-circuit fault. Please refer to the schematic content of the aforementioned example, and no further explanation will be given here.

[0105] It should be noted that the reference signal at the input end of the comparator in the aforementioned example, the form and size of the signal can be determined according to actual application needs and are not limited here.

[0106] In some implementations, when processing the sampled signal, an analog-to-digital converter may be used to implement digital signal processing.

[0107] In some examples, the processing unit includes a first analog-to-digital converter and a first judgment unit, wherein the input end of the analog-to-digital converter is electrically connected to the first sampling detection unit, and the first analog-to-digital converter is used to convert the first sampling signal into a first digital signal; the first judgment unit is used to output the first processing result after judging the first digital signal with a preset first threshold.

[0108] In some examples, the processing unit includes a second analog-to-digital converter and a second judgment unit, wherein the input end of the second analog-to-digital converter is electrically connected to the second sampling detection unit, and the second analog-to-digital converter is used to convert the second sampling signal into a second digital signal; the second judgment unit is used to output the second processing result after judging the second digital signal with a preset second threshold.

[0109] In implementation, the analog-to-digital converter and the judgment unit may be in the form of independent circuits, or they may be functional circuits in a signal processing processor (such as an MCU) (they may be functional circuit units in the form of software or hardware).

[0110] The analog-to-digital conversion circuit is used to convert the sampled signal into a corresponding digital quantity, and the value of the digital quantity can reflect whether there is a short circuit fault. It should be noted that the value of the digital quantity corresponding to the short circuit fault can be set according to actual application needs and is not limited.

[0111] In implementation, the conversion bit number of the analog-to-digital conversion circuit includes at least one of the following bit numbers: 8 bits, 10 bits, 12 bits, 14 bits, 16 bits, 24 bits, etc. The circuit form of the analog-to-digital converter is not limited here.

[0112] By adopting an analog-to-digital converter, the digital value corresponding to the short-circuit fault when the motor phase line is normal, the digital value corresponding to the short-circuit fault when the motor phase line is short-circuited to the positive bus of the power supply, the digital value corresponding to the short-circuit fault when the motor phase line is short-circuited to the negative bus of the power supply, the digital value corresponding to the short-circuit fault when the motor phase lines are short-circuited, etc. can be set according to different application scenarios.

[0113] In some implementations, the operational amplifier circuit, comparator, analog-to-digital converter and other functional circuits in the aforementioned examples may be circuit units integrated in a processor, thereby forming a compact circuit form based on a signal processor.

[0114] In the implementation, the processing unit includes a microcontroller (MCU), wherein the microcontroller is a processor including a comparator and an analog-to-digital converter. It should be noted that the selection of the MCU can be determined according to actual application needs and is not limited.

[0115] Based on the same inventive concept, an embodiment of this specification also provides a motor drive controller, which can be based on the detection and protection circuit provided in any of the aforementioned embodiments to perform overcurrent detection and protection on the H-bridge.

[0116] As mentioned above Figure 2As shown, a motor drive controller includes: a detection protection circuit, a pre-driver 20 and an H-bridge 30 , wherein the detection protection circuit is electrically connected to the pre-driver 20 , the pre-driver 20 is electrically connected to the H-bridge 30 , and the load output end of the H-bridge 30 is used to connect the motor 40 .

[0117] The detection protection circuit is an H-bridge power transistor overcurrent detection protection circuit as described in any one of the embodiments of this specification, which is used to sample and detect a first current flowing from the positive bus VBAT+ of the power supply to the high-side transistor in the H-bridge 30, and sample and detect a second current flowing from the low-side transistor in the H-bridge 30 to the negative bus VBAT- of the power supply, and output a corresponding control signal (for example, Figure 2 Schematic 4-way or 6-stream PWM signal);

[0118] The pre-driver 20 is used to generate a power switch signal of the power transistor in the H-bridge 30 according to the control signal output by the detection protection circuit;

[0119] The power transistors of the H bridge 30 are driven by the power switch signal to drive the motor 40 to operate.

[0120] As described in the above examples, when a short circuit occurs in the phase line of the motor, the drive controller can detect the fault in real time and cut off the motor drive path in time to avoid the risk of the power transistor of the H-bridge being damaged or even destroyed by overcurrent shock.

[0121] For example, if the phase line is short-circuited to the positive bus VBAT+ of the power supply, the second sampling detection unit at the low side of the H-bridge will detect a large overload current, thereby promptly notifying the short-circuit fault, and then the processing unit cuts off the drive path of the motor, such as no longer outputting PWM to the pre-driver 30, so that the pre-driver 30 loses the drive of the PWM signal and no longer outputs a power switch signal to the H-bridge to drive the transistor to work, and the motor stops working. In addition, the other two types of short-circuit faults can refer to the description of the above examples and will not be described in detail.

[0122] In some embodiments, the pre-driver can be a pre-driver without drain-source overvoltage protection, that is, a pre-driver without VDS protection function can be used in the drive controller to drive the H-bridge, which can avoid the use of high-cost imported components with VDS protection function, and can also reduce the supply impact of imported components (such as bottlenecks, long cycles, chip shortages, etc.), thereby ensuring that the drive controller can be produced and delivered in an orderly manner.

[0123] In some implementations, the power transistors in the H-bridge may be power devices such as MOSFET or IGBT. It should be noted that the selection of power transistors, circuit form, etc. may be determined according to actual application needs and are not limited.

[0124] In some embodiments, the control signal output by the detection protection circuit to the pre-driver includes a PWM signal, wherein the PWM signal can be used by the pre-driver to generate a power switch signal required by the H-bridge power transistor. It should be noted that the number of paths, duty cycle, frequency and other parameters of the PWM signal can be determined according to actual application needs and are not limited.

[0125] In this specification, the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the embodiments described later, the description is relatively simple, and the relevant parts can be referred to the partial description of the previous embodiments.

[0126] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. An H-bridge power transistor overcurrent detection protection circuit, characterized in that: include: A first sampling and detection unit, a second sampling and detection unit and a processing unit; The first sampling detection unit is arranged between the high-side transistor of the H-bridge and the positive bus of the power supply, and is used for sampling and detecting the first current flowing from the positive bus of the power supply to the high-side transistor to obtain a first sampling signal; The second sampling detection unit is arranged between the low-side transistor of the H-bridge and the negative power bus, and is used for sampling and detecting the second current flowing from the low-side transistor to the negative power bus to obtain a second sampling signal; The processing unit is used to process the first sampling signal and the second sampling signal respectively to form a first processing result corresponding to the first sampling signal and a second processing result corresponding to the second sampling signal, and to generate a corresponding first drive control signal according to the first processing result and the second processing result and output it to the pre-driver, and the first drive control signal is used to generate a power switching signal of the power transistor in the H-bridge in the pre-driver.

2. The H-bridge power transistor overcurrent detection protection circuit according to claim 1, characterized in that: The processing unit is also used to determine whether the motor driven by the H-bridge has a phase line short circuit fault based on the first processing result and the second processing result, and when it is determined that the phase line short circuit fault exists, output a second drive control signal to the pre-driver, and record the fault type corresponding to the phase line short circuit fault. The second drive control signal is used to cut off the path for the pre-driver to output the drive signal to the H-bridge.

3. The H-bridge power transistor overcurrent detection protection circuit according to claim 1, characterized in that: The first sampling detection unit includes a first current sampling circuit and a first signal conditioning circuit, wherein the first current sampling circuit is connected in series between the high-side transistor of the H-bridge and the positive bus of the power supply, and is used to form a first feedback signal according to a first current flowing from the positive bus of the power supply to the high-side transistor; and the first signal conditioning circuit is used to amplify and condition the first feedback signal to output the first sampling signal to the processing unit; and / or: The second sampling detection unit includes a second current sampling circuit and a second signal conditioning circuit, wherein the second current sampling circuit is connected in series between the low-side transistor of the H-bridge and the negative power bus, and is used to form a second feedback signal according to a second current flowing from the low-side transistor to the negative power bus; and the second signal conditioning circuit is used to amplify and condition the second feedback signal to output the second sampling signal to the processing unit.

4. The H-bridge power transistor overcurrent detection protection circuit according to claim 3, characterized in that: The first current sampling circuit includes a first shunt sampler, and the first signal conditioning circuit includes a first operational amplifier, wherein the first shunt sampler is used to convert the first current into a first feedback signal in the form of a voltage signal, and the first operational amplifier is used to proportionally amplify the first feedback signal in the form of a voltage signal to form the first sampling signal in the form of a voltage signal; and / or: The second current sampling circuit includes a second shunt sampler, and the second signal conditioning circuit includes a second operational amplifier, wherein the second shunt sampler is used to convert the second current into a second feedback signal in the form of a voltage signal, and the second operational amplifier is used to proportionally amplify the second feedback signal in the form of a voltage signal to form the second sampling signal in the form of a voltage signal.

5. The H-bridge power transistor overcurrent detection protection circuit according to claim 4, characterized in that: The first current shunt sampler includes a first sampling resistor, and the first operational amplifier is used to proportionally amplify a first voltage drop on the first sampling resistor; And / or: the second current shunt sampler includes a second sampling resistor, and the second operational amplifier is used to proportionally amplify a second voltage drop on the second sampling resistor.

6. The H-bridge power transistor overcurrent detection protection circuit according to claim 1, characterized in that: The processing unit comprises a first comparator, wherein one input terminal of the first comparator is electrically connected to the first sampling detection unit, another input terminal of the first comparator inputs a first reference signal, and the first comparator is used to output the first processing result according to the difference between the first sampling signal and the first reference signal; and / or: The processing unit includes a second comparator, wherein one input end of the second comparator is electrically connected to the second sampling detection unit, and the other input end of the second comparator inputs a second reference signal, and the second comparator is used to output the second processing result according to the difference between the second sampling signal and the second reference signal.

7. The H-bridge power transistor overcurrent detection protection circuit according to claim 1, characterized in that: The processing unit includes a first analog-to-digital converter and a first judgment unit, wherein the input end of the analog-to-digital converter is electrically connected to the first sampling detection unit, the first analog-to-digital converter is used to convert the first sampling signal into a first digital signal; the first judgment unit is used to judge the first digital signal with a preset first threshold and then output the first processing result; and / or: The processing unit includes a second analog-to-digital converter and a second judgment unit, wherein the input end of the second analog-to-digital converter is electrically connected to the second sampling detection unit, and the second analog-to-digital converter is used to convert the second sampling signal into a second digital signal; the second judgment unit is used to output the second processing result after judging the second digital signal with a preset second threshold.

8. The H-bridge power transistor overcurrent detection protection circuit according to any one of claims 1 to 7, characterized in that: The processing unit includes a microcontroller, which is a processor including a comparator and an analog-to-digital converter.

9. A motor drive controller, characterized in that: include: A detection protection circuit, a pre-driver and an H-bridge, wherein the detection protection circuit is electrically connected to the pre-driver, the pre-driver is electrically connected to the H-bridge, and a load output end of the H-bridge is used to connect to a target motor; The detection protection circuit is an H-bridge power transistor overcurrent detection protection circuit as claimed in any one of claims 1 to 8, which is used to sample and detect a first current flowing from a positive bus of a power supply to a high-side transistor in the H-bridge, and to sample and detect a second current flowing from a low-side transistor in the H-bridge to a negative bus of a power supply, and output a corresponding control signal to the pre-driver after processing the first current and the second current; The pre-driver is used to generate a power switch signal of the power transistor in the H-bridge according to the control signal output by the detection protection circuit; The power transistors in the H-bridge drive the target motor to operate under the drive of the power switch signal.

10. The motor drive controller according to claim 9, characterized in that: The pre-driver is a pre-driver without drain-source overvoltage protection; And / or, the transistors in the H-bridge are MOSFETs or IGBTs; And / or, the control signal output by the detection protection circuit to the pre-driver includes a PWM signal.

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