JP2007236161A - Switched reluctance motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve high motor output characteristics over the whole rotational speed ranging, from low rotational speed to high rotational speed. <P>SOLUTION: In a control unit 1 for performing PWM control on a switched reluctance motor 2, maps 11, 12, 13 for obtaining duty, a switch-on angle and an angle of lead of switch-on angle of PWM control according to the operation amount of accelerator and rotational speed are provided. According to the input operation amount of accelerator and the detected rotational speed, each value is set by CPU 3, and a motor 2 is drive controlled based on the set value. Since control is not performed only by rotational speed; as an example, if it is applied to an electric cart, the target output can be matched with the pedaling amount (operational amount) in accelerator pedal; and thereby the motor output can be changed according the pedaling amount of the accelerator. In this case, the accelerator can be operated with the same feeling as of a cart having an internal combustion engine. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a control device for a switched reluctance motor.

  Conventionally, a salient pole portion made of a plurality of magnetic bodies is provided on a rotor, a plurality of inward salient pole portions are provided on a stator that is coaxially arranged so as to surround the rotor, and windings are provided on each inward salient pole portion. In this way, a switched reluctance is formed by forming a magnetizing coil and selectively energizing each magnetizing coil to magnetically attract the salient pole part of the rotor to the inward salient pole part of the stator to generate rotational torque in the rotor. A motor is known. Since this SR motor does not require a magnet and has a simple structure, it has advantages such as being easy to cope with a bad environment and being able to reduce the size and increase the output at a low cost. For example, it may be used for a drive motor as an electric vehicle such as an electric cart.

As a control of the switched reluctance motor, a countermeasure at high rotational speed is considered. For example, the rotational state of the rotor is determined based on at least one of the actual rotational speed of the rotor (rotor) and the set target rotational speed. In some cases, PWM control is performed in the low rotation speed region of the rotor and advance angle control is performed in the high rotation speed region according to the determination result (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 3-143285

  However, in the low rotation speed region, the winding current can flow sufficiently even if the lead angle control is not performed. However, in the control of the above patent document, the current feedback is performed due to the limitation of the capacity of the power element to be used. Control is going on. For this reason, since the current detector is provided, there is a problem that the number of parts increases and the apparatus becomes so expensive.

  Further, in the above-mentioned patent document, since the decrease period and the increase period are continuously described with respect to the change of the inductance, the increase / decrease of the inductance continuously changes. There is a problem that the angle control causes a brake generation by regenerative braking.

  Generally, efficiency and motor output can be improved by performing advance angle control on the high rotation speed side. However, as the rotational speed becomes higher, the commutation interval becomes shorter, the energization time of each phase decreases, the effect of the rise time of the winding current becomes relatively large, and sufficient winding current cannot be secured. . Therefore, there is a problem that the motor output drops on the high rotation speed side, and the maximum speed is suppressed in an electric cart or the like.

  In order to solve such problems and realize high motor characteristics in the entire rotational speed region from the low rotational speed region to the high rotational speed region, in the present invention, the target output of the switched reluctance motor is set. Corresponding to the target output setting means, the rotational speed detection means for detecting the rotational speed of the switched reluctance motor, the drive control means for PWM controlling the switched reluctance motor, the target output and the rotational speed An energization form setting means for setting an energization form of the switched reluctance motor, and the drive control means is set by the energization form setting means according to the set target output and the detected rotational speed. Further, the driving of the switched reluctance motor is controlled based on the energization mode.

  In particular, the energization mode of the switched reluctance motor set according to the duty of the PWM control set corresponding to the target output and the rotational speed, and the target output and the rotational speed. It may be set by an energization angle and an advance angle of the energization angle set corresponding to the target output and the rotation speed. Further, the duty, the energization angle, and the advance angle may be set by each map created corresponding to the target output and the rotation speed.

  Thus, according to the present invention, the switch reluctance motor is PWM-controlled, and the energization mode setting means that sets the energization mode corresponding to the target output and rotation speed of the switched reluctance motor is used. Since the energization mode is set according to the speed, it is not controlled only by the rotation speed, so for example, by applying the target output to the accelerator pedal depression amount (operation amount) when applied to an electric cart, The accelerator operation can be performed with a feeling similar to that of the cart equipped with the internal combustion engine, such that the duty can be changed in accordance with the accelerator depression amount.

  In particular, the energization mode targets the duty of PWM control, the energization angle and its advance angle, and sets them according to the rotation speed and the target output, so that PWM control with a duty of 100% or less on the low rotation speed side Efficient control based on the advance angle is performed, and on the high rotation speed side, the energization angle is further increased and the advance angle is increased at a duty of 100%, so that control with a large dynamic range can be easily performed. Moreover, it can set easily by using those maps which obtain | require those settings corresponding to a target output and a rotational speed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic block diagram of a drive motor control device mounted on an electric cart to which the present invention is applied. An accelerator operation signal, which may be a depression amount of an accelerator pedal (not shown) as a target set value, is input to the control unit 1 as drive control means, and according to the drive control signal output from the control unit 1 according to the accelerator operation signal. A target switched reluctance motor (hereinafter referred to as “SR motor”) 2 is driven and controlled.

  The control unit 1 is provided with an accelerator operation signal as a target output, and a CPU 3 as target output setting means for setting the target output in response thereto, and a driver circuit 4 for energizing the SR motor 2. Yes. The SR motor 2 is provided with a rotation sensor 6 as a rotation speed detecting means for detecting the rotation speed of the rotor, and a rotation detection signal detected by the rotation sensor 6 is input to the CPU 3. The rotation sensor 6 may be one that detects the rotor position or rotation angle (angle sensor). In this case, the CPU 3 converts the rotation speed into a rotation speed.

  The SR motor 2 according to the present invention may have a three-phase structure shown in FIG. For example, the rotor 7 is provided with four radially outward salient pole portions, the annular stator 8 coaxially surrounding the rotor 7 is provided with six radially inward salient pole portions, U-phase, V-phase, and W-phase exciting coils Lu, Lv, and Lw are wound around the salient pole portions of the stator 8 and connected to each other at opposing positions. In the illustrated example, the winding is performed such that one of a pair of opposed salient pole portions of the stator 8 is an N pole and the other is an S pole.

  FIG. 2 shows an example of the driver circuit 4. In FIG. 2, one excitation coil Lu, Lv, and Lw of each phase is connected through each transistor Q1, Q2, and Q3 connected in parallel to a power supply line (voltage Vb) from a battery (not shown) as a power source. The other exciting coils Lu, Lv, and Lw of each phase are grounded through the transistors Q4, Q5, and Q6. The diodes D1, D2, D3, D4, D5, and D6 are for reflux.

  The transistors Q1 to Q6 are controlled by the CPU 3 so that, for example, the U-phase exciting coil Lu, the V-phase exciting coil Lv, and the W-phase exciting coil Lw are switched in order of the coil through which the winding current flows in accordance with the rotation of the rotor 7. Turns on / off according to the signal. In the energization control, PWM control is performed, and a drive control signal including a PWM control signal is output from the CPU 3 to each of the transistors Q1 to Q6, so that the SR motor 2 can be duty controlled. Yes.

  FIG. 3 shows the U-phase excitation coil Lu as a representative of the energization control on the low rotation speed side and the high rotation speed side. In the uppermost part of the figure, the change in inductance is shown, and the corresponding on / off procedure of the transistors Q1 and Q4 is shown on the upper side with a low rotational speed, and on the lower stage with a high rotational speed. Regarding the change in inductance, in addition to the U-phase excitation coil Lu indicated by a solid line, for reference, the V-phase excitation coil Lv is indicated by a broken line and the W-phase excitation coil Lw is indicated by a one-dot chain line.

  In the SR motor 2 of the illustrated example, as shown in FIG. 4, the rotation direction width θpr of the salient pole portion 7 a of the rotor 7 and the rotation direction width θps of the inward salient pole portion 8 a of the stator 8 are adjacent to each other. The rotation direction width θs between the matching inward salient pole portions 8a are the same width (angle), and as shown in FIG. 3, there is a section Jmin in which the minimum value continues for a predetermined section in the change in inductance. When the overlapping portion between the salient pole portion 7a and the inward salient pole portion 8a is increased by the rotation, the inductance is increased (section Jinc in FIG. 3), and the inductance is decreased when the overlapping portion is reduced. In the illustrated example, θpr = θps = θt is set as described above. In this case, θpr = θps = θt = 30 degrees (mechanical angle). However, the widths are not limited to the same width. Absent. These values may be increased (θt is decreased) while maintaining the relationship of θpr = θps. In that case, the inductance changes as shown by a two-dot chain line in FIG. Can be made larger, and the output can be increased by increasing the energization angle.

  On the low rotation speed side, energization control is performed by a so-called 120 degree (electrical angle) energization method in the case of three-phase driving. The conduction angle of 120 degrees is in a range indicated by AL in the figure. As shown in the figure, the energization control at the energization angle AL is performed by PWM control. In this case, the ground side transistor Q4 is turned on during the energization angle AL, and the power supply side transistor Q1 is turned on according to the duty.・ Turn it off.

  Further, the energization is started not from the start of the inductance increasing section Jinc but from the section Jmin where the minimum value is continuous. The advance angle from the start of the section Jinc to the energization start point to the section Jmin side is defined as the ON advance angle BL. Further, the advance angle before the end point of the section Jinc with respect to the end point of the energization angle AL is defined as the OFF advance angle CL. Note that the ON delay DL is set from the start of the section Jmin to the start of the energization section AL, and the OFF delay EL is set from the start of the section Jinc to the end point of the energization section AL. good.

  At the time of high output on the high rotation speed side, as shown in the lower side of FIG. 3, the duty is set to 100%, the energization angle AH is increased more than 120 degrees, and the OFF advance angle EH is advanced to advance the end position. Is progressing. As a result, as shown in the figure, the other ON advance angle BH, ON delay angle DH, and OFF advance angle CH change.

  Examples mapped as energization mode setting means for obtaining the PWM duty, energization angle, and OFF advance angle as the set values used for the control are shown in FIGS. 5, 6, and 7, respectively. In each map, each set value is obtained according to the accelerator operation amount and the rotation speed. The duty map 11, the energization angle map 12, and the OFF advance map 13 may be connected to the CPU 3 as shown in FIG. Note that the energization mode setting means is not limited to a map, and for example, each set value at some reference points may be set, and an interval between them may be obtained by interpolation calculation. good. FIG. 5 shows an example of the case of the interpolation calculation. As shown in the figure, the reference points P0 to P5 are set, and each point is interpolated with an equation that becomes a straight line or a curve.

  Next, each map is shown. In the map of FIG. 5, the duty increases in proportion to the accelerator operation amount from the low rotation speed side to the predetermined rotation speed Nd, and when the accelerator operation amount is maximum (100%), the high rotation speed is equal to or higher than the predetermined rotation speed Nd. On the side, the duty is set to 100%. As shown in the figure, the point at which the duty reaches 100% is continuously shifted to the minimum side of the accelerator operation amount as the rotational speed increases.

  In the map of FIG. 6, the energization angle AL is set constant (120 degrees) regardless of the amount of accelerator operation from the low rotational speed side to the predetermined rotational speed Nd, and the rotational speed increases above the predetermined rotational speed Nd. The energization angle AH is increased to 120 degrees or more from a smaller accelerator operation amount. It is increased so as to reach a predetermined maximum energization angle Amax at the maximum rotation speed and the maximum accelerator operation amount. In the example of FIG. 6, the increase method is proportional (linear) and the map is configured by two planes. However, in order to achieve smoother control, the map may be made non-linear and configured by curved surfaces. .

  In the map of FIG. 7, on the low rotational speed side, the OFF advance angle increases (advances) as the rotational speed increases regardless of the accelerator operation amount. In this map, when the rotational speed Nd2 is higher than the predetermined rotational speed Nd in each map and the accelerator operation amount is large, the OFF advance angle decreases as the rotational speed increases. The decrease starts from the side where the accelerator operation amount is small as the rotational speed increases. This is an example in which the OFF advance angle is limited to prevent the ON advance angle from increasing as the energization angle and the OFF advance angle increase, and the braking torque is generated when it reaches the reduced inductance portion. In addition, since the OFF advance angle becomes small and enters the reduced portion of the inductance in the middle of the decrease of the winding current after the drive is turned off, the braking state is also entered. Therefore, an appropriate ON advance angle, so as to obtain a desired output and efficiency, It is desirable to use an OFF advance angle and a conduction angle.

  From these maps, the PWM duty, energization angle, and OFF advance angle are obtained according to the accelerator operation amount and the rotation speed, and energization control is performed based on the set values as shown in FIG. When the 120 ° conduction angle is constant at a low rotation speed, when the OFF advance CL is changed according to the map of FIG. 7, the ON advance BL is set at the same advance as the advance, and the winding current Is controlled by the duty.

  In addition, each map of the example of illustration is an example, and can change and use each map shape suitably according to use environment. For example, a linearly changing portion in the illustrated example may be a map shape that changes with a curve. It is possible to freely change the design of the map shape, and thus it is possible to easily perform appropriate control in accordance with the use conditions of the apparatus using the SR motor 2.

  According to the present invention, motor output characteristics as shown in FIG. 8A can be obtained. In the case of the conventional 120-degree energization method, it is as shown in FIG. The efficiency and motor output are improved by performing the lead angle control on the high rotation speed side, but the drive time per phase decreases as the rotation speed increases, so the rise time of the winding current This is because a sufficient winding current cannot be secured due to the influence, and the motor output falls on the high rotation speed side as shown in FIG.

  On the other hand, this control device is used because the winding current becomes too large when energization with a high PWM duty is performed at a 120-degree conduction angle AL on the low rotation speed side (rotation speed Nd or less in the illustrated example). By setting the maximum PWM duty that can secure the necessary current within the current value allowed by the power element corresponding to the rotation speed, the winding current can be suppressed without using the current detection means. . Furthermore, as shown in the example, by associating the maximum duty with the maximum value of the accelerator operation amount, an equivalent dynamic range that is the same output control as the current feedback control can be secured, and the conventional current feedback control and It is possible to perform control that gives the same feeling.

  On the high rotation speed side (in the illustrated example, the rotation speed Nd or higher), the conduction angle AH is also increased from 120 degrees. The maximum energization angle Amax and the maximum accelerator operation amount (100%) are associated with each other, so that the dynamic range of the output (accelerator) control on the high rotational speed side can be made larger than that of the 120 ° energization angle control. it can. As for the OFF advance angle, an appropriate advance amount may be set in consideration of the relationship between efficiency and output. In the illustrated example, as shown in the map of FIG. 7, the OFF advance angle is increased until it reaches the maximum value of the rotation speed and the accelerator operation amount, and after reaching the maximum advance angle, the maximum of the rotation speed and the accelerator operation amount is reached. It has been reduced to the value. This is a case where the ON advance angle becomes large and the start of the energization angle does not enter the region where the braking torque is generated, and the energization angle is given priority in order to obtain a desired output. It may be set arbitrarily according to the operating conditions, the characteristics of the SR motor 2, and the like. Thereby, as shown to Fig.8 (a), the fall of the motor output in the high rotational speed side can be prevented, and the maximum speed can be raised further.

  According to the present invention, the setting values (duty, energization angle, OFF advance angle in the illustrated example) used for energization control are obtained from the map using the rotation speed and the accelerator operation amount as parameters, and this makes it possible to easily perform necessary control. A value can be set, and output control can be actively performed from the accelerator operation amount. As a result, when applied to an electric vehicle such as an electric cart, the driving feeling is the same as that of a vehicle equipped with an internal combustion engine, and a sense of incongruity does not occur even when changing.

  In addition, when the energization angle AL / AH is advanced and energization is started, in the SR motor in which the increase / decrease or increase / decrease / hold of the inductance is repeated, if the advance angle is large, the energized portion reduces the inductance. Although the brake is applied to the portion, as described above, the ON advance angle is kept within the section Jmin where the inductance is the minimum value, so that the brake does not occur and the efficiency decreases when the advance angle increases on the high rotational speed side. The effect is great.

It is a schematic block diagram of the drive motor control apparatus mounted in the electric cart to which this invention was applied. It is a circuit diagram which shows a driver circuit. It is a figure which shows the change of an inductance, and the energization point. It is principal part expansion explanatory drawing of a switched reluctance motor. It is a figure which shows the map for duty. It is a figure which shows the map for conduction angles. It is a figure which shows the map for OFF advance. (A) is a figure which shows the motor output characteristic by this invention, (b) is a figure corresponding to (a) which shows the motor output characteristic in the case of a 120 degree | times energization system.

Explanation of symbols

1 Control unit 2 Switched reluctance motor (SR motor)
3 CPU
4 Driver Circuit 6 Rotation Sensor 11 Duty Map 12 Energization Angle Map 13 OFF Advance Map

Claims (3)

Target output setting means for setting a target output of the switched reluctance motor, rotational speed detection means for detecting the rotational speed of the switched reluctance motor, drive control means for PWM controlling the switched reluctance motor, and the target output And an energization form setting means for setting an energization form of the switched reluctance motor corresponding to the rotational speed,
The drive control means controls the drive of the switched reluctance motor based on the energization form set by the energization form setting means according to the set target output and the detected rotational speed. A control device for a switched reluctance motor.   The duty of the PWM control that is set corresponding to the target output and the rotation speed, and the conduction angle of the switched reluctance motor set corresponding to the target output and the rotation speed. 2. The switched reluctance motor control device according to claim 1, wherein the control unit is set according to the target output and the advance angle of the energization angle set in correspondence with the rotation speed.   3. The switch according to claim 1, wherein the duty, the energization angle, and the advance angle are set by each map created in correspondence with the target output and the rotation speed. 4. Control device for trilactance motor.

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