KR101384063B1 - Power supply device for permanent magnet field type linear motor and pwm inverter for permanent magnet field type motor - Google Patents

Abstract

By controlling the supply current to the coils of each phase of the linear motor, a non-uniformity of thrust generated in the coils of each phase can be reduced, and furthermore, a permanent magnet field type linear motor capable of reducing the speed ripple can be provided. . The power supply device 11 for the permanent magnet field type linear motor supplies electric power to the armature 5 of the permanent magnet field type linear motor which makes magnetic flux with the field permanent magnet 4. This power supply device 11 is not located at both ends of the power supply means 13 for supplying a multi-phase alternating current to the polyphase coil of the armature 5 of the linear motor 2 and in the operation direction of the linear motor 2. Current adjustment to reduce the current supplied to the coil of at least one phase (e.g., W phase) that is lower than the current supplied to the remaining two phases (e.g., U and V phases) located at both ends of the operating direction. The means 19 may be employed. Thrust generated in the coils of each phase can be equalized, so that the speed ripple can be reduced.

Speed ripple, permanent magnet for field, thrust, linear motor, armature

Description

POWER SUPPLY DEVICE FOR PERMANENT MAGNET FIELD TYPE LINEAR MOTOR AND PWM INVERTER FOR PERMANENT MAGNET FIELD TYPE MOTOR}

The present invention relates to a power supply for a permanent magnet field type linear motor for supplying electric power to the armature of a permanent magnet field type linear motor for making magnetic flux with a permanent magnet for field, and a permanent magnet field type motor for making magnetic flux with a field permanent magnet The present invention relates to a PWM inverter for a permanent magnet field motor that supplies electric power to an armature.

The linear motor extends the stator side and the movable side of the rotary motor in a straight line shape and converts electrical energy directly into linear thrust. Linear motors, like rotary motors, are classified into DC motors, AC motors, stepping motors, and brushless DC motors. DC motors and brushless DC motors are classified into two types: permanent magnet field type using permanent magnets and electromagnet field type not using permanent magnets.

A permanent magnet field-type linear motor generates thrust in a field permanent magnet or armature by flowing an alternating current through the armature by making a magnetic flux with the field permanent magnet (see Patent Document 1, for example). In the permanent magnet field type linear motor, as shown in Fig. 9, a coil of a polyphase (generally three phase) is wound around the comb teeth 1. Coils are one set with three phases of U, W, and V. Since three sets of coils are provided in plural sets, the total number of coils is an integer multiple of three. The number of teeth of the comb 1 is an integer multiple of 3 equal to the total number of coils. The plurality of coils and comb teeth are arranged side by side in the operating direction of the armature or permanent magnet.

Patent Document 1: Japanese Patent Application Publication No. 2003-70226 (see page 1)

Since the teeth of the U phase and the V phase are necessarily present on both sides of the teeth of the W phase, for example, the magnetic flux φ generated by the coils of the W ₁ phase can pass the teeth of the U ₁ phase and the V ₁ phase of the teeth on both sides, and the coil of the W ₂ phase. The magnetic flux φ generated by can pass through these U ₂ and V ₂ phases on both sides. However, since only the W ₁ phase is adjacent to the U ₁ phase positioned at the end of the comb teeth, the magnetic flux φ generated by the coil of the U ₁ phase passes through the W ₁ phase, but for the region indicated by the broken line in the figure. This is made difficult to pass. The same can be said for the V ₂ phase located at the other end of the comb teeth. In other words, the U and V phase coils located at both ends of the comb teeth have a higher magnetic resistance than the W phase coils. If this causes a current of equal magnitude to each phase coil (U, W, and V phases), the thrust acting on the U and V phase coils becomes smaller than the thrust acting on the W phase coil, resulting in a speed ripple. Occurs.

In order to reduce the speed ripple which arises in a linear motor, various methods are conventionally proposed. For example, Patent Document 1 discloses a method of devising a magnetization direction and arrangement of a permanent magnet on the stator side to make a sine wave the magnetic flux density distribution due to the permanent magnet train, and bring the counter electromotive force induced in the coil to the sine wave. However, in the prior art, there is no technique for reducing the thrust unevenness by controlling the supply current supplied to the coil of each phase, paying attention to the magnetoresistance of the coil of each phase of the linear motor.

Therefore, the present invention can control the supply current to the coils of each phase of the linear motor to reduce the nonuniformity of the thrust generated in the coils of each phase, and furthermore, the power supply for the permanent magnet field type linear motor which can reduce the speed ripple. It is an object to provide a PWM inverter for a device and a permanent magnet field motor.

Hereinafter, the present invention will be described.

In order to solve the said subject, the invention of Claim 1 is a power supply device for permanent magnet field type linear motors which supplies electric power to the armature of a permanent magnet field type linear motor which makes a magnetic flux with a field permanent magnet, and the armature of a linear motor Power supply means for supplying a multi-phase alternating current to the multi-phase coil of and a current for supplying a coil of at least one phase (for example, W phase) which is not located at both ends of the linear motor in the operating direction. It is a power supply device for permanent magnet field type linear motors provided with current adjusting means which reduces the current supplied to the remaining two phases (for example, U phase and V phase) located in both ends.

The invention according to claim 2 is a power supply device for a permanent magnet field type linear motor that supplies electric power to an armature of a permanent magnet field type linear motor that generates magnetic flux with a field permanent magnet, and includes U, V, and W phases of the armature of the linear motor. A power supply circuit for supplying a three-phase alternating current to a three-phase coil comprising: a parallel connection with a coil of one phase (for example, W phase) not located at both ends of an operation direction of the linear motor; Power supply for permanent magnet field type linear motor having a resistance to reduce the current supplied to the coil of the phase to the current supplied to the remaining two phases (for example, U phase and V phase) located at both ends of the operation direction. Device.

The invention as set forth in claim 3 is a PWM inverter for a permanent magnet field-type motor that supplies electric power to an armature of a permanent magnet field-type motor that generates magnetic flux with a permanent magnet for field, and has two upper and lower switching elements operating in pairs. The arm consisting of two upper and lower switching elements operating in pairs is provided in parallel between three phases and a DC power supply for three-phase coils consisting of U, V, and W phases of the armature. It is further provided in parallel between DC power supplies for the lead wires drawn out from the three-phase coil neutral point N, and the control circuit turns on and off the switching element for the three-phase coils and the switching element for the lead-out wires. It is a PWM inverter for controlling permanent magnet field motors.

The invention according to claim 4 is the PWM inverter for permanent magnet field motor according to claim 3, wherein the permanent magnet field motor is a linear motor, and the PWM inverter for permanent magnet field motor is U, the armature of the linear motor; When supplying three-phase alternating current to a three-phase coil consisting of V and W phases, the current is supplied to the coils of one phase (for example, W phase) not located at both ends of the linear motor in the operating direction. It is characterized by reducing than the current supplied to the remaining two phases (for example, U phase and V phase) located at both ends of.

According to the invention as set forth in claim 1, the current supply means supplies current to the coil of at least one phase (e.g., W phase) which is not located at both ends in the operating direction. For example, the thrust generated in the coils of each phase can be equalized since it is reduced than the current supplied to the U phase and the V phase. Therefore, speed ripple can be reduced.

According to the invention as set forth in claim 2, the remaining two phases (e.g., at both ends of the operating direction) supply current to the coil of at least one phase (e.g. For example, the thrust generated in the coils of each phase can be equalized since it is reduced than the current supplied to the U and V phases. Therefore, speed ripple can be reduced.

According to the invention of claim 3, the current supplied to the coil of the three phases of the armature of the motor can be controlled for each phase.

According to invention of Claim 4, the thrust generate | occur | produced in the coil of each phase can be equalized. Therefore, speed ripple can be reduced.

1 is a cross-sectional view taken along the direction of operation of a permanent magnet field linear motor;

2 is a configuration diagram of a power supply device for a permanent magnet field type linear motor according to one embodiment of the present invention.

3 is a diagram illustrating a method of connecting coils of a nia motor.

4 is a graph measuring the generated voltage (back electromotive force) generated in the coils of each phase.

Fig. 5A is a graph showing an example in which three-phase alternating currents of the same amplitude are supplied to the coils of each phase.

Fig. 5B is a graph showing an example in which the amplitude of the current supplied to the coils of the W phase is reduced from the amplitude of the currents supplied to the U and V phases.

Fig. 6 is a block diagram showing a PWM inverter for a permanent magnet field type motor in one embodiment of the present invention.

Fig. 7 is a schematic diagram showing the current flowing through the coil in three phases.

Fig. 8A is a schematic diagram showing the current flowing through the coil in three phases in the first stage of processing.

Fig. 8B is a schematic diagram showing the current flowing through the coil in three phases in the second stage of processing.

9 illustrates a comb teeth of a linear motor.

<Description of Symbols>

2: permanent magnet field type linear motor

3: stator

4: permanent magnet

5: armature

10: coil

11: Power supply for permanent magnet field type linear motor

13, 22: inverter main circuit (power supply means)

19: resistance (power adjusting means)

N: neutral point

20: PWM inverter (power control means) for permanent magnet field motor

21: DC power

22: inverter main circuit (power supply means)

28: control circuit

23, 24, 25: Arm for three-phase coil

23a, 23b, 24a, 24b, 25a, 25b: switching element for three-phase coil

26: arm for neutral point

26a, 26b: switching element for neutral point

27: leader line

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described in detail based on an accompanying drawing.

Fig. 1 shows a cross-sectional view along an operating direction of a permanent magnet field type linear motor, which is an example of the permanent magnet field type linear motor 2, which is operated by the armature side. On the stator 3 side, permanent magnets 4 of the N pole and the S pole are alternately arranged in the operation direction of the armature at a constant pitch. On the armature 5 side, a three-phase coil 10 consisting of U, V, and W phases is provided. The armature 5 is constituted by a comb teeth 9 fixed to the top plate 7 with bolts 8 and the like, and a coil 10 wound around teeth 9a of the comb teeth 9. The coil 10 has one set of three phases of U, W, and V. Since a plurality of sets of three coils 10 are provided, the total number of coils 10 is an integer multiple of three. The number of teeth 9a as the iron core is an integer multiple of 3, similar to the total number of coils 10. The coil 10 is U, W, V,... , U, W, V phases are arranged side by side in the direction of operation of the armature. Both ends of the armature 5 in the operating direction become the U-phase coil 10 and the V-phase coil 10. By flowing a three-phase alternating current through the three-phase coil 10, a moving field that moves linearly is generated, and the armature 5 moves linearly with respect to the stator 3. In addition, the coil 10 may be a coreless coil in which no iron core is provided. The linear motor may be a so-called rod type linear motor in which a coil is wound in a round ring shape around the rod.

Fig. 2 shows a power supply device 11 for a permanent magnet field type linear motor according to one embodiment of the present invention. The power supply device 11 of the present embodiment is constituted by a voltage type PWM inverter (PWM: Pulse Width Modulation) for converting a DC voltage into an AC voltage, and the armature 5 of the linear motor 2 is provided. Supply three-phase alternating current.

The permanent magnet field type linear motor power supply device 11 includes a DC power supply 12, an inverter main circuit 13, and a control circuit 14. The inverter main circuit 13 consists of arms 15, 16, and 17 of three phases (U phase, W phase, and V phase). Each arm 15, 16, 17 is composed of switching elements 15a, 15b, 16a, 16b, 17a, 17b operating in pairs up and down. Each switching element 15a to 17b comprises a parallel connection of a transistor and a flywheel diode. Flywheel diodes are used to return current in reverse with respect to the transistor. The on / off of the switching elements 15a to 17b is determined by the on / off signal of the transistor. By turning on and off the switching element, the three-phase AC voltage can be output equivalently by changing the pulse width of the output voltage without changing the magnitude of the DC voltage. As the switching elements 15a to 17b, a metal oxide semi-conductor field effect transistor (MOSFET) or an insulated gate bipolar mode transistor (IGBT) can be used.

The control circuit 14 outputs a PWM signal for controlling the on and off of the transistor. As a generation method of a PWM signal, the triangular wave comparison method which obtains the voltage of a pulse train by comparing the three-phase sine wave voltage command and the triangular wave (carrier) which is a carrier wave, for example is used. When the transistor is turned on or off by the PWM signal using the triangular wave comparison method, the voltage of the pulse train approximated to the three-phase AC voltage is output from the inverter main circuit 13. When the 3-phase AC voltage is output from the inverter main circuit 13, the 3-phase AC current is supplied to the 3-phase coil of the linear motor. If two transistors connected in series in each phase are turned on at the same time even for a slight time, a short circuit of the DC voltage will cause a breakdown of the transistor. Therefore, the on and off signals of the two transistors have a short circuit prevention time for both. It is set.

3 shows a method of connecting coils in a linear motor. The connection method includes a Δ connection (delta connection) for connecting the coil in a ring shape, and a Y connection (star) in which U, V, and W of three coils are massed. 3 shows a star connection generally used.

The voltage output from the inverter main circuit 13 is the line voltage between WV, WU, and UV. When a voltage is applied between the WV lines, a current flows simultaneously through the coils of the W phase and the coils of the V phase. When a voltage is applied between the WV lines, the current flows simultaneously through the coils of the W phase and the coils of the U phase. Therefore, no matter how softly the voltage output from the inverter is controlled, the current supplied to the coil of phase W cannot be reduced while the magnitude of the current supplied to the coil of phase V remains the same. It is not possible to reduce the current supplied to the W-phase coil while maintaining the magnitude of the current. For this reason, in this embodiment, the resistor 19 is connected in parallel with the coil of the W phase in order to reduce the current supplied to the W phase more hardly than the current supplied to the coils of the U and V phase. This resistor 19 may be provided in the power supply device or may be provided in the linear motor.

When a resistor 19 is connected in parallel to the W phase coil and a line voltage is applied between the WVs, current is branched to the resistance 19 side and the W phase coil side as indicated by the arrow 1 in the figure. The current flowing on the resistor 19 side and the current flowing on the coil side of V phase join at the neutral point N, and then flow through the coil of V phase. As indicated by the outline arrow (2) in the figure, even when current in the opposite direction flows from the coil of V to the coil of W, the current flowing through the coil of V is the current and resistance (19) flowing from the neutral point (N) to the coil of the W phase. It branches to the current flowing to the side. Then, it joins and returns to the inverter main circuit 13. Similarly, even when the line voltage is applied between the WUs, the current flowing in the coil of the W phase branches into the current flowing in the resistor 19 side and the current flowing in the coil side of the W phase. By connecting the resistors 19 in parallel to the W phase coil in this manner, the current flowing through the W phase coil can be reduced without affecting the current flowing through the U phase or V phase coils.

Fig. 4 shows a graph measuring the generated voltage (back electromotive force) generated in the coils of each phase when the armature is moved at a constant speed. When measuring this generated voltage, electric current is not supplied to an armature, and the resistor 19 is not connected in parallel to the coil of W phase.

Since the coil of the W phase is not located at both ends of the linear motor operating direction, the magnetoresistance is smaller than that of the other U and V phases. For this reason, as shown in Fig. 4, the amplitude of the generated voltage at both ends of the coil of the W phase becomes larger than the amplitude of the generated voltage generated in the coil of the U phase or the V phase. That is, the counter electromotive force constant of the coil of the W phase becomes larger than the counter electromotive force constant of the coil of the U phase or the V phase. In the case of a DC motor, since the counter electromotive force constant and the torque constant are the same, when three-phase alternating current having the same amplitude flows through the three-phase coil, the torque generated by the coil of W phase becomes larger than the torque generated by the coil of U phase or V phase. This causes speed ripples that do not result in constant speed.

In order to eliminate the velocity ripple, instead of supplying a current having the same amplitude to the three-phase coil as shown in FIG. 5A, the current supplied to the coil of the W phase is supplied to the coil of the U or V phase as shown in FIG. 5B. What is necessary is just to reduce (namely, make amplitude small) than current. According to the coil connection method shown in Fig. 3, since the resistor 19 is connected in parallel to the coil of the W phase, the current supplied to the coil of the W phase can be reduced more than the current supplied to the coil of the U phase or the V phase. For this reason, the dispersion | variation in the thrust generate | occur | produced by the coil of each phase can be eliminated, and also the speed ripple can be reduced. The size of the resistor 19 is determined in consideration of the deviation of the counter electromotive force constant of the coil of each phase or the inductance of the coil of each phase.

In the case where a resistor is connected in parallel to the W-phase coil, the connection of the motor may be a Δ connection, and the motor driving method may be a unipolar drive using three semiconductor elements. The motor may be a four-phase motor, not a three-phase motor.

Fig. 6 shows a PWM inverter 20 (PWM: Pulse Width Modulation) for a permanent magnet field motor according to an embodiment of the present invention. The PWM inverter 20 converts a DC voltage into an AC voltage to supply a three-phase AC current to the armature of the linear motor.

The PWM inverter 20 includes a DC power supply 21, an inverter main circuit 22, and a control circuit 28. The inverter main circuit 22 carries arms U, V, W of the arm 23, 24, 25 made up of two switching elements 23a, 23b, 24a, 24b, 25a, and 25b which are operated in pairs. It is provided in parallel between three phase parts and the DC power supply 21 for the three-phase coils which consist of phases. In addition, the inverter main circuit 22 of the present embodiment draws an arm 26 composed of two upper and lower switching elements 26a and 26b operating in pairs from the neutral point N of the three-phase coil in which the star is connected. It is provided in parallel between the direct current power sources 21 for the lead wire 27. That is, while the arm 26 which consists of two upper and lower switching elements 26a and 26b is connected in parallel to the DC power supply 21, the lead wire 27 is drawn out from the neutral point N, and the upper switching element is carried out. The lead wire 27 drawn out from the neutral point N is connected between the 26a and the lower switching element 26b.

Each of the arms 23 to 26 is composed of switching elements 23a to 26b operating in pairs up and down. Each switching element 23a to 26b comprises a parallel connection of a transistor and a flywheel diode. Flywheel diodes are used to return current in reverse with respect to the transistor. The on / off of the switching element is determined by the on / off signal of the transistor. By turning on and off the switching element, the three-phase AC voltage can be output equivalently by changing the pulse width of the output voltage without changing the magnitude of the DC voltage. As the switching element, a MOSFET (Metal Oxide Semi-conductor Field Effect Transistor) or an IGBT (Insulated Gate Bipolar mode Transistor) can be used.

In the conventional PWM inverter 11 (refer to FIG. 2) which provided the arm for three-phase coils, without providing the arm for neutral points, a three-phase alternating voltage by turning on and off the switching element of the arm for three-phase coils. Outputs However, as described above, since the voltage output from the inverter main circuit 13 is the line voltage between WV, WU, and UV, for example, at the point of (1) of Fig. 5A, when the switching element is on, WV The line voltage (for example, 280V) is applied between the lines, and the line voltage (for example, 280V) is applied between WVs. At this time, as shown in FIG. 7, current I ₁ flows through the coils in the W phase and the coils in the U phase, and currents I ₂ flow through the coils in the W phase and the coils in the V phase. For this reason, only the current supplied to the coil of the W phase cannot be reduced while maintaining the current supplied to the U or V phase.

In order to solve this problem, in the PWM inverter 20 of this embodiment, the arm 26 is provided for the lead wire drawn out from the neutral point N, for example, the switching element in the point (1) of FIG. 5A. Is divided into two stages. Specifically, as shown in Fig. 8A, in the first step, the current I ₃ flows from the coil of the W phase to the lead line 27, and the current does not flow to the coils of the U and V phases. On the other hand, as shown in Fig. 8B, in the second process, the current I ₄ flows from the leader line 27 to the coil of U phase, and at the same time, the current I ₅ from the leader line 27 to the coil of V phase. Flows, so that no current flows through the coil of the W phase. Table 1 shows two switching modes of the PWM inverter 20.

By adjusting the processing time for each of the first and second stages, only the magnitude of the current flowing in the W phase can be reduced while the magnitude of the current flowing in the U phase or the V phase remains the same. Since the current flowing through the coils in the W phase can be reduced, the variation in thrust generated by the coils in each phase can be eliminated, and the speed ripple can be reduced. The PWM signal for turning on and off the switching element is created by the control circuit.

In addition, the control according to the conventional triangular wave comparison method of comparing the three-phase sine wave voltage command and the triangular wave (carrier), which is a carrier wave, to obtain the voltage of the pulse train, and the current only in the coils of the U and V phases without passing a current through the coils of the W phase. The combination of the control of the switching mode in the second stage of passing through can reduce the current flowing through the coil of the W phase.

By providing the arm 26 for the neutral point N, not only the current flowing through the coil of the W phase can be reduced, but also the current flowing through the coil of the W phase can be increased. In addition, even when a current flows from U to V, U to W, and V to U and V to W, by providing a two-stage switching mode, it is possible to control the current flowing through the U-phase coil and the V-phase coil. Therefore, it becomes possible to control the current flowing through the coil of each phase.

This specification is based on the JP Patent application 2006-234412 of an application on August 30, 2006. All of this is included here.

Claims (4)

It is a power supply device for permanent magnet field type linear motor that supplies electric power to the armature of the permanent magnet field type linear motor that makes magnetic flux with the field permanent magnet. A multiphase coil installed in plural in the operating direction of the armature of the linear motor, Power supply means for supplying a multiphase alternating current to the polyphase coil of the armature of the linear motor, Permanently provided with current adjusting means for reducing the current supplied to the coils of at least one phase not located at both ends of the linear motor in operation direction from the current supplied to the coils of the remaining two phases located at both ends of the linear motor direction. Power supply for magnetic field linear motors. It is a power supply device for permanent magnet field type linear motor that supplies electric power to the armature of the permanent magnet field type linear motor that makes magnetic flux with the field permanent magnet. A power supply circuit for supplying a three-phase alternating current to a three-phase coil consisting of U, V, and W phases of the armature of the linear motor, It is connected in parallel with a coil of one phase which is not located at both ends of the linear motor in an operating direction, and the current supplied to the coil of one phase is higher than the current supplied to the other two phases which are located at both ends in the operating direction. A power supply for a permanent magnet field type linear motor having a resistance to reduce. It is a PWM inverter for permanent magnet field motor that supplies electric power to the armature of the permanent magnet field motor which makes magnetic flux with the field permanent magnet. An arm composed of two upper and lower switching elements operating in pairs is provided in parallel between three phases and a DC power supply for a three-phase coil composed of the U, V, and W phases of the armature. An arm consisting of two upper and lower switching elements operating in pairs is further provided in parallel between the DC power supplies for the lead wires drawn out from the neutral point of the star-connected three-phase coil, The PWM inverter for permanent magnet field type motor which controls ON / OFF of the said switching element for the said three-phase coils, and the said switching element for the said leader line by a control circuit. The method of claim 3, wherein the permanent magnet field motor is a linear motor, The PWM inverter for the permanent magnet field-type motor is not located at both ends in the operation direction of the linear motor when supplying a three-phase alternating current to a three-phase coil composed of U, V, and W phases of the armature of the linear motor. A PWM inverter for permanent magnet field type motor, characterized in that the current supplied to the coil of the upper phase is reduced than the current supplied to the remaining two phases located at both ends of the operation direction.

Images