Rapid braking method and system for high-voltage brushless motor

Abstract

The invention discloses a rapid braking method and system for a high-voltage brushless motor, and relates to the technical field of braking control. The method comprises the steps that the direct-current bus voltage of a motor is monitored, and a preset voltage safety threshold value is obtained and input to a braking current decision module; dynamically calculating a braking current given value; when the direct-current bus voltage is lower than the voltage safety threshold value, the braking current given value is made to change in the increasing direction so as to accelerate braking; when the direct current bus voltage approaches or reaches the voltage safety threshold value, the braking current given value is made to change in the decreasing direction; and applying corresponding phase current to the motor based on the braking current given value until the rotating speed of the motor is reduced to the target braking rotating speed. By the adoption of the scheme, on the premise that the voltage of the direct-current bus does not exceed the voltage safety threshold value, maximum rapid braking of the high-voltage brushless motor at different rotating speeds can be achieved, it is ensured that the voltage of the direct-current bus is stable in the braking process, and damage to the motor and circuit elements caused by voltage overrun is avoided.

Description

Technical Field

[0001] This application relates to the field of braking control technology, specifically to a rapid braking method and system for a high-voltage brushless motor. Background Technology

[0002] High-pressure brushless motors, with their advantages of high efficiency, high speed, and low noise, have become the core power component of high-pressure brushless vacuum cleaners. In actual use, the motor needs to start and stop frequently; rapid and stable braking can shorten downtime and reduce downtime noise. Furthermore, stable bus voltage during braking can prevent damage to circuit components and ensure long-term equipment operation. Therefore, how to achieve rapid braking of high-pressure brushless vacuum cleaner motors while ensuring bus voltage safety has become a pressing technical problem to be solved in the industry.

[0003] There are two main braking methods for existing high-pressure brushless vacuum cleaner motors: one is that after receiving a stop command, the motor relies on its own rotor inertia to coast freely until the speed naturally drops to a preset low speed threshold, at which point the braking mechanism is activated to stop the machine. This method results in a long coasting time from normal operating speed to the preset low speed, leading to low braking efficiency. The other method involves providing a fixed negative current value in the control loop after receiving a stop command, causing the motor to operate in a generator state, converting the rotor's mechanical energy into electrical energy to increase the load and reduce speed. The braking mechanism is activated when the speed drops to the preset low speed threshold. The negative current value is set according to the motor's limit speed operating condition to control the range of bus voltage rise. However, in this method, the higher the speed, the greater the rise in bus voltage. Furthermore, the fixed negative current applied to braking at normal operating speed is insufficient for the load, resulting in a long braking time. Summary of the Invention

[0004] This application provides a method, system, device, and medium for rapid braking of a high-voltage brushless motor, which solves the problem of achieving maximum rapid braking of a high-voltage brushless vacuum cleaner motor at different speeds, provided that the bus voltage does not exceed a set value.

[0005] In a first aspect, this application provides a rapid braking method for a high-voltage brushless motor, the method comprising: The DC bus voltage of the motor is monitored, and a preset voltage safety threshold is obtained. The DC bus voltage is used as the controlled feedback quantity, and the voltage safety threshold is used as the control target quantity, and both are input to the braking current decision module. Based on the braking current decision module, the braking current setpoint is dynamically calculated according to the real-time deviation between the controlled feedback quantity and the control target quantity. The dynamic calculation method includes: when the DC bus voltage is lower than the voltage safety threshold, the braking current setpoint is changed to increase to accelerate braking; when the DC bus voltage approaches or reaches the voltage safety threshold, the braking current setpoint is changed to decrease to constrain the DC bus voltage within the voltage safety threshold; based on the braking current setpoint, the corresponding phase current is applied to the motor until the motor speed drops to the target braking speed.

[0006] By adopting the above technical solution, it is possible to achieve maximum rapid braking of high-voltage brushless motors at different speeds, provided that the DC bus voltage does not exceed the voltage safety threshold. This ensures that the DC bus voltage remains stable during braking and avoids damage to the motor and circuit components caused by voltage over-limit.

[0007] In a specific feasible implementation, dynamic solution includes: Calculate the instantaneous deviation between the DC bus voltage and the voltage safety threshold; input the instantaneous deviation value into the proportional-integral controller, and generate proportional and integral components through the proportional and integral operation channels respectively; superimpose the proportional and integral components to generate the initial control quantity as the braking current setpoint.

[0008] By adopting the above technical solutions, the calculation accuracy and stability of the braking current setpoint are improved, the fluctuation of the braking current is reduced, and the consistency and smoothness of the motor braking effect are ensured.

[0009] In a specific feasible implementation, the initial control quantity is subjected to amplitude limiting after dynamic calculation. The amplitude limiting process includes: Define a dynamic current limit that is positively correlated with the current motor speed; compare the amplitude of the initial control quantity with the dynamic current limit; if the amplitude of the initial control quantity exceeds the dynamic current limit, use the dynamic current limit as the braking current setpoint; otherwise, use the initial control quantity as the braking current setpoint.

[0010] By adopting the above technical solution, the braking current is prevented from exceeding the allowable limit corresponding to the current speed of the motor, thus preventing excessive current from impacting the motor windings and circuit components. At the same time, it adapts to the braking requirements of the motor at different speeds, balancing braking efficiency and equipment operation safety.

[0011] In one specific implementation scheme, the proportional gain coefficient and integral gain coefficient of the proportional-integral controller are adjusted by mapping according to the motor speed, wherein the mapping rules include: Under the same voltage deviation, the higher the motor speed, the larger the values ​​of the proportional gain coefficient and integral gain coefficient should be, so as to improve the braking current response intensity in the high-speed range of the motor.

[0012] By adopting the above technical solutions, the response speed and intensity of the braking current in the high-speed range of the motor are improved, ensuring that the motor can quickly obtain sufficient braking load to shorten the deceleration time at high speed, while maintaining braking stability in the low-speed range, and further optimizing the braking adaptation effect in different speed ranges.

[0013] In one specific feasible implementation, the method of applying a corresponding phase current to the motor includes: The braking current setpoint is used as the outer loop current command and compared with the actual current feedback value obtained by sampling the motor phase current and coordinate transformation to generate a current error signal. The current error signal is input to the inner loop current regulator, which combines the back EMF information of the motor to perform feedforward compensation and outputs the voltage control command for each phase winding of the motor. Based on the voltage control command, the braking current applied to the motor winding is generated.

[0014] By adopting the above technical solutions, the tracking accuracy and response speed of the braking current are improved, the interference of back EMF on the braking current control is reduced, and the braking current can be accurately and quickly applied to the motor windings, thereby improving the efficiency and stability of the braking process.

[0015] In one specific feasible implementation, the method for generating voltage control commands includes: Based on the motor model and speed, the feedforward voltage component used to offset the back EMF is calculated; the current error signal is subjected to proportional-integral operation to generate the feedback voltage component used to eliminate steady-state error; the voltage suppression factor is calculated based on the instantaneous value of the DC bus voltage and its proximity to the voltage safety threshold; and the voltage control commands for each phase winding of the motor are generated by combining the feedforward voltage component, the feedback voltage component, and the voltage suppression factor.

[0016] By adopting the above technical solution, the influence of back EMF on current control is effectively offset, the steady-state error of current is eliminated, and the abnormal rise of DC bus voltage is further suppressed. This balances the precise control of braking current with the stability of bus voltage, thereby improving the overall reliability of the braking process.

[0017] In a specific feasible implementation, dynamic solution includes: The rate of change of DC bus voltage per unit time is calculated. When the rate of change exceeds the preset positive rate threshold, a negative correction is added to the dynamically calculated output to suppress the excessively rapid rise of bus voltage. When the rate of change exceeds the preset negative rate threshold, the negative correction is reduced or removed to maintain basic braking performance.

[0018] By adopting the above technical solution, the rapid rise of DC bus voltage can be suppressed in advance, avoiding voltage surges beyond limits. At the same time, when the bus voltage drops too quickly, the basic braking performance of the motor can be maintained, achieving a dynamic balance between bus voltage stability and braking efficiency during braking, thus improving braking smoothness and safety.

[0019] A second aspect of this application provides a rapid braking system for a high-voltage brushless motor, the system comprising: The bus voltage monitoring module is configured to monitor the DC bus voltage of the motor in real time; the braking current decision module is configured to receive the DC bus voltage and the voltage safety threshold, and dynamically calculate the braking current setpoint; wherein, the calculation logic of the braking current decision module is configured as follows: when the DC bus voltage is lower than the voltage safety threshold, the braking current setpoint is changed to increase to accelerate braking; when the DC bus voltage approaches or reaches the voltage safety threshold, the braking current setpoint is changed to decrease to constrain the DC bus voltage within the voltage safety threshold; the current application module is configured to apply the corresponding phase current to the motor based on the braking current setpoint until the motor speed drops to the target braking speed.

[0020] A third aspect of this application provides an electronic device, comprising: a processor and a memory; wherein the memory stores a computer program adapted to be loaded by the processor and to execute the method steps described above.

[0021] A fourth aspect of this application provides a computer storage medium storing a plurality of instructions adapted for loading by a processor and executing the method steps described above. Attached Figure Description

[0022] Figure 1 This is a schematic flowchart of a rapid braking method for a high-voltage brushless motor provided in an embodiment of this application; Figure 2 This is a control circuit diagram of the braking state of a high-voltage brushless motor provided in an embodiment of this application; Figure 3 This is a control circuit diagram of a high-voltage brushless motor in normal working condition provided in an embodiment of this application. Detailed Implementation

[0023] To enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0024] In the description of the embodiments of this application, the words "for example" or "for instance" are used to indicate examples, illustrations, or explanations. Any embodiment or design that is described as "for example" or "for instance" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design options. Rather, the use of the words "for example" or "for instance" is intended to present the relevant concepts in a specific manner.

[0025] In the description of the embodiments of this application, the term "multiple" means two or more. For example, multiple systems means two or more systems, and multiple screen terminals means two or more screen terminals. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. The terms "comprising," "including," "having," and variations thereof all mean "including but not limited to," unless otherwise specifically emphasized.

[0026] Please refer to Figure 1 A flowchart illustrating a rapid braking method for a high-voltage brushless motor is presented. This method can be implemented using a computer program, a microcontroller, or run on a rapid braking system for a high-voltage brushless motor. The computer program can be integrated into a computer device or run as a standalone application. Specifically, the method includes steps S100 to S400, as follows: S100: Monitor the DC bus voltage of the motor and obtain the preset voltage safety threshold. In some embodiments, the controller acquires the DC side voltage signal in the high-voltage brushless motor power supply circuit in real time. The acquisition process is achieved through a voltage sensor connected in series with the DC bus. The voltage sensor converts the acquired analog voltage signal into a digital voltage signal that the controller can recognize. After receiving the digital voltage signal, the controller obtains the DC bus voltage. At the same time, the controller reads a preset voltage safety threshold.

[0027] In some embodiments, the voltage safety threshold can be 300 volts.

[0028] S200: The DC bus voltage is used as the controlled feedback quantity, and the voltage safety threshold is used as the control target quantity, and input to the braking current decision module. In some embodiments, the controller transmits the controlled feedback quantity and the control target quantity to the braking current decision module through an internal data transmission interface. After receiving the two sets of data, the braking current decision module enters a waiting state and waits to execute the subsequent dynamic calculation process.

[0029] S300: Based on the braking current decision module, the braking current setpoint is dynamically calculated according to the real-time deviation between the controlled feedback quantity and the control target quantity. The dynamic calculation method includes: when the DC bus voltage is lower than the voltage safety threshold, the braking current setpoint is changed to increase to accelerate braking; when the DC bus voltage approaches or reaches the voltage safety threshold, the braking current setpoint is changed to decrease to constrain the DC bus voltage within the voltage safety threshold. In this embodiment of the application, the braking current setpoint is an instruction value output by the braking current decision module to control the magnitude of the motor braking current. The value is a negative current value, corresponding to the generator current instruction when the motor is braking. The direction of the negative current is opposite to the direction of the current when the motor is working normally, and it is used to convert the mechanical energy of the motor rotor into electrical energy to achieve braking.

[0030] In some embodiments, the braking current decision module first calculates the real-time deviation between the controlled feedback quantity, i.e., the DC bus voltage, and the control target quantity, i.e., the voltage safety threshold. The real-time deviation is the difference obtained by subtracting the DC bus voltage from the voltage safety threshold. The braking current decision module dynamically calculates the braking current setpoint based on the magnitude and trend of the real-time deviation.

[0031] When the DC bus voltage is lower than the voltage safety threshold, the real-time deviation is positive. The braking current decision module controls the braking current setpoint to increase. The increased braking current can enhance the motor's generator braking effect, apply a larger load to the motor rotor, and thus accelerate the decrease of motor speed to achieve rapid braking.

[0032] When the DC bus voltage approaches or reaches the voltage safety threshold, the real-time deviation approaches or becomes zero. The braking current decision module controls the braking current setpoint to decrease. The reduced braking current can reduce the motor's power generation and prevent excessive energy conversion that could cause the DC bus voltage to exceed the voltage safety threshold, thereby stabilizing and constraining the DC bus voltage within the voltage safety threshold.

[0033] refer to Figures 2 to 3 Based on the above embodiments, as another optional embodiment, dynamic solution includes: S301. Calculate the instantaneous deviation between the DC bus voltage and the voltage safety threshold. In some embodiments, the braking current decision module calls the internal deviation calculation subroutine to perform a numerical subtraction operation between the real-time sampled value of the DC bus voltage obtained in S100 and the voltage safety threshold. The calculation result is the instantaneous deviation value between the DC bus voltage and the voltage safety threshold.

[0034] The sign of the instantaneous deviation value reflects the level of the DC bus voltage relative to the voltage safety threshold. A positive instantaneous deviation value indicates that the DC bus voltage is lower than the voltage safety threshold, a negative instantaneous deviation value indicates that the DC bus voltage is higher than the voltage safety threshold, and a zero instantaneous deviation value indicates that the DC bus voltage is equal to the voltage safety threshold.

[0035] S302. Input the instantaneous deviation value into the proportional-integral controller, and generate proportional and integral components through the proportional calculation channel and the integral calculation channel respectively; In some embodiments, the braking current decision module transmits the instantaneous deviation value to the signal input terminal of the proportional-integral controller. After receiving the instantaneous deviation value, the proportional-integral controller simultaneously activates its internal proportional calculation channel and integral calculation channel.

[0036] The proportional calculation channel performs proportional amplification calculation on the instantaneous deviation value. During the calculation, the instantaneous deviation value is amplified according to the preset proportional gain coefficient to obtain the proportional component. The integral calculation channel performs integral calculation on the instantaneous deviation value. During the calculation, the instantaneous deviation value is accumulated and calculated in the time dimension according to the preset integral gain coefficient to obtain the integral component.

[0037] Based on the above embodiments, as another optional embodiment, the proportional gain coefficient and integral gain coefficient of the proportional-integral controller are adjusted by mapping according to the motor speed, wherein the mapping rules include: Under the same voltage deviation, the higher the motor speed, the larger the values ​​of the proportional gain coefficient and integral gain coefficient should be, so as to improve the braking current response intensity in the high-speed range of the motor.

[0038] In some embodiments, the controller acquires the motor's rotational speed signal in real time. The rotational speed signal is obtained through a motor position and speed estimator, which calculates the motor's real-time rotational speed based on the motor's phase current and voltage signals.

[0039] The controller internally stores a mapping table between motor speed and proportional gain coefficients and integral gain coefficients. This mapping table is pre-defined based on test data of the motor's braking characteristics. When the controller obtains the real-time speed of the motor, it consults the mapping table to determine the corresponding values ​​for the proportional gain coefficient and integral gain coefficient.

[0040] Under the same voltage deviation, if the real-time speed of the motor is higher, the values ​​of the proportional gain coefficient and integral gain coefficient will be larger. A larger proportional gain coefficient can speed up the response speed of the proportional calculation channel, and a larger integral gain coefficient can speed up the accumulation speed of the integral calculation channel, thereby improving the braking current response intensity in the high-speed range of the motor and ensuring that the motor can quickly obtain sufficient braking current to achieve rapid braking at high speed.

[0041] In some embodiments, when the motor speed is 100,000 rpm, the proportional gain coefficient can be 5.0 and the integral gain coefficient can be 0.8; when the motor speed is 50,000 rpm, the proportional gain coefficient can be 3.0 and the integral gain coefficient can be 0.5; when the motor speed is 30,000 rpm, the proportional gain coefficient can be 1.5 and the integral gain coefficient can be 0.3.

[0042] S303. The proportional and integral components are superimposed to generate the initial control quantity as the braking current setpoint.

[0043] In some embodiments, the proportional-integral controller transmits the proportional component and the integral component to the internal addition unit. After receiving the two components, the addition unit performs an algebraic superposition operation, maintaining the same numerical precision as the proportional and integral components during the operation. The result of the superposition operation is the initial control quantity, which is directly used as a candidate value for the braking current setpoint, waiting to enter the subsequent processing flow.

[0044] Based on the above embodiments, as another optional embodiment, the initial control quantity is subjected to amplitude limiting processing after dynamic calculation. The amplitude limiting processing includes: S304. Predefined dynamic current limits that are positively correlated with the current motor speed; In this embodiment of the application, the dynamic current limit is a maximum allowable value of braking current predefined according to the current speed of the motor. It changes with the change of motor speed to limit the amplitude of braking current and avoid excessive braking current from damaging the motor and circuit components.

[0045] In some embodiments, the controller stores the calculation formula and related parameters of the dynamic current limit. The controller first obtains the current speed of the motor and calculates the dynamic current limit through the preset calculation formula. The dynamic current limit is positively correlated with the current speed of the motor. That is, the higher the current speed of the motor, the larger the dynamic current limit, and the lower the current speed of the motor, the smaller the dynamic current limit.

[0046] In some embodiments, the dynamic current limit can be the product of the motor's current speed and the speed-current coefficient, where the speed-current coefficient is a fixed constant.

[0047] S305. Compare the amplitude of the initial control quantity with the dynamic current limit; In some embodiments, the controller invokes its internal comparison unit. The comparison unit first obtains the amplitude of the initial control quantity generated by S303. Simultaneously, the comparison unit obtains the dynamic current limit, and then compares the amplitude of the initial control quantity with the dynamic current limit. During the comparison, the precision of the two values ​​is maintained. The comparison unit outputs a comparison result, which is one of three cases: the amplitude of the initial control quantity is greater than the dynamic current limit, equal to the dynamic current limit, or less than the dynamic current limit.

[0048] S306. If the amplitude of the initial control quantity exceeds the dynamic current limit, the dynamic current limit shall be used as the braking current setpoint; otherwise, the initial control quantity shall be used as the braking current setpoint.

[0049] In some embodiments, the controller receives the comparison result of S305. If the comparison result is that the amplitude of the initial control quantity exceeds the dynamic current limit, the controller determines the dynamic current limit predefined in S304 as the final braking current setpoint. This setting can prevent excessive braking current from impacting the motor windings and circuit components.

[0050] If the comparison result shows that the amplitude of the initial control quantity does not exceed the dynamic current limit, the controller will directly determine the initial control quantity generated by S303 as the final braking current setpoint to ensure that the braking current can meet the needs of rapid braking to the greatest extent.

[0051] Based on the above embodiments, as another optional embodiment, dynamic solution includes: S307. Calculate the rate of change of DC bus voltage per unit time. When the rate of change exceeds the preset rate threshold in the positive direction, add a negative correction amount to the output of the dynamic solution in order to suppress the excessively rapid rise of the bus voltage in advance. In this embodiment, the rate of change of DC bus voltage per unit time refers to the ratio of the difference between two adjacent sampling periods to the sampling period, used to reflect how fast the DC bus voltage changes. The positive direction preset rate threshold is a preset maximum rate value that allows the DC bus voltage to rise. When the rate of rise of the DC bus voltage exceeds this value, it indicates that the bus voltage rises too fast and needs to be suppressed. In this embodiment, the negative direction preset rate threshold is a preset maximum rate value that allows the DC bus voltage to fall. When the rate of fall of the DC bus voltage exceeds this value, it indicates that the bus voltage falls too fast and the negative correction amount needs to be adjusted to maintain braking performance. The negative correction amount is a preset adjustment amount used to reduce the braking current setpoint. This value is negative, and when superimposed, it can reduce the amplitude of the braking current.

[0052] In some embodiments, the controller acquires two consecutive sampled values ​​of the DC bus voltage, with the sampling times corresponding to the two sampled values ​​being a first sampling time and a second sampling time, respectively, the second sampling time being later than the first sampling time. The controller calculates the difference between the DC bus voltage corresponding to the second sampling time and the DC bus voltage corresponding to the first sampling time, and then divides this difference by the time interval between the second sampling time and the first sampling time to obtain the rate of change of the DC bus voltage per unit time.

[0053] The controller reads the preset rate threshold in the positive direction and compares the rate of change with the preset rate threshold in the positive direction. When the rate of change exceeds the preset rate threshold in the positive direction, it indicates that the DC bus voltage is rising too fast. The controller adds a negative correction value to the braking current setpoint obtained by dynamic calculation in S300. The amplitude of the added braking current setpoint is reduced, thereby reducing the generator power of the motor and suppressing the excessively rapid rise of the bus voltage in advance.

[0054] In some embodiments, the positive preset rate threshold can be 50 volts per second, and the negative correction amount can be -20 amperes.

[0055] The controller reads the negative direction preset rate threshold and compares the rate of change of the DC bus voltage per unit time with the negative direction preset rate threshold. When the rate of change exceeds the negative direction preset rate threshold, it indicates that the DC bus voltage is dropping too quickly. Continuing to maintain the original negative correction amount will result in an insufficient braking current, affecting the braking effect. At this time, the controller reduces the magnitude of the negative correction amount or removes the negative correction amount directly, restoring the braking current setpoint to or close to the value before the negative correction amount was added, thereby maintaining the basic braking performance of the motor and ensuring the continuity and efficiency of the braking process.

[0056] In some embodiments, the negative direction preset rate threshold can be -30 volts per second, and the reduced negative correction amount can be -10 amperes.

[0057] S400: Apply the corresponding phase current to the motor based on the braking current setpoint until the motor speed drops to the target braking speed.

[0058] In this embodiment, the target braking speed is a pre-set threshold motor speed at which the mechanical braking action is initiated. When the motor speed drops to this threshold, the braking current braking phase ends, and the motor will be completely stopped by mechanical braking. This threshold is determined based on the braking characteristics of the motor and the working requirements of the mechanical braking.

[0059] In some embodiments, the controller acquires a braking current setpoint and generates a current control signal corresponding to the phase of the motor windings based on the winding phase characteristics and the current rotor position. The controller transmits the current control signal to the motor's drive circuit, which then drives the power switching devices to apply the corresponding phase of braking current to each phase winding of the motor.

[0060] During the application of braking current, the controller monitors the motor speed in real time through the position and speed estimator and compares the real-time speed with the target braking speed. When the real-time speed of the motor is higher than the target braking speed, the controller continues to output a current control signal to maintain the application of braking current; when the real-time speed of the motor drops to the target braking speed, the controller stops outputting the current control signal, and the braking current braking phase ends.

[0061] In some embodiments, the target braking speed can be 30,000 revolutions per minute.

[0062] Based on the above embodiments, as another optional embodiment, the method for applying a corresponding phase current to the motor includes: S401. The braking current setpoint is used as the outer loop current command and compared with the actual current feedback value obtained by sampling the motor phase current and coordinate transformation to generate a current error signal. In this embodiment of the application, coordinate transformation refers to the process of converting the phase current in the three-phase stationary coordinate system into the current signal in the two-phase rotating coordinate system, including Clark transformation and Park transformation; the actual current feedback value is the actual current value obtained after coordinate transformation and used for comparison with the outer loop current command; the current error signal is the difference between the outer loop current command and the actual current feedback value, which is used as the input signal of the inner loop current regulator.

[0063] In some embodiments, the controller determines the braking current setpoint as an outer loop current command, which is a q-axis current command in a two-phase rotating coordinate system. The controller acquires the three-phase currents of the motor through current sensors installed on the winding lines of each phase of the motor. The acquired three-phase currents are current signals in a three-phase stationary coordinate system. The controller performs a Clarke transform on the acquired three-phase currents, converting the current signals in the three-phase stationary coordinate system into α-axis and β-axis currents in a two-phase stationary coordinate system.

[0064] The controller performs a Parker transformation on the α-axis and β-axis currents, converting the current signals in the two-phase stationary coordinate system into d-axis and q-axis currents in the two-phase rotating coordinate system. The q-axis current is the actual current feedback value. The controller subtracts the outer-loop current command (i.e., the braking current setpoint) from the actual current feedback value, and the difference is the current error signal.

[0065] S402. Input the current error signal to the inner loop current regulator. The inner loop current regulator combines the back EMF information of the motor to perform feedforward compensation and outputs the voltage control command for each phase winding of the motor. In this embodiment of the application, the voltage control command is a command signal used to control the magnitude and phase of the voltage of each phase winding of the motor, and to drive the power switching device to generate the required braking current.

[0066] In some embodiments, the controller inputs a current error signal to the inner-loop current regulator. Upon receiving the current error signal, the inner-loop current regulator initiates its internal proportional-integral (PI) regulation calculation. Simultaneously, the controller obtains the motor's back electromotive force (EMF) information through the motor's position and speed estimator. The back EMF information is calculated based on the motor's real-time speed and the motor's back EMF coefficient.

[0067] The inner-loop current regulator incorporates back EMF information as a feedforward compensation quantity into the proportional-integral (PI) regulation calculation process. This feedforward compensation counteracts the interference of back EMF on current control, accelerating the elimination of current error signals. After completing the calculation, the inner-loop current regulator outputs voltage control commands for each phase winding of the motor. These commands include the voltage amplitude and phase information of each phase winding.

[0068] Based on the above embodiments, as another optional embodiment, the method for generating voltage control commands includes: S4021. Based on the motor model and speed, calculate the feedforward voltage component used to offset the back electromotive force. In this embodiment of the application, the motor model refers to a mathematical model that describes the input and output characteristics of the motor, including parameters such as the motor's resistance, inductance, and back electromotive force coefficient.

[0069] In some embodiments, the controller calculates the amplitude and phase of the back electromotive force (EMF) of each phase winding of the motor according to the motor model and real-time speed using a preset calculation formula. Then, based on the amplitude and phase of the back EMF, a feedforward voltage component with the same magnitude but opposite direction to the back EMF is calculated. This feedforward voltage component is used to counteract the influence of the back EMF during the generation of voltage control commands.

[0070] The formulas for calculating the feedforward voltage component include: U ff =K e ×n×θ.

[0071] Among them, U ff For the feedforward voltage component, K e θ is the back electromotive force coefficient of the motor, the value of which is determined by the structure and material properties of the motor; n is the real-time speed of the motor, in revolutions per minute; θ is the rotor position angle of the motor, in radians.

[0072] S4022. Perform proportional-integral calculation on the current error signal to generate a feedback voltage component for eliminating steady-state error; In some embodiments, the inner-loop current regulator performs proportional-integral calculations on the current error signal, using preset proportional and integral coefficients. The proportional calculation section amplifies the current error signal proportionally based on its magnitude, enabling rapid response to current deviations; the integral calculation section accumulates the current error signal over time to eliminate steady-state errors. The proportional and integral calculation results are superimposed to obtain the feedback voltage component, which is used to compensate for current errors, ensuring that the actual current feedback value accurately tracks the outer-loop current command.

[0073] S4023. Calculate the voltage suppression factor based on the instantaneous value of the DC bus voltage and its proximity to the voltage safety threshold. In this embodiment, the voltage suppression factor is a coefficient used to adjust the amplitude of the voltage control command. Its value ranges from 0 to 1 and changes dynamically according to the proximity of the instantaneous value of the DC bus voltage to the voltage safety threshold, in order to prevent the DC bus voltage from exceeding the voltage safety threshold.

[0074] In some embodiments, the controller acquires the instantaneous value of the DC bus voltage and calculates the ratio of the instantaneous value to a voltage safety threshold. Based on this ratio, the value of the voltage suppression factor is determined. When the instantaneous value of the DC bus voltage approaches or reaches the voltage safety threshold, the ratio approaches 1, and the voltage suppression factor decreases to reduce the amplitude of the voltage control command. When the instantaneous value of the DC bus voltage is far from the voltage safety threshold, the ratio is smaller, and the voltage suppression factor approaches 1, ensuring that the amplitude of the voltage control command can meet the braking current requirements.

[0075] The formula for calculating the voltage suppression factor includes: K v =1-(U bus / U th )×k.

[0076] Among them, K v U is the voltage suppression factor. bus U represents the instantaneous value of the DC bus voltage, in volts. th is the voltage safety threshold, in volts; k is the suppression coefficient, which ranges from 0 to 0.5 and is used to adjust the sensitivity of the voltage suppression factor.

[0077] In some embodiments, the inhibition coefficient k can be 0.3.

[0078] S4024: Combines the feedforward voltage component, the feedback voltage component, and the voltage suppression factor to generate voltage control commands for each phase winding of the motor.

[0079] In some embodiments, the inner-loop current regulator first algebraically superimposes the feedforward voltage component and the feedback voltage component to obtain a superimposed voltage component. Then, it multiplies the superimposed voltage component with a voltage suppression factor, and the result is the voltage control command for each phase winding of the motor. The voltage control command includes multiple functions, such as offsetting back electromotive force, eliminating current steady-state error, and suppressing excessive bus voltage, ensuring that the braking current is accurately and stably applied to the motor windings.

[0080] S403. Based on voltage control commands, generate a braking current applied to the motor windings.

[0081] In some embodiments, the controller transmits voltage control commands to the pulse width modulation (PWM) module. The PWM module generates a corresponding PWM signal based on the amplitude and phase information of the voltage control commands. The duty cycle of this PWM signal changes with the voltage control commands. The PWM module then transmits the PWM signal to the drive circuit of the power switching device. The drive circuit controls the on and off times of the power switching device according to the PWM signal. The power switching device turns on and off according to a preset logic, converting the DC bus voltage into the AC voltage required by each phase winding of the motor. This AC voltage acts on the motor windings, generating a braking current in the opposite direction to that during normal motor operation, thus achieving regenerative braking of the motor.

[0082] The technical solution of this invention is particularly applicable to high-pressure brushless vacuum cleaner motors, and can also be applied to other motors with high pressure, brushless operation and speed ≥100,000 rpm, such as high-pressure brushless blower motors, high-pressure brushless cleaning equipment motors, etc.

[0083] Based on the above embodiments, as another optional embodiment, this application also provides a rapid braking system for a high-voltage brushless motor, the system comprising: A bus voltage monitoring module is configured to monitor the DC bus voltage of the motor in real time; a braking current decision module is configured to receive the DC bus voltage and a voltage safety threshold, and dynamically calculate the braking current setpoint; wherein, the calculation logic of the braking current decision module is configured as follows: When the DC bus voltage is lower than the voltage safety threshold, the braking current setpoint is changed to increase in order to accelerate braking; when the DC bus voltage approaches or reaches the voltage safety threshold, the braking current setpoint is changed to decrease in order to constrain the DC bus voltage within the voltage safety threshold. The current application module is configured to apply a corresponding phase current to the motor based on the given braking current value until the motor speed drops to the target braking speed.

[0084] In some embodiments, the system further includes a threshold acquisition module configured to acquire a preset voltage safety threshold.

[0085] It should be noted that the system provided in the above embodiments is only illustrated by the division of the above functional modules. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above. In addition, the system and method embodiments provided in the above embodiments belong to the same concept, and the specific implementation process can be found in the method embodiments, which will not be repeated here.

Claims

1. A method for fast braking of a high voltage brushless electric machine, characterized in that, The method includes: Monitor the DC bus voltage of the motor and obtain the preset voltage safety threshold; The DC bus voltage is used as the controlled feedback quantity, and the voltage safety threshold is used as the control target quantity, which are input to the braking current decision module. Based on the braking current decision module, the braking current setpoint is dynamically calculated according to the real-time deviation between the controlled feedback quantity and the control target quantity; wherein, the dynamic calculation method includes: When the DC bus voltage is lower than the voltage safety threshold, the braking current setpoint is changed to increase in order to accelerate braking; When the DC bus voltage approaches or reaches the voltage safety threshold, the braking current setpoint is changed in a decreasing direction to constrain the DC bus voltage within the voltage safety threshold. Based on the given braking current value, a corresponding phase current is applied to the motor until the motor speed drops to the target braking speed.

2. The rapid braking method for a high-voltage brushless motor according to claim 1, characterized in that, The dynamic solution includes: Calculate the instantaneous deviation between the DC bus voltage and the voltage safety threshold; The instantaneous deviation value is input into the proportional-integral controller, and proportional and integral components are generated through the proportional calculation channel and the integral calculation channel, respectively. The proportional component and the integral component are superimposed to generate an initial control quantity that serves as the given value of the braking current.

3. The rapid braking method for a high-voltage brushless motor according to claim 2, characterized in that, After the dynamic calculation, the initial control quantity is subjected to amplitude limiting processing, which includes: Predefined dynamic current limits that are positively correlated with the current motor speed; The amplitude of the initial control quantity is compared with the dynamic current limit; If the amplitude of the initial control quantity exceeds the dynamic current limit, the dynamic current limit is used as the braking current setpoint; otherwise, the initial control quantity is used as the braking current setpoint.

4. The rapid braking method for a high-voltage brushless motor according to claim 3, characterized in that, The proportional gain coefficient and integral gain coefficient of the proportional-integral controller are adjusted by mapping according to the speed of the motor, wherein the mapping rules include: Under the same voltage deviation, the higher the motor speed, the larger the values ​​of the proportional gain coefficient and the integral gain coefficient, so as to improve the braking current response intensity in the high-speed range of the motor.

5. The rapid braking method for a high-voltage brushless motor according to claim 1, characterized in that, The method for applying a corresponding phase current to the motor includes: The braking current setpoint is used as the outer loop current command and compared with the actual current feedback value obtained by sampling the motor phase current and coordinate transformation to generate a current error signal. The current error signal is input to the inner loop current regulator, which combines the back electromotive force information of the motor to perform feedforward compensation and outputs voltage control commands for each phase winding of the motor. Based on the voltage control command, a braking current is generated and applied to the motor windings.

6. The rapid braking method for a high-voltage brushless motor according to claim 5, characterized in that, The method for generating the voltage control command includes: Based on the motor model and speed, the feedforward voltage component used to counteract the back electromotive force is calculated. The current error signal is subjected to proportional-integral operation to generate a feedback voltage component for eliminating steady-state error; The voltage suppression factor is calculated based on the instantaneous value of the DC bus voltage and its proximity to the voltage safety threshold. By combining the feedforward voltage component, the feedback voltage component, and the voltage suppression factor, voltage control commands for each phase winding of the motor are generated.

7. The rapid braking method for a high-voltage brushless motor according to claim 1, characterized in that, The dynamic solution includes: The rate of change of the DC bus voltage per unit time is calculated. When the rate of change exceeds a preset positive rate threshold, a negative correction is superimposed on the output of the dynamic calculation to suppress the excessively rapid rise of the bus voltage in advance. When the rate of change exceeds a preset negative rate threshold, the negative correction amount is reduced or removed to maintain basic braking performance.

8. A rapid braking system for a high-voltage brushless motor, characterized in that, The system includes: The bus voltage monitoring module is configured to monitor the DC bus voltage of the motor in real time. The braking current decision module is configured to receive the DC bus voltage and voltage safety threshold, and dynamically calculate the braking current setpoint. The solution logic of the braking current decision module is configured as follows: When the DC bus voltage is lower than the voltage safety threshold, the braking current setpoint is changed to increase in order to accelerate braking; When the DC bus voltage approaches or reaches the voltage safety threshold, the braking current setpoint is changed in a decreasing direction to constrain the DC bus voltage within the voltage safety threshold. The current application module is configured to apply a corresponding phase current to the motor based on the given braking current value until the motor speed drops to the target braking speed.

9. An electronic device, characterized in that, It includes a processor, a memory, a user interface, and a network interface. The memory is used to store instructions, the user interface and the network interface are used to communicate with other devices, and the processor is used to execute the instructions stored in the memory to cause the electronic device to perform the method as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a plurality of instructions adapted to be loaded by a processor and executed as described in any one of claims 1-7.

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