Motor driving circuit based on current reconstruction and hardware rapid protection

Abstract

A motor drive circuit based on current reconstruction and hardware rapid protection belongs to the field of motor drive and control, the circuit comprises a current sampling module, a current reconstruction module, a microcontroller, a power drive module and a hardware rapid protection module, the current sampling module is used for sampling any two-phase current in real time and outputting a corresponding analog voltage signal; the current reconstruction module adopts an analog summing circuit formed by an operational amplifier to perform reverse-phase summation on two-phase analog voltage signals and reconstruct an analog voltage signal corresponding to residual phase current in real time, and the hardware rapid protection module is independent of the microcontroller and monitors current analog signals in real time through a voltage comparator, so that the residual phase current can be detected in real time. And when the current exceeds a set threshold value, a turn-off signal is directly output to the power driving module, microsecond-level rapid protection is realized, and the real-time performance of current detection and the reliability of system overcurrent protection are remarkably improved while the cost and complexity of the system are reduced.

Description

Technical Field

[0001] This invention relates to a motor drive circuit based on current reconstruction and rapid hardware protection, belonging to the field of motor drive and control. Background Technology

[0002] In modern motor drive systems, such as servo drives, frequency converters, and electric vehicle controllers, accurate phase current detection and reliable overcurrent protection are the cornerstones for ensuring high performance, high efficiency, and safe and stable operation of the system.

[0003] In current sensing, to implement advanced algorithms such as vector control, the controller needs to acquire high-precision three-phase current information in real time. Traditional direct sampling schemes require current sensors (such as Hall sensors or sampling resistors) to be placed on the lower arm of the three-phase bridge arm or on all three phase lines of the motor. This not only increases the material cost and circuit board area of ​​the system but also increases the complexity of wiring. To reduce costs, the industry has proposed a "two-phase sampling, third-phase reconstruction" scheme, which samples only two phase currents and calculates the third phase current using Kirchhoff's current law (the sum of the three phase currents is zero). However, existing reconstruction schemes are mostly completed in the digital domain of the microcontroller through software calculation. Their accuracy and real-time performance are limited by the sampling rate and resolution of the analog-to-digital converter (ADC) and the software processing delay. Errors may be introduced when the dynamic load changes drastically, affecting control performance.

[0004] In terms of overcurrent protection, a fast and effective protection mechanism is essential to prevent damage from motor stall, short circuits, or overload of controller power devices. Currently, common protection schemes primarily rely on microcontroller software protection: sampling the current value using an ADC and comparing it to a set threshold in software. If the threshold is exceeded, the PWM output is shut down via software. The response speed of this scheme is limited by the ADC sampling period, interrupt response time, and software processing flow, typically requiring tens to hundreds of microseconds. In the event of severe short circuits or other faults, this delay can lead to irreversible damage to power devices before protection action. Although some simple hardware comparison circuits exist, they typically directly monitor the unprocessed raw sampled signal, are susceptible to noise interference, and are difficult to integrate with the aforementioned two-phase sampling-based current reconstruction system, thus failing to provide fast protection for the reconstructed third-phase current. Utility Model Content

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a motor drive circuit based on current reconstruction and rapid hardware protection. This addresses the technical problem that existing technologies cannot simultaneously provide rapid hardware overcurrent protection for the reconstructed phase in motor drive systems that use two-phase sampling to reconstruct three-phase current, thus creating a contradiction between cost reduction and ensuring system safety.

[0006] To achieve the above objectives, this utility model provides a motor drive circuit based on current reconstruction and rapid hardware protection, comprising:

[0007] The current sampling module samples the phase current of any two phases in the three-phase motor in real time and outputs a first analog voltage signal and a second analog voltage signal corresponding to the two phase currents, respectively.

[0008] A current reconstruction module is connected to the output of the current sampling module and generates a third analog voltage signal corresponding to the remaining phase current based on the first analog voltage signal and the second analog voltage signal received by the module.

[0009] The microcontroller is used to receive the analog voltage signal generated by the current sampling module and the current reconstruction module, and participate in the generation of PWM control signal;

[0010] A hardware fast protection module, whose input terminal is connected to the output terminal of the current sampling module and / or the current reconstruction module, is used to monitor at least one of the analog voltage signals in real time, and output a shutdown signal when the voltage value exceeds a preset threshold.

[0011] Furthermore, it also includes a power drive module for receiving the PWM control signal to drive the three-phase motor, and the shutdown signal output by the hardware fast protection module is connected to the power drive module for cutting off the drive in case of overcurrent.

[0012] Furthermore, the current sampling module consists of two sampling units, each of which includes a sampling resistor connected in series in the corresponding phase current path, a differential amplifier, and a differential amplifier circuit connected to both ends of the overall structure of the differential amplifier and the sampling resistor.

[0013] Furthermore, the differential amplifier circuit acquires the differential voltage drop signal generated across the corresponding sampling resistor and outputs an analog voltage signal that is proportional to the phase current flowing through the sampling resistor.

[0014] Furthermore, the current reconstruction module includes an adder circuit, which is composed of an operational amplifier, for inverting and summing the first analog voltage signal and the second analog voltage signal to output the third analog voltage signal.

[0015] Furthermore, the adder circuit includes a first input resistor, a second input resistor, and a feedback resistor. The first input resistor and the second input resistor are connected between the corresponding phase current sampling signal and the inverting input terminal of the operational amplifier. The non-inverting input terminal of the operational amplifier is connected to a DC bias voltage source via a resistor. The voltage source is 3.3V. The feedback resistor is connected between the inverting input terminal of the operational amplifier and the output terminal of the adder circuit.

[0016] Furthermore, the hardware fast protection module includes a threshold setting unit, a voltage comparator, and a logic control circuit. The voltage comparator compares at least one of the analog voltage signals with a reference voltage provided by the threshold setting unit, and outputs a trigger signal when the analog voltage signal exceeds the reference voltage. The logic control circuit receives the trigger signal and generates a shutdown signal to block the PWM signal.

[0017] Furthermore, the shutdown signal generated by the logic control circuit is transmitted to the power drive module to cut off its output.

[0018] Furthermore, the hardware fast protection module also includes a fault signal reporting circuit, which outputs a fault indication signal to the microcontroller at the same time as outputting the shutdown signal.

[0019] The beneficial effects of this utility model are:

[0020] This application employs a two-phase sampling and adder reconstruction scheme, which effectively reduces system cost and complexity while ensuring the acquisition of complete three-phase current information. Specifically, the current sampling module only needs to directly measure the U and V phases, omitting the third-phase sensor and related signal chain, thus saving hardware resources. The current reconstruction module utilizes an analog adder circuit composed of operational amplifiers to reconstruct the W-phase current in real time in the analog signal domain, completely avoiding the unavoidable ADC sampling delay and digital computation overhead in traditional software reconstruction methods, thereby significantly improving the real-time performance and dynamic response of the current feedback loop.

[0021] In addition, this application introduces a hardware fast protection module that is completely independent of the microcontroller. This module continuously and directly monitors the analog voltage signal that represents the current through a voltage comparator and compares it with a preset threshold at high speed. Once an overcurrent is detected, the generated shutdown signal can be directly sent to the shutdown pin of the power drive module within a few microseconds, instantly cutting off the drive output. This provides microsecond-level ultimate protection for the power switching device and greatly avoids device damage caused by protection delay in serious faults such as short circuits.

[0022] In summary, this application ingeniously integrates a low-cost two-phase reconfiguration architecture with a nanosecond-level response hardware protection channel, successfully solving the industry challenge of ensuring control performance and operational safety while reducing system costs. This circuit not only reduces material costs but also achieves significant improvements in dynamic response speed and system reliability. Attached Figure Description

[0023] Other features, objects, and advantages of this invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0024] Figure 1 This is a schematic diagram of the structure of a motor drive circuit based on current reconstruction and hardware fast protection according to this utility model;

[0025] Figure 2 This is a schematic diagram of the circuit for U-phase data acquisition in this utility model;

[0026] Figure 3 This is a schematic diagram of the differential amplifier circuit for U-phase acquisition in this utility model;

[0027] Figure 4 This is a schematic diagram of the V-phase acquisition circuit in this utility model;

[0028] Figure 5 This is a schematic diagram of the differential amplifier circuit for V-phase acquisition in this utility model;

[0029] Figure 6 This is a circuit diagram of the current reconstruction module in this utility model;

[0030] Figure 7 This is a schematic diagram of the process structure of the hardware rapid protection module in this utility model.

[0031] The reference numerals in the attached figures are as follows:

[0032] 1. Current sampling module; 2. Current reconstruction module; 3. Microcontroller; 4. Power drive module; 5. Hardware fast protection module. Detailed Implementation

[0033] To make the technical means, creative features, objectives and effects of this utility model easier to understand, the present utility model will be further described below in conjunction with specific embodiments.

[0034] Reference Figure 1 As shown, this application provides a technical solution for a motor drive circuit based on current reconstruction and hardware fast protection, which includes a current sampling module 1, a current reconstruction module 2, a microcontroller 3, a power drive module 4, and a hardware fast protection module 5.

[0035] 1. Current sampling module 1:

[0036] This module is used to acquire phase current information of the motor in real time with high precision. It only needs to directly measure two phases. In this embodiment, the U phase and V phase are selected for direct sampling.

[0037] 1. U-phase sampling:

[0038] Reference Figure 2 As shown, the U-phase sampling unit uses an integrated current sensing chip IC5 with model number CC6921SO-100A. The current path of the sensing chip IC5 adopts a multi-pin parallel design to carry large current. Its pins 1 to 4 serve as the positive current input terminal IP+, which are connected to the source node U1 of the power transistor of the upper bridge arm of the U-phase; its pins 5 to 8 serve as the negative current input terminal IP-, which are connected to the input terminal U of the U-phase winding of the motor. The U-phase current to be measured flows into the chip through this path. It should be noted that the NC pins 9, NC pin 11, NC pin 14, and NC pin 16 of this chip do not need to be connected.

[0039] The VOUT pin 12 of the sensor chip IC5 is used as the positive terminal of the differential output, outputting the signal DU+; the VZCR pin 13 is used as the zero current reference terminal, outputting the signal DU-. DU+ and DU- form a differential analog voltage pair proportional to the sampling current, which is sent to the subsequent differential amplifier circuit.

[0040] To improve sampling accuracy and anti-interference capabilities, a filter capacitor C98 is connected in parallel between DU+ and DU- to filter out high-frequency common-mode noise on the differential signal line. Simultaneously, a capacitor C97 is connected in parallel between the DU- signal line and analog ground, forming a differential signal filtering network together with the filter capacitor C98. This further suppresses common-mode interference and smooths the zero-current reference voltage, ensuring the integrity and accuracy of the differential signal. The chip's power supply pin VCC10 is connected to a +5V DC power supply, providing energy to internal signal conditioning and amplification circuits. It is also connected to analog ground (labeled 5G, i.e., analog signal ground, used to distinguish between power ground and signal ground, preventing large currents in the power loop from interfering with the analog sampling circuit) via a power supply decoupling capacitor C101. This decoupling capacitor C101 effectively filters out power supply ripple and high-frequency noise, providing a clean and stable operating voltage for the chip, improving sampling accuracy and circuit anti-interference capabilities. The chip's GND pin 15 is directly connected to analog ground 5G, providing a stable zero-potential reference for the internal analog circuits, ensuring normal chip operation.

[0041] Reference Figure 3 As shown, the U-phase sampling unit includes a sampling resistor connected in series in the corresponding phase current path, and a differential amplifier circuit connected across the sampling resistor:

[0042] The U-phase differential amplifier circuit is based on an operational amplifier IC10A. Its non-inverting input pin 3 receives the positive differential output signal DU+ from the U-phase current sensor via resistor R102, and its inverting input pin 2 receives the negative differential output signal DU- via resistor R100. Furthermore, a feedback resistor R99 is connected between the inverting input pin 2 and the output IU of the operational amplifier. Together with resistor R100, the feedback resistor R99 sets the closed-loop gain of the circuit.

[0043] On the differential signal input path, capacitor C96 is connected in parallel with resistor R100, and capacitor C100 is connected in parallel with resistor R102, forming two RC low-pass filter stages to suppress high-frequency interference on the DU+ and DU- signal lines and prevent noise from entering the operational amplifier and affecting amplification accuracy. At the same time, the non-inverting input pin 3 is also connected to a 3.3V DC bias voltage through resistor R103 to provide a suitable common-mode bias potential for the differential amplifier circuit, so that the output signal IU can be adapted to the voltage range of the subsequent single-ended sampling circuits such as the ADC.

[0044] Among them, pin 4 and pin 11 of the operational amplifier IC10A are the positive and negative power supply terminals, respectively. Pin 4 is connected to the +15V positive power supply and pin 11 is connected to the -15V negative power supply, providing a symmetrical bipolar operating voltage for the internal circuit of the operational amplifier, ensuring that it stably amplifies differential signals in a wide dynamic range, while meeting the linear amplification requirements for positive and negative current signals.

[0045] In the feedback branch, capacitor C93 and feedback resistor R99 are connected in parallel to form a lead-lag compensation network. On the one hand, it is used for phase compensation to improve closed-loop stability and prevent circuit self-oscillation. On the other hand, it can suppress high-frequency noise, avoid high-frequency interference being amplified through the feedback path, and further optimize the smoothness of the output signal.

[0046] The differential amplifier circuit linearly amplifies the small differential voltage drop signal output by the current sensor and converts it into a single-ended analog voltage signal IU that is ground-referenced and proportional to the U-phase current. At pin 1 of the operational amplifier IC10A, an RC low-pass filter network consisting of resistor R101 and capacitor C99 is used to further filter out high-frequency switching noise, ultimately outputting a clean and stable U-phase analog voltage signal IU.

[0047] 2. V-phase sampling:

[0048] Reference Figure 4 and Figure 5As shown, the V-phase sampling unit is consistent with the aforementioned U-phase sampling unit in terms of circuit structure and working principle: its current path is connected in series in the V-phase drive circuit, the input terminal of the differential amplifier circuit is connected to the V-phase signal (such as DV+ and DV-), and the output terminal generates a single-ended analog voltage signal IV proportional to the V-phase current. By adopting a circuit structure that is completely consistent with the U-phase, it is beneficial to ensure that the gain, bandwidth and temperature characteristics of the two-phase sampling channels are matched, thereby improving the calculation accuracy of subsequent current reconstruction and simplifying system design and debugging. The specific circuit structure is as follows:

[0049] Reference Figure 4 As shown, the V-phase sampling unit uses an integrated current sensing chip of model CC6921SO-100A. The current path of the sensing chip IC7 adopts a multi-pin parallel design to carry large current. Its pins 1 to 4 are used as the positive current input terminals IP+, which are connected to the source node V1 of the V-phase upper bridge arm power transistor; its pins 5 to 8 are used as the negative current input terminals IP-, which are connected to the input terminal V of the motor V-phase winding. The V-phase current to be measured flows into the chip through this path. It should be noted that the NC pins 9, NC pin 11, NC pin 14, and NC pin 16 of this chip do not need to be connected.

[0050] The VOUT pin 12 of the sensor chip IC7 is used as the positive terminal of the differential output, outputting the signal DV+; the VZCR pin 13 is used as the zero current reference terminal, outputting the signal DV-. DV+ and DV- form a differential analog voltage pair that is proportional to the sampling current and are sent to the subsequent differential amplifier circuit.

[0051] To improve sampling accuracy and anti-interference capabilities, a filter capacitor C104 is connected in parallel between DV+ and DV- to filter out high-frequency common-mode noise on the differential signal line. Simultaneously, a capacitor C103 is connected in parallel between the DV- signal line and analog ground, forming a differential signal filtering network together with the filter capacitor C104. This further suppresses common-mode interference and smooths the zero-current reference voltage, ensuring the integrity and accuracy of the differential signal. The chip's power supply pin VCC10 is connected to a +5V DC power supply, providing energy to internal signal conditioning and amplification circuits. It is also connected to analog ground (marked 5G, analog signal ground, used to distinguish between power ground and signal ground, preventing large currents in the power loop from interfering with the analog sampling circuit) via a power supply decoupling capacitor C105. This decoupling capacitor C105 effectively filters out power supply ripple and high-frequency noise, providing a clean and stable operating voltage for the chip, improving sampling accuracy and circuit anti-interference capabilities. The chip's GND pin 15 is directly connected to analog ground 5G, providing a stable zero-potential reference for the internal analog circuits, ensuring normal chip operation.

[0052] Reference Figure 5As shown, the V-phase sampling unit includes a sampling resistor connected in series in the corresponding phase current path, and a differential amplifier circuit connected across the sampling resistor:

[0053] The V-phase differential amplifier circuit is based on an operational amplifier IC10B. Its non-inverting input pin 5 receives the positive differential output signal DV+ from the V-phase current sensor via resistor R107, and its inverting input pin receives the negative differential output signal DV- via resistor R105 via pin 6. Furthermore, a feedback resistor R104 is connected between the inverting input pin 6 and the output pin IV of the operational amplifier. Together with resistor R107, the feedback resistor R104 sets the closed-loop gain of the circuit.

[0054] On the differential signal input path, capacitor C106 is connected in parallel with resistor R108, and capacitor C108 is connected in parallel with resistor R107, forming two RC low-pass filter stages to suppress high-frequency interference on the DV+ and DV- signal lines and prevent noise from entering the operational amplifier and affecting amplification accuracy. At the same time, the non-inverting input pin 5 is also connected to a 3.3V DC bias voltage through resistor R108 to provide a suitable common-mode bias potential for the differential amplifier circuit, so that the output signal IV can be adapted to the voltage range of the subsequent single-ended sampling circuits such as the ADC.

[0055] In the feedback branch, capacitor C102 and feedback resistor R104 are connected in parallel to form a lead-lag compensation network. On the one hand, it is used for phase compensation to improve closed-loop stability and prevent circuit self-oscillation. On the other hand, it can suppress high-frequency noise, avoid high-frequency interference being amplified through the feedback path, and further optimize the smoothness of the output signal.

[0056] The differential amplifier circuit linearly amplifies the small differential voltage drop signal output by the current sensor and converts it into a single-ended analog voltage signal IV that is ground-referenced and proportional to the V-phase current. At pin 7 of the operational amplifier IC10B, an RC low-pass filter network consisting of resistor R106 and capacitor C107 is used to further filter out high-frequency switching noise, ultimately outputting a clean and stable V-phase analog voltage signal IV.

[0057] 2. Current Reconstruction Module 2:

[0058] This module is used to perform real-time calculations on the two-phase analog voltage signals from current sampling module 1 in the analog signal domain, based on Kirchhoff's current law, to reconstruct the analog voltage signal of the third-phase current. Specifically, it includes an adder circuit, as shown in the reference... Figure 6 As shown, the specific structure and connection relationship of the adder circuit are as follows:

[0059] The inverting input pin 9 of the operational amplifier is a summing node. A first input resistor R110 is connected between the U-phase analog voltage signal and the inverting input pin 9 of the operational amplifier. A second input resistor R111 is connected between the V-phase analog voltage signal and the inverting input pin 9 of the operational amplifier. A feedback resistor R109 is connected between the inverting input pin 9 of the operational amplifier and the W-phase analog voltage signal output terminal IW. The output pin 8 of the operational amplifier is connected to the W-phase analog voltage signal output terminal IW through an output resistor R112. A filter capacitor C109 is connected between the output terminal IW and analog ground 5G. The feedback resistor R109, along with the first input resistor R110 and the second input resistor R111, together set the closed-loop gain of the circuit.

[0060] The non-inverting input pin 10 of the operational amplifier is connected to a reference voltage source (e.g., 3.3V) through a bias resistor R113 to provide a stable DC bias operating point for the output signal, ensuring that it is within the appropriate input range of subsequent circuits (e.g., ADC).

[0061] Furthermore, at the output pin 8 of the operational amplifier, an output resistor R112 is connected in series and a filter capacitor C109 is connected in parallel to the analog ground, forming an RC low-pass filter network to filter out high-frequency switching noise in the output signal, improve signal quality, and finally output a smooth W-phase analog voltage signal IW.

[0062] This approach completely avoids the sampling and computation delays caused by software reconfiguration of the microcontroller 3, significantly improving the real-time performance and dynamic response of the system control.

[0063] 3. Microcontroller 3:

[0064] As the digital control core of the entire circuit, the microcontroller 3 integrates analog-to-digital converter pins to sample the three analog voltage signals IU, IV, and IW representing the three-phase current, convert them into digital quantities, and combine them with algorithms such as field-oriented control. Based on these digital quantities and position estimation, the microcontroller calculates a precise PWM control signal and sends it to the power drive module 4. At the same time, the MCU receives fault indication signals from the hardware fast protection module 5 and performs fault recording and system management.

[0065] 4. Power drive module 4:

[0066] The core function of this module is to convert the low-voltage, low-current logic-level PWM signal output by the microcontroller 3 into a high-voltage, high-current power signal that can directly drive the windings of a three-phase motor.

[0067] Furthermore, the dedicated fault protection pin of the power drive module 4 is directly connected to the output of the hardware fast protection module 5. When the hardware protection is triggered, the generated shutdown signal is sent directly to the power drive module 4 through this pin, thereby immediately causing its internal gate driver to enter the protection state, blocking all PWM outputs, and putting all power transistors into the shutdown state, thereby achieving the fastest fault isolation and system protection, and thus protecting the power devices under severe overcurrent or short circuit faults.

[0068] 5. Hardware Fast Protection Module 5:

[0069] Reference Figure 7 As shown, the hardware fast protection module 5 serves as a key safety barrier in this drive circuit. Its core design goal is to achieve overcurrent protection that is independent of the microcontroller 3 software and has a response speed at the microsecond level, thereby providing the last and fastest protection for power devices.

[0070] The core of this module consists of a threshold setting unit and a voltage comparator, forming a complete analog comparison channel:

[0071] The threshold setting unit is used to generate two stable reference voltages, Vref+ and Vref-, which correspond to the overcurrent protection threshold set by the system. For example, this unit can be implemented by dividing the system reference power supply with several resistors. The protection point can be flexibly set by selecting the resistor ratio.

[0072] The voltage comparator can perform protection judgments in real time. One of its input terminals is connected to the monitored analog voltage signal path (this signal comes from the output of the current sampling module 1 or the current reconstruction module 2, representing the real-time current of a certain phase), and the other input terminal is connected to the reference voltages Vref+ and Vref- provided by the threshold setting unit. Its protection working principle is as follows: The voltage comparator continuously compares the voltages at its two input terminals at high speed: Under normal operating conditions, when the analog voltage signal representing the current is lower than the reference voltage Vref+ and higher than the reference voltage Vref-, the comparator output remains normal (such as high level). Once the motor experiences faults such as stall or short circuit, the current of the monitored phase rises sharply, and the corresponding analog voltage signal also rises accordingly. When the signal voltage value exceeds (or reaches, depending on the circuit design) the preset reference voltages Vref+ and Vref-, the output state of the voltage comparator will flip in a very short time (usually hundreds of nanoseconds to several microseconds), thereby generating an effective shutdown signal.

[0073] After being generated by the logic control circuit, the shutdown signal is sent directly to the power drive module 4 to block the PWM signal. This direct connection means that the shutdown path completely bypasses the MCU's software processing flow. Once the shutdown signal takes effect, it will immediately force the gate driver inside the power drive module 4 into a protection state, blocking all PWM outputs and turning off all power transistors, thereby physically cutting off the motor's drive current.

[0074] Furthermore, to further enhance system management functions, the hardware fast protection module 5 can also integrate a fault signal reporting circuit. This circuit generates a logic level signal (i.e., a fault indication signal) simultaneously with the voltage comparator outputting a shutdown signal, and sends it to the external interrupt pin of the microcontroller 3. This allows the microcontroller 3 to almost synchronously detect the triggered hardware protection status, thereby enabling it to promptly interrupt the current task and perform a series of operations such as fault recording, status saving, and system shutdown management, achieving effective coordination between the hardware fast protection and the microcontroller 3 management system.

[0075] In summary, this application provides a complete preferred solution for a motor drive circuit based on current reconfiguration and hardware fast protection. This solution achieves current reconfiguration and fast protection through the organic synergy of various modules and through pure hardware circuitry, significantly improving the system's real-time performance, dynamic performance, and operational reliability, while effectively controlling the overall cost.

[0076] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. It will be apparent to those skilled in the art that this utility model is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or basic characteristics of this utility model. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of this utility model is defined by the appended claims rather than the foregoing description, and thus all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this utility model. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0077] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A motor drive circuit based on current reconstruction and fast hardware protection, characterized in that: It includes: The current sampling module (1) samples the phase current of any two phases in the three-phase motor in real time and outputs the first analog voltage signal and the second analog voltage signal corresponding to the two phase currents respectively. The current reconstruction module (2) is connected to the output terminal of the current sampling module (1) and generates a third analog voltage signal corresponding to the remaining phase current based on the first analog voltage signal and the second analog voltage signal received by it. The microcontroller (3) is used to receive the analog voltage signal generated by the current sampling module (1) and the current reconstruction module (2) and participate in the generation of PWM control signal; The hardware fast protection module (5) has its input terminal connected to the output terminal of the current sampling module (1) and / or the current reconstruction module (2) for real-time monitoring of at least one of the analog voltage signals, and outputting a shutdown signal when its voltage value exceeds a preset threshold.

2. The motor drive circuit based on current reconstruction and fast hardware protection according to claim 1, characterized in that: It also includes a power drive module (4) for receiving the PWM control signal to drive the three-phase motor. The shutdown signal output by the hardware fast protection module (5) is connected to the power drive module (4) to cut off the drive in case of overcurrent.

3. The motor drive circuit based on current reconstruction and fast hardware protection according to claim 1, characterized in that: The current sampling module (1) consists of two sampling units. Each sampling unit includes a sampling resistor connected in series in the corresponding phase current path, a differential amplifier, and a differential amplifier circuit connected to both ends of the overall structure of the differential amplifier and the sampling resistor.

4. A motor drive circuit based on current reconstruction and fast hardware protection according to claim 3, characterized in that: The differential amplifier circuit acquires the differential voltage drop signal generated across the corresponding sampling resistor and outputs an analog voltage signal that is proportional to the phase current flowing through the sampling resistor.

5. A motor drive circuit based on current reconstruction and fast hardware protection according to claim 4, characterized in that: The current reconstruction module (2) includes an adder circuit, which is composed of an operational amplifier and is used to sum the first analog voltage signal and the second analog voltage signal in reverse phase to output the third analog voltage signal.

6. A motor drive circuit based on current reconstruction and fast hardware protection according to claim 5, characterized in that: The adder circuit includes a first input resistor, a second input resistor, and a feedback resistor. The first input resistor and the second input resistor are connected between the corresponding phase current sampling signal and the inverting input terminal of the operational amplifier. The non-inverting input terminal of the operational amplifier is connected to a DC bias voltage source via a resistor. The feedback resistor is connected between the inverting input terminal of the operational amplifier and the output terminal of the adder circuit.

7. A motor drive circuit based on current reconstruction and fast hardware protection according to claim 1, characterized in that: The hardware fast protection module (5) includes a threshold setting unit, a voltage comparator and a logic control circuit. The voltage comparator compares at least one of the analog voltage signals with the reference voltage provided by the threshold setting unit, and outputs a trigger signal when the analog voltage signal exceeds the reference voltage. The logic control circuit receives the trigger signal and generates a shutdown signal to block the PWM signal.

8. A motor drive circuit based on current reconstruction and fast hardware protection according to claim 7, characterized in that: The shutdown signal generated by the logic control circuit is transmitted to the power drive module (4) to cut off its output.

9. A motor drive circuit based on current reconstruction and fast hardware protection according to claim 7, characterized in that: The hardware fast protection module (5) also includes a fault signal reporting circuit, which outputs a fault indication signal to the microcontroller (3) while outputting the shutdown signal.

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