JP2007325355A - Motor drive system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor drive system with enhanced practicality in energy efficiency improvement. <P>SOLUTION: An inverter unit 20 includes a semiconductor switch 19-1 connected between the input end and one end of an armature coil 17; a semiconductor switch 19-2 connected between the other end of the armature coil 17 and the output end; a semiconductor switch 19-3 connected between the input end and the other end of the armature coil 17; and a semiconductor switch 19-4 connected between the one end of the armature coil 17 and the output end. A set of the semiconductor switches 19-1 and 19-2 and a set of the semiconductor switches 19-3 and 19-4 are controlled by an inverter controller so that at least either set is turned on. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a motor drive system that drives an electric vehicle or the like using a motor.

  The DC motor is driven by inverter control. Specifically, the position of the rotor in the DC motor is detected, and the inverter controls energization to the DC motor based on the position information.

  In a DC motor, generally, the magnet material of the rotor is constituted by a cylindrical permanent magnet. On the other hand, the number of coils on the stator side facing one polarity (N pole or S pole) of the cylindrical permanent magnet is one (one phase). And one coil on the stator side is in a form facing one polarity on the rotor side.

When using such a DC motor, charging may be performed during braking to improve energy efficiency. For example, Patent Document 1 is a motor drive system including a charging circuit that charges regenerative energy during high-speed running based on a constant voltage system, a regenerative operation detection / comparison circuit that detects high-speed running, and the like. In this motor drive system, regenerative energy is stored in the electric double layer capacitor only when a predetermined condition is satisfied, or the electric double layer capacitor is discharged. Patent Document 2 is a motor drive system that collects regenerative energy during high-speed running in a capacitor.
JP-A-6-276616 JP-A-7-143611

  However, in Patent Documents 1 and 2, regenerative energy cannot be recovered when the rotation of the motor is low, in other words, when the electromotive force (load electromotive force) of the motor is small. For this reason, the practical use of the motor drive system which improved energy efficiency is desired.

  Then, an object of this invention is to provide the motor drive system which raised the practicality of energy efficiency improvement.

  The present invention includes a power supply apparatus, an inverter unit configured in series for the number of phases, an inverter configured to control a direction of a direct current from the power supply apparatus to generate a rectangular wave alternating current, and a switching in the inverter A motor drive system having switching control means for controlling drive of an element and a motor for driving and braking according to a rectangular wave alternating current from the inverter flowing through an armature coil, wherein the power supply device is a DC voltage And a voltage control means for inputting a DC voltage from the DC power supply and controlling the polarity and magnitude of the output voltage in accordance with the electromotive force of the motor so that the output current becomes a DC constant current. And the inverter unit has a self-turn-off capability connected between an input end and one end of an armature coil for one phase in the motor. A switching element, a second switching element having a self-turn-off capability connected between the other end of the armature coil for one phase in the motor and the output end, the input end and 1 in the motor A third switching element having a self-turn-off capability connected between the other end of the armature coil for the phase and a first switching element connected to the output end of the armature coil for the one phase in the motor. A fourth switching element having a self-turn-off capability, wherein the switching control means includes at least one of the first and second switching elements and the third and fourth switching elements during a driving period. The driving of the first to fourth switching elements is controlled so that one of them is turned on.

  According to this configuration, the power supply device controls the polarity and magnitude of the output voltage according to the electromotive force of the motor, thereby supplying a constant DC current having a certain direction and a certain magnitude to the inverter. It is possible to discharge energy when the motor is driven and charge with regenerative power during braking until the motor is stopped, in other words, until the electromotive force of the motor becomes almost zero, thereby improving energy efficiency. Become. Further, since the motor is a direct current motor driven by a direct current, it is possible to realize high torque efficiency with downsizing. Furthermore, in the inverter unit, the first to fourth switching elements are connected in a single-phase bridge shape, and at least one of the two facing switching elements and the other two facing switching elements is turned on. Since the current path from the input end to the output end is always formed, it is possible to prevent an overvoltage from being applied to the switching element and further improve the practicality of the motor drive system.

  In the motor drive system of the present invention, the inverter unit is connected in series to each of the first to fourth switching elements, and the upstream side of the direct current from the power supply device is the anode, and the downstream side is the downstream side. You may make it have the diode used as a cathode.

  According to this configuration, when a back electromotive force is generated during regenerative braking of the motor, it is possible to give the constant current multiphase inverter a reverse withstand voltage that can correspond to the back electromotive force by the diode.

  In the motor drive system of the present invention, the inverter unit may include a capacitor connected in parallel to the armature coil.

  According to this configuration, when an inductance is present in the armature coil, the change in the current direction in the armature coil due to the driving of the switching element can be moderated to prevent an overvoltage from being applied to the switching element. it can.

  In the motor drive system of the present invention, the resonance frequency of the armature coil and the capacitor may be 10 to 20 times the frequency of the rectangular wave alternating current.

  According to this configuration, the change in the current direction in the armature coil due to the driving of the switching element can be moderated, and the change can be completed in an appropriate time.

  In the motor drive system of the present invention, the inverter unit may have a resistor or a coil connected in series to the capacitor.

  According to this configuration, it is possible to prevent the overvoltage from being applied to the switching element by slowing the rising of the current flowing from the capacitor that flows by driving the switching element.

  According to the present invention, charging can be performed during braking of the motor until the motor is stopped, and further, overvoltage can be prevented from being applied to the switching element in the inverter unit, and counter-electromotive force can be supported. It is possible to give the constant current multiphase inverter the reverse breakdown voltage to be obtained, and the energy efficiency can be improved more practically.

  FIG. 1 shows a configuration of an electric vehicle to which a constant current motor driving system according to the present invention is applied. In FIG. 1, the electric vehicle includes a DC constant current power supply device 1, a multiphase constant current inverter 2, a multiphase constant current motor 3, a differential gear 4, and a mechanical brake 5. The constant current type motor drive system according to the present invention is mainly composed of the DC constant current power supply device 1, the multiphase constant current inverter 2, and the multiphase constant current motor 3. In FIG. 1, only one multiphase constant current motor 1 is installed, but a configuration may be adopted in which the differential gear 4 is omitted for each tire. In the motor drive system according to the present invention, the mechanical brake 5 is not necessary in normal operation as will be described later, but has a role as a tire lock after a stop and an emergency brake.

  FIG. 2 is a block diagram of a basic configuration of a constant current type constant current multiphase inverter according to the present invention. The constant current multiphase inverter shown in FIG. 2 includes a DC constant current power supply device 1, a constant current multiphase inverter 2, and a constant current multiphase motor 3. Hereinafter, the configuration of a constant current type constant current multiphase inverter according to the present invention will be described in detail.

  3 and 4 show the configuration of the constant current multiphase motor 3 in FIG. 3 is an axial sectional view, and FIG. 4 is an axial vertical sectional view. 3 and 4, the rotor core 6 is made of pure iron having a small magnetic resistance, is supported by a bearing 8, and can be freely rotated by a rotating shaft 7. The magnet material 9 is a strong magnet material of a rare earth magnet. An NS pair having an N pole on the inner peripheral side and an S pole on the outer peripheral side, and an S pole on the outer peripheral portion of the rotor core 6 are used. 4 pairs of NS pairs each having the N-pole on the outer side and the N-pole are arranged on the outer side.

  The stator core 13 has a ring shape, and is disposed so that its inner peripheral surface faces the rotor core 6 with a slight gap 14 therebetween, and is fixed to a case 16 described later. This stator core 13 is formed by laminating silicon steel plates. Further, a groove 10 for inserting an armature coil 17 described later is formed on the inner peripheral surface of the stator core 13. The grooves 10 are formed by the number of phases per magnetic pole. In this embodiment, since it has a four-phase configuration, there are four grooves per magnetic pole. Therefore, there are 8 (poles) × 4 (grooves) = 32 grooves as a whole.

  FIG. 5 shows the configuration of the armature coil 17. The upper part of FIG. 5 shows the rotor core 6 stopped at a specific position and the magnetic pole array stopped at the specific position and developed in a straight line. As described above, there are four grooves 10 indicated by dotted lines, and symbols a, b, c, and d are given in the order of the rotation direction of the magnetic poles. The armature coil 17 is an A phase, B phase coil, C phase coil, and D phase coil corresponding to each of the four phases. The A phase coil is wound between one magnetic pole side groove a and the adjacent magnetic pole side groove a, and one of the A phase coils corresponds to a pair of magnetic poles. In this embodiment, since there are four pairs (eight poles), four A-phase coils are wound in the same direction in one circumference, all of which are connected in series or in parallel and taken out as a pair of input / output terminals to the outside. The B phase, C phase, and D phase coils are the same as the A phase coil.

  Again, it returns and demonstrates to FIG.3 and FIG.4. The light shielding plate 11 and the photosensor 12 are for detecting the angular position of the rotor composed of the rotor core 6 and the magnet material 9. The outer edge part of the light shielding plate 11 is cut in accordance with the polarity of the magnet material 9 constituting the rotor. The photosensor 12 is configured such that light passes through the cut portion of the light shielding plate 11 and can detect an ON signal, which becomes an angular position signal described later. It should be noted that the above-described angular position can also be detected by a magnetic mechanism using a magnetic pole plate magnetized according to the polarity of the magnet material 9 instead of the photosensor 12 or a combination with the magnetic pole of the rotor itself. It is well known.

  FIG. 6A is a diagram showing the configuration of the four-phase configuration of the constant current multiphase inverter 2 in FIG. In FIG. 6A, a DC constant current from a DC constant current power supply device 1 to be described later flows in through terminal 18-1 (X) and flows out from terminal 18-2 (Y). The semiconductor switch 19 is a switching element having a self turn-off capability. The armature coil 17 corresponds to the armature coil 17 of the constant current multiphase motor 3 in FIG. 3 and is configured by four phases A, B, C, and D.

  The inverter units 20 to 23 as inverter units correspond to the A phase to the D phase. The A-phase inverter unit 20 includes four semiconductor switches 19 (Ta, Ta, Ta ′, Ta ′), to which one-phase armature coil 17 is connected. The semiconductor switch 19-1 (Ta) is connected between the input end and one end of the A-phase armature coil 17, and the semiconductor switch 19-2 (Ta) is connected to the other end of the A-phase armature coil 17 and the output end. Connected between. On the other hand, the semiconductor switch 19-3 (Ta ′) is connected between the input end and the other end of the A-phase armature coil 17, and the semiconductor switch 19-4 (Ta ′) is connected to the A-phase armature coil 17. Connected between one end and the output end.

  The B-phase inverter unit 21, the C-phase inverter unit 22, and the D-phase inverter unit 23 have the same configuration. The constant current multiphase inverter 2 is configured by connecting inverter units in series for the number of phases. Since the present embodiment has a four-phase configuration, the constant current multiphase inverter 2 is configured by connecting four inverter units 20 to 23 in series.

  The operation of the inverter units 20 to 23 will be described using the A-phase inverter unit 20 as an example. The four semiconductor switches 19 (Ta, Ta, Ta ′, Ta ′) constituting the A-phase single-phase bridge are turned on by two semiconductor switches 19-1 and 19-2 (Ta) and two semiconductor switches 19-. 3 and 19-4 (Ta ′) are alternately turned on. In the A-phase armature coil 17 of the armature coil 17, when the semiconductor switches 19-1 and 19-2 (Ta) are on, a current flows in the direction of a → a ′ in FIG. When the two semiconductor switches 19-3 and 19-4 (Ta ′) are on, a current flows in the reverse direction from a ′ to a. For this reason, the direct current constant current flowing from the terminal X becomes a rectangular wave alternating current having the same amplitude and flows through the A-phase armature coil 17.

  In this case, the current at the junction (X ′ in FIG. 6A) on the outlet side of the inverter unit 20 is the same DC constant current as the current flowing in from the terminal X, and this DC constant current is the subsequent inverter unit. The input current is 21. In the inverter unit 21, the same operation as that of the inverter unit 20 is performed, and in the subsequent inverter units 22 and 23, the same operation as that of the inverter unit 20 is performed.

  The inverter control device 24 in FIG. 6B is for controlling the above-described four-phase inverter units 20 to 23. In FIG. 6B, the angular position signal 25 (Sa, Sb, Sc, Sd) is sent from the photosensor 12 corresponding to the angular position of the rotor core 6 of the multiphase constant electric motor 3 described above. The inverter control device 24 outputs a drive signal 26 for driving each semiconductor switch 19 in the inverter units 20 to 23 according to the angular position signal 25. The braking command signal 27 (So) is generated when the constant current multiphase motor 3 is braked. When the braking command signal 27 is at a high level (when there is a braking command), the inverter control device 24 The phase of 26 is reversed by an electrical angle of 180 °.

  FIG. 7 is a diagram illustrating a correspondence relationship between the angular position signal 25, the drive signal 26, and the braking command signal 27. The angular position detection signals Sa to Sd are alternately repeated between the high level (H) and the low level (0) every time the rotor rotates by an angle corresponding to an electrical angle of 180 ° (geometric angle 45 °). . In addition, the switching timing between the high level and the low level in the angular position detection signals Sa to Sd is shifted every time the rotor rotates by an angle corresponding to an electrical angle of 45 ° (geometric angle 12.25 °).

  When there is no braking command signal (low level), the drive signal 26 for driving the two semiconductor switches 19-1 and 19-2 (Ta) in the inverter unit 20 has a high level of the angular position detection signal Sa. Sometimes it is also at a high level, and when the angular position detection signal Sa is at a low level, it is also at a low level. Further, the drive signal 26 for driving the two semiconductor switches 19-3 and 19-4 (Ta ′) in the inverter unit 20 becomes the low level when the angular position detection signal Sa is at the high level. Conversely, when the detection signal Sa is at a low level, the detection signal Sa is at a high level. The same applies to drive signals for driving the semiconductor switches 19 (Tb, Tb′Tc, Tc ′, Td, Td ′) in the other inverter units 21 to 23.

  On the other hand, when there is a braking command signal (high level), the drive signal 26 for driving the two semiconductor switches 19-1 and 19-2 (Ta) in the inverter unit 20 is high in the angular position detection signal Sa. On the other hand, when the level is low, the level is low, and when the angular position detection signal Sa is low level, the level is high. Further, the drive signal 26 for driving the two semiconductor switches 19-3 and 19-4 (Ta ′) in the inverter unit 20 is similarly at a high level when the angular position detection signal Sa is at a high level. Similarly, when the detection signal Sa is at a low level, the detection signal Sa is at a low level. The same applies to drive signals for driving the semiconductor switches 19 (Tb, Tb′Tc, Tc ′, Td, Td ′) in the other inverter units 21 to 23.

  More specifically, the inverter control device 24 drives the two semiconductor switches 19-1 and 19-2 (Ta) and the two semiconductor switches 19-3 and 19-4 (Ta ′) in the inverter unit 20. Control is performed so that at least one of the semiconductor switches 19-1 and 19-2 (Ta) and the semiconductor switches 19-3 and 19-4 (Ta ′) is turned on during the period.

  FIG. 8 is a diagram showing a detailed configuration of the inverter control device 24. The inverter control device 24 includes delay circuits 51 and 52 and inverting circuits 53 and 54. The delay circuit 51 receives the angular position detection signal Sa and the braking command signal So, performs delay processing based on these signals, and outputs a predetermined signal to the inversion circuit 53. Similarly, the delay circuit 52 receives the angular position detection signal Sa and the braking command signal So, performs delay processing based on these signals, and outputs a predetermined signal to the inverting circuit 54.

  The inversion circuit 53 receives the signal from the delay circuit 51 and the braking command signal So, performs the inversion processing of the signal from the delay circuit 51 based on the braking command signal So, and performs the semiconductor switches 19-1 and 19-2 ( A drive signal Ta for driving Ta) is output. Similarly, the inversion circuit 54 receives the signal from the delay circuit 52 and the braking command signal So, performs the inversion processing of the signal from the delay circuit 52 based on the braking command signal So, and performs the semiconductor switches 19-3 and 19. -4 (Ta ′) to drive the drive signal Ta ′.

  Hereinafter, the operation of the inverter control device 24 will be described. First, a case where the braking command signal So is at a low level (no braking command) will be described. When there is no braking command, the delay circuit 51 outputs a signal that rises simultaneously with the input angular position detection signal Sa when the input angular position detection signal Sa rises (switches from low level to high level). Further, the delay circuit 51 outputs a signal delayed by a predetermined time from the input angular position detection signal Sa when the input angular position detection signal Sa falls (switches from high level to low level). . When there is no braking command, the inverting circuit 53 outputs the signal from the delay circuit 51 as it is as the drive signal Ta for driving the semiconductor switches 19-1 and 19-2 (Ta).

  On the other hand, when there is no braking command, the delay circuit 52 outputs a signal whose rising is delayed by a predetermined time from the input angular position detection signal Sa at the rising of the input angular position detection signal Sa. The delay circuit 52 outputs a signal that falls simultaneously with the input angular position detection signal Sa when the input angular position detection signal Sa falls. When there is no braking command, the inverting circuit 53 inverts the signal from the delay circuit 51 and outputs it as a drive signal Ta ′ for driving the semiconductor switches 19-3 and 19-4 (Ta ′).

  With this operation, when there is no braking command, the semiconductor switches 19-1 and 19-2 (Ta) shown in FIG. 9B are turned on in response to the braking command signal So shown in FIG. A drive signal Ta for driving and a drive signal Ta ′ for driving the semiconductor switches 19-3 and 19-4 (Ta ′) shown in FIG. 9C are generated. These drive signals Ta and Ta ′ exist when only the drive signal Ta is at a high level and when both the drive signals Ta and Ta ′ are at a high level, and both the drive signals Ta and Ta ′ are at a low level. The case does not exist. That is, at least one of the semiconductor switches 19-1 and 19-2 (Ta) and the semiconductor switches 19-3 and 19-4 (Ta ′) is on, and there is no period during which both are off.

  Next, a case where the braking command signal So is at a high level (with a braking command) will be described. When there is a braking command, the delay circuit 51 outputs a signal whose rising is delayed by a predetermined time from the input angular position detection signal Sa at the rising of the input angular position detection signal Sa. The delay circuit 51 outputs a signal that rises simultaneously with the input angular position detection signal Sa at the rising edge of the input angular position detection signal Sa. When there is a braking command, the inverting circuit 53 inverts the signal from the delay circuit 51 and outputs it as a drive signal Ta for driving the semiconductor switches 19-1 and 19-2 (Ta).

  On the other hand, when there is a braking command, the delay circuit 52 outputs a signal that rises simultaneously with the input angular position detection signal Sa when the input angular position detection signal Sa rises. In addition, the delay circuit 52 outputs a signal delayed by a predetermined time from the input angular position detection signal Sa at the falling edge of the input angular position detection signal Sa. When there is a braking command, the inverting circuit 53 outputs the signal from the delay circuit 51 as it is as the drive signal Ta ′ for driving the semiconductor switches 19-3 and 19-4 (Ta ′).

  With this operation, when there is a braking command, the semiconductor switches 19-1 and 19-2 (Ta) shown in FIG. 9C are turned on in response to the braking command signal So shown in FIG. A drive signal Ta for driving and a drive signal Ta ′ for driving the semiconductor switches 19-3 and 19-4 (Ta ′) shown in FIG. 9D are generated. These drive signals Ta and Ta ′ exist when only the drive signal Ta ′ is at a high level and when both the drive signals Ta and Ta ′ are at a high level, and both the drive signals Ta and Ta ′ are at a low level. In the case of That is, at least one of the semiconductor switches 19-1 and 19-2 (Ta) and the semiconductor switches 19-3 and 19-4 (Ta ′) is on, and there is no period during which both are off.

  FIG. 10 shows a case where the inverter control device 24 performs control so that at least one of the semiconductor switches 19-1 and 19-2 (Ta) and the semiconductor switches 19-3 and 19-4 (Ta ′) is turned on. FIG. 6 is a diagram showing a switching operation of these semiconductor switches 19 in FIG. In FIG. 10, a case where there is a braking command and a case where the angular position detection signal Sa falls is described.

  First, the inverter control device 24 sets the drive signal Ta to the high level and the drive signal Ta ′ to the low level. As a result, as shown in FIG. 10A, the semiconductor switches 19-1 and 19-2 (Ta) are turned on, and the semiconductor switches 19-3 and 19-4 (Ta ′) are turned off. 1 flows through the semiconductor switch 19-1 (Ta), the A-phase armature coil 17 (a → a ′ direction), and the semiconductor switch 19-2 (Ta).

  Next, when the angular position detection signal Sa falls, the inverter control device 24 sets both the drive signal Ta and the drive signal Ta ′ to the high level. As a result, as shown in FIG. 10B, both the semiconductor switches 19-1 and 19-2 (Ta) and the semiconductor switches 19-3 and 19-4 (Ta ′) are turned on, and the DC constant current power supply is turned on. Half of the current I from the device 1 flows through the semiconductor switch 19-1 (Ta) and the semiconductor switch 19-4 (Ta ′), and the other half is the semiconductor switch 19-3 (Ta ′) and the semiconductor switch 19-. 2 (Ta).

  Further, after a predetermined time has elapsed, the inverter control device 24 sets the drive signal Ta to the low level and the drive signal Ta ′ to the high level. As a result, as shown in FIG. 10C, the semiconductor switches 19-1 and 19-2 (Ta) are turned off, and the semiconductor switches 19-3 and 19-4 (Ta ′) are turned on. 1 flows through the semiconductor switch 19-3 (Ta ′), the A-phase armature coil 17 (a ′ → a direction), and the semiconductor switch 19-4 (Ta ′).

  For example, when the semiconductor switches 19-1 and 19-2 (Ta) are turned on and the semiconductor switches 19-3 and 19-4 (Ta ′) are turned off, the semiconductor switches 19-1 and 19-2 (Ta) are turned off. When the semiconductor switches 19-3 and 19-4 (Ta ′) are turned on, as shown in FIG. 11, the semiconductor switches 19-1 and 19-2 (Ta) and the semiconductor switches 19-3 and 19-3 If both 19-4 (Ta ′) are in an off state, an overvoltage is applied to the semiconductor switches 19-1 and 19-2 (Ta), which may cause damage.

  However, as shown in FIG. 10, the semiconductor switches 19-1 and 19-2 (Ta) are turned on, and the semiconductor switches 19-3 and 19-4 (Ta ′) are turned off. 2 (Ta) and the semiconductor switches 19-3 and 19-4 (Ta ′) are both turned on, and after a predetermined time has elapsed, the semiconductor switches 19-1 and 19-2 (Ta) are turned off. By causing the switches 19-3 and 19-4 (Ta ′) to transition to the ON state, it is possible to prevent an overvoltage from being applied to the semiconductor switches 19-1 and 19-2 (Ta), and practicality. Will improve. However, the drive efficiency and braking efficiency of the constant current multiphase motor 3 are in a period in which both the semiconductor switches 19-1 and 19-2 (Ta) and the semiconductor switches 19-3 and 19-4 (Ta ′) are on. It is desirable to keep the time as short as possible in order to maintain the above.

  FIG. 12 is a diagram illustrating a configuration of the inverter unit 20 to which a diode is added. The A-phase inverter unit 20 shown in FIG. 12 has a configuration in which four diodes 60 are added to the A-phase inverter unit 20 shown in FIG. The B-phase inverter unit 21, the C-phase inverter unit 22, and the D-phase inverter unit 23 may have the same configuration.

  The diode 60-1 is connected in series to the semiconductor switch 19-1 so that the input terminal X side is an anode and the semiconductor switch 19-1 side is a cathode. The diode 60-2 is connected in series to the semiconductor switch 19-2 so that the semiconductor switch 19-2 side is an anode and the output terminal X ′ side is a cathode. The diode 60-3 is connected in series to the semiconductor switch 19-3 so that the input terminal X side is the anode and the semiconductor switch 19-3 side is the cathode, and the diode 60-4 is the semiconductor switch 19-4. Are connected in series to the semiconductor switch 19-4 so that the side of the output terminal X ′ is the anode and the side of the output terminal X ′ is the cathode.

  On the other hand, FIG. 13 is a diagram showing a configuration of a conventional inverter unit. In the inverter unit 70 shown in FIG. 13, the diode 60-1 is connected in parallel to the semiconductor switch 19-1 so that the input terminal X side becomes a cathode. The diode 60-2 is connected in parallel to the semiconductor switch 19-2 so that the output terminal X ′ side becomes an anode. The diode 60-3 is connected in parallel to the semiconductor switch 19-3 so that the input terminal X side is a cathode, and the diode 60-4 is a semiconductor switch so that the output terminal X ′ side is an anode. 19-4 connected in parallel.

  In the inverter unit 70 shown in FIG. 13, when a back electromotive force is generated during regenerative braking of the constant current multiphase motor 3, the semiconductor switch 19-1, the diode 60-1, the armature coil 17, and the semiconductor switch 19-3 are used. And a short circuit is formed by the diode 60-3 and a short circuit current flows. Similarly, the semiconductor switch 19-2 and the diode 60-2, the armature coil 17, the semiconductor switch 19-4 and the diode 60-4 are short-circuited. A circuit is formed and a short circuit current flows. For this reason, it is not possible to use a well-known IGBT, power transistor, turn-off thyristor or the like in which the semiconductor switch 19 and the diode 60 are connected in parallel and integrated.

  On the other hand, in the inverter unit 20 shown in FIG. 12, the semiconductor switch 19 and the diode 60 are connected in series, so that when back electromotive force is generated during regenerative braking of the constant current multiphase motor 3, the diode 60-1 to 60-4 allows the inverter unit 20 to have a reverse breakdown voltage that can correspond to the counter electromotive force.

  FIG. 14 is a diagram illustrating a commutation phenomenon of the inverter unit 20 when an inductance is present in the armature coil 17. First, when the semiconductor switches 19-1 and 19-2 are on and the semiconductor switches 19-3 and 19-4 are off, a current path indicated by a solid line in FIG. Next, the semiconductor switches 19-1 and 19-2 are turned off while at least one of the semiconductor switches 19-1 and 19-2 and the semiconductor switches 19-3 and 19-4 is kept on. By performing the switching operation so that the switches 19-3 and 19-4 are turned on, a current path indicated by a dotted line in FIG. 14 is obtained.

  However, when there is an inductance in the armature coil 17, if the direction of the current flowing through the armature coil 17 is instantaneously switched, an overvoltage due to a current change occurs in the armature coil 17. The overvoltage is expressed as L (diL / dt) obtained by differentiating iL by t and multiplying L by assuming that the inductance of the armature coil 17 is L, the current flowing through the armature coil 17 is iL, and the time is t. . When this overvoltage is applied to the semiconductor switch 19, the semiconductor switch 19 may be damaged. For this reason, it is desirable to take measures to moderate the current change in the armature coil 17.

  FIG. 15 is a diagram illustrating a configuration of the inverter unit 20 to which a capacitor is added. The A-phase inverter unit 20 shown in FIG. 15 has a configuration in which a capacitor 70 is connected in parallel to the armature coil 17 connected to the A-phase inverter unit 20 shown in FIG. The B-phase inverter unit 21, the C-phase inverter unit 22, and the D-phase inverter unit 23 may have the same configuration.

  FIG. 16 is a diagram illustrating a time transition of the current ic of the capacitor 70 and the current iL of the armature coil 17. The additional electromotive force is zero. Initially, the semiconductor switches 19-1 and 19-2 are in the on state, the semiconductor switches 19-3 and 19-4 are in the off state, and the inflow current I is the semiconductor switch 19-1, the armature coil 17, and the semiconductor switch 19-2. It is flowing in the route. Thereafter, at time t = 0, the semiconductor switches 19-1 and 19-2 are turned off, and the semiconductor switches 19-3 and 19-4 are turned on. In this case, the inflow current I flows through the semiconductor switch 19-3 and the semiconductor switch 19-4, but the current ic in the capacitor 70 is generated from the inflow current I and the armature coil 17 as shown in FIG. 2I is superimposed on the current I, and then decreases to 0. On the other hand, the current iL in the armature coil 17 becomes I as shown in FIG. 16B, and then becomes -I at the same time as the current ic in the capacitor 70 becomes zero.

  The time for the current ic in the capacitor 70 to decrease from 2I to 0 and the time for the current iL in the armature coil 17 to decrease from I to -I (fall time) are the inductance of the armature coil 17 being L and the capacitor 70. Is defined as 1/2 of the reciprocal of the resonance frequency fo = 1 / (2π√ (LC)). Therefore, as the capacitance C of the capacitor 70 increases, the resonance frequency fo decreases and the fall time becomes longer. In other words, the current change in the armature coil 17 becomes gradual, and the overvoltage applied to the semiconductor switch 19 is increased. Becomes smaller. However, if the resonance frequency fo is smaller than the frequency (basic frequency) f of the rectangular wave alternating current, the shape of the rectangular wave alternating current cannot be maintained, so the resonance frequency fo is 10 times to 20 times the basic frequency f. It is desirable that the capacitance C of the capacitor 70 is set so as to be about double.

  17A, a resistor 71 is connected in series with the capacitor 70, or a coil 72 is connected in series with the capacitor 70 as shown in FIG. 17B. As in the case where the capacitance C of the capacitor 70 is increased, the resonance frequency fo is decreased to increase the fall time. In other words, the current change in the armature coil 17 is moderated and applied to the semiconductor switch 19. It is possible to reduce the overvoltage.

  In FIG. 16, the semiconductor switches 19-1 and 19-2 are switched from on to off at the time t = 0, and the semiconductor switches 19-3 and 19-4 are switched from off to on at the same time. When the semiconductor switches 19-3 and 19-4 are switched from OFF to ON at time t = 0, and the semiconductor switches 19-1 and 19-2 are switched from ON to OFF after a predetermined time has elapsed. It is possible to reduce the overvoltage applied to the semiconductor switch 19 more reliably.

  18 shows a specific configuration of a conventional constant voltage inverter, and FIG. 19 shows a specific configuration of the constant current multiphase inverter 2 to which the diode 60 and the capacitor 70 described above are added.

  The conventional constant voltage inverter shown in FIG. 18 has a three-phase configuration, and supplies voltage and current to each of the R-phase, S-phase, and T-layer armature coils so that a phase difference of 120 degrees occurs between them. The switching elements 19-1, 19-2 and 19-3 are connected in parallel, and the switching elements 19-4, 19-5 and 19-6 are connected in parallel. Further, diodes 60-1 to 60-6 are connected in antiparallel to the switching elements 19-1 to 19-6, respectively.

  On the other hand, the constant-current multiphase inverter 2 shown in FIG. 19 has a four-phase configuration, in which an A-phase inverter unit 20, a B-phase inverter unit 21, a C-phase inverter unit 22, and a D-phase inverter unit 23 are connected in series. The voltage and current are supplied so that a phase difference of 90 degrees is generated between the armature coils 17 for one phase. The inverter units 20 to 23 include four semiconductor switches 19-1 to 19-4, diodes 60-1 to 60-4 connected in series to the semiconductor switches 19-1 to 19-4, and an armature, respectively. The capacitor 70 is connected in parallel to the coil 17.

  Since the conventional constant voltage inverter and the constant current multiphase inverter 2 have different configurations as described above, there are the following operational differences. That is, with respect to the processing of the magnetic energy of the inductance of the armature coil, the conventional constant voltage inverter recovers to the power supply side through the diode 60 connected in antiparallel to the semiconductor switch 19, whereas the constant current multiphase inverter 2 Is stored in a capacitor 70 connected in parallel to the armature coil 17. In addition, regarding the response to the negative electromotive force generated in the armature coil at the time of regenerative braking of the motor, the conventional constant voltage inverter has no relation to the regeneration, and the power supply is provided by a separately provided AC / DC converter and a boost chopper. In contrast, the constant current multiphase inverter 2 can perform regeneration until the motor stops, and can improve the regeneration efficiency.

  FIG. 20 is a diagram for explaining the rotation angle of the rotor, the current direction of the armature coil 17, and the generation of the rotational force in the absence of a braking command signal. In FIG. 20, the magnet material 9 and the light shielding plate 11 on the rotor surface are integrally rotated clockwise. The photosensor 12 has Pa, Pb, Pc, and Pd for detecting the A phase, the B phase, the C phase, and the D phase, respectively. Signals Sa, Sb, Sc and Sd are generated. 10 correspond to a and a ′ in FIG. 6A, and when the two semiconductor switches 19 (Ta) are on, the current flows in the a → a ′ direction in the armature coil 17. When the two semiconductor switches 19 (Ta ′) are on, a current flows in the a ′ → a direction in the armature coil 17. The same applies to the B, C, and D phases.

  The rotor angular position in FIG. 20 corresponds to the reference angular position in the case of no braking command in FIG. 7, and the current flowing through the armature coil 17 in all the grooves 10 is linked to the maximum density magnetic flux. Produces an effective rotational force. Further, when the rotor is rotated from the position of FIG. 20 by one pitch of the groove 10 (electrical angle 45 °, geometric angle 12.25 °), the magnetic flux interlinking with the A-phase coil of the armature coil 17. At the same time, the photosensor 19 (Pa) is shielded, the angular position signal Sa is turned off, and the two semiconductor switches 19 (Ta ′) of the A-phase inverter unit 20 in FIG. Switch on. Thereby, the current of the A-phase armature coil 17 is reversed, and the current flowing through the armature coils 17 in all the grooves 10 continues to generate effective rotational force. The same applies thereafter, and each time the rotor rotates by an angle corresponding to an electrical angle of 45 ° (geometric angle 12.25 °), the coil current of each phase of the armature coil 17 is sequentially reversed, and Go around with reversal. Then, at any angular position of the rotor, the currents of all the armature coils 17 in the groove 10 effectively contribute to the generation of the rotational force.

  On the other hand, FIG. 21 shows the angular position signal of the rotor and the current direction of the armature coil 17 in a state where there is a braking command signal. Compared with FIG. 20, the current direction is the same for the same magnetic field direction. All are the opposite and produce an effective braking force.

  Transmission and reception of electric energy when the above-described braking control is performed will be described. FIG. 22 is a diagram for explaining the electromotive force between the terminal (X) and the terminal (Y) of the constant current multiphase inverter 2 in FIG. Although the constant current multiphase inverter 2 of FIG. 6A has a four-phase configuration, here, in order to simplify the explanation, the transmission and reception of electric energy in the A-phase inverter unit 20 shown in FIG. To do. Due to the rotation of the rotor in the constant current multiphase motor 3, the magnetic flux from the magnet material 9 crosses the armature coil 17, so that an electromotive force is generated in the armature coil 17. Since the magnetic flux density distribution in the gap 14 of the constant current multiphase motor 3 has a rectangular wave shape, the electromotive force ed generated in the armature coil 17 becomes a rectangular wave AC voltage as shown in FIG.

  FIG. 22 (c) shows that the semiconductor switches S1 and S4 in the A-phase inverter unit 20 of FIG. 22 (a) are turned on at the “positive” timing of the waveform of the electromotive force ed generated in the armature coil 17. This is an electromotive force waveform between the point X and the point X ′ when the semiconductor switches S2 and S3 are turned on at the “negative” timing of the waveform. The voltage between the point X and the point X ′ has a positive value of the average value ed. If the DC constant current I flows from the DC constant current power supply device 1 to the X point, the A-phase armature coil 17 is supplied with edxI power from the power supply side, and the rotor has rotational energy corresponding to this value. Occurs. The power loss due to the resistance of the armature coil 17 and the mechanical loss of the rotor are ignored.

  FIG. 22D shows that the switching operation of the semiconductor switches Ta to Td in the A-phase inverter unit 20 in FIG. 22A with respect to the waveform of the electromotive force ed generated in the armature coil 17 is more electrical than in the case of FIG. It is an electromotive force waveform between point X and point X ′ when the angle is delayed by 180 °. The voltage between the point X and the point X ′ has a negative value with an average value of −ed. Therefore, if the DC constant current I flows from the power source side to the X point, the -phase armature coil 17 is supplied with -edxI power from the power source side. This means that edxI electric power is sent back from the A-phase armature coil 17 to the power source side, and a braking force is applied to the rotor, and the energy recovered by the braking is recovered by the DC constant current power supply device 1.

  The B-phase inverter unit 21, the C-phase inverter unit 22, and the D-phase inverter unit 23 are basically the same, and all of them are superposed and act.

  As described above, the motor drive system according to the present invention allows the rotational force of the rotor in the constant current multiphase motor 3 to be constant by passing a constant current (DC constant current) in a constant direction through the constant current multiphase inverter 2. Control during driving and braking is performed only by the phase control of the current multiphase inverter 2, and the load electromotive force changes in the positive and negative regions, so that power supply and regeneration are automatically performed regardless of the speed. Done.

  FIG. 23A is a diagram illustrating a circuit configuration of the DC constant current power supply device 1. Unlike a power supply device in which the output current is simply controlled to be constant, the DC constant current power supply device 1 outputs a constant current (DC constant current) in a constant direction regardless of whether the electromotive force on the load side is positive or negative. It is characterized in that it has a function of receiving electric power that is controlled and regenerated from the constant current multiphase motor 3 on the load side.

  The DC constant current power supply device 1 is configured around an asymmetrically controlled PWM (pulse width control) bridge (hereinafter referred to as “asymmetrical PWM bridge”). As the semiconductor switch 31 in the asymmetric PWM bridge, an IGBT, a thyristor, a power transistor, or the like can be arbitrarily selected. A DC power supply 29 is connected to a portion corresponding to a so-called AC terminal in the asymmetric PWM bridge, and a terminal X and a terminal Y of the constant current multiphase inverter 2 (FIG. 6A) are connected to a so-called DC terminal of the asymmetric PWM bridge. )) Is connected.

  In the DC constant current power supply device 1 of FIG. 23A, the semiconductor switches 31 (S1, S2, S3, S4) constituting the asymmetric PWM bridge are turned on / off according to a predetermined carrier frequency signal, and the on period is controlled. Is possible. The pair of two semiconductor switches 31 (S1, S4) and the pair of two semiconductor switches 31 (S2, S3) do not operate symmetrically as in a normal bridge, but are positive or negative of the load electromotive force. In correspondence with each other, they are designed to operate integrally and asymmetrically. Specifically, when the pair of semiconductor switches 31 (S1, S4) operates, a positive average voltage is output across the terminals X and Y, and the value is based on the ON period of the semiconductor switches 31 (S1, S4). Is controlled by the length. Further, when the pair of semiconductor switches 31 (S2, S3) is operated, a negative average voltage is output across the terminals X and Y, and this value is the length of the ON period of the semiconductor switch 31 (S2, S3). It is controlled by

  The semiconductor switch 31 (S5) is connected in parallel to the output side of the asymmetric PWM bridge and constitutes a circulation circuit through the reactor 30 and the constant current multiphase inverter 2 in the subsequent stage. The semiconductor switch 31 (S5) is a semiconductor switch. It operates so as to be on during the off period of the pair of 31 (S1, S4) and the off period of the pair of the semiconductor switch 31 (S2, S3). Thereby, the constant current multiphase inverter 2 is intermittently connected to the constant current multiphase inverter 2 even during the off period of the pair of semiconductor switches 31 (S1, S4) and the off period of the pair of semiconductor switches 31 (S2, S3). Supply without.

  FIG. 23B shows a constant current power supply control device 35 configured in the DC constant current control device 1 for controlling the semiconductor switch 31 (S1, S2, S3, S4, S5) described above. is there. This constant current power supply control device 35 receives control information such as output current and load electromotive force so that the output current of the DC constant current power supply device 1 becomes a constant current value commanded by the current setting command signal 34. A drive signal 32 for driving the semiconductor switch 31 (S1 to S5) is output.

  FIG. 24 is a diagram showing the operation of the semiconductor switch 19 (S1 to S5) and the output voltage at the time of operation under four conditions of positive and small load electromotive force and negative and large. When the load electromotive force is positive and large, the pair of semiconductor switches 31 (S1, S4) is selected, and the on period is lengthened. For this reason, a positive large average voltage is output across the terminals X and Y. When the load electromotive force is positive and small, the pair of semiconductor switches 31 (S1, S4) is selected, and the on period is shortened. For this reason, a positive small average voltage is output across the terminals X and Y. On the other hand, when the load electromotive force is negative and the absolute value is large, the pair of semiconductor switches 31 (S2, S3) is selected, and the ON period is lengthened. For this reason, an average voltage having a large negative absolute value is output at both ends of the terminals X and Y. Further, when the load electromotive force is negative and small, the pair of semiconductor switches 31 (S1, S4) is selected, and the ON period is shortened. For this reason, an average value voltage having a small negative absolute value is output to both ends of the terminals X and Y.

  FIG. 25 shows the operation of the DC constant current power supply device 1 corresponding to a series of operations of starting acceleration, constant speed rotation, regenerative braking and stopping of the constant current multiphase motor 3. When the operation of the constant current multiphase motor 3 is performed as shown in FIG. 25A, the DC constant current power supply device 1 operates when the constant current multiphase motor 3 is driven, as shown in FIG. During braking, it is necessary to supply a constant current larger than that during constant speed rotation to the constant current multiphase inverter 2.

  The load electromotive force viewed from the terminal X of the constant current multiphase inverter 2 is positive in the driving state and negative in the braking state, and its magnitude is substantially proportional to the rotational speed of the rotor of the constant current multiphase motor 3. As shown by the dotted line in FIG. 25C, the DC constant current power supply device 1 outputs a voltage obtained by adding a voltage drop (resistance drop) due to the resistance of the load circuit to a positive and negative load electromotive force. A DC constant current can be supplied to the current multiphase inverter 2. Thereby, at the time of braking of the constant current multiphase motor 3, regenerative braking is possible until stopping, and it is not necessary to use a mechanical brake.

  When the load-side constant current multiphase motor 3 is in a braking state, the load electromotive force is negative. In this case, in the DC constant current power supply device 1, the pair of semiconductor switches 31 (S 2, S 3) operates, the output voltage becomes negative, and the regenerative current flows from the positive terminal of the DC power supply 29 from the load side. This phenomenon is similar to the charging of the battery. The DC power supply 29 has a charging function and charges regenerative power. On the other hand, when the DC power supply 29 is a fuel cell or the like and does not have a charging function, it is necessary to connect an ultracapacitor in parallel to the DC power supply 29 for energy recovery. Furthermore, even when the direct current power source 29 has a charging function like a lithium ion battery, when the regenerative power becomes a steep fluctuation of a unit of several tens of seconds, it cannot be appropriately charged. It is desirable to connect an ultracapacitor in parallel with the DC power supply 29.

  As described above, the motor drive system of the present invention can improve energy efficiency more practically and is useful as a motor drive system.

It is a figure which shows the structure of an electric vehicle. It is a figure which shows the structure of a motor drive system. It is an axial sectional view of a multiphase constant current motor. It is an axial perpendicular direction sectional view of a multiphase constant current motor. It is a figure which shows the structure (expanded linearly) of an armature coil. It is a figure which shows the structure (displayed in circular arc shape) of an armature coil. It is a time chart which shows operation | movement of a multiphase constant current inverter. It is a figure which shows the detailed structure of an inverter control apparatus. It is a figure which shows an example of the drive signal with respect to an angular position signal. It is a figure which shows switching operation | movement of a semiconductor switch. It is a figure which shows the state when all the semiconductor switches are OFF. It is a figure which shows the structure of the inverter unit which added the diode. It is a figure which shows the structure of the conventional inverter unit. It is a figure which shows the commutation phenomenon of an inverter unit. It is a figure which shows the structure of the inverter unit which added the capacitor | condenser. It is a figure which shows the time transition of the electric current of a capacitor | condenser, and the electric current of an armature coil. It is a figure which shows the structure of the inverter unit which connected resistance or the coil to the capacitor | condenser in series. It is a figure which shows the specific structure of the conventional constant voltage inverter. It is a figure which shows the specific structure of the constant current multiphase inverter which added the diode and the capacitor | condenser. It is a figure which shows the position of the rotor in a drive state, and an armature coil current. It is a figure which shows the position of the rotor in a braking state, and an armature coil current. It is a figure which shows the load electromotive force which arises in a polyphase constant current inverter. It is a figure which shows the structure of a direct current constant current power supply device. It is a figure which shows the operation | movement of the semiconductor switch in a direct current constant current power supply device, and the output voltage at the time of the operation | movement. It is a figure which shows the drive state of a motor vehicle, and operation | movement of a direct current constant current power supply device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 DC constant current power supply device 2 Multiphase constant current inverter 3 Multiphase constant current motor 4 Differential gear 5 Mechanical brake 6 Rotor core 7 Rotating shaft 8 Bearing 9 Magnet material 10 Groove 11 Light shielding plate 12 Photo sensor 13 Stator core 14 Air gap DESCRIPTION OF SYMBOLS 15 Stop metal fitting 16 Case 17 Armature coil 18-1, 18-2 Terminal 19, 31, 41 Semiconductor switch 20 A phase single phase bridge unit 21 B phase single phase bridge unit 22 C phase single phase bridge unit 23 D phase single phase Bridge unit 24 Inverter control device 25 Angular position signal 26, 32 Drive signal 27 Braking command signal 29 DC power supply 30 Reactor 34 Current setting command signal 35 Constant current power supply control device 51, 52 Delay circuit 53, 54 Inversion circuit 60 Diode 70 Capacitor 71 Resistance 72 coil

Claims (5)

A power supply device and an inverter unit for the number of phases connected in series to control the direction of the direct current from the power supply device to generate a rectangular wave alternating current, and drive the switching element in the inverter A motor drive system having switching control means for controlling, and a motor for driving and braking according to a rectangular wave alternating current from the inverter flowing through the armature coil,
The power supply device
A DC power supply for supplying DC voltage;
Voltage control means for inputting a DC voltage from the DC power source and controlling the polarity and magnitude of the output voltage according to the electromotive force of the motor so that the output current becomes a DC constant current;
The inverter unit is
A first switching element having a self-turnoff capability connected between an input end and one end of an armature coil for one phase in the motor;
A second switching element having a self-turn-off capability connected between the other end of the armature coil for one phase in the motor and the output end;
A third switching element having a self-turnoff capability connected between the input end and the other end of the one-phase armature coil in the motor;
A fourth switching element having a self-turn-off capability connected between one end and an output end of an armature coil for one phase in the motor;
The switching control means is configured to switch the first to fourth switching elements so that at least one of the first and second switching elements and the third and fourth switching elements is turned on during a driving period. A motor drive system for controlling driving of an element.   The inverter unit includes a diode that is connected in series to each of the first to fourth switching elements and has an anode on the upstream side and a cathode on the downstream side of the direct current from the power supply device. The motor drive system according to claim 1.   The motor drive system according to claim 1, wherein the inverter unit includes a capacitor connected in parallel to the armature coil.   The motor drive system according to claim 3, wherein a resonance frequency of the armature coil and the capacitor is 10 to 20 times a frequency of the rectangular wave alternating current. The motor drive system according to claim 3 or 4, wherein the inverter unit includes a resistor or a coil connected in series to the capacitor.

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