JP2012152043A - Power supply system for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent overheat of a bidirectional DC-DC converter 100 connecting between a high-voltage battery 200 and an electric motor 40 of an electromagnetic suspension device.SOLUTION: A primary switching circuit 110 and a secondary switching circuit 120 of a DC-DC converter 100 includes a switching element pair SP with two switching elements S connected in parallel at each of portions for performing switching. A switch control section 140 detects failure in the switching element pair SP based on an electric current running through one switching element S of the each switching element pair SP, a primary total current i1 and a secondary total current i2.

Description

  The present invention relates to a vehicle power supply system that transforms electric power output from an in-vehicle battery and supplies the electric power to the in-vehicle electric device, and transforms an electromotive force generated in the in-vehicle electric device to regenerate the in-vehicle battery.

  Conventionally, a high-voltage battery is mounted on a hybrid vehicle or the like. For example, the high-voltage battery has a rated voltage set to 288 V and is used as a power source for a vehicle running motor, but may also be used as a power source for other in-vehicle electric devices. Examples of the in-vehicle electric device include an electromagnetic suspension device and an electric power steering device. When power is supplied from the high-voltage battery to the in-vehicle electric device, the output voltage of the high-voltage battery is stepped down by the DC / DC converter, and the reduced power is supplied to the in-vehicle electric device.

  For example, in the electromagnetic suspension device proposed in Patent Document 1, the power output from the high voltage battery is stepped down by a DC / DC converter and supplied to a motor drive circuit (three-phase inverter). The electromagnetic suspension device includes an electromagnetic actuator having a motor and a ball screw mechanism that is connected to the motor output shaft and expands and contracts by relative movement of the sprung member and the unsprung member, and controls the energization of the motor (control of the three-phase inverter). ) Is a so-called active suspension device that can generate not only a damping force for the relative movement between the sprung member and the unsprung member but also a propulsive force that actively changes the suspension stroke.

  In general, a DC / DC converter is provided with a switching circuit in a primary winding of a transformer, and a current supplied from a battery is caused to flow alternately and reversely in the primary winding, so that the secondary winding of the transformer An AC voltage is generated, the AC voltage is rectified, and a DC voltage transformed to a predetermined voltage is output. Further, in the configuration in which the high voltage battery and the motor drive circuit of the electromagnetic suspension device are connected via the DC / DC converter, the electromotive force generated when the motor is rotated by the expansion / contraction operation of the electromagnetic actuator can be regenerated to the high voltage battery. A switching circuit is also provided in the secondary winding of the transformer of the DC / DC converter.

JP 2009-120026 JP

  When the high-voltage battery and the on-vehicle electrical device are connected via a DC / DC converter, the switching element of the DC / DC converter generates heat when the power supplied from the high-voltage battery to the motor or the regenerative power from the motor to the high-voltage battery increases. Resulting in. For example, in an electromagnetic suspension device, when a vehicle travels on an uneven road surface for a long time, the electromagnetic actuator continues to expand and contract, and thus a large current flows in both directions in the DC / DC converter for a long time. For this reason, in order to prevent overheating damage of the DC / DC converter, the electromagnetic suspension device interrupts active control and short-circuits the current-carrying terminals of the motor to each other and a power supply line from the inverter to the motor The motor opening process for shutting off is alternately performed. However, when the overheat damage of the DC / DC converter is prevented by such a method, the stopper of the electromagnetic suspension device occurs. The suspension device is provided with a stopper member (bound stopper, rebound stopper) that regulates the end of the expansion / contraction stroke. If the stopper member abuts frequently, the ride performance and the durability of the suspension deteriorate. It will lead to.

  The present invention has been made to cope with the above-described problem, and an object thereof is to suppress heat generation of a bidirectional DC voltage converter (DC / DC converter) so as not to deteriorate the vehicle performance.

In order to achieve the above object, the present invention is characterized in that an in-vehicle battery (200) and an in-vehicle electric device (40, 50) are connected via a bidirectional DC voltage converter (100), The electric power output from the vehicle is transformed by the DC voltage converter and supplied to the in-vehicle electric device, and the electromotive force generated in the in-vehicle electric device is transformed by the DC voltage converter and regenerated to the in-vehicle battery. Power supply system
The DC voltage converter includes a transformer (130) having a primary side winding connected to the in-vehicle battery and a secondary side winding connected to the in-vehicle electrical device, and a current in the primary side winding. A primary-side switching circuit (110) for alternately flowing forward and reverse, and a secondary-side switching circuit (120) for flowing a current to the secondary-side winding alternately forward and reverse,
The primary-side switching circuit and the secondary-side switching circuit each have a switching element pair (111, 112, 113, 114, 121, 122) in which two switching elements (S) are connected in parallel at the portion to be switched. Be prepared.

  In the vehicle power supply system of the present invention, the electric power output from the vehicle-mounted battery is converted into the operating voltage of the vehicle-mounted electrical device by the DC voltage converter and supplied to the vehicle-mounted electrical device. Electric power (generated power) is transformed with a DC voltage converter and regenerated on the on-board battery. In the DC voltage converter, an in-vehicle battery is connected to the primary winding of the transformer, and an in-vehicle electric device is connected to the secondary winding of the transformer. The primary side winding is provided with a primary side switching circuit. By the operation of the primary side switching circuit, the current supplied from the in-vehicle battery flows alternately to the primary side winding in the forward and reverse directions. While supplying AC power to the winding, AC power supplied from the secondary winding is converted to DC power and regenerated in the vehicle battery. Moreover, the secondary side winding of the transformer is provided with a secondary side switching circuit. By the operation of the secondary side switching circuit, the current in the secondary side winding is forward and reverse by the electromotive force generated in the in-vehicle electric device. Alternating current is supplied to supply AC power to the primary winding, while AC power supplied from the primary winding is converted to DC power and supplied to the in-vehicle electric device. In this way, DC power converted into a predetermined voltage is bidirectionally supplied between the in-vehicle battery and the in-vehicle electric device.

  In the DC voltage converter, if the mutual power supply between the in-vehicle battery and the in-vehicle electric device is large, the switching elements of the primary side switching circuit and the secondary side switching circuit generate heat. Limiting the operation of the in-vehicle electrical device can prevent overheating damage of the switching element, but the vehicle performance is sacrificed. Therefore, in the present invention, each of the primary side switching circuit and the secondary side switching circuit is provided with a switching element pair in which two switching elements are connected in parallel at the portion to be switched. By inputting a common control signal to the two switching elements constituting the switching element pair, the current paths are distributed in both switching circuits, and the current flowing through each switching element is reduced by half. Heat generation of the element can be suppressed. As a result, according to the present invention, it is possible to prevent overheating damage of the DC voltage converter without deteriorating the vehicle performance.

  Another feature of the present invention is that failure detecting means (140, S11 to S17, S21 to S27) for detecting a failure of each switching element pair in the primary side switching circuit and the secondary side switching circuit is provided. It is in.

  When a primary side switching circuit and a secondary side switching circuit are configured using a pair of switching elements, one of the paired switching elements has an off failure (a failure that is fixed in the off state and does not turn on). However, if the other switching element is normal, the DC voltage converter can continue to operate as it is, and thus cannot grasp the abnormality. However, in such a case, since the current flowing through the other switching element is doubled compared to the normal time, if the operation is continued as it is, the normal-side switching element may be damaged due to overheating. And when both of the two switching elements which finally comprise a switching element pair fail, as a DC voltage converter, an appropriate operation | movement cannot be performed.

  Therefore, in the present invention, the failure detection means detects a failure of each switching element pair in the primary side switching circuit and the secondary side switching circuit. As a result, the failure of the DC voltage converter can be grasped at the time when one of the switching elements of the switching element pair is turned off, and can be dealt with at an early stage. In addition, when both of the switching elements constituting the switching element pair are off-failed, or when at least one of them is on-failed (failure that is fixed in the on-state and does not enter the off-state), the DC voltage converter is appropriate. Since the operation can not be performed and the operation abnormality can be detected, the failure detection means in the present invention may detect the off-failure on one side of the two switching elements constituting each switching element pair.

  Another feature of the present invention is that the failure detection means obtains primary side total current information representing a primary side current value flowing between the in-vehicle battery and the primary side switching circuit. An acquisition means (156, S11) and a primary side element current for acquiring primary side element current information representing a current value flowing through the switching element on one side in each switching element pair provided in the primary side switching circuit. Secondary side for obtaining secondary side total current information representing a secondary side current value flowing between the obtaining means (151, 152, 153, 154, S11) and the in-vehicle electric device and the secondary side switching circuit. Total current acquisition means (158, S21) and current value flowing through one side switching element in each switching element pair provided in the secondary side switching circuit Based on the secondary-side single-side element current acquisition means (161, 162, S21) for acquiring secondary-side single-side element current information, and the acquired primary-side total current information and primary-side single-side element current information, Primary-side switching element pair failure detection means (S12 to S17) for detecting a failure of each switching element pair provided in the primary-side switching circuit, the acquired secondary-side total current information and the secondary-side one-side element And a secondary switching element pair failure detecting means (S22 to S27) for detecting a failure of each switching element pair provided in the secondary side switching circuit based on the current information.

  In the present invention, the current flowing in one switching element in each switching element pair, the primary total current flowing between the in-vehicle battery and the primary switching circuit, the in-vehicle electrical device, and the secondary switching circuit By acquiring information representing the secondary-side total current flowing between them, a failure of the switching element in each switching element pair is detected. For example, if both switching elements in the switching element pair are normal, the current flowing through the switching element on one side is half of the total current (primary side total current or secondary side total current). Is equal to the total current, it can be determined that the other switching element of the pair has an off-failure. Further, if the current flowing through the switching element on one side is zero, it can be determined that the switching element has an off failure. Therefore, the number of current acquisition means such as current sensors can be reduced, and implementation can be performed at low cost. The primary-side total current information and the secondary-side total current information may be acquired from, for example, the current value detected on the vehicle-mounted electrical device side or the control command value without being directly detected by the current sensor. It may be.

  Another feature of the present invention is that, when an off-fault of one switching element in the switching element pair is detected by the failure detection means, the fault switching element pair having the switching element in which the fault is detected is turned on. On period ratio changing means for shortening an on period compared to an on period in which a switching element pair in which a failure is not detected and which is alternately turned on / off with the failed switching element pair is turned on ( 140, S31 to S36, S41 to S46).

  When an off-failure of one switching element in the switching element pair is detected, the current flowing through the other switching element of the pair is doubled, and overheating is likely to occur. Therefore, in the present invention, the ON period ratio changing means sets the ON period (ON command period) in which the fault switching element pair having the switching element in which the fault is detected to the ON state by the switching element pair in which no fault is detected. Therefore, the switching element pair that is alternately turned on and off alternately with the faulty switching element pair is shortened compared to the on period in which the pair is turned on. Therefore, the period during which current flows through the switching elements on the normal side in the failure switching element pair is shortened, and overheating of the switching elements can be suppressed.

  Another feature of the present invention resides in that an operation limiting means (74) for limiting the operation of the in-vehicle electric device based on the failure of the switching element pair detected by the failure detection means.

  In the present invention, when a failure of the switching element pair is detected, the operation restricting means restricts the operation of the in-vehicle electric device as compared with the case where no failure is detected. Therefore, the current flowing through the DC voltage converter provided between the in-vehicle battery and the in-vehicle electric device is reduced, and the current flowing through one normal switching element in the faulty switching element pair can be reduced. Therefore, it is possible to prevent overheating damage of each switching circuit.

  Another feature of the present invention is that the in-vehicle electric device includes an electric motor (40), and the operation limiting means lowers an upper limit value of a current flowing through the electric motor (S61 to S63), or The control amount of the electric motor is reduced and corrected (S53 to S54).

  In the present invention, the on-vehicle electric device includes an electric motor. When the failure of the switching element pair is detected, the operation limiting means lowers the upper limit value of the current flowing through the electric motor or corrects the control amount of the electric motor to be lower than when no failure is detected. . Therefore, when a failure of the switching element pair is detected, a large current does not flow to the electric motor, and as a result, a current flowing to one normal switching element in the failure switching element pair is reduced. Therefore, it is possible to prevent overheating damage of each switching circuit of the DC voltage converter.

  Another feature of the present invention is that the on-vehicle electric device includes an electric motor (40) that is provided in an electromagnetic suspension device and generates a propulsive force and a damping force for relative movement between the sprung member and the unsprung member. And when the failure detecting means detects a failure of the switching element only in the secondary side switching circuit, the operation limiting means is connected to the in-vehicle device from the electric motor by the electromotive force generated in the electric motor. The operation of the electric motor is limited so that only power regeneration to the battery is limited (S100).

  The vehicle power supply system of the present invention is a system that supplies electric power from an in-vehicle battery to an electric motor that constitutes an electromagnetic actuator provided in an electromagnetic suspension device, and regenerates an electromotive force generated by the electric motor to the in-vehicle battery. In the electromagnetic suspension device, the power output from the in-vehicle battery is converted into a predetermined voltage by the operation of the primary side switching circuit of the DC voltage converter and supplied to the electric motor, whereby the sprung member (vehicle body) and the unsprung portion Propulsive force for relative movement with the member (wheel) is generated. In addition, when the sprung member and the unsprung member are moved by an external input and the electric motor is rotated to generate an electromotive force, the electromotive force is changed to a predetermined voltage by the operation of the secondary side switching circuit of the DC voltage converter. A damping force is generated by converting and regenerating the vehicle-mounted battery.

  Therefore, when a failure of the switching element pair in the secondary side switching circuit is detected, heat generation of the secondary side switching circuit becomes a problem during power regeneration from the electric motor to the in-vehicle battery. Therefore, in the present invention, the operation restricting means is configured so that, when a failure of the switching element pair is detected only in the secondary side switching circuit, only the electric power regeneration from the electric motor to the in-vehicle battery is restricted. Limit operation. Thereby, the overheating damage of the secondary side switching circuit is prevented.

  In this case, since the primary side switching circuit is not out of order, there is no fear of overheating even if the power supply from the in-vehicle battery to the electric motor is not limited. Therefore, the operation limiting means does not limit the operation of the electric motor when supplying electric power from the in-vehicle battery to the electric motor (it is not limited as compared with the normal time). Thereby, in the electromagnetic suspension device, an appropriate driving force can be generated.

  For example, the operation limiting unit includes a status determination unit that determines whether power is being regenerated from the electric motor to the in-vehicle battery, and based on the power supply status determined by the status determination unit, What is necessary is just to restrict | limit the action | operation of an electric motor at the time of electric power regeneration.

  Another feature of the present invention is that the on-vehicle electric device includes an electric motor (40) that is provided in an electromagnetic suspension device and generates a propulsive force and a damping force for relative movement between the sprung member and the unsprung member. The operation restricting means restricts only power supply from the in-vehicle battery to the electric motor when a failure of the switching element pair is detected only in the primary side switching circuit by the failure detecting means. Thus, the operation of the electric motor is limited (S90).

  In the present invention, when a failure of the switching element pair in the primary side switching circuit is detected, heat generation of the primary side switching circuit becomes a problem when power is supplied from the in-vehicle battery to the electric motor. Therefore, when the failure of the switching element pair is detected only in the primary side switching circuit, the operation limiting unit limits the operation of the electric motor so that only the power supply from the in-vehicle battery to the electric motor is limited. Thereby, the overheating damage of the primary side switching circuit is prevented.

  In this case, since the secondary side switching circuit is not out of order, there is no fear of overheating even if power regeneration from the electric motor to the in-vehicle battery is not limited. Therefore, the operation limiting means does not limit the operation of the electric motor during power regeneration from the electric motor to the in-vehicle battery (it is not limited as compared with the normal time). Thereby, in an electromagnetic suspension device, an appropriate damping force can be generated.

  For example, the operation limiting unit includes a state determination unit that determines whether or not the electric motor is in a state of being supplied with power from the in-vehicle battery, and is electrically operated from the in-vehicle battery based on the power supply status determined by the state determination unit. What is necessary is just to restrict | limit the action | operation of an electric motor at the time of the electric power supply to a motor.

  Another feature of the present invention is that when the electric power regenerated from the electric motor to the in-vehicle battery exceeds a set threshold (Wref) due to the electromotive force generated in the electric motor, the phases of the electric motor are short-circuited. An interphase short-circuit means (S106 to S109) for disabling power regeneration is provided, and the operation restricting means is to restrict the power regeneration by lowering the setting threshold (S101).

  When the electric motor is rotated by an external force, it generates an electromotive force, and the electromotive force is regenerated to the in-vehicle battery. In this case, if the regenerative power is large, the load on the motor drive circuit and the in-vehicle battery increases, so the interphase short-circuit means shorts between the energization terminals of the electric motor when the regenerative power exceeds the set threshold value, In order to prevent the electromotive force from being supplied to the outside, a reflux current is allowed to flow.

  When the failure of the switching element pair of the secondary side switching circuit is detected, the operation limiting unit lowers the setting threshold value, which is a threshold value for the regenerative power at which the phase short-circuit unit starts phase-to-phase short-circuiting, from a normal level. As a result, when an electromotive force is generated in the electric motor, an interphase short circuit is performed before the electromotive force becomes too large, and power regeneration from the electric motor to the in-vehicle battery is limited. As a result, overheating damage of the secondary side switching circuit is prevented.

  In the above description, in order to help the understanding of the invention, the reference numerals used in the embodiments are attached to the configuration of the invention corresponding to the embodiments in parentheses. It is not intended to be limited to the embodiment defined by.

It is a schematic block diagram showing the electric power supply system of the electromagnetic suspension apparatus which concerns on embodiment of this invention. It is sectional drawing showing schematic structure of a suspension main body. It is a schematic block diagram showing the control system of an electromagnetic suspension apparatus. It is a schematic circuit block diagram of a DC / DC converter. It is a flowchart showing a primary side switching circuit failure detection routine. It is a flowchart showing a secondary side switching circuit failure detection routine. It is a flowchart showing a primary side ON period ratio change control routine. It is a flowchart showing a secondary ON period ratio change control routine. It is a graph showing the change of ratio of the ON period of a 1st electricity supply path, and the ON period of a 2nd electricity supply path. It is a flowchart showing a target motor force correction routine. It is a flowchart showing a target motor force upper limit limiting routine. It is a flowchart showing an upper limit current setting routine. It is a flowchart showing a target motor force correction routine. It is a flowchart showing a power consumption restriction control routine. It is a flowchart showing an electric power regeneration restriction control routine. It is a flowchart showing an electric power regeneration restriction control routine. It is a graph showing a regeneration area | region and a consumption area | region.

  Hereinafter, a vehicle power supply system according to an embodiment of the present invention will be described. In this embodiment, a power supply system for an electromagnetic suspension device will be described. The vehicle provided with the power supply system of the electromagnetic suspension device in the present embodiment is a hybrid vehicle. In the case of a hybrid vehicle, as a vehicle-mounted power source, a high voltage battery (referred to as a main engine battery) as a power source for a main motor that is an electric actuator for driving the vehicle and a low voltage battery (referred to as an auxiliary battery) used for general vehicle loads. And. In the present embodiment, a system for supplying electric power to the electromagnetic suspension device using a high voltage battery used in a hybrid system is configured.

  FIG. 1 is a schematic configuration diagram illustrating a power supply system of an electromagnetic suspension device according to the present embodiment. The electromagnetic suspension apparatus includes four sets of suspension bodies 10 (a right front wheel suspension body 10FR, a left front wheel suspension body 10FL, a right rear wheel suspension body 10RR, a left rear wheel suspension body 10RL), and a motor drive unit corresponding to each suspension body 10. 50 (right front wheel drive unit 50FR, left front wheel drive unit 50FL, right rear wheel drive unit 50RR, left rear wheel drive unit 50RL) and a suspension control device 70. Four sets of suspension bodies 10FR, 10FL, 10RR, 10RL are provided between the wheels WFR, WFL, WRR, WRL and the vehicle body B, respectively.

  Each motor drive unit 50 is connected to the high voltage battery 200 via a DC / DC converter 100 which is a DC voltage converter. Therefore, the power supply system of the present embodiment includes the electromagnetic suspension device, the DC / DC converter 100, and the high voltage battery 200 as main parts.

  Hereinafter, the four suspension bodies 10FL, 10FR, 10RL, and 10RR are referred to as the suspension body 10 except for the case of distinguishing front and rear and left and right, and the drive units 50FL, 50FR, 50RL, and 50RR are distinguished from front, rear, left, and right. Is referred to as a motor EDU50, and the wheels WFL, WFR, WRL, and WRR are referred to as wheels W except for the case where front, rear, left and right are distinguished. The suspension control device 70 is referred to as a suspension ECU 70.

  FIG. 2 is a partial schematic cross-sectional view of the suspension body 10. As illustrated, the suspension body 10 includes an air spring device 20 and an electromagnetic actuator 30. The air spring device 20 is provided between the lower arm LA that supports the wheel W and the vehicle body B, absorbs the impact received from the road surface using the elasticity (compressibility) of the air, enhances the ride comfort, and reduces the weight of the vehicle body B. Support elastically. The side supported by the air spring device 20, that is, the member on the vehicle body B side is a sprung member, and the side that supports the air spring device 20, that is, the member on the wheel W side is an unsprung member. The electromagnetic actuator 30 generates not only a damping force but also a propulsive force with respect to the vertical vibration of the air spring device 20, and is provided in parallel with the air spring device 20 between the unsprung member and the sprung member.

  The electromagnetic actuator 30 includes an outer cylinder 31 and an inner cylinder 32 that are arranged coaxially, a ball screw mechanism 35 provided inside the inner cylinder 32, and an electric motor 40 that operates the ball screw mechanism 35. In the present embodiment, a three-phase DC brushless motor is used as the electric motor 40.

  The outer cylinder 31 and the inner cylinder 32 are constituted by coaxial different diameter pipes, and the outer cylinder 31 is provided on the outer periphery of the inner cylinder 32 so as to be slidable in the axial direction. In the figure, reference numerals 33 and 34 denote bearings that slidably support the inner cylinder 32 in the outer cylinder 31.

  The ball screw mechanism 35 includes a ball screw 36 that is rotated by the rotating operation of the electric motor 40, and a ball screw nut 39 having a female screw portion 38 that is screwed into a male screw portion 37 formed on the ball screw 36. The ball screw nut 39 is restricted so as not to rotate by a non-illustrated detent. Therefore, in this ball screw mechanism 35, the rotational motion of the ball screw 36 is converted into the linear motion in the vertical axis direction of the ball screw nut 39, and conversely, the linear motion in the vertical axis direction of the ball screw nut 39 is converted into the rotational motion of the ball screw 36. Is done.

  The lower end of the ball screw nut 39 is fixed to the bottom surface of the outer cylinder 31. The upper end of the inner cylinder 32 is fixed to the mounting plate 41. The mounting plate 41 is fixed to the motor casing 42 of the electric motor 40, and the ball screw 36 is inserted through a through hole 43 formed in the center thereof. The ball screw 36 is coupled to the motor shaft in the motor casing 42 and is rotatably supported by a bearing 44 in the inner cylinder 32.

  In the electromagnetic actuator 30, when the electric motor 40 is rotated by power supply from the high voltage battery 200, the ball screw 36 connected to the motor shaft rotates. As the ball screw 36 rotates, the ball screw nut 39 moves in the axial direction. As the ball screw nut 39 moves in the axial direction, the outer cylinder 31 is pushed down or pulled up. This changes the relative distance between the sprung member and the unsprung member. In this way, the electric motor 40 expands and contracts the ball screw mechanism 35 by supplying power from the high voltage battery 200, and generates a propulsive force for relative movement between the sprung member and the unsprung member. This propulsive force is controlled, for example, so as to improve riding comfort.

  When an external force (such as road surface input) is applied to the suspension body 10, this external force acts on the outer cylinder 31, and the motion of the outer cylinder 31 is transmitted to the ball screw nut 39. As a result, the ball screw nut 39 moves in the axial direction, and the ball screw 36 rotates. The electric motor 40 is rotated by the rotation of the ball screw 36. At this time, the electric motor 40 acts as a generator by generating an induced electromotive force in the electromagnetic coil when the magnetic flux of a permanent magnet (not shown) provided in the rotor crosses the electromagnetic coil provided in the stator, and acts as a generator. A resistance force (damping force) against the relative movement between the spring and the unsprung member is generated. Thereby, the relative vibration between the sprung member and the unsprung member is suppressed. In this case, a regenerative current flows through the high voltage battery 200 due to the induced electromotive force generated by the electric motor 40.

  The air spring device 20 is provided on the outer periphery of the electromagnetic actuator 30, and includes a cylindrical upper case 21 that surrounds the outer periphery of the motor casing 42, a lower case 22 that surrounds the outer peripheral surface of the outer cylinder 31, and both cases 21 and 22. A diaphragm 23 mainly composed of rubber that connects the two in an airtight state. These cases 21 and 22 and the diaphragm 23 form an air chamber 24 on the outer periphery of the outer cylinder 31, the inner cylinder 32, and the motor casing 42. The upper case 21 and the lower case 22 are hermetically welded and fixed to the outer peripheral surfaces of the motor casing 42 and the outer cylinder 31, respectively, so that the air chamber 24 is hermetically sealed.

  The upper case 21 is provided with a nozzle 25 as a supply / exhaust port for supplying air into the air chamber 24 and discharging air from the air chamber 24. A supply / discharge device (not shown) is connected to the nozzle 25, and the air pressure in the air chamber 24 is adjusted by supply / exhaust from the nozzle 25.

  The suspension body 10 configured in this manner is attached to the vehicle body B via the upper support 26 made of an elastic material on the upper surface of the upper case 21.

  The motor EDU 50 is provided in the vicinity of each suspension body 10FL, 10FR, 10RL, 10RR, and is communicably connected to the suspension ECU 70 by CAN communication. The control signal output from the suspension ECU 70 is input, and the motor EDU 50 is input according to the control signal. The electric motor 40 is driven and controlled so that the target motor force is generated. As shown in FIG. 3, the motor EDU 50 includes a three-phase inverter 51 that is a motor drive circuit, and a motor control unit 52 that includes a microcomputer as a main part. The motor control unit 52 generates a PWM control signal based on the control signal output from the suspension ECU 70, and outputs the PWM control signal to the three-phase inverter 51.

  The three-phase inverter 51 includes three switching elements S1, S2, S3 constituting the upper arm circuit and three switching elements S4, S5, S6 constituting the lower arm circuit connected in series, and the switching element S1 The motor drive lines L1, L2, and L3 are drawn from between -S4, between switching elements S2-S5, and between switching elements S3-S6. The motor drive lines L1, L2, and L3 are connected to the U-phase terminal, V-phase terminal, and W-phase terminal of the electric motor 40.

  The three-phase inverter 51 is provided with a current sensor 53 that individually detects currents flowing in the U phase, V phase, and W phase, and a voltage sensor 54 that detects voltages of the U phase, V phase, and W phase. ing. The current sensor 53 outputs motor currents iu, iv, iw representing these detected three-phase current values (collectively referred to as motor current iuvw) to the motor control unit 52. The voltage sensor 54 outputs motor voltages Vu, Vv, and Vw representing these detected three-phase voltage values (collectively referred to as motor voltage Vuvw) to the motor control unit 52.

  Three-phase inverter 51 is connected to the secondary side of DC / DC converter 100. As will be described later, the DC / DC converter 100 not only steps down the output of the high voltage battery 200 and supplies it to the four sets of three-phase inverters 51, but also boosts the electromotive force generated by the electric motor 40 to increase the voltage of the high voltage battery 200. This is a bidirectional DC voltage converter that has a function of regenerating the power.

The motor control unit 52 applies the target motor force to the electric motor 40 based on a control control signal representing a target motor force fmotor ^* (described later) output from the suspension ECU 70 and a motor current iuvw detected by the current sensor 53. A PWM control signal in which the duty ratio is set so that a current corresponding to fmotor ^* flows is generated and output to the three-phase inverter 51. As a result, the duty ratio of the switching elements S1 to S6 is controlled, a current corresponding to the target motor force fmotor ^* flows to the electric motor 40, and the electric motor 40 generates the target motor force. In this case, the state where the electric power of the high voltage battery 200 is supplied to the three-phase inverter 51 via the DC / DC converter 100 and the electromotive force generated by the electric motor 40 is regenerated to the high voltage battery 200 via the DC / DC converter 100. In any state, the force generated by the electric motor 40 is controlled to the target motor force fmotor ^* by the duty ratio control of the switching elements S1 to S6 of the three-phase inverter 51.

  The motor EDU 50 is provided with an interphase opening relay unit 55. The phase opening relay unit 55 is provided with phase opening relays R1, R2, and R3 on the motor drive lines L1, L2, and L3, respectively. Each of the relays R1, R2, and R3 is switched to an on state (closed) or an off state (open) by a relay drive signal output from the motor control unit 52.

  In the present embodiment, a high voltage battery 200 having a rated voltage of 288 V is used. A high voltage power supply line 201 is connected to the + terminal of the high voltage battery 200, and a ground line 202 is connected to the − terminal. The primary side of the DC / DC converter 100 is connected to the high voltage battery 200 via the high voltage power line 201 and the ground line 202. The secondary side of the DC / DC converter 100 is connected to the three-phase inverter 51 of the motor EDU 50 via a step-down power supply line 203 and a ground line 204. The DC / DC converter 100 steps down the output voltage (288V) of the high voltage battery 200 to 46V, for example, and supplies the reduced power to the three-phase inverter 51 of each motor EDU50. Although not shown in FIGS. 3 and 4, four motors EDU 50 are connected in parallel to the secondary side of the DC / DC converter 100 through a step-down power supply line 203 and a ground line 204. Has been.

The suspension ECU 70 includes a microcomputer as a main part, and is communicably connected to the four motors EDU 50 and the DC / DC converter 100 by CAN communication. The suspension ECU 70 individually calculates the control amount (target motor force fmotor ^* ) of the electric motor 40 for four wheels based on the vehicle state, and commands the calculated control amount to each motor EDU 50. Since the control amount calculation method is the same for all four wheels, only one wheel will be described here.

The suspension ECU 70 is connected to a sprung acceleration sensor 61, a sprung acceleration sensor 62, and a stroke sensor 63 provided at positions (each wheel position) where the suspension main bodies 10 are attached. Sprung acceleration sensor 61 is provided on the sprung member, detects the acceleration along the vertical direction at each wheel position of the sprung member (sprung vertical acceleration), a signal indicative of the sensed sprung mass vertical accelerations G ₂ Is output. Unsprung acceleration sensor 62 is provided on the unsprung member, such as a lower arm, to detect acceleration along a vertical direction of the unsprung member (unsprung vertical acceleration), the detection signal representing the unsprung vertical acceleration G ₁ Is output. Stroke sensor 63, the stroke displacement amount of the suspension body 10 (the amount of change in distance between the sprung member and the unsprung member, i.e., the amount of expansion and contraction of the electromagnetic actuator 30) is detected, detecting that represents the stroke displacement amount x _S Output a signal.

  Further, a lateral acceleration sensor 64 is connected to the suspension ECU 70. The lateral acceleration sensor 64 detects the lateral acceleration generated in the vehicle body and outputs a detection signal representing the lateral acceleration Gy.

  Next, processing performed by the suspension ECU 70 will be described. The upper part of FIG. 3 is a functional block diagram showing a control process performed by the microcomputer in the suspension ECU 70. Each functional unit is realized by repeatedly executing a control program stored in the ROM of the microcomputer at a predetermined calculation cycle. The suspension ECU 70 includes a vibration damping control force calculation unit 71, a roll suppression control force calculation unit 72, a target motor force calculation unit 73, and a correction calculation unit 74.

Vibration damping control force calculating section 71 receives the detection signal output from the sprung acceleration sensor 61, by integrating the sprung vertical acceleration G ₂ at the time, a velocity along the vertical direction of the sprung member spring _'calculated and the sprung mass vertical velocity x _2' on vertical velocity x ₂ by multiplying the preset spring gain C _{2 (corresponding} to the attenuation coefficient), so as to damp the vibration of the sprung member The sprung damping control force (C ₂ · x ₂ ′) acting on is calculated. Also, enter the detection signal output from the unsprung acceleration sensor 62, by integrating the unsprung vertical acceleration G ₁ in time, the unsprung vertical velocity x _{1 'is} a velocity along the vertical direction of the unsprung member An unsprung damping control force that acts to attenuate the vibration of the unsprung member by calculating and multiplying the unsprung vertical speed x ₁ ′ by a preset unsprung gain C ₁ (corresponding to a damping coefficient). (C ₁ · x ₁ ′) is calculated. The vibration damping control force calculation unit 71 subtracts the unsprung damping control force (C ₁ · x ₁ ′) from the unsprung damping control force (C ₂ · x ₂ ′) as shown in the following equation. The force fv is calculated.
fv = C ₂ · x ₂ '-C ₁ · x ₁ '

  This vibration damping control force fv calculates the force required to attenuate the vibration of the sprung member and the unsprung member by control based on the skyhook damper theory and control based on the pseudo groundhook theory. It is a thing. The vibration damping control force calculation unit 71 outputs the calculated vibration damping control force fv to the target motor force calculation unit 73. In this case, the vibration damping control force fv is set in the direction (contraction / extension) in which the electromagnetic actuator 30 is operated by the sign (positive / negative) of the value. In the above calculation, the detection signals output from the sprung acceleration sensor 61 and the unsprung acceleration sensor 62 may be subjected to low-pass filter processing to remove high frequency components.

The roll suppression control force calculator 72 receives the detection signal output from the lateral acceleration sensor 64, and multiplies the lateral acceleration Gy by a preset roll gain Kro as shown in the following equation to roll control suppression control force fro. And the calculated roll suppression control force fro is output to the target motor force calculation unit 73.
fro = Kro ・ Gy

  When the vehicle is turning, the relative distance between the sprung member on the turning inner ring side and the unsprung member is increased by the roll moment, and the relative distance between the sprung member on the turning outer ring side and the unsprung member is reduced. Therefore, the roll suppression control force calculation unit 72 suppresses the expansion of the relative distance between the sprung member on the turning inner ring side and the unsprung member, and reduces the relative distance between the sprung member on the turning outer ring side and the unsprung member. The force generated by the electromagnetic actuator 30 is calculated to be suppressed as shown in the above equation. Accordingly, the roll suppression control force fro generated by the electromagnetic actuator 30 on the inner turning wheel side and the roll suppression control force fro generated by the electromagnetic actuator 30 on the outer turning wheel side have opposite directions (positive and negative). The lateral acceleration generated in the vehicle body may be estimated based on the steering angle and the vehicle speed.

The target motor force calculation unit 73 adds the vibration damping control force fv output from the vibration damping control force calculation unit 71 and the roll suppression control force fro output from the roll suppression control force calculation unit 72 to thereby add a spring. A target motor force fmotor ^* which is a necessary acting force to be applied between the upper member and the unsprung member is calculated.
fmotor ^* = fv + fro

The target motor force calculation unit 73 outputs the calculated target motor force fmotor ^* to the correction calculation unit 74. The correction calculation unit 74 receives a failure diagnosis signal from the DC / DC converter 100, and when the failure diagnosis signal is a signal indicating that a failure is detected in the DC / DC converter 100, the target motor force f motor ^* Is corrected, and the corrected control amount is replaced with a new target motor force fmotor ^* for output. When the failure diagnosis signal is a signal indicating that no failure is detected in the DC / DC converter 100, the target motor force fmotor ^* input from the target motor force calculation unit 73 is output as it is without correction. . The correction process by the correction calculation unit 74 will be described later together with the failure detection process of the DC / DC converter 100.

The correction calculation unit 74 outputs a control signal corresponding to the target motor force fmotor ^* to the motor EDU50. As a result, in the motor EDU 50, the duty ratio of the switching elements S1 to S4 of the three-phase inverter 51 is controlled, whereby a current corresponding to the target motor force fmotor ^* flows to the electric motor 40, and the electric motor 40 is set to the target. Motor force fmotor ^* is generated. In this case, when the direction in which the suspension body 10 is actually expanded and contracted and the control direction of the electromagnetic actuator 30 represented by the target motor force f motor ^* are the same, the high-voltage battery is connected via the DC / DC converter 100. Electric power is supplied from 200 to the motor EDU 50 and the electric motor 40 is driven to generate a propulsive force. On the other hand, when the direction in which the suspension body 10 is actually expanded and contracted and the control direction of the electromagnetic actuator 30 represented by the target motor force fmotor ^* are reversed, the electromotive force generated by the electric motor 40 is DC / It is regenerated to the high voltage battery 200 via the DC converter 100. As a result, the electric motor 40 generates a braking force, that is, a damping force against the stroke motion of the suspension body 10 by causing a regenerative current to flow through the motor coil.

FIG. 17 shows the relationship between the stroke speed of the suspension body 10 and the target motor force fmotor ^* . In FIG. 17, a thinly painted area is an area where power is regenerated from the electric motor 40 to the high voltage battery 200. For example, the regenerative region 1 is a region where the target motor force f motor ^* is set in a direction in which the suspension main body 10 is not expanded when the suspension main body 10 is expanding, and the regenerative region 2 is when the suspension main body 10 is contracting. In addition, the target motor force fmotor ^* is set in a direction in which the motor is not contracted. The consumption area 1 is an area where the target motor force fmotor ^* is set in the contracting direction when the suspension body 10 is contracting, and the consumption area 2 is when the suspension body 10 is extending. The target motor force fmotor ^* is set in the extending direction. In the figure, a straight line A represents a motor short-circuit characteristic line, and represents a load characteristic generated when each phase of the electric motor 40 is short-circuited. Therefore, the damping force that can be generated by power regeneration of the electric motor 40 is in a range between the motor short-circuit characteristic line A and the horizontal axis. When the electromagnetic actuator 30 is actively controlled, generally, the target motor force fmotor ^* corresponding to the stroke speed is set along the locus B in the figure.

  Next, the DC / DC converter 100 will be described. When the electromagnetic actuator 30 is actively controlled as described above, for example, when the vehicle travels on an uneven road surface for a long time, the electromagnetic actuator 30 continues to expand and contract, so that a large current flows in both directions in the DC / DC converter 100. Time flows. For this reason, there is a possibility that the heat generation of the DC / DC converter 100 increases and the DC / DC converter 100 is damaged by overheating. If the active control of the electromagnetic actuator 30 is interrupted according to the heat generation state of the DC / DC converter 100, the DC / DC converter 100 can be prevented from overheating damage, but the vehicle performance is sacrificed. Therefore, the DC / DC converter 100 of the present embodiment employs a circuit configuration that solves these problems.

  As shown in FIG. 4, the DC / DC converter 100 includes a transformer 130 including a primary side winding 131 and a secondary side winding 132, and a primary side switching circuit connected to the primary side winding 131. 110, a full-bridge type DC-DC voltage converter including a secondary side switching circuit 120 connected to the secondary side winding 132 and a switch control unit 140. The primary side switching circuit 110 is connected to the high voltage battery 200 via the high voltage power supply line 201 and the ground line 202, and the current flows from the high voltage battery 200 to the primary side winding 131 alternately in the forward and reverse directions. The AC power supplied from the secondary winding 132 is rectified to DC. The secondary side switching circuit 120 is connected to the three-phase inverter 51 via the step-down power supply line 203 and the ground line 204, and rectifies AC power supplied from the primary side winding 131 into DC, while at the time of power regeneration. A current flows alternately from the three-phase inverter 51 to the secondary winding 132 in the forward and reverse directions.

  The primary side switching circuit 110 includes four switching element pairs (a first switching element pair 111, a second switching element pair 112, a third switching element pair 113, a fourth switching element pair) in which two switching elements S are connected in parallel. 114). In the present embodiment, MOS-FETs are used as the two switching elements S constituting each of the switching element pairs 111 to 114, but other switching elements can also be used.

  The first switching element pair 111 and the second switching element pair 112 are connected in series, and the high-voltage power supply line 201 and the ground line 202 are electrically connected by the circuit connected in series. The third switching element pair 113 and the fourth switching element pair 114 are also connected in series, and the high voltage power supply line 201 and the ground line 202 are electrically connected by the series connected circuit. One end of the primary side winding 131 of the transformer 130 is connected to a connection portion between the first switching element pair 111 and the second switching element pair 112, and the third switching element pair 113 and the fourth switching element pair 114 are connected to each other. The other end of the primary winding 131 is connected to the connection portion.

  A parasitic diode is incorporated in the switching element S in each of the switching element pairs 111 to 114. In each of the switching element pairs 111 to 114, the parasitic diode is in a direction in which a current flow from the high-voltage power supply line 201 to the ground line 202 is blocked and a current flow from the ground line 202 to the high-voltage power supply line 201 is allowed. Each switching element S is connected and provided. A diode other than the parasitic diode may be provided in parallel to each switching element S in the above direction.

  PWM control signals output from the switch control unit 140 are independently input to the switching element pairs 111 to 114, respectively. In this case, a common PWM control signal is input to the two switching elements S constituting each switching element pair 111 to 114. Accordingly, the two switching elements S forming a pair are configured to be turned on / off simultaneously.

  The primary side switching circuit 110 includes current sensors 151, 152, 153, and 154 that detect currents flowing through the switching elements S on one side of the switching element pairs 111, 112, 113, and 114. The current sensors 151 to 154 output a detection signal representing the detected current value to the switch control unit 140. Hereinafter, the current value detected by the current sensor 151 provided in the first switching element pair 111 is referred to as a first element current i11, and the current value detected by the current sensor 152 provided in the second switching element pair 112 is referred to as a first element current i11. The current value detected by the current sensor 153 provided in the third switching element pair 113 is referred to as a second element current i12 and is referred to as a third element current i13, and the current sensor 154 provided in the fourth switching element pair 114. The detected current value is called a fourth element current i14.

  In the primary side switching circuit 110, a choke coil 181 is provided on the high voltage power supply line 201 on the high voltage battery 200 side relative to the connection position with the first switching element pair 111. The high voltage power supply line 201 is provided with a primary side voltage sensor 155 and a primary side current sensor 156. The primary side voltage sensor 155 detects the potential of the high voltage power supply line 201 with respect to the ground line 202 and outputs the detection signal to the switch control unit 140. The voltage value detected by the primary side voltage sensor 155 is referred to as a primary side voltage V1. Primary side current sensor 156 detects a current flowing between high voltage battery 200 and primary side winding 131 of DC / DC converter 100 and outputs the detection signal to switch control unit 140. The current value detected by the primary side current sensor 156 is referred to as a primary side total current i1.

  The secondary side switching circuit 120 includes two switching element pairs (a first switching element pair 121 and a second switching element pair 122) in which two switching elements S are connected in parallel. As the switching element S of each switching element pair 121, 122, a MOS-FET is used in the same manner as the switching element S of the primary side switching circuit 110, but other switching elements can also be used.

  The first switching element pair 121 electrically connects one end of the secondary side winding 132 of the transformer 130 and the ground line 204, and the second switching element pair 122 includes the secondary side winding 132 of the transformer 130. The other end and the ground line 204 are electrically connected. An intermediate point of the secondary winding 132 of the transformer 130 is connected to the step-down power supply line 203. In each switching element pair 121, 122, the parasitic diode is in a direction that prevents a current flow from the step-down power supply line 203 to the ground line 204 and allows a current flow from the ground line 204 to the step-down power supply line 203. Are connected to each switching element S. In the secondary side winding 132 of the transformer 130, when distinguishing a portion from the intermediate point to one end and a portion from the intermediate point to the other end, the former is called a secondary side winding 132a, and the latter is This is called a secondary winding 132b.

  Each switching element pair 121 and 122 is independently input with a PWM control signal output from the switch control unit 140. In this case, a common PWM control signal is input to the two switching elements S constituting each pair of switching elements 121 and 122. Accordingly, the two switching elements S forming a pair are configured to be turned on / off simultaneously.

  The secondary side switching circuit 120 includes current sensors 161 and 162 that detect a current flowing through the switching element S on one side in each switching element pair 121 and 122. The current sensors 161 and 162 output a detection signal representing the detected current value to the switch control unit 140. Hereinafter, a current value detected by the current sensor 161 provided in the first switching element pair 121 is referred to as a first element current i21, and a current value detected by the current sensor 162 provided in the second switching element pair 122 is referred to as a first element current i21. This is called a second element current i22.

  In the secondary side switching circuit 120, a choke coil 182 is provided on the step-down power supply line 203, and a capacitor 183 is provided between the step-down power supply line 203 and the ground line 204 on the motor EDU 50 side of the choke coil 182. Is provided. The step-down power supply line 203 is provided with a secondary side voltage sensor 157 and a secondary side current sensor 158. The secondary side voltage sensor 157 detects the potential of the step-down power supply line 203 with respect to the ground line 204 and outputs the detection signal to the switch control unit 140. The voltage value detected by the secondary side voltage sensor 157 is referred to as a secondary side voltage V2. Secondary current sensor 158 detects a current flowing between motor EDU 50 and secondary winding 132 of DC / DC converter 100, and outputs a detection signal to switch control unit 140. The current value detected by the secondary side current sensor 158 is referred to as a secondary side total current i2.

  A power consuming circuit 190 is provided between the secondary side switching circuit 120 and the motor EDU 50. In this power consumption circuit 190, a resistance element 191 and a switching element 192 are connected in series, and the step-down power supply line 203 and the ground line 204 are electrically connected by the circuit connected in series. The switching element 192 is switched on / off by a control signal output from the switch controller 140 and is normally maintained in the off state, but the regenerative power output from the motor EDU 50 to the DC / DC converter 100 side. Is larger than the set value, the switch control unit 140 switches it to the on state. Thereby, a part of the regenerative power is consumed as heat generated by the resistance element 191, and the regenerative current flowing through the DC / DC converter 100 and the high voltage battery 200 is reduced. Note that the power consumption circuit 190 is not necessarily provided.

  The switch control unit 140 includes a microcomputer and a switch drive circuit as main parts. The switch control unit 140 operates the primary side switching circuit 110 when the power of the high voltage battery 200 is stepped down and supplied to the motor EDU 50. In this case, the switch control unit 140 turns on the first switching element pair 111 and the fourth switching element pair 114 and turns off the second switching element pair 112 and the third switching element pair 113 (hereinafter referred to as the first switching element pair 114). A state in which the first switching element pair 111 and the fourth switching element pair 114 are turned off, and the second switching element pair 112 and the third switching element pair 113 are turned on (hereinafter referred to as a second conduction path). Are alternately switched, so that a current flows through the primary winding 131 alternately in the forward and reverse directions. As a result, a high-frequency AC voltage stepped down in the secondary winding 132 is generated.

  In such a switching operation, the time for forming the first current path and the time for forming the second current path are set to the same length. Accordingly, half of the current flowing through the primary winding 131 flows through the eight switching elements S for the same time.

  When the primary side switching circuit 110 is operated as described above, the switch control unit 140 maintains the two switching element pairs 121 and 122 of the secondary side switching circuit 120 in the off state. When the first energization path is formed in the primary side switching circuit 110, in the secondary side switching circuit 120, a current flows through the parasitic diode of the second switching element pair 122 as shown by the solid line arrow in FIG. A current flows from the power line 203 to the motor EDU 50. Further, when the second energization path is formed in the primary side switching circuit 110, in the secondary side switching circuit 120, a current flows through the parasitic diodes of the first switching element pair 121 as indicated by broken line arrows in FIG. Thus, a current flows from the step-down power supply line 203 to the motor EDU50. As a result, DC power is supplied to the motor EDU50.

  The motor control unit 52 reads the secondary side voltage V2 detected by the secondary side voltage sensor 157, and adjusts the duty ratio of each switching element pair 111 to 114 so that the secondary side voltage V2 becomes the set voltage. To do. When the electric motor 40 acts as a generator due to the expansion and contraction of the electromagnetic actuator 30, the secondary side voltage V2 rises. When the motor control unit 52 detects an increase in the secondary side voltage V2, the motor control unit 52 operates the secondary side switching circuit 120 in order to cause the high voltage battery 200 to regenerate the electromotive force generated in the electric motor 40.

  When operating the secondary side switching circuit 120, the motor control unit 52 stops the operation of the primary side switching circuit 110 and maintains the four switching element pairs 111 to 114 in the OFF state. The motor control unit 52 is in a state where the first switching element pair 121 of the secondary side switching circuit 120 is turned on and the second switching element pair 122 is turned off (referred to as a first regenerative current path), and the first switching element pair 121. Is switched off and the second switching element pair 122 is switched on alternately (referred to as a second regenerative current path). In this case, when the first regenerative current path is formed in the secondary side switching circuit 120, the regenerative current passes from the step-down power supply line 203 through the secondary side winding 132 a of the transformer 130 and the first switching element pair 121. It flows to the ground line 204 (the direction opposite to the broken line arrow in FIG. 4). When the second regenerative current path is formed in the secondary side switching circuit 120, the regenerative current is grounded from the step-down power supply line 203 through the secondary side winding 132b of the transformer 130 and the second switching element pair 122. It flows to the line 204 (the direction opposite to the solid line arrow in FIG. 4).

  As a result, regenerative current flows in the secondary winding 132 alternately in the forward and reverse directions, and a high-frequency AC voltage boosted in the primary winding 131 is generated. In such a switching operation, the time for forming the first regenerative current path and the time for forming the second regenerative current path are set to the same length. Therefore, half of the current flowing through the secondary winding 132 flows through the four switching elements S for the same time.

  According to the DC / DC converter 100 configured as described above, in the primary side switching circuit 110, the current path is distributed into two by the switching element pairs 111 to 114, and in the secondary side switching circuit 120, the switching element pair. In 121 to 122, the current path is distributed into two. For this reason, the current flowing through each switching element S is reduced to half of the current flowing through each of the windings 131 and 132.

  Accordingly, even when the vehicle travels on an uneven road for a long time and the electromagnetic actuator 30 continues to expand and contract, the switching element S can be operated even in a situation where a large current flows through the DC / DC converter 100 in both directions for a long time. Heat generation can be suppressed. As a result, it is not necessary to perform the motor opening process for disconnecting the electric motor 40 from the three-phase inverter 52 and preventing the regenerative current from flowing into the DC / DC converter 100. Therefore, the stopper contact that mechanically restricts the expansion / contraction stroke of the electromagnetic actuator 30 is reduced, and it is possible to prevent a decrease in riding comfort performance and a decrease in durability of the electromagnetic actuator 30. As a result, according to the present embodiment, it is possible to prevent overheating damage of the DC / DC converter 100 without degrading the performance of the electromagnetic suspension device.

  By the way, when the primary side switching circuit 110 and the secondary side switching circuit 120 are configured using the switching element pairs 111 to 114 and 121 to 122, even if one of the paired switching elements S is turned off, The DC / DC converter 100 can continue the voltage conversion operation as it is. However, in such a case, since the current flowing through the other switching element S is doubled compared to the normal time, if the operation is continued as it is, the normal-side switching element S may be damaged due to overheating. In the case where an off failure has occurred even with the other switching element S forming a pair, the DC / DC converter 100 cannot perform an appropriate operation from that point.

  Therefore, the power supply system of the present embodiment responds to the function of detecting the failure of each switching element pair 111 to 114, 121 to 122 in the primary side switching circuit 110 and the secondary side switching circuit 120, and the failure detection. It has a failure handling function. Hereinafter, when the switching element pairs 111 to 114 and 121 to 122 are not individually specified, they are simply referred to as a switching element pair SP.

  First, the failure detection process of the primary side switching circuit 110 will be described. FIG. 5 shows a primary-side switching circuit failure detection routine executed by the microcomputer of the switch control unit 140. This primary side switching circuit failure detection routine is repeatedly executed at a predetermined cycle when the primary side switching circuit 110 is operated to step down the power of the high voltage battery 200 and supply it to the motor EDU 50. First, in step S11, the switch control unit 140 detects the primary-side total current i1 detected by the primary-side current sensor 156 and the four current sensors 151, 152, 153, and 154 provided in the primary-side switching circuit 110. The first element current i11, the second element current i12, the third element current i13, and the fourth element current i14 detected by the above are read. Subsequently, in step S12, the value of the variable n is set to “1”. Subsequently, in step S13, it is determined whether or not the n-th element current i1n is substantially equal to a half value (i1 / 2) of the primary-side total current i1. In this case, since n = 1, it is determined whether or not the first element current i11 is substantially equal to a half value (i1 / 2) of the primary total current i1.

  If the two switching elements S constituting the switching element pair SP are normal, currents having the same current value flow through the two switching elements S. Therefore, the current value detected by the current sensors 151 to 154 is half of the primary total current i1. Further, when one of the two switching elements S constituting the switching element pair SP has an off-failure, no current flows in the switching element S on the failed side, and switching on the non-failed side is performed. The primary total current i1 flows through the element S. Therefore, by detecting the value of the current flowing through the switching element S on one side, it is possible to determine the presence / absence of a failure of each switching element S in the switching element pair SP.

  When the switch control unit 140 determines that the n-th element current i1n is substantially equal to a half value (i1 / 2) of the primary-side total current i1 (S13: Yes), in step S14, the variable n The value is incremented by 1. In step S15, it is determined whether or not the incremented variable n has exceeded “4”. If it does not exceed “4”, the process returns to step S13 and the same processing is performed. Repeat the process. Therefore, regarding the first element current i11 to the fourth element current i14, the determination as to whether or not it is substantially equal to half the value (i1 / 2) of the primary total current i1 is repeated.

  When the n-th element current i1n is not in the vicinity of the half value (i1 / 2) of the primary total current i1 (for example, when i1n = 0 or i1n = i1), step S16 is performed. , It is determined that the n-th switching element pair SP has failed. In this case, when i1n = 0, it is determined that the switching element S on the side where the current sensor is provided is off failure, and that the switching element S on the side where the current sensor is not provided is normal, i1n = In the case of i1, it is determined that the switching element S on the side where the current sensor is provided is normal, and that the switching element S on the side where the current sensor is not provided has an off failure.

  When the switch control unit 140 determines whether or not there is a failure in the four switching element pairs SP, in a subsequent step S17, the switch control unit 140 outputs a failure diagnosis signal representing the failure diagnosis result to the suspension ECU 70, and once ends this routine. This failure diagnosis signal represents the number of switching element pairs SP that have failed in the primary side switching circuit 110, and is a signal representing "0" if normal.

  Note that in any of the primary side switching circuit 110 and the secondary side switching circuit 120, when any one of the switching elements S is on-failed, or the two switching elements S constituting the switching element pair SP are When both of them are off-failed, voltage control of the DC / DC converter 100 cannot be performed properly. Therefore, when the switch control unit 140 detects that the voltage control is disabled, the switch control unit 140 does not execute the primary side switching circuit failure detection routine and the secondary side switching circuit failure detection routine described later. The operations of the primary side switching circuit 110 and the secondary side switching circuit 120 are stopped, and a fail signal is output to the suspension ECU 70. Therefore, regarding the failure detection processing of the DC / DC converter 100 in the present embodiment, an off failure of one switching element S of the switching element pair SP in the primary side switching circuit 110 and the secondary side switching circuit 120 is targeted for detection. .

  When the operation of the DC / DC converter 100 is stopped, for example, a power supply line is connected so that a low voltage battery (not shown), which is a vehicle-mounted battery that supplies power to a normal electric load, and the motor EDU 50 are connected. May be switched.

  Next, failure detection processing of the secondary side switching circuit 120 will be described. FIG. 6 shows a secondary-side switching circuit failure detection routine executed by the microcomputer of the switch control unit 140. This secondary-side switching circuit failure detection routine is repeatedly executed at a predetermined cycle when the secondary-side switching circuit 120 is operated to boost the regenerative power output from the motor EDU 50 and supply it to the high-voltage battery 200. Is done. First, in step S21, the switch control unit 140 is detected by the secondary-side total current i2 detected by the secondary-side current sensor 158 and the two current sensors 161 and 162 provided in the secondary-side switching circuit 120. The first element current i21 and the second element current i22 are read. Subsequently, in step S22, the value of the variable m is set to “1”. Subsequently, in step S23, it is determined whether or not the m-th element current i2m is substantially equal to a half value (i2 / 2) of the secondary-side total current i2. In this case, since m = 1, it is determined whether or not the first element current i21 is substantially equal to half the value (i2 / 2) of the secondary total current i2.

  Also in the secondary side switching circuit 120, if the two switching elements S constituting the switching element pair SP are normal, currents having the same current value flow through the two switching elements S. Therefore, the current value detected by the current sensors 161 and 162 is half of the secondary total current i2. Further, when one of the two switching elements S constituting the switching element pair SP has an off-failure, no current flows in the switching element S on the failed side, and switching on the non-failed side is performed. The secondary total current i2 flows through the element S. Accordingly, by detecting the value of the current flowing through the switching element S on one side, it is possible to determine whether or not the switching element S of the switching element pair SP has a failure.

  When the switch control unit 140 determines that the m-th element current i2m is substantially equal to a half value (i2 / 2) of the secondary-side total current i2 (S23: Yes), in step S24, the switch m 140 The value is incremented by 1, and in step S25, it is determined whether or not the incremented variable m exceeds “2”. If the variable m does not exceed “2”, the process returns to step S23 and the same processing is performed. Repeat the process. Accordingly, a determination is made as to whether or not the second element current i22 is substantially equal to a half value (i2 / 2) of the secondary total current i2.

  When the m-th element current i2m is not in the vicinity of the half value (i2 / 2) of the secondary total current i2 (for example, when i2m = 0 or i2m = i2), in step S26 , It is determined that the m-th switching element pair SP is out of order. In this case, when i2m = 0, it is determined that the switching element S on the side where the current sensor is provided is off failure, and that the switching element S on the side where the current sensor is not provided is normal, i2m = In the case of i2, it is determined that the switching element on the side where the current sensor is provided is normal and the switching element S on the side where the current sensor is not provided is off-failed.

  When the switch control unit 140 determines whether or not there is a failure in the two switching element pairs SP, in subsequent step S27, the switch control unit 140 outputs a failure diagnosis signal representing the failure diagnosis result to the suspension ECU 70, and once ends this routine. This failure diagnosis signal represents the number of switching element pairs SP that have failed in the secondary side switching circuit 120. If the failure diagnosis signal is normal, the failure diagnosis signal is a signal representing "0".

  According to this failure detection process, since the failure of each switching element S can be detected without providing a current sensor for each switching element S, the configuration of the DC / DC converter 100 is not complicated, and is low. It can be implemented at a cost.

  When a failure is detected in the primary side switching circuit 110 or the secondary side switching circuit 120, the switch control unit 140 activates a warning device such as a vehicle warning lamp (not shown) to cause the driver to break down. Inform. Thereby, the driver can arrange vehicle repair at the stage where the switching element S on one side in the switching element pair SP is out of order. For this reason, it is possible to prevent the occurrence of a double failure in which the two switching devices S constituting the switching device pair SP both fail off.

  In the present embodiment, a configuration is adopted in which the number of current sensors is reduced by detecting the current flowing through the switching element S on one side of the switching element pair SP. You may make it detect the electric current which flows into both the switching elements S with a current sensor individually. In this case, the primary side switching circuit 110 or the secondary side switching circuit 120 can determine a failure by comparing current values detected by the current sensors with each other.

The detection of the secondary side total current i2 may be estimated from the target motor force fmotor ^* calculated by the suspension ECU 70, instead of being directly detected by the secondary side current sensor 158. Further, the motor EDU 50 may be estimated from the motor current iuvw detected by the current sensor 53. When the power consumption circuit 190 is operated, the current flowing through the resistance element 191 may be subtracted from the estimated current value. This current can be obtained from the resistance value (known) of the resistance element and the secondary side voltage V2 detected by the secondary side voltage sensor 157.

Similarly, regarding the detection of the primary side total current i1, instead of the direct detection by the primary side current sensor 156, it may be estimated from the target motor force fmotor ^* calculated by the suspension ECU 70, or the motor It may be estimated from the motor current iuvw detected by the current sensor 53 by the EDU 50. In this case, the primary-side total current i1 can be calculated from the estimated value of the secondary-side total current and the transformation ratio of the DC / DC converter 100.

  Next, processing in the DC / DC converter 100 when a failure of the switching element pair SP is detected will be described. FIG. 7 shows a primary on-period ratio change control routine executed by the microcomputer of the switch control unit 140. This primary-side on-period ratio change control routine is repeatedly executed at a predetermined cycle in parallel with the above-described primary-side switching circuit failure detection routine. In the on-period ratio change control routine, the failure of the switching element pair SP means the off-failure of one of the paired switching elements S.

  First, in step S31, the switch control unit 140 determines whether or not a failure of the switching element pair SP in the primary side switching circuit 110 is detected. If no failure has been detected for all four switching element pairs SP, in step S32, as shown in FIG. 9A, the on period of the first energization path and the on period of the second energization path The ratio is the same. That is, a period in which a first current path in which the first switching element pair 111 and the fourth switching element pair 114 are turned on and the second switching element pair 112 and the third switching element pair 113 are turned off is formed, The ratio between the period in which the second energization path in which the switching element pair 111 and the fourth switching element pair 114 are turned off and the second switching element pair 112 and the third switching element pair 113 are turned on is made equal.

  If it is determined “No” in step S31, a failure is detected in at least one of the first switching element pair 111 and the fourth switching element pair 114 in step S33, and the second switching element pair 112 and It is determined whether or not a failure is detected in the third switching element pair 113. When the switching element pair in which the failure is detected is the first switching element pair 111, the fourth switching element pair 114, or both (S33: Yes), the switch control unit 140 determines in step S34. As shown in FIG. 9B, the ON period of the first energization path (the period during which the first switching element pair 111 and the fourth switching element pair 114 are ON) is the ON period of the second energization path (second switching). The period is shorter than the period during which the element pair 112 and the third switching element pair 113 are turned on. That is, the period for forming the first energization path is made shorter than the period for forming the second energization path. For example, 30% of the switching period T is set as the ON period of the first energization path, and 70% of the switching period T is set as the ON period of the second energization path. In this case, the switching cycle T for alternately switching between the ON period of the first energization path and the ON period of the second energization path is the same as the switching period T at the normal time.

  If it is determined “No” in step S33, a failure is detected in at least one of the second switching element pair 112 and the third switching element pair 113 in step S35, and the first switching element pair 111 and It is determined whether or not a failure is detected in the fourth switching element pair 114. When the switching element pair in which the failure is detected is the second switching element pair 112, the third switching element pair 113, or both (S35: Yes), the switch control unit 140 determines in step S36. As shown in FIG. 9C, the ON period of the second energization path is made shorter than the ON period of the first energization path. That is, the period for forming the second energization path is made shorter than the period for forming the first energization path. For example, 70% of the switching period T is set as the ON period of the first energization path, and 30% of the switching period T is set as the ON period of the second energization path. In this case, the switching cycle T for alternately switching between the ON period of the first energization path and the ON period of the second energization path is the same as the switching period T at the normal time.

  When it is determined “No” in step S35, that is, at least one of the first switching element pair 111 and the fourth switching element pair 114, and the second switching element pair 112 and the third switching element pair 113. If at least one of the faults is detected, the process proceeds to step S32, and the ratio of the on period of the first energization path and the on period of the second energization path is made the same.

  When the ratio of the ON period of the first energization path and the ON period of the second energization path is set in steps S32, S34, and S36, the switch control unit 140 once ends the primary-side on period ratio change control routine. Then, the above-described processing is repeated at a predetermined cycle.

  Next, the secondary on-period ratio changing process will be described. FIG. 8 shows a secondary on-period ratio change control routine executed by the microcomputer of the switch control unit 140. This secondary-side on-period ratio change control routine is repeatedly executed at a predetermined cycle in parallel with the above-described secondary-side switching circuit failure detection routine.

  First, in step S41, the switch control unit 140 determines whether a failure of the switching element pair SP in the secondary side switching circuit 120 is detected. If no failure is detected in any of the two switching element pairs SP, in step S42, the ratio between the on period of the first regenerative current path and the on period of the second regenerative current path is made the same. . That is, the period during which the first regenerative current path is formed in which the first switching element pair 121 is turned on and the second switching element pair 122 is turned off, and the first switching element pair 121 is turned off and the second switching element pair 122 is turned on. The ratio with the period in which the second regenerative current path is formed is made equal.

  If it is determined “No” in step S41, it is determined in step S43 whether or not a failure is detected only in the first switching element pair 121. When the switching element pair in which the failure is detected is only the first switching element pair 121 (S43: Yes), the switch control unit 140 determines that the first regenerative current path is turned on (first switching) in step S44. The period during which the element pair 121 is turned on is made shorter than the period during which the second regenerative current path is turned on (the period during which the second switching element pair 122 is turned on). That is, the period for forming the first regeneration energization path is made shorter than the period for forming the second regeneration energization path. For example, 30% of the switching cycle T is set as the ON period of the first regenerative current path, and 70% of the switching cycle T is set as the ON period of the second regenerative current path. In this case, the switching cycle T for alternately switching between the ON period of the first regeneration energization path and the ON period of the second regeneration energization path is the same as the switching period T at normal time.

  If it is determined “No” in step S43, it is determined in step S45 whether or not a failure is detected only in the second switching element pair 122. When the switching element pair in which the failure is detected is only the second switching element pair 122 (S45: Yes), the switch control unit 140 sets the second regeneration energization path on period to the first regeneration in step S46. Shorten compared to the ON period of the current path. That is, the period for forming the second regeneration energization path is made shorter than the period for forming the first regeneration energization path. For example, 70% of the switching cycle T is set as the ON period of the first regenerative current path, and 30% of the switching cycle T is set as the ON period of the second regenerative current path. In this case, the switching cycle T for alternately switching between the ON period of the first regeneration energization path and the ON period of the second regeneration energization path is the same as the switching period T at normal time.

  If “No” is determined in step S45, that is, if a failure is detected in both the first switching element pair 121 and the second switching element pair 122, the process proceeds to step S42. Thus, the ratio between the ON period of the first regenerative current path and the ON period of the second regenerative current path is made the same.

  When the ratio of the ON period of the first regenerative energization path and the ON period of the second regenerative energization path is set in steps S42, S44, and S46, the switch control unit 140 temporarily ends the secondary on-period ratio change control routine. . Then, the above-described processing is repeated at a predetermined cycle.

  Next, the processing of the suspension ECU 70 when a failure of the switching element pair SP is detected will be described. As described above, the switch control unit 140 of the DC / DC converter 100 outputs a failure diagnosis signal to the suspension ECU 70 every time the primary side and secondary side switching circuit failure detection routine is executed. In the suspension ECU 70, a failure diagnosis signal is input to the correction calculation unit 74. The correction calculation unit 74 corrects the target motor force based on the failure diagnosis signal. Hereinafter, the target motor force correction process executed by the correction calculation unit 74 will be described.

  FIG. 10 shows a target motor force correction routine executed by the correction calculation unit 74. The target motor force correction routine is repeatedly executed at a predetermined short cycle. In step S51, the correction calculation unit 74 receives the failure diagnosis signal output from the switch control unit 140 of the DC / DC converter 100. Subsequently, in step S52, the number represented by the failure diagnosis signal of the primary side switching circuit 110 and the number represented by the diagnosis failure signal of the secondary side switching circuit 120 are added to perform switching in the DC / DC converter 100. Calculate the number of failures of the element pair. Subsequently, in step S53, a control gain K corresponding to the number of failures is set. The control gain K is set to “1” (K = 1) when the number of failures is “0”, and is set to a smaller value (0 <K <1) as the number of failures increases. The relationship between the control gain K and the number of failures is stored in advance in the memory of the suspension ECU 70.

Subsequently, in step S54, the correction calculation unit 74 multiplies the target motor force fmotor ^* calculated by the target motor force calculation unit 73 by the control gain K, and uses the multiplication result (K · fmotor ^* ) as a new target motor. Set force fmotor ^* . Therefore, the target motor force fmotor ^* is corrected so as to decrease as the number of failures of the switching element pair SP of the DC / DC converter 100 increases. When calculating the new target motor force fmotor ^* , the correction calculation unit 74 outputs a control signal corresponding to the target motor force fmotor ^* to the motor EDU 50 in step S55, and temporarily ends the target motor force correction routine.

In the DC / DC converter 100, when the switching element S on one side of the switching element pair SP is off-failed, twice the current flows through the other switching element. By executing the routine, the target motor force fmotor ^* is set to a smaller value than in the normal time (normal time), and as a result, the current is limited. As a result, the heat generation of the switching element S is suppressed, and it is possible to avoid as much as possible the problem that both of the paired switching elements S fail and the operation of the DC / DC converter 100 stops.

  According to the power supply system of the electromagnetic suspension device of the present embodiment described above, the switching circuits 110 and 120 of the DC / DC converter 100 are configured by the switching element pair SP, so that overheating damage of the DC / DC converter 100 can be prevented. Therefore, active control by the electromagnetic suspension device can be continued, and proper riding comfort performance and steering stability performance can be maintained, and an increase in the amount per stopper that regulates the suspension stroke can be prevented.

Moreover, even when the switching element S on one side in the switching element pair SP has an off-failure, the failure can be detected. Further, even if the switching element S on one side is in an off-state failure, the target motor force fmotor ^* is corrected to limit the operation of the electric motor 40, so that a large current does not flow through the normal side switching element S. . For this reason, the malfunction that even the switching element S on the normal side fails and the DC / DC converter 100 becomes inoperable can be prevented.

Further, since the target motor force f motor ^* is corrected so as to be smaller than the normal time as the number of failures of the switching element pair SP is larger, the current flowing through the DC / DC converter 100 can be more appropriately limited.

  Moreover, in order to shorten the ON period of the failure switching element pair SP compared to the ON period of the switching element pair SP in which no failure is detected by executing the primary side and secondary side on period ratio change control routine, The period during which current flows through the switching element S on the normal side in the failure switching element pair SP is shortened, and overheating of the switching element S can be further suppressed. For this reason, in the DC / DC converter 100, the heat generation states of the plurality of switching elements S can be balanced, and the load on the specific switching element S does not increase.

  As a result, the performance of the electromagnetic suspension device can be exhibited as much as possible while preventing overheating damage of the DC / DC converter 100.

<Modification 1>
In the target motor force correction routine described above, the target motor force fmotor ^* is corrected by the control gain K. Alternatively, the upper limit value of the target motor force fmotor ^* may be varied. A modification thereof will be described with reference to FIG. FIG. 11 shows a target motor force upper limit limiting routine. In this control routine, steps S61, S62, and S63 are performed instead of steps S53 and S54 in the target motor force correction routine described above. Hereinafter, the same processing as that in the target motor force correction routine is denoted by the same step number, description thereof is omitted, and different portions will be described.

After calculating the number of failures of the switching element pair SP in the DC / DC converter 100 in step S52, the correction calculation unit 74 sets the upper limit target motor force flim corresponding to the number of failures in step S61. The upper limit target motor force flim represents the upper limit value of the target motor force fmotor ^{*. When} the number of failures is “0”, the upper limit target motor force flim is normally set to the upper limit value flim0, and the smaller the number of failures, the smaller the value flim (<flim0 ). The relationship between the upper limit target motor force flim and the number of failures is stored in advance in the memory of the suspension ECU 70.

Subsequently, in step S62, the correction calculation unit 74 determines whether or not the target motor force fmotor ^* calculated by the target motor force calculation unit 113 is larger than the upper limit target motor force flim. If the target motor force fmotor ^* is larger than the upper limit target motor force flim, the target motor force fmotor ^* is changed to the upper limit target motor force flim in step S63 (fmotor ^* ← flim). On the other hand, if the target motor force fmotor ^* is less than or equal to the upper limit target motor force flim, the process of step S63 is skipped and the target motor force fmotor ^* is not changed. When the new target motor force fmotor ^* is calculated in this way, in step S55, a control signal corresponding to the target motor force fmotor ^* is output to the motor EDU 50, and the target motor force correction routine is terminated.

  In the first modification, when a failure of the switching element pair SP of the DC / DC converter 100 is detected, the upper limit current flowing through the DC / DC converter 100 is limited, and the heat generation of the switching element S is suppressed. For this reason, also in the modification 1, the effect similar to embodiment can be acquired.

<Modification 2>
In each of the above examples, the failure diagnosis signal is output to the suspension ECU 70 to vary the target motor force fmotor ^*. Instead, the current is limited by the motor control unit 52 of the motor EDU 50. Also good. For example, the switch control unit 140 of the DC / DC converter 100 outputs a failure diagnosis signal to the motor control unit 52 of the motor EDU 50 in step S17 and step S27. And the motor control part 52 implements the upper limit electric current setting routine shown in FIG. The motor control unit 52 inputs a failure diagnosis signal in step S71, and calculates the number of failures of the switching element pair SP in the DC / DC converter 100 in step S72. Subsequently, in step S73, an upper limit current ilim corresponding to the number of failures is set. In this case, the upper limit current ilim is set to a smaller value as the number of failures increases. The relationship between the upper limit current ilim and the number of failures is stored in the memory of the motor control unit 52 in advance.

When the target current i ^* corresponding to the target motor force f motor ^* of the control signal output from the suspension ECU 70 is larger than the upper limit current i lim in step S74, the motor control unit 52 performs the target current i ^* in step S75 ^. Is set to the upper limit current value ilim, and if the target current i ^* is less than or equal to the upper limit current value, the process of step S75 is skipped and the target current i ^* is not changed. As described above, the upper limit current limiting process can be performed in either the suspension ECU 70 or the motor EDU50.

<Modification 3>
Further, correction by the control gain K can be performed on the motor EDU 50 side. For example, the motor control unit 52 of the motor EDU 50 calculates the number of failures of the switching element pair SP based on the failure diagnosis signal, and sets a control gain K corresponding to the number of failures. Then, the target motor force fmotor ^* of the control signal output from the suspension ECU 70 is multiplied by the control gain K, and a target current corresponding to the target motor force fmotor ^* is caused to flow to the electric motor 40. Thereby, the electric current which flows into the DC / DC converter 100 is restrict | limited, and the heat_generation | fever of the switching element S can be suppressed.

<Modification 4>
In the example described above, the control gain K or the upper limit value is set according to the number of failures of the switching element pair SP of the DC / DC converter 100, but is set according to the presence or absence of the failure regardless of the number of failures. There may be. For example, when a failure has occurred in the switching element pair SP of the DC / DC converter 100, the target motor force fmotor ^* is multiplied by a constant control gain K (<1) regardless of the number of failures. May be. For example, when the control gain K is set to 0.5, the normal switching element S on one side has a current that does not change from the normal level (before the occurrence of a failure), and the switching element S generates heat. It can be suppressed appropriately. Further, when a failure has occurred in the switching element pair SP of the DC / DC converter 100, a constant upper limit current ilim smaller than that in the normal state may be set regardless of the number of failures.

<Modification 5>
In the fifth modification, the processing in the suspension ECU 70 is changed according to the location where the failure of the switching element pair SP in the DC / DC converter 100 occurs. As described above, the primary side switching circuit 110 operates when the electric power of the high voltage battery 200 is supplied to the motor EDU 50, and the secondary side switching circuit 120 regenerates the electromotive force generated by the electric motor 40 to the high voltage battery 200. It works when you let it go. Therefore, in the fifth modification, when a failure is detected in the switching element pair SP of the primary side switching circuit 110, the power supply from the high voltage battery 200 to the motor EDU 50 is limited, and the secondary side switching circuit 120 When a failure is detected in the switching element pair SP, power regeneration from the motor EDU 50 to the high voltage battery 200 is limited.

FIG. 13 shows a target motor force correction routine executed by the correction calculation unit 74 of the suspension ECU 70. The target motor force correction routine is repeated at a predetermined short cycle. First, in step S81, the correction calculation unit 74 inputs a failure diagnosis signal output from the switch control unit 140 of the DC / DC converter 100. Subsequently, in step S82, it is determined whether or not a failure is detected in the switching element pair SP of the DC / DC converter 100 based on the failure diagnosis signal. If no failure is detected (S82: No), the correction calculation unit 74 does not correct the target motor force fmotor ^* calculated by the target motor force calculation unit 113 in step S83, and directly applies it to the motor EDU50. Outputs and this routine is finished once.

  On the other hand, if a failure is detected (S82: Yes), in step S84, the failure location of the switching element pair SP is determined based on the failure diagnosis signal. When the failure part is the primary side switching circuit 110, in step S90, power consumption restriction control processing is executed. When the failure part is the secondary side switching circuit 120, in step S100, a power regeneration restriction control process is executed. If the failure location is both the primary side switching circuit 110 and the secondary side switching circuit 120, bidirectional restriction control is executed in step S110.

  As the bidirectional restriction control, a target motor force correction routine shown in FIG. 10 or FIG. 11 may be executed. Alternatively, the current limiting process (FIG. 12) may be executed on the motor EDU 50 side.

The power consumption restriction control process is executed according to the power consumption restriction control routine shown in FIG. This power consumption restriction control routine is a subroutine incorporated as the process of step S90 of the target motor force correction routine. Correction calculation unit 74, at step S91, the read stroke displacement amount x _S detected by the stroke sensor 63, calculates the stroke speed x _{S 'by} differentiating the stroke displacement amount x _S in time. Subsequently, in step S92, a control region in the current suspension control is determined from the stroke speed x _S 'and the target motor force fmotor ^* calculated by the target motor force calculation unit 113. As shown in FIG. 17, the control region is determined by the stroke speed x _S ′ and the target motor force f motor ^* .

Subsequently, in step S93, the correction calculation unit 74 determines whether or not the control area is a consumption area. When the control area is the consumption area 1 or the consumption area 2 (S93: Yes), the control gain K (0 <K <1) is added to the target motor force fmotor ^* calculated by the target motor force calculation unit 113 in step S94. ) And the multiplication result (K · fmotor ^* ) is set to a new target motor force fmotor ^* . This control gain K is preset and stored in the memory (for example, K = 0.5), but may be changed according to the number of failures as described above. On the other hand, when the control area is not the consumption area 1 or the consumption area 2 (S93: No), the target motor force fmotor ^* is not corrected. In step S95, the correction calculation unit 74 outputs a control signal corresponding to the target motor force fmotor ^* to the motor EDU 50, and ends the power consumption restriction control routine.

Therefore, when the control region is the consumption region 1 or the consumption region 2, the current supplied from the high voltage battery 200 to the motor EDU 50 is reduced, so that the heat generation of the switching element S of the primary side switching circuit 110 is suppressed. Can do. Moreover, since the target motor force fmotor ^* is not corrected during power regeneration, a sufficient damping force can be obtained. In this case, since the secondary side switching circuit 120 has not failed, heat generation is suppressed by current distribution in the switching element pair SP.

In this example, the target motor force fmotor ^* is corrected by multiplying by the control gain K. However, as in the above-described modifications (S61, S62, S63), the upper limit target motor force flim is set to the normal time. It may be made smaller. In this case, the upper limit value of the current supplied from the high voltage battery 200 to the motor EDU 50 is suppressed. Thereby, heat_generation | fever of the switching element S of the primary side switching circuit 110 can be suppressed.

Further, the target motor force fmotor ^* may be set to zero (fmotor ^* = 0). In this case, semi-active control for controlling only the damping force is executed.

Further, the upper limit current flowing through the electric motor 40 may be limited by outputting an upper limit current reduction command when the correction calculation unit 74 outputs the target motor force f motor ^* to the motor EDU 50.

Next, the power regeneration restriction control process in step S100 will be described. FIG. 15 shows a power regeneration restriction control routine executed by the correction calculation unit 74. This power regeneration restriction control routine is a subroutine incorporated as the process of step S100 of the target motor force correction routine. In step S101, the correction calculation unit 74 changes the interphase short-circuit start threshold value Wref to the failure threshold value Wlow instead of the normal threshold value W0 (when the failure of the secondary side switching circuit 120 is not detected) ( Wref ← Wlow). The failure threshold value Wlow is set to a value smaller than the normal threshold value W0. Subsequently, in step S102, the interphase short-circuit start threshold Wref set to the failure threshold Wlow is output to the motor EDU 50, and the power regeneration restriction control routine is temporarily terminated. In this case, the correction calculation unit 74 outputs the motor EDU 50 as it is without correcting the target motor force fmotor ^* calculated by the target motor force calculation unit 113 in addition to the interphase short-circuit start threshold value Wref.

  FIG. 16 shows a power regeneration limit control routine executed by the motor control unit 52 of the motor EDU 50. This power regeneration restriction control routine is repeatedly executed at a predetermined short cycle. In step S105, the motor control unit 52 reads the interphase short-circuit start threshold Wref output from the correction calculation unit 74 of the suspension ECU 70. Subsequently, in step S106, the motor current iuvw detected by the current sensor 53 and the motor voltage Vuvw detected by the voltage sensor 54 are read. Subsequently, in step S107, the regenerative power Wx is calculated from the motor current iuvw and the motor voltage Vuvw. In this case, it can be determined from the direction in which the motor current iuvw flows whether the power regeneration state is the power consumption state. In the case of the power consumption state, the value of the regenerative power Wx is set to zero (Wx = 0).

  In subsequent step S108, the motor control unit 52 compares the regenerative power Wx with the interphase short circuit start threshold value Wref, and determines whether or not the regenerative power Wx is larger than the interphase short circuit start threshold value Wref. If it is determined that the regenerative power Wx is greater than the interphase short-circuit start threshold Wref (S108: Yes), in step S109, the switching elements S1, S2, S3 on the step-down power line 203 side of the three-phase inverter 51 are turned on. The switching elements S4, S5, S6 on the ground line 204 side are turned off. As a result, the energization terminals of the electric motor 40 are short-circuited. In this phase-to-phase short-circuit state, current flows between the terminals of the electric motor 40 due to the electromotive force generated in the electric motor 40, and no regenerative current flows from the three-phase inverter 51 to the DC / DC converter 100. At this time, a braking force proportional to the magnitude of the current flowing through the motor coil is generated in the electric motor 40, and the expansion / contraction operation of the electromagnetic actuator 30 (the expansion / contraction operation of the ball screw mechanism) is attenuated.

  On the other hand, when the motor control unit 52 determines that the regenerative power Wx is equal to or smaller than the interphase short-circuit start threshold Wref (S108: No), the process of step S109 is skipped. That is, the interphase short circuit process of the electric motor 40 is not performed. Therefore, power regeneration from the electric motor 40 to the high voltage battery 200 is performed.

  The motor control unit 52 repeatedly executes this power regeneration restriction control routine at a predetermined short cycle. Therefore, while the regenerative power Wx exceeds the interphase short circuit start threshold Wref, the interphase short circuit process of the electric motor 40 is performed, and the regenerative current does not flow to the DC / DC converter 100.

  According to the power regeneration limiting control routine in the suspension ECU 70 and the motor EDU 50, when the secondary side switching circuit 120 of the DC / DC converter 100 fails, the interphase short circuit start threshold Wref is set to a value smaller than usual. Therefore, the start timing of the interphase short circuit process is advanced. Thereby, a large regenerative current does not flow to the high voltage battery 200 via the DC / DC converter 100. As a result, the current flowing through the switching element pair SP of the secondary side switching circuit 120 is limited, and heat generation of the switching element S paired with the failed switching element S can be suppressed. In addition, since the power supply from the high voltage battery 200 to the motor EDU 50 is not limited, the electromagnetic actuator 30 can generate a sufficient propulsive force.

  Since the electric motor 40 generates heat when the inter-phase short-circuit process is executed, it is preferable that the relays R1, R2, and R3 of the inter-phase opening relay unit 55 are appropriately turned off to open the electric motor 40 from the power source. In this case, since no current flows through the coil of the electric motor 40, motor overheating can be prevented.

Further, the power regeneration restriction control process is not limited to the interphase short-circuit process. For example, the control area is determined in the same manner as the power consumption restriction control routine (FIG. 14), and the control area is the regeneration area 1 or the regeneration area 2. In this case, the target motor force fmotor ^* may be corrected for reduction. In this case, for example, step S93 of the power consumption restriction control routine of FIG. 14 may be changed to a process for determining whether the control area is the regeneration area 1 or the regeneration area 2.

  The power supply system for the electromagnetic suspension device according to the present embodiment has been described above. However, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the object of the present invention.

For example, when a failure of the switching element pair SP is detected, a process for reducing and correcting the target motor force fmotor ^* using the control gain K (= a process for reducing and correcting the target current) and a target motor force fmotor ^* It is also possible to perform both of the process of reducing the upper limit value (= the process of reducing the upper limit value of the target current).

  The present embodiment is a power supply system that mutually supplies power between the high-voltage battery 200 and the electromagnetic suspension device via the DC / DC converter 100. For example, instead of the electromagnetic suspension device, electric power steering The present invention can also be applied to other in-vehicle electric devices such as devices. In the case of an electric power steering device, power may be supplied from the DC / DC converter 100 to a motor drive circuit (for example, a three-phase inverter) that drives an electric motor provided in the steering mechanism.

  In this embodiment, the configuration in which four motors EDU 50 are connected in parallel to one DC / DC converter 100 is adopted, but the primary sides of the four DC / DC converters 100 are connected in parallel to the high-voltage battery 200. It is also possible to adopt a configuration in which the motor EDU 50 is connected to the secondary side of each DC / DC converter 100.

  In the present embodiment, the power output from the high voltage battery 200 is stepped down by the DC / DC converter 100 and supplied to the in-vehicle electric device. However, in the present embodiment, the power output from the low voltage battery is DC / DC. It can also be adopted in a system that boosts the voltage with a converter and supplies it to an in-vehicle electric device.

  DESCRIPTION OF SYMBOLS 10 ... Suspension main body, 30 ... Electromagnetic actuator, 40 ... Electric motor, 50 ... Motor EDU, 51 ... Three-phase inverter, 52 ... Motor control part, 53 ... Current sensor, 54 ... Voltage sensor, 70 ... Suspension ECU, 71 ... Vibration Damping control force calculation unit, 72 ... Roll suppression control force calculation unit, 73 ... Target motor force calculation unit, 74 ... Correction calculation unit, 100 ... DC / DC converter, 110 ... Primary side switching circuit, 111, 112, 113, 114, 121, 122 ... switching element pair, 120 ... secondary side switching circuit, 130 ... transformer, 131 ... primary side winding, 132 ... secondary side winding, 140 ... switch control unit, 151, 152, 153 154, 161, 162 ... current sensor, 155 ... primary voltage sensor, 156 ... primary current sensor, 157 ... secondary Voltage sensor, 158 ... secondary current sensor, 190 ... power consumption circuit, 200 ... high voltage battery, 201 ... high voltage power line, 202, 204 ... ground line, 203 ... step-down power supply line, i1 ... primary side total current, i11 , I12, i13, i14, i21, i22 ... element current, i2 ... secondary side total current, SP ... switching element pair, S ... switching element.

Claims (9)

The in-vehicle battery and the in-vehicle electric device are connected via a bidirectional DC voltage converter, and the electric power output from the in-vehicle battery is transformed by the DC voltage converter and supplied to the in-vehicle electric device, and In the vehicle power supply system for regenerating the in-vehicle battery by transforming the electromotive force generated in the in-vehicle electric device with the DC voltage converter,
The DC voltage converter includes a transformer having a primary side winding connected to the in-vehicle battery and a secondary side winding connected to the in-vehicle electrical device, and forward / reverse current to the primary side winding. A primary-side switching circuit for alternately flowing, and a secondary-side switching circuit for alternately flowing a current through the secondary-side winding in the forward and reverse directions,
The vehicular power supply system, wherein the primary side switching circuit and the secondary side switching circuit each include a switching element pair in which two switching elements are connected in parallel at a portion to be switched.   2. The vehicle power supply system according to claim 1, further comprising failure detection means for detecting a failure of each switching element pair in the primary side switching circuit and the secondary side switching circuit. The failure detection means includes
Primary-side total current acquisition means for acquiring primary-side total current information representing a primary-side current value flowing between the in-vehicle battery and the primary-side switching circuit;
Primary-side one-side element current acquisition means for acquiring primary-side one-side element current information representing a current value flowing through one-side switching element in each switching element pair provided in the primary-side switching circuit;
Secondary-side total current acquisition means for acquiring secondary-side total current information representing a secondary-side current value flowing between the in-vehicle electric device and the secondary-side switching circuit;
Secondary-side single-side element current acquisition means for acquiring secondary-side single-side element current information representing a current value flowing through the switching element on one side in each switching element pair provided in the secondary-side switching circuit;
Primary switching element pair failure detecting means for detecting a failure of each switching element pair provided in the primary side switching circuit based on the acquired primary side total current information and primary side one side element current information. When,
Secondary-side switching element pair failure detection means for detecting a failure of each switching element pair provided in the secondary-side switching circuit based on the acquired secondary-side total current information and secondary-side single-side element current information The vehicle power supply system according to claim 2, further comprising:   When the failure detecting means detects an off-failure of one switching element in the switching element pair, the failure detects an on period during which the failure switching element pair having the switching element in which the failure is detected is turned on. An on-period ratio changing unit that shortens the switching element pair that is not turned on and that is alternately turned on / off with the failed switching element pair, as compared with an on-period in which the switching element pair is turned on. Item 4. The vehicle power supply system according to Item 2 or 3.   5. The apparatus according to claim 2, further comprising an operation restriction unit that restricts the operation of the in-vehicle electric device based on a failure of the switching element pair detected by the failure detection unit. The vehicle power supply system described. The in-vehicle electric device includes an electric motor,
6. The vehicle power supply system according to claim 5, wherein the operation limiting means lowers an upper limit value of a current flowing through the electric motor, or reduces and corrects a control amount of the electric motor. The in-vehicle electric device is provided in an electromagnetic suspension device, and includes an electric motor that generates a propulsive force and a damping force with respect to relative movement between the sprung member and the unsprung member,
When the failure detection unit detects a failure of the switching element pair only in the secondary side switching circuit, the operation limiting unit is configured to transfer the electric motor generated by the electric motor to the vehicle battery. 7. The vehicle power supply system according to claim 5, wherein the operation of the electric motor is limited so that only the power regeneration is limited. The in-vehicle electric device is provided in an electromagnetic suspension device, and includes an electric motor that generates a propulsive force and a damping force with respect to relative movement between the sprung member and the unsprung member,
The operation restricting means restricts only power supply from the in-vehicle battery to the electric motor when a failure of the switching element pair is detected only in the primary side switching circuit by the failure detecting means. The vehicle power supply system according to any one of claims 5 to 7, wherein the operation of the electric motor is limited to the above. When the electric power regenerated from the electric motor to the in-vehicle battery exceeds a set threshold due to the electromotive force generated by the electric motor, the electric motor includes a phase short-circuit unit that short-circuits the phases of the electric motor and disables the power regeneration. ,
The vehicle power supply system according to claim 7, wherein the operation limiting unit limits the power regeneration by lowering the setting threshold.

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