An active damping control method for an electrically driven vehicle

Abstract

The application discloses a kind of active damping control methods of electric drive car, comprising the following steps: S1, receiving and processing input signal, the low-pass filter of high frequency is carried out to motor speed signal, and N cycle average filter is carried out to request torque;S2, after motor speed signal is passed through second-order low-pass filter series second-order high-pass filter, the fluctuation amount in motor speed is calculated;S3, according to the two-dimensional table of filtered motor speed and motor request torque, output corresponding PI control parameter;S4, the fluctuation amount in speed in S2 is carried out PI control calculation by formula Torque out =K p ·ΔSpd+K i ·(ΔSpd‑ΔSpd last ) is calculated, and output torque is obtained after the upper and lower limit restriction of calculated torque.The active damping compensation torque calculated according to the fluctuation characteristics of motor speed signal is attached to torque request command to suppress motor speed fluctuation and even vehicle body shaking, and the driving comfort of whole vehicle is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric drive motor control, and particularly relates to an active damping control method for electric drive vehicles. BACKGROUND

[0002] The transmission system of an electric vehicle is relatively simple and does not have components such as clutches and hydraulic torque converters, and the transmission system is rigidly connected and presents an under-damped characteristic. At the same time, the torque response of a motor is 10-50 times faster than that of an engine, and in the process of accelerating and starting of a pure electric vehicle, the sudden step torque generated by the motor will excite the torsional vibration of the transmission system, and the low-frequency vibration frequency is in the range of 2-12 Hz. Due to the "under-damped" dynamic characteristics of the electric drive transmission system, in some specific transient transition conditions, the pure electric vehicle is prone to transmission system impact noise or vehicle shaking problems, which seriously reduces the driving comfort of the vehicle, and therefore it is particularly important to study the control method of active anti-shake for improving the driving quality of the pure electric vehicle. SUMMARY

[0003] In view of the deficiencies of the prior art, the present application provides an active damping control method for electric drive vehicles, which adds the active damping compensation torque calculated according to the fluctuation characteristics of the motor speed signal to the torque request command to suppress the motor speed fluctuation and even the vehicle body shaking, and improves the driving comfort of the vehicle.

[0004] The technical solutions solving the above technical problems are as follows:

[0005] An active damping control method for electric drive vehicles, comprising the following steps:

[0006] S1, receiving and processing input signals, performing high-frequency low-pass filtering on the motor speed signal, and performing N-cycle average filtering on the requested torque;

[0007] S2, calculating the speed fluctuation in the motor speed after the motor speed signal is filtered through a second-order low-pass filter in series with a second-order high-pass filter;

[0008] S3, looking up a two-dimensional table according to the filtered motor speed and the motor requested torque to output corresponding PI control parameters;

[0009] S4, performing PI control calculation on the speed fluctuation in S2 through the formula Torque out =K p ·ΔSpd+K i ·(ΔSpd-ΔSpd last ), limiting the calculated torque through upper and lower limits to obtain an output torque;

[0010] In the above formula, ΔSpd is the speed fluctuation, and ΔSpd lastK p , K i is a PI control parameter, Torque out is a calculated torque;

[0011] S5, the motor speed after low-pass filtering is compared with the speed threshold value to determine whether the speed condition flag is triggered, and the active damping enable is sent by the vehicle at the same time, the speed condition flag and the active damping enable are triggered at the same time, and the active damping trigger flag is obtained;

[0012] S6, the active damping flag is triggered and the opening slope is set, and the exit slope is set when exiting, and the active damping torque coefficient is calculated;

[0013] S7, the output torque in S4 is multiplied by the active damping torque coefficient in S6 to obtain the active damping compensation torque;

[0014] S8, the requested torque is compared with the torque threshold value to determine whether the active damping compensation torque in S7 or 0 is output.

[0015] Further, the number N of cycles in S1 is an empirical value obtained according to driving experience and data analysis in vehicle testing.

[0016] Further, in S2, the motor speed signal is filtered through a second-order low-pass filter in series with a second-order high-pass filter, and the speed fluctuation with consistent frequency and small phase shift in the motor speed signal is calculated.

[0017] Further, in S3, a two-dimensional table is searched according to the filtered motor speed and the motor requested torque to distinguish the specific requirements of different working conditions and interpolate to obtain the PI control parameter.

[0018] Further, in S4, the speed fluctuation and the difference between the current cycle fluctuation are PI calculated to close-loop control the motor speed fluctuation, and the output torque is obtained.

[0019] Further, in S7, the output torque is multiplied by the active damping torque coefficient in S6 to obtain the active damping compensation torque, that is, the following formula is satisfied: Torque ADC = Torque out * TorqueCoeff, wherein Torque ADC is the active damping compensation torque, and TorqueCoeff is the torque coefficient.

[0020] The beneficial effects of the present application are:

[0021] The application utilizes the characteristics of quick response of motor torque, adopts the motor as the actuator of the active control system, can directly integrate the active damping control method into the motor controller, calculates the active damping compensation torque by accurately extracting the motor speed fluctuation under the condition of no change and no increase of system cost, realizes the active damping control to inhibit the motor speed fluctuation and even the body shaking condition, and improves the driving comfort of the whole vehicle. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The flow chart of the active damping control method of the electric drive vehicle. DETAILED DESCRIPTION

[0023] The application will be further described below in combination with the drawings and specific embodiments.

[0024] First of all, it needs to be pointed out that, in order to make the purpose, technical scheme and advantages of the application clearer, the technical scheme in the embodiments of the application will be described in more detail below in combination with the drawings of the embodiments of the application. The described embodiments are a part of the embodiments of the application, rather than all the embodiments. The embodiments described below by referring to the drawings are exemplary and are intended to explain the application, and cannot be simply understood as the limitation of the application. Based on the embodiments of the application, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the application.

[0025] As shown in the drawing, an active damping control method of an electric drive vehicle comprises the following steps: Figure 1

[0026] S1, receiving and processing input signals, performing high-frequency low-pass filtering of motor speed signals and N-cycle average filtering of requested torque (average filtering is generally 5 to 10 cycles, which can be calibrated according to the calibration experience combined with the driving effect);

[0027] S2, calculating the speed fluctuation in the motor speed after the motor speed signal is filtered through a second-order low-pass filter in series with a second-order high-pass filter;

[0028] The continuous domain transfer function of the second-order low-pass and high-pass filter is:

[0029] The continuous domain transfer function is converted to the transfer function of the discrete system: According to the transfer function of the discrete system, a model is built, and five calibration parameters N2, N1, N0, D1 and D0 are used as filter calibration parameters (which need to be calibrated according to the calibration experience combined with the driving feeling), and the five parameters can be changed by changing the filter frequency.

[0030] ​S3, according to the filtered motor speed and the motor request torque, a two-dimensional table is searched to output corresponding PI control parameters (as shown in the following table):

[0031]

[0032] The speed / torque-PI parameter two-dimensional table needs to be calibrated according to the experience and driving feeling.

[0033] MotSpd is a 1*5 speed table, ReqTrq is a 1*5 torque table, and KpTable is a 5*5 parameter table.

[0034] S4, the speed fluctuation in S2 is calculated by PI control formula, and the calculated torque is limited by upper and lower limits to obtain the output torque;

[0035] In the above formula, ΔSpd is the speed fluctuation, ΔSpd last is the speed fluctuation of the previous cycle.

[0036] K p and K i are PI control parameters, and Torque out is the calculated torque.

[0037] S5, the low-pass filtered motor speed is compared with the speed threshold to determine whether the speed condition flag is triggered, and the vehicle sends the active damping enablement at the same time. The speed condition flag and the active damping enablement are triggered at the same time to obtain the active damping trigger flag.

[0038] S6, the active damping flag is triggered and the opening slope is set, the torque coefficient is increased from 0 to 1, the exit slope is set when the period is 1s, the torque coefficient is decreased from 1 to 0, and the active damping torque coefficient is calculated at the same time with a period of 2s;

[0039] S7, the output torque in S4 is multiplied by the active damping torque coefficient in S6 to obtain the active damping compensation torque;

[0040] Specifically, as shown in the formula: Torque ADC = Torque out * TorqueCoeff, wherein Torque ADC is the active damping compensation torque, and TorqueCoeff is the torque coefficient.

[0041] S8, according to the request torque and the torque threshold, it is determined that the active damping compensation torque in S7 or 0 is output.

[0042] Preferably, the number N of cycles in S1 is an empirical value obtained according to driving feeling and data analysis in vehicle test.

[0043] Preferably, in S2, the motor speed signal is filtered through a second-order low-pass filter in series with a second-order high-pass filter, and the frequency-consistent and small phase-shifted speed fluctuation amount in the motor speed signal is calculated.

[0044] Preferably, in S3, the PI control parameters are obtained by interpolation according to the filtered motor speed and the motor request torque and a two-dimensional table.

[0045] Preferably, in S4, the speed fluctuation amount and the difference between the current period fluctuation amount are subjected to PI calculation, the motor speed fluctuation amount is closed-loop controlled, and the output torque is obtained.

[0046] Preferably, in S7, the output torque is multiplied by the active damping torque coefficient in S6 to obtain the active damping compensation torque, i.e., satisfying the following formula: Torque ADC = Torque out * TorqueCoeff, wherein Torque ADC is the active damping compensation torque, and TorqueCoeff is the torque coefficient.

[0047] In this embodiment, according to the comparison between the request torque and the torque threshold (ReqTrqThreshold = 1.0 Nm), it is determined that the active damping compensation torque in S7 is output if the request torque is greater than the torque threshold, otherwise 0 Nm is output.

[0048] Finally, it should be noted that the above-described embodiments are merely preferred embodiments of the present application for describing the technical solutions of the present application, and are not intended to limit the present application, and are not intended to limit the protection scope of the present application; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can still be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not cause the corresponding technical solutions to deviate from the protection scope of the claims.

Claims

1. A method of active damping control of an electrically driven vehicle, characterized by, The method comprises the following steps: S1, receiving and processing input signals, high-frequency low-pass filtering motor speed signals, and N-cycle average filtering requested torque; S2, calculating the speed fluctuation amount with the same frequency in the motor speed signal after the motor speed signal is filtered through a second-order low-pass filter and a second-order high-pass filter in series; S3, according to the filtered motor speed and the requested torque of the motor, searching a two-dimensional table, distinguishing specific requirements of different working conditions, interpolating to obtain PI control parameters, and outputting; In step S3, the two-dimensional table is a speed / torque-PI parameter two-dimensional table, which comprises a 1x5 speed table, a 1x5 torque table, and a 5x5 PI parameter table. The data in the two-dimensional table is cross-indexed by'speed-torque', and is calibrated according to calibration experience and driving feeling; S4, PI control calculation is performed on the speed fluctuation amount in S2 by the formula Torque out = K p · ΔSpd + K i · (ΔSpd - ΔSpd last ) to obtain an output torque, which is limited by upper and lower limits. In the above formula, ΔSpd represents the speed fluctuation. last K represents the speed fluctuation of the previous period. p K i Torque is a PI control parameter. out To calculate torque; Further, in S4, the speed fluctuation amount and the difference between the current cycle fluctuation amount are subjected to PI calculation, the motor speed fluctuation amount is closed-loop controlled, and the output torque is obtained; S5, comparing the low-pass filtered motor speed with the speed threshold value to determine whether the speed condition flag is triggered, and simultaneously sending the active damping enablement of the whole vehicle, the speed condition flag and the active damping enablement are simultaneously triggered to obtain the flag of the active damping trigger; S6, triggering the active damping flag and setting the opening slope, setting the exit slope when exiting, and simultaneously calculating the active damping torque coefficient; S7, multiplying the output torque in S4 by the active damping torque coefficient in S6 to obtain the active damping compensation torque; S8, comparing the requested torque with the torque threshold value to determine whether the active damping compensation torque in S7 or 0 is output.

2. The method of claim 1, wherein, In S1, the number N of cycles is an empirical value obtained according to driving feeling and data analysis in the whole vehicle test.

3. The method of claim 1, wherein, In the S7, the output torque is multiplied by the active damping torque coefficient in S6 to obtain the active damping compensation torque, i.e. to satisfy the following formula: Torque ADC = Torque out * TorqueCoeff, wherein Torque ADC is the active damping compensation torque, and TorqueCoeff is the torque coefficient.

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