JP3942550B2 - Stepping motor drive device - Google Patents

Description

ただし、Ｔは軸トルク、Ｔｍはモータ最大トルク、δは偏差である。
また、振動抑制部２０を図２のように構成したときの振動抑制部出力λは数式２となる。
【数２】

ここで、ｋは係数器２１の設定値、θ＊は端子１０に加えられる位置指令、θｆは位置検出器９２の出力であるロータ磁極位置である。
振動抑制部２０の出力λは電流指令の角度となるから、ロータ磁極位置θｆとλの位相差が偏差δと考えることができ、数式３が成り立つ。
【数３】

数式３を数式１に代入して数式４を得る。
【数４】

数式４の関係を図３に示す。図３において（ａ）はｋ＝０の場合、（ｂ）はｋ＞０の場合（代表値としてｋ＝０．５）、（ｃ）はｋ＜０の場合（代表値としてｋ＝−０．５）を示している。また、ｋと最大トルク発生角度の関係を図４に示す。即ち、図４に示すとおり、係数器の設定値ｋの大きさを変えることで最大トルク発生の角度を制御することができることが分かる。また、図３に示すとおり安定点における位置偏差対発生トルクの割合（軸剛性と称する）も変化させることができる。
図３における（ａ）のｋ＝０という条件は通常のステッピングモータのオープン駆動に対応することは明らかであるから、ｋを正の値に取ることで軸剛性を小さくすることができる。この結果、振動を低減することができる。
また、ｋを負の値に取ることで軸剛性を大きくすることができるから、停止位置精度を向上することができる。
【０００９】
【実施例】
図１は本発明の第１の実施例である。
図１において、ステッピングモータ９１に対してＰＷＭインバータ７０でモータに所定の電圧を印加し、モータを回転させる。電流検出器８１、８２でモータ相電流ｉαｆ、ｉβｆを検出し、前記モータ相電流ｉαｆ、ｉβｆを第１の加算器３１及び第２の加算器３２の一方の入力とする。また、第１相の電流振幅指令入力端子６１と第２相の電流振幅指令入力端子にそれぞれｉα＊及びｉβ＊を印加する。
加算器３１、３２は電流指令と帰還電流の差分である電流誤差を演算するものであり、前記電流誤差を電流補償器４１、４２で増幅したのち、前記ＰＷＭインバータ７０の入力としている。
【００１０】
図２は前記調整部２０の詳細を示す図である。
角度演算器２１は加算器２２の出力である位置偏差εを係数倍（ｋ倍）し、加算器２３（異符号であるため減算となる）の一方の入力に接続する。加算器２３の他方の入力には位置指令θ＊を接続し、出力λを得ている。
【００１１】
係数ｋを０＜ｋ＜１に取ると、前記調整部２０の出力λは、ロータ磁極位置が指令に対して偏差を持つ場合、角度指令を直接励磁電流の角度指令に用いるよりも小さな指令変化を過渡的に与えることができるため、振動低減効果が得られる。
【００１２】
係数ｋをｋ＜０に取ると、前記調整部２０の出力λは、ロータ磁極位置が指令に対して偏差を持つ場合、角度指令を直接励磁電流の角度指令に用いるよりも大きな指令変化を過渡的に与えることができるため、モータの軸剛性を大きくできる。
【００１３】
図７は本発明の第２の実施例である。
図７と図１の共通部は同一番号を付しているが、図７では、対象モータが３相ステッピングモータになり、第１の座標変換器（３相−２相変換）６５、及び第２の座標変換器（２相−３相変換）６６、電流センサ８３が追加されている他は、同一の構成である。３相電流を検出する場合、対称性を利用して、２つの電流センサ検出出力で第３相電流を演算することで第３相目の電流センサを省略することも可能である。
尚、第１及び第２の実施例に示す機能は、構成部品を少なくするためにマイクロプロセッサを用いて実現することも可能である。
【００１４】
【発明の効果】
上記のごとく、本発明によるステッピングモータの駆動装置は、軸剛性を調節することができるから、低振動と高停止精度のモータ駆動を実現することができ、低振動、高精度の装置を構築可能である。
また、対象モータは異なる相数に対して柔軟に対応することができる。
【００１５】
【図面の簡単な説明】
【図１】本発明の第１の実施例である。
【図２】本発明の第１の実施例の部分説明図である。
【図３】本発明の原理説明のための角度対軸トルクの関係を示す説明図である。
【図４】本発明の係数器係数対最大トルク発生角度の関係を示す説明図である。
【図５】第１の従来例ブロック図である。
【図６】第２の従来例ブロック図である。
【図７】本発明の第２の実施例である。
【符号の説明】
１０ 位置指令入力端子
２０ 調整部
２１ 係数器
２２、２３ 加算器
３１、３２ 加算器
４１ 第１相電流制御器
４２ 第２相電流制御器
５１ 第１相基本電流指令発生器
５２ 第２相基本電流指令発生器
６１ 第１相電流振幅指令入力端子
６２ 第２相電流振幅指令入力端子
６３、６４ 乗算器
６５ 第１の座標変換器
６６ 第２の座標変換器
７０ ＰＷＭインバータ
８１、８２、８３ 電流検出器
９１ ステッピングモータ
９２ 位置検出器
１０１ 加算器
１０２ 加算器
１０３ 加算器
１０４ 加算器
１０５ 加算器
１１０ 位置制御器
１２０ 速度制御器
１３０ 第１の座標変換器
１４１ 第１の電流制御器
１４２ 第２の電流制御器
１５０ ＰＷＭインバータ
１５４ 第１の電流検出器
１５５ 第２の電流検出器
１６０ 第２の座標変換器
１７０ 三角関数発生器
１８０ ステッピングモータ
１９０ 位置検出器[0001]
[Industrial application fields]
The present invention relates to a stepping motor driving apparatus for controlling an angle and a speed.
[0002]
[Prior art]
As the functions of the equipment increase, the motor is required to rotate over a wide range with low vibration and low noise. However, the stepping motor advances by switching the energization state of each winding instantaneously every time an external command pulse is applied. Since it rotates, it is a problem to reduce vibration noise generated at the time of switching current and to prevent step-out.
In order to reduce vibration noise and prevent step-out, a microstep drive is generally used in which a winding current is smoothly changed using a pulse width modulation (hereinafter referred to as PWM) inverter. FIG. 5 is a block diagram of a microstep driving circuit according to the prior art.
[0003]
Microstep drive can be realized by energizing a motor winding with a sinusoidal staircase current with a phase difference corresponding to the number of motor phases. FIG. 5 shows an example of a two-phase stepping motor, but the output cos θ * of the first phase basic current command generator 51 corresponding to the position command θ * applied to the external input terminal 10 and the second phase basic current command. The output sin θ * of the generator 52 is generated, the output of the phase basic current command generators 51 and 52 is connected to one input terminal of the multipliers 63 and 64, and the current amplitude applied to the external input terminals 61 and 62 The command is connected to the other input terminals of the multipliers 63 and 64 to obtain the first phase current command Iα * cos θ * and the second phase current command Iβ * sin θ *. The adders 31 and 32, the current controllers 41 and 42, the inverter 70, and the current detectors 81 and 82 are a first phase current command Iα * cos θ * and a second phase current command Iβ * applied to the adders 31 and 32. A current control system using sin θ * as a current command is configured to achieve desired characteristics.
The micro-step driving method according to FIG. 5 is an effective technique for reducing transient vibrations because the step-like operation can be made minute and close to smooth rotation according to the resolution of the position command. .
However, in the microstep drive system, for example, the stop position error when stationary is dependent on the motor angle versus the generated torque characteristics, and therefore the stop position improvement effect cannot be expected. Similarly, the characteristic vibration of the stepping motor is shown with respect to the natural vibration of the motor.
[0004]
In order to realize a microstep function and vibration reduction, for example, as described in JP-A-6-225595, there is a control device that converts each phase current into a dq rotating coordinate system and handles control of the motor current in the rotating coordinate system.
In the system described in Japanese Patent Laid-Open No. 6-225595, an encoder is connected to the stepping motor on the assumption that the stepping motor is the same model as the permanent magnet type synchronous motor as shown in the configuration diagram of FIG. 6, and current control, speed control, and position control are performed. Are described, and a specific method for realizing position control by converting them into a dq rotating coordinate system is described. Further, for the purpose of simplifying the control configuration, it is specified that the non-interfering element of the dq axis component is omitted and that a current command is given directly on the dq axis.
[0005]
However, the stepping motor is characterized by a large number of magnetic poles and a higher current fundamental frequency than other control motors. For this reason, when the stepping motor is configured with a control circuit similar to a permanent magnet type synchronous motor having the same structure, the current controller gain decreases as the speed increases due to the limit of responsiveness of the current controller, and the motor current is controlled. There is a problem that the error increases. Further, since the motor generates the speed electromotive force Emf, a state occurs in which the Emem antagonizes the applied voltage due to the increase in the motor rotational speed or the motor current cannot be controlled at the rotational speed exceeding the applied voltage.
In other words, in an actual device having a limited applied voltage compared to the stepping motor control method according to the method described in JP-A-6-225595, it becomes difficult to control the current as the rotational speed increases, and the controllable range is limited. There was a problem.
Further, the stepping motor control device described in Japanese Patent Application Laid-Open No. 6-225595 has a magnetic flux direction component as a d-axis and a direction perpendicular to the d-axis as a q-axis. Since the current is controlled in accordance with the speed deviation, and it is necessary to provide a position controller and a speed controller in order to realize position control, the control apparatus is complicated and expensive.
[0006]
[Problems to be solved by the invention]
As described above, the conventional method subdivides the amount of change in position per step of the stepping motor for the purpose of suppressing vibration, but the characteristics with respect to vibration and stop accuracy with respect to load fluctuations are inherent characteristics of the stepping motor. It was. Further, the conventional system that positively improves the vibration characteristics has a complicated structure and an expensive control device.
An object of the present invention is to realize a stepping motor drive device that has a vibration suppressing effect and has a simple configuration and is inexpensive. Another object of the present invention is to realize a stepping motor driving device having an effect of improving the position accuracy at the time of stop (zero speed).
[0007]
[Means for solving problems]
In order to solve the above problems, in the present invention, in a multiphase stepping motor drive device that supplies a sinusoidal staircase current to a stepping motor, a position detector that detects a rotor magnetic pole position is provided, and a position given to a position command input terminal Using the command θ * and the rotor magnetic pole position θf detected by the position detector to calculate the position deviation ε, which is the difference between the position command θ * and the rotor magnetic pole position θf, and multiplying the position deviation ε by a coefficient, A value obtained by subtracting the coefficient output from the position command θ * is configured as an excitation angle command.
Further, the coefficient k of the coefficient unit is adjusted with 0 <k <1 for the purpose of vibration suppression, and the coefficient k is changed within the range of k <0 for the purpose of controlling the stop accuracy.
[0008]
[Action]
With the above configuration, a low-vibration and high-accuracy drive device that is a subject of the present invention can be realized at low cost. The rationale is described below.
If the shaft torque of the motor is a sine function of the deviation between the rotor magnetic pole position and the excitation position, the shaft torque can be expressed by Equation 1.
[Expression 1]

However, T is a shaft torque, Tm is a motor maximum torque, and δ is a deviation.
Further, the vibration suppression unit output λ when the vibration suppression unit 20 is configured as shown in FIG.
[Expression 2]

Here, k is a set value of the coefficient unit 21, θ * is a position command applied to the terminal 10, and θf is a rotor magnetic pole position that is an output of the position detector 92.
Since the output λ of the vibration suppressing unit 20 is the angle of the current command, the phase difference between the rotor magnetic pole positions θf and λ can be considered as the deviation δ, and Equation 3 is established.
[Equation 3]

Substituting Equation 3 into Equation 1 yields Equation 4.
[Expression 4]

The relationship of Formula 4 is shown in FIG. In FIG. 3, (a) is k = 0, (b) is k> 0 (typical value is k = 0.5), and (c) is k <0 (typical value is k = −0). .5). FIG. 4 shows the relationship between k and the maximum torque generation angle. That is, as shown in FIG. 4, it can be seen that the angle of maximum torque generation can be controlled by changing the magnitude of the setting value k of the coefficient unit. Further, as shown in FIG. 3, the ratio of the position deviation to the generated torque at the stable point (referred to as shaft rigidity) can also be changed.
Since it is clear that the condition of k = 0 in FIG. 3A corresponds to the open drive of a normal stepping motor, the shaft rigidity can be reduced by taking k as a positive value. As a result, vibration can be reduced.
Moreover, since the shaft rigidity can be increased by taking k as a negative value, the stop position accuracy can be improved.
[0009]
【Example】
FIG. 1 shows a first embodiment of the present invention.
In FIG. 1, a predetermined voltage is applied to the stepping motor 91 by a PWM inverter 70 to rotate the motor. The current detectors 81 and 82 detect motor phase currents iαf and iβf, and the motor phase currents iαf and iβf are input to one of the first adder 31 and the second adder 32. Further, iα * and iβ * are applied to the first-phase current amplitude command input terminal 61 and the second-phase current amplitude command input terminal, respectively.
The adders 31 and 32 calculate a current error which is a difference between the current command and the feedback current. The current error is amplified by the current compensators 41 and 42 and then used as the input of the PWM inverter 70.
[0010]
FIG. 2 is a diagram showing details of the adjusting unit 20.
The angle calculator 21 multiplies the position deviation ε, which is the output of the adder 22, by a factor (k times), and connects it to one input of the adder 23 (because of the different sign, it is subtracted). A position command θ * is connected to the other input of the adder 23 to obtain an output λ.
[0011]
When the coefficient k is set to 0 <k <1, the output λ of the adjusting unit 20 is smaller in command change than when the angle command is directly used for the excitation current angle command when the rotor magnetic pole position has a deviation from the command. Can be provided in a transitional manner, so that a vibration reduction effect can be obtained.
[0012]
When the coefficient k is set to k <0, the output λ of the adjusting unit 20 causes a larger command change than when the angle command is directly used as the angle command of the excitation current when the rotor magnetic pole position has a deviation from the command. Therefore, the shaft rigidity of the motor can be increased.
[0013]
FIG. 7 shows a second embodiment of the present invention.
7 and FIG. 1 have the same reference numerals, but in FIG. 7, the target motor is a three-phase stepping motor, and the first coordinate converter (three-phase to two-phase conversion) 65, and the first The configuration is the same except that two coordinate converters (two-phase to three-phase conversion) 66 and a current sensor 83 are added. In the case of detecting a three-phase current, it is possible to omit the third-phase current sensor by calculating the third-phase current using two current sensor detection outputs using symmetry.
The functions shown in the first and second embodiments can be realized by using a microprocessor in order to reduce the number of components.
[0014]
【The invention's effect】
As described above, the stepping motor drive device according to the present invention can adjust the shaft rigidity, so that it can realize low-vibration and high-stop accuracy motor drive, and can construct a low-vibration and high-precision device. It is.
In addition, the target motor can flexibly cope with different numbers of phases.
[0015]
[Brief description of the drawings]
FIG. 1 is a first embodiment of the present invention.
FIG. 2 is a partial explanatory view of a first embodiment of the present invention.
FIG. 3 is an explanatory diagram showing the relationship between angle and shaft torque for explaining the principle of the present invention.
FIG. 4 is an explanatory diagram showing a relationship between a coefficient coefficient and a maximum torque generation angle according to the present invention.
FIG. 5 is a block diagram of a first conventional example.
FIG. 6 is a block diagram of a second conventional example.
FIG. 7 is a second embodiment of the present invention.
[Explanation of symbols]
10 position command input terminal 20 adjustment unit 21 coefficient unit 22, 23 adder 31, 32 adder 41 first phase current controller 42 second phase current controller 51 first phase basic current command generator 52 second phase basic current Command generator 61 First phase current amplitude command input terminal 62 Second phase current amplitude command input terminals 63, 64 Multiplier 65 First coordinate converter 66 Second coordinate converter 70 PWM inverters 81, 82, 83 Current detection 91 Stepping motor 92 Position detector 101 Adder 102 Adder 103 Adder 103 Adder 104 Adder 105 Adder 110 Position controller 120 Speed controller 130 First coordinate converter 141 First current controller 142 Second current Controller 150 PWM inverter 154 First current detector 155 Second current detector 160 Second coordinate converter 170 Trigonometric function generator 180 Step Ping motor 190 Position detector

Claims (4)

A stepping motor driving apparatus for supplying a stepping motor with a sinusoidal staircase current is provided with a current control function for controlling a motor current in accordance with a current command and a position detector for detecting a command rotor magnetic pole position, which are given to a position command input terminal. Using the position command θ * and the rotor magnetic pole position θf detected by the position detector to calculate the position deviation ε, which is the difference between the position command θ * and the rotor magnetic pole position θf, and multiplying the position deviation ε by a coefficient A stepping motor driving apparatus configured to subtract the coefficient output from the position command θ * as an excitation angle command. 2. The stepping motor driving apparatus according to claim 1, wherein k is a coefficient of the coefficient unit and k is determined within a range of 0 ≦ k <1. 2. The stepping motor driving apparatus according to claim 1, wherein the coefficient k of the coefficient unit is determined in a range of k ≦ 0. 2. The stepping motor drive device according to claim 1, wherein the coefficient k of the coefficient unit is determined in a range of 0 ≦ k <1 when the motor is rotated and k ≦ 0 when the motor is stopped.

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