JP4123145B2 - Speed control device for electric vehicle - Google Patents

Description

    The present invention relates to a speed control device for an electric vehicle, and is devised so that the pitching phenomenon can be quickly and reliably suppressed even when the electric vehicle is pitched while the electric vehicle is stopped by a cargo handling operation or the like. The cargo handling operation refers to, for example, lifting and lowering a load loaded on a fork in an electric forklift to transfer the load.

  In an electric vehicle such as an electric forklift or an electric vehicle, a direct current voltage of a battery is converted into an alternating current voltage by an inverter to drive the alternating current motor, and a driving force during traveling is obtained using the alternating current motor as a drive source. As this type of drive motor, an induction motor is frequently used, and a vector control system is adopted as a speed control system of the induction motor (see, for example, Patent Document 1). FIG. 6 is a block diagram showing a speed control device for an electric vehicle using a vector control method according to the prior art.

  As shown in FIG. 6, the speed control device mainly includes a speed command control unit 100, a vector control unit 200, and a motor drive command control unit 300.

An outline of the control operation of this speed control device is as follows. That is, the speed command control unit 100 outputs a speed command ω ^* corresponding to (proportional to) the amount of depression of the accelerator 10. The vector control unit 200 outputs a two-phase torque current command Iq ^* and an excitation current command I ₁ d ^{* for} setting the actual speed (detected speed) ω of the electric vehicle to the speed command ω ^* . The motor drive command control unit 300 outputs three-phase voltage commands (motor drive commands) Vu ^* , Vv ^* , Vw ^* corresponding to the current commands Iq ^* , I ₁ d ^* .

The inverter 20 converts the direct current of the battery B into a three-phase alternating current in accordance with the voltage commands (motor drive commands) Vu ^* , Vv ^* , Vw ^* and supplies the three-phase alternating current to the traveling induction motor 30. As a result, the induction motor 30 is driven to run the electric vehicle. As a result, the speed of the electric vehicle can be controlled according to the amount of depression of the accelerator 10.

  The rotation speed of the induction motor 30 is detected by a rotation speed sensor (pulse pickup) 40, and a pulse signal P indicating the rotation speed is output from the rotation speed sensor 40. Based on this pulse signal P, The detected speed ω, which is the actual speed of the electric vehicle, is obtained.

  Next, the detailed configuration and operation of each control unit 100, 200, 300 of the speed control device described above will be described.

  The speed command control unit 100 includes an accelerator input processing unit 101, a cushion processing unit 102, and a torque current command limit processing unit 103.

The accelerator input Vin 101 corresponding to the amount of depression of the accelerator 10 is input to the accelerator input processing unit 101. Then, the accelerator input processing unit 101 outputs a speed command ω ^* corresponding to the accelerator voltage Vin.
The cushion processing unit 102 outputs the speed command ω ^* after a certain time delay after the accelerator 10 is depressed.
The torque current command limit processing unit 103 outputs a torque current command limit value Iq-lim corresponding to the detected speed ω. The maximum value of the torque current command limit value Iq-lim is Iq0. Note that ωb is a base velocity.

  The vector control unit 200 includes a PI (proportional integral) calculation unit 201, a magnetic flux command unit 202, a slip calculation unit 203, a speed calculation unit 204, and the like.

The PI calculation unit 201 obtains the torque current command Iq ^* by performing PI calculation based on the deviation speed Δω that is the deviation between the speed command ω ^* and the detected speed ω, and the speed PI gains Kp and Ki. However, the value of the torque current command Iq ^* is limited with the torque current command limit value Iq-lim as an upper limit. The speed PI gains Kp and Ki are multiplied by a predetermined number by multipliers 205 and 206 as described later when the detected speed ω exceeds the base speed ωb.

The magnetic flux command unit 202 outputs a magnetic flux command λ ^* corresponding to the detected speed ω. The maximum value of the magnetic flux command λ ^* is λo. Note that ωb is a base velocity.

The magnetic flux command λ ^* is multiplied by a gain G in order to improve the response of the excitation current command I _1d ^* . Then, the excitation current command I _1d ^* is obtained through the M (mutual inductance) fluctuation compensation table 207 and the divider 208.
Further, the magnetic flux command λ ^* becomes the magnetic flux command λ ₁ ^* through the first-order lag portion 209. Note that τ ₂ is a second-order time constant.

The multiplication gain calculator 210 obtains a multiplication gain by dividing the fixed value Ido (= Mλo) by Id (= Mλ ₁ ^* ), and this multiplication gain is obtained by the multipliers 205 and 206 by the speed PI gain. Multiply by Kp, Ki. The multiplication gain is λ ₁ ^* = λo when the detection speed ω is lower than the base speed ωb, and is _{1 and} when the detection speed ω is higher than the base speed ωb, λ ₁ ^* <λo. Greater than 1.

Slip calculation unit 203, a flux command lambda ₁ ^* corresponding to the excitation current command I ₁ d ^*, the torque current command Iq ^*, obtaining a slip rate .omega.s. The speed calculation unit 204 obtains the detection speed ω from the pulse signal P. Then, the primary angular velocity ωo is obtained by adding the sliding velocity ωs and the detection velocity ω.

  The motor drive command control unit 300 includes a current control unit 301, coordinate conversion units 302 and 303, an integrator 304, a speed estimation unit 305, and the like.

The current control unit 301 calculates a value obtained by multiplying the excitation current command I ₁ d ^* and the torque current command Iq ^* by the gain Kid and the gain Klq, and the excitation current detection value I ₁ d and the torque current detection value I ₁ q. A two-phase excitation voltage command Vd ^* and a torque voltage command Vq ^* are obtained using the deviation and the primary angular velocity ωo. The two-phase excitation voltage command Vd ^* and the torque voltage command Vq ^* are converted into three-phase voltage commands (motor drive commands) Vu ^* , Vv ^* , and Vw ^* by the coordinate converter 303.
The excitation current detection value I ₁ d and the torque current detection value I ₁ q are obtained by coordinate-converting the detected three-phase currents Iu and Iw with the coordinate converter 302.

  The integrator 304 obtains a phase angle θ (an angle formed by the d-axis and the rotor) necessary for coordinate conversion from the primary angular velocity ωo.

The speed estimation unit 305 estimates the rotational speed of the induction motor 30 based on the excitation voltage command Vd ^* , the torque voltage command Vq ^* , and the detected three-phase currents Iu and Iw. When the rotation speed sensor 40 is not used, the estimated speed estimated by the speed estimating unit 305 is used instead of the detected speed ω.

In the speed control device shown in FIG. 6, when the depression amount (operation amount) of the accelerator 10 is the maximum, the speed command ω ^* is also the maximum, and the detected speed ω of the induction motor 30 matches the command speed command ω ^* . Torque current command Iq ^* is calculated by PI calculation.

When the amount of depression (operation amount) of the accelerator 10 is maximum and the speed command ω ^* is also maximized, the electric vehicle is driven without load (running without a load), or the amount of depression of the accelerator 10 (operation When the speed command ω ^* is made to run at a low speed by reducing the amount), the motor torque characteristic of the induction motor 30 has a sufficient margin with respect to the running load torque, so the speed command ω ^* and the detected speed (actual The vehicle travels with the speed (ω) substantially matched.

When the electric vehicle is run in a load (running with a load loaded) when the amount of depression (operation amount) of the accelerator 10 is maximum and the speed command ω ^* is also maximum, the motor torque characteristics of the induction motor 30 Travels at a point balanced with the travel load torque characteristics, and travel is performed in a state where the detected speed (actual speed) ω is lower than the speed command ω ^* .

When the electric vehicle is stopped, the speed command ω ^* is zero because the accelerator 10 is not depressed. In the prior art, when the speed command ω ^* becomes zero, the PI calculation unit 201 stops the control calculation, that is, the speed control is interrupted, and the induction motor 30 is set in a free state. In other words, no current is supplied to the induction motor 30, and when an external force is applied, the induction motor 30 is relatively easily rotated (free state) by an external force.

JP 2000-308399 A

    When an electric vehicle is stopped, a cargo handling operation (lift up / down, tilt forward / back tilt) resonates due to the natural vibration of the electric vehicle, and the electric vehicle swings up and down and back and forth (pitching operation). . When pitching occurs in this way, the motor rotating shaft of the induction motor (traveling motor) 30 rotates according to the pitching, although the entire electric vehicle is stopped. That is, even if the position of the wheel of the electric vehicle on the ground is constant, the electric vehicle pitches (relatively rotates) with respect to the stopped wheel. Therefore, the motor rotation shaft of the induction motor 30 is pitched by the electric vehicle. (Rotation: forward or reverse rotation with a small rotation angle).

  As described above, since the induction motor 30 is in a motor-free state while the electric vehicle is stopped, the pitching phenomenon is not suppressed and vibration (pitching) continues. Since the driver feels fear when the pitching becomes large, in reality, the cargo handling operation is carefully performed so that the pitching does not become large.

  An object of the present invention is to provide a speed control device for an electric vehicle that can quickly and surely suppress the pitching phenomenon even if the electric vehicle performs a cargo handling operation while the electric vehicle is stopped.

The configuration of the present invention that solves the above problems is based on a proportional-integral command obtained by proportional-integral calculation of a deviation speed that is a deviation between a speed command corresponding to the accelerator depression amount and a detected speed that is the actual speed of the electric vehicle. In addition, a traveling control device for an electric vehicle that controls the rotational drive of a traveling motor,
An accelerator input processing unit that generates a speed command according to the accelerator depression amount;
When the detected speed, which is the actual speed of the electric vehicle, and the speed command generated in the accelerator input processing unit are equal to or lower than a preset set speed, the detected speed is sampled every predetermined sampling period. When the difference between the maximum detection speed and the minimum detection speed is greater than a predetermined pitching detection level, a pitching detection unit that detects that a pitching phenomenon has occurred,
When the pitching detection unit does not detect a pitching phenomenon, the speed command generated by the accelerator input processing unit is output. On the other hand, when the pitching detection unit detects a pitching phenomenon, the accelerator input processing unit Instead of the generated speed command, a speed command adjusting unit that outputs a speed command having a value of zero,
A proportional-integral command obtained by proportional-integral calculation of a deviation speed, which is a deviation between the speed command output from the speed command adjusting unit and a detected speed that is an actual speed of the electric vehicle, is obtained, and the pitching detection unit And a proportional-integral calculation unit that stops the proportional-integral calculation when a set time elapses after the phenomenon is no longer detected.

In the speed control device for an electric vehicle according to the present invention, when the pitching phenomenon is detected, the motor is controlled by obtaining the torque current command Iq ^* by the PI calculation unit in a state where the speed command ω ^* is zero. A force that cancels the pitching is generated, and the pitching can be quickly and reliably suppressed.

  Hereinafter, embodiments of the present invention will be described based on examples. In addition, the same code | symbol is attached | subjected to the part which performs the same function as a prior art, and description of the overlapping part is simplified.

  FIG. 1 is a block diagram illustrating a speed control apparatus for an electric vehicle using a vector control method according to an embodiment of the present invention.

  As shown in FIG. 1, the speed control device mainly includes a speed command control unit 100A, a vector control unit 200, and a motor drive command control unit 300.

  The vector control unit 200, the motor drive command control unit 300, the accelerator 10, the inverter 20, the induction motor 30 that is a traveling motor, the rotation speed sensor 40, and the battery B have the same functions as those of the prior art shown in FIG. ing.

That is, the vector control unit 200 outputs a two-phase torque current command Iq ^* and an excitation current command I ₁ d ^{* for} setting the actual speed (detected speed) ω of the electric vehicle to the speed command ω ^* . The motor drive command control unit 300 outputs three-phase voltage commands (motor drive commands) Vu ^* , Vv ^* , Vw ^* corresponding to the current commands Iq ^* , I ₁ d ^* .

Then, the inverter 20 converts the direct current of the battery B into a three-phase alternating current in accordance with the voltage commands (motor drive commands) Vu ^* , Vv ^* , Vw ^* and supplies it to the traveling induction motor 30. As a result, the induction motor 30 is driven to run the electric vehicle. The rotation speed of the induction motor 30 is detected by a rotation speed sensor (pulse pickup) 40. A pulse signal P indicating the rotation speed is output from the rotation speed sensor 40. Based on this pulse signal P A detection speed ω is obtained.

A PI calculation unit (proportional integration calculation unit) 201 of the vector control unit 200 performs a PI calculation based on a deviation speed Δω that is a deviation between the speed command ω ^* and the detected speed ω and the speed PI gains Kp, Ki. To obtain the torque current command (proportional integral command) Iq ^* . Such a function of the PI calculation unit 201 is the same as that of the prior art. However, in this embodiment, the PI calculation unit 201 performs the above-described PI calculation even when the speed command ω ^* becomes zero. . That is, although details will be described later, even if the speed command ω ^* is zero, a torque current command Iq ^* is obtained so that the deviation speed Δω is zero, and according to the current commands Iq ^* and I ₁ d ^* The three-phase voltage commands (motor drive commands) Vu ^* , Vv ^* , Vw ^* are output, and current is supplied from the inverter 20 to the induction motor 30.

  The speed command control unit 100A newly includes a pitching detection unit 104 and a speed command adjustment unit 105 in addition to the accelerator input processing unit 101, the cushion processing unit 102, and the torque current command limit processing unit 103.

  Among these, the accelerator input processing unit 101, the cushion processing unit 102, and the torque current command limit processing unit 103 have the same functions as those of the prior art shown in FIG.

That is, the accelerator voltage Vin corresponding to the amount of depression of the accelerator 10 is input to the accelerator input processing unit 101. Then, the accelerator input processing unit 101 outputs a speed command ω ^* corresponding to the accelerator voltage Vin.
The cushion processing unit 102 outputs the speed command ω ^* after a certain time delay after the accelerator 10 is depressed.
The torque current command limit processing unit 103 outputs a torque current command limit value Iq-lim corresponding to the detected speed ω. The maximum value of the torque current command limit value Iq-lim is Iq0. Note that ωb is a base velocity.

The pitching detection unit 104 performs processing shown in the flowchart of FIG. 2 based on the speed command ω ^* output from the accelerator input processing unit 101 and passed through the cushion processing unit 102 and the detected speed (actual speed) ω. Thus, occurrence of pitching is detected.

First, the pitching detection operation is started under the condition (step 1 in FIG. 2) that both the speed command ω ^* and the detected speed ω are equal to or lower than the set speed (for example, 10 km / h).

  The pitching detection operation is continuously performed every predetermined sampling period (for example, every second). That is, the pitching detection operation is performed in the preceding sampling period (for example, 1 second), and the pitching detection operation is also performed in the sampling period (for example, 1 second) immediately following this sampling period. In this pitching detection operation, first, the detection speed ω is sampled continuously in each sampling period of 1 second, and the maximum detection speed ωmax and the minimum detection speed ωmin during this sampling period are extracted (step 2). When the difference between the maximum detection speed ωmax and the minimum detection speed ωmin is greater than a predetermined pitching detection level (step 3), it is determined that pitching has occurred (step 4).

  If it is determined that the pitching has occurred, the pitching detection signal α is output to the speed command adjustment unit 105 and the PI calculation unit 201. The pitching detection signal α is output every time pitching is detected in each sampling period.

  The sampling period is, for example, 1 second. This period is determined from the vibration frequency when various electric vehicles are pitched. This sampling period is conditioned on the existence of at least two speed peaks (the part that decreases after the speed increases) and at least two speed valleys (the part that increases after the speed decreases). It has been decided.

When the pitching detection signal α is not input, the speed command adjusting unit 105 passes the speed command ω ^* output from the accelerator output processing unit 101 as it is and sends it to the vector control unit 200.

On the other hand, when the pitching detection signal α is input, the speed command adjustment unit 105 does not pass the speed command ω ^* output from the accelerator output processing unit 101 as it is, and the speed command ω ^* whose value is zero ^. Is sent to the vector control unit 200 (see steps 11 and 12 in FIG. 3).

When the pitching detection signal α is input, the PI calculation unit 201 continues the PI calculation for a preset time (for example, 10 seconds) from the input time point even if the value of the speed command ω ^* is zero. To do. Therefore, when the pitching detection signal α is input one after another, the PI calculation is continued and the torque current command Iq ^* is continued from the time when the pitching detection signal α is input to the preset time. Output. After a preset time has elapsed since the last time when the pitching detection signal α was input, the PI calculation unit 201 stops the PI calculation, and the PI control is cut off (step 13 in FIG. 3). The electric motor 30 is in a free state.

Therefore, when the electric vehicle stops and performs the cargo handling operation or the like and the electric vehicle pitches, the rotating shaft of the induction motor 30 rotates (turns) even though the electric vehicle stops as a whole. The deviation speed Δω, which is the deviation between the command speed ω ^* (= zero) and the detected speed ω, has a certain value, and a torque current command Iq ^* obtained by PI calculation of the deviation speed Δω is output from the PI calculation unit 201. .

As a result, the vector control unit 200 outputs a two-phase torque current command Iq ^* and an excitation current command I ₁ d ^* for setting the detected speed ω resulting from pitching to the speed command ω ^* (= zero). The The motor drive command control unit 300 outputs three-phase voltage commands (motor drive commands) Vu ^* , Vv ^* , Vw ^* corresponding to the current commands Iq ^* , I ₁ d ^* . For this reason, the induction motor 30 generates a motor driving force that prevents the motor rotation shaft from rotating due to pitching. For this reason, a pitching phenomenon is suppressed quickly and reliably.

FIG. 4 shows the detected speed ω and the torque current command Iq ^* when a 1-ton load loaded on the fork is lowered by 30 cm from a position 2 m high and stopped in the electric forklift to which this embodiment is applied. The characteristics are shown. As shown in the figure, when pitching is detected, a torque current command Iq ^* that suppresses pitching is output, so that the detection speed ω resulting from pitching is suppressed to zero in a short time.

FIG. 5 shows the characteristics of the detected speed ω and the torque current command Iq ^* when a 1-ton load loaded on the fork is lowered by 30 cm from a position 2 m high and stopped in a conventional electric forklift. Yes. As can be seen from FIG. 5, the detection speed ω due to pitching has conventionally occurred over a long period of time.

  The present invention can be used for an electric vehicle such as an electric forklift or an electric vehicle.

It is a block block diagram which shows the speed control apparatus of the electric vehicle which concerns on the Example of this invention. It is a flowchart which shows pitching detection operation | movement. It is a flowchart which shows pitching suppression control. It is a characteristic view which shows the relationship between the detection speed when a pitching suppression control is performed, and a torque current command. It is a characteristic view which shows the relationship between the detection speed when not performing pitching suppression control, and a torque current command. It is a block block diagram which shows the speed control apparatus of the electric vehicle which concerns on a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Accelerator 20 Inverter 30 Induction motor 40 Rotation speed sensor 100, 100A Speed command control part 101 Accelerator input process part 102 Cushion process part 103 Torque current command limit process part 104 Pitching detection part 105 Speed command adjustment part 200 Vector control part 201 PI calculation 300 Motor drive command controller B Battery

Claims (1)

Controls the rotational drive of the motor for traveling based on a proportional-integral command that is a proportional-integral calculation of the deviation speed, which is the deviation between the speed command corresponding to the accelerator depression amount and the detected speed, which is the actual speed of the electric vehicle. An electric vehicle running control device,
An accelerator input processing unit that generates a speed command according to the accelerator depression amount;
When the detected speed, which is the actual speed of the electric vehicle, and the speed command generated in the accelerator input processing unit are equal to or lower than a preset set speed, the detected speed is sampled every predetermined sampling period. When the difference between the maximum detection speed and the minimum detection speed is greater than a predetermined pitching detection level, a pitching detection unit that detects that a pitching phenomenon has occurred,
When the pitching detection unit does not detect a pitching phenomenon, the speed command generated by the accelerator input processing unit is output. On the other hand, when the pitching detection unit detects a pitching phenomenon, the accelerator input processing unit Instead of the generated speed command, a speed command adjusting unit that outputs a speed command having a value of zero,
A proportional-integral command obtained by proportional-integral calculation of a deviation speed, which is a deviation between the speed command output from the speed command adjusting unit and a detected speed that is an actual speed of the electric vehicle, is obtained, and the pitching detection unit A traveling control apparatus for an electric vehicle, comprising: a proportional-integral calculation unit that stops the proportional-integral calculation when a set time elapses from the time when the phenomenon is no longer detected.

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