JP7673012B2 - Control device for wound-rotor induction motor and method thereof, and wound-rotor induction motor system - Google Patents

Description

The present invention relates to a control device for a wound-type induction motor that controls a wound-type induction motor having a primary winding and a secondary winding, a control method for a wound-type induction motor, and a wound-type induction motor system that includes the control device for a wound-type induction motor.

Induction motors are broadly divided into wound-rotor induction motors and squirrel-cage induction motors. Wound-rotor induction motors can control torque and rotation speed by controlling the secondary resistance, and are therefore used in equipment that requires a relatively large capacity, such as pumps, trains, and cranes. For example, Patent Document 1 describes this secondary resistance control.

This patent document 1 discloses a system that includes a wound-type induction motor, a speed detector, a diode rectifier, a secondary resistor, and a secondary switching control circuit that connects the secondary winding of the wound-type induction motor to the diode rectifier via a conductor when the rotational speed of the wound-type induction motor detected by the speed detector is 50% to 70% or more of the rated rotational speed, and connects the secondary winding of the wound-type induction motor to the secondary resistor via another conductor when the rotational speed is less than the rated speed.

JP 2005-229725 A

The secondary resistor in Patent Document 1 has a variable resistance value as shown in Figures 1 to 3, but does not disclose how to change the resistance value. In general, the resistance value of the secondary resistor is changed manually, for example to obtain a desired rotation speed.

The present invention was made in consideration of the above circumstances, and its purpose is to provide a control device for a wound-rotor induction motor and a control method for a wound-rotor induction motor that can automatically change the secondary resistance value, as well as a wound-rotor induction motor system equipped with the control device for the wound-rotor induction motor.

After various studies, the inventors have found that the above object can be achieved by the present invention described below. That is, a control device for a wound-type induction motor according to one aspect of the present invention is a device for controlling a wound-type induction motor having a primary winding and a secondary winding, and includes a secondary resistance unit connected to the secondary winding and having a variable resistance value, a pattern generation unit that generates a plurality of different time-series resistance value patterns in the secondary resistance unit, a prediction unit that predicts, for each of the plurality of time-series resistance value patterns generated by the pattern generation unit, the value of a predetermined physical quantity related to the control purpose of the wound-type induction motor when the resistance value of the secondary resistance unit is changed in the time-series resistance value pattern, as a predicted value, a pattern selection unit that selects, from the plurality of time-series resistance value patterns generated by the pattern generation unit, a time-series resistance value pattern corresponding to the most highly evaluated predicted value among the predicted values of the wound-type induction motor predicted by the prediction unit, and a secondary resistance control unit that controls the secondary resistance unit based on the time-series resistance value pattern selected by the pattern selection unit.

This type of control device for a wound-rotor induction motor can determine the resistance value of the secondary resistance section through predictive control, so the secondary resistance value can be changed automatically.

In another aspect, in the above-mentioned control device for a wound-type induction motor, the secondary resistance section includes at least one resistance element unit including a resistance element and a changeover switch that switches whether or not the resistance element is connected to the secondary winding. Preferably, in the above-mentioned control device for a wound-type induction motor, the secondary resistance section includes a plurality of resistance element units connected in cascade.

Such a control device for a wound-rotor induction motor can increase the resistance value patterns by the simple method of increasing the number of resistance element units in cascade connection. By increasing the number of resistance element units, the specified physical quantities related to the control purpose of the wound-rotor induction motor can be set in detail (set with high resolution), allowing the wound-rotor induction motor to be controlled in detail (control with high resolution).

In another aspect, in the above-mentioned control device for a wound-rotor induction motor, the predetermined physical quantity related to the control objective of the wound-rotor induction motor is the rotation speed.

This makes it possible to provide a control device for a wound-rotor induction motor that can control the rotation speed.

In another aspect, in the above-mentioned control device for a wound-rotor induction motor, the predetermined physical quantity related to the control objective of the wound-rotor induction motor is torque.

This makes it possible to provide a control device for a wound-rotor induction motor that can control torque.

In another aspect, in the above-mentioned control device for a wound-rotor induction motor, the pattern selection unit selects the most highly evaluated predicted value by using an evaluation value based on the deviation between the control target value and the predicted value.

This type of control device for a wound-rotor induction motor evaluates the predicted value using an evaluation value based on the deviation between the control target value and the predicted value, making it possible to select a predicted value that has high tracking ability to the control target value.

In another aspect, in the above-mentioned control device for a wound-type induction motor, when generating the multiple time-series resistance value patterns, the pattern generation unit selects the subsequent resistance value of two resistance values that are arranged one behind the other in the time series from among the previous resistance value, a resistance value that is one greater than the previous resistance value, and a resistance value that is one less than the previous resistance value when the multiple resistance values that can be variably generated in the secondary resistance unit are arranged in order of magnitude.

This type of control device for a wound-rotor induction motor controls the secondary resistance section so that the two resistance values that are arranged one after the other in a time series are shifted by one, so the wound-rotor induction motor can be controlled to operate smoothly.

A control method for a wound-type induction motor according to another aspect of the present invention is a method for controlling a wound-type induction motor having a primary winding and a secondary winding connected to a secondary resistance section having a variable resistance value, and includes a pattern generation step of generating a plurality of different time-series resistance value patterns in the secondary resistance section, a prediction step of predicting, for each of the plurality of time-series resistance value patterns generated in the pattern generation step, a value of a predetermined physical quantity related to the control purpose of the wound-type induction motor when the resistance value of the secondary resistance section is changed in the time-series resistance value pattern, a pattern selection step of selecting, from the plurality of time-series resistance value patterns generated in the pattern generation step, a time-series resistance value pattern corresponding to the most highly evaluated predicted value among the predicted values of the wound-type induction motor predicted in the prediction step, and a secondary resistance control step of controlling the secondary resistance section based on the time-series resistance value pattern selected in the pattern selection step.

This type of control method for a wound-rotor induction motor can determine the resistance value of the secondary resistance section through predictive control, so the secondary resistance value can be changed automatically.

A wound-type induction motor system according to another aspect of the present invention includes a wound-type induction motor having a primary winding and a secondary winding, and a wound-type induction motor control unit that controls the wound-type induction motor, and the wound-type induction motor control unit is any one of the above-mentioned wound-type induction motor control devices.

This makes it possible to provide a wound-rotor induction motor system equipped with any one of the above-mentioned control devices for a wound-rotor induction motor. Since the above-mentioned wound-rotor induction motor system is equipped with any one of the above-mentioned control devices for a wound-rotor induction motor, the resistance value of the secondary resistance section can be determined by predictive control, and the secondary resistance value can be changed automatically.

The control device for a wound-rotor induction motor and the control method for a wound-rotor induction motor according to the present invention can automatically change the secondary resistance value. According to the present invention, a wound-rotor induction motor system equipped with the control device for a wound-rotor induction motor can be provided.

1 is a diagram showing a configuration of a wound-rotor induction motor system according to an embodiment; 5 is a diagram for explaining an example of a time-series resistance value pattern that can be realized in a secondary resistor unit of the wound-rotor induction motor system. FIG. 4 is a flowchart showing an operation of the wound-type induction motor system. 13 is a diagram for explaining an example of a time-series resistance value pattern when a constraint is imposed. FIG. FIG. 13 is a diagram showing a simulation result in the case of no load. FIG. 13 is a diagram showing a simulation result when a load torque is applied. FIG. 2 is a diagram showing a schematic configuration of the wound-type induction motor system when applied to a trolley truck. FIG. 8 is a diagram showing a simulation result when the wound-type induction motor system shown in FIG. 7 is applied to a trolley cart. FIG. 13 is a diagram showing a simulation result of a comparative example.

One or more embodiments of the present invention will be described below with reference to the drawings. However, the scope of the invention is not limited to the disclosed embodiments. Note that components with the same reference numerals in each drawing are the same components, and their description will be omitted as appropriate. In this specification, when referring to a general term, a reference numeral without a subscript is used, and when referring to an individual component, a reference numeral with a subscript is used.

In an embodiment, the wound induction motor system includes a wound induction motor having a primary winding and a secondary winding, and a wound induction motor control unit that controls the wound induction motor. The wound induction motor control unit includes a secondary resistance unit connected to the secondary winding and having a variable resistance value, a pattern generation unit that generates multiple time-series resistance value patterns in the secondary resistance unit so that the resistance values are different from each other, a prediction unit that predicts, for each of the multiple time-series resistance value patterns generated by the pattern generation unit, a value of a predetermined physical quantity related to the control purpose of the wound induction motor when the resistance value of the secondary resistance unit is changed in the time-series resistance value pattern, as a predicted value, a pattern selection unit that selects, from the multiple time-series resistance value patterns generated by the pattern generation unit, a time-series resistance value pattern corresponding to the most highly evaluated predicted value of each predicted value of the wound induction motor predicted by the prediction unit, and a secondary resistance control unit that controls the secondary resistance unit based on the time-series resistance value pattern selected by the pattern selection unit. Below, we will explain in more detail about a wound-rotor induction motor system equipped with such a control unit for a wound-rotor induction motor.

Figure 1 is a diagram showing the configuration of a wound-rotor induction motor system in an embodiment. Figure 1A shows the whole system, and Figure 1B is a block diagram showing the configuration of the MPC control unit. Figure 2 is a diagram for explaining an example of a time-series resistance value pattern that can be realized by the secondary resistance unit of the wound-rotor induction motor system.

The wound-type induction motor system SM in the embodiment includes, for example, a wound-type induction motor IM having a primary winding and a secondary winding, a predictive control control unit (MPC control unit) CL, and a secondary resistance unit RU, as shown in FIG. 1A. In this embodiment, as will be understood later, the secondary resistance unit RU and the MPC control unit CL correspond to a control unit for a wound-type induction motor that controls the wound-type induction motor, i.e., an example of a control device for a linear induction motor.

The wound-rotor induction motor IM is supplied with three-phase AC power from a power source (not shown), and a secondary resistance unit RU is connected to its secondary winding.

The secondary resistor unit RU is a resistor having a variable resistance value. The secondary resistor unit RU is connected to the MPC control unit CL, and changes its resistance value according to the control of the MPC control unit CL. The secondary resistor unit RU may be a variable resistor of a slider type or a rotary type, etc., whose slider position or rotation position can be electrically controlled. For example, in this embodiment, the secondary resistor unit RU includes at least one resistor element unit UT including a resistor element R and a changeover switch S for switching whether or not the resistor element R is connected to the secondary winding, and changes the resistance value in a stepped manner (discretely changes the resistance value). In the example shown in FIG. 1A, the secondary resistor unit RU includes four first to fourth resistor element units UT ₁ to UT ₄ , and can change the resistance value of the secondary side (secondary circuit, secondary winding side) in five stages, including the resistance value R _rm of the secondary winding in the wound-type induction motor IM, as shown in the following Table 1.

More specifically, the fourth resistor unit _UT4 includes a first-phase resistor element _R4 , a second-phase resistor element _R4 , a third-phase resistor element _R4 , a switch S4 for turning on and off the connection between the first phase and the second phase, a switch _S4 for turning on and off the connection between the second phase and the _third phase, and a switch _S4 for turning on and off the connection between the third phase and the first phase, and is connected to the secondary winding. The third resistor unit _UT3 includes a first-phase resistor element _R3 , a second-phase resistor element _R3 , a third-phase resistor element _R3 , a switch S3 for turning on and off the connection between the first phase and the second phase, a switch _S3 for turning on and off the connection between the _second phase and the third phase, and a switch S3 for turning on and off the connection between the third phase and _{the first phase} , and is cascade-connected to the fourth resistor unit _UT4 . Similarly, the second resistor unit _UT2 includes a first-phase resistor element _R2 , a second-phase resistor element _R2 , a third-phase resistor element _R2 , a switch _S2 for turning on and off the connection between the first phase and the second phase, a switch S2 for turning on and off the connection between the second phase and the _third phase, and a switch _S2 for turning on and off the connection between the third phase and the first phase, and is cascade-connected to the third resistor unit _UT3 . The first resistor unit _UT1 includes a first-phase resistor element _R1 , a second-phase resistor element _R1 , a third-phase resistor element _R1 , a switch _S1 for turning on and off the connection between the first phase and the second phase, a switch _S1 for turning on and off the connection between the second phase and the third phase, and a switch _S1 for turning on and off the connection between the third phase and the first phase, and the first phase, second phase, and third phase are wired together. In other words, the first phase resistor element R4 in the fourth resistor unit UT4, the first phase resistor element _R3 in the third resistor unit _UT3 , the first phase resistor element _R2 in the second resistor unit _UT2 , and the first phase resistor element _R1 in the first resistor unit _UT1 are connected in series in this order from the secondary winding to the first phase line; the second phase resistor element _R4 in the fourth resistor unit _UT4 , the second phase resistor element R3 in the third resistor unit UT3, the second phase resistor element _R2 in the second resistor unit _UT2 , and the second phase resistor element _R1 in the first resistor unit _UT1 are connected in series in this order from the secondary winding to the second phase line; and the third phase resistor element _R4 in the fourth resistor unit _UT4 , the second phase resistor element R3 in the third resistor unit _UT3 , the second phase resistor element _R2 in the second resistor unit UT2, and the second phase resistor element R1 in the first resistor unit _UT1 are connected in series in this order from the secondary winding to the third phase line _. , the third phase resistance element _R3 in the third resistance element unit _UT3 , the third phase resistance element _R2 in the second resistance element unit _UT2 , and the third phase resistance element _R1 in the first resistance element unit _UT1 are connected in series in this order, and the resistance elements _R1 , _R1 , _R1 of each phase are wired together. The switches S4, S4, S4 in the fourth resistor unit _UT4 are arranged between the secondary winding and the resistor elements _R4 , _R4 , _R4 of each phase in the fourth resistor unit _UT4 , the switches _S3 , _S3 , _S3 in the third resistor unit UT3 are arranged between the resistor elements _R4 , _R4 , _R4 of each phase in the _fourth resistor unit _UT4 and the resistor elements _R3 , _R3 , _R3 of each phase in the _third resistor unit UT3, the switches _S2 , _S2 , _S2 in the _second resistor unit UT2 are arranged between the resistor elements _R3 , _R3 , _R3 of each phase in the _third resistor unit UT3 and _the resistor elements _R2 , _R2 , _{R2 of} each phase in _{the second} resistor unit UT2, The switches S1, _S1 , S1 in _{the first} resistor element unit _UT1 are arranged between the resistor elements _R2 , _R2 , _R2 of each phase in the first resistor element unit UT2 and the resistor elements _R1 , _R1 , _{R1 of} each phase in the first resistor element unit _UT1 . These switches _{S4 , S4, S4, S3, S3, S3, S2, S2, S2 , S1 , S1 , S1 are connected to the MPC} control unit CL and their on/off is controlled by the MPC control unit CL. _Each of these switches _S4 , _S4 , _S4 , S3, _S3 , _S3 , _S2 , _S2 , _S2 , _S1 , _S1 , and _S1 is configured to include a so-called power switching element such as an insulated gate bipolar transistor (IGBT), etc. For convenience of explanation, the symbol R of a resistive element also represents its resistance value.

In the secondary resistance unit RU configured as described above, when changing to the first resistance value, the number of notch steps n is set to 1, and as shown in the following Table 2, all of the switches S4, _S4 , _S4 , _S3 , _S3 , _S3 , _S2 , _S2 , _S2 , _S1 , _S1 , _S1 are controlled to be off (OFF), and this first resistance value _Rr1 becomes ^Rrm + _R4 + _R3 + _R2 + _R1 as shown in Table ¹ ( _Rr1 = _Rrm + _R4 + _R3 + _{R2 + R1} ) _. When changing to the second resistance value, the number of notch steps n is set to 2, and as shown in Table 2, only the switches _S1 , _S1 , and _S1 of the first resistor element unit _TU1 are controlled to be on (ON), and the remaining switches _S3 , _S3 , _S3 , _S2 , _S2 , _S2 , _S1 , _S1 , and _S1 are controlled to ^be off, and this second resistance value _Rr2 becomes _Rrm + _R4 + _R3 + _R2 as shown in Table ¹ ( _Rr2 = _Rrm + _R4 + _R3 + _R2 ). When changing to the third resistance value, the number of notch steps n is set to 3, and as shown in Table 2, the switches _S1 , _S1 , _S1 , _S2 , _{S2 ,} and _S2 of the first and second resistance element units TU1 and _TU2 are controlled to be on, and the remaining switches _S4 , _S4 , _S4 , _S3 , _S3 , and _S3 are controlled to be off, and ^this third resistance value _Rr3 becomes _Rrm + _R4 + _R3 as shown in Table ¹ ( _Rr3 = _Rrm + _R4 + _R3 ). When changing to the fourth resistance value, the number of notch steps n is set to 4, and as shown in Table 2, the switches _{S1 ,} S1, S1, S2, _S2 , _S2 , _S2 , _S2 , _S2 , and _S2 of _the first to third resistor element units _TU1 , _TU2 , and _TU3 are controlled to be on, and only the remaining switches _S4 , _S4 , and _S4 are ^controlled to be off, and this fourth resistance value _Rr4 becomes _Rrm + _R4 as shown in Table 1 ⁽ _Rr4 = _Rrm + _R4 ). When changing to the fifth resistance value, the number of notch steps n is set to 5, and as shown in Table 2, all of the switches _S4 , _S4 , _S4 , S3, _S3 , _S3 , _S2 , _S2 , _S2 , _S1 , _S1 , _S1 are controlled to be on, and ^this fifth resistance value _Rr5 becomes _Rrm as shown in Table 1 ( _Rr5 = ^Rrm _, i.e., _the resistance value of the secondary resistance unit RU is 0).

1A, when the number of resistance values of the secondary resistance unit RU is increased, the resistance element units UT in the number corresponding to the number of resistance values to be increased are sequentially cascaded to the first resistance element unit _TU1 , and each phase in the terminal resistance element unit UT is connected to each other. That is, in this embodiment, since one of the resistance values on the secondary side includes the resistance value _Rrm of the secondary winding in the wound-type induction motor IM (including the resistance value 0 of the secondary resistance unit RU), when the number of resistance values on the secondary side is α, the secondary resistance unit RU can be configured by sequentially cascading the number of first resistance element units TU obtained by subtracting 1 from the number α (α-1).

The MPC control unit CL is a device for controlling the wound-rotor induction motor IM through predictive control by controlling the resistance value of the secondary resistance unit RU. The MPC control unit CL is configured, for example, as a microcomputer equipped with a CPU (Central Processing Unit), memory and its peripheral circuits. In the MPC control unit CL, a control unit 11, a pattern generation unit 12, a prediction unit 13, a pattern selection unit 14 and a secondary resistance control unit 15 are functionally configured by executing a predetermined program.

The control unit 11 controls each part of the wound-rotor induction motor system SM according to the function of each part, and is responsible for controlling the entire wound-rotor induction motor system SM.

The pattern generating unit 12 generates a plurality of time-series resistance value patterns in the secondary resistor unit RU so that the resistance values are different from each other. That is, the pattern generating unit 12 performs a pattern generating process to generate a plurality of time-series resistance value patterns in the secondary resistor unit RU so that the resistance values are different from each other. In this embodiment, the secondary resistor unit RU can be changed to five resistance values _Rr ⁱ (i=1, 2, 3, 4, 5) as described above. The time-series voltage pattern is determined by a prediction horizon, which is the number of control periods to be predicted, and a control horizon, which is the number of control periods in which the resistance value, which is the control input, is made variable. For this reason, the numerical values of the prediction horizon and the control horizon are appropriately set in advance in the MPC control unit CL according to the specifications of the wound-type induction motor system S, and the pattern generating unit 12 generates a plurality of time-series voltage patterns that are different from each other according to the resistance value (five in the above description) that can be changed in the secondary resistor unit RU, the numerical value of the prediction horizon, and the numerical value of the control horizon. 2, as an example, all time-series resistance value patterns that can be realized by the secondary resistance unit RU when the prediction horizon is 2 and the control horizon is 1 are illustrated in a tree diagram. In FIG. 2, since the prediction horizon is 2 for the resistance value in the current (Current) k-th control, the resistance value in the next (k+1)-th control and the resistance value in the further next (k+2)-th control are predicted, and since the control horizon is 1, all time-series voltage patterns that can be realized by the secondary resistance unit RU are five sets of time-series resistance value patterns that branch from the resistance value in the current k-th control to five ^first to ^fifth resistance values _Rr1 to _Rr5 in the next (k+ ¹ )-th control, and are maintained at the respective resistance values _Rr1 to _Rr5 from each of the resistance values _Rr1 ^to _Rr5 in the further next ^{( k} +2)-th control. As another example, when the prediction horizon is 2 and the control horizon is 2, since the prediction horizon is 2, the resistance value in the next (k+1)th control and the resistance value in the next (k+2)th control are predicted for the resistance value in the current kth control, and since the control horizon is 2, all time-series resistance value patterns that can be realized by the secondary resistance unit RU are branched into five first to fifth resistance values _Rr1 to _Rr5 for each of the (k+1 ⁾ th control and the (k+ ² )th control, resulting in 25 (=5 x 5) sets of time-series resistance value patterns.

The prediction unit 13 predicts, as a predicted value, a value of a predetermined physical quantity related to a control objective of the wound-type induction motor IM when the resistance value of the secondary resistance unit RU is changed in the time-series resistance value pattern for each of the multiple time-series resistance value patterns generated by the pattern generation unit 12. That is, the prediction unit 13 performs a prediction process to predict, as a predicted value, a value of a predetermined physical quantity related to a control objective of the wound-type induction motor IM when the resistance value of the secondary resistance unit RU is changed in the time-series resistance value pattern for each of the multiple time-series resistance value patterns generated by the pattern generation unit 12. More specifically, in this embodiment, the predetermined physical quantity related to the control objective of the wound-type induction motor IM is the rotation speed, and therefore, for each of the multiple time-series resistance value patterns generated by the pattern generation unit 12, the prediction unit 13 obtains (predicts) an output torque T _e by the following equation 1, and obtains (predicts) a rotation speed ω _m by the following equation 2. n represents the notch step number, and therefore, the output torque _T ^en (k+1) is the output torque T at the notch step number n in the (k+1)th control, and the rotational speed ω _m ⁿ (k+1) is the rotational speed ω at the notch step number n in the (k+1)th control.

ここで、ｎ_ｐｈは、誘導機の極対数であり、Ｖ_１－１は、１次側（１次回路、１次巻線側）の線間電圧実効値であり、Ｒ_ｓは、１次側の抵抗値であり、ω_ｍは、巻線形誘導電動機ＩＭの実測された回転速度であり、ｆ_０は、１次側の電圧の周波数であり（ｆ_０＝ω_０／２π）、ｌ_ｓは、１次側の漏れインダクタンスであり、ｌ_ｒは、２次側の漏れインダクタンスである。回転速度ω_ｍは、例えばロータリエンコーダ（パルスジェネレータ）や、ホールＩＣ等を備えて構成される、巻線形誘導電動機ＩＭの回転速度を測定する図略の回転速度センサで実測される。Ｊは、巻線形誘導電動機ＩＭにおける回転子（ロータ）の慣性モーメントであり、Ｄは、巻線形誘導電動機ＩＭにおける回転子の動摩擦トルクであり、Ｔ_ｓは、制御周期である。なお、現在、ｋ番目の制御の場合、（ｋ＋１）、（ｋ＋２）、（ｋ＋３）、・・・は、予測値であることを表している。

Here, n _ph is the number of pole pairs of the induction motor, V _1-1 is the effective line voltage value of the primary side (primary circuit, primary winding side), R _s is the resistance value of the primary side, ω _m is the measured rotation speed of the wound-type induction motor IM, f ₀ is the frequency of the voltage on the primary side (f ₀ =ω ₀ /2π), l _s is the leakage inductance on the primary side, and l _r is the leakage inductance on the secondary side. The rotation speed ω _m is measured by a rotation speed sensor (not shown) that measures the rotation speed of the wound-type induction motor IM, which is configured to include, for example, a rotary encoder (pulse generator) or a Hall IC. J is the moment of inertia of the rotor in the wound-type induction motor IM, D is the dynamic friction torque of the rotor in the wound-type induction motor IM, and T _s is the control period. In the case of the kth control, (k+1), (k+2), (k+3), . . . represent predicted values.

_Tl in Equation 2 is the load torque, and is, for example, an estimated value estimated by the following Equation 3.

ここで、文字変数の上に付された“＾”は、その推定値であることを表す。したがって、Ｔ_ｌ＾（ｋ－１）は、前回の制御で推定した（ｋ－１）番目の制御での負荷トルクであり、ω_ｍ＾（ｋ）は、前回の制御で推定した（ｋ）番目の制御での回転速度である。なお、文字変数の上に付された“＾”は、記載の都合上、前記文字変数に続けて“＾”を記載している。Ｋ_ＬＴは、ゲインであり、例えば複数のサンプルから予め適宜に設定される。

Here, the "^" placed above the character variables indicates that they are estimated values. Therefore, T _l ^(k-1) is the load torque in the (k-1)th control estimated in the previous control, and ω _m ^(k) is the rotation speed in the (k)th control estimated in the previous control. Note that the "^" placed above the character variables is written following the character variables for convenience of description. K _LT is a gain, and is appropriately set in advance from a plurality of samples, for example.

In the above example, for the five possible first to fifth resistance values _Rr1 ^to _Rr5 that can be achieved by the secondary resistance unit RU in the current kth control, the prediction unit 13 obtains five sets of predicted values [ _Tei ⁽ k+ ¹ ), _Tei (k+2)] for up to two control cycles ahead and [ ^{ωmi (} k+1), _ωmi (k+2)] for up to two control cycles ahead (i=1, 2 _, 3 ^, 4, 5).

The pattern selection unit 14 selects, from among the multiple time-series resistance value patterns generated by the pattern generation unit 12, a time-series resistance value pattern corresponding to the most highly evaluated predicted value among the predicted values of the wound-type induction motor IM predicted by the prediction unit 13. That is, the pattern selection unit 14 performs a pattern selection process of selecting, from among the multiple time-series resistance value patterns generated by the pattern generation unit 12, a time-series resistance value pattern corresponding to the most highly evaluated predicted value among the predicted values of the wound-type induction motor IM predicted by the prediction unit 13. The pattern selection unit 14 selects the most highly evaluated predicted value by using an evaluation value based on the deviation between a control target value and the predicted value. More specifically, in the above example, since the predetermined physical quantity related to the control objective of the wound-rotor induction motor IM is the rotational speed, the pattern selection unit 14 quantitatively evaluates each of the multiple time-series resistance value patterns generated by the pattern generation unit 12 by using the predicted value [ _ωmi (k+1 ⁾ , _ωmi (k+2)] of the rotational speed ^of the wound-rotor induction motor IM predicted by the prediction unit 13 in an evaluation formula g ⁿ of the following formula 4, for example, and selects a time-series resistance value pattern corresponding to the most highly evaluated predicted value [ _ωmi (k+1), ^ωmi (k+2)] of the rotational speed from among the multiple time _- series resistance value patterns. In this formula 4, the smaller the numerical value, the higher ^the evaluation.

ここで、ω_ｍ ^＊（ｋ＋ｉ）は、（ｋ＋ｉ）番目の制御における回転速度の制御目標値であり、Ｎ_ｐは、前記予測ホライズンである。なお、ＭＰＣ制御部ＣＬには、外部から回転速度の制御目標値ω_ｍ ^＊が入力され、設定される。

Here, _ωm ^* (k+i) is the control target value of the rotation speed in the (k+i)th control, and _Np is the prediction horizon. The control target value _ωm ^* of the rotation speed is input from the outside and set in the MPC control unit CL.

The secondary resistance control unit 15 controls the secondary resistance unit RU based on the time-series resistance value pattern selected by the pattern selection unit 14. That is, the secondary resistance control unit 15 performs a secondary resistance control process for controlling the secondary resistance unit RU based on the time-series resistance value pattern selected by the pattern selection unit 14. More specifically, in this embodiment, when the kth control is currently being performed, the secondary resistance control unit 15 outputs a control signal for switching on and off each of the switches S4, S4, _S4 , _S3 , S3, _S3 , S2, _S2 , _S2 , S1, _S1 , _S1 so that the resistance value _Rri in the next (k+1)th control in ^the time-series resistance value pattern selected by _the pattern selection unit ₁ becomes the resistance value Rri in the _next (k _{+ 1)} th control.

Then, the control unit 11 causes the pattern generation unit 12, the prediction unit 13, the pattern selection unit 14 and the secondary resistance control unit 15 to repeatedly perform the pattern generation process, the prediction process, the pattern selection process and the secondary resistance control process at a predetermined control period.

Next, the operation of this embodiment will be described. Figure 3 is a flowchart showing the operation of the wound-type induction motor system.

When the power is turned on in such a wound-rotor induction motor system SM, the necessary parts are initialized and start to operate. Then, for example, by executing a program, the CPU is functionally configured with a control part 11, a pattern generation part 12, a prediction part 13, a pattern selection part 14, and a secondary resistance control part 15.

Then, each of the processes S11 to S15 shown in FIG. 3 is repeatedly executed by the control unit 11 at a predetermined control period until the driving of the wound-type induction motor IM is stopped.

In FIG. 3, first, at this time (kth), the MPC control unit CL acquires the rotation speed ω _m (k) of the wound-rotor induction motor IM from the rotation speed sensor (not shown) by the control unit 11 (S11).

Next, the MPC control unit CL generates multiple time-series resistance value patterns in the secondary resistance unit RU, which are different from each other, by the pattern generation unit 12 (S12, pattern generation process). In this embodiment, multiple time-series resistance value patterns are generated according to the preset prediction horizon value and control horizon value.

Next, the MPC control unit CL predicts, by the prediction unit 13, the value of a predetermined physical quantity related to the control objective of the wound-type induction motor IM when the resistance value of the secondary resistance unit RU is changed in each of the multiple time-series resistance value patterns generated by the pattern generation unit 12 in process S12, as a predicted value (S13, prediction process). In this embodiment, the predetermined physical quantity is the rotation speed, and for each of the multiple time-series resistance value patterns generated by the pattern generation unit 12 in process S12, the output torque T _e is calculated by Equation 1, and the rotation speed _ωm is calculated by Equation 2 and Equation 3.

Next, the MPC control unit CL selects, by the pattern selection unit 14, from among the multiple time-series resistance value patterns generated by the pattern generation unit 12 by process S12, the time-series resistance value pattern corresponding to the most highly evaluated predicted value of the wound-rotor induction motor IM predicted by the prediction unit 13 by process S13 (S14, pattern selection process). In this embodiment, for each of the multiple time-series resistance value patterns generated by the pattern generation unit 12 by process S12, its evaluation value is calculated by Equation 4, and the time-series resistance value pattern that gives the smallest evaluation value is selected.

Then, the MPC control unit CL controls the secondary resistance unit RU by the secondary resistance control unit 15 based on the time-series resistance value pattern selected by the pattern selection unit 14 in process S14, and ends this process at the current control timing (S15, secondary resistance control process). In this embodiment, the secondary resistance unit RU is controlled so that the resistance value _Rri is the resistance value ^Rri in the next (k+1)th control.

In this manner, the wound-rotor induction motor IM is controlled and driven by predictive control so that the rotational speed ω _m ^* becomes the target value for control.

As described above, the control device for a wound-rotor induction motor in the embodiment (secondary resistance unit RU and MPC control unit CL) and the control method for a wound-rotor induction motor implemented therein, as well as the wound-rotor induction motor system SM, can determine the resistance value of the secondary resistance unit RU by predictive control, and therefore can automatically change the secondary resistance value.

The above-mentioned control device for a wound-rotor induction motor, control method for a wound-rotor induction motor, and wound-rotor induction motor system SM can increase the resistance value patterns by the simple method of increasing the number of resistance element units UT in cascade connection. By increasing the number of resistance element units UT, the specified physical quantity related to the control purpose of the wound-rotor induction motor IM (in the above example, the rotation speed) can be set finely (set with high resolution), so the wound-rotor induction motor IM can be controlled finely (with high resolution).

The above-mentioned control device for a wound-rotor induction motor, control method for a wound-rotor induction motor, and wound-rotor induction motor system SM evaluate the predicted value using an evaluation value based on the deviation between the control target value and the predicted value, so that a predicted value with high tracking ability to the control target value can be selected.

According to this embodiment, a control device for a wound-rotor induction motor capable of controlling the rotation speed, a control method for a wound-rotor induction motor, and a wound-rotor induction motor system SM can be provided, and a wound-rotor induction motor system SM equipped with the control device for the wound-rotor induction motor can be provided.

In the above embodiment, the pattern selection unit 14 can select any one of the multiple time-series resistance value patterns as long as it has the highest evaluation value, but the options may be restricted. More specifically, for example, the options are restricted by restricting the options when generating the multiple time-series resistance value patterns. For example, when generating the multiple time-series resistance value patterns, the pattern generation unit 12 selects the latter resistance value of two resistance values that are arranged in chronological order from the previous resistance value, a resistance value that is one value larger than the previous resistance value, and a resistance value that is one value smaller than the previous resistance value when the multiple resistance values that can be variably generated in the secondary resistance unit RU are arranged in order of magnitude. Such a control device for a wound-type induction motor, a control method for a wound-type induction motor, and a wound-type induction motor system SM control the secondary resistance unit RU so that the resistance value is a resistance value that is shifted by one value from the two adjacent resistance values, and therefore the wound-type induction motor IM can be controlled to drive smoothly.

Figure 4 is a diagram for explaining an example of a time-series resistance value pattern when a constraint is set. For example, the five sets of time-series resistance value patterns shown in Figure 2 become three sets of time-series resistance value patterns shown in Figure 4, and the pattern selection unit 14 selects the resistance value pattern that gives the highest evaluation value from among these three sets of time-series resistance value patterns.

Simulation results for this modified form are shown in Figures 5 and 6, respectively. Figure 5 is a diagram showing simulation results when there is no load. Figure 6 is a diagram showing simulation results when a load torque is applied. Figures 5A and 6A respectively show the change over time in rotation speed, and Figures 5B and 6B show the change over time in the number of notch stages. The horizontal axis of each of Figures 5A and 6A is the elapsed time from the start of startup (start of speed control), and each of these vertical axes is the rotation speed. The horizontal axis of each of Figures 5B and 6B is the elapsed time from the start of startup, and each of these vertical axes is the number of notch stages.

From FIG. 5A, it can be seen that when speed control is performed with no load and acceleration, the target speed can be followed without delay or large deviation. And from FIG. 5B, it can be seen that the speed control can be performed by changing the notch step number by one at a time. On the other hand, FIG. 6 shows the simulation result when a load torque is applied while driving a wound-type induction motor at a constant speed, and from FIG. 6A, it can be seen that the target speed can be followed, as in the case of FIG. 5A. And even in this case, from FIG. 6B, it can be seen that the speed control can be performed by changing the notch step number by one at a time. Note that in FIGS. 5 and 6, the actual measurement results are shown by solid lines and the simulation results are shown by dashed lines, but these are almost overlapping and cannot be distinguished from each other.

In these simulations, the control period is 30 Hz, and therefore the switching period for the number of notch stages is also a maximum of 30 Hz. Generally, when an inverter is used to control an electric motor, the switching period of the inverter is on the order of several kHz. For this reason, when an inverter is used in the secondary circuit, there is a high possibility that a large surge voltage will be generated, which may result in effects such as accelerating the deterioration of peripheral devices such as slip rings. In the wound-type induction motor system of this embodiment, good control can be achieved at 30 Hz, which is less than 1/100 of that, as described above, and because the switching period is small, the above-mentioned effects expected when using an inverter can also be significantly reduced.

We will also explain the simulation results when the wound-rotor induction motor system SM in the embodiment is applied to a trolley truck, and the simulation results of a comparative example.

7 is a diagram showing a schematic configuration when the wound induction motor system is applied to a trolley cart. FIG. 8 is a diagram showing a simulation result when the wound induction motor system shown in FIG. 7 is applied to a trolley cart. FIG. 9 is a diagram showing a simulation result of a comparative example. FIGS. 8A and 9A respectively show the time change of the position of the trolley cart, FIGS. 8B and 9B respectively show the time change of the rotation speed at that time, and FIGS. 8C and 9C show the time change of the notch stage number at that time. The horizontal axis of each of FIGS. 8A and 9A is the elapsed time from the start of starting (start of speed control), and each of these vertical axes is the position (Position) of the trolley cart. The horizontal axis of each of FIGS. 8B and 9B is the elapsed time from the start of starting, and each of these vertical axes is the rotation speed (Speed). The horizontal axis of each of FIGS. 8C and 9C is the elapsed time from the start of starting, and each of these vertical axes is the notch stage number. In Figures 8 and 9, the actual measurement results are shown by solid lines, and the simulation results are shown by dashed lines.

The wound-type induction motor system SM in the embodiment is used for position control of the trolley cart VC. As shown in FIG. 7, the wound-type induction motor IM is used as a power source of the trolley cart VC, and the output shaft of the wound-type induction motor IM is connected to the driving wheel DT of the trolley cart VC via the reduction gear GA. As a result, the output torque of the wound-type induction motor IM is transmitted to the driving wheel DT via the reduction gear GA, the driving wheel DT rotates, and the trolley cart VC moves. The current position x of the trolley cart VC and the control target value x ^* of the position are differentiated by the difference calculator SB, and the difference is P-controlled (proportional controlled) by the P controller PCL, and becomes the control target value ω _m ^* of the rotation speed, which is input to the MPC controller CL. The MPC controller CL controls the resistance value of the secondary resistor unit RU by predictive control as described above at the control period 20 [Hz], prediction horizon 5, and control horizon 1, and thereby the rotation speed of the wound-type induction motor IM is controlled.

As shown in FIG. 8, such a wound-rotor induction motor system SM can track the rotational speed control target value _ωm ^* generated by a position controller comprising a differentiator SB and a P controller PCL, and although there is a slight deviation from the position control target value x ^* , it can accurately position the position x of the trolley cart VC.

On the other hand, in the comparative example, instead of the above-mentioned MPC control unit CL, a speed feedback control unit that performs general speed feedback control is used. In this comparative example, as shown in Fig. 9, the notch step number is determined according to the magnitude of the position deviation, so the change amount of the input notch step number is large, and a relatively large pulsation occurs in the rotation speed. In particular, in the simulation result around 25 [s], even in a situation where selecting a larger notch step number would exceed the position control target value x ^* , control is performed to increase the notch step number, resulting in a position deviation. By increasing the switching period and control period, the position deviation is reduced, but there is a possibility of a large surge voltage being generated.

When controlling the rotation speed by switching the secondary resistance, it is difficult to make fine adjustments to the rotation speed, and it is necessary to ensure control precision by increasing the switching period and control period. However, by using the wound-rotor induction motor system SM in this embodiment, it is possible to keep the switching period to a few tens of Hz and achieve more precise control than with conventional methods.

In the above embodiment, the predetermined physical quantity related to the control objective of the wound-rotor induction motor is the rotational speed, but the predetermined physical quantity related to the control objective of the wound-rotor induction motor may be torque. This provides a control device for a wound-rotor induction motor, a control method for a wound-rotor induction motor, and a wound-rotor induction motor system SM that are capable of torque control. In this case, for example, the following equation 5 is used to calculate the evaluation value instead of equation 4 for finding the evaluation value. Alternatively, for example, when a rotational speed limit ω _{m_lim} is set in the torque control, the following equation 6 is used.

ここで、Ｔ_ｅ ^＊（ｋ＋ｉ）は、（ｋ＋ｉ）番目の制御における出力トルクの制御目標値である。

Here, T _e ^* (k+i) is the control target value of the output torque in the (k+i)th control.

In order to express the present invention, the present invention has been described above adequately and sufficiently through the embodiments with reference to the drawings. However, it should be recognized that a person skilled in the art can easily modify and/or improve the above-mentioned embodiments. Therefore, unless the modification or improvement implemented by a person skilled in the art is at a level that deviates from the scope of the claims described in the claims, the modification or improvement is interpreted as being included in the scope of the claims.

SM Wound-rotor induction motor system IM Wound-rotor induction motor CL Predictive control unit (MPC control unit)
RU Secondary resistor unit UT Resistance element unit S Switch R Resistance element 11 Control unit 12 Pattern generation unit 13 Prediction unit 14 Pattern selection unit 15 Secondary resistor control unit

Claims (8)

A control device for a wound-type induction motor that controls a wound-type induction motor having a primary winding and a secondary winding,
a secondary resistance section connected to the secondary winding and having a variable resistance value;
a pattern generating unit that generates a plurality of different time-series resistance value patterns in the secondary resistor unit;
a prediction unit that predicts, for each of a plurality of time-series resistance value patterns generated by the pattern generation unit, a value of a predetermined physical quantity related to a control purpose of the wound-type induction motor when the resistance value of the secondary resistance unit is changed in the time-series resistance value pattern; and
a pattern selection unit which selects, from among the plurality of time-series resistance value patterns generated by the pattern generation unit, a time-series resistance value pattern corresponding to a most highly evaluated predicted value among the predicted values of the wound-rotor induction motor predicted by the prediction unit;
a secondary resistance control unit that controls the secondary resistance unit based on the time-series resistance value pattern selected by the pattern selection unit.
Control device for wound-rotor induction motor. the secondary resistance section includes at least one resistance element unit including a resistance element and a change-over switch for switching whether or not the resistance element is connected to the secondary winding;
2. The control device for a wound-rotor induction motor according to claim 1. The predetermined physical quantity related to the control objective of the wound-rotor induction motor is a rotation speed.
3. The control device for a wound-rotor induction motor according to claim 1 or 2. The predetermined physical quantity related to the control objective of the wound-rotor induction motor is torque.
3. The control device for a wound-rotor induction motor according to claim 1 or 2. the pattern selection unit selects the most highly evaluated predicted value by using an evaluation value based on a deviation between a control target value and the predicted value;
5. The control device for a wound-rotor induction motor according to claim 1. When generating the plurality of time-series resistance value patterns, the pattern generating unit selects a subsequent resistance value among two resistance values arranged in a chronological order from a previous resistance value, a resistance value that is one step larger than the previous resistance value, and a resistance value that is one step smaller than the previous resistance value when a plurality of resistance values that can be variably generated in the secondary resistance unit are arranged in order of magnitude.
6. The control device for a wound-rotor induction motor according to claim 1. 1. A control method for a wound-type induction motor, comprising:
a pattern generating step of generating a plurality of time-series resistance value patterns in the secondary resistance portion, the resistance value patterns being different from one another;
a prediction step of predicting, for each of a plurality of time-series resistance value patterns generated in the pattern generation step, a value of a predetermined physical quantity related to a control purpose of the wound-type induction motor when the resistance value of the secondary resistance unit is changed in the time-series resistance value pattern;
a pattern selection step of selecting, from the plurality of time-series resistance value patterns generated in the pattern generation step, a time-series resistance value pattern corresponding to a most highly evaluated predicted value among the predicted values of the wound-rotor induction motor predicted in the prediction step;
and a secondary resistance control step of controlling the secondary resistance unit based on the time-series resistance value pattern selected in the pattern selection step.
A control method for a wound rotor induction motor. a wound-type induction motor having a primary winding and a secondary winding;
a control unit for a wound-rotor induction motor that controls the wound-rotor induction motor,
The control unit for the wound-rotor induction motor is a control device for a wound-rotor induction motor according to any one of claims 1 to 6.
Wound rotor induction motor system.

Images