JP5313454B2 - Electric vehicle stop control method - Google Patents

Description

  The present invention includes an operation lever, an axle, a motor whose rotation is controlled by drive control means based on an operation instruction from the operation lever, a transmission mechanism that transmits the rotational force of the motor to the axle, and the rotation of the motor The present invention relates to a stop control method for an electric vehicle having a brake for stopping the vehicle.

  In general, an electric vehicle includes an axle, a motor, a transmission mechanism that transmits the rotational force of the motor to the axle, and an electromagnetic brake for braking the rotation of the motor.

  As the stop control of the electric vehicle, for example, as shown in Patent Document 1, when both the motor rotation speeds of the electric vehicle decrease to the minimum rotation speed threshold value that is substantially close to the stop speed, the brake that simultaneously activates the electromagnetic brake is performed. Control is known.

  Thereby, the stable stop with few stop posture changes can be performed. For this reason, it is not necessary to correct the attitude of the vehicle, and unnecessary operations can be eliminated. As a result, operability can be improved. Moreover, there is no shock due to sudden braking. Furthermore, wear of the electromagnetic brake can be suppressed.

  Further, a method of detecting the position of the magnetic pole of the rotor of the DC brushless motor is known as the rotation control of the motor of the electric vehicle. In this method, a Hall IC, which is a magnetic sensor, is provided in a stator having windings, a change in magnetic flux accompanying rotation of the rotor is detected by the Hall IC, and the detection signal is detected digitally, and the magnetic pole of the rotor is detected. The position is detected. In this case, if the rotor position detection accuracy is low, the speed detection accuracy is also low.

  As a conventional method of detecting the position of the magnetic pole of the rotor, for example, there is a magnetic rotary encoder described in Patent Document 2. In this magnetic rotary encoder, six Hall ICs are installed in the stator to detect the position of the magnetic pole of the rotor.

JP 2005-137055 A JP-A-6-88704

  By the way, as shown in Patent Document 1, it is preferable that the electromagnetic brakes are simultaneously operated after the rotational speeds of the motors of the electric vehicle are both substantially close to the stop speed.

  For this purpose, it is necessary to increase the stopping accuracy of the rotor and to perform the stopping control of the electric vehicle with high accuracy while minimizing the influence of the error component.

  Although systems using an encoder or resolver are also conceivable, these systems have a problem that although they are highly accurate, they lead to an increase in cost compared to a Hall IC.

  For this reason, in stop control of an electric vehicle, a low-cost and high-accuracy stop control method using an inexpensive Hall IC is required.

  The present invention has been made in consideration of such problems, and an electric vehicle capable of performing stop control of the electric vehicle with high accuracy by using an inexpensive Hall IC and minimizing the influence of error components. An object of the present invention is to provide a stop control method.

A stop control method for an electric vehicle according to a first aspect of the present invention includes an operation lever, an axle, a motor that is rotationally controlled by drive control means based on a steering angle of the operation lever , and the rotational force of the motor as an axle. In the stop control method for an electric vehicle having a transmission mechanism for transmitting and a brake for braking the rotation of the motor, the electric vehicle is based on a series of pulse signals generated with the rotation of the motor. A speed detection circuit for detecting a rotation speed of the motor, and a timer for outputting a clock; based on the steering angle of the operation lever , the motor is decelerated and controlled to stop rotating by the drive control means; then, from the time the product is detected internal signal indicating the stop state based on the steering angle of the operation lever, of the pulse signal from the speed detecting circuit Upon expiration of the times it falls in, and starts counting the clock from the timer, characterized in that stopping the rotation of the motor by the brake at the time of counting the clock by a predetermined number.
According to a second aspect of the present invention, there is provided an electric vehicle stop control method comprising: an operation lever; an axle; a motor that is rotationally controlled by a drive control means based on a steering angle of the operation lever ; and a rotational force of the motor. In a stop control method for an electric vehicle having a transmission mechanism for transmitting to an axle and a brake for braking the rotation of the motor, the electric vehicle is based on a series of pulse signals generated as the motor rotates. It includes a speed detection circuit for detecting the rotational speed of the motor, and a timer for outputting a clock, and a counter for outputting an overflow signal each time a predetermined number of counts clock from the timer Te, the said operating lever Based on the steering angle, the motor is controlled to decelerate toward the rotation stop by the drive control means, and then based on the steering angle of the operation lever. From the time the product is detected internal signal indicating the stop state, at the time of the lapse of twice the fall of the pulse signal from the speed detecting circuit, and starts counting the clock at the counter, the counting and controlling the motor according to the speed command value decreases stepwise in response to two or more number of output times of the overflow signal from the vessel.

  As a result, it is possible to perform stop control of the electric vehicle with high accuracy by using an inexpensive Hall IC and minimizing the influence of the error component.

  In the present invention, the speed detection circuit includes at least three magnetic sensors arranged to face the rotor of the motor, and the change in the plurality of magnetic poles accompanying the rotation of the rotor is a three-phase digital waveform. And a pulse generation circuit that generates the series of pulse signals reflecting each rising edge and each falling edge of the three-phase digital waveform, and outputs to the output from the pulse generation circuit. Based on this, the rotational speed of the rotor may be detected.

  In this case, the pulse generation circuit includes a first logic circuit that outputs an exclusive OR of the first phase digital waveform and the second phase digital waveform among the three phase digital waveforms, and the three phase digital waveforms. Among the digital waveforms, a second logic circuit that outputs an exclusive OR of the third-phase digital waveform and the output of the first logic circuit is provided. You may make it make the time of falling pass be the said reference time of the opportunity which stops rotation of the said motor with the said brake.

  It is preferable that a speed detection cycle is a period from the rising edge of the output of the second logic circuit to the next arbitrary rising edge or a period from the falling edge to the next arbitrary falling edge.

  The magnetic detection circuit may include three magnetic sensors, and the three magnetic sensors may be arranged 30 ° apart from each other along the rotation direction of the rotor. In this case, it is advantageous in reducing the cost when detecting the forward rotation speed of the rotor.

  In addition, the magnetic detection circuit includes a first magnetic sensor unit that outputs a first detection signal of three phases for detecting the forward rotation speed of the rotor, and a three-phase first sensor for detecting the reverse rotation speed of the rotor. A second magnetic sensor unit that outputs two detection signals, and based on a control signal indicating normal rotation or reverse rotation of the rotor, the three-phase first digital waveform from the first magnetic sensor unit or the second You may make it have a selection circuit which selects the 3rd phase 2nd digital waveform from a magnetic sensor part. In this case, not only the forward rotation speed of the rotor but also the reverse rotation speed of the rotor can be detected, which is highly versatile.

  The first magnetic sensor unit is arranged in the order of a first phase first magnetic sensor, a second phase first magnetic sensor, and a third phase first magnetic sensor along the forward rotation direction of the rotor. And the second magnetic sensor unit is arranged to be spaced apart from each other by 30 ° along the forward rotation direction of the rotor, and the second magnetic sensor unit includes the second magnetic sensor of the first phase and the third phase of the third phase along the reverse rotation direction of the rotor. The second magnetic sensor and the second phase second magnetic sensor may be arranged in this order, and may be arranged 30 ° apart from each other along the reverse direction of the rotor. In this case, it is advantageous in reducing the cost when detecting the forward rotation speed and the reverse rotation speed of the rotor.

  As described above, according to the stop control method for an electric vehicle according to the present invention, it is possible to perform stop control of the electric vehicle with high accuracy by using an inexpensive Hall IC and minimizing the influence of error components. it can.

  Hereinafter, an embodiment of an electric vehicle stop control method according to the present invention will be described with reference to FIGS.

  As shown in FIG. 1, electrically powered vehicle 100 according to the present embodiment has a motor whose rotation is controlled by electronic control unit 104 (ECU) based on operation instructions from operation lever 82, axle 102, and operation lever 82. 10, a transmission mechanism 106 (mission) for transmitting the rotational force of the motor 10 to the axle 102, and an electromagnetic brake 108 for braking the rotation of the motor 10. For example, a DC brushless servomotor can be used as the motor 10.

  The electronic control unit 104 detects the rotational speed of the CPU 58, the brake drive circuit 110 that controls the drive of the electromagnetic brake 108 based on the braking signal from the CPU 58, and the rotor 12 (see FIG. 2) built in the motor 10. For example, the speed detection circuit 50 supplied to the CPU 58, the motor drive circuit 112 for controlling the rotational drive of the motor 10 based on the drive control signal from the CPU 58, and the steering angle of the operation lever 82 are detected, and a digital signal (operation signal) is detected. And an accelerator detection circuit 114 that converts the data into Sd) and supplies the converted data to the CPU 58. In addition, as described later, a timer 86 (see FIG. 11), a counter 94 (see FIG. 14), and the like are installed.

  Examples of the control form include speed control of the electric vehicle 100 and stop control described later. That is, in speed control, for example, when the user operates the operation lever 82 to move the electric vehicle 100 at a desired speed, the steering angle of the operation lever 82 at that time is determined by the accelerator detection circuit 114 using the operation signal Sd. Is converted into and input to the CPU 58. The CPU 58 monitors the rotational speed of the rotor 12 from the speed detection circuit 50 and sends a drive control signal to the motor drive circuit 112 so that the rotational speed of the rotor 12 becomes the rotational speed indicated by the input operation signal Sd. The rotational drive of the motor 10 is controlled by outputting.

  In order to perform such speed control of the electric vehicle 100 and stop control described later with high accuracy, it is important to detect the rotational speed of the rotor 12 with high accuracy.

  Here, speed detection circuit 50 used in stop control of electric vehicle 100 according to the present embodiment will be described with reference to FIGS.

  First, the motor 10 applied to the electric vehicle 100 is an inner rotor type motor 10 having a rotor 12 and a stator 14 as shown in FIG.

  The rotor 12 includes a cylindrical casing 16 and a rotor shaft 18 that extends in the axial direction at the center of the casing 16. As shown in FIG. 3, a permanent magnet 20 is disposed inside the housing 16 along the inner wall of the housing 16, and is configured as an 8-pole motor 10, for example. A detection magnet 22 is installed in a portion of the rotor 12 that faces the stator 14. The permanent magnet 20 is installed for rotating the rotor 12, and the detection magnet 22 is installed for detecting the speed of the rotor 12.

  The detection magnet 22 is magnetized by alternately arranging N poles and S poles so as to correspond to the magnetic pole positions of the motor 10. Therefore, the detection magnet 22 has eight boundaries (the first boundary 24a to the eighth boundary 24h) with respect to the boundary between the N pole and the S pole.

  On the other hand, as shown in FIG. 4, the stator 14 has twelve slots (first slot 26a to twelfth slot 261) at equal intervals along the circumference and, for example, in the clockwise direction, the first slot 26a and the second slot. The second slot 26b, the third slot 26c,... Are arranged in this order. Among them, the first slot 26a, the fourth slot 26d, the seventh slot 26g, and the tenth slot 26j are wound with the first phase winding, and the second slot 26b, the fifth slot 26e, the eighth slot 26h, and the A second phase winding is wound around the 11th slot 26k, and a third phase winding is wound around the third slot 26c, the sixth slot 26f, the ninth slot 26i and the twelfth slot 26l.

  Further, the stator 14 is provided with a hole 28 into which the end of the rotor shaft 18 is inserted at the center thereof, and a mounting plate having a U-shape, for example, is formed so as to surround the hole 28 around the hole 28. 30 is installed. Further, around the hole 28, there are a first connection terminal portion 32a for the first phase winding, a second connection terminal portion 32b for the second phase winding, and a third connection for the third phase winding. A connection terminal portion 32c is provided.

  Six magnetic sensors (first magnetic sensor 34 a to sixth magnetic sensor 34 f) are arranged on the surface (for example, the upper surface) of the mounting plate 30 facing the detection magnet 22 of the rotor 12.

  Specifically, when the reference line m passing through the center position of the hole 28 and passing through the centers of the fifth slot 26e and the eleventh slot 26k is considered, the upper surface of the mounting plate 30 is on the reference line m. In addition, the first magnetic sensor 34a is installed at a position on the fifth slot 26e side, and the first magnetic sensor 34a is spaced from the first magnetic sensor 34a along the circumference of the hole 28 by, for example, 30 ° clockwise. The second magnetic sensor 34b is installed, and the third magnetic sensor 34c is installed at a position 30 ° away from the second magnetic sensor 34b along the circumference of the hole 28.

  Similarly, a fourth magnetic sensor 34d is installed at a position on the reference line m on the upper surface of the mounting plate 30 and on the eleventh slot 26k side, and the circle of the hole 28 extends from the fourth magnetic sensor 34d. For example, a fifth magnetic sensor 34e is installed at a position spaced 30 ° in the counterclockwise direction along the circumference, and a sixth magnetic sensor is disposed at a position spaced 30 ° along the circumference of the hole 28 from the fifth magnetic sensor 34e. 34f is installed.

  Among the first magnetic sensor 34a to the sixth magnetic sensor 34f, the first magnetic sensor 34a to the third magnetic sensor 34c are for detecting the forward rotation speed of the rotor 12, and the first magnetic sensor 34a is the first magnetic sensor 34a. The second magnetic sensor 34b corresponds to the second phase, and the third magnetic sensor 34c corresponds to the third phase. Therefore, in other words, the first magnetic sensor 34a to the third magnetic sensor 34c are arranged in the order of the first magnetic sensor 34a, the second magnetic sensor 34b, and the third magnetic sensor 34c along the forward rotation direction of the rotor 12. And 30 ° apart from each other along the forward rotation direction of the rotor 12.

  Similarly, the fourth magnetic sensor 34d to the sixth magnetic sensor 34f are for detecting the reverse rotation speed of the rotor 12, the fourth magnetic sensor 34d corresponds to the first phase, and the fifth magnetic sensor 34e is the first one. Corresponding to the three phases, the sixth magnetic sensor 34f corresponds to the second phase. Therefore, in other words, the fourth magnetic sensor 34d to the sixth magnetic sensor 34f are arranged in the order of the fourth magnetic sensor 34d, the fifth magnetic sensor 34e, and the sixth magnetic sensor 34f along the reverse direction of the rotor 12. They are arranged and arranged 30 ° apart from each other along the reverse direction of the rotor 12.

  The first magnetic sensor 34a to the sixth magnetic sensor 34f are each configured by a Hall IC. The Hall IC is a magnetic sensor in which a Hall element and a logic circuit are integrated into an IC, and detects the magnetic pole (N pole or S pole) of the detection magnet 22 of the rotor 12 and the strength of the magnetic pole by the electromagnetic phenomenon of the Hall element. . Therefore, when the rotor 12 rotates, an analog voltage signal proportional to the magnetic flux density is output from the Hall element. The logic circuit shapes the analog voltage signal from the Hall element and outputs it as a digital waveform corresponding to the polarity of the magnetic field, for example, a high-level digital waveform at the N pole and a low-level digital waveform at the S pole. In the present embodiment, for example, an open collector output type Hall IC having an output transistor is used.

  The speed detection circuit 50 according to the present embodiment includes a magnetic detection circuit 52, a rotor position detection circuit 54, a pulse generation circuit 56, and a CPU 58, as shown in FIG. The CPU 58 operates at least a rotor position detecting means 60 and a rotor speed detecting means 62 as software.

  The magnetic detection circuit 52 includes a first magnetic sensor unit 64a including a first magnetic sensor 34a to a third magnetic sensor 34c, and a second magnetic sensor unit 64b including a fourth magnetic sensor 34d to a sixth magnetic sensor 34f.

  The rotor position detection circuit 54 outputs the digital waveform from the magnetic detection circuit 52, that is, the three-phase first digital waveform from the first magnetic sensor unit 64a and the three-phase second digital waveform from the second magnetic sensor unit 64b. Waveform shaping that has a pull-up resistor 66 to be stabilized, a noise filter 68 (low-pass filter) that suppresses high-frequency components (noise), and a Schmitt trigger function, and shapes a waveform that has been distorted by the noise filter 68 into a pulse waveform. Based on a control signal Sc indicating normal rotation or reverse rotation of the rotor 12 from the circuit 70 and the CPU 58, a three-phase first digital waveform or a three-phase second digital waveform is switched and selected, and a three-phase rotor position detection pulse is selected. And a selection circuit 72 that outputs as Sa (first phase rotor position detection pulse Sa1 to third phase rotor position detection pulse Sa3). .

  The pulse generation circuit 56 is a circuit that generates a series of pulse signals that reflect each rising edge and each falling edge of the three-phase rotor position detection pulse Sa from the selection circuit 72. That is, the pulse generation circuit 56 performs exclusive OR of the first-phase rotor position detection pulse Sa1 and the second-phase rotor position detection pulse Sa2 among the three-phase rotor position detection pulses Sa from the selection circuit 72. The first logic circuit 74 for outputting, and the second logic circuit 76 for outputting the exclusive OR of the third-phase rotor position detection pulse Sa3 and the output of the first logic circuit 74 as the rotor speed detection pulse Sb.

  The rotor position detection means 60 operated by the CPU 58 detects the position of the rotor 12 based on the three-phase rotor position detection pulse Sa from the selection circuit 72, and the rotor speed detection means 62 operated by the CPU 58 is a pulse generation circuit 56. The rotational speed (forward rotation speed or reverse rotation speed) of the rotor 12 is detected based on the rotor speed detection pulse Sb from. Further, the CPU 58 controls the rotational drive of the motor 10 based on the detected rotational speed so that the rotational speed indicated by the generated speed command value or the external speed command value is obtained. In FIG. 5, the control system of the motor 10 is not shown.

  For example, when detecting only the rotor position and the normal rotation speed during the normal rotation of the rotor 12, the speed detection circuit 50a according to the modification shown in FIG. 6 can be used.

  In the speed detection circuit 50a according to this modification, the second magnetic sensor unit 64b (the fourth magnetic sensor 34d to the sixth magnetic sensor 34f) relating to the reverse rotation of the rotor 12 is omitted, and accordingly, the pull-up resistor 66 These components, the noise filter 68, and the waveform shaping circuit 70 may be partially omitted, and the selection circuit 72 may be omitted.

  Here, in the speed detection circuit 50 according to the present embodiment, signal processing of a digital waveform output from one magnetic sensor, for example, the first magnetic sensor 34a will be described with reference to FIGS. 7A to 7C.

  As the rotor 12 rotates forward, for example, the magnetic pole facing the first magnetic sensor 34a changes in order, for example, N pole → S pole → N pole → S pole, so that the output transistor of the first magnetic sensor 34a. Is turned off in a period facing the N pole and turned on in a period facing the S pole, for example.

  Since the pull-up resistor 66 is connected to the output of the first magnetic sensor 34a, when the output transistor is OFF, the output voltage is raised to near the power supply voltage Vcc. Therefore, as shown in FIG. 7A, the output of the first magnetic sensor 34a is surely at a high level during the period in which the first magnetic sensor 34a is opposed to, for example, the N pole, and is reliably at a low level in the period opposed to the S pole. It becomes.

  In the output of the first magnetic sensor 34a, a high frequency component (noise) is suppressed by the noise filter 68 at the subsequent stage. However, the output waveform of the first magnetic sensor 34a is a first-order lag waveform in which the rise and fall correspond to the time constant of the noise filter 68, as shown in FIG. 7B.

  The output of the first magnetic sensor 34a that has risen and fallen by the noise filter 68 is shaped into a pulse waveform by the Schmitt trigger function of the waveform shaping circuit 70 at the subsequent stage, as shown in FIG. 7C. Specifically, the waveform shaping circuit 70 is set to a low level when the output (output voltage) of the noise filter 68 becomes equal to or higher than the first threshold voltage Vtp, and when it becomes equal to or lower than the second threshold voltage Vtn (<Vtp). To a high level. The waveform shaping circuit 70 also prevents chattering.

  On the other hand, the selection circuit 72 outputs the three-phase first digital waveform corresponding to the first magnetic sensor unit 64a output from the waveform shaping circuit 70 and the three-phase second digital waveform corresponding to the second magnetic sensor unit 64b, Based on the control signal Sc indicating normal rotation or reverse rotation of the rotor 12 from the rotor position detecting means 60 operated by the CPU 58, switching is selected and output as a three-phase rotor position detection pulse Sa. An example of a three-phase rotor position detection pulse Sa when the rotor 12 is rotating forward is shown in FIG. 8A.

  The three-phase rotor position detection pulse Sa is used to detect forward rotation or reverse rotation of the rotor 12 and further to detect the position of the magnetic pole of the rotor 12. Of course, the speed of the rotor 12 can be detected at a timing of 4 cycles (pulse cycle Ta) per rotation of the rotor, but the detection accuracy is low.

  In the pulse generation circuit 56, an exclusive OR of the first phase rotor position detection pulse Sa 1 and the second phase rotor position detection pulse Sa 2 is output from the first logic circuit 74, and the second logic circuit 76 outputs the second logic circuit 76. An exclusive OR of the three-phase rotor position detection pulse Sa3 and the output of the first logic circuit 74 is output. That is, the rotor speed detection pulse Sb is generated by a 3-input exclusive OR function. The waveform of the rotor speed detection pulse Sb is shown in FIG. 8B.

  A truth table of the pulse generation circuit 56 is shown in FIG. In this truth table, if all of the first-phase rotor position detection pulse Sa1 to the third-phase rotor position detection pulse Sa3 are “0” or “1”, it is an abnormal output due to a disconnection or short circuit of the harness. The CPU 58 performs error processing such as motor stop.

  The speed detection circuit 50 according to the present embodiment detects the rotational speed (forward rotation speed and reverse rotation speed) of the rotor 12 based on the output from the pulse generation circuit 56. Since the pulse period of the rotor speed detection pulse Sb output from the pulse generation circuit 56 is 1/3 of the pulse period Ta of the rotor position detection pulse Sa, it is based on the rotor speed detection pulse Sb output from the pulse generation circuit 56. By detecting the speed of the rotor 12, the detection accuracy can be improved as compared with the case of using the three-phase rotor position detection pulse Sa.

  As the detection timing, as a first method, it is conceivable that the timing at which the pulse waveform changes, that is, the period from the fall to the next rise and the period from the rise to the next fall are used as the speed detection period. . In this case, since 24 speed detection cycles arrive during one rotation of the rotor 12, the speed of the rotor 12 can be detected with high accuracy.

  However, the start point of each speed detection period is often influenced by various error components. Examples of error components include a detection magnet error, a magnetic sensor error, a noise filter error, and a CPU error.

  The detection magnet error includes an error in the magnetizing range of the detection magnet 22 and an installation error with respect to the rotor 12, and an arrangement error of the actual first boundary 24a to the eighth boundary 24h with respect to the ideal first boundary 24a to the eighth boundary 24h. Refers to ingredients. The magnetic sensor error includes a reading error of the first magnetic sensor 34a to the third magnetic sensor 34c and an attachment error with respect to the stator 14 when detecting the normal rotation speed of the rotor 12, and when detecting the reverse rotation speed of the rotor 12. The reading error of the fourth magnetic sensor 34d to the sixth magnetic sensor 34f and the mounting error with respect to the stator 14 are included. The noise filter error includes a time constant error caused by variations in circuit constants of circuit elements. The CPU error includes a quantization error when converting an analog signal to a digital signal. Of these, the CPU error depends on the performance of the CPU 58 itself, and is therefore excluded from the error components described above.

  As shown in FIG. 7B, the time constant error is generated when the output waveform of the noise filter 68 becomes a first-order lag waveform due to the CR time constant.

  That is, the pulse waveform (see FIG. 7C) output from the waveform shaping circuit 70 at the subsequent stage ideally has a falling point almost simultaneously with a rising point of the output waveform of the noise filter 68 (see FIG. 7B). In other words, the rising point is almost simultaneously with the falling point of the output waveform of the noise filter 68.

  However, since the output waveform of the noise filter 68 is a first-order lag waveform, the output (output voltage) of the noise filter 68 starts from the rising point of the output waveform of the noise filter 68 at the falling point of the output waveform of the waveform shaping circuit 70. This is delayed by a time until the time when the voltage becomes equal to or higher than the first threshold voltage Vtp, and this delay time Δt1 becomes a time constant error.

  The rise time of the output waveform of the waveform shaping circuit 70 is delayed by the time from the fall time of the output waveform of the noise filter 68 to the time when the output (output voltage) of the noise filter 68 becomes equal to or lower than the second threshold voltage Vtn. However, this delay time Δt2 is short enough to be ignored. Therefore, the output waveform of the waveform shaping circuit 70 can be treated as having no time constant error at the rise time.

  Accordingly, as shown in FIG. 10A, each falling edge of the three-phase rotor position detection pulse Sa is affected by a noise filter error.

  As described above, the detection magnet error includes an error in the magnetization range of the detection magnet 22 and an installation error, and therefore, the detection magnet error is affected by the detection magnet error when each magnetic sensor detects a change in the magnetic pole. That is, each falling edge and each rising edge of the three-phase rotor position detection pulse Sa are affected by the detection magnet error.

  Specifically, when the first magnetic sensor 34a is used as the reference position, for example, in the first-phase rotor position detection pulse Sa1, the first falling from the reference position is the position error of the first boundary 24a in the detection magnet 22. The next first rising edge is affected by the position error (second detecting magnet error) of the second boundary 24b in the detecting magnet 22, and the next second falling edge is influenced by the (first detecting magnet error). Due to the influence of the position error (third detection magnet error) of the third boundary 24 c in the detection magnet 22, the next second rise is the position error (fourth detection magnet error of the fourth boundary 24 d in the detection magnet 22). ), The next third fall is affected by the position error (fifth detection magnet error) of the fifth boundary 24e in the detection magnet 22 and the next third fall. The rise is affected by the position error (sixth detection magnet error) of the sixth boundary 24f in the detection magnet 22, and the next fourth fall is the position error (seventh detection of the seventh boundary 24g in the detection magnet). It is influenced by the magnet error. The same applies to the second-phase rotor position detection pulse Sa2 and the third-phase rotor position detection pulse Sa3.

  As described above, the magnetic sensor error includes the reading error of the first magnetic sensor 34a to the third magnetic sensor 34c and the mounting error with respect to the stator 14 when detecting the forward rotation speed of the rotor 12. When the sensor 34a is used as a reference, each rising edge and each falling edge of the second-phase rotor position detection pulse Sa2 corresponding to the second magnetic sensor 34b is a magnetic sensor error (second magnetic sensor error) caused by the second magnetic sensor 34b. The rise and fall of the third-phase rotor position detection pulse Sa3 corresponding to the third magnetic sensor 34c is affected by the third magnetic sensor 34c (the third magnetic sensor error). It is influenced by.

  Therefore, the rotor speed detection pulse Sb output from the pulse generation circuit 56 is affected by the various error components described above.

  For example, as shown in FIG. 10B, the time t1 is affected by the noise filter error, the third magnetic sensor error, and the seventh detection magnet error, the time t2 is affected by the second magnetic sensor error, and the time t3 is the noise filter error. The same applies to the influence of the first detection magnet error.

  Therefore, when the speed of the rotor 12 is detected using the first method described above, that is, the period from the falling edge of the rotor speed detection pulse Sb to the next rising edge and the period from the rising edge to the next falling edge, respectively, as speed detection cycles, As shown in FIG. 10B, the three-phase rotor position detection pulse Sa included in the time point t1 to the time point t23 is affected by the error components.

  Therefore, as a second method, the speed of the rotor 12 is detected using the period from the falling edge of the rotor speed detection pulse Sb to the next arbitrary falling edge and the period from the rising edge to the next arbitrary falling edge as the speed detection period. It is preferable. In this case, in order to increase the detection accuracy, it is preferable to satisfy the speed detection period <the pulse period Ta of the rotor position detection pulse Sa.

  For example, when the speed of the rotor 12 is detected using the period from the fall of the rotor speed detection pulse Sb to the next fall (t0 → t2, t2 → t4, t4 → t6,...) As the speed detection cycle, FIG. As shown, the second magnetic sensor error at time t2, the third magnetic sensor error at time t4, the second detection magnet error at time t6, the second detection magnet error and the second magnetic sensor error at time t8, Second detection magnet error and third magnetic sensor error at time t10, fourth detection magnet error at time t12, fourth detection magnet error and second magnetic sensor error at time t14, fourth detection magnet at time t16 Error and third magnetic sensor error, sixth detection magnet error at time t18, sixth detection magnet error and second magnetic sensor error at time t20, sixth detection magnet error and third magnetic sensor error at time t22 Affected Is only, it is possible to minimize the impact of the error component. This leads to further improvement in the detection accuracy of the speed of the rotor 12.

  The period from the fall of the rotor speed detection pulse Sb used as the speed detection period to the next arbitrary fall is one period from the fall in addition to the period from the fall to the next fall described above. It is also possible to adopt a period (t0 → t4, t4 → t8, t8 → t12,...) Until the trailing edge.

  Further, as a period from the rise of the rotor speed detection pulse Sb used as the speed detection period to the next arbitrary rise, periods from the rise to the next rise (t1 → t3, t3 → t5, t5 → t7,... Or a period from a rising edge to every other rising edge (t1 → t5, t5 → t9, t9 → t13,...) May be adopted.

  In any case, it is preferable to adopt a period in which the influence of the error component is minimized as the speed detection period.

  As described above, the speed detection circuit 50 according to the present embodiment can minimize the influence of the error component, and can detect the speed of the rotor 12 with high accuracy.

  In a motor system that performs speed control, the detection accuracy of the rotational speed of the motor 10 (rotor 12) is extremely important. Therefore, it is conceivable to use an expensive encoder or resolver for detecting the number of rotations of the motor 10 in a motor system that performs speed control, although it is highly accurate. On the other hand, the Hall IC used in the present embodiment is inexpensive, but has a problem that the resolution is low and generally the detection error of the rotational speed of the motor 10 is large.

  However, the speed of the rotor 12 can be detected with high accuracy by providing the pulse generation circuit 56 that generates the rotor speed detection pulse Sb based on the three-phase rotor position detection pulse Sa as in the present embodiment. Furthermore, the detection accuracy can be further improved by selecting a period from the falling edge of the rotor speed detection pulse Sb to the next arbitrary falling edge or a period from the rising edge to the next arbitrary rising edge as the speed detection period. . In particular, by selecting the period from the fall of the rotor speed detection pulse Sb to the next fall as the speed detection period, the influence of the error component can be minimized, and as a result, the speed detection accuracy of the rotor 12 can be improved. The rotor position detection pulse Sa can be improved three times as long as the pulse detection period Ta is the speed detection period, and the error component can be reduced to about 1/10.

  As a result, even if a Hall IC is used as the magnetic sensor, the speed control of the motor 10 can be performed with high accuracy, and the speed command value from the CPU 58 can be followed with high accuracy with almost no error.

  And the stop control method of the electric vehicle 100 which concerns on this Embodiment has two control forms (a 1st control form and a 2nd control form) as shown below.

  First, the first control mode will be described with reference to FIGS. This first control mode is an example in which the speed detection circuit 50 is used to drive the electromagnetic brake 108 of the electric vehicle 100. FIG. 11 mainly shows the operation lever 82, the accelerator detection circuit, the CPU 58, the speed detection circuit 50, the electromagnetic brake 108, the brake drive circuit 110, and the timer 86 in order to explain the first control mode.

  In the CPU 58, an internal signal generation means 88 as software and a brake instruction means 90 operate.

  An operation signal Sd from the accelerator detection circuit 114 based on an operation instruction of the operation lever 82 is input to the CPU 58. The internal signal generator 88 generates an internal signal Se indicating, for example, a stop state (OFF) and a running state (ON) based on the input operation signal Sd.

  For example, when the ratio of the user's steering angle θa to the maximum steering angle θm of the operation lever 82 is the accelerator ratio, the internal signal generating means 88 has an accelerator ratio of 0% to 4%, for example, as shown in FIG. At the time of change, the internal signal Se is turned ON (running state). Thereafter, when the accelerator ratio is 4% or more, the internal signal Se is maintained in an ON state. In this running state, the rotation of the rotor 12 (motor 10) is controlled with high precision by the CPU 58 based on the rotational speed and accelerator ratio of the rotor 12 detected with high precision by the speed detection circuit 50. Thereafter, when the accelerator ratio is lowered by the operation of the operation lever 82 by the user, the internal signal Se is in the ON state, and the accelerator ratio becomes, for example, 3%, the internal signal generation means 88 performs the internal signal Se. Is turned off (stopped).

  In the stop state, since the speed of the electric vehicle 100 becomes close to zero, the rotational speed of the rotor 12 (motor 10) also becomes slow, and the pulse width of the rotor speed detection pulse Sb becomes long as shown in FIG. In this case, it becomes impossible to accurately detect whether the speed of the electric vehicle 100 is zero or whether the electric vehicle 100 is moving forward or backward. Therefore, it is necessary to completely stop the rotation of the rotor 12 (motor 10) when a certain amount of time has passed.

  The brake drive circuit 110 turns on the electromagnetic brake 108 for the first time when the brake instruction means 90 turns on the stop flag 92 to completely stop the rotation of the rotor 12 (motor 10).

  Therefore, in the first control mode, when the internal signal Se is turned off (stopped), the time point t30 when the two trailing edges of the rotor speed detection pulse Sb have elapsed is the trigger for driving the electromagnetic brake 108 ( Timing) is the reference time point.

  That is, the brake instructing unit 90 operated by the CPU 58 counts the clock from the timer 86 from the time t30 when the two trailing edges of the rotor speed detection pulse Sb have elapsed, and counts a predetermined number of times t31 (the predetermined period Tb is When the time has elapsed), the stop flag 92 is turned ON. The brake drive circuit 110 turns on the electromagnetic brake 108 when the brake instruction means 90 turns on the stop flag 92 to completely stop the rotation of the rotor 12.

  Next, the second control mode will be described with reference to FIGS. In the second control mode, as shown in FIG. 14, a counter 94 that counts the clock from the timer 86 is newly provided and used for stop control of the electric vehicle 100.

  As shown in FIG. 15, the counter 94 resets the count value based on the falling edge of the rotor speed detection pulse Sb output from the pulse generation circuit 56 of the speed detection circuit 50 and counts the clock from the timer 86. To do. The counter 94 outputs an overflow signal Sf when the count value reaches a predetermined value, resets the count value, and restarts counting of the clock from the timer 86.

  The brake instructing means 90 operated by the CPU 58 starts the overflow signal Sf from the counter 94 from the time t30 when two falling edges of the rotor speed detection pulse Sb have elapsed from the time when the internal signal Se is turned off (stopped). The number of outputs (the number of overflows) is counted, and the rotational speed of the motor 10 (rotor 12) is controlled so that the speed command value corresponds to the number of overflows.

The speed command value corresponding to the overflow count is, for example, speed command value (rpm) = 40000000 / (overflow count × 2 ¹⁶ )
Can be obtained. Of course, other relational expressions and information tables may be used.

  Then, the brake instruction unit 90 turns on the stop flag 92 when a predetermined number, for example, 7 is counted as the overflow count. The brake drive circuit 110 turns on the electromagnetic brake 108 when the brake instruction means 90 turns on the stop flag 92 to completely stop the rotation of the motor 10 (rotor 12).

  In the first control mode and the second control mode described above, electromagnetic waves are detected based on the falling edge in which the error component is minimized among the rotor speed detection pulses Sb output from the pulse generation circuit 56 of the speed detection circuit 50. Since the brake 108 is driven, the stopping accuracy of the motor 10 (rotor 12) can be improved.

  Of course, the speed detection circuit according to the present invention is not limited to the above-described embodiments, and various configurations can be adopted without departing from the gist of the present invention.

It is a block diagram which shows the electric vehicle which concerns on this Embodiment. It is a block diagram which shows the motor applied to the electric vehicle which concerns on this Embodiment. It is the arrow line view seen from the III-III line in FIG. It is a top view which shows the structure of a stator. It is a circuit diagram which shows an example of a speed detection circuit. It is a circuit diagram which shows the other example of a speed detection circuit. 7A is a diagram illustrating an output waveform of the first magnetic sensor, FIG. 7B is a diagram illustrating an output waveform of the noise filter, and FIG. 7C is a diagram illustrating an output waveform of the waveform shaping circuit. FIG. 8A is a waveform diagram showing three-phase rotor position detection pulses, and FIG. 8B is a waveform diagram showing rotor speed detection pulses. It is a table | surface figure which shows the truth table of a pulse generation circuit. FIG. 10A is an explanatory diagram showing a three-phase rotor position detection pulse together with an error component, and FIG. 10B is an explanatory diagram showing an influence of the error component when the speed is detected by the first method based on the rotor speed detection pulse. FIG. 10C is an explanatory diagram showing the influence of the error component when the speed is detected by the first method. It is a block diagram which shows the 1st control form of the stop control method of the electric vehicle which concerns on this Embodiment. In a 1st control form, it is a wave form diagram which shows the waveform change of the internal signal with respect to an accelerator ratio. 6 is a timing chart showing a waveform of a rotor speed detection pulse at a stage when an internal signal is turned off, a stop flag ON timing, and an electromagnetic brake start timing. It is a block diagram which shows the 2nd control form of the stop control method of the electric vehicle which concerns on this Embodiment. It is a timing chart which shows the waveform of the rotor speed detection pulse in the stage where the internal signal became OFF, the change of the count value by the counter, the change of the speed command value, the timing of turning on the stop flag, and the start timing of the electromagnetic brake.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Motor 12 ... Rotor 50, 50a ... Speed detection circuit 52 ... Magnetic detection circuit 54 ... Rotor position detection circuit 56 ... Pulse generation circuit 58 ... CPU 60 ... Rotor position detection means 62 ... Rotor speed detection means 64a ... 1st magnetic sensor Part 64b ... Second magnetic sensor part 74 ... First logic circuit 76 ... Second logic circuit 82 ... Operation lever 100 ... Electric vehicle 102 ... Axle 104 ... Electronic control unit 106 ... Transmission mechanism 108 ... Electromagnetic brake 110 ... Brake drive circuit 112 ... Motor drive circuit 114 ... Accelerator detection circuit

Claims (5)

An operation lever, an axle, a motor whose rotation is controlled by drive control means based on a steering angle of the operation lever , a transmission mechanism for transmitting the rotational force of the motor to the axle, and a brake for rotating the motor In a stop control method for an electric vehicle having a brake,
The electric vehicle has a speed detection circuit that detects a rotation speed of the motor based on a series of pulse signals generated as the motor rotates, and a timer that outputs a clock.
Based on the steering angle of the operation lever, the drive control means controls the motor to decelerate toward the stop of rotation, and then the generation of an internal signal indicating a stop state based on the steering angle of the operation lever is detected. from time points, at the time of the lapse of twice the fall of the pulse signal from the speed detecting circuit, and starts counting the clock from the timer, the rotation of the motor at the time of counting the clock by a predetermined number The vehicle is stopped by a brake. An operation lever, an axle, a motor whose rotation is controlled by drive control means based on a steering angle of the operation lever , a transmission mechanism for transmitting the rotational force of the motor to the axle, and a brake for rotating the motor In a stop control method for an electric vehicle having a brake,
The electric vehicle includes a speed detection circuit that detects a rotation speed of the motor based on a series of pulse signals generated as the motor rotates, a timer that outputs a clock, and a predetermined number of clocks from the timer. A counter that outputs an overflow signal each time counting is performed,
Based on the steering angle of the operation lever, the drive control means controls the motor to decelerate toward the stop of rotation, and then the generation of an internal signal indicating a stop state based on the steering angle of the operation lever is detected. from time points, the upon expiration of the two falling of the pulse signal from the speed detection circuit, the starts counting of the clock at the counter, two or more outputs of the overflow signal from the counter A stop control method for an electric vehicle, wherein the motor is controlled according to a speed command value that decreases stepwise according to the number of times. In the stop control method of the electric vehicle according to claim 1 or 2,
The speed detection circuit includes:
A magnetic detection circuit having at least three magnetic sensors arranged to face the rotor of the motor, and outputting changes in a plurality of magnetic poles accompanying rotation of the rotor as a three-phase digital waveform;
A pulse generation circuit that generates the series of pulse signals in which each rising edge and each falling edge of the three-phase digital waveform is reflected;
An electric vehicle stop control method, comprising: detecting a rotation speed of the rotor based on an output from the pulse generation circuit. In the stop control method of the electric vehicle according to claim 3,
The pulse generation circuit includes:
A first logic circuit that outputs an exclusive OR of a first-phase digital waveform and a second-phase digital waveform among the three-phase digital waveforms;
A second logic circuit that outputs an exclusive OR of a third-phase digital waveform of the three-phase digital waveform and an output of the first logic circuit;
A stop control method for an electric vehicle, wherein the counting of the clock is started when two falling edges of the output of the second logic circuit have elapsed. In the stop control method of the electric vehicle according to claim 4,
A stop control method for an electric vehicle, characterized in that a speed detection period is a period from the rising edge of the output of the second logic circuit to the next arbitrary rising edge or a period from the falling edge to the next arbitrary falling edge.

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