JP4676869B2 - Vehicle power system and boost power supply - Google Patents

Description

  The present invention relates to a vehicle power system and a boost power source that supply power to a plurality of loads of a vehicle.

  Many starting systems such as cell motors and ignition, headlamps, indoor instruments, electrical components, etc. are used in vehicles. In addition, for example, a motor used in an electric power steering device that assists steering force needs to pass a large current of 60 A or more in a normal 2000 cc class automobile. In particular, in order to obtain more output recently. It is required to drive at a voltage higher than the battery voltage. For this reason, a vehicle power distribution system is disclosed in which not only a battery load but also a DC-DC converter is used to generate a high voltage and supply power to a high voltage compatible load (see Patent Document 1).

An example of a power supply device in which a second battery is provided on the output side of the booster circuit has been reported. For example, a first battery, a booster connected to the first battery, a second battery connected to the booster, and a torque signal of the steering handle connected to the second battery An example of a power supply device for electric power steering composed of a control circuit for supplying driving power of a steering motor corresponding to the above and a steering motor connected to the control circuit has been reported (see Patent Document 2).
JP 2000-318545 A (FIG. 2) Japanese Patent Publication No. 8-539 (Claim 1)

However, in the technique of Patent Document 1, since the load is connected to a DC-DC converter or a battery (power source), the load capacity of the DC-DC converter may be exceeded or the battery voltage may be There is a problem that the load voltage also decreases with the decrease.
Further, since the voltage of the second battery used in Patent Document 2 is fixed, there is a problem that the boosted voltage is applied even when a large current does not flow. Further, the voltage of the second battery needs to be an integral multiple of a unit battery that is generally used, and there is a problem that the degree of freedom of voltage is small.
Further, a switching element used in the DC-DC converter may cause a short circuit failure. Even in this failure state, it is preferable to supply the battery voltage to the load to avoid the operation stop of the load.

The present onset Ming challenge, Ru der to provide a power system for a vehicle which can also supply a stable power to each load to changes in transient load current.

To solve the above problems, the present onset Ming, power supply and, and a step-up power supply of one obtained by boosting the output voltage of the power supply, a vehicle power system for supplying power to a plurality of load groups of the vehicle, The vehicular power system further includes an auxiliary power source, and supplies power to any one or a plurality of loads of the load group by any one or a plurality of power sources of the power source, the boost power source, and the auxiliary power source. The plurality of load groups include a first load that operates only with the power source, a second load that operates using both the power source and the auxiliary power source, and a third load that operates only with the boost power source. The auxiliary power source is provided on the output side of the boost power source, and an input control unit that controls input power to the auxiliary power source, and an output control unit that controls output power from the auxiliary power source, And the second load has a front Power or the a power from the auxiliary power supply can selectively supplied, and wherein said first load, the second load, and it is possible to simultaneously supply power to the third load.
According to this, power is supplied to any load in the load group by any one or a plurality of power sources among the power source, the boost power source, and the auxiliary power source.

  In particular, if the auxiliary power source is a power source that is powered by the power source or the boosted power source, power is supplied to the load by the auxiliary power source even if the voltage of the power source decreases. In addition, power can be supplied to the boost power supply using an auxiliary power supply. That is, the vehicle power system further includes an auxiliary power source that is supplied with power by either the power source or the boost power source, and one or more of the power source, the boost power source, and the auxiliary power source. It is preferable to supply power to one or a plurality of loads in the load group by a power source.

  The invention according to claim 2 is characterized in that, in the vehicle power system, the power source is a battery having an internal resistance, and the auxiliary power source is a capacitor. As a result, the output voltage of the boost power supply is output to the load with the low impedance of the capacitor, so that the voltage drop is reduced even if the output current is large.

The invention according to claim 3 is the vehicle power system according to claim 1 or 2 , further comprising charge control means for starting charging of the capacitor before the ignition of the vehicle is turned on. Features. As a result, since charging of the capacitor is started before the engine is started, the output can be supplied to the load group immediately after the ignition is turned on.

  The vehicle power system may further include a switching unit that switches between a power source, a power source using both the auxiliary power source and the power source, and the boost power source to supply power. The motor has a characteristic that it rotates at a high speed when a large voltage is applied and a high torque when a large current is applied. Therefore, by switching the drive power source to the power source using the switching means, the motor is driven at a low speed rotation, and by switching the drive power source to the boost power source, the high speed rotation and the low torque drive are performed to assist the drive power source. By switching to the power source, high speed rotation and high torque driving are performed.

According to a fourth aspect of the present invention, in the vehicular power system according to any one of the first to third aspects, the boost power supply is stored in an input voltage and a coil to which the input voltage is applied. When the switching element that performs the switching operation is in a short-circuit fault state in which the input voltage is continuously short-circuited, the magnetic energy back electromotive force can be superimposed and supplied to the load by the switching operation. The application of the input voltage to the coil is cut off, and the input voltage is connected to a load.

  According to this, even if the switching element is in a short-circuit fault state in which the input voltage is continuously short-circuited, the connection between the input voltage and the switching element is cut off and the input voltage is connected to the load, so that the load is stopped. Is avoided. Here, if the load is a motor, the operation of the motor continues even in a short-circuit failure state.

Further, the invention according to claim 5 is the vehicle power system according to any one of claims 1 to 3, wherein the boosting power source is a series of a first switching element and a coil that have transitioned to a conductive state. When the input voltage is applied to the circuit, a voltage obtained by superimposing the back electromotive force of the magnetic energy accumulated in the coil and the input voltage is turned on by the transition of the first switching element to the open state. it is those that can be supplied to the load via the second switching elements of the state, a third switching element inserted in series with the first switching element, continuing the first switching element The second switching element is continuously conducted and the third switching element is continuously opened when there is a short-circuit fault state conducting to And applying the input voltage to the load via the coil.

  According to this, the input voltage is applied to the coil via the first switching element and the third switching element, and magnetic energy is stored. The first switching element is opened, and the input voltage and the counter electromotive force of the coil are supplied to the load via the second switching element that has transitioned to the conductive state. By repeatedly conducting and releasing the first switching element and the second switching element, the input voltage is steadily boosted. When the first switching element is in a short-circuit failure state, the third switching element is opened to avoid a short-circuit state of the input voltage, and the input voltage is loaded via the second switching element in the conductive state. To be applied.

Furthermore , the invention according to claim 6 is the vehicle power system according to any one of claims 1 to 3, wherein the input voltage is applied to the input voltage, the coil, and the first switching element in a conductive state. By being applied, the back electromotive force of the magnetic energy accumulated in the coil is superimposed using the first switching element that has been changed to the open state and the second switching element that has been changed to the conductive state. A third switching element that can be supplied to a load , and that cuts off the application of the input voltage to the coil when the first switching element is in a short-circuit fault state in which the first switching element is continuously conducted; And a fourth switching element for supplying the input voltage to the load.

According to this, the input voltage is applied to the coil via the first switching element and the third switching element, and magnetic energy is stored. The first switching element is opened, and the input voltage and the counter electromotive force of the coil are supplied to the load via the second switching element that has transitioned to the conductive state. By repeatedly conducting and releasing the first switching element and the second switching element, the input voltage is steadily boosted. When the first switching element is in a short circuit failure state, the third switching element cuts off the application of the input voltage to the coil, and the fourth switching element supplies the input voltage to the load.

According to the onset bright, power is supplied to either the load of the load group by any one or more of the power supply and the boost power supply and an auxiliary power supply. In particular, when the auxiliary power source is a power source that is powered by the power source or the boost power source, power is supplied to the load by the auxiliary power source even if the voltage of the power source is reduced. As a result, stable power can be supplied to the load group even when the load current changes transiently .

(First embodiment)
Next, a first embodiment of the present invention will be described in detail with reference to the drawings as appropriate. FIG. 1 is a configuration diagram of a vehicle power system 100 according to the present embodiment.
A vehicle power system 100 includes a battery 1 that is a power source (battery), a booster circuit 10 that boosts the voltage of the battery 1, and a capacitor 8 that serves as an auxiliary power source that charges an output voltage of the booster circuit 10 that is a booster power source. The steady load 50 to which the voltage of the battery 1 is supplied, the boost corresponding load 52 to which the output of the booster circuit 10 is supplied, the voltage of the capacitor 8 controlled by the FET 6 as an active element, and the voltage of the battery 1 The main part is a load 54 with a large temporary current supplied through the diodes 2 and 3, and each part is controlled by the constant current charge control circuit 20, the discharge control circuit 30, and the power supply system activation control circuit 40 Is done.

  The battery 1 is a secondary battery having a voltage of 12 V, and is connected to a steady load 50 such as a headlight or an electrical component. Further, since the battery 1 has an internal resistance, the output voltage decreases due to a large current, and the battery 1 has a characteristic of deteriorating with long-term use.

  The booster circuit 10 to which the voltage of the battery 1 is input via the diode 2 is configured by a DC-DC converter having an input voltage of 12V and an output voltage of 20V. The output terminal of the booster circuit 10 is connected to a booster-compatible load 52 such as an electric power steering device, and the output voltage is connected to the capacitor 8 via the diode 4 and the FET 7. Here, the capacitor 8 is a large-capacity electric double layer capacitor, and for example, a capacitor having a capacity of 50 F and a rated voltage of 25 V is used. The diode 4 is provided in order to prevent backflow when the output voltage of the booster circuit 10 is lower than the charging voltage of the capacitor 8. Details of the DC-DC converter circuit will be described later.

  The capacitor 8 is connected to the input terminal of the booster circuit 10 via the FET 6 and the diode 3, and is connected to the load 54 having a large temporary current. That is, the cathodes of the diodes 2 and 3 are connected to the input of the booster circuit 10 and the load 54 having a large temporary current. Due to the action of the diodes 2 and 3, the load 54 having a large temporary current is applied to the load 54 having a large temporary current, whichever is larger than the voltage of the battery 1 or the voltage controlled by the FET 6. As a result, even if the temporary current is large and the voltage of the battery 1 is lowered, the voltage controlled by the FET 6 is applied to the load 54 having a large temporary current. In addition, since the voltage controlled by the FET 6 is input to the booster circuit 10, the voltage applied to the booster load 52 does not decrease even if the booster circuit 10 itself is not output voltage controlled. The substrates of the FETs 6 and 7 are preferably connected to the drain or source or grounded.

  The constant current charge control circuit 20 is a control circuit for making the charging current for charging the output voltage of the booster circuit 10 into the capacitor 8 constant, and controls the gate voltage of the FET 7 which is an active element. Further, when the voltage monitored at the connection point between the FET 7 and the diode 4 exceeds a predetermined value, the FET 7 is turned on. As a result, even if a regenerative current is generated in the boost-corresponding load 52, a current flows through the capacitor 8, so that the booster circuit 10 can be protected. Since the inrush current to the capacitor 8 may be limited, if the resistor is inserted instead of the FET 7, the control by the constant current charge control circuit 20 becomes unnecessary. If a coil L1 is inserted between the FET 7 and the capacitor 8 and a commutation diode is provided between the connection point of the FET 7 and the coil L1 and the ground, constant current control is performed by controlling the ON-OFF time of the FET 7. You can also.

  The discharge control circuit 30 controls the discharge of the charge of the capacitor 8 by changing the gate voltage of the FET 6 when the voltage of the battery 1 decreases and becomes equal to or lower than the reference voltage Vr. In this circuit, the input voltage of the load 54 and the booster circuit 10 is varied from 0 V to the maximum voltage. Thereby, the input voltage of the load 54 and the booster circuit 10 having a large temporary current can be maintained at the voltage of the battery 1. If a coil L2 is inserted between the FET 6 and the diode 3 and a commutation diode is provided between the connection point of the FET 6 and the coil L2 and the ground, the constant voltage control is performed by controlling the ON-OFF time of the FET 6. You can also.

  The power supply system activation control circuit 40 is a circuit for starting charging of the capacitor 8 before the load 54 having a large temporary current is driven, and functions as a charging power control means. This circuit drives the booster circuit 10 by using, for example, a door lock release signal for detecting whether or not the door lock is released and an occupant detection signal for judging whether or not the occupant is in the vehicle, and the discharge control circuit 30. Is instructed to turn off the FET 6, and the constant current charge control circuit 20 is instructed to perform constant current control of the FET 7. Thereby, the charging of the capacitor 8 is started before the ignition is turned on. When charging the 50 F electric double layer capacitor at 50 A, the voltage rises only by 1 V per second. For this reason, a power supply system activation control circuit 40 is provided in order to perform charging at the earliest possible stage.

Next, an electric power steering apparatus in which a motor is used as the boosting load 52 will be described with reference to FIG.
In the electric power steering apparatus 70, when the steering handle 11 is rotated, the steering shaft 12 directly connected to the steering handle 11 rotates the pinion 13 constituting the rack and pinion mechanism 15 via the connected torque sensor 23, thereby The rack shaft 14 is moved to change the direction of the snake wheel 17 and steer. At this time, according to the torque signal T detected by the torque sensor 23, the control circuit 22 controls the motor 19 using the electric power supplied from the booster circuit 10 (see FIG. 1). With this supplied power, the motor 19 rotates the pinion 13 via the power transmission mechanism 18 and operates to reduce the steering torque of the steering handle 11.

  The electric power steering device 70 detects a steering torque generated in the steering shaft 12 when the steering handle 11 is steered. When a large steering force is required based on this detection signal, the motor 19 is driven to assist steering. A force is generated, and the steering handle 11 is operated to reduce the steering force. That is, when the steering handle 11 is being steered, if a large steering torque is required, a large steering force is required, so that a large steering assist force is supplied. On the other hand, if the steering torque is small, a large steering force is provided. Therefore, it is configured to supply a small steering assist force.

  Next, a DC-DC converter circuit (not shown) of the booster circuit 10 will be briefly described. The booster circuit 10 includes a coil, an FET, and a diode as main parts, and one end of the coil is connected to the input end IN, and the drain end of the FET and the anode end of the diode are connected to the other end. The source terminal of the FET is grounded, and the cathode terminal of the diode is connected to the output of the booster circuit 10. Here, voltage control is performed by ON-OFF control of the gate voltage of the FET.

  First, when the FET is turned on, a current flows through the coil, and magnetic energy is stored. Next, when the FET is turned off, the counter electromotive force generated in the coil is superimposed on the input voltage Vin of the booster circuit 10, so that a boosted voltage is output. Note that the output voltage varies depending on the DUTY ratio of the gate voltage of the FET.

Next, the operation of this embodiment will be described with reference to the flowchart of FIG.
Electric power is supplied to the steady load 50 directly connected to the battery 1 and the load 54 having a large temporary current connected via the diode 2, and the flow of FIG. In step S1, a command to turn off the discharge of the capacitor 8 is issued to the discharge control circuit 30, and the FET 6 is set to the OFF state. Next, the process proceeds to step S2, and it is determined whether or not boarding has been confirmed. Specifically, boarding confirmation is performed by detecting a door lock release signal or an occupant detection signal. If boarding confirmation is not performed, it will be judged as "NO" and processing of Step S2 will be repeated. On the other hand, if the occupant is confirmed, "YES" is determined, and the process proceeds to step S3.

  In step S <b> 3, constant current charging to the capacitor 8 and driving of the booster circuit 10 are instructed, and power is supplied to the booster load 52. And a process progresses to step S4 and it is determined whether a battery voltage is less than predetermined value. If the battery voltage is equal to or higher than a predetermined value (for example, 11V), it is determined as “NO”, and the process of step S4 is repeated, and the power of the battery 1 is supplied to the load 54 having a large temporary current. On the other hand, if the battery voltage is less than the predetermined value, “YES” is determined, and the process proceeds to step S5.

  In step S5, discharge control of the capacitor 8 is performed. Here, if the FET 6 is turned on, the power charged in the capacitor 8 is supplied to the load 54 having a large temporary current. Thereby, the current burden of the battery 1 is reduced. Then, this routine ends and returns to the original routine. Note that the voltage of the battery 1 is restored by taking out the current from the capacitor 8, but the FET 6 is assumed to be in the ON state. Further, it is preferable to discharge the capacitor 8 after detecting that the charging of the capacitor 8 is completed.

  As described above, according to the present embodiment, it is possible to efficiently supply power to the boost-capable load 52, the load 54 with a large temporary current, and the steady load 50 with a simple configuration. Further, by providing the discharge control circuit 30, it is possible to supply power from the high power load to the constant power load to the load 54 having a large temporary current. In particular, even in a system in which a temporary large current flows, the power charged in the capacitor 8 serving as an auxiliary power supply is supplied to the load 54 having a large temporary current, so that the voltage drop of the steady load 50 is avoided. As a result, an unstable state such as a change in the illuminance of the headlamp is reduced, and the reliability of the system is increased. In addition, since it is not necessary to determine the capacity of the battery 1 in accordance with a temporary large current, an inexpensive vehicle power system is obtained. Moreover, since the capacity | capacitance of the generator which charges the battery 1 or the battery 1 can be made small, these size reduction and weight reduction can be achieved.

(Second Embodiment)
In the first embodiment, power is supplied to each of the steady load 50, the load 54 with a large temporary current, and the boosting load 52. However, it is also possible to connect each output voltage to one load using the switching means. it can. Hereinafter, a second embodiment will be described with reference to FIG. The battery 1, diodes 2, 3, 4, FETs 6, 7, capacitor 8, and booster circuit 10 are the same as those shown in FIG.
The three outputs of the battery 1, the booster circuit 10 and the capacitor 8 are input to the switching means 60 having three contacts a, b and c, and the outputs are supplied to a single load 55. The switching means 60 may be a relay or a semiconductor switch such as an FET or a transistor.

  The motor (electric motor) has a characteristic that it rotates at a high speed when a large voltage is applied and a high torque when a large current is applied. Therefore, when the load 55 is a motor, the switching power supply is switched to the battery 1 by using the switching means 60, so that the low-speed rotation is achieved, and the high-speed rotation and low-torque driving is performed by switching to the booster circuit 10. However, switching to the capacitor 8 enables high-speed rotation and high-torque driving.

(Third embodiment)
The booster circuit 10 used in each of the above embodiments is provided with a switching element therein, and can be configured to avoid stopping the load even when the switching element is short-circuited. The power supply apparatus having such a configuration will be described with reference to the circuit diagram of FIG.
The power supply device 80 shown in FIG. 5A that can be used in the booster circuit 10 shown in FIGS. 1 and 4 includes a booster circuit 81, a third switching element FET77, and a fourth switching device. It is comprised from FET78 which is an element.
The drain terminal of the FET 77 is connected to the positive terminal of the battery 1 and the drain terminal of the FET 78, and the source terminal of the FET 77 is connected to the input terminal IN 1 of the booster circuit 81 and functions as the input terminal IN 2 of the power supply device 80. The source terminal of the FET 78 is connected to the output terminal OUT 1 of the booster circuit 81 and functions as the output terminal OUT 2 of the power supply device 80. The negative electrode of the battery 1 and the GND terminal of the power supply device 80 are grounded, and the output terminal OUT2 and the GND terminal are connected to the load 55.

  The booster circuit 81 includes a coil 74, a capacitor C, a diode D, an FET 75 that is a first switching element, and an FET 76 that is a second switching element. The input terminal IN1 of the booster circuit 81 and one end of the coil 74 are connected, and the other end of the coil 74 is connected to the drain terminal of the FET 75, the drain terminal of the FET 76, and the anode terminal of the diode D. The source end of the FET 76, the cathode end of the diode D, and one end of the capacitor C are connected to the output end OUT1. The source end of the FET 75 is grounded to GND.

Next, the operation of the booster circuit 81 in a state where the FET 77 is turned on and the voltage _{VIN of the} battery 1 is applied to the input terminal IN1 will be described. _First, conduction FET75 the _{T ON} time, by FET76 to cut off, current flows through the coil 74, magnetic energy is stored. Note that this current increases linearly with a slope that is inversely proportional to the inductance L of the coil 74, and the amount of increase in current is (V _IN / L) T _ON . _After a lapse _{T ON} time, on the contrary, to cut off the FET 75 _{T OFF} time, thereby turning the FET 76. As a result, the current decreases linearly at a T _OFF time with a slope inversely proportional to the inductance L, and the decrease amount of the current is ((V _O −V _IN ) / L) T _OFF when the output voltage is V _O. . After the T _OFF time has elapsed, the FET 75 is _{turned on} and the FET 76 is turned off again. That is, the two FETs 75 and 76 are switched in a complementary manner.

By alternately repeating the conduction of the FET 75 and the interruption of the FET 76 and the interruption of the FET 75 and the conduction of the FET 76, the increase amount and decrease amount of the current become equal, and the output voltage V _O becomes (1 + T _ON / T _OFF ) V. Converges to _IN . That, ON of FET75,76, the voltage determined by the ratio of the OFF time _{(T ON / T OFF) V} IN is added to the voltage _{V IN} of the battery 1, the superimposed voltage is output from the booster circuit 81. Note that when T _ON = T _OFF , the input voltage _VIN and the counter electromotive force of the coil 74 are superimposed, and a voltage twice the input voltage can be output.

  At this time, if the FET 75 is in a short-circuit failure state, which is a continuous conduction state, the FET 77 is transitioned to the open state, and at the same time, the FET 78 is transitioned to the conduction state, and the FET 76 is opened. As a result, no short-circuit current flows through the FET 75, and the voltage of the battery 1 is generated at the output terminal OUT 2, and this voltage is supplied to the load 55.

  As described above, according to the present embodiment, if the FET 75 is not in a short-circuit failure state, a voltage obtained by boosting the charging voltage of the battery 1 is supplied to the load 55. On the other hand, even when the FET 75 is in a short circuit failure state, the charging voltage of the battery 1 is supplied to the load 55. For example, when a motor is connected to the load, since the boosted voltage is supplied to the motor unless the FET 75 is in a short-circuit fault state, even if the motor is rotated at a high speed and the FET 75 is in a short-circuit fault state. Since the charging voltage of the battery 1 is supplied to the motor, the operation of the motor is continued and the stopped state of the motor is avoided. In addition, the protective fuse inserted on the input side is not burned out.

(Fourth embodiment)
In the third embodiment, the current blocking FET 77 is provided in front of the booster circuit 81, and the FET 78 that connects the charging voltage of the battery 1 to the output terminal OUT2 is provided. However, the blocking FET is connected in series with the FET that is in a short-circuit fault state. Even if it is inserted, the power supply device can be configured to supply the charging voltage of the battery 1 to the load.

The power supply device 82 according to this embodiment that can be used as the booster circuit 10 shown in FIGS. 1 and 4 will be described with reference to FIG.
The battery 1 is connected between the input terminal IN and the GND terminal of the power supply device 82, and the load 55 is connected between the output terminal OUT and the GND terminal of the booster circuit 82. The power supply device 82 has an input terminal IN connected to one end of the coil 79, and the other end of the coil L connected to the drain terminal of the FET 71 that is the first switching element, the drain terminal of the FET 73 that is the second switching element, and the diode D. Connected to the anode end. In the power supply device 82, the source end of the FET 71 is connected to the drain end of the FET 72, which is the third switching element, and the source end of the FET 72 is connected to the GND end. In the power supply device 82, the source end of the FET 73, the cathode end of the diode D, and one end of the capacitor C are connected to the output end OUT. The other end of the capacitor C is grounded.

Next, the operation of the power supply device 82 will be described. In the normal operation state, the FET 72 is kept in a conducting state, and the voltage of the battery 1 is boosted by switching the FET 71 and the FET 73 alternately.
In addition, when the failure state in which the FET 71 is continuously short-circuited, the FET 72 is opened and the FET 73 is short-circuited. Thereby, the voltage of the battery 1 which is the voltage of the input terminal IN is directly output to the output terminal OUT.

  As described above, according to the present embodiment, in the normal operation state, the voltage (input voltage) of the battery 1 is intermittently shorted by intermittently short-circuiting the FETs 75 and 71 as the first switching elements. Applied to the coil, the back electromotive force of the coil is superimposed on the input voltage when the FETs 75 and 71 are opened. Then, when the FETs 75 and 71 are in a failure state in which they are continuously short-circuited (conducted), by opening the FET 72 as the third switching element, application of the input voltage to the coil is prohibited, and the short-circuit current is reduced. Avoided. Further, by short-circuiting the FET 73 as the second switching element or the FET 78 as the fourth switching element, the input voltage is generated as it is at the output terminal OUT. Therefore, the operation stop of the load 55 can be avoided.

(Modification)
The present invention is not limited to the above-described embodiment, and various modifications such as the following are possible, for example.
(1) In each of the above embodiments, the battery 1 is used as a power source, but a primary battery, a generator, or the like can also be used. Moreover, although the capacitor | condenser 8 was used as an auxiliary battery, it is also possible to use secondary batteries, such as a lead acid battery.
(2) In each of the above embodiments, a current is passed from the capacitor 8 to the load 54 having a large temporary current via the diode 3, but a relay may be used instead of the diode 3. In this case, the capacitor 1 can be charged from the battery 1 by turning off the FET 7.
(3) In each of the above embodiments, the voltage from the auxiliary power source is controlled by the discharge control circuit, but the current can also be controlled. Thereby, the motor torque can be directly controlled.
(4) In the first embodiment, the electric power steering device 70 is connected to the boost-corresponding load 52. However, the electric power steering device 70 may be connected to a load 54 having a large temporary current. In this case, the load 54 having a large temporary current is connected to the motor 19 via the control means 22. As a result, electric power is supplied from the battery 1 at normal times, but the voltage from the capacitor 8 is supplied to the motor 19 when a large steering force is required or when the battery voltage drops. Thereby, the voltage drop of the steady load 50 is avoided.
(5) The motor of the second embodiment can be used not only for a motor used for an electric power steering apparatus but also for a motor used for a hybrid vehicle.
(6) In the third and fourth embodiments, the drains and sources of the FETs 73 and 76 and the diode D are connected in parallel. However, the FETs 73 and 76 are not connected, and the diode D alone can be operated. In this case, the current flowing through the FETs 73 and 76 passes through the diode D.
(7) The present invention is also applicable to a steer-by-wire (Steer_By_Wire) in which a steering wheel and a snake wheel in a steering system are mechanically separated.

It is a lineblock diagram of the electric power system for vehicles of a 1st embodiment. It is a block diagram of an electric power steering device. It is a flowchart for starting the electric power system for vehicles of a 1st embodiment. It is a block diagram of the electric power system for vehicles of 2nd Embodiment. It is a block diagram of the power supply device of 3rd Embodiment, and the block diagram of the power supply device of 4th Embodiment.

Explanation of symbols

1 battery (power supply, battery)
2, 3, 4 Diode 6, 7 FET (active element, output control unit)
8 Capacitor (auxiliary power supply)
10 Booster circuit (Boost power supply)
DESCRIPTION OF SYMBOLS 11 Steering handle 12 Steering shaft 13 Pinion 14 Rack shaft 15 Rack pinion mechanism 17 Snake wheel 18 Power transmission mechanism 19 Motor 20 Constant current charge control circuit 22 Control circuit 23 Torque sensor 30 Discharge control circuit (output control part)
40 Power supply system start control circuit (charge control means)
DESCRIPTION OF SYMBOLS 50 Steady load 52 Boost corresponding | compatible load 54 Load with much temporary current 55 Load 60 Switching means 70 Electric power steering apparatus 71,75 FET (1st switching element)
72,77 FET (third switching element)
73,76 FET (second switching element)
78 FET (fourth switching element)
74, 79 Coil 100 Power system for vehicle

T Torque signal D Diode C Capacitor

Claims (6)

A vehicle power system that includes a power source and a single boost power source that boosts the output voltage of the power source, and supplies power to a plurality of load groups of the vehicle,
The vehicular power system further includes an auxiliary power source, and supplies power to any one or a plurality of loads of the load group by any one or a plurality of power sources of the power source, the boost power source, and the auxiliary power source. And
The plurality of load groups are divided into a first load that operates only with the power source, a second load that operates using both the power source and the auxiliary power source, and a third load that operates only with the boost power source. And
The auxiliary power source is provided on the output side of the boost power source,
An input control unit for controlling input power to the auxiliary power source;
An output control unit that controls output power from the auxiliary power source,
The second load can be selectively supplied with power from the power source or the auxiliary power source, and can be simultaneously supplied to the first load, the second load, and the third load. power system for a vehicle, characterized in that it. The power source is a battery having an internal resistance,
The vehicular power system according to claim 1, wherein the auxiliary power source is a capacitor. Vehicle power system according to claim 1 or claim 2, characterized in that it has a charging control means for ignition of the vehicle starts charging of the capacitor prior turned ON. The boost power supply, which can be supplied to the input voltage, and a counter electromotive force of the input voltage is accumulated on the applied coil magnetic energy superimposed by a switching operation load,
When the switching element that performs the switching operation is in a short-circuit fault state in which the input voltage is continuously short-circuited, application of the input voltage to the coil is cut off, and the input voltage is connected to a load. The vehicular power system according to any one of claims 1 to 3 . The boost power source is configured to superimpose the input voltage on the back electromotive force of the magnetic energy accumulated in the coil by applying an input voltage to the series circuit of the first switching element and the coil that have transitioned to a conductive state. Can be supplied to the load via the second switching element in the conductive state by the transition of the first switching element to the open state,
A third switching element inserted in series with the first switching element;
When the first switching element is in a short-circuit fault state in which the first switching element is continuously conducted, the second switching element is continuously conducted, and the third switching element is continuously opened, thereby the input. The vehicle power system according to any one of claims 1 to 3 , wherein a voltage is applied to the load via the coil. In the step-up power supply, the input voltage and the back electromotive force of the magnetic energy accumulated in the coil are shifted to the open state by applying the input voltage to the coil and the first switching element in the conductive state. it is those that can be supplied to the load by superimposing with the second switching element transitions to the first switching element and a conductive state,
A third switching element that cuts off the application of the input voltage to the coil, and a fourth that supplies the input voltage to the load when the first switching element is in a short-circuit fault state in which the first switching element is continuously conducted; The vehicle power system according to any one of claims 1 to 3, further comprising: a switching element.

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