JP5535285B2 - AC motor winding switching device and inverter device - Google Patents

Description

  The present invention relates to a winding switching device that expands a speed control range by switching an armature winding (hereinafter simply referred to as “winding”) of an AC motor, and an inverter device having a winding switching function. It is applied in a wide range of industrial technical fields, such as vehicle drive, machine spindle drive, traversing and traveling of cranes, and winders.

As a means for obtaining a sufficiently large torque in a low speed region and enabling high-efficiency operation in a high speed region in a spindle of a machine tool or a vehicle drive device driven by an inverter device, there is a winding switching method. It has been adopted.
The star / delta winding switching method shown in FIG. 11 is an example of a method widely used for driving a spindle of a machine tool. In FIG. 11, 622 is an AC power source, 616 to 621 are diodes constituting a three-phase full-wave rectifier circuit, 615 is a smoothing capacitor, and 614 is a converter unit that converts the AC power source 622 into a DC power source. Terminals TP and TN are DC output terminals of the converter unit 614 and are input to the inverter unit 601. 602 is an AC motor, T1 to T6 are terminals used for winding switching, and 603 and 604 are switches such as electromagnetic contactors.

  When the switch 604 is opened and the switch 603 is closed, a star (Y) connection is obtained. When the switch 604 is closed and the switch 603 is opened, a delta (Δ) connection is obtained. By selecting a star (Y) connection in the low speed region and applying a sufficiently high voltage, a large torque can be obtained for the same current. Since the impedance of the electric motor increases in proportion to the frequency and current does not flow easily in the high speed region, it is possible to facilitate current flow by selecting a delta (Δ) connection with low impedance. In addition, in a synchronous motor, the voltage is saturated at high speed due to the counter electromotive voltage, so weak magnetic flux control is performed to generate torque. By reducing itself, high-efficiency operation can be performed even at high speed.

In addition to the winding switching method, there is a method of switching two sets of star windings in series-parallel (for example, see Patent Document 1). However, these methods are all premised on switching by a switch having a mechanical contact, and the current from the inverter device is forced to be interrupted at the time of switching, so there is a problem that the torque is interrupted and a shock is generated. .
On the other hand, a method of shortening the cutoff time by a method using a semiconductor switch has been proposed (for example, see Patent Document 2).
Further, in order to reduce the shock due to winding switching, a method is proposed in which, in an electric vehicle, winding switching is not performed during acceleration / deceleration and winding switching is performed only when acceleration / deceleration is not performed (for example, (See Patent Document 3).
In addition, a method has been proposed in which two motor systems that perform winding switching are connected in parallel, and the variation in the total torque of the two motors is suppressed by shifting the winding switching timing between the two (for example, see Patent Document 4). .
Thus, the conventional winding switching device performs switching operation after cutting off the current from the inverter device or switching the current to near zero when switching the winding.
Japanese Patent No. 3037471 Japanese Patent No. 3948209 (page 3-6, FIG. 1) Japanese Patent Laid-Open No. 06-225588 (FIG. 1) Japanese Patent Laid-Open No. 06-217596 (FIG. 1)

Since the conventional winding switching device for a three-phase AC motor uses mechanical contacts, it takes time for the mechanism operation to turn the contacts on and off, and after interrupting the current once considering the life So-called no-current switching is performed, and when these times are combined, a dead time that cannot be ignored (usually several tens of milliseconds) is generated. This dead time affects the quality of the final product in, for example, a machine tool spindle drive device, and affects the ride quality in a vehicle drive device. Furthermore, since the contact life is finite, maintenance work is required.
On the other hand, the method using an electric switch is effective in reducing this dead time, but it is necessary to cut off or set the current to zero when switching the winding.
In addition, although the method of prohibiting switching during acceleration / deceleration in an automobile eliminates shock, there is a problem that, for example, when accelerating continuously to a high speed, efficiency is low and torque is not generated.
In the method of shifting the winding switching time by paralleling two systems, there is a problem that the system becomes large and costs increase.
The present invention has been made in view of such problems, and there is provided a winding switching device for a three-phase AC motor that can be realized with a simple configuration without shock at the time of winding switching even under conditions such as acceleration and deceleration. The purpose is to provide.

In order to solve the above-described problem, according to one aspect of the present invention, an AC motor including a plurality of windings for each phase, a winding switching unit that switches the plurality of windings, and the AC motor are driven. An inverter device, wherein the inverter device outputs a winding switching command signal generator for outputting a winding switching command signal and a plurality of built-in AC motor constants according to the output of the winding switching command signal. The detected value of the motor current flowing through the AC motor until the winding switching unit switches the winding after the constant switching unit switches the motor constant of the AC motor. A winding switching device for an AC motor is applied, which includes a current detection value correction arithmetic unit that corrects according to a change in the motor constant of the AC motor.
Further, the inverter device calculates a current command value to the AC motor as a d-axis and q-axis current command value based on the torque command and the motor constant in a dq coordinate system based on the magnetic flux direction of the AC motor. The current command calculator and the output voltage to the AC motor are calculated so that the d-axis and q-axis current command values coincide with the d-axis and q-axis current detection values that are dq coordinate conversion values of the motor current. And an AC motor winding switching device including a current controller.
Further, the current detection value correction arithmetic unit uses the motor constant before and after switching of the windings, a current command value to the AC motor, a function of the motor current detection value, or a table, and uses the motor current. A winding switching device for an AC motor that calculates a correction value for the detected value is applied.
Further, a winding switching device for an AC motor including at least an armature inductance is applied to the motor constant.
Further, the inverter device includes a PWM controller that performs PWM control of the output voltage in synchronization with a carrier signal and outputs the PWM voltage to the AC motor, and the current detection value correction arithmetic unit is synchronized with the carrier signal. An AC motor winding switching device for correcting the motor current to the detected value is applied.
Further, the current detection value correction computing unit is a winding switching device for an AC motor that performs correction to the detected value of the motor current according to the ratio of the motor constant before and after switching of the winding.
According to another aspect of the present invention, there is provided an AC motor having a plurality of windings for each phase, a winding switching means for switching the plurality of windings, and an inverter device for driving the AC motor. The inverter device includes: a winding switching command signal generator that outputs a winding switching command signal; and a constant switching unit that switches a plurality of motor constants of the AC motor built in accordance with the output of the winding switching command signal. The detected value of the motor current flowing through the AC motor is supplied to the AC motor from the time when the constant switch switches the motor constant of the AC motor until the winding is switched by the winding switching means. A winding switching device for an AC motor is applied, which includes a current detection value correction calculator that corrects the current command value according to changes before and after the winding switching.
Further, the current detection value correction computing unit is applied with a winding switching device for an AC motor that performs correction to the detected value of the motor current in accordance with the ratio of the current command value before and after switching of the winding.

According to another aspect of the present invention, a winding switching command signal connected to an AC motor having the plurality of windings switchable by winding switching means for each phase and outputting a winding switching command signal. A generator, a constant switch for switching the motor constant of the plurality of built-in AC motors according to the output of the winding switching command signal, and after the constant switch switches the motor constant of the AC motor, the winding Until the line switching means switches the windings, the AC motor includes a detected current value correction arithmetic unit that corrects a detected value of the motor current flowing through the AC motor according to a change in the motor constant. An inverter device for driving is applied.
A current command calculator that calculates a current command value to the AC motor as a d-axis and q-axis current command value based on a torque command and the motor constant in a dq coordinate system based on a magnetic flux direction of the AC motor; A current controller that calculates the output voltage to the AC motor so that the d-axis and q-axis current command values coincide with the d-axis and q-axis current detection values that are dq coordinate conversion values of the motor current. An inverter device is applied.
Further, the current detection value correction arithmetic unit uses the motor constant before and after switching of the windings, a current command value to the AC motor, a function of the motor current detection value, or a table, and uses the motor current. An inverter device that calculates a correction value for the detected value is applied.
Further, the current detection value correction calculator is an inverter device that corrects the detected value of the motor current according to the ratio of the motor constant before and after switching of the winding.
According to another aspect of the present invention, a winding switching command signal connected to an AC motor having the plurality of windings switchable by winding switching means for each phase and outputting a winding switching command signal. A generator, a constant switch for switching a motor constant of the plurality of built-in AC motors according to the output of the winding switching command signal, and the constant switcher switches the motor constant of the AC motor, Until the winding is switched by the line switching means, the detected current value for the motor current flowing in the AC motor is corrected according to the change before and after the winding switching of the current command value to the AC motor. The inverter apparatus which drives the said AC motor provided with a correction | amendment calculator is applied.
Further, the current detection value correction calculator is an inverter device that corrects the motor current to a detection value in accordance with a ratio of the current command value before and after switching of the winding.

  According to the present invention, compensation for AC motor generated torque discontinuity before and after winding switching, armature current overshoot, response delay or inconsistency, etc., transition from maximum torque / current control to constant output control, or Since the transition from the constant output control to the maximum torque / current control can be performed smoothly, the torque fluctuation shock can be greatly reduced. As a result, effects such as improved machining accuracy in machine tool spindle drive control and improved ride comfort in the vehicle drive device can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

FIG. 1 is an overall block diagram of a winding switching device for a three-phase AC motor according to the present invention. In the figure, 15 is an inverter device, 20 is a three-phase AC motor, 21 is a position detector, and 30 is a winding switch.
Next, the configuration of the inverter device 15 will be described. Reference numeral 1 denotes a torque command generator that generates a torque command. Reference numeral 2 denotes a current command computing unit, which corresponds to the d-axis current command and q based on the torque command, the d-axis current command correction value output from the constant output controller 12 and the motor constant according to the speed, efficiency or voltage. Generate shaft current command. Reference numeral 3 denotes a current controller that generates a voltage command so that a current flows through the three-phase AC motor 20 following the d-axis current command I _d _ref and the q-axis current command I _q _ref. A PWM controller 4 supplies a variable voltage with a variable frequency to the three-phase AC motor 20 in accordance with a voltage command generated by the current controller 3. Reference numeral 5 denotes a current detector that detects a current flowing through the winding of the three-phase AC motor 20. Reference numeral 6 denotes an A / D converter for converting the current detected by the current detector 5 into a signal used for control calculation. A d-axis current command correction value calculator 7 calculates a d-axis current command correction value using a table or an approximate expression. Reference numeral 8 denotes a speed detector for differentiating the position detected by the position detector 21 to obtain a speed. Reference numeral 9 denotes a winding switching command signal generator that determines a winding switching timing according to the speed and torque command of the three-phase AC motor 20 and generates a winding switching command signal to be given to the winding switching device 30. Reference numeral 10 denotes a constant switch that switches motor constants and control parameters used in the current command calculator 2 and the current controller 3 in accordance with the winding switching command signal. Reference numeral 11 denotes an inter-PN voltage detector that detects the inter-PN voltage of the converter unit output. Reference numeral 12 denotes a constant output controller, and when the inverter output voltage exceeds a set arbitrary maximum voltage, based on a difference between the inverter output voltage and the set arbitrary maximum voltage, a PI control calculation or an I control calculation is performed. A shaft current command correction value is obtained, the output voltage is limited by correcting the d-axis current command, and control is performed to keep the output voltage from the inverter device 15 constant.

The three-phase AC motor 20 has connection terminals (A1 to A6, B1 to B3) for drawing out both ends and intermediate points of each phase of the winding, and can be selected from two winding connection methods. Yes. The position detector 21 detects the rotor position of the three-phase AC motor 20. Usually an encoder or resolver is used.
The winding switch 30 has two winding switching means, and is connected to the terminal end and the intermediate point of the winding of the three-phase AC motor 20 and short-circuits the terminal end or the intermediate point, so that two types of winding characteristics can be obtained. It is the structure which switches. When the terminal is short-circuited, the winding impedance becomes large, so that a large torque can be obtained at a low speed, and by short-circuiting the intermediate point, the impedance can be reduced and a torque can be generated at a high speed.
In the first embodiment, the winding switching device 30 and the inverter device 15 are separately provided. However, the inverter switching device may be an integrated inverter device having a built-in winding switching function. However, when the installation area and wiring man-hours are taken into consideration, the overall merit can be obtained.

  Here, constants that change due to winding switching will be described taking the case of a synchronous motor as an example. The synchronous motor can be expressed as follows when the voltage-current equation is obtained in the dq coordinate system synchronized with the magnetic flux of the rotor.

ただし、ｐ：微分演算子、Ｉ_ｄ，Ｉ_ｑ：ｄ軸，ｑ軸電流、Ｖ_ｄ，Ｖ_ｑ：ｄ軸，ｑ軸電圧、ω：電動機回転子の電気角速度、Ｒ：電機子巻線抵抗、Ｌ_ｄ，Ｌ_ｑ：ｄ軸，ｑ軸の電機子巻線インダクタンス、Φ：電機子鎖交磁束
式（１）からｄｑ軸干渉分および誘起電圧分を補償する電圧フィードフォワードを、

Where p: differential operator, I _d , I _q : d-axis, q-axis current, V _d , V _q : d-axis, q-axis voltage, ω: electric angular velocity of the motor rotor, R: armature winding resistance , L _d , L _q : armature winding inductance of d-axis and q-axis, Φ: armature interlinkage flux Voltage feedforward that compensates for dq-axis interference and induced voltage from equation (1),

とすることによって、同期電動機は単純なＲＬ負荷とみなすことができるため、次のようなＰＩ制御により電流制御器を構成することができる。

Thus, since the synchronous motor can be regarded as a simple RL load, a current controller can be configured by the following PI control.

ただし、Ｉ_ｄ ^＊，Ｉ_ｑ ^＊はｄ軸およびｑ軸の電流指令、Ｋ_Ｐｄ，Ｋ_Ｐｑはそれぞれｄ軸とｑ軸の電流制御器の比例ゲイン、Ｔ_Ｉｄ，Ｔ_Ｉｑは積分時定数、vacrd，vacrqはｄ軸，ｑ軸の電流制御器のＰＩ制御出力である。
ここで、積分時定数と比例ゲインは一般的に電動機定数を元に決定される。例えば、積分時定数Ｔ_Ｉｄ，Ｔ_Ｉｑを電動機の電気的時定数、

Where I _d ^* and I _q ^* are d-axis and q-axis current commands, K _Pd and K _Pq are proportional gains of the d-axis and q-axis current controllers, T _Id and T _Iq are integration time constants, and vacrd , Vacrq are the PI control outputs of the d-axis and q-axis current controllers.
Here, the integration time constant and the proportional gain are generally determined based on the motor constant. For example, the integration time constants T _Id and T _Iq are the electric time constants of the motor,

とすることにより、式（３）と同期電動機との伝達関数は一次遅れ系とみなすことができ、比例ゲインＫ_Ｐｄ，Ｋ_Ｐｑにより応答を設定することができる。この時の応答周波数をfとすると、

Thus, the transfer function between the expression (3) and the synchronous motor can be regarded as a first-order lag system, and the response can be set by the proportional gains K _Pd and K _Pq . If the response frequency at this time is f,

により比例ゲインを求めることができる。
また、トルクは以下の式のようになる。

Thus, the proportional gain can be obtained.
Further, the torque is expressed by the following equation.

ただし、P：極対数
電流指令演算器２は式（４）や高効率位相、および定出力制御などによりｄｑ軸電流指令を求める。
ここで、図１の３相交流電動機２０の巻線の中間点（Ｂ１〜Ｂ３）を各巻線の切換点であるとすると、高速モード時の各電動機定数は以下のようになる。
電機子巻線抵抗：Ｒ_ｈ＝Ｒ／２
ｄ軸，ｑ軸の電機子巻線インダクタンス：Ｌ_ｄｈ = Ｌ_ｄ／４、Ｌ_ｑｈ＝Ｌ_ｑ／４
電機子鎖交磁束：Φ_ｈ＝Φ／２
したがって、これらを用いて演算される値、つまり式（２）の演算用の係数、式（３）の制御定数、および式（４）から求められる電流指令演算のために使用される係数のそれぞれをデータ（巻線1用定数、巻線２用定数）として定数切換器１０で持っておき、巻線切換信号によってそれらの巻線定数を切換えるようにする。

However, P: pole pair current command computing unit 2 obtains a dq-axis current command by equation (4), high efficiency phase, constant output control, and the like.
Here, assuming that the intermediate points (B1 to B3) of the windings of the three-phase AC motor 20 in FIG. 1 are the switching points of the windings, the motor constants in the high speed mode are as follows.
Armature winding resistance: R _h = R / 2
d-axis and q-axis armature winding inductances: L _dh = L _d / 4, L _qh = L _q / 4
Armature interlinkage magnetic flux: Φ _h = Φ / 2
Therefore, the values calculated using these, that is, the coefficients for the calculation of Expression (2), the control constants of Expression (3), and the coefficients used for the current command calculation obtained from Expression (4), respectively. Is stored as data (constant for winding 1 and constant for winding 2) by the constant changer 10, and these winding constants are switched by a winding switching signal.

Next, the operation of the winding switch 30 will be described. FIG. 2 shows an example of the configuration of the winding switch 30. The example of FIG. 2 is the same as FIG. 1 shown in Japanese Patent No. 3948209 in the basic configuration, but a capacitor (C1) is provided for each of the winding switching means 1 and the winding switching means 2 of the winding switching device 30. , C2) and resistors (R1, R2) are different from each other. Thereby, the excess energy at the time of winding switching can be absorbed more effectively. Although only one semiconductor switch (SW1, SW2) for short-circuiting is used, when the capacitance is large, a semiconductor switch may be provided for each phase in parallel with the lower diode on the diode bridge.
Hereinafter, the winding switching operation will be described with reference to FIG. When SW1 is OFF and SW2 is ON, the terminal of the three-phase AC motor 20 is short-circuited, so that the winding impedance becomes maximum. This is called a low speed mode. In this low speed mode, it is easy to obtain a large torque, but it becomes difficult to generate torque as the rotational speed increases. As the rotational speed of the three-phase AC motor 20 increases, the back electromotive voltage increases, and therefore, it is difficult to obtain a voltage necessary for torque generation. Impedance can be reduced by turning SW1 ON and SW2 OFF. This is called a high speed mode. As a result, the back electromotive force is reduced, and the torque can be easily obtained.

In this way, SW1 is turned off, SW2 is turned on at low speed (low speed mode), SW1 is turned on at high speed, and SW2 is turned off (high speed mode). It is possible to achieve both torque generation.
When shifting from the low-speed mode to the high-speed mode with current flowing during acceleration, the energy of the winding sandwiched between SW1 and SW2 switches the switch and at the same time to the capacitor C2 connected in parallel with SW2. Moving. Thereafter, the winding on the inverter side is controlled so as to obtain an appropriate torque according to the control in the high speed mode. However, since the winding impedance becomes small, there may be a temporary increase in current. At the moment of switching, there is a temporary increase in current, but thereafter the torque is controlled according to the torque command from the torque command generator 1, and there is no big shock.
Further, when shifting from the high speed mode to the low speed mode, the energy of the winding moves to the capacitor C1 connected in parallel with SW1 and the terminating side winding. In this case, since the winding impedance becomes large, the current may be temporarily reduced. However, control is performed so that an appropriate torque is obtained according to the control in the low speed mode.

When the three-phase AC motor 20 is driven and the winding is switched from the low speed mode to the high speed mode according to the speed or torque command of the three-phase AC motor 20, the torque command generator 1 generates a torque command T_ref, and the current command This is given to the calculator 2. In this case, the torque command may be a torque command input from the outside or the like, or a torque command that is an output from the speed controller.
When the current command computing unit 2 performs maximum torque / current control, that is, when the current amplitude of the electric motor is set to the same value, the current phase capable of generating the maximum torque is defined as the high efficiency phase β. A d-axis current command is generated by equation (5). Note that β means the phase of the current vector with the direction orthogonal to the main magnetic flux (d-axis) direction being 0, in other words, the current phase with reference to the q-axis direction.

ここで、Ｋはトルク−電流換算係数である。また、ｑ軸電流指令は、式（６）にて求める。

Here, K is a torque-current conversion coefficient. Further, the q-axis current command is obtained by Expression (6).

トルク精度を向上するために、Ｌ_ｄ，Ｌ_ｑの電流による変化を考慮した式（７）を用いてもよい。

In order to improve the torque accuracy, equation (7) that considers changes due to the currents of L _d and L _q may be used.

ここで、Ｋ_ｄはｄ軸電流により変化する係数である。またＫ_ｑはｑ軸電流により変化する係数である。

Here, K _d is a coefficient that varies depending on the d-axis current. K _q is a coefficient that varies depending on the q-axis current.

When the d-axis current command correction value output from the constant output controller 12 is not 0, a value obtained by adding the d-axis current command correction value to the d-axis current command I _d _ref calculated from the equation (5) Using the newly calculated d-axis current command value as the current command value, the q-axis current command value is calculated using Equation (6) or Equation (7).
The d-axis current command I _d _ref and the q-axis current command I _q _ref calculated by the current command calculator 2 are input to the current controller 3. In the current controller 3, the current detected by the current detector 5 is taken in by the A / D converter 6, the three-phase current is converted into the d-axis and q-axis currents to generate a feedback current, and the d-axis current command I _d The voltage commands V _d and V _q are obtained by calculating a deviation amount between _ref and the q-axis current command I _q _ref by PI control or the like. In order to further convert the d-axis and q-axis voltage commands into three-phase voltages to be applied to the three-phase AC motor 20, U-phase, V-phase, and W-phase voltage commands Vu_ref, Vv_ref, and Vw_ref are generated. At this time, the phase θ of the electric motor detected by the position detector 21 is used.
The voltage commands Vu_ref, Vv_ref, Vw_ref generated by the current controller 3 are input to the PWM controller 4, a PWM voltage is applied to the three-phase AC motor 20, and the three-phase AC motor 20 is driven according to the torque command T_ref. .

When the winding is switched on the basis of the speed (hereinafter referred to as winding switching speed), the winding switching command signal generator 9 detects the winding switching speed and the speed of the three-phase AC motor 20 detected by the speed detector 8. And a signal for switching the winding to the high speed mode is generated when the winding switching speed is exceeded. A signal for switching the winding to the high speed mode is given to the winding switch 30 to turn off SW2, turn on SW1, and drive the three-phase AC motor 20 in the high speed mode with reduced impedance. At this time, the constant changer 10 sets the motor constant for the high speed mode in the current command calculator 2 and the current controller 3 to perform control.
Before the winding is switched by the winding switch 30, the d-axis current command correction value calculator 7 uses the table or approximate expression, the torque command T_ref, the speed of the three-phase AC motor 20, and the PN voltage detector 11. The d-axis current command correction value I _d is calculated using the PN voltage detected in step (b).
As an approximate expression, the following expression (8) or expression (9) is used.

ただし、

However,

ここで、Ｖ_ｏｍは電圧出力制限値、Ｉ_ｑ_refは巻線が切り換わる前のｑ軸電流指令を用いる。また、ｄ軸電流指令補正値Ｉ_ｄを算出する式は２式あるが、より電流値が小さくなる式を用い、負荷が増加して、Ｉ_ｄが次式で与えられる値となった場合は式（９）を用いる。

Here, V _om is a voltage output limit value, and I _q _ref is a q-axis current command before the winding is switched. In addition, there are two formulas for calculating the d-axis current command correction value I _d , but when the load increases and I _d becomes a value given by the following formula, a formula with a smaller current value is used. Equation (9) is used.

テーブルを用いてｄ軸電流指令補正値Ｉ_ｄを算出する場合、ＰＮ間電圧変動を考慮したテーブルを用いるか、ＰＮ間電圧を考慮しないテーブルを用いる。ＰＮ間電圧を考慮しないテーブルを用いた場合、トルク指令と速度によって決められたｄ軸電流指令補正値Ｉ_ｄ０にＰＮ間電圧Ｖdcを用いて補正を行い、ｄ軸電流指令補正値Ｉ_ｄを算出する。

When the d-axis current command correction value I _d is calculated using a table, a table considering the PN voltage fluctuation is used, or a table not considering the PN voltage is used. When a table that does not consider the voltage between PNs is used, the d-axis current command correction value _Id is calculated by correcting the d-axis current command correction value _Id0 determined by the torque command and speed using the PN voltage Vdc. To do.

式（８）（９）あるいは（１１）より算出されたｄ軸電流指令補正値Ｉ_ｄは、低速モードから高速モードに切り換えて駆動されるときに、定出力制御器１２の積分器に設定され、積分演算の遅れを補償する。ただし、ｄ軸電流指令補正値Ｉ_ｄが正の値となった場合、定出力制御器１５の積分器には０を設定する。この操作は巻線切換前後の電動機の発生トルクを同一の値に保つための処理であり、この操作により、巻線切換時の電流制御の応答特性を改善することができ、トルクの変動を緩和することができる。
なお、ｄ軸電流指令補正値Ｉ_ｄが正の値の場合は、電動機の主磁束を増磁する方向に作用する電流を意味し、負の値の場合は減磁する方向に作用する電流であることを意味する。
図３は定出力制御器１２の詳細ブロック図を示したものである。電流制御器３より得られる電圧指令Ｖ_ｄ，Ｖ_ｑを振幅演算器４４によって式（１２）に示す演算を行い、減算器４０への電圧フィードバック信号とし、制限電圧指令との偏差量をＰＩ制御器４１にてＰＩ

Equation (8) (9) or (11) d-axis current instruction correction value I _d calculated from, when driven by switching from the low-speed mode to the high speed mode is set to the integrator constant output controller 12 Compensate for delays in integration calculations. However, when the d-axis current command correction value I _d becomes a positive value, 0 is set in the integrator of the constant output controller 15. This operation is a process to keep the generated torque of the motor before and after the winding switching at the same value. This operation can improve the response characteristics of the current control at the time of winding switching and reduce the fluctuation of torque. can do.
In the case d axis current instruction correction value I _d is a positive value means a current that acts to Zo磁the main magnetic flux of the motor, a current that acts to demagnetization in case of negative value It means that there is.
FIG. 3 shows a detailed block diagram of the constant output controller 12. The voltage commands V _d and V _q obtained from the current controller 3 are subjected to the calculation shown in the equation (12) by the amplitude calculator 44 and used as a voltage feedback signal to the subtractor 40, and the amount of deviation from the limit voltage command is PI controlled. PI in vessel 41

制御演算もしくはＩ制御演算し、Ｉ_ｄ指令リミッタ４２と一次遅れフィルタ４３を介して３相交流電動機２０の逆起電圧を抑えるためのｄ軸電流指令補正値とする。すなわち、式（５）で求めたｄ軸電流指令を補正することで出力電圧を制限し、インバータからの出力を一定に保つ制御を行う。ここで、ｄ軸電流指令補正値はＩ_ｄ指令リミッタ４２にて、正の値のときは０にリミットされ、負の値のときは所定の負の最大値にリミットされる。
図４は、（ａ）最大トルク／電流制御の場合と（ｂ）定出力制御の場合の電流ベクトルの様子を示したものである。（ｂ）の定出力制御時は、最大トルク／電流制御の場合に生成されるｄ軸電流指令に対して、さらに負のｄ軸電流が加算されて流れる。そのため、電流Ｉは定出力制御の方が大きくなる。ただし、電動機の端子電圧は図５に示す電圧ベクトルのように、定出力制御時の方が小さくなる（Ｖ→Ｖ′となる）。
図６は低速モード、高速モードにおける制御の切換領域を表わしたものである。図６で示すように、低速モードから高速モードへの切換時は定出力制御から最大トルク／電流制御となり、高速モードから低速モードへの切換時は最大トルク／電流制御から定出力制御となる。

Control operation or I control is calculated, and the d-axis current command correction value for suppressing a back electromotive voltage of the three-phase AC motor 20 via the I _d command limiter 42 and first-order lag filter 43. That is, the output voltage is limited by correcting the d-axis current command obtained by the equation (5), and the output from the inverter is kept constant. Here, in the d-axis current command correction value I _d command limiter 42, when a positive value is the limit to zero, it is a limit to a predetermined maximum negative value when a negative value.
FIG. 4 shows the state of the current vector in the case of (a) maximum torque / current control and (b) constant output control. In the constant output control of (b), a negative d-axis current is further added to the d-axis current command generated in the case of the maximum torque / current control and flows. Therefore, the current I is larger in the constant output control. However, the terminal voltage of the motor becomes smaller during constant output control (V → V ′) as in the voltage vector shown in FIG.
FIG. 6 shows control switching areas in the low speed mode and the high speed mode. As shown in FIG. 6, when switching from the low speed mode to the high speed mode, the constant output control changes to the maximum torque / current control, and when switching from the high speed mode to the low speed mode, the maximum torque / current control changes to the constant output control.

  The difference between the present invention and the prior art is that the d-axis current command correction value calculated by the constant output controller 12 is calculated in advance by the d-axis current command correction value calculator 7 before switching the winding. By setting the integrator of the constant output controller 12 at the timing of winding switching, the delay of the integral calculation is compensated. By this operation, the transition to the constant output control at the time of winding switching or the transition to the maximum torque / current control can be promptly operated. In the high efficiency phase β or the constant output control phase β ′ shown in FIG. The motor can be driven, and the torque shock can be greatly reduced.

FIG. 7 is an overall block diagram of a winding switching device for a three-phase AC motor in Embodiment 2 of the present invention. The difference from FIG. 1 is that a voltage FF (feed forward) calculator 13 is added. Hereinafter, a description will be given with reference to FIG.
When the three-phase AC motor 20 is driven and the windings are switched according to the speed and torque command of the three-phase AC motor 20, and the winding switching is performed at the winding switching speed, the winding switching command signal generator 9 The line switching speed and the speed of the three-phase AC motor 20 detected by the speed detector 8 are compared, and a winding switching command signal is generated. The winding switching command signal is given to the winding switching unit 30, and the three-phase AC motor 20 is driven by switching from the low speed mode to the high speed mode or from the high speed mode to the low speed mode by turning on and off SW1 and SW2. At this time, the constant changer 10 sets the motor constant in the low speed mode or the high speed mode in the current command calculator 2 and the current controller 3 to perform control.
Before the winding is switched by the winding switch 30, the d-axis current command correction value calculator 7 calculates the d-axis current command correction value I _d using a table or an approximate expression. The calculated d-axis current command correction value _Id is set in the integrator of the constant output controller 12 when the winding is switched, and compensates for the delay in the integral calculation. However, when the d-axis current command correction value I _d becomes a positive value, 0 is set in the integrator of the constant output controller 12.
Further, in the voltage FF (feed forward) calculator 13, the d-axis current command I _d _ref corrected by the d-axis current command correction value I _d , the q-axis current command I _q _ref, the speed ω of the three-phase AC motor, the motor Using the constants L _d and L _q , voltage feed forwards V _d _FF and V _q _FF are calculated from the following equations.

式（１３）で算出された電圧フィードフォワードＶ_ｄ_FF，Ｖ_ｑ_FFは、巻線が切り換えられるときに、電流制御器３のｄ軸およびｑ軸の電圧指令に電圧フィードフォワードとして加えられる。
電圧フィードフォワードによって３相交流電動機２０に印加される電圧が巻線切換直後に補償されるため、電流応答を上げることができ、３相交流電動機２０のトルクのショックを大幅に減らすことができる。

The voltage feed forwards V _d _FF and V _q _FF calculated by the equation (13) are added as voltage feed forward to the d-axis and q-axis voltage commands of the current controller 3 when the winding is switched.
Since the voltage applied to the three-phase AC motor 20 by voltage feedforward is compensated immediately after switching the windings, the current response can be increased and the torque shock of the three-phase AC motor 20 can be greatly reduced.

A description will be given of a method of creating a table that takes into account the voltage fluctuation between PNs, which is used to calculate the d-axis current command correction value I _d by the d-axis current correction value calculator 7.
First, the PN voltage is fixed to a constant value, and the low speed mode operation is performed at the winding switching speed. The d-axis current command correction value output from the constant output controller 12 at this time is measured. Here, the torque command is changed from 0 to the maximum torque while a load is applied to the electric motor using a load machine or the like, and the d-axis current command correction value for the torque command is measured. Next, the mode is changed to the high-speed mode, and the d-axis current command correction value output from the constant output controller 12 is measured in the same procedure.
The d-axis current output from the constant output controller 12 at the time of coil switching considering the voltage fluctuation between PN by performing the above procedure while changing the voltage between PN in the voltage range for driving the three-phase AC motor 20. Measure the command correction value.
Based on the data measured as described above, a table that outputs a d-axis current command correction value when a torque command and a PN voltage are input can be created.

Next, a method for creating a d-axis current command correction value I _d calculation table that does not take into account voltage fluctuations between PNs will be described.
First, the PN voltage is fixed to a constant value, and the low speed mode operation is performed at the winding switching speed. The d-axis current command correction value output from the constant output controller 12 at this time is measured. Here, the torque command is changed from 0 to the maximum torque while a load is applied to the electric motor using a load machine or the like, and the d-axis current command correction value for the torque command is measured. Next, the mode is changed to the high-speed mode, and the d-axis current command correction value output from the constant output controller 12 is measured in the same procedure.
Based on the data measured as described above, a table that outputs a d-axis current command correction value when a torque command is input can be created.

FIG. 8 is an overall block diagram of a winding switching device for a three-phase AC motor in Embodiment 4 of the present invention. Portions denoted by the same reference numerals as those in FIG. 1 and FIG. 7 mean the same circuit blocks or functional blocks, and thus description thereof is omitted. For the sake of convenience for explaining the invention according to the fourth embodiment, the original circuit block or the functional block is subdivided by adding a subscript (a, b) to the original code. In the description of the fourth embodiment, circuit blocks or functional blocks that are less relevant are omitted. For example, the constant output controller 12 and the d-axis current command correction value calculator 7 shown in FIG. 1 are not directly involved in the description in the fourth embodiment, and thus are not described. Hereinafter, additional changes will be described with reference to FIG.
Reference numeral 3a denotes a current controller that generates a voltage command so that a current flows through the three-phase AC motor 20 following the d-axis current command I _d _ref and the q-axis current command I _q _ref. 3b corrects the dead time and on-voltage in the switching element, fluctuations in the DC voltage of the converter, etc., calculates each phase voltage so that a voltage in accordance with the voltage command from the current controller 3a is output, and performs PWM control. This is a voltage command setter that corrects the voltage command output to the device 4a. 4a is a PWM controller that supplies a variable voltage with a variable frequency to the three-phase AC motor 20 in accordance with the voltage command corrected and calculated by the voltage command setter 3b, and is composed of a semiconductor switching element or the like. A carrier signal generator 4b generates a carrier signal. A winding switching command signal generator 9a determines the winding switching timing according to the speed and torque command of the three-phase AC motor 20, and provides the winding switching to the constant switching device 10 and the winding switching signal output device 9b. Generate a command signal. Reference numeral 9b denotes a winding switching signal output unit which outputs a driving signal for the switching element of the winding switch 30.
Reference numeral 45 denotes the U-phase and V-phase currents of the three-phase AC motor 20 detected by the current detector 5, which are input via the A / D converter 6, and two phases having a 90-degree phase difference of α and β phases. Is a three-phase two-phase converter that converts the current detection signal into a d-axis current detection signal and a q-axis current detection signal from the α-phase and β-phase current detection signals calculated by the three-phase two-phase converter 45. Dq converter. Reference numeral 14 denotes a d-axis current detection signal and a q-axis current detection signal calculated by the dq converter 46 in accordance with the rate of change in the motor constant, for example, the inductance or the induced voltage constant, which is generated when the winding is switched. It is a current detection value correction calculator for correction.

  Next, the operation at the time of switching the winding in the fourth embodiment will be described. FIG. 9 shows a time chart at the time of winding switching. The carrier signal generator 4b outputs a triangular wave carrier signal 101. The carrier signal 101 is compared with the voltage command signal 105a of each phase output from the voltage command setter 3b, and the semiconductor switching element of the PWM controller 4a is compared. A drive signal is obtained. The carrier signal generator 4 b outputs the carrier synchronization signal 102 simultaneously with the carrier signal 101. FIG. 9 shows an example in which the carrier synchronization signal 102 is output at the peak of the valley side of the carrier signal 101. The current detection process 103 is started with the carrier synchronization signal 102 as a reference. After the current detection process 103 is completed, the current control process 104 is started, and a voltage command is obtained so that the current conforms to the torque command. The voltage command obtained by the current control process 104 is output at the timing of the carrier synchronization signal 102 after the calculation. That is, the setting timing of the voltage command setting 105 requires one cycle of the carrier synchronization signal 102 from the detection of the current until the voltage is discharged.

Here, when the winding switching command signal 106 is generated from the winding switching command signal generator 9a at the timing 106a shown in FIG. 9, the actual winding switching operation is performed after the winding switching command signal 106a is output. This is performed at the timing 102c of the carrier synchronization signal 102 for the second time. That is, the winding switching signal output 108 is output at the timing 108a, and the switching element of the winding switch 30 is driven to perform the winding switching.
Further, the motor constant switching process 107 used for the current control calculation is executed at the timing 107a in accordance with the winding switching command signal 106a. The current control process 104 executed after the motor constant switching process 107 is completed is executed with the constant and current command after the coil switching. However, the current detection value detected by the current detector 5 at this time is the value before switching the winding. Therefore, at the timing of 102b of the carrier synchronization signal 102, the current command is commanded with the value after the coil switching, and the detected current value as the current feedback signal becomes the value before the coil switching, so that mismatch occurs between them.
Therefore, the current detection value correction calculator 14 shows the following equation according to the ratio of the change in the motor constant caused by the switching of the winding, specifically, the ratio of the change in the winding inductance in the low speed mode and the high speed mode. The detected current value is corrected.

In Expressions (14) to (17), I _{d_fb} is the d-axis current detection value, I _{q_fb} is the q-axis current detection value, and I _{d_fbc (L → H)} is the d-axis current detection when switching from the low speed mode to the high speed mode. Correction value, I _{q_fbc (L → H)} is the correction value of q-axis current detection value when switching from low speed mode to high speed mode, and I _{d_fbc (H → L)} is the value when switching from high speed mode to low speed mode The correction value of the d-axis current detection value, I _{q — fbc (H → L)} , indicates the correction value of the q-axis current detection value when switching from the high speed mode to the low speed mode. L _dL and L _qL are the d-axis and q-axis winding inductances in the low-speed mode, and L _dH and L _qH are the d-axis and q-axis winding inductances in the high-speed mode.
By performing the correction processing of the current detection value as described above, the current detection value becomes equivalent to the value after the coil switching, and the deviation between the current command value and the current detection value in the current controller 3a becomes small. The output voltage from the PI controller of the current deviation, that is, the voltage command is smaller than that in the case of none.
Furthermore, since the current detection value used in the current control processing 104 performed at the timing 108a when the winding switching signal output 108 is executed is the value before the winding switching, By correcting the detected value according to the ratio of the change in the winding inductance caused by the switching of the winding by the detected value correction computing unit 14, the detected current value is also equivalent to the value after the switching of the winding, and the current command value and the current The deviation of the detected value becomes smaller, and the output voltage from the PI controller of the current controller 3a becomes smaller than that without correction. By performing the above processing, it is possible to switch the winding smoothly during energization.

  The difference between the present invention and the prior art is that the deviation between the current command and the current detection value is reduced by correcting the current detection value in accordance with the ratio of the change in the winding inductance, which is the motor constant generated when the winding is switched. Therefore, the voltage output from the PI controller of the current controller 3a immediately after the winding switching is reduced. That is, since the mismatch state between the current command and the current detection value associated with the winding switching is alleviated, the current ripple is reduced and the shock of the torque generated by the three-phase AC motor 20 can be greatly reduced.

As shown in the time chart of FIG. 9, the winding switching signal output 108 is executed at the timing 108a at the timing 102c of the second carrier synchronization signal 102 generation after the motor constant switching processing 107 is executed. The switching element of the switch 30 is driven to switch the winding. At this time, the constant switch 10 sets the motor constant in the current command calculator 2 and the current controller 3a to perform control.
When the motor constant is switched, as described in the above-described fourth embodiment, in the process performed by the current controller 3a, a period in which the current command becomes the value after the coil switching and the detected current value becomes the value before the coil switching. Exists twice. Therefore, the current detection value is corrected by the current detection value correction calculator 14 in accordance with the ratio of the change in winding inductance caused by the winding switching. However, their characteristics, including winding inductance and other motor constants, vary with the magnitude of current and temperature.

FIG. 10 shows, as an example, the current dependence of the d-axis and q-axis winding inductances. Therefore, in consideration of the current and temperature dependence of these motor constants, for example, if the winding inductance is corrected by the current command, the current detection value can be corrected more accurately. In this case, the winding inductance may be corrected using an approximate expression based on a linear function or a quadratic function of the current command, or a table for the current command may be prepared. A dotted line connecting the current command calculator 2 and the current detection correction calculator 14 in FIG. 8 corrects the winding inductance by the current command, and uses the corrected winding inductance, the above equations (14) to (17) are obtained. The current detection value is executed and corrected.
Note that it is naturally possible to correct the winding inductance based on the actual detected current value, and the correction can be performed in the same manner as the correction based on the current command described above.

In the fourth and fifth embodiments, the method of correcting the detected current value by the winding inductance is shown. However, the sixth embodiment corrects the current command before and after switching the winding. When the d-axis and q-axis current commands before and after winding switching are I _dL _ref, I _qL _ref in the low speed mode, and I _dH _ref, I _qH _ref in the high speed mode, the current detection value The correction is calculated by the following formula.

  By the above correction process, the detected current value is equivalently a value after switching the winding, and the deviation between the current command value and the detected current value in the current controller 3a is reduced. Therefore, the output voltage from the PI controller of the current deviation, that is, the voltage command becomes smaller than in the case of no correction, so that smooth switching during energization is possible.

Overall block diagram of a winding switching device for a three-phase AC motor in Embodiment 1 of the present invention Detailed configuration diagram of winding switch 30 shown in FIG. Detailed block diagram of the constant output controller 12 shown in FIG. The figure which shows the current vector in the case of (a) the case of maximum torque / current control and (b) constant output control in this invention. The figure which shows the voltage vector in this invention The figure which shows the control area | region of the torque-rotation speed characteristic of the maximum torque / current control and constant output control in the low speed mode and high speed mode in this invention Whole block diagram of winding switching device of three-phase AC motor in Embodiment 2 of the present invention Overall block diagram of a winding switching device for a three-phase AC motor in Embodiment 4 of the present invention Time chart for explaining the operation at the time of switching the winding in the fourth embodiment of the present invention The figure which shows the electric current dependence of the winding inductance of the three-phase alternating current motor in Example 5 of this invention Configuration diagram of winding switching device of conventional three-phase AC motor

DESCRIPTION OF SYMBOLS 1 Torque command generator 2 Current command calculator 3, 3a Current controller 3b Voltage command setter 4, 4a PWM controller 4b Carrier signal generator 5 Current detector 6 A / D converter 7 for current detection d-axis current command Correction value calculator 8 Speed detector 9, 9a Winding switching command signal generator 9b Winding switching signal output device 10 Constant switching device 11 PN voltage detector 12 Constant output controller 13 Voltage FF calculator 14 Current detection value correction Arithmetic unit 15 Inverter 20 Three-phase AC motor 21 Position detector 30 Winding switch 40 Subtractor 41 PI controller 42 I _d command limit 43 First-order lag filter 44 Amplitude calculator 45 Three-phase two-phase converter 46 dq Converter 601 Inverter unit 602 AC motors 603 and 604 Switch 614 Converter unit 615 Smoothing capacitors 616 to 621 Diode 622 Power supply

Claims (14)

AC motor having a plurality of windings for each phase, winding switching means for switching the plurality of windings, and an inverter device for driving the AC motor,
The inverter device includes a winding switching command signal generator that outputs a winding switching command signal;
A constant switching unit that switches a plurality of motor constants of the built-in AC motor according to the output of the winding switching command signal;
The detected value of the motor current flowing in the AC motor is changed from the constant of the constant motor until the winding is switched by the winding switching means after the motor constant of the AC motor is switched. A winding switching device for an AC motor, comprising: AC motor having a plurality of windings for each phase, winding switching means for switching the plurality of windings, and an inverter device for driving the AC motor,
The inverter device includes a winding switching command signal generator that outputs a winding switching command signal;
A constant switching unit that switches a plurality of motor constants of the built-in AC motor according to the output of the winding switching command signal;
The detected value of the motor current flowing through the AC motor is supplied to the AC motor from when the constant switch switches the motor constant of the AC motor until the winding is switched by the winding switching means. A winding switching device for an AC motor, comprising: a current detection value correction calculator that corrects the current command value according to a change before and after the winding switching. The inverter device further calculates a current command value to the AC motor as a d-axis and q-axis current command value based on a torque command and the motor constant in a dq coordinate system based on a magnetic flux direction of the AC motor. A current command calculator,
A current controller that calculates an output voltage to the AC motor so that the d-axis and q-axis current command values match a d-axis and q-axis current detection value that is a dq coordinate conversion value of the motor current; The winding switching device for an AC motor according to claim 1, comprising: The current detection value correction computing unit detects the motor current using the motor constant before and after switching of the windings, a current command value to the AC motor, a function of the motor current detection value, or a table. AC motor winding switching device according to claim 1 or 3, characterized in that to calculate the correction value to the value. The AC motor winding switching apparatus according to any one of claims 1 to 3, wherein the motor constant includes at least an armature inductance. The inverter device further includes a PWM controller that PWM-controls the output voltage in synchronization with a carrier signal and outputs the PWM voltage to the AC motor,
The current detection value correction arithmetic unit includes an AC motor according to any one of claims 1-3, characterized in that in synchronization with the carrier signal to perform the correction to the detected value of the motor current Winding switching device. The said current detection value correction | amendment calculator performs the correction | amendment to the detected value of the said motor current according to the ratio of the said motor constant before and behind the switching of the said coil | winding, The Claim 1 or 3 characterized by the above-mentioned. AC motor winding switching device. The said current detection value correction | amendment calculator performs the correction | amendment to the detected value of the said motor current according to the ratio of the said current command value before and after switching of the said coil | winding. AC motor winding switching device. It is connected to an AC motor equipped with a plurality of windings that can be switched by winding switching means for each phase,
A winding switching command signal generator for outputting a winding switching command signal;
A constant switching unit that switches a plurality of motor constants of the built-in AC motor according to the output of the winding switching command signal;
The detected value of the motor current flowing in the AC motor is changed from the constant of the constant motor until the winding is switched by the winding switching means after the motor constant of the AC motor is switched. And a current detection value correction calculator that corrects according to
An inverter device for driving the AC motor. It is connected to an AC motor equipped with a plurality of windings that can be switched by winding switching means for each phase,
A winding switching command signal generator for outputting a winding switching command signal;
A constant switching unit that switches a plurality of motor constants of the built-in AC motor according to the output of the winding switching command signal;
The detected value of the motor current flowing through the AC motor is supplied to the AC motor from when the constant switch switches the motor constant of the AC motor until the winding is switched by the winding switching means. A current detection value correction calculator that corrects according to the change of the current command value before and after the winding switching,
An inverter device for driving the AC motor. A current command calculator that calculates a current command value to the AC motor as a d-axis and q-axis current command value based on a torque command and the motor constant in a dq coordinate system based on the magnetic flux direction of the AC motor;
A current controller that calculates an output voltage to the AC motor so that the d-axis and q-axis current command values match a d-axis and q-axis current detection value that is a dq coordinate conversion value of the motor current; The inverter device according to claim 9 . The current detection value correction computing unit detects the motor current using the motor constant before and after switching of the windings, a current command value to the AC motor, a function of the motor current detection value, or a table. the inverter apparatus according to claim 9 or 11, characterized in that to calculate the correction value to the value. The current detection value correction computing unit, according to claim 9 or 11, characterized in that to perform the correction of the detected value of the motor current according to a ratio of the motor constants after before switching of the winding Inverter device. The said detected electric current value correction | amendment calculator performs the correction | amendment to the detected value of the said motor electric current according to the ratio of the said electric current command value before and after switching of the said coil | winding. Inverter device.

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