Low-electromagnetic emission driving control method and system for long-distance direct-current motor

Abstract

The invention discloses a low-electromagnetic emission driving control method and system for a long-distance direct current motor, and relates to the technical field of motor driving. The method comprises the following steps: constructing a source-line-load system impedance model, and estimating a far-end motor voltage and an armature current in real time by using a state observation algorithm based on near-end sampled voltage and current data; responding to the control instruction to generate an S-shaped flexible voltage reference track with second derivative amplitude limiting so as to suppress resonance formed by the LC filter circuit and the long cable; calculating the line voltage drop compensation amount by combining the cable resistance parameter and the estimated current, and enabling the actual voltage of the motor end to accurately follow the reference track; and during motor commutation, the output voltage is controlled to be smoothly reduced to zero, and the polarity switch is switched after the current is monitored to return to zero. Under the condition that a far-end sensor is not added, the problems of line voltage drop, system oscillation and reversing impact of long-distance driving are solved, and high-precision reliable driving with low electromagnetic emission is achieved.

Description

Technical Field

[0001] This application relates to the field of low electromagnetic emission drive control technology, and in particular to a low electromagnetic emission drive control method and system for long-distance DC motors. Background Technology

[0002] In long-distance DC motor drive applications such as vehicle window control and industrial sites, traditional drive solutions often employ H-bridge pulse width modulation (PWM) technology, directly applying high-frequency PWM square wave signals to long-distance transmission cables to drive the motor. However, this method results in long leads carrying signals with high dv / dt and di / dt, equivalent to radiating antennas, generating severe common-mode and differential-mode electromagnetic noise, making it difficult to meet electromagnetic compatibility (EMC) standards. This typically requires expensive filters at the motor end. To suppress EMI at its source, existing technology proposes an improved "variable DC bus" drive topology, employing a structure of "Buck converter + source-side LC filter + polarity switching switch." Source-side filtering bypasses high-frequency noise, ensuring only smooth DC current is transmitted over long cables, thus significantly reducing conducted and radiated interference.

[0003] Although the aforementioned "variable DC bus" topology effectively solves the EMI problem during steady-state operation, significant drawbacks remain in practical applications due to the parasitic parameters of long-distance transmission cables. First, the DC resistance of long cables generates a non-negligible line voltage drop, causing the actual voltage at the motor end to deviate from the source output voltage, severely affecting the control accuracy of motor speed and torque. Second, the LC filter at the source end easily forms a complex second-order or higher-order resonant network with the distributed inductance and capacitance of the long cable. When the voltage command undergoes a step change, the system is highly susceptible to voltage oscillations. These transient oscillations not only reduce system stability but also induce new transient electromagnetic radiation. Finally, when using mechanical relays or switches for motor commutation, direct operation in the presence of current in the circuit will generate severe arcing and current surges, damaging switch life and generating commutation interference pulses.

[0004] In summary, how to systematically solve the problems of poor control accuracy caused by line voltage drop in long-distance DC transmission, resonance oscillation caused by coupling of LC network and long cable, and current surge during polarity switching without increasing the cost of motor-end sensors and filters, and achieve high-precision, oscillation-free and highly reliable soft switching drive, is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] This application aims to at least partially address one of the technical problems in the related art. Therefore, one objective of this application is to propose a low electromagnetic emission drive control method and system for long-distance DC motors.

[0006] One aspect of this application provides a method and system for driving and controlling a long-distance DC motor with low electromagnetic emission. This application provides a low electromagnetic emission drive control method for a long-distance DC motor, applied to a motor drive system. The system sequentially includes a DC power supply, a step-down converter circuit, an LC filter circuit, a polarity switching switch, a long-distance transmission cable, and a DC motor. The method includes the following steps: Step S1: Construct a source-line-load system dynamic model; obtain the output impedance parameters of the buck converter circuit, the electrical parameters of the LC filter circuit, the distributed parameters of the long-distance transmission cable, and the electrical parameters of the DC motor, and establish the full-order state equation of the system including the above parameters; based on the full-order state equation of the system, define a set of state variables, which includes at least the estimated voltage at the end of the long-distance transmission cable and the estimated armature current of the motor, which cannot be directly measured. Step S2: Perform remote state observation based on near-end sampling; collect near-end voltage data and near-end current data in real time at the output port of the buck converter circuit; use the near-end voltage data and near-end current data as input quantities, substitute them into the system dynamics model constructed in step S1, and solve them in real time through the state observation algorithm to output the estimated values ​​of the motor terminal voltage and the motor armature current at the end of the long-distance transmission cable. Step S3: Generate a vibration-damping flexible voltage reference trajectory; determine the target voltage value in response to external control commands; calculate the path from the current voltage to the target voltage using a trajectory planning algorithm with continuous second derivatives, and impose amplitude constraints on the voltage change rate and its change rate to output a smooth voltage reference trajectory that changes over time. Step S4: Calculate the duty cycle control signal after line voltage drop compensation; receive the estimated value of motor armature current output in step S2 and the smoothed voltage reference trajectory output in step S3; calculate the line voltage drop compensation amount based on the equivalent resistance parameters of the long-distance transmission cable; superimpose the line voltage drop compensation amount onto the smoothed voltage reference trajectory to obtain the compensated target output voltage, and convert it into the final conduction duty cycle control signal according to the DC power supply voltage; Step S5: Drive execution and feedforward compensation drive; use the final conduction duty cycle control signal generated in step S4 to drive the buck converter circuit, so that the actual voltage output by the buck converter circuit, after passing through the LC filter circuit and long-distance transmission cable, presents the actual physical voltage at the motor end following the smooth voltage reference trajectory.

[0007] Preferably, in step S1, the process of acquiring the distributed parameters of the long-distance transmission cable further includes a system initialization detection sub-step: before the motor starts, the step-down converter circuit is controlled to output a fixed low voltage lower than the motor starting threshold; the steady-state current value and voltage value at this time are collected; the total circuit resistance parameter including the resistance of the long-distance transmission cable and the resistance of the motor winding is calculated based on Ohm's law, and the total circuit resistance parameter is updated to the system dynamic model for observation in step S2 and voltage drop compensation calculation in step S4.

[0008] Preferably, in step S3, the specific method for limiting the voltage change rate and its rate of change is as follows: based on the LC filter circuit parameters and the distribution parameters of the long-distance transmission cable in step S1, the inherent resonant frequency of the system is calculated; the upper limit of the second derivative of the smooth voltage reference trajectory is set so that the spectral energy corresponding to the reference trajectory is lower than the excitation threshold of the inherent resonant frequency, thereby outputting an S-shaped voltage curve that can suppress the oscillation of the LC network and the long cable as the smooth voltage reference trajectory.

[0009] Preferably, the method further includes a zero-current soft-switching commutation step based on observation feedback. This step specifically includes: when a motor commutation command is received, firstly, the trajectory planning algorithm described in step S3 is invoked to generate a falling edge reference trajectory with a target value of zero, and the output of the buck converter circuit is adjusted through step S4; continuously monitoring the estimated value of the motor armature current output in step S2; if and only if the estimated value of the motor armature current is detected to return to zero and remain there for a period exceeding a preset dead time, controlling the polarity switching switch to change the motor connection polarity; after the polarity switching is completed, step S3 is invoked again to generate a rising edge reference trajectory with a target value of a set speed voltage, and motor drive is restored.

[0010] Preferably, in step S4, the final on-duty cycle control signal The calculation formula is as follows:

[0011] in, The instantaneous value of the smoothed voltage reference trajectory output in step S3. The estimated value of the motor armature current output in step S2 is... The equivalent resistance of long-distance transmission cables. This is the DC power supply voltage.

[0012] Preferably, the state observation algorithm uses a Luenberger observer or a Kalman filter, which uses the near-end voltage and near-end current at the output of the buck converter circuit as observation variables and the motor terminal voltage and armature current as state variables, and corrects the prediction error of the system dynamics model described in step S1 in real time through a correction matrix.

[0013] The present invention also provides a low electromagnetic emission drive control system for a long-distance DC motor using the method described above, comprising: The step-down and filtering module, consisting of a step-down converter circuit and an LC filter circuit, is used to convert the high-frequency pulse width modulation voltage of the DC power supply into a low-ripple DC voltage. A near-end sensing module, located at the output port of the step-down and filtering module, is used to collect near-end voltage and near-end current data. A polarity switching module, connected to the DC motor via a long-distance transmission cable, is used to switch the motor's direction of rotation. A digital control unit is connected to the step-down and filtering module, the near-end sensing module, and the polarity switching module, respectively. The digital control unit is configured to: perform state observation based on the data from the near-end sensing module to obtain the state of the remote motor; generate a vibration suppression trajectory and voltage drop compensation signal based on the observation results and target commands; and adjust the duty cycle of the step-down and filtering module accordingly.

[0014] Preferably, the digital control unit includes: an observer module for running a system dynamics model and outputting an estimated value of the motor armature current based on near-end sampled data; a trajectory planning module for generating an S-shaped voltage reference trajectory with limited second derivative; and a feedforward compensation module for multiplying the estimated value of the motor armature current by the cable impedance and then superimposing it onto the S-shaped voltage reference trajectory to generate control commands.

[0015] Beneficial effects According to an exemplary embodiment of this application, this application changes the traditional mode of directly transmitting high-frequency PWM signals to drive the motor via long lines. Instead, it uses a "Buck converter + LC filter" structure to convert the high-frequency pulse-width modulation voltage into a low-ripple DC voltage before transmission over long lines. This architecture cuts off the propagation path of high-frequency noise on long cables at the source, eliminating common-mode and differential-mode interference generated by the long cables acting as "radiating antennas." This allows the system to meet electromagnetic compatibility standards without relying on expensive remote (motor-side) EMI filters, significantly reducing system hardware costs and wiring complexity.

[0016] To address the voltage drop problem caused by the resistance of long-distance transmission cables, this application does not adopt the high-cost solution of adding remote sensors. Instead, it constructs a "source-line-load" system dynamic model and uses voltage and current data sampled at the near end, combined with state observation algorithms (such as Luneburg or Kalman filters), to accurately estimate the armature current of the remote motor in real time.

[0017] Based on this, this application further proposes a duty cycle calculation formula that includes a line resistance compensation term, realizing active feedforward compensation for line voltage drop. This ensures that even with load changes or long cables, the actual physical voltage at the motor terminal can accurately follow the target value, thereby significantly improving the control accuracy of motor speed and torque.

[0018] To address the potential second-order oscillation network formed by the source-end LC filter and the distributed parameters of long cables, this application does not employ simple step or ramp control. Instead, it uses a trajectory planning algorithm with continuous second derivatives (such as an S-shaped curve of the Sigmoid function) to generate a voltage reference. By calculating the inherent resonant frequency based on system parameters and thereby limiting the upper limit of the second derivative (acceleration) of the voltage reference trajectory, this application ensures that the spectral energy of the control signal is below the excitation threshold of the system resonant frequency. This "vibration-suppressing flexible trajectory" effectively smooths the voltage change rate, avoids voltage overshoot and oscillation, and eliminates secondary electromagnetic radiation caused by transient oscillations while ensuring a fast response.

[0019] To address the issues of arcing and current surges during polarity switching, this application designs a zero-current soft-switching logic based on observation feedback. During commutation, the control voltage is first smoothly brought to zero through trajectory planning, and the remote current is continuously monitored using an observer. Only after confirming that the motor armature current has completely returned to zero and the dead time has elapsed is the polarity switching switch activated. This control strategy completely eliminates the arcing and current surges generated during load switching, prevents switch contact erosion, significantly extends the service life of relays and other switching devices, and avoids pulse interference during commutation.

[0020] This application introduces a system initialization detection mechanism that outputs a small voltage below the starting threshold before the motor starts, and uses Ohm's law to measure the total circuit resistance. This mechanism can automatically adapt to resistance drift caused by different cable lengths or temperature changes, updating the system dynamic model parameters in real time. This not only ensures the estimation accuracy of the state observer but also guarantees the accuracy of the voltage drop compensation calculation, enabling the system to maintain optimal control performance under different operating conditions. Attached Figure Description

[0021] Figure 1 This application provides a low electromagnetic emission drive control method for a long-distance DC motor. Figure 2 This is a schematic diagram of the structure of a long-distance DC motor low electromagnetic emission drive control system provided in one embodiment of this application.

[0022] Figure 3 This is a voltage / time comparison simulation waveform diagram of the conventional step response, ramp response and the S-curve response of this application according to an embodiment of this application; Figure 4 This application provides a low electromagnetic emission drive control system for a long-distance DC motor, as one embodiment of the present application. Detailed Implementation

[0023] To better understand this application, various aspects of this application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely illustrative of exemplary embodiments of this application and are not intended to limit the scope of this application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0024] In the accompanying drawings, the size, dimensions, and shapes of the elements have been slightly adjusted for ease of illustration. The drawings are for illustrative purposes only and are not strictly to scale. As used herein, the terms “approximately,” “about,” and similar terms are used to indicate approximation, not degree, and are intended to illustrate inherent deviations in measured or calculated values ​​that will be recognized by one of ordinary skill in the art. Furthermore, the order in which the steps are described in this application does not necessarily indicate the order in which these steps occur in actual operation, unless otherwise expressly defined or deduced from the context.

[0025] It should also be understood that expressions such as "comprising," "including," "having," "containing," and / or "comprising" are open-ended rather than closed-ended expressions in this specification, indicating the presence of the stated features, elements, and / or components, but not excluding the presence of one or more other features, elements, components, and / or combinations thereof. Furthermore, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire list of features, not just individual elements in the list. Additionally, when describing embodiments of this application, the word "may" is used to mean "one or more embodiments of this application." And the term "exemplary" is intended to refer to examples or illustrations.

[0026] Unless otherwise specified, all terms used herein (including engineering and technical terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that, unless expressly stated herein, terms defined in common dictionaries shall be interpreted as having the meaning consistent with their meaning in the context of the relevant art, and not as having an idealized or overly formalized meaning.

[0027] It should be noted that, where there is no conflict, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0028] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments. The components of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0029] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this application, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0030] In traditional long-distance DC motor drive applications, the parasitic parameters of long-distance transmission cables lead to several issues: reduced control accuracy due to line voltage drop; voltage resonance oscillations caused by the coupling between the LC filter network and the cable's distributed parameters; and current surges during polarity switching. Specifically, line voltage drop causes the actual voltage at the motor terminal to deviate from the source output voltage, directly affecting the control accuracy of speed and torque. The LC filter circuit, along with the distributed inductance and capacitance of the long cable, forms a resonant network, generating transient oscillations during voltage command step changes, reducing system stability. Furthermore, if the switching action is performed before the loop current returns to zero during polarity switching, current surges and arcing will occur, damaging the reliability of the switching devices.

[0031] For example, in the motor drive scenario of an industrial automated production line, when an external control command requires the motor to change its operating state, the voltage signal output from the source end is transmitted over a long distance via a transmission cable. Due to the voltage drop caused by the line resistance, the voltage at the motor end cannot accurately track the command value, resulting in a deviation in speed response. At the same time, the voltage step change excites the interaction between the LC filter circuit and the cable distributed parameters, manifesting as voltage oscillation, which affects the dynamic performance of the system. During commutation operations, the switching devices switch under the condition of current, generating transient current spikes, introducing electromagnetic interference and accelerating switch aging.

[0032] If the above problems are not solved, the system will face technical consequences such as continuous deterioration of control accuracy, increased system instability due to resonant oscillation, and shortened lifespan of switching devices due to current surges. In severe cases, it may lead to drive system failure and affect the reliability and safety of the entire application.

[0033] In this regard, such as Figure 1As shown, this application proposes a low electromagnetic emission drive control method for long-distance DC motors, applied to a motor drive system. The system sequentially includes a DC power supply, a step-down converter circuit, an LC filter circuit, a polarity switching switch, a long-distance transmission cable, and a DC motor. The method includes the following steps: Step S1: Construct a dynamic model of the source-line-load system; obtain the output impedance parameters of the buck converter circuit, the electrical parameters of the LC filter circuit, the distributed parameters of the long-distance transmission cable, and the electrical parameters of the DC motor, and establish the full-order state equation of the system containing the above parameters; based on the full-order state equation of the system, define a set of state variables, which should at least include the estimated values ​​of the voltage at the end of the long-distance transmission cable and the estimated values ​​of the armature current of the motor, which cannot be directly measured. Step S2: Perform remote state observation based on near-end sampling; collect near-end voltage data and near-end current data in real time at the output port of the buck converter circuit; use the near-end voltage data and near-end current data as input quantities, substitute them into the system dynamics model constructed in step S1, and solve them in real time through the state observation algorithm to output the estimated values ​​of the motor terminal voltage and the motor armature current at the end of the long-distance transmission cable. Step S3: Generate a vibration-damping flexible voltage reference trajectory; determine the target voltage value in response to external control commands; calculate the path from the current voltage to the target voltage using a trajectory planning algorithm with continuous second derivatives, and impose amplitude constraints on the voltage change rate and its rate of change, outputting a smooth voltage reference trajectory that changes over time. Step S4: Calculate the duty cycle control signal after line voltage drop compensation; receive the estimated value of motor armature current output in step S2 and the smoothed voltage reference trajectory output in step S3; calculate the line voltage drop compensation amount based on the equivalent resistance parameters of the long-distance transmission cable; superimpose the line voltage drop compensation amount onto the smoothed voltage reference trajectory to obtain the compensated target output voltage, and convert it into the final conduction duty cycle control signal according to the DC power supply voltage. Step S5: Drive execution and feedforward compensation drive; use the final conduction duty cycle control signal generated in step S4 to drive the buck converter circuit, so that the actual physical voltage output by the buck converter circuit, after passing through the LC filter circuit and long-distance transmission cable, follows the smooth voltage reference trajectory at the motor end.

[0034] like Figure 2 As shown, the motor drive system provided in this embodiment mainly consists of five parts: a DC power supply 1, which provides energy to the system; a step-down and filtering module 2 (corresponding to...). Figure 1The BUCK step-down and filter circuit (containing MOSFET switching devices, diodes, inductors, and capacitors) is used to output an adjustable low-ripple DC voltage, and a voltage sensor (V) and a current sensor (A) are configured at the output terminal to collect near-end data; polarity switching switch 3, composed of a relay contact network (such as S1, S2), is used to physically switch the motor connection polarity; long-distance transmission cable and motor load 4 simulate the impedance of long wires and the remote motor in actual working conditions; digital control unit 5 (corresponding to Figure 1 The MCUcontrol unit is connected to the voltage / current sensor, the gate of the MOS transistor, and the relay control terminal, respectively, and is used to perform state observation, trajectory planning, and PWM signal generation.

[0035] For ease of understanding, the following explains some key terms in this embodiment: Motor drive system: This system comprises several interconnected components. These include, in sequence, a DC power supply, a buck converter circuit, an LC filter circuit, a polarity switching switch, long-distance transmission cables, and a DC motor. This configuration is designed to efficiently and reliably drive long-distance DC motors while simultaneously reducing electromagnetic interference.

[0036] Buck converter circuit: This is a switch-mode power converter that converts a higher DC input voltage into a lower DC output voltage. The output voltage can be precisely controlled by adjusting the on-time ratio, or duty cycle, of its internal switching devices.

[0037] LC filter circuit: This circuit consists of an inductor (L) and a capacitor (C) and is a passive filter. In this system, its main function is to filter out the high-frequency ripple of the buck converter circuit output and convert the pulsating DC voltage into a smooth DC voltage to reduce electromagnetic interference to long-distance transmission cables.

[0038] Polarity switch: This is a device used to change the polarity of the voltage across a DC motor. By switching its connection method, the DC motor can be turned forward, reversed, or braked.

[0039] Long-distance transmission cables: These cables refer to the wires connecting the power supply-side drive circuit to the remote DC motor. Due to their long length, they introduce parasitic parameters such as resistance, inductance, and capacitance, which can affect system performance.

[0040] DC motor: This is a rotating electric motor that converts electrical energy into mechanical energy. Its speed and torque are usually controlled by the voltage applied across its armature and the current flowing through the armature.

[0041] System dynamics model: This model describes the interactions between the various physical quantities within the system and their time-varying mathematical expressions. In this method, this model is used to characterize the dynamic behavior of the entire system consisting of a DC power supply, a buck converter circuit, an LC filter circuit, long-distance transmission cables, and a DC motor.

[0042] State variables: These variables are the minimal set of independent variables that describe the state of the system at any given time. The future behavior of the system can be completely determined using these variables. In this method, the set of state variables includes at least the estimated voltage at the end of the long-distance transmission cable and the estimated armature current of the motor; these variables are crucial for precise control of the remote motor.

[0043] State observation algorithm: This is an algorithm that estimates in real time the internal state variables of a system that cannot be directly measured, based on system inputs and measurable outputs. It improves the accuracy of state estimation through mathematical models and feedback correction mechanisms.

[0044] Trajectory planning algorithm: This is an algorithm used to generate smooth, continuous motion or changing paths. In this method, it is used to plan the path of voltage transition from the current value to the target value to avoid system oscillations caused by voltage abrupt changes.

[0045] This embodiment provides a low electromagnetic emission drive control method for long-distance DC motors, which aims to solve the problems of poor control accuracy caused by line voltage drop, resonant oscillation caused by coupling of LC network and long cable, and current surge during polarity switching in long-distance DC transmission.

[0046] First, the method involves constructing a dynamic model of the source-line-load system. Specifically, it requires obtaining the output impedance parameters of the buck converter circuit, the electrical parameters of the LC filter circuit, the distributed parameters of the long-distance transmission cable, and the electrical parameters of the DC motor. These parameters can be obtained by consulting device datasheets, conducting laboratory measurements, or through system identification. For example, the output impedance parameters of the buck converter circuit can be calculated using its equivalent circuit model; the inductance and capacitance values ​​of the LC filter circuit can be directly read from the components or measured using an impedance analyzer; the distributed parameters of the long-distance transmission cable, such as resistance, inductance, and capacitance per unit length, can be measured using the bridge method or time-domain reflectometer; the electrical parameters of the DC motor, such as armature resistance, armature inductance, and back EMF constant, can be obtained from the motor nameplate or through no-load / locked-rotor experiments. Based on the obtained parameters, a full-order state equation for the system can be established, which comprehensively describes the dynamic characteristics of the entire motor drive system. On this basis, a set of state variables is defined, which includes at least the estimated values ​​of the voltage at the end of the long-distance transmission cable and the estimated values ​​of the motor armature current, which cannot be directly measured. These remote state variables are crucial for precise motor control, but due to cost and wiring complexity, it is often difficult to install sensors directly on the motor for measurement.

[0047] Secondly, the method includes performing remote state observation based on near-end sampling. Near-end voltage and current data are acquired in real time at the output port of the buck converter circuit, i.e., near the power supply side. This data can be directly acquired using voltage and current sensors. For example, a Hall effect current sensor can be used to measure the near-end current, and a voltage divider network can be used to measure the near-end voltage. These real-time acquired near-end voltage and current data are used as inputs and substituted into the system dynamics model constructed in step S1. The model is solved in real time using a state observation algorithm, thereby outputting estimated values ​​of the motor terminal voltage and motor armature current at the end of the long-distance transmission cable. This approach avoids installing additional sensors at the remote motor, reducing system cost and complexity. The state observation algorithm can estimate the internal, unmeasurable states of the system based on the system model and measurable input / output data through mathematical derivation and iterative calculation.

[0048] Furthermore, the method includes generating a vibration-damped flexible voltage reference trajectory. First, a target voltage value is determined in response to an external control command. For example, when a user sets the motor speed via the user interface, this speed command is converted into a corresponding target voltage value. Then, a trajectory planning algorithm with continuous second derivatives is used to calculate the path from the current voltage to the target voltage. This trajectory planning algorithm can be implemented using methods such as polynomial interpolation, spline functions, or time-optimal control to ensure a smooth generated trajectory. Simultaneously, voltage change rate and its amplitude are constrained. For example, the maximum rate of voltage rise or fall, and the maximum value of voltage change acceleration, can be set. In this way, a smooth voltage reference trajectory that varies over time is output, avoiding abrupt changes in voltage commands and thus reducing potential shocks to the system.

[0049] Next, the method includes calculating the duty cycle control signal after line voltage drop compensation. The estimated motor armature current output from step S2 and the smoothed voltage reference trajectory output from step S3 are received. The line voltage drop compensation amount is calculated based on the equivalent resistance parameters of the long-distance transmission cable. For example, the line voltage drop compensation amount can be simply obtained by multiplying the estimated motor armature current by the cable's equivalent resistance. This line voltage drop compensation amount is superimposed on the smoothed voltage reference trajectory to obtain the compensated target output voltage. For example, if the smoothed voltage reference trajectory requires a motor terminal voltage of U_ref, and the estimated line voltage drop is U_drop, then the compensated target output voltage is U_ref + U_drop. Finally, the compensated target output voltage is converted into a final on-duty cycle control signal based on the DC power supply voltage. For example, the duty cycle can be simply determined by the ratio of the target output voltage to the DC power supply voltage.

[0050] Finally, the method includes drive execution and feedforward compensation drive. The buck converter circuit is driven using the final duty cycle control signal generated in step S4. The buck converter circuit adjusts the on-time of its switching transistors according to the duty cycle signal, thereby outputting a corresponding voltage. Thus, the actual voltage output by the buck converter circuit, after passing through the LC filter circuit and long-distance transmission cable, presents a physical voltage at the motor end that follows a smooth voltage reference trajectory. Through this feedforward compensation drive, the system can correct deviations caused by various disturbances (such as load changes, power fluctuations, etc.) in real time, ensuring that the motor terminal voltage accurately tracks the preset smooth trajectory, thereby achieving precise control of motor speed and torque.

[0051] The following example will provide a more detailed explanation of the above technical solution: Imagine an industrial automation scenario where a DC motor needs to be driven via a long transmission cable, sometimes tens of meters long, to control a remote valve. In traditional solutions, due to the resistance of the long cable, the actual voltage at the motor terminals will be lower than the driver's output voltage, leading to inaccurate valve opening control. Furthermore, if a step voltage is directly applied to the motor, the long cable and LC filter may oscillate, affecting system stability.

[0052] The method provided in this embodiment can effectively solve the above problems.

[0053] First, before the system is put into operation, a source-line-load system dynamic model is constructed. Specifically, engineers will measure or consult the DC power supply voltage, the switching frequency and equivalent output impedance of the buck converter circuit, the inductance and capacitance values ​​of the LC filter circuit, the resistance per meter, inductance and capacitance parameters of the long-distance transmission cable, and the armature resistance, armature inductance, and back electromotive force constant of the DC motor. For example, by measuring the resistance of the cable, its total resistance is determined as R_line. These parameters are input into the controller's processor to establish a full-order state equation for the system that includes all these electrical parameters. Based on this equation, a set of state variables is defined, which includes two key variables that cannot be directly measured: the estimated value of the motor terminal voltage at the end of the long-distance transmission cable (U_motor_est) and the estimated value of the motor armature current (I_motor_est).

[0054] Specifically, when constructing the system dynamics model, the electrical characteristics of the DC motor follow the following voltage balance equation and torque equation: ; in, This is the motor terminal voltage. For armature current, and These are the armature resistance and inductance of the motor, respectively. Where is the back electromotive force constant, and N is the motor speed. For electromagnetic torque, is the torque constant.

[0055] During system operation, remote state observation based on near-end sampling is performed. Near-end voltage and current data are acquired in real time at the output port of the buck converter circuit, i.e., near the controller. This data is fed into the controller. The controller uses these data as inputs and substitutes them into a pre-built system dynamics model. By running a state observation algorithm, such as a model-based state estimator, the controller can calculate the estimated values ​​of the motor terminal voltage and motor armature current at the end of the long-distance transmission cable in real time. Thus, even if the motor is tens of meters away, the controller can "sense" the actual electrical state of the motor's operation without installing additional sensors at the motor end.

[0056] When the operator issues a command via the control panel, requesting the valve to smoothly move from its current position to a new opening degree, the system generates a vibration-damping flexible voltage reference trajectory. The controller responds to this external control command and determines the target voltage value corresponding to the new valve opening degree. For example, if the current motor terminal voltage is 10V and the target voltage is 20V, the controller uses a trajectory planning algorithm with continuous second derivatives to calculate the voltage path that smoothly transitions from 10V to 20V. During this process, strict limits are imposed on the rate of change of voltage (i.e., the speed of voltage rise or fall) and its rate of change (i.e., the acceleration of voltage change). For example, the voltage change per second is set to no more than 1V / s, and the rate of change of voltage per second is set to no more than 0.1V / s². This generates a smooth voltage reference trajectory that varies over time, exhibiting an S-shaped curve, avoiding sudden voltage jumps and effectively suppressing potential resonant oscillations caused by the LC filter circuit and long cables.

[0057] In a preferred embodiment, this application uses the Sigmoid function (S-shaped function) to generate the smooth voltage reference trajectory; Compared to a simple ramp function, the sigmoid function is infinitely differentiable, thus smoothing voltage changes to the greatest extent possible. Its calculation formula is as follows: ; in, The target voltage value is calculated based on the target rotational speed; t is the time variable. is the adjustment coefficient used to control the rate of voltage change (i.e., the steepness of the S-curve). The smaller the value of $a$, the smoother the voltage change and the smaller the system oscillation. b is the time offset used to control the starting moment of voltage rise.

[0058] By adjusting the parameters With b, the system can precisely control the voltage transition from the current value to b. The acceleration ensures that its spectral energy avoids the system's inherent resonant frequency.

[0059] Subsequently, the system calculates the duty cycle control signal after line voltage drop compensation. The controller receives the estimated motor armature current output in step S2 and the smoothed voltage reference trajectory output in step S3. Based on the equivalent resistance parameters of the long-distance transmission cable, the line voltage drop compensation amount is calculated.

[0060] Finally, the system drives the execution and feedforward compensation. The controller uses the final duty cycle control signal D(t) generated in step S4 to drive the buck converter circuit. The buck converter circuit adjusts its output voltage according to D(t). Therefore, the actual physical voltage output by the buck converter circuit, after passing through the LC filter circuit and long-distance transmission cable, can accurately follow the smooth voltage reference trajectory U_ref(t) at the motor end. Through this feedforward compensation drive, even when load changes or ambient temperature fluctuations cause slight changes in cable resistance, the actual voltage at the motor end can stably track the target trajectory, thereby achieving high-precision, oscillation-free control of the remote valve opening.

[0061] To verify the effectiveness of the vibration-damping flexible voltage reference trajectory generated in this application Figure 3 The voltage response under three different driving methods is compared. For example... Figure 3 As shown in (a), when using the traditional step response command, the system exhibits significant voltage oscillations with an overshoot of up to 62.1%, and the oscillation time is relatively long, making it highly susceptible to electromagnetic radiation; Figure 3 As shown in (c), when using a simple ramp response, although the oscillation is reduced, there is still an overshoot of 2.1%, and the rise time is relatively long (48.3 ms), resulting in a slow dynamic response; while as Figure 3 As shown in (b), when using the S-Curve Response proposed in this application, the voltage trajectory is smooth, the overshoot is only 1.7%, and the rise time is only 17.5 ms. This indicates that the method of this application effectively suppresses oscillations in the LC network and long cables while significantly improving the dynamic response speed of the system, achieving a fast and oscillation-free control effect.

[0062] Based on the above examples, the low electromagnetic emission drive control method for long-distance DC motors proposed in this embodiment demonstrates a significant technical contribution in solving the inherent technical challenges in long-distance DC transmission.

[0063] Furthermore, in traditional solutions, when the voltage command undergoes a step change, the long cable and LC filter easily form a resonant network, causing voltage oscillations and affecting system stability. For example, during rapid valve opening and closing, voltage surges may lead to motor vibration or transient electromagnetic radiation. This embodiment generates a vibration-suppressed flexible voltage reference trajectory, utilizes a trajectory planning algorithm with continuous second derivatives, and imposes amplitude constraints on the voltage change rate and its amplitude, outputting a smooth S-shaped voltage reference trajectory. This trajectory planning method suppresses voltage step changes at the source, effectively avoiding resonant oscillations caused by the coupling of the LC network and the long cable, thus improving the dynamic stability and reliability of the system. This has a significant advantage in oscillation suppression compared to traditional solutions that directly apply step voltage commands or only perform simple ramp control.

[0064] Finally, through the close coordination of the above series of steps, this method achieves high-precision, oscillation-free drive for long-distance DC motors. The drive execution and feedforward compensation steps ensure that the actual physical voltage at the motor end accurately follows the smooth voltage reference trajectory, forming a stable and reliable control closed loop. Overall, the method in this embodiment systematically solves the problems of line voltage drop, resonant oscillation, and potential current surges caused by long-distance DC transmission without increasing the cost of motor-end sensors and filters. It provides a high-performance, low-electromagnetic-emission solution for long-distance DC motor drive applications and has significant engineering application value.

[0065] In some of the solutions described above in this application, the distributed parameters of long-distance transmission cables are obtained to establish a system dynamics model. However, in this process, the parameter acquisition may be inaccurate, leading to model errors and affecting the accuracy of state observation and voltage drop compensation. To address this, this application further proposes that in step S1, the process of obtaining the distributed parameters of the long-distance transmission cable also includes a system initialization detection sub-step: before the motor starts, the step-down converter circuit is controlled to output a fixed low voltage lower than the motor starting threshold; the steady-state current and voltage values ​​at this time are collected; based on Ohm's law, the total loop resistance parameter, including the resistance of the long-distance transmission cable and the resistance of the motor windings, is calculated, and this total loop resistance parameter is updated in the system dynamics model for use in the observation of step S2 and the voltage drop compensation calculation of step S4.

[0066] The system initialization testing sub-step aims to accurately measure key electrical parameters in the system, especially resistance-related parameters, through a specific testing process before the system is officially put into operation. Its purpose is to calibrate or update the parameters in the system dynamics model to improve the model's accuracy. This sub-step can be executed by pre-setting a diagnostic mode or calibration procedure in the system controller. In this mode, the controller issues control commands according to a predetermined sequence and collects corresponding feedback data. Alternatively, it can be completed with the assistance of external testing equipment. For example, during system installation or maintenance, a professional resistance meter or LCR meter can be connected to perform individual measurements on long-distance transmission cables and motor windings, and then the measurement results can be manually input or imported into the system controller via an interface.

[0067] Before the motor starts, the buck converter circuit outputs a fixed low voltage below the motor starting threshold. This is to establish a stable DC circuit without starting the motor, allowing for accurate measurement of the circuit's resistance. The voltage below the motor starting threshold ensures the motor will not rotate, thus avoiding interference from the motor's back electromotive force and guaranteeing the purity of the measurement results. The buck converter circuit controller can have a built-in low-voltage output mode that automatically sets the output voltage to a preset fixed value below the motor starting voltage upon receiving an initialization command. Alternatively, software programming can be used to add a judgment logic to the system startup sequence. When the system is detected to be in the initialization state, this logic forces the PWM duty cycle of the buck converter circuit to a minimum value, stabilizing the output voltage at a low level.

[0068] The steady-state current and voltage values ​​are acquired after the buck converter outputs a fixed low voltage and reaches a steady state. These values ​​form the basis for calculating the total resistance of the circuit. Steady-state acquisition ensures that the measured values ​​are unaffected by transient processes, reflecting the true DC characteristics of the circuit. This can be achieved by placing voltage and current sensors at the output port (near end) of the buck converter, which convert analog signals into digital signals and transmit them to the main controller for processing. Alternatively, the buck converter's integrated current sensing function (e.g., via a sampling resistor or Hall sensor) and voltage feedback function can be used to read the values ​​converted by its internal ADC under steady-state conditions.

[0069] The total resistance of a circuit, including the resistance of long-distance transmission cables and motor windings, is calculated based on Ohm's Law, the fundamental principle for resistance calculation. By acquiring steady-state voltage and current values, the equivalent DC resistance of the entire circuit, encompassing the resistance of the long-distance transmission cables and motor windings, can be calculated directly and accurately. After receiving the acquired steady-state voltage and current values, the main controller performs a division operation directly in the software to obtain the total circuit resistance. Alternatively, a dedicated resistance calculation module can be designed. This module receives voltage and current inputs and outputs the calculated resistance value. This module can be implemented as hardware circuitry or as a function in firmware.

[0070] Updating the total loop resistance parameter to the system dynamics model significantly improves its accuracy. An accurate model is fundamental for subsequent state observations and voltage drop compensation, reducing deviations between the model and the actual system. A parameter area can be reserved in the system controller's memory to store the total loop resistance. After initialization detection, the calculated resistance value is written to this area for use by the system dynamics model. Alternatively, the system dynamics model can be designed with configurable parameters, receiving updated resistance parameters via a software interface and integrating them into the state equations or transfer functions.

[0071] The updated total loop resistance parameter is used for observation in step S2 and voltage drop compensation calculation in step S4. In step S2, the accurate resistance parameter enables the state observation algorithm to more accurately estimate the motor terminal voltage and motor armature current at the end of the long-distance transmission cable. In step S4, this parameter is directly used to calculate the line voltage drop compensation, ensuring the accuracy of the compensation so that the actual voltage at the motor terminal can accurately follow the reference trajectory. Internally, the updated resistance parameter can be used as part of the model in state prediction and correction within the state observation algorithm (such as a Luenberger observer or a Kalman filter). In the voltage drop compensation calculation module, this resistance parameter can be used as input, multiplied by the estimated motor armature current to obtain the accurate line voltage drop, and added to the voltage reference trajectory.

[0072] This application's solution introduces a system initialization detection sub-step in step S1 of the low electromagnetic emission drive control method for long-distance DC motors, aiming to address the problem of inaccurate acquisition of distributed parameters of long-distance transmission cables and electrical parameters of the motor in the system dynamics model. Specifically, before the motor starts, the system first controls the buck converter circuit to output a fixed low voltage below the motor starting threshold. This ensures the motor is stationary, avoiding interference from the motor's back electromotive force on the measurement results, thus creating a pure steady-state condition for accurate measurement of the loop resistance. Subsequently, the system collects the steady-state current and voltage values ​​at this time, which are direct evidence for calculating the total loop resistance based on Ohm's law. Using Ohm's law, the system can accurately calculate the total loop resistance parameters, including the resistance of the long-distance transmission cable and the resistance of the motor windings. This calculation result is then used to update the system dynamics model, enabling the model to more realistically reflect the characteristics of the actual physical system. The updated total loop resistance parameters are crucial for subsequent control steps. In step S2, the near-end sampling-based far-end state observation algorithm utilizes this more accurate total loop resistance parameter, combined with near-end voltage and current data, to more accurately calculate the estimated values ​​of the motor terminal voltage and motor armature current at the end of the long-distance transmission cable. Simultaneously, in step S4, when calculating the duty cycle control signal after line voltage drop compensation, this accurate total loop resistance parameter is directly used to calculate the line voltage drop compensation amount. By superimposing the accurate line voltage drop compensation amount onto the smooth voltage reference trajectory, the system can obtain the compensated target output voltage and ultimately convert it into an accurate conduction duty cycle control signal. This mechanism ensures that the actual voltage output from the buck converter circuit, after passing through the LC filter circuit and the long-distance transmission cable, more accurately follows the smooth voltage reference trajectory at the motor terminal, thereby significantly improving the control accuracy of motor speed and torque, and effectively suppressing oscillations and control deviations caused by inaccurate parameters.

[0073] As a specific implementation, the above system initialization detection sub-step can be implemented as follows: After the motor drive system is powered on, but before receiving any motor start command, the system controller (e.g., a control unit based on a DSP or high-performance microcontroller) first enters a self-test or calibration mode. In this mode, the controller sends a preset PWM signal to the buck converter circuit, causing the buck converter circuit to output a fixed low voltage, for example, 0.5V, which is much lower than the starting voltage of a typical DC motor (e.g., a 12V motor may require more than 2V to start). The system waits for approximately 50-100 milliseconds to ensure that the circuit reaches a steady state. Subsequently, through voltage and current sensors connected to the output port of the buck converter circuit, the controller synchronously acquires the steady-state voltage value (e.g., U_measured = 0.48V) and steady-state current value (e.g., I_measured = 0.05A). The firmware program inside the controller immediately performs Ohm's law calculation: R_total = U_measured / I_measured = 0.48V / 0.05A = 9.6 ohms. The calculated total circuit resistance parameter (9.6 ohms) is then stored in a non-volatile memory and loaded into the state equations of the system dynamics model, replacing or correcting the original estimated values ​​of the long-distance transmission cable resistance and motor winding resistance in the model. During subsequent motor operation, both the state observer in step S2 and the voltage drop compensation module in step S4 will use this actually measured and updated 9.6-ohm resistance value for calculations, thereby ensuring the accuracy of the estimation of motor terminal voltage and current, as well as the line voltage drop compensation.

[0074] Through the above technical solution, this application effectively solves the problem in long-distance DC motor drive systems where inaccurate parameters of long-distance transmission cables and motors lead to errors in the system dynamics model, thus affecting the accuracy of state observation and voltage drop compensation. By performing system initialization detection before motor startup, accurately measuring the total circuit resistance parameter, and updating it to the system dynamics model, the model can more realistically reflect the characteristics of the actual physical system. This significantly improves the accuracy of remote state observation in step S2, making the estimated motor terminal voltage and the estimated motor armature current closer to the true values. Simultaneously, in step S4, the line voltage drop compensation is calculated based on the accurate total circuit resistance parameter, ensuring the accuracy of the compensation. This allows the buck converter circuit to output a more precise duty cycle control signal, enabling the actual physical voltage at the motor terminal to follow the smooth voltage reference trajectory with high precision. Ultimately, this solution improves the control accuracy and stability of long-distance DC motor drive systems, effectively avoiding control deviations and potential system oscillations caused by inaccurate parameters.

[0075] In some of the solutions described above in this application, a limit constraint is proposed on the voltage change rate and its rate of change to generate a smooth voltage reference trajectory to suppress oscillation. However, in its implementation, if the inherent resonant frequency is not calculated based on the system parameters and an upper limit of the second derivative is set, the spectral energy of the reference trajectory may exceed the excitation threshold, and the oscillation of the LC network and long cable cannot be effectively suppressed.

[0076] In this regard, this application further proposes a specific method for limiting the voltage change rate and its rate of change in step S3 above: based on the LC filter circuit parameters and the distribution parameters of the long-distance transmission cable in step S1 above, the inherent resonant frequency of the system is calculated; the upper limit of the second derivative of the smooth voltage reference trajectory is set so that the spectral energy corresponding to the reference trajectory is lower than the excitation threshold of the inherent resonant frequency, thereby outputting an S-shaped voltage curve that can suppress the oscillation of the LC network and the long cable as the smooth voltage reference trajectory.

[0077] Specifically, firstly, based on the LC filter circuit parameters and long-distance transmission cable distribution parameters obtained in step S1 above, the inherent resonant frequency of the system needs to be calculated. The inherent resonant frequency is the frequency point at which the internal energy of the system is most prone to oscillation when subjected to external excitation. Accurately calculating this frequency is crucial to avoiding system resonance. This calculation can be based on eigenvalue analysis of the system dynamics model or determined through analysis of the system transfer function. Secondly, an upper limit needs to be set for the second derivative of the smoothed voltage reference trajectory. The second derivative of the smoothed voltage reference trajectory represents the rate of change of the voltage change rate, i.e., voltage acceleration. Limiting its upper limit can effectively control the drastic degree of voltage change, preventing excessive changes in voltage command within a short period, thereby avoiding impact on the system. This upper limit value can be comprehensively set based on the system's requirements for transient response, the hardware's tolerance, and the system's inherent resonant characteristics. Furthermore, the spectral energy corresponding to the reference trajectory needs to be lower than the excitation threshold of the inherent resonant frequency. This technical feature aims to ensure that the generated voltage reference trajectory does not significantly excite the system's inherent resonant frequency in the frequency domain. If the spectral components of the reference trajectory have high energy near the inherent resonant frequency, it may excite resonance in the system, even if the trajectory itself is smooth. Resonance can be fundamentally avoided by limiting the spectral energy of the reference trajectory below the excitation threshold. This is typically achieved by adjusting trajectory planning parameters and combining them with frequency domain analysis. Ultimately, the output is an S-shaped voltage curve that suppresses oscillations in LC networks and long cables, serving as the smooth voltage reference trajectory. An S-shaped voltage curve is a trajectory with smooth acceleration and deceleration processes, characterized by continuous and finite rates of change of voltage (first derivative) and rate of change of voltage (second derivative). This curve effectively avoids the impact of step changes, thereby suppressing system oscillations. S-shaped curves can be generated using various trajectory planning algorithms, such as those based on polynomial interpolation or jerk limiting.

[0078] The solution in this application accurately calculates the inherent resonant frequency of the entire motor drive system by utilizing the LC filter circuit parameters and long-distance transmission cable distribution parameters provided by the system dynamics model constructed in step S1 above. This calculation process is based on the actual physical parameters of the system, rather than empirical settings, thus enabling accurate identification of the system's sensitivity to specific frequency excitations. Furthermore, when generating a smooth voltage reference trajectory, it no longer simply limits the voltage change rate and its amplitude, but rather closely integrates this limitation with the system's inherent resonant characteristics. Specifically, the smoothness and acceleration of voltage changes are controlled by setting an upper limit for the second derivative of the smooth voltage reference trajectory. More importantly, this upper limit for the second derivative is not arbitrary but carefully designed to ensure that the energy distribution of the generated voltage reference trajectory in the frequency domain, especially its high-frequency components, is below the excitation threshold of the system's inherent resonant frequency. This means that even during voltage transitions, the spectrum of the reference trajectory will not contain enough energy to excite the LC network and long cable to resonate. In this way, the final output smooth voltage reference trajectory exhibits S-shaped curve characteristics, with stable and continuous voltage changes, and its internal spectral components are actively confined to the non-resonant region. This S-shaped voltage curve, used as the control target for the buck converter circuit, can prevent impacts on the complex resonant network composed of long-distance transmission cables and LC filter circuits from the source, thereby effectively suppressing voltage oscillations. Compared with the above-mentioned schemes that only perform general amplitude limiting constraints, this approach combines trajectory planning with the inherent resonant characteristics of the system to achieve deeper and more fundamental suppression of oscillations, significantly improving the stability and reliability of the system.

[0079] As a specific implementation, the inductance and capacitance of the LC filter circuit obtained in the above step S1, as well as the equivalent inductance and equivalent capacitance of the long-distance transmission cable, can be utilized. These parameters are substituted into the system transfer function, and the natural resonance frequency f_res of the system is accurately calculated by analyzing its poles or zeros, or by solving the characteristic equation. For example, for a second-order LC resonance system, the natural resonance frequency can be approximated as f_res = 1 / (2π√(L_total*C_total)), where L_total and C_total are the equivalent total inductance and total capacitance. In the trajectory planning algorithm, a parameter can be used to represent the upper limit of the voltage acceleration, such as A_max. When determining A_max, iteration or pre-calculation can be performed. For example, for a given A_max, an S-shaped trajectory is generated through simulation, and then its Fourier transform is performed to analyze the spectral energy E_res at f_res. If E_res is higher than the preset excitation threshold E_threshold, then A_max needs to be reduced, the trajectory is regenerated and analyzed until E_res < E_threshold. The trajectory planning algorithm can adopt an S-shaped curve generator based on a fifth-order polynomial. This generator receives the current voltage, the target voltage, and the calculated upper limit of the second derivative (i.e., the maximum acceleration) as inputs, and outputs a series of voltage reference points that change with time, and these points together form a smooth S-shaped curve.

[0080] By accurately calculating the natural resonance frequency of the system based on the actual LC filter circuit parameters of the system and the distributed parameters of the long-distance transmission cable, and on this basis, specifically setting the upper limit of the second derivative of the smooth voltage reference trajectory so that the spectral energy of this trajectory is lower than the excitation threshold at the natural resonance frequency, this solution can fundamentally avoid exciting the complex resonance system composed of the LC network and the long cable. This effectively solves the problem that the system generates voltage oscillation due to resonance when the voltage command changes, and significantly improves the transient stability of the motor drive system. Compared with the solution that only performs general amplitude limiting constraints, this solution deeply combines trajectory planning with the natural resonance characteristics of the system, realizes more accurate and thorough suppression of oscillations, ensures the smooth operation of the long-distance DC motor during variable voltage speed regulation or commutation, further reduces the transient electromagnetic radiation, and improves the overall reliability of the system.

[0081] In some of the above solutions of this application, a drive control method is proposed to control the motor. However, during the commutation process, if the switch is directly switched, it will cause problems such as arc and current shock.

[0082] In response, this application proposes a method that further includes a zero-current soft-switching commutation step based on observation feedback. This step specifically includes: when a motor commutation command is received, firstly, the trajectory planning algorithm described in step S3 is invoked to generate a falling edge reference trajectory with a target value of zero, and the output of the buck converter circuit is adjusted through step S4; continuously monitoring the estimated value of the motor armature current output in step S2; if and only if the estimated value of the motor armature current is detected to return to zero and remain there for a period exceeding a preset dead time, controlling the polarity switching switch to change the motor connection polarity; after the polarity switching is completed, step S3 is invoked again to generate a rising edge reference trajectory with a target value of the set speed voltage, and motor drive is restored.

[0083] Zero-current soft-switching commutation based on observation feedback refers to performing a switching operation when the current in the circuit drops to zero or near zero, to avoid arcing, transient voltage surges, and electromagnetic interference generated when the switching device opens or closes under current conditions. Observation feedback here refers to using a system model and measurable near-end data to estimate the remote motor armature current, which cannot be directly measured, through a state observer, thereby achieving real-time, non-contact monitoring of the remote current state. This method avoids installing additional current sensors at the remote end, reducing cost and complexity. The motor commutation command is a signal issued by the control system to change the rotation direction of the DC motor. This command can originate from user operation, the upper-level controller, or the internal logic of the motor drive strategy. The trajectory planning algorithm described in step S3 above is invoked to generate a falling-edge reference trajectory with a target value of zero. The trajectory planning algorithm is a mathematical method for generating smooth transition paths, aiming to smoothly change the system state (such as voltage) from the current value to the target value. Here, a falling-edge reference trajectory with a target value of zero means that the voltage will smoothly decrease from the current operating voltage to zero, ensuring that the motor armature current decreases smoothly accordingly. Trajectory planning algorithms can be implemented using various mathematical models, such as polynomial interpolation, S-curve planning, or spline function-based methods. The core principle is to limit the rate of voltage change and its variation to avoid transient impacts. Step S4 adjusts the output of the buck converter circuit, which calculates and outputs the final duty cycle control signal based on the smoothed voltage reference trajectory and line voltage drop compensation. By adjusting the duty cycle of the buck converter circuit, its output voltage can be precisely controlled to follow the reference trajectory generated by the trajectory planning algorithm, thereby achieving smooth control of the motor terminal voltage and consequently, a smooth decrease in the motor armature current. The estimated motor armature current output in step S2 is continuously monitored. Continuous monitoring means that the system continuously acquires and analyzes the estimated motor armature current during commutation. Step S2 uses a state observation algorithm to calculate the estimated value of the far-end motor armature current in real time using near-end voltage and current data. This continuous monitoring is crucial for accurately determining whether the current has returned to zero and is the foundation for soft switching. A zero-current estimate is detected only when it returns to zero and remains so for a duration exceeding a preset dead time. "Zero-current" means the estimated armature current drops below a preset minimum threshold, indicating almost no current flow in the motor circuit. The "preset dead time" is a short delay set to ensure that the current has completely disappeared and the system is in a stable, current-free state. This dead time can be set based on system response speed, switching device characteristics, and safety margins. Polarity switching is only permitted after the current estimate meets the zero-current condition and remains above this dead time to avoid misjudgment and potential current surges.The polarity switching switch is controlled to change the motor's connection polarity. This switch is used to change the polarity of the voltage applied to the DC motor, thereby changing the motor's rotation direction. It is typically composed of power electronic devices such as relays, MOSFETs, or IGBTs. After confirming the current has returned to zero, the controller sends a command to the polarity switching switch to change the state of its internal contacts or semiconductor devices, thus reversing the voltage polarity across the motor. After the polarity switch is complete, step S3 is called again to generate a rising edge reference trajectory with the target voltage as the set speed voltage, and motor drive is resumed. After the polarity switch, the motor needs to restart and reach the target speed. At this point, the trajectory planning algorithm is called again to generate a reference trajectory that smoothly rises from zero voltage to the target speed voltage. This rising edge reference trajectory also has smooth characteristics, ensuring that the motor accelerates smoothly in a controlled manner after commutation, avoiding current surges and mechanical vibrations during startup.

[0084] In long-distance DC motor drive systems, to address the potential arcing and current surges during commutation, this application proposes a zero-current soft-switching commutation method based on observation feedback. When the system receives a motor commutation command, firstly, to ensure the motor armature current smoothly decreases to zero, the system invokes the trajectory planning algorithm described in step S3. This algorithm generates a falling-edge voltage reference trajectory with a target value of zero. This trajectory is smooth and effectively limits the voltage change rate and its rate of change, thus avoiding abrupt current changes. Subsequently, through step S4, the system accurately calculates and outputs the duty cycle control signal of the buck converter circuit based on this falling-edge reference trajectory and the line voltage drop compensation, ensuring that the actual voltage at the motor terminals follows the falling-edge trajectory, thereby guiding the motor armature current to decrease smoothly. Throughout this process, the system continuously monitors the estimated motor armature current output in step S2. Due to the presence of long-distance transmission cables, directly installing current sensors at the motor end is costly and involves complex wiring. However, step S2, through the constructed system dynamics model and state observation algorithm, can accurately estimate the remote motor armature current using measurable voltage and current data from the near end. This observation-based feedback mechanism provides a reliable basis for accurate judgment of the remote current. Only when the estimated value of the motor armature current drops to zero and remains there for more than a preset dead time will the system issue a command to control the polarity switching switch. This dead time is designed to ensure that the current completely disappears, preventing the switch from switching while the current is present, thereby effectively preventing arcing and damage to the switching devices. Once the polarity switching switch completes its action and the motor connection polarity changes, the system calls the trajectory planning algorithm from step S3 again. At this time, the algorithm generates a rising edge reference trajectory with a target value of the set speed voltage. This rising edge trajectory is also smooth, ensuring that the motor can accelerate smoothly in a controlled manner after commutation, avoiding the starting current surge and mechanical vibration that may occur with traditional hard switching methods. Through the organic combination of the above steps, the solution proposed in this application achieves soft switching during the motor commutation process. This not only protects the polarity switching switch and extends its service life, but also significantly reduces electromagnetic interference and mechanical shock generated during commutation, thereby improving the reliability and stability of the entire motor drive system. This solution cleverly utilizes state observation technology to solve the problem of motor commutation in long-distance transmission cable environments without increasing the cost of remote sensors.

[0085] In one specific implementation, upon receiving a motor commutation command, such as when a user presses the window lowering button, the system immediately initiates the commutation process. First, the controller invokes a trajectory planning algorithm based on a fifth-order polynomial. This algorithm calculates a smooth voltage drop curve based on the current motor terminal voltage and the target zero voltage. This curve ensures that the voltage change rate and its rate of change are within preset limits, thus avoiding sudden changes in current. Subsequently, the buck converter circuit precisely adjusts the output voltage along this drop trajectory based on the duty cycle signal calculated in step S4 above. During this period, the system continuously obtains an estimate of the motor armature current from step S2 above. For example, if step S2 uses a Kalman filter, it predicts and corrects the estimated motor armature current in real time based on the near-end voltage and near-end current data at the output port of the buck converter circuit. When this estimated value is below a very small threshold (e.g., 10 mA) for 100 consecutive milliseconds (as the preset dead time), the controller determines that the current has returned to zero. At this point, the controller sends a command to the polarity switching switch (e.g., an H-bridge structure consisting of two relays) to complete the polarity reversal in a current-free state. After the polarity switching is completed, the controller calls the trajectory planning algorithm again to generate a rising edge trajectory that smoothly rises from zero voltage to the target speed voltage (e.g., 12 volts), and drives the motor again through the above steps S4 and the buck converter circuit to smoothly accelerate it to the target speed.

[0086] Through the above technical solution, this application effectively solves the problems of arcing and current surges caused by direct switching during motor commutation. Specifically, by smoothly reducing the motor terminal voltage to zero using a trajectory planning algorithm before commutation, and combining this with precise monitoring of the estimated motor armature current, it ensures that the polarity switching switch only operates after the loop current has completely disappeared. This zero-current soft-switching mechanism significantly extends the service life of the polarity switching switch and avoids contact erosion and mechanical wear. Simultaneously, due to the smooth transition of current and voltage, electromagnetic interference and mechanical shocks generated during commutation are also greatly suppressed, improving the system's electromagnetic compatibility and operational stability. Furthermore, this solution cleverly utilizes the estimated motor armature current provided in step S2, eliminating the need for additional current sensors at the remote end. This achieves highly reliable soft switching while reducing system cost and wiring complexity, providing an economical, efficient, and high-performance commutation solution for long-distance DC motor drive systems.

[0087] In some of the solutions mentioned above in this application, a duty cycle control signal after calculating line voltage drop compensation is proposed to compensate for line voltage drop and generate control signal. However, in this process, without a clear mathematical formula, the compensation calculation may be inaccurate or the implementation efficiency may be low, affecting the control accuracy and thus failing to ensure that the motor terminal voltage stably follows the reference trajectory.

[0088] In this regard, this application further proposes the following formula for calculating the final duty cycle control signal D(t) in step S4:

[0089] in, The instantaneous value of the smoothed voltage reference trajectory output in step S3. The estimated value of the motor armature current output in step S2 is... The equivalent resistance of long-distance transmission cables. This is the DC power supply voltage.

[0090] The final duty cycle control signal D(t) is a key parameter used to control the buck converter circuit, determining its output voltage. The duty cycle D(t) is a dimensionless value between 0 and 1, representing the ratio of the on-time of the switching transistor to the total cycle within one switching cycle. Its function is to precisely adjust the output of the buck converter circuit to achieve precise control of the motor terminal voltage. For example, this signal can be generated using pulse width modulation (PWM) technology, or controlled by outputting an analog voltage signal from a digital-to-analog converter (DAC). Uref(t) represents the instantaneous value of the smooth voltage reference trajectory, which is the desired target value of the motor terminal voltage generated in step S3 above, varying over time. This trajectory has been processed by a trajectory planning algorithm, possessing continuous second derivatives, and its rate of change and amplitude are constrained to provide a smooth, oscillating voltage command, avoiding transient oscillations in the system. It can be a series of voltage values ​​pre-stored in a lookup table, or a voltage sequence calculated in real-time by the trajectory planning algorithm. Iest(t) represents the estimated value of the motor armature current, which is calculated in real time in step S2 above using a near-end sampling-based far-end state observation algorithm. Due to the presence of long-distance transmission cables, directly measuring the current at the motor end is difficult and costly. Therefore, a state observer is used to estimate the motor armature current to provide accurate real-time current information. This estimated value can be the output of a state observation algorithm such as a Luneburger observer or a Kalman filter, or a value derived based on the system dynamics model and near-end measurement data. Rline represents the equivalent resistance of the long-distance transmission cable. The resistance of the long-distance transmission cable causes a line voltage drop, resulting in a difference between the output voltage at the power supply end and the actual voltage at the motor end. Rline is used to quantify this voltage drop and is a key parameter for voltage drop compensation. This parameter can be obtained through the system initialization detection sub-step (as described in claim 2 above), or by consulting the cable specification manual or performing offline measurements. Udc represents the DC power supply voltage, i.e., the output voltage of the DC power supply that provides energy to the entire motor drive system. It is the input voltage of the buck converter circuit and also the reference for voltage conversion when calculating the duty cycle. This voltage is usually constant; for example, it can be the voltage of a vehicle battery or an industrial DC bus, or it can be a stable DC voltage after rectification and filtering. Calculation formula This formula is used to superimpose the desired motor terminal voltage (Uref(t)) with the line voltage drop compensation (Iest(t)×Rline) to obtain the compensated target output voltage, which is then normalized to the duty cycle D(t) to control the buck converter circuit. Through this formula, the system can accurately calculate the duty cycle required to drive the buck converter circuit in real time, thereby offsetting the line voltage drop caused by long-distance transmission cables and ensuring that the actual motor terminal voltage accurately follows the smooth voltage reference trajectory.

[0091] This scheme provides a clear mathematical expression to precisely quantify the key aspects of the low electromagnetic emission drive control method for long-distance DC motors—line voltage drop compensation and duty cycle generation. In the entire control process, firstly, the system obtains the real-time estimated value of the motor armature current Iest(t) through near-end sampling-based far-end state observation in step S2. This estimated value accurately reflects the actual load current at the motor end. Simultaneously, step S3 generates a smooth voltage reference trajectory Uref(t), which is a carefully planned instantaneous target value of the desired motor end voltage; its smoothness helps suppress system oscillations. In step S4, which calculates the duty cycle control signal after line voltage drop compensation, this scheme multiplies the real-time estimated value of the motor armature current Iest(t) with the pre-determined equivalent resistance Rline of the long-distance transmission cable, thereby accurately calculating the line voltage drop compensation amount at the current moment. This compensation amount directly reflects the voltage loss caused by the cable resistance. Subsequently, this line voltage drop compensation amount is superimposed on the smooth voltage reference trajectory Uref(t) to obtain a compensated target output voltage. The compensated target output voltage represents the voltage value that the buck converter circuit needs to output to offset the line voltage drop and achieve Uref(t) at the motor end. Finally, dividing this compensated target output voltage by the DC power supply voltage Udc yields the final duty cycle control signal D(t). The introduction of this calculation formula enables the entire control system to accurately compensate for the line voltage drop of long-distance transmission cables in real time and dynamically. By combining the real-time current estimate provided in step S2 with the smooth voltage reference trajectory provided in step S3, and utilizing the known cable resistance and power supply voltage, the system can generate a highly accurate duty cycle control signal. This signal is then used in step S5 to drive the buck converter circuit, ensuring that the actual voltage output by the buck converter circuit, after passing through the LC filter circuit and the long-distance transmission cable, closely follows the smooth voltage reference trajectory Uref(t) at the motor end. This precise compensation mechanism effectively solves the problem of decreased motor control accuracy caused by the line voltage drop of long-distance transmission cables, making the control of motor speed and torque more accurate, while maintaining the smoothness of the system output and avoiding unnecessary transient oscillations.

[0092] As a specific implementation, the method for calculating the final duty cycle control signal D(t) described above can be implemented by an embedded controller or digital signal processor (DSP). For example, the main controller in the system can be an STM32 series microcontroller or a TI C2000 series DSP. This controller integrates an analog-to-digital converter (ADC) for acquiring near-end voltage and near-end current data, and has sufficient processing power to run state observation algorithms (such as a Luenberger observer or a Kalman filter) to obtain the estimated motor armature current Iest(t). Simultaneously, the controller can execute a trajectory planning algorithm to generate a smooth voltage reference trajectory Uref(t). When calculating the duty cycle, the controller reads the preset values ​​of the equivalent resistance Rline of the long-distance transmission cable and the DC power supply voltage Udc from its memory. Then, the controller calculates the duty cycle according to the formula... Real-time and The sums are then divided by Udc to obtain the current duty cycle D(t). This calculation result is subsequently output through the controller's pulse width modulation (PWM) module to generate a corresponding PWM signal to drive the switching transistors of the buck converter circuit. The entire calculation and output process can be completed within each control cycle, for example, refreshed at a frequency of 10kHz or higher to ensure the real-time performance and accuracy of the control.

[0093] Through the above technical solution, this application provides a clear and operable duty cycle calculation formula, effectively solving the problem of inaccurate or inefficient line voltage drop compensation calculation in long-distance DC motor drives, which in turn affects control accuracy. This formula achieves precise quantification and compensation of line voltage drop by combining the estimated motor armature current, smooth voltage reference trajectory, cable equivalent resistance, and DC power supply voltage in real time. This enables the buck converter circuit to output a precisely adjusted voltage, ensuring that the actual physical voltage at the motor terminals can stably and accurately follow the desired smooth voltage reference trajectory. Therefore, this solution significantly improves the control accuracy of motor speed and torque, avoids control deviations caused by line voltage drop, simplifies the controller implementation logic, and improves the overall performance and reliability of the system.

[0094] In some of the solutions described above in this application, a state observation algorithm is proposed to provide an estimated value of the motor armature current during motor commutation, so as to monitor the current returning to zero and realize soft switching. However, in this process, if the accuracy of the observation algorithm is insufficient or the anti-interference ability is weak, the current estimation value may be deviated, thereby misjudging the current state during commutation, causing arcing and current surges, damaging the switch life and generating electromagnetic interference.

[0095] To address this, this application further proposes an improved scheme. In this scheme, the state observation algorithm can employ a Luenberger observer or a Kalman filter. A state observation algorithm is a mathematical tool used to estimate internal, non-measurable state variables of a system. The Luenberger observer is a linear state estimator based on a system model and measurable output; it designs a gain matrix to dynamically converge the observer's error. The Kalman filter, on the other hand, is an optimal linear filter that recursively estimates the system state using the system's dynamic model and the statistical characteristics of measurement noise, making it particularly suitable for systems with random noise. Both observers can estimate the internal state of the system in real time based on the system's input and output data, combined with the system's dynamic model. For example, the Luenberger observer can be implemented by constructing an observer model with the same dynamic characteristics as the original system and designing a suitable observer gain matrix. This gain matrix is ​​typically designed using the pole placement method or the linear matrix inequality (LMI) method to ensure rapid convergence of the observation error. For example, a Kalman filter can be implemented by defining the state-space model of the system, the process noise covariance matrix, and the measurement noise covariance matrix. Its core lies in the two steps of prediction and updating, and the state estimate is continuously corrected through iterative calculation.

[0096] In this scheme, the near-end voltage and near-end current data at the output port of the buck converter circuit are used as observed variables. Observed variables refer to physical quantities that can be directly measured and used for state estimation in the actual system. The near-end voltage and near-end current data refer to the voltage and current measured at the output port of the buck converter circuit, i.e., the starting end of a long-distance transmission cable. These variables are external information directly obtainable by the system, providing the necessary input data for the state observation algorithm. For example, near-end voltage data can be acquired by connecting a voltage sensor (such as a voltage divider resistor network combined with an ADC) in parallel at the output port of the buck converter circuit. Alternatively, near-end current data can be acquired by connecting a current sensor (such as a Hall current sensor or a sampling resistor combined with a differential amplifier) ​​in series at the output port of the buck converter circuit.

[0097] Meanwhile, the estimated values ​​of the motor terminal voltage and the motor armature current are used as state variables. State variables are the smallest set of variables that can completely describe the dynamic behavior of the system. The estimated value of the motor terminal voltage refers to the estimated value of the actual voltage at the end of the long-distance transmission cable, i.e., at both ends of the DC motor. The estimated value of the motor armature current refers to the estimated value of the current flowing through the armature winding of the DC motor. These variables are key parameters for system operation, but due to the presence of long-distance transmission cables, they cannot be directly measured at the source end and need to be estimated through state observation algorithms. Specifically, the estimated value of the motor terminal voltage reflects the actual voltage experienced by the motor and directly affects the motor speed; the estimated value of the motor armature current reflects the actual load condition of the motor, directly affects the motor torque, and is a key basis for determining when the current returns to zero during commutation.

[0098] Furthermore, the prediction error of the system dynamics model described in step S1 is corrected in real time using a correction matrix. The correction matrix is ​​a key component of the state observation algorithm; it is used to feed back the difference between the observed variables (actual measured values) and the output predicted by the system dynamics model into the state estimation process, thereby correcting the model's prediction error. This real-time correction mechanism ensures the accuracy and robustness of the state estimation, allowing the estimated value to approximate the true value even if the system model has certain uncertainties or is subject to external disturbances. For example, in a Romberg observer, the correction matrix is ​​the observer gain matrix L, which multiplies the measurement error by a gain and adds it to the state prediction value to correct the state estimation. Similarly, in a Kalman filter, the correction matrix is ​​the Kalman gain K, which dynamically adjusts the degree of correction of the measured value to the state estimation based on the prediction error covariance and the measurement noise covariance to achieve optimal estimation.

[0099] This application's solution constructs a robust and accurate far-end state estimation mechanism by combining an advanced state observation algorithm with a system dynamics model and real-time measurement data. Specifically, during system operation, the output port of the buck converter circuit collects near-end voltage and near-end current data in real time as observation variables. These observation variables, along with the source-line-load system dynamics model constructed in step S1, are input into the state observation algorithm. This algorithm, whether using a Luneburger observer or a Kalman filter, can predict state variables such as motor terminal voltage and motor armature current using the system dynamics model. Simultaneously, through a correction matrix, the actually collected near-end voltage and near-end current data are compared with the model's predicted output, and the estimated values ​​of the state variables are corrected in real time based on the difference between the two. This real-time feedback correction mechanism enables the state observation algorithm to effectively handle system dynamic changes and external noise, thereby providing more stable and accurate estimates of motor terminal voltage and motor armature current. This accurate estimate of the motor armature current is crucial for the aforementioned zero-current soft-switching commutation step based on observation feedback. Upon receiving a motor commutation command, the system first adjusts the output of the buck converter circuit using a trajectory planning algorithm, gradually reducing the motor armature current. During this time, a state observation algorithm continuously provides a high-precision estimate of the motor armature current. Only when this estimate is detected to have returned to zero and remained there for more than a preset dead time is the polarity switching switch activated. This mechanism avoids directly switching polarity when current exists in the circuit, effectively preventing arcing and current surges. In this way, the proposed solution achieves accurate perception of the remote motor status without increasing the cost of motor-end sensors and filters, providing highly reliable, shock-free soft-switching capabilities for long-distance DC motor drive systems.

[0100] As a specific implementation, the aforementioned state observation algorithm can be implemented using a high-performance microcontroller (e.g., an STM32 series microcontroller based on an ARM Cortex-M4 or M7 core). This microcontroller integrates a high-speed analog-to-digital converter (ADC) and a floating-point unit (FPU). At the output port of the buck converter circuit, a high-precision voltage sensor (e.g., based on a resistor divider network and an isolation amplifier) ​​and a high-precision current sensor (e.g., a current sensor based on the Hall effect principle) can be configured to acquire near-end voltage and near-end current data in real time. The analog output signals from these sensors are conditioned and then fed into the microcontroller's ADC for digitization. The firmware running inside the microcontroller implements a discretized Kalman filter algorithm. The system dynamics model parameters of this algorithm (such as the output impedance parameters of the buck converter circuit, the electrical parameters of the LC filter circuit, the distributed parameters of long-distance transmission cables, and the electrical parameters of the DC motor) are loaded during system initialization. The Kalman gain matrix can be calculated offline based on the system noise characteristics and measurement noise characteristics and stored in the microcontroller, or adaptively adjusted during runtime. The microcontroller performs the prediction and update steps of the Kalman filter at a fixed sampling period (e.g., every 100 microseconds), outputting real-time estimates of the motor terminal voltage and motor armature current. These estimates are then used to drive the control logic, specifically to monitor whether the estimated motor armature current returns to zero, triggering the polarity switching switch to achieve soft-switching commutation.

[0101] Through the above technical solution, this application significantly improves the accuracy and robustness of remote motor state estimation in long-distance DC motor drive systems. By employing advanced state observation algorithms such as Luneburger observers or Kalman filters, combined with a real-time correction mechanism, it is possible to accurately estimate the motor terminal voltage and armature current, which cannot be directly measured, even relying solely on measurable data from the near end. This high-precision estimation capability, especially during motor commutation, reliably monitors whether the motor armature current has truly returned to zero, thus avoiding misjudgments caused by observation errors. Therefore, when performing zero-current soft-switching commutation steps based on observation feedback, it ensures that the polarity switching switch operates in a state of no current or extremely low current, effectively preventing the generation of arcs and the damage to switch life caused by current surges, and eliminating the resulting electromagnetic interference. Furthermore, this solution avoids installing additional sensors at the remote motor, reducing system cost and complexity, while improving the overall reliability and control accuracy of the system.

[0102] Example 2 This embodiment is an improvement upon Embodiment 1. The similarities with Embodiment 1 will not be elaborated further here. This embodiment provides a long-distance DC motor low electromagnetic emission drive control system applying the aforementioned long-distance DC motor low electromagnetic emission drive control method, such as... Figure 4 As shown, the system is applied to a motor drive system, and the system sequentially includes a DC power supply, a step-down converter circuit, an LC filter circuit, a polarity switching switch, a long-distance transmission cable, and a DC motor; the method includes the following steps: A construction module is used to construct a dynamic model of a source-line-load system; obtain the output impedance parameters of the buck converter circuit, the electrical parameters of the LC filter circuit, the distributed parameters of the long-distance transmission cable, and the electrical parameters of the DC motor, and establish a full-order state equation of the system that includes the above parameters; based on the full-order state equation of the system, define a set of state variables, which at least includes the estimated values ​​of the voltage at the end of the long-distance transmission cable and the estimated values ​​of the armature current of the motor, which cannot be directly measured. The execution module is used to perform remote state observation based on near-end sampling; it collects near-end voltage data and near-end current data in real time at the output port of the buck converter circuit; it uses the near-end voltage data and near-end current data as inputs and substitutes them into the system dynamics model constructed in step S1, and solves them in real time through the state observation algorithm to output the estimated value of the motor terminal voltage and the estimated value of the motor armature current at the end of the long-distance transmission cable. The production module is used to generate a vibration-damping flexible voltage reference trajectory; determine the target voltage value in response to external control commands; calculate the path from the current voltage to the target voltage using a trajectory planning algorithm with continuous second derivatives, and impose amplitude constraints on the voltage change rate and its change rate, and output a smooth voltage reference trajectory that changes over time. The calculation module is used to calculate the duty cycle control signal after line voltage drop compensation; receive the estimated value of motor armature current output in step S2 and the smoothed voltage reference trajectory output in step S3; calculate the line voltage drop compensation amount based on the equivalent resistance parameters of the long-distance transmission cable; superimpose the line voltage drop compensation amount onto the smoothed voltage reference trajectory to obtain the compensated target output voltage, and convert it into the final conduction duty cycle control signal according to the DC power supply voltage; The output module is used to drive execution and feedforward compensation drive; the final conduction duty cycle control signal generated in step S4 is used to drive the buck converter circuit, so that the actual voltage output by the buck converter circuit, after passing through the LC filter circuit and long-distance transmission cable, presents the actual physical voltage at the motor end following the smooth voltage reference trajectory.

[0103] In addition, the parts of the technical solutions provided in the embodiments of this application that are consistent with the implementation principles of the corresponding technical solutions in the prior art have not been described in detail, so as to avoid excessive elaboration.

[0104] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A low electromagnetic emission drive control method for a long-distance DC motor, applied to a motor drive system, wherein the system sequentially comprises a DC power supply, a step-down converter circuit, an LC filter circuit, a polarity switching switch, a long-distance transmission cable, and a DC motor; characterized in that, The method includes the following steps: Step S1: Construct a source-line-load system dynamic model; obtain the output impedance parameters of the buck converter circuit, the electrical parameters of the LC filter circuit, the distributed parameters of the long-distance transmission cable, and the electrical parameters of the DC motor, and establish the full-order state equation of the system including the above parameters; based on the full-order state equation of the system, define a set of state variables, which includes at least the estimated voltage at the end of the long-distance transmission cable and the estimated armature current of the motor, which cannot be directly measured. Step S2: Perform remote state observation based on near-end sampling; collect near-end voltage data and near-end current data in real time at the output port of the buck converter circuit; use the near-end voltage data and near-end current data as input quantities, substitute them into the system dynamics model constructed in step S1, and solve them in real time through the state observation algorithm to output the estimated values ​​of the motor terminal voltage and the motor armature current at the end of the long-distance transmission cable. Step S3: Generate a vibration-damping flexible voltage reference trajectory; determine the target voltage value in response to external control commands; calculate the path from the current voltage to the target voltage using a trajectory planning algorithm with continuous second derivatives, and impose amplitude constraints on the voltage change rate and its change rate to output a smooth voltage reference trajectory that changes over time. Step S4: Calculate the duty cycle control signal after line voltage drop compensation; receive the estimated value of motor armature current output in step S2 and the smoothed voltage reference trajectory output in step S3; calculate the line voltage drop compensation amount based on the equivalent resistance parameters of the long-distance transmission cable; superimpose the line voltage drop compensation amount onto the smoothed voltage reference trajectory to obtain the compensated target output voltage, and convert it into the final conduction duty cycle control signal according to the DC power supply voltage; Step S5: Drive execution and feedforward compensation drive; use the final conduction duty cycle control signal generated in step S4 to drive the buck converter circuit, so that the actual voltage output by the buck converter circuit, after passing through the LC filter circuit and long-distance transmission cable, presents the actual physical voltage at the motor end following the smooth voltage reference trajectory.

2. The method according to claim 1, characterized in that, In step S1, the process of acquiring the distributed parameters of the long-distance transmission cable also includes a system initialization detection sub-step: before the motor starts, the step-down converter circuit is controlled to output a fixed low voltage lower than the motor starting threshold; the steady-state current value and voltage value at this time are collected; the total circuit resistance parameter including the resistance of the long-distance transmission cable and the resistance of the motor winding is calculated based on Ohm's law, and the total circuit resistance parameter is updated to the system dynamic model for observation in step S2 and voltage drop compensation calculation in step S4.

3. The method according to claim 1, characterized in that, In step S3, the specific method for limiting the voltage change rate and its amplitude is as follows: based on the LC filter circuit parameters and the distribution parameters of the long-distance transmission cable in step S1, the inherent resonant frequency of the system is calculated; the upper limit of the second derivative of the smooth voltage reference trajectory is set so that the spectral energy corresponding to the reference trajectory is lower than the excitation threshold of the inherent resonant frequency, thereby outputting an S-shaped voltage curve that can suppress the oscillation of the LC network and the long cable as the smooth voltage reference trajectory.

4. The method according to claim 1, characterized in that, The method further includes a zero-current soft-switching commutation step based on observation feedback. This step specifically includes: when a motor commutation command is received, the trajectory planning algorithm described in step S3 is first invoked to generate a falling edge reference trajectory with a target value of zero, and the output of the buck converter circuit is adjusted in step S4; the estimated value of the motor armature current output in step S2 is continuously monitored; if and only if the estimated value of the motor armature current is detected to return to zero and remain there for a period exceeding a preset dead time, the polarity switching switch is controlled to change the motor connection polarity; after the polarity switching is completed, step S3 is invoked again to generate a rising edge reference trajectory with a target value of a set speed voltage, and the motor drive is restored.

5. The method according to claim 1, characterized in that, In step S4, the final on-duty cycle control signal The calculation formula is as follows: ， in, The instantaneous value of the smoothed voltage reference trajectory output in step S3. The estimated value of the motor armature current output in step S2 is... The equivalent resistance of long-distance transmission cables. This is the DC power supply voltage.

6. The method according to claim 4, characterized in that, The state observation algorithm uses a Luenberger observer or a Kalman filter. It uses the near-end voltage and near-end current at the output of the buck converter circuit as observation variables and the motor terminal voltage and armature current as state variables. It corrects the prediction error of the system dynamics model described in step S1 in real time through a correction matrix.

7. A low electromagnetic emission drive control system for a long-distance DC motor using the method described in any one of claims 1 to 6, characterized in that, The method is applied to a motor drive system, which sequentially includes a DC power supply, a step-down converter circuit, an LC filter circuit, a polarity switching switch, a long-distance transmission cable, and a DC motor; the method includes the following steps: A construction module is used to construct a dynamic model of a source-line-load system; obtain the output impedance parameters of the buck converter circuit, the electrical parameters of the LC filter circuit, the distributed parameters of the long-distance transmission cable, and the electrical parameters of the DC motor, and establish a full-order state equation of the system that includes the above parameters; based on the full-order state equation of the system, define a set of state variables, which at least includes the estimated values ​​of the voltage at the end of the long-distance transmission cable and the estimated values ​​of the armature current of the motor, which cannot be directly measured. The execution module is used to perform remote state observation based on near-end sampling; it collects near-end voltage data and near-end current data in real time at the output port of the buck converter circuit; it uses the near-end voltage data and near-end current data as inputs and substitutes them into the system dynamics model constructed in step S1, and solves them in real time through the state observation algorithm to output the estimated value of the motor terminal voltage and the estimated value of the motor armature current at the end of the long-distance transmission cable. The production module is used to generate a vibration-damping flexible voltage reference trajectory; determine the target voltage value in response to external control commands; calculate the path from the current voltage to the target voltage using a trajectory planning algorithm with continuous second derivatives, and impose amplitude constraints on the voltage change rate and its change rate, and output a smooth voltage reference trajectory that changes over time. The calculation module is used to calculate the duty cycle control signal after line voltage drop compensation; receive the estimated value of motor armature current output in step S2 and the smoothed voltage reference trajectory output in step S3; calculate the line voltage drop compensation amount based on the equivalent resistance parameters of the long-distance transmission cable; superimpose the line voltage drop compensation amount onto the smoothed voltage reference trajectory to obtain the compensated target output voltage, and convert it into the final conduction duty cycle control signal according to the DC power supply voltage; The output module is used to drive execution and feedforward compensation drive; the final conduction duty cycle control signal generated in step S4 is used to drive the buck converter circuit, so that the actual voltage output by the buck converter circuit, after passing through the LC filter circuit and long-distance transmission cable, presents the actual physical voltage at the motor end following the smooth voltage reference trajectory.

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