WO2020188880A1 - Backlash control device and backlash control method in electric motor drive system - Google Patents

Abstract

The present invention improves the operation performance of an electric motor drive system for driving a load via a gear by outputting an appropriate torque in a backlash zone. This backlash control device of an electric motor drive system for driving a load via a gear by an electric motor connected to an inverter is provided with: an acceleration torque switch 23 for adding, to a torque command T^*, an acceleration torque for accelerating a torque within a backlash zone; and a friction compensation switch 26 for adding a friction compensation torque for canceling a torque component in a direction opposite to a direction of exiting from the backlash zone. The backlash control device determines the backlash zone according to a switch flowchart in a determination unit 22 on the basis of an estimated twisting angle θ_BL^, an estimated twisting angular speed ω_BL^, and the torque command T^* which are estimated and calculated using an internal model in a calculation unit 24, said internal model describing the electric motor drive system, and determines the ON/OFF of the switches 23, 26 and outputs a torque command T^** considering backlash.

Description

Backlash control device and backlash control method in the motor drive system

The present invention relates to responsiveness and impact suppression in a system in which an electric motor drives a load via gears.

A mechanism that generates a DC voltage consisting of a combination of a battery or AC power supply and a rectifier (diode rectifier, PWM converter, 120 ° flow converter, etc.), an inverter that converts the DC voltage into an AC voltage and applies it to the motor (motor), and gears. Consider a drive system consisting of a motor that rotates a load via a motor, and the like. Here, the inverter generates an AC voltage having an amplitude and frequency that allows the motor to operate with an appropriate torque based on a torque command generated by operating the accelerator or the operation panel, and applies the AC voltage to the motor. Systems having such a drive system include, for example, elevators and machine tools.

By the way, backlash exists in the drive system having gears, and the torque on the motor side is not transmitted to the load side of the drive system in the backlash section, which has an influence such as deterioration of control responsiveness and instability. There is. Also, if you try to finish the backlash section short by turning the gears at high speed in the backlash section to avoid the influence, the impact will increase depending on the relative speed between the gears at the end of the backlash, that is, when the gears hit, and the sound will be heard. May occur. Such an impact sound may cause discomfort and anxiety to the user of the system, which is not preferable.

Regarding the effects of backlash such as these, conventionally, for example, in the steering device of Patent Document 1 and the work machine of Patent Document 2, the control stability of the backlash section is related by lowering the gain of the feedback control only in the backlash section. We are taking measures.

In addition, there are cases where a special structure is used such as a gear that does not contact teeth in the elevator of Patent Document 3 and a plurality of acceleration sensors in a vehicle of Patent Document 4 to take measures against impact and control responsiveness.

Further, the machine tool of Patent Document 5 is operated to absorb an unstable torque component in the backlash section to improve control stability.

Further, for operations known to enter backlash, such as the control of the vehicle of Patent Document 6, the molding machine of Patent Document 7, and the elevator of Patent Document 8, the control within the backlash section is determined in advance. It is also known to take measures for both control response and impact mitigation.

Japanese Unexamined Patent Publication No. 2004-358985 Japanese Unexamined Patent Publication No. 2012-10462 Japanese Unexamined Patent Publication No. 1-120457 Japanese Unexamined Patent Publication No. 2012-30745 Japanese Unexamined Patent Publication No. 10-254548 Japanese Unexamined Patent Publication No. 2013-183504 Japanese Unexamined Patent Publication No. 2003-71895 Japanese Unexamined Patent Publication No. 11-11688

The method of lowering the gain as in Patent Document 1 and Patent Document 2 requires a speed sensor. Further, in the backlash section, for example, an operation method in which acceleration is good at the beginning and then moderately decelerated in order to suppress the impact of the gears is excellent from the viewpoint of both responsiveness and impact suppression. In the control of, the stability is emphasized, and the operation that adjusts the fine responsiveness and impact in the backlash section is not considered.

Further, the method using a special structure as in Patent Document 3 and Patent Document 4 requires structural ingenuity in the drive system, resulting in an increase in design cost.

Further, the method of considering the vibration component as in Patent Document 5 requires repeated test operation to obtain the vibration component, and the responsiveness and the impact of the gear hitting are not discussed.

Further, the method of performing predetermined control as in Patent Document 6, Patent Document 7, and Patent Document 8 suppresses the impact of accelerating well at the beginning and then appropriately decelerating as described above. Although it is possible to express driving with high responsiveness, there is a problem that a table creation cost is incurred. In addition, since it is a table, there is a problem that it is difficult to deal with parameter errors and disturbances for each individual.

The present invention solves the above problems, and an object of the present invention is to improve the operating performance of an electric motor drive system that drives a load via gears by outputting an appropriate torque in a backlash section. The purpose of the present invention is to provide a backlash control device and a control method in a drive system.

The backlash control device in the electric motor drive system according to claim 1 for solving the above problems is
A backlash control device in an electric motor drive system that drives a load via gears by an electric motor connected to an inverter.
It has a means to determine the backlash section, a torque command corresponding to the set speed command is input, a process to generate acceleration torque for accelerating the torque in the backlash section, or a direction to exit the backlash section. It is equipped with a backlash control unit that calculates the backlash-considered torque command by performing at least one of the friction compensation torque addition processing for canceling the torque component in the opposite direction.
It is characterized in that the inverter is controlled based on the calculated backlash-considered torque command.

The backlash control device in the electric motor drive system according to claim 2 is claimed in claim 1.
The backlash control unit
An acceleration torque generator that generates acceleration torque when it is decided to perform the process of generating acceleration torque.
The relationship between the load torque with respect to the twist angle between the motor shaft between the motor and the gear and the load shaft between the gear and the load in the back crash section is defined by the back crash block set with a dead zone, and the motor side block and back crash block. , It has an internal model that expresses the motor drive system by dividing it into load side blocks, and the estimated motor angular speed is calculated from the output torque of the acceleration torque generator by the internal model, and is estimated for the load shaft of the motor shaft. A calculation unit that calculates and outputs the torsion angle speed and the estimated torsion angle or estimated load torque of the motor shaft with respect to the load shaft.
When the execution of the friction compensation torque addition process is decided, the friction compensation torque addition unit that adds the friction compensation torque to the output torque of the acceleration torque generation unit, and the friction compensation torque addition unit.
The estimated torsion angle or estimated load torque of the motor shaft with respect to the load shaft calculated by the calculation unit, the estimated torsional angle speed of the load shaft of the motor shaft, and the torque command corresponding to the speed command are input, and in the backlash section. It is determined whether or not there is, and based on the determination result, the process of generating the acceleration torque in the acceleration torque generating unit is executed, the decision not to be performed, and the friction compensation torque addition process in the friction compensation torque adding unit is performed. It is characterized by being provided with a determination unit for determining non-implementation.

The backlash control device in the electric motor drive system according to claim 3 is claimed in claim 2.
The acceleration torque generating unit is characterized by having a limiter that limits the upper limit and the lower limit of the input torque command.

The backlash control device in the electric motor drive system according to claim 4 is claimed in claim 2.
The acceleration torque generation unit is characterized by having a backlash speed control unit that controls the speed so that the estimated torsion angular velocity calculated by the internal model becomes a set speed command.

The backlash control device in the electric motor drive system according to claim 5 is according to any one of claims 2 to 4.
The internal model has a disturbance compensation system that takes a deviation between the detected motor angular velocity that detects the angular velocity of the electric motor and the calculated estimated motor angular velocity, and feeds back the deviation to the internal model so that the deviation becomes zero. It is characterized by being.

The backlash control device in the electric motor drive system according to claim 6 is according to any one of claims 2 to 5.
The determination unit
When the estimated torsion angle of the motor shaft with respect to the load shaft is within the backlash phase range of the gear, or when the estimated load torque is near zero, it is determined to be a backlash section, and other than that, it is not a backlash section. The first determination process to determine that
When the backlash section is determined by the first determination process, the second determination process for determining whether or not the torque command corresponding to the speed command is within the set dead zone,
When it is determined by the second determination process that it is not within the dead zone, a third determination process for determining whether or not the estimated torsional angular velocity is within the set dead zone is performed.
When it is determined by the first determination process that it is not a backlash section and when it is determined by the second determination process that the torque command is within the dead zone, the process of generating the acceleration torque is not performed and friction Decided not to implement the compensation torque addition process,
When it is determined by the third determination process that the estimated torsional angular velocity is within the dead zone, it is determined to perform the process of generating the acceleration torque, and it is determined not to perform the friction compensation torque addition process.
When it is determined by the third determination process that the estimated torsional angular velocity is not within the dead zone, it is characterized in that the execution of the process of generating the acceleration torque and the execution of the friction compensation torque addition process are determined.

The backlash control method in the electric motor drive system according to claim 7 is
It is characterized in that the backlash control device in the electric motor drive system according to any one of claims 1 to 6 is executed.
(1) According to the inventions of claims 1 to 7, the operating performance of the electric motor drive system that drives the load via the gear can be improved by outputting an appropriate torque in the backlash section.
(2) According to the second aspect of the present invention, it is possible to prevent a decrease in responsiveness while suppressing the generation of a gear collision sound when exiting the backlash.
(3) According to the invention of claim 3, control can be performed based on a backlash-considered torque command that does not exceed the upper limit of torque.
(4) According to the invention of claim 4, since the torque for appropriately controlling the torsional angular velocity of the motor shaft with respect to the load shaft is set as the acceleration torque, it is not easily affected by the parameter error and the control performance of the backlash section is improved. improves.
(5) According to the invention of claim 5, even if an error occurs between the internal model expressing the electric motor drive system and the actual electric motor drive system due to the disturbance, the influence of the error can be suppressed. it can.
(6) According to the invention of claim 6, it is possible to prevent chattering of the output of the backlash control unit (backlash consideration torque command).

The configuration of the motor drive system in the embodiment of the present invention is shown, (a) is a connection configuration diagram of a motor and a load, and (b) is a configuration diagram of a control. The system block diagram of the backlash control in Example 1 of this invention. The system block diagram of the internal model in Example 1 of this invention. The flowchart of the main part in the Example of Embodiment of this invention. The system block diagram of the backlash control in Example 2 of this invention. The system block diagram of the internal model in Example 2 of this invention. The system block diagram of the backlash control in Example 3 of this invention. The system block diagram of the backlash speed control in Example 3 of this invention. The system block diagram of the backlash control in Example 4 of this invention. The effect of friction compensation in the backlash section is shown, (a) is a graph of torsion angle θ _BL , and (b) is a graph of torsion angular velocity ω _BL . The effect of acceleration torque in the backlash section is shown, (a) is a graph of torsion angle θ _BL , and (b) is a graph of torsion angular velocity ω _BL . The effect of disturbance compensation in the backlash section is shown, (a) is a graph of torsion angle θ _BL , (b) is a graph of torsion angular velocity ω _BL , (c) is a graph of torsion angle comparison without disturbance compensation, (d). Is a graph of torsion angle comparison with disturbance compensation. The effect of backlash velocity control in the backlash section is shown, (a) is a graph of torsional velocity θ _BL , and (b) is a graph of torsional angular velocity ω _BL .

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following examples of embodiments.

In the following, "backlash" may be abbreviated as "BL".

(Example 1)
FIG. 1 shows a system configuration diagram of the drive system according to the first embodiment. The connection configuration diagram of FIG. 1A represents a drive system in which a motor (motor) 1 rotates a load 5 via a gear 3, 2 is a motor shaft between motor 1- gear 3, and 4 is gear 3-load. The load axis between 5 is shown. The relative angular velocity (torsion angular velocity) of the motor shaft 2 with respect to the load shaft 4 is ω _BL (at this time, the gear ratio is taken into consideration in the angular velocity of the two shafts), and the torsion angle of the two shafts is θ _BL . Within the backlash section, ω _BL is the angular velocity at which the gear (gear 3) passes through the backlash. FIG. 1A is hereinafter sometimes referred to as a “plant”.

In the control system of FIG. 1B, a speed command ω ^* that is generated and adjusted according to the form of the drive system such as the accelerator depression amount and the operation panel operation amount is input. The speed command ω ^* is input to the speed control unit 11, and the speed control unit 11 outputs a torque command T ^* for appropriately reaching the target speed. Regarding speed control, although the speed sensor is not provided in FIG. 1 (b), it is not essential that the speed sensor is not provided, and the torque is based on the motor phase detected by the sensor and the motor speed calculated using the phase. Command T ^* may be determined.

The torque command T ^* output from the speed control unit 11 is input to the backlash control unit 12, and the backlash control unit 12 calculates the BL-considered torque command T ^** in consideration of the presence of the backlash. The BL-considered torque command T ^** output from the backlash control unit 12 is input to the current control unit 13. The current control unit 13 calculates a voltage command for outputting a target torque based on the detected current that detects the current of the motor 1, outputs a gate signal for realizing the voltage, and appropriately controls the inverter 14. To do. Inverter 14 applies a three-phase AC voltage to the motor 1, the motor torque T _M is caused by electromagnetic induction in the motor 1.

FIG. 2 shows a system configuration diagram of the backlash control unit 12 in the first embodiment. The torque command T ^* from the speed control unit 11 is input to the backlash control unit 12. The input torque command T ^* branches into three, one of which does not perform any particular calculation, and the other of which becomes the limit torque command _Trim via the limiter 21, and the remaining one is the acceleration shown in FIG. 4 described later. A switch flowchart for determining ON / OFF of the torque switch and the friction compensation switch is provided, a backlash section is determined, and a determination is made to determine whether to perform a process of generating acceleration torque or a process of adding friction compensation torque. It is input to the unit 22.

_{Reference numeral} 23 denotes an acceleration torque switch controlled by an ON / OFF control signal determined by the determination unit 22, and the limit torque command _Slim is selected during ON control and the torque command T ^* is selected during OFF control. The output is used as the in-control motor torque T _Mc in the subsequent processing. The limiter 21 and the acceleration torque switch 23 constitute the acceleration torque generator of the present invention.

Reference numeral 24 denotes a calculation unit having an internal model of FIG. 3 described later, which expresses the drive system of FIG. 1A, and receives an in-control motor torque T _Mc which is an output of the acceleration torque switch 23 as an input, and an estimated torsion angle. θ _BL ^ and the estimated torsional angular velocity ω _BL ^ are calculated and output to the determination unit 22.

The in-control motor torque T _Mc is also branched and input to the adder 25 and the friction compensation switch 26, and the adder 25 adds the friction compensation torque of the friction compensation torque setting unit 27 and the in-control motor torque T _Mc. The friction-considered torque command T _f is output.

The friction compensation switch 26 is controlled by an ON / OFF control signal determined by the determination unit 22, and the friction consideration torque command T _f is selected during ON control, and the in-control motor torque T _Mc is selected during OFF control. The output is the BL-considered torque command T ^** , which is the output of the backlash control unit 12. The adder 25, the friction compensation switch 26, and the friction compensation torque setting unit 27 constitute the friction compensation torque adding unit of the present invention.

In FIGS. 2, 4, 5, 7, and 9, the "acceleration torque switch" is abbreviated as "acceleration switch" and the "friction compensation switch" is abbreviated as "friction switch".

FIG. 3 shows a system configuration diagram of an internal model of the arithmetic unit 24 in the first embodiment. Each block is arranged based on the equation of motion, rigidity, friction, etc. of the drive system shown in FIG. 1 (a).

In FIG. 3, the subtractor 31 subtracts the torque obtained by dividing the estimated load torque T _L ^ described later by the gear ratio gr of the divider 33b from the input in-control motor torque T _Mc .

The subtraction output of the subtractor 31, a function multiplier 32 the motor torque to the motor angular velocity transfer function G _.omega.M (s) is the estimated motor angular velocity omega _M ^ is multiplied is calculated.

The estimated motor angular velocity ω _M ^ is divided by the gear ratio gr of the divider 33a and input to the subtractor 34. Subtractor 34, the divider output of 33a from (angular velocity component of the motor side), the estimated load torque T _L ^ multiplied by multiplying a transfer function G _.omega.L from the load torque of the function multiplier 35 to the load angular velocity (s) to the output Subtract (angular velocity component on the load side).

Output estimated torsional angular velocity omega _BL ^ is obtained in the subtractor 34, the estimated torsion angle theta _BL ^ is obtained by integrating the integral term 1 / s integrator 36 the omega _BL ^.

Reference numeral 37 denotes a backlash block in which the relationship of the load torque with respect to the estimated torsion angle θ _BL ^ is set with a dead zone.

The output torque of the back crush block 37 is multiplied by the transfer function G _TL (s) from the output of the back crush block of the function multiplier 38 to the load torque, and the multiplied output is the estimated load torque _TL ^. It is input to 33b and the function multiplier 35.

The obtained estimated torsional velocity ω _BL ^ and the estimated torsional angle θ _BL ^ are output to the determination unit 22 in FIG.

In the internal model configured as shown in FIG. 3, the load torque is normally determined based on the torsion angle of the motor shaft 2 with respect to the load shaft 4, but is the load torque 0 in the phase in which the gears (gears 3) do not mesh? , A value close to 0 (considering mechanical friction, etc.). The backlash block 37 modifies the estimated torsion angle θ _BL ^ so that the relationship between the torsion angle and the load torque can be expressed, and generates an input to the transfer function G _TL (s) of the function multiplier 38.

In the internal model of FIG. 3, the drive system is divided into the motor side, backlash, and load side, and the interaction is fed back from the load side to the motor side. As long as the drive system separated by this backlash is expressed, it is not always necessary to stick to the shape shown in FIG.

The transfer functions G _ωM (s), G _ωL (s), and G _TL (s) have a significant effect on the estimated torsion angle θ _BL ^ not only for a single equation of motion of the motor and load but also for the entire drive system. All equations of motion, friction and stiffness shall be considered within the range.

Regarding the backlash block 37, the backlash may be regarded as equivalent to the dead zone processing, but the upper and lower limits of the dead zone do not have to be constant. That is, the upper and lower limits of the dead zone may be changed in consideration of changing the connection with the load, heat, wear, and the like. Further, it is not always necessary to output 0 in the dead zone, and a continuous output may be provided inside and outside the dead zone in consideration of an actual physical phenomenon.

Further, for the entire internal model, each estimator is obtained on the assumption that the input in-control motor torque T _Mc is directly applied to the drive system.

In FIG. 2, which shows the configuration of the backlash control unit 12, there are two switches, an acceleration torque switch 23 and a friction compensation switch 26. If both of these switches are always OFF, the backlash control unit in FIG. 2 has an input torque. The command T ^* is output as it is as the torque command T ^** . This shows the operation during normal driving, which is not related to backlash. That is, the backlash control unit 12 turns off both the switches 23 and 26 outside the backlash section to support normal driving, and turns on the switches 23 and 26 at appropriate timings inside the backlash section to backlash. It enables special control within the rush section.

The ON / OFF determination of the acceleration torque switch 23 and the friction compensation switch 26 performed by the determination unit 22 is executed according to the flow chart for the switch, and will be described in detail later together with FIG.

Here, the torque output in the backlash will be explained by dividing it into two types, friction compensation torque and acceleration torque, according to their role.

First, the friction compensation torque will be explained. In the backlash, friction is generated in the gear until the gears mesh, but by outputting the compensation torque in consideration of this amount, it is possible to prevent the time until the backlash is removed from becoming long.

When the friction compensation switch 26 is turned on, the friction compensation torque of the friction compensation torque setting unit 27 is added at the final stage of the BL control calculation as shown in FIG. The final stage is because if the input torque command T ^* is added in the first process, the friction compensation torque will be added to the internal model of the calculation unit 24, and the internal model does not consider friction. This is because the friction compensation torque has an unintended effect on the estimator of the internal model. Therefore, the friction compensation torque may be generated by using a model that considers friction in the internal model instead of the form of direct addition.

Since the friction in the gear 3 of FIG. 1A is generated in the direction opposite to the torsional angular velocity ω _BL , which is the relative angular velocity of the motor shaft 2 and the load shaft 4, the positive and negative of the friction compensation torque, which is the compensation, is determined by the internal model. Make it the same as the positive and negative of the calculated estimated torsional velocity ω _BL ^. In addition, the absolute value of friction compensation torque shall be set to an appropriate value according to the load.

FIG. 10 shows a simulation of friction compensation. Here, we are considering a drive system in which a motor rotates a load via gears. In addition, the same motor constant and load constant are used in each simulation. The input torque command T ^* to the BL control unit 12 was given at a rate of change of 200 Nm per second from −50 Nm to 50 Nm. FIG. 10 (a) shows the transition of the torsion angle θ _BL in the gear 3 of the plant of FIG. 1 (a), the line 101 shows the simulation result when BL control is not performed, and the line 102 suppresses the torque in the BL section to zero. As a result of the simulation, the line 103 shows the simulation results when only the friction compensation torque is present and the acceleration torque is not considered.

FIG. 10B shows the transition of the torsional angular velocity ω _BL of the plant of FIG. 1A, line 104 shows the simulation result when BL control is not performed, and line 105 shows the case where the torque in the BL section is suppressed to zero. As a result of the simulation, the line 106 shows the simulation results when only the friction compensation torque is present and the acceleration torque is not considered.

The backlash interval in this simulation is the interval of -1 <θ _BL <1.

Looking at FIG. 10 (a), “without BL (backlash) control” shown by line 101 is the earliest of the three results to exit the backlash, but looking at FIG. 10 (b) at that time, Like the wire 104, the torsional angular velocity ω _BL is large, and in actual operation, a sound is generated when the gear (gear 3) collides. If the torque is suppressed to 0 in the backlash section in order to prevent this, the period of being in the backlash becomes longer as shown by the line 102 in FIG. 10 (a). This can lead to reduced responsiveness.

On the other hand, in the case of "with friction compensation and without acceleration" shown in line 103 of FIG. 10A, only the compensation for friction is added in BL (acceleration torque described later is not considered), and the line 102 "BL torque 0". It can be seen that the backlash is exited faster than "" and the responsiveness is improved. After exiting the backlash, the ω _BL changes sharply, but this is because the higher speed control works, not the BL control. Then, in the subsequent simulations, the interpretation of the steep ω _BL after exiting the backlash is the same.

Next, the acceleration torque will be described. The above-mentioned friction compensation torque is compensation for canceling the torque component in the direction opposite to the direction of exiting the backlash, and it is compensation for preventing deceleration of the meshing speed. Here, assuming that the friction content is accurately canceled, the torque for further acceleration is considered.

There are three main points to note when setting the acceleration torque.

The first is about the appropriate addition position. Since the internal model does not consider friction, the friction compensation torque is not input to the internal model, but the acceleration torque is a component that the internal model considers, so it must be input to the internal model.

The second is the upper limit of the torque command. If the motor torque is large when exiting the backlash, that is, when the gear hits, a noise is generated and comfortable driving is hindered. Therefore, the torque in the backlash section needs to be adjusted so as not to generate noise by combining the friction compensation torque and the acceleration torque.

The third is the handling of input torque commands. For example, if the method of adding the acceleration torque to the input torque command T ^* from the upper level is adopted, T ^* is added to the torque command adjusted to the extent that no sound is generated, and the torque upper limit described in the second item cannot be observed. As another example of the method, if the torque is simply set to a fixed value in the backlash section, the backlash will always be released with a constant torque after the backlash enters, which causes inconvenience in the operation at extremely low speed or when stopped.

Based on the above three points, the torque command T ^* is limited as shown in FIG. 2 to realize the acceleration torque. At this time, the limiter is set before the internal model (corresponding to the first caution), and the torque value that does not generate sound when the gears are engaged is set as the upper and lower limits (corresponding to the second caution). ), Limit processing (corresponding to the third point of caution).

Since the limiter 21 for acceleration torque is desired to be effective only in the backlash section, the torque command T ^* is configured to pass through the limiter 21 only when the acceleration torque switch 23 is ON-controlled.

FIG. 11 shows the difference between the case where the acceleration torque is provided and the case where the acceleration torque is not provided. FIG. 11A shows the transition of the torsion angle θ _BL of the plant of FIG. 1A, line 101 shows the simulation result when BL control is not performed, and line 103 shows only the friction compensation torque and does not consider the acceleration torque. As a result of the simulation, the line 107 shows the simulation result when the friction compensation torque and the acceleration torque are present.

FIG. 11B shows the transition of the torsional angular velocity ω _BL of the plant of FIG. 1A, line 104 shows the simulation result when BL control is not performed, line 106 shows only friction compensation torque, and acceleration torque is not considered. As a result of the simulation, the line 108 shows the simulation result when the friction compensation torque and the acceleration torque are present.

In FIG. 11, friction compensation is appropriately performed in both cases except for the case of "no BL control".

As can be seen from FIG. 11A, there is a difference in the period of backlash (period of -1 <θ _BL <1) due to the acceleration torque, which is more than the line 103 "with friction compensation and without acceleration". 107 "with friction compensation and with acceleration" is faster than the backlash.

Further, as shown in FIG. 11B, the ω _BL of line 108 “with friction compensation and with acceleration” is lower than that of line 104 “without BL control”, and is limited to an appropriate value in consideration of sound generation. You can also see that it has been done. Therefore, when the lines 107 and 108 are provided with "with friction compensation and with acceleration", that is, when the friction compensation torque and the acceleration torque are provided, the generation of the collision noise of the gears is suppressed and the responsiveness is reduced as much as possible. It can be prevented.

The above is the explanation of the compensation torque in the backlash.

Next, a method of determining ON / OFF of the acceleration torque switch 23 and the friction compensation switch 26 will be described with reference to FIG.

FIG. 4 shows an example of the process (flow chart for the switch) performed by the determination unit 22 of FIG. 2, and in step S1, the torque command T ^* from the speed control unit 11 and the estimated torsion angle θ calculated by the internal model of FIG. 3 Enter _BL ^, estimated torsional velocity ω _BL ^.

Next, in step S2, it is determined whether or not the estimated torsion angle θ _BL ^, which is basically the output of the internal model, is within the backlash phase range of the gear (gear 3), and if it is within the range, backlash It is determined as an interval (first determination process). Further, the backlash determination criterion is not limited to θ _BL ^, and for example, the estimated load torque T _L ^ in FIG. 3 may be used. _TL ^ is the output of the backlash block 37 passed through the transfer function G _TL (s), and when the internal model is within the backlash interval, _TL ^ is near 0 (otherwise, backlash is near 0). The operation cannot be expressed).

As described above, in the first branch of the backlash determination (step S2), it is determined whether or not it is within the backlash section, and if it is outside the backlash section, both the acceleration torque switch 23 and the friction compensation switch 26 are turned off (acceleration torque). (Determine the non-execution of the process to generate and the non-execution of the friction compensation torque addition process) (processing during normal driving).

If the judgment result of step S2 is within the backlash section, the process proceeds to the next branch (step S3). Subsequent branches (steps S3 and S4) are processes for chattering countermeasures.

The input torque command T ^* is a torque command calculated at the upper level based on the amount of operation of the accelerator and the operation panel, and is considered to be close to 0 when stopped. At this time, it is possible that the torque moves up and down near the zero cross, and the polarity of the torque for exiting the backlash may change at high speed.

In such a case, the BL control output (BL-considered torque command T ^** ) causes chattering. To prevent this, a dead zone is set in T ^* , and if it is outside the dead zone, backlash torque is generated ( ON of the acceleration torque switch 23 is confirmed). Within the dead zone, it is considered that the appropriate compensation direction, that is, the direction in which the backlash is desired to be exited is unknown, and compensation is not performed. That is, the acceleration torque switch 23 and the friction compensation switch 26 are turned off (determined not to perform the process of generating the acceleration torque and not to perform the friction compensation torque addition process).

Since there is another chattering factor in the friction compensation torque, when the torque command T ^* is out of the dead zone, the vehicle goes to the next branch (step S4).

It was mentioned above that the positive and negative of the friction compensation torque should be the same as the positive and negative of the estimated torsional angular velocity ω _BL ^. With this estimation method, when ω _BL ^ is near the zero cross, the estimated friction generation direction may switch at high speed. At this time, the polarity of the friction compensation torque changes at high speed, and the BL control output (T ^** ) causes chattering. As a countermeasure, a dead zone is set for the estimated torsional angular velocity ω _BL ^, and if the determination result in step S4 is outside the dead zone, friction compensation torque is generated (friction compensation switch 26 is confirmed to be ON) (acceleration torque is generated). Determine the implementation of the process and the friction compensation torque addition process).

The direction of friction compensation is unknown within the dead zone of the estimated torsional angular velocity ω _BL ^, but it is considered that the direction in which the backlash is desired to be exited is known by the dead zone determination (step S3) of T ^{* in} the previous stage, and only the acceleration torque switch 23 is turned ON ( Decide whether to perform the process to generate acceleration torque and not to perform the friction compensation torque addition process).

In addition, when estimating the direction of friction by another method, a dead zone shall be provided according to the method and chattering processing shall be performed.

It is necessary to determine the dead band width for each dead band of the torque command T ^* in step S3 and the estimated torsional angular velocity ω _BL ^ in step S4, but this is a detected value such as the resolution and error of the number of effective digits of digital calculation and adaptive correction. Usually, it is set to 1% or less of the rating in consideration of the indirect effect on. It may be set to about 0.1% while checking in an actual plant.

The above is the explanation of the flow chart for ON / OFF determination of the acceleration torque switch 23 and the friction compensation switch 26. By performing the control based on this flowchart, the backlash section can be controlled without causing chattering.

As described above, according to the first embodiment, by determining the backlash section and outputting an appropriate torque, it is possible to suppress the collision noise of the gear when the backlash is passed, and the responsiveness is not lowered more than necessary. It is possible to perform control within the backlash section that chattering of the control output does not occur, and it is possible to improve the operating performance of the electric motor drive system that drives the load via gears.

In addition, for the prior art documents, in order to obtain a vibration component that does not require the use of a speed sensor, considers responsiveness and impact, can be realized only by changing the control without requiring a special structure. It has the advantages of not requiring repeated test runs and no need to create a table.

(Example 2)
In the first embodiment, a method of predicting the backlash section and instructing an appropriate motor torque without using a speed sensor was considered. However, depending on the drive system, a large amount of disturbance may occur, which causes an error between the internal model and the actual drive system, resulting in a misprediction of the timing of entering backlash. Such a drive system includes, for example, an automobile. When driving a car, its own weight acts as a disturbance on a slope.

As a countermeasure for this, Example 2 made it possible to compensate for disturbance by using a speed sensor. FIG. 5 shows the system configuration of the backlash control unit 12 of FIG. 1 (b) in the second embodiment.

In FIG. 5, the difference from FIG. 2 of the first embodiment is that, for example, the detected motor angular velocity ωdet from the speed sensor attached to the motor 1 is input to the internal model configured in the calculation unit 54, and the detected motor angular velocity ωdet and the internal model are input. It is to feed back to the internal model by, for example, PI control so that the difference becomes zero by comparing with the estimated angular velocity ω _BL ^ calculated in, and the other parts are configured in the same manner as in FIG.

The operation of determining ON / OFF of the acceleration torque switch 23 and the friction compensation switch 26 is the same as the operation of the first embodiment in consideration of whether or not it is a backlash section according to the switch flowchart (flow of FIG. Will be done.

The internal model in the calculation unit 54 of the second embodiment is configured as shown in FIG. 6, and the same parts as those in FIG. 3 are indicated by the same reference numerals.

Reference numeral 41 denotes a subtractor that takes a deviation between the estimated motor angular velocity ω _M ^ calculated by the function multiplier 32 and the input detection motor angular velocity ωdet, and the deviation output is a positive proportional gain of the gain multiplier 42. The KP and the positive integrated gain KI of the gain multiplier 43 are each multiplied. The output of the gain multiplier 43 is integrated by the integrator 44.

The output of the gain multiplier 42 (P control component) and the output of the integrator 44 (I control component) are added by the adder 45, and the added output is fed back to the front of the function multiplier 35.

Reference numeral 46 denotes a subtractor for subtracting the output of the adder 45 from the estimated load torque T _L ^ which is the output of the function multiplier 38, and the subtracted output is input to the function multiplier 35.

The internal model of FIG. 6 is provided with a disturbance compensation system that performs PI control on the deviation of the subtractor 41 and feeds back the output of the adder 45 to the subtractor 46, and the other parts are the same as those of FIG. It is configured in.

For the positive proportional gain KP and positive integrated gain KI of the PI control, values appropriately adjusted so that disturbance compensation can be performed under normal control shall be used. Other system configurations and variable names are the same as in FIG.

The feedback position of the PI control, although the front of the transfer function G _.omega.L function multiplier 35 in FIG. 6 (s), the estimated motor angular velocity omega _M ^ and detection of the motor angular velocity ωdet difference another be zero Since it can be achieved by feeding back to the position, it may be fed back to another position, for example, before the transfer function G _ωM (s) of the function multiplier 32. At that time, it should be noted that the estimated torsion angle θ _BL ^ and the estimated torsional angular velocity ω _BL ^ used for determining the backlash section change sensitively to disturbance depending on the feedback position. Then, since the disturbance is added to the acceleration torque in the backlash section due to the occurrence of the disturbance, the control of the backlash section may be affected. Regarding the compensation method in that case, first, the output of PI control or only the I term is multiplied by the gain (gear ratio, etc.) according to the feedback position, and the estimated disturbance is converted into the motor shaft to obtain the motor torque disturbance. Then, compensation is performed by increasing or decreasing the vertical limit value of the acceleration torque (limit value of the limiter 21) and the friction compensation torque value of the friction compensation torque setting unit 27 by the amount of the motor torque disturbance.

FIG. 12 shows the effect of disturbance compensation in the backlash section. The simulation conditions are basically the same as in the first embodiment, except that a constant steady disturbance is always applied to the load side during the simulation period.

FIG. 12A shows the transition of the torsion angle θ _BL of the plant of FIG. 1A, line 111 is a simulation result in the case of no disturbance compensation (Example 1), and line 112 is with disturbance compensation (Example 2). The simulation results in the case of) are shown.

FIG. 12 (b) shows the transition of the torsion angular velocity ω _BL of the plant of FIG. 1 (a), line 113 is a simulation result in the case of no disturbance compensation (Example 1), and line 114 is with disturbance compensation (Example 2). The simulation results in the case of) are shown.

FIG. 12 (c) shows the transition of the torsion angle θ _BL when there is no disturbance compensation (Example 1), line 115 is the simulation result of the torsion angle estimated and calculated by the internal model, and line 116 is FIG. 1 (a). The simulation results of the torsion angle of the plant are shown.

FIG. 12 (d) shows the transition of the torsion angle θ _BL when there is disturbance compensation (Example 2), line 117 is the simulation result of the torsion angle estimated by the internal model, and line 118 is the simulation result of the torsion angle in FIG. 1 (a). The simulation results of the torsion angle of the plant are shown.

In addition, in FIGS. 12 (c) and 12 (d), the torsion angles of the plant and the internal model are compared in order to see the influence of the disturbance on the backlash interval estimation in more detail, and FIGS. 12 (a) and 12 (b) show. The area around the backlash is enlarged.

Looking at FIGS. 12A and 12B, it can be seen that the second embodiment (lines 112 and 114) in which the disturbance compensation is performed passes through the backlash faster, and the responsiveness is improved by the disturbance compensation. Recognize.

In the case of no disturbance compensation in FIG. 12 (c), the error between the plant θ _BL (line 116) and the θ _BL ^ (line 115) estimated by the internal model is large, and the plant θ _BL passes through the backlash. Despite the fact that the estimated θ _BL ^ is in the backlash section (the torque for the backlash section is output outside the backlash section), the period is longer than that with the disturbance compensation shown in FIG. 12 (d). It has been done. This estimation error affects the responsiveness and causes a difference between the results with and without disturbance compensation in FIGS. 12A and 12B.

In the polarity of the disturbance this time, the decrease in responsiveness was improved by compensation, but consider the case of the opposite polarity. In this case, since it is determined that the backlash has passed earlier than the actual value due to the estimation error, the responsiveness does not deteriorate, but the torque is treated as normal running and is not limited, so that a sound is generated by the impact. Therefore, even if the polarity of the disturbance is different, it can be said that the disturbance compensation is necessary due to problems other than responsiveness.

As described above, in the second embodiment, in addition to the contents of the first embodiment, it is possible to compensate for the disturbance by giving feedback based on the detected motor angular velocity.

As a result, the collision noise of the gears when exiting the backlash can be suppressed, the responsiveness is not lowered more than necessary, the control output is not chattered, and the control performance deterioration caused by the estimation error due to the disturbance can be prevented. Control within the section can be performed, and the operating performance of the electric motor drive system that drives the load via gears can be improved.

In addition, for the prior art documents, it is necessary to repeat test operation to obtain the vibration component, which considers responsiveness and impact, can be realized only by changing the control without requiring a special structure. It has advantages such as no need to create a table, consideration of the influence of disturbance, and so on.

(Example 3)
In Example 1, it was decided to set a torque value that is compatible with both responsiveness and impact in the backlash section. However, the speed becomes a problem with respect to the time until the gear (gear 3) meshes and the momentum contributing to the impact. Further, in the case of the first embodiment, since the vehicle continues to accelerate with a constant torque within the backlash section, if the backlash of the plant is large with respect to the model data regarding the backlash angle, the acceleration will be too large and noise will be generated. There are also problems due to parameter errors. As these measures, in Example 3, the control performance of the backlash section was improved by performing control based on the speed.

At this time, the important point is that the friction compensation torque needs to be compensated in the same manner as in Example 1 in order to compensate for the torque component generated as friction. Therefore, the acceleration torque is controlled based on the speed.

FIG. 7 shows the system configuration of the backlash control unit 12 of FIG. 1B in the third embodiment. In FIG. 7, the difference from FIG. 2 of the first embodiment is that the backlash speed control unit 80 is provided as the acceleration torque generation unit instead of the limiter 21, and the estimated torsional angular velocity ω calculated by the internal model of the calculation unit 24 is provided. _BL ^ is input to the backlash speed control unit 80, and the torque command T _s is output from the backlash speed control unit 80, and the other parts are configured in the same manner as in FIG.

Further, the operation of determining ON / OFF of the acceleration torque switch 23 and the friction compensation switch 26 in consideration of whether or not it is a backlash section according to the switch flowchart (flow of FIG. 4) of the determination unit 22 is the operation of the first embodiment. It is done in the same way.

The backlash speed control unit 80 takes in the estimated torsional velocity ω _BL ^ calculated by the internal model of the arithmetic unit 24, and controls the speed so that the estimated torsional velocity ω _BL ^ becomes the set speed command ω _BL ^* ( For example, PI control), and is configured as shown in FIG. 8, for example.

8, 81 is a speed command setting unit which is the speed command omega _BL ^* is set, in the speed instruction omega _BL ^* subtractor 82, the estimated torsional angular velocity calculated by the internal model of the arithmetic unit 24 omega _BL ^ The deviation from is taken.

The deviation output of the subtractor 82 is multiplied by the positive proportional gain KP _BL of the gain multiplier 83 and the positive integral gain KI _{BL of the} gain multiplier 84, respectively. The output of the gain multiplier 84 is integrated by the integrator 85.

The output of the output of the gain multiplier 83 and (P control component) integrator 85 (I control component) are added by the adder 86, the addition output as the torque command T _s, the torque command T _s selection of acceleration torque switch 23 Input to the side contact.

As described above, in the third embodiment, the acceleration torque is determined by controlling the torsional angular velocity ω _BL of the motor shaft 2 with respect to the load shaft 4. The speed command ω _BL ^* for the estimated torsional velocity ω _BL ^ is set considering the positive and negative of the direction in which the backlash is to be exited.

Here, notes on backlash speed control will be described. Terms of speed command omega _BL ^*, backlash is controlled at a high speed at first in the interval, but later gear omega _BL ^* is desirable so as to decelerate to shock exposed to (gear 3) does not generate sound, backlash Since there is a risk of hitting the gears at high speed due to the model data related to the angle of and the plant error, the impact may be constant with ω _BL ^*, which does not generate sound within the backlash section.

Regarding the integrated gain KI _BL of PI control, it is difficult to expect sufficient speed tracking by the integral term because the period of stay in the backlash section is generally 1 s or less, and the integrator 85 is abnormal when entering the backlash section. The KI _BL may be set to 0, that is, it may be simplified to only proportional control, in consideration of the fact that a mechanism for appropriately resetting the values does not have a value is required for mounting and the control system is complicated.

The output torque command T _s may be output through the limiter because the PI control may calculate a large torque command, but at that time, the absolute value of the upper and lower limits of the limiter is set to the limiter 21 installed in the first embodiment. If the value is less than the absolute value of, the acceleration performance will be inferior to that of the first embodiment. Therefore, it is necessary to carefully determine the upper and lower limits of the limiter.

FIG. 13 shows the effect of BL speed control in the backlash section. In FIG. 13, Example 1 using only the limiter and Example 3 using BL speed control are compared. In the simulation, the speed command ω _BL ^* of the backlash speed control unit 80 was kept constant in consideration of the generation of sound due to acceleration exceeding the responsiveness. Further, PI control is simplified to P control only for the above-mentioned reason.

13 (a) shows the transition of the torsion angle θ _BL of the plant of FIG. 1 (a), line 121 is a simulation result in the case of only the limiter (Example 1), and line 122 is an example using BL speed control. The simulation results in the case of 3 are shown respectively.

13 (b) shows the transition of the torsional angular velocity ω _BL of the plant of FIG. 1 (a), line 123 is a simulation result in the case of only the limiter (Example 1), and line 124 is an example using BL speed control. The simulation results in the case of 3 are shown respectively.

In the graph of the torsion angle θ _BL in FIG. 13 (a), Example 1 (line 121) passed through the backlash slightly earlier, but no significant difference was observed. Then, I would like to confirm the speed control performance by looking at the graph of FIG. 13 (b). In the first embodiment (line 123), since the torque is constant, the torsion angular velocity ω _BL is accelerated at a constant acceleration. On the other hand, in Example 3 (line 124), the torsion angular velocity ω _BL is maintained at a constant velocity by speed control.

From this, if the backlash angle θ _BL of the actual plant is larger than the model data, the sound is generated by excessive acceleration in the first embodiment, whereas the speed is maintained in the third embodiment. It can be said that the problem does not occur.

Therefore, in Example 3, BL control that is more resistant to parameter errors than in Example 1 is possible. In addition, if BL speed control is controlled at high speed at the beginning of the backlash section and then decelerated so that the impact of the gear (gear 3) does not generate sound, it will replace the robustness to parameter error. It is also possible to improve the responsiveness.

As described above, according to the third embodiment, by determining the backlash section and outputting the torque for appropriately controlling the torsional angle speed of the motor shaft with respect to the load shaft, the collision noise of the gear when the backlash is exited is suppressed. It is possible to perform control within the backlash section, such as being able to do so, not lowering the responsiveness more than necessary, not causing chattering of the control output, and being less susceptible to parameter errors than in Example 1, and the load is applied via gears. The operating performance of the driving motor drive system can be improved.

In addition, for the prior art documents, in order to obtain a vibration component that does not require the use of a speed sensor, considers responsiveness and impact, can be realized only by changing the control without requiring a special structure. It has the advantages of not requiring repeated test runs, no need to create a table, and robust control of parameter errors compared to tables.

(Example 4)
The disturbance compensation of Example 2 and the BL speed control of Example 3 can be used in combination without adversely affecting each other due to the difference in the change position. Therefore, in the fourth embodiment, the backlash control unit 12 of FIG. 1 (b) is configured as shown in FIG. 9 by combining the second embodiment and the third embodiment.

The difference from FIG. 5 in FIG. 9 is that the limiter 21 is replaced by the backlash speed control unit 80, and the estimated torsional angular velocity ω _BL ^ output from the internal model of the calculation unit 54 is input to the backlash speed control unit 80. The three points are that the limit torque command T _lim of the limiter output is replaced with the torque command T _s of the output of the backlash speed control unit 80. Other system configurations and variable names are the same as in FIG.

The system configuration, variables, and operations other than backlash control shall be based on FIGS. 1, 4, 6, 7, and 8.

According to the fourth embodiment, the backlash section is determined, the torque for appropriately controlling the torsional angular velocity of the motor shaft with respect to the load shaft is output, and the backlash is compensated by comparing the detection and estimation of the motor angular velocity. It is possible to suppress the collision noise of the gear when it comes off, do not lower the responsiveness more than necessary, do not cause chattering of the control output, prevent the deterioration of control performance caused by the estimation error due to disturbance, the influence of the parameter error compared to Example 1. It is possible to control the backlash section so that it is less susceptible to damage, and it is possible to improve the operating performance of the motor drive system that drives the load via gears.

In addition, for the prior art documents, it is necessary to repeat test operation to obtain the vibration component, which considers responsiveness and impact, can be realized only by changing the control without requiring a special structure. It has advantages such as no need to create a table, consideration of the influence of disturbance, and robust control of parameter error compared to a table.

Claims (7)

1. A backlash control device in an electric motor drive system that drives a load via gears by an electric motor connected to an inverter.
   It has a means to determine the backlash section, a torque command corresponding to the set speed command is input, a process to generate acceleration torque for accelerating the torque in the backlash section, or a direction to exit the backlash section. It is equipped with a backlash control unit that calculates the backlash-considered torque command by performing at least one of the friction compensation torque addition processing for canceling the torque component in the opposite direction.
   A backlash control device in an electric motor drive system, which controls the inverter based on the calculated backlash-considered torque command.
2. The backlash control unit
   An acceleration torque generator that generates acceleration torque when it is decided to perform the process of generating acceleration torque.
   The relationship between the load torque with respect to the twist angle between the motor shaft between the motor and the gear and the load shaft between the gear and the load in the back crash section is defined by the back crash block set with a dead zone, and the motor side block and back crash block. , It has an internal model that expresses the motor drive system by dividing it into load side blocks, and the estimated motor angular speed is calculated from the output torque of the acceleration torque generator by the internal model, and is estimated for the load shaft of the motor shaft. A calculation unit that calculates and outputs the torsion angle speed and the estimated torsion angle or estimated load torque of the motor shaft with respect to the load shaft.
   When the execution of the friction compensation torque addition process is decided, the friction compensation torque addition unit that adds the friction compensation torque to the output torque of the acceleration torque generation unit, and the friction compensation torque addition unit.
   The estimated torsion angle or estimated load torque of the motor shaft with respect to the load shaft calculated by the calculation unit, the estimated torsional angle speed of the load shaft of the motor shaft, and the torque command corresponding to the speed command are input, and in the backlash section. It is determined whether or not there is, and based on the determination result, the processing for generating the acceleration torque in the acceleration torque generating unit is executed, the decision not to be performed, and the friction compensation torque adding processing in the friction compensation torque adding unit are performed. The backlash control device in the motor drive system according to claim 1, further comprising a determination unit for determining non-implementation.
3. The backlash control device in an electric motor drive system according to claim 2, wherein the acceleration torque generating unit has a limiter that limits an upper limit and a lower limit on an input torque command.
4. The second aspect of the present invention is characterized in that the acceleration torque generating unit has a backlash speed control unit that controls the speed so that the estimated torsional angular velocity calculated by the internal model becomes a set speed command. Backlash control device in the motor drive system of.
5. The internal model has a disturbance compensation system that takes a deviation between the detected motor angular velocity that detects the angular velocity of the motor and the calculated estimated motor angular velocity, and feeds back the deviation to the internal model so that the deviation becomes zero. The backlash control device in the electric motor drive system according to any one of claims 2 to 4, wherein the back crash control device is provided.
6. The determination unit
   When the estimated torsion angle of the motor shaft with respect to the load shaft is within the backlash phase range of the gear, or when the estimated load torque is near zero, it is determined to be a backlash section, and other than that, it is not a backlash section. The first determination process to determine that
   When the backlash section is determined by the first determination process, the second determination process for determining whether or not the torque command corresponding to the speed command is within the set dead zone,
   When it is determined by the second determination process that it is not within the dead zone, a third determination process for determining whether or not the estimated torsional angular velocity is within the set dead zone is performed.
   When it is determined by the first determination process that it is not a backlash section and when it is determined by the second determination process that the torque command is within the dead zone, the process of generating the acceleration torque is not performed and friction Decided not to implement the compensation torque addition process,
   When it is determined by the third determination process that the estimated torsional angular velocity is within the dead zone, it is determined to perform the process of generating the acceleration torque, and it is determined not to perform the friction compensation torque addition process.
   According to claim 2, when it is determined by the third determination process that the estimated torsional angular velocity is not within the dead zone, it is determined to carry out the process of generating the acceleration torque and the friction compensation torque addition process. 5. The backlash control device in the electric motor drive system according to any one of 5.
7. A backlash control method in an electric motor drive system, which comprises executing the backlash control device in the electric motor drive system according to any one of claims 1 to 6.

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