Control method of brake-by-wire system and computing device

Abstract

The invention relates to a control method of a brake-by-wire system and computing equipment. The method comprises the following steps: constructing a nonlinear flux linkage observer based on operation parameters of a motor under a static two-phase coordinate system, and resolving the flux linkage observer to obtain an original orthogonal signal corresponding to an electric angle of the motor; processing the original orthogonal signal by using an improved second-order generalized integrator module to obtain a target orthogonal signal; based on the target orthogonal signal and a phase-locked loop, determining a motor estimated rotating speed estimated by the flux observer; determining a first failure condition of the flux linkage observer based on a target orthogonal signal, and determining a second failure condition of a position sensor based on the estimated rotating speed of the motor and the actual rotating speed of the motor detected by the position sensor; and controlling the brake-by-wire system based on the first failure condition and the second failure condition. The method can achieve the verification of the position sensor, and saves the hardware cost.

Description

Technical Field

[0001] The present invention relates to the technical field of automobile wire control, and in particular to a control method and computing equipment for a wire control brake system. Background Art

[0002] In the automobile brake-by-wire system, the servo pump permanent magnet synchronous motor (hereinafter referred to as the motor) is a key pressure-building execution unit, and generally requires a position sensor to provide motor position and speed information. Therefore, in order to prevent the position sensor from failing due to unexpected reasons, it is necessary to calibrate the position sensor to determine whether the entire motor control loop has a permanent fault or a transient fault, resulting in the actual output speed and torque being seriously inconsistent with the expected state. Therefore, based on the calibration of the position sensor, the brake-by-wire system can be controlled in a timely manner to ensure the safety of the vehicle.

[0003] The prior art usually adopts the method of master and slave position sensor inspection, with the speed position information detected by the master sensor as the main factor and the slave sensor used to verify whether the master sensor is normal. However, this method will increase the hardware cost.

[0004] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present application, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0005] In order to overcome the problem that the traditional verification method increases the hardware cost, the present invention provides a control method and a computing device for a brake-by-wire system.

[0006] In a first aspect, in order to solve the above technical problems, the present invention provides a control method of a wire control brake system, comprising:

[0007] A nonlinear flux observer is constructed based on the operating parameters of the motor in a stationary two-phase coordinate system, and the flux observer is solved to obtain an original orthogonal signal corresponding to the electrical angle of the motor;

[0008] Using an improved second-order generalized integrator module to process the original orthogonal signal to obtain a target orthogonal signal;

[0009] Determining the estimated motor speed estimated by the flux observer based on the target quadrature signal and the phase-locked loop;

[0010] Determining a first failure condition of the flux observer based on the target quadrature signal, and determining a second failure condition of the position sensor based on the estimated motor speed and the actual motor speed detected by the position sensor;

[0011] Based on the first failure condition and the second failure condition, a brake-by-wire system is controlled.

[0012] In a second aspect, in order to solve the above-mentioned technical problem, the present invention provides a computing device, including a memory, a processor, and a program stored in the memory and running on the processor, and when the processor executes the program, the steps of a control method of a wire control braking system as described above are implemented.

[0013] The beneficial effects of the present invention are:

[0014] By constructing a nonlinear flux observer in a stationary two-phase coordinate system and solving to obtain the original orthogonal signal corresponding to the electrical angle, the original orthogonal signal is processed by an improved second-order generalized integrator module to eliminate the noise and DC bias of the original orthogonal signal, thereby obtaining the target orthogonal signal to verify the effectiveness of the flux observer and determine the first failure condition of the flux observer. The target orthogonal signal is then processed by a phase-locked loop to obtain the motor estimated speed estimated by the flux observer. In this way, by determining the first failure condition of the flux observer to ensure the accuracy of the motor estimated speed of the flux observer, it is convenient to determine the second failure condition of the position sensor through the motor estimated speed and the actual motor speed to realize the verification of the position sensor, saving hardware costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A flow chart of a control method of a wire control brake system provided by the present invention;

[0016] Figure 2 A schematic diagram of the structure of an improved second-order generalized integrator provided by the present invention;

[0017] Figure 3 A schematic diagram of a confidence interval and a population mean distribution provided by the present invention;

[0018] Figure 4 An embodiment of a control method for a wire control brake system provided by the present invention. DETAILED DESCRIPTION

[0019] The principles and features of the present invention are described below. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0020] The principles and features of the present invention are described below. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0021] A control method and a computing device for a brake-by-wire system according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

[0022] like Figure 1 As shown, a control method of a brake-by-wire system provided by an embodiment of the present disclosure includes:

[0023] Step S101 : constructing a nonlinear flux observer based on the operating parameters of the motor in a stationary two-phase coordinate system, and solving the flux observer to obtain an original orthogonal signal corresponding to the electrical angle of the motor.

[0024] Step S102: Process the original orthogonal signal using an improved second-order generalized integrator module to obtain a target orthogonal signal.

[0025] Step S103, determining the estimated motor speed estimated by the flux observer based on the target quadrature signal and the phase-locked loop.

[0026] The phase-locked loop is a PLL. The phase-locked loop also outputs the estimated rotor position estimated by the flux observer. For example, the estimated rotor position can be obtained by integrating the estimated motor speed.

[0027] Step S104 , determining a first failure condition of the flux observer based on the target quadrature signal, and determining a second failure condition of the position sensor based on the estimated motor speed and the actual motor speed detected by the position sensor.

[0028] It is understandable that the position sensor also detects the actual position of the rotor. Therefore, the second failure condition of the position sensor can also be determined based on the estimated rotor position and the actual rotor position. Since the rotor position involves phase information, the calculation is more complicated. Therefore, this embodiment uses the estimated motor speed and the actual motor speed to determine the second failure condition of the position sensor, which is more efficient.

[0029] Step S105 , controlling the brake-by-wire system based on the first failure condition and the second failure condition.

[0030] A control method for a brake-by-wire system provided by an embodiment of the present disclosure is adopted. A nonlinear flux observer in a stationary two-phase coordinate system is constructed, and the original orthogonal signal corresponding to the electrical angle is obtained by solving the solution. The original orthogonal signal is then processed by an improved second-order generalized integrator module to eliminate the noise and DC bias of the original orthogonal signal, thereby obtaining a target orthogonal signal to verify the effectiveness of the flux observer, thereby determining the first failure condition of the flux observer. The target orthogonal signal is then processed by a phase-locked loop to obtain the motor estimated speed estimated by the flux observer. In this way, by determining the first failure condition of the flux observer to ensure the accuracy of the motor estimated speed of the flux observer, it is convenient to determine the second failure condition of the position sensor through the motor estimated speed and the motor actual speed to realize the verification of the position sensor, thereby saving hardware costs.

[0031] In addition, compared with the traditional method of using different ADC groups for dual-channel sampling of the position sensor to perform two sets of sampling signal verification, this embodiment can achieve complete decoupling of the two sets of speed and angle signals. Compared with the traditional method of feeding back the terminal voltage feedback pin of the pre-driver chip to the main MCU and estimating the motor speed position information through the terminal voltage, this embodiment reduces the sampling resource consumption and PCB layout difficulty, does not need to add hardware, and reduces hardware costs.

[0032] Preferably, a nonlinear flux observer is constructed based on the operating parameters of the motor in a stationary two-phase coordinate system, including: obtaining the operating parameters of the motor in the stationary two-phase coordinate system; wherein the operating parameters include stator resistance, stator inductance, angular velocity, permanent magnet flux, rotor position, α-axis voltage, β-axis voltage, α-axis current and β-axis current; determining a voltage equation and a flux equation in the stationary two-phase coordinate system based on stator resistance, stator inductance, angular velocity, permanent magnet flux, rotor position, α-axis voltage, β-axis voltage, α-axis current and β-axis current; defining the flux in the flux equation as a state variable of the flux observer, and determining the output variable of the flux observer based on the flux equation and the voltage equation; and constructing a nonlinear flux observer based on the state variable of the flux observer and the output variable of the flux observer.

[0033] In this way, through the feedback current, output voltage, and the relationship between the flux and back electromotive force in the voltage equation of the motor, the flux is used as a state variable, and a back electromotive force equation with the flux as the error as feedback compensation is established. This allows the established nonlinear flux observer to accurately estimate and observe the motor state without setting up additional sensors, so as to reconstruct the motor speed, position, direction, etc.

[0034] Specifically, the voltage equation in the stationary two-phase coordinate system is:

[0035]

[0036] Among them, u α is the α-axis voltage, u β is the β-axis voltage, i α is the α-axis current, i β is the β-axis current, R s is the stator resistance, L s is the stator inductance, ω e is the angular velocity, ψ f is the permanent magnet flux and θ is the rotor position.

[0037] Specifically, the magnetic flux equation is:

[0038]

[0039] Specifically, the state variable χ of the flux observer is:

[0040]

[0041] Specifically, the output variable of the flux observer is determined based on the flux equation and the voltage equation, including: taking the derivative of the flux equation and combining it with the voltage equation to obtain the output variable equation. The output variable equation is defined as the output variable of the flux observer. Among them, the output variable equation is:

[0042]

[0043] Then, the output variable y is:

[0044]

[0045] Specifically, the nonlinear flux observer is:

[0046]

[0047] Among them, γ is strictly greater than 0 and is the observer gain. is the estimated value of the state variable, is the first-order derivative of the estimated value of the state variable, η(x) is the true value of the rotor flux, is the estimated value of rotor flux

[0048] Specifically, the original orthogonal signal is:

[0049]

[0050] Preferably, the voltage equation and the flux equation in the stationary two-phase coordinate system are determined based on the stator resistance, stator inductance, angular velocity, permanent magnet flux, rotor position, α-axis voltage, β-axis voltage, α-axis current and β-axis current, including: obtaining the D-axis compensation voltage; based on the D-axis compensation voltage, performing voltage compensation on the α-axis voltage and the β-axis voltage to obtain the target α-axis voltage and the target β-axis voltage; determining the voltage equation and the flux equation in the stationary two-phase coordinate system based on the stator resistance, stator inductance, angular velocity, permanent magnet flux, rotor position, target α-axis voltage, target β-axis voltage, α-axis current and β-axis current.

[0051] Because parameter perturbations, load disturbances, wave delays, etc. will cause the input to the flux observer u α and u βThe signal is distorted, and the THD (harmonic distortion) value increases, thus affecting the accuracy of the flux observer. Among them, harmonic distortion refers to the harmonic components that the output signal has more than the input signal. In this way, the α-axis voltage and the β-axis voltage are compensated by the D-axis compensation voltage. The D-axis voltage only increases the signal amplitude and does not change the signal phase. Therefore, the sum signal after amplitude amplification can be obtained, and the THD is suppressed. This can improve the angle tracking accuracy and robustness of the flux observer.

[0052] Specifically, obtaining the D-axis compensation voltage includes: obtaining the motor estimated speed at a previous moment by the flux observer, and determining the D-axis compensation voltage at a current moment by looking up a table based on the motor estimated speed at a previous moment.

[0053] Specifically, based on the D-axis compensation voltage, voltage compensation is performed on the α-axis voltage and the β-axis voltage to obtain the target α-axis voltage and the target β-axis voltage, including: transforming the α-axis voltage and the β-axis voltage to the synchronous rotating coordinate system dq axis to obtain the transformed voltage. Injecting the D-axis compensation voltage into the transformed voltage to obtain the compensated voltage. Inversely transforming the compensated voltage to the stationary two-phase coordinate system to obtain the target α-axis voltage and the target β-axis voltage.

[0054] Preferably, the improved second-order generalized integrator module includes a first integrator and a second integrator, and the original orthogonal signal includes an original sine signal and an original cosine signal. The original orthogonal signal is processed by the improved second-order generalized integrator module to obtain the target orthogonal signal, including: using the first integrator to respectively determine the in-phase signal corresponding to the original sine signal as the first target sine signal, and determining the delayed signal corresponding to the original sine signal as the first target cosine signal; using the second integrator to respectively determine the in-phase signal corresponding to the original cosine signal as the second target sine signal, and determining the delayed signal corresponding to the original cosine signal as the second target cosine signal; the first target sine signal, the second target sine signal, the first target cosine signal and the second target cosine signal are all used as target orthogonal signals. Among them, the first integrator represents the first improved second-order generalized integrator, and the second integrator represents the second improved second-order generalized integrator.

[0055] Factors such as motor parameter perturbation cause the original orthogonal signal containing the motor electrical angle to have noise and DC offset. In this way, the original orthogonal signal is processed by the first integrator and the second integrator respectively to increase the bandwidth and eliminate the original orthogonal signal noise and DC offset and verify the validity of the original orthogonal signal, thereby optimizing the original orthogonal signal, thereby improving the validity of the flux observer, so as to determine the first failure condition of the flux observer.

[0056] Specific, combined Figure 2 As shown, Figure 2An improved second-order generalized integrator (ISOGI) is provided. The improved second-order generalized integrator includes a first transfer function Φ0(s) and a second transfer function Φ 90 (s). The first transfer function Φ0(s) is used to increase the bandwidth and eliminate the original orthogonal signal noise and DC offset, and the second transfer function Φ 90 (s) is used to verify the validity of the original orthogonal signal. The first transfer function Φ0(s) and the second transfer function Φ 90 (s) are as follows:

[0057]

[0058] Among them, s is the Laplace complex variable, k is the system gain, ω is the angular velocity, and τ is the time constant.

[0059] In some embodiments, the original quadrature signal includes The original sine signal is sinθ′, and the original cosine signal is cosθ′.

[0060] Specifically, the first integrator is used to determine the in-phase signal corresponding to the original sinusoidal signal as the first target sinusoidal signal, and the delayed signal corresponding to the original sinusoidal signal as the first target cosine signal, including: the first integrator uses the first transfer function Φ0(s) to determine the in-phase signal corresponding to the original sinusoidal signal as the first target sinusoidal signal The first integrator uses the second transfer function Φ 90 (s) Determine the delayed signal corresponding to the original sine signal as the first target cosine signal

[0061] Specifically, the second integrator is used to respectively determine the in-phase signal corresponding to the original cosine signal as the second target sinusoidal signal, and to determine the delayed signal corresponding to the original cosine signal as the second target cosine signal, including: the second integrator uses the first transfer function Φ0(s) to determine the in-phase signal corresponding to the original cosine signal as the second target sinusoidal signal The second integrator uses the second transfer function Φ 90 (s) Determine the delayed signal corresponding to the original cosine signal as the second target cosine signal in, and 90 degrees difference.

[0062] In this way, the original sine signal is processed by the first transfer function of the first integrator, and the original cosine signal is processed by the first transfer function of the second integrator, so that the noise of the original quadrature signal can be suppressed and the DC bias can be eliminated. The original sine signal is processed by the second transfer function of the first integrator, and the original cosine signal is processed by the second transfer function of the second integrator, so that the validity of the original quadrature signal can be verified. Thus, the original quadrature signal is optimized by the improved second-order generalized integrator to verify the validity of the flux observer.

[0063] Preferably, determining a first failure condition of the flux observer based on the target orthogonal signal includes: determining a first verification result based on a first target sine signal, a second target sine signal, a first target cosine signal, and a second target cosine signal; obtaining a first threshold condition; if the first verification result satisfies the first threshold condition, the first failure condition of the flux observer is not failed, and if the first verification result does not satisfy the first threshold condition, the first failure condition of the flux observer is failed.

[0064] Since the stability of the flux observer cannot fully characterize the accuracy and performance of the flux observer estimation, the first target sine signal, the second target sine signal, the first target cosine signal and the second target cosine signal are used to determine the first verification result, and then it is determined whether the first verification result meets the first threshold condition, so that the effectiveness of the flux observer can be verified more accurately, so as to ensure the estimation accuracy of the flux observer.

[0065] Specifically, determining the first verification result based on the first target sine signal, the second target sine signal, the first target cosine signal, and the second target cosine signal includes: determining the first verification result by the following formula based on the first target sine signal, the second target sine signal, the first target cosine signal, and the second target cosine signal:

[0066]

[0067] in, is the first target sinusoidal signal, is the second target sinusoidal signal, is the first target cosine signal, is the second target cosine signal.

[0068] If the flux observer estimates accurately, then At this time, the first verification result will not jump due to the forward and reverse rotation of the motor, and will not be affected by the original signal noise and DC bias of the flux observer, so the flux observer is judged to be effective. When the first threshold condition is met, the first failure condition of the flux observer is not failed; when When the first threshold condition is not met, the first failure condition of the flux observer is failure.

[0069] Preferably, obtaining the first threshold condition includes: selecting a plurality of different operating conditions as target operating conditions; for each target operating condition, obtaining a plurality of second verification results according to a preset frequency when the motor is running; based on the obtained second verification results, determining the variance of the first population using t distribution; and determining the first threshold condition using the first preset confidence and the variance of the first population. The second verification results represent the obtained variance of the first population when the vehicle is driving under different target operating conditions.

[0070] It is understandable that the second verification result and the first verification result are both verification results. Specifically, the first verification result is the verification result obtained in real time when the car is actually driving. The second verification result is the verification result obtained when the car is driving under different target conditions. In other words, the first verification result and the second verification result are the verification results obtained in different scenarios.

[0071] Since the motor will operate normally under a variety of working conditions, its parameters will have certain differences. And according to the central limit theorem, the sample mean of any population is usually normally distributed around the actual mean of the population, so the failure threshold determination method based on the frequency confidence interval can determine a reasonable first threshold condition. In this way, multiple second verification results of the motor when it is running under each target working condition are obtained according to the preset frequency and used as sample data. Since the mean of the population data is unknown, the variance of the first population is described by the t distribution, so that the first threshold condition is determined using the first preset confidence and the determined variance of the first population, so that the obtained first threshold condition is closer to the first verification result when the motor is operating normally. Thereby, the first failure condition of the flux observer can be determined more accurately.

[0072] It can be understood that obtaining multiple second verification results according to a preset frequency when the motor is running means obtaining a second verification result every preset time when the motor is running. The population corresponds to the sample. In this embodiment, the first population refers to the population data corresponding to the second verification result, that is, multiple second verification results are selected as sample data from each second verification result of the population.

[0073] Specifically, based on all the second verification results, the variance of the first population is determined using t distribution, including: calculating the sample mean of all the second verification results And calculate the corresponding sample standard deviation as Based on the corresponding sample standard deviation, the variance of the first population described by t distribution is in, is the mean of all second verification results, X iis the i-th second verification result, n is the number of second verification results, S is the sample standard deviation, t is the variance of the first population, and μ is the mean of the first population.

[0074] Specifically, using the first preset confidence and the variance of the first population to determine the first threshold condition includes: using the first preset confidence to construct a first confidence interval of the first population mean, using the confidence lower limit of the first confidence interval as the lower threshold of the first threshold condition, and using the confidence upper limit of the first confidence interval as the upper threshold of the first threshold condition. The calculation formula is as follows:

[0075]

[0076]

[0077] Where α is the significance level, and (1-α) is the first preset reliability. Represents the right tail area of ​​a t distribution with n-1 degrees of freedom The corresponding t value is, Represents the confidence width, which describes the distribution interval of the acceptance domain. is the lower confidence limit, is the upper confidence limit.

[0078] In this embodiment, when the first verification result is greater than and less than When the first verification result is less than or equal to Or, greater than or equal to When , the first failure condition of the flux observer is failure.

[0079] In some embodiments, considering the differences in working conditions at various points in the motor TN (T represents torque, N represents speed) curve, 30 working condition points of the TN curve are selected as target working conditions. Under each target working condition, a second verification result is recorded every 1ms. Record 100ms, a total of 3000 second verification result data as sample data. Let the significance level α be 0.05, the confidence level be 0.95, then 95% of the confidence intervals contain the population mean. Then its upper and lower confidence limits are the thresholds for rationality judgment, that is, the upper and lower thresholds of the first threshold condition.

[0080] For ease of understanding, combined Figure 3 As shown, Figure 3 A diagram of the confidence interval and the distribution of the population mean is provided. Figure 3 In , assuming 20 tests are performed, 95% of the confidence intervals for the test data should include the population mean μ. For example, Figure 3In a, the confidence intervals of the test data include the population mean μ 19 times, and only once does not include the population mean μ. Figure 3 b and Figure 3 c are schematic diagrams showing that the confidence interval includes the population mean μ. Figure 3 d is a schematic diagram showing that the confidence interval does not include the population mean μ. If n tests are conducted, there must be n*95% of the confidence intervals of the tests that cross the population true μ horizontal line, which shows that the 95% confidence level is equivalent to the 95% acceptance domain. Therefore, the confidence interval calculated by the t distribution in a single test can be used to describe the distribution of the acceptance domain of the population, so as to provide a basis for determining the rationality threshold.

[0081] Preferably, determining the estimated motor speed estimated by the flux observer based on the target orthogonal signal and the phase-locked loop includes: inputting the first target sinusoidal signal and the second target sinusoidal signal into the phase-locked loop to determine the estimated motor speed estimated by the flux observer.

[0082] The original sine signal is processed by the first transfer function of the first integrator, and the original cosine signal is processed by the first transfer function of the second integrator, so that the noise of the original quadrature signal can be suppressed and the DC bias can be eliminated. In this way, the first target sine signal processed by the first transfer function of the first integrator and the second target sine signal processed by the first transfer function of the second integrator are input into the phase-locked loop, so that a more accurate motor estimated speed estimated by the flux observer can be obtained.

[0083] Preferably, based on the estimated motor speed and the actual motor speed detected by the position sensor, the second failure condition of the position sensor is determined, including: calculating the difference between the actual motor speed and the estimated motor speed to determine the first speed difference; obtaining the second threshold condition; if the first speed difference meets the second threshold condition, the second failure condition of the position sensor is not failed, and if the first speed difference does not meet the second threshold condition, the second failure condition of the position sensor is failed.

[0084] In this way, the difference between the actual motor speed and the estimated motor speed is evaluated through the second threshold condition, that is, the speed error is determined, so as to determine whether the position sensor is faulty, so as to determine the second failure condition of the position sensor.

[0085] Preferably, obtaining the second threshold condition includes: selecting a plurality of different operating conditions as target operating conditions; for each target operating condition, obtaining a plurality of second speed difference values ​​according to a preset frequency when the motor is running; determining the variance of the second population using t distribution based on the obtained second speed difference values; and determining the second threshold condition using a second preset confidence and the variance of the second population. The second speed difference value represents the difference between the actual speed of the motor and the estimated speed of the motor when the vehicle is driving under different target operating conditions.

[0086] Since the motor will operate normally under a variety of working conditions, its parameters will have certain differences. And according to the central limit theorem, the sample mean of any population is usually normally distributed around the actual mean of the population, so the failure threshold determination method based on the frequency confidence interval can determine a reasonable second threshold condition. In this way, multiple second speed difference values ​​when the motor is running under each target working condition are obtained according to the preset frequency and used as sample data. Since the mean of the population data is unknown, the variance of the second population is described by t distribution, so that the second threshold condition is determined using the second preset confidence and the determined variance of the second population, so that the obtained second threshold condition is closer to the second speed difference when the motor is operating normally. Thereby, the second failure condition of the position sensor can be determined more accurately.

[0087] It can be understood that obtaining multiple second speed difference values ​​according to a preset frequency when the motor is running means obtaining a second speed difference value every preset time when the motor is running. The population corresponds to the sample. In this embodiment, the second population refers to the population data corresponding to the second speed difference value, that is, multiple second speed difference values ​​are selected as sample data from each second speed difference value of the population.

[0088] Specifically, based on all the second speed differences, the variance of the second population is determined using t distribution, including: calculating the sample means of all the second speed differences and the corresponding sample standard deviations. Based on the corresponding sample standard deviations, the variance of the second population is described using t distribution.

[0089] Specifically, the second threshold condition is determined using the second preset confidence level and the variance of the second population, including: using the second preset confidence level to construct a second confidence interval for the second population mean, using the lower confidence limit of the second confidence interval as the lower threshold of the second threshold condition, and using the upper confidence limit of the second confidence interval as the upper threshold of the second threshold condition.

[0090] Preferably, the brake-by-wire system is controlled based on the first failure condition and the second failure condition, including: performing a table lookup operation in a preset data table using the first failure condition and the second failure condition to find out an alternative safety state corresponding to the first failure condition and the second failure condition as a target safety state; the preset data table stores a correspondence between the first failure condition and the second failure condition and the safety state; and controlling the brake-by-wire system based on the target safety state.

[0091] Since the first failure condition represents the failure condition of the flux observer, and the second failure condition of the position sensor is related to the estimated motor speed estimated by the flux observer, the first failure condition and the second failure condition are used together to determine the safety state of the vehicle, so that the obtained safety state is more reasonable. When the wire control brake system is controlled by using a more reasonable safety state, the safety performance of the vehicle can be improved.

[0092] In some embodiments, the preset data table is as follows:

[0093]

[0094]

[0095] Among them, safety state three is the redundant control mode of the permanent magnet synchronous motor position sensor failure of the wire control brake system.

[0096] For ease of understanding, combined Figure 4 As shown. In this embodiment, the output voltage is the α-axis voltage and β-axis voltage of the motor, and the compensation voltage is the D-axis compensation voltage. The compensation voltage is used to perform D-axis voltage compensation on the output voltage to obtain the compensated voltage. A flux observer is constructed using the compensated voltage, the feedback current (the α-axis current and the β-axis current of the motor) and the remaining operating parameters of the motor (not shown) to obtain the original orthogonal signal, that is, the original sinusoidal signal sinθ′ and the original cosine signal cosθ′. The original sinusoidal signal sinθ′ is input into the first integrator (that is, the first improved second-order generalized integrator, referred to as the first ISOGI), and the first ISOGI uses the first transfer function to process the original sinusoidal signal sinθ′ to obtain the first target sinusoidal signal The first ISOGI uses the second transfer function to process the original sine signal sinθ′ to obtain the first target cosine signal The original cosine signal cosθ′ is input to the second integrator (i.e., the second improved second-order generalized integrator, referred to as the second ISOGI), and the second ISOGI processes the original cosine signal cosθ′ using the first transfer function to obtain the second target sine signal The second ISOGI uses the second transfer function to process the original cosine signal cosθ′ to obtain the second target cosine signal Using the first target sinusoidal signal Second target sinusoidal signal First target cosine signal and the second target cosine signal Calculate the first verification result The first threshold condition is obtained based on the confidence interval determination failure threshold method, and the first failure condition of the flux observer is verified based on the first verification result and the first threshold condition. and the second target sinusoidal signal Input into the phase-locked loop (PLL) to obtain the estimated motor speed estimated by the flux observer. Obtain the actual motor speed detected by the position sensor. Subtract the actual motor speed from the estimated motor speed to obtain a first difference. Determine the failure threshold method based on the confidence interval to obtain the second threshold condition, and verify the second failure condition of the position sensor based on the first difference and the second threshold condition. Determine the safety state of the brake-by-wire system based on the first failure condition and the second failure condition. This embodiment shows four safety states, see the preset data table above for details.

[0097] A computing device according to an embodiment of the present invention includes a memory, a processor, and a program stored in the memory and running on the processor. When the processor executes the program, part or all of the steps of the control method of the above-mentioned wire control brake system are implemented.

[0098] Among them, the computing device can be a computer, and correspondingly, its program is computer software. The above-mentioned parameters and steps in a computing device of the present invention can refer to the parameters and steps in an embodiment of a control method of a wire control braking system mentioned above, and will not be repeated here.

[0099] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0100] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A control method for a brake-by-wire system, characterized in that: include: A nonlinear flux observer is constructed based on the operating parameters of the motor in a stationary two-phase coordinate system, and the flux observer is solved to obtain an original orthogonal signal corresponding to the electrical angle of the motor; Using an improved second-order generalized integrator module to process the original orthogonal signal to obtain a target orthogonal signal; Determining the estimated motor speed estimated by the flux observer based on the target quadrature signal and the phase-locked loop; Determining a first failure condition of the flux observer based on the target quadrature signal, and determining a second failure condition of the position sensor based on the estimated motor speed and the actual motor speed detected by the position sensor; Based on the first failure condition and the second failure condition, a brake-by-wire system is controlled.

2. The method according to claim 1, characterized in that The nonlinear flux observer is constructed based on the operating parameters of the motor in a stationary two-phase coordinate system, including: Obtaining the operating parameters of the motor in a stationary two-phase coordinate system; wherein the operating parameters include stator resistance, stator inductance, angular velocity, permanent magnet flux, rotor position, α-axis voltage, β-axis voltage, α-axis current and β-axis current; Determine a voltage equation and a flux equation in a stationary two-phase coordinate system based on the stator resistance, the stator inductance, the angular velocity, the permanent magnet flux, the rotor position, the α-axis voltage, the β-axis voltage, the α-axis current, and the β-axis current; defining the flux in the flux equation as a state variable of the flux observer, and determining an output variable of the flux observer based on the flux equation and the voltage equation; A nonlinear flux observer is constructed based on the state variable of the flux observer and the output variable of the flux observer.

3. The method according to claim 2, characterized in that The step of determining a voltage equation and a flux equation in a stationary two-phase coordinate system based on the stator resistance, the stator inductance, the angular velocity, the permanent magnet flux, the estimated rotor position, the α-axis voltage, the β-axis voltage, the α-axis current, and the β-axis current comprises: Get the D-axis compensation voltage; Based on the D-axis compensation voltage, voltage compensation is performed on the α-axis voltage and the β-axis voltage to obtain a target α-axis voltage and a target β-axis voltage; A voltage equation and a flux equation in a stationary two-phase coordinate system are determined based on the stator resistance, the stator inductance, the angular velocity, the permanent magnet flux, the rotor position, the target α-axis voltage, the target β-axis voltage, the α-axis current and the β-axis current.

4. The method according to claim 1, characterized in that: The improved second-order generalized integrator module includes a first integrator and a second integrator, and the original orthogonal signal includes an original sine signal and an original cosine signal; The method of processing the original orthogonal signal by using an improved second-order generalized integrator module to obtain a target orthogonal signal includes: Using a first integrator, respectively determining an in-phase signal corresponding to the original sinusoidal signal as a first target sinusoidal signal, and determining a delayed signal corresponding to the original sinusoidal signal as a first target cosine signal; Using a second integrator, respectively determining an in-phase signal corresponding to the original cosine signal as a second target sine signal, and determining a delayed signal corresponding to the original cosine signal as a second target cosine signal; The first target sine signal, the second target sine signal, the first target cosine signal and the second target cosine signal are all used as target orthogonal signals.

5. The method according to claim 4, characterized in that The determining a first failure condition of the flux observer based on the target orthogonal signal comprises: Determining a first verification result based on the first target sine signal, the second target sine signal, the first target cosine signal, and the second target cosine signal; Obtaining a first threshold condition; If the first verification result satisfies the first threshold condition, the first failure condition of the flux observer is not failed; if the first verification result does not satisfy the first threshold condition, the first failure condition of the flux observer is failed.

6. The method according to claim 5, characterized in that The obtaining of the first threshold condition includes: Select multiple different working conditions as target working conditions; For each target operating condition, a plurality of second verification results are obtained according to a preset frequency when the motor is running; Based on the obtained second verification result, determining the variance of the first population using t distribution; A first threshold condition is determined using a first preset confidence and the variance of the first population.

7. The method according to claim 4, characterized in that The step of determining the estimated motor speed estimated by the flux observer based on the target quadrature signal and the phase-locked loop comprises: The first target sinusoidal signal and the second target sinusoidal signal are input into a phase-locked loop to determine the estimated motor speed estimated by the flux observer.

8. The method according to claim 1, characterized in that The determining a second failure condition of the position sensor based on the estimated motor speed and the actual motor speed detected by the position sensor comprises: Calculating a difference between the actual speed of the motor and the estimated speed of the motor to determine a first speed difference; obtaining a second threshold condition; If the first rotation speed difference meets the second threshold condition, the second failure condition of the position sensor is not failed; if the first rotation speed difference does not meet the second threshold condition, the second failure condition of the position sensor is failed.

9. The method according to any one of claims 1 to 8, characterized in that: The controlling the brake-by-wire system based on the first failure condition and the second failure condition includes: Performing a table lookup operation in a preset data table using the first failure condition and the second failure condition to find out an alternative safety state corresponding to both the first failure condition and the second failure condition as a target safety state; the preset data table stores a corresponding relationship between both the first failure condition and the second failure condition and the safety state; Based on the target safety state, the brake-by-wire system is controlled.

10. A computing device comprising a memory, a processor, and a program stored in the memory and running on the processor, characterized in that: When the processor executes the program, the steps of the control method of a wire control brake system as claimed in any one of claims 1 to 9 are implemented.

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