JP5638465B2 - Vehicle power supply system - Google Patents

Description

  The present invention relates to a vehicular power supply system, and more particularly to a vehicular power supply system capable of simplifying control of a field current and realizing regeneration of braking energy of the vehicle and improvement of fuel consumption of the vehicle.

  In a conventional vehicular generator motor system, a rotating electric machine including a stator having a three-phase armature winding, and a rotor having a field coil for magnetizing a plurality of field magnetic poles, and the rotating electric machine as a generator A power converter that functions as a rectifying unit when functioning and a power converter that functions as an inverter when the rotating electrical machine functions as an electric motor and a control unit that controls the power converter are provided (for example, see Patent Document 1).

JP 2004-187346 A

In the conventional vehicular generator motor system, when the rotating electrical machine functions as a generator, the power generated by the rotating electrical machine is converted into DC power by the power converter and directly supplied to the battery. If the electric power generated by the rotating electrical machine is changed greatly, the life of the battery is reduced. As a result, there is a problem that the generated power of the rotating electrical machine, that is, the range for increasing the generated voltage cannot be increased, and the amount of charge of the battery cannot be increased greatly.
In the conventional vehicular generator motor system, when the rotating electrical machine functions as a generator, the switching element is turned on / off according to the generated voltage, and the field current is controlled by the duty ratio. Control of the field current by the control means becomes complicated.

  The present invention was made to solve such a problem, and is intended to increase the amount of charge of the power storage device so that the generated power of the generator can be greatly changed while suppressing a reduction in the life of the power storage device. An object of the present invention is to provide a vehicle power supply system that can realize regeneration of braking energy of a vehicle and improvement of fuel efficiency of the vehicle, and can simplify control of a field current.

A power supply system for a vehicle according to the present invention includes a field winding, a generator that is driven by an engine to generate AC power, and a rectifier that rectifies and outputs the AC power generated by the generator to DC power And a power conversion circuit that is connected to the positive output terminal of the rectifier via a generator side wiring, converts the output voltage of the rectifier to a different voltage value, and outputs the power conversion circuit via a load side wiring. a vehicle load connected Te, is connected via the load side wirings to the power conversion circuit, the voltage and the magnetic field of said vehicle a power storage device for supplying electric power to a load, the power storage device to the field winding A field energization circuit that supplies a field current determined from the resistance value of the winding, and the drive control of the power conversion circuit and the field energization circuit, and the generated power of the generator to the power storage device and the vehicle load Control times to supply power It has a, and. The power conversion circuit is configured by a constant voltage control type DC / DC converter, and the control circuit turns on the field energization circuit and sets the generator in a power generation state in response to a load-side power request. The field energization circuit is kept on until the end of power generation, and a target voltage for obtaining the maximum generated power is set according to the rotation speed of the generator, and the voltage of the generator-side wiring becomes the target voltage. Thus, the power conversion circuit is configured to be driven and controlled.

According to this invention, since the power storage device is connected to the positive output terminal of the rectifier via the power conversion circuit, fluctuations in the generated power of the generator do not affect the life of the power storage device. Therefore, the power generated by the generator can be greatly changed, and the braking energy of the vehicle can be efficiently recovered. As a result, it is possible to reduce the operation of causing the generator to generate power during non-deceleration and charging the power storage device, reducing the engine load during non-deceleration and improving the fuel efficiency of the vehicle.
In addition, the power conversion circuit is configured by a constant voltage control type DC / DC converter, and is driven and controlled so that the power generation voltage of the generator becomes a target voltage. Therefore, the duty ratio for turning on / off the field energization circuit is high. There is no need to control the field current, and the control of the field current is simplified.

1 is a schematic configuration diagram of a vehicle power supply system according to Embodiment 1 of the present invention. It is a circuit block diagram of the power converter device in the vehicle power supply system according to Embodiment 1 of the present invention. It is a figure which shows the electric power generation characteristic of the generator used for the vehicle power supply system which concerns on Embodiment 1 of this invention. It is a schematic block diagram of the vehicle power supply system which concerns on Embodiment 2 of this invention.

  Hereinafter, preferred embodiments of a vehicle power supply system of the present invention will be described with reference to the drawings.

Embodiment 1 FIG.
1 is a schematic configuration diagram of a vehicle power supply system according to Embodiment 1 of the present invention, FIG. 2 is a circuit configuration diagram of a power conversion device in the vehicle power supply system according to Embodiment 1 of the present invention, and FIG. It is a figure which shows the electric power generation characteristic of the generator used for the power supply system for vehicles which concerns on Embodiment 1 of invention.

  1 and 2, the vehicular power supply system is driven by the rotational torque of the engine 1 to generate AC power, and the AC power generated by the generator 2 is rectified to DC power and output. The rectifier 7, the power conversion device 20 that converts the output voltage of the rectifier 7 into a DC voltage having a different voltage value, and the DC power converted by the power conversion device 20 are charged and supplied to the in-vehicle load 10. A power storage device 9; and a control circuit 11 that controls the operation of the power converter 20 based on the rotational speed n of the generator 2, the voltage Va of the generator-side wiring 12, the voltage Vb of the load-side wiring 13, and the like. Yes. The rotation speed n of the generator 2 is obtained, for example, by attaching a rotation sensor (not shown) to the generator 2 and detecting the rotation speed of the shaft of the rotor 3. The control circuit 11 may be configured separately from an ECU (electronic control unit) or may be integrated into the ECU.

The generator 2 includes a claw pole type rotor 3 having a field winding 4, a stator 5 having a three-phase AC winding 6 formed by Y-connecting three-phase windings, a rectifier 7, This is an AC generator for a Landell vehicle equipped with Although not shown, the generator 2 is connected to a pulley fixed to the rotation shaft of the rotor 3 via a belt, and is driven by the rotational torque of the engine 1. .
The rectifier 7 is configured as a three-phase full-wave rectifier circuit including a diode bridge circuit in which three diode pairs formed by connecting two diodes 8 in series are connected in parallel.

  The power storage device 9 is a secondary battery such as a lead storage battery or a nickel / cadmium storage battery, and constitutes a low-voltage in-vehicle power source of, for example, 14 V (rated voltage). And the electrical storage apparatus 9 is connected to the load side wiring 13 connected to the output terminal 20b of the power converter device 20. FIG. In addition, the power storage device 9 is connected to the positive output terminal 7 a of the rectifier 7 via the power conversion device 20 and the generator wiring 12. The in-vehicle load 10 is an electric device such as an air conditioner or an audio device mounted on the vehicle, and is connected to the load side wiring 13 and driven by the power storage device 9.

  In the power converter 20, the input terminal 20a is connected to the positive output terminal 7a of the rectifier 7 via the generator side wiring 12, the output terminal 20b is connected to the power storage device 9 via the load side wiring 13, and the output terminal 20 c is connected to the field winding 4 of the rotor 3 through the wiring 14. The power conversion device 20 controls the energization of the field winding 4 and the voltage conversion circuit 20X that converts the power generation voltage of the generator 2 input from the input terminal 20a into a different voltage value and outputs it from the output terminal 20b. A field energizing circuit 20Y.

  As the voltage conversion circuit 20X, a constant voltage control type DC / DC converter that is feedback-controlled so as to keep the voltage of the input terminal 20a at the target voltage is used. This DC / DC converter is a general step-up / step-down chopper circuit composed of switching elements Q1 to Q4 such as MOSFETs, a free-wheeling diode, an inductor L, and capacitors C1 and C2. The field energizing circuit 20Y only needs to be able to turn on / off the energization of the field winding 4, and is configured by interposing a switching element Q5 such as a MOSFET in the wiring 15 that connects the output terminal 20b and the output terminal 20c. The The operations of the switching elements Q1 to Q5 are controlled by the control circuit 11 based on the rotation speed n of the generator 2, the voltage Va of the generator side wiring 12, the voltage Vb of the load side wiring 13, and the like.

Next, the operation of the generator 2 will be described.
A field current is supplied to the field winding 4 of the rotor 3 to generate a magnetic flux. Thereby, the N pole and the S pole are alternately formed on the outer peripheral portion of the rotor 3 in the circumferential direction. Then, the rotational torque of the engine 1 is transmitted to the rotating shaft of the rotor 3, and the rotor 3 is rotationally driven. Therefore, a rotating magnetic field is applied to the three-phase AC winding 6 of the stator 5, and an electromotive force is induced in the three-phase AC winding 6. The alternating current generated by the alternating electromotive force is rectified by the rectifier 7 and output.

Here, if the field current supplied to the field winding 4 is constant, the power generated by the generator 2 increases as the rotational speed of the rotor 3 increases. As the generated power rises, the current flowing through the three-phase AC winding 6 increases, and heat generation at the three-phase AC winding 6 increases. Further, the field energization circuit 20Y is turned on by the field energization circuit 20Y, so that the voltage of the power storage device 9 is applied to the field winding 4 and is determined from the voltage and the resistance value of the field winding 4. A direct current (field current) is applied.
Since the amount of heat generated in the three-phase AC winding 6 depends on the current value flowing through the three-phase AC winding 6, in order to obtain a large amount of power while suppressing the amount of power generated in the three-phase AC winding 6, output current It is desirable to increase the generated voltage while leaving Further, by increasing the generated voltage and reducing the output current, the copper loss in the three-phase AC winding 6 and the commutator loss in the rectifier 7 can be reduced, and the overall loss is reduced to generate power. Efficiency can be improved and large electric power can be obtained.

  Here, the field current applied to the field winding 4 is constant, the number of revolutions of the generator 2 (number of revolutions of the rotor 3) is changed, and the generated voltage is set to a predetermined voltage (6V to 29V). The results of measuring the generated power at that time are shown in FIG. In FIG. 3, the vertical axis represents the generated power, and the horizontal axis represents the number of rotations of the generator. The generated voltage is an output voltage at the positive output terminal 7 a of the rectifier 7.

As can be seen from FIG. 3, the higher the generated voltage, the greater the generated power in the high rotation range. It can also be seen that when the power generation voltage is a low voltage, for example, 6 V, it is possible to generate power even in a low rotation region that could not be generated.
The map of the generated voltage, generated power, and rotation speed shown in FIG. 3 is stored in a memory (not shown). The control circuit 11 controls the operation of the switching elements Q1 to Q4 of the voltage conversion circuit 20X with reference to the map stored in the memory.

Next, the operation of the vehicle power supply system will be described.
The control circuit 11 monitors the voltage Vb of the load side wiring 13 and determines whether or not the power storage device 9 needs to be charged from the voltage Vb. When the voltage Vb decreases and it is determined that the power storage device 9 needs to be charged, the control circuit 11 takes in the rotational speed n of the generator 2 and determines that the generated power is maximum based on the map stored in the memory. Is set as the target voltage. Next, the control circuit 11 turns on the switching element Q5 of the field energization circuit 20Y to supply a field current to the field winding 4, and starts power generation by the generator 2. At the same time, the control circuit 11 turns on / off the switching elements Q1 to Q4 so that the voltage Va of the generator-side wiring 12 becomes the set target voltage, that is, feedback-controls the voltage conversion circuit 20X. And if the electrical storage apparatus 9 is fully charged, the switching elements Q1-Q5 will be turned off and the electric power generation by the generator 2 will be complete | finished.

  Here, the generator 2, the rectifier 7, and the voltage conversion circuit 20 </ b> X are connected to the generator-side wiring 12. The voltage conversion circuit 20X is a constant voltage control type DC / DC converter capable of maintaining the voltage of the input terminal 20a at a target voltage. Considering (change in input voltage) / (conversion of input current) as the input impedance of the DC / DC converter, the voltage conversion circuit 20X tries to keep the input impedance constant regardless of the current. / DC converter. That is, the internal impedance of the generator 2 and the rectifier 7 is sufficiently higher than that of the voltage conversion circuit 20X. Therefore, the voltage Va of the generator-side wiring 12, that is, the generated voltage of the generator 2, can be set to a predetermined value only by controlling the voltage conversion circuit 20X having the lowest input impedance. That is, the voltage Va of the generator side wiring 12 can be maintained at the target voltage by controlling the voltage conversion circuit 20X by the control circuit 11.

  According to the first embodiment, the power storage device 9 is connected to the positive output terminal 7a of the rectifier 7 that rectifies the output current of the generator 2 via the voltage conversion circuit 20X. The life of the power storage device 9 is not reduced even if the power supply is greatly changed. Therefore, when the number of revolutions of the generator 2 is large, the generated power can be increased by increasing the generated voltage of the generator 2, so that the charging time of the power storage device 9 can be shortened and the amount of charge can be greatly increased. it can. Further, when the rotational speed of the generator 2 is small, the power storage device 9 can be charged by generating power by lowering the generated voltage of the generator 2. In this way, the braking energy of the vehicle can be recovered efficiently. As a result, the operation of causing the generator 2 to generate power during non-deceleration and charging the power storage device 9 can be reduced, the load on the engine 1 during non-deceleration can be reduced, and the fuel consumption of the vehicle can be improved.

  Further, since the control circuit 11 feedback-controls the voltage conversion circuit 20X so that the power generation voltage of the generator 2 becomes the set target voltage, the field current is controlled by the duty ratio that turns on / off the switching element Q5. There is no need to do. That is, during the power generation operation of the generator 2, the switching element Q5 of the field energization circuit 20Y may be turned on, the control of the field current is simplified, and the configuration of the control circuit 11 is simplified.

Further, since the electric power of the power storage device 9 is supplied to the field winding 4 via the field energization circuit 20Y, the field winding 4 is not affected by the change in the power generation voltage (target voltage) of the generator 2. Can supply power.
In addition, since the field energization circuit 20Y is incorporated in the power conversion device 20 together with the voltage conversion circuit 20X, the control of the amount of power generated by the generator 2 can be centralized in the power conversion device 20. Further, since the voltage conversion circuit 20X and the field energization circuit 20Y are not built in the generator 2, the installation space for the rectifier 7 in the generator 2 is increased, the cooling section of the rectifier 7 can be enlarged, and the rectifier 7 is cooled. Is improved.

In the first embodiment, the target voltage of the power generation voltage of the generator 2 is set based on the number of rotations of the power generator 2 in response to the charge request to the power storage device 9. The request is not limited to a charge request to the power storage device 9 but may be a load power request for supplying power to the in-vehicle load 10.
In the first embodiment, the rotation sensor is attached to the generator 2 and the rotation speed n of the rotor 3 is directly detected. However, the rotation speed of the rotor 3 depends on the rotation speed of the engine 1 and the pulley ratio ( (Power transmission ratio).

Embodiment 2. FIG.
FIG. 4 is a schematic configuration diagram of a vehicle power supply system according to Embodiment 2 of the present invention.

  4, the DC / DC converter 21 and the auxiliary power storage device 22 are connected in series between the generator-side wiring 12 that connects the positive-side output terminal 7a and the input terminal 20a of the voltage conversion device 20 and the ground. . Then, the DC / DC converter 21 is controlled by the control circuit 11 together with the power converter 20, and converts the voltage of the generator-side wiring 12 into a different voltage value and outputs it.

As the DC / DC converter 21, a constant current control type DC / DC converter is used that maintains a current flowing through the auxiliary power storage device 22 at a predetermined target current. Further, since DC / DC converter 21 needs to perform both charging and discharging operations on auxiliary power storage device 22, a bidirectional DC / DC converter that can reverse the input / output direction is used. As such a bidirectional constant current control type DC / DC converter, a step-up / step-down chopper circuit that is feedback-controlled so as to keep the current of the auxiliary power storage device 22 at a target current is used. The auxiliary power storage device 22 has better discharge characteristics than the power storage device 9, and for example, an electric double layer capacitor or a lithium ion capacitor is used.
The vehicle power supply system according to the second embodiment is configured in the same manner as the vehicle power supply system according to the first embodiment, except that a DC / DC converter 21 and an auxiliary power storage device 22 are provided.

  In the vehicle power supply system configured as described above, the control circuit 11 increases the generated power of the generator 2 when the vehicle is decelerated, and charges the power storage device 9 via the voltage conversion circuit 20X. Power is stored in the auxiliary power storage device 22 via the DC converter 21. Thereby, when the power storage device 9 is sufficiently charged or when the power generation amount of the generator 2 is excessively increased, the generated power of the generator 2 can be stored in the auxiliary power storage device 22. Therefore, when the vehicle is not decelerated (acceleration and cruise), the power stored in the auxiliary power storage device 22 is discharged, so that the time for stopping the power generation of the generator 2 during non-deceleration can be extended. The load on the engine 1 during non-deceleration is reduced, and the fuel consumption of the vehicle can be further improved.

Since the DC / DC converter 21 acts to keep the input current constant regardless of the voltage, it can be regarded as a DC / DC converter having a high input impedance. Therefore, the DC / DC converter 21 does not affect the operation of the voltage conversion circuit 20X that attempts to keep the voltage Va of the generator-side wiring 12 at the target voltage.
The control circuit 11 monitors the terminal voltage Vc of the auxiliary power storage device 22 and controls the operation of the DC / DC converter 21 so that the auxiliary power storage device 22 is not overcharged.

In each of the above embodiments, a vehicle AC generator is used as the generator. However, the generator is not limited to the vehicle AC generator, and a vehicle generator motor may be used.
In each of the above embodiments, the rectifier is configured as a three-phase full-wave rectifier circuit using a diode bridge. However, the rectifier may be a MOSFET that performs synchronous rectification or a MOSFET that performs rectification using a parasitic diode. You may comprise with a polyphase inverter.
Moreover, in each said embodiment, although the rectifier shall be incorporated in the generator, a rectifier may be comprised separately from a generator.

Further, in each of the above embodiments, the stator winding of the stator of the generator is configured as a three-phase AC winding, but the stator winding is limited to a three-phase AC winding. Instead, a multi-phase AC winding or a multi-phase AC winding (for example, 5-phase, 7-phase) may be used. In that case, the rectifier rectifies AC power into DC with a full-wave rectifier circuit according to the number of phases.
In each of the above embodiments, the three-phase AC winding is configured by Y-connecting the three-phase winding, but the three-phase AC winding is Δ-connected to the three-phase winding. It may be configured.

  In each of the above embodiments, a claw pole type rotor having only field windings as field means is used as the generator rotor. However, the rotor is not limited to the field windings. Thus, a claw pole type rotor having a permanent magnet as a field means may be used. In this case, the field winding is not energized, and the target voltage of the generated voltage that is the maximum generated power is set according to the number of revolutions of the generator, and power is generated only with the rotor magnetic flux of the permanent magnet. Can generate electricity. Further, if the field winding is energized, the field winding and the permanent magnet are used together as the field means, and the amount of power generation can be increased as compared with the case where the field means is only the field winding.

  DESCRIPTION OF SYMBOLS 1 Engine, 2 Generator, 4 Field winding, 7 Rectifier, 7a Positive side output terminal, 9 Power storage device, 10 Car load, 11 Control circuit, 12 Generator side wiring, 13 Load side wiring, 20X Power conversion circuit, 20Y Field energization circuit, 21 Bidirectional constant current control type DC / DC converter, 22 Auxiliary power storage device.

Claims (4)

A generator having a field winding and driven by an engine to generate AC power;
A rectifier that rectifies and outputs AC power generated by the generator to DC power;
A power conversion circuit that is connected to the positive output terminal of the rectifier via a generator-side wiring, converts the output voltage of the rectifier to a different voltage value, and outputs it;
An in-vehicle load connected to the power conversion circuit via a load-side wiring;
A power storage device connected to the power conversion circuit via the load-side wiring and supplying power to the in-vehicle load;
A field energization circuit for supplying a field current determined by a voltage of the power storage device and a resistance value of the field winding to the field winding ;
A drive circuit that controls driving of the power conversion circuit and the field energization circuit, and feeds power generated by the generator to the power storage device and the on-vehicle load.
The power conversion circuit includes a constant voltage control type DC / DC converter,
In response to the power demand on the load side, the control circuit turns on the field energizing circuit to place the generator in a power generation state , keeps the field energizing circuit on until the end of power generation, and rotates the generator A target voltage for obtaining the maximum generated power is set according to the number, and the power conversion circuit is driven and controlled so that the voltage of the generator-side wiring becomes the target voltage. Power supply system for vehicles. The vehicle power supply system according to claim 1, wherein the power conversion circuit and the field energization circuit are installed outside the generator. A bidirectional constant current control type DC / DC converter connected to the generator-side wiring;
An auxiliary power storage device connected to the generator-side wiring via the bidirectional constant current control type DC / DC converter,
The control circuit drives and controls the bidirectional constant current control type DC / DC converter so that the power generated by the generator is stored in the auxiliary power storage device, and the power stored in the auxiliary power storage device is stored. 3. The vehicle power supply system according to claim 1, wherein the vehicle power supply system is configured to be discharged. The generator, in addition to the above field winding, a power supply system for a vehicle according to any one of claims 1 to 3, characterized in that it comprises a permanent magnet as a field means.

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