JP2020124024A - Motor controller - Google Patents

Abstract

To solve a problem such that beyond a maximum possible output voltage of a power converter, a desired output torque of a motor cannot be obtained.SOLUTION: A current controller has an integrator with phase correction that calculates a correction phase from a voltage phase calculation unit for calculating a voltage phase of a motor and a voltage saturation detector for outputting a saturation degree of 0 to 1 according to voltage saturation, multiplies a d-axis current deviation and a q-axis current deviation by an integration gain and a sample time, adds an output prior to one sample subjected to reverse rotation coordinate conversion by a correction phase, and outputs those subjected to rotary coordinate conversion by a correction phase by dividing into a d-axis voltage command and a q-axis voltage command. By performing Q-axis current priority control to make a q-axis current control voltage a tangential component of a voltage vector, a torque according to a torque command is output.SELECTED DRAWING: Figure 1

Description

The present invention relates to a motor control device for driving a motor.

A conventional AC motor current control technique will be described below with reference to FIG. The current detector 2 converts the stator current of the motor 1 into a d-axis current id and a q-axis current iq of each component on the dq axes which are orthogonal coordinates for rotation and outputs the converted current. The d-axis is generally defined in the direction of the secondary flux linkage vector of the motor 1 when the motor 1 is an induction motor, and is generally defined as the rotor of the motor 1 when the motor 1 is a permanent magnet synchronous motor. It is defined in the N pole direction of the permanent magnet.

The current command generator 4 generates and outputs the d-axis current command idref and the q-axis current command iqref on the dq coordinates. The d-axis deviation calculator 6 calculates a d-axis deviation ide between the d-axis current command idref obtained by the current command generator 4 and the d-axis current id obtained by the current detector 2. The d-axis proportional amplifier 8 amplifies the d-axis deviation ide obtained by the d-axis deviation calculator 6 by a predetermined factor to calculate the d-axis proportional component vdp. Further, the d-axis deviation ide is amplified by the d-axis integral gain amplifier 32 and then time-integrated by the d-axis integrator 34 to become a d-axis integral component vdi.

The q-axis deviation calculator 5 calculates a q-axis deviation iqe between the q-axis current command iqref obtained by the current command generator 4 and the q-axis current iq obtained by the current detector 2. The q-axis proportional amplifier 7 amplifies the q-axis deviation iqe obtained by the q-axis deviation calculator 5 by a predetermined factor to calculate the q-axis proportional component vqp. The q-axis deviation iqe is amplified by the q-axis integral gain amplifier 31 and then time-integrated by the q-axis integrator 33 to become a q-axis integral component vqi.

The adder 35 adds the output vqp of the q-axis proportional amplifier 7 and the output vqi of the q-axis integrator 33 to calculate a q-axis voltage command vqr and outputs it to the power converter 3. The adder 36 adds the output vdp of the d-axis proportional amplifier 8 and the output of the d-axis integrator 34 to calculate a d-axis voltage command vdr and outputs it to the power converter 3.

The power converter 3 applies the voltage according to the input voltage command to the motor 1. If the magnitude of the voltage command is larger than the maximum voltage that the power converter 3 can output, the magnitude is phased at the maximum voltage. Applies the voltage as instructed to the motor 1.

In the current control shown in FIG. 4, when the magnitude of the voltage command vector having the d-axis component vdr and the q-axis component vqr exceeds the maximum output voltage of the power converter 3, the voltage according to the command is applied to the motor 1. Since it cannot be done, current control of one or both of the dq axes cannot be performed. The current control described in Patent Document 1 shown in FIG. 5 is proposed to solve this problem. Although FIG. 5 will be described below, description of the same parts as in FIG. 4 will be omitted, and only different parts will be described.

The voltage equation on the primary side when the motor 1 is an induction motor is expressed by equations (1) and (2). Here, vd is a d-axis voltage, vq is a q-axis voltage, R1 is a winding resistance value, Lσ=L1−M·M/L2, ω is an output angular frequency, M is a mutual inductance, and L1 and L2 are primary orders, respectively. And the secondary self-inductance, φ2 is the magnitude of the secondary interlinkage magnetic flux, and p is the time derivative. The voltage equation when the motor 1 is a permanent magnet synchronous motor is expressed by the equations (3) and (4). Here, Ld and Lq are d-axis and q-axis inductances, respectively, and φ is the magnitude of the permanent magnet magnetic flux.

The adder 44 adds the d-axis current deviation ide amplified by the d-axis speed proportional amplifier 42 to the input of the q-axis integrator 33. The d-axis speed proportional amplifier 42 is based on the third term on the right side of the equation (2) if the motor 1 is an induction motor and the equation (4) if it is a permanent magnet synchronous motor, and its amplification gain is proportional to the angular frequency ω. Will be things. Similarly, the adder 45 adds the q-axis current deviation iqe amplified by the q-axis speed proportional amplifier 43. The q-axis speed proportional amplifier 43 is based on the third term on the right side of the formula (1) when the motor 1 is an induction motor and the formula (3) when the motor 1 is a permanent magnet synchronous motor, and its amplification gain is proportional to the angular frequency ω. Will be things. The output of the adder 45 is input to the d-axis integrator 34. A switch 41 is inserted in the input of the d-axis integral gain amplifier 32, and the switch 41 operates when the magnitude of the input voltage command of the power converter 3 is smaller than the maximum outputtable voltage of the power converter 3. Deviation ide, 0 is output if not.

Even when the switch 41 is off, the d-axis current deviation ide is set to 0 by correcting the q-axis voltage command vqr by the q-axis integrator 33 via the d-axis speed proportional amplifier 42 and the adder 44. Therefore, d-axis current control can be realized. However, when the magnitude of the input voltage command of the power converter 3 exceeds the maximum outputtable voltage of the power converter 3 and enters a voltage saturation state, the output of the q-axis integrator 33 becomes a fixed value limited to the limit value. Therefore, the d-axis current control cannot be performed.

On the other hand, the q-axis current deviation iqe of the output of the q-axis deviation calculator 5 is corrected by correcting the d-axis voltage command vdr via the q-axis speed proportional amplifier 43, the adder 45 and the d-axis integrator 34. Remains retained. That is, in the voltage saturation state, the d-axis current control can be abandoned and the q-axis current control can be prioritized. Since the q-axis is an axis orthogonal to the magnetic flux axis, the torque of the motor 1 can be controlled by controlling the q-axis current, so that torque control can be maintained even if the voltage is saturated.

JP, 2003-88193, A JP, 2003-209997, A JP2012-151931A JP, 2016-167946, A

The problem to be solved is that, in the prior art of FIG. 4, when the voltage is saturated, control of both shafts or one shaft becomes impossible, and the desired output torque of the motor cannot be obtained. In the prior art of FIG. 5, the q-axis priority control can be performed even when the voltage is saturated, and a desired output torque can be obtained, so that the above problem can be solved, but there are the following problems.

FIG. 6 shows the voltage command vectors vr and vr1 at the time of voltage saturation and the voltage vectors v and v1 applied to the motor 1 in the conventional technique of FIG. The voltage vectors v and v1 are limited within the voltage output limit circle that is the maximum output voltage of the power converter 3, and the q-axis component of the voltage command vectors vr and vr1 is limited by the q-axis integrator 33 due to voltage saturation. Limited to the value vqrlmt. This vqrlmt needs to be equal to or higher than the maximum outputtable voltage of the power converter 3. As shown in FIG. 6, in the voltage saturation state, the q-axis voltage command is limited to the limit value vqrlmt, so the d-axis voltage command is adjusted to change the phase of the voltage vector to control the q-axis current. Will be there. For example, in order to change the voltage vector phase by Δθ, it is necessary to change the d-axis voltage command of Δvdr. In the case of an induction motor, as shown in FIG. 6, since the voltage vector is oriented in the direction close to the q-axis, the change amount of the d-axis voltage command required to change the voltage vector phase can be small. .. However, in the case of a permanent magnet synchronous motor, the direction of the voltage vector may be far away from the q-axis, so the amount of change Δvdr of the d-axis voltage command required to change the voltage vector phase must be increased. .. Therefore, it is necessary to make the output range of the d-axis integrator 34 very large, and it becomes difficult to adjust the gain of the q-axis speed proportional amplifier 43 or the d-axis integral gain amplifier 32, which is the integral gain.

Further, when the direction of the voltage vector becomes close to the d-axis, the voltage vector phase cannot be controlled by the d-axis voltage command control and the control becomes impossible. This also applies to the case where the voltage vector is in the first quadrant of FIG. 6 in the regenerative operation.

In Patent Document 2, in order to solve the above-mentioned problems, an M axis that matches the primary interlinkage magnetic flux vector of the AC motor and a T axis that is orthogonal thereto are introduced, and the MT axes are used instead of the dq axes as in FIG. However, there are the following problems. Although the T-axis current priority control can be performed, when the MT-axis current command is obtained from the dq-axis current command by rotational coordinate conversion, the q-axis current does not match the command due to voltage saturation, and the desired torque is obtained. Disappear. In addition, the phase of the M axis viewed from the d axis may change suddenly due to the sudden change of the current. At that time, it is necessary to suddenly change the voltage command of each axis to a value corresponding to the phase. However, since the output of the integrator cannot change suddenly, current control may become unstable when the phase of the MT axis changes suddenly.

The object of the present invention made in view of the above problems,
When the voltage is saturated, the q-axis current control output is used as the tangential component of the voltage vector, whereby the q-axis current priority control can be realized, and even if the voltage is saturated, the torque according to the torque command is output.
Further, by limiting the q-axis current command with a limit value according to the power supply voltage, an output according to the torque command can no longer be obtained, but it is possible to prevent an uncontrollable state.

In order to solve the above problems, a motor control device according to the present invention is a motor control device for discrete time control,
a current command generator for generating d-axis and q-axis current commands; and a d-axis current deviation calculator for calculating a deviation between the d-axis current command generated by the current command generator and the d-axis current flowing through the motor. A q-current deviation calculator for calculating a deviation between the q-axis current command generated by the current command generator and the q-axis current flowing through the motor,
A d-axis proportional amplifier that multiplies the output of the d-axis current deviation calculator by a proportional gain, and a q-axis proportional amplifier that multiplies the output of the q-axis current deviation calculator by a proportional gain,
A voltage phase calculator that calculates a voltage phase from the d-axis using the d-axis current command and the q-axis current command or the d-axis current and the q-axis current flowing through the motor and the motor impedance;
a voltage saturation detector that outputs a saturation degree of 0 to 1 according to voltage saturation using the d-axis voltage command and the q-axis voltage command;
A correction phase calculator that multiplies the outputs of the voltage phase calculator and the voltage saturation detector,
The outputs of the d-axis current deviation calculator and the q-axis current deviation calculator are multiplied by the integral gain and the sample time, and the output of the previous sample is subjected to reverse rotation coordinate conversion and added. A phase-corrected integrator that outputs the rotational coordinate conversion output from the phase correction calculator by dividing it into a d-axis component and a q-axis component;
An adder for adding the d-axis component outputs of the d-axis proportional amplifier and the integrator with phase correction, and a voltage value calculated using current feedback or a current command to the output of the adder to add the d-axis component A d-axis voltage adder that outputs a voltage command,
An adder for adding the q-axis component output of the q-axis proportional amplifier and the integrator with phase correction, and a voltage value calculated using current feedback or a current command to the output of the adder to add the q-axis component A q-axis voltage adder that calculates a voltage command is provided.

Also, the voltage saturation detector outputs 0 when the vector sum having the d-axis voltage command and the q-axis voltage command as vector components is less than the voltage output limit, The voltage phase based on the d axis is output to the rotary coordinate converter and the inverse rotary coordinate converter, and linearly changed from 0 to 1 according to the ratio of exceeding the voltage output limit. The voltage phase to be calculated is output to the rotary coordinate converter and the reverse rotary coordinate converter.

Further, a voltage-dependent limit calculator that outputs a q-axis current limit value by voltage limit, a current-dependent limit calculator that outputs a q-axis current limit value by current limit, an output of the voltage-dependent limit calculator and the current dependency A limit selector that selects a smaller one of the outputs of the limit calculators to calculate the q-axis current limit value, and a q-axis current command generated by the current command generator is input and the output is less than or equal to the output of the limit selector. A limiter for limiting the output to the q current deviation calculator is provided.

According to the motor control device of the present invention, even when voltage saturation occurs, the q-axis current control voltage is used as the tangential direction component of the voltage vector and the q-axis current priority control is performed to output the torque according to the torque command. can do.

It is a figure showing an example of composition of a current control part of a motor control device concerning the present invention. It is the figure which added the limitation of the q-axis current command to the motor control device concerning the present invention. It is a figure which shows the detail of a q-axis current limiter. It is explanatory drawing of the prior art example 1 of current control. It is explanatory drawing of the prior art example 2 of current control. It is the figure which illustrates the relationship between the voltage vector and each voltage command of the prior art. It is the figure which illustrates the relationship between the voltage vector and each voltage command of the present invention.

Hereinafter, a case where the present invention is applied to a permanent magnet synchronous motor will be described with reference to the drawings. The same parts as those in FIGS. 4 and 5 are designated by the same reference numerals, and the description thereof will be omitted. Further, the present invention will be described on the assumption that discrete time control is used.

FIG. 1 is a diagram showing a configuration example of a motor control device according to the present invention.

The voltage phase calculator 11 uses the d-axis current id and the q-axis current iq which are the outputs from the current detector 2 or the d-axis current command idref and the q-axis current command iqref which are the outputs from the current command generator. The voltage phase θv from the d-axis is calculated. The voltage phase θv is the voltage phase θv from the d axis of the voltage vector obtained from the equations (5) and (6). However, idv is the d-axis current id or the d-axis current command idref, and iqv is the q-axis current iq or the q-axis current command iqref. Further, ω is the output angular frequency.

The voltage saturation detector 12 uses the d-axis voltage command vdr and the q-axis voltage command vqr input to the power converter 3 to calculate the saturation degree Vs of 0 to 1 according to the voltage saturation.

Further, the voltage saturation detector 12 outputs 0 when the vector sum having the d-axis voltage command and the q-axis voltage command as vector components is less than the voltage output limit. Then, the vector sum is linearly changed from 0 to 1 according to the rate of exceeding the voltage output limit, and the voltage phase calculated by the voltage phase calculator is output to the rotary coordinate converter and the reverse rotary coordinate converter.

Expression (7) is an example of an expression for calculating Vs. α is a modulation factor obtained from the d-axis voltage command and the q-axis voltage command, K is a predetermined gain, and Vs is 1 when the voltage output limit is exceeded. Therefore, when the equation (7) is used, Vs gradually increases when the modulation rate exceeds 0.9, and Vs outputs 1 when the modulation rate reaches a predetermined value by the predetermined gain K.

The correction phase calculator 13 obtains the correction phase angle θr by θr=Vs·θv and outputs it to the integrator 100 with phase correction. Therefore, θr=0 when the voltage is not saturated, and θr=θv when the voltage is completely saturated.

The phase-corrected integrator 100 is composed of a q-axis integral gain amplifier 101, a d-axis integral gain amplifier 102, a rotating coordinate converter 103, an inverse rotating coordinate converter 104, and an output saver 105. The inverse rotational coordinate converter 104 performs inverse rotational coordinate conversion on the outputs vdi and vqi of the integrator 100 with phase correction, which is stored in the output storage 105, one sample before by using the corrected phase angle θr.

The d-axis integral gain amplifier 102 multiplies the d-axis current deviation ide, which is the output from the d-axis deviation calculator 6, by the integration gain and the sample time, and rotates Vx added to the output from the inverse rotation coordinate converter 104. Output to the coordinate converter 103. Here, Vx is limited to a predetermined value range. Further, the q-axis integral gain amplifier 101 multiplies the q-axis current deviation iqe, which is the output from the q-axis deviation calculator 5, by the integration gain and the sample time, and adds it to the output from the reverse rotation coordinate converter 104. Is output to the rotary coordinate converter 103.

The rotary coordinate converter 103 inputs Vx and Vy, performs rotary coordinate conversion with the correction phase angle θr, and outputs vdi and vqi.

The adder 18 adds the d-axis proportional output vdp of the d-axis proportional amplifier 8 and the d-axis output vdi of the integrator 100 with phase correction. Further, the d-axis voltage adder 16 calculates the d-axis voltage value by the equation (6) using the d-axis current id from the current detector 2 or the d-axis current command idref generated by the current command generator, The d-axis voltage command vdr is calculated by adding it to the output of the adder 18 and output to the power converter 3.

Further, the adder 17 adds the q-axis proportional output vqp of the q-axis proportional amplifier 7 and the output q-axis output vqi of the integrator 100 with phase correction. Further, the q-axis voltage adder 15 calculates the q-axis voltage value by the equation (5) using the q-axis current iq from the current detector 2 or the q-axis current command iqref generated by the current command generator, The q-axis voltage command vqr is calculated by adding to the output of the adder 17 and output to the power converter 3.

As described above, the voltage command can be obtained from the current command. Since θr=0 when the voltage is not saturated, vdi is the time integrated value of ide, and vqi is the time integrated value of iqe. Therefore, the d-axis and q-axis are independent proportional-integration amplifiers. The configuration is similar to that of 4.

In the state where the voltage is completely saturated, θr=θv, and the voltage vector relationship diagram as shown in FIG. 7 is obtained. Here, Vk is a voltage vector having components of the voltages of equations (6) and (5). ΔV is a voltage vector having vdi and vqi as components, and Vr is a voltage vector having vdr and vqr as components and is the sum of Vr and ΔV. Further, ΔV can also be represented by Vx, which is a normal component of Vk, and Vy, which is a tangential component of Vk. Therefore, the phase θ of Vr can be controlled by the Vy of the q-axis integral gain amplifier 101 output. On the other hand, although the magnitude of Vr can be controlled by the Vx of the d-axis integral gain amplifier 102 output, in the voltage saturation state, the magnitude of the voltage actually applied to the motor is limited to the voltage output limit. Therefore, Vx is limited to a predetermined value, and the output of the d-axis deviation calculator 6 cannot be constantly set to zero. In the following, it will be described that q-axis current control can be performed by Vy of the q-axis integral gain amplifier 101 output.

When the motor is in a steady state, the equations (8) and (9) are obtained from the equations (3) and (4). When the equations (8) and (9) are solved for each axis current, the equations (10) and ( It becomes a formula 11).

In the state where the power converter is saturated with the saturation voltage Em, the expression (12) can be obtained by using the voltage phase θ from the d-axis.

From equations (10), (11) and (12), equations (13) and (14) are obtained, and when partial differentiation of equations (13) and (14) is performed with θ, equation (15) is obtained. Equation (16) is obtained.
Becomes

From equation (15), in the range of ω>0 and 0≦θ≦θvx, or in the range of ω<0 and −θvx≦θ≦0, ∂iq/∂θ≧0, so θ can be positively increased. It can be seen that the q-axis current iq can be positively increased. Here, θvx is the expression (17).

That is, in the voltage saturated state, 0≦θ is always satisfied when ω>0, and 0≧θ is always satisfied when ω<0. Therefore, the q-axis current iq can be controlled by θ. That is, the q-axis current iq can be controlled by Vy of the q-axis integral gain amplifier 101 output.

Further, from the equation (14), the d-axis current id has a value corresponding to θ when the voltage is saturated. That is, when the voltage is saturated, the value becomes according to θ as a result of controlling the q-axis current iq.

As described above, in order to control the q-axis current iq by θ, θ<θvx must be satisfied when ω>0. By substituting the equation (12) and the equation (17) with θ=θvx into the equation (8), the q-axis current limit value iqLMT1 which is the limit of the q-axis current control can be obtained by the equation (18). That is, since it becomes difficult to control the q-axis current of iqLMT1 or more under the saturation voltage Em, the q-axis current command iqref must be limited to iqLMT1 or less.

Further, there is a limit value in the magnitude of the vector of the current that can be output by the power converter. If the limit value is set as the current limit value Im in order to prevent the current exceeding the limit value from flowing, the q-axis current command iqref must be limited by the q-axis current limit value iqLMT2 shown in the equation (19). I won't.

FIG. 2 shows a q-axis current command limiter 200 added between the current command generator 4 and the q-axis deviation calculator 5 of FIG. FIG. 3 is a diagram showing an example of the q-axis current command limiter 200 of FIG. 2, and is a diagram showing a method of limiting the q-axis current command. The voltage dependence limit calculator 21 inputs the saturation voltage Em and obtains the q-axis current limit value iqLMT1 from the equation (18). The current dependence limit calculator 22 calculates the q-axis current limit value iqLMT2 from the current limit value Im by the formula (19). The limit selector 23 selects the smaller one of iqLMT1 and iqLMT2 and outputs iqLMT. The limiter 24 limits the q-axis current command generated by the current command generator 4 to iqLMT and outputs it.

By limiting the q-axis current command as described above, an uncontrollable state due to the saturation voltage Em can be avoided, and the power converter can be protected by setting the current to a value that the power converter 3 does not allow. it can.

Although the present invention has been described, these embodiments are presented as examples and are not intended to limit the scope of the invention.

1 Motor 2 Current Detector 3 Power Converter 4 Current Command Generator 5 q-axis Deviation Calculator 6 d-axis Deviation Calculator 7 q-axis Proportional Amplifier 8 d-axis Proportional Amplifier 100 Integrator with Phase Correction 101 q-axis Integral Gain Amplifier 102 d-axis integral gain amplifier 103 rotating coordinate converter 104 inverse rotating coordinate converter 105 output saver 11 voltage saturation detector 12 voltage phase calculator 13 phase correction calculator 15 q-axis voltage value adder 16 d-axis voltage value adder

200 q-axis current command limiter 21 voltage-dependent limit calculator 22 current-dependent limit calculator 23 limit selector 24 limiter 31 q-axis integral gain amplifier 32 d-axis integral gain amplifier 33 q-axis integrator 34 d-axis integrator 41 switch 42 q-axis speed proportional device 43 d-axis speed proportional device 17, 18, 35, 36, 44, 45 adder

Claims (3)

A motor control device for controlling a motor in discrete time,
a current command generator for generating d-axis and q-axis current commands; and a d-axis current deviation calculator for calculating a deviation between the d-axis current command generated by the current command generator and the d-axis current flowing through the motor. A q-current deviation calculator for calculating a deviation between the q-axis current command generated by the current command generator and the q-axis current flowing through the motor,
A d-axis proportional amplifier that multiplies the output of the d-axis current deviation calculator by a proportional gain, and a q-axis proportional amplifier that multiplies the output of the q-axis current deviation calculator by a proportional gain,
A voltage phase calculator that calculates a voltage phase from the d-axis using the d-axis current command and the q-axis current command or the d-axis current and the q-axis current flowing through the motor and the motor impedance;
a voltage saturation detector that outputs a saturation degree of 0 to 1 according to voltage saturation using the d-axis voltage command and the q-axis voltage command;
A correction phase calculator that multiplies the outputs of the voltage phase calculator and the voltage saturation detector,
The outputs of the d-axis current deviation calculator and the q-axis current deviation calculator are multiplied by the integral gain and the sample time, and the output of the previous sample is subjected to reverse rotation coordinate conversion and added. Then, an integrator with phase correction for outputting the output of the phase correction arithmetic unit, which has been subjected to rotational coordinate conversion, into a d-axis component and a q-axis component separately, and
An adder for adding the d-axis component outputs of the d-axis proportional amplifier and the integrator with phase correction;
A d-axis voltage adder that adds a voltage value calculated using current feedback or a current command to the output of the adder, and outputs the d-axis voltage command;
An adder for adding the q-axis component output of the q-axis proportional amplifier and the integrator with phase correction, and a voltage value calculated using current feedback or a current command to the output of the adder to add the q-axis component A motor control device including a q-axis voltage adder that calculates a voltage command.
The voltage saturation detector according to claim 1,
When the vector sum having the d-axis voltage command and the q-axis voltage command as vector components is less than the voltage output limit, the voltage saturation detector rotates 0, and the voltage phase based on the d-axis is rotated. Output to the coordinate converter and the inverse rotation coordinate converter,
A voltage phase calculated by the voltage phase calculator, in which the vector sum having the d-axis voltage command and the q-axis voltage command as vector components is linearly changed from 0 to 1 according to the ratio of exceeding the voltage output limit. Is output to the rotary coordinate converter and the reverse rotary coordinate converter.
A motor control device for controlling a motor, comprising: a voltage-dependent limit calculator that outputs a q-axis current limit value by voltage limit; a current-dependent limit calculator that outputs a q-axis current limit value by current limit; Input the limit selector that selects the smaller of the output of the limit calculator and the output of the current-dependent limit calculator to calculate the q-axis current limit value, and the q-axis current command generated by the current command generator. 2. The motor control device according to claim 1, further comprising a limiter that limits the output to a value equal to or less than the output of the limit selector and outputs the current to the q current deviation calculator.

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