JP5345173B2 - Vehicle power supply - Google Patents

Description

  The present invention relates to a vehicle power supply device that has a plurality of power storage devices and performs power transfer with an electric motor mounted on a vehicle via an inverter device.

  In recent years, electric vehicles, hybrid vehicles, plug-in hybrid vehicles, and the like that use an electric motor as a drive source have attracted attention as vehicles that take environmental issues into consideration. These vehicles are equipped with a power storage device such as a secondary battery or an electric double layer capacitor for supplying electric power to an electric motor or converting kinetic energy into electric energy to store electric power during deceleration. .

  By the way, a general electric vehicle has a problem that a distance that can be continued continuously (hereinafter referred to as a cruising distance) is shorter than a vehicle equipped with a gasoline engine or a diesel engine.

  To solve this problem, in an electric vehicle having a plurality of power storage devices of a battery and a large-capacitance capacitor, it is possible to continue by switching to an appropriate mode according to the running state of the electric vehicle and increasing the utilization rate of the large-capacity capacitor An electric vehicle power supply device that extends the possible distance has been proposed (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 7-231511

  In the conventional device as shown in Patent Document 1, a large-capacity capacitor can be charged from a battery via a chopper due to its structure. However, in order to discharge from the large-capacity capacitor, power must be supplied to the inverter. That is, if there is no load, it is impossible to discharge from the large-capacity capacitor, and the charge amount of the large-capacity capacitor cannot be controlled arbitrarily. For this reason, for example, when the large-capacity capacitor is fully charged when the vehicle is decelerated, the energy cannot be regenerated on the large-capacitance capacitor side, and the energy is regenerated on the battery side. As a result, there is a problem that the battery current is increased, the internal loss of the battery is increased, and the cruising distance is shortened.

  The present invention has been made to solve the above-described problems, and provides a power supply device for a vehicle that can efficiently regenerate energy and extend the cruising range of the vehicle. Objective.

The vehicle power supply device according to the present invention is a vehicle power supply device that performs power transfer with an electric motor mounted on a vehicle via an inverter device, and is connected to the inverter device via a first switch. A first power storage device, a second power storage device connected to the inverter device via a second switch and having input / output characteristics different from the first power storage device, the first switch, and the second switch Power control means for controlling opening and closing of the first switch and the second switch so that when one of the switches is open, the other is closed; and the first power storage device And the voltage or current output from one of the first power storage device and the second power storage device is converted into a voltage or current having a different magnitude. The above Output to the other side of the first power storage device and the second power storage device, an output conversion device capable of switching the output direction of the voltage or current of the output conversion device according to the input command, and the output conversion device Output control means for sending a command and controlling the output direction and output voltage or output current of the output conversion device; requested load calculation means for calculating a load required by the driver of the vehicle and outputting a requested load amount; And a voltage detection means for detecting the voltage of the second power storage device , wherein the power supply control means determines the first switch according to the required load amount and the voltage of the second power storage device. Each of the second switches, and the output control means controls the output direction and output voltage or output of the output converter according to the required load amount and the voltage of the second power storage device. Current When the required load amount is smaller than a predetermined load amount threshold value and the voltage of the second power storage device is within a predetermined range, the power supply control means sets the first switch to The output control means performs control to open and close the second switch, and the output control means outputs the output so that a voltage or current output direction is a direction from the first power storage device side to the second power storage device side. The output control unit controls the output conversion device such that the output voltage from the first power storage device side to the second power storage device side decreases as the required load amount decreases. To do .

The vehicle power supply device according to the present invention is a vehicle power supply device that performs power transfer with an electric motor mounted on a vehicle via an inverter device, and is connected to the inverter device via a first switch. A first power storage device, a second power storage device connected to the inverter device via a second switch and having input / output characteristics different from the first power storage device, the first switch, and the second switch Power control means for controlling opening and closing of the first switch and the second switch so that when one of the switches is open, the other is closed; and the first power storage device And the voltage or current output from one of the first power storage device and the second power storage device is converted into a voltage or current having a different magnitude. The above Output to the other side of the first power storage device and the second power storage device, an output conversion device capable of switching the output direction of the voltage or current of the output conversion device according to the input command, and the output conversion device Output control means for sending a command and controlling the output direction and output voltage or output current of the output conversion device; requested load calculation means for calculating a load required by the driver of the vehicle and outputting a requested load amount; And a voltage detection means for detecting the voltage of the second power storage device, wherein the power supply control means determines the first switch according to the required load amount and the voltage of the second power storage device. Each of the second switches, and the output control means controls the output direction and output voltage or output of the output converter according to the required load amount and the voltage of the second power storage device. Current When the required load amount is smaller than a predetermined load amount threshold value and the voltage of the second power storage device is within a predetermined range, the power supply control means sets the first switch to The output control means performs control to open and close the second switch, and the output control means outputs the output so that a voltage or current output direction is a direction from the first power storage device side to the second power storage device side. The output control unit controls the output conversion device such that the output voltage from the first power storage device side to the second power storage device side decreases as the required load amount decreases. Therefore, even if there is no load, it can be discharged from the second power storage device side to the first power storage device side, and the charge amount of the second power storage device can be arbitrarily controlled, so that energy can be saved. Can regenerate efficiently, Since energy can be used effectively, the cruising range of the vehicle can be extended.

It is a block diagram which shows the vehicle power supply device by Embodiment 1 of this invention. It is a circuit diagram which shows the output converter of FIG. It is a flowchart which shows operation | movement of the controller of FIG. 6 is a graph showing an example of a relationship between a target voltage Vt and a required load amount L. It is a graph which shows an example of the magnitude | size of the load of a motor, and the relationship between the inverter applied voltage that the loss generate | occur | produced in a motor and an inverter apparatus becomes the minimum.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
Embodiment 1 FIG.
1 is a block diagram showing a power supply device for a vehicle according to Embodiment 1 of the present invention.
In FIG. 1, an inverter device 3 is connected to a motor (for example, a permanent magnet type AC synchronous motor) 2 as an electric motor mounted on a vehicle 1. A first power storage device 5 is connected to an input terminal of the inverter device 3 via a first switch 4, and a second power storage device 7 is connected via a second switch 6.

  Here, in Embodiment 1, a 400 V lithium ion battery (hereinafter referred to as LIB (Lithium Ion Battery)) is used as the first power storage device 5 and an electric double layer capacitor (hereinafter referred to as EDLC) having a withstand voltage of 200 V. (Electric Double Layer Capacitor) is assumed to be used as the second power storage device 7. However, the power storage device and the voltage value to be used are not limited to this, and other types of power storage devices may be used.

  The output converter 8 is connected in parallel between the output terminals of the LIB 5 and the EDLC 7. The output converter 8 has a circuit configuration as shown in FIG. 2, for example. The output converter 8 converts the voltage or current output from the LIB 5 into a voltage or current having a different magnitude and outputs it to the EDLC 7 side, and outputs from the EDLC 7. The voltage or current to be converted into a voltage or current of a different magnitude and output to the LIB 5 side. Further, the output conversion device 8 can switch the output direction of voltage or current, that is, the output direction from one side of the LIB 5 and the EDLC 7 to the other side in accordance with the input command.

  The first switch 4, the second switch 6, and the output conversion device 8 each operate in response to a command from the controller 9. The controller 9 has power supply control means 10, output control means 11, and required load calculation means (not shown). The power supply control means 10 and the output control means 11 monitor changes in the voltage of the EDLC 7 via the voltage sensor 12 as voltage detection means.

  The power supply control means 10 controls the opening and closing of the first switch 4 and the second switch 6 based on the required load amount from the required load calculating means and the voltage of the EDLC 7. Here, when one of the first switch 4 and the second switch 6 is in the open state, the power supply control means 10 performs control so that the other is in the closed state (controlled exclusively). The output control means 11 controls on / off of the switching elements Q1 and Q2 in FIG. 2 based on the required load amount from the required load calculating means and the voltage of the EDLC 7, and the output direction of the output converter 8 and the output Control voltage or output current.

  Next, the operation will be described. The controller 9 of the vehicle power supply device shown in FIG. 1 includes first to first states corresponding to the open / close state of the first switch 4, the open / close state of the second switch 6, and the output direction (conversion direction) of the output conversion device 8. It has at least three control modes of three control modes. The controller 9 can alternatively select the first to third control modes.

  The first control mode is a control mode in which power is supplied from the LIB 5 to the motor 2 through the first switch 4 and from the LIB 5 to the EDLC 7 through the output converter 8. In the first control mode, the first switch 4 is turned on, the second switch 6 is turned off, and the output direction of the output converter 8 is set to the direction LIB5 → EDLC7.

  The second control mode is a control mode in which power is supplied from the LIB 5 to the motor 2 via the first switch 4 and also supplied from the EDLC 7 to the LIB 5 or the motor 2 via the output converter 8. In the second control mode, the first switch 4 is turned on, the second switch 6 is turned off, and the output direction of the output converter 8 is set to the direction of EDLC7 → LIB5.

  The third control mode is a control mode in which power is supplied to at least the motor 2 from the LIB 5 via the output converter 8. In the third control mode, the first switch 4 is turned off, the second switch 6 is turned on, and the output direction of the output converter 8 is set to the direction LIB5 → EDLC7.

  Next, FIG. 3 is a flowchart showing the operation of the controller 9 of FIG. In FIG. 3, in step S <b> 101, the controller 9 acquires a required load amount L that is a driver's required load calculated by a required load calculating means (not shown). The driver's required load can be calculated from, for example, the amount of depression of an accelerator pedal (not shown) mounted on the vehicle and the vehicle speed.

In step S102, the controller 9 acquires the detected voltage Vc of the EDLC 7. In step S103, the controller 9 calculates the target voltage Vt of the output converter 8. The target voltage Vt can be calculated as shown in the following equation (1) based on the required load amount L acquired in step S101, for example.
Vt = f (L) (1)

  Here, an example of the relationship between the target voltage Vt and the required load L is shown in FIG. Symbols V1 and V2 in FIG. 4 are the minimum value and the maximum value of the working voltage range of the EDLC 7, respectively. For example, V1 is determined from the upper limit value of the current that can flow from the EDLC 7 to the output conversion device 8. V2 is generally equal to the withstand voltage, and is set to 200 V, for example, in this apparatus. The target voltage Vt of the output converter 8 increases as the required load amount L increases.

  The reason for this calculation is that when the load is low, the loss generated in the motor 2 and the inverter device 3 becomes lower as the applied voltage to the inverter device 3 is lower. FIG. 5 shows an example of the relationship between the magnitude of the load of the motor 2 and the inverter applied voltage at which the loss generated in the motor 2 and the inverter device 3 is minimized.

  Returning to FIG. 3, in step S <b> 104, the controller 9 calculates a voltage determination value Vh. Here, the voltage determination value Vh is used to determine whether or not the voltage Vc of the EDLC 7 is within a predetermined range, that is, whether or not Vt ≦ Vc ≦ Vh, so that the voltage determination value Vh is larger than the target voltage Vt. Calculated.

  Thereafter, in step S105, the controller 9 determines whether or not the required load amount L acquired in step S101 is larger than a predetermined value (predetermined load amount threshold) Lt. This predetermined value Lt is set as L2 or more shown in FIG. 4, for example. In step S105, when the required load amount L is larger than the predetermined value Lt, the controller 9 proceeds to step S106, and when the required load amount L is equal to or smaller than the predetermined value Lt, the controller 9 proceeds to step S107.

  In step S106, the controller 9 determines whether or not the voltage Vc of the EDLC 7 is smaller than the target voltage Vt. At this time, if the voltage Vc of the EDLC 7 is smaller than the target voltage Vt, the controller 9 proceeds to step S109 and selects the first control mode. On the other hand, if the voltage Vc of the EDLC 7 is equal to or higher than the target voltage Vt in step S106, the controller 9 proceeds to step S110 and selects the second control mode.

  In step S105, when the required load amount L is equal to or less than the predetermined value Lt, the controller 9 proceeds to step S107 and determines whether or not the voltage Vc of the EDLC 7 is smaller than the target voltage Vt. At this time, if the voltage Vc of the EDLC 7 is smaller than the target voltage Vt, the controller 9 proceeds to step S109 and selects the first control mode. On the other hand, if the voltage Vc of the EDLC 7 is equal to or higher than the target voltage Vt, the controller 9 proceeds to step S108.

  In step S108, the controller 9 determines whether or not the voltage Vc of the EDLC 7 is greater than the voltage determination value Vh. When the voltage Vc of the EDLC 7 is larger than the voltage determination value Vh, the controller 9 proceeds to step S110 and selects the second control mode.

  That is, in the second control mode, the required load amount L is equal to or less than the predetermined value Lt and the voltage Vc of the EDLC 7 is larger than the voltage determination value (upper limit value of the predetermined range) Vh, or the required load amount L is the predetermined value. This is selected when it is larger than Lt and the voltage Vc of the EDLC 7 is larger than the target voltage (lower limit value of the predetermined range) Vt.

  On the other hand, when the voltage Vc of the EDLC 7 is equal to or lower than the voltage determination value Vh in step S108, the controller 9 proceeds to step S111 and selects the third control mode. That is, the third control mode is selected when the required load amount L is smaller than a predetermined value (predetermined load amount threshold) Lt and Vt ≦ Vc ≦ Vh is satisfied. When the controller 9 selects the control mode, the controller 9 repeatedly performs the operation shown in FIG.

  According to the first embodiment as described above, since the output conversion device 8 has a function of outputting a voltage or current from the EDLC 7 to the LIB 5, it is possible to discharge from the EDLC 7 to the LIB 5 even when there is no load. Yes (second control mode). Thereby, since the controller 9 can control arbitrarily the charge amount of EDLC7, energy can be regenerated efficiently and energy can be used effectively. As a result, the cruising distance of the vehicle 1 can be extended.

Here, in the conventional device as shown in Patent Document 1, in order to increase the utilization rate of the large-capacity capacitor, the battery and the large-capacitance capacitor are used in the running state of the vehicle that becomes a heavy load when climbing or accelerating. At the same time, power is supplied to the motor. At this time, since the switch is switched so that the battery and the large-capacity capacitor are connected in parallel, the voltage of the large-capacitance capacitor must be larger than a predetermined value in order to prevent inrush current from the battery to the large-capacity capacitor. When the voltage of the capacitor is low, electric power cannot be supplied from the large-capacity capacitor to the motor, and the utilization factor of the large-capacity capacitor is lowered, that is, the cruising distance of the vehicle is shortened.
In contrast, in the first embodiment, since the output conversion device 8 has a function of outputting a voltage or current from the EDLC 7 to the LIB 5, in a traveling state where the load is high, such as during climbing or acceleration, Regardless of the amount of charge of the EDLC 7, it is also possible to supply power to the motor 2 via the output converter 8 (second control mode). Thereby, the utilization factor of EDLC7 can be increased and, as a result, the cruising range of the vehicle 1 can be further extended.

Moreover, in the conventional apparatus as shown in Patent Document 1, in order to prevent an overvoltage failure of the large-capacity capacitor, the withstand voltage of the large-capacity capacitor needs to be set to the maximum value in the operating voltage range of the battery. There was also a problem that it would be expensive.
On the other hand, in the first embodiment, even when the voltage of the EDLC 7 is low, the motor 2 can be supplied with power from the EDLC 7 via the output converter 8 in a traveling state where the load is high, such as when climbing or accelerating. Therefore, the withstand voltage of the EDLC 7 can be made lower than the minimum value of the working voltage range of the LIB 5, and the manufacturing cost of the EDLC 7 can be reduced.

Furthermore, in the conventional device as shown in Patent Document 1, the operation is performed so as to reduce the internal loss of the battery, but the loss of the motor and the inverter device is not taken into consideration. For this reason, the loss of the motor and the inverter device generated when the vehicle travels cannot be reduced, and there is a problem that the cruising distance of the vehicle cannot be sufficiently extended.
On the other hand, in the first embodiment, the output control unit 11 sets and controls the target voltage of the output converter 8 so that the voltage of the EDLC 7 becomes lower as the required load amount is smaller (third control). mode). Thereby, the loss of the motor 2 and the inverter apparatus 3 which generate | occur | produces at the time of vehicle travel can be reduced, and the cruising range of the vehicle 1 can be extended more.

  In the first embodiment, the target voltage Vt of the output converter 8 is calculated based only on the required load amount in step S103. However, the calculation is not limited to this example. For example, the calculation may be performed in consideration of the vehicle speed VEL, the road gradient θ, the temperature T of the LIB 5, the SOC (charge amount) of the LIB 5, and the like. Here, in general, in order to increase the utilization rate of the EDLC 7, the target voltage Vt is decreased as the vehicle speed increases, the target voltage Vt is decreased as the downhill road gradient increases, and the temperature of the LIB 5 decreases. It is known that the target voltage Vt is increased, and the target voltage Vt is increased as the SOC of the LIB 5 is decreased. It goes without saying that the effect can be obtained by adding the element of the required load amount L to these to calculate the target voltage Vt and controlling the output voltage of the output converter 8 to be the target voltage Vt.

  In the first embodiment, the hardware (calculation means, storage means, signal input / output means) of the controller 9 having the same functions of the power supply control means 10, the output control means 11, and the required load calculation means (not shown). Hardware). However, the present invention is not limited to this example, and the functions of the power supply control means, the output control means, and the required load calculation means may be realized by hardware of different controllers.

  Further, in the first embodiment, the controller 9 is configured to automatically select the control mode of the output conversion device 8. However, the selection of the control mode of the output conversion device 8 may be performed manually by the driver of the vehicle.

  In FIG. 1, the first switch 4 and the second switch 6 are represented by mechanical switch symbols, but may be configured by a switching element such as a MOS-FET or an IGBT.

  Furthermore, the switching elements used as the first switch 4 and the second switch 6 may be formed of a wide band gap semiconductor having a larger band gap than silicon. Examples of the wide band gap semiconductor include silicon carbide (SiC), a gallium nitride material, and diamond. A switching element formed of such a wide band gap semiconductor has a high voltage resistance and a high allowable current density. For this reason, it is possible to reduce the size of the switching element, and by using these reduced switching elements, it is possible to reduce the size of a power supply device for a vehicle incorporating these elements.

  In addition, since the wide band gap semiconductor has high heat resistance, it is possible to reduce the size of the heat dissipating fins of the heat sink and the air cooling of the water-cooled portion, thereby further reducing the size of the vehicle power supply device. Furthermore, since the power loss is low, it is possible to increase the efficiency of the switching element, and thus to increase the efficiency of the vehicle power supply device.

  DESCRIPTION OF SYMBOLS 1 Vehicle, 2 Motor (electric motor), 3 Inverter apparatus, 4 1st switch, 5 1st electrical storage apparatus and LIB, 6 2nd switch, 7 2nd electrical storage apparatus and EDLC, 8 Output converter, 9 Controller 10 power control means, 11 output control means, 12 voltage sensor (voltage detection means).

Claims (4)

A vehicle power supply device that performs power transfer with an electric motor mounted on a vehicle via an inverter device,
A first power storage device connected to the inverter device via a first switch;
A second power storage device connected to the inverter device via a second switch and having an input / output characteristic different from that of the first power storage device;
Power supply control for controlling opening and closing of the first switch and the second switch so that when one of the first switch and the second switch is open, the other is closed Means,
Voltages or currents connected to both the first power storage device and the second power storage device and output from one of the first power storage device and the second power storage device are voltages having different magnitudes. Alternatively, the output is converted into current and output to the other side of the first power storage device and the second power storage device, and the output of the output conversion device can be switched according to the input command. A conversion device;
An output control means for sending a command to the output converter and controlling an output direction and an output voltage or output current of the output converter ;
A required load calculating means for calculating a load required by a driver of the vehicle and outputting a required load amount;
Voltage detecting means for detecting the voltage of the second power storage device ,
The power control means controls the opening and closing of the first switch and the second switch according to the required load amount and the voltage of the second power storage device,
The output control means controls the output direction and output voltage or output current of the output converter according to the required load amount and the voltage of the second power storage device,
When the required load amount is smaller than a predetermined load amount threshold and the voltage of the second power storage device is within a predetermined range,
The power control means performs control to open the first switch and close the second switch,
The output control means controls the output conversion device so that an output direction of voltage or current is a direction from the first power storage device side to the second power storage device side,
The output control means controls the output conversion device such that an output voltage from the first power storage device side to the second power storage device side becomes lower as the required load amount is smaller. Vehicle power supply device. When the voltage of the second power storage device is larger than the upper threshold value of the predetermined range,
The power control means performs control to close the first switch and open the second switch,
Said output control means according to claim wherein the controller controls the output conversion device such that the direction from the output direction of the voltage or current the second power storage device side to the first power storage device side 1 the power supply device according to. The vehicle power supply device according to claim 1 or 2 , wherein a withstand voltage of the second power storage device is lower than a minimum value of a working voltage range of the first power storage device. The vehicle according to any one of claims 1 to 3, wherein at least one of the first switch and the second switch is a switching element made of a wide bandgap semiconductor. Power supply.

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