Bus voltage regulation method, control processing unit and motor drive system

Abstract

The application discloses a bus voltage regulation method, a control processing unit and a motor driving system. The bus voltage regulation method is applied to regulating the bus voltage of the motor driving system. The bus voltage regulation method comprises the following steps: acquiring an excitation current component, a torque current component and a rotating speed; determining a modulation coefficient according to the excitation current component and the torque current component, and performing feedback regulation based on the difference between a preset target coefficient and the modulation coefficient to obtain a first voltage regulation amount; determining the power variation of the motor, determining the rotating speed variation rate, and determining a preset compensation amount according to the working state of a PI controller; determining a second voltage regulation amount according to the first voltage regulation amount, the power variation, the rotating speed variation rate and the preset compensation amount; and regulating the bus voltage according to the second voltage regulation amount. Through the above method, the modulation coefficient can be dynamically kept in an optimal interval, so as to solve the problems of efficiency reduction and current waveform distortion caused by the excessively large or small modulation coefficient.

Description

Technical Field

[0001] This application relates to the field of bus voltage regulation technology, and in particular to a bus voltage regulation method, a control processing unit, and a motor drive system. Background Technology

[0002] In motor drive systems such as air conditioning compressors, power tools, and industrial fans, the front end uses a power factor correction (PFC) circuit to boost the AC input to a stable DC bus voltage of 380V to 400V; the rear stage uses a three-phase inverter combined with a field-oriented control (FOC) algorithm to drive a permanent magnet synchronous motor (PMSM) or induction motor.

[0003] For the aforementioned motor drive system, existing technologies mostly adopt a PFC control strategy with a fixed bus voltage. That is, regardless of whether the motor is under light load, low speed, heavy load or high speed, the DC bus voltage is kept constant at a preset value (typically 380V).

[0004] However, this constant voltage control method leads to lower system efficiency. On the one hand, under light load and low speed conditions, the modulation coefficient is only 0.2 to 0.4. The constant high bus voltage will significantly increase the inverter switching losses, causing the overall system efficiency to decrease by 5% to 15%. On the other hand, under heavy load and high speed conditions, the modulation coefficient can exceed 0.95 or even approach 1.0, causing the inverter to enter the overmodulation region. The current loop is prone to runaway. To avoid overmodulation, the system needs to engage field weakening control in advance, but this will introduce additional copper and iron losses, further reducing the system operating efficiency. Summary of the Invention

[0005] This application provides a bus voltage regulation method, a control processing unit, and a motor drive system, which can dynamically maintain the modulation coefficient within an optimal range to solve problems such as efficiency reduction and current waveform distortion caused by an excessively large or small modulation coefficient.

[0006] In a first aspect, embodiments of this application provide a bus voltage regulation method applied to regulate the bus voltage of a motor drive system. The motor in the motor drive system is driven by a field-oriented control algorithm. The bus voltage regulation method includes: acquiring the excitation current component, torque current component, and speed of the motor in the motor control system; determining a modulation coefficient based on the excitation current component and torque current component, and performing feedback regulation based on the difference between a preset target coefficient and the modulation coefficient to obtain a first voltage regulation amount; determining the power change of the motor based on the excitation current component and torque current component, determining the speed change rate based on the speed, and determining a preset compensation amount based on the operating state of the PI controller of the current loop in the field-oriented control algorithm, wherein the operating state is a saturated state or a non-saturated state; determining a second voltage regulation amount based on the first voltage regulation amount, the power change amount, the speed change rate, and the preset compensation amount; and regulating the bus voltage based on the second voltage regulation amount.

[0007] In one or more embodiments, performing feedback adjustment based on the difference between a preset target coefficient and a modulation coefficient to obtain a first voltage adjustment amount includes: performing incremental PI adjustment based on the difference between the preset target coefficient and the modulation coefficient to obtain the first voltage adjustment amount.

[0008] In one or more embodiments, determining the power change of the motor based on the excitation current component and the torque current component includes: the power of the motor is: P motor =3 / 2×(V d ×I d +V q ×I q ), where P motor I represents the power of the motor. d I is the excitation current component. q V is the torque current component. d and V q The reference voltage vectors are obtained based on the excitation current component and the torque current component, respectively; the power change is determined based on the difference between the power of the motor in the current control cycle and the power in the previous control cycle.

[0009] In one or more embodiments, determining a second voltage regulation amount based on a first voltage regulation amount, a power change amount, a speed change rate, and a preset compensation amount includes: the second voltage regulation amount is: V bus_pre =V bus_PI +K FFp ×ΔP motor +K FFp ×(dω / dt)+V FF_sat , where V bus_pre V is the second voltage regulation value. bus_PI K is the first voltage regulation value. FFp ΔP is a preset coefficient.motor The power change is set to 0 when it is less than the power change threshold. dω / dt is the speed change rate; it is set to 0 when it is less than the speed change threshold. FF_sat The preset compensation amount is V when the working state is saturated. FF_sat It is a fixed value greater than 0.

[0010] In one or more embodiments, adjusting the bus voltage according to a second voltage adjustment amount includes: setting the second voltage adjustment amount as a target adjustment amount when the second voltage adjustment amount is greater than or equal to a first voltage threshold and less than or equal to a second voltage threshold; setting the first voltage threshold as the target adjustment amount when the second voltage adjustment amount is less than the first voltage threshold; setting the second voltage threshold as the target adjustment amount when the second voltage adjustment amount is greater than the second voltage threshold; and adjusting the bus voltage according to the target adjustment amount.

[0011] In one or more embodiments, before performing the step of adjusting the bus voltage according to the target adjustment amount, the method further includes: performing the step of adjusting the bus voltage according to the target adjustment amount when the bus voltage is less than a second voltage threshold and / or the modulation coefficient is less than or equal to a first coefficient threshold.

[0012] In one or more embodiments, before performing the step of adjusting the bus voltage according to the target adjustment amount, the method further includes: when the bus voltage is greater than or equal to a second voltage threshold and the modulation coefficient is greater than a first coefficient threshold, controlling the current loop to increase a negative magnetic weakening current.

[0013] In one or more embodiments, the magnetic weakening current is: ,in, For weak magnetic current, K fw V is the magnetic weakening proportional adjustment coefficient. ref The magnitude of the synthesized voltage vector along the dq axis. V bus_max MI is the second voltage threshold. max This is the first coefficient threshold.

[0014] Secondly, embodiments of this application provide a control processing unit, including: at least one processor and a memory; the memory is coupled to the processor and is used to store instructions or programs, which, when executed by at least one processor, cause at least one processor to perform the bus voltage regulation method of the first aspect.

[0015] Thirdly, embodiments of this application provide a motor drive system, including a power factor correction circuit, a three-phase inverter, a motor, and a control processing unit as described in the second aspect; the power factor correction circuit inputs AC power and outputs bus voltage; the three-phase inverter is electrically connected to the power factor correction circuit, the motor, and the control processing unit respectively, and the three-phase inverter inputs the bus voltage and drives the motor under the control of the control processing unit.

[0016] The beneficial effects of this application are as follows: The bus voltage regulation method in this application relies on an incremental PI controller to construct a feedback closed loop. Using the real-time modulation coefficient as the control target, it calculates the modulation coefficient deviation in real time based on the motor excitation current and torque current, and continuously corrects the bus voltage. Feedback regulation stabilizes the system modulation coefficient within a relatively optimal operating range. Furthermore, to compensate for the shortcomings of a single PI feedback system, which can only provide delayed correction and lacks dynamic response, this solution further introduces a feedforward compensation strategy. By real-time detection of motor power changes, speed change rate, and the operating state of the current loop PI controller, it predicts the dynamic abrupt changes in motor load and speed and outputs a compensation adjustment amount, correcting the bus voltage in advance. Thus, a composite voltage regulation architecture combining feedback closed loop and feedforward prediction is realized to regulate the bus voltage. This helps maintain the modulation coefficient within a relatively optimal range, enabling the inverter to always operate at high voltage utilization and lowest switching losses, effectively solving the problems of bus voltage redundancy and system efficiency degradation under low modulation coefficient conditions. It also allows for early correction of the bus voltage, effectively suppressing problems such as current loop instability and current waveform distortion caused by excessively high modulation coefficients under high-speed, heavy-load conditions. Attached Figure Description

[0017] One or more embodiments are illustrated by way of example with reference to the accompanying drawings, which are not intended to limit the embodiments, and elements having the same reference numerals in the drawings are designated as similar elements.

[0018] Figure 1 This is a flowchart of the bus voltage regulation method provided in the embodiments of this application. Figure 1 ; Figure 2 This is a schematic diagram of the motor drive system provided in the embodiments of this application; Figure 3 This is a schematic diagram of the control processing unit provided in an embodiment of this application; Figure 4 This is a flowchart of the bus voltage regulation method provided in the embodiments of this application. Figure 2 ; Figure 5 This is a schematic diagram of the voltage control block diagram provided in the embodiments of this application. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be described clearly and in detail below with reference to the accompanying drawings. Obviously, the embodiments in this application are only some embodiments, not all embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0020] It should be noted that when an element is described as "connected" to another element, it can be directly connected to the other element, or there can be one or more intermediate elements between them.

[0021] Furthermore, the technical features involved in the various embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0022] In related technologies, a PFC control strategy with a fixed bus voltage is typically used to control the motor drive system. However, this control method has the following drawbacks: (1) Poor operating efficiency under light load and low speed conditions: When the motor is running under light load and low speed, the modulation coefficient is only 0.2~0.4. Since the bus voltage remains constant at a high value and the switching loss of the power device is proportional to the square of the bus voltage, the switching loss of the inverter will increase significantly, and the overall system efficiency will decrease by 5%~15%.

[0023] (2) Overmodulation and additional losses induced by heavy-load and high-speed operation: Under the heavy-load operation of high-speed and high-torque motor, the modulation coefficient can reach 0.95 or even approach 1.0. The inverter enters the overmodulation range, the output current waveform is distorted, the stability of the current loop control decreases, and the torque pulsation intensifies. In order to avoid the overmodulation runaway problem, the control system puts the field weakening control in advance, which generates additional stator copper loss and core iron loss, further reducing the operating efficiency.

[0024] (3) Lack of dynamic load adaptation capability: The bus voltage cannot be adjusted in real time. Therefore, when the load changes suddenly, the bus is prone to voltage drop or voltage overshoot, which will disrupt the steady-state operation conditions of the current loop and reduce the stability of system control.

[0025] Based on this, this application provides a bus voltage regulation method, which adopts a composite voltage regulation architecture of PI feedback closed loop combined with feedforward prediction to regulate the bus voltage, so as to solve the above problems.

[0026] Figure 1This is a flowchart of the bus voltage regulation method provided in this application. The method is applied to regulate the bus voltage of a motor drive system, where the motor is driven using a field-oriented control (FOC) algorithm. Field-oriented control, also known as vector control, is a mainstream high-performance decoupling drive algorithm for permanent magnet synchronous motors and asynchronous motors. Its core idea is to map the coupled stator currents in the three-phase stationary coordinate system of the motor to the synchronously rotating dq rotor magnetic field coordinate system through coordinate transformation, thus decomposing the stator currents into independent excitation current components i. d Torque current component i q This enables independent adjustment of the magnetic field and torque through decoupling.

[0027] Figure 2 An exemplary block diagram of a motor drive system is shown. Figure 2 As shown, the motor drive system 200 includes a power factor correction circuit 210, a three-phase inverter 220, a control processing unit 230, and a motor 240.

[0028] The power factor correction circuit 210 takes AC power 200 as input and outputs bus voltage V. bus The power factor correction circuit 210 is the front-stage AC-DC converter unit of this motor drive system. Its input terminal is electrically connected to the external AC power supply 200. Its core function is to rectify, correct the power factor, and regulate the DC voltage of the input AC power, and output a stable and controllable DC bus voltage V to the subsequent three-phase inverter 220. bus .

[0029] The three-phase inverter 220 is electrically connected to the power factor correction circuit 210, the motor 240, and the control processing unit 230, respectively. The input bus voltage V of the three-phase inverter 220 is... bus And under the control of the control processing unit 230, it drives the motor 240. That is, the three-phase inverter 220 is the downstream DC-AC power conversion unit of the system, which uses the DC bus voltage V output by the power factor correction circuit 210. bus As input, it receives the drive logic signal sent by the control processing unit 230, completes the conversion of DC power to three-phase alternating power, and drives the motor 240 to operate.

[0030] The control processing unit 230 is used to collect operating status quantities such as motor current, rotor position, and bus voltage in real time, complete FOC vector decoupling calculation to generate d / q axis voltage reference commands, and output PWM drive signals to the three-phase inverter 220 to uniformly manage the entire process control logic of PFC bus voltage regulation, inverter modulation, motor field weakening, and current closed loop.

[0031] The control processing unit 230 can be a microcontroller unit (MCU) or a digital signal processing (DSP) controller, etc.

[0032] like Figure 3 As shown, the control processing unit 230 includes at least one processor 231 and a memory 232. The memory 232 can be built into the control processing unit 230 or external to the control processing unit 230. The memory 232 can also be a remotely configured memory connected to the control processing unit 230 via a network.

[0033] Memory 232, as a non-volatile computer-readable storage medium, can be used to store non-volatile software programs, non-volatile computer-executable programs, and modules. Memory 232 may include a program storage area and a data storage area, wherein the program storage area may store the operating system and application programs required for at least one function; the data storage area may store data created based on the use of the terminal, etc. Furthermore, memory 232 may include high-speed random access memory and may also include non-volatile memory, such as at least one disk storage device, flash memory device, or other non-volatile solid-state storage device. In some embodiments, memory 232 may optionally include memory remotely located relative to processor 231, and these remote memories can be connected to the terminal via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0034] The processor 231 performs various functions of the terminal and processes data by running or executing software programs and / or modules stored in the memory 232 and calling data stored in the memory 232, thereby performing overall monitoring of the terminal, such as implementing the bus voltage regulation method described in any embodiment of this application.

[0035] There can be one or more processors 231. Figure 3 The example provided is a processor 231. The processor 231 and memory 232 can be connected via a bus or other means. The processor 231 may include a central processing unit (CPU), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a controller, a field-programmable gate array (FPGA) device, etc. The processor 231 can also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration.

[0036] Return to reference Figure 1 ,like Figure 1As shown, the bus voltage regulation method includes the following steps S110 to S150.

[0037] Step S110: Obtain the excitation current component, torque current component, and speed of the motor in the motor control system.

[0038] This step is the pre-sampling and coordinate decoupling calculation stage of the motor control system driven by the field-oriented control algorithm. Through hardware signal acquisition, coordinate transformation, and angle calculation, the mutually decoupled d-axis excitation current components i in the synchronous rotating dq coordinate system are obtained in real time. d q-axis torque current component i q The real-time motor speed ω provides the basic feedback variables for subsequent current closed-loop regulation, modulation coefficient calculation, field weakening control, and adaptive bus voltage regulation.

[0039] Step S120: Determine the modulation coefficient based on the excitation current component and the torque current component, and perform feedback adjustment based on the difference between the preset target coefficient and the modulation coefficient to obtain the first voltage adjustment amount.

[0040] The modulation coefficient is a dimensionless parameter that characterizes the degree of utilization of the inverter's output synthesized stator voltage amplitude relative to the bus voltage. It is calculated by combining the direct-axis and quadrature-axis voltage commands corresponding to the excitation current component and torque current component in the dq coordinate system with the bus voltage.

[0041] The preset target coefficient is a pre-set target value for the modulation coefficient, which can be set based on the actual application scenario. For example, in a specific embodiment, the preset target coefficient is configured as any value in [0.85, 0.95], such as 0.9, thereby triggering bus voltage regulation when the actual modulation coefficient deviates from the preset target coefficient. Specifically, if the actual modulation coefficient is greater than the preset target coefficient, it means that the voltage utilization rate is too high and is close to over-modulation, requiring an increase in the bus voltage V. bus If the actual modulation coefficient is less than the preset target coefficient, it means that the voltage utilization rate is too low and the switching losses are wasted, and the bus voltage V needs to be reduced. bus .

[0042] Specifically, a preset target coefficient is used as the given value for closed-loop control, and the real-time modulation coefficient calculated from the excitation current component and torque current component is used as the closed-loop feedback acquisition quantity. The difference between the two is calculated to form the closed-loop adjustment deviation. This deviation is used to perform closed-loop feedback calculation and output the control quantity. The final output result is the first voltage regulation quantity. This regulation belongs to closed-loop feedback control, which automatically completes the correction based on the deviation between the actual operating condition and the desired operating condition, and is used to continuously constrain the modulation coefficient to stably approach the preset target coefficient.

[0043] In some embodiments, the specific implementation process of determining the modulation coefficient based on the excitation current component and the torque current component in step S120 includes the following steps: The modulation coefficient is: Where MI is the modulation coefficient, and V d and V q V is the reference voltage vector obtained based on the excitation current component and the torque current component, respectively. bus This is the bus voltage.

[0044] Specifically, The magnitude of the synthesized phase voltage along the dq axis, multiplied by Converting to line voltage amplitude and dividing by the bus voltage yields the dimensionless modulation coefficient MI.

[0045] In some embodiments, the specific implementation process of performing feedback adjustment based on the difference between the preset target coefficient and the modulation coefficient in step S120 to obtain the first voltage adjustment amount includes the following steps: performing incremental PI adjustment based on the difference between the preset target coefficient and the modulation coefficient to obtain the first voltage adjustment amount.

[0046] The incremental PI controller is a discrete-domain incremental proportional-integral controller. It does not directly output the complete control quantity, but only calculates the single-cycle control increment. The current control quantity is obtained by superimposing the output of the previous cycle. The calculation result output by the incremental PI after adjustment is the first voltage regulation quantity, which is used to correct the bus voltage and ultimately constrain the real-time modulation coefficient to stably approach the preset target coefficient.

[0047] Specifically, the first voltage regulation amount is: V bus_PI (k)=V bus_PI (k-1)+K P ×[e(k)-e(k-1)]+K I ×e(k)×T S Where, e(k) = M Iref -MI(k), M Iref Let MI(k) be the preset target coefficient, and V be the modulation coefficient for the k-th power factor correction control cycle. bus_PI (k) represents the first voltage regulation value in the k-th control cycle, V bus_PI (k-1) represents the first voltage regulation value in the (k-1)th control cycle, K P K is the proportionality factor. I T is the integral factor. S The power factor correction control cycle is k, where k is a positive integer.

[0048] Where e(k)-e(k-1) is the change in deviation between adjacent periods, K P×[e(k)-e(k-1)] is the proportional increment term, used to dynamically suppress rapid fluctuations in the modulation coefficient based on the change in deviation, thereby improving the dynamic response. K I ×e(k)×T S The integral increment term is used to continuously eliminate the steady-state error of the modulation coefficient, ensuring that the actual modulation coefficient accurately follows the preset target coefficient under steady state. The proportional increment term and the integral increment term are superimposed on the stored previous cycle adjustment output to iteratively generate a new control output.

[0049] In this way, a closed-loop control process is achieved, which uses the difference between the preset target coefficient and the modulation coefficient as input and employs an incremental PI algorithm for iterative calculation. This process is called incremental PI regulation based on the difference between the preset target coefficient and the modulation coefficient. This facilitates real-time correction of the bus voltage output, suppresses modulation coefficient (MI) fluctuations, and ensures that the modulation coefficient (MI) operates stably within the preset optimal modulation range, balancing voltage utilization, modulation waveform quality, and system efficiency.

[0050] Step S130: Determine the power change of the motor based on the excitation current component and the torque current component, determine the speed change rate based on the speed, and determine the preset compensation amount based on the working state of the PI controller of the current loop in the field-oriented control algorithm, wherein the working state is either saturated or unsaturated.

[0051] Specifically, the process of determining the motor power change based on the excitation current component and the torque current component in step S130 is as follows: The motor power is: P motor =3 / 2×(V d ×I d +V q ×I q ), where P motor I represents the power of the motor. d I is the excitation current component. q V is the torque current component. d and V q The reference voltage vectors are obtained based on the excitation current component and the torque current component, respectively; the power change is determined based on the difference between the power of the motor in the current control cycle and the power in the previous control cycle.

[0052] Among them, V d ×I d Characterizing the pure active component, specifically, the quadrature axis (q-axis) directly generates electromagnetic torque, with energy output / mechanical work performed, all corresponding to active power; the energy for the motor to drive the load and output torque all comes from V. d ×I d .

[0053] V q ×I qIt represents the reactive power plus the equivalent loss component of field weakening, and is not output as mechanical work. That is, V q ×I q This represents the excitation reactive power used to counteract the permanent magnet flux linkage and weaken the air gap magnetic field. It only establishes / counters the magnetic field inside the motor and does not convert into mechanical active power output; it belongs to inductive reactive power.

[0054] V d ×I d With V q ×I q After adding the two together, the total active power input of the three-phase stator of the motor is obtained by restoring it using the coordinate conversion factor 3 / 2.

[0055] Power change P motor =P motor (k)-P motor (k-1). Instantaneous motor power P calculated in real time based on the dq axis. motor Calculate the change in power P motor By predicting the changing trend of the synthesized reference voltage required by the motor through power step changes, a feedforward pre-adjustment command is applied to the PFC bus voltage loop: like P motor For a positive step (P) motor (Sudden surge in load): Anticipating a rapid increase in the motor's d / q composite reference voltage, a pre-boost command is sent to the PFC voltage loop to proactively raise the DC bus voltage V. bus The bus voltage is raised before the modulation coefficient MI rises significantly and the inverter enters voltage saturation, to prevent the bus voltage from dropping and the modulation coefficient from exceeding the limit during a sudden increase in load.

[0056] like P motor A negative step (P) motor (Sudden reduction in voltage, sudden load unloading): Predicting that the reference voltage required for motor d / q synthesis will decrease synchronously, a pre-voltage reduction command is issued to actively reduce the bus voltage, avoiding excessively high bus voltage and excessively low modulation coefficient, which would increase bus losses and switching losses.

[0057] The specific implementation process of determining the rate of change of rotational speed based on the rotational speed in step S130 is as follows: the rate of change of rotational speed dω / dt is: dω / dt=[ω(k)-ω(k-1)] / T S .

[0058] Specifically, when the motor is running at high speed, the amplitude of the motor's back electromotive force is directly proportional to the mechanical speed; the motor speed is collected in real time and the rate of change of speed dω / dt is calculated using discrete difference, and then compared with a preset speed change threshold. If the rate of change of speed dω / dt is greater than the preset speed change threshold (e.g., 500 rpm / s), the motor is determined to be in a rapid acceleration condition, and the motor's synthesized reference voltage is predicted to rise rapidly. The target value of the PFC bus voltage is proactively increased in advance, and the bus voltage pre-rise is completed before the reference voltage amplitude increases and the modulation coefficient MI reaches saturation.

[0059] If the deceleration is rapid (dω / dt significantly exceeds the preset speed change threshold in the negative direction), it is predicted that the motor's synthetic reference voltage will drop rapidly, and the target value of the PFC bus voltage is actively reduced to achieve pre-voltage reduction control.

[0060] The specific implementation process of determining the preset compensation amount based on the working state of the PI controller of the current loop in the field-oriented control algorithm in step S130 is as follows: real-time monitoring of the output voltage V of the direct-axis and quadrature-axis current loop PI controllers of the field-oriented control (FOC) d V q V d V q The operating status is determined by comparing the voltage with the software / hardware voltage limit value: when V d Or V q If any voltage limit is reached, the current loop PI controller is determined to be in saturation. This indicates that the current DC bus voltage supply is insufficient and cannot provide the d / q axis reference voltage vector required to track the target current. At this point, the PFC bus pre-boost regulation is forcibly triggered to continuously raise the target bus voltage value, expanding the inverter voltage output margin until V... d V q All are out of the limiting range and the saturation state is completely released. It can be understood that when the working state is saturation, the preset compensation amount is a fixed value greater than 0, in order to forcibly raise the target value of the bus voltage to trigger the bus voltage boost until the saturation state is completely released. It can be applied to cope with extreme load change conditions such as heavy load impact and sudden extreme load.

[0061] Step S140: Determine the second voltage regulation amount based on the first voltage regulation amount, power change amount, speed change rate, and preset compensation amount.

[0062] Step S150: Adjust the bus voltage according to the second voltage adjustment amount.

[0063] Specifically, the first voltage regulation quantity is the main feedback quantity of bus voltage regulation. It is generated by solving the real-time modulation coefficient from the excitation current component and the torque current component, combined with the deviation of the preset target coefficient through incremental PI calculation. It can eliminate the steady-state error of the modulation coefficient, maintain the modulation coefficient in the linear optimal range for a long time, and perform closed-loop correction on the voltage deviation caused by feedforward compensation.

[0064] The power change, speed change rate, and the preset compensation amount corresponding to the current loop PI working state are superimposed to form the feedforward compensation amount. The feedforward compensation amount can predict load changes and speed fluctuations in advance and actively adjust the bus voltage, so that the bus voltage regulation response time is shortened from tens of milliseconds to milliseconds by pure feedback control that relies solely on the first voltage regulation amount.

[0065] Thus, the system adopts a composite control architecture that combines feedforward prediction dynamic voltage regulation with closed-loop steady-state correction of the first voltage regulation amount, which can balance dynamic response speed and steady-state control accuracy.

[0066] In some embodiments, the specific implementation process of step S140 includes the following steps: the second voltage adjustment amount is: V bus_pre =V bus_PI +K FFp ×ΔP motor +K FFp ×(dω / dt)+V FF_sat , where V bus_pre V is the second voltage regulation value. bus_PI K is the first voltage regulation value. FFp ΔP is a preset coefficient. motor The power change is set to 0 when it is less than the power change threshold. dω / dt is the speed change rate; it is set to 0 when it is less than the speed change threshold. FF_sat The preset compensation amount is V when the working state is saturated. FF_sat It is a fixed value greater than 0.

[0067] Among them, K FFp For a pre-calibrated fixed proportional coefficient, the compensation amplitude of the two feedforwards, namely the power change and the speed change rate, is uniformly scaled to match the bus voltage regulation sensitivity corresponding to the system power and speed. It can be set based on the actual application scenario.

[0068] K FFp ×ΔP motor The feedforward input characterizes the power change. When the power change is less than the power change threshold, the load is considered stable without sudden changes, and ΔP is set... motor =0, power feedforward is turned off to avoid frequent bus voltage fluctuations caused by small power fluctuations. In other words, K is only enabled when the power change is greater than or equal to the power change threshold. FFp ×ΔP motor It will only take effect after that. Among them, the power change threshold is a preset threshold, which can be set according to the actual application scenario.

[0069] K FFp×(dω / dt) represents the feedforward input of the speed change rate. When the speed change rate is less than the speed change threshold, the motor is considered to be running smoothly, and dω / dt is set to 0, thus disabling the speed feedforward and eliminating ineffective voltage regulation caused by slight speed fluctuations. In other words, K only becomes active when the speed change rate is greater than or equal to the speed change threshold. FFp The effect only takes effect after ×(dω / dt). The speed change threshold is a pre-set threshold that can be adjusted based on the actual application scenario.

[0070] V FF_sat A preset compensation value characterizing the current loop state. This value is assigned based on whether the FOC current loop's PI controller is in saturation or non-saturation: when the current loop's PI controller is in saturation, V... FF_sat Take a fixed compensation value greater than 0 (e.g., 5V) to force an increase in the bus voltage margin and quickly release integral saturation; when the PI controller of the current loop is in a non-saturated state, V FF_sat =0, no additional compensation voltage is added, reducing the static loss of the system.

[0071] In some embodiments, such as Figure 4 As shown, the specific implementation process of step S150 includes the following steps S410 to S440.

[0072] Step S410: When the second voltage regulation amount is greater than or equal to the first voltage threshold and less than or equal to the second voltage threshold, the second voltage regulation amount is set as the target regulation amount.

[0073] Step S420: When the second voltage adjustment amount is less than the first voltage threshold, set the first voltage threshold as the target adjustment amount.

[0074] Step S430: When the second voltage regulation amount is greater than the second voltage threshold, set the second voltage threshold as the target regulation amount.

[0075] Step S440: Adjust the bus voltage according to the target adjustment amount.

[0076] Specifically, the first voltage threshold (denoted as V) bus_min This is the pre-calibrated minimum limit value for bus regulation, i.e., the minimum allowable value for the target regulation amount. It is used to prevent the bus voltage from being regulated to an excessively low level, avoiding insufficient bus voltage supply under high-speed, heavy-load motor conditions. First voltage threshold V bus_min The first voltage threshold V is determined by the peak value of the AC input voltage and the maximum duty cycle of the PFC circuit. In a specific embodiment, the first voltage threshold V bus_min When configured for 250V, with a minimum effective AC input of 176V, the peak input voltage is 176 × 2. 1 / 2≈248.9V; To ensure that the PFC has a boost regulation margin and to avoid duty cycle saturation, the typical lower limit is set to 250V.

[0077] Second voltage threshold (denoted as V) bus_max The second voltage threshold V is the pre-calibrated maximum limit for bus regulation, representing the maximum allowable value for the target regulation. It is used to prevent the bus voltage from being regulated to excessively high levels, thus preventing overvoltage stress on the bus capacitors and switching transistors. bus_max Determined by the rated withstand voltage of the power switching transistors and the DC bus electrolytic capacitors, this is the highest bus voltage that the hardware devices are allowed to operate safely for extended periods. In a specific embodiment, the second voltage threshold V... bus_max It is configured for 400V; if the bus voltage exceeds 400V, the switching transistors and capacitors will be subjected to over-rated voltage for a long time, which will accelerate the aging and breakdown of the devices.

[0078] When V bus_min ≤V bus_pre ≤V bus_max When the second voltage regulation falls within the safe range between the upper and lower thresholds, no limiting correction is needed. The original second voltage regulation is directly assigned as the target regulation, i.e., V bus_tar =V bus_pre V bus_tar The target adjustment amount is as follows. This means that the current demand for composite voltage regulation is moderate, the magnitude of the bus voltage increase / decrease is within the safe allowable range, the voltage regulation command of feedback and feedforward superposition is fully preserved, and the dynamic voltage regulation capability is not weakened.

[0079] When V bus_pre <V bus_min When the second voltage regulation is below the lower threshold, direct use would result in excessively low bus voltage, triggering insufficient inverter voltage margin and over-modulation risk. Forced clamping to the lower threshold is used, assigning the first voltage threshold as the target regulation, i.e.: V bus_tar =V bus_min This enables minimum bus voltage protection, ensuring that even with light load and feedforward output voltage reduction commands, the bus voltage will not fall below the safety limit, guaranteeing the motor has basic voltage output capability throughout the entire process.

[0080] When V bus_pre >V bus_max When the second voltage regulation value exceeds the upper limit threshold, direct use will cause excessively high bus voltage, leading to overvoltage of power devices and bus capacitors, and a surge in losses. Forced clamping to the upper limit threshold and assigning the second voltage threshold value as the target regulation value, i.e., V... bus_tar =V bus_max This enables protection against the highest bus voltage. Even with sudden extreme overloads or current loop saturation triggering a significant voltage boost command, the bus voltage will not exceed the device's withstand voltage limit, thus achieving hardware overvoltage protection.

[0081] Target adjustment amount V after amplitude limiting bus_tar The PI controller input to the PFC voltage loop adjusts the duty cycle of the PWM signal driving the switching transistor in real time through PFC dual closed-loop control, thereby completing the adjustment action of raising or lowering the DC bus voltage.

[0082] Please refer to Figure 5 , Figure 5 An exemplary block diagram of voltage control performed by a control processing unit is shown. For example... Figure 5 As shown, the control architecture consists of two parts: The first part is the inner basic closed loop, namely the relevant components of the PFC's own dual-loop control (the PI controller in the bus voltage loop and the PI controller in the current loop), which is responsible for stabilizing the actual DC bus voltage. This first part is common knowledge in the field and will not be elaborated upon here. The second part is the voltage regulation correction loop. This loop combines main feedback regulation (i.e., the process implemented in step S120) with multi-path feedforward compensation (i.e., the process implemented in step S130) to generate a correction amount (i.e., the processes implemented in steps S140 and S150), thereby correcting the target value V of the bus voltage in real time. bus_tar This achieves steady-state precise constraint of the modulation coefficient and advance prediction of voltage regulation, keeping the modulation coefficient within an optimal range. Among them, V FF = K FFp ×ΔP motor +K FFp ×(dω / dt)+V FF_sat For detailed implementation instructions, please refer to the documentation for [specific implementation details]. Figure 1 The details of each step are not repeated here.

[0083] In some embodiments, after performing step S430 and before performing step S440, the bus voltage regulation method further includes the following step: performing step S440 when the bus voltage is less than a second voltage threshold and / or the modulation coefficient is less than or equal to a first coefficient threshold.

[0084] Wherein, the first coefficient threshold (denoted as MI) max ) is the upper limit threshold of the modulation coefficients allowed for linear modulation, such as 0.95, which can be set based on the actual application scenario.

[0085] Specifically, the execution step S440 is triggered by the following three types of conditions: First type of operating condition: V bus <V bus_max Regardless of the modulation coefficient MI, at this time, the bus has not reached the hardware boost limit and still has the voltage regulation margin to boost the bus voltage. The bus boost is used first to expand the voltage output margin, and step S440 is executed normally.

[0086] Second type of operating condition: MI≤MI max Regardless of whether the bus voltage reaches V bus_max At this point, the modulation coefficient MI is within the safe linear modulation range, and there is no risk of overmodulation. Therefore, there is no need to activate the field weakening compensation, and the conventional bus voltage regulation is directly executed, i.e., step S440 is executed normally.

[0087] Third type of operating condition: V bus <V bus_max And MI≤MI max At this point, the bus voltage regulation margin is sufficient, the modulation waveform quality is good, the feedback and feedforward prediction voltage regulation functions are fully preserved, and the target bus voltage is dynamically corrected, i.e., step S440 is executed normally.

[0088] In some embodiments, after performing step S430 and before performing step S440, the bus voltage regulation method further includes the following step: when the bus voltage is greater than or equal to a second voltage threshold and the modulation coefficient is greater than a first coefficient threshold, the control current loop increases a negative magnetic weakening current.

[0089] Specifically, when V bus ≥V bus_max And MI>MI max If the system has reached its bus voltage hardware limit, even if the bus is pulled up to the maximum safe voltage, the inverter's linear modulation margin is still insufficient, and the reference voltage vector required by the motor exceeds the current system's maximum output capacity. At this point, the bus voltage boost regulation is stopped, and a command is sent to the FOC field-oriented control to actively superimpose a negative direct-axis field-weakening current. This weakens the motor's air gap back electromotive force, reducing the motor's demand for output voltage, thus causing the modulation coefficient MI to fall back into the linear modulation range.

[0090] In some embodiments, the magnetic weakening current is: ,in, For weak magnetic current, K fw V is the magnetic weakening proportional adjustment coefficient. ref The magnitude of the synthesized voltage vector along the dq axis. V bus_max MI is the second voltage threshold. max This is the first coefficient threshold.

[0091] Specifically, The given value of the direct-axis weakening magnetic current is the target current output to the FOC direct-axis current loop; the formula has a negative sign, and the calculation result is always negative, representing the demagnetizing weakening magnetic current used to counteract the air gap flux linkage of the permanent magnet.

[0092] K fw This is a positive proportional gain, used to adjust the sensitivity by matching the voltage difference and the magnetic weakening current; Kfw The larger the value, the greater the amplitude of the weak magnetic current output under the same voltage deficit, and the faster the modulation coefficient MI falls back.

[0093] V ref This represents the total voltage amplitude that the inverter needs to output under the current operating conditions. (V) ref The larger the value, the higher the motor load / speed, and the tighter the voltage requirement.

[0094] This indicates the maximum safe output voltage allowed by linear modulation.

[0095] This represents the difference between the current voltage demand and the maximum allowable voltage for linear modulation, i.e., the voltage gap. The larger the gap, the more severe the overmodulation.

[0096] This indicates a negative direct-axis current output, generating an armature reaction flux opposite to the permanent magnet flux linkage, weakening the total air gap flux linkage, and reducing the motor's back electromotive force (EMF). After the back EMF decreases, the V required to maintain the same torque and speed... d and V q Simultaneous decrease, V ref It then decreases until V ref ≤ The modulation coefficient falls back to MI≤MI max It exits overmodulation, and the modulation coefficient falls back to the linear modulation range.

[0097] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

[0098] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Within the framework of this application, the technical features of the above embodiments or different embodiments can also be combined, and the steps can be implemented in any order. Those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for regulating bus voltage, characterized in that, The method for regulating the bus voltage of a motor drive system, wherein the motor in the motor drive system is driven by a field-oriented control algorithm, includes: Obtain the excitation current component, torque current component, and speed of the motor in the motor control system; The modulation coefficient is determined based on the excitation current component and the torque current component, and feedback adjustment is performed based on the difference between the preset target coefficient and the modulation coefficient to obtain the first voltage adjustment amount. The power change of the motor is determined based on the excitation current component and the torque current component, the speed change rate is determined based on the speed, and the preset compensation amount is determined based on the working state of the PI controller of the current loop in the field-oriented control algorithm, wherein the working state is either saturated or unsaturated. The second voltage adjustment amount is determined based on the first voltage adjustment amount, the power change amount, the speed change rate, and the preset compensation amount; The bus voltage is adjusted according to the second voltage adjustment amount.

2. The bus voltage regulation method according to claim 1, characterized in that, The step of performing feedback adjustment based on the difference between the preset target coefficient and the modulation coefficient to obtain the first voltage adjustment amount includes: Incremental PI regulation is performed based on the difference between the preset target coefficient and the modulation coefficient to obtain the first voltage regulation amount.

3. The bus voltage regulation method according to claim 1, characterized in that, Determining the power change of the motor based on the excitation current component and the torque current component includes: The power of the motor is: P motor =3 / 2×(V d ×I d +V q ×I q ), where P motor I is the power of the motor. d For the excitation current component, I q V is the torque current component. d and V q These are reference voltage vectors obtained based on the excitation current component and the torque current component, respectively. The power change is determined based on the difference between the power of the motor in the current control cycle and the power in the previous control cycle.

4. The bus voltage regulation method according to claim 1, characterized in that, Determining the second voltage adjustment amount based on the first voltage adjustment amount, the power change amount, the speed change rate, and the preset compensation amount includes: The second voltage regulation amount is: V bus_pre =V bus_PI +K FFp ×ΔP motor +K FFp ×(dω / dt)+V FF_sat , where V bus_pre V is the second voltage regulation amount. bus_PI K is the first voltage regulation amount. FFp ΔP is a preset coefficient. motor The power change is defined as follows: when the power change is less than a power change threshold, the power change is set to 0; dω / dt is the rotational speed change rate; when the rotational speed change rate is less than a rotational speed change threshold, the rotational speed change rate is set to 0; V FF_sat The preset compensation amount is V when the working state is saturated. FF_sat It is a fixed value greater than 0.

5. The bus voltage regulation method according to claim 1, characterized in that, The step of adjusting the bus voltage according to the second voltage adjustment amount includes: When the second voltage regulation amount is greater than or equal to the first voltage threshold and less than or equal to the second voltage threshold, the second voltage regulation amount is set as the target regulation amount; When the second voltage adjustment amount is less than the first voltage threshold, the first voltage threshold is set as the target adjustment amount; When the second voltage adjustment amount is greater than the second voltage threshold, the second voltage threshold is set as the target adjustment amount; Adjust the bus voltage according to the target adjustment amount.

6. The bus voltage regulation method according to claim 5, characterized in that, Before performing the step of adjusting the bus voltage according to the target adjustment amount, the method further includes: When the bus voltage is less than the second voltage threshold and / or the modulation coefficient is less than or equal to the first coefficient threshold, the step of adjusting the bus voltage according to the target adjustment amount is performed.

7. The bus voltage regulation method according to claim 5, characterized in that, Before performing the step of adjusting the bus voltage according to the target adjustment amount, the method further includes: When the bus voltage is greater than or equal to the second voltage threshold and the modulation coefficient is greater than the first coefficient threshold, the current loop is controlled to increase a negative magnetic weakening current.

8. The bus voltage regulation method according to claim 7, characterized in that, The magnetic weakening current is: ,in, For the weak magnetic current, K fw V is the magnetic weakening proportional adjustment coefficient. ref The magnitude of the synthesized voltage vector along the dq axis. V bus_max MI is the second voltage threshold. max The threshold value is the first coefficient.

9. A control processing unit, characterized in that, include: At least one processor and memory; The memory is coupled to the processor and is used to store instructions or programs that, when executed by the at least one processor, cause the at least one processor to perform the bus voltage regulation method as described in any one of claims 1-8.

10. A motor drive system, characterized in that, It includes a power factor correction circuit, a three-phase inverter, a motor, and a control processing unit as described in claim 9; The power factor correction circuit takes AC power as input and outputs the bus voltage. The three-phase inverter is electrically connected to the power factor correction circuit, the motor, and the control processing unit, respectively. The three-phase inverter receives the bus voltage and drives the motor under the control of the control processing unit.

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