Single-resistor time-sharing sampling-based EPS motor current monitoring method and system

Abstract

The application discloses an EPS motor current monitoring method based on single-resistance time-sharing sampling, relates to the technical field of electric power steering control, and comprises the following steps: sampling two-phase currents flowing through a single sampling resistor respectively; wherein the single sampling resistor is arranged on an inverter bridge DC bus; in a PWM period, the conduction combination of three-phase MOS tubes of the inverter bridge is controlled, so that the two-phase currents of the motor flow through the single sampling resistor in a time-sharing mode, and the two-phase currents are time-sharing sampled in a non-zero vector state; and according to the two-phase currents, a third-phase current is calculated according to the Kirchhoff's current law. The monitoring and time sequence control strategy of the three-phase motor current are realized through single-resistance time-sharing sampling, and the method is suitable for the design of an EPS controller meeting the safety level requirement.

Description

Technical Field

[0001] This invention relates to the field of electric power steering control technology, and in particular to an EPS motor current monitoring method and system based on time-division sampling of a single resistor. Background Technology

[0002] Traditional EPS (Electric Power Steering) controllers, to achieve precise vector control of brushless DC motors, typically use a precision shunt resistor connected in series on each of the three bridge arms for independent current sensing. This traditional approach employs a three-resistor sampling topology, requiring three precision shunt resistors and three independent signal chains, resulting in hardware redundancy and a large PCB footprint. Furthermore, the multi-resistor layout leads to uneven local temperature rise, affecting sampling accuracy. While a dual-resistor method has been proposed, it reduces the number of components, but increases phase current reconstruction errors, failing to meet safety requirements. Summary of the Invention

[0003] To address the aforementioned issues, this invention proposes an EPS motor current monitoring method and system based on single-resistor time-division sampling. This method achieves monitoring and timing control strategies for three-phase motor current through single-resistor time-division sampling, and is suitable for EPS controller designs that meet safety level requirements.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides an EPS motor current monitoring method based on single-resistor time-division sampling, comprising: The two-phase current flowing through the single sampling resistor is sampled separately. The single sampling resistor is set on the DC bus of the inverter bridge. Within one PWM cycle, the two-phase current of the motor flows through the single sampling resistor in a time-sharing manner by controlling the conduction combination of the three-phase MOSFETs of the inverter bridge, so as to sample the two-phase current in a time-sharing manner under non-zero vector state. Based on the two-phase currents, the third-phase current is calculated according to Kirchhoff's current law.

[0005] As an alternative implementation, one end of the single sampling resistor is connected to the common convergence node of the source of the inverter bridge power transistor to receive the current flowing out of the inverter bridge; the other end serves as the current sampling signal output terminal and is directly connected to the subsequent signal conditioning module.

[0006] As an alternative implementation, the signal conditioning module includes an operational amplifier and an ADC sampling module. The input of the operational amplifier is connected to a single sampling resistor to receive the sampled current and perform amplification and filtering. The output of the operational amplifier is connected to the ADC sampling module to perform analog-to-digital signal conversion.

[0007] As an alternative implementation, during the sampling process, the sampling action at the non-zero vector is initiated by counting the PWM cycles and when the count reaches half a PWM cycle.

[0008] As an alternative implementation, the switching state combination of the three-phase MOSFETs of the inverter bridge is defined as a switching combination vector, where [000,111] is the zero vector and the other combinations are non-zero vectors. Current sampling is performed only at the non-zero switching combination vectors, and no sampling is performed at the zero vector stage.

[0009] As an alternative implementation, the space vector pulse width modulation is divided into six sectors, each sector corresponding to a different combination of non-zero vectors, and each sector has an ADC sampling point set at a specified non-zero vector point to capture the two-phase current in that sector.

[0010] Secondly, the present invention provides an EPS motor current monitoring system based on single-resistor time-division sampling, comprising: The sampling module is configured to sample the two-phase current flowing through the single sampling resistor. The single sampling resistor is set on the DC bus of the inverter bridge. Within one PWM cycle, by controlling the conduction combination of the three-phase MOSFETs of the inverter bridge, the two-phase current of the motor flows through the single sampling resistor in a time-sharing manner, so as to sample the two-phase current in a time-sharing manner under non-zero vector state. The calculation module is configured to calculate the third phase current based on the two phase currents and Kirchhoff's current law.

[0011] Thirdly, the present invention provides an electronic device including a memory and a processor, and computer instructions stored in the memory and running on the processor, wherein the computer instructions, when executed by the processor, perform the method described in the first aspect.

[0012] Fourthly, the present invention provides a computer-readable storage medium for storing computer instructions, which, when executed by a processor, perform the method described in the first aspect.

[0013] Fifthly, the present invention provides a computer program product, including a computer program that, when executed by a processor, implements the method described in the first aspect.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention proposes an EPS motor current monitoring method and system based on single-resistor time-division sampling. By using single-resistor time-division sampling, it achieves monitoring and timing control strategies for three-phase motor current, simplifying the hardware structure, reducing costs, optimizing PCB layout, and solving the hardware redundancy problem of traditional multi-resistor solutions. Within one PWM cycle, the conduction combination of the three-phase MOSFETs in the inverter bridge is controlled, allowing two-phase motor currents to flow through the single sampling resistor in a time-division manner. Accurate time-division sampling of the two-phase current is achieved in a non-zero vector state. The third-phase current is then calculated based on Kirchhoff's current law. Compared to the current reconstruction method of the dual-resistor solution, this effectively avoids reconstruction errors caused by factors such as operating conditions, component deviations, and interference.

[0015] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0017] Figure 1 This is a flowchart of the EPS motor current monitoring method based on single-resistor time-division sampling provided in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the sampling resistor connection provided in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of current transmission through a sampling resistor provided in Embodiment 1 of the present invention; Figure 4 This is a schematic diagram of the spatial vector pulse width modulation wave of sector one provided in Embodiment 1 of the present invention; Figure 5 This is a schematic diagram of the spatial vector pulse width modulation wave of different sectors provided in Embodiment 1 of the present invention. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0019] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0020] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form as well. Furthermore, it should be understood that the terms “comprising” and “including”, and any variations thereof, are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0021] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0022] Example 1 As a core module of the automotive chassis electronic control system, the Electric Power Steering (EPS) system outputs auxiliary steering torque through a brushless DC motor (BLDC), directly affecting the vehicle's handling stability and driving safety. Real-time and accurate detection of the three-phase stator current is a crucial prerequisite for achieving high-precision vector control (FOC) of the motor. Precise phase current data is not only the foundation for field orientation and torque closed-loop regulation, but also a key basis for EPS system fault diagnosis and overcurrent protection, directly determining the smoothness of the power steering characteristics and the system's functional safety level.

[0023] In traditional EPS controller current sensing schemes, the three-phase bridge arm independent sampling topology (three-resistor sampling method) is the mainstream technical solution for realizing vector control of brushless DC motors. This scheme connects a shunt resistor in series between the source terminal and ground of each of the three-phase bridge arms of the inverter. By sampling the voltage drop across the resistors and applying Ohm's law, the real-time current of the corresponding phase is calculated. To ensure sampling accuracy, this topology requires three independent signal processing links, each containing core components such as a precision operational amplifier (e.g., INA240) and an anti-aliasing filter. Finally, the conditioned current signal is transmitted to a microcontroller (MCU) for algorithm processing.

[0024] However, the traditional three-resistor sampling scheme has significant technical bottlenecks in engineering applications, making it difficult to adapt to the current development trend of miniaturization, high integration, and high safety levels in EPS controllers: First, it has high hardware resource redundancy and is difficult to integrate. The scheme requires three high-precision shunt resistors and three complete signal chains, which not only significantly increases the cost of component procurement but also occupies a large amount of PCB layout space, contradicting the design requirements of small size and high power density for vehicle controllers; Second, the sampling accuracy is easily affected by thermal characteristics. The distributed layout of the three shunt resistors on the PCB is prone to uneven local temperature rise due to power loss during operation. The resistance value of precision resistors has temperature drift characteristics, and temperature rise differences will directly introduce sampling errors. Under high motor load conditions, this error will be amplified, thereby reducing the accuracy of vector control and affecting the smoothness of power steering; Third, the fault tolerance capability is limited. The existence of multiple signal chains also increases the probability of single-point failure, placing higher demands on the redundancy design of system functional safety.

[0025] To address the hardware redundancy issue of the three-resistor method, the industry has proposed an optimization approach: the dual-resistor sampling method. This solution eliminates one shunt resistor, retaining only the current sampling branches of two-phase bridge arms. It leverages the electrical characteristic of a brushless DC motor where the instantaneous sum of the three-phase currents is zero, to deduce the third-phase current from the known two-phase currents. While the dual-resistor method effectively reduces the number of shunt resistors, operational amplifiers, and other components, simplifying PCB layout, it also introduces new technical challenges: the algorithm error for phase current reconstruction increases significantly during motor commutation or under low switching duty cycles, making accurate current detection under all operating conditions impossible. Furthermore, as an automotive safety-related component, the EPS system must meet relevant functional safety standards. The reconstruction error of the dual-resistor method is ill-suited to the system's requirements for current detection accuracy and fault diagnosis reliability, thus preventing its widespread application in high-safety-level EPS controllers.

[0026] In summary, the hardware redundancy and accuracy shortcomings of the traditional three-resistor sampling method, as well as the insufficient safety adaptability of the two-resistor method, are driving the current detection technology of EPS brushless motors to iterate towards fewer components, higher precision, and higher safety. There is an urgent need to propose a new current detection topology and implementation scheme that can take into account the requirements of hardware integration, sampling accuracy, and functional safety.

[0027] This embodiment proposes an EPS motor current monitoring method based on single-resistor time-division sampling. By arranging a single sampling resistor on the DC negative bus of the inverter bridge, and combining the non-zero vector characteristics of seven-segment SVPWM (Space Vector Pulse Width Modulation) to sample two-phase currents in a time-division manner, and then calculating the third-phase current using Kirchhoff's current law, accurate monitoring of the three-phase current of the motor is achieved. At the same time, through hardware parameter constraints and sampling timing optimization, the speed and accuracy of current detection are guaranteed.

[0028] This solution implements a three-phase motor current monitoring and timing control strategy through time-division sampling using a single resistor. This simplifies the hardware structure, reduces costs, optimizes PCB layout, and solves the hardware redundancy problem of traditional multi-resistor solutions. By controlling the conduction combination of the three-phase MOSFETs in the inverter bridge within one PWM cycle, two-phase motor currents flow through the single sampling resistor in a time-division manner. Accurate time-division sampling of the two-phase current is achieved in a non-zero vector state. The third-phase current is then calculated based on Kirchhoff's current law. Compared to the current reconstruction method of the dual-resistor solution, this effectively avoids reconstruction errors caused by factors such as operating conditions, component deviations, and interference.

[0029] like Figure 1 As shown, it specifically includes: The two-phase current flowing through the single sampling resistor is sampled separately. The single sampling resistor is set on the DC bus of the inverter bridge. Within one PWM cycle, the two-phase current of the motor flows through the single sampling resistor in a time-sharing manner by controlling the conduction combination of the three-phase MOSFETs of the inverter bridge, so as to sample the two-phase current in a time-sharing manner under non-zero vector state. Based on the two-phase currents, the third-phase current is calculated according to Kirchhoff's current law.

[0030] Based on the PWM duty cycle allocation window, the three-phase MOSFETs of the inverter bridge are alternately turned on and off, so that the currents of different phases flow through the single sampling resistor of the DC negative bus in a time-sharing manner. With the detection path switching of the multiplexer, the time-sharing sampling effect of one resistor sampling two phases is achieved, ensuring the independence and effectiveness of the phase current during the sampling process.

[0031] In this embodiment, as Figure 2 As shown, the inverter adopts a three-phase full-bridge topology, including 6 MOSFETs, divided into one upper bridge arm for each of the U / V / W phases and one lower bridge arm for each of the U / V / W phases, for a total of 6 switching channels.

[0032] The DC bus positive power supply (Vdc+) is directly connected to the drain of all power transistors in the upper arm of the inverter bridge, and the sources of all power transistors in the lower arm of the inverter bridge converge into a common node. This node is directly connected to the high-side pin of the single sampling resistor, forming a common current loop for single-resistor sampling.

[0033] By connecting the PWM drive signal output pins (6 channels) of the microcontroller MCU to the gates of the 6 power transistors of the inverter bridge one-to-one, the MCU can achieve precise control of the switching state of the three-phase upper / lower bridge arms of the inverter bridge, thereby adjusting the SVPWM vector state.

[0034] The U / V / W three-phase output terminals of the inverter bridge are directly connected to the U / V / W three-phase winding pins of the EPS three-phase motor to supply drive current to the motor.

[0035] In this embodiment, as Figures 2-3 As shown, the single sampling resistor (RIBUS) is set on the negative terminal of the DC bus of the inverter bridge. Current monitoring is achieved by acquiring the current flowing through the single resistor. There are no additional auxiliary components. The current is collected without redundancy through pure resistors in series.

[0036] Specifically: The high-side pin of the single sampling resistor is directly connected to the common convergence node of the sources of all power transistors in the lower arm of the inverter bridge. It receives the total current flowing out of the inverter bridge and is the only sampling point for the current of all the arms. The low-end pin of the single sampling resistor is divided into two independent connections. One connection is directly connected to the negative terminal of the DC bus to form a complete DC bus current loop. The other connection serves as the current sampling signal output terminal and is directly connected to the subsequent signal conditioning module.

[0037] This sampling resistor is the only sampling element in the common loop of the DC negative bus. The current of all arms of the inverter bridge must flow through this resistor and return to the DC negative bus to ensure that the sampling signal can truly reflect the total output current of the inverter bridge.

[0038] In this embodiment, the signal conditioning module is an analog signal preprocessing unit, including an operational amplifier and an ADC sampling module, which amplifies, biases, and filters weak sampled signals, eliminates high-frequency interference, and matches the input voltage range of the subsequent ADC sampling module.

[0039] Specifically: The operational amplifier's differential input pins: The two pins are directly connected to the high-side and low-side pins of a single sampling resistor, respectively, to acquire the differential voltage signal (i.e., the current drop signal) across the resistor. There are no additional voltage divider / current limiter components, ensuring the originality of the sampled signal.

[0040] The operational amplifier has a built-in passive / active filter, eliminating the need for external filtering components and wiring. It filters out high-frequency interference in the sampled signal through built-in hardware circuitry, thereby improving signal purity.

[0041] The amplifier's bias voltage input pin is connected to a precise reference voltage source (such as 2.5V / 3.3V) provided by the MCU to provide DC bias for the amplified analog signal and prevent negative voltage signals from exceeding the sampling range of the subsequent ADC sampling module.

[0042] Amplifier gain adjustment pin: Connected to the power supply via an external precision resistor, a fixed 4x operational amplification factor is set. When no adjustment is needed, a matching resistor is directly used to achieve fixed amplification, ensuring the standardization of the amplified signal.

[0043] The amplifier's analog signal output pin serves as the output terminal of the conditioned signal, directly connected to the input pin of the ADC sampling module to transmit the amplified, biased, and filtered standard analog voltage signal.

[0044] The sampled current is processed by the operational amplifier and then input to the ADC sampling module, and finally input to the MCU to calculate the sampled current.

[0045] In this embodiment, the ADC sampling module realizes the conversion of analog signals to digital signals. It is usually integrated on the MCU (or can be an external independent ADC chip) and serves as a bridge between hardware sampling and MCU software calculation.

[0046] Specifically: The analog input pins of the ADC sampling module are connected to the analog output pins of the operational amplifier to receive standard analog voltage signals.

[0047] Digital signal output pins of the ADC sampling module: If it is an external ADC, it is directly connected to the digital input / serial port pins of the MCU; if it is an on-chip ADC of the MCU, it is connected to the internal bus of the chip and there is no external wiring.

[0048] The ADC's reference voltage pin and the operational amplifier's bias reference voltage pin are connected to the same ground, using the same precise reference voltage source to ensure consistent accuracy in analog-to-digital conversion.

[0049] The ADC sampling module is also connected to the interrupt trigger output pin of the MCU to receive the sampling trigger signal from the MCU and realize precise timing control of the sampling action.

[0050] In this embodiment, within one PWM cycle, the conduction combination (non-zero vector) of the three-phase MOSFETs of the inverter bridge is controlled according to the PWM duty cycle, so that the two-phase current of the motor flows through the single sampling resistor in a time-sharing manner. Thus, within a specified time window, the instantaneous value of the corresponding phase current is captured by the ADC sampling module. The total period of the time window does not exceed 1000μs, and the single capture time is not less than 200ns, ultimately realizing the separate sampling of the two-phase current.

[0051] Finally, based on Kirchhoff's current law (the sum of the three-phase currents of the motor is zero, i.e., Iu+Iv+Iw=0), after sampling the two-phase currents, the third-phase current is directly calculated using the formula.

[0052] In this embodiment, the MCU has a built-in PWM counter to realize the full-process control of PWM driving, sampling interrupt triggering, data reception, current calculation and fluctuation compensation. The connection relationship is forward control + reverse signal feedback.

[0053] Specifically as follows: PWM drive signal output: The MCU's PWM output pin outputs 6 PWM signals to precisely control the inverter bridge switching state and adjust the SVPWM vector (zero / non-zero). Sampling interrupt trigger: The MCU has a built-in PWM counter, which is configured through internal registers to count PWM cycles. When the counter reaches half a PWM cycle, the MCU controls the ADC sampling module to start the sampling action at the non-zero vector. Digital signal reception: After sampling by the ADC sampling module, the signal is input to the MCU. The MCU receives the sampled digital voltage signal, providing a data basis for current calculation. Without external hardware connection, the MCU completes the calculation through its internal program: combining the fixed resistance value of the single sampling resistor, the digital voltage signal is converted into the actual sampled current; based on the formula that the sum of the three-phase currents is zero, the third-phase current is derived from the sampled currents of the two phases; the two sampled data of the same phase within a single PWM cycle are calculated to compensate for current fluctuations, while realizing real-time monitoring of the three-phase current of the motor.

[0054] In this embodiment, sampling and calculation are based on seven-segment SVPWM modulation. The following example illustrates this using sector one.

[0055] like Figure 2 As shown, when M1 is on and M3 and M5 are off, the motor has a U-direction current flowing in; when M4 is off and M2 and M6 are on, the motor has a V-direction and a W-direction current flowing out. The current sampled by the sampling resistor is equal to the U-direction current + Iu. When M1 and M3 are on and M5 is off, current flows into the motor in the U and V directions; when M4 and M6 are off and M2 is on, current flows out of the motor in the W direction, the sampling resistor collects the current equal to the A-direction current - Iw.

[0056] like Figure 4 As shown, referring to the 7-segment SVPWM sampling waveform, the sampling points are set at V1 and V2. V1 corresponds to UVW100, and the current flowing through the sampling resistor is +Iu; V2 corresponds to UVW110, and the current flowing through the sampling resistor is -Iw.

[0057] By setting ADC sampling points at UVW100 and UVW110 of the seven-segment PWM wave, the voltages in the U and W directions are obtained (according to Kirchhoff's current law Iu+Iv+Iw=0), and the current is obtained (calculated by the resistance value of the sampling resistor).

[0058] Current sampling occurs during each PWM cycle when an interrupt is triggered after the PWM counter reaches half a cycle. Similarly, current signals sampled from different sectors are... Figure 5 As shown.

[0059] The SVPWM is divided into six sectors, each corresponding to a different combination of non-zero vectors. Each sector has an ADC sampling point set at a specified non-zero vector location to achieve accurate capture of the two-phase current within that sector. The sampling rules for each sector are a fixed one-to-one pairing. Details are as follows: Sector 1: The non-zero vector is [100, 110]. The sampling points are set at V1 (100) and V2 (110) to capture the positive current of phase U and the negative current of phase W. Sector 2: Sampled V-phase positive current and W-phase negative current; Sector 3: Sampled V-phase positive current and U-phase negative current; Sector 4: Sampled to obtain the positive current of phase W and the negative current of phase U; Sector 5: Sampled to obtain the positive current of phase W and the negative current of phase V; Sector 6: Samples obtain the U-phase positive current and V-phase negative current.

[0060] In this embodiment, the complete process is as follows: (1) Sampling point selection: The switching state combination of the three-phase upper MOSFETs of the inverter bridge is defined as the switching combination vector, where [000,111] is the zero vector and the other combinations are non-zero vectors; the key difference from dual / triple resistor sampling is that current sampling is only performed at the non-zero switching combination vector, and no sampling is performed at the zero vector stage to avoid invalid detection caused by no effective phase current flowing through the sampling resistor under the zero vector. For example, the sampling point of sector 1 is set at the position corresponding to the non-zero vector [100,110].

[0061] (2) Time-division sampling execution: Sampling is triggered by the built-in PWM counter of the MCU. Within a single PWM cycle, two samplings are completed at non-zero vectors (such as

[100] and

[110] ) to collect the two phase currents (such as U-phase positive current (+Iu) and W-phase negative current (-Iw)).

[0062] (3) Derivation of three-phase current: According to the formula that the sum of three-phase current is zero (Iu+Iv+Iw=0), the sampled two-phase current is substituted into the formula to directly calculate the third-phase current, thus completing the acquisition of three-phase current.

[0063] (4) Current fluctuation compensation: Within a single PWM cycle, the same phase current (such as Iu / Iw) is sampled twice. The MCU calibrates and calculates the two sampled data through its internal program to compensate for the fluctuation of the current during transmission and sampling, thereby improving the sampling accuracy of the three-phase current.

[0064] (5) Multiplexing of multiple sectors: The remaining SVPWM sectors set sampling points at their respective non-zero switching combination vectors, obtain two-phase currents through time-division sampling, and then derive the third phase by formula. At the same time, the fluctuation compensation of single-phase second sampling is completed, so as to realize the real-time monitoring of three-phase current of the entire sector.

[0065] This embodiment proposes an EPS motor current monitoring method based on single-resistor time-division sampling. Addressing the inherent defects of existing EPS controller current detection schemes, it achieves both hardware simplification and improved detection accuracy through innovative sampling topology design and control strategy.

[0066] Specifically as follows: This embodiment significantly simplifies the hardware structure, reduces costs, and optimizes PCB layout, solving the hardware redundancy problem of traditional multi-resistor solutions. It uses only one sampling resistor, placed on the DC bus of the inverter bridge, eliminating the need for separate shunt resistors in series on each of the three bridge arms. Compared to the traditional three-resistor solution, this reduces two precision shunt resistors and the corresponding two signal processing links (including operational amplifiers, anti-aliasing filters, etc.), significantly reducing the number and types of hardware components and effectively lowering the hardware cost of the controller. Simultaneously, the centralized layout of the single resistor reduces the PCB board space occupied, avoiding the layout complexity issues caused by the dispersed layout of multiple resistors. This aligns with the miniaturization and high integration requirements of vehicle electronics, making it particularly suitable for compact automotive installation environments and reducing PCB layout difficulty and manufacturing costs.

[0067] Balancing detection accuracy and response speed, this embodiment meets the dynamic control requirements and functional safety standards of EPS systems. Within a single PWM cycle, it controls the conduction combination of the three-phase MOSFETs in the inverter bridge, allowing two-phase motor currents to flow through a single sampling resistor in a time-sharing manner. This achieves precise time-sharing sampling of the two-phase currents in a non-zero vector state, and then calculates the third-phase current using Kirchhoff's current law. Compared to the current reconstruction method of a dual-resistor scheme, this effectively avoids reconstruction errors caused by factors such as operating conditions, device deviations, and interference. Practical verification shows that, compared to a three-resistor reference, this scheme has a synthesized vector error of <3% and a response delay of ≤100μs. It ensures high accuracy in current detection while meeting the real-time requirements of EPS systems for current feedback. It is suitable for the stringent requirements of mid-to-high-end automotive EPS systems, meets the functional safety level specified in ISO 26262, and has broad application value.

[0068] Improved system reliability and reduced maintenance costs. The reduction in the number of hardware components not only lowers the cost of component procurement and production assembly, but also reduces the probability of system failures due to component aging and malfunctions, thus improving the overall reliability of the EPS controller current monitoring system. At the same time, the layout and maintenance of single resistors are simpler, and subsequent repairs or replacements of sampling resistors are easier and less time-consuming, effectively reducing later maintenance costs and further enhancing the product's market competitiveness.

[0069] In summary, this embodiment effectively solves the problems of high cost, complex layout, and uneven temperature rise of traditional multi-resistor solutions. At the same time, it overcomes the shortcomings of insufficient detection accuracy and inability to meet safety level requirements of dual-resistor solutions. It achieves multiple goals of hardware simplification, cost reduction, accuracy improvement, and fast response, perfectly adapting to the dynamic control requirements of EPS systems. It provides an efficient, reliable, and economical solution for current detection in EPS controllers, and has significant engineering application value and industrial promotion significance.

[0070] Example 2 This embodiment provides an EPS motor current monitoring system based on single-resistor time-division sampling, including: The sampling module is configured to sample the two-phase current flowing through the single sampling resistor. The single sampling resistor is set on the DC bus of the inverter bridge. Within one PWM cycle, by controlling the conduction combination of the three-phase MOSFETs of the inverter bridge, the two-phase current of the motor flows through the single sampling resistor in a time-sharing manner, so as to sample the two-phase current in a time-sharing manner under non-zero vector state. The calculation module is configured to calculate the third phase current based on the two phase currents and Kirchhoff's current law.

[0071] As an alternative implementation, one end of the single sampling resistor is connected to the common convergence node of the source of the inverter bridge power transistor to receive the current flowing out of the inverter bridge; the other end serves as the current sampling signal output terminal and is directly connected to the subsequent signal conditioning module.

[0072] As an alternative implementation, the signal conditioning module includes an operational amplifier and an ADC sampling module. The input of the operational amplifier is connected to a single sampling resistor to receive the sampled current and perform amplification and filtering. The output of the operational amplifier is connected to the ADC sampling module to perform analog-to-digital signal conversion.

[0073] As an alternative implementation, during the sampling process, the sampling action at the non-zero vector is initiated by counting the PWM cycles and when the count reaches half a PWM cycle.

[0074] As an alternative implementation, the switching state combination of the three-phase MOSFETs of the inverter bridge is defined as a switching combination vector, where [000,111] is the zero vector and the other combinations are non-zero vectors. Current sampling is performed only at the non-zero switching combination vectors, and no sampling is performed at the zero vector stage.

[0075] As an alternative implementation, the space vector pulse width modulation is divided into six sectors, each sector corresponding to a different combination of non-zero vectors, and each sector has an ADC sampling point set at a specified non-zero vector point to capture the two-phase current in that sector.

[0076] It should be noted that the above modules correspond to the steps described in Embodiment 1, and the examples and application scenarios implemented by the above modules and the corresponding steps are the same, but are not limited to the content disclosed in Embodiment 1. It should also be noted that the above modules, as part of the system, can be executed in a computer system such as a set of computer-executable instructions.

[0077] In further embodiments, the following is also provided: An electronic device includes a memory and a processor, as well as computer instructions stored in the memory and running on the processor, wherein the computer instructions, when executed by the processor, perform the method described in Embodiment 1. For brevity, further details are omitted here.

[0078] It should be understood that in this embodiment, the processor can be a central processing unit (CPU), or it can be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor, etc.

[0079] Memory may include read-only memory and random access memory, and provides instructions and data to the processor. A portion of memory may also include non-volatile random access memory. For example, memory may also store information about the device type.

[0080] A computer-readable storage medium for storing computer instructions, which, when executed by a processor, perform the method described in Embodiment 1.

[0081] The method in Example 1 can be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules within the processor. The software modules can reside in readily available storage media in the field, such as random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, or registers. This storage medium is located in memory, and the processor reads information from the memory and, in conjunction with its hardware, completes the steps of the above method. To avoid repetition, a detailed description is not provided here.

[0082] A computer program product includes a computer program that, when executed by a processor, implements the method described in Embodiment 1.

[0083] The present invention also provides at least one computer program product tangibly stored on a non-transitory computer-readable storage medium. The computer program product includes computer-executable instructions, such as instructions included in program modules, which execute in a device on a target real or virtual processor to perform the processes / methods described above. Typically, program modules include routines, programs, libraries, objects, classes, components, data structures, etc., that perform specific tasks or implement specific abstract data types. In various embodiments, the functionality of program modules can be combined or divided among program modules as needed. The machine-executable instructions for the program modules can execute within a local or distributed device. In a distributed device, the program modules can reside in both local and remote storage media.

[0084] The computer program code used to implement the methods of the present invention may be written in one or more programming languages. This computer program code may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, such that when executed by the computer or other programmable data processing device, the program code causes the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code may be executed entirely on a computer, partially on a computer, as a stand-alone software package, partially on a computer and partially on a remote computer, or entirely on a remote computer or server.

[0085] In the context of this invention, computer program code or related data may be carried by any suitable carrier to enable a device, apparatus, or processor to perform the various processes and operations described above. Examples of carriers include signals, computer-readable media, and the like. Examples of signals may include electrical, optical, radio, sound, or other forms of propagation signals, such as carrier waves, infrared signals, etc.

[0086] Those skilled in the art will recognize that the units and algorithm steps described in connection with the various examples of this embodiment can be implemented in electronic hardware or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this invention.

[0087] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for monitoring EPS motor current based on time-division sampling of a single resistor, characterized in that, include: The two-phase current flowing through the single sampling resistor is sampled separately. The single sampling resistor is set on the DC bus of the inverter bridge. Within one PWM cycle, the two-phase current of the motor flows through the single sampling resistor in a time-sharing manner by controlling the conduction combination of the three-phase MOSFETs of the inverter bridge, so as to sample the two-phase current in a time-sharing manner under non-zero vector state. Based on the two-phase currents, the third-phase current is calculated according to Kirchhoff's current law.

2. The EPS motor current monitoring method based on single-resistor time-division sampling as described in claim 1, characterized in that, One end of the single sampling resistor is connected to the common convergence node of the source of the inverter bridge power transistors to receive the current flowing out of the inverter bridge; The other end serves as the current sampling signal output terminal, which is directly connected to the signal conditioning module.

3. The EPS motor current monitoring method based on single-resistor time-division sampling as described in claim 2, characterized in that, The signal conditioning module includes an operational amplifier and an ADC sampling module. The input of the operational amplifier is connected to a single sampling resistor to receive the sampled current and perform amplification and filtering. The output of the operational amplifier is connected to the ADC sampling module to perform analog-to-digital signal conversion.

4. The EPS motor current monitoring method based on single-resistor time-division sampling as described in claim 1, characterized in that, During the sampling process, the PWM cycle is counted, and when the count reaches half a PWM cycle, the control starts the sampling action at the non-zero vector.

5. The EPS motor current monitoring method based on single-resistor time-division sampling as described in claim 1, characterized in that, The switching state combination of the three-phase MOSFETs in the inverter bridge is defined as the switching combination vector, where [000,111] is the zero vector and the other combinations are non-zero vectors. Current sampling is performed only at the non-zero switching combination vectors, and no sampling is performed at the zero vector stage.

6. The EPS motor current monitoring method based on single-resistor time-division sampling as described in claim 5, characterized in that, The space vector pulse width modulation is divided into six sectors, each sector corresponding to a different combination of non-zero vectors, and each sector has an ADC sampling point set at a specified non-zero vector point to capture the two-phase current in that sector.

7. An EPS motor current monitoring system based on single-resistor time-division sampling, characterized in that, include: The sampling module is configured to sample the two-phase current flowing through the single sampling resistor. The single sampling resistor is set on the DC bus of the inverter bridge. Within one PWM cycle, by controlling the conduction combination of the three-phase MOSFETs of the inverter bridge, the two-phase current of the motor flows through the single sampling resistor in a time-sharing manner, so as to sample the two-phase current in a time-sharing manner under non-zero vector state. The calculation module is configured to calculate the third phase current based on the two phase currents and Kirchhoff's current law.

8. An electronic device, characterized in that, It includes a memory and a processor, as well as computer instructions stored in the memory and running on the processor, which, when executed by the processor, perform the method according to any one of claims 1-6.

9. A computer-readable storage medium, characterized in that, Used to store computer instructions, which, when executed by a processor, perform the method described in any one of claims 1-6.

10. A computer program product, characterized in that, Includes a computer program, which, when executed by a processor, implements the method described in any one of claims 1-6.

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