JP2011199984A - Motor driving system - Google Patents

Abstract

Provided is a motor drive system having a wide operation area, realizing high-efficiency operation in each operation area, and realizing miniaturization.
A drive system of a winding switching motor includes a plurality of semiconductor switches each having a power MOSFET and a gate drive circuit using a pulse transformer, and the in-phase connection patterns of the plurality of windings are connected in series or in parallel. Switching control for switching to connection and switching the interphase connection pattern to star connection or delta connection, and switching control for supplying on / off control signals to the plurality of semiconductor switches in accordance with the stator winding connection pattern employed And a drive control device that determines the stator winding connection pattern and controls the switching control device, and includes an inverter and controls the inverter so that multiphase AC power is supplied to the stator winding. It has.
[Selection] Figure 3

Description

  The present invention relates to a motor drive system including a motor that can be operated by switching connection patterns of a plurality of windings constituting a stator winding.

  In conventional manufacturing methods for motors, the wire diameter, number of turns, connection method (delta connection or star connection), etc. are determined according to the required torque or rotational speed, supplied voltage or current, etc. The lead wires at the beginning and end of each phase of the three-phase alternating current are physically connected by terminal terminals or the like. Therefore, it was difficult to change the structure later.

  On the other hand, the following Patent Documents 1 to 4 take out the lead wires at the beginning and end of each phase (and intermediate lead wires) to the outside of the motor, and switch to star connection or delta connection with a switch, We propose a technology that provides an inverter motor that can be operated at both low and high speeds without increasing the size of the motor by realizing a structure that switches multiple windings in the phase to series connection or parallel connection. ing.

  On the other hand, a drive system such as a robot requires a wider speed and torque adjustment range in order to apply to a wide range of load conditions. For example, as shown in FIG. 1, in a crawler vehicle, low speed and high torque are required when moving up and down stairs, medium speed and medium torque are required when traveling on rough ground, and high speed and low torque are required when traveling on flat ground. . In the walking machine, the support leg requires a low speed and a high torque, and the free leg requires a medium speed and a medium torque or a high speed and a low torque.

  The conventional motor technology alone cannot cover the entire operating range of torque and speed required in a drive system such as a robot. In addition, in the application of a motor to a drive system such as a robot, in addition to the expansion of the operation area, downsizing is also required.

JP 2006-148999 A JP 2008-182783 A JP 2008-178207 A JP 2008-160920 A

  The present invention has been made in view of the above-described background, and its purpose is to have a wide operating range of low speed and high torque, medium speed and medium torque, and high speed and low torque. The object is to provide a motor drive system that realizes high-efficiency operation and miniaturization. The prior art for realizing a wide speed and torque adjustment range in the drive system and the object and positioning of the present invention are shown in FIG.

  In order to achieve the above object, according to the present invention, there is provided a motor drive system including a motor operable by switching a connection pattern of a plurality of windings constituting a stator winding, using a power MOSFET and a pulse transformer. Winding switching that switches the internal connection pattern of the multiple windings to series connection or parallel connection, and switches the interphase connection pattern to star connection or delta connection, using multiple semiconductor switches each equipped with a gate drive circuit. A circuit, a switching control device for supplying an on / off control signal to the plurality of semiconductor switches according to the employed stator winding connection pattern, and controlling the switching control device by determining a stator winding connection pattern A drive control device that includes an inverter and controls the inverter so that multi-phase AC power is supplied to the stator winding; A motor drive system for Bei is provided.

  In one preferred embodiment, an electronic board on which the winding switching circuit is mounted is built in the motor. Only three lead wires corresponding to the three-phase synchronous motor are led out from the motor.

  Moreover, in one suitable aspect, this drive control apparatus is comprised so that the instruction | command regarding the switching of this stator winding connection pattern and the timing and sequence of this switching may be received.

  Also, in one preferred aspect, the switching control device aims at a target by sequentially turning on or off a semiconductor switch corresponding to a phase in which no current flows or is minimized. Switch to the stator winding connection pattern.

  According to the present invention, since the winding switching circuit is configured by a plurality of semiconductor switches each having a power MOSFET and a gate drive circuit using a pulse transformer, the device configuration for switching the winding is greatly reduced in size. Can be built into the motor. In addition, the adoption of a semiconductor switch makes it possible to switch the stator winding connection pattern during operation. In addition, by sequentially turning on or off the semiconductor switch corresponding to the phase where current is not flowing or minimized, switching to the target stator winding connection pattern is realized. Variations in speed and torque over time can be minimized.

It is a figure which shows the speed and torque characteristic requested | required with drive systems, such as a robot. It is a figure which shows the objective and positioning of the prior art for implement | achieving the adjustment range of a wide speed and torque in a drive system, and this invention. It is a block diagram showing one embodiment of a motor drive system by the present invention. FIG. 4 is a circuit diagram illustrating a circuit configuration of a stator winding and a winding switching circuit in FIG. 3 in a form that is easier to understand. It is a figure which shows the ON or OFF state of each semiconductor switch for implement | achieving various connection patterns in FIG. It is a circuit diagram which shows one structural example of a semiconductor switch. It is a wave form diagram which shows the voltage induced by the on / off control signal and pulse transformer secondary side which are supplied to a semiconductor switch. It is a figure which illustrates the generated voltage characteristic of a motor. It is a figure which illustrates the rotation speed characteristic of a motor.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 3 is a block diagram showing an embodiment of a motor drive system according to the present invention. As shown in FIG. 3, the motor drive system includes a stator winding 10 of the motor, a winding switching circuit 20, a switching control device 30, and a drive control device 40.

  The stator winding 10 has six unit windings (coils), namely, U1-U2 winding, U3-U4 winding, V1-V2 winding, V3-V4 winding, W1-W2 winding, and W3. -Includes W4 winding. The winding switching circuit 20 includes 15 semiconductor switches, that is, SU1, SU2,..., SU5, SV1, SV2,..., SV5, SW1, SW2,. The connection pattern of a plurality of unit windings can be switched.

  FIG. 4 is a circuit diagram showing the circuit configurations of the stator winding 10 and the winding switching circuit 20 in an easily understandable form, and FIG. 5 shows each semiconductor switch for realizing various connection patterns in FIG. It is a figure which shows an ON or OFF state. For example, the switch SU2 is turned on and the switches SU1 and SU3 are turned off in order to set the connection pattern in the U phase in series with the U1-U2 winding and the U3-U4 winding. On the other hand, in order to achieve parallel connection, the switches SU1 and SU3 are turned on and the switch SU2 is turned off. The same applies to the connection pattern in the V phase and the connection pattern in the W phase.

  Further, regarding the interphase connection of the U-phase winding, the V-phase winding, and the W-phase winding, when the star (Y) connection is used, the switch SU4 is turned on and the switch SU5 is turned off in the U phase. Is done. The same applies to the V phase and the W phase. On the other hand, in the case of delta (Δ) connection, in the U phase, the switch SU5 is turned on and the switch SU4 is turned off. The same applies to the V phase and the W phase. Thus, as shown in FIG. 5, by controlling the on / off state of each semiconductor switch, a star (Y) connection / series type, a delta (Δ) connection / series type, a star (Y) connection / parallel type , And delta (Δ) connection / parallel type four stator winding structures are realized.

  Returning to FIG. 3, the switching control device 30 is configured to switch the semiconductor switches SU1,..., SU5, SV1,..., SV5, SW1,. For each, the on / off control signal shown in FIG. 5 is supplied.

  The drive control device 40 includes a central processing unit (CPU) 42 and an inverter 44. The CPU 42 determines the connection pattern of the stator winding 10 based on the command from the host device, the operation status, etc., and sends the command to the switching control device 30. Further, the CPU 42 controls the inverter 44 so that predetermined three-phase AC power is supplied to the stator winding 10. Under the control, the inverter 44 converts DC power from an external DC power source into three-phase AC power, and supplies the three-phase AC power to the stator winding 10 via the terminals U1, V1, and W1.

  FIG. 6 is a circuit diagram showing a configuration example of each of the semiconductor switches SU1,..., SW5. As shown in FIG. 6, the semiconductor switch includes power MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) Q2 and Q3 and a gate drive circuit using a pulse transformer T1. The primary winding of the pulse transformer T1 is connected to a circuit including on / off control signal input terminals 22 and 24, a DC cut capacitor C1, and a resistor R1.

  The secondary winding of the pulse transformer T1 includes Zener diodes D1 and D2 for threshold voltage, power MOSFETs Q1A and Q1B for preventing reverse current, and power MOSFETs Q2 and Q3 as bidirectional AC switching devices. , And a circuit including output-side terminals 26 and 28 of the semiconductor switch. In addition, the symbol of the diode described in Q1A, Q1B, Q2, and Q3 so as to be connected in parallel to the symbol of the enhancement type N-channel MOSFET represents a diode inherently included in the power MOSFET.

  FIG. 7 is a waveform diagram showing the on / off control signal Vin supplied to the semiconductor switch and the voltage Vout induced in the secondary winding of the pulse transformer T1. When the semiconductor switch is turned on, a positive pulse of several hundred nanoseconds to several microseconds is supplied between the terminals 22 and 24. Since T1 is a positive phase transformer, a positive pulse voltage is also induced in the secondary winding of T1. Due to this induced voltage, current flows from one end of the secondary winding of T1 (the upper end in FIG. 6) to each gate of Q2 and Q3 via D1 and the internal diode of Q1B. Further, current flows from the sources of Q2 and Q3 to the other end of the secondary winding of T1 (the lower end in FIG. 6) via the drain-source channel of D1A and D2.

  Thus, since charge is stored in the gate-to-source capacitance of each of Q2 and Q3, Q2 and Q3 are turned on. As a result, current flows from the terminal 26 to the terminal 28 via the drain-source channel of Q2 and the internal diode of Q3, and also from the terminal 28 to the drain-source channel of Q3 and the internal diode of Q2. It is also allowed for current to flow to terminal 26 via. That is, the on state of the bidirectional switch is realized. Then, in consideration of a decrease in the accumulated charge, a positive pulse is repeatedly supplied between the terminals 22 and 24 with a period of several seconds to several minutes in order to maintain (refresh) the on state of Q2 and Q3.

  On the other hand, when the semiconductor switch is turned off, a negative pulse of several hundred nanoseconds to several microseconds is supplied between the terminals 22 and 24. Since T1 is a positive phase transformer, a negative pulse voltage is also induced in the secondary winding of T1. With this induced voltage, a current flows from the gates of Q2 and Q3 to one end (the upper end in FIG. 6) of the secondary winding of T1 via the drain-source channel of D1B and D1. . Also, current flows from the other end of the secondary winding of T1 (the lower end in FIG. 6) to each source of Q2 and Q3 via D2 and the internal diode of Q1A.

  Thus, since the gate-to-source capacitance of each of Q2 and Q3 is released, Q2 and Q3 are turned off. As a result, the flow of current from the terminal 26 to the terminal 28 and the flow of current from the terminal 28 to the terminal 26 are prohibited. That is, the bidirectional switch is turned off. In order to maintain (refresh) the off-states of Q2 and Q3, negative pulses are repeatedly supplied between the terminals 22 and 24 with a period of several seconds to several minutes.

As shown in FIG. 7, when the positive pulse of the on / off control signal Vin falls, a negative voltage −V ₁ appears in the secondary side voltage Vout of the pulse transformer T1. In addition, the positive voltage + V ₁ appears in the secondary side voltage Vout of the pulse transformer T1 even when the negative pulse of the on / off control signal Vin falls. In order to prevent unintended turn-off or turn-on of Q2 and Q3 due to these voltages, threshold voltage Zener diodes D1 and D2 are inserted.

  Since the semiconductor switch shown in FIG. 6 does not have a mechanical contact, the winding switching circuit 20 realizes a winding switching device that is greatly reduced in size. In the present embodiment, an electronic board on which the winding switching circuit 20 is mounted is built in the motor. From the motor, only three lead lines U1, V1, and W1 (FIG. 3) corresponding to the three-phase synchronous motor are extended to the outside.

  Further, by adopting the semiconductor switch shown in FIG. 6, the connection pattern of the stator winding 10 can be switched during motor operation. The CPU 42 is configured to receive a command for switching the connection pattern of the stator winding 10 and the timing and sequence of the switching from the host device. When the CPU 42 determines the switching of the connection pattern of the stator winding 10, the CPU 42 notifies the switching control device 30 to that effect.

  In response to this, the switching control device 30 sequentially turns on or off the semiconductor switches corresponding to the phases in which the current is not flowing or minimized under the 120-degree energization method in the inverter 44. By doing so, switching to the target stator winding connection pattern is realized.

  That is, the switching control device 30 first switches the U-phase semiconductor switches SU1,..., SU5, then switches the V-phase semiconductor switches SV1,. Further, the wiring patterns are sequentially switched such that the W-phase semiconductor switches SW1,..., SW5 are switched with a 120 ° delay in electrical angle. By such a switching procedure and current control, fluctuations in speed and torque during connection pattern switching are suppressed to a minimum.

  FIG. 8 is a diagram illustrating the generated voltage characteristics of the motor according to this embodiment, and FIG. 9 is a diagram illustrating the rotational speed characteristics of the motor. In FIG. 8, the horizontal axis indicates the stator winding connection pattern, that is, delta (Δ) connection / parallel type, star (Y) connection / parallel type, delta (Δ) connection / series type, and star (Y) connection / The series type is shown, and the vertical axis shows the back electromotive force constant. In FIG. 9, the horizontal axis indicates the supply voltage and the vertical axis indicates the motor speed, with the stator winding connection pattern as a parameter.

  In general, the motor torque is proportional to the supply current from the inverter, and the motor speed is proportional to the supply voltage from the inverter. In this embodiment, it is possible to select from four types of motor characteristic patterns. The voltage specification and current specification are reduced. As a result, the drive controller 40 can be significantly reduced in size. In the low-speed and high-torque region, by selecting the star (Y) connection / series type, the voltage applied per winding is reduced, so that the current ripple is reduced and consequently the torque ripple is also reduced.

  According to the present embodiment, as described above, since the winding switching device (electronic substrate) can be incorporated into the motor by downsizing, the motor according to the present embodiment is a conventional fixed winding motor of the same type. The increase in volume is small compared to. Further, the three lead-out lines U1, V1, and W1 (FIG. 3) correspond to the output lines of the conventional three-phase synchronous motor, so that they can be driven by a conventional driving device. Further, instead of the semiconductor switch (electronic switch), a conventional fixed winding motor can be configured by configuring a circuit with jumper wires. Furthermore, the wiring connecting the motor and the drive control device can be made thin, and the wiring can be easily performed.

  As mentioned above, although embodiment of this invention has been described, of course, this invention is not limited to this. For example, in the present embodiment, three-phase alternating current is used for generating a rotating magnetic field, but multiphase alternating current other than three-phase alternating current may be used.

  Further, in the semiconductor switch shown in FIG. 6, the bidirectional AC switching devices Q2 and Q3 are configured by enhancement type MOSFETs, but may be configured by depletion type MOSFETs. With such a configuration, even when the switching control device 30 is not functioning, the drain-source channels of Q2 and Q3 are normally on, and the motor windings are short-circuited, that is, the regenerative brake is applied. . That is, when the motor drive system is stopped, the motor can be made difficult to rotate. On the other hand, when the enhancement type MOSFET is used, the drain-source channels of Q2 and Q3 are normally turned off, and the motor can be freely rotated when the motor drive system is stopped. When the motor drive system is stopped, when each switch is normally turned on or normally turned off, it is possible to combine a switch constituted by a depletion type MOSFET and a switch constituted by an enhancement type MOSFET. is there.

  The present invention can be used for a wheel / crawler driving actuator of a mobile robot, a robot manipulator, a joint driving actuator of a walking robot, and the like.

DESCRIPTION OF SYMBOLS 10 Stator winding 20 Winding switching circuit 22, 24 Input terminal 26/28 of on / off control signal Output terminal of semiconductor switch 30 Switching control device 40 Drive control device 42 Central processing unit (CPU)
44 Inverter

Claims (5)

A motor drive system including a motor operable by switching a connection pattern of a plurality of windings constituting a stator winding,
By using a plurality of semiconductor switches each having a power MOSFET and a gate drive circuit using a pulse transformer, the in-phase connection pattern of the plurality of windings is switched to serial connection or parallel connection, and the inter-phase connection pattern is changed to star connection or A winding switching circuit for switching to delta connection;
A switching control device for supplying an on / off control signal to the plurality of semiconductor switches according to a stator winding connection pattern employed;
A drive control device that determines the stator winding connection pattern and controls the switching control device, and includes an inverter and controls the inverter so that multiphase AC power is supplied to the stator winding;
A motor drive system comprising:   The motor drive system according to claim 1, wherein an electronic board on which the winding switching circuit is mounted is built in the motor.   The motor drive system according to claim 2, wherein only three lead wires corresponding to a three-phase synchronous motor are led out from the motor.   2. The motor drive system according to claim 1, wherein the drive control device is configured to receive a command regarding switching of the stator winding connection pattern and timing and sequence of the switching.   The switching controller sequentially turns on or off a semiconductor switch corresponding to a phase in which no current flows or is minimized, thereby switching to a target stator winding connection pattern. The motor drive system according to claim 1, which is realized.

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