High-efficiency energy-saving high-power permanent magnet synchronous servo motor closed-loop control system
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHANGZHOU WUJIN JINBAO MOTOR
- Filing Date
- 2026-03-20
- Publication Date
- 2026-06-09
AI Technical Summary
In existing high-performance vector control of permanent magnet synchronous servo motors, the fixed current distribution strategy cannot respond to the real-time dynamic changes in load torque, speed and DC bus voltage of the motor, resulting in low system efficiency under non-design point operating conditions, especially significant energy loss in high-power applications.
The data acquisition module acquires three-phase current, rotor position angle and DC bus voltage in real time. Direct-axis and quadrature-axis current components are generated through coordinate transformation. The optimal current setpoint is calculated online by the efficiency optimization module. The ratio of direct-axis to quadrature-axis current is dynamically adjusted. A loss model is constructed for iterative optimization. The current setpoint is generated and proportional-integral adjustment is performed. Finally, the pulse width modulation signal of the inverter bridge is generated.
It achieves adaptive efficiency optimization of the motor across the entire operating range, reduces system energy consumption, improves continuous overload capacity and power density for high-power applications, and meets the requirements of high efficiency, energy saving and high power output.
Smart Images
Figure CN122178780A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of permanent magnet synchronous motor servo control technology, specifically a high-efficiency, energy-saving, high-power permanent magnet synchronous servo motor closed-loop control system. Background Technology
[0002] In high-performance vector control of permanent magnet synchronous servo motors, conventional techniques generally employ pre-set current distribution strategies. The most common is id=0 control, which forces the direct-axis current to zero to achieve decoupling. For high-speed operation, the current is typically given based on a field weakening curve table calculated offline based on the motor's nominal parameters. The core of these methods lies in the fact that their current command is static or piecewise feedforward based on speed, relying on a mathematical model of the motor under specific ideal operating conditions.
[0003] The aforementioned static current distribution strategy has flaws. The actual operating state of the motor, including load torque, speed, and DC bus voltage, is constantly and dynamically changing. This causes the proportional relationships of various internal losses, such as stator copper losses and core losses, to change in real time. A fixed current setpoint cannot respond to these real-time changes, preventing the system from operating at its optimal efficiency under a wide range of conditions deviating from the design point, resulting in additional energy losses. This problem is particularly prominent in high-power applications.
[0004] A control method is needed that can dynamically optimize based on real-time operating parameters. This method must automatically adjust control commands directly based on the system's real-time electrical state to achieve efficiency optimization across the entire operating range. Furthermore, addressing the challenge of more complex loss characteristics during high-power operation, the optimization model of this method must be able to comprehensively handle multi-dimensional losses under high power density, thereby meeting the dual objectives of high efficiency and energy saving, and high power output. Summary of the Invention
[0005] This invention aims to solve at least one of the technical problems existing in the prior art; Therefore, this invention proposes a high-efficiency, energy-saving, high-power permanent magnet synchronous servo motor closed-loop control system, comprising: The data acquisition module is used to collect the three-phase current value, rotor position angle and DC bus voltage value of the permanent magnet synchronous servo motor in real time. The coordinate transformation module is used to perform Clarke transformation and Park transformation on the three-phase current values to generate direct-axis current components and quadrature-axis current components. The rotational speed and angle module is used to calculate the real-time electrical angular velocity and electrical angle of the rotor based on the rotor position angle. The efficiency optimization module is used to perform online efficiency optimization calculations based on the DC bus voltage value, the direct-axis current component, and the quadrature-axis current component, and to generate direct-axis current setpoints and quadrature-axis current setpoints.
[0006] Further, the step of performing Clarke transform and Park transform on the three-phase current values to generate direct-axis current components and quadrature-axis current components includes: The three-phase current values are transformed into alpha-axis current components and beta-axis current components in a stationary two-phase coordinate system. Based on the real-time electrical angle, the alpha axis current component and the beta axis current component are transformed into a rotating two-phase coordinate system, and the direct axis current component representing the excitation current and the quadrature axis current component representing the torque current are output.
[0007] Further, the step of performing online efficiency optimization calculations based on the DC bus voltage value, the direct-axis current component, and the quadrature-axis current component to generate direct-axis current setpoints and quadrature-axis current setpoints includes: Estimate the motor operating voltage boundary under the current power supply conditions based on the DC bus voltage value; A motor loss model is constructed with the direct-axis current component and the quadrature-axis current component as variables. The motor loss model includes copper loss calculation items, iron loss calculation items, and stray loss compensation items. Under the constraints of satisfying the motor operating voltage boundary and output torque requirements, the combination ratio of the direct-axis current component and the quadrature-axis current component is iteratively adjusted to solve for the minimum point of the motor loss model. The combination of current components corresponding to the minimum point is determined as the optimal efficiency point under the current operating conditions, and the current value corresponding to the optimal efficiency point is output as the direct-axis current setpoint and the quadrature-axis current setpoint.
[0008] Furthermore, the construction of the motor loss model using the direct-axis current component and the quadrature-axis current component as variables includes: Based on the stator resistance parameters of the permanent magnet synchronous servo motor, the direct-axis current component and the quadrature-axis current component, the copper loss of the stator winding is calculated; Based on the DC bus voltage value, the real-time electric angular velocity, and the material characteristics of the motor core, calculate the eddy current loss and hysteresis loss of the motor core. By querying a pre-calibrated stray loss mapping table, the estimated stray loss values corresponding to the current direct-axis current component, the quadrature-axis current component, and the real-time electric angular velocity are obtained. The estimated values of copper loss, eddy current loss, hysteresis loss, and stray loss are summed to obtain the total loss value, which is then used as the output of the motor loss model.
[0009] Furthermore, the method also includes: The direct-axis current setpoint is compared with the direct-axis current component to obtain the direct-axis current error value; The cross-axis current setpoint is compared with the cross-axis current component to obtain the cross-axis current error value; The direct-axis current error value and the quadrature-axis current error value are respectively subjected to proportional-integral adjustment processing to generate direct-axis voltage compensation value and quadrature-axis voltage compensation value.
[0010] Furthermore, the method also includes: Obtain the electrical angular velocity setpoint issued by the upper-level controller; The electric angular velocity setpoint is compared with the real-time electric angular velocity to obtain the electric angular velocity error value; The electrical angular velocity error value is subjected to proportional-integral adjustment processing to generate an additional setpoint value for the quadrature-axis current; The additional given value of the quadrature-axis current is superimposed on the given value of the quadrature-axis current obtained by efficiency optimization to form the final comprehensive given value of the quadrature-axis current.
[0011] Further, the step of performing proportional-integral adjustment processing on the electrical angular velocity error value to generate an additional setpoint value for the quadrature-axis current includes: The electric angular velocity error value is processed by a variable gain proportional-integral (PII) controller, and the proportional coefficient and integral time constant of the PII controller are adaptively adjusted according to the magnitude of the real-time electric angular velocity. When the real-time electric angular velocity is lower than a set threshold, a proportional coefficient greater than the preset average value and an integral time constant greater than the preset average value are used to enhance low-speed stability. When the real-time electric angular velocity is higher than the set threshold, a proportional coefficient less than the preset average value and an integral time constant less than the preset average value of the integral time constant are used to improve the dynamic response speed.
[0012] Furthermore, the method also includes: The direct-axis voltage compensation value and the quadrature-axis voltage compensation value are subjected to Parker inverse transformation to obtain the alpha-axis voltage component and beta-axis voltage component in the stationary two-phase coordinate system. The alpha axis voltage component and the beta axis voltage component are subjected to space vector pulse width modulation processing to generate six pulse width modulation signals for driving the inverter bridge.
[0013] Further, the step of performing space vector pulse width modulation processing on the alpha axis voltage component and the beta axis voltage component to generate six pulse width modulation signals for driving the inverter bridge includes: The magnitude and phase angle of the reference voltage vector are calculated based on the alpha-axis voltage component and the beta-axis voltage component. Based on the phase angle of the reference voltage vector, determine the sector in which it is located and the two basic non-zero voltage vectors and the zero vector corresponding to the sector; Based on the volt-second balance principle, the duration of action of the two fundamental non-zero voltage vectors and the zero vector is calculated. The duty cycle sequence of the six pulse width modulation signals is generated according to the said action time.
[0014] Furthermore, the method also includes: Real-time monitoring of the stator winding temperature and radiator temperature of the permanent magnet synchronous servo motor; The current safety limit in the online efficiency optimization calculation is dynamically adjusted based on the difference between the rate of change of the stator winding temperature and the radiator temperature. When the stator winding temperature exceeds the warning threshold, under the premise of ensuring the output torque, the combination of current components that can reduce the winding temperature rise is preferentially used to update the direct-axis current setpoint and the quadrature-axis current setpoint.
[0015] Compared with the prior art, the beneficial effects of the present invention are: By performing online efficiency optimization calculations based on real-time variables such as DC bus voltage and direct-axis and quadrature-axis current components, and dynamically generating current setpoints, the system can respond in real-time to fluctuations in load, speed, and voltage. The optimization algorithm calculates the total system losses based on the current operating point and automatically adjusts the distribution ratio of direct-axis and quadrature-axis currents, ensuring the motor is always driven near the minimum loss or high-efficiency region. This dynamic adjustment overcomes the limitations of fixed strategies, achieving adaptive efficiency optimization across the entire operating range and directly reducing the overall energy consumption of the system under varying operating conditions.
[0016] The optimization model and algorithm, specifically designed for the operating characteristics of high-power servo motors, comprehensively consider factors such as the significantly increased core and copper losses under high flux density and high current, as well as inverter switching losses. Through online optimization, it intelligently balances different loss components to find the globally optimal efficiency point for the current power level while ensuring output torque and dynamic response. This enables the motor to effectively suppress temperature rise, improve continuous overload capacity and power density during high torque output or high-speed operation, and meet the core requirements of efficiency and heat dissipation for high-power applications. Attached Figure Description
[0017] Figure 1 This is a timing diagram of the high-efficiency, energy-saving, high-power permanent magnet synchronous servo motor closed-loop control system described in this invention. Figure 2 A flowchart for calculating the current setpoint for online efficiency optimization; Figure 3 Line graph showing the adaptive adjustment of parameters for a variable gain PI controller; Figure 4 The temperature dynamic monitoring curve of the permanent magnet synchronous servo motor; Figure 5 This is a monitoring curve showing the linkage between temperature and current safety constraints for a permanent magnet synchronous servo motor. Detailed Implementation
[0018] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0019] See Figure 1 The implementation scheme of the high-efficiency and energy-saving high-power permanent magnet synchronous servo motor closed-loop control system is based on the real-time acquisition of the three-phase current values, rotor position angle, and DC bus voltage values of the permanent magnet synchronous servo motor. This data is acquired through a data acquisition module. The coordinate transformation module performs Clark and Park transformations on the three-phase current values to generate direct-axis and quadrature-axis current components. The speed and angle module calculates the real-time electrical angular velocity and electrical angle of the rotor based on the rotor position angle. The efficiency optimization module performs online efficiency optimization calculations based on the DC bus voltage value, direct-axis current component, and quadrature-axis current component, generating direct-axis and quadrature-axis current setpoints.
[0020] In one embodiment of the present invention, the coordinate transformation module receives the three-phase current values of the permanent magnet synchronous servo motor collected in real time by the data acquisition module. The three-phase current values include the A-phase current value, the B-phase current value, and the C-phase current value. In one implementation scenario, a typical set of three-phase current values are 1.5 amperes, -0.8 amperes, and -0.7 amperes, respectively. The coordinate transformation module first performs Clark transformation processing on these three-phase current values.
[0021] In some embodiments, the Clarke transform converts the three-phase current values in a stationary three-phase coordinate system into alpha-axis and beta-axis current components in a stationary two-phase coordinate system. This transformation follows the mapping relationship from three-phase to two-phase in electrical machinery, and its mathematical expression can be described by the following formula:
[0022] in: , , These represent the instantaneous current values of phases A, B, and C, respectively. and These represent the alpha-axis current component and beta-axis current component in the transformed stationary two-phase coordinate system, respectively, with coefficients... These are transformation coefficients, and their values are [values] under the power constant constraint. For the three-phase current values in the aforementioned example, the corresponding alpha axis current component is approximately 1.372 amperes and the beta axis current component is approximately 0.433 amperes, as calculated.
[0023] In practice, the coordinate transformation module then performs Parker transformation. The Parker transformation requires real-time electrical angles calculated by the rotational speed angle module. The real-time electrical angles reflect the instantaneous positions of the rotor magnetic poles within the electrical cycle. In one example, the real-time electrical angle is 0.785 radians. The coordinate transformation module transforms the alpha axis current components and beta axis current components in the stationary two-phase coordinate system to a two-phase rotating coordinate system that rotates synchronously with the rotor.
[0024] Optionally, the Parker transform process performs a rotational transformation on the alpha axis current component and the beta axis current component based on the real-time electrical angle, thereby outputting the direct-axis current component and the quadrature-axis current component in the rotating two-phase coordinate system. The direct-axis current component represents the excitation current component of the motor, and the quadrature-axis current component represents the torque current component of the motor. For the alpha axis current component of 1.372 amps, the beta axis current component of 0.433 amps, and the real-time electrical angle of 0.785 radians in the previous example, after the rotational transformation calculation, the obtained direct-axis current component is approximately 1.0 amps, and the quadrature-axis current component is approximately 1.0 amps.
[0025] It is understood that the coordinate transformation module continuously executes the aforementioned Clarke transform and Park transform processes. The time-varying three-phase current value in the stationary three-phase coordinate system is decomposed into independent direct-axis current components and quadrature-axis current components in the rotating coordinate system. The values of these two components are directly provided to the efficiency optimization module for calculation. In some embodiments, the calculation cycle of the coordinate transformation module is synchronized with the sampling cycle of the data acquisition module to ensure the real-time performance of the current feedback. Optionally, for high-power servo motor applications, the three-phase current value may contain high-frequency harmonic components introduced by pulse width modulation. In specific implementations, a low-pass digital filter can be configured at the front end of the coordinate transformation module to preprocess the original three-phase current value to filter out switching harmonics above a certain frequency, thereby ensuring that the current value undergoing coordinate transformation is an effective value reflecting the fundamental component.
[0026] In one embodiment of the present invention, see [reference] Figure 2The efficiency optimization module receives the DC bus voltage value from the data acquisition module, the direct-axis current component and quadrature-axis current component output from the coordinate transformation module, and the real-time electrical angular velocity output from the speed angle module. The efficiency optimization module first estimates the motor operating voltage boundary under the current power supply conditions based on the DC bus voltage value. In an example scenario, the DC bus voltage value is 600 volts. Considering the on-state voltage drop and safety margin of the inverter power devices, the efficiency optimization module calculates that the current maximum available voltage amplitude boundary is 340 volts.
[0027] In practical implementation, the efficiency optimization module constructs a motor loss model with direct-axis and quadrature-axis current components as variables. This model includes copper loss calculation terms, iron loss calculation terms, and stray loss compensation terms. Copper loss calculation is based on the stator resistance parameters, direct-axis current components, and quadrature-axis current components of the permanent magnet synchronous servo motor. The stator resistance parameter was measured to be 0.5 ohms at 25 degrees Celsius. For a set of input direct-axis current components of 1.0 amps and quadrature-axis current components of 1.5 amps, the formula for calculating the copper loss is as follows:
[0028] in: Represents the total copper loss of the stator winding. Represents the stator phase resistance. Represents the direct-axis current component. The value represents the quadrature axis current component. Substituting this into the numerical calculation, the copper loss is found to be 1.625 watts.
[0029] In some embodiments, the iron loss calculation includes eddy current loss and hysteresis loss of the motor core. The calculation is based on the DC bus voltage, real-time electrical angular velocity, and the material properties of the motor core. The real-time electrical angular velocity is 100 radians per second. The material properties of the motor core include the thickness of the silicon steel sheet, resistivity, and hysteresis loop area. The efficiency optimization module calculates the iron loss value to be 2.1 watts under the current voltage and speed conditions through table lookup and interpolation. Optionally, the stray loss compensation item is obtained by querying a pre-calibrated stray loss mapping table. The stray loss mapping table uses the direct-axis current component, quadrature-axis current component, and real-time electrical angular velocity as input indices and outputs the corresponding estimated stray loss value. For the aforementioned current and speed conditions, the estimated stray loss value obtained from the table lookup is 0.35 watts. The efficiency optimization module sums the copper loss, eddy current loss, hysteresis loss, and stray loss estimates to obtain a total loss value of 4.075 watts under the current operating condition as the output of the motor loss model.
[0030] In some embodiments, the efficiency optimization module performs iterative optimization under the constraints of satisfying the motor operating voltage boundary and output torque requirements. The output torque requirement is given by the upper-level controller, for example, a required torque of 2.0 N·m. The efficiency optimization module uses the motor loss model as the objective function and iteratively adjusts the combination ratio of the direct-axis current component and the quadrature-axis current component within the intersection range of the voltage limit circle and the constant torque curve. It can be understood that the iterative adjustment process uses the gradient descent method or the golden section method to search for the current component combination that minimizes the output value of the motor loss model. For one search step, the efficiency optimization module substitutes the assumed direct-axis current component of -0.3 amps and the quadrature-axis current component of 1.8 amps into the motor loss model to calculate a total loss of 3.92 watts, which is lower than the loss value of the initial combination.
[0031] In practice, the efficiency optimization module continuously iterates until it finds the minimum point, and determines the optimal efficiency point under the current operating conditions by combining the current components corresponding to the minimum point. Optionally, the values of the direct-axis current component and quadrature-axis current component corresponding to the optimal efficiency point are output as the direct-axis current setpoint and quadrature-axis current setpoint, respectively. For example, the final output direct-axis current setpoint is -0.35 amps, and the quadrature-axis current setpoint is 1.82 amps. It can be understood that the efficiency optimization module performs the above calculations online once in each control cycle, thereby achieving real-time dynamic optimization of the permanent magnet synchronous servo motor's operating efficiency.
[0032] In one embodiment of the present invention, the direct-axis current setpoint of -0.35 amps and the quadrature-axis current setpoint of 1.82 amps output by the efficiency optimization module are sent to the current regulation circuit. The current regulation circuit compares the direct-axis current setpoint with the direct-axis current component of 1.0 amps fed back by the coordinate transformation module, and the resulting direct-axis current error value is -1.35 amps. The current regulation circuit compares the quadrature-axis current setpoint with the quadrature-axis current component of 1.5 amps fed back by the coordinate transformation module, and the resulting quadrature-axis current error value is 0.32 amps.
[0033] In some embodiments, the current regulation circuit includes two independent proportional-integral (PI) controllers, which perform proportional-integral (PI) regulation on the direct-axis current error value and the quadrature-axis current error value, respectively. The direct-axis current PI controller calculates the direct-axis voltage compensation value based on the direct-axis current error value, and the quadrature-axis current PI controller calculates the quadrature-axis voltage compensation value based on the quadrature-axis current error value. Optionally, the PI regulation process follows a standard PI algorithm, and its output voltage compensation value includes a component proportional to the error and a component integral over the error. For one control cycle, the direct-axis current PI controller outputs a direct-axis voltage compensation value of -5.2 volts, and the quadrature-axis current PI controller outputs a quadrature-axis voltage compensation value of 1.1 volts.
[0034] In practical implementation, the system simultaneously receives the electrical angular velocity setpoint from the upper-level controller. This setpoint is used to set the target rotational speed of the rotor; for example, the setpoint might be 120 radians per second. The real-time electrical angular velocity provided by the speed angle module is 100 radians per second. The speed adjustment stage compares the setpoint with the real-time electrical angular velocity, obtaining an error value of 20 radians per second. The speed adjustment stage then performs proportional-integral adjustment on the error value to generate an additional setpoint for the quadrature-axis current. In one calculation example, the initially generated additional setpoint for the quadrature-axis current is 0.15 amperes.
[0035] It can be understood that the additional quadrature-axis current setpoint is used to dynamically correct the quadrature-axis current setpoint output by the efficiency optimization module. The speed regulation stage adds the additional quadrature-axis current setpoint of 0.15 amps to the quadrature-axis current setpoint of 1.82 amps obtained from efficiency optimization, forming the final comprehensive quadrature-axis current setpoint of 1.97 amps. In some embodiments, the speed regulation stage uses a variable gain proportional-integral (VRI) controller to process the electrical angular velocity error value. The proportional coefficient and integral time constant of the VRI controller are adaptively adjusted according to the magnitude of the real-time electrical angular velocity. When the real-time electrical angular velocity is lower than a set threshold, for example, a set threshold of 50 radians per second and a real-time electrical angular velocity of 30 radians per second, the VRI controller uses a proportional coefficient greater than the preset average and an integral time constant greater than the preset average of the integral time constant. The proportional coefficient is set to 0.8, and the integral time constant is set to 0.05 seconds.
[0036] In practical implementation, when the real-time electrical angular velocity exceeds a set threshold, for example, 150 radians per second, the variable gain proportional-integral (VII) controller uses a proportional coefficient and an integral time constant that are both less than the preset average values. The proportional coefficient is adjusted to 0.3, and the integral time constant is adjusted to 0.02 seconds. Optionally, the parameter adjustment rules of the VII controller can be expressed by the following functional relationship:
[0037] in: Represents the real-time electric angular velocity The proportionality coefficient of change Represents the baseline value of the proportional coefficient. Representative on The proportional coefficient adjustment function, Represents the real-time electric angular velocity The changing integral time constant, Represents the baseline value of the integration time constant. Representative on The integral time constant adjustment function. It can be understood that the function... and When the real-time electric angular velocity is lower than the set threshold, a coefficient greater than 1 is output; when the real-time electric angular velocity is higher than the set threshold, a coefficient less than 1 is output.
[0038] See Figure 3 This is a line graph showing the adaptive adjustment of parameters of a variable-gain PI controller, clearly illustrating the dynamic changes of the speed loop PI parameters of a permanent magnet synchronous servo motor with real-time electrical angular velocity. This variable-gain design resolves the contradiction between "low-speed stability" and "high-speed responsiveness" inherent in traditional fixed-PI parameters, and is a key element in the efficient and energy-saving control of permanent magnet synchronous servo motors. Precise control of the speed loop provides stable operating conditions for the efficiency optimization module, ensuring that the motor operates at its optimal efficiency point at different speeds. This segmented parameter adjustment strategy has been widely applied in industrial servo drive systems, effectively improving the motor's control performance and energy-saving effect across the entire speed range.
[0039] In one embodiment of the present invention, the direct-axis voltage compensation value and quadrature-axis voltage compensation value output by the current regulation circuit, for example, a direct-axis voltage compensation value of -5.2 volts and a quadrature-axis voltage compensation value of 1.1 volts, are sent to the space vector pulse width modulation module. The space vector pulse width modulation module first performs an inverse Parker transformation on the direct-axis voltage compensation value and the quadrature-axis voltage compensation value. The inverse Parker transformation requires real-time electrical angles provided by the rotational angle module, for example, a real-time electrical angle of 0.785 radians. The inverse Parker transformation transforms the direct-axis voltage compensation value and the quadrature-axis voltage compensation value in the rotating two-phase coordinate system back to the stationary two-phase coordinate system, outputting the alpha-axis voltage component and the beta-axis voltage component in the stationary two-phase coordinate system. After calculation, the alpha-axis voltage component is approximately -3.5 volts, and the beta-axis voltage component is approximately -4.3 volts.
[0040] In some embodiments, the space vector pulse width modulation module then performs space vector pulse width modulation processing on the alpha-axis voltage component and the beta-axis voltage component. The space vector pulse width modulation processing first calculates the amplitude and phase angle of the reference voltage vector based on the alpha-axis voltage component and the beta-axis voltage component. From the formula:
[0041] in: Represents the alpha axis voltage component. Representing the beta-axis voltage component, substituting it into the numerical calculation yields a reference voltage vector amplitude of approximately 5.5 volts. The phase angle of the reference voltage vector... From the formula Calculations show that, by substituting the values, the phase angle of the reference voltage vector is approximately -2.3 radians.
[0042] In practical implementation, the space vector pulse width modulation (SVM) process determines the sector of the reference voltage vector based on its phase angle. The space vector plane is divided into six sectors, each spanning 60 electrical degrees. By determining the magnitude relationship between the alpha-axis voltage component, the beta-axis voltage component, and their combination with zero, the sector number of the reference voltage vector can be uniquely determined. For a given sector, the SVM process selects two adjacent fundamental non-zero voltage vectors and the zero vector corresponding to that sector to synthesize the reference voltage vector. The correspondence between fundamental non-zero voltage vectors and sectors is shown in Table 1. Table 1: Correspondence between sectors and the basic non-zero voltage vector required for synthesis
[0043] Optionally, based on the volt-second balance principle, space vector pulse width modulation (SVM) processing is used to calculate the duration of the two fundamental non-zero voltage vectors and the zero vector. The volt-second balance principle requires that within one pulse width modulation cycle... Within this context, the product of the reference voltage vector and the pulse width modulation period is equal to the vector sum of the products of the two fundamental non-zero voltage vectors and their respective durations. For the case where the reference voltage vector is located in sector III, the calculation involves... The duration of the vector and The duration of the vector and the duration of action of the zero vector ,satisfy This is understandable; the duration of action... and The specific values are obtained by solving linear equations based on the alpha-axis voltage component and the beta-axis voltage component.
[0044] In some embodiments, based on the calculated duration of action , and The space vector pulse width modulation (SVM) process generates a duty cycle sequence of six corresponding pulse width modulation (PWM) signals. The duty cycle sequence defines the timing sequence of turning on and off the six power switches of the three-phase inverter bridge within one PWM cycle. For seven-segment SVM, the zero vector is symmetrically distributed at the beginning, middle, and end of the PWM cycle, and the action times of the two fundamental non-zero voltage vectors are inserted in a predetermined order. Optionally, the final generated six-channel PWM signal duty cycle sequence is sent to the gate drive circuit of the inverter bridge to control the actual voltage on the stator windings of the permanent magnet synchronous servo motor, achieving precise closed-loop control of the motor torque and speed.
[0045] See Figure 4This is a dynamic temperature monitoring curve of a permanent magnet synchronous servo motor, reflecting the real-time temperature changes of the stator windings and radiator, as well as the two-level temperature protection thresholds set by the system. When the stator winding temperature reaches the 60℃ warning threshold, the system will activate the efficiency optimization module for dynamic adjustment, prioritizing the selection of direct-axis / quadrature-axis current combinations that reduce winding temperature rise while ensuring output torque. When the temperature reaches the 70℃ protection threshold, the system will forcibly limit the output power and may even trigger a shutdown protection to prevent damage to the winding insulation. The curve shows that throughout the monitoring period, the radiator temperature consistently lags behind the winding temperature, indicating that the heat dissipation design meets the thermal balance requirements under the current load. This temperature data will serve as a key input to correct the current safety limit in the efficiency optimization calculation in real time, ensuring that the motor operates efficiently without exceeding the temperature safety boundary.
[0046] In one embodiment of the present invention, the system integrates a temperature monitoring module. This module monitors the stator winding temperature and heat sink temperature of the permanent magnet synchronous servo motor in real time. The stator winding temperature is measured by a thermocouple sensor embedded in the motor stator slot, and the heat sink temperature is measured by a thermistor mounted on the heat sink substrate of the inverter power module. In one operating example, the temperature monitoring module collects a current stator winding temperature of 85 degrees Celsius and a heat sink temperature of 60 degrees Celsius.
[0047] In some embodiments, the temperature monitoring module sends the stator winding temperature and radiator temperature values and historical data to the efficiency optimization module. The efficiency optimization module dynamically adjusts the current safety limit in the online efficiency optimization calculation based on the rate of change of the stator winding temperature and the difference between the radiator temperature and the current limit. The rate of change of the stator winding temperature is obtained by calculating the ratio of the difference in stator winding temperature over a recent period to the time interval. For example, if the stator winding temperature rises from 82 degrees Celsius to 85 degrees Celsius in the past 10 seconds, the calculated rate of change is 18 degrees Celsius per minute.
[0048] Optionally, the efficiency optimization module includes a pre-defined current safety limit adjustment function. This function uses the difference between the stator winding temperature change rate and the radiator temperature as input variables to dynamically calculate and output a scaling factor for the current safety limit. Current safety limit scaling factor. The calculation can be expressed by the following relation:
[0049] in: This represents the scaling factor for the current safety limit. This represents a pre-defined two-dimensional function mapping relationship. Represents stator winding temperature With radiator temperature The difference, This represents the rate of change of the stator winding temperature. Based on the current data, the temperature difference between the stator winding and the radiator is 25 degrees Celsius, and the rate of change of the stator winding temperature is 18 degrees Celsius per minute. By querying the preset two-dimensional function mapping table, the efficiency optimization module obtains a current safety limit scaling factor of 0.92.
[0050] In practical implementation, the efficiency optimization module applies the calculated current safety limit scaling factor to the online efficiency optimization calculation process. The original direct-axis and quadrature-axis current absolute limits, such as ±50 amps, are updated to ±46 amps after being multiplied by a scaling factor of 0.92. In subsequent iterative optimization calculations, the efficiency optimization module strictly limits the search range of the current component within the updated current safety limit. It can be understood that when the difference between the stator winding temperature and the radiator temperature increases, or when the stator winding temperature change rate is positive and large, the function... The scaling factor of the output will decrease, thus more strictly limiting the current amplitude to suppress temperature rise; when the temperature difference decreases or the rate of temperature change slows down, the scaling factor will increase, allowing the motor to operate at higher currents to achieve its performance.
[0051] In some embodiments, the temperature monitoring module also sets a warning threshold for the stator winding temperature, for example, a warning threshold of 130 degrees Celsius. When the temperature monitoring module detects that the stator winding temperature exceeds the warning threshold, the efficiency optimization module will receive a temperature over-limit signal. In a specific implementation, once a temperature over-limit signal is received, the efficiency optimization module will initiate a protective optimization mode. Under the premise of ensuring that the output torque meets the requirements given by the upper-level controller, it will prioritize using the combination of current components that can reduce the winding temperature rise to update the direct-axis current setpoint and quadrature-axis current setpoint. Optionally, in the protective optimization mode, the objective function in the efficiency optimization model will add a penalty term positively correlated with the stator winding temperature rise. This penalty term makes the algorithm tend to select the current vector that produces less copper loss, i.e., a larger negative direct-axis current component, to utilize reluctance torque when searching for the minimum loss point, thereby reducing the quadrature-axis current component to reduce winding heating under the same torque output. It can be understood that this mechanism ensures the continuous safe operation of the motor under the risk of overheating, while maintaining the necessary torque output capability as much as possible.
[0052] See Figure 5This is a temperature and current safety constraint linkage monitoring curve of a permanent magnet synchronous servo motor, visually demonstrating the dynamic relationship between stator winding temperature, radiator temperature, and current limit scaling factor. The stator winding temperature continues to rise, while the radiator temperature remains relatively stable, with the temperature difference widening from an initial 22°C to a final 40°C. This indicates that the cooling system is nearing thermal saturation and cannot effectively dissipate the increased heat from the windings. This continuously widening temperature difference is a typical sign that the motor has entered a high-load, high-risk operating phase. When the stator winding temperature approaches 100°C, maintaining a current limit of 0.70 may exceed the heat resistance limit of the insulation material, posing a risk of burnout. The ideal strategy would be to dynamically reduce the current limit scaling factor based on the rate of change of the stator winding temperature and the difference in radiator temperature, prioritizing current combinations that reduce winding temperature rise while ensuring torque output.
[0053] The above embodiments are only used to illustrate the technical methods of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical methods of the present invention without departing from the spirit and scope of the technical methods of the present invention.
Claims
1. A high-efficiency, energy-saving, high-power permanent magnet synchronous servo motor closed-loop control system, characterized in that, The method includes: The data acquisition module is used to collect the three-phase current value, rotor position angle and DC bus voltage value of the permanent magnet synchronous servo motor in real time. The coordinate transformation module is used to perform Clarke transformation and Park transformation on the three-phase current values to generate direct-axis current components and quadrature-axis current components. The rotational speed and angle module is used to calculate the real-time electrical angular velocity and electrical angle of the rotor based on the rotor position angle. The efficiency optimization module is used to perform online efficiency optimization calculations based on the DC bus voltage value, the direct-axis current component, and the quadrature-axis current component, and to generate direct-axis current setpoints and quadrature-axis current setpoints.
2. The high-efficiency, energy-saving, high-power permanent magnet synchronous servo motor closed-loop control system according to claim 1, characterized in that, The step of performing Clarke transform and Park transform on the three-phase current values to generate direct-axis current components and quadrature-axis current components includes: The three-phase current values are transformed into alpha-axis current components and beta-axis current components in a stationary two-phase coordinate system. Based on the real-time electrical angle, the alpha axis current component and the beta axis current component are transformed into a rotating two-phase coordinate system, and the direct axis current component representing the excitation current and the quadrature axis current component representing the torque current are output.
3. The high-efficiency, energy-saving, high-power permanent magnet synchronous servo motor closed-loop control system according to claim 2, characterized in that, The process of performing online efficiency optimization calculations based on the DC bus voltage value, the direct-axis current component, and the quadrature-axis current component to generate direct-axis current setpoints and quadrature-axis current setpoints includes: Estimate the motor operating voltage boundary under the current power supply conditions based on the DC bus voltage value; A motor loss model is constructed with the direct-axis current component and the quadrature-axis current component as variables. The motor loss model includes copper loss calculation items, iron loss calculation items, and stray loss compensation items. Under the constraints of satisfying the motor operating voltage boundary and output torque requirements, the combination ratio of the direct-axis current component and the quadrature-axis current component is iteratively adjusted to solve for the minimum point of the motor loss model. The combination of current components corresponding to the minimum point is determined as the optimal efficiency point under the current operating conditions, and the current value corresponding to the optimal efficiency point is output as the direct-axis current setpoint and the quadrature-axis current setpoint.
4. The high-efficiency, energy-saving, high-power permanent magnet synchronous servo motor closed-loop control system according to claim 3, characterized in that, The construction of the motor loss model using the direct-axis current component and the quadrature-axis current component as variables includes: Based on the stator resistance parameters of the permanent magnet synchronous servo motor, the direct-axis current component and the quadrature-axis current component, the copper loss of the stator winding is calculated; Based on the DC bus voltage value, the real-time electric angular velocity, and the material characteristics of the motor core, calculate the eddy current loss and hysteresis loss of the motor core. By querying a pre-calibrated stray loss mapping table, the estimated stray loss values corresponding to the current direct-axis current component, the quadrature-axis current component, and the real-time electric angular velocity are obtained. The estimated values of copper loss, eddy current loss, hysteresis loss, and stray loss are summed to obtain the total loss value, which is then used as the output of the motor loss model.
5. The high-efficiency, energy-saving, high-power permanent magnet synchronous servo motor closed-loop control system according to claim 1, characterized in that, The method further includes: The direct-axis current setpoint is compared with the direct-axis current component to obtain the direct-axis current error value; The cross-axis current setpoint is compared with the cross-axis current component to obtain the cross-axis current error value; The direct-axis current error value and the quadrature-axis current error value are respectively subjected to proportional-integral adjustment processing to generate direct-axis voltage compensation value and quadrature-axis voltage compensation value.
6. The high-efficiency, energy-saving, high-power permanent magnet synchronous servo motor closed-loop control system according to claim 5, characterized in that, The method further includes: Obtain the electrical angular velocity setpoint issued by the upper-level controller; The electric angular velocity setpoint is compared with the real-time electric angular velocity to obtain the electric angular velocity error value; The electrical angular velocity error value is subjected to proportional-integral adjustment processing to generate an additional setpoint value for the quadrature-axis current; The additional given value of the quadrature-axis current is superimposed on the given value of the quadrature-axis current obtained by efficiency optimization to form the final comprehensive given value of the quadrature-axis current.
7. The high-efficiency, energy-saving, high-power permanent magnet synchronous servo motor closed-loop control system according to claim 6, characterized in that, The step of performing proportional-integral adjustment on the electrical angular velocity error value to generate an additional setpoint value for the quadrature-axis current includes: The electric angular velocity error value is processed by a variable gain proportional-integral (PII) controller, and the proportional coefficient and integral time constant of the PII controller are adaptively adjusted according to the magnitude of the real-time electric angular velocity. When the real-time electric angular velocity is lower than a set threshold, a proportional coefficient greater than the preset average value and an integral time constant greater than the preset average value of the integral time constant are used to enhance low-speed stability. When the real-time electric angular velocity is higher than the set threshold, a proportional coefficient less than the preset average value and an integral time constant less than the preset average value of the integral time constant are used to improve the dynamic response speed.
8. The high-efficiency, energy-saving, high-power permanent magnet synchronous servo motor closed-loop control system according to claim 5, characterized in that, The method further includes: The direct-axis voltage compensation value and the quadrature-axis voltage compensation value are subjected to Parker inverse transformation to obtain the alpha-axis voltage component and beta-axis voltage component in the stationary two-phase coordinate system. The alpha axis voltage component and the beta axis voltage component are subjected to space vector pulse width modulation processing to generate six pulse width modulation signals for driving the inverter bridge.
9. The high-efficiency, energy-saving, high-power permanent magnet synchronous servo motor closed-loop control system according to claim 8, characterized in that, The process of performing space vector pulse width modulation (SVM) on the alpha axis voltage component and the beta axis voltage component to generate six pulse width modulation signals for driving the inverter bridge includes: The magnitude and phase angle of the reference voltage vector are calculated based on the alpha-axis voltage component and the beta-axis voltage component. Based on the phase angle of the reference voltage vector, determine the sector in which it is located and the two basic non-zero voltage vectors and the zero vector corresponding to the sector; Based on the volt-second balance principle, the duration of action of the two fundamental non-zero voltage vectors and the zero vector is calculated. The duty cycle sequence of the six pulse width modulation signals is generated according to the said action time.
10. The high-efficiency, energy-saving, high-power permanent magnet synchronous servo motor closed-loop control system according to claim 1, characterized in that, The method further includes: Real-time monitoring of the stator winding temperature and radiator temperature of the permanent magnet synchronous servo motor; The current safety limit in the online efficiency optimization calculation is dynamically adjusted based on the difference between the rate of change of the stator winding temperature and the radiator temperature. When the stator winding temperature exceeds the warning threshold, under the premise of ensuring the output torque, the combination of current components that can reduce the winding temperature rise is preferentially used to update the direct-axis current setpoint and the quadrature-axis current setpoint.