JP2007037264A - Motor drive circuit and electromagnetic suspension device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor drive circuit that can make an electromagnetic suspension device generate a sufficient load in a middle-high speed range of a stroke speed even at a fail. <P>SOLUTION: The motor drive circuit C is constituted such that a plurality of arms A1, A2 and A3 connected with switching elements S1, S2, S3, S4, S5 and S6 in series are connected to a power supply E, and the switching elements S1, S2, S3, S4, S5 and S6 of the arms A1, A2 and A3 are connected to one another by windings 12 of the motor M. The motor drive circuit comprises a short-circuiting means T that short-circuits the windings 12 of the motor M, and a resistor 60 that is arranged so as to be in series to each winding 12 at least at the short circuit. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to improvements in motor drive circuits and electromagnetic suspension devices.

  In a motor drive circuit for driving a motor, for example, as shown in FIG. 8, switching elements 71 and 72, switching elements 73 and 74 are provided to enable output torque control of a motor configured as a three-phase brushless motor. , And a circuit configured by connecting arms 81, 82, 83 each having switching elements 75, 76 connected in series to a plurality of power supplies, and switching the switching elements 71, 72, 73, 74, 75, 76. The motor is driven by control (see Patent Documents 1 and 2).

  In an electromagnetic suspension device that uses the electromagnetic force of a motor, the motor drive circuit is connected to the motor, and the torque and propulsive force that are the output of the motor are controlled by the motor drive circuit.

Specific examples of the electromagnetic suspension device include a ball screw nut, a screw shaft that is screwed to the ball screw nut, and a motor that is coupled to the screw shaft, and the ball screw nut and the screw shaft that are used when the shock absorber expands and contracts. Is converted into a rotational motion of the screw shaft, and the rotational motion of the screw shaft can be transmitted to the rotor of the motor. The motor torque is controlled by the motor drive circuit to control the screw shaft and the ball screw. A load (control force) that suppresses axial relative motion with the nut can be generated (see, for example, Patent Document 3).
JP 2001-204194 A (paragraph number 0012, FIG. 1) Japanese Patent Laying-Open No. 2003-324986 (paragraph number 0038, FIG. 4) JP 2003-104025 A (Detailed description of the invention, FIG. 4 and FIG. 17)

  And, in the electromagnetic suspension device as described above, since it is mounted on a vehicle, there is a demand for reducing the power consumption as much as possible. On the other hand, a sufficient load is applied even in a region where the stroke speed is low. There is a desire to make it possible.

In order to achieve both power saving and load generation, it is necessary to reduce the resistance of the motor winding and the drive circuit as much as possible. Here, as shown in FIG. 9, the regenerative region (shaded area in FIG. 9) in which the power can be charged by the power generation of the motor is a stroke in the electromagnetic suspension device in a state where the winding of each phase of the motor is short-circuited from the origin. It is partitioned by the slope of the tangent drawn so as to contact the short-circuit characteristic that is the relationship between the speed and the load. The smaller the resistance, the greater the slope of the tangent and the larger the regeneration region. And if a load is generated with respect to the stroke speed in this regeneration region, the electromagnetic suspension device does not consume electric power.
The rotational speed of the rotor of the motor is proportional to the relative speed of the screw shaft and the ball screw nut, that is, the stroke speed of the electromagnetic suspension device, and the output torque of the motor is proportional to the load of the electromagnetic suspension device. The short-circuit characteristic described above is obtained by converting the short-circuit characteristic, which is the relationship between the rotational speed and torque of the motor itself, into the relationship between the stroke speed and the load of the electromagnetic suspension device. In the present specification, the term “short-circuit characteristic” refers to the relationship between the stroke speed and the load of the electromagnetic suspension device when the motor is short-circuited as described above unless otherwise specified.

  As described above, in this electromagnetic suspension device, if the resistance is reduced, the regenerative region is expanded. Therefore, an opportunity to generate a necessary load in the regenerative region even if the stroke speed is low. As a result, power saving and load generation are both achieved.

  In general, in an electromagnetic suspension device, the torque generated by the motor is controlled by appropriately controlling the switching element of the motor drive circuit connected to the power source, and the electromagnetic suspension device controls the generated load. However, when control of the switching element becomes impossible for some reason, it is difficult to generate a load as it is at the time of so-called failure. Is electrically disconnected from the motor drive circuit, and the motor winding is short-circuited.

  However, as shown in FIG. 9, when the stroke speed of the electromagnetic suspension device is increased, the load reaches a peak at a certain stroke speed. However, the load increases as the stroke speed increases thereafter. Has a characteristic of gradually decreasing, and when the resistance is reduced, the short-circuit characteristic has a property of being compressed toward the origin along the stroke speed axis.

  Therefore, if the resistance is set to a small value as described above, there is a merit that it is possible to achieve both power saving and load generation in a region where the stroke speed is low, but on the other hand, if the motor is short-circuited when the stroke speed is medium to high, a large load Therefore, if the above-described measures for short-circuiting the motor are taken, the electromagnetic suspension device may not be able to generate a sufficient load in the middle-high speed range.

  Therefore, the present invention has been developed to improve the above-described problems, and the object of the present invention is to generate a sufficient load on the electromagnetic suspension device in the middle and high stroke speed range even during a failure. It is an object of the present invention to provide a motor drive circuit that can be made to operate, and an electromagnetic suspension device that can generate a sufficient load in a middle and high stroke speed range even during a failure.

  In order to achieve the above object, a motor driving circuit according to the present invention is a motor driving circuit in which a plurality of arms having switching elements connected in series are connected to a power source, and the switching elements of each arm are connected to a motor winding. The circuit includes a short-circuit means for short-circuiting the motor windings and at least a resistor interposed in series with each winding when the short-circuit occurs.

  The electromagnetic suspension device of the present invention includes the one member, the other member that exhibits relative motion with respect to the one member, a motor that can suppress at least the relative motion, and the motor drive circuit. Achieved.

 According to the motor drive circuit of the present invention, each winding of the motor can be short-circuited with respect to an abnormality in the control system, so that the electromagnetic suspension device can function reliably as a passive damper even in the event of an abnormality. Is possible.

 Further, in the electromagnetic suspension device of the present invention, each winding of the motor can be short-circuited with respect to an abnormality of the control system, so that it can function as a passive damper reliably even in the event of an abnormality. Is possible.

 According to the motor drive circuit and the electromagnetic suspension device, it is possible to increase the torque constant, expand the regenerative region at normal times, and generate a load necessary for vehicle body posture control in the regenerative region. When fail-safe, the motor windings can be short-circuited and at the same time the short-circuit characteristics can be changed from the normal short-circuit characteristics by resistance, and a sufficient load can be generated even when the stroke speed is in the middle-high speed range. Is possible.

 Therefore, if you turn the reverse side, it is normal that the short-circuit characteristic of the motor in the electromagnetic suspension device can be the short-circuit characteristic without using a resistor, and the short-circuit characteristic through a resistor can be used when fail-safe. Sometimes, as a short-circuit characteristic with a larger regenerative area, it is possible to generate sufficient load while saving power during normal operation, and even during fail-safe operation, sufficient load can be generated even if the stroke speed is in the middle to high speed area. Riding comfort in the vehicle can be ensured.

  The present invention will be described below based on the embodiments shown in the drawings. FIG. 1 is a diagram conceptually showing an electromagnetic suspension device according to an embodiment. FIG. 2 is a circuit diagram of the motor drive circuit. FIG. 3 is a diagram showing a short-circuit characteristic which is a relationship between the load of the electromagnetic suspension and the stroke speed in a state where the motor is short-circuited. FIG. 4 is a diagram illustrating a regeneration region. FIG. 5 is a diagram illustrating a setting frequency state of generated loads on the expansion side and the contraction side of a shock absorber applied to light, small, and ordinary automobiles. FIG. 6 is a diagram showing the frequency of the expansion / contraction stroke speed of the shock absorber while the vehicle is running. FIG. 7 is a conceptual diagram of another electromagnetic suspension device.

  As shown in FIG. 1, the electromagnetic suspension device in one embodiment includes a screw shaft 1 that is one member, a ball screw nut 2 that exhibits relative motion with respect to the screw shaft 1, a motor M, and a motor drive circuit C. It is prepared for.

  Specifically, the screw shaft 1 is rotatably engaged with the ball screw nut 2, and the upper end of the screw shaft 1 in FIG. 1 is connected to the rotor R of the motor M. The other ball screw nut 2 is fixed to the upper end of a cylinder 4 into which the screw shaft 1 is inserted, and can be connected to one of the sprung member and the unsprung member of the vehicle via this cylinder 4. It is like that.

  The screw shaft 1 is rotatably connected to the other of the sprung member and the unsprung member of the vehicle. Specifically, the screw shaft 1 is provided on the other of the sprung member and the unsprung member of the vehicle. The motor M is fixed to the other of the sprung member and the unsprung member of the vehicle.

  Therefore, when the screw shaft 1 and the ball screw nut 2 exhibit a linear relative motion in the axial direction, the screw shaft 1 exhibits a rotational motion, and the rotational motion of the screw shaft 1 is transmitted to the rotor R of the motor M. It will be. Here, the rotational speed of the screw shaft 1 may be reduced through a reduction gear constituted by a gear mechanism or the like to transmit the rotational motion of the screw shaft 1 to the rotor R.

  When the screw shaft 1 and the ball screw nut 2 exhibit a linear relative motion in the axial direction, the ball screw nut 2 is used when the screw shaft 1 cannot be rotated and the ball screw nut 2 is rotated instead. The rotational motion of 2 may be transmitted to the rotor R of the motor M. Specifically, the screw shaft 1 is non-rotatably connected to one of the sprung member and unsprung member of the vehicle, and the other ball screw nut 2 is connected to the other of the sprung member and unsprung member of the vehicle with a ball bearing or the like. And the rotational movement of the ball screw nut 2 may be transmitted to the rotor R of the motor M via a gear mechanism, a friction wheel mechanism, or the like.

  In this case, the motor M includes a cylindrical frame 10, a stator that is an armature provided on the inner peripheral side of the frame 10, and a rotor R that is rotatably supported by the frame 10. Specifically, the stator includes an annular stator core 11 having a plurality of teeth, and a winding 12 in each of the U, V, and W phases wound around each tooth, The rotor R includes a shaft 13 and a driving magnet 14 mounted on the outer periphery of the intermediate portion of the shaft 13.

  Each of the U-phase, V-phase, and W-phase windings is Y-shaped at one end, but may be Δ-connected.

  And the drive magnet 14 is comprised with the magnet made into the block so that the predetermined number of poles can be implement | achieved, and it is embedded in the shaft 13, This motor M is made into the embedded magnet type. Of course, the drive magnet 14 is blocked so that a predetermined number of poles can be realized and bonded to the outer periphery of the shaft 13, or it is formed in an annular shape and dividedly magnetized so as to be fitted to the outer periphery of the shaft 13. May be.

  The motor M is equipped with a rotation angle sensor 15 for detecting the rotation angle of the rotor R. Specifically, for example, the rotation angle sensor 15 is attached to the resolver core provided on the shaft 13 and the frame 10. It only has to be constituted by a resolver stator facing the provided resolver core. In addition, an optical encoder may be adopted, and when a sensing magnet is provided in the rotor R, a Hall element, MR element, etc. The magnetic sensor may be provided on the frame 10.

  Further, a current sensor (not shown) for detecting the current flowing in each of the windings 12 of the motor M, U, V, and W is separately provided, and signals output from the rotation angle sensor 15 and the current sensor are sent to the control device 20. Entered.

  In order to control the current flowing through the winding 12 of the motor M, specifically, the U, V, and W phase windings 12 are connected to the motor drive circuit C shown in FIG.

  As shown in FIG. 2, the motor drive circuit C for driving the motor M includes an arm A1 in which switching elements S1 and S4 are connected in series, an arm A2 in which switching elements S2 and S5 are connected in series, and a switching element S3. , S6 connected in series, a short-circuit means T for short-circuiting the winding of the motor M, and a resistor 60, each arm A1, A2, A3 is connected in parallel, and each arm A1, Between the switching elements S1, S4, S2, S5, S3, S6 of A2, A3 are output terminals P1, P2, P3 connected to the motor M.

 Further, the upper connection point in FIG. 2 of each arm A1, A2, A3 is connected to a power source E such as a vehicle battery via a relay L, and the lower connection point in FIG. Whether the current supply from the power source E to the motor drive circuit C is possible or not is performed by the above-described relay L. Although the relay L is well known and will not be described in detail, a coil built in the relay L is excited. In such a state, current is supplied to the motor drive circuit C.

  The arm A1 is configured by connecting two switching elements S1 and S4 in series. An output terminal P1 is provided between the switching elements S1 and S4 of the arm A1, and the output terminal P1 is connected to the motor M. It is connected to the U phase of winding 12.

  The other arms A2 and A3 have the same configuration as the arm A1, and their output terminals P2 and P3 are connected to the V phase and W phase of each winding 12 of the motor M, respectively.

  Therefore, for example, when the switching element S1 and the switching element S5 are turned on, current can be passed through the U phase and the V phase of the winding 12 of the motor M. Similarly, any one of the arms A1, A2, A3 is appropriately selected. When one switching element S4, S5, S6 of the other switching arms S1, S2, S3 and the other two arms A1, A2, A3 is turned on, each winding 12 of the motor M can be energized. The control device 20 controls the opening and closing of the motor M so that a rotating magnetic field is formed in each of the U, V, and W phase windings 12.

  The switching element S1 is a MOSFET (Metal Oxide Semiconductor, FET: Field Effect Transistor), which includes a parasitic diode K1 that connects the source electrode and the drain electrode. A switching element other than the MOSFET may be used.

The other switching elements S2, S3, S4, S5, and S6 have the same configuration as that of the switching element S1, are respectively MOSFETs, and include parasitic diodes K2, K3, K4, K5, and K6. The diodes K1, K2, K3, K4, K5, and K6 function as flywheel diodes that absorb surges generated in the windings of the motor M when the switching elements S1, S2, S3, S4, S5, and S6 are turned off. The switching elements S1, S2, S3, S4, S5 and S6 can be protected.

  The switching elements S1, S2, S3, S4, S5, and S6 are respectively connected to the energization phase of the control device 20 based on the rotation angle of the rotor detected by the rotation angle sensor 15 and the current flowing through each winding 12. The motor M is driven by applying a voltage to the gate electrode by switching control and being controlled to open and close, and further, the output torque and rotor rotational speed of the motor M are controlled by PWM control.

  In addition to PWM control, control using a continuous modulation method such as PAM (Pulse Amplitude Modulation) or PPM (Pulse Position Modulation) or a discontinuous modulation method such as a PNM (Pulse Number Modulation) circuit may be performed.

  In the motor drive circuit C, during the PWM control, each of the switching elements S1, S2, S3, S4, S5, and S6 has a predetermined pulse width period that realizes a predetermined duty ratio under the control of the control device 20, respectively. The control is performed so that the torque generated by the motor M is turned on, and the torque generated by the motor M is thereby controlled.

  Therefore, in this electromagnetic suspension device, since the drive source is the motor M, when the motor M is driven by being supplied with electric energy via the motor drive circuit C, the screw shaft 1 is generated by the torque generated by the motor M. And the screw shaft 1 and the ball screw nut 2 can be positively and relatively linearly moved, that is, stroked, so that the function as an actuator can be exhibited.

  In addition, when a rotational motion is forcibly input from the screw shaft 1, the motor M generates a magnetic field due to a current flowing through the winding 12 by the induced electromotive force or the power from the power source E, and an electromagnetic force is generated. Since the torque that suppresses the rotational movement of the screw shaft 1 is generated, it functions to suppress the relative linear movement of the screw shaft 1 and the ball screw nut 2.

  That is, in this case, the torque generated by the electric power obtained by the motor M regenerating kinetic energy input from the outside and converting it into electric energy, or by the electric power supplied from the power source in addition to this regeneration. Thus, the relative linear motion of the screw shaft 1 and the ball screw nut 2 can be suppressed.

  Furthermore, this electromagnetic suspension device can cause the motor M to function as both an actuator and a generator, so that the relative linear motion of the screw shaft 1 and the ball screw nut 2 can be suppressed, and at the same time, the function as an actuator can be utilized. Thus, the posture control of the vehicle body of the vehicle can be performed at the same time, so that the function as an active suspension can be exhibited.

  The control device 20 is not illustrated as hardware, but specifically, for example, an amplifier for amplifying each signal output from various sensors necessary for a current sensor, a rotation angle sensor, and vehicle body posture control, A converter that converts an analog signal into a digital signal, a storage device such as a CPU (Central Processing Unit) and a ROM (Read Only Memory), a RAM (Random Access Memory), a crystal oscillator, and a bus line that connects these. And a load to be generated in the electromagnetic suspension device based on a predetermined control law for vehicle body posture control, and each switching element S1, S2, S3, S4, S5, S6 of the motor drive circuit C. Gives a control signal as a PWM pulse signal And it is capable of generating 該荷 heavy to electromagnetic suspension system.

  The control processing procedure for controlling the switching of the switching elements S1, S2, S3, S4, S5, and S6 of the motor drive circuit C to drive the motor M by PWM is stored in advance in a ROM or other storage device as a program. Has been.

  Further, when detecting an abnormality, the control device 20 determines a predetermined threshold value as a difference between a current value flowing in the winding 12 of the motor M detected by the current sensor and a current command value calculated by the control device 20, for example. It is determined that there is an abnormality in the control system, such as when the time is exceeded, when an abnormality is detected by self-diagnosis of the current sensor or rotation angle sensor, or when the abnormality is determined as a result of self-diagnosis of the control device 20 itself. In the case of a failure, a transition is made to a fail-safe mode to be described later.

  In addition, the control apparatus 20 may be integrated into ECU mounted in a vehicle as this hardware.

 Next, the short-circuit means T will be described. In the figure, the short-circuit means T includes a bypass B connected in parallel to the arms A1, A2, A3, and a switching element 50 provided in the middle of the bypass B. And a switching circuit V that is connected to both ends of each arm A1, A2, A3 and operates the switching element 50.

 In more detail, the switching element 50 is an N-channel MOSFET and is turned off when a voltage is applied to the gate electrode, and is normally maintained by the switching circuit V so that no voltage is applied. Maintained in a state.

 Further, a resistor 60 is interposed between the drain electrode of the switching element 50 of the bypass B and the contact points of the arms A1, A2, A3. When the switching element 50 is turned on, the switching elements S1, S2, S3, S4, S5 and S6 for PWM control of the motor M are turned off and the windings 12 of the motor M are short-circuited by the bypass B, the electromagnetic The regenerative current caused by the vibration input to the suspension device and the induced electromotive force in the winding 12 is rectified by the input parasitic diodes K1, K2, K3, K4, K5, K6, and the upper end side of the bypass B in FIG. The regenerative current passes through the bypass B in the order of the resistor 60 and the switching element 50 and is returned to the winding 12. Therefore, this resistor 60 is connected in series to each winding 12 in this short circuit state.

 Further, the switching circuit V is configured by connecting the resistor 61 and the switch 51 in series, and the resistor 61 side is connected to the upstream side of the regenerative current in the short-circuit state of each arm A1, A2, A3, and the switch 51 side is connected. The resistor 61 and the switch 51 are connected so that each arm A1, A2, A3 is connected to the upstream side of the current in the short-circuit state, and the voltage between the resistor 61 and the switch 51 can be applied to the gate electrode of the switching element 50. Is connected to the gate electrode.

 That is, when the switch 51 is in the on state, the gate electrode of the switching element 50 is grounded, no voltage is applied, and the switching element 50 is maintained in the off state. On the other hand, when the switch 51 is turned off, a voltage is applied from the switching circuit V to the gate electrode, the switching element 50 is turned on, the bypass B is opened, and the motor M Each winding 12 is short-circuited. The resistor 61 is interposed to apply the voltage after the voltage drop to the gate electrode of the switching element 50, and an excessive voltage due to the induced electromotive force or the inductance of each winding 12 is directly applied to the switching element 50. The switching element 50 is protected so as not to be applied to the 50 gate electrodes.

 The motor drive circuit C and the electromagnetic suspension device are configured as described above, and the operation thereof will be described below.

 First, at the normal time, as described above, the switching elements S1, S2, S3, S4, S5, and S6 of the motor drive circuit C are controlled by a predetermined control law under the control of the control device 20.

 When the control device 20 determines that there is an abnormality in the control system, the control device 20 shifts to the fail-safe mode, supplies power to the relay L, and switches the switching elements S1, S2, S3, S4, S5, S6. The control signal output to the gate electrode is stopped, and the switch 51 is turned off.

 Then, the power supply from the power source E to the motor drive circuit C is stopped by turning off the relay L. On the other hand, the switching element 50 in the short-circuit means T is turned on and the bypass B is opened, and each winding 12 of the motor M is short-circuited. Will be.

 In this state, when vibration is input from the road surface to the electromagnetic suspension device while the vehicle is traveling, the electromagnetic suspension device expands and contracts, so that the motor M is forcibly rotated.

 When the motor M is forcedly rotated as described above, an induced electromotive force is generated in each winding 12, and a regenerative current flows due to this induced electromotive force. Thus, the electromagnetic suspension device can generate a load corresponding to the short-circuit characteristic with respect to the expansion / contraction stroke speed.

 In this fail safe mode, the winding is short-circuited and a current flows through the bypass B, so that the regenerative current also passes through the resistor 60. Here, the action of the resistor 60 will be described. Since the resistor 60 acts so as to reduce the current value generated by the induced electromotive force, as shown in FIG. By acting so as to expand along the stroke speed axis, the curve Y, which is a short-circuit characteristic when there is no resistance 60, is changed to the curve Z.

 That is, in this motor drive circuit, it is possible to short-circuit each winding 12 of the motor M with respect to an abnormality in the control device 20 itself or the control system, so that the electromagnetic suspension device can be operated even when there is an abnormality. It is possible to reliably function as a passive damper, and in the electromagnetic suspension device, each winding 12 of the motor M can be short-circuited with respect to an abnormality in the control device 20 or the control system. Therefore, even when there is an abnormality, it can function reliably as a passive damper.

 During normal times, the regenerative region K is enlarged while keeping the resistance of the winding 12 of the motor M and the entire motor drive circuit small, and a load necessary for vehicle body posture control is generated in the regenerative region K. However, at the time of fail-safe, each winding 12 of the motor M is short-circuited, and at the same time, the resistance of the winding 12 of the motor M and the entire resistance of the motor drive circuit is increased by the resistor 60, so that the short-circuit characteristic is changed from the normal short-circuit characteristic. As shown in FIG. 3, it can be changed in particular, and it is possible to generate a sufficient load even when the stroke speed is in the middle to high speed region.

 Therefore, in other words, it is possible to make the short circuit characteristic of the motor in the electromagnetic suspension device the short circuit characteristic without using the resistor 60 in the normal state and the short circuit characteristic through the resistor 60 at the time of fail safe. In normal times, as the short-circuit characteristic with a larger regenerative region K, it is possible to generate sufficient load while saving power during normal operation. It is possible to secure the ride comfort in the vehicle. Also, in normal times, the electromagnetic suspension device can set the generated load at a stroke speed of around 0.1 m / s to the load generated by a general hydraulic shock absorber mounted on the vehicle, so it is equivalent to the hydraulic shock absorber. It is possible to achieve a comfortable ride.

 If the switch 51 is a switch, MOSFET, or the like having the same configuration as that of the relay L, and can be turned off by stopping the voltage application, an abnormality occurs in the power supply system of the control device 20 In addition, since the short-circuit means T can automatically short-circuit each winding 12 of the motor M, it is possible to reliably perform fail-safe.

By the way, in this electromagnetic suspension device, as described above, when the rotor R of the motor M rotates, the magnetic flux of the driving magnet 14 of the rotor R crosses the winding 12, so that an induced electromotive force is generated in the winding 12 and regeneration is performed. Since the current flows, the current due to the power source E and the regenerative current due to the induced electromotive force flow through the winding 12, but the regenerative power that can charge the power source E by the induced electromotive force of the winding 12 of the motor M is generated. As shown in FIG. 4, the regenerative region K that can be performed is a range surrounded by the tangent line X that passes through the origin and is in contact with the short-circuit characteristic and the stroke speed axis, and this regenerative region K can be determined by the short-circuit property. it can. Furthermore, the inclination of the tangent line X is not limited to the torque constant of the motor M and the torque constant of the motor M and the entire resistance of the winding 12 and the motor drive circuit C, that is, the internal resistance of the lead wire in addition to the resistors in the circuit. Therefore, the regeneration region K can also be determined by the torque constant and the total resistance of the winding 12 of the motor M and the motor drive circuit C. The inclination of the tangent line X can also be adjusted by the lead of the screw shaft 1.

  On the other hand, in the vehicle, a spring element is interposed between the unsprung member and the unsprung member in order to make it difficult to transmit the vibration input to the unsprung member to the unsprung member during traveling of the vehicle. In order to suppress vibration, a shock absorber is interposed between the unsprung member and the sprung member, but the set frequency of the generated load on the expansion side and contraction side of the shock absorber applied to light, small and ordinary automobiles From FIG. 5 showing the situation, on the expansion side, there are many shock absorbers that generate a load in the range of 200N to 1000N centering around 600N, and on the contraction side, the load is in the range of 0N to 600N centering around 300N. In order to suppress the above-described vehicle body vibration, the shock absorber needs to generate a load of about 1000 N on the expansion side and about 600 N on the contraction side.

  Moreover, from FIG. 6 which shows the frequency of the expansion / contraction stroke speed of the shock absorber during traveling of the vehicle, the shock absorber is -0.1 m / s, assuming that the contraction side stroke speed is a negative value and the expansion side stroke speed is a positive value. Is frequently used within a stroke speed range of 0.1 m / s.

  As can be understood from the above, the frequently used stroke speed range in the expansion and contraction of the shock absorber is within a range of 0.1 m / s (in the case where a positive or negative sign is attached in the expansion and contraction direction, it is −0.1 m / s or more and 0.00. The required generated load is within 1000 N.

  From this, as shown in FIG. 4, the load in the normal short-circuit characteristic in the above-described electromagnetic suspension device, that is, the short-circuit characteristic in a state where the winding 12 of the motor M is short-circuited without the resistor 60 at the time of fail-safe. The frequently used stroke speed range in which the maximum value becomes a range of 0.1 m / s or less is set.

  Accordingly, since the regeneration region K within the stroke speed range that frequently appears during vehicle travel increases, the opportunity for charging the power source E by regeneration can be increased, and energy regeneration by the motor M can be performed efficiently. Needless to say, the power saving can be ensured, and further, the riding comfort in the vehicle can be improved. However, the electromagnetic suspension device can be obtained by standardizing the frequently used stroke speed range in this way. This improves the versatility and reduces the manufacturing cost.

  At this time, if the tangent line X is set so as to pass above the point where the stroke speed is 0.1 m / s and the load is 1000 N, the stroke in which the electromagnetic suspension device is frequently used. The entire load range that needs to be generated as a shock absorber within the speed range is covered in the regeneration region K.

  Therefore, in the case where the electromagnetic suspension device is frequently used, when the electromagnetic suspension device is frequently used, the power source E is always regenerated and the power source E is not consumed and the power of the power source E is not consumed. It is possible to reliably save power, prevent a situation where the power source E is raised, and further, it is optimal for a vehicle using a drive source such as an electric vehicle as a motor.

  Further, the electromagnetic suspension device is, like the other electromagnetic suspension devices shown in FIG. 7, the cylinder 31 that is one member, the rod 32 that is the other member that exhibits relative movement with respect to the cylinder 31, and at least suppressing the relative movement. You may make it comprise with possible motor M2.

  Specifically, the cylinder 31 is connected to one of a sprung member and an unsprung member of the vehicle, and a rod 32 connected to the other of the sprung member and the unsprung member of the vehicle is passed through the cylinder 31. .

  The motor M2 includes a driving magnet 33 that is mounted on the outer periphery of the rod 32 so that S poles and N poles appear alternately in the axial direction, and a winding 34 that faces the driving magnet 33 in the cylinder 31. The windings 34 are arranged so that the U, V, and W phases are alternately arranged along the axial direction of the cylinder 31 over a predetermined length.

  Note that the winding 34 provided in the cylinder 31 is formed in an annular shape, and at least the inner peripheral side is coated with resin or the like. The inner periphery of the winding 34 and the outer periphery of the rod 32 or the drive magnet 33 An annular bearing (not shown) is disposed between them, and the shaft 32 is prevented from shaking with respect to the cylinder 31.

  That is, in this other electromagnetic suspension device, a so-called linear motor type configuration in which the drive magnet 33 moves relative to the winding 34 when the rod 32 advances and retreats relative to the cylinder 31 and exhibits relative motion. Even in the other electromagnetic suspension devices, similarly to the electromagnetic suspension device in the above-described embodiment, the motor M2 functions as both a motor and a generator. Therefore, by applying the motor drive circuit C, it is possible to combine the same functions and effects as those of the electromagnetic suspension device according to the embodiment.

  This is the end of the description of the embodiment of the present invention, but the scope of the present invention is of course not limited to the details shown or described.

It is the figure which showed notionally the electromagnetic suspension apparatus in one embodiment. It is a circuit diagram of a motor drive circuit. It is a figure which shows the short circuit characteristic which is the relationship between the load of an electromagnetic suspension in the state which short-circuited the motor, and stroke speed. It is a figure which shows a regeneration area | region. It is a figure which shows the setting frequency situation of the generation | occurrence | production load of the expansion | extension side and shrinkage | contraction side of the buffer applied to a light, small size, and a normal vehicle. It is a figure which shows the frequency of the expansion-contraction stroke speed of the buffer during driving | running | working of a vehicle. It is a conceptual diagram of another electromagnetic suspension apparatus. It is a circuit diagram of the conventional motor drive circuit. It is a figure which shows a regeneration area | region.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Screw shaft which is one member 2 Ball screw nut 10 which is the other member Frame 11 Stator core 12, 33 Winding 13 Shafts 14, 34 Driving magnet 15 Rotation angle sensor 20 Control device 31 Tube 32 which is one member Rod 50 which is the other member , S1, S2, S3, S4, S5, S6 Switching element 51 Switch 60, 61 Resistance A1, A2, A3 Arm B Bypass C Motor drive circuit E Power supply K1, K2, K3, K4, K5, K6 Parasitic diode L Relay M Motor P1, P2, P3 Output terminal R Rotor T Short-circuit means V Switching circuit

Claims (10)

In a motor drive circuit in which a plurality of arms connected in series with switching elements are connected to a power source and the switching elements of each arm are connected to the motor windings, a short-circuit means for short-circuiting the motor windings and at least when short-circuited A motor drive circuit comprising a resistor interposed in series with each winding. 2. The motor drive circuit according to claim 1, wherein the short-circuit means shorts the winding when the control of the switching element becomes impossible. The short-circuit means includes a bypass connected to both ends of each arm and a switch means provided in the middle of the bypass, and the resistor is interposed in the middle of the bypass and upstream of the switch means. The motor drive circuit according to claim 1. 4. The apparatus according to claim 1, further comprising: a shut-off means for shutting off the connection between each arm and the power supply, wherein the shut-off means cuts off the connection between each arm and the power supply when the switching element cannot be controlled. The motor drive circuit described. 5. The switch means is a MOS transistor having a drain electrode and a source electrode connected to a bypass, and a voltage is applied to the gate electrode of the MOS transistor by an induced electromotive force of a winding. Motor drive circuit. The motor drive circuit according to claim 5, wherein the gate electrode is grounded via a switching element. An electromagnetic suspension device comprising: one member; the other member that exhibits relative motion with respect to the one member; a motor that can at least suppress the relative motion; and the motor drive circuit according to claim 1. The load in the short-circuit characteristic, which is the relationship between the stroke speed and the load when the motor winding is short-circuited without the above resistance, is set to take the maximum value within the frequently used stroke speed range. The electromagnetic suspension device according to claim 7. 9. The electromagnetic wave according to claim 7, wherein when the other member exhibits linear relative motion with respect to the one member and the other member, the one member exhibits rotational motion, and the rotational motion of the one member is transmitted to the motor. Suspension device. 10. The electromagnetic suspension device according to claim 7, wherein the variable resistor is installed at a location where the vehicle can be air-cooled while the vehicle is running.

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